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+[{"text": "[SQUEAKING]\n[RUSTLING] [CLICKING]", "start": 0.0, "duration": 15.08}, {"text": "JOHN DOLHUN: Good\nafternoon, everyone.", "start": 15.08, "duration": 2.32}, {"text": "Welcome to The Ellen Swallow\nRichards lab part two.", "start": 17.4, "duration": 5.06}, {"text": "There is-- the room will\nbe a little bit more", "start": 22.46, "duration": 2.46}, {"text": "sparsely populated today.", "start": 24.92, "duration": 1.74}, {"text": "I wonder why.", "start": 26.66, "duration": 1.35}, {"text": "Lab reports are due, right?", "start": 28.01, "duration": 1.53}, {"text": "So we're going to get started.", "start": 32.479, "duration": 2.921}, {"text": "And I'm going to start off by\ntalking about probably the most", "start": 35.4, "duration": 5.57}, {"text": "important parameter in measuring\nthe health of the river,", "start": 40.97, "duration": 5.07}, {"text": "and that's the dissolved\noxygen. So when", "start": 46.04, "duration": 3.99}, {"text": "we look at the dissolved\noxygen concentrations", "start": 50.03, "duration": 4.05}, {"text": "out there, for a river\nto really be healthy,", "start": 54.08, "duration": 4.74}, {"text": "we're looking for something\ngreater than probably about 8", "start": 58.82, "duration": 3.88}, {"text": "PPM.", "start": 62.7, "duration": 0.5}, {"text": "If the concentrations\nfall down to 5 or less,", "start": 73.52, "duration": 4.44}, {"text": "then you'll start to see the\nfish move around erratically,", "start": 77.96, "duration": 3.66}, {"text": "because they're trying\nto get their oxygen.", "start": 81.62, "duration": 2.85}, {"text": "So less than or equal to\n5, and we have some stress", "start": 84.47, "duration": 9.48}, {"text": "placed on the aquatic life.", "start": 93.95, "duration": 2.25}, {"text": "If the dissolved\noxygen concentration", "start": 96.2, "duration": 2.43}, {"text": "goes below 2, even\nfor an hour or two,", "start": 98.63, "duration": 9.827}, {"text": "you're going to have fish kills.", "start": 108.457, "duration": 1.333}, {"text": "So let's take a\nmoment to actually see", "start": 117.07, "duration": 4.08}, {"text": "how this oxygen\ngets into the water,", "start": 121.15, "duration": 2.88}, {"text": "and this is the big picture.", "start": 124.03, "duration": 2.89}, {"text": "So if you look at this, you've\ngot two processes going on.", "start": 126.92, "duration": 4.43}, {"text": "You've got the oxygen coming\nin from the atmosphere,", "start": 131.35, "duration": 3.51}, {"text": "and it's diffusing\ninto the water system.", "start": 134.86, "duration": 3.75}, {"text": "You also have down below, you've\ngot aerobic biodegradation", "start": 138.61, "duration": 5.04}, {"text": "taking place.", "start": 143.65, "duration": 2.02}, {"text": "So we've got oxygen\ndiffusing into the water,", "start": 145.67, "duration": 13.16}, {"text": "and then we've got\naerobic biodegradation.", "start": 158.83, "duration": 7.37}, {"text": "These are the two main\nprocesses that are taking place,", "start": 171.28, "duration": 5.79}, {"text": "and both of these\nprocesses are going--", "start": 177.07, "duration": 4.53}, {"text": "they have different kinetics,\nyet they're coupled together,", "start": 181.6, "duration": 4.5}, {"text": "coupled in the sense that if\naerobic biodegradation uses up", "start": 186.1, "duration": 4.62}, {"text": "the oxygen, more oxygen\nwill start to dissolve in.", "start": 190.72, "duration": 4.68}, {"text": "There's a transfer\ndriving force that", "start": 195.4, "duration": 2.34}, {"text": "actually lets more oxygen\ndissolve into the water.", "start": 197.74, "duration": 2.76}, {"text": "The rate at which\noxygen is dissolving", "start": 203.85, "duration": 5.78}, {"text": "is actually proportional\nto the deficit of oxygen", "start": 209.63, "duration": 4.65}, {"text": "that's in the river.", "start": 214.28, "duration": 1.32}, {"text": "And that deficit is equal\nto the equilibrium level", "start": 222.49, "duration": 8.26}, {"text": "that we would expect\nminus the actual level", "start": 230.75, "duration": 4.5}, {"text": "that we actually find.", "start": 235.25, "duration": 1.5}, {"text": "So the amounts of oxygen\nthat we're talking about", "start": 246.34, "duration": 2.87}, {"text": "are very tiny.", "start": 249.21, "duration": 2.22}, {"text": "And there was a\nbrilliant chemist", "start": 251.43, "duration": 3.06}, {"text": "by the name of William Henry,\nwho actually, back in 1803,", "start": 254.49, "duration": 15.26}, {"text": "came out with Henry's Law.", "start": 269.75, "duration": 2.52}, {"text": "And what Henry's Law\nsays is very simple.", "start": 279.51, "duration": 5.17}, {"text": "The solubility of a dissolved\ngas in a body of water", "start": 284.68, "duration": 13.74}, {"text": "is proportional to\nthe partial pressure", "start": 298.42, "duration": 3.06}, {"text": "of that gas over the water.", "start": 301.48, "duration": 2.4}, {"text": "There's even a Henry's\nLaw constant here,", "start": 308.35, "duration": 2.67}, {"text": "and there are tables of these.", "start": 311.02, "duration": 2.73}, {"text": "There are thousands of them.", "start": 313.75, "duration": 1.53}, {"text": "For every solvent, for every\ngas, for every temperature", "start": 315.28, "duration": 4.23}, {"text": "combination that\nyou can think of,", "start": 319.51, "duration": 2.06}, {"text": "there is a Henry Law constant\nthat you can plug in.", "start": 321.57, "duration": 4.58}, {"text": "Let's think about, what\nis the partial pressure", "start": 326.15, "duration": 3.18}, {"text": "of oxygen on any given day?", "start": 329.33, "duration": 2.86}, {"text": "How do we calculate that?", "start": 332.19, "duration": 1.19}, {"text": "Yes, yeah.", "start": 344.1, "duration": 1.05}, {"text": "Alec.", "start": 345.15, "duration": 0.66}, {"text": "AUDIENCE: So if you\nhave total pressure,", "start": 345.81, "duration": 1.77}, {"text": "and then you know the\nmakeup of the atmosphere.", "start": 347.58, "duration": 2.34}, {"text": "You can just break it down.", "start": 349.92, "duration": 2.2}, {"text": "So say your pressure\nis 1 atmosphere", "start": 352.12, "duration": 2.08}, {"text": "and you have 20% oxygen in\nthe at-- that's not right.", "start": 354.2, "duration": 3.49}, {"text": "But 20% oxygen in\nthe atmosphere,", "start": 357.69, "duration": 2.22}, {"text": "your oxygen would be\ncontributing 0.20 atmospheres", "start": 359.91, "duration": 3.423}, {"text": "to the pressure [INAUDIBLE].", "start": 363.333, "duration": 1.167}, {"text": "JOHN DOLHUN: Very good.", "start": 364.5, "duration": 1.08}, {"text": "Very good, Alec.", "start": 365.58, "duration": 1.38}, {"text": "So Alec said that you've got\n20.9% oxygen in the atmosphere.", "start": 366.96, "duration": 5.38}, {"text": "So we can convert\nthat to a decimal.", "start": 372.34, "duration": 3.29}, {"text": "Partial pressure of\noxygen on any given day", "start": 375.63, "duration": 2.61}, {"text": "would be the percent\nof oxygen that's", "start": 378.24, "duration": 3.81}, {"text": "in the atmosphere times\nthe atmospheric pressure", "start": 382.05, "duration": 5.61}, {"text": "on that particular day minus\nthe pressure of the water vapor", "start": 387.66, "duration": 6.96}, {"text": "that we're talking about.", "start": 394.62, "duration": 2.44}, {"text": "So that gives us\na handle on this.", "start": 397.06, "duration": 5.315}, {"text": "I want to show you\nprobably the simplest", "start": 402.375, "duration": 2.565}, {"text": "example of Henry's Law.", "start": 404.94, "duration": 2.61}, {"text": "I brought a bottle of Coke\nhere, and these are hard, right,", "start": 407.55, "duration": 6.81}, {"text": "because they pack them--", "start": 414.36, "duration": 1.47}, {"text": "there's a head of carbon\ndioxide gas over the liquid.", "start": 415.83, "duration": 5.14}, {"text": "Now when I open this, I'm\ngoing to release the gas,", "start": 420.97, "duration": 3.15}, {"text": "so the partial pressure of\nCO2 over this liquid is gone.", "start": 424.12, "duration": 3.65}, {"text": "We should start to see bubbles\ncoming out of the solution,", "start": 427.77, "duration": 2.88}, {"text": "right?", "start": 430.65, "duration": 1.809}, {"text": "[HISSING]", "start": 432.459, "duration": 1.581}, {"text": "Oh good, it's not an\nexplosive one, so that's good.", "start": 434.04, "duration": 6.66}, {"text": "So there are the bubbles of\nthe dissolved carbon dioxide", "start": 440.7, "duration": 4.14}, {"text": "gas starting to come out.", "start": 444.84, "duration": 2.13}, {"text": "And that's a simple\nexample of Henry's Law.", "start": 446.97, "duration": 4.08}, {"text": "Can anybody think of a\nmore complex example?", "start": 451.05, "duration": 2.565}, {"text": "Anybody a diver here?", "start": 460.94, "duration": 4.54}, {"text": "Kelly, you're a diver?", "start": 465.48, "duration": 1.02}, {"text": "AUDIENCE: Oh, no,\nI'm just [INAUDIBLE]..", "start": 466.5, "duration": 1.667}, {"text": "JOHN DOLHUN: OK.", "start": 468.167, "duration": 1.813}, {"text": "When you--", "start": 469.98, "duration": 0.82}, {"text": "AUDIENCE: Yeah.", "start": 470.8, "duration": 1.43}, {"text": "It's like the bends, right?", "start": 472.23, "duration": 1.21}, {"text": "Because as you go down\nfurther, the pressure", "start": 473.44, "duration": 3.47}, {"text": "increases so that more nitrogen\ncan dissolve in your blood,", "start": 476.91, "duration": 6.65}, {"text": "you said?", "start": 483.56, "duration": 0.61}, {"text": "JOHN DOLHUN: Yeah, very good.", "start": 484.17, "duration": 1.29}, {"text": "Yeah, so you've got\ngases in your blood.", "start": 485.46, "duration": 2.255}, {"text": "And when you go\ndown, when you're", "start": 487.715, "duration": 1.375}, {"text": "diving down under\na great pressure,", "start": 489.09, "duration": 3.22}, {"text": "when you start your ascent,\nall of those gas bubbles", "start": 492.31, "duration": 5.28}, {"text": "are going to come out.", "start": 497.59, "duration": 1.62}, {"text": "And they have to go somewhere.", "start": 499.21, "duration": 1.26}, {"text": "They could migrate\nanywhere in your body,", "start": 500.47, "duration": 2.46}, {"text": "and it could cause a rash.", "start": 502.93, "duration": 3.16}, {"text": "It could cause some\ntype of joint pain.", "start": 506.09, "duration": 3.47}, {"text": "You could end up with\nparalysis, even death.", "start": 509.56, "duration": 3.28}, {"text": "So divers have to really,\nreally time their ascent.", "start": 512.84, "duration": 4.67}, {"text": "That there's a name for that.", "start": 517.51, "duration": 1.529}, {"text": "Kelly said the bends.", "start": 519.039, "duration": 1.651}, {"text": "That's one of the names.", "start": 520.69, "duration": 1.504}, {"text": "It's also called DCS,\nDecompression Sickness.", "start": 525.62, "duration": 4.995}, {"text": "That's a great example\nof Henry's Law.", "start": 542.41, "duration": 4.65}, {"text": "What about if we think about\ntemperature and dissolved", "start": 547.06, "duration": 5.31}, {"text": "oxygen?", "start": 552.37, "duration": 1.47}, {"text": "Let's actually take\na look at that.", "start": 553.84, "duration": 2.07}, {"text": "Here is a graph of oxygen\nconcentration and temperature.", "start": 560.63, "duration": 4.47}, {"text": "What stands out to you here?", "start": 565.1, "duration": 1.59}, {"text": "Sean?", "start": 576.71, "duration": 0.5}, {"text": "AUDIENCE: It decreases\nexponentially with temperature.", "start": 577.21, "duration": 3.57}, {"text": "JOHN DOLHUN: Yeah, as\nthe water is warming up,", "start": 580.78, "duration": 2.04}, {"text": "look what's happening\nto the dissolved oxygen.", "start": 582.82, "duration": 3.76}, {"text": "Why do you think\nthat's happening?", "start": 586.58, "duration": 1.906}, {"text": "And why, when the water is\ncold, can we hold so much oxygen", "start": 592.95, "duration": 6.09}, {"text": "in that cold water?", "start": 599.04, "duration": 3.14}, {"text": "Kelly.", "start": 602.18, "duration": 0.75}, {"text": "AUDIENCE: Is it because, as\nthe temperature increases,", "start": 602.93, "duration": 2.82}, {"text": "the average kinetic\nenergy of the molecules", "start": 605.75, "duration": 2.495}, {"text": "increases, and the\ndistribution broadens,", "start": 608.245, "duration": 2.665}, {"text": "so more oxygen has\nthe ability to escape?", "start": 610.91, "duration": 5.13}, {"text": "JOHN DOLHUN: Good, good.", "start": 616.04, "duration": 1.155}, {"text": "As the temperature increases,\nthe kinetic energy of the water", "start": 617.195, "duration": 3.675}, {"text": "molecules is\nincreasing, and they're", "start": 620.87, "duration": 2.37}, {"text": "starting-- think about\nwhen you boil water.", "start": 623.24, "duration": 3.12}, {"text": "Bam, they're bubbling out.", "start": 626.36, "duration": 2.43}, {"text": "That hydrogen bonding\nnetwork is gone.", "start": 628.79, "duration": 2.61}, {"text": "All those intermolecular\nforces of attraction are gone.", "start": 631.4, "duration": 3.51}, {"text": "Now think about this side when\nthe water gets really cold", "start": 634.91, "duration": 4.44}, {"text": "and you form this\nhydrogen bonding network.", "start": 639.35, "duration": 5.82}, {"text": "I mean, it expands, right?", "start": 645.17, "duration": 2.13}, {"text": "Pipes break.", "start": 647.3, "duration": 0.9}, {"text": "That's why our pipes break.", "start": 648.2, "duration": 1.35}, {"text": "It's because of the hydrogen\nbonding in the ice crystals", "start": 649.55, "duration": 3.225}, {"text": "when they expand out.", "start": 652.775, "duration": 1.635}, {"text": "But look at the crevices\nhere in these things.", "start": 654.41, "duration": 3.74}, {"text": "So the oxygen molecules can\nswim in and out of those,", "start": 658.15, "duration": 3.43}, {"text": "and they can become weakly\ntrapped and pinned in.", "start": 661.58, "duration": 3.3}, {"text": "And there you've got\na dramatic increase", "start": 664.88, "duration": 4.82}, {"text": "in the amount of oxygen that can\ndissolve in the colder waters.", "start": 669.7, "duration": 5.32}, {"text": "The other thing to keep in mind\nabout the water is the heat", "start": 675.02, "duration": 5.94}, {"text": "capacity of water\nis much greater", "start": 680.96, "duration": 2.7}, {"text": "than the heat capacity of air.", "start": 683.66, "duration": 2.43}, {"text": "It takes a lot more\nenergy to change", "start": 686.09, "duration": 2.61}, {"text": "the temperature of water.", "start": 688.7, "duration": 2.05}, {"text": "I mean, you can--", "start": 690.75, "duration": 1.875}, {"text": "I've gone out when\nit's 85 degrees,", "start": 692.625, "duration": 2.265}, {"text": "and I want to go for a\nswim across from my house.", "start": 694.89, "duration": 2.94}, {"text": "And I jump in, and\nit's only 67 in there.", "start": 697.83, "duration": 3.36}, {"text": "So the water hasn't caught up\nto the temperature of the air.", "start": 701.19, "duration": 3.63}, {"text": "Now there are a lot of\ndifferent equations out there", "start": 707.87, "duration": 6.4}, {"text": "that actually would\nlet us calculate", "start": 714.27, "duration": 2.85}, {"text": "the potential of a body of water\nto hold oxygen, theoretically,", "start": 717.12, "duration": 5.31}, {"text": "how much could be out\nthere on a given day.", "start": 722.43, "duration": 2.89}, {"text": "And the more complex\nthe equation,", "start": 725.32, "duration": 2.54}, {"text": "the better the results.", "start": 727.86, "duration": 1.8}, {"text": "I found a couple\nempirical, simple equations", "start": 729.66, "duration": 3.18}, {"text": "that give really good results,\nso I'm going to go with these.", "start": 732.84, "duration": 4.44}, {"text": "And they're all based on\naltitude and temperature.", "start": 737.28, "duration": 4.42}, {"text": "If you look at\nthe equation, it's", "start": 741.7, "duration": 2.24}, {"text": "all about the\natmospheric pressure,", "start": 743.94, "duration": 3.04}, {"text": "the water vapor pressure, and\nthe temperature of the water,", "start": 746.98, "duration": 4.86}, {"text": "which is in Celsius.", "start": 751.84, "duration": 2.04}, {"text": "So if we look at that\nequation, if the pressure,", "start": 753.88, "duration": 5.87}, {"text": "the atmospheric\npressure goes up, right,", "start": 759.75, "duration": 3.4}, {"text": "what happens to the dissolved\noxygen concentration?", "start": 763.15, "duration": 2.98}, {"text": "If you're trying to\ncalculate the saturated level", "start": 773.74, "duration": 2.37}, {"text": "of dissolved oxygen, and\nthe pressure goes up,", "start": 776.11, "duration": 3.96}, {"text": "the atmospheric\npressure, what happens", "start": 780.07, "duration": 1.8}, {"text": "to the DO concentration?", "start": 781.87, "duration": 1.5}, {"text": "I promise this is\nnot a trick question.", "start": 787.48, "duration": 3.66}, {"text": "This is-- Alec.", "start": 791.14, "duration": 1.232}, {"text": "AUDIENCE: It increases.", "start": 792.372, "duration": 0.958}, {"text": "JOHN DOLHUN: It\nabsolutely increases.", "start": 793.33, "duration": 1.92}, {"text": "Yeah.", "start": 795.25, "duration": 0.9}, {"text": "Now what happens if we\nhave a high water vapor", "start": 796.15, "duration": 2.73}, {"text": "pressure that day?", "start": 798.88, "duration": 2.82}, {"text": "You might be on a\nmountaintop stream.", "start": 801.7, "duration": 2.31}, {"text": "Water vapor pressure\nis very high.", "start": 804.01, "duration": 1.72}, {"text": "What happens to the DO?", "start": 805.73, "duration": 1.16}, {"text": "Someone?", "start": 811.41, "duration": 0.5}, {"text": "AUDIENCE: Decreases.", "start": 811.91, "duration": 0.93}, {"text": "JOHN DOLHUN: Sam, decreases.", "start": 812.84, "duration": 1.26}, {"text": "Good.", "start": 814.1, "duration": 1.77}, {"text": "And the other situation, which\nif the river temperature is", "start": 815.87, "duration": 4.32}, {"text": "high, then it's\nintuitive, right?", "start": 820.19, "duration": 3.33}, {"text": "Your DO is going to be smaller.", "start": 823.52, "duration": 5.1}, {"text": "So that's how you\nuse those equations.", "start": 828.62, "duration": 2.25}, {"text": "And then what you can\ndo with the equation", "start": 830.87, "duration": 2.04}, {"text": "is you can calculate a thing\ncalled the percent saturation", "start": 832.91, "duration": 4.65}, {"text": "level, which is the actual DO\nthat you get in the lab divided", "start": 837.56, "duration": 7.46}, {"text": "by the potential of\nwater to hold oxygen", "start": 845.02, "duration": 4.65}, {"text": "based on the temperature\nand pressure above.", "start": 849.67, "duration": 2.85}, {"text": "And that saturated\nlevel is going", "start": 852.52, "duration": 1.83}, {"text": "to tell us a lot about the\ncondition of the water.", "start": 854.35, "duration": 4.56}, {"text": "Usually-- I mean, you could\nhave from 90% to 110%,", "start": 858.91, "duration": 4.53}, {"text": "something like that.", "start": 863.44, "duration": 0.96}, {"text": "That's normal.", "start": 864.4, "duration": 1.14}, {"text": "If you get to 120%\nor greater, that's", "start": 865.54, "duration": 4.38}, {"text": "a problem, because there\nare different diseases", "start": 869.92, "duration": 3.03}, {"text": "that the fish can--", "start": 872.95, "duration": 1.32}, {"text": "they have an oxygen bubble\ndisease fish can get", "start": 874.27, "duration": 3.685}, {"text": "if it becomes too saturated.", "start": 877.955, "duration": 2.191}, {"text": "So this is something that\nyou'll do these calculations,", "start": 880.146, "duration": 4.654}, {"text": "and the TAs will\ncarry a pH meter.", "start": 884.8, "duration": 3.78}, {"text": "They'll record the\nair temperature,", "start": 888.58, "duration": 2.46}, {"text": "the atmospheric\npressure, the river water", "start": 891.04, "duration": 3.63}, {"text": "temperature each\nday you go down,", "start": 894.67, "duration": 1.89}, {"text": "and they'll put that\non the whiteboard.", "start": 896.56, "duration": 2.37}, {"text": "Here is some simple\ndata that will", "start": 898.93, "duration": 5.52}, {"text": "allow you to\ninterpolate the water", "start": 904.45, "duration": 1.89}, {"text": "vapor pressures based\non temperatures.", "start": 906.34, "duration": 5.32}, {"text": "And you can go in\nbetween these, and you'll", "start": 911.66, "duration": 1.83}, {"text": "get very good results.", "start": 913.49, "duration": 1.92}, {"text": "If you can't find it on here,\nyou could use this equation.", "start": 915.41, "duration": 3.82}, {"text": "But the T here is the\ntemperature of air,", "start": 919.23, "duration": 3.96}, {"text": "and it's in Kelvin.", "start": 923.19, "duration": 2.16}, {"text": "And back here, this\nis the temperature", "start": 925.35, "duration": 2.16}, {"text": "of the river in Celsius.", "start": 927.51, "duration": 1.96}, {"text": "So don't get confused with that.", "start": 929.47, "duration": 3.73}, {"text": "And now I'd like to spend\na few minutes talking", "start": 933.2, "duration": 2.85}, {"text": "about the actual method that\nwe're going to use in this lab.", "start": 936.05, "duration": 6.39}, {"text": "This method was\nactually discovered", "start": 942.44, "duration": 2.25}, {"text": "by a graduate student by the\nname of Winkler back in 1888.", "start": 944.69, "duration": 10.81}, {"text": "And the method has\nwithstood time.", "start": 955.5, "duration": 3.39}, {"text": "What he did is he developed this\nseries of oxidation reduction", "start": 958.89, "duration": 4.11}, {"text": "equations to actually\nmeasure the dissolved oxygen", "start": 963.0, "duration": 6.09}, {"text": "concentration in saltwater.", "start": 969.09, "duration": 3.21}, {"text": "And he came up with this\nseries of equations.", "start": 972.3, "duration": 3.06}, {"text": "And it's been 130 years,\nand this is still here.", "start": 975.36, "duration": 4.38}, {"text": "Today they have the fancy\ndissolved oxygen meters,", "start": 979.74, "duration": 3.81}, {"text": "which we're not using,\nbut you can just", "start": 983.55, "duration": 1.71}, {"text": "drop it in and get your DO.", "start": 985.26, "duration": 3.24}, {"text": "They used this method to\ncalibrate those meters today.", "start": 988.5, "duration": 4.44}, {"text": "So you're using--\nyou're going to be", "start": 992.94, "duration": 1.5}, {"text": "doing the real chemistry here.", "start": 994.44, "duration": 2.22}, {"text": "The whole method is\nbased on that if you've", "start": 996.66, "duration": 5.08}, {"text": "got oxygen in the\nwater, iodide is", "start": 1001.74, "duration": 3.99}, {"text": "going to get oxidized\nto iodine, and you're", "start": 1005.73, "duration": 3.12}, {"text": "going to be able to titrate the\niodine with sodium thiosulfate.", "start": 1008.85, "duration": 4.56}, {"text": "So let's just go through the\nmethod just a little bit here.", "start": 1013.41, "duration": 5.74}, {"text": "So we start with\nmanganese sulfate,", "start": 1019.15, "duration": 2.57}, {"text": "and we form a white precipitate.", "start": 1021.72, "duration": 2.94}, {"text": "But if oxygen is\npresent in the water,", "start": 1024.66, "duration": 3.9}, {"text": "oxygen is an\noxidizing agent here.", "start": 1028.56, "duration": 3.18}, {"text": "It's going to oxidize\nthis manganese hydroxide", "start": 1031.74, "duration": 4.41}, {"text": "to this tetravalent\nmanganic species.", "start": 1036.15, "duration": 5.41}, {"text": "So you've got manganese over\nhere, which is a plus 2,", "start": 1041.56, "duration": 4.61}, {"text": "and over here,\nyou've got a plus 4.", "start": 1046.17, "duration": 4.04}, {"text": "There are a couple--", "start": 1050.21, "duration": 0.93}, {"text": "in the literature, there's\nsome argument about this.", "start": 1051.14, "duration": 3.07}, {"text": "Some people feel the\nspecies is a trivalent,", "start": 1054.21, "duration": 3.86}, {"text": "and they're saying it's MnOH3.", "start": 1058.07, "duration": 2.71}, {"text": "So on this side, you'd have a\ntrivalent manganese species.", "start": 1063.35, "duration": 5.37}, {"text": "Other people are\nsaying no, it's MnO2.", "start": 1068.72, "duration": 4.0}, {"text": "It's a hydrated form of mnO2.", "start": 1072.72, "duration": 1.715}, {"text": "It's tetravalent.", "start": 1077.9, "duration": 1.92}, {"text": "What I've done is I've\ncombined both these", "start": 1079.82, "duration": 3.03}, {"text": "to give you this manganic\nspecies here, which works.", "start": 1082.85, "duration": 4.44}, {"text": "This is tetravalent.", "start": 1087.29, "duration": 2.4}, {"text": "So notice that when\nyou've formed this,", "start": 1089.69, "duration": 2.37}, {"text": "this is like a brown flock.", "start": 1092.06, "duration": 3.27}, {"text": "You've captured the\noxygen at this point.", "start": 1095.33, "duration": 4.04}, {"text": "Now you've got to dissolve\nthat, so we add sulfuric acid", "start": 1099.37, "duration": 4.92}, {"text": "to dissolve that\nbrown precipitate.", "start": 1104.29, "duration": 3.0}, {"text": "And then there's\niodide in there.", "start": 1107.29, "duration": 3.6}, {"text": "So this oxidized manganese\nwill oxidize iodide to iodine.", "start": 1110.89, "duration": 9.54}, {"text": "We can then detect it\nwith sodium thiosulfate,", "start": 1120.43, "duration": 3.75}, {"text": "and the iodine gets reduced\nback down to iodide.", "start": 1124.18, "duration": 5.07}, {"text": "If you look at this, for every\noxygen, every one oxygen,", "start": 1129.25, "duration": 4.26}, {"text": "you make to manganic species.", "start": 1133.51, "duration": 3.41}, {"text": "Each manganic species\ngives you one I2,", "start": 1136.92, "duration": 3.85}, {"text": "and each I2 requires\ntwo thiosulfate.", "start": 1140.77, "duration": 3.81}, {"text": "So that's a 4 to 1 ratio,\nthiosulfate to oxygen.", "start": 1144.58, "duration": 10.83}, {"text": "So let's take a look at\nyour first day, which", "start": 1155.41, "duration": 3.17}, {"text": "is the standardization\nof the thiosulfate.", "start": 1158.58, "duration": 4.71}, {"text": "We have to know exactly what\nthe concentration of that", "start": 1163.29, "duration": 3.18}, {"text": "is when we titrate the river\nwater to actually get-- to home", "start": 1166.47, "duration": 4.91}, {"text": "in on the exact concentration.", "start": 1171.38, "duration": 2.5}, {"text": "So we're going to be using a\nprimary standard, potassium", "start": 1173.88, "duration": 4.95}, {"text": "biiodate.", "start": 1178.83, "duration": 0.5}, {"text": "Does anybody know what the\nqualities of a primary standard", "start": 1187.66, "duration": 4.99}, {"text": "are?", "start": 1192.65, "duration": 0.5}, {"text": "When you pick a\nprimary standard,", "start": 1199.39, "duration": 1.8}, {"text": "it's pretty important.", "start": 1201.19, "duration": 1.14}, {"text": "You want something that\nhas certain properties.", "start": 1202.33, "duration": 4.58}, {"text": "Anybody ever worked\nwith a primary standard?", "start": 1206.91, "duration": 2.025}, {"text": "No?", "start": 1211.76, "duration": 2.73}, {"text": "OK, well, first thing,\nnotice how big this is.", "start": 1214.49, "duration": 4.815}, {"text": "It has a very high\nformula weight.", "start": 1219.305, "duration": 2.715}, {"text": "So that's actually a good thing.", "start": 1222.02, "duration": 2.565}, {"text": "Not all primary\nstandards have that.", "start": 1224.585, "duration": 4.235}, {"text": "When you mass it\nout, you're going", "start": 1228.82, "duration": 1.83}, {"text": "to have less error on\nthe balance because", "start": 1230.65, "duration": 2.88}, {"text": "of the mass of this thing.", "start": 1233.53, "duration": 2.1}, {"text": "Also, it has to be\nsomething that's pure.", "start": 1235.63, "duration": 4.56}, {"text": "And this is like 99.9% pure.", "start": 1240.19, "duration": 5.46}, {"text": "The other thing is\nyou need something", "start": 1245.65, "duration": 2.82}, {"text": "that does not have any\nwater vapor attached,", "start": 1248.47, "duration": 3.33}, {"text": "no attached water.", "start": 1251.8, "duration": 2.01}, {"text": "The TAs put this in the oven.", "start": 1253.81, "duration": 2.49}, {"text": "So no hydrated water.", "start": 1256.3, "duration": 5.79}, {"text": "And then the final\nthing is, you want--", "start": 1265.52, "duration": 3.09}, {"text": "it should be stable at room\ntemperature and when heated.", "start": 1268.61, "duration": 3.9}, {"text": "And oftentimes we'll\nlook at the cost, too.", "start": 1283.36, "duration": 2.28}, {"text": "That's another factor\nthat comes into play.", "start": 1285.64, "duration": 2.808}, {"text": "But what you're\ngoing to do is you're", "start": 1288.448, "duration": 1.542}, {"text": "going to weigh out\n0.0818 grams of this.", "start": 1289.99, "duration": 4.96}, {"text": "And if you divide by the\nmolecular weight of that,", "start": 1294.95, "duration": 2.45}, {"text": "you'll get moles.", "start": 1297.4, "duration": 1.8}, {"text": "And you're going to\nmake a 100-mil solution.", "start": 1299.2, "duration": 2.83}, {"text": "So divide that by 0.1\nliters, and you'll", "start": 1302.03, "duration": 3.14}, {"text": "get your concentration.", "start": 1305.17, "duration": 1.95}, {"text": "You're actually making up\nsomething like a 0.0021 molar", "start": 1307.12, "duration": 5.64}, {"text": "solution of that standard.", "start": 1312.76, "duration": 4.3}, {"text": "And then you're going to\nuse that to standardize", "start": 1317.06, "duration": 4.49}, {"text": "your thiosulfate.", "start": 1321.55, "duration": 2.84}, {"text": "We're also going to be using\nstarch in this reaction.", "start": 1324.39, "duration": 3.73}, {"text": "So why do you think\nwe need to use starch", "start": 1328.12, "duration": 2.9}, {"text": "when we're titrating something?", "start": 1331.02, "duration": 2.063}, {"text": "Alec.", "start": 1337.82, "duration": 0.8}, {"text": "AUDIENCE: Starch\nreacts with iodide,", "start": 1338.62, "duration": 1.69}, {"text": "and it creates the\nblue color so that when", "start": 1340.31, "duration": 3.15}, {"text": "we react-- when\nwe were titrating,", "start": 1343.46, "duration": 1.975}, {"text": "it could turn really pale.", "start": 1345.435, "duration": 1.235}, {"text": "JOHN DOLHUN: OK.", "start": 1346.67, "duration": 0.36}, {"text": "AUDIENCE: So it was really hard\nto tell if it was clear or not.", "start": 1347.03, "duration": 2.625}, {"text": "So I think the starch helps\nindicate whether or not", "start": 1349.655, "duration": 2.175}, {"text": "you've gotten rid of\nall of the iodide.", "start": 1351.83, "duration": 2.19}, {"text": "Iodide, yeah.", "start": 1354.02, "duration": 0.99}, {"text": "JOHN DOLHUN: Good.", "start": 1355.01, "duration": 0.75}, {"text": "Good.", "start": 1355.76, "duration": 0.31}, {"text": "That's very good.", "start": 1356.07, "duration": 0.73}, {"text": "So starch actually reacts\nwith iodide and iodine,", "start": 1356.8, "duration": 4.06}, {"text": "gives you that blue-black color.", "start": 1360.86, "duration": 1.44}, {"text": "So if you're titrating\nsomething yellow to clear,", "start": 1362.3, "duration": 3.75}, {"text": "sometimes it might\nbe harder to see.", "start": 1366.05, "duration": 3.22}, {"text": "So what Alec said\nwas your solution", "start": 1369.27, "duration": 5.1}, {"text": "actually reacts with starch.", "start": 1374.37, "duration": 4.28}, {"text": "So I actually brought some\nof the solution in here,", "start": 1378.65, "duration": 3.94}, {"text": "and I brought a\npiece of bread in.", "start": 1382.59, "duration": 1.83}, {"text": "I don't know if this\nis going to work,", "start": 1384.42, "duration": 2.01}, {"text": "but bread has starch\nin it, doesn't it?", "start": 1386.43, "duration": 3.87}, {"text": "So I'm going to put\nsomeone on this bread.", "start": 1390.3, "duration": 3.33}, {"text": "Wow.", "start": 1393.63, "duration": 1.93}, {"text": "Look at that blue black.", "start": 1395.56, "duration": 1.52}, {"text": "So something's going on here.", "start": 1397.08, "duration": 1.77}, {"text": "It's reacting with\nthe starch, right?", "start": 1398.85, "duration": 2.87}, {"text": "Can I have a volunteer?", "start": 1401.72, "duration": 2.67}, {"text": "Some brave person?", "start": 1404.39, "duration": 3.34}, {"text": "I know you're all\ntired, but one of you.", "start": 1407.73, "duration": 2.01}, {"text": "One of you, come up.", "start": 1409.74, "duration": 2.84}, {"text": "Come on up, Maida.", "start": 1412.58, "duration": 1.59}, {"text": "Maida, right?", "start": 1414.17, "duration": 1.29}, {"text": "It's Maida, right?", "start": 1418.21, "duration": 0.96}, {"text": "AUDIENCE: Yes.", "start": 1419.17, "duration": 0.24}, {"text": "JOHN DOLHUN: OK.", "start": 1419.41, "duration": 0.75}, {"text": "Maida, stand up front here.", "start": 1420.16, "duration": 2.41}, {"text": "So what we're going to do is\nwe're going to open this up.", "start": 1422.57, "duration": 3.56}, {"text": "And put a pair of\nthese on, Maida.", "start": 1426.13, "duration": 4.87}, {"text": "And I'm going to let\nyou hold this beaker", "start": 1431.0, "duration": 7.34}, {"text": "and face your fellow students.", "start": 1438.34, "duration": 2.31}, {"text": "And just hold it nice and--", "start": 1440.65, "duration": 2.58}, {"text": "and what we're\ngoing to do is we're", "start": 1445.834, "duration": 1.546}, {"text": "going to add something to it.", "start": 1447.38, "duration": 1.95}, {"text": "It's clear, right?", "start": 1449.33, "duration": 1.69}, {"text": "OK, keep your eye on the beaker.", "start": 1451.02, "duration": 3.9}, {"text": "Maida, don't drop\nbut whatever you do.", "start": 1454.92, "duration": 1.67}, {"text": "AUDIENCE: I won't drop it.", "start": 1456.59, "duration": 0.27}, {"text": "JOHN DOLHUN: OK.", "start": 1456.86, "duration": 0.667}, {"text": "[CHUCKLES]", "start": 1457.527, "duration": 0.823}, {"text": "OK.", "start": 1462.63, "duration": 1.95}, {"text": "So keep your eye on that beaker.", "start": 1464.58, "duration": 2.037}, {"text": "Don't take your\neyes off the beaker.", "start": 1470.03, "duration": 1.74}, {"text": "Now what-- don't worry.", "start": 1478.68, "duration": 1.715}, {"text": "Keep watching it, Maida.", "start": 1480.395, "duration": 1.465}, {"text": "Don't get nervous.", "start": 1481.86, "duration": 0.75}, {"text": "Oh!", "start": 1482.61, "duration": 1.28}, {"text": "Now that's what\nI'm talking about.", "start": 1483.89, "duration": 2.23}, {"text": "You see that?", "start": 1486.12, "duration": 1.31}, {"text": "This is what we're\ntalking about.", "start": 1487.43, "duration": 2.23}, {"text": "And I mean, you're titrating.", "start": 1489.66, "duration": 1.79}, {"text": "You can't see the end point.", "start": 1491.45, "duration": 1.17}, {"text": "You put this in, now that\nlast drop of titrant,", "start": 1492.62, "duration": 3.78}, {"text": "it's going to turn it clear.", "start": 1496.4, "duration": 2.01}, {"text": "You're going to be able\nto see your titration.", "start": 1498.41, "duration": 2.315}, {"text": "And thank you very much, Maida.", "start": 1500.725, "duration": 2.305}, {"text": "So what's going on\nwith the starch?", "start": 1508.8, "duration": 3.12}, {"text": "Let's take a look at this.", "start": 1511.92, "duration": 2.58}, {"text": "Starch is made up of\nabout 25% amylose, which", "start": 1514.5, "duration": 5.67}, {"text": "is the linear helical form.", "start": 1520.17, "duration": 2.88}, {"text": "And it also is made up about\n75% of the branched amylopectin.", "start": 1523.05, "duration": 5.87}, {"text": "What happens is we have\niodine and iodide present", "start": 1528.92, "duration": 5.535}, {"text": "in our solution, and when\nthose two come together,", "start": 1534.455, "duration": 5.065}, {"text": "they actually form\nthis pentaiodide anion.", "start": 1539.52, "duration": 5.07}, {"text": "So you've got some\nI2, some I minus.", "start": 1544.59, "duration": 6.39}, {"text": "Remember, I2 is amber.", "start": 1550.98, "duration": 2.67}, {"text": "I minus is clear.", "start": 1553.65, "duration": 1.95}, {"text": "When you get these\ntwo together and they", "start": 1555.6, "duration": 4.06}, {"text": "insert into this helix, the\namylose helix of starch,", "start": 1559.66, "duration": 5.04}, {"text": "and what amylose does is it\nforces the pentaiodide anion", "start": 1564.7, "duration": 4.86}, {"text": "to go in linearly\ninto that helix.", "start": 1569.56, "duration": 3.37}, {"text": "Then the energy spacings change.", "start": 1572.93, "duration": 3.46}, {"text": "So you've got-- the way the\nwavelength of light hits", "start": 1576.39, "duration": 2.96}, {"text": "that, you're going\nto see blue black.", "start": 1579.35, "duration": 2.19}, {"text": "It's all happening inside of\nthe starch with the amylose.", "start": 1581.54, "duration": 3.6}, {"text": "That's the key thing.", "start": 1585.14, "duration": 1.5}, {"text": "There are different people--", "start": 1586.64, "duration": 1.57}, {"text": "some people still\nbelieve it's I3 minus.", "start": 1588.21, "duration": 4.07}, {"text": "There's somebody else out\nthere saying no, no, it's", "start": 1592.28, "duration": 2.28}, {"text": "a polyiodide.", "start": 1594.56, "duration": 2.04}, {"text": "There's always going to be\nsome controversy in the--", "start": 1596.6, "duration": 3.57}, {"text": "but they're working on it.", "start": 1600.17, "duration": 2.1}, {"text": "I like I5.", "start": 1602.27, "duration": 1.74}, {"text": "And someone actually\nmade an inorganic complex", "start": 1604.01, "duration": 6.3}, {"text": "to make it look like starch,\nand they proved it was I5.", "start": 1610.31, "duration": 5.61}, {"text": "But even after this\npaper came out,", "start": 1615.92, "duration": 1.8}, {"text": "there's still a lot\nof controversy, so.", "start": 1617.72, "duration": 2.4}, {"text": "So for your standardization,\npretty simple.", "start": 1622.88, "duration": 4.807}, {"text": "You're going to go\nthrough, and you're", "start": 1627.687, "duration": 1.583}, {"text": "going to just\nfollow these steps.", "start": 1629.27, "duration": 1.65}, {"text": "The TAs will go through\nthis with you, very simple.", "start": 1630.92, "duration": 3.33}, {"text": "And you're going to\nstart off with probably", "start": 1634.25, "duration": 2.49}, {"text": "something like this, kind\nof like a reddish solution.", "start": 1636.74, "duration": 5.91}, {"text": "And then you're going to\nstart adding your thiosulfate.", "start": 1642.65, "duration": 6.87}, {"text": "And gradually, your titrating\nthe iodine in this solution", "start": 1649.52, "duration": 5.46}, {"text": "to iodide.", "start": 1654.98, "duration": 1.8}, {"text": "So here you've got a\nmore yellow solution.", "start": 1656.78, "duration": 2.425}, {"text": "What you want to do is you want\nto find a spot when it turns", "start": 1661.725, "duration": 5.055}, {"text": "yellow to add your starch.", "start": 1666.78, "duration": 3.8}, {"text": "And the starch has to be\nbubbly hot on the hot plate.", "start": 1670.58, "duration": 3.96}, {"text": "And if you add it\ntoo early, there's", "start": 1674.54, "duration": 4.61}, {"text": "so much iodine in\nthere, it's going", "start": 1679.15, "duration": 1.77}, {"text": "to destroy the starch complex.", "start": 1680.92, "duration": 2.28}, {"text": "You won't get a reaction.", "start": 1683.2, "duration": 2.22}, {"text": "But if you wait until it's\nso pale yellow, what happens,", "start": 1685.42, "duration": 4.945}, {"text": "Thomas?", "start": 1690.365, "duration": 0.5}, {"text": "AUDIENCE: It turns blue.", "start": 1692.85, "duration": 1.0}, {"text": "It makes the complex\nsuccessfully,", "start": 1693.85, "duration": 2.14}, {"text": "it turns it dark blue.", "start": 1695.99, "duration": 1.68}, {"text": "JOHN DOLHUN: It\nturns it dark blue.", "start": 1697.67, "duration": 2.37}, {"text": "Yeah.", "start": 1700.04, "duration": 0.69}, {"text": "But if you wait\ntoo long, right--", "start": 1700.73, "duration": 2.357}, {"text": "AUDIENCE: [? I ?] [? mean, ?]\nif you add too much, [INAUDIBLE]", "start": 1703.087, "duration": 2.583}, {"text": "JOHN DOLHUN: Did you--", "start": 1705.67, "duration": 0.95}, {"text": "you had a reaction\nyesterday where your starch", "start": 1706.62, "duration": 2.35}, {"text": "was an globules, right?", "start": 1708.97, "duration": 1.71}, {"text": "Is that--", "start": 1710.68, "duration": 0.87}, {"text": "AUDIENCE: Oh yeah.", "start": 1711.55, "duration": 0.952}, {"text": "It formed a film because\nwe didn't keep it hot.", "start": 1712.502, "duration": 3.36}, {"text": "JOHN DOLHUN: Oh, the\nstarch was not hot enough.", "start": 1715.862, "duration": 1.958}, {"text": "OK, that explains that.", "start": 1717.82, "duration": 1.76}, {"text": "AUDIENCE: [INAUDIBLE]", "start": 1719.58, "duration": 0.94}, {"text": "JOHN DOLHUN: Yeah.", "start": 1720.52, "duration": 0.45}, {"text": "AUDIENCE: We put\nit in and stirred,", "start": 1720.97, "duration": 0.973}, {"text": "and it made a bunch of little\nblue specks that [INAUDIBLE]..", "start": 1721.943, "duration": 2.957}, {"text": "JOHN DOLHUN: Yes, yes.", "start": 1724.9, "duration": 1.32}, {"text": "Yeah, I've seen that before.", "start": 1726.22, "duration": 1.51}, {"text": "So you want to keep your starch\nhot, and just be patient.", "start": 1727.73, "duration": 5.12}, {"text": "And then you just take a\nplastic pasture pipette,", "start": 1732.85, "duration": 4.17}, {"text": "take a swig of it,\nshoot it in, and you", "start": 1737.02, "duration": 2.64}, {"text": "should get your blue black.", "start": 1739.66, "duration": 1.95}, {"text": "And then look.", "start": 1741.61, "duration": 1.96}, {"text": "You've got your blue black.", "start": 1743.57, "duration": 1.55}, {"text": "You put that last drop\nof thiosulfate in,", "start": 1745.12, "duration": 2.61}, {"text": "and you've got your\nclear solution.", "start": 1747.73, "duration": 2.71}, {"text": "So you turn around, and\nyou're writing this down", "start": 1750.44, "duration": 2.0}, {"text": "in your notebooks, right,\nand then you look back,", "start": 1752.44, "duration": 4.53}, {"text": "but it's starting to\nturn blue black again.", "start": 1756.97, "duration": 2.49}, {"text": "What should you do?", "start": 1759.46, "duration": 0.98}, {"text": "What would you do?", "start": 1763.49, "duration": 0.86}, {"text": "AUDIENCE: Add another\ndrop of titrant.", "start": 1768.84, "duration": 2.482}, {"text": "JOHN DOLHUN: Add\nanother drop of titrant.", "start": 1771.322, "duration": 1.708}, {"text": "That's what I would do, Thomas.", "start": 1773.03, "duration": 2.04}, {"text": "But it's not correct.", "start": 1775.07, "duration": 1.13}, {"text": "AUDIENCE: [LAUGHS]", "start": 1776.2, "duration": 0.75}, {"text": "JOHN DOLHUN: But I\nwould do the same thing.", "start": 1776.95, "duration": 1.792}, {"text": "I would add another\ndrop of titrant.", "start": 1778.742, "duration": 1.698}, {"text": "AUDIENCE: Oh, what if it\njust turned blue by itself,", "start": 1780.44, "duration": 1.49}, {"text": "[INAUDIBLE] and you're\njust [INAUDIBLE]", "start": 1781.93, "duration": 1.625}, {"text": "JOHN DOLHUN: There's a side\nreaction going on in the air.", "start": 1783.555, "duration": 2.855}, {"text": "When you get this\nclear, you've got", "start": 1786.41, "duration": 2.1}, {"text": "all iodide present in there.", "start": 1788.51, "duration": 2.74}, {"text": "But what happens is--", "start": 1791.25, "duration": 1.04}, {"text": "so you've got iodide\nthere, but you also", "start": 1795.18, "duration": 4.83}, {"text": "have oxygen in the air.", "start": 1800.01, "duration": 1.44}, {"text": "And the oxygen is oxidizing\nthe iodide to iodine,", "start": 1804.86, "duration": 10.23}, {"text": "and we don't want this\niodine coming from the air.", "start": 1815.09, "duration": 3.36}, {"text": "We want it only from\nthe river water,", "start": 1818.45, "duration": 2.16}, {"text": "right, from the\noxygen in the river.", "start": 1820.61, "duration": 2.34}, {"text": "So this is a side reaction that\ncan go on if you let it set.", "start": 1822.95, "duration": 4.38}, {"text": "So just ignore it.", "start": 1827.33, "duration": 1.68}, {"text": "Just take your end point,\nyour final neutralization,", "start": 1829.01, "duration": 6.66}, {"text": "and you're good.", "start": 1835.67, "duration": 2.37}, {"text": "Take a look at the\nstoichiometry here.", "start": 1838.04, "duration": 2.76}, {"text": "One biiodate make six I2.", "start": 1840.8, "duration": 4.775}, {"text": "Each I2 reacts with\ntwo thiosulfate.", "start": 1845.575, "duration": 4.445}, {"text": "So it's 12 to 1\nthiosulfate to biiodate.", "start": 1850.02, "duration": 5.695}, {"text": "What you're going\nto do is you're", "start": 1855.715, "duration": 1.375}, {"text": "going to do three trials,\nand they all should agree to", "start": 1857.09, "duration": 4.05}, {"text": "within 2% or 3%.", "start": 1861.14, "duration": 2.22}, {"text": "If they don't, do an\nextra trial or two.", "start": 1863.36, "duration": 3.42}, {"text": "And what you're\ngoing to do is you're", "start": 1866.78, "duration": 2.1}, {"text": "going to find your mean,\nyour standard deviation,", "start": 1868.88, "duration": 2.85}, {"text": "and your confidence\nintervals and then give all", "start": 1871.73, "duration": 2.64}, {"text": "that information to your TA.", "start": 1874.37, "duration": 2.16}, {"text": "Yesterday the TAs\ndid a beautiful job.", "start": 1876.53, "duration": 2.16}, {"text": "They put everybody's on\nan Excel spreadsheet,", "start": 1878.69, "duration": 3.0}, {"text": "had it all averaged out.", "start": 1881.69, "duration": 1.96}, {"text": "They really did a\ngood job yesterday.", "start": 1883.65, "duration": 2.37}, {"text": "The students really homed in\non the exact concentration", "start": 1886.02, "duration": 4.25}, {"text": "of the thiosulfate.", "start": 1890.27, "duration": 2.42}, {"text": "So it's pretty simple.", "start": 1892.69, "duration": 1.71}, {"text": "You do your calculations\nright there in the lab.", "start": 1894.4, "duration": 3.06}, {"text": "And then you have a choice\nof using the class average", "start": 1897.46, "duration": 3.51}, {"text": "or using your own results for\nthe dissolved oxygen that will", "start": 1900.97, "duration": 3.99}, {"text": "take place on the next day.", "start": 1904.96, "duration": 1.38}, {"text": "So collection of water samples.", "start": 1911.62, "duration": 2.4}, {"text": "So you're going to be going\nto the river for day two.", "start": 1914.02, "duration": 3.66}, {"text": "And we have these poles.", "start": 1917.68, "duration": 2.82}, {"text": "If you have long arms,\nyou'll take a short poll.", "start": 1920.5, "duration": 5.66}, {"text": "If you're short and\nhave short arms,", "start": 1926.16, "duration": 2.53}, {"text": "then we have real long poles.", "start": 1928.69, "duration": 1.8}, {"text": "They're like hockey sticks.", "start": 1930.49, "duration": 2.28}, {"text": "So you get your stick, and what\nyou do is you insert your--", "start": 1932.77, "duration": 6.21}, {"text": "your BOD bottle snaps into\nthe clip that I've got inside.", "start": 1938.98, "duration": 3.85}, {"text": "You take the stopper\nout, and then you", "start": 1942.83, "duration": 2.3}, {"text": "go to the edge of the dock.", "start": 1945.13, "duration": 1.77}, {"text": "Don't fall in, and\ndon't push anybody, OK.", "start": 1946.9, "duration": 5.25}, {"text": "Remember the cyanobacteria\nand all that out there.", "start": 1952.15, "duration": 3.93}, {"text": "And take gloves with\nyou, because when", "start": 1956.08, "duration": 2.82}, {"text": "you put this under water, it's\ngot to be completely submerged.", "start": 1958.9, "duration": 3.84}, {"text": "You have to reach over the dock.", "start": 1962.74, "duration": 2.04}, {"text": "You've got to stopper\nit underwater.", "start": 1964.78, "duration": 2.28}, {"text": "So you've got to have\ngloves with you, all right.", "start": 1967.06, "duration": 2.85}, {"text": "So I stoppered mine underwater.", "start": 1969.91, "duration": 2.13}, {"text": "I bring it up, take it out,\nand then I look at the--", "start": 1972.04, "duration": 5.46}, {"text": "I take the bottle,\nand I do this test.", "start": 1977.5, "duration": 3.9}, {"text": "I don't see any bubbles.", "start": 1981.4, "duration": 2.01}, {"text": "That's a good sign.", "start": 1983.41, "duration": 1.66}, {"text": "That means it's perfect.", "start": 1985.07, "duration": 1.8}, {"text": "If you see bubbles, you've\nintroduced more oxygen", "start": 1986.87, "duration": 3.47}, {"text": "in there.", "start": 1990.34, "duration": 0.78}, {"text": "Your DO concentrations\nare going to be too high.", "start": 1991.12, "duration": 2.91}, {"text": "Pour it out, and restart again.", "start": 1994.03, "duration": 2.95}, {"text": "OK, so that's the collection.", "start": 1996.98, "duration": 3.0}, {"text": "Then you bring the\nstuff back to the lab,", "start": 1999.98, "duration": 2.87}, {"text": "and you're going to treat\nthe bottles in the lab.", "start": 2002.85, "duration": 5.502}, {"text": "This here is wrong.", "start": 2008.352, "duration": 3.438}, {"text": "You don't want to use these\ndigital pipetters to treat", "start": 2011.79, "duration": 3.66}, {"text": "the water, because you'll\nbe introducing oxygen", "start": 2015.45, "duration": 3.8}, {"text": "into those water bottles.", "start": 2019.25, "duration": 1.39}, {"text": "What you're going to use is\nyour 10-mL glass pipette.", "start": 2020.64, "duration": 4.8}, {"text": "And what we're\ngoing to do here is", "start": 2025.44, "duration": 4.23}, {"text": "each pair of students\nwill have four bottles.", "start": 2029.67, "duration": 3.63}, {"text": "So you're going to--", "start": 2033.3, "duration": 1.32}, {"text": "first, you're going to treat it\nwith the manganese sulfate, 2", "start": 2034.62, "duration": 4.11}, {"text": "mLs of manganese sulfate.", "start": 2038.73, "duration": 1.41}, {"text": "That's the first reaction\non that oxidation reduction", "start": 2040.14, "duration": 3.57}, {"text": "Winkler series.", "start": 2043.71, "duration": 1.89}, {"text": "And the way you do it\nis-- what I would do", "start": 2045.6, "duration": 2.19}, {"text": "is I would take up 10\nmils of manganese sulfate", "start": 2047.79, "duration": 4.38}, {"text": "to prevent any airflow, any air.", "start": 2052.17, "duration": 3.14}, {"text": "And then what you're\ngoing to do is you're", "start": 2055.31, "duration": 1.75}, {"text": "going to take the stopper out.", "start": 2057.06, "duration": 1.95}, {"text": "You're going to go just below\nthe surface of the liquid", "start": 2059.01, "duration": 3.57}, {"text": "and put in 2 mils.", "start": 2062.58, "duration": 2.099}, {"text": "And then your partner\ncan stopper it.", "start": 2064.679, "duration": 1.921}, {"text": "You go to the next one.", "start": 2066.6, "duration": 1.079}, {"text": "You do all four of them.", "start": 2067.679, "duration": 1.861}, {"text": "The last 2 mils in here,\nshoot it into waste.", "start": 2069.54, "duration": 3.96}, {"text": "And then do the same thing\nwith the alkaline-iodide-azide", "start": 2073.5, "duration": 3.719}, {"text": "reagent, 2 mils in each bottle.", "start": 2077.219, "duration": 2.821}, {"text": "And you should look at\nthe bottle at this point.", "start": 2080.04, "duration": 4.949}, {"text": "After you add those\nreagents, there", "start": 2084.989, "duration": 1.741}, {"text": "should not be any bubbles.", "start": 2086.73, "duration": 2.28}, {"text": "If there's a bubble, it\nmeans you've introduced air,", "start": 2089.01, "duration": 3.45}, {"text": "and your DO values will\nbe higher by doing that.", "start": 2092.46, "duration": 5.2}, {"text": "So once you've treated with\nthese two steps here, you've", "start": 2097.66, "duration": 6.59}, {"text": "essentially trapped\nthe oxygen. You're", "start": 2104.25, "duration": 2.31}, {"text": "going to have this\nbrown flock like this.", "start": 2106.56, "duration": 3.52}, {"text": "Now you just shake that\na bit, and then you're", "start": 2110.08, "duration": 4.92}, {"text": "going to dissolve it now\nby adding sulfuric acid, 28", "start": 2115.0, "duration": 3.93}, {"text": "drops of sulfuric.", "start": 2118.93, "duration": 1.8}, {"text": "Acid for the sulfuric, you\ndon't go below the surface.", "start": 2120.73, "duration": 2.94}, {"text": "You just open the lid,\nand you drip, drip it in.", "start": 2123.67, "duration": 3.66}, {"text": "The acid is heavy.", "start": 2127.33, "duration": 0.99}, {"text": "It's going to fall right to\nthe bottom of the bottle.", "start": 2128.32, "duration": 2.97}, {"text": "And now you should\nhave a bubble in there.", "start": 2131.29, "duration": 4.68}, {"text": "You will have a bubble\nafter you add the sulfuric,", "start": 2135.97, "duration": 2.76}, {"text": "and that's OK.", "start": 2138.73, "duration": 2.53}, {"text": "So when you're done with\nthis, you're ready to titrate.", "start": 2141.26, "duration": 3.86}, {"text": "And we've got to-- we're\nsupposed to titrate 200 mils.", "start": 2145.12, "duration": 4.59}, {"text": "That's what you titrated when\nyou did your standardization as", "start": 2149.71, "duration": 3.27}, {"text": "well.", "start": 2152.98, "duration": 1.67}, {"text": "But we've got to make\nup for the 4 mils", "start": 2154.65, "duration": 5.81}, {"text": "that we added there\nin the beginning.", "start": 2160.46, "duration": 2.91}, {"text": "We've displaced something there.", "start": 2163.37, "duration": 2.33}, {"text": "So you want to titrate\n200 mLs times--", "start": 2165.7, "duration": 5.46}, {"text": "you've got a 300 mL BOD bottle,\nand you've taken and added", "start": 2171.16, "duration": 6.84}, {"text": "4 mLs of stuff to it.", "start": 2178.0, "duration": 2.81}, {"text": "So if you do the math\nto make up for that,", "start": 2180.81, "duration": 2.69}, {"text": "you really have to\ntitrate 203 mLs.", "start": 2183.5, "duration": 4.28}, {"text": "So there's a couple\nways you could do this.", "start": 2187.78, "duration": 3.07}, {"text": "You can use a 100-mL graduated\ncylinder, and the error on that", "start": 2190.85, "duration": 6.13}, {"text": "is about plus or minus 0.5.", "start": 2196.98, "duration": 2.97}, {"text": "You fill that up twice,\nput that in your container.", "start": 2199.95, "duration": 4.33}, {"text": "The last 3 mils, you could\nuse this for accuracy", "start": 2204.28, "duration": 5.13}, {"text": "to get your last 3 mLs\nin, and then you're good.", "start": 2209.41, "duration": 4.02}, {"text": "But you can also\njust titrate 200 mLs", "start": 2213.43, "duration": 5.46}, {"text": "and then multiply your answer\nby a correction factor, which", "start": 2218.89, "duration": 4.53}, {"text": "would be 203 over 200.", "start": 2223.42, "duration": 4.56}, {"text": "And that will give you the same\nanswer as titrating the 203.", "start": 2227.98, "duration": 11.12}, {"text": "So the math is\npretty simple here.", "start": 2239.1, "duration": 2.97}, {"text": "You're converting the\nmoles of your titrant", "start": 2242.07, "duration": 3.15}, {"text": "to moles of oxygen,\ngrams of oxygen.", "start": 2245.22, "duration": 3.69}, {"text": "You divide by the liters.", "start": 2248.91, "duration": 2.61}, {"text": "If you're doing 200\nmLs, that's 0.2 liters.", "start": 2251.52, "duration": 4.74}, {"text": "And then you get your\nmilligrams per liter in PPM.", "start": 2256.26, "duration": 4.1}, {"text": "I kept mentioning\nwe're using the--", "start": 2266.88, "duration": 4.08}, {"text": "we've got to add this\nalkaline-azide solution.", "start": 2270.96, "duration": 3.21}, {"text": "We're actually using\nthe azide modification", "start": 2274.17, "duration": 3.24}, {"text": "of the Winkler method.", "start": 2277.41, "duration": 2.3}, {"text": "And what is that?", "start": 2279.71, "duration": 2.15}, {"text": "Well, there are NOx\ngases in the atmosphere.", "start": 2281.86, "duration": 7.42}, {"text": "What's the nastiest NOx\ngas that you can think of?", "start": 2289.28, "duration": 3.66}, {"text": "I'll give you a hint.", "start": 2305.67, "duration": 2.11}, {"text": "It's a big greenhouse\ngas, and it's not CO2.", "start": 2307.78, "duration": 5.801}, {"text": "AUDIENCE: Ozone?", "start": 2313.581, "duration": 1.749}, {"text": "JOHN DOLHUN: Ozone is\na gas up there, yeah.", "start": 2315.33, "duration": 2.94}, {"text": "But that protects us.", "start": 2318.27, "duration": 2.34}, {"text": "Our ozone layer is a\nlayer of protection.", "start": 2320.61, "duration": 4.94}, {"text": "But what's-- yes.", "start": 2325.55, "duration": 1.14}, {"text": "AUDIENCE: Is it NO2 or--", "start": 2326.69, "duration": 3.685}, {"text": "JOHN DOLHUN: The other way.", "start": 2330.375, "duration": 1.125}, {"text": "AUDIENCE: Or N O?", "start": 2331.5, "duration": 0.81}, {"text": "I know that [INAUDIBLE]", "start": 2332.31, "duration": 3.24}, {"text": "JOHN DOLHUN: All right,\nplease don't laugh at this.", "start": 2335.55, "duration": 3.86}, {"text": "It's laughing gas, N2O.", "start": 2339.41, "duration": 4.3}, {"text": "You're all-- I\nmean, the atmosphere", "start": 2343.71, "duration": 2.12}, {"text": "is loaded with laughing gas.", "start": 2345.83, "duration": 2.39}, {"text": "I know.", "start": 2348.22, "duration": 0.76}, {"text": "Everybody's laughing now.", "start": 2348.98, "duration": 2.46}, {"text": "It's great.", "start": 2351.44, "duration": 1.2}, {"text": "Where does it come from, N2O?", "start": 2352.64, "duration": 2.79}, {"text": "All the fertilizer.", "start": 2355.43, "duration": 2.01}, {"text": "1% of all the\nfertilizer in the world", "start": 2357.44, "duration": 3.12}, {"text": "goes up in the atmosphere\nas laughing gas.", "start": 2360.56, "duration": 2.73}, {"text": "It's not from a\ndentist's office.", "start": 2363.29, "duration": 1.98}, {"text": "It's from fertilizer.", "start": 2365.27, "duration": 1.28}, {"text": "I know.", "start": 2366.55, "duration": 1.39}, {"text": "I don't want to\nthink about dentists.", "start": 2367.94, "duration": 1.83}, {"text": "I was just at one yesterday.", "start": 2369.77, "duration": 1.59}, {"text": "I don't like dentists.", "start": 2371.36, "duration": 2.52}, {"text": "But every ton of laughing\ngas that's in the atmosphere.", "start": 2373.88, "duration": 7.36}, {"text": "is like 300 tons of CO2.", "start": 2381.24, "duration": 4.04}, {"text": "And it stays up there\nfor over 100 years.", "start": 2385.28, "duration": 3.58}, {"text": "And what does it do?", "start": 2388.86, "duration": 2.49}, {"text": "Well, who said ozone back there?", "start": 2391.35, "duration": 7.65}, {"text": "There you are.", "start": 2399.0, "duration": 0.78}, {"text": "OK.", "start": 2399.78, "duration": 1.41}, {"text": "Laughing gas reacts\nwith ozone, and it", "start": 2401.19, "duration": 3.93}, {"text": "forms dinitrogen dioxide.", "start": 2405.12, "duration": 2.47}, {"text": "And this dinitrogen dioxide\nonly lasts for about an hour.", "start": 2410.5, "duration": 5.07}, {"text": "And immediately, the N2O2\nreacts with air and water", "start": 2415.57, "duration": 11.52}, {"text": "to form nitrites.", "start": 2427.09, "duration": 0.99}, {"text": "And here we are talking about\ngreenhouse gas in the world,", "start": 2435.76, "duration": 5.35}, {"text": "and this is affecting our little\ntiny reaction in the Charles", "start": 2441.11, "duration": 3.62}, {"text": "River experiment, because these\nnitrites, look what they do.", "start": 2444.73, "duration": 4.59}, {"text": "They get in and oxidize\niodide to iodine.", "start": 2449.32, "duration": 3.96}, {"text": "And we don't want\nour iodine coming", "start": 2453.28, "duration": 2.31}, {"text": "from some reaction from laughing\ngas, right, from nitrite.", "start": 2455.59, "duration": 4.92}, {"text": "We want it coming from\nthe oxygen in the river.", "start": 2460.51, "duration": 3.24}, {"text": "So we add sodium azide.", "start": 2463.75, "duration": 3.12}, {"text": "And that zaps the\nnitrites, convert them", "start": 2466.87, "duration": 3.24}, {"text": "to harmless nitrogen and water.", "start": 2470.11, "duration": 3.21}, {"text": "So that's the theory\nbehind why we're", "start": 2473.32, "duration": 5.69}, {"text": "using the azide modification.", "start": 2479.01, "duration": 1.98}, {"text": "All that for these nitrites.", "start": 2480.99, "duration": 2.22}, {"text": "So let's talk for a moment\nabout pH, pH in natural waters.", "start": 2486.84, "duration": 6.45}, {"text": "Let's see here.", "start": 2493.29, "duration": 1.323}, {"text": "Pulling down some board, here.", "start": 2494.613, "duration": 1.932}, {"text": "Who knows the definition of pH?", "start": 2500.42, "duration": 2.01}, {"text": "Remember your chemical\nprinciples from a long time a--", "start": 2513.49, "duration": 2.695}, {"text": "Alec.", "start": 2516.185, "duration": 0.5}, {"text": "AUDIENCE: I think it was log\nof concentration of hydrogen", "start": 2516.685, "duration": 3.075}, {"text": "ions, [INAUDIBLE] ions.", "start": 2519.76, "duration": 1.062}, {"text": "JOHN DOLHUN: Very good.", "start": 2520.822, "duration": 0.958}, {"text": "The negative log of the\nconcentration of the hydrogen", "start": 2521.78, "duration": 2.81}, {"text": "ions.", "start": 2524.59, "duration": 1.126}, {"text": "So pH.", "start": 2525.716, "duration": 0.5}, {"text": "And I mean, you all know\nthe pH scale is 0 to 14,", "start": 2532.99, "duration": 3.24}, {"text": "and acid is less than 7.", "start": 2536.23, "duration": 2.79}, {"text": "And I hope you know what color\nlitmus paper changes, right,", "start": 2539.02, "duration": 3.39}, {"text": "with pH.", "start": 2542.41, "duration": 0.505}, {"text": "That was a question on a\nTV show with Regis Philbin,", "start": 2545.68, "duration": 4.29}, {"text": "You Want to Be a Millionaire.", "start": 2549.97, "duration": 1.92}, {"text": "A guy actually got up to\nthe million dollar question.", "start": 2551.89, "duration": 4.4}, {"text": "And I happened to turn\nit on just at that point,", "start": 2556.29, "duration": 4.14}, {"text": "and they ask him,\nwhat color does", "start": 2560.43, "duration": 1.65}, {"text": "litmus paper change in base?", "start": 2562.08, "duration": 3.39}, {"text": "And the guy said,\noh, I don't know,", "start": 2565.47, "duration": 3.12}, {"text": "but can I call my lifeline?", "start": 2568.59, "duration": 2.52}, {"text": "And they said yes.", "start": 2571.11, "duration": 1.38}, {"text": "So he called this\nprestigious biologist", "start": 2572.49, "duration": 3.12}, {"text": "at one of the\nCalifornia universities.", "start": 2575.61, "duration": 3.18}, {"text": "And they said red.", "start": 2578.79, "duration": 1.98}, {"text": "[LAUGHTER]", "start": 2580.77, "duration": 1.23}, {"text": "And the guy answers red, and\nhe loses the million dollars.", "start": 2582.0, "duration": 4.514}, {"text": "Oh, I was beside myself.", "start": 2586.514, "duration": 3.346}, {"text": "So if you remember anything,\nremember what color", "start": 2589.86, "duration": 2.8}, {"text": "litmus paper is in acid.", "start": 2592.66, "duration": 2.66}, {"text": "But in the river, the pH\ncan go from 6.5 to 8.5.", "start": 2595.32, "duration": 9.12}, {"text": "And the pH effects everything,\nfrom the solubility of metals--", "start": 2604.44, "duration": 6.36}, {"text": "if it gets too acidic\nout there in the river,", "start": 2610.8, "duration": 3.585}, {"text": "the metals become more soluble,\nmercury, cadmium, arsenic,", "start": 2614.385, "duration": 6.355}, {"text": "all those metals.", "start": 2620.74, "duration": 1.26}, {"text": "So the fish uptake the\nmetals, and we eat the fish.", "start": 2622.0, "duration": 3.3}, {"text": "And with global warming,\nthe acidity of the rivers", "start": 2625.3, "duration": 3.39}, {"text": "is gradually drifting\nvery slightly lower.", "start": 2628.69, "duration": 5.52}, {"text": "It also affects the\nforms of phosphorous.", "start": 2634.21, "duration": 3.18}, {"text": "So remember, you've\ngot PO4 to the 3 minus.", "start": 2637.39, "duration": 4.92}, {"text": "But if it's slightly\nacidic, you might", "start": 2642.31, "duration": 2.64}, {"text": "have the hydrogen phosphate\nor the dihydrogen phosphate.", "start": 2644.95, "duration": 7.86}, {"text": "Or you could end up\nwith phosphoric acid,", "start": 2656.17, "duration": 4.58}, {"text": "depending on how acidic it gets.", "start": 2660.75, "duration": 3.4}, {"text": "What about\nphotosynthesis and pH?", "start": 2664.15, "duration": 2.741}, {"text": "Where are my biologists\nat, my resident bi--", "start": 2669.87, "duration": 4.7}, {"text": "there must be somebody\nin bio in here.", "start": 2674.57, "duration": 2.22}, {"text": "Come on.", "start": 2676.79, "duration": 2.37}, {"text": "Don't be afraid.", "start": 2679.16, "duration": 2.07}, {"text": "Yes.", "start": 2681.23, "duration": 1.17}, {"text": "There you are.", "start": 2682.4, "duration": 1.35}, {"text": "What's the equation\nfor photosynthesis?", "start": 2683.75, "duration": 3.696}, {"text": "AUDIENCE: Water\nand carbon dioxide.", "start": 2687.446, "duration": 1.634}, {"text": "JOHN DOLHUN: Good, good.", "start": 2689.08, "duration": 1.0}, {"text": "Water and carbon dioxide.", "start": 2690.08, "duration": 2.07}, {"text": "Let's just write that\ndown for a moment.", "start": 2692.15, "duration": 1.95}, {"text": "So CO2 plus water,\nlittle bit of sun.", "start": 2697.95, "duration": 10.07}, {"text": "AUDIENCE: Oxygen and glucose.", "start": 2708.02, "duration": 2.1}, {"text": "JOHN DOLHUN: Oxygen\nand sugars, good.", "start": 2710.12, "duration": 2.64}, {"text": "So CH2O, n.", "start": 2712.76, "duration": 1.85}, {"text": "So does the pH go up or\ndown during photosynthesis?", "start": 2720.23, "duration": 4.77}, {"text": "I mean, it's like\na 50/50 chance.", "start": 2729.06, "duration": 2.105}, {"text": "Sean, you want to\nanswer, don't you?", "start": 2736.63, "duration": 2.92}, {"text": "AUDIENCE: I would\nsay the pH goes up.", "start": 2739.55, "duration": 2.97}, {"text": "JOHN DOLHUN: It goes up?", "start": 2742.52, "duration": 1.0}, {"text": "OK.", "start": 2743.52, "duration": 0.88}, {"text": "Anyone else?", "start": 2744.4, "duration": 0.78}, {"text": "Alec?", "start": 2745.18, "duration": 0.795}, {"text": "AUDIENCE: It goes down?", "start": 2745.975, "duration": 1.125}, {"text": "JOHN DOLHUN: It goes down?", "start": 2747.1, "duration": 0.75}, {"text": "OK.", "start": 2747.85, "duration": 0.39}, {"text": "[LAUGHTER]", "start": 2748.24, "duration": 0.54}, {"text": "There you go.", "start": 2748.78, "duration": 0.72}, {"text": "I told you it's\nlike a 50/50, right?", "start": 2749.5, "duration": 2.85}, {"text": "All right, let's do a\nlittle experiment with this.", "start": 2752.35, "duration": 3.78}, {"text": "I'm going to pour\nmyself a drink here.", "start": 2758.68, "duration": 1.99}, {"text": "This is good stuff.", "start": 2764.38, "duration": 1.26}, {"text": "It's not Gatorade,\nI can tell you that.", "start": 2771.15, "duration": 1.68}, {"text": "This is a classic test in\nthe medical profession,", "start": 2776.175, "duration": 4.845}, {"text": "if you're going to medical\nschool, for breath.", "start": 2781.02, "duration": 3.0}, {"text": "And when I'm doing this,\nyou cannot make me laugh.", "start": 2784.02, "duration": 4.14}, {"text": "If you make me\nlaugh, I'm dead, OK.", "start": 2788.16, "duration": 2.51}, {"text": "Please.", "start": 2790.67, "duration": 1.06}, {"text": "I'm going to play some\nmusic to relax myself here.", "start": 2791.73, "duration": 4.81}, {"text": "Let me just-- let me see\nif we can get this on here.", "start": 2796.54, "duration": 4.28}, {"text": "OK.", "start": 2800.82, "duration": 0.72}, {"text": "There we go.", "start": 2801.54, "duration": 0.71}, {"text": "So I'm breathing into this.", "start": 2805.34, "duration": 2.12}, {"text": "We don't hear any\nmusic coming out.", "start": 2811.45, "duration": 3.9}, {"text": "Going to--", "start": 2815.35, "duration": 1.572}, {"text": "[MUSIC PLAYING]", "start": 2816.922, "duration": 4.268}, {"text": "There we go.", "start": 2821.19, "duration": 0.56}, {"text": "You're making me laugh, Sean.", "start": 2830.41, "duration": 1.62}, {"text": "I may have to have you come\nup and help me with this.", "start": 2835.79, "duration": 2.34}, {"text": "[MUSIC PLAYING]", "start": 2838.13, "duration": 3.96}, {"text": "I may not be OK.", "start": 2861.41, "duration": 1.663}, {"text": "The color's supposed to change.", "start": 2863.073, "duration": 1.292}, {"text": "[MUSIC PLAYING]", "start": 2864.365, "duration": 3.757}, {"text": "There we are.", "start": 2879.53, "duration": 1.15}, {"text": "Good?", "start": 2880.68, "duration": 2.3}, {"text": "I'm OK.", "start": 2882.98, "duration": 0.72}, {"text": "So what just happened?", "start": 2887.46, "duration": 2.52}, {"text": "AUDIENCE: You blew carbon\ndioxide into the water.", "start": 2892.888, "duration": 2.042}, {"text": "JOHN DOLHUN: I blew carbon\ndioxide in the water.", "start": 2894.93, "duration": 2.07}, {"text": "So we've got CO2 plus\nwater going to what?", "start": 2897.0, "duration": 8.764}, {"text": "Yeah.", "start": 2909.48, "duration": 0.71}, {"text": "AUDIENCE: Carbonic acid.", "start": 2910.19, "duration": 1.0}, {"text": "JOHN DOLHUN: Carbonic acid.", "start": 2911.19, "duration": 1.125}, {"text": "Good.", "start": 2912.315, "duration": 0.81}, {"text": "H2CO3, which breaks down\ninto H plus plus bicarbonate.", "start": 2913.125, "duration": 8.025}, {"text": "Now photosynthesis needs\ncarbon dioxide, right?", "start": 2924.29, "duration": 5.56}, {"text": "So we take that out\nof the equation,", "start": 2929.85, "duration": 2.77}, {"text": "which means we're also\ntaking out the H plus.", "start": 2932.62, "duration": 5.01}, {"text": "So does the pH go up or down?", "start": 2937.63, "duration": 2.066}, {"text": "AUDIENCE: Up.", "start": 2939.696, "duration": 0.914}, {"text": "JOHN DOLHUN: Alec?", "start": 2940.61, "duration": 1.19}, {"text": "Up, up, up.", "start": 2941.8, "duration": 1.19}, {"text": "OK?", "start": 2942.99, "duration": 0.66}, {"text": "Good.", "start": 2943.65, "duration": 0.96}, {"text": "And pollution and\npH, same thing.", "start": 2944.61, "duration": 3.37}, {"text": "If you've got pollution,\nyou've got all this vegetation.", "start": 2947.98, "duration": 3.5}, {"text": "So you've got photosynthesis,\nso the pH is going to be up.", "start": 2951.48, "duration": 3.66}, {"text": "This is Lassen Lake, Volcanic\nNational Park, pH 2, 2.0.", "start": 2957.88, "duration": 7.84}, {"text": "You do not want to stick\nyour foot into this lake.", "start": 2965.72, "duration": 3.35}, {"text": "And then you've got some\nsafety of the chemicals, which", "start": 2969.07, "duration": 4.83}, {"text": "the most serious is the\nazide reagent, which", "start": 2973.9, "duration": 4.68}, {"text": "it's a neurological toxin.", "start": 2978.58, "duration": 2.52}, {"text": "And if you ingest it,\nit can cause death.", "start": 2981.1, "duration": 3.52}, {"text": "So please be careful with that.", "start": 2984.62, "duration": 3.29}, {"text": "Sulfuric acid, you\nknow how bad that is.", "start": 2987.91, "duration": 2.94}, {"text": "You don't want to get it\nin your respiratory system.", "start": 2990.85, "duration": 2.67}, {"text": "And the manganese\nsulfate seems innocuous,", "start": 2993.52, "duration": 4.41}, {"text": "but it attacks the\ncentral nervous system,", "start": 2997.93, "duration": 3.18}, {"text": "targets blood and kidneys.", "start": 3001.11, "duration": 2.62}, {"text": "So be careful with that.", "start": 3003.73, "duration": 1.52}, {"text": "Sodium thiosulfate is\na respiratory irritant,", "start": 3005.25, "duration": 5.04}, {"text": "can cause breathing problems.", "start": 3010.29, "duration": 3.04}, {"text": "So if you feel like you're\nhaving breathing issues,", "start": 3013.33, "duration": 3.77}, {"text": "it could be that.", "start": 3017.1, "duration": 1.17}, {"text": "Biiodate can burn your eyes.", "start": 3018.27, "duration": 2.88}, {"text": "Very, very dangerous\nstuff around your eyes.", "start": 3021.15, "duration": 3.36}, {"text": "So all of these things, you\nhave to be careful with.", "start": 3024.51, "duration": 3.52}, {"text": "OK.", "start": 3028.03, "duration": 0.53}, {"text": "So we'll see you Thursday\nfor the last lecture", "start": 3028.56, "duration": 2.85}, {"text": "in this series.", "start": 3031.41, "duration": 1.85}]

transcripts/0XjWRilFPQY.json

@@ -0,0 +1 @@
+[{"text": "The following\ncontent is provided", "start": 0.61, "duration": 1.83}, {"text": "by MIT OpenCourseWare under\na Creative Commons license.", "start": 2.44, "duration": 3.9}, {"text": "Additional information about our\nlicense and MIT OpenCourseWare,", "start": 6.34, "duration": 3.78}, {"text": "in general, is available\nat OCW.MIT.edu.", "start": 10.12, "duration": 2.61}, {"text": "GEORGE CHURCH: OK,\nso welcome tonight,", "start": 22.51, "duration": 3.36}, {"text": "a very special lecture for\nme tonight in more ways", "start": 25.87, "duration": 4.18}, {"text": "than I can express.", "start": 30.05, "duration": 1.49}, {"text": "This is the last of my\nlectures, but I look forward", "start": 31.54, "duration": 2.22}, {"text": "to your lectures coming up.", "start": 33.76, "duration": 2.73}, {"text": "I really do.", "start": 36.49, "duration": 0.7}, {"text": "I've heard from the\nTFs, and from what", "start": 37.19, "duration": 1.82}, {"text": "I've seen from talking\nto many of you,", "start": 39.01, "duration": 2.14}, {"text": "this is going to be a really\namazing set of projects", "start": 41.15, "duration": 3.38}, {"text": "this year, more\nthan any other year.", "start": 44.53, "duration": 3.06}, {"text": "Anyway, last week, we asked what\ncan biology do for computing?", "start": 47.59, "duration": 7.77}, {"text": "And this week is going to be\na little less nuts and bolts", "start": 55.36, "duration": 3.93}, {"text": "than usual.", "start": 59.29, "duration": 0.69}, {"text": "The entire course--\nas you all understand,", "start": 59.98, "duration": 1.89}, {"text": "you're all self-selected\nto life survey", "start": 61.87, "duration": 2.399}, {"text": "courses, at least this one,\nbecause you're still here.", "start": 64.269, "duration": 3.781}, {"text": "And tonight's going to be more\nof a survey than ever before,", "start": 68.05, "duration": 3.856}, {"text": "and it's going to be talking\nabout topics for which we don't", "start": 71.906, "duration": 2.954}, {"text": "have answers for the most part.", "start": 74.86, "duration": 4.59}, {"text": "There'll be some interesting\ndetails along the way.", "start": 79.45, "duration": 3.63}, {"text": "But anyway, instead of what\nbiology can do for computing,", "start": 83.08, "duration": 3.96}, {"text": "this is more about what\nbiology and computing can", "start": 87.04, "duration": 2.52}, {"text": "do for the world.", "start": 89.56, "duration": 1.11}, {"text": "That's really what\nwe want to do,", "start": 90.67, "duration": 2.13}, {"text": "and also, the\nhigher level network", "start": 92.8, "duration": 2.61}, {"text": "models that we can build since\nthis is network number three.", "start": 95.41, "duration": 3.84}, {"text": "So we'll start out--", "start": 99.25, "duration": 1.46}, {"text": "we've been talking mainly about\ncellular models as our highest", "start": 100.71, "duration": 3.73}, {"text": "level of networking,\nand so we'll", "start": 104.44, "duration": 1.5}, {"text": "talk about multicellular\nmodels, in particular,", "start": 105.94, "duration": 3.22}, {"text": "the sort of multicellular\nmodels that you get that involve", "start": 109.16, "duration": 3.02}, {"text": "sensory integration and\nintegration of higher levels,", "start": 112.18, "duration": 6.93}, {"text": "and then all the way up to\nmulti-organ systems, where", "start": 119.11, "duration": 4.11}, {"text": "we'll take an example\nfrom the atomic scale,", "start": 123.22, "duration": 3.9}, {"text": "all the way up to\norgan system failure.", "start": 127.12, "duration": 4.77}, {"text": "And then we'll go from there.", "start": 131.89, "duration": 2.85}, {"text": "So let's start with\nmulticellular models.", "start": 134.74, "duration": 2.76}, {"text": "And this is something that I--", "start": 137.5, "duration": 4.38}, {"text": "I'll show you a few slides\nthat will remind you", "start": 141.88, "duration": 2.43}, {"text": "of the first lecture.", "start": 144.31, "duration": 1.282}, {"text": "They either were taken\nfrom the first lecture--", "start": 145.592, "duration": 1.958}, {"text": "in this case, this is a wildly\ndifferent author, and approach,", "start": 147.55, "duration": 3.43}, {"text": "and so forth, but\nit's the same lesson", "start": 150.98, "duration": 1.982}, {"text": "as from the first\nlecture, which is", "start": 152.962, "duration": 1.458}, {"text": "we not only have these\nexponential curves going", "start": 154.42, "duration": 2.19}, {"text": "through the 1900s, but\nthey're super exponential.", "start": 156.61, "duration": 2.19}, {"text": "They go up, and the\ntrend lines you get", "start": 158.8, "duration": 1.68}, {"text": "depend on which set of points\nyou use, the steepest one being", "start": 160.48, "duration": 3.21}, {"text": "the most recent one, 1995.", "start": 163.69, "duration": 2.31}, {"text": "And this basically\nis part of when", "start": 166.0, "duration": 1.74}, {"text": "it is that we will\nhave computing power", "start": 167.74, "duration": 2.85}, {"text": "that might be on the order of\nan integrated human neural net.", "start": 170.59, "duration": 5.67}, {"text": "We talked about neural nets\nlast time as a metaphor,", "start": 176.26, "duration": 2.76}, {"text": "or as an algorithm,\nbut when will", "start": 179.02, "duration": 3.24}, {"text": "we actually have a\ncomputer that has", "start": 182.26, "duration": 3.27}, {"text": "the capability of the\nhuman cerebral cortex,", "start": 185.53, "duration": 5.4}, {"text": "or entire integrated\nnervous system?", "start": 190.93, "duration": 2.19}, {"text": "And the basis of\nthose calculations", "start": 193.12, "duration": 2.4}, {"text": "that Moravec made,\nand in lecture one", "start": 195.52, "duration": 3.96}, {"text": "Kurzweil was the\nsuper exponential", "start": 199.48, "duration": 2.55}, {"text": "curve that I showed.", "start": 202.03, "duration": 1.35}, {"text": "Moravec made them\nbased on his studies", "start": 203.38, "duration": 3.33}, {"text": "on how the retina works.", "start": 206.71, "duration": 2.83}, {"text": "And I think those\nof you who have", "start": 209.54, "duration": 4.16}, {"text": "done a lot of\ncomputer programming,", "start": 213.7, "duration": 2.82}, {"text": "that understanding\nhow the retina works", "start": 216.52, "duration": 4.23}, {"text": "is probably one of\nthe more intuitive", "start": 220.75, "duration": 2.13}, {"text": "of our various human senses, in\nthe sense that you can program", "start": 222.88, "duration": 5.19}, {"text": "an algorithm that might do in\nthe lower right of slide four", "start": 228.07, "duration": 3.85}, {"text": "here, edge or motion detection.", "start": 231.92, "duration": 2.45}, {"text": "When a frog sees a fly, black\nand white, high contrast,", "start": 234.37, "duration": 4.77}, {"text": "zoom across its visual\nfield, something goes off.", "start": 239.14, "duration": 4.2}, {"text": "And you could write an\nalgorithm that could do that,", "start": 243.34, "duration": 2.49}, {"text": "given a few frames\nof any kind of form.", "start": 245.83, "duration": 4.3}, {"text": "So anyway, but there's been\nliterature on the subject.", "start": 250.13, "duration": 3.75}, {"text": "And when you go through even\nthe best algorithms right now", "start": 253.88, "duration": 3.11}, {"text": "for doing these\nkind of calculations", "start": 256.99, "duration": 2.43}, {"text": "and you figure out how\nlong it takes to do--", "start": 259.42, "duration": 5.04}, {"text": "the retina is doing about 10\nmillion detections per second.", "start": 264.46, "duration": 4.62}, {"text": "And then you scale up from\nthat 0.02 gram chunk of retina", "start": 269.08, "duration": 5.94}, {"text": "up to the 1,500\ngram human brain,", "start": 275.02, "duration": 4.05}, {"text": "then you get the extrapolation\nthat was in the previous slide.", "start": 279.07, "duration": 3.61}, {"text": "I think this is interesting\nboth as an introduction", "start": 282.68, "duration": 2.283}, {"text": "to the kind of algorithms we'd\nlike to think about when we", "start": 284.963, "duration": 2.417}, {"text": "think about integrating\na multicellular system,", "start": 287.38, "duration": 3.57}, {"text": "but also in terms of\nwhere the compute power", "start": 290.95, "duration": 4.5}, {"text": "both biological and\ncomputational is going.", "start": 295.45, "duration": 3.06}, {"text": "Do we want to engineer\nbiological systems", "start": 298.51, "duration": 3.99}, {"text": "to keep up with these silicon\nor whatever other computational", "start": 302.5, "duration": 4.77}, {"text": "system we're using a\ndecade or so from now.", "start": 307.27, "duration": 5.77}, {"text": "Now, so I said that\nthe visual system", "start": 313.04, "duration": 4.25}, {"text": "is a relatively intuitive\ncomputational system", "start": 317.29, "duration": 2.94}, {"text": "to program.", "start": 320.23, "duration": 1.36}, {"text": "In contrast, I would say\nthe olfactory system is less", "start": 321.59, "duration": 3.78}, {"text": "intuitive, at least for me.", "start": 325.37, "duration": 2.61}, {"text": "We know now quite a bit\nabout the molecular biology", "start": 327.98, "duration": 3.36}, {"text": "of the system.", "start": 331.34, "duration": 0.6}, {"text": "There are 1,000 receptors.", "start": 331.94, "duration": 1.47}, {"text": "It's probably one of the largest\nclasses of genomic repeated", "start": 333.41, "duration": 5.04}, {"text": "proteins.", "start": 338.45, "duration": 1.71}, {"text": "And these receptors\nare in the same family", "start": 340.16, "duration": 2.94}, {"text": "as the receptors that are\nthe major class of drug", "start": 343.1, "duration": 2.7}, {"text": "receptors, the G protein\ncoupled receptors.", "start": 345.8, "duration": 3.57}, {"text": "And there is\nbasically one receptor", "start": 349.37, "duration": 2.73}, {"text": "per cell, which is\nquite a trick, right?", "start": 352.1, "duration": 1.98}, {"text": "Because you got one receptor\nfrom mom and one from dad.", "start": 354.08, "duration": 2.88}, {"text": "And you've got\nthousands of receptors.", "start": 356.96, "duration": 2.28}, {"text": "But there's basically\none per cell.", "start": 359.24, "duration": 3.3}, {"text": "And they detect olfactory\nmolecule concentrations", "start": 362.54, "duration": 7.8}, {"text": "over about seven logs, where\nthey can detect a concentration", "start": 370.34, "duration": 11.16}, {"text": "threshold with a particular\nstandard deviation.", "start": 381.5, "duration": 4.74}, {"text": "Now this is the\nbeginnings of the model,", "start": 386.24, "duration": 1.8}, {"text": "just stating the fact\nthat you know about it.", "start": 388.04, "duration": 2.61}, {"text": "When you look at the\nneuroanatomy, you've got this--", "start": 390.65, "duration": 4.575}, {"text": "the odorant molecules\ndown at the very bottom", "start": 395.225, "duration": 1.875}, {"text": "of this figure, cilia\nolfactory neurons, which is", "start": 397.1, "duration": 4.8}, {"text": "a primary signal transduction.", "start": 401.9, "duration": 2.73}, {"text": "This thing goes up where it's\nintegrated in the glomeruli.", "start": 404.63, "duration": 4.11}, {"text": "And you can think of\nthis like the neural nets", "start": 408.74, "duration": 2.24}, {"text": "that we're talking\nabout last time, where", "start": 410.98, "duration": 1.708}, {"text": "you had these interneurons.", "start": 412.688, "duration": 1.512}, {"text": "You had the extra layer that\nwe showed was so important.", "start": 414.2, "duration": 7.08}, {"text": "And the thing that's\namazing about this system", "start": 421.28, "duration": 2.07}, {"text": "are lodged in these\nfour basic olfactory", "start": 423.35, "duration": 5.94}, {"text": "facts, which I take from\nHopfield's work, which", "start": 429.29, "duration": 3.81}, {"text": "is really just like this is the\nsame Hopfield that introduced", "start": 433.1, "duration": 3.63}, {"text": "us to or really championed\nthe concept of neural nets", "start": 436.73, "duration": 3.81}, {"text": "as a computational\nalgorithmic metaphor.", "start": 440.54, "duration": 3.36}, {"text": "And here, the idea is you have\nodor and memory recognition.", "start": 443.9, "duration": 6.51}, {"text": "You have background\nelimination, just", "start": 450.41, "duration": 2.7}, {"text": "like how your eyes adapt\nto a mostly red room,", "start": 453.11, "duration": 5.43}, {"text": "your nose is great, or\nwhole olfactory system", "start": 458.54, "duration": 3.87}, {"text": "is great at adapting\nto background odorants.", "start": 462.41, "duration": 4.8}, {"text": "So you have one known and\none unknown thoroughly mixed.", "start": 467.21, "duration": 4.62}, {"text": "Number three, you can\nhave component separation.", "start": 471.83, "duration": 2.73}, {"text": "You can have a few\ndifferent odors at once.", "start": 474.56, "duration": 3.12}, {"text": "You have odor separation\nwhere you have unknowns.", "start": 477.68, "duration": 5.535}, {"text": "I mean, the combination of\nthese is quite remarkable.", "start": 486.53, "duration": 4.24}, {"text": "So the basis of the model that\nHopfield has proposed is this.", "start": 490.77, "duration": 7.82}, {"text": "You have a coverage for\neach of the i receptors,", "start": 498.59, "duration": 4.38}, {"text": "where i goes from 1 to 1,000.", "start": 502.97, "duration": 2.1}, {"text": "This will vary depending\non the organism.", "start": 505.07, "duration": 2.01}, {"text": "Mice have twice as many as\nwe do, probably, and so on.", "start": 507.08, "duration": 3.31}, {"text": "But the coverage of\neach of those receptors", "start": 510.39, "duration": 6.14}, {"text": "is equal to the minimum\ncoverage for the concentration", "start": 516.53, "duration": 8.52}, {"text": "of the target, where let's\nsay the target is the target", "start": 525.05, "duration": 2.49}, {"text": "odorant that you're looking for\nover the concentration that's", "start": 527.54, "duration": 4.47}, {"text": "the threshold for firing\nthat neuron for that target,", "start": 532.01, "duration": 3.87}, {"text": "threshold of t.", "start": 535.88, "duration": 1.62}, {"text": "And you multiply that times\neither one or some fraction.", "start": 537.5, "duration": 3.72}, {"text": "It's 1 if you really\nhit the target.", "start": 541.22, "duration": 3.93}, {"text": "And it's this fraction for\nthat particular receptor", "start": 545.15, "duration": 4.47}, {"text": "and that particular target.", "start": 549.62, "duration": 1.53}, {"text": "You've got some crosstalk.", "start": 551.15, "duration": 1.47}, {"text": "And the amount of\ncrosstalk you can", "start": 552.62, "duration": 2.64}, {"text": "think of this as a field\nof receptors, which", "start": 555.26, "duration": 5.77}, {"text": "all have variable binding.", "start": 561.03, "duration": 2.06}, {"text": "And that binding is over\nthe six or seven logs here.", "start": 563.09, "duration": 4.12}, {"text": "And this just reflects\nthat same thing", "start": 567.21, "duration": 1.925}, {"text": "that we were talking about.", "start": 569.135, "duration": 1.125}, {"text": "So the total number\nof inputs going", "start": 572.96, "duration": 4.26}, {"text": "to the next layer in the\nneural net, the coverage here,", "start": 577.22, "duration": 2.97}, {"text": "is the sum of this target signal\nplus the background signal.", "start": 580.19, "duration": 7.33}, {"text": "So the first term is target.", "start": 587.52, "duration": 1.25}, {"text": "And the right hand\nterm is the background.", "start": 588.77, "duration": 1.99}, {"text": "And so you can see they have the\nsame form, the same threshold,", "start": 590.76, "duration": 2.96}, {"text": "and concentration. c sub b is\nconcentration of background.", "start": 593.72, "duration": 3.705}, {"text": "Now, so let's see\nhow this plays out", "start": 603.63, "duration": 3.66}, {"text": "when you actually try this\nout in an olfactory processing", "start": 607.29, "duration": 6.51}, {"text": "problem.", "start": 613.8, "duration": 0.66}, {"text": "Here you have an odor space.", "start": 614.46, "duration": 3.03}, {"text": "And what you have here\nis 80 different neurons", "start": 617.49, "duration": 5.67}, {"text": "is the y-axis at the\ntop of slide seven.", "start": 623.16, "duration": 3.63}, {"text": "And then across the x-axis\nis time in milliseconds going", "start": 626.79, "duration": 6.93}, {"text": "from 0 to 800 milliseconds.", "start": 633.72, "duration": 1.65}, {"text": "And this is all modeled on\nfairly realistic parameters", "start": 635.37, "duration": 5.67}, {"text": "based on experiments.", "start": 641.04, "duration": 2.7}, {"text": "And so what you have here\nis 80 adapting neurons.", "start": 643.74, "duration": 2.85}, {"text": "And what you're doing is\ntwo sniffs of a mixed odor.", "start": 646.59, "duration": 2.67}, {"text": "That's what this\nis modeling, OK?", "start": 649.26, "duration": 3.66}, {"text": "First, you have a 100 to 500\nmilliseconds, the range from--", "start": 652.92, "duration": 6.57}, {"text": "so you can see that something's\nhappening at 100 milliseconds.", "start": 659.49, "duration": 3.33}, {"text": "And up to 500 you\nhave a mixed odor,", "start": 662.82, "duration": 2.34}, {"text": "which is 50 parts of x\nplus 1,000 parts of y,", "start": 665.16, "duration": 4.17}, {"text": "or 1,000 times y.", "start": 669.33, "duration": 5.22}, {"text": "And then 500 milliseconds\nyou change this ratio very", "start": 674.55, "duration": 3.63}, {"text": "slightly, you see?", "start": 678.18, "duration": 0.96}, {"text": "You just up x by 75 and\ny up from 1,000 to 1,100.", "start": 679.14, "duration": 8.21}, {"text": "OK, so that's the paradigm,\n50 and 1,000 to 75 and 1,100.", "start": 687.35, "duration": 6.06}, {"text": "And the sniff at 100\nmilliseconds, that first one,", "start": 693.41, "duration": 3.93}, {"text": "that mixed odorant, it activates\nmore than half the neurons.", "start": 697.34, "duration": 5.35}, {"text": "So this is not like\nyour retina, where", "start": 702.69, "duration": 2.48}, {"text": "if you have a\nsingle point source", "start": 705.17, "duration": 2.01}, {"text": "it will activate that one\nbroad cell, or maybe a center", "start": 707.18, "duration": 4.89}, {"text": "surround effect.", "start": 712.07, "duration": 2.31}, {"text": "But it's really activating\nhalf of the neurons, OK?", "start": 714.38, "duration": 3.45}, {"text": "And then the changed sniff at\n500 milliseconds-- remember,", "start": 717.83, "duration": 3.09}, {"text": "just these two small changes--", "start": 720.92, "duration": 2.07}, {"text": "is almost invisible, right?", "start": 722.99, "duration": 3.36}, {"text": "So that's what you're\nseeing right here,", "start": 726.35, "duration": 5.37}, {"text": "OK, is this huge,\nswamping amount.", "start": 731.72, "duration": 4.68}, {"text": "But then in B-- so that's\nwhat happened in A. B,", "start": 736.4, "duration": 5.55}, {"text": "you've now plotting instead\nof individual neurons,", "start": 741.95, "duration": 4.71}, {"text": "you're doing the instantaneous\nrate in hertz, OK?", "start": 746.66, "duration": 3.81}, {"text": "And now, you can see\nthe second sniff here", "start": 750.47, "duration": 7.74}, {"text": "at the 500 milliseconds,\nwhich even though you really", "start": 758.21, "duration": 2.85}, {"text": "can't see it in the\ncorresponding point", "start": 761.06, "duration": 1.782}, {"text": "where you're looking at all\nthese individual neurons.", "start": 762.842, "duration": 2.208}, {"text": "And so you can see that\neven a 20% spread in one", "start": 765.05, "duration": 6.27}, {"text": "of these parameters is enough\nto get this kind of easily", "start": 771.32, "duration": 5.55}, {"text": "detectable signal.", "start": 776.87, "duration": 2.4}, {"text": "Now, that's an example\nof a simulation.", "start": 779.27, "duration": 2.46}, {"text": "That's not a simulation of\na particular experimental", "start": 781.73, "duration": 3.12}, {"text": "dataset, but it's based\non experimental datasets.", "start": 784.85, "duration": 3.06}, {"text": "And the code, this\nis not Mathematica,", "start": 787.91, "duration": 1.92}, {"text": "this is Matlab,\nwhich we all wish", "start": 789.83, "duration": 2.22}, {"text": "we could have interchangeably\ntaught in this course.", "start": 792.05, "duration": 2.88}, {"text": "And you can see here in\ngreen are the comments.", "start": 794.93, "duration": 2.28}, {"text": "And you can see\nsome of the things", "start": 797.21, "duration": 1.47}, {"text": "that we've been\ntalking about here.", "start": 798.68, "duration": 1.458}, {"text": "The number of receptor\ntypes is actually", "start": 803.673, "duration": 1.667}, {"text": "here 2,000 instead of 1,000.", "start": 805.34, "duration": 2.04}, {"text": "You see the target,\nremember, I said", "start": 807.38, "duration": 2.34}, {"text": "could be some random number\nthat goes over six logarithms.", "start": 809.72, "duration": 3.995}, {"text": "Well, the way\nthat's done here is", "start": 813.715, "duration": 1.375}, {"text": "here's a random number\ngenerated and you generate", "start": 815.09, "duration": 4.628}, {"text": "as the log of the target.", "start": 819.718, "duration": 1.042}, {"text": "And then, you get the target\nby taking the exponential.", "start": 820.76, "duration": 2.292}, {"text": "It's very straightforward and\nthe code goes on from there.", "start": 823.052, "duration": 4.828}, {"text": "OK, now this brings us to\na very interesting point.", "start": 827.88, "duration": 4.88}, {"text": "Since these three\nlectures on networks,", "start": 832.76, "duration": 2.622}, {"text": "and in a certain sense,\nthe whole course,", "start": 835.382, "duration": 1.708}, {"text": "is building towards systems\nbiology network models.", "start": 837.09, "duration": 4.16}, {"text": "And for these\nmodels to be useful,", "start": 841.25, "duration": 1.92}, {"text": "in the same sense that\nthe models we have", "start": 843.17, "duration": 1.832}, {"text": "for X-ray crystallography,\nand the models", "start": 845.002, "duration": 1.708}, {"text": "we've had for genome\ninterpretation in terms", "start": 846.71, "duration": 2.61}, {"text": "of homology, and\nsequence folding,", "start": 849.32, "duration": 3.42}, {"text": "and so forth needed\nto be shared.", "start": 852.74, "duration": 3.72}, {"text": "The models, even\nmore than the data,", "start": 856.46, "duration": 1.95}, {"text": "need to be shareable\nbecause in a certain sense,", "start": 858.41, "duration": 4.23}, {"text": "even modest\nmanipulation of the data", "start": 862.64, "duration": 2.94}, {"text": "usually involves some\ngood model behind it.", "start": 865.58, "duration": 2.323}, {"text": "And so these are some\nof the work groups", "start": 867.903, "duration": 1.667}, {"text": "that are working on\ndifferent modeling schemes.", "start": 869.57, "duration": 3.27}, {"text": "In particular, I\nshould point out", "start": 872.84, "duration": 2.535}, {"text": "that BioSpice is\nnow DARPA BioSpice,", "start": 875.375, "duration": 3.195}, {"text": "and SBML is kind of a\ngrowing part of that.", "start": 878.57, "duration": 3.0}, {"text": "System Biology Markup Language\nis a way of sharing this data.", "start": 881.57, "duration": 3.66}, {"text": "And as yet, there's not\nthe kind of convention", "start": 885.23, "duration": 3.6}, {"text": "that we have in\ncrystallography and DNA", "start": 888.83, "duration": 3.24}, {"text": "sequencing where you submit--", "start": 892.07, "duration": 1.818}, {"text": "at the time that\nyou publish a paper,", "start": 893.888, "duration": 1.542}, {"text": "you submit your data\nand model, data/model,", "start": 895.43, "duration": 4.41}, {"text": "with an accession number\nto the database or else", "start": 899.84, "duration": 2.58}, {"text": "you don't get it published.", "start": 902.42, "duration": 1.14}, {"text": "We're nowhere near that now\nfor the rest of biology.", "start": 903.56, "duration": 2.43}, {"text": "But these kind of\nefforts, probably,", "start": 905.99, "duration": 2.22}, {"text": "are moving in that direction.", "start": 908.21, "duration": 1.27}, {"text": "And you can see that the\nfeatures of each of these", "start": 909.48, "duration": 3.115}, {"text": "are some of the\nthings that we've", "start": 912.595, "duration": 1.375}, {"text": "been talking about before.", "start": 913.97, "duration": 1.083}, {"text": "You've got stochastic\nmodeling, kinetic modeling,", "start": 915.053, "duration": 3.927}, {"text": "enzyme receptor cell geometry,\nneural nets, and so on.", "start": 918.98, "duration": 11.37}, {"text": "This is by no means\ncomprehensive.", "start": 930.35, "duration": 1.96}, {"text": "And there are hypertext\nlinks here if you really", "start": 932.31, "duration": 2.0}, {"text": "want to dig into them.", "start": 934.31, "duration": 1.38}, {"text": "And some of the\nplatforms that they've", "start": 935.69, "duration": 1.83}, {"text": "been thinking about different\nways of making it slightly less", "start": 937.52, "duration": 4.74}, {"text": "system-dependent.", "start": 942.26, "duration": 1.17}, {"text": "Everyone has their attempts.", "start": 943.43, "duration": 2.1}, {"text": "Obviously, Windows is\nnot system-independent.", "start": 945.53, "duration": 4.89}, {"text": "So that's two very\nbrief examples", "start": 950.42, "duration": 3.0}, {"text": "of multicellular models, both\nof them being neural models", "start": 953.42, "duration": 5.55}, {"text": "kind of building from what we\nwere thinking about last time.", "start": 958.97, "duration": 2.67}, {"text": "But now we're going to a\ncompletely different kind", "start": 961.64, "duration": 2.22}, {"text": "of multicellular model, all the\nway up from individual effects", "start": 963.86, "duration": 5.19}, {"text": "that a single nucleotide-- how\nmuch effect a single nucleotide", "start": 969.05, "duration": 3.45}, {"text": "can have on a whole organ\nsystem, which in this case", "start": 972.5, "duration": 3.48}, {"text": "will be cardiovascular.", "start": 975.98, "duration": 1.96}, {"text": "So we go from--.", "start": 977.94, "duration": 2.33}, {"text": "And there are a number of\nphysiome and cardiome projects", "start": 980.27, "duration": 5.79}, {"text": "that are of active interest.", "start": 986.06, "duration": 2.77}, {"text": "Just like the\nprevious slides that I", "start": 992.44, "duration": 1.95}, {"text": "showed showing all the ways\nof sharing system models,", "start": 994.39, "duration": 2.94}, {"text": "many of these efforts are kind\nof loose consortium alliances", "start": 997.33, "duration": 6.12}, {"text": "where people have put together\ndifferent models either to deal", "start": 1003.45, "duration": 4.44}, {"text": "with the anatomy,\nphysiology, or sometimes,", "start": 1007.89, "duration": 4.98}, {"text": "a integration of molecular to\ncellular, cellular to, say,", "start": 1012.87, "duration": 7.71}, {"text": "neural or muscular, and all\nthe way up to fluid dynamics", "start": 1020.58, "duration": 4.71}, {"text": "and so on.", "start": 1025.29, "duration": 3.069}, {"text": "So let's start with a\nsingle base-pair change.", "start": 1028.359, "duration": 3.951}, {"text": "And I start with\nthis one because you", "start": 1032.31, "duration": 2.683}, {"text": "should feel comfortable\nwith it at this point.", "start": 1034.993, "duration": 1.917}, {"text": "We mentioned it briefly before.", "start": 1036.91, "duration": 3.05}, {"text": "We'll talk about it\nin more detail now.", "start": 1039.96, "duration": 2.04}, {"text": "This is the single\nnucleotide polymorphism,", "start": 1042.0, "duration": 2.589}, {"text": "which causes the change of the\nbeta subunit of hemoglobin,", "start": 1044.589, "duration": 5.751}, {"text": "which is a tetramer,\nto go from a glutamate,", "start": 1050.34, "duration": 6.69}, {"text": "normally, in most people at\nposition six of the beta chain,", "start": 1057.03, "duration": 3.42}, {"text": "to a valine.", "start": 1060.45, "duration": 2.52}, {"text": "So that's the purple\nset of tetramers.", "start": 1062.97, "duration": 3.21}, {"text": "Or to tryptophan, and that's\nthe cyan set on the far right.", "start": 1066.18, "duration": 5.22}, {"text": "And this, from combinations\nof X-ray crystallography", "start": 1071.4, "duration": 8.27}, {"text": "and three-dimensional\nmodeling, and this", "start": 1079.67, "duration": 2.19}, {"text": "is not speculation, just based\non primary sequence data,", "start": 1081.86, "duration": 3.09}, {"text": "even though the primary sequence\nhere is very, very close,", "start": 1084.95, "duration": 3.12}, {"text": "just a single nucleotide and\na single amino acid change.", "start": 1088.07, "duration": 4.33}, {"text": "Nevertheless, these\nauthors have been", "start": 1092.4, "duration": 2.21}, {"text": "building this from the\ncrystallographic data", "start": 1094.61, "duration": 4.23}, {"text": "where not only do you care\nabout the tetramer itself,", "start": 1098.84, "duration": 3.36}, {"text": "but how the tetramers\ninteract with one another", "start": 1102.2, "duration": 2.61}, {"text": "to make these long, fibrous\nchains, which are considerably", "start": 1104.81, "duration": 3.69}, {"text": "more stable in the sickle cell.", "start": 1108.5, "duration": 2.82}, {"text": "And what you see here is sort\nof the valine substitution", "start": 1111.32, "duration": 7.86}, {"text": "is locked in one\nkind of conformation", "start": 1119.18, "duration": 2.58}, {"text": "and the tryptophan in another.", "start": 1121.76, "duration": 2.53}, {"text": "And you can see\nhow these authors", "start": 1124.29, "duration": 2.81}, {"text": "have decided how a\npotential fiber can", "start": 1127.1, "duration": 4.02}, {"text": "form in the different cases.", "start": 1131.12, "duration": 2.16}, {"text": "Now those fibers, in\none way or another,", "start": 1137.11, "duration": 2.76}, {"text": "which is not totally\nmapped out, but you", "start": 1139.87, "duration": 5.52}, {"text": "affect the efficiency of\nthe hemoglobin slightly", "start": 1145.39, "duration": 5.35}, {"text": "and the shape of the\ncell much more radically.", "start": 1150.74, "duration": 3.2}, {"text": "And this combination\nresults in the cell,", "start": 1153.94, "duration": 5.26}, {"text": "especially under any kind\nof stress, either oxidative", "start": 1159.2, "duration": 3.89}, {"text": "or other metabolic\nstress, becoming sickled.", "start": 1163.09, "duration": 2.82}, {"text": "So you can have a combination\nof cells which have", "start": 1165.91, "duration": 3.42}, {"text": "varying degrees of sickling.", "start": 1169.33, "duration": 1.68}, {"text": "Here in this microscopic\nslide on the left,", "start": 1171.01, "duration": 6.42}, {"text": "you have both the sickle\ncell and the normal cell side", "start": 1177.43, "duration": 2.7}, {"text": "by side.", "start": 1180.13, "duration": 2.08}, {"text": "I think when we built up the\nred blood cell metabolic model,", "start": 1182.21, "duration": 3.05}, {"text": "we talked about some of the\nnon-metabolic considerations", "start": 1185.26, "duration": 2.79}, {"text": "of that, which were that its\nfunction is to transport oxygen", "start": 1188.05, "duration": 4.23}, {"text": "and so forth.", "start": 1192.28, "duration": 2.4}, {"text": "And what we're talking about now\nis more a cell membrane issue.", "start": 1194.68, "duration": 3.65}, {"text": "This is on slide 13, where the\ninternal environment, which", "start": 1198.33, "duration": 5.35}, {"text": "is the hemoglobin, is\ngreatly affecting now", "start": 1203.68, "duration": 2.37}, {"text": "the external environment,\nwhich is the hemodynamic flow", "start": 1206.05, "duration": 3.12}, {"text": "in the capillaries.", "start": 1209.17, "duration": 3.15}, {"text": "So this falls under\nthe heading now", "start": 1215.68, "duration": 2.16}, {"text": "of how is it that we can go from\nthat single nucleotide change", "start": 1217.84, "duration": 3.72}, {"text": "to a very dramatic\nmorphological change?", "start": 1221.56, "duration": 2.16}, {"text": "In this case, it's\npathological, but you", "start": 1223.72, "duration": 2.25}, {"text": "could imagine that in the hands\nof evolutionary adaptation,", "start": 1225.97, "duration": 4.917}, {"text": "an organism could take\nthis and run with it.", "start": 1230.887, "duration": 1.833}, {"text": "Maybe not sickle cell mutation,\nbut some other one that", "start": 1232.72, "duration": 2.46}, {"text": "causes some other morphological\nchange in some other cell", "start": 1235.18, "duration": 2.88}, {"text": "or complex aggregate of cells.", "start": 1238.06, "duration": 3.06}, {"text": "Because here you can see a whole\nvariety of different shapes", "start": 1241.12, "duration": 6.63}, {"text": "of red blood cells.", "start": 1247.75, "duration": 2.043}, {"text": "And remember, these red\nblood cells are very simple.", "start": 1249.793, "duration": 2.167}, {"text": "They have no macromolecular\n[INAUDIBLE],, no DNA, no RNA,", "start": 1251.96, "duration": 4.94}, {"text": "so we're really just talking\nabout a bag of proteins which", "start": 1256.9, "duration": 2.64}, {"text": "are greatly affected by\nthese different conditions", "start": 1259.54, "duration": 4.05}, {"text": "or enzyme deficiencies.", "start": 1263.59, "duration": 1.87}, {"text": "So the system models\nthat were built up,", "start": 1265.46, "duration": 1.82}, {"text": "where we had the kinetic\nparameters for the enzymes,", "start": 1267.28, "duration": 4.17}, {"text": "here can, in principle, be\nmodeled on the impact it would", "start": 1271.45, "duration": 4.65}, {"text": "have on the osmolarity, or the\nother membrane properties that", "start": 1276.1, "duration": 5.22}, {"text": "were listed in the\nprevious slide,", "start": 1281.32, "duration": 1.59}, {"text": "or the sickling that\nwas in two slides back.", "start": 1282.91, "duration": 2.34}, {"text": "So from a single\nnucleotide polymorphism,", "start": 1296.68, "duration": 5.13}, {"text": "we've gone from this\nthree-dimensional fiber", "start": 1301.81, "duration": 2.43}, {"text": "of hemoglobin to a change in\nthe three-dimensional structure", "start": 1304.24, "duration": 5.76}, {"text": "of this biconcave\ndisk to a sickle disk.", "start": 1310.0, "duration": 7.02}, {"text": "But you can also go,\nsort of in parallel,", "start": 1317.02, "duration": 2.52}, {"text": "the same single-nucleotide\npolymorphism, or some like it,", "start": 1319.54, "duration": 3.42}, {"text": "can take you up to\npathogen resistance.", "start": 1322.96, "duration": 2.79}, {"text": "We've already mentioned that\nsickle cell hemoglobin can take", "start": 1325.75, "duration": 3.75}, {"text": "you to malarial resistance.", "start": 1329.5, "duration": 2.19}, {"text": "But in addition, you\ncan get components", "start": 1331.69, "duration": 7.32}, {"text": "of the enzymatic\nmetabolic pathway,", "start": 1339.01, "duration": 3.85}, {"text": "such as the one that we\nmodeled a few lectures back,", "start": 1342.86, "duration": 6.08}, {"text": "such as glutathione peroxidase.", "start": 1348.94, "duration": 1.69}, {"text": "This is part of the\nredox components.", "start": 1350.63, "duration": 4.52}, {"text": "And here, erythrocytes\nthat are heterozygous", "start": 1355.15, "duration": 3.96}, {"text": "for this particular\nallele should", "start": 1359.11, "duration": 7.12}, {"text": "be more efficient in\nsheltering the cell membrane", "start": 1366.23, "duration": 2.16}, {"text": "from irreversible oxidation\nin binding hemoglobin caused", "start": 1368.39, "duration": 2.7}, {"text": "by the oxidant\nstress that's exerted", "start": 1371.09, "duration": 2.04}, {"text": "by the malarial parasite.", "start": 1373.13, "duration": 4.53}, {"text": "And what they observe\nhere is actually", "start": 1377.66, "duration": 2.25}, {"text": "an interaction between these\ntwo possible haplotypes.", "start": 1379.91, "duration": 7.56}, {"text": "So it's actually, you can think\nof it as a pair of haplotypes.", "start": 1387.47, "duration": 2.61}, {"text": "It's the one is\nthe hemoglobin AS,", "start": 1390.08, "duration": 4.8}, {"text": "the one we've been talking\nabout for sickling,", "start": 1394.88, "duration": 3.12}, {"text": "and then, this\nglutathione peroxidase.", "start": 1398.0, "duration": 2.88}, {"text": "And so you can imagine, that\nsince both of these things", "start": 1400.88, "duration": 2.76}, {"text": "interact with malaria\nparasite, that your genotype", "start": 1403.64, "duration": 3.39}, {"text": "will depend--", "start": 1407.03, "duration": 0.87}, {"text": "I'm sorry, your phenotype\nin respect to malaria", "start": 1407.9, "duration": 2.16}, {"text": "will depend on the alleles\nthat you have at both cases.", "start": 1410.06, "duration": 3.517}, {"text": "So you can-- here, you can\nhave an A over S heterozygote", "start": 1413.577, "duration": 2.333}, {"text": "and a two over one heterozygote.", "start": 1415.91, "duration": 3.337}, {"text": "And so that's something to\ntake into account when you're", "start": 1419.247, "duration": 2.333}, {"text": "trying to do any kind of\npredictive modeling or modeling", "start": 1421.58, "duration": 4.59}, {"text": "to explain the functional\ngenomics that you", "start": 1426.17, "duration": 3.03}, {"text": "have in a patient who's\na compound heterozygote", "start": 1429.2, "duration": 2.64}, {"text": "like that.", "start": 1431.84, "duration": 1.54}, {"text": "So now, the third pathway.", "start": 1433.38, "duration": 2.21}, {"text": "Now, from single-- the same\nset of single nucleotide", "start": 1435.59, "duration": 2.37}, {"text": "polymorphisms that\naffect either hemoglobin", "start": 1437.96, "duration": 1.83}, {"text": "or one of the major enzymes\nin the red blood cell.", "start": 1439.79, "duration": 3.01}, {"text": "Now, on to cell morphology.", "start": 1442.8, "duration": 3.5}, {"text": "On to pathogen interaction.", "start": 1446.3, "duration": 3.39}, {"text": "And finally, to\ninteraction with drugs.", "start": 1449.69, "duration": 1.98}, {"text": "We talked about\npharmacogenomics.", "start": 1451.67, "duration": 1.62}, {"text": "Here's another example where you\nhave the drug-induced oxidative", "start": 1453.29, "duration": 6.36}, {"text": "hemolysis that you occur\nwith certain enzymopathies", "start": 1459.65, "duration": 4.68}, {"text": "like glucose-6-phosphate\ndehydrogenase.", "start": 1464.33, "duration": 4.14}, {"text": "This enzyme, glucose-6-phosphate\ndehydrogenase,", "start": 1468.47, "duration": 4.08}, {"text": "interacts with drugs\nsuch as primaquine.", "start": 1472.55, "duration": 4.11}, {"text": "And it disrupts mitochondrial\nfunction, heme biosynthesis,", "start": 1476.66, "duration": 6.04}, {"text": "and so forth, and so on.", "start": 1482.7, "duration": 3.0}, {"text": "This is a very\nsignificant consideration", "start": 1485.7, "duration": 6.02}, {"text": "with a long list\nof 20-some drugs", "start": 1491.72, "duration": 2.7}, {"text": "that has to be taken\nto account when", "start": 1494.42, "duration": 2.04}, {"text": "you have any of a variety of\nred blood cell enzyme changes.", "start": 1496.46, "duration": 7.03}, {"text": "So we've got these three\neffects of a limited number", "start": 1503.49, "duration": 4.67}, {"text": "of single nucleotide\npolymorphisms.", "start": 1508.16, "duration": 3.15}, {"text": "How do you make this\ntransition from--", "start": 1511.31, "duration": 5.55}, {"text": "and they're all\nsomewhat interconnected.", "start": 1516.86, "duration": 1.71}, {"text": "Part of the reason it's\nresistant to malaria", "start": 1518.57, "duration": 1.833}, {"text": "is because it's less\neffective in its cell", "start": 1520.403, "duration": 1.947}, {"text": "shape, and its ability to\ntransport oxygen, and do", "start": 1522.35, "duration": 5.4}, {"text": "its metabolism.", "start": 1527.75, "duration": 1.7}, {"text": "And same thing with\ndrug sensitivity.", "start": 1529.45, "duration": 3.01}, {"text": "How are these changes\nin the hemoglobin--", "start": 1532.46, "duration": 7.29}, {"text": "might they be reflected in\nthe three-dimensional shape", "start": 1539.75, "duration": 2.94}, {"text": "of the erythrocyte,\nwhich is a kind", "start": 1542.69, "duration": 2.67}, {"text": "of a membrane-bound compartment?", "start": 1545.36, "duration": 2.58}, {"text": "And here's a model that\nstruck me as interesting.", "start": 1547.94, "duration": 2.58}, {"text": "It's not been that\nextensively tested since 1998.", "start": 1550.52, "duration": 5.62}, {"text": "But the idea is that Band3--", "start": 1556.14, "duration": 2.69}, {"text": "this is one of those\nnames that just comes out", "start": 1558.83, "duration": 2.43}, {"text": "of the molecular\nbiologist literature,", "start": 1561.26, "duration": 3.06}, {"text": "that they ran a\ngel, and they count", "start": 1564.32, "duration": 2.01}, {"text": "the bands, and number three.", "start": 1566.33, "duration": 1.77}, {"text": "And it turns out it's about 10%\nof the red blood cell membrane.", "start": 1568.1, "duration": 5.28}, {"text": "It's a very abundant protein.", "start": 1573.38, "duration": 3.27}, {"text": "And it's responsible\nfor the equilibration", "start": 1576.65, "duration": 4.02}, {"text": "of anions such as carbonate and\nchloride across the red blood", "start": 1580.67, "duration": 3.81}, {"text": "cell membrane.", "start": 1584.48, "duration": 1.26}, {"text": "It's not a pump, it just\nkind of allows these anions", "start": 1585.74, "duration": 3.42}, {"text": "to go across because\nthe pump here", "start": 1589.16, "duration": 2.04}, {"text": "is the pumps that are\ninvolved in proton", "start": 1591.2, "duration": 2.97}, {"text": "and there's also\nsodium potassium.", "start": 1594.17, "duration": 3.57}, {"text": "And that's what your ATP in the\nred blood cell is going for.", "start": 1597.74, "duration": 2.58}, {"text": "And these are just kind\nof following along.", "start": 1600.32, "duration": 1.792}, {"text": "The idea here is that if\nyou change the degree--", "start": 1604.46, "duration": 9.73}, {"text": "let's see, I think this\nis covered in more detail.", "start": 1614.19, "duration": 3.248}, {"text": "No, sorry.", "start": 1617.438, "duration": 1.332}, {"text": "The mechanism of\naction here is greatly", "start": 1622.405, "duration": 3.265}, {"text": "affected by its\ndisulfide effects.", "start": 1625.67, "duration": 3.18}, {"text": "And if you change the redox\ncomponents in the red blood", "start": 1628.85, "duration": 4.74}, {"text": "cell, you get just a slight\nchange in conformation", "start": 1633.59, "duration": 3.81}, {"text": "of this molecule.", "start": 1637.4, "duration": 1.44}, {"text": "And then that can result\nin a net difference", "start": 1638.84, "duration": 3.3}, {"text": "between the cross-sectional area\nof this protein on the outside", "start": 1642.14, "duration": 3.9}, {"text": "and the inside, which\ntranslates into a net change--", "start": 1646.04, "duration": 3.78}, {"text": "since the phospholipids\ndon't exchange,", "start": 1649.82, "duration": 4.457}, {"text": "or the rate constant for\nthe phospholipid exchange", "start": 1654.277, "duration": 2.083}, {"text": "is slow and known,\nthen this results", "start": 1656.36, "duration": 2.4}, {"text": "in a conformational change.", "start": 1658.76, "duration": 7.14}, {"text": "Anyway, that's the model.", "start": 1665.9, "duration": 2.94}, {"text": "That connects the\nsingle nucleotide to--", "start": 1668.84, "duration": 3.06}, {"text": "could connect it to the\nthree-dimensional structure", "start": 1671.9, "duration": 3.0}, {"text": "of the cell.", "start": 1674.9, "duration": 0.87}, {"text": "Then you want to connect the\nthree-dimensional structure", "start": 1675.77, "duration": 2.333}, {"text": "of the cell to its ability\nto carry out its function", "start": 1678.103, "duration": 3.457}, {"text": "in the capillaries.", "start": 1681.56, "duration": 1.26}, {"text": "And its function there\nis to allow the fusion", "start": 1682.82, "duration": 3.57}, {"text": "of oxygen and carbon dioxide.", "start": 1686.39, "duration": 6.18}, {"text": "So here, each of these cells is\nshaped by a mechanical process.", "start": 1702.52, "duration": 6.03}, {"text": "A mechanical process\nhere, you can", "start": 1708.55, "duration": 1.8}, {"text": "take the known or the\nmeasurable mechanical properties", "start": 1710.35, "duration": 5.67}, {"text": "of a red blood cell\nand subject them", "start": 1716.02, "duration": 3.21}, {"text": "to a method called finite\nelements analysis where", "start": 1719.23, "duration": 5.94}, {"text": "you're solving these partial\ndifferentiable equations.", "start": 1725.17, "duration": 4.62}, {"text": "And you can calculate the\nexchange of the oxygen--", "start": 1729.79, "duration": 5.71}, {"text": "alveolar just refers to--\nthis would be in the lungs.", "start": 1739.27, "duration": 2.455}, {"text": "This would be a small\ncapillary in the lungs.", "start": 1741.725, "duration": 1.875}, {"text": "And you can see\nthe capillary now,", "start": 1743.6, "duration": 1.417}, {"text": "the endothelial walls are close\nenough so that the red blood", "start": 1745.017, "duration": 2.653}, {"text": "cells are basically\ndeformed in their shape", "start": 1747.67, "duration": 3.158}, {"text": "as they go through there.", "start": 1750.828, "duration": 1.042}, {"text": "And the exact shapes that\nare compatible with this", "start": 1751.87, "duration": 2.82}, {"text": "will determine the rate that\nthese little arrows that", "start": 1754.69, "duration": 2.55}, {"text": "go from the oxygen on the\noutside the lung epithelium", "start": 1757.24, "duration": 4.23}, {"text": "get through to the blood cell.", "start": 1761.47, "duration": 2.89}, {"text": "So that's a reference that\ndeals with that kind of problem.", "start": 1764.36, "duration": 6.77}, {"text": "Now, as we start thinking about\nbuilding up a larger system", "start": 1771.13, "duration": 8.45}, {"text": "model, the other parts of\nthe system, each of them--", "start": 1779.58, "duration": 2.52}, {"text": "so we've got a red\nblood cell model,", "start": 1782.1, "duration": 1.5}, {"text": "it's the metabolic model.", "start": 1783.6, "duration": 1.042}, {"text": "In principle, it could also be\na shape model and a diffusion", "start": 1784.642, "duration": 4.358}, {"text": "model.", "start": 1789.0, "duration": 1.26}, {"text": "But the other\nparts of the system", "start": 1790.26, "duration": 3.1}, {"text": "typically involve muscle cells.", "start": 1793.36, "duration": 4.65}, {"text": "They have the smooth muscles\nthroughout the entire arterial", "start": 1798.01, "duration": 9.82}, {"text": "and venous system, and most\nsignificantly, the heart", "start": 1807.83, "duration": 4.99}, {"text": "muscles.", "start": 1812.82, "duration": 0.93}, {"text": "And so here you have an example\nof action potential in one", "start": 1813.75, "duration": 6.12}, {"text": "of the ventricular\ncells of the dog heart.", "start": 1819.87, "duration": 3.51}, {"text": "And it includes all the\ncomponents that at least we,", "start": 1823.38, "duration": 4.35}, {"text": "since this is not an entire\ncourse on ventricular heart", "start": 1827.73, "duration": 6.73}, {"text": "modeling.", "start": 1834.46, "duration": 2.43}, {"text": "This is the sort of\nparameters, in terms", "start": 1836.89, "duration": 2.34}, {"text": "of all the I to the currents for\neach of the different potassium", "start": 1839.23, "duration": 3.39}, {"text": "channels to K, all of--\neach of the ones at I", "start": 1842.62, "duration": 3.36}, {"text": "sub K was all potassium.", "start": 1845.98, "duration": 2.7}, {"text": "And then there's some in sodium,\nand sodium and calcium, calcium", "start": 1848.68, "duration": 3.87}, {"text": "potassium, sodium alone.", "start": 1852.55, "duration": 2.057}, {"text": "And so each of these things,\nthat internal storage", "start": 1854.607, "duration": 2.083}, {"text": "of calcium [INAUDIBLE] from\none subcellular compartment", "start": 1856.69, "duration": 3.21}, {"text": "to another and so on.", "start": 1859.9, "duration": 3.31}, {"text": "You get the idea.", "start": 1863.21, "duration": 0.71}, {"text": "Each of these things has to\nhave the parameters measured.", "start": 1863.92, "duration": 3.21}, {"text": "And any of that are\nabsent, you have", "start": 1867.13, "duration": 3.03}, {"text": "to have reasonable ways\nof getting surrogates.", "start": 1870.16, "duration": 6.51}, {"text": "And so this is just\nthe sort of data", "start": 1876.67, "duration": 3.66}, {"text": "that would go into the other\nmajor type of cell that", "start": 1880.33, "duration": 4.14}, {"text": "comes into this\ncardiovascular modeling.", "start": 1884.47, "duration": 4.92}, {"text": "And finally, you can\nintegrate this up", "start": 1889.39, "duration": 3.87}, {"text": "to a fairly complete system.", "start": 1893.26, "duration": 2.76}, {"text": "It's obviously not\ncomplete until you", "start": 1896.02, "duration": 1.56}, {"text": "get to the whole organism,\nbut higher level,", "start": 1897.58, "duration": 2.88}, {"text": "and how we're talking about\nwhole body recirculation.", "start": 1900.46, "duration": 3.8}, {"text": "This NSR group, this\nis a hypertext link", "start": 1904.26, "duration": 3.28}, {"text": "for this particular model\nwhich you can download.", "start": 1907.54, "duration": 3.39}, {"text": "And it has a\nfour-chambered heart.", "start": 1910.93, "duration": 1.57}, {"text": "We were just talking\nabout one ventricular", "start": 1912.5, "duration": 2.12}, {"text": "cell on the previous slide.", "start": 1914.62, "duration": 1.68}, {"text": "But that would be--", "start": 1916.3, "duration": 1.8}, {"text": "if we look at the second\nbox from the top here,", "start": 1918.1, "duration": 2.88}, {"text": "this is where the heart and\nlung model would fit in there.", "start": 1920.98, "duration": 4.15}, {"text": "It's got seven different organs,\nwhich include kidney, liver,", "start": 1925.13, "duration": 3.17}, {"text": "lower limbs, and so forth\ndown at the bottom part", "start": 1928.3, "duration": 2.84}, {"text": "of this diagram.", "start": 1931.14, "duration": 1.85}, {"text": "And you get the picture.", "start": 1932.99, "duration": 1.19}, {"text": "Each of these things, you're\nmodeling the volumes and flows,", "start": 1934.18, "duration": 9.51}, {"text": "Now, this is systems biology.", "start": 1943.69, "duration": 2.1}, {"text": "This is really kind of a\nrenaissance of interest", "start": 1945.79, "duration": 3.75}, {"text": "in physiology, which is what it\nwould have been called before.", "start": 1949.54, "duration": 2.79}, {"text": "And there are some really\ninteresting mysteries out there", "start": 1952.33, "duration": 4.47}, {"text": "to be solved that are really\nonly solvable, or possibly only", "start": 1956.8, "duration": 4.77}, {"text": "solvable, at the system level.", "start": 1961.57, "duration": 1.35}, {"text": "You never know,\nsomebody could come up", "start": 1962.92, "duration": 2.22}, {"text": "and say, oh, yeah,\nthis is really", "start": 1965.14, "duration": 1.59}, {"text": "well understood immunology\nand that answers everything.", "start": 1966.73, "duration": 3.61}, {"text": "But even if it's some\nkind of immunology,", "start": 1970.34, "duration": 4.967}, {"text": "you still have to say,\nhow does it play out?", "start": 1975.307, "duration": 1.833}, {"text": "And what happens is we've\nbeen talking about sickle cell", "start": 1977.14, "duration": 2.333}, {"text": "disease, and you can\nhave fairly mild pain", "start": 1979.473, "duration": 3.487}, {"text": "as one of the major symptoms.", "start": 1982.96, "duration": 2.17}, {"text": "But then all of a\nsudden, out of nowhere,", "start": 1985.13, "duration": 1.85}, {"text": "you'll get this\nmulti-organ system failure", "start": 1986.98, "duration": 2.49}, {"text": "where almost every major\norgan in that previous slide,", "start": 1989.47, "duration": 4.38}, {"text": "lungs and so forth,\nfill up with fluid", "start": 1993.85, "duration": 1.74}, {"text": "and you have a very\nhigh chance of dying.", "start": 1995.59, "duration": 3.492}, {"text": "And this could happen to\nevery one of us in this room", "start": 1999.082, "duration": 2.208}, {"text": "because it's not\nrestricted to sickle cell.", "start": 2001.29, "duration": 2.55}, {"text": "If any of you have severe\nburn, or car crash, major bone", "start": 2003.84, "duration": 7.14}, {"text": "injuries, and so forth,\nyou have a very good chance", "start": 2010.98, "duration": 2.61}, {"text": "of getting into\nmulti-organ system failure.", "start": 2013.59, "duration": 2.44}, {"text": "And it really isn't\nknown how that plays out.", "start": 2016.03, "duration": 3.47}, {"text": "I mean, not even that-- not\njust a quantitative model,", "start": 2019.5, "duration": 2.79}, {"text": "but even qualitatively.", "start": 2022.29, "duration": 2.73}, {"text": "So I think this is something--\nthere are projects now", "start": 2025.02, "duration": 4.2}, {"text": "to get genomic data collection,\nboth genetic and expression", "start": 2029.22, "duration": 5.4}, {"text": "data, and time will tell whether\nthat is actually the best", "start": 2034.62, "duration": 5.85}, {"text": "route to solving that mystery.", "start": 2040.47, "duration": 2.3}, {"text": "So that was multi-organ.", "start": 2042.77, "duration": 1.57}, {"text": "Now we're talking\nabout multi-organism.", "start": 2044.34, "duration": 3.09}, {"text": "After you've built up\nan entire organism,", "start": 2047.43, "duration": 4.26}, {"text": "then you want to\nknow how it acts", "start": 2051.69, "duration": 1.98}, {"text": "at the next level of network\nanalysis, which is how does it", "start": 2053.67, "duration": 4.89}, {"text": "fit in with other organisms?", "start": 2058.56, "duration": 3.929}, {"text": "None of us, almost\nno organism, really", "start": 2062.489, "duration": 3.841}, {"text": "belongs in ecological\nniche all by itself.", "start": 2066.33, "duration": 3.36}, {"text": "And some of the modeling we\nare taught in this course", "start": 2069.69, "duration": 5.969}, {"text": "could be called simulation.", "start": 2075.659, "duration": 2.071}, {"text": "And probably one of the\nlongest-lasting computer", "start": 2077.73, "duration": 6.09}, {"text": "games in the world, and\none of the most successful,", "start": 2083.82, "duration": 4.62}, {"text": "I've heard, is The Sims.", "start": 2088.44, "duration": 4.11}, {"text": "It started with SimCity in--", "start": 2092.55, "duration": 1.98}, {"text": "SimCity in '87.", "start": 2097.44, "duration": 1.08}, {"text": "And then this particular\none illustrated here", "start": 2100.995, "duration": 1.875}, {"text": "is SimLife, which is all\nabout ecological modeling.", "start": 2102.87, "duration": 3.6}, {"text": "And it's not entirely\ndifferent from what", "start": 2106.47, "duration": 2.4}, {"text": "a serious ecological-modeling\nprogram would do.", "start": 2108.87, "duration": 3.66}, {"text": "It certainly has a lot of\nthe interesting parameters", "start": 2112.53, "duration": 2.34}, {"text": "such as the lifespan here.", "start": 2114.87, "duration": 3.54}, {"text": "You're doing demographics\nhere so you have the lifespan,", "start": 2118.41, "duration": 3.48}, {"text": "the amount of food needed,\nthe size, kind of vision,", "start": 2121.89, "duration": 6.96}, {"text": "roaming, so forth, of all these\ndifferent kinds of animals.", "start": 2128.85, "duration": 3.45}, {"text": "You can have plants, you\nhave herbivores, carnivores,", "start": 2135.09, "duration": 3.87}, {"text": "and so on.", "start": 2138.96, "duration": 0.97}, {"text": "And then you can set up\nthe population sizes,", "start": 2139.93, "duration": 2.63}, {"text": "and then it will do\nsimulations based", "start": 2142.56, "duration": 3.42}, {"text": "on that, where each individual\nanimal is tracked in terms", "start": 2145.98, "duration": 5.46}, {"text": "of its position and quantity.", "start": 2151.44, "duration": 2.13}, {"text": "And as you would expect,\nas the carnivores build up,", "start": 2153.57, "duration": 5.79}, {"text": "then they knock\ndown the herbivores,", "start": 2159.36, "duration": 1.5}, {"text": "and the plants go\nup, and so forth.", "start": 2160.86, "duration": 3.3}, {"text": "And it goes through\nthese cycles.", "start": 2164.16, "duration": 2.52}, {"text": "And so this is basically\na stochastic model,", "start": 2166.68, "duration": 2.31}, {"text": "just like the stochastic models\nthat we had for molecules,", "start": 2168.99, "duration": 4.74}, {"text": "but here, at the organism level.", "start": 2173.73, "duration": 2.28}, {"text": "And what's happening here in\nthe slower right-hand section", "start": 2176.01, "duration": 3.15}, {"text": "is you've got little\ngreen plants getting", "start": 2179.16, "duration": 3.42}, {"text": "eaten by herbivores, and\nthe herbivores getting", "start": 2182.58, "duration": 2.58}, {"text": "eaten by carnivores.", "start": 2185.16, "duration": 1.2}, {"text": "Now, hopefully, this\ncourse has already", "start": 2189.05, "duration": 6.16}, {"text": "or will inspire you to\nreally think globally.", "start": 2195.21, "duration": 4.89}, {"text": "To think not only\nglobally in terms", "start": 2200.1, "duration": 2.4}, {"text": "of how little pieces\nof molecular tools", "start": 2202.5, "duration": 5.52}, {"text": "fit together into\nsystems and networks,", "start": 2208.02, "duration": 2.73}, {"text": "but how our systems\nand networks we model", "start": 2210.75, "duration": 2.85}, {"text": "fit into the big picture of what\nare really important problems.", "start": 2213.6, "duration": 4.83}, {"text": "Maybe a slightly\nimproved Viagra is not", "start": 2218.43, "duration": 6.12}, {"text": "in the same category as\na new tuberculosis drug", "start": 2224.55, "duration": 3.78}, {"text": "or maybe it is.", "start": 2228.33, "duration": 0.75}, {"text": "I mean, you decide for yourself\nwhat is thinking globally.", "start": 2229.08, "duration": 4.05}, {"text": "But you have to act\nlocally, and that's", "start": 2233.13, "duration": 1.74}, {"text": "what we're doing in this class.", "start": 2234.87, "duration": 1.292}, {"text": "When we're thinking\nglobally, and we're", "start": 2239.07, "duration": 1.71}, {"text": "thinking about\necological systems,", "start": 2240.78, "duration": 2.46}, {"text": "we're thinking about the\nlithosphere, for the most part,", "start": 2243.24, "duration": 5.25}, {"text": "and its interaction\nwith the hydrosphere.", "start": 2248.49, "duration": 3.66}, {"text": "The lithosphere is\nmostly silicon dioxide,", "start": 2252.15, "duration": 7.88}, {"text": "a tiny bit of carbon, and it\ngets very hot, very quickly.", "start": 2260.03, "duration": 4.85}, {"text": "So only the top 0.1%, that's\nthe top four kilometers of it,", "start": 2264.88, "duration": 7.88}, {"text": "is survivable in any type\nof organism we know of.", "start": 2272.76, "duration": 3.75}, {"text": "About 110 degrees centigrade\nis where organisms start", "start": 2276.51, "duration": 3.21}, {"text": "having a great deal of trouble.", "start": 2279.72, "duration": 2.22}, {"text": "You and I would have\ntrouble before that.", "start": 2281.94, "duration": 1.8}, {"text": "The biosphere here\nis about 3 times 10", "start": 2287.57, "duration": 3.44}, {"text": "to the 15th grams, my\nestimate for marine organisms.", "start": 2291.01, "duration": 10.14}, {"text": "And maybe 10 to the 18th grams\nfor all land plants and animals", "start": 2301.15, "duration": 6.06}, {"text": "and microorganisms.", "start": 2307.21, "duration": 2.94}, {"text": "The microbial hydrosphere\nhere is about 10", "start": 2310.15, "duration": 6.275}, {"text": "to the 21st milliliters,\nwhich works out about 10", "start": 2316.425, "duration": 5.155}, {"text": "to the 27th cells.", "start": 2321.58, "duration": 1.38}, {"text": "A phenomenal number of\nthese cells, about 10", "start": 2322.96, "duration": 1.97}, {"text": "to the 26th of those\ncells is a single species,", "start": 2324.93, "duration": 2.71}, {"text": "which is prochlorococcus,\nwhich is responsible for maybe", "start": 2327.64, "duration": 5.07}, {"text": "about 50% of the\nEarth's photosynthesis.", "start": 2332.71, "duration": 3.96}, {"text": "A lot of that photosynthesis\ndoes not end up in fixed carbon", "start": 2336.67, "duration": 3.99}, {"text": "because it is\nimmediately consumed", "start": 2340.66, "duration": 2.91}, {"text": "by one of its other\npredators, basically.", "start": 2343.57, "duration": 7.5}, {"text": "But there's really quite a\nlot of cells out there which,", "start": 2351.07, "duration": 7.027}, {"text": "to the extent that\nthey're well-mixed,", "start": 2358.097, "duration": 1.583}, {"text": "and they're not-- of course,\nit's not perfectly mixed,", "start": 2359.68, "duration": 2.25}, {"text": "all the Pacific and\nAtlantic and so forth.", "start": 2361.93, "duration": 1.84}, {"text": "But it's a considerably\nmore well-mixed,", "start": 2363.77, "duration": 2.09}, {"text": "say, than the\nlithosphere organisms,", "start": 2365.86, "duration": 1.62}, {"text": "where you have organisms down\na kilometer into the ground.", "start": 2367.48, "duration": 3.91}, {"text": "They don't move\naround very rapidly.", "start": 2371.39, "duration": 3.51}, {"text": "So when you have a\npopulation of that size", "start": 2374.9, "duration": 1.75}, {"text": "as you remember from one\nof our first lectures", "start": 2376.65, "duration": 1.96}, {"text": "on population size, the\neffect of population size", "start": 2378.61, "duration": 2.91}, {"text": "determines the rate of drift and\nthe optimality of the organism.", "start": 2381.52, "duration": 8.058}, {"text": "So one of the things\nthat we do, when", "start": 2389.578, "duration": 1.542}, {"text": "we've been talking about\nmining the biosphere, one", "start": 2391.12, "duration": 3.54}, {"text": "of the things that\nwe're looking for", "start": 2394.66, "duration": 1.5}, {"text": "are new tools that we can\nuse for nanoengineering.", "start": 2396.16, "duration": 7.38}, {"text": "And kind of one of my pet ones\nthat I'm becoming interested", "start": 2403.54, "duration": 3.63}, {"text": "in, we don't work\non the same thing,", "start": 2407.17, "duration": 1.5}, {"text": "but it is kind of interesting,\nis a set of-- we mentioned this", "start": 2408.67, "duration": 4.2}, {"text": "briefly in the drug protein\ninteraction lecture where--", "start": 2412.87, "duration": 5.845}, {"text": "but I don't think I mentioned\nthis particular one-- where", "start": 2418.715, "duration": 2.375}, {"text": "you have polyketides\nthat go together.", "start": 2421.09, "duration": 3.21}, {"text": "It's another polymer that\nhas certain similarities", "start": 2424.3, "duration": 3.75}, {"text": "to the basic polymers\nwe talked about,", "start": 2428.05, "duration": 1.62}, {"text": "but each step in it had\nto have a protein enzyme--", "start": 2429.67, "duration": 4.32}, {"text": "an enzymatic domain\nto accomplish that.", "start": 2433.99, "duration": 2.56}, {"text": "And so one of these\nis tetracycline.", "start": 2436.55, "duration": 2.0}, {"text": "And this is one of\nthe more aromatic kind", "start": 2438.55, "duration": 2.49}, {"text": "of coupled-aromatic\ncompounds that's", "start": 2441.04, "duration": 1.86}, {"text": "made because you have\nthese [INAUDIBLE]", "start": 2442.9, "duration": 2.04}, {"text": "and aromatases in addition\nto the polymerization steps.", "start": 2444.94, "duration": 5.31}, {"text": "And so you make this\nthing that looks", "start": 2450.25, "duration": 2.1}, {"text": "kind of like a poly\naromatic hydrocarbon.", "start": 2452.35, "duration": 3.6}, {"text": "And also in nature, you will\nfind, in soot, in forest fires,", "start": 2455.95, "duration": 5.25}, {"text": "in all kinds of\nnatural phenomena,", "start": 2461.2, "duration": 1.77}, {"text": "you will find polycyclic\naromatic hydrocarbons, which", "start": 2462.97, "duration": 4.44}, {"text": "some of you may know about\nas the potent carcinogens,", "start": 2467.41, "duration": 3.3}, {"text": "but they're also just\nnatural components.", "start": 2470.71, "duration": 3.96}, {"text": "But they also-- you\ncan start to see this", "start": 2474.67, "duration": 2.37}, {"text": "looks a little bit like the\nbuckyballs and buckytubes", "start": 2477.04, "duration": 2.61}, {"text": "that we talked\nabout when we were", "start": 2479.65, "duration": 1.375}, {"text": "talking about\nmolecular-type transistors.", "start": 2481.025, "duration": 3.545}, {"text": "So the possibility of mining\nthe biosphere for enzymes", "start": 2484.57, "duration": 5.22}, {"text": "that act to\nsynthesize or degrade", "start": 2489.79, "duration": 2.16}, {"text": "this class of\ncompounds, I think,", "start": 2491.95, "duration": 1.56}, {"text": "would be just an example.", "start": 2493.51, "duration": 1.42}, {"text": "We could list many others.", "start": 2494.93, "duration": 1.2}, {"text": "But the part of it is\njust to dream, to imagine,", "start": 2496.13, "duration": 3.02}, {"text": "what it is would like\nto find out there.", "start": 2499.15, "duration": 2.44}, {"text": "And if there's an\nabundant source of it,", "start": 2501.59, "duration": 5.36}, {"text": "then you should be able to--", "start": 2506.95, "duration": 1.77}, {"text": "abundant source of, say,\nthe compound, in this case,", "start": 2508.72, "duration": 2.29}, {"text": "you need to be able to find\na microorganism and an enzyme", "start": 2511.01, "duration": 4.02}, {"text": "that goes with that\nbecause there's a truly", "start": 2515.03, "duration": 2.03}, {"text": "phenomenal amount of diversity.", "start": 2517.06, "duration": 2.13}, {"text": "Another very important\nglobal consideration,", "start": 2522.37, "duration": 3.21}, {"text": "rather than just mining\nit for new tools,", "start": 2525.58, "duration": 3.03}, {"text": "is thinking about ways that\neither we could engineer", "start": 2528.61, "duration": 2.91}, {"text": "or accidentally mess\nup our entire planet,", "start": 2531.52, "duration": 5.37}, {"text": "as we could be doing with\nglobal warming or could do.", "start": 2536.89, "duration": 5.91}, {"text": "And perhaps it's naive\nto think that we actually", "start": 2542.8, "duration": 3.06}, {"text": "are having such a\nbig effect because we", "start": 2545.86, "duration": 1.83}, {"text": "know that global warming changes\nperiodically over millennia.", "start": 2547.69, "duration": 4.41}, {"text": "But it is very clear\nfrom the record", "start": 2555.11, "duration": 4.92}, {"text": "just exactly how much carbon\ndioxide we are releasing", "start": 2560.03, "duration": 2.38}, {"text": "and it makes sense, that it\nis consistent with the kind", "start": 2562.41, "duration": 3.848}, {"text": "of temperature\nchanges that have been", "start": 2566.258, "duration": 1.542}, {"text": "observed since the\nIndustrial Revolution.", "start": 2567.8, "duration": 2.73}, {"text": "In any case, when you\nlook at, in particular,", "start": 2570.53, "duration": 5.26}, {"text": "the Southern Ocean--", "start": 2575.79, "duration": 2.06}, {"text": "up at the top of slide 27--", "start": 2577.85, "duration": 2.108}, {"text": "you can see there is a\nfew places, in particular,", "start": 2579.958, "duration": 2.042}, {"text": "Southern Ocean seems like\nit's a prime candidate where", "start": 2582.0, "duration": 2.33}, {"text": "you have high nutrients\nbut low chlorophyll.", "start": 2584.33, "duration": 3.18}, {"text": "And you say, well, why would\nyou have high nutrients", "start": 2587.51, "duration": 2.22}, {"text": "but very little of the\nchlorophyll around,", "start": 2589.73, "duration": 5.2}, {"text": "which is a tipoff that you have\nthe photosynthetic bacteria.", "start": 2594.93, "duration": 5.24}, {"text": "And the reason is that\nyou have a limitation", "start": 2600.17, "duration": 3.33}, {"text": "of some micronutrient.", "start": 2603.5, "duration": 1.17}, {"text": "Micronutrient means it's not\nneeded in the vast quantities", "start": 2604.67, "duration": 4.68}, {"text": "that you need nitrogen,\nphosphorus, carbon, oxygen,", "start": 2609.35, "duration": 2.92}, {"text": "and so on.", "start": 2612.27, "duration": 1.2}, {"text": "So iron, typically, is\nthe limiting micronutrient", "start": 2613.47, "duration": 2.6}, {"text": "in the Southern Ocean.", "start": 2616.07, "duration": 1.26}, {"text": "And so there actually have\nbeen little pilot experiments", "start": 2617.33, "duration": 3.48}, {"text": "to drop iron off the\nbacks of huge tankers.", "start": 2620.81, "duration": 4.08}, {"text": "And there are now at\nleast seven patents", "start": 2624.89, "duration": 2.37}, {"text": "that have been filed\non doing this in order", "start": 2627.26, "duration": 2.46}, {"text": "to balance out the carbon\ncredits for different nations.", "start": 2629.72, "duration": 4.02}, {"text": "This is potentially a very big\nbit of terrestrial engineering", "start": 2633.74, "duration": 3.96}, {"text": "that might happen.", "start": 2637.7, "duration": 1.14}, {"text": "It involves trying to\nchange phytoplankton.", "start": 2638.84, "duration": 5.4}, {"text": "And as this line here\nbegins to point out,", "start": 2644.24, "duration": 4.21}, {"text": "even though\nphytoplankton are only 1%", "start": 2648.45, "duration": 2.6}, {"text": "of the total global\nbiomass, it's about 50%", "start": 2651.05, "duration": 2.7}, {"text": "of the carbon fixation.", "start": 2653.75, "duration": 3.19}, {"text": "What is the source of\nthis 50-fold anomaly?", "start": 2656.94, "duration": 2.63}, {"text": "Why is it that even\nthough it's doing--", "start": 2659.57, "duration": 4.96}, {"text": "how is it doing 50% of\nthe carbon fixation?", "start": 2664.53, "duration": 1.88}, {"text": "And what's happening\nis a lot of the carbon", "start": 2666.41, "duration": 2.34}, {"text": "is going right back\nout after being fixed.", "start": 2668.75, "duration": 3.693}, {"text": "Instead of settling to\nthe bottom of the ocean", "start": 2672.443, "duration": 1.917}, {"text": "and never bothering us\nagain, it gets returned.", "start": 2674.36, "duration": 5.67}, {"text": "And the exact modeling\nof that requires", "start": 2680.03, "duration": 2.25}, {"text": "a much deeper knowledge\nof exactly what organisms", "start": 2682.28, "duration": 3.18}, {"text": "are present in the ocean.", "start": 2685.46, "duration": 1.35}, {"text": "One of the problems\nwith this however,", "start": 2686.81, "duration": 1.78}, {"text": "is a genomic problem, in\na certain sense, which", "start": 2688.59, "duration": 4.16}, {"text": "is that very few\nof these organisms", "start": 2692.75, "duration": 3.93}, {"text": "can be cultivated\nin the laboratory.", "start": 2696.68, "duration": 2.16}, {"text": "On the order of 99.9% of the\norganisms that you sample", "start": 2698.84, "duration": 3.39}, {"text": "from the ocean,\nor from the soil,", "start": 2702.23, "duration": 1.95}, {"text": "a number of different\nenvironments,", "start": 2704.18, "duration": 2.91}, {"text": "do not grow well\nin the laboratory.", "start": 2707.09, "duration": 2.26}, {"text": "So if you were to\nstudy them, some people", "start": 2709.35, "duration": 3.77}, {"text": "are feeling that the best\nroute to studying them", "start": 2713.12, "duration": 2.76}, {"text": "is going directly for--", "start": 2715.88, "duration": 3.15}, {"text": "looking at their genomes,\nwithout necessarily", "start": 2719.03, "duration": 2.07}, {"text": "being able to grow\nthem in the laboratory.", "start": 2721.1, "duration": 2.532}, {"text": "Now, when we talk\nabout this problem of--", "start": 2726.41, "duration": 4.44}, {"text": "even if we fertilize\nthe oceans, and we", "start": 2730.85, "duration": 3.93}, {"text": "can model this whole procedure,\nI won't go into details.", "start": 2734.78, "duration": 2.46}, {"text": "But if there are predators\nthere that take the fixed carbon", "start": 2737.24, "duration": 10.15}, {"text": "and turn it back\ninto carbon dioxide,", "start": 2747.39, "duration": 2.43}, {"text": "you want to be able\nto monitor that.", "start": 2749.82, "duration": 2.37}, {"text": "Now, of course, the ocean\nis a large, complex set", "start": 2752.19, "duration": 3.48}, {"text": "of prokaryotic\nautotrophs that are, say,", "start": 2755.67, "duration": 3.87}, {"text": "photosynthetic bacteria, and\neukaryotic photosynthetic", "start": 2759.54, "duration": 2.91}, {"text": "bacteria, and prokaryotic\nand eukaryotic predators", "start": 2762.45, "duration": 5.76}, {"text": "of various sorts.", "start": 2768.21, "duration": 1.36}, {"text": "And this is, I think, one\nof the more interesting", "start": 2769.57, "duration": 2.9}, {"text": "predator-prey differential\nequation models.", "start": 2772.47, "duration": 6.09}, {"text": "It's almost the same as many\nof the other differential", "start": 2778.56, "duration": 2.82}, {"text": "equations that we did from\nthe first lecture on growth.", "start": 2781.38, "duration": 5.5}, {"text": "We did the logistic\nequation, some", "start": 2786.88, "duration": 2.3}, {"text": "of the ones we did on\nrepressor function, and so on.", "start": 2789.18, "duration": 2.838}, {"text": "But the thing that's kind of\ninteresting about this one", "start": 2792.018, "duration": 2.292}, {"text": "is it's not simply a\nsingle-cell bacteria", "start": 2794.31, "duration": 5.85}, {"text": "being eaten by a\nsingle-celled heterotroph,", "start": 2800.16, "duration": 3.15}, {"text": "let's say, a blue-green\nalgae being eaten", "start": 2803.31, "duration": 1.71}, {"text": "by a single-cell heterotroph.", "start": 2805.02, "duration": 1.47}, {"text": "Here, they are\nboth multicellular.", "start": 2806.49, "duration": 2.45}, {"text": "They're sort of the\nminimal multicellular.", "start": 2808.94, "duration": 1.75}, {"text": "But because they\nare-- so Chlorella", "start": 2810.69, "duration": 2.55}, {"text": "is one of the smallest\nplants, multicellular plants.", "start": 2813.24, "duration": 2.79}, {"text": "And Brachionus is a small\nrotifer, a multicellular", "start": 2816.03, "duration": 7.89}, {"text": "animal.", "start": 2823.92, "duration": 0.595}, {"text": "Because they're\nmulti-cellular, though,", "start": 2824.515, "duration": 1.625}, {"text": "now you have the demographic\nmortality and fecundity", "start": 2826.14, "duration": 5.55}, {"text": "of each of these things\nthat has to be modeled in.", "start": 2831.69, "duration": 2.43}, {"text": "That's the m and the\nlambda for Brachionus.", "start": 2834.12, "duration": 4.83}, {"text": "And so this plays into these\nequations where you have here,", "start": 2838.95, "duration": 6.45}, {"text": "in the upper-right\nof slide 28, the rate", "start": 2845.4, "duration": 3.3}, {"text": "of change of nitrogen\nwith respect to time,", "start": 2848.7, "duration": 5.43}, {"text": "and concentration of Chlorella.", "start": 2854.13, "duration": 2.82}, {"text": "So nitrogen is N,\nChlorella is C.", "start": 2856.95, "duration": 3.42}, {"text": "The R is the Brachionus\nthat are reproducing", "start": 2860.37, "duration": 7.59}, {"text": "and B are the Brachionus\nwhich are the total.", "start": 2867.96, "duration": 3.43}, {"text": "And you can see each of these\nequations and how it plays out.", "start": 2871.39, "duration": 3.02}, {"text": "Now this is how--", "start": 2874.41, "duration": 1.53}, {"text": "and the way they play\nit out here is you do it", "start": 2875.94, "duration": 2.7}, {"text": "by dilution rate, delta, here.", "start": 2878.64, "duration": 2.82}, {"text": "And the dilution rate is shown\nalong the horizontal x-axis", "start": 2881.46, "duration": 11.49}, {"text": "for each of these\nthree plots here.", "start": 2892.95, "duration": 2.04}, {"text": "And what they're modeling\nis on the far left,", "start": 2894.99, "duration": 4.44}, {"text": "the nitrogen concentration as\na function of dilution rate.", "start": 2899.43, "duration": 7.36}, {"text": "And you can see you get these\ndifferent sectors of behavior.", "start": 2906.79, "duration": 7.85}, {"text": "When you look at\nthe Chlorella, this", "start": 2914.64, "duration": 1.74}, {"text": "is a green, photosynthetic,\nmulticellular organism,", "start": 2916.38, "duration": 4.59}, {"text": "in units of millions of\ncells per milliliter,", "start": 2920.97, "duration": 2.79}, {"text": "that can take different--", "start": 2923.76, "duration": 3.86}, {"text": "it take different\npathways here where,", "start": 2927.62, "duration": 4.15}, {"text": "as a function of\ndilution rate, you", "start": 2931.77, "duration": 1.65}, {"text": "get this bifurcation\nwhere you get", "start": 2933.42, "duration": 2.19}, {"text": "a huge split in the possible\nconcentrations of Chlorella", "start": 2935.61, "duration": 7.77}, {"text": "is the one curve and the\nBrachionus, the predator,", "start": 2943.38, "duration": 3.84}, {"text": "is the other curve.", "start": 2947.22, "duration": 1.095}, {"text": "This kind of bifurcation\nis the sort of thing", "start": 2948.315, "duration": 1.875}, {"text": "we talked about earlier,\nboth in the logistic equation", "start": 2950.19, "duration": 4.62}, {"text": "and in the\nself-exclusion modeling.", "start": 2954.81, "duration": 10.1}, {"text": "And in the upper-right-hand,\nhere's our friend", "start": 2964.91, "duration": 4.38}, {"text": "the coefficient of\nvariation in percent,", "start": 2969.29, "duration": 2.03}, {"text": "ranging from 0 to 80 or\nso on the vertical axis", "start": 2971.32, "duration": 4.84}, {"text": "and the dilution rate.", "start": 2976.16, "duration": 1.57}, {"text": "And again, you can see that you\nget a peak in the dilution rate", "start": 2977.73, "duration": 4.82}, {"text": "at around 0.75.", "start": 2982.55, "duration": 1.92}, {"text": "The bottom two are models, and\nthe upper right is the data.", "start": 2984.47, "duration": 5.08}, {"text": "You can actually see, when\nyou run real Chlorella", "start": 2989.55, "duration": 2.33}, {"text": "and Brachionus in here, that you\ndo get a peak just as you would", "start": 2991.88, "duration": 3.27}, {"text": "predict in this kind\nof bifurcation analysis", "start": 2995.15, "duration": 2.145}, {"text": "in kinetic modeling.", "start": 2997.295, "duration": 2.385}, {"text": "That's due to-- where you\nget interesting behavior", "start": 2999.68, "duration": 5.28}, {"text": "in this complicated-- or this\nfairly simple model ecosystem", "start": 3004.96, "duration": 4.08}, {"text": "where you just have two species.", "start": 3009.04, "duration": 1.92}, {"text": "In the ocean, of course,\nyou have a lot more.", "start": 3010.96, "duration": 4.11}, {"text": "Now, that's out\nin the wide world", "start": 3015.07, "duration": 2.16}, {"text": "where you have 10\nto the 26 cells.", "start": 3017.23, "duration": 3.66}, {"text": "But inside every one of us\nin this room, no offense,", "start": 3020.89, "duration": 3.42}, {"text": "but there are about 10 times\nas many non-human cells", "start": 3024.31, "duration": 4.86}, {"text": "in each of us as\nare human cells.", "start": 3029.17, "duration": 2.88}, {"text": "And we have our own ecology.", "start": 3032.05, "duration": 2.97}, {"text": "And there is a literature\nwhere certain organisms", "start": 3035.02, "duration": 4.95}, {"text": "we know cause\ndiseases, and they're", "start": 3039.97, "duration": 1.77}, {"text": "put into one category,\ninfectious diseases,", "start": 3041.74, "duration": 3.24}, {"text": "but then there's\nanother set that", "start": 3044.98, "duration": 1.47}, {"text": "takes some time to sort out.", "start": 3046.45, "duration": 1.69}, {"text": "And you can see here\nare candidate diseases", "start": 3048.14, "duration": 1.97}, {"text": "and candidate organisms.", "start": 3050.11, "duration": 1.41}, {"text": "And all these little bars\nthat are going in here", "start": 3051.52, "duration": 2.46}, {"text": "are references that\nyou can look up", "start": 3053.98, "duration": 3.33}, {"text": "where maybe it's not\nan airtight case yet,", "start": 3057.31, "duration": 3.21}, {"text": "or maybe it's not\neven-- maybe there's", "start": 3060.52, "duration": 1.8}, {"text": "controversial or\ndiscredited [INAUDIBLE],,", "start": 3062.32, "duration": 2.79}, {"text": "but these are links where,\neventually, this will be", "start": 3065.11, "duration": 2.88}, {"text": "called an infectious disease.", "start": 3067.99, "duration": 2.01}, {"text": "Helicobacter pylori\ncauses stomach ulcers.", "start": 3070.0, "duration": 2.52}, {"text": "I think that fact's\nbasically already accepted.", "start": 3072.52, "duration": 2.415}, {"text": "Some Australian\ndoctor named Marshall", "start": 3077.98, "duration": 2.28}, {"text": "decided to drink a\nbunch of Helicobacter", "start": 3080.26, "duration": 1.833}, {"text": "to prove to his colleagues,\nwho didn't believe", "start": 3082.093, "duration": 1.917}, {"text": "any stomach ulcers were caused\nby Helicobacter, much less all", "start": 3084.01, "duration": 2.82}, {"text": "of them.", "start": 3086.83, "duration": 0.81}, {"text": "And he drank it, he cured\nhimself, he drank it again.", "start": 3087.64, "duration": 4.32}, {"text": "And he caused stomach\nulcers in himself.", "start": 3091.96, "duration": 5.46}, {"text": "And hopefully, none\nof you will volunteer", "start": 3097.42, "duration": 4.14}, {"text": "to do similar things with\nsome of these other nasty guys", "start": 3101.56, "duration": 3.63}, {"text": "here because I think some\nof the list of things", "start": 3105.19, "duration": 2.7}, {"text": "that they cause are a little\nmore serious than stomach", "start": 3107.89, "duration": 2.43}, {"text": "ulcers, and the cures\nare a little less obvious", "start": 3110.32, "duration": 2.67}, {"text": "than the cures for a\ngram-negative bacterium", "start": 3112.99, "duration": 2.25}, {"text": "like Helicobacter.", "start": 3115.24, "duration": 3.6}, {"text": "There have been\nvarious efforts started", "start": 3118.84, "duration": 2.76}, {"text": "to actually mine what's the\nconnection with genomics", "start": 3121.6, "duration": 4.35}, {"text": "and computational biology?", "start": 3125.95, "duration": 1.26}, {"text": "To mine the transcriptome\nfor evidence of these.", "start": 3127.21, "duration": 5.13}, {"text": "You can look for\nbacteria very easily", "start": 3132.34, "duration": 1.8}, {"text": "because they have ribosomal RNA\ncomponents which you can PCR.", "start": 3134.14, "duration": 5.52}, {"text": "Viruses are more complicated\nbecause they're not conserved,", "start": 3139.66, "duration": 5.94}, {"text": "or they don't have any\nuniversally conserved element", "start": 3145.6, "duration": 2.79}, {"text": "like ribosomal RNA.", "start": 3148.39, "duration": 1.59}, {"text": "But there have been\nefforts to look", "start": 3149.98, "duration": 3.93}, {"text": "for what's present in the\nhuman transcriptome that's not", "start": 3153.91, "duration": 2.613}, {"text": "present in the human genome.", "start": 3156.523, "duration": 1.167}, {"text": "The human genome is something\nhighly purified and cloned", "start": 3157.69, "duration": 4.38}, {"text": "and so forth, while\nthe transcriptome", "start": 3162.07, "duration": 2.1}, {"text": "is whatever cells they\nground up that day and they.", "start": 3164.17, "duration": 4.38}, {"text": "And indeed, lurking in there\nare many of these hepatitis,", "start": 3168.55, "duration": 4.26}, {"text": "papilloma, Epstein-Barr virus,\nretroviral-like elements which", "start": 3172.81, "duration": 4.92}, {"text": "are not present in the\nhuman genome as yet.", "start": 3177.73, "duration": 2.55}, {"text": "Human genome is not\ncompletely finished.", "start": 3180.28, "duration": 2.11}, {"text": "So that's still\nan escape clause.", "start": 3182.39, "duration": 1.94}, {"text": "But basically, these are smoking\nguns for at least commensals.", "start": 3184.33, "duration": 6.33}, {"text": "Microorganisms and viruses that\nare living in tissues, some", "start": 3190.66, "duration": 5.1}, {"text": "of them may be tissue-specific.", "start": 3195.76, "duration": 1.86}, {"text": "Some of them, subset, may\nactually cause disease.", "start": 3197.62, "duration": 2.723}, {"text": "And that's the\nwhole problem then,", "start": 3200.343, "duration": 1.417}, {"text": "is sorting out cause and effect.", "start": 3201.76, "duration": 1.75}, {"text": "We know how it's been\ndone, heroically,", "start": 3203.51, "duration": 3.95}, {"text": "with Helicobacter\npylori, but how do", "start": 3207.46, "duration": 1.5}, {"text": "we do it with the other ones?", "start": 3208.96, "duration": 1.208}, {"text": "Some of them will have\ntissue-culture models.", "start": 3210.168, "duration": 1.957}, {"text": "At the time this slide\nwas done, but so--", "start": 3216.43, "duration": 4.68}, {"text": "this is just illustrating\nkind of the flow", "start": 3221.11, "duration": 4.68}, {"text": "of nucleic acid information\nthat comes in about--", "start": 3225.79, "duration": 6.24}, {"text": "that was capable of being\nmined for new microorganisms,", "start": 3232.03, "duration": 3.39}, {"text": "new viruses that might be\npresent in a tissue-specific", "start": 3235.42, "duration": 3.0}, {"text": "fashion, might be pathogens.", "start": 3238.42, "duration": 2.83}, {"text": "These are some of the\nmost popular sequences", "start": 3241.25, "duration": 2.12}, {"text": "from which we're mining.", "start": 3243.37, "duration": 1.44}, {"text": "Obviously, human was\npopular at times [INAUDIBLE]", "start": 3244.81, "duration": 4.71}, {"text": "the human genome was in place.", "start": 3249.52, "duration": 1.72}, {"text": "Here's Brachionus,\nour friend, which", "start": 3251.24, "duration": 1.76}, {"text": "was pretty high up on this\nlist, considering most of you", "start": 3253.0, "duration": 2.73}, {"text": "probably didn't hear about\nBrachionus before this lecture.", "start": 3255.73, "duration": 2.47}, {"text": "Now you've heard of it twice.", "start": 3258.2, "duration": 1.79}, {"text": "There just was a spurt\nin sequencing interest.", "start": 3259.99, "duration": 3.45}, {"text": "And of course, HIV\nis the winner year", "start": 3263.44, "duration": 2.49}, {"text": "after year because of the\nimportance of resequencing it", "start": 3265.93, "duration": 3.15}, {"text": "for new mutations.", "start": 3269.08, "duration": 2.32}, {"text": "And it really has a record\nnumber of new mutations.", "start": 3271.4, "duration": 4.52}, {"text": "And we've talked about\nHIV from a variety", "start": 3275.92, "duration": 7.2}, {"text": "of different standpoints.", "start": 3283.12, "duration": 2.28}, {"text": "One of them is\npolymerase, is protease,", "start": 3285.4, "duration": 2.88}, {"text": "is drug targets, and as a\nsource of drug resistance.", "start": 3288.28, "duration": 4.44}, {"text": "And that you can follow\nup that model, that sort", "start": 3292.72, "duration": 3.83}, {"text": "of atomic-scale\nprotein modeling,", "start": 3296.55, "duration": 2.92}, {"text": "where you're looking\nfor new drugs", "start": 3299.47, "duration": 4.62}, {"text": "where the polymerase,\nthe mutant polymerase,", "start": 3304.09, "duration": 2.16}, {"text": "will not be resistant\nto the new drug.", "start": 3306.25, "duration": 2.01}, {"text": "But you can also monitor\nat the population scale.", "start": 3308.26, "duration": 2.34}, {"text": "As HIV goes to a\nparticular patient,", "start": 3310.6, "duration": 3.39}, {"text": "or to a population of patients,\nhow does the drug resistance", "start": 3313.99, "duration": 6.54}, {"text": "change as a function of time?", "start": 3320.53, "duration": 1.65}, {"text": "Here, the horizontal axis\nis in days, up to 30 days,", "start": 3322.18, "duration": 3.66}, {"text": "and then the vertical\naxis is the titers", "start": 3325.84, "duration": 9.59}, {"text": "of the viruses [INAUDIBLE]\nas a function of time.", "start": 3335.43, "duration": 4.69}, {"text": "And what you have here is\nrates of exponential increase.", "start": 3340.12, "duration": 8.65}, {"text": "These are all on\nlogarithmic scales.", "start": 3348.77, "duration": 2.73}, {"text": "And where you're\nmodeling such a thing", "start": 3351.5, "duration": 2.52}, {"text": "as the clearance to the\nimmune system and so forth.", "start": 3354.02, "duration": 3.623}, {"text": "Originally, this\nvirus was thought", "start": 3357.643, "duration": 1.417}, {"text": "to be a very slowly replicating\nvirus, almost cryptic.", "start": 3359.06, "duration": 6.96}, {"text": "And then later\nwas found out this", "start": 3366.02, "duration": 1.38}, {"text": "is actually a very rapidly\nreplicating, but immune system", "start": 3367.4, "duration": 3.24}, {"text": "is very rapidly responding.", "start": 3370.64, "duration": 3.177}, {"text": "Just each of these\nmodels we've gone through", "start": 3373.817, "duration": 1.833}, {"text": "has a set of parameters\nthat it goes along with.", "start": 3375.65, "duration": 2.26}, {"text": "In a certain sense,\nthere's quite a bit", "start": 3377.91, "duration": 1.7}, {"text": "you can learn about a model just\nby seeing what parameters are", "start": 3379.61, "duration": 3.06}, {"text": "present or absent, whether\nthey're experimentally", "start": 3382.67, "duration": 3.63}, {"text": "determined, how\naccurately, and so on.", "start": 3386.3, "duration": 2.52}, {"text": "And model parameters here are\nmortality rate of uninfected", "start": 3388.82, "duration": 4.86}, {"text": "CD4+ T-cells, same thing\nfor infected cells,", "start": 3393.68, "duration": 4.235}, {"text": "and they can have different\n[INAUDIBLE] you can see", "start": 3397.915, "duration": 2.125}, {"text": "on the far right that there's a\nhuge difference between a diet", "start": 3400.04, "duration": 4.26}, {"text": "of 1/4 per day versus\n[INAUDIBLE] and so on.", "start": 3404.3, "duration": 5.95}, {"text": "There's rates for getting\ninfected, rates of virus loss,", "start": 3410.25, "duration": 5.0}, {"text": "production, threshold value for\nremission, so on and so forth.", "start": 3415.25, "duration": 10.65}, {"text": "And these are\nimportant parameters", "start": 3425.9, "duration": 3.35}, {"text": "for how the virus\npopulation changes", "start": 3429.25, "duration": 4.29}, {"text": "within a person\nor the population.", "start": 3433.54, "duration": 2.268}, {"text": "How it spreads\nthrough the population", "start": 3435.808, "duration": 1.542}, {"text": "depends on, in many cases, on\nthe herd immunity and so forth.", "start": 3437.35, "duration": 7.21}, {"text": "And we get into issues\nof public health.", "start": 3444.56, "duration": 2.99}, {"text": "It's almost a truism that\nmost of the additional quality", "start": 3450.87, "duration": 9.24}, {"text": "years of life, quality-adjusted\nlife years here,", "start": 3460.11, "duration": 3.66}, {"text": "QALY, that we have in the\nworld the fact that our life", "start": 3463.77, "duration": 5.19}, {"text": "expectancy is so much\nlonger and so forth,", "start": 3468.96, "duration": 1.77}, {"text": "are mainly public health\ndecisions that have been made,", "start": 3470.73, "duration": 4.53}, {"text": "not so much pharmaceutical.", "start": 3475.26, "duration": 1.8}, {"text": "Such things as clean water\nhave made a huge impact.", "start": 3481.04, "duration": 7.06}, {"text": "And so we need to think--", "start": 3488.1, "duration": 1.46}, {"text": "but even when you think about\nthe pharmaceutical aspects,", "start": 3489.56, "duration": 2.895}, {"text": "it needs to be thought of\nin a public health sense.", "start": 3492.455, "duration": 2.125}, {"text": "And a surprising amount\nof public health officials", "start": 3494.58, "duration": 3.47}, {"text": "in even the most developed\nnations, maybe most of them", "start": 3498.05, "duration": 5.25}, {"text": "do not have formal\neducation in public health.", "start": 3503.3, "duration": 2.34}, {"text": "And so I urge you all to get at\nleast some education in this.", "start": 3505.64, "duration": 4.68}, {"text": "Because in this, we have--", "start": 3510.32, "duration": 2.16}, {"text": "here, they're trying\nto build and have", "start": 3512.48, "duration": 3.57}, {"text": "built quantitative models,\nnot only for the kinetics", "start": 3516.05, "duration": 5.17}, {"text": "which a disease will go\nthrough a population or even", "start": 3521.22, "duration": 2.66}, {"text": "through an individual, but the\nway that you make decisions.", "start": 3523.88, "duration": 6.52}, {"text": "And this is having an impact\non the way decisions are--", "start": 3530.4, "duration": 2.66}, {"text": "how these different\nprojects are prioritized.", "start": 3533.06, "duration": 2.52}, {"text": "At any given time,\nyou might have", "start": 3535.58, "duration": 1.74}, {"text": "hundreds of different\ncandidate vaccines, which", "start": 3537.32, "duration": 4.5}, {"text": "is one of the major, very\neffective public health", "start": 3541.82, "duration": 3.99}, {"text": "strategies.", "start": 3545.81, "duration": 2.49}, {"text": "And this is the way\nthey prioritize it.", "start": 3548.3, "duration": 2.05}, {"text": "So the level one, saves\nmoney and it improves life.", "start": 3550.35, "duration": 3.68}, {"text": "So that's almost a no-brainer.", "start": 3554.03, "duration": 3.72}, {"text": "Then you have different levels.", "start": 3557.75, "duration": 1.39}, {"text": "We have it might cost\na $10,000, or $100,000", "start": 3559.14, "duration": 5.21}, {"text": "per quality-adjusted\nlife year saved.", "start": 3564.35, "duration": 2.565}, {"text": "And so the level one\ncandidates are cytomegalovirus,", "start": 3570.2, "duration": 3.66}, {"text": "and therapeutic vaccines.", "start": 3573.86, "duration": 2.4}, {"text": "These are not aimed at\nan infectious disease,", "start": 3576.26, "duration": 2.46}, {"text": "they're for diabetes, rheumatoid\narthritis, multiple sclerosis,", "start": 3578.72, "duration": 3.78}, {"text": "various bacterial ones.", "start": 3582.5, "duration": 1.695}, {"text": "And of course, HIV was\nnot even in this study", "start": 3584.195, "duration": 1.875}, {"text": "because it was such a\nhigh priority already", "start": 3586.07, "duration": 3.96}, {"text": "within the NIH.", "start": 3590.03, "duration": 0.72}, {"text": "So is there a role for genomics\nand computational biology,", "start": 3595.773, "duration": 2.417}, {"text": "the title of this course,\nin this vaccine research", "start": 3598.19, "duration": 3.09}, {"text": "and development?", "start": 3601.28, "duration": 1.56}, {"text": "I think the answer\nis yes, but it", "start": 3602.84, "duration": 2.25}, {"text": "requires a great deal of\ncreativity and resourcefulness", "start": 3605.09, "duration": 2.85}, {"text": "on all of your parts.", "start": 3607.94, "duration": 2.19}, {"text": "There are new opportunities\nwith DNA vaccines where", "start": 3610.13, "duration": 3.6}, {"text": "you can have one or more\nDNAs shot intramuscularly", "start": 3613.73, "duration": 4.29}, {"text": "or a variety of other ways.", "start": 3618.02, "duration": 2.73}, {"text": "What is delivered\nby the DNA vaccine", "start": 3620.75, "duration": 2.25}, {"text": "can be various so-called\nintracellular vaccines,", "start": 3623.0, "duration": 4.74}, {"text": "which can either act through\ncell-mediated immunity", "start": 3627.74, "duration": 2.37}, {"text": "or in some other\nway intracellularly.", "start": 3630.11, "duration": 2.88}, {"text": "RNAi is a rapidly emerging\nway of delivering things", "start": 3632.99, "duration": 8.49}, {"text": "that may not be\nclassically considered", "start": 3641.48, "duration": 2.82}, {"text": "therapeutics or vaccines.", "start": 3644.3, "duration": 2.97}, {"text": "The concept of multiplexing--", "start": 3647.27, "duration": 2.49}, {"text": "many of us have received\nmultiple vaccines at a time.", "start": 3649.76, "duration": 7.68}, {"text": "Typically, every\nyear, your flu vaccine", "start": 3657.44, "duration": 1.89}, {"text": "will have two or\nthree strains in it.", "start": 3659.33, "duration": 1.84}, {"text": "But as you can see from\nthis middle article,", "start": 3661.17, "duration": 4.85}, {"text": "the diversity of\ncertain diseases,", "start": 3666.02, "duration": 1.86}, {"text": "like HIV and influenza, almost\ndemand attention from genomics.", "start": 3667.88, "duration": 5.46}, {"text": "The diversity that can occur,\neither from year to year", "start": 3673.34, "duration": 3.42}, {"text": "or throughout the entire\nglobal set of viruses.", "start": 3676.76, "duration": 8.29}, {"text": "Another opportunity\nis when we have", "start": 3685.05, "duration": 2.69}, {"text": "vectors for, say,\narthropod vectors,", "start": 3687.74, "duration": 4.38}, {"text": "insect vectors like mosquito.", "start": 3692.12, "duration": 1.95}, {"text": "And we have opportunities\nto hit malaria and all", "start": 3694.07, "duration": 6.0}, {"text": "the different life stages.", "start": 3700.07, "duration": 1.347}, {"text": "There are multiple life\nstages within humans", "start": 3701.417, "duration": 1.833}, {"text": "and multiple stages\nwithin the insect vector.", "start": 3703.25, "duration": 5.19}, {"text": "And now, the genomics\nof these two just", "start": 3708.44, "duration": 2.28}, {"text": "came out recently, in the same\nweek, in Nature and Science.", "start": 3710.72, "duration": 6.03}, {"text": "This provides a whole new\nset of inspirations for work", "start": 3716.75, "duration": 4.767}, {"text": "that can be done on these.", "start": 3721.517, "duration": 1.083}, {"text": "I think we should take\na little break now,", "start": 3722.6, "duration": 2.4}, {"text": "and we'll wrap up the\ntalk after that break.", "start": 3725.0, "duration": 4.25}]

transcripts/0YvENlEZwNg.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 2.44}, {"text": "[RUSTLING]", "start": 2.44, "duration": 1.464}, {"text": "[CLICKING]", "start": 3.904, "duration": 1.464}, {"text": "MARKUS KLUTE: Welcome back\nto 8.20, Special Relativity.", "start": 19.07, "duration": 3.17}, {"text": "So in this section,\nwe're going to review", "start": 22.24, "duration": 3.26}, {"text": "the content of the\nmaterial, but underlined", "start": 25.5, "duration": 3.0}, {"text": "with a few questions and\nexamples, very similar", "start": 28.5, "duration": 3.0}, {"text": "to the previous section.", "start": 31.5, "duration": 1.44}, {"text": "It's just this one is\ninterleaved with activities.", "start": 32.94, "duration": 4.61}, {"text": "So let me start by bringing\nback two of those Einstein", "start": 37.55, "duration": 4.77}, {"text": "quotes, which nicely relate\nto each other in a sense", "start": 42.32, "duration": 3.17}, {"text": "that they feed off each other.", "start": 45.49, "duration": 2.72}, {"text": "The first one is, \"I\nhave no special talent.", "start": 48.21, "duration": 2.9}, {"text": "I'm only passionately curious.\"", "start": 51.11, "duration": 3.03}, {"text": "Albert Einstein.", "start": 54.14, "duration": 1.32}, {"text": "And the second one, \"It is\na miracle that curiosity", "start": 55.46, "duration": 3.75}, {"text": "survives formal education.\"", "start": 59.21, "duration": 1.98}, {"text": "And I [LAUGHS] sincerely\nhope that I didn't stop", "start": 61.19, "duration": 2.49}, {"text": "your curiosity\nwith this lecture--", "start": 63.68, "duration": 2.91}, {"text": "quite the opposite.", "start": 66.59, "duration": 1.763}, {"text": "Like we discussed here,\nit's just the starting point", "start": 68.353, "duration": 2.167}, {"text": "of a wider discussion\nof general relativity", "start": 70.52, "duration": 2.55}, {"text": "in your education at MIT\nin the Physics Department.", "start": 73.07, "duration": 3.09}, {"text": "You could learn about quantum\nmechanics, quantum field", "start": 76.16, "duration": 2.82}, {"text": "theories.", "start": 78.98, "duration": 0.78}, {"text": "And a lot of physics\nis out there,", "start": 79.76, "duration": 2.53}, {"text": "which is super exciting\nand interesting.", "start": 82.29, "duration": 5.75}, {"text": "So it basically\nneeds your curiosity", "start": 88.04, "duration": 2.46}, {"text": "in order to tackle challenging\nquestions in physics today.", "start": 90.5, "duration": 3.87}, {"text": "We started the\ndiscussion looking", "start": 97.1, "duration": 2.1}, {"text": "at the background\nwhich led Einstein", "start": 99.2, "duration": 2.85}, {"text": "to make his discoveries.", "start": 102.05, "duration": 2.31}, {"text": "And specifically the\nyear 1905, in which", "start": 104.36, "duration": 3.06}, {"text": "he was able to come out with\nfive papers, all breakthrough", "start": 107.42, "duration": 6.45}, {"text": "papers, including the theory\nof special relativity.", "start": 113.87, "duration": 4.68}, {"text": "His career didn't stop there.", "start": 118.55, "duration": 2.12}, {"text": "He developed the general\ntheory of relativity", "start": 120.67, "duration": 4.64}, {"text": "and published a paper\non this in 1915.", "start": 125.31, "duration": 3.949}, {"text": "And his fame as a\nphysicist really", "start": 129.259, "duration": 2.311}, {"text": "comes out of the predictions\nhe made at that time.", "start": 131.57, "duration": 3.81}, {"text": "So we set the context\nof this class,", "start": 137.89, "duration": 2.42}, {"text": "and we started with a question\nof Galilean transformation and", "start": 140.31, "duration": 5.43}, {"text": "whether or not you can\ntell in a moving train car", "start": 145.74, "duration": 6.42}, {"text": "whether or not this is\nactually moving or stationary.", "start": 152.16, "duration": 3.3}, {"text": "And we demonstrated that\ntime and acceleration", "start": 155.46, "duration": 3.54}, {"text": "is invariant in the\nGalilean transformation.", "start": 159.0, "duration": 2.94}, {"text": "And then, therefore, since you\ncannot distinguish the strength", "start": 161.94, "duration": 5.88}, {"text": "of a force in two reference\nframes which move to each other", "start": 167.82, "duration": 4.17}, {"text": "with moderate velocity, you\ncannot tell whether or not", "start": 171.99, "duration": 4.63}, {"text": "the train car is moving or not.", "start": 176.62, "duration": 2.74}, {"text": "Very important are the\ndevelopment of clocks and times", "start": 179.36, "duration": 3.33}, {"text": "and signal processing\nof the time.", "start": 182.69, "duration": 2.7}, {"text": "And we discussed this in the\ncontext of trains and train", "start": 185.39, "duration": 2.82}, {"text": "lines, but also in Einstein\nliving in the city of Bern,", "start": 188.21, "duration": 3.93}, {"text": "with a large number\nof clock towers", "start": 192.14, "duration": 3.06}, {"text": "which needed synchronization.", "start": 195.2, "duration": 1.44}, {"text": "And even working in\nthe patent office", "start": 196.64, "duration": 3.99}, {"text": "certainly confronted him with\nthose questions all the time.", "start": 200.63, "duration": 4.18}, {"text": "So time is suspect.", "start": 204.81, "duration": 1.04}, {"text": "That is really the\nkey to moving out", "start": 205.85, "duration": 4.38}, {"text": "from Galilean transformation\ninto Newtonian mechanics", "start": 210.23, "duration": 3.39}, {"text": "to special relativity.", "start": 213.62, "duration": 4.8}, {"text": "When we classify or when\nwe look at specific series,", "start": 218.42, "duration": 5.04}, {"text": "we have to understand that\nthey live within a context,", "start": 223.46, "duration": 2.64}, {"text": "within a range of validity.", "start": 226.1, "duration": 2.38}, {"text": "And so classical\nmechanics is not wrong", "start": 228.48, "duration": 2.06}, {"text": "because it breaks down\nat large velocities.", "start": 230.54, "duration": 3.96}, {"text": "It's just only correct in\nthe frame of slow velocities.", "start": 234.5, "duration": 4.17}, {"text": "And special relativity\nalso has its limitations,", "start": 238.67, "duration": 4.68}, {"text": "as in it only describes\nreference frames or scenarios", "start": 243.35, "duration": 4.77}, {"text": "in which there is no\nacceleration between two", "start": 248.12, "duration": 2.91}, {"text": "reference frames.", "start": 251.03, "duration": 0.93}, {"text": "Going back to the question\nof the time, Michelson--", "start": 254.57, "duration": 4.41}, {"text": "and a number of other\nexperiments leading to the very", "start": 258.98, "duration": 2.46}, {"text": "same direction--", "start": 261.44, "duration": 1.89}, {"text": "was trying to\nestablish that there", "start": 263.33, "duration": 2.445}, {"text": "is an ether wind, a medium\nin which light is moving.", "start": 265.775, "duration": 3.135}, {"text": "And his experiment,\nat the time, failed", "start": 268.91, "duration": 2.76}, {"text": "to demonstrate that\nether actually exists.", "start": 271.67, "duration": 3.39}, {"text": "His experiment used a light\nsource and a couple of mirrors", "start": 275.06, "duration": 2.88}, {"text": "in order to show\ninterference patterns.", "start": 277.94, "duration": 4.11}, {"text": "And those interference patterns\ndidn't manifest themselves.", "start": 282.05, "duration": 3.28}, {"text": "So he thought for a long time\nthat his experiment is limited", "start": 285.33, "duration": 3.62}, {"text": "or that he has made a mistake.", "start": 288.95, "duration": 2.38}, {"text": "But it turns out that\nether indeed doesn't exist.", "start": 291.33, "duration": 4.04}, {"text": "Einstein tackled this problem\nby making two postulates.", "start": 295.37, "duration": 3.24}, {"text": "The first one is the\nprinciple of relativity,", "start": 298.61, "duration": 5.16}, {"text": "that there is no preferred\nreference frame if you want;", "start": 303.77, "duration": 3.06}, {"text": "and the second, that the\nspeed of light is constant--", "start": 306.83, "duration": 3.61}, {"text": "and constant and the same\nin all reference frames.", "start": 310.44, "duration": 3.03}, {"text": "And in this class we use\nthose two postulates in order", "start": 313.47, "duration": 2.69}, {"text": "to derive everything we know\nabout special relativity.", "start": 316.16, "duration": 3.54}, {"text": "So we looked at\nthe implications.", "start": 322.485, "duration": 1.375}, {"text": "And the implications\nstarted from time dilation,", "start": 323.86, "duration": 2.13}, {"text": "length contractions.", "start": 325.99, "duration": 0.9}, {"text": "We were able to derive the\nLorentz factor and Lorentz", "start": 326.89, "duration": 3.36}, {"text": "transformation.", "start": 330.25, "duration": 1.35}, {"text": "And we did this by showing\nthis light clock here,", "start": 331.6, "duration": 3.42}, {"text": "where you observe a ticking\nclock in which there", "start": 335.02, "duration": 3.9}, {"text": "is two mirrors and\nlight bouncing back.", "start": 338.92, "duration": 2.37}, {"text": "And each time there\nis a bounce, we", "start": 341.29, "duration": 2.16}, {"text": "count this as one\ntick of the clock.", "start": 343.45, "duration": 2.98}, {"text": "So if the clock is\nmoving, the light", "start": 346.43, "duration": 1.73}, {"text": "has to travel a longer distance.", "start": 348.16, "duration": 1.65}, {"text": "And hence time is delayed.", "start": 349.81, "duration": 4.05}, {"text": "And from just the\ngeometry of this problem,", "start": 353.86, "duration": 2.67}, {"text": "we were able to derive\nthis gamma factor here--", "start": 356.53, "duration": 3.57}, {"text": "1 over square root of\n1 minus beta squared.", "start": 360.1, "duration": 2.37}, {"text": "The beta is velocity\nover the speed of light.", "start": 362.47, "duration": 3.406}, {"text": "So as the first activity\nin today's class,", "start": 365.876, "duration": 2.424}, {"text": "I want you to think\nabout a clock which", "start": 368.3, "duration": 3.05}, {"text": "is moving with a\nphoton, a clock which is", "start": 371.35, "duration": 2.64}, {"text": "moving with the speed of light.", "start": 373.99, "duration": 1.65}, {"text": "And also discuss why isn't\nit possible to go faster", "start": 375.64, "duration": 3.39}, {"text": "than the speed of light.", "start": 379.03, "duration": 1.08}, {"text": "And why can you not\njust keep accelerating?", "start": 380.11, "duration": 3.3}, {"text": "So think about\nthis a little bit.", "start": 383.41, "duration": 1.65}, {"text": "In the live class we\nwill have a discussion.", "start": 385.06, "duration": 2.7}, {"text": "But just come up with\nsome sort of answer", "start": 387.76, "duration": 2.97}, {"text": "of why this is the case.", "start": 390.73, "duration": 1.633}, {"text": "So here we have, in\nthe class, actually", "start": 396.44, "duration": 2.31}, {"text": "showed that there\nis a real speed", "start": 398.75, "duration": 1.38}, {"text": "limit, that if you\ntry to go faster,", "start": 400.13, "duration": 2.85}, {"text": "past [INAUDIBLE]\nvelocity, you run", "start": 402.98, "duration": 1.59}, {"text": "against a boundary,\na real speed limit.", "start": 404.57, "duration": 4.3}, {"text": "If you think about keeping\naccelerating, giving", "start": 408.87, "duration": 2.03}, {"text": "more energy, you\nfind that the amount", "start": 410.9, "duration": 2.16}, {"text": "of energy you need in order to\ngo faster and faster, faster,", "start": 413.06, "duration": 3.84}, {"text": "doesn't get you to velocities\nwhich are faster and faster.", "start": 416.9, "duration": 3.09}, {"text": "And again, you enter a speed\nlimit-- the speed of light.", "start": 419.99, "duration": 4.02}, {"text": "An important topic\nin understanding", "start": 429.28, "duration": 1.86}, {"text": "some of the paradoxes\nin special relativity,", "start": 431.14, "duration": 2.37}, {"text": "and some of the\nconfusion, is the concept", "start": 433.51, "duration": 2.34}, {"text": "of the relativity\nof simultaneity.", "start": 435.85, "duration": 2.775}, {"text": "Now, it can be illustrated quite\nnicely in this example here,", "start": 438.625, "duration": 3.165}, {"text": "where you have a carriage train\ncar with light being emitted", "start": 441.79, "duration": 5.13}, {"text": "and clocks which record those\nevents at each end of the train", "start": 446.92, "duration": 5.55}, {"text": "car.", "start": 452.47, "duration": 1.05}, {"text": "For the stationary person,\nthose clocks will tick in sync.", "start": 453.52, "duration": 4.12}, {"text": "They will always show the\nsame tick and the same time.", "start": 457.64, "duration": 4.25}, {"text": "But for somebody who's observing\nthis train from a platform,", "start": 461.89, "duration": 4.89}, {"text": "or somebody who's moving\nwith a relative velocity", "start": 466.78, "duration": 2.61}, {"text": "towards this train car, you\nwill see those clocks not", "start": 469.39, "duration": 3.36}, {"text": "ticking at the same time.", "start": 472.75, "duration": 2.24}, {"text": "So the clear evidence\nis given in this picture", "start": 474.99, "duration": 3.62}, {"text": "again, where you see that\nthe light's being emitted", "start": 478.61, "duration": 2.505}, {"text": "in the center, but one side\nof the train car is hit first", "start": 481.115, "duration": 3.405}, {"text": "and the second side\nis hit afterwards.", "start": 484.52, "duration": 2.83}, {"text": "So you see that the\nleading clock lags.", "start": 487.35, "duration": 2.84}, {"text": "The leading clock in\nthis example lags behind.", "start": 490.19, "duration": 3.37}, {"text": "And so what you find\nhere is that events which", "start": 493.56, "duration": 2.15}, {"text": "are observed simultaneously\nfor one observer--", "start": 495.71, "duration": 3.42}, {"text": "in this case, the person\ninside the carriage--", "start": 499.13, "duration": 5.07}, {"text": "they will not be simultaneous\nfor an observer who's moving", "start": 504.2, "duration": 4.56}, {"text": "with a relative velocity.", "start": 508.76, "duration": 2.23}, {"text": "And that led us to the\nunderstanding of the pole", "start": 510.99, "duration": 3.679}, {"text": "in the barn paradox, where,\nin one example, the event", "start": 514.669, "duration": 6.061}, {"text": "of the front of the pole\nhitting the back of the barn", "start": 520.73, "duration": 4.02}, {"text": "and the event of the\nback of the pole hitting", "start": 524.75, "duration": 2.52}, {"text": "the front of the barn,\nthey are simultaneously", "start": 527.27, "duration": 2.61}, {"text": "for the barn owner.", "start": 529.88, "duration": 1.29}, {"text": "But they're not simultaneously\nhappening for the person", "start": 531.17, "duration": 3.81}, {"text": "who's carrying the pole.", "start": 534.98, "duration": 3.6}, {"text": "In this case, the event of\nhitting the back of the barn", "start": 538.58, "duration": 7.08}, {"text": "is simultaneous to an event\nwhere the back of the pole", "start": 545.66, "duration": 2.94}, {"text": "is still sticking\nout of the barn.", "start": 548.6, "duration": 1.62}, {"text": "So there is a\nclear disagreement.", "start": 550.22, "duration": 1.53}, {"text": "But the disagreement\ncan be resolved", "start": 551.75, "duration": 2.04}, {"text": "by understanding that\nsimultaneous events are not", "start": 553.79, "duration": 3.75}, {"text": "necessarily simultaneous\nto two observers.", "start": 557.54, "duration": 5.59}, {"text": "Then we moved on to a\nvariety of other paradoxes", "start": 563.13, "duration": 5.01}, {"text": "in special relativity.", "start": 568.14, "duration": 1.5}, {"text": "And the most famous likely\nis the twin paradox,", "start": 569.64, "duration": 3.48}, {"text": "where we discussed that a person\nmoving away and then returning", "start": 573.12, "duration": 5.85}, {"text": "is younger than the person\nwho actually stayed at rest.", "start": 578.97, "duration": 3.96}, {"text": "And we discussed that we were\nable to use time dilation", "start": 582.93, "duration": 4.98}, {"text": "or length contraction in order\nto quantitatively figure out", "start": 587.91, "duration": 3.36}, {"text": "the difference in time.", "start": 591.27, "duration": 1.9}, {"text": "But we also discussed\nthat the person", "start": 593.17, "duration": 1.74}, {"text": "who is moving away\nand then coming back", "start": 594.91, "duration": 5.2}, {"text": "needs to describe the journey in\ntwo different reference frames.", "start": 600.11, "duration": 4.81}, {"text": "And from the fact that\nyou don't consistently can", "start": 604.92, "duration": 2.25}, {"text": "describe this sequence\nof events as two", "start": 607.17, "duration": 3.2}, {"text": "reference frames\ncan see the paradox", "start": 610.37, "duration": 3.33}, {"text": "and the extra confusion.", "start": 613.7, "duration": 5.01}, {"text": "So here we have\nanother activity--", "start": 618.71, "duration": 2.37}, {"text": "an asymmetric travel.", "start": 621.08, "duration": 1.74}, {"text": "So we discussed also the example\nwhere two people move away", "start": 622.82, "duration": 3.93}, {"text": "and then they come back\nin a symmetric fashion.", "start": 626.75, "duration": 2.44}, {"text": "But here we want\nto discuss the case", "start": 629.19, "duration": 1.64}, {"text": "where there are three trends.", "start": 630.83, "duration": 1.56}, {"text": "Carol stays on Earth.", "start": 632.39, "duration": 1.41}, {"text": "Bob moves to Star 1.", "start": 633.8, "duration": 1.59}, {"text": "And Alice moves to Star 2.", "start": 635.39, "duration": 2.34}, {"text": "The distance to Star 1 is longer\nthan the distance to Star 2.", "start": 637.73, "duration": 6.69}, {"text": "So the question is, in this\njourney, they both start", "start": 644.42, "duration": 5.16}, {"text": "and they both return at\nthe same time for Carol.", "start": 649.58, "duration": 3.63}, {"text": "But which of the\ntwins is the youngest?", "start": 653.21, "duration": 3.88}, {"text": "So again, I invite you\nto just work this out.", "start": 657.09, "duration": 2.49}, {"text": "You can use some numbers if\nyou want a quantitative answer.", "start": 659.58, "duration": 4.2}, {"text": "Or you can just reason\nabout [INAUDIBLE]..", "start": 663.78, "duration": 2.52}, {"text": "The answer here is that Bob\nis the youngest of the three", "start": 670.07, "duration": 6.81}, {"text": "once they return to Earth.", "start": 676.88, "duration": 3.27}, {"text": "And the reason for this is\nthe distance he has to travel", "start": 680.15, "duration": 3.13}, {"text": "is the longest.", "start": 683.28, "duration": 0.8}, {"text": "Hence the velocity he has\nto travel in is the largest.", "start": 684.08, "duration": 3.81}, {"text": "And hence the effect of\ntime dilation for him", "start": 687.89, "duration": 2.7}, {"text": "is the biggest.", "start": 690.59, "duration": 1.02}, {"text": "And therefore he's going to\nbe the youngest of the three.", "start": 691.61, "duration": 3.12}, {"text": "All right.", "start": 700.67, "duration": 0.96}, {"text": "We had a rather long discussion\nabout waves and light, Doppler", "start": 701.63, "duration": 4.77}, {"text": "effect, and relativistic\nDoppler effect.", "start": 706.4, "duration": 3.66}, {"text": "Here, just as a\nreminder, the wave", "start": 710.06, "duration": 2.01}, {"text": "equation for an electric\nfield in a vacuum.", "start": 712.07, "duration": 2.37}, {"text": "And the solution to\nthe wave equation", "start": 714.44, "duration": 2.49}, {"text": "is use the second derivative\nwith space and time.", "start": 716.93, "duration": 5.95}, {"text": "And the solution\nsimply can be expressed", "start": 722.88, "duration": 2.03}, {"text": "as a cosine, which is a\nfunction of space and time.", "start": 724.91, "duration": 4.22}, {"text": "We have talked about\nlight quite a bit.", "start": 729.13, "duration": 2.5}, {"text": "And just as\nreminder, [INAUDIBLE]", "start": 731.63, "duration": 1.85}, {"text": "the energy of photon is\nrelated via the Planck-Einstein", "start": 733.48, "duration": 3.81}, {"text": "relation to the frequency.", "start": 737.29, "duration": 2.82}, {"text": "So the higher the frequency,\nthe higher the energy.", "start": 740.11, "duration": 6.005}, {"text": "The higher the frequency,\nthe higher the energy.", "start": 746.115, "duration": 2.485}, {"text": "And here, in this\npicture, you can", "start": 748.6, "duration": 3.03}, {"text": "see the effect of\nthe Doppler effect,", "start": 751.63, "duration": 2.865}, {"text": "where, when you have\na moving source,", "start": 754.495, "duration": 3.075}, {"text": "the observer sees the\nwaveline modified.", "start": 757.57, "duration": 2.73}, {"text": "Objects which move\ntowards us are", "start": 763.44, "duration": 2.82}, {"text": "blueshifted, starting\nfrom white light,", "start": 766.26, "duration": 3.51}, {"text": "or green light in this example.", "start": 769.77, "duration": 1.86}, {"text": "And objects that move away\nfrom us are redshifted.", "start": 771.63, "duration": 3.45}, {"text": "The effect can be\nused, for example,", "start": 775.08, "duration": 3.12}, {"text": "in speed measurements of cars.", "start": 778.2, "duration": 3.45}, {"text": "It can also be used in order\nto measure speed or distances", "start": 781.65, "duration": 3.03}, {"text": "of stars moving away from us.", "start": 784.68, "duration": 2.58}, {"text": "And so that defines,\nthen, the concept", "start": 787.26, "duration": 2.07}, {"text": "of redshift, which is simply\nthe ratio of the difference", "start": 789.33, "duration": 7.05}, {"text": "in wavelength divided\nby the wavelength as", "start": 796.38, "duration": 3.48}, {"text": "observed by the observer.", "start": 799.86, "duration": 2.4}, {"text": "So here there's two\nconcept questions.", "start": 802.26, "duration": 1.96}, {"text": "The first one is, is\nthe wave equation,", "start": 804.22, "duration": 3.27}, {"text": "which you can see\nthere as an example,", "start": 807.49, "duration": 1.61}, {"text": "invariant under\nLorentz transformation?", "start": 809.1, "duration": 3.15}, {"text": "And the second question is,\nhow about the solutions?", "start": 812.25, "duration": 2.67}, {"text": "Are the solutions\nto the wave equation", "start": 814.92, "duration": 2.01}, {"text": "invariant under\nLorentz transformation?", "start": 816.93, "duration": 2.9}, {"text": "So I'll have you\nwork this out again.", "start": 819.83, "duration": 2.27}, {"text": "And the answers are yes and no.", "start": 822.1, "duration": 6.7}, {"text": "The wave equation is invariant.", "start": 828.8, "duration": 2.04}, {"text": "The wave equation\ndescribes the physics.", "start": 830.84, "duration": 3.65}, {"text": "It explains how electric\nand magnetic fields change.", "start": 834.49, "duration": 3.64}, {"text": "And the laws of physics\nneed to be invariant", "start": 838.13, "duration": 3.45}, {"text": "under Lorentz transformation.", "start": 841.58, "duration": 1.29}, {"text": "Otherwise they\nwill not be valid.", "start": 842.87, "duration": 1.74}, {"text": "They will violate the postulate\nwe just made that all reference", "start": 844.61, "duration": 3.81}, {"text": "frames are equal to each other.", "start": 848.42, "duration": 2.55}, {"text": "However, the solutions of the\nwave equation-- light itself--", "start": 850.97, "duration": 3.17}, {"text": "is not invariant under\nLorentz transformation.", "start": 854.14, "duration": 2.76}, {"text": "We've just discussed\nredshift and blueshift,", "start": 856.9, "duration": 2.97}, {"text": "which means that the wavelength\nand frequency of light", "start": 859.87, "duration": 2.25}, {"text": "changes with respect to the\nobserver, or for each observer.", "start": 862.12, "duration": 4.17}, {"text": "So the solutions-- light--", "start": 866.29, "duration": 1.83}, {"text": "are not invariant under\nLorentz transformation.", "start": 868.12, "duration": 4.493}, {"text": "And then we went a little\nbit into particle physics.", "start": 872.613, "duration": 2.167}, {"text": "And I have to apologize\nfor my own preference.", "start": 874.78, "duration": 2.88}, {"text": "But elementary\nparticles, as they", "start": 877.66, "duration": 1.97}, {"text": "have been reproduced\nor observed,", "start": 879.63, "duration": 1.45}, {"text": "are typically moving at\nrather large velocities.", "start": 881.08, "duration": 2.89}, {"text": "So they are very good\nexamples to study", "start": 883.97, "duration": 1.88}, {"text": "effects of special relativity.", "start": 885.85, "duration": 2.46}, {"text": "We looked at energy, the\ntotal energy m0 gamma c", "start": 888.31, "duration": 3.21}, {"text": "squared, which also\ncan be expressed", "start": 891.52, "duration": 2.49}, {"text": "as the energy of the rest\nenergy of the particle,", "start": 894.01, "duration": 3.27}, {"text": "m0 c squared, plus\nthe kinetic energy.", "start": 897.28, "duration": 2.82}, {"text": "And we looked at\nthe total energy", "start": 900.1, "duration": 1.83}, {"text": "as being invariant, one\nof those invariants,", "start": 901.93, "duration": 3.75}, {"text": "as equal to the total\nmomenta squared.", "start": 905.68, "duration": 3.22}, {"text": "The total energy squared is\nequal to the total momentum", "start": 908.9, "duration": 2.45}, {"text": "squared times c squared\nplus the rest mass squared", "start": 911.35, "duration": 3.21}, {"text": "times c to the fourth power.", "start": 914.56, "duration": 2.05}, {"text": "And then we went through a\nlarger number of examples,", "start": 916.61, "duration": 3.37}, {"text": "from accelerating electrons\nto composite particles.", "start": 919.98, "duration": 3.36}, {"text": "We talked about deuteron\nphoton absorption and emission,", "start": 923.34, "duration": 4.15}, {"text": "the creation of particle, the\ncreation of antiparticles,", "start": 927.49, "duration": 3.86}, {"text": "and the scattering of particles.", "start": 931.35, "duration": 2.17}, {"text": "So here we had another example.", "start": 933.52, "duration": 2.06}, {"text": "Oops-- without the solution.", "start": 935.58, "duration": 3.69}, {"text": "In 1995, at Fermilab, a\nproton-antiproton collider,", "start": 939.27, "duration": 4.44}, {"text": "the Tevatron, top\nquarks were discovered.", "start": 943.71, "duration": 3.42}, {"text": "And we measured the top\nquark mass to 175 GeV.", "start": 947.13, "duration": 4.83}, {"text": "The center of mass\nenergy at the Tevatron", "start": 951.96, "duration": 2.16}, {"text": "was 1.8, and later almost\n2 tera-electronvolt,", "start": 954.12, "duration": 4.62}, {"text": "and clearly sufficient for the\nproduction of top and antitop.", "start": 958.74, "duration": 3.99}, {"text": "But what is the minimal energy\nin order for this process", "start": 962.73, "duration": 2.91}, {"text": "to occur?", "start": 965.64, "duration": 1.63}, {"text": "And here we went through\na number of examples.", "start": 967.27, "duration": 3.68}, {"text": "The minimal energy-- sorry.", "start": 970.95, "duration": 1.47}, {"text": "I have to work this out again.", "start": 972.42, "duration": 2.16}, {"text": "The minimal energy required\ncan be derived or extracted", "start": 974.58, "duration": 5.49}, {"text": "in the center of mass frame,\nwhere the top and antitop are", "start": 980.07, "duration": 3.27}, {"text": "produced at rest.", "start": 983.34, "duration": 1.66}, {"text": "And if you do this--\nin this example,", "start": 985.0, "duration": 1.56}, {"text": "the proton in this\ncollider experiment--", "start": 986.56, "duration": 2.97}, {"text": "the experiment is\nalready conducted", "start": 989.53, "duration": 1.79}, {"text": "in the center of mass frame.", "start": 991.32, "duration": 1.44}, {"text": "So the minimal energy\nis simply 2 times", "start": 992.76, "duration": 3.0}, {"text": "the top mass times c square,\nor 2 times gamma times the mass", "start": 995.76, "duration": 3.45}, {"text": "of the proton times c\nsquare, which gives you", "start": 999.21, "duration": 2.1}, {"text": "a gamma factor of 175.", "start": 1001.31, "duration": 3.07}, {"text": "But the likelihood\nto actually observe", "start": 1004.38, "duration": 2.93}, {"text": "a top quark and a antitop\nquark at that energy, 175 GeV", "start": 1007.31, "duration": 6.76}, {"text": "proton or antiproton\nenergy, is rather 0.", "start": 1014.07, "duration": 4.77}, {"text": "And the reason for this has\nto do with the structure", "start": 1018.84, "duration": 2.7}, {"text": "of the proton.", "start": 1021.54, "duration": 1.08}, {"text": "The actual interaction between\nthe proton and the antiproton", "start": 1022.62, "duration": 2.999}, {"text": "is such that the quarks and\nantiquarks inside the proton,", "start": 1025.619, "duration": 5.25}, {"text": "and also the gluons, interact.", "start": 1030.869, "duration": 1.861}, {"text": "And they only carry a\nfraction of the momentum", "start": 1032.73, "duration": 2.31}, {"text": "and the energy of the proton.", "start": 1035.04, "duration": 1.35}, {"text": "And hence this\nminimal calculation", "start": 1036.39, "duration": 2.25}, {"text": "is insufficient to get a\nsufficient cross-section", "start": 1038.64, "duration": 2.79}, {"text": "likelihood for top quarks and\nantiquarks to be produced.", "start": 1041.43, "duration": 3.929}, {"text": "But that is particle physics\nand goes beyond the scope", "start": 1045.359, "duration": 3.061}, {"text": "of this lecture.", "start": 1048.42, "duration": 2.22}, {"text": "One last point, which leads\nsometimes to confusion,", "start": 1050.64, "duration": 3.06}, {"text": "is the concept of conserved\nand invariant properties.", "start": 1053.7, "duration": 4.96}, {"text": "When we look at the\nmeaning of the word,", "start": 1058.66, "duration": 2.6}, {"text": "invariant means never-changing.", "start": 1061.26, "duration": 2.37}, {"text": "And in the concept of\nspecial relativity,", "start": 1063.63, "duration": 2.43}, {"text": "properties are invariant\nwhen they do not", "start": 1066.06, "duration": 2.49}, {"text": "change under Lorentz\ntransformation or Galilean", "start": 1068.55, "duration": 3.99}, {"text": "transformation, as we\ndiscussed earlier in the class.", "start": 1072.54, "duration": 3.63}]

transcripts/0_w-R_g5lRA.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 2.495}, {"text": "[RUSTLING]", "start": 2.495, "duration": 1.497}, {"text": "[CLICKING]", "start": 3.992, "duration": 1.497}, {"text": "CASEY RODRIGUEZ: OK, so let's\ncontinue our study of sequences", "start": 13.99, "duration": 3.173}, {"text": "of real numbers.", "start": 17.163, "duration": 0.667}, {"text": "So we've seen special types of\nsequences, monotone sequences,", "start": 24.24, "duration": 3.9}, {"text": "before.", "start": 28.14, "duration": 0.51}, {"text": "And then in the\nprevious lecture,", "start": 28.65, "duration": 4.12}, {"text": "we looked at sequences\nobtained from sequences,", "start": 32.77, "duration": 6.45}, {"text": "namely the sequences that give\nyou the lim sup and lim inf.", "start": 39.22, "duration": 2.958}, {"text": "And we showed that\nthese are actually", "start": 42.178, "duration": 1.542}, {"text": "limits of subsequences.", "start": 43.72, "duration": 3.453}, {"text": "Now I'm going to\ndefine what looks", "start": 47.173, "duration": 1.417}, {"text": "like a new class of sequences.", "start": 48.59, "duration": 5.88}, {"text": "But we'll see it's actually not.", "start": 54.47, "duration": 1.74}, {"text": "These are called\nCauchy sequences.", "start": 56.21, "duration": 1.83}, {"text": "So \"coe-shee\"-- not\n\"couch-ee,\" not \"cawt-shee\"--", "start": 62.45, "duration": 7.33}, {"text": "Cauchy, so a French guy.", "start": 69.78, "duration": 3.15}, {"text": "So it's pronounced Cauchy and\nprobably not even pronounced", "start": 72.93, "duration": 3.03}, {"text": "like that.", "start": 75.96, "duration": 0.5}, {"text": "It's probably got a\ndifferent pronunciation", "start": 76.46, "duration": 8.04}, {"text": "by people who\nactually speak French.", "start": 84.5, "duration": 1.98}, {"text": "So what is the definition\nof a Cauchy sequence?", "start": 86.48, "duration": 2.655}, {"text": "A Cauchy sequence,\nintuitively, it's", "start": 89.135, "duration": 3.945}, {"text": "a sequence so that if you go\nfar enough out in the sequence,", "start": 93.08, "duration": 5.28}, {"text": "any two entries in that\nsequence are close together.", "start": 98.36, "duration": 4.35}, {"text": "So convergent sequences\nhad the property", "start": 102.71, "duration": 2.61}, {"text": "that if you go far enough out,\nthe entries in the sequence", "start": 105.32, "duration": 3.66}, {"text": "are getting close\nto a real number.", "start": 108.98, "duration": 2.76}, {"text": "Cauchy sequence is\nthat any two entries", "start": 111.74, "duration": 2.58}, {"text": "are close to each other.", "start": 114.32, "duration": 1.305}, {"text": "So a Cauchy sequence, so\nwe say a sequence is Cauchy", "start": 118.72, "duration": 12.87}, {"text": "if we're all epsilon\npositive, there", "start": 131.59, "duration": 6.9}, {"text": "exists an M,\nnatural number, such", "start": 138.49, "duration": 3.54}, {"text": "that if n is bigger\nthan or equal to M and k", "start": 142.03, "duration": 7.54}, {"text": "is bigger than or equal\nto M, then xn minus xk", "start": 149.57, "duration": 6.895}, {"text": "is less than epsilon.", "start": 156.465, "duration": 0.875}, {"text": "So maybe not write if.", "start": 161.05, "duration": 2.33}, {"text": "I mean, it's the same\nstatement, but since it looks--", "start": 163.38, "duration": 2.49}, {"text": "so it'll look a little more\nlike previous statements", "start": 165.87, "duration": 4.25}, {"text": "when we put a \"for all\" there.", "start": 170.12, "duration": 1.25}, {"text": "So you have a definition here.", "start": 174.07, "duration": 3.345}, {"text": "It's the definition\nof a new thing.", "start": 180.99, "duration": 3.43}, {"text": "You should now try\nto look at an example", "start": 184.42, "duration": 2.88}, {"text": "and then possibly negate the\ndefinition to see if you really", "start": 187.3, "duration": 2.82}, {"text": "understand it.", "start": 190.12, "duration": 1.15}, {"text": "So an example of\na Cauchy sequence", "start": 191.27, "duration": 3.02}, {"text": "is x of n equals 1 over\nn, our favorite sequence.", "start": 194.29, "duration": 6.37}, {"text": "So let's prove this.", "start": 200.66, "duration": 2.27}, {"text": "So all we have is\nthe definition.", "start": 202.93, "duration": 1.96}, {"text": "So we have to verify that\nx of n equals 1 over n", "start": 204.89, "duration": 3.41}, {"text": "verifies the definition\nof being Cauchy.", "start": 208.3, "duration": 3.78}, {"text": "So just like when we try to\nprove something is convergent,", "start": 212.08, "duration": 2.7}, {"text": "which is a \"for all\" epsilon\nstatement, the first thing", "start": 214.78, "duration": 3.51}, {"text": "you have to do is let\nepsilon be positive.", "start": 218.29, "duration": 3.43}, {"text": "And then I have to choose M\nand show that that capital", "start": 221.72, "duration": 2.48}, {"text": "M produces this statement here.", "start": 224.2, "duration": 3.76}, {"text": "So choose M, a natural\nnumber, so that 1 over M", "start": 227.96, "duration": 9.17}, {"text": "is less than epsilon over 2.", "start": 237.13, "duration": 2.13}, {"text": "So I could phrase that as\ncapital M being bigger than 2", "start": 239.26, "duration": 3.33}, {"text": "over epsilon, but I'm going\nto phrase it this way.", "start": 242.59, "duration": 4.05}, {"text": "Now we have to show\nthat it works-- namely,", "start": 246.64, "duration": 2.34}, {"text": "if I take n bigger than\nor equal to capital M", "start": 248.98, "duration": 2.16}, {"text": "and k bigger than or\nequal to a capital M,", "start": 251.14, "duration": 2.13}, {"text": "then this difference\nis less than epsilon.", "start": 253.27, "duration": 2.67}, {"text": "Then if n is bigger\nthan or equal to M,", "start": 255.94, "duration": 5.97}, {"text": "k is bigger than or equal to M,\nand I look at 1 over n minus 1", "start": 261.91, "duration": 4.71}, {"text": "over k, this is less than\nor equal to, by the triangle", "start": 266.62, "duration": 4.47}, {"text": "inequality, the\nabsolute value of each", "start": 271.09, "duration": 3.45}, {"text": "of these added together, which\nis just 1 over n plus 1 over k.", "start": 274.54, "duration": 5.01}, {"text": "And since these are both\nbigger than or equal to M,", "start": 279.55, "duration": 3.06}, {"text": "each 1 is less than\nor equal to 1 over M 1", "start": 282.61, "duration": 3.705}, {"text": "over M, so I get 2 over M,\nwhich, by our choice of M,", "start": 286.315, "duration": 4.635}, {"text": "is less than epsilon.", "start": 290.95, "duration": 3.41}, {"text": "So x of n equals 1 over n is an\nexample of a Cauchy sequence.", "start": 294.36, "duration": 7.33}, {"text": "So let's negate the\ndefinition, and then we'll", "start": 301.69, "duration": 8.68}, {"text": "look at an example of a\nsequence which is not Cauchy.", "start": 310.37, "duration": 2.23}, {"text": "And as you'll probably guess, if\nthis is our favorite sequence,", "start": 312.6, "duration": 2.625}, {"text": "which converges, our favorite\nsequence which doesn't converge", "start": 315.225, "duration": 4.535}, {"text": "will be an example of a\nsequence which is not Cauchy.", "start": 319.76, "duration": 3.885}, {"text": "And this should shouldn't\ncome as a surprise.", "start": 323.645, "duration": 1.875}, {"text": "Because, again, a sequence\nwhich is Cauchy, if you", "start": 325.52, "duration": 4.56}, {"text": "go far enough out,\nany two entries", "start": 330.08, "duration": 3.33}, {"text": "are close to each other.", "start": 333.41, "duration": 1.74}, {"text": "But if we look at, for\nexample, the sequence minus 1", "start": 335.15, "duration": 2.22}, {"text": "to the n, which is just\nminus 1 plus 1 minus 1,", "start": 337.37, "duration": 2.64}, {"text": "any two entries will differ by--", "start": 340.01, "duration": 4.987}, {"text": "or you can always\nchoose two entries--", "start": 344.997, "duration": 1.583}, {"text": "that differ by 2 in distance.", "start": 346.58, "duration": 5.83}, {"text": "So let's negate this\ndefinition to get what it means", "start": 352.41, "duration": 8.47}, {"text": "for something not to be Cauchy.", "start": 360.88, "duration": 2.4}, {"text": "So we'll not write all that out.", "start": 363.28, "duration": 3.42}, {"text": "So x of n is not Cauchy if--", "start": 373.45, "duration": 4.65}, {"text": "so every time we\nsee a \"for all,\"", "start": 378.1, "duration": 2.19}, {"text": "it becomes \"there exists.\"", "start": 380.29, "duration": 3.75}, {"text": "If there exists a bad\nepsilon 0 positive", "start": 384.04, "duration": 5.1}, {"text": "such that for all\nM, a natural number,", "start": 389.14, "duration": 4.89}, {"text": "you can find two entries\nfurther out than M", "start": 394.03, "duration": 4.68}, {"text": "that are greater than epsilon\n0 distance to each other.", "start": 398.71, "duration": 3.28}, {"text": "So there exists n bigger\nthan or equal to M", "start": 401.99, "duration": 3.44}, {"text": "and k bigger than or equal to\nM such that x of n minus x of k", "start": 405.43, "duration": 7.68}, {"text": "is bigger than or equal\nto this bad epsilon.", "start": 413.11, "duration": 1.89}, {"text": "OK", "start": 417.72, "duration": 2.53}, {"text": "Again, the definition\nof Cauchy means", "start": 420.25, "duration": 3.03}, {"text": "that, as long as I go far\nenough out in the sequence,", "start": 423.28, "duration": 8.33}, {"text": "this distance is supposed\nto be less than epsilon.", "start": 431.61, "duration": 2.72}, {"text": "So for all epsilon positive,\nthere exists a capital M", "start": 434.33, "duration": 3.13}, {"text": "so that I have this picture.", "start": 437.46, "duration": 1.62}, {"text": "If I choose x sub k plus\n1, then it should also", "start": 439.08, "duration": 4.53}, {"text": "be within distance epsilon\nto x sub n or x sub k.", "start": 443.61, "duration": 5.22}, {"text": "So they're getting closer\nand closer together.", "start": 448.83, "duration": 2.58}, {"text": "The negation means that they're\nnot getting closer and closer", "start": 451.41, "duration": 3.27}, {"text": "together to each other.", "start": 454.68, "duration": 1.15}, {"text": "So there exists\nsome small distance", "start": 455.83, "duration": 3.27}, {"text": "so that you can always go as\nfar out as you want and find", "start": 459.1, "duration": 4.13}, {"text": "two entries that are greater\nthan epsilon 0 distance", "start": 463.23, "duration": 4.47}, {"text": "to each other.", "start": 467.7, "duration": 0.78}, {"text": "So what's an example of that?", "start": 471.51, "duration": 2.06}, {"text": "Like I said, the sequence\nminus 1 to the n is not Cauchy.", "start": 473.57, "duration": 13.18}, {"text": "That just doesn't look right.", "start": 497.04, "duration": 1.32}, {"text": "There we go.", "start": 498.36, "duration": 0.63}, {"text": "Now it is.", "start": 503.98, "duration": 0.78}, {"text": "So this is not Cauchy.", "start": 507.94, "duration": 1.35}, {"text": "So that means there should\nexist some bad epsilon 0.", "start": 509.29, "duration": 4.769}, {"text": "So I can go as far\nout as I want and find", "start": 514.059, "duration": 2.881}, {"text": "two entries in the sequence\ndiffering from each other", "start": 516.94, "duration": 3.239}, {"text": "by epsilon 0 in distance.", "start": 520.179, "duration": 2.201}, {"text": "So basically, I can\nalways find two entries", "start": 522.38, "duration": 6.56}, {"text": "in the sequence which\ndiffer from each other by 2.", "start": 528.94, "duration": 3.6}, {"text": "So that'll be my bad epsilon 0.", "start": 532.54, "duration": 3.51}, {"text": "So if you like, here's a proof.", "start": 536.05, "duration": 3.96}, {"text": "Choose epsilon 0 equals 2.", "start": 540.01, "duration": 3.855}, {"text": "Let M be a natural number.", "start": 546.83, "duration": 1.42}, {"text": "So now we have to find\nan element of entries", "start": 548.25, "duration": 3.98}, {"text": "in the sequence further out than\nM whose distance to each other", "start": 552.23, "duration": 3.412}, {"text": "is bigger than or equal to 2.", "start": 555.642, "duration": 1.208}, {"text": "We can just take M plus\n1 and capital M. Choose n", "start": 556.85, "duration": 8.24}, {"text": "equals M and k equals M plus 1.", "start": 565.09, "duration": 4.59}, {"text": "So these are both bigger\nthan or equal to M.", "start": 569.68, "duration": 3.87}, {"text": "Then minus 1 to the\nn minus 1 to the k,", "start": 573.55, "duration": 5.52}, {"text": "this is equal to 1 minus minus\n1 after I factor out a minus 1", "start": 579.07, "duration": 8.15}, {"text": "to the capital M,\nwhich equals 2.", "start": 587.22, "duration": 2.19}, {"text": "So minus 1 to the\nn is not Cauchy.", "start": 593.95, "duration": 4.095}, {"text": "So I, at the beginning,\nsaid that this", "start": 605.75, "duration": 3.69}, {"text": "will look like a definition\nof a new type of sequence,", "start": 609.44, "duration": 4.71}, {"text": "but it's not, really.", "start": 614.15, "duration": 1.59}, {"text": "So as it turns out, the\nelements of the sequence", "start": 615.74, "duration": 11.9}, {"text": "are getting closer\nand closer together", "start": 627.64, "duration": 2.37}, {"text": "as you go far enough out.", "start": 630.01, "duration": 3.01}, {"text": "So", "start": 633.02, "duration": 0.5}, {"text": "They're all kind of clustering\nnear each other, which kind of", "start": 633.52, "duration": 2.94}, {"text": "makes you think they're all\nclustering near something", "start": 636.46, "duration": 2.31}, {"text": "in the real number line.", "start": 638.77, "duration": 2.64}, {"text": "And therefore, maybe, the\nsequence is convergent.", "start": 641.41, "duration": 3.21}, {"text": "Now, this is true--\nand we'll prove this--", "start": 644.62, "duration": 5.75}, {"text": "that a sequence is Cauchy if\nand only if it's convergent.", "start": 650.37, "duration": 3.63}, {"text": "Now, this is true only\nfor the real numbers.", "start": 654.0, "duration": 2.43}, {"text": "And I'll say a little bit\nabout this in a minute--", "start": 656.43, "duration": 2.947}, {"text": "or not only true for\nthe real numbers,", "start": 659.377, "duration": 1.583}, {"text": "but it's not true for\nthe rational numbers.", "start": 660.96, "duration": 3.73}, {"text": "And I'll get to that\nin just a second.", "start": 664.69, "duration": 1.84}, {"text": "So what we're going to prove\nis that a sequence is Cauchy if", "start": 666.53, "duration": 3.56}, {"text": "and only if it is convergent.", "start": 670.09, "duration": 2.98}, {"text": "So the first thing\nI want to show", "start": 673.07, "duration": 5.85}, {"text": "is that Cauchy\nsequences are bounded.", "start": 678.92, "duration": 6.775}, {"text": "So the proof of this\nstatement is essentially", "start": 695.36, "duration": 3.45}, {"text": "the same as the proof\nthat convergent sequences", "start": 698.81, "duration": 5.35}, {"text": "are bounded.", "start": 704.16, "duration": 0.5}, {"text": "So let me draw a picture that\ngoes along with this proof.", "start": 704.66, "duration": 3.97}, {"text": "So as long as I\ngo far enough out,", "start": 708.63, "duration": 2.51}, {"text": "there exists an M so\nthat for all n bigger", "start": 711.14, "duration": 6.39}, {"text": "than or equal to capital\nM, I can say this.", "start": 717.53, "duration": 2.67}, {"text": "Let's look at this entry x\nof M. Then for all n bigger", "start": 720.2, "duration": 4.2}, {"text": "than or equal to capital\nM, all of the other entries", "start": 724.4, "duration": 2.49}, {"text": "have to be within a certain\ndistance to x sub n,", "start": 726.89, "duration": 3.6}, {"text": "based on the\ndefinition of Cauchy.", "start": 730.49, "duration": 2.67}, {"text": "So let's say I make\nthat distance 1.", "start": 733.16, "duration": 3.39}, {"text": "And let's say 0's over\nhere, just for this picture.", "start": 740.51, "duration": 3.39}, {"text": "So then for all n\nfor all n bigger", "start": 743.9, "duration": 4.5}, {"text": "than or equal to capital M,\nx sub n lies in this interval", "start": 748.4, "duration": 2.815}, {"text": "here.", "start": 751.215, "duration": 0.5}, {"text": "And therefore, we'll get\nthat x of n is bounded.", "start": 754.45, "duration": 9.11}, {"text": "So the way this picture looks,\nI'm going to write it this way.", "start": 763.56, "duration": 3.14}, {"text": "It's 1 plus 1.", "start": 766.7, "duration": 1.08}, {"text": "Now, that handles all n bigger\nthan or equal to capital M.", "start": 770.66, "duration": 3.45}, {"text": "So we just need to deal\nwith the first capital", "start": 774.11, "duration": 2.495}, {"text": "M minus 1 other guy.", "start": 776.605, "duration": 3.355}, {"text": "So maybe there's capital\nM minus 1 is over here.", "start": 779.96, "duration": 4.74}, {"text": "Capital X sub 1 is over there.", "start": 784.7, "duration": 1.59}, {"text": "Capital X sub 2 is over here.", "start": 786.29, "duration": 1.81}, {"text": "So then our bound\nwill just be this one,", "start": 788.1, "duration": 3.05}, {"text": "which handles all of the n\nbigger than or equal to M", "start": 791.15, "duration": 2.88}, {"text": "plus the absolute values of\nthese guys that we missed.", "start": 794.03, "duration": 6.105}, {"text": "So since xn is\nCauchy, there exists", "start": 804.81, "duration": 10.33}, {"text": "and M, a natural number,\nsuch that for all n", "start": 815.14, "duration": 4.91}, {"text": "bigger than or equal\nto M, and k bigger", "start": 820.05, "duration": 4.92}, {"text": "than or equal to M, x sub n\nminus x sub k is less than 1", "start": 824.97, "duration": 9.16}, {"text": "in distance.", "start": 834.13, "duration": 2.38}, {"text": "So this is certainly\ntrue for k equals", "start": 836.51, "duration": 3.41}, {"text": "capital M. So this\nimplies for all n bigger", "start": 839.92, "duration": 4.83}, {"text": "than or equal to M, x\nsub n minus x sub capital", "start": 844.75, "duration": 4.29}, {"text": "M is less than 1.", "start": 849.04, "duration": 2.16}, {"text": "So now, if I use the\ntriangle inequality,", "start": 851.2, "duration": 4.74}, {"text": "I can show that the\nprevious implies", "start": 855.94, "duration": 2.85}, {"text": "that for all n bigger\nthan or equal to M,", "start": 858.79, "duration": 2.31}, {"text": "if I look at the absolute\nvalue of x sub n,", "start": 861.1, "duration": 2.43}, {"text": "this is equal to x sub n minus\nx sub capital M plus capital M.", "start": 863.53, "duration": 8.49}, {"text": "And this is less than or\nequal to the absolute value", "start": 872.02, "duration": 2.31}, {"text": "of this guy plus the\nabsolute value of this guy.", "start": 874.33, "duration": 5.97}, {"text": "And this is bounded by 1.", "start": 880.3, "duration": 1.95}, {"text": "So in summary, I've shown\nthat for all n bigger", "start": 886.69, "duration": 5.84}, {"text": "than or equal to this\nfixed integer, capital M, x", "start": 892.53, "duration": 5.02}, {"text": "sub n is less than or\nequal to x sub capital", "start": 897.55, "duration": 5.9}, {"text": "M in absolute value plus 1.", "start": 903.45, "duration": 4.537}, {"text": "So that's for all\nlittle n bigger than", "start": 907.987, "duration": 1.583}, {"text": "or equal to capital\nM. So now I just", "start": 909.57, "duration": 1.5}, {"text": "need to pick a big enough number\nthat bounds the first capital M", "start": 911.07, "duration": 7.21}, {"text": "entries that are not\ncovered by this inequality.", "start": 918.28, "duration": 3.24}, {"text": "Capital M is fixed.", "start": 921.52, "duration": 1.005}, {"text": "So let B be the absolute\nvalue of x sub 1", "start": 926.83, "duration": 5.52}, {"text": "plus absolute value of x sub\n2 plus this fixed number now.", "start": 932.35, "duration": 11.42}, {"text": "Then for all n bigger than\nor equal to capital M,", "start": 947.49, "duration": 4.4}, {"text": "I have, by this\ninequality up here--", "start": 951.89, "duration": 3.28}, {"text": "this is a sum of\nnon-negative numbers,", "start": 958.56, "duration": 1.945}, {"text": "so this number is\ncertainly bigger than", "start": 960.505, "duration": 1.625}, {"text": "or equal to just this part.", "start": 962.13, "duration": 1.425}, {"text": "And if I have n bigger than\nequal to 1 and less than M,", "start": 969.39, "duration": 9.22}, {"text": "then x of n, the absolute\nvalue of this guy", "start": 978.61, "duration": 5.51}, {"text": "is going to be one of these\nthat appears here, which", "start": 984.12, "duration": 2.73}, {"text": "is certainly less than\nor equal to if I add", "start": 986.85, "duration": 3.54}, {"text": "on this number and the\nothers, which is less than", "start": 990.39, "duration": 3.63}, {"text": "or equal to B. So now I've found\na B which is non-negative which", "start": 994.02, "duration": 5.08}, {"text": "bounds all the absolute values.", "start": 999.1, "duration": 1.59}, {"text": "And therefore, this proves\nthat the sequence is bounded.", "start": 1000.69, "duration": 4.17}, {"text": "So we've shown that a\nCauchy sequence is bounded.", "start": 1014.16, "duration": 4.65}, {"text": "And so what I'm now going\nto show is the following.", "start": 1021.47, "duration": 10.879}, {"text": "So again, all of the entries\nare getting close to each other.", "start": 1032.349, "duration": 3.75}, {"text": "They're kind of clustering\nnear each other.", "start": 1036.099, "duration": 2.161}, {"text": "So it kind of feels like\nthey want to converge.", "start": 1038.26, "duration": 5.349}, {"text": "And this next theorem\nsays that, well,", "start": 1043.609, "duration": 2.341}, {"text": "if you've identified a\nlimit along a subsequence,", "start": 1045.95, "duration": 3.93}, {"text": "then, in fact, the entire\nsequence converges.", "start": 1049.88, "duration": 2.95}, {"text": "So of course, this is not true\nfor an arbitrary sequence.", "start": 1052.83, "duration": 3.45}, {"text": "If a subsequence converges--", "start": 1056.28, "duration": 2.99}, {"text": "or I should say, for\nan arbitrary sequence,", "start": 1059.27, "duration": 3.27}, {"text": "it's not true that a\nsubsequence converging implies", "start": 1062.54, "duration": 2.64}, {"text": "a full sequence converging.", "start": 1065.18, "duration": 1.92}, {"text": "We have minus 1 to the n for\nwhich a subsequence converges,", "start": 1067.1, "duration": 4.56}, {"text": "but the whole sequence\ndoes not converge.", "start": 1071.66, "duration": 2.13}, {"text": "But if we make the\nadditional hypothesis", "start": 1073.79, "duration": 2.4}, {"text": "that the sequence is\nCauchy, then the sequence", "start": 1076.19, "duration": 3.39}, {"text": "converges if and only if\nthat subsequence converges.", "start": 1079.58, "duration": 3.76}, {"text": "So the statement of the\ntheorem is following.", "start": 1083.34, "duration": 2.72}, {"text": "If x sub n is Cauchy and there\nexists a subsequence which", "start": 1092.38, "duration": 22.24}, {"text": "is converging to some number--", "start": 1114.62, "duration": 3.06}, {"text": "call it x-- then the whole\nsequence converges to x.", "start": 1117.68, "duration": 12.355}, {"text": "So what I was saying right\nbefore I stated this theorem is", "start": 1133.5, "duration": 2.79}, {"text": "that if I hide this\npart and just say,", "start": 1136.29, "duration": 1.83}, {"text": "there exists a subsequence\nwhich is converging to x,", "start": 1138.12, "duration": 3.48}, {"text": "this does not imply that the\nfull sequence converges to x.", "start": 1141.6, "duration": 2.67}, {"text": "Because we had this example\nof minus 1 to the n.", "start": 1144.27, "duration": 2.79}, {"text": "But if I also assume\nthe sequence is Cauchy,", "start": 1147.06, "duration": 3.84}, {"text": "then it does follow that\nCauchy plus subsequence", "start": 1150.9, "duration": 3.21}, {"text": "converging implies the\nfull sequence converges.", "start": 1154.11, "duration": 2.61}, {"text": "So I want to show that\nxn converges to x.", "start": 1161.96, "duration": 4.56}, {"text": "So want to show--", "start": 1166.52, "duration": 1.275}, {"text": "and we're going to do this\njust by using the definition,", "start": 1176.18, "duration": 5.13}, {"text": "by verifying this\nthrough the definition,", "start": 1181.31, "duration": 1.89}, {"text": "not using the squeeze theorem\nor anything like that.", "start": 1183.2, "duration": 3.818}, {"text": "So let epsilon be positive.", "start": 1187.018, "duration": 4.102}, {"text": "Since xn is Cauchy, there\nexist M0, a natural number", "start": 1198.26, "duration": 17.53}, {"text": "such that for all n\nbigger than or equal to M0", "start": 1215.79, "duration": 4.53}, {"text": "and k bigger than\nor equal to M0, x", "start": 1220.32, "duration": 6.825}, {"text": "sub n minus x sub k is\nless than epsilon over 2.", "start": 1227.145, "duration": 5.055}, {"text": "Why this epsilon over 2?", "start": 1232.2, "duration": 3.0}, {"text": "Or why should you\nnot be surprised?", "start": 1235.2, "duration": 1.53}, {"text": "Well, we have two\nassumptions here.", "start": 1236.73, "duration": 1.99}, {"text": "So like we did when we did\nconvergence of products", "start": 1238.72, "duration": 5.51}, {"text": "of sequences and so on,\nwhich had two assumptions,", "start": 1244.23, "duration": 4.86}, {"text": "namely two sequences converged\nto something, typically,", "start": 1249.09, "duration": 3.27}, {"text": "that means we'll have\ntwo integers coming.", "start": 1252.36, "duration": 1.8}, {"text": "We'll choose a bigger integer\nand then some inequalities", "start": 1254.16, "duration": 4.14}, {"text": "to get an epsilon.", "start": 1258.3, "duration": 0.94}, {"text": "So that's a little bit\nof a rambling answer", "start": 1259.24, "duration": 3.08}, {"text": "to why we get an epsilon over 2\nhere, or why we put one there.", "start": 1262.32, "duration": 4.92}, {"text": "Since the subsequence-- so this\nsubsequence converges to x--", "start": 1272.69, "duration": 7.23}, {"text": "there exists another\ninteger, M sub 1 such", "start": 1288.67, "duration": 4.92}, {"text": "that if k is bigger than\nor equal to M sub 1,", "start": 1293.59, "duration": 7.95}, {"text": "then x sub n sub k minus x\nis less than epsilon over 2.", "start": 1301.54, "duration": 9.3}, {"text": "So maybe I should have used\na different letter here.", "start": 1310.84, "duration": 2.97}, {"text": "Let's use a little m.", "start": 1313.81, "duration": 1.865}, {"text": "Because I don't\nwant you to think", "start": 1315.675, "duration": 1.375}, {"text": "these have to be the same k.", "start": 1317.05, "duration": 1.38}, {"text": "So now we'll choose an integer\nbigger than both M1 and M2", "start": 1327.95, "duration": 7.95}, {"text": "and show that it works.", "start": 1335.9, "duration": 1.42}, {"text": "Choose M to be M0 plus M1.", "start": 1337.32, "duration": 5.87}, {"text": "Now we need to show this works.", "start": 1359.47, "duration": 2.04}, {"text": "And if n is bigger than\nor equal to M, so let me,", "start": 1361.51, "duration": 11.62}, {"text": "actually, make a\nfirst observation", "start": 1373.13, "duration": 6.02}, {"text": "before I go to the n bigger\nthan or equal to capital M.", "start": 1379.15, "duration": 3.57}, {"text": "Then, since n sub k is bigger\nthan or equal to k for all", "start": 1382.72, "duration": 10.63}, {"text": "of k, a natural number-- just\nbecause the n sub k is there", "start": 1393.35, "duration": 2.94}, {"text": "in increasing\nsequence of integers,", "start": 1396.29, "duration": 2.84}, {"text": "which starts at least at 1--", "start": 1399.13, "duration": 1.68}, {"text": "and since n sub k is bigger\nthan or equal to k for all k,", "start": 1404.43, "duration": 3.69}, {"text": "this implies that the integer\nn sub capital M is bigger", "start": 1408.12, "duration": 5.4}, {"text": "than or equal to\nM, which, remember,", "start": 1413.52, "duration": 1.59}, {"text": "is M0 plus M1, which\nimplies that n sub M is", "start": 1415.11, "duration": 5.97}, {"text": "bigger than or equal\nto M0 and n sub M is", "start": 1421.08, "duration": 4.11}, {"text": "bigger than or equal to M1.", "start": 1425.19, "duration": 2.82}, {"text": "So I just wanted to make\nthis preliminary observation.", "start": 1428.01, "duration": 6.3}, {"text": "And now we'll go to showing\nthat this capital M works.", "start": 1434.31, "duration": 2.835}, {"text": "So now, if n is bigger\nthan or equal to capital", "start": 1440.36, "duration": 2.34}, {"text": "M, and I look at x sub n\nminus x, an absolute value,", "start": 1442.7, "duration": 5.47}, {"text": "and add and subtract x sub n\ncapital M capital M minus x", "start": 1448.17, "duration": 12.44}, {"text": "and use the triangle\ninequality, then--", "start": 1460.61, "duration": 13.75}, {"text": "so since n is bigger than\nor equal to capital M, which", "start": 1474.36, "duration": 3.66}, {"text": "is bigger than or\nequal to M0, that", "start": 1478.02, "duration": 2.34}, {"text": "means n is bigger\nthan or equal to M0.", "start": 1480.36, "duration": 2.85}, {"text": "And then n sub M we just showed\nis bigger than or equal to 0.", "start": 1483.21, "duration": 3.75}, {"text": "So by this inequality, I\nget that the first term", "start": 1486.96, "duration": 5.88}, {"text": "is less than epsilon over 2.", "start": 1492.84, "duration": 2.94}, {"text": "And now, so M is\ncertainly bigger than", "start": 1495.78, "duration": 6.06}, {"text": "or equal to M sub 1.", "start": 1501.84, "duration": 2.04}, {"text": "And therefore, I will get that\nthis part is less than epsilon", "start": 1503.88, "duration": 6.06}, {"text": "over 2 because of\nthis inequality.", "start": 1509.94, "duration": 4.24}, {"text": "So that choice of\ncapital M works.", "start": 1514.18, "duration": 8.47}, {"text": "And now, we'll\nprove the following,", "start": 1527.78, "duration": 8.02}, {"text": "that a sequence is convergent\nif and only if it's Cauchy.", "start": 1535.8, "duration": 3.75}, {"text": "So this is a two-way street.", "start": 1567.14, "duration": 1.75}, {"text": "So we need to show the\nleft implies the right", "start": 1568.89, "duration": 3.38}, {"text": "and then the right\nimplies the left.", "start": 1572.27, "duration": 1.665}, {"text": "So this direction\nis, in fact, easy.", "start": 1580.8, "duration": 9.757}, {"text": "Based on what we've done--", "start": 1590.557, "duration": 1.083}, {"text": "I shouldn't say it's easy--", "start": 1591.64, "duration": 1.14}, {"text": "but what we've done so\nfar, it quickly follows.", "start": 1592.78, "duration": 2.97}, {"text": "So we're assuming\nx sub n is Cauchy.", "start": 1602.31, "duration": 3.14}, {"text": "I'm trying to show\nit's convergent.", "start": 1605.45, "duration": 1.47}, {"text": "So if x sub n is\nCauchy, this implies", "start": 1612.25, "duration": 2.91}, {"text": "that x sub n is bounded,\nthe sequence is bounded,", "start": 1615.16, "duration": 7.08}, {"text": "which implies by the\nBolzano-Weierstrass theorem", "start": 1622.24, "duration": 3.48}, {"text": "that x sub n has a\nconvergent subsequence.", "start": 1625.72, "duration": 15.11}, {"text": "And by the theorem\nwe just proved,", "start": 1640.83, "duration": 1.89}, {"text": "if a Cauchy sequence has\na convergent subsequence,", "start": 1642.72, "duration": 3.81}, {"text": "it must be convergent.", "start": 1646.53, "duration": 1.32}, {"text": "Now, for the converse\ndirection, that xn", "start": 1656.05, "duration": 3.39}, {"text": "is convergent implies xn\nis Cauchy, well, so this", "start": 1659.44, "duration": 5.13}, {"text": "should not come as a surprise.", "start": 1664.57, "duration": 1.26}, {"text": "Let me draw a picture.", "start": 1665.83, "duration": 0.917}, {"text": "Let's suppose x sub\nn is converging to x,", "start": 1670.51, "duration": 5.35}, {"text": "and epsilon is positive.", "start": 1675.86, "duration": 1.77}, {"text": "Then, since the\nxn's are converging", "start": 1680.55, "duration": 3.0}, {"text": "to x, if I draw a\nlittle interval around x", "start": 1683.55, "duration": 9.3}, {"text": "of total length epsilon--", "start": 1692.85, "duration": 3.07}, {"text": "so x minus epsilon over 2\nand x plus epsilon over 2--", "start": 1695.92, "duration": 3.38}, {"text": "then I will find, as long\nas so then there exists M", "start": 1699.3, "duration": 5.61}, {"text": "so that, for all n bigger\nthan or equal to capital M,", "start": 1704.91, "duration": 4.89}, {"text": "all of the x sub n's\nlie in this interval.", "start": 1709.8, "duration": 5.67}, {"text": "They all lie in this\ninterval because they", "start": 1721.54, "duration": 1.75}, {"text": "have to be within\ndistance epsilon over 2", "start": 1723.29, "duration": 1.8}, {"text": "to x if the xn's\nare converging to x.", "start": 1725.09, "duration": 5.46}, {"text": "And since they lie\nin this interval,", "start": 1730.55, "duration": 1.86}, {"text": "the distance between\nany two of them", "start": 1732.41, "duration": 2.37}, {"text": "can only be as big as the\nlength of the interval, which", "start": 1734.78, "duration": 2.7}, {"text": "is epsilon.", "start": 1737.48, "duration": 2.79}, {"text": "So this is essentially\nthe picture", "start": 1740.27, "duration": 3.78}, {"text": "of why a convergence\nsequence has to be Cauchy.", "start": 1744.05, "duration": 2.67}, {"text": "So now let's turn this\npicture into math.", "start": 1746.72, "duration": 1.8}, {"text": "We have to verify xn is\nCauchy through the definition.", "start": 1753.2, "duration": 2.34}, {"text": "That's all we have.", "start": 1755.54, "duration": 1.02}, {"text": "So let epsilon be positive.", "start": 1756.56, "duration": 3.48}, {"text": "Since the xn's\nconverge to x, there", "start": 1760.04, "duration": 4.32}, {"text": "exists an integer M sub\n0, a natural number,", "start": 1764.36, "duration": 3.84}, {"text": "such that for all n bigger\nthan or equal to M sub 0, x", "start": 1768.2, "duration": 5.64}, {"text": "sub n minus x is less\nthan epsilon over 2.", "start": 1773.84, "duration": 3.42}, {"text": "And so we'll choose the M\nfor our definition of Cauchy", "start": 1782.86, "duration": 4.65}, {"text": "to be this M sub 0.", "start": 1787.51, "duration": 1.41}, {"text": "And if n is bigger\nthan or equal to M", "start": 1792.52, "duration": 3.66}, {"text": "and k is bigger\nthan or equal to M", "start": 1796.18, "duration": 3.51}, {"text": "and I look at the absolute\nvalue of x sub n minus x sub k", "start": 1799.69, "duration": 4.62}, {"text": "and add and subtract x and\nuse the triangle inequality,", "start": 1804.31, "duration": 4.14}, {"text": "this is less than\nor equal to x sub", "start": 1808.45, "duration": 1.65}, {"text": "n minus x, an absolute\nvalue, plus x minus x sub k.", "start": 1810.1, "duration": 6.93}, {"text": "Each of these is less\nthan epsilon over 2", "start": 1817.03, "duration": 5.1}, {"text": "since n is bigger than\nor equal to capital M,", "start": 1822.13, "duration": 1.988}, {"text": "and k is bigger than\nor equal to capital M.", "start": 1824.118, "duration": 1.792}, {"text": "So this is less than epsilon\nover 2 plus epsilon over 2", "start": 1825.91, "duration": 4.2}, {"text": "equals epsilon.", "start": 1830.11, "duration": 1.29}, {"text": "And therefore, xn is Cauchy.", "start": 1831.4, "duration": 1.5}, {"text": "Now I want to make\na brief remark", "start": 1837.23, "duration": 4.5}, {"text": "about the previous theorem.", "start": 1841.73, "duration": 3.24}, {"text": "So remember how this\nwhole story started off?", "start": 1847.94, "duration": 3.18}, {"text": "There was something wrong with\nthe rational numbers, namely,", "start": 1856.07, "duration": 5.06}, {"text": "they didn't contain\nthe square root of 2.", "start": 1861.13, "duration": 2.76}, {"text": "So we couldn't solve\nthe algebraic equation", "start": 1863.89, "duration": 2.34}, {"text": "x squared minus 2 equals 0.", "start": 1866.23, "duration": 2.79}, {"text": "But this also, then,\nturned into the rationals", "start": 1869.02, "duration": 4.74}, {"text": "not being complete in\nthe sense of order.", "start": 1873.76, "duration": 3.72}, {"text": "Not every non-empty\nbounded set had a supremum.", "start": 1877.48, "duration": 3.348}, {"text": "It didn't have the least\nupper bound property.", "start": 1880.828, "duration": 1.917}, {"text": "But you can also interpret this\nlack of having square root of 2", "start": 1885.7, "duration": 5.16}, {"text": "as somehow saying\nthat the rationals are", "start": 1890.86, "duration": 6.24}, {"text": "incomplete in this sense.", "start": 1897.1, "duration": 1.93}, {"text": "So hopefully, at the\nend of this class,", "start": 1899.03, "duration": 3.747}, {"text": "we'll be able to get\nto metrics basis.", "start": 1902.777, "duration": 1.583}, {"text": "But so what do I mean by that?", "start": 1904.36, "duration": 4.03}, {"text": "Let's say I look\nat this statement", "start": 1908.39, "duration": 1.82}, {"text": "now within the universe\nof rational numbers.", "start": 1910.21, "duration": 4.87}, {"text": "So now, if this sequence\nis rational numbers--", "start": 1919.26, "duration": 19.03}, {"text": "meaning sequences are only\nsequences of rational numbers,", "start": 1938.29, "duration": 4.07}, {"text": "limits are only elements\nof the rational numbers,", "start": 1942.36, "duration": 5.01}, {"text": "epsilon is only a rational\nnumber, and so on-- then", "start": 1947.37, "duration": 5.1}, {"text": "we still have many\nof the same theorems", "start": 1952.47, "duration": 2.01}, {"text": "that we proved--\nnot all of them,", "start": 1954.48, "duration": 2.22}, {"text": "and I'll indicate\nwhich ones don't hold.", "start": 1956.7, "duration": 3.28}, {"text": "But if we only\nwork in rationals,", "start": 1959.98, "duration": 1.55}, {"text": "then we always do have a\nconvergence implies Cauchy,", "start": 1961.53, "duration": 11.38}, {"text": "meaning convergent\nsequences are Cauchy.", "start": 1972.91, "duration": 4.23}, {"text": "But Cauchy sequences are\nnot necessarily convergent.", "start": 1977.14, "duration": 13.74}, {"text": "Again, what's the\nexample here, or what's", "start": 1990.88, "duration": 8.44}, {"text": "the intuitive example?", "start": 1999.32, "duration": 1.17}, {"text": "Take x sub n so\nthat x of n is in Q.", "start": 2000.49, "duration": 11.05}, {"text": "And now viewed in the\nuniverse of real numbers,", "start": 2011.54, "duration": 6.62}, {"text": "x sub n's converge to root 2.", "start": 2018.16, "duration": 1.815}, {"text": "Then such a sequence would\nbe a Cauchy sequence.", "start": 2026.59, "duration": 4.38}, {"text": "We just proved that, basically.", "start": 2030.97, "duration": 2.34}, {"text": "So such a sequence would\nbe a Cauchy sequence", "start": 2033.31, "duration": 2.19}, {"text": "of rational numbers.", "start": 2035.5, "duration": 1.71}, {"text": "However, it would not converge\nin the set of rational numbers.", "start": 2037.21, "duration": 3.95}, {"text": "It would converge to\nthe square root of 2,", "start": 2041.16, "duration": 1.75}, {"text": "which is not a rational number.", "start": 2042.91, "duration": 1.87}, {"text": "So because the square root of\n2 is not a rational number,", "start": 2044.78, "duration": 5.04}, {"text": "this shows that the\nrational numbers do not", "start": 2049.82, "duration": 1.919}, {"text": "have this completeness property\nthat Cauchy sequences converge.", "start": 2051.739, "duration": 4.68}, {"text": "So there's a whole,\nstill, to this day, kind", "start": 2062.34, "duration": 4.87}, {"text": "of industry of studying\nspaces for which Cauchy", "start": 2067.21, "duration": 4.35}, {"text": "is equivalent to convergent.", "start": 2071.56, "duration": 2.55}, {"text": "These are called\ncomplete metric spaces.", "start": 2074.11, "duration": 1.799}, {"text": "And then if you add a\nlittle more structure,", "start": 2075.909, "duration": 1.833}, {"text": "they're called Banach\nspaces and so on,", "start": 2077.742, "duration": 4.147}, {"text": "which are very important,\nnot just in math", "start": 2081.889, "duration": 1.75}, {"text": "but also for\nformulating rigorously", "start": 2083.639, "duration": 6.27}, {"text": "a lot of the\nunderlying assumptions", "start": 2089.909, "duration": 6.421}, {"text": "for mathematical physics.", "start": 2096.33, "duration": 1.86}, {"text": "So if we're just looking\ninside the rationals,", "start": 2101.96, "duration": 2.76}, {"text": "it does not follow that Cauchy\nsequences always converge.", "start": 2104.72, "duration": 3.48}, {"text": "And now let's just\nstop for a minute", "start": 2108.2, "duration": 1.8}, {"text": "and take stock of why this\nwas true for the real numbers.", "start": 2110.0, "duration": 3.43}, {"text": "What did we use going back?", "start": 2113.43, "duration": 1.756}, {"text": "So if you really go\nback to the proof", "start": 2115.186, "duration": 8.374}, {"text": "of the Bolzano-Weierstrass--\nso that's what we used here", "start": 2123.56, "duration": 3.57}, {"text": "to show that Cauchy\nsequences converge--", "start": 2127.13, "duration": 2.25}, {"text": "we use the fact that the lim sup\nand the lim inf always exists.", "start": 2132.11, "duration": 5.37}, {"text": "And lim sup and lim\ninf, first off, they're", "start": 2137.48, "duration": 3.63}, {"text": "defined to be sups and\ninfs, which may not always", "start": 2141.11, "duration": 2.16}, {"text": "exist as rational numbers,\nas we've already shown.", "start": 2143.27, "duration": 2.88}, {"text": "So that's definitely a\nproblem already there.", "start": 2146.15, "duration": 5.28}, {"text": "But even more so, when we prove\nthat every bounded monotone", "start": 2151.43, "duration": 4.02}, {"text": "sequence converges,\nwhat we showed", "start": 2155.45, "duration": 2.76}, {"text": "was that this limit is\nactually a sup of a certain set", "start": 2158.21, "duration": 3.27}, {"text": "or an inf of a certain set,\nwhich, again, may or may not", "start": 2161.48, "duration": 2.843}, {"text": "exist if we're just looking\nin the rational numbers.", "start": 2164.323, "duration": 2.167}, {"text": "Because the rational numbers do\nnot have the least upper bound", "start": 2166.49, "duration": 2.7}, {"text": "property.", "start": 2169.19, "duration": 1.23}, {"text": "So it really is the least\nupper bound property", "start": 2170.42, "duration": 4.17}, {"text": "that gives us\nconvergence equivalent", "start": 2174.59, "duration": 3.66}, {"text": "to Cauchy for the real numbers.", "start": 2178.25, "duration": 2.17}, {"text": "So for R, the least\nupper bound property is--", "start": 2180.42, "duration": 12.492}, {"text": "it has to be because\nthat's the main thing that", "start": 2192.912, "duration": 1.958}, {"text": "separates the two fields,\nbut I'm just reiterating this", "start": 2194.87, "duration": 4.89}, {"text": "here--", "start": 2199.76, "duration": 1.56}, {"text": "is the reason why convergent\nis equivalent to Cauchy.", "start": 2201.32, "duration": 12.1}, {"text": "Now that I've proved that Cauchy\nis equivalent to convergence,", "start": 2227.75, "duration": 5.49}, {"text": "maybe you'll ask, then why\ndid we introduce it at all?", "start": 2233.24, "duration": 2.73}, {"text": "If these two notions\nare the same,", "start": 2238.48, "duration": 4.96}, {"text": "why even introduce\nthem if they're just", "start": 2243.44, "duration": 2.19}, {"text": "convergent sequences already?", "start": 2245.63, "duration": 2.23}, {"text": "And the reason is because to\nshow that a sequence converges,", "start": 2247.86, "duration": 6.59}, {"text": "you have to somehow\nhave your hands", "start": 2254.45, "duration": 1.86}, {"text": "on a candidate for the limit.", "start": 2256.31, "duration": 4.47}, {"text": "If you want to prove\nthat xn converges,", "start": 2260.78, "duration": 4.71}, {"text": "you have to somehow come up\nwith an x that it converges to.", "start": 2265.49, "duration": 3.39}, {"text": "And it's not always\nclear how to find that x.", "start": 2268.88, "duration": 6.234}, {"text": "But Cauchy, although it's\nequivalent to a convergent", "start": 2275.114, "duration": 3.306}, {"text": "in the set of real\nnumbers, doesn't", "start": 2278.42, "duration": 3.45}, {"text": "require you to find a\ncandidate for convergence.", "start": 2281.87, "duration": 5.28}, {"text": "All it requires\nyou to do is show", "start": 2287.15, "duration": 2.67}, {"text": "that, as long as you\ngo far enough out,", "start": 2289.82, "duration": 3.61}, {"text": "any two entries in the\nsequence are close together", "start": 2293.43, "duration": 4.98}, {"text": "without requiring you\nto come up with a limit.", "start": 2298.41, "duration": 2.62}, {"text": "See, computing limits\nis quite difficult.", "start": 2301.03, "duration": 2.15}, {"text": "We're about to do series.", "start": 2303.18, "duration": 1.71}, {"text": "And there's maybe, I don't\nknow, five series people", "start": 2304.89, "duration": 3.15}, {"text": "can compute explicitly.", "start": 2308.04, "duration": 1.937}, {"text": "But you do know that there's\na ton of other series", "start": 2309.977, "duration": 2.083}, {"text": "that are actually convergent,\neven though you don't know what", "start": 2312.06, "duration": 2.7}, {"text": "the limit as.", "start": 2314.76, "duration": 1.32}, {"text": "And why do you know that?", "start": 2316.08, "duration": 1.65}, {"text": "This is exactly\nbecause and exactly", "start": 2317.73, "duration": 2.16}, {"text": "why people thought\nof Cauchy sequences", "start": 2319.89, "duration": 3.96}, {"text": "to begin with in\nmuch of analysis.", "start": 2323.85, "duration": 2.59}, {"text": "So again, just to\nsummarize this,", "start": 2326.44, "duration": 5.33}, {"text": "convergent sequences are nice.", "start": 2331.77, "duration": 1.47}, {"text": "But in practice, it's\ndifficult to get your hands", "start": 2333.24, "duration": 2.94}, {"text": "on what could be a\nlimit of a sequence,", "start": 2336.18, "duration": 2.1}, {"text": "especially if that sequence\nis pretty complicated.", "start": 2338.28, "duration": 3.37}, {"text": "So if you're trying to show\na certain sequence converges,", "start": 2341.65, "duration": 3.5}, {"text": "it suffices, by what we've done\nhere, to show that it's Cauchy.", "start": 2345.15, "duration": 4.18}, {"text": "And that's a little bit\neasier to do because that just", "start": 2349.33, "duration": 3.51}, {"text": "requires you to work with\nthe original sequence.", "start": 2352.84, "duration": 2.485}, {"text": "You don't have to\ncome up with a limit.", "start": 2355.325, "duration": 1.625}, {"text": "You can just take your sequence\nand start playing directly", "start": 2356.95, "duration": 4.41}, {"text": "with the entries rather than\ntry to come up with a limit", "start": 2361.36, "duration": 6.01}, {"text": "explicitly.", "start": 2367.37, "duration": 0.93}, {"text": "So that's what we're\ngoing to move on to", "start": 2372.02, "duration": 2.46}, {"text": "is series now, which,\nas I said a minute ago,", "start": 2374.48, "duration": 5.46}, {"text": "is original reason why\npeople started developing", "start": 2379.94, "duration": 8.81}, {"text": "the foundations of\nanalysis, what we're talking", "start": 2388.75, "duration": 2.248}, {"text": "about right now, to begin with.", "start": 2390.998, "duration": 1.292}, {"text": "Because they were just kind\nof doing very formal things", "start": 2395.64, "duration": 6.33}, {"text": "that ended up not\nmaking sense, like they", "start": 2401.97, "duration": 5.07}, {"text": "were adding infinitely\nmany positive numbers", "start": 2407.04, "duration": 2.94}, {"text": "and coming up with\na negative number.", "start": 2409.98, "duration": 3.048}, {"text": "Well, that can't be right.", "start": 2413.028, "duration": 1.252}, {"text": "So all of this was\ncreated, discovered--", "start": 2414.28, "duration": 7.31}, {"text": "however you want to phrase it--", "start": 2421.59, "duration": 1.56}, {"text": "to put on rigorous\nfoundations this next topic,", "start": 2423.15, "duration": 6.143}, {"text": "which is series.", "start": 2429.293, "duration": 0.667}, {"text": "And you dealt with\nseries in calculus,", "start": 2435.2, "duration": 3.51}, {"text": "so you know what a series is.", "start": 2438.71, "duration": 1.885}, {"text": "Maybe you don't\nremember all the proofs", "start": 2440.595, "duration": 1.625}, {"text": "of the properties of series.", "start": 2442.22, "duration": 1.35}, {"text": "But suffice it to say, series\nis a pretty good motivation", "start": 2443.57, "duration": 6.16}, {"text": "since it's one of the most\nuseful things that comes out", "start": 2449.73, "duration": 4.375}, {"text": "of math.", "start": 2454.105, "duration": 0.5}, {"text": "Series expansions are\nhow you solve ODEs, PDEs,", "start": 2458.79, "duration": 6.21}, {"text": "Taylor expansions.", "start": 2465.0, "duration": 1.02}, {"text": "All these things are, in\nsome sense, a form of series.", "start": 2466.02, "duration": 3.33}, {"text": "So being able to justify\nthem as being real things", "start": 2469.35, "duration": 5.25}, {"text": "is a necessity.", "start": 2474.6, "duration": 2.56}, {"text": "So the definition of\na series, for now,", "start": 2477.16, "duration": 8.66}, {"text": "really is just this symbol\nI'm about to write down.", "start": 2485.82, "duration": 2.7}, {"text": "So given a sequence\nx sub n, the symbol--", "start": 2488.52, "duration": 8.945}, {"text": "or maybe I'll just sometimes\nwrite just the sum x sub n--", "start": 2505.13, "duration": 3.105}, {"text": "is what's called the series\nassociated to the sequence", "start": 2510.8, "duration": 9.31}, {"text": "x sub n.", "start": 2520.11, "duration": 0.56}, {"text": "So right now, that's\njust a symbol.", "start": 2523.607, "duration": 1.458}, {"text": "We're going to interpret\nthis as a real number", "start": 2527.6, "duration": 2.46}, {"text": "in the following situation.", "start": 2530.06, "duration": 1.53}, {"text": "We say that the\nseries converges,", "start": 2535.04, "duration": 13.34}, {"text": "if the following sequence\ngiven by s sub m equals--", "start": 2548.38, "duration": 20.51}, {"text": "so s sub m, this is the\nelement of the sequence.", "start": 2574.06, "duration": 3.06}, {"text": "And what is it?", "start": 2577.12, "duration": 0.84}, {"text": "It is the actual sum.", "start": 2577.96, "duration": 1.93}, {"text": "So this is not a formal thing.", "start": 2579.89, "duration": 1.38}, {"text": "This is just a finite\nsum from n equals 1 to m.", "start": 2581.27, "duration": 3.56}, {"text": "So this is-- so this sequence\nnow, m equals 1 to infinity.", "start": 2584.83, "duration": 10.24}, {"text": "And these guys we call\npartial sums converges.", "start": 2600.0, "duration": 14.07}, {"text": "So right now, if we just\nhave a sequence x sub n,", "start": 2616.87, "duration": 5.04}, {"text": "the series associated to that\nsequence is just a symbol.", "start": 2621.91, "duration": 4.5}, {"text": "We say that this\nseries converges", "start": 2626.41, "duration": 1.8}, {"text": "if this sequence of\npartial sums converge", "start": 2628.21, "duration": 4.72}, {"text": "and if s is this limit.", "start": 2632.93, "duration": 9.43}, {"text": "And we write s is\nequal to the series", "start": 2651.81, "duration": 13.26}, {"text": "and treat the series\nnow as a number.", "start": 2665.07, "duration": 1.8}, {"text": "So in general, if\nI have a sequence,", "start": 2677.03, "duration": 1.98}, {"text": "I just have this formal\nsymbol, which I'm writing down,", "start": 2679.01, "duration": 3.73}, {"text": "which I call a series\nassociated to it.", "start": 2682.74, "duration": 2.96}, {"text": "In the case that the sequence\nof partial sums converges,", "start": 2685.7, "duration": 3.85}, {"text": "then I actually identify this\nseries with a real number", "start": 2689.55, "duration": 3.585}, {"text": "and treat it as a real number.", "start": 2693.135, "duration": 1.25}, {"text": "And so the way\nI've written this,", "start": 2699.12, "duration": 3.96}, {"text": "the series is starting at 1.", "start": 2703.08, "duration": 1.44}, {"text": "But it doesn't\nnecessarily have to.", "start": 2704.52, "duration": 2.01}, {"text": "So just by shifting the index--", "start": 2706.53, "duration": 4.905}, {"text": "so let me just say here\nthat we don't necessarily", "start": 2716.08, "duration": 9.69}, {"text": "have to start a\nseries at n equals 1.", "start": 2725.77, "duration": 9.63}, {"text": "So this could be\nsum from n equals 0", "start": 2735.4, "duration": 2.25}, {"text": "to infinity, in which case, we\nhave a sequence starting now", "start": 2737.65, "duration": 3.0}, {"text": "at x sub 0.", "start": 2740.65, "duration": 1.53}, {"text": "Or this could be starting\nat 2, in which place", "start": 2742.18, "duration": 3.24}, {"text": "the sequence of x sub\nn starts at n equals 2.", "start": 2745.42, "duration": 3.12}, {"text": "And then the sequence\nof partial sums", "start": 2748.54, "duration": 2.43}, {"text": "would start at not m\nequals 1 but m equals 0", "start": 2750.97, "duration": 3.3}, {"text": "or m equals 2, depending\non where the series starts.", "start": 2754.27, "duration": 3.57}, {"text": "So some examples.", "start": 2760.86, "duration": 0.84}, {"text": "The series sum from n equals\n1 to infinity 1 over n", "start": 2765.18, "duration": 8.93}, {"text": "plus 1 times n, this\nis a convergent series.", "start": 2774.11, "duration": 7.47}, {"text": "So why is this?", "start": 2786.01, "duration": 1.935}, {"text": "So let's look at the proof.", "start": 2787.945, "duration": 1.125}, {"text": "So we look at the\nm-th partial sum--", "start": 2789.07, "duration": 2.7}, {"text": "this is the sum from n equals\n1 to m of 1 over n plus 1n.", "start": 2791.77, "duration": 6.93}, {"text": "And this is equal to--", "start": 2798.7, "duration": 2.73}, {"text": "now, if I write 1 over n plus\n1 times n as 1 over n minus 1", "start": 2801.43, "duration": 15.11}, {"text": "over n plus 1, this is\nnow the sum of 1 over n", "start": 2816.54, "duration": 4.98}, {"text": "plus-- these are finite sums,\nso I can always split them up.", "start": 2821.52, "duration": 3.87}, {"text": "This should be a minus.", "start": 2827.747, "duration": 0.958}, {"text": "And so now, this is\nequal to 1 plus 1/2", "start": 2831.64, "duration": 2.91}, {"text": "plus 1 over m minus 1/2\nplus 1/3 plus 1 over m", "start": 2834.55, "duration": 12.0}, {"text": "plus 1 over n plus 1.", "start": 2846.55, "duration": 4.41}, {"text": "And you see all of these cancel.", "start": 2850.96, "duration": 4.02}, {"text": "And all that's left is\n1 minus 1 over m plus 1.", "start": 2854.98, "duration": 5.82}, {"text": "So the m-th partial sum is equal\nto 1 minus 1 over m plus 1.", "start": 2860.8, "duration": 5.01}, {"text": "And therefore, the\nsequence of partial sums", "start": 2865.81, "duration": 7.48}, {"text": "is the limit as m\ngoes to infinity", "start": 2873.29, "duration": 1.62}, {"text": "of this, which is just 1.", "start": 2874.91, "duration": 2.2}, {"text": "And therefore, this\nseries converges.", "start": 2877.11, "duration": 2.84}, {"text": "Now, our favorite sequence,\nwhich does not converge,", "start": 2889.61, "duration": 4.44}, {"text": "will give us a series\nwhich does not converge.", "start": 2894.05, "duration": 2.64}, {"text": "So let's look at sum from n\nequals 1 to infinity minus 1", "start": 2896.69, "duration": 5.55}, {"text": "to the n.", "start": 2902.24, "duration": 1.2}, {"text": "This does not converge.", "start": 2903.44, "duration": 3.06}, {"text": "So what's the proof?", "start": 2909.532, "duration": 0.833}, {"text": "The m-th partial sum,\nthis is equal to minus 1", "start": 2913.1, "duration": 6.24}, {"text": "plus 1 plus minus 1 up until\nI get minus 1 to the m.", "start": 2919.34, "duration": 6.14}, {"text": "And therefore, this is always\nequal to one of two things.", "start": 2928.61, "duration": 6.45}, {"text": "If m is odd, then I have an\nodd number of these guys.", "start": 2935.06, "duration": 7.61}, {"text": "And therefore, the\nminuses and pluses", "start": 2942.67, "duration": 4.38}, {"text": "cancel, just leaving\na minus 1 in the end--", "start": 2947.05, "duration": 3.75}, {"text": "this last one, the odd one.", "start": 2950.8, "duration": 1.44}, {"text": "And m is odd and 0 if m is even.", "start": 2955.9, "duration": 5.86}, {"text": "If I add up an even\nnumber of these terms,", "start": 2961.76, "duration": 4.2}, {"text": "then all of the minus\n1's and 1's cancel out,", "start": 2965.96, "duration": 2.23}, {"text": "so I just get 0.", "start": 2968.19, "duration": 1.49}, {"text": "And therefore, this sequence,\nwhich is just minus 1", "start": 2969.68, "duration": 10.25}, {"text": "for m odd, 0 for m\neven, does not converge.", "start": 2979.93, "duration": 11.487}, {"text": "And therefore, the\nseries does not converge.", "start": 2991.417, "duration": 1.833}, {"text": "So when I write this,\nthis is just a symbol.", "start": 2993.25, "duration": 3.0}, {"text": "This is just chalk\non a chalkboard.", "start": 2996.25, "duration": 1.838}, {"text": "It doesn't mean anything.", "start": 2998.088, "duration": 1.042}, {"text": "So let's go to another\nseries, which does converge.", "start": 3006.32, "duration": 6.0}, {"text": "And this is kind of\nthe one to which we", "start": 3012.32, "duration": 5.22}, {"text": "compare all other series,\nessentially, as you'll see.", "start": 3017.54, "duration": 4.98}, {"text": "You have all these series tests\nthat you remember, hopefully,", "start": 3022.52, "duration": 3.18}, {"text": "from calculus that tell you\nwhen a series converges.", "start": 3025.7, "duration": 7.0}, {"text": "But maybe, if you\nremember the proof", "start": 3032.7, "duration": 2.58}, {"text": "or don't, how you do\nthat is you converge it", "start": 3035.28, "duration": 2.46}, {"text": "to one series, which\nyou do know how to sum.", "start": 3037.74, "duration": 2.58}, {"text": "So it was just by pure luck we\nwere able to compute the sum,", "start": 3040.32, "duration": 5.34}, {"text": "or compute the explicit\nseries for this guy.", "start": 3045.66, "duration": 4.71}, {"text": "Another one which we can do\nthat for is geometric series.", "start": 3050.37, "duration": 3.64}, {"text": "So the theorem is if\nI have a real number", "start": 3054.01, "duration": 4.22}, {"text": "with absolute value less\nthan 1, then the series", "start": 3058.23, "duration": 7.77}, {"text": "starting now at 0 R\nto the n converges.", "start": 3066.0, "duration": 7.23}, {"text": "And I can actually compute\nthe sum of this series.", "start": 3073.23, "duration": 6.57}, {"text": "And this is 1 over 1 minus r.", "start": 3079.8, "duration": 3.09}, {"text": "So what's the proof?", "start": 3088.775, "duration": 2.595}, {"text": "Let's look at the partial sums.", "start": 3091.37, "duration": 2.46}, {"text": "And we can actually\ncompute these, as well,", "start": 3093.83, "duration": 4.23}, {"text": "just as we were able to\ndo for the first example.", "start": 3098.06, "duration": 2.55}, {"text": "We compute that the sum from n\nequals 0 to m of r to the m--", "start": 3105.63, "duration": 6.44}, {"text": "now, you can prove\nthis by induction.", "start": 3112.07, "duration": 2.94}, {"text": "I cannot exactly\nremember if I did this--", "start": 3115.01, "duration": 2.52}, {"text": "I believe I did-- in\nthe second lecture", "start": 3120.44, "duration": 1.8}, {"text": "on induction, first or second\nlecture on the induction.", "start": 3122.24, "duration": 2.52}, {"text": "But if I add up some\nnumber raised to the n-th--", "start": 3124.76, "duration": 4.41}, {"text": "so this should be to the n--", "start": 3129.17, "duration": 2.91}, {"text": "power from 0 to m, this\nis equal to 1 minus r", "start": 3132.08, "duration": 3.36}, {"text": "to the m plus 1 over 1 minus r.", "start": 3135.44, "duration": 5.23}, {"text": "And I guess two lectures\nago, we proved that", "start": 3140.67, "duration": 5.46}, {"text": "if the absolute value--", "start": 3146.13, "duration": 1.96}, {"text": "so let me state this now.", "start": 3148.09, "duration": 2.585}, {"text": "Two lectures ago, we proved\nthat if the absolute value of r", "start": 3158.49, "duration": 7.8}, {"text": "is less than 1, then limit as,\nlet's make it m, of r to the m", "start": 3166.29, "duration": 9.12}, {"text": "equals 0, which implies that--", "start": 3175.41, "duration": 7.37}, {"text": "so this was the\nm-th partial sum--", "start": 3182.78, "duration": 4.33}, {"text": "which implies that the limit as\nm goes to infinity of s sub m", "start": 3187.11, "duration": 4.82}, {"text": "equals the limit as m goes to\ninfinity of this thing, which", "start": 3191.93, "duration": 4.29}, {"text": "is, if you like--", "start": 3196.22, "duration": 1.05}, {"text": "so that plus 1 there just\nmultiplies r to the m by r.", "start": 3200.25, "duration": 4.62}, {"text": "And using the algebraic\nfacts we proved", "start": 3204.87, "duration": 5.04}, {"text": "about limits is 1\nminus r time 0 over 1", "start": 3209.91, "duration": 2.7}, {"text": "minus r, which equals\n1 over 1 minus r.", "start": 3212.61, "duration": 3.93}, {"text": "So now you ask about the other.", "start": 3222.756, "duration": 3.534}, {"text": "What about r bigger than 1?", "start": 3226.29, "duration": 2.43}, {"text": "Well, when r equals\nminus 1, then we", "start": 3232.57, "duration": 2.73}, {"text": "get the second\nexample we looked at.", "start": 3235.3, "duration": 4.14}, {"text": "If we get r equals 1, then\nthat's just summing up 1,", "start": 3239.44, "duration": 4.89}, {"text": "and I'll leave it to you\nto check that that does not", "start": 3244.33, "duration": 3.24}, {"text": "converge, that the sequence of\npartial sums, if I just sum up", "start": 3247.57, "duration": 3.72}, {"text": "1 from n equals 0 to\nm, is equal 2n plus 1,", "start": 3251.29, "duration": 5.53}, {"text": "which does not converge.", "start": 3256.82, "duration": 1.0}, {"text": "And let me make just a\nkind of silly comment.", "start": 3272.67, "duration": 3.33}, {"text": "And maybe I didn't\nexplicitly make", "start": 3276.0, "duration": 2.16}, {"text": "this comment about sequences.", "start": 3278.16, "duration": 2.01}, {"text": "Maybe I forgot to\ndo that, as well.", "start": 3280.17, "duration": 1.81}, {"text": "So for a sequence, you could\nstart your sequence not", "start": 3281.98, "duration": 8.24}, {"text": "necessarily at the first entry.", "start": 3290.22, "duration": 1.95}, {"text": "Maybe you look at a, if you\nlike, new sequence where--", "start": 3292.17, "duration": 3.78}, {"text": "well, so we know from\nsequences that subsequences", "start": 3300.05, "duration": 4.24}, {"text": "of convergent\nsequences converge.", "start": 3304.29, "duration": 1.68}, {"text": "So if I, instead of looking at\nthe whole sequence, start at,", "start": 3305.97, "duration": 6.01}, {"text": "let's say, x100 and\nthen go x101, x102,", "start": 3311.98, "duration": 3.98}, {"text": "and that's the\nsequence I look at,", "start": 3315.96, "duration": 1.74}, {"text": "well, that's a subsequence\nof the original one, which,", "start": 3317.7, "duration": 2.79}, {"text": "if it converges, implies\nthat subsequence converges.", "start": 3320.49, "duration": 2.92}, {"text": "So all that is to say--", "start": 3323.41, "duration": 3.35}, {"text": "and for this simple way of\nobtaining this new sequence--", "start": 3326.76, "duration": 4.74}, {"text": "all of that is to say\nthat to understand", "start": 3331.5, "duration": 5.04}, {"text": "if a sequence\nconverges, I don't have", "start": 3336.54, "duration": 1.86}, {"text": "to consider what happens for\nthe first finitely many terms", "start": 3338.4, "duration": 5.58}, {"text": "in the sequence,\nmeaning a sequence x", "start": 3343.98, "duration": 5.33}, {"text": "sub n converges if and only if\na sequence starting now at say,", "start": 3349.31, "duration": 5.57}, {"text": "n equals 100-- and 101, 102,\n103 and so on-- converges.", "start": 3354.88, "duration": 5.49}, {"text": "And the same is true for series,\nthat a series converges if", "start": 3360.37, "duration": 6.73}, {"text": "and only if a series\nconverges, now,", "start": 3367.1, "duration": 4.68}, {"text": "starting at a different\npoint along the sequence.", "start": 3371.78, "duration": 2.95}, {"text": "So this is the\nfollowing theorem.", "start": 3374.73, "duration": 4.52}, {"text": "Let xn be a sequence, and let\ncapital M be a natural number.", "start": 3383.34, "duration": 15.29}, {"text": "Then n equals 1 to\ninfinity of x sub n.", "start": 3398.63, "duration": 8.01}, {"text": "This converges if and only\nif the sequence, now starting", "start": 3406.64, "duration": 5.25}, {"text": "at capital M,\nconverges, meaning when", "start": 3411.89, "duration": 6.29}, {"text": "I have to decide whether\na series converges or not,", "start": 3418.18, "duration": 3.03}, {"text": "it doesn't matter\nwhat's going on", "start": 3421.21, "duration": 2.46}, {"text": "for the first\nfinitely many terms.", "start": 3423.67, "duration": 3.01}, {"text": "What matters is\nwhat's going on as I", "start": 3426.68, "duration": 1.79}, {"text": "keep adding terms from\nfurther and further out", "start": 3428.47, "duration": 4.467}, {"text": "of this sequence.", "start": 3432.937, "duration": 0.708}, {"text": "And what's the proof?", "start": 3436.57, "duration": 0.93}, {"text": "The proof is just\nexpressing the partial sums", "start": 3437.5, "duration": 2.93}, {"text": "for this guy in terms of the\npartial sums for this guy.", "start": 3440.43, "duration": 3.48}, {"text": "So a partial sum satisfied\nfor all m, sum from n", "start": 3443.91, "duration": 18.46}, {"text": "equals 1 to m, and now\nx sub n as sum from n", "start": 3462.37, "duration": 9.67}, {"text": "equals capital M to m\nx sub n plus sum from n", "start": 3472.04, "duration": 6.63}, {"text": "equals 1 to capital\nM minus 1 x sub n.", "start": 3478.67, "duration": 6.35}, {"text": "So this is now just\na fixed number.", "start": 3485.02, "duration": 2.32}, {"text": "So this is a sequence of\npartial sums corresponding", "start": 3487.34, "duration": 4.94}, {"text": "to this series.", "start": 3492.28, "duration": 1.92}, {"text": "This is a sequence of\npartial sums corresponding", "start": 3494.2, "duration": 2.28}, {"text": "to this series.", "start": 3496.48, "duration": 0.99}, {"text": "And this is just a fixed number.", "start": 3497.47, "duration": 2.01}, {"text": "Therefore, if this\nconverges, then this side", "start": 3499.48, "duration": 3.78}, {"text": "converges to this plus this--", "start": 3503.26, "duration": 4.86}, {"text": "so maybe I'm going\na little quick.", "start": 3508.12, "duration": 2.25}, {"text": "But so if this\nconverges, then this", "start": 3510.37, "duration": 4.29}, {"text": "converges to this\nminus this number.", "start": 3514.66, "duration": 3.31}, {"text": "And if this converges, then\nthis sequence of partial sums", "start": 3517.97, "duration": 5.36}, {"text": "converges to this limit\nplus this fixed number.", "start": 3523.33, "duration": 5.67}, {"text": "And that's all I'm\ngoing to write.", "start": 3529.0, "duration": 1.65}, {"text": "Now, coming back to the\nusefulness of Cauchy sequences,", "start": 3538.72, "duration": 15.74}, {"text": "this is kind of\nwhere they really", "start": 3554.46, "duration": 5.0}, {"text": "become useful is in\nthe study of series.", "start": 3559.46, "duration": 2.91}, {"text": "Because again, it's\ndifficult to sum.", "start": 3565.58, "duration": 2.41}, {"text": "So when I keep talking\nsaying the word sum a series,", "start": 3567.99, "duration": 2.81}, {"text": "I'm talking about find\nthe limit of partial sums.", "start": 3570.8, "duration": 5.055}, {"text": "But because we have this\nequivalence between Cauchy", "start": 3578.45, "duration": 2.79}, {"text": "sequences and\nconvergent sequences,", "start": 3581.24, "duration": 3.63}, {"text": "to decide if a series\nis convergent or not,", "start": 3584.87, "duration": 3.96}, {"text": "we can just decide if, in some\nsense, it's Cauchy or not.", "start": 3588.83, "duration": 5.02}, {"text": "So let me make this definition.", "start": 3593.85, "duration": 5.39}, {"text": "We say that a series x sub\nn is Cauchy if the sequence", "start": 3599.24, "duration": 10.41}, {"text": "of partial sums--", "start": 3609.65, "duration": 1.17}, {"text": "again, I'm just going to\nput an m up top because this", "start": 3610.82, "duration": 8.66}, {"text": "may start at 0 or n equals 1\nor something-- so the sequence", "start": 3619.48, "duration": 4.11}, {"text": "of partial sums is Cauchy.", "start": 3623.59, "duration": 7.73}, {"text": "And so let me just restate\nwhat we proved for sequences", "start": 3636.84, "duration": 5.67}, {"text": "in terms of series.", "start": 3642.51, "duration": 1.62}, {"text": "So we proved that every\nCauchy sequence is convergent.", "start": 3644.13, "duration": 4.15}, {"text": "So a series is Cauchy means that\nthe sequence of partial sums", "start": 3648.28, "duration": 7.73}, {"text": "is Cauchy.", "start": 3656.01, "duration": 0.78}, {"text": "But we've proven that Cauchy\nsequences are convergent.", "start": 3656.79, "duration": 3.79}, {"text": "So if this is Cauchy, then\nit's convergent and vice versa.", "start": 3660.58, "duration": 4.32}, {"text": "So based on what we've\nproven already for sequences,", "start": 3664.9, "duration": 6.99}, {"text": "it follows that--", "start": 3671.89, "duration": 1.985}, {"text": "and this just\nfollows immediately", "start": 3673.875, "duration": 1.375}, {"text": "from what we've proven\nalready, so I'm not even", "start": 3675.25, "duration": 1.958}, {"text": "going to write a proof--", "start": 3677.208, "duration": 1.672}, {"text": "a series is Cauchy if and only\nif the series is convergent--", "start": 3678.88, "duration": 7.11}, {"text": "again, because both\nare defined in terms", "start": 3688.57, "duration": 2.04}, {"text": "of the sequence of partial\nsums associated to the series.", "start": 3690.61, "duration": 3.03}, {"text": "And we've already proven the\nequivalence between Cauchy", "start": 3693.64, "duration": 2.85}, {"text": "and convergence for sequences.", "start": 3696.49, "duration": 3.54}, {"text": "Now, let me write what\nit means to be Cauchy", "start": 3710.74, "duration": 3.0}, {"text": "in a slightly different way.", "start": 3713.74, "duration": 3.435}, {"text": "And it's the following.", "start": 3723.66, "duration": 1.29}, {"text": "So before, we had that\na sequence is Cauchy,", "start": 3731.86, "duration": 5.13}, {"text": "intuitively, if the\nelements of the sequence", "start": 3736.99, "duration": 3.63}, {"text": "are getting close to each other.", "start": 3740.62, "duration": 2.07}, {"text": "Now, for a series to be\nCauchy, the intuitive way", "start": 3742.69, "duration": 3.87}, {"text": "to think about it is\nthat the tail of the sum", "start": 3746.56, "duration": 3.9}, {"text": "is getting small, is\ngetting arbitrarily", "start": 3750.46, "duration": 3.72}, {"text": "small, the tail of the\nsum being if I add up", "start": 3754.18, "duration": 3.93}, {"text": "finitely many numbers\nfar enough out.", "start": 3758.11, "duration": 2.88}, {"text": "So a series is\nCauchy if and only", "start": 3760.99, "duration": 4.48}, {"text": "if all epsilon positive there\nexist to M, a natural number,", "start": 3765.47, "duration": 7.86}, {"text": "such that for all integers\nl bigger than m, which", "start": 3773.33, "duration": 7.35}, {"text": "is bigger than or equal to\ncapital M, the sum from n", "start": 3780.68, "duration": 7.92}, {"text": "equals n plus 1\nto l of x sub n--", "start": 3788.6, "duration": 4.71}, {"text": "so this is a sum involving\nterms that are pretty far out", "start": 3793.31, "duration": 4.53}, {"text": "there, at least all\nindexed by something bigger", "start": 3797.84, "duration": 4.44}, {"text": "than or equal to capital M--", "start": 3802.28, "duration": 1.65}, {"text": "is less than epsilon.", "start": 3803.93, "duration": 1.86}, {"text": "So a series is Cauchy\nif you're adding up", "start": 3805.79, "duration": 3.39}, {"text": "smaller and smaller pieces, not\nindividual pieces but actual", "start": 3809.18, "duration": 4.29}, {"text": "adding those up.", "start": 3813.47, "duration": 1.29}, {"text": "So I'll leave it to you to do--", "start": 3824.74, "duration": 5.16}, {"text": "they're both pretty\neasy-- but this direction,", "start": 3829.9, "duration": 3.25}, {"text": "I'll leave it to\nyou as an exercise.", "start": 3833.15, "duration": 1.85}, {"text": "And it'll follow\nimmediately from what", "start": 3835.0, "duration": 4.29}, {"text": "I'm going to write for,\nessentially, this direction.", "start": 3839.29, "duration": 3.57}, {"text": "So let's suppose-- and\nlet's make things concrete,", "start": 3846.45, "duration": 8.2}, {"text": "starting somewhere-- let's\nsuppose this sum is Cauchy.", "start": 3854.65, "duration": 2.535}, {"text": "And we want to prove now\nthat it has this property.", "start": 3861.08, "duration": 4.23}, {"text": "So let epsilon be positive.", "start": 3865.31, "duration": 5.3}, {"text": "We now want to produce\nsome capital number", "start": 3870.61, "duration": 1.75}, {"text": "M so that this holds.", "start": 3872.36, "duration": 2.01}, {"text": "So since the sequence of\npartial sums s sub m is Cauchy--", "start": 3883.73, "duration": 8.49}, {"text": "that's what it means for\nthe series to be Cauchy--", "start": 3892.22, "duration": 3.99}, {"text": "there exists a natural\nnumber, capital M,", "start": 3896.21, "duration": 4.14}, {"text": "such that for all M\nbigger than or equal to M0", "start": 3900.35, "duration": 9.75}, {"text": "and l bigger than or equal\nto M0, s sub m minus s", "start": 3910.1, "duration": 13.5}, {"text": "sub l is less than epsilon.", "start": 3923.6, "duration": 2.04}, {"text": "So we're actually going to\ntake capital M to be this M0.", "start": 3931.72, "duration": 4.47}, {"text": "Choose M to be M0.", "start": 3936.19, "duration": 8.65}, {"text": "Then, if l is\nbigger than m, which", "start": 3944.84, "duration": 6.77}, {"text": "is bigger than or equal to\nM, which is equal to M0,", "start": 3951.61, "duration": 6.12}, {"text": "if I look at this sum from n\nequals m plus 1 to l x sub n,", "start": 3957.73, "duration": 7.98}, {"text": "I can write--", "start": 3965.71, "duration": 2.568}, {"text": "so this is absolute value.", "start": 3968.278, "duration": 1.272}, {"text": "So in fact, let me remove\nthe absolute value so", "start": 3973.73, "duration": 2.09}, {"text": "that this becomes pretty clear.", "start": 3975.82, "duration": 1.71}, {"text": "I can write this sum\nas the l-th partial sum", "start": 3980.54, "duration": 4.29}, {"text": "minus the n-th partial sum.", "start": 3984.83, "duration": 3.42}, {"text": "Because the l-th partial sum\nsums from n equals 1 up to l.", "start": 3988.25, "duration": 4.32}, {"text": "The m-th partial sums\nfrom n equals 1 up to m.", "start": 3992.57, "duration": 3.27}, {"text": "So the sum containing only the\nterms between n plus 1 and l", "start": 3995.84, "duration": 4.05}, {"text": "is the difference of these guys.", "start": 3999.89, "duration": 1.395}, {"text": "So now I'll put it\non absolute values.", "start": 4003.91, "duration": 3.79}, {"text": "And this thing,\nbecause l and m are", "start": 4007.7, "duration": 2.46}, {"text": "bigger than or equal to capital\nM, which is equal to M0,", "start": 4010.16, "duration": 3.09}, {"text": "and because I have\nthis inequality,", "start": 4013.25, "duration": 2.4}, {"text": "this is less than epsilon.", "start": 4015.65, "duration": 1.83}, {"text": "And the converse\ndirection, again, it", "start": 4017.48, "duration": 1.74}, {"text": "follows immediately,\nessentially,", "start": 4019.22, "duration": 1.74}, {"text": "from this equality here.", "start": 4020.96, "duration": 3.54}, {"text": "So to check whether\na series converges,", "start": 4028.57, "duration": 2.97}, {"text": "I don't have to somehow come up\nwith a limit for this series,", "start": 4031.54, "duration": 6.69}, {"text": "a sum for this series.", "start": 4038.23, "duration": 3.21}, {"text": "I can just prove\nthat the tail can", "start": 4041.44, "duration": 3.72}, {"text": "be made arbitrarily\nsmall, as long", "start": 4045.16, "duration": 1.95}, {"text": "as I go far enough\nout in the series.", "start": 4047.11, "duration": 3.105}, {"text": "And from this, we get a pretty\nsimple elementary property,", "start": 4065.97, "duration": 7.98}, {"text": "so a theorem.", "start": 4073.95, "duration": 0.78}, {"text": "If a series converges, then\nthis implies that the limit as n", "start": 4080.19, "duration": 14.98}, {"text": "goes to infinity of x sub\nn of the sequence you used", "start": 4095.17, "duration": 5.88}, {"text": "to obtain the series equals 0.", "start": 4101.05, "duration": 3.36}, {"text": "So this should fall in line\nwith a series being convergent", "start": 4104.41, "duration": 6.9}, {"text": "if and only if it satisfies this\nproperty here, which is somehow", "start": 4111.31, "duration": 3.87}, {"text": "saying the tail of the sum is\ngetting smaller and smaller,", "start": 4115.18, "duration": 4.719}, {"text": "which means you can't be adding\nup big things as you go on", "start": 4119.899, "duration": 5.75}, {"text": "out in the series.", "start": 4125.649, "duration": 1.516}, {"text": "So proof.", "start": 4133.399, "duration": 0.541}, {"text": "So we'll show this by a\nsimple epsilon M definition.", "start": 4139.02, "duration": 10.549}, {"text": "So suppose xn converges.", "start": 4149.569, "duration": 6.96}, {"text": "Then xn the series is Cauchy.", "start": 4159.56, "duration": 5.945}, {"text": "And now I'm going to verify this\nusing the epsilon M definition.", "start": 4168.87, "duration": 4.59}, {"text": "Let epsilon be positive.", "start": 4176.76, "duration": 1.44}, {"text": "Since xn is Cauchy,\nthis implies that there", "start": 4180.76, "duration": 6.36}, {"text": "exists a natural number M0\nsuch that for all l bigger", "start": 4187.12, "duration": 7.38}, {"text": "than or equal to m\nbigger than or equal M0,", "start": 4194.5, "duration": 4.11}, {"text": "I have that condition there,\nsum from n equals m plus 1", "start": 4198.61, "duration": 9.4}, {"text": "to l x sub n is\nless than epsilon.", "start": 4208.01, "duration": 3.66}, {"text": "Choose M to be M0 plus 1.", "start": 4220.74, "duration": 5.06}, {"text": "So why M0 plus 1\nbut not exactly M0?", "start": 4229.16, "duration": 2.76}, {"text": "Just because, basically,\nwhat I'm going to do", "start": 4231.92, "duration": 2.76}, {"text": "is I'm going to take l\nto be equal to m plus 1.", "start": 4234.68, "duration": 2.85}, {"text": "And the index gets shifted by 1.", "start": 4237.53, "duration": 2.91}, {"text": "Then if m is bigger\nthan or equal to M,", "start": 4243.32, "duration": 5.52}, {"text": "I get that the absolute\nvalue of x sub m--", "start": 4248.84, "duration": 3.3}, {"text": "maybe instead of\nsaying limit as n", "start": 4255.38, "duration": 3.57}, {"text": "goes to infinity, I'll write\nlimit as m goes to infinity,", "start": 4258.95, "duration": 2.68}, {"text": "it's just a change in\nthe dummy variable-- this", "start": 4261.63, "duration": 2.21}, {"text": "is equal to the sum from\nn equals m to m x sub n.", "start": 4263.84, "duration": 11.88}, {"text": "And so I've shifted this.", "start": 4275.72, "duration": 2.11}, {"text": "So now little m is bigger than\nor equal to capital M0 plus 1.", "start": 4277.83, "duration": 5.6}, {"text": "So you could write this as,\nif you like, m minus 1 plus 1.", "start": 4283.43, "duration": 4.17}, {"text": "So little m minus 1 is\nbigger than or equal to M0.", "start": 4287.6, "duration": 4.56}, {"text": "So by this inequality,\nthis is less than epsilon.", "start": 4292.16, "duration": 2.64}, {"text": "So we see that if a series\nconverges the terms,", "start": 4312.96, "duration": 5.19}, {"text": "the individual terms, x\nsub n must converge to 0.", "start": 4318.15, "duration": 6.03}, {"text": "So there's another reason why\nthis series minus 1 to the n", "start": 4324.18, "duration": 4.5}, {"text": "does not converge.", "start": 4328.68, "duration": 1.98}, {"text": "Because those terms\ndo not converge.", "start": 4330.66, "duration": 1.53}, {"text": "And this also tells us that\nfor this geometric series, when", "start": 4335.64, "duration": 4.08}, {"text": "r is greater than or equal\nto 1 in absolute value,", "start": 4339.72, "duration": 3.802}, {"text": "the series does not converge.", "start": 4343.522, "duration": 1.208}, {"text": "It does not converge.", "start": 4354.25, "duration": 2.64}, {"text": "And the proof is--", "start": 4356.89, "duration": 0.78}, {"text": "and we proved this, in fact,\nI think, a few lectures ago,", "start": 4361.24, "duration": 6.71}, {"text": "as well, that if the absolute\nvalue of r is bigger than 1,", "start": 4367.95, "duration": 5.79}, {"text": "then the limit as n goes\nto infinity of r to the n,", "start": 4373.74, "duration": 5.1}, {"text": "this limit does not exist.", "start": 4378.84, "duration": 3.56}, {"text": "We showed it's, in\nfact, unbounded.", "start": 4385.55, "duration": 3.39}, {"text": "r to the n is an\nunbounded sequence.", "start": 4388.94, "duration": 6.23}, {"text": "So it does not convert.", "start": 4395.17, "duration": 6.71}, {"text": "So I'm using that\ntheorem over there", "start": 4401.88, "duration": 3.21}, {"text": "in a little bit roundabout way.", "start": 4405.09, "duration": 1.35}, {"text": "Let me restate this\ntheorem over here.", "start": 4417.89, "duration": 1.68}, {"text": "This theorem says if\nthe series converges,", "start": 4419.57, "duration": 6.55}, {"text": "then this limit equals 0.", "start": 4426.12, "duration": 4.49}, {"text": "Now, this statement is logically\nequivalent to the negation", "start": 4430.61, "duration": 6.15}, {"text": "of the converse, or there's\nan actual word for that,", "start": 4436.76, "duration": 5.76}, {"text": "but I can't remember--", "start": 4442.52, "duration": 1.95}, {"text": "namely that the negation of this\nimplies the negation of this.", "start": 4444.47, "duration": 8.43}, {"text": "So a logically equivalent way\nto rewrite that statement over", "start": 4452.9, "duration": 6.06}, {"text": "there is that if this\nlimit does not equal to 0--", "start": 4458.96, "duration": 12.94}, {"text": "so if it doesn't exist at\nall, that's also fine--", "start": 4471.9, "duration": 4.68}, {"text": "this implies that\ndoes not converge.", "start": 4476.58, "duration": 6.57}, {"text": "So this restatement of\nthe theorem over there", "start": 4483.15, "duration": 4.92}, {"text": "is really what I used here.", "start": 4488.07, "duration": 3.84}, {"text": "All right.", "start": 4496.35, "duration": 0.5}, {"text": "And I think I'll stop there.", "start": 4496.85, "duration": 2.59}, {"text": "Next time, we'll see\nthat this theorem here", "start": 4499.44, "duration": 4.7}, {"text": "is a one-way street.", "start": 4504.14, "duration": 1.39}, {"text": "And I think you covered\nthis example in, probably,", "start": 4505.53, "duration": 2.93}, {"text": "calculus, namely that\none-way street in the sense", "start": 4508.46, "duration": 3.72}, {"text": "that if x then converges,\nthen this limit is 0.", "start": 4512.18, "duration": 3.63}, {"text": "But the converse does not hold.", "start": 4515.81, "duration": 2.22}, {"text": "Namely, it is not true\nthat if this limit", "start": 4518.03, "duration": 3.93}, {"text": "is 0, then this converges.", "start": 4521.96, "duration": 3.48}, {"text": "And we'll see the famed\nharmonic series next time.", "start": 4525.44, "duration": 6.23}]

transcripts/0lPfTMmyzvk.json

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+[{"text": "MARKUS KLUTE: Welcome back\nto 8.20, special relativity.", "start": 12.98, "duration": 2.58}, {"text": "Let's start here\nwith a short summary.", "start": 15.56, "duration": 2.86}, {"text": "We have seen through\nexperimental measurements", "start": 18.42, "duration": 2.09}, {"text": "that there is no ether, that\nelectromagnetic waves travels", "start": 20.51, "duration": 4.11}, {"text": "through vacuum.", "start": 24.62, "duration": 2.31}, {"text": "We have discussed the concept of\nthe relativity of simultaneity,", "start": 26.93, "duration": 5.25}, {"text": "meaning that two events\nmight occur simultaneous", "start": 32.18, "duration": 4.14}, {"text": "to one reference-- in\none reference frame,", "start": 36.32, "duration": 1.77}, {"text": "to one observer, while\nthey're not to another.", "start": 38.09, "duration": 4.32}, {"text": "In the last two videos,\nwe looked at clocks.", "start": 42.41, "duration": 3.06}, {"text": "And we've seen that\nmoving clocks run slow.", "start": 45.47, "duration": 2.67}, {"text": "We've also seen that moving\nobjects appear smaller.", "start": 48.14, "duration": 3.84}, {"text": "They're lengths contract.", "start": 51.98, "duration": 2.42}, {"text": "We found that the\ntime of a moving clock", "start": 54.4, "duration": 5.94}, {"text": "is related to the time\nin the clock at rest", "start": 60.34, "duration": 3.3}, {"text": "with a gamma factor\nbecause it's time dilation.", "start": 63.64, "duration": 3.21}, {"text": "And, for the length, we\nhave seen that there is a 1", "start": 66.85, "duration": 2.67}, {"text": "over gamma dependency,\nlength contraction.", "start": 69.52, "duration": 3.78}, {"text": "The entire discussion was\nbased on Einstein's postulates.", "start": 73.3, "duration": 3.81}, {"text": "We simply used\nEinstein's postulates.", "start": 77.11, "duration": 2.46}, {"text": "And then we looked at\nexperiments of clocks.", "start": 79.57, "duration": 3.3}, {"text": "Now, you might argue that\nthe setup of the clock", "start": 82.87, "duration": 2.07}, {"text": "is actually what's\ntricking us here,", "start": 84.94, "duration": 1.86}, {"text": "but I can tell you\nthat is not the case.", "start": 86.8, "duration": 1.9}, {"text": "As you have seen for\nthe muon, the muon", "start": 88.7, "duration": 1.625}, {"text": "doesn't know about\noptical clocks.", "start": 90.325, "duration": 1.785}, {"text": "It just decays based\non its own properties.", "start": 92.11, "duration": 4.44}, {"text": "I think it's fair to say that\nPoincar\u00e9 and Lorentz came", "start": 96.55, "duration": 3.18}, {"text": "to similar conclusions about\nthe same time as Einstein did.", "start": 99.73, "duration": 4.85}, {"text": "Delta t at rest and delta L at\nrest, the time and the length,", "start": 104.58, "duration": 4.08}, {"text": "are also sometimes called\nthe proper time and length.", "start": 108.66, "duration": 3.72}, {"text": "In German-- and I actually\nprefer this a bit--", "start": 112.38, "duration": 2.73}, {"text": "we use the word eigen,\nwhich means own.", "start": 115.11, "duration": 2.61}, {"text": "So it's basically the time,\nthe own time of the object,", "start": 117.72, "duration": 3.39}, {"text": "the object being addressed.", "start": 121.11, "duration": 3.57}, {"text": "So we can now ask, [INAUDIBLE]\nseen time is suspect.", "start": 124.68, "duration": 4.92}, {"text": "What is not suspect?", "start": 129.6, "duration": 1.17}, {"text": "What are the observables\nwhich are invariant?", "start": 130.77, "duration": 3.6}, {"text": "And, by this, I mean\nthe observables,", "start": 134.37, "duration": 2.048}, {"text": "when we have two\ndifferent reference frames", "start": 136.418, "duration": 1.792}, {"text": "and we have a conversation,\nwe do actually", "start": 138.21, "duration": 2.19}, {"text": "agree in a conversation\nabout an observation we have.", "start": 140.4, "duration": 7.074}, {"text": "We have seen we\ncannot agree on time,", "start": 147.474, "duration": 2.396}, {"text": "and we cannot agree on the\nlength in the direction", "start": 149.87, "duration": 2.61}, {"text": "in which we are moving.", "start": 152.48, "duration": 2.22}, {"text": "So can I ask, for\nexample, what happens", "start": 154.7, "duration": 1.95}, {"text": "to the width or the height?", "start": 156.65, "duration": 3.27}, {"text": "If I put a train on a train\ntrack and it's fast moving,", "start": 159.92, "duration": 3.57}, {"text": "is that contracted or even\nexpanded or changing at all?", "start": 163.49, "duration": 4.0}, {"text": "The answer is no.", "start": 167.49, "duration": 1.31}, {"text": "Similarly, if I put a\ntrain track on a track", "start": 168.8, "duration": 3.06}, {"text": "and I go very fast\ninto a tunnel,", "start": 171.86, "duration": 2.91}, {"text": "does the height of\nthe tunnel change?", "start": 174.77, "duration": 2.53}, {"text": "Also here the answer is no.", "start": 177.3, "duration": 2.37}, {"text": "And we can verify this\nlater quantitatively.", "start": 179.67, "duration": 6.11}, {"text": "In summary, transverse\ndimensions are not affected.", "start": 185.78, "duration": 3.0}, {"text": "They are not suspect.", "start": 188.78, "duration": 1.38}, {"text": "We can agree in a\nconversation of two people", "start": 190.16, "duration": 2.7}, {"text": "in different reference\nframes about the height", "start": 192.86, "duration": 2.76}, {"text": "and the width of a train.", "start": 195.62, "duration": 2.01}, {"text": "That's good.", "start": 197.63, "duration": 0.79}, {"text": "But what else is invariant?", "start": 198.42, "duration": 3.04}, {"text": "So here I want you to\nconsider the time and distance", "start": 201.46, "duration": 2.49}, {"text": "between two events or\nmaybe even three events", "start": 203.95, "duration": 2.88}, {"text": "observed from different\nreference frames.", "start": 206.83, "duration": 2.4}, {"text": "And we introduce or reintroduce\nour characters Alice and Bob", "start": 209.23, "duration": 3.51}, {"text": "and add Carol to this.", "start": 212.74, "duration": 1.21}, {"text": "So we're going to have three\nreference frames of three", "start": 213.95, "duration": 3.23}, {"text": "observers in this discussion.", "start": 217.18, "duration": 3.69}, {"text": "So I want you to look\nat this one here.", "start": 220.87, "duration": 1.72}, {"text": "So assume that Bob\nhas a clock, and it's", "start": 222.59, "duration": 3.5}, {"text": "moving with a velocity v. And\nAlice is observing Bob's clock.", "start": 226.09, "duration": 5.66}, {"text": "We have done this before.", "start": 231.75, "duration": 1.72}, {"text": "Now, we want to also\nadd Carol to this.", "start": 233.47, "duration": 2.28}, {"text": "And Carol is moving with\nthree times the velocity", "start": 235.75, "duration": 2.85}, {"text": "and is also observing\nBob's clock.", "start": 238.6, "duration": 3.15}, {"text": "What I want you to do is\nlook at this property here.", "start": 241.75, "duration": 7.22}, {"text": "So we have seen that\nthe height is invariant.", "start": 248.97, "duration": 3.59}, {"text": "So let's look at what\nhappens if I calculate", "start": 252.56, "duration": 2.52}, {"text": "2 times the height squared, and\nI use x and t, time and space,", "start": 255.08, "duration": 5.939}, {"text": "in order to express\nthe height, all right?", "start": 261.019, "duration": 3.151}, {"text": "Again, this is an opportunity to\nstop the clock, stop the video,", "start": 264.17, "duration": 5.31}, {"text": "and work this out\non a piece of paper.", "start": 269.48, "duration": 4.35}, {"text": "So it turns out\nit's not that hard.", "start": 273.83, "duration": 2.97}, {"text": "We basically find that 4\ntimes the height squared", "start": 276.8, "duration": 2.61}, {"text": "is equal to--", "start": 279.41, "duration": 1.315}, {"text": "maybe it is hard--", "start": 280.725, "duration": 2.185}, {"text": "c squared times t\nsquared minus x squared.", "start": 282.91, "duration": 2.97}, {"text": "And, since the height\nis an invariant,", "start": 285.88, "duration": 2.94}, {"text": "this property, c squared,\nthe speed of light squared,", "start": 288.82, "duration": 3.63}, {"text": "times the time squared minus\nx squared, is invariant.", "start": 292.45, "duration": 3.87}, {"text": "So we can think about them\nas delta t and delta x.", "start": 296.32, "duration": 4.11}, {"text": "When we look at the difference\nin time and the difference", "start": 300.43, "duration": 3.03}, {"text": "in space between two events--", "start": 303.46, "duration": 1.59}, {"text": "Professor Klute\nentered the class.", "start": 308.09, "duration": 2.01}, {"text": "And, at the other\nend of the class,", "start": 310.1, "duration": 1.47}, {"text": "Professor Klute exploded.", "start": 311.57, "duration": 2.01}, {"text": "If I do the delta t and the\ndelta x between the two--", "start": 313.58, "duration": 3.3}, {"text": "we square them and\nsubtract them--", "start": 316.88, "duration": 2.4}, {"text": "that is an observation\nwe can all agree on.", "start": 319.28, "duration": 2.4}, {"text": "Whether or not you're\nstationary in the classroom", "start": 321.68, "duration": 2.58}, {"text": "or you're passing by really\nquickly with your spacecraft,", "start": 324.26, "duration": 3.18}, {"text": "that observation is\nsomething we can agree on.", "start": 327.44, "duration": 2.8}, {"text": "And it's invariant.", "start": 330.24, "duration": 1.1}, {"text": "This property is called\nthe invariant interval.", "start": 331.34, "duration": 4.25}]

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+[{"text": "[SQUEAKING]\n[RUSTLING] [CLICKING]", "start": 0.0, "duration": 6.279}, {"text": "NORVIN RICHARDS:\nSigned languages--", "start": 11.109, "duration": 1.971}, {"text": "there are a bunch\nof signed languages.", "start": 13.08, "duration": 3.48}, {"text": "I've listed three of them\nhere, but there are many.", "start": 16.56, "duration": 3.15}, {"text": "And maybe the first\nthing to say about them,", "start": 19.71, "duration": 2.7}, {"text": "I can remember a\ntime when I believed,", "start": 22.41, "duration": 4.44}, {"text": "as a child, that signed\nlanguages were basically", "start": 26.85, "duration": 2.55}, {"text": "just codes--", "start": 29.4, "duration": 1.44}, {"text": "coded versions of\nspoken languages.", "start": 30.84, "duration": 3.18}, {"text": "When I was a kid,\nyou were sometimes", "start": 34.02, "duration": 1.5}, {"text": "taught ASL signs for things\nevery so often in class,", "start": 35.52, "duration": 4.902}, {"text": "sort of the way\nyou would be taught", "start": 40.422, "duration": 1.458}, {"text": "the occasional Spanish\nword in class or whatever.", "start": 41.88, "duration": 2.428}, {"text": "It's like, here's the word\nin a foreign language.", "start": 44.308, "duration": 2.042}, {"text": "Let's all learn this word.", "start": 46.35, "duration": 2.97}, {"text": "Unlike Spanish, the impression\nI was given by my teachers-- who", "start": 49.32, "duration": 2.675}, {"text": "may actually have\nbelieved this--", "start": 51.995, "duration": 1.375}, {"text": "was that the way you spoke\nASL was to speak English,", "start": 53.37, "duration": 3.12}, {"text": "but to use your hands.", "start": 56.49, "duration": 1.23}, {"text": "So like every English word\nhad an ASL translation.", "start": 57.72, "duration": 4.11}, {"text": "And there is\nsomething like that.", "start": 61.83, "duration": 1.57}, {"text": "It's called Signed\nExact English.", "start": 63.4, "duration": 2.33}, {"text": "But it is not the standard\nlanguage used by the deaf.", "start": 65.73, "duration": 4.38}, {"text": "The deaf use something\ncalled American Sign Language", "start": 70.11, "duration": 2.4}, {"text": "in America.", "start": 72.51, "duration": 1.116}, {"text": "Another way to\nmake this point may", "start": 77.28, "duration": 1.77}, {"text": "be that signed\nlanguages are not just", "start": 79.05, "duration": 2.1}, {"text": "coded versions of the spoken\nlanguages that are around them,", "start": 81.15, "duration": 3.39}, {"text": "is that American-- to point out\nthat American Sign Language is", "start": 84.54, "duration": 5.07}, {"text": "fairly closely related to French\nSign Language, which I won't", "start": 89.61, "duration": 4.14}, {"text": "try to pronounce in French\nbecause I don't speak French,", "start": 93.75, "duration": 3.06}, {"text": "for historical reasons.", "start": 96.81, "duration": 2.23}, {"text": "The first schools for\nthe deaf in America", "start": 99.04, "duration": 2.78}, {"text": "were established by\npeople from France", "start": 101.82, "duration": 1.937}, {"text": "who had established schools\nfor the deaf in France", "start": 103.757, "duration": 2.083}, {"text": "and began establishing\nthem here.", "start": 105.84, "duration": 1.44}, {"text": "So American Sign Language is\na descendant of French Sign", "start": 107.28, "duration": 3.51}, {"text": "Language, and it is unrelated\nto British Sign Language", "start": 110.79, "duration": 2.46}, {"text": "and quite different from it.", "start": 113.25, "duration": 1.32}, {"text": "So go ahead and\nmake all the jokes", "start": 114.57, "duration": 2.615}, {"text": "you want about American\nEnglish and British English", "start": 117.185, "duration": 2.125}, {"text": "being different, but they're\nmore similar to each other", "start": 119.31, "duration": 2.292}, {"text": "than either is to French.", "start": 121.602, "duration": 1.488}, {"text": "But American Sign Language is\nmore similar to French Sign", "start": 123.09, "duration": 3.69}, {"text": "Language than it is to\nBritish Sign Language", "start": 126.78, "duration": 2.46}, {"text": "because American Sign\nLanguage is not English.", "start": 129.24, "duration": 2.25}, {"text": "It's another\nlanguage, one which is", "start": 131.49, "duration": 2.4}, {"text": "spoken with your body,\nespecially your hands.", "start": 133.89, "duration": 2.385}, {"text": "Yes, I just said that.", "start": 139.473, "duration": 0.917}, {"text": "Thank you.", "start": 140.39, "duration": 2.382}, {"text": "Another way to make\nthe same point,", "start": 142.772, "duration": 1.458}, {"text": "there are big\ngrammatical differences", "start": 144.23, "duration": 1.59}, {"text": "between ASL and English, some\nof which we'll be exploring.", "start": 145.82, "duration": 3.18}, {"text": "Here's one.", "start": 149.0, "duration": 0.5}, {"text": "In English has\novert wh-movement.", "start": 149.5, "duration": 2.51}, {"text": "Remember wh-movement?", "start": 152.01, "duration": 2.67}, {"text": "So in \"Who did John see?\"", "start": 154.68, "duration": 2.03}, {"text": "Lots of other languages,\nlike Mandarin, don't.", "start": 156.71, "duration": 2.82}, {"text": "And in this regard, ASL\nis more like Mandarin", "start": 159.53, "duration": 2.97}, {"text": "than it is like English.", "start": 162.5, "duration": 1.44}, {"text": "It's actually a blend.", "start": 163.94, "duration": 1.35}, {"text": "You can do either one.", "start": 165.29, "duration": 1.44}, {"text": "But there's a very natural\nway to ask wh-questions", "start": 166.73, "duration": 2.91}, {"text": "in ASL, which looks\nsomething like this.", "start": 169.64, "duration": 4.72}, {"text": "Here's a guy who\nis about to say,", "start": 174.36, "duration": 1.73}, {"text": "I think, \"Who did John see?\"", "start": 176.09, "duration": 3.94}, {"text": "\"John\"- \"saw\"- \"who?\"", "start": 180.03, "duration": 1.56}, {"text": "Yeah, so I'll get him\nto sign that again.", "start": 181.59, "duration": 2.55}, {"text": "So \"John saw who?\"", "start": 184.14, "duration": 2.85}, {"text": "And \"who\" is signed like this.", "start": 186.99, "duration": 1.68}, {"text": "That's the ASL for \"who.\"", "start": 188.67, "duration": 2.4}, {"text": "There's another thing he's\ndoing, which we'll talk about.", "start": 191.07, "duration": 2.85}, {"text": "Part of signing\na question in ASL", "start": 193.92, "duration": 4.063}, {"text": "is not just what you\ndo with your hands,", "start": 197.983, "duration": 1.667}, {"text": "but what you do with your face.", "start": 199.65, "duration": 1.38}, {"text": "You're required to\nlook puzzled as you", "start": 201.03, "duration": 3.12}, {"text": "ask these particular\nkinds of questions--", "start": 204.15, "duration": 1.93}, {"text": "and so to tilt your head\nand furrow your brow.", "start": 206.08, "duration": 2.45}, {"text": "And there's some\nvery careful work", "start": 208.53, "duration": 2.79}, {"text": "on where, exactly, you're\nrequired to tilt your head", "start": 211.32, "duration": 2.515}, {"text": "and furrow your brow.", "start": 213.835, "duration": 0.875}, {"text": "It turns out to be\nvery interesting.", "start": 214.71, "duration": 1.63}, {"text": "It isn't just you do that\nfor the whole question.", "start": 216.34, "duration": 2.06}, {"text": "You do that for certain\nparts of the question.", "start": 218.4, "duration": 1.917}, {"text": "And linguists who work\non signed languages", "start": 220.317, "duration": 2.733}, {"text": "do work on what's going on.", "start": 223.05, "duration": 1.8}, {"text": "I'll put a link to this.", "start": 224.85, "duration": 1.58}, {"text": "This is a corpus of American\nSign Language utterances", "start": 226.43, "duration": 3.94}, {"text": "by the folks over\nthere at BU who", "start": 230.37, "duration": 3.39}, {"text": "have a center for studying ASL.", "start": 233.76, "duration": 3.108}, {"text": "There's a lot of really\ninteresting data in here, which", "start": 236.868, "duration": 2.292}, {"text": "is tagged, as you can see.", "start": 239.16, "duration": 1.53}, {"text": "Anyway, I'll put a link\nto this on our website.", "start": 240.69, "duration": 3.01}, {"text": "So this is Carol Neidle,\nwho's done a lot of really", "start": 243.7, "duration": 2.53}, {"text": "interesting work on ASL.", "start": 246.23, "duration": 1.0}, {"text": "Back into full screen mode.", "start": 250.285, "duration": 1.125}, {"text": "I'm sorry, I'm going\nto do a lot of this", "start": 251.41, "duration": 1.05}, {"text": "because we're going to be going\nback and forth between videos", "start": 252.46, "duration": 2.542}, {"text": "and my slides.", "start": 255.002, "duration": 1.418}, {"text": "And I am low tech.", "start": 256.42, "duration": 1.151}, {"text": "If I were higher tech, I\nwould have figured out a way", "start": 257.571, "duration": 2.208}, {"text": "to incorporate the\nvideos into the slides,", "start": 259.779, "duration": 1.771}, {"text": "but that's why this is the\nlinguistics department and not", "start": 261.55, "duration": 3.07}, {"text": "some other department.", "start": 264.62, "duration": 2.19}, {"text": "OK, so ASL is not English.", "start": 266.81, "duration": 1.953}, {"text": "It's not English because it's\nnot all that closely related", "start": 268.763, "duration": 2.417}, {"text": "to British sign language,\nand it's also not English", "start": 271.18, "duration": 2.28}, {"text": "because, well, it has\nwh- [INAUDIBLE] too,", "start": 273.46, "duration": 1.845}, {"text": "like, English standard way\nto ask \"Who did John see?,\"", "start": 275.305, "duration": 2.505}, {"text": "the word order is,\n\"John saw who?\"", "start": 277.81, "duration": 1.58}, {"text": "That's not to say that\nsign languages aren't", "start": 282.01, "duration": 1.86}, {"text": "in some kind of contact\nwith spoken languages.", "start": 283.87, "duration": 1.917}, {"text": "So typically, if you're a deaf\nperson growing up in America,", "start": 285.787, "duration": 7.413}, {"text": "you have some kind of\nrelationship with ASL.", "start": 293.2, "duration": 2.67}, {"text": "What kind of relationship\ndepends on the circumstances.", "start": 295.87, "duration": 3.19}, {"text": "So it's not at all\nuncommon for deaf children", "start": 299.06, "duration": 2.39}, {"text": "to be the deaf children\nof hearing parents,", "start": 301.45, "duration": 1.95}, {"text": "and then their parents\nhave to do some hustling", "start": 303.4, "duration": 2.588}, {"text": "and be careful to make sure that\ntheir children have a chance", "start": 305.988, "duration": 2.542}, {"text": "to learn ASL.", "start": 308.53, "duration": 2.4}, {"text": "Some children of hearing\nparents will try to learn ASL", "start": 310.93, "duration": 2.76}, {"text": "themselves and raise\ntheir children in ASL.", "start": 313.69, "duration": 2.94}, {"text": "But, of course that's quite\ndifficult, to learn quickly", "start": 316.63, "duration": 3.78}, {"text": "a language like ASL.", "start": 320.41, "duration": 1.5}, {"text": "I say \"quickly\" because\nif you didn't know ASL", "start": 321.91, "duration": 2.893}, {"text": "before you realized that you\nhad a deaf child, well, then,", "start": 324.803, "duration": 2.417}, {"text": "you need to hurry up and\nlearn it fairly fast.", "start": 327.22, "duration": 2.37}, {"text": "And that's a difficult\nposition for parents to be in.", "start": 329.59, "duration": 3.1}, {"text": "So there are some barriers with\nrespect to how much resources", "start": 332.69, "duration": 4.22}, {"text": "these people have,\nwhether they can", "start": 336.91, "duration": 2.64}, {"text": "do that in time for their kids\nto be exposed to ASL the way", "start": 339.55, "duration": 3.903}, {"text": "you need to be exposed\nto your first language.", "start": 343.453, "duration": 1.917}, {"text": "They're the deaf kids\nwho-- and then, there", "start": 345.37, "duration": 1.8}, {"text": "are deaf kids who are lucky\nenough to be around native ASL", "start": 347.17, "duration": 2.88}, {"text": "signers from a very early age.", "start": 350.05, "duration": 1.98}, {"text": "Now, the upshot of all\nthis is that if you're deaf", "start": 352.03, "duration": 3.338}, {"text": "and you're growing up\nin the United States,", "start": 355.368, "duration": 1.792}, {"text": "you probably have some\nkind of relation to ASL.", "start": 357.16, "duration": 2.01}, {"text": "Maybe you become\na fluent speaker.", "start": 359.17, "duration": 1.44}, {"text": "That's one hope.", "start": 360.61, "duration": 4.165}, {"text": "But you also have some kind\nof relationship with English.", "start": 364.775, "duration": 2.375}, {"text": "You're surrounded by people\nwho are communicating", "start": 367.15, "duration": 2.7}, {"text": "with each other in English.", "start": 369.85, "duration": 1.17}, {"text": "And so there are what you\ncould think of as borrowings", "start": 371.02, "duration": 2.7}, {"text": "between gestures of\nhearing people around you", "start": 373.72, "duration": 3.93}, {"text": "and the gestures that\nare used in the sign.", "start": 377.65, "duration": 5.22}, {"text": "Maybe one of the\nclearest examples", "start": 382.87, "duration": 1.47}, {"text": "of this, the pronoun for \"I\" in\nAmerican Sign Language is this.", "start": 384.34, "duration": 3.3}, {"text": "You point at your own chest.", "start": 387.64, "duration": 2.25}, {"text": "The pronoun for \"I\" in\nJapanese Sign Language is this.", "start": 389.89, "duration": 3.03}, {"text": "You point at your own nose.", "start": 392.92, "duration": 1.86}, {"text": "That's borrowing\nfrom the standard way", "start": 394.78, "duration": 3.96}, {"text": "to point to yourself\nin these places.", "start": 398.74, "duration": 2.2}, {"text": "So in Japan, and a\nlot of Asia, I think,", "start": 400.94, "duration": 2.39}, {"text": "the way to point to yourself\nis to point at your own nose,", "start": 403.33, "duration": 4.44}, {"text": "whereas in America, the standard\nway to point to yourself", "start": 407.77, "duration": 3.0}, {"text": "is to point at your chest.", "start": 410.77, "duration": 1.083}, {"text": "So we could think of\nthis as borrowing,", "start": 411.853, "duration": 1.625}, {"text": "if we wanted to,\nsome kind of contact", "start": 413.478, "duration": 1.582}, {"text": "between the spoken language\nand the sign language.", "start": 415.06, "duration": 3.495}, {"text": "From very early on--", "start": 422.61, "duration": 1.2}, {"text": "one of the first\ndays, I think-- we", "start": 423.81, "duration": 1.548}, {"text": "talked about Saussure and\nthe idea of the arbitrariness", "start": 425.358, "duration": 2.292}, {"text": "of the sign, the observation\nthat the fact that this", "start": 427.65, "duration": 3.12}, {"text": "is called a \"table\"\nis an arbitrary fact.", "start": 430.77, "duration": 3.7}, {"text": "There's nothing\nabout it that demands", "start": 434.47, "duration": 2.51}, {"text": "that it be called a table.", "start": 436.98, "duration": 1.163}, {"text": "It could have been\ncalled \"chair\",", "start": 438.143, "duration": 1.417}, {"text": "and the fact that it's called\na table is an accident.", "start": 439.56, "duration": 2.67}, {"text": "The fact that we call it a table\nin English but that in another", "start": 442.23, "duration": 2.79}, {"text": "language it could be called\na \"mesa,\" or a [NON-ENGLISH],,", "start": 445.02, "duration": 2.55}, {"text": "or a bunch of other things.", "start": 447.57, "duration": 3.03}, {"text": "Yeah, languages get to\narbitrarily decide what", "start": 450.6, "duration": 3.12}, {"text": "they're going to call things.", "start": 453.72, "duration": 1.71}, {"text": "Even in spoken languages--", "start": 455.43, "duration": 1.29}, {"text": "I think we said this before--", "start": 456.72, "duration": 1.54}, {"text": "there are places where the\nway a word is pronounced", "start": 458.26, "duration": 7.43}, {"text": "has some kind of connection\nwith what it refers to.", "start": 465.69, "duration": 3.03}, {"text": "The classic example\nof this is names", "start": 468.72, "duration": 1.74}, {"text": "for birds, which are\nnot always, but often", "start": 470.46, "duration": 3.03}, {"text": "imitations of the\ncall of the bird.", "start": 473.49, "duration": 2.01}, {"text": "So a little chickadee\nis named after the thing", "start": 475.5, "duration": 3.058}, {"text": "that a chickadee says.", "start": 478.558, "duration": 0.917}, {"text": "It sounds like it's\nsaying \"chickadee,\"", "start": 479.475, "duration": 1.725}, {"text": "if you listen to a chickadee.", "start": 481.2, "duration": 2.19}, {"text": "Or Passamaquoddy, the word\nfor \"Great Horned Owl,\"", "start": 483.39, "duration": 3.6}, {"text": "is [NON-ENGLISH],, which\nis a pretty good imitation", "start": 486.99, "duration": 2.97}, {"text": "of an owl.", "start": 489.96, "duration": 1.2}, {"text": "So there are some\nthings like that", "start": 491.16, "duration": 1.56}, {"text": "where people seem\nto be imitating", "start": 492.72, "duration": 1.74}, {"text": "the sounds made by something.", "start": 494.46, "duration": 4.11}, {"text": "In ASL, of course, your\nsounds are not relevant.", "start": 498.57, "duration": 5.16}, {"text": "In a sense, you have\na lot of chances", "start": 503.73, "duration": 1.92}, {"text": "to have non-arbitrary signs.", "start": 505.65, "duration": 2.22}, {"text": "So there are signs\nthat really do", "start": 507.87, "duration": 2.22}, {"text": "look like you're\nimitating the thing,", "start": 510.09, "duration": 2.55}, {"text": "trying to make an\nimage of the thing.", "start": 512.64, "duration": 1.99}, {"text": "So here's \"book.\"", "start": 514.63, "duration": 1.297}, {"text": "That's \"book.\"", "start": 515.927, "duration": 0.583}, {"text": "You can see why that's\nthe word for \"book.\"", "start": 516.51, "duration": 2.31}, {"text": "Or this is \"tree,\"\nand you can see", "start": 518.82, "duration": 2.187}, {"text": "why that's the word for \"tree.\"", "start": 521.007, "duration": 1.292}, {"text": "It's a picture of a tree.", "start": 522.299, "duration": 1.411}, {"text": "This is the kind of\nthing that gets people", "start": 523.71, "duration": 3.03}, {"text": "to think that ASL is basically\na very sophisticated version", "start": 526.74, "duration": 3.72}, {"text": "of charades, that people are\njust trying to imitate things,", "start": 530.46, "duration": 4.53}, {"text": "and then you're done.", "start": 534.99, "duration": 1.27}, {"text": "But of course, that's not it.", "start": 536.26, "duration": 1.7}, {"text": "Signs are just as\narbitrary in ASL", "start": 537.96, "duration": 2.19}, {"text": "as they are in any\nspoken language.", "start": 540.15, "duration": 1.56}, {"text": "That is to say they're\nmostly arbitrary,", "start": 541.71, "duration": 2.07}, {"text": "with some other cases\nlike \"chickadee\"", "start": 543.78, "duration": 2.34}, {"text": "for English or \"book\"\nfor ASL, cases where it's", "start": 546.12, "duration": 3.48}, {"text": "possible to imitate something.", "start": 549.6, "duration": 1.71}, {"text": "There's a fair amount\nof work on the phonology", "start": 553.83, "duration": 1.98}, {"text": "of signed languages-- which,\nwhen I say it that way,", "start": 555.81, "duration": 2.67}, {"text": "sounds like a bad joke.", "start": 558.48, "duration": 1.51}, {"text": "I mean, what does that mean,\nthe phonology of sign languages?", "start": 559.99, "duration": 3.2}, {"text": "But it's actually, there's this\nreally cool stuff that people", "start": 563.19, "duration": 2.73}, {"text": "have observed about, if you\nthink of phonology as being", "start": 565.92, "duration": 3.93}, {"text": "the study of how basic units\ncan be combined to make slightly", "start": 569.85, "duration": 4.89}, {"text": "larger units-- so OK,\nfor spoken languages,", "start": 574.74, "duration": 2.58}, {"text": "those units are sounds--", "start": 577.32, "duration": 1.56}, {"text": "and we make all kinds of\nobservations about the rules", "start": 578.88, "duration": 2.37}, {"text": "for how those things\nget to combine.", "start": 581.25, "duration": 2.25}, {"text": "And cast your mind back to when\nI was showing you some Lardil", "start": 583.5, "duration": 2.79}, {"text": "data, and I said, we\nconvinced ourselves", "start": 586.29, "duration": 3.09}, {"text": "that it was useful to think\nthat the accusative forms were", "start": 589.38, "duration": 4.32}, {"text": "a more reliable guide\nto the underlying forms", "start": 593.7, "duration": 4.23}, {"text": "than the nominative forms were.", "start": 597.93, "duration": 1.68}, {"text": "That's what we ended\nup saying for Lardil.", "start": 599.61, "duration": 2.47}, {"text": "So we wanted to say, -in is\nbeing added to the underlying", "start": 602.08, "duration": 4.4}, {"text": "form of the noun, which\nfor \"woman\" is \"bidngen\"", "start": 606.48, "duration": 3.06}, {"text": "and for \"fish\" is \"yak.\"", "start": 609.54, "duration": 2.64}, {"text": "And if you ask a Lardil speaker,\nwhat's your word for fish,", "start": 612.18, "duration": 2.67}, {"text": "they're not going to say \"yak.\"", "start": 614.85, "duration": 1.77}, {"text": "They're going to say \"yaga.\"", "start": 616.62, "duration": 1.26}, {"text": "But that's because, although\nthe Lardil word for fish is", "start": 617.88, "duration": 4.05}, {"text": "underlyingly \"yak,\" Lardil\nalso has a basic rule--", "start": 621.93, "duration": 3.6}, {"text": "a bunch of rules--", "start": 625.53, "duration": 0.9}, {"text": "that lengthen\nmonosyllabic words.", "start": 626.43, "duration": 2.16}, {"text": "And we talked about\nvarious rules of this kind.", "start": 628.59, "duration": 2.76}, {"text": "They add different\nthings depending", "start": 631.35, "duration": 1.86}, {"text": "on what the monosyllabic word\nends in, what sound it ends in,", "start": 633.21, "duration": 4.38}, {"text": "with the upshot that \"yak\"\nis not a possible Lardil", "start": 637.59, "duration": 4.14}, {"text": "word because it's too short.", "start": 641.73, "duration": 1.83}, {"text": "And Lardil, therefore,\nlengthens it", "start": 643.56, "duration": 2.64}, {"text": "if you haven't added\nanything to it.", "start": 646.2, "duration": 1.665}, {"text": "So if you've made it\naccusative, you're fine.", "start": 647.865, "duration": 1.875}, {"text": "It's two syllables long,\n\"yaga,\" and you're all done.", "start": 649.74, "duration": 2.557}, {"text": "But if you wanted\nit to be nominative,", "start": 652.297, "duration": 1.583}, {"text": "you weren't going to add any\nsuffixes to it, well, then,", "start": 653.88, "duration": 1.98}, {"text": "you need to add another\nvowel because it's too short.", "start": 655.86, "duration": 1.95}, {"text": "That was the picture of\nLardil that we ended up with.", "start": 657.81, "duration": 2.07}, {"text": "Does that sound even\nfaintly familiar?", "start": 659.88, "duration": 1.583}, {"text": "That's what we\nwere talking about.", "start": 661.463, "duration": 1.837}, {"text": "That's a story about\nLardil that says", "start": 663.3, "duration": 1.95}, {"text": "Lardil is like many languages\nin having what's called", "start": 665.25, "duration": 2.55}, {"text": "a minimal word requirement.", "start": 667.8, "duration": 1.44}, {"text": "That is, in Lardil, it\nsays Lardil words can't", "start": 669.24, "duration": 3.12}, {"text": "be just one syllable long.", "start": 672.36, "duration": 1.142}, {"text": "If you have a word\nthat's going to end up", "start": 673.502, "duration": 1.708}, {"text": "being one syllable long,\nyou do something to it", "start": 675.21, "duration": 1.71}, {"text": "to make it longer.", "start": 676.92, "duration": 0.75}, {"text": "ASL has also been argued to\nhave a minimal word requirement,", "start": 680.1, "duration": 3.78}, {"text": "and the argument goes like this.", "start": 683.88, "duration": 1.35}, {"text": "There are signs that, if\nthey're by themselves,", "start": 685.23, "duration": 3.36}, {"text": "they involve a movement\nwhich is often short.", "start": 688.59, "duration": 2.31}, {"text": "But then, that\nmovement goes away", "start": 690.9, "duration": 1.74}, {"text": "if they're made part\nof a larger word.", "start": 692.64, "duration": 2.02}, {"text": "So here's the ASL for \"think.\"", "start": 694.66, "duration": 3.43}, {"text": "You take your finger, you\nmove it towards your temple,", "start": 698.09, "duration": 3.91}, {"text": "and touch yourself in\nthe temple briefly.", "start": 702.0, "duration": 1.74}, {"text": "Yeah, that's \"think\" and\n[INAUDIBLE] \"I think.\"", "start": 703.74, "duration": 3.45}, {"text": "And here is \"shocked.\"", "start": 707.19, "duration": 1.313}, {"text": "So \"shocked\" starts with\nyour finger at your temple,", "start": 708.503, "duration": 2.167}, {"text": "where it would be\nfor \"think,\" and then", "start": 710.67, "duration": 1.625}, {"text": "it has a second\ncomponent, \"shocked.\"", "start": 712.295, "duration": 2.455}, {"text": "\"I'm shocked.\"", "start": 714.75, "duration": 0.93}, {"text": "Yeah, so \"think,\" one way\nto think about \"think\"", "start": 715.68, "duration": 5.46}, {"text": "is just having your\nhand in a position.", "start": 721.14, "duration": 2.37}, {"text": "That's too small.", "start": 723.51, "duration": 1.32}, {"text": "That's like a\nmonosyllable in Lardil.", "start": 724.83, "duration": 2.01}, {"text": "And so you add something.", "start": 726.84, "duration": 1.26}, {"text": "You add emotion.", "start": 728.1, "duration": 0.84}, {"text": "Your hand moves\ntowards your temple.", "start": 728.94, "duration": 2.58}, {"text": "But if you're adding,\nif you're making", "start": 731.52, "duration": 1.74}, {"text": "\"shocked,\" which is \"think\"\nplus something else--", "start": 733.26, "duration": 2.85}, {"text": "that's kind of like the\naccusative of \"fish\"--", "start": 736.11, "duration": 2.13}, {"text": "then it's OK to just start\nwith your hand at your temple", "start": 738.24, "duration": 2.55}, {"text": "and then do the second half.", "start": 740.79, "duration": 1.35}, {"text": "You don't have to add\nthat motion to your hand.", "start": 742.14, "duration": 3.84}, {"text": "And the suggestion that's been\nmade in the literature on ASL", "start": 745.98, "duration": 3.18}, {"text": "phonology is this is like\na minimal word requirement.", "start": 749.16, "duration": 3.55}, {"text": "So Diane Brentari has suggested\nASL signs have a minimal word", "start": 752.71, "duration": 4.76}, {"text": "requirement.", "start": 757.47, "duration": 0.72}, {"text": "She doesn't say \"like Lardil.\"", "start": 758.19, "duration": 1.25}, {"text": "I forget what minimal word\nlanguage she's talking about.", "start": 759.44, "duration": 2.81}, {"text": "So they have to contain at\nleast one move, is her idea.", "start": 762.25, "duration": 3.68}, {"text": "\"Think\" Is the ASL version of\nthe Lardil word for \"fish.\"", "start": 765.93, "duration": 3.21}, {"text": "Remember Polish obstruents?", "start": 773.33, "duration": 2.82}, {"text": "I like this class because\nI think I promised you", "start": 776.15, "duration": 2.197}, {"text": "that I was never, ever again\ngoing to talk about Polish,", "start": 778.347, "duration": 2.333}, {"text": "and so I apologize.", "start": 780.68, "duration": 2.15}, {"text": "It's the last day.", "start": 782.83, "duration": 0.88}, {"text": "You don't have to hear\nany more about Polish.", "start": 783.71, "duration": 1.875}, {"text": "Sorry, go ahead.", "start": 785.585, "duration": 0.755}, {"text": "AUDIENCE: I just\nhave a question.", "start": 786.34, "duration": 1.06}, {"text": "NORVIN RICHARDS: Yeah.", "start": 787.4, "duration": 0.917}, {"text": "AUDIENCE: Are there other words\nthat have \"think\" something?", "start": 788.317, "duration": 3.033}, {"text": "NORVIN RICHARDS:\nOh, dear, now we", "start": 791.35, "duration": 1.8}, {"text": "get beyond my very modest\nknowledge about ASL.", "start": 793.15, "duration": 2.82}, {"text": "I don't know.", "start": 795.97, "duration": 0.66}, {"text": "Are you thinking that\nmight be the only one?", "start": 796.63, "duration": 2.85}, {"text": "AUDIENCE: Well, I think,\nagain, if you, I guess,", "start": 799.48, "duration": 3.71}, {"text": "look at compound words, there\nis definitely the ability", "start": 803.19, "duration": 3.18}, {"text": "to pair them with other things.", "start": 806.37, "duration": 3.26}, {"text": "So I was just wondering\nif that's a common way", "start": 809.63, "duration": 3.33}, {"text": "to just show surprise,\nmaybe confusion.", "start": 812.96, "duration": 4.17}, {"text": "NORVIN RICHARDS:\nOh, you mean having", "start": 817.13, "duration": 1.5}, {"text": "this as part of a larger sign?", "start": 818.63, "duration": 1.95}, {"text": "Yeah, so Brentari's\ndiscussion certainly makes", "start": 820.58, "duration": 2.522}, {"text": "it sound like there\nare a bunch of these.", "start": 823.102, "duration": 1.708}, {"text": "\"Shocked\" is the\nexamples she uses,", "start": 824.81, "duration": 1.503}, {"text": "and I'm afraid I don't\nknow any other examples", "start": 826.313, "duration": 1.917}, {"text": "off the top of my head.", "start": 828.23, "duration": 0.81}, {"text": "I'll try to find the paper\nthat I got this from,", "start": 829.04, "duration": 2.01}, {"text": "and I can put it on the\nwebsite so you can take a look.", "start": 831.05, "duration": 3.7}, {"text": "So here I am signing\nthings at you, yeah.", "start": 834.75, "duration": 4.48}, {"text": "Polish-- last time, I promise,\nwe will talk about Polish.", "start": 839.23, "duration": 2.52}, {"text": "Polish obstruents, so\nstops and fricatives--", "start": 841.75, "duration": 4.2}, {"text": "we convinced\nourselves that Polish", "start": 845.95, "duration": 1.59}, {"text": "has what's called final\nvoicing, cross-linguistically", "start": 847.54, "duration": 2.31}, {"text": "extraordinarily common, a\nphenomenon in which, if you", "start": 849.85, "duration": 4.17}, {"text": "have a voiced obstruent\nat the end of a word,", "start": 854.02, "duration": 3.88}, {"text": "it becomes voiceless.", "start": 857.9, "duration": 1.08}, {"text": "So if you look at the\nplurals of these nouns,", "start": 858.98, "duration": 2.94}, {"text": "then you can see that before\nthe plural suffix \"i\",", "start": 861.92, "duration": 2.54}, {"text": "you can have both\nvoiced and voiceless", "start": 864.46, "duration": 2.79}, {"text": "stops and fricatives-- in\nthe last example, \"nose\"", "start": 867.25, "duration": 2.85}, {"text": "and \"rubble,\"\nplural of \"rubble,\"", "start": 870.1, "duration": 1.95}, {"text": "which, hopefully, none of\nus will meet any time soon.", "start": 872.05, "duration": 3.7}, {"text": "But that if you don't have the\nplural, all of these obstruents", "start": 875.75, "duration": 2.75}, {"text": "are voiceless if they're\nat the end of a word", "start": 878.5, "duration": 1.875}, {"text": "because Polish has\nfinal devoicing.", "start": 880.375, "duration": 2.295}, {"text": "This was part of the argument\nthat we need to posit", "start": 882.67, "duration": 3.09}, {"text": "an underlying representation for\na word like \"lye,\" let's say--", "start": 885.76, "duration": 3.39}, {"text": "the second line there--\nwhich ends in a voiced stop,", "start": 889.15, "duration": 4.59}, {"text": "because that gives us the best--", "start": 893.74, "duration": 2.7}, {"text": "well, the best\nmatch on the data.", "start": 896.44, "duration": 1.848}, {"text": "So it allows us to account\nfor the fact that the plural", "start": 898.288, "duration": 2.292}, {"text": "of \"bow\" and \"lye\" look\ndifferent from each other--", "start": 900.58, "duration": 2.89}, {"text": "they're \"wuki\" and \"wugi\"--", "start": 903.47, "duration": 1.58}, {"text": "even though the\nsingulars look the same.", "start": 905.05, "duration": 2.258}, {"text": "So this is what we were doing\nback when we were doing Polish,", "start": 907.308, "duration": 2.542}, {"text": "Yeah?", "start": 909.85, "duration": 0.96}, {"text": "Have I triggered your\nPolish flashbacks?", "start": 910.81, "duration": 2.68}, {"text": "OK, so it has voiced\nobstruents, but they're", "start": 913.49, "duration": 2.272}, {"text": "limited in where they can go.", "start": 915.762, "duration": 1.208}, {"text": "They can't go at\nthe ends of words.", "start": 916.97, "duration": 2.69}, {"text": "Here's an observation about\nthe distribution of finger", "start": 919.66, "duration": 2.25}, {"text": "wiggling in the ASL sign.", "start": 921.91, "duration": 1.68}, {"text": "So sometimes when\nyou make an ASL sign,", "start": 923.59, "duration": 1.86}, {"text": "you wiggle your fingers.", "start": 925.45, "duration": 1.26}, {"text": "There are ASL signs in which\nthere isn't much movement,", "start": 926.71, "duration": 3.242}, {"text": "or just one of Brentari's\nshortened ones,", "start": 929.952, "duration": 1.708}, {"text": "like the word for\n\"color,\" which is this.", "start": 931.66, "duration": 1.83}, {"text": "So you put your\nhand to your chin,", "start": 933.49, "duration": 1.86}, {"text": "and you wiggle your fingers.", "start": 935.35, "duration": 2.46}, {"text": "There are also signs where\nyour hands are moving", "start": 937.81, "duration": 3.81}, {"text": "and the wiggling is\nhappening during the move,", "start": 941.62, "duration": 2.1}, {"text": "like go up in flames,\nwhere your hands are rising", "start": 943.72, "duration": 3.7}, {"text": "and your fingers are wiggling.", "start": 947.42, "duration": 1.25}, {"text": "That's how you do\ngo up in flames.", "start": 948.67, "duration": 2.07}, {"text": "So ASL signs can have\nfinger wiggling in them,", "start": 950.74, "duration": 2.61}, {"text": "but there are imaginable\nsigns that you don't get.", "start": 953.35, "duration": 2.58}, {"text": "So you could\nimagine a sign where", "start": 955.93, "duration": 2.52}, {"text": "your fingers would wiggle,\nand then you would move.", "start": 958.45, "duration": 2.7}, {"text": "It would be like\ngo up in flames,", "start": 961.15, "duration": 2.088}, {"text": "except you would wiggle first\nbefore you began moving--", "start": 963.238, "duration": 2.292}, {"text": "or in which you moved\nand then, having reached", "start": 965.53, "duration": 2.28}, {"text": "your destination,\nyou did a long move--", "start": 967.81, "duration": 2.28}, {"text": "not one of your short\nmoves, but a long move--", "start": 970.09, "duration": 2.265}, {"text": "did your move, and then\nwiggled your fingers.", "start": 972.355, "duration": 1.875}, {"text": "But there aren't\nany signs like that.", "start": 974.23, "duration": 2.46}, {"text": "So finger wiggling\nis either confined", "start": 976.69, "duration": 5.13}, {"text": "to the position\nat the end of one", "start": 981.82, "duration": 2.13}, {"text": "of Brentari's short movements,\nor if your hands are moving", "start": 983.95, "duration": 2.85}, {"text": "over a longer distance like in\n\"go up in flames,\" well, you", "start": 986.8, "duration": 3.28}, {"text": "have to wiggle the whole time.", "start": 990.08, "duration": 1.25}, {"text": "Similar observation\nabout hand shape change.", "start": 995.66, "duration": 2.707}, {"text": "So there are signs where your\nhands just do a short move", "start": 998.367, "duration": 2.333}, {"text": "and then change their hand\nshape, like \"understand,\" where", "start": 1000.7, "duration": 4.08}, {"text": "your hand moves into position\nand then, put up one finger,", "start": 1004.78, "duration": 2.7}, {"text": "\"understand,\" or \"old\", where\nyour hand starts at your chin", "start": 1007.48, "duration": 5.48}, {"text": "and moves as it moves away\nfrom your chin-- \"old.\"", "start": 1012.96, "duration": 2.25}, {"text": "Yeah?", "start": 1015.21, "duration": 1.17}, {"text": "AUDIENCE: You're talking about\nother mental concepts being", "start": 1016.38, "duration": 5.58}, {"text": "expressed in sign\nlanguage and understand--", "start": 1021.96, "duration": 3.31}, {"text": "so it also starts at the temple?", "start": 1025.27, "duration": 2.007}, {"text": "NORVIN RICHARDS: Yeah,\nso I think, right, I", "start": 1027.277, "duration": 1.792}, {"text": "think there are a number of--", "start": 1029.069, "duration": 1.591}, {"text": "not surprising, maybe\na number of mental.", "start": 1030.66, "duration": 1.885}, {"text": "So \"forget\" is another one.", "start": 1032.545, "duration": 1.125}, {"text": "This is \"forget,\" where you wipe\nsomething off of your brain,", "start": 1033.67, "duration": 3.35}, {"text": "yeah, using your middle finger.", "start": 1037.02, "duration": 3.7}, {"text": "Your middle finger is\nalso used for being sick.", "start": 1040.72, "duration": 3.8}, {"text": "So yeah, there are\na bunch of signs,", "start": 1044.52, "duration": 1.5}, {"text": "that use your head that\nhave to do with what's", "start": 1046.02, "duration": 2.053}, {"text": "going on in your head.", "start": 1048.073, "duration": 0.917}, {"text": "Yeah, that's right.", "start": 1048.99, "duration": 1.11}, {"text": "That's right.", "start": 1050.1, "duration": 1.482}, {"text": "OK, so ASL has finger\nwiggling, but there", "start": 1051.582, "duration": 3.196}, {"text": "are limits on where\nfinger wiggling can go.", "start": 1054.778, "duration": 1.792}, {"text": "It goes during the\nmotion, or it goes right", "start": 1056.57, "duration": 1.792}, {"text": "after one of Brentari's\nshort movements.", "start": 1058.362, "duration": 2.198}, {"text": "Hand shape change is the same.", "start": 1060.56, "duration": 1.38}, {"text": "It goes after one of\nBrentari's short movements,", "start": 1061.94, "duration": 1.62}, {"text": "like in \"understand,\" or it\ngoes during the movement,", "start": 1063.56, "duration": 1.83}, {"text": "like in \"old.\"", "start": 1065.39, "duration": 0.9}, {"text": "Yeah, but there aren't--", "start": 1066.29, "duration": 1.99}, {"text": "did I say this in\nthe next slide?", "start": 1068.28, "duration": 1.58}, {"text": "Yeah, again, you can\nimagine a sign where--", "start": 1069.86, "duration": 3.36}, {"text": "which would be like \"old\" where\nyou would start with one hand", "start": 1073.22, "duration": 2.79}, {"text": "shape, you change\nshapes, and then move,", "start": 1076.01, "duration": 3.54}, {"text": "or where you would move along\ndistance and then change", "start": 1079.55, "duration": 2.37}, {"text": "shapes, but there aren't\nany signs like that.", "start": 1081.92, "duration": 3.7}, {"text": "And so people have\nsuggested, yeah,", "start": 1085.62, "duration": 1.76}, {"text": "just like a phonologist has\nto be able to say things like,", "start": 1087.38, "duration": 2.76}, {"text": "this is a language that has\nvoiced obstruents but not", "start": 1090.14, "duration": 3.42}, {"text": "at the ends of words-- there are\nlimits on where they can go--", "start": 1093.56, "duration": 2.94}, {"text": "ASL has finger wiggling, and\nit has hand shape change,", "start": 1096.5, "duration": 3.27}, {"text": "but it has rules about where\nthey can go in the sign.", "start": 1099.77, "duration": 2.49}, {"text": "And then, of course,\nyou want to know why--", "start": 1102.26, "duration": 1.95}, {"text": "like why, what constrains\nthese to where they go.", "start": 1104.21, "duration": 3.18}, {"text": "But when I say that there's\nwork on ASL phonology, ,", "start": 1107.39, "duration": 2.76}, {"text": "this is what I mean--", "start": 1110.15, "duration": 0.972}, {"text": "there's people\ntrying to figure out", "start": 1111.122, "duration": 1.458}, {"text": "what makes something a\npossible well-formed ASL sign.", "start": 1112.58, "duration": 3.81}, {"text": "It turns out there\nare limits on this.", "start": 1116.39, "duration": 3.24}, {"text": "One observation,\nactually, that people", "start": 1119.63, "duration": 2.82}, {"text": "have made as they\ndo this work, there", "start": 1122.45, "duration": 2.79}, {"text": "are compounds or\npolymorphemic signs,", "start": 1125.24, "duration": 4.062}, {"text": "which you can tell they're\npolymorphemic because they", "start": 1129.302, "duration": 2.208}, {"text": "appear to violate these rules.", "start": 1131.51, "duration": 1.21}, {"text": "So I just said, there aren't\nany signs where you first", "start": 1132.72, "duration": 2.25}, {"text": "finger wiggle and then move.", "start": 1134.97, "duration": 2.98}, {"text": "Here's an apparent\ncounterexample to that.", "start": 1137.95, "duration": 1.75}, {"text": "There's a word \"hypnotist,\"\nwhich goes like this.", "start": 1139.7, "duration": 3.105}, {"text": "But that's a two-morpheme sign.", "start": 1145.43, "duration": 2.52}, {"text": "So it's \"hypnotize\"-- which is\na Brentari short movement plus", "start": 1147.95, "duration": 5.04}, {"text": "finger wiggling-- and\nthen there's a suffix,", "start": 1152.99, "duration": 2.61}, {"text": "which is the agentive suffix.", "start": 1155.6, "duration": 1.86}, {"text": "You use it to make--", "start": 1157.46, "duration": 1.38}, {"text": "you attach it to nouns to\nmake people who do that now.", "start": 1158.84, "duration": 2.47}, {"text": "So it's a hypnotist.", "start": 1161.31, "duration": 1.97}, {"text": "So \"hypnotist\" by itself looks\nlike you're finger wiggling", "start": 1163.28, "duration": 4.11}, {"text": "and then moving.", "start": 1167.39, "duration": 0.93}, {"text": "But that's because there's\na morpheme boundary", "start": 1168.32, "duration": 1.56}, {"text": "between those two things.", "start": 1169.88, "duration": 0.95}, {"text": "So within a morpheme,\nyou can think of it", "start": 1170.83, "duration": 1.708}, {"text": "as a bisyllabic\nword if you want.", "start": 1172.538, "duration": 1.822}, {"text": "So in the first syllable,\nyou're doing finger wiggling", "start": 1174.36, "duration": 2.48}, {"text": "the same way you're doing\nfinger wiggling in color.", "start": 1176.84, "duration": 3.75}, {"text": "And then there's a\nsecond move, which", "start": 1180.59, "duration": 1.8}, {"text": "involves moving your hands.", "start": 1182.39, "duration": 1.23}, {"text": "ASL has one-handed\nsigns, like \"understand,\"", "start": 1189.39, "duration": 3.48}, {"text": "and it also has two-handed\nsigns, like \"go up in flames.\"", "start": 1192.87, "duration": 5.29}, {"text": "There's an interesting\nrestriction in two-handed signs", "start": 1198.16, "duration": 2.25}, {"text": "on the second hand.", "start": 1200.41, "duration": 1.05}, {"text": "So the second hand\neither has to stay still,", "start": 1201.46, "duration": 2.73}, {"text": "like in tree, where one hand\nmoves and the other hand", "start": 1204.19, "duration": 3.24}, {"text": "just stays there in the\nbackground for the first sign,", "start": 1207.43, "duration": 3.75}, {"text": "or it does the same\nthing as the other hand.", "start": 1211.18, "duration": 3.24}, {"text": "So \"teach,\" both your hands\nare doing the same thing.", "start": 1214.42, "duration": 3.87}, {"text": "I love the sign for \"teach.\"", "start": 1218.29, "duration": 1.8}, {"text": "I want to do this\nwhen I teach now.", "start": 1220.09, "duration": 3.33}, {"text": "Or bicycle, where your hands\nare doing the same thing,", "start": 1223.42, "duration": 2.652}, {"text": "but they're out of\nphase with each other.", "start": 1226.072, "duration": 1.708}, {"text": "So they're both\ngoing in circles.", "start": 1227.78, "duration": 2.79}, {"text": "Which is kind of\ninteresting because--", "start": 1230.57, "duration": 1.88}, {"text": "so and that's it, right?", "start": 1232.45, "duration": 1.62}, {"text": "So there aren't\nASL signs in which", "start": 1234.07, "duration": 2.882}, {"text": "one hand is doing one\nthing and the other hand,", "start": 1236.952, "duration": 1.958}, {"text": "is doing a completely\ndifferent thing.", "start": 1238.91, "duration": 2.4}, {"text": "And it's not because--", "start": 1241.31, "duration": 1.97}, {"text": "does that make sense?", "start": 1243.28, "duration": 1.32}, {"text": "So your hands can't\nboth be moving and doing", "start": 1244.6, "duration": 3.57}, {"text": "different things.", "start": 1248.17, "duration": 2.05}, {"text": "Which is interesting, because it\nis actually physically possible", "start": 1250.22, "duration": 2.75}, {"text": "to violate this, to have your\ntwo hands both moving and doing", "start": 1252.97, "duration": 3.48}, {"text": "different things, in poetry.", "start": 1256.45, "duration": 1.59}, {"text": "So there's a video which\nI'll try to show you now", "start": 1258.04, "duration": 3.18}, {"text": "of an ASL poet, guy\nnamed Clayton Valli, who", "start": 1261.22, "duration": 4.26}, {"text": "wrote many poems in ASL.", "start": 1265.48, "duration": 1.26}, {"text": "There are a lot\nof YouTube videos", "start": 1266.74, "duration": 1.62}, {"text": "of him performing his poems.", "start": 1268.36, "duration": 2.4}, {"text": "And this one is\ncalled \"Snowflake.\"", "start": 1270.76, "duration": 2.97}, {"text": "And what he does in it--", "start": 1273.73, "duration": 3.14}, {"text": "the reason I'm going\nto show you the video", "start": 1276.87, "duration": 1.75}, {"text": "is that I can't physically\ndo it very well.", "start": 1278.62, "duration": 1.92}, {"text": "I'll show you what he does.", "start": 1280.54, "duration": 1.83}, {"text": "But I'll tell you\nwhat he's about to do,", "start": 1282.37, "duration": 2.02}, {"text": "just so you can see it.", "start": 1284.39, "duration": 1.67}, {"text": "With one hand, he's doing\nthe sign for \"snowflake\"--", "start": 1286.06, "duration": 3.53}, {"text": "which is a snowflake falling.", "start": 1289.59, "duration": 1.95}, {"text": "And, then with the other\nhand, he's signing one-handed", "start": 1291.54, "duration": 2.31}, {"text": "versions of--", "start": 1293.85, "duration": 1.243}, {"text": "I may not get the order right--", "start": 1295.093, "duration": 1.292}, {"text": "white, cold, beautiful.", "start": 1298.98, "duration": 6.32}, {"text": "And he's doing this as\nthis hand is moving.", "start": 1305.3, "duration": 1.94}, {"text": "So this hand is moving, and\nwith the other hand, he's going,", "start": 1307.24, "duration": 2.5}, {"text": "white, cold, beautiful.", "start": 1309.74, "duration": 1.56}, {"text": "And as you can see, I can't\nphysically do this, but he can.", "start": 1311.3, "duration": 3.24}, {"text": "Let me show you him doing it.", "start": 1314.54, "duration": 1.23}, {"text": "Let me get it.", "start": 1318.47, "duration": 2.732}, {"text": "Where is he?", "start": 1321.202, "duration": 0.608}, {"text": "Yeah, so here's Clayton Valli.", "start": 1321.81, "duration": 1.297}, {"text": "And I think I paused it in\nmore or less the right place,", "start": 1323.107, "duration": 2.333}, {"text": "and we have to watch\nthis for a little bit.", "start": 1325.44, "duration": 1.792}, {"text": "So he's about to sign\nabout looking out", "start": 1327.232, "duration": 2.438}, {"text": "the window at a snowy day.", "start": 1329.67, "duration": 1.71}, {"text": "The snow is coming down.", "start": 1331.38, "duration": 2.43}, {"text": "And now I think\nit's about to come.", "start": 1333.81, "duration": 2.47}, {"text": "Here's the snow piled up.", "start": 1336.28, "duration": 1.07}, {"text": "Come on, Clayton.", "start": 1341.014, "duration": 1.066}, {"text": "Yeah, here it is.", "start": 1346.732, "duration": 0.708}, {"text": "There's the snowflake\nfalling, and", "start": 1347.44, "duration": 1.92}, {"text": "white, beautiful, cold,\nyeah, with his other hand.", "start": 1349.36, "duration": 4.56}, {"text": "So it's physically\npossible to do that,", "start": 1353.92, "duration": 3.63}, {"text": "at least if you're Clayton\nValli, if you're a fluent ASL", "start": 1357.55, "duration": 2.82}, {"text": "signer.", "start": 1360.37, "duration": 1.62}, {"text": "But there aren't any\nASL signs that do it.", "start": 1361.99, "duration": 2.17}, {"text": "It's one of those rules\nthat you break in order", "start": 1364.16, "duration": 4.13}, {"text": "to perform poetry.", "start": 1368.29, "duration": 2.07}, {"text": "So I'll put a link to that.", "start": 1370.36, "duration": 3.18}, {"text": "I'll put link to that poem on\nthe website so you can see.", "start": 1373.54, "duration": 2.76}, {"text": "Yeah?", "start": 1376.3, "duration": 0.5}, {"text": "AUDIENCE: I feel\nlike that might just", "start": 1376.8, "duration": 0.91}, {"text": "be because most people\naren't capable of doing", "start": 1377.71, "duration": 2.49}, {"text": "that, like do a\ncircle with one hand", "start": 1380.2, "duration": 2.523}, {"text": "and a square with the other.", "start": 1382.723, "duration": 1.167}, {"text": "Most people can't do that.", "start": 1383.89, "duration": 1.3}, {"text": "NORVIN RICHARDS:\nSo I think it's one", "start": 1385.19, "duration": 1.58}, {"text": "of those things that probably\nrequires practice, right?", "start": 1386.77, "duration": 2.55}, {"text": "And question, is this something\nthat any ASL signer could just", "start": 1389.32, "duration": 4.23}, {"text": "do cold without any trouble?", "start": 1393.55, "duration": 2.43}, {"text": "If they saw the\nClayton Valli video,", "start": 1395.98, "duration": 1.77}, {"text": "they'd be like, oh, yeah,\nand then they would do it,", "start": 1397.75, "duration": 3.15}, {"text": "and I can't do it because\nI'm not a fluent ASL signer?", "start": 1400.9, "duration": 2.46}, {"text": "Or whether it's because Clayton\nValli practiced in his room", "start": 1403.36, "duration": 3.263}, {"text": "hour after hour\nand eventually got", "start": 1406.623, "duration": 1.417}, {"text": "to where he could get\nhis hands to do that?", "start": 1408.04, "duration": 2.34}, {"text": "Yeah, right.", "start": 1410.38, "duration": 0.84}, {"text": "So I think you're right.", "start": 1411.22, "duration": 1.35}, {"text": "It's not exactly that.", "start": 1412.57, "duration": 1.03}, {"text": "It's not surprising\nthat ASL isn't", "start": 1413.6, "duration": 1.64}, {"text": "full of signs that are like\nthis, with your two hands doing", "start": 1415.24, "duration": 2.82}, {"text": "two different things.", "start": 1418.06, "duration": 1.72}, {"text": "But it's interesting that\nit is physically possible", "start": 1419.78, "duration": 2.84}, {"text": "to learn to do it.", "start": 1422.62, "duration": 1.62}, {"text": "Yeah?", "start": 1424.24, "duration": 1.08}, {"text": "AUDIENCE: I think that it's in\ncontrast to the signing rule.", "start": 1425.32, "duration": 4.08}, {"text": "It's one of the first things\nyou learn in an ASL class.", "start": 1429.4, "duration": 2.714}, {"text": "And I believe that\nis where you should", "start": 1432.114, "duration": 2.629}, {"text": "focus all your attention,\non the dominant hand.", "start": 1434.743, "duration": 3.16}, {"text": "NORVIN RICHARDS:\nYeah, yeah, yeah.", "start": 1437.903, "duration": 1.417}, {"text": "So I mean, you're\nabsolutely right.", "start": 1439.32, "duration": 3.33}, {"text": "What happens is that\nthe non-dominant hand", "start": 1442.65, "duration": 2.25}, {"text": "either copies the\ndominant hand or just", "start": 1444.9, "duration": 2.01}, {"text": "sits still, like in \"tree.\"", "start": 1446.91, "duration": 3.15}, {"text": "And so you think this is\nsomething somebody deliberately", "start": 1450.06, "duration": 3.51}, {"text": "did?", "start": 1453.57, "duration": 0.51}, {"text": "They decided that ASL\nshould work this way?", "start": 1454.08, "duration": 2.455}, {"text": "It'd be interesting to see.", "start": 1456.535, "duration": 1.125}, {"text": "I have no idea.", "start": 1457.66, "duration": 0.65}, {"text": "I'm doing all this\ntalk about ASL.", "start": 1458.31, "duration": 2.01}, {"text": "I started by saying, there\nare many sign languages.", "start": 1460.32, "duration": 2.88}, {"text": "I don't know whether this is\ntrue in every sign language.", "start": 1463.2, "duration": 2.79}, {"text": "I haven't heard\nof a sign language", "start": 1465.99, "duration": 1.5}, {"text": "in which your hands are\nallowed to move independently", "start": 1467.49, "duration": 2.208}, {"text": "of each other.", "start": 1469.698, "duration": 1.012}, {"text": "So it'd be interesting to\nsee how universal this is.", "start": 1470.71, "duration": 2.37}, {"text": "Yeah?", "start": 1473.08, "duration": 0.5}, {"text": "Is there a left-handed versus\nright-handed version of ASL?", "start": 1473.58, "duration": 5.22}, {"text": "No, I mean if, so\nI'm right-handed,", "start": 1478.8, "duration": 3.33}, {"text": "and so this is my\nversion of \"tree.\"", "start": 1482.13, "duration": 1.5}, {"text": "If I were left-handed this\nwould be my version of \"tree.\"", "start": 1483.63, "duration": 2.85}, {"text": "And they mean the same\nthing, as far as I can tell.", "start": 1486.48, "duration": 2.67}, {"text": "Similarly, for the signs\nthat use both hands--", "start": 1489.15, "duration": 3.81}, {"text": "I mean, this is a consequence\nof these facts about the signs", "start": 1492.96, "duration": 2.91}, {"text": "that we've been talking about--\nfor the signs that use both", "start": 1495.87, "duration": 2.458}, {"text": "hands, like \"teach,\" if I'm--", "start": 1498.328, "duration": 3.354}, {"text": "somebody described this\nto me as the equivalent", "start": 1501.682, "duration": 1.958}, {"text": "of talking with your\nmouth full-- if I'm", "start": 1503.64, "duration": 1.667}, {"text": "busy with my right hand,\nif I'm holding something", "start": 1505.307, "duration": 2.713}, {"text": "or whatever, then I\ncan sign \"teach\" just", "start": 1508.02, "duration": 1.98}, {"text": "with my other hand, and\nyou don't lose anything,", "start": 1510.0, "duration": 3.3}, {"text": "in a sense.", "start": 1513.3, "duration": 2.16}, {"text": "You might if there's also a\nsign that's just like this.", "start": 1515.46, "duration": 3.93}, {"text": "And Valli, actually,\nin this video,", "start": 1519.39, "duration": 2.632}, {"text": "is doing something like that.", "start": 1522.022, "duration": 1.208}, {"text": "The sign for \"cold\"\nuses both hands.", "start": 1523.23, "duration": 4.62}, {"text": "They're both moving.", "start": 1527.85, "duration": 1.59}, {"text": "But because his right hand\nis busy doing \"snowflake,\"", "start": 1529.44, "duration": 3.01}, {"text": "he does a one-handed\nversion of \"cold,\" yeah.", "start": 1532.45, "duration": 3.16}, {"text": "Yeah, OK, and I alluded\nto this a second ago.", "start": 1541.18, "duration": 4.55}, {"text": "There's a lot of work\non the use of parts", "start": 1545.73, "duration": 1.77}, {"text": "of the body other\nthan your hands, so", "start": 1547.5, "duration": 1.44}, {"text": "your non-manual component.", "start": 1548.94, "duration": 1.083}, {"text": "There's facial expressions\nthat are involved in doing", "start": 1550.023, "duration": 2.787}, {"text": "certain kinds of things.", "start": 1552.81, "duration": 1.0}, {"text": "So as I said, in\nwh-questions in ASL,", "start": 1553.81, "duration": 3.5}, {"text": "wh-questions require\nyou to furrow your brow", "start": 1557.31, "duration": 3.06}, {"text": "and look puzzled.", "start": 1560.37, "duration": 1.41}, {"text": "And there's all this interesting\nwork on where, exactly, you're", "start": 1561.78, "duration": 2.647}, {"text": "required to do that.", "start": 1564.427, "duration": 0.833}, {"text": "As I said, ASL is a\nwh-in-situ language,", "start": 1565.26, "duration": 4.455}, {"text": "or it has the option\nof wh in situ.", "start": 1569.715, "duration": 2.235}, {"text": "And I do have chalk\ntoday, which is nice.", "start": 1571.95, "duration": 3.16}, {"text": "So apparently,\nwhat that means is", "start": 1575.11, "duration": 3.5}, {"text": "that if you're doing the ASL for\n\"You gave what to the teacher?\"", "start": 1578.61, "duration": 14.07}, {"text": "where just pretend that\nall of this is ASL,", "start": 1592.68, "duration": 3.03}, {"text": "you're required to\nlook puzzled here--", "start": 1595.71, "duration": 3.66}, {"text": "that is, from the\nbeginning of the question", "start": 1599.37, "duration": 2.13}, {"text": "until you get to the wh word.", "start": 1601.5, "duration": 1.68}, {"text": "And then you're allowed\nto relax your face.", "start": 1603.18, "duration": 3.45}, {"text": "And if this is an embedded\nquestion like, I don't know--", "start": 1606.63, "duration": 3.195}, {"text": "so if I'm saying the\nASL for, \"I don't know", "start": 1613.96, "duration": 2.06}, {"text": "what you gave to the teacher\"--", "start": 1616.02, "duration": 2.1}, {"text": "well, then, this is still true.", "start": 1618.12, "duration": 1.53}, {"text": "You sign \"I don't know\" without\ndoing a wh- facial expression,", "start": 1619.65, "duration": 3.57}, {"text": "but you do one for this part.", "start": 1623.22, "duration": 1.89}, {"text": "So from the beginning of the\nquestion to the wh- word,", "start": 1625.11, "duration": 3.21}, {"text": "you're required to look puzzled.", "start": 1628.32, "duration": 2.28}, {"text": "Just kind of cool there's\nthis work on this.", "start": 1630.6, "duration": 4.08}, {"text": "Or similarly, there's a negation\nin facial expression in ASL.", "start": 1634.68, "duration": 4.035}, {"text": "And so negation--", "start": 1638.715, "duration": 1.665}, {"text": "ASL has a word for \"not.\"", "start": 1640.38, "duration": 2.1}, {"text": "It's this.", "start": 1642.48, "duration": 1.87}, {"text": "And so if I want to sign--", "start": 1644.35, "duration": 2.93}, {"text": "oh, sorry.", "start": 1647.28, "duration": 0.99}, {"text": "AUDIENCE: So does that mean that\nthe facial expressions we make", "start": 1648.27, "duration": 2.78}, {"text": "when [INAUDIBLE] are\nrelated to [INAUDIBLE]", "start": 1651.05, "duration": 5.582}, {"text": "face and interaction\nwith others?", "start": 1656.632, "duration": 3.278}, {"text": "Because I would think it's\nsomething that's unique,", "start": 1659.91, "duration": 2.84}, {"text": "like when you're\nconfused, to make", "start": 1662.75, "duration": 2.32}, {"text": "an expression with your face.", "start": 1665.07, "duration": 2.01}, {"text": "Is it just related to\nthe fact that you're", "start": 1667.08, "duration": 2.154}, {"text": "talking with someone you want\nto understand you're confused.", "start": 1669.234, "duration": 2.5}, {"text": "Or is it [INAUDIBLE]?", "start": 1671.734, "duration": 1.886}, {"text": "NORVIN RICHARDS: These are all\nreally interesting questions", "start": 1673.62, "duration": 1.38}, {"text": "to which I don't\nknow the answers.", "start": 1675.0, "duration": 1.417}, {"text": "One possibility is that the\npuzzled facial expression,", "start": 1676.417, "duration": 4.163}, {"text": "the wh- facial\nexpression in ASL,", "start": 1680.58, "duration": 1.95}, {"text": "it's a little bit the\ntwo pronouns for \"I\"", "start": 1682.53, "duration": 3.12}, {"text": "that I was talking\nabout earlier--", "start": 1685.65, "duration": 1.47}, {"text": "that this is \"I\" in ASL, and\nthis is \"I\" in Japanese Sign", "start": 1687.12, "duration": 2.82}, {"text": "Language, and that maybe\nthat's connected to gestures", "start": 1689.94, "duration": 2.55}, {"text": "that hearing people make that\nspeakers of sign languages", "start": 1692.49, "duration": 4.59}, {"text": "are using in a different way.", "start": 1697.08, "duration": 1.45}, {"text": "So you're right, I might, if I\nwere asking you a wh- question,", "start": 1698.53, "duration": 3.41}, {"text": "look puzzled.", "start": 1701.94, "duration": 1.96}, {"text": "I don't have to look puzzled\nto ask you a wh-question,", "start": 1703.9, "duration": 2.72}, {"text": "and there are no particular\nrestrictions on when I should", "start": 1706.62, "duration": 3.69}, {"text": "look puzzled--", "start": 1710.31, "duration": 0.99}, {"text": "where during my question\nI should look puzzled.", "start": 1711.3, "duration": 2.67}, {"text": "But in ASL, there are.", "start": 1713.97, "duration": 1.68}, {"text": "You actually have\nto do this, and you", "start": 1715.65, "duration": 1.8}, {"text": "have to do it at\nthe right points,", "start": 1717.45, "duration": 2.07}, {"text": "in the right points\nof the wh- question.", "start": 1719.52, "duration": 3.48}, {"text": "So their use of\nfacial expressions", "start": 1723.0, "duration": 2.76}, {"text": "is a little more sophisticated,\nI guess, or rule-governed,", "start": 1725.76, "duration": 3.81}, {"text": "than they have been shown to\nbe, anyway, for speaking people.", "start": 1729.57, "duration": 4.17}, {"text": "Now, maybe all this\nshows is that there", "start": 1733.74, "duration": 2.31}, {"text": "hasn't been enough work\non facial expressions", "start": 1736.05, "duration": 2.79}, {"text": "for spoken languages.", "start": 1738.84, "duration": 1.08}, {"text": "We're all obsessed\nwith the sounds,", "start": 1739.92, "duration": 2.22}, {"text": "but for ASL, there's all\nthis clever work on what you", "start": 1742.14, "duration": 3.18}, {"text": "do with the rest of your body.", "start": 1745.32, "duration": 1.32}, {"text": "Yeah, good question.", "start": 1746.64, "duration": 3.22}, {"text": "Similarly, there's a\nnegation facial expression.", "start": 1749.86, "duration": 2.61}, {"text": "So if I want to say, \"I'm\nnot deaf,\" I can sign,", "start": 1752.47, "duration": 3.99}, {"text": "\"I,\" \"not,\" and \"deaf.\"", "start": 1756.46, "duration": 4.2}, {"text": "or I can point at myself and\nshake my head as I sign \"deaf.\"", "start": 1760.66, "duration": 7.74}, {"text": "So I don't have to use\nthe sign for \"not\" at all.", "start": 1768.4, "duration": 3.36}, {"text": "By shaking my head,\nI convey negation", "start": 1771.76, "duration": 3.81}, {"text": "without using the negation sign.", "start": 1775.57, "duration": 2.435}, {"text": "So there are facial expressions\nfor both of these things.", "start": 1778.005, "duration": 2.375}, {"text": "I don't know what\nhappens when they", "start": 1780.38, "duration": 1.458}, {"text": "combine because, presumably,\nyou can ask negative questions.", "start": 1781.838, "duration": 3.164}, {"text": "I guess you can do all of these\nthings with your head at once.", "start": 1785.002, "duration": 2.583}, {"text": "One of the other properties\nof signed languages", "start": 1790.84, "duration": 4.57}, {"text": "which is cool and there's\na lot of work on it", "start": 1795.41, "duration": 3.59}, {"text": "is the use of loci\nin space to refer.", "start": 1799.0, "duration": 3.4}, {"text": "So an English\nsentence like \"Trump", "start": 1802.4, "duration": 2.3}, {"text": "told Biden that he\nwould win\" is ambiguous.", "start": 1804.7, "duration": 4.32}, {"text": "So \"he\" could refer to Trump,\nor to Biden, or to anybody else,", "start": 1809.02, "duration": 5.34}, {"text": "in principle.", "start": 1814.36, "duration": 1.01}, {"text": "It has to refer to\nsome male person.", "start": 1815.37, "duration": 1.93}, {"text": "It could refer to\neither of these people.", "start": 1817.3, "duration": 2.79}, {"text": "If you were going to\nsign this in ASL--", "start": 1820.09, "duration": 2.7}, {"text": "and I'm not going to.", "start": 1822.79, "duration": 1.148}, {"text": "I don't know enough\nASL, but I can tell you", "start": 1823.938, "duration": 1.792}, {"text": "the basic ideas about how this\nwould work-- first of all,", "start": 1825.73, "duration": 2.89}, {"text": "you would need what are\ncalled \"name signs.\"", "start": 1828.62, "duration": 2.48}, {"text": "So you would need to sign the\nnames \"Trump\" and \"Biden\".", "start": 1831.1, "duration": 3.75}, {"text": "The simple way to do that\nis by finger spelling.", "start": 1834.85, "duration": 2.67}, {"text": "So there are correspondents\nto all of the letters.", "start": 1837.52, "duration": 5.377}, {"text": "You can sign all of the letters\nof the English alphabet.", "start": 1842.897, "duration": 2.333}, {"text": "So you could sign T-R-U-M-P,\nonly you'd do it faster if you", "start": 1845.23, "duration": 4.2}, {"text": "knew ASL.", "start": 1849.43, "duration": 2.64}, {"text": "But there are also what are\ncalled \"name signs,\" which", "start": 1852.07, "duration": 2.25}, {"text": "are signs that are just\nsigns for particular people--", "start": 1854.32, "duration": 2.85}, {"text": "typically famous people,\nor people who are deaf,", "start": 1857.17, "duration": 3.87}, {"text": "I think, generally end\nup with name signs.", "start": 1861.04, "duration": 3.96}, {"text": "Name signs are often based--", "start": 1865.0, "duration": 1.77}, {"text": "they often contain the first\nletter of the person's name.", "start": 1866.77, "duration": 3.21}, {"text": "I had a classmate in\ngrad school who was deaf.", "start": 1869.98, "duration": 2.1}, {"text": "He's now a professor at\nGallaudet University.", "start": 1872.08, "duration": 3.42}, {"text": "His name was Gaurav in\nEnglish, and his ASL sign", "start": 1875.5, "duration": 3.638}, {"text": "involved the letter G, which is\nthe first letter of his name,", "start": 1879.138, "duration": 2.542}, {"text": "put on the chest.", "start": 1881.68, "duration": 0.99}, {"text": "Sorry, so that's Gaurav in ASL.", "start": 1882.67, "duration": 3.66}, {"text": "The name sign for\n\"Noam Chomsky,\"", "start": 1886.33, "duration": 1.47}, {"text": "which is one of the few\nother signs I know, is this.", "start": 1887.8, "duration": 3.24}, {"text": "So it's a C. When I\nfirst saw it, I was like,", "start": 1891.04, "duration": 2.442}, {"text": "what, they think\nhe's an alcoholic?", "start": 1893.482, "duration": 1.458}, {"text": "What is the deal?", "start": 1894.94, "duration": 1.87}, {"text": "It turns out to be based\non the sign for \"God.\"", "start": 1896.81, "duration": 2.54}, {"text": "So it's \"God\" with a C.", "start": 1899.35, "duration": 1.54}, {"text": "[LAUGHTER]", "start": 1900.89, "duration": 0.5}, {"text": "It's Noam Chomsky.", "start": 1901.39, "duration": 0.96}, {"text": "It was invented by someone\nwith the proper level", "start": 1902.35, "duration": 2.31}, {"text": "of respect for Noam Chomsky.", "start": 1904.66, "duration": 2.77}, {"text": "The name of sign for\nTrump, there are apparently", "start": 1907.43, "duration": 2.0}, {"text": "various name signs for Trump.", "start": 1909.43, "duration": 1.208}, {"text": "One of them is this--", "start": 1910.638, "duration": 0.877}, {"text": "[LAUGHTER]", "start": 1911.515, "duration": 2.965}, {"text": "Or this, that's another one.", "start": 1914.98, "duration": 3.45}, {"text": "For Biden, I was looking,\nand apparently, there", "start": 1918.43, "duration": 2.928}, {"text": "isn't general agreement on\nwhat the name sign for Biden", "start": 1921.358, "duration": 2.292}, {"text": "ought to be.", "start": 1923.65, "duration": 0.5}, {"text": "One of them is this,\nwhich is apparently", "start": 1924.15, "duration": 2.08}, {"text": "supposed to be a gesture\nthat indicates that he likes", "start": 1926.23, "duration": 3.06}, {"text": "to wear sunglasses, I guess.", "start": 1929.29, "duration": 2.22}, {"text": "It's connected to the fact\nthat he has sunglasses a lot.", "start": 1931.51, "duration": 2.55}, {"text": "By now, there must be\na name sign for Biden", "start": 1934.06, "duration": 2.01}, {"text": "because, of course, he's\nsurrounded by interpreters", "start": 1936.07, "duration": 3.06}, {"text": "when he's talking, you hope.", "start": 1939.13, "duration": 2.22}, {"text": "But anyway, if you wanted\nto say-- bless you-- in ASL,", "start": 1941.35, "duration": 2.598}, {"text": "\"Trump told Biden that he\nwould win,\" you'd sign Trump,", "start": 1943.948, "duration": 2.292}, {"text": "and you'd sign Biden, and\nyou would put them in places.", "start": 1946.24, "duration": 2.85}, {"text": "So you'd say \"Trump,\" and you'd\nput Trump here, and Biden,", "start": 1949.09, "duration": 3.09}, {"text": "put Biden here.", "start": 1952.18, "duration": 1.23}, {"text": "And then you would say,\nhe told him that he--", "start": 1953.41, "duration": 4.532}, {"text": "and then you would\neither point at Trump,", "start": 1957.942, "duration": 1.708}, {"text": "or you would point at Biden--", "start": 1959.65, "duration": 1.26}, {"text": "would win.", "start": 1960.91, "duration": 1.33}, {"text": "So the ASL versions of the\nsentence are not ambiguous.", "start": 1962.24, "duration": 2.66}, {"text": "So you make it clear.", "start": 1964.9, "duration": 2.55}, {"text": "You've either pointed at Trump,\nor you've pointed at Biden.", "start": 1967.45, "duration": 2.67}, {"text": "So he always refers to\nsomeone in particular.", "start": 1970.12, "duration": 2.22}, {"text": "Or, if what I want\nto convey to you", "start": 1972.34, "duration": 2.04}, {"text": "is \"Trump told Biden that\nObama would win,\" well,", "start": 1974.38, "duration": 2.16}, {"text": "then, I need to sign\n\"Biden,\" \"Obama,\"", "start": 1976.54, "duration": 1.65}, {"text": "and put \"Obama\" somewhere else.", "start": 1978.19, "duration": 1.5}, {"text": "You can have many, many people\nin front of you in space.", "start": 1979.69, "duration": 3.075}, {"text": "I believe people who have\nstudied this have not", "start": 1985.63, "duration": 2.37}, {"text": "found limits on how much space,\nhow much subdividing of space", "start": 1988.0, "duration": 3.51}, {"text": "you can do in front of you.", "start": 1991.51, "duration": 1.56}, {"text": "I don't know how\nhard they've tried,", "start": 1993.07, "duration": 1.5}, {"text": "but yeah, it's\ncertainly not just two.", "start": 1994.57, "duration": 2.925}, {"text": "You can have lots of\npronouns in front of you.", "start": 1997.495, "duration": 3.735}, {"text": "There are even fancier\nthings you can do.", "start": 2001.23, "duration": 1.912}, {"text": "I was just reading\na paper about this.", "start": 2003.142, "duration": 1.583}, {"text": "This is kind of astonishing.", "start": 2004.725, "duration": 1.695}, {"text": "So if I want to say something\nin ASL like \"Most of my students", "start": 2006.42, "duration": 3.78}, {"text": "came to class,\" what I do is I\nstart by signing \"my students,\"", "start": 2010.2, "duration": 5.41}, {"text": "and then I put my\nstudents in a circle.", "start": 2015.61, "duration": 2.25}, {"text": "So I have my students, and\nthen I establish a circle", "start": 2017.86, "duration": 2.69}, {"text": "that all of my students are in.", "start": 2020.55, "duration": 1.392}, {"text": "And then I'm going to make\nthe sign for \"most,\" which", "start": 2021.942, "duration": 2.208}, {"text": "I think is something like this.", "start": 2024.15, "duration": 1.39}, {"text": "And then I describe\na smaller circle", "start": 2025.54, "duration": 2.3}, {"text": "that's part of the circle that\nI've just described for you.", "start": 2027.84, "duration": 2.94}, {"text": "And then I would\nsign, \"went to class.\"", "start": 2030.78, "duration": 2.44}, {"text": "So I make my circle that\nhas all the students,", "start": 2033.22, "duration": 3.87}, {"text": "And then I have a\nsubset of that that's--", "start": 2037.09, "duration": 1.91}, {"text": "I draw the kinds of\nVenn diagram-y things", "start": 2039.0, "duration": 2.07}, {"text": "we were talking about before.", "start": 2041.07, "duration": 1.933}, {"text": "Here are the students.", "start": 2043.003, "duration": 0.917}, {"text": "And the cool thing\nabout this is now,", "start": 2043.92, "duration": 1.77}, {"text": "what I've got in front of me is\na space that's got my students,", "start": 2045.69, "duration": 3.029}, {"text": "and it's subdivided into\na larger space that's", "start": 2048.719, "duration": 3.174}, {"text": "got most of my students,\nthe ones who came to class,", "start": 2051.893, "duration": 2.167}, {"text": "and a smaller space that's\ngot the students who", "start": 2054.06, "duration": 2.04}, {"text": "didn't come to class.", "start": 2056.1, "duration": 1.15}, {"text": "So the next\nsentence, apparently,", "start": 2057.25, "duration": 1.909}, {"text": "can be \"They stayed home,\"\npointing at the ones who", "start": 2059.159, "duration": 4.471}, {"text": "didn't come to class.", "start": 2063.63, "duration": 1.529}, {"text": "In English, if I say \"Most\nof my students came to class,", "start": 2065.159, "duration": 3.601}, {"text": "they stayed home,\" I'm\ncontradicting myself.", "start": 2068.76, "duration": 5.72}, {"text": "And there's something\ninteresting going on here.", "start": 2074.48, "duration": 2.0}, {"text": "When we were talking\nabout pronouns,", "start": 2076.48, "duration": 1.5}, {"text": "we just breezed by them, right?", "start": 2077.98, "duration": 1.73}, {"text": "Pronouns, well,\nthey refer to people", "start": 2079.71, "duration": 1.86}, {"text": "who are salient or whatever.", "start": 2081.57, "duration": 2.76}, {"text": "Certainly, if I pass a bunch\nof students on the Infinite", "start": 2084.33, "duration": 5.24}, {"text": "Corridor, I could remark to\nyou, \"They're on their way", "start": 2089.57, "duration": 2.25}, {"text": "to class.\"", "start": 2091.82, "duration": 0.5}, {"text": "We don't have to have been\ntalking about them before.", "start": 2092.32, "duration": 2.208}, {"text": "They're just there in the world.", "start": 2094.528, "duration": 1.381}, {"text": "I get to assume that\nyou're thinking about them.", "start": 2095.909, "duration": 2.311}, {"text": "But if I say \"Most\nof my students", "start": 2098.22, "duration": 2.33}, {"text": "came to class,\" well, that--", "start": 2100.55, "duration": 2.67}, {"text": "I mean, I'm telling you\nthat they're my students,", "start": 2103.22, "duration": 2.4}, {"text": "and that most of\nthem came to class,", "start": 2105.62, "duration": 1.71}, {"text": "and then there were the\nones who didn't, right?", "start": 2107.33, "duration": 2.1}, {"text": "I mean, that's what that means.", "start": 2109.43, "duration": 1.482}, {"text": "But I still don't get to\nrefer to the ones who didn't", "start": 2110.912, "duration": 2.208}, {"text": "come to class with \"they.\"", "start": 2113.12, "duration": 1.29}, {"text": "\"They\" has to refer to the\nones who did come to class.", "start": 2114.41, "duration": 2.25}, {"text": "But in ASL, I get\nto point at them.", "start": 2116.66, "duration": 3.12}, {"text": "And so I get to refer\nto them right away.", "start": 2119.78, "duration": 2.08}, {"text": "Joseph?", "start": 2121.86, "duration": 1.38}, {"text": "AUDIENCE: So the \"Most of\nmy students came to class.\"", "start": 2123.24, "duration": 3.14}, {"text": "NORVIN RICHARDS: Yeah.", "start": 2126.38, "duration": 1.66}, {"text": "AUDIENCE: Because [INAUDIBLE]\nthe quantifier \"most,\"", "start": 2128.04, "duration": 3.585}, {"text": "you're describing a subset.", "start": 2131.625, "duration": 1.785}, {"text": "But doesn't it\nconservatively mean you", "start": 2133.41, "duration": 1.95}, {"text": "get to ignore the [INAUDIBLE]?", "start": 2135.36, "duration": 2.77}, {"text": "NORVIN RICHARDS: So if\nwe didn't know about ASL,", "start": 2138.13, "duration": 2.0}, {"text": "I might have said, why don't I\nget to refer to that other set?", "start": 2140.13, "duration": 4.685}, {"text": "And you might have\nsaid, ah, it's", "start": 2144.815, "duration": 1.375}, {"text": "because of the\nconservativity of \"most.\"", "start": 2146.19, "duration": 1.862}, {"text": "Yeah, that would have been a\npretty plausible thing to say,", "start": 2148.052, "duration": 2.458}, {"text": "and it's maybe even right.", "start": 2150.51, "duration": 2.22}, {"text": "But the fact that in ASL you\ncan refer to them with a pronoun", "start": 2152.73, "duration": 3.0}, {"text": "suggests that\nmaybe it's actually", "start": 2155.73, "duration": 1.86}, {"text": "something else going on.", "start": 2157.59, "duration": 1.135}, {"text": "There's all kinds of stuff\nlike this in spoken languages,", "start": 2158.725, "duration": 2.375}, {"text": "by the way.", "start": 2161.1, "duration": 0.37}, {"text": "It's not just about modifiers.", "start": 2161.47, "duration": 1.25}, {"text": "And so like-- old observation--", "start": 2162.72, "duration": 2.91}, {"text": "if I say, John has a\nchild; she's five--", "start": 2165.63, "duration": 5.94}, {"text": "that's fine.", "start": 2171.57, "duration": 1.02}, {"text": "And \"she,\" you\nprobably figure it's", "start": 2172.59, "duration": 1.56}, {"text": "the child I'm talking about.", "start": 2174.15, "duration": 1.62}, {"text": "If I say, \"John\nis a parent; she's", "start": 2175.77, "duration": 3.15}, {"text": "five,\" that's a weird\nthing for me to say,", "start": 2178.92, "duration": 4.0}, {"text": "even though by saying,\n\"John is a parent,\"", "start": 2182.92, "duration": 1.95}, {"text": "I'm telling you that\nJohn has a child, right?", "start": 2184.87, "duration": 2.01}, {"text": "That's what that means,\nbut it doesn't help.", "start": 2186.88, "duration": 2.31}, {"text": "[LAUGHS] So we're limited\nin how we can use pronouns.", "start": 2189.19, "duration": 4.15}, {"text": "I'm sorry.", "start": 2193.34, "duration": 0.5}, {"text": "You had a point\nyou wanted to make.", "start": 2193.84, "duration": 1.552}, {"text": "AUDIENCE: Is there\nany finer distinction,", "start": 2195.392, "duration": 1.708}, {"text": "like with [INAUDIBLE] say, I\nget most of my students who", "start": 2197.1, "duration": 3.6}, {"text": "don't come to class because--", "start": 2200.7, "duration": 1.82}, {"text": "NORVIN RICHARDS: I\nbelieve you can, then,", "start": 2202.52, "duration": 1.74}, {"text": "draw subparts of these.", "start": 2204.26, "duration": 1.96}, {"text": "I'll put that paper\non the website, too.", "start": 2206.22, "duration": 1.97}, {"text": "You can--", "start": 2208.19, "duration": 0.54}, {"text": "AUDIENCE: [INAUDIBLE].", "start": 2208.73, "duration": 0.48}, {"text": "NORVIN RICHARDS: Yeah,\nthere's all kinds of stuff", "start": 2209.21, "duration": 1.29}, {"text": "that you can do with space.", "start": 2210.5, "duration": 1.143}, {"text": "Again, I don't know what\nthe limits of it are,", "start": 2211.643, "duration": 1.917}, {"text": "but it would be really\ninteresting to find out.", "start": 2213.56, "duration": 1.958}, {"text": "Yeah, they can do more\nreferring to sets and subsets", "start": 2215.518, "duration": 2.424}, {"text": "than we can do because they\nhave the advantage that they've", "start": 2217.942, "duration": 2.458}, {"text": "got a blackboard.", "start": 2220.4, "duration": 2.01}, {"text": "They get to point out\nwhere everything is.", "start": 2222.41, "duration": 2.63}, {"text": "Yeah?", "start": 2225.04, "duration": 0.5}, {"text": "AUDIENCE: OK, so\nthat seems pretty", "start": 2225.54, "duration": 2.06}, {"text": "different from spoken English.", "start": 2227.6, "duration": 1.603}, {"text": "NORVIN RICHARDS: Yeah.", "start": 2229.203, "duration": 0.917}, {"text": "AUDIENCE: [INAUDIBLE] shapes\nthat individual's perception", "start": 2230.12, "duration": 3.298}, {"text": "of the world into\ncertain [INAUDIBLE]..", "start": 2233.418, "duration": 2.172}, {"text": "But is their written form of\ncommunication very different", "start": 2235.59, "duration": 4.21}, {"text": "from a non-deaf individual's?", "start": 2239.8, "duration": 1.44}, {"text": "Or are they similar?", "start": 2241.24, "duration": 0.98}, {"text": "NORVIN RICHARDS: Oh, OK.", "start": 2242.22, "duration": 1.0}, {"text": "So there have been\nvarious attempts", "start": 2243.22, "duration": 1.5}, {"text": "to come up with writing systems\nthat are indigenous to ASL,", "start": 2244.72, "duration": 3.57}, {"text": "and I don't think\nany of them have", "start": 2248.29, "duration": 1.5}, {"text": "gained a lot of popularity.", "start": 2249.79, "duration": 3.79}, {"text": "So when linguists are\nwriting papers about ASL,", "start": 2253.58, "duration": 5.51}, {"text": "what they typically do is--", "start": 2259.09, "duration": 1.303}, {"text": "I mean, I did a parody\nof it over here--", "start": 2260.393, "duration": 1.667}, {"text": "that if you want to write an\nexample sentence that's like,", "start": 2262.06, "duration": 3.33}, {"text": "\"I saw a tree,\" for \"tree,\"\nyou're going to write--", "start": 2265.39, "duration": 3.12}, {"text": "for this sign, you're going\nto write the English word", "start": 2268.51, "duration": 3.45}, {"text": "\"tree\" in all capital letters.", "start": 2271.96, "duration": 1.38}, {"text": "So you use all capital letters\nto indicate that you're", "start": 2273.34, "duration": 2.25}, {"text": "talking about signs.", "start": 2275.59, "duration": 2.16}, {"text": "And then, they'll\nannotate these,", "start": 2277.75, "duration": 1.59}, {"text": "if you're interested\nin indicating things", "start": 2279.34, "duration": 2.61}, {"text": "about facial position,\nand facial expression,", "start": 2281.95, "duration": 2.26}, {"text": "and things like\nthat, there are ways", "start": 2284.21, "duration": 1.5}, {"text": "of annotating that\nto show you're", "start": 2285.71, "duration": 1.4}, {"text": "doing the wh- facial\nexpression or whatever.", "start": 2287.11, "duration": 3.39}, {"text": "As far as actual\nASL speakers go,", "start": 2290.5, "duration": 2.92}, {"text": "my understanding is that they\ntypically don't write in ASL.", "start": 2293.42, "duration": 3.8}, {"text": "So dictionaries, you can find\ndictionaries of ASL online.", "start": 2297.22, "duration": 3.39}, {"text": "They have lots of\nvideos, or they'll", "start": 2300.61, "duration": 2.34}, {"text": "have pictures of one\nframe after another of--", "start": 2302.95, "duration": 4.37}, {"text": "so there isn't-- literacy among\nthe deaf is apparently a really", "start": 2307.32, "duration": 4.69}, {"text": "serious problem, as you\nmight imagine, right?", "start": 2312.01, "duration": 2.13}, {"text": "So somebody who's\nprofoundly deaf,", "start": 2314.14, "duration": 1.89}, {"text": "who hasn't heard a sound--", "start": 2316.03, "duration": 4.13}, {"text": "learning to spell if you\ncan hear is hard enough.", "start": 2320.16, "duration": 4.21}, {"text": "Learning to spell if all of the\nsymbols that you're being asked", "start": 2324.37, "duration": 4.86}, {"text": "to write just don't represent\nanything for you at all,", "start": 2329.23, "duration": 4.29}, {"text": "it's going to be a nightmare.", "start": 2333.52, "duration": 1.3}, {"text": "And so although ASL\nnative signers typically", "start": 2334.82, "duration": 4.58}, {"text": "write in English, it's\napparently very hard,", "start": 2339.4, "duration": 2.665}, {"text": "as you might imagine.", "start": 2342.065, "duration": 0.875}, {"text": "Yeah.", "start": 2342.94, "duration": 1.77}, {"text": "Yeah?", "start": 2344.71, "duration": 1.48}, {"text": "Points about this?", "start": 2346.19, "duration": 1.86}, {"text": "OK.", "start": 2348.05, "duration": 0.5}, {"text": "Oh, OK, so yeah,\nthis has all been", "start": 2353.05, "duration": 2.04}, {"text": "about space and other\nthings to do with your body.", "start": 2355.09, "duration": 2.23}, {"text": "I wanted to show\nyou one other video.", "start": 2357.32, "duration": 3.63}, {"text": "So there's another phenomenon\nthat people use when they are", "start": 2360.95, "duration": 3.05}, {"text": "telling stories or talking\nabout multiple people,", "start": 2364.0, "duration": 3.123}, {"text": "which is what's\ncalled \"role shift\"--", "start": 2367.123, "duration": 1.542}, {"text": "that's what people who\nwork on it call it--", "start": 2368.665, "duration": 2.145}, {"text": "where you'll shift your body.", "start": 2370.81, "duration": 1.86}, {"text": "People do this in\nspoken language,", "start": 2372.67, "duration": 1.737}, {"text": "too, but again, in ASL,\nit's apparently more", "start": 2374.407, "duration": 1.833}, {"text": "or less obligatory.", "start": 2376.24, "duration": 0.99}, {"text": "You'll shift your\nbody to represent", "start": 2377.23, "duration": 1.92}, {"text": "the different characters\nthat you're talking about.", "start": 2379.15, "duration": 3.78}, {"text": "And I'll show you a story\nwhere somebody does this.", "start": 2382.93, "duration": 4.68}, {"text": "It is a story about\nthrowing a stick for a dog,", "start": 2387.61, "duration": 2.25}, {"text": "and one of the nice\nthings about it", "start": 2389.86, "duration": 2.28}, {"text": "is that there's no\nneed at all to explain", "start": 2392.14, "duration": 1.74}, {"text": "what the guy is talking about.", "start": 2393.88, "duration": 2.3}, {"text": "Maybe at the beginning\na little bit.", "start": 2396.18, "duration": 1.5}, {"text": "He's going for a\nwalk with his dog.", "start": 2397.68, "duration": 2.19}, {"text": "No, stop that!", "start": 2403.22, "duration": 1.1}, {"text": "OK, so there's his dog, right?", "start": 2411.93, "duration": 2.1}, {"text": "[LAUGHS] And there's him.", "start": 2414.03, "duration": 1.95}, {"text": "[LAUGHS] Yeah, so\nhe's doing role shift.", "start": 2415.98, "duration": 2.25}, {"text": "He's going to get a stick.", "start": 2418.23, "duration": 1.82}, {"text": "Yeah, and there's the dog again.", "start": 2420.05, "duration": 3.043}, {"text": "The dog's all excited.", "start": 2423.093, "duration": 0.917}, {"text": "There's the guy.", "start": 2424.01, "duration": 0.667}, {"text": "He throws the stick.", "start": 2424.677, "duration": 2.363}, {"text": "Phew, clunk.", "start": 2427.04, "duration": 3.42}, {"text": "And here comes the dog.", "start": 2430.46, "duration": 1.59}, {"text": "And so--", "start": 2432.05, "duration": 0.72}, {"text": "[LAUGHTER]", "start": 2432.77, "duration": 3.114}, {"text": "I'm showing this to you partly\nbecause it's a cute story--", "start": 2438.853, "duration": 2.417}, {"text": "\"Thank you,\" he says.", "start": 2441.27, "duration": 2.305}, {"text": "I'm showing that to you partly\nbecause it's a cute story,", "start": 2443.575, "duration": 2.375}, {"text": "but also because it's a\ngood example of role shift.", "start": 2445.95, "duration": 2.125}, {"text": "So he's-- oh, there's\nClayton Valli again--", "start": 2448.075, "duration": 2.175}, {"text": "a good example of role shift.", "start": 2450.25, "duration": 1.34}, {"text": "So he's using his body to go\nback and forth between being", "start": 2451.59, "duration": 2.82}, {"text": "the dog and being the person.", "start": 2454.41, "duration": 1.23}, {"text": "And apparently, this\nis a standard thing", "start": 2455.64, "duration": 1.667}, {"text": "that you do if you do ASL, if\nyou're a native speaker of ASL.", "start": 2457.307, "duration": 4.183}, {"text": "It's part of being a fluent\nsigner as opposed to being", "start": 2461.49, "duration": 2.64}, {"text": "someone who knows a bit of ASL.", "start": 2464.13, "duration": 1.62}, {"text": "Full screen mode,\nthat's what I want.", "start": 2469.068, "duration": 1.542}, {"text": "OK.", "start": 2473.322, "duration": 0.908}, {"text": "So this was what I wanted to\ntry to show you about ASL.", "start": 2474.23, "duration": 5.17}, {"text": "So just to review, ASL, American\nSign Language, it's a language.", "start": 2479.4, "duration": 5.1}, {"text": "It's a language spoken here in\nAmerica by many deaf people.", "start": 2484.5, "duration": 4.42}, {"text": "It is not English.", "start": 2488.92, "duration": 1.91}, {"text": "It's not any form of English.", "start": 2490.83, "duration": 1.59}, {"text": "It's not charades, and\nit's not English with all", "start": 2492.42, "duration": 2.64}, {"text": "of the words replaced\nby signs, which is what", "start": 2495.06, "duration": 2.19}, {"text": "I believed when I was a kid.", "start": 2497.25, "duration": 2.555}, {"text": "It's a language that's\nquite different from English", "start": 2499.805, "duration": 2.125}, {"text": "in various ways, as\nI've tried to show you.", "start": 2501.93, "duration": 3.72}, {"text": "There's a lot of\ninteresting work on ASL.", "start": 2505.65, "duration": 3.06}, {"text": "A lot of it is on ASL phonology,\nwhere by \"phonology,\" we", "start": 2508.71, "duration": 3.51}, {"text": "mean what we always meant\nby phonology, I guess,", "start": 2512.22, "duration": 2.79}, {"text": "which is the rules for how\nthe articulations work.", "start": 2515.01, "duration": 3.12}, {"text": "So phonology up\nuntil now has all", "start": 2518.13, "duration": 3.3}, {"text": "been about what you're\ndoing with your vocal tract", "start": 2521.43, "duration": 2.44}, {"text": "and what the rules are for what\nyour vocal tract is allowed", "start": 2523.87, "duration": 2.458}, {"text": "to do here or there in a word.", "start": 2526.328, "duration": 3.052}, {"text": "There is an ASL\nversion of this where", "start": 2529.38, "duration": 2.13}, {"text": "people try to understand what\nare the various articulations", "start": 2531.51, "duration": 3.0}, {"text": "your fingers, your hands, your\nwrists, the rest of your body,", "start": 2534.51, "duration": 4.53}, {"text": "what are those\nparts of you allowed", "start": 2539.04, "duration": 1.83}, {"text": "to do at different\npoints in the sign?", "start": 2540.87, "duration": 3.48}, {"text": "And then, as I\nsaid, there's a lot", "start": 2544.35, "duration": 1.53}, {"text": "of interest in the use\nof parts of your body", "start": 2545.88, "duration": 1.65}, {"text": "other than your hands.", "start": 2547.53, "duration": 0.917}, {"text": "Lots of work on facial\nexpression and on role shift,", "start": 2548.447, "duration": 2.233}, {"text": "shifting your shifting\nyour body back and forth.", "start": 2550.68, "duration": 2.52}, {"text": "And that's what I wanted\nto tell you about ASL.", "start": 2553.2, "duration": 3.02}, {"text": "Any questions about any of that?", "start": 2556.22, "duration": 3.58}, {"text": "Then we are done.", "start": 2559.8, "duration": 1.11}, {"text": "You officially know\neverything about 24.900.", "start": 2560.91, "duration": 2.7}, {"text": "So 24.900, you know\neverything about linguistics.", "start": 2563.61, "duration": 2.17}, {"text": "[LAUGHTER]", "start": 2565.78, "duration": 0.5}, {"text": "No, actually, that's false.", "start": 2566.28, "duration": 2.17}, {"text": "But one of the main\ngoals of this class--", "start": 2568.45, "duration": 2.485}, {"text": "this class has\nhad several goals,", "start": 2570.935, "duration": 1.375}, {"text": "but one of the main\ngoals of this class", "start": 2572.31, "duration": 1.625}, {"text": "has been to convince\nyou that there", "start": 2573.935, "duration": 1.705}, {"text": "are some interesting mysteries\nhaving to do with how language", "start": 2575.64, "duration": 3.42}, {"text": "works and that, if you take\nmore linguistics classes,", "start": 2579.06, "duration": 3.182}, {"text": "you might get to learn more\nabout how those mysteries work.", "start": 2582.242, "duration": 2.458}, {"text": "If you take even more\nlinguistics classes,", "start": 2584.7, "duration": 1.83}, {"text": "then you could be the person\nwho solves these mysteries", "start": 2586.53, "duration": 2.61}, {"text": "for the rest of us,\nwhich would be great.", "start": 2589.14, "duration": 2.24}, {"text": "One of the nice things\nabout linguistics--", "start": 2591.38, "duration": 1.75}, {"text": "I think I've said this before--", "start": 2593.13, "duration": 1.38}, {"text": "it's a field that's\nbeen around for a while.", "start": 2594.51, "duration": 2.52}, {"text": "We have some results.", "start": 2597.03, "duration": 1.27}, {"text": "But it's not all that hard,\neven in an intro class,", "start": 2598.3, "duration": 2.57}, {"text": "to bring you right up to the\nedge of what we understand", "start": 2600.87, "duration": 3.18}, {"text": "and invite you to look down into\nthe abyss and ask yourself how", "start": 2604.05, "duration": 3.72}, {"text": "you could build a bridge-- this\nmetaphor is getting away from", "start": 2607.77, "duration": 2.58}, {"text": "me--", "start": 2610.35, "duration": 1.35}, {"text": "how you could move\nfurther, how you", "start": 2611.7, "duration": 1.86}, {"text": "could get further\nfrom where we are.", "start": 2613.56, "duration": 1.902}, {"text": "So I hope that at\nleast some of you", "start": 2615.462, "duration": 1.458}, {"text": "will be inspired to want to\ndo that because we need people", "start": 2616.92, "duration": 2.7}, {"text": "to go out there and\nsolve the mysteries that", "start": 2619.62, "duration": 2.01}, {"text": "haven't been solved.", "start": 2621.63, "duration": 1.8}, {"text": "Questions about any of that?", "start": 2623.43, "duration": 3.162}, {"text": "All right, then, we are done.", "start": 2626.592, "duration": 1.208}, {"text": "Go forth.", "start": 2627.8, "duration": 1.17}, {"text": "Do your class evaluations.", "start": 2628.97, "duration": 1.558}, {"text": "So we're ending early, so\nyou'll have a good half", "start": 2630.528, "duration": 2.042}, {"text": "hour to think hard about what\nyou want to write in your class", "start": 2632.57, "duration": 3.15}, {"text": "evaluations.", "start": 2635.72, "duration": 0.81}, {"text": "And thanks very much.", "start": 2636.53, "duration": 3.132}, {"text": "[APPLAUSE]", "start": 2639.662, "duration": 1.678}, {"text": "Thank you.", "start": 2641.34, "duration": 0.5}, {"text": "Thank you, thank you.", "start": 2645.645, "duration": 0.875}, {"text": "Go out and enjoy the day.", "start": 2646.52, "duration": 2.39}]

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+[{"text": "How is everyone doing today?", "start": 17.5, "duration": 2.002}, {"text": "[CHEERING]", "start": 19.502, "duration": 2.769}, {"text": "You know why there's\na lot of excitement,", "start": 22.271, "duration": 1.702}, {"text": "and I saw the silent\npraise, because I", "start": 23.973, "duration": 2.135}, {"text": "know what this means, recently,\nand I'm doing more and more.", "start": 26.108, "duration": 5.205}, {"text": "You guys are excited, because\nwe are celebrating something", "start": 31.313, "duration": 3.204}, {"text": "on Friday.", "start": 34.517, "duration": 1.101}, {"text": "We are celebrating knowledge,\nwe are celebrating chemistry,", "start": 35.618, "duration": 6.339}, {"text": "and we are celebrating\nhow much we've", "start": 41.957, "duration": 3.537}, {"text": "learned in the last month.", "start": 45.494, "duration": 1.335}, {"text": "It's called exam three.", "start": 46.829, "duration": 1.668}, {"text": "Woo.", "start": 48.497, "duration": 0.734}, {"text": "It's a midterm.", "start": 49.231, "duration": 1.368}, {"text": "Thank you for that.", "start": 50.599, "duration": 0.935}, {"text": "What I thought we'd\ndo today instead of--", "start": 58.574, "duration": 2.769}, {"text": "again, I mentioned\nthis on Monday.", "start": 61.343, "duration": 3.304}, {"text": "You guys just had\nThanksgiving, you're back,", "start": 64.647, "duration": 3.603}, {"text": "and now we've got a test.", "start": 68.25, "duration": 1.402}, {"text": "And I know you've got a\nlot of other stuff going on", "start": 69.652, "duration": 2.102}, {"text": "too at this time.", "start": 71.754, "duration": 0.767}, {"text": "So instead of throwing\nsomething in that we're not", "start": 72.521, "duration": 2.102}, {"text": "going to test you on, what\nI wanted to do with today", "start": 74.623, "duration": 2.569}, {"text": "was just to kind of feel our\noneness with the concepts.", "start": 77.192, "duration": 4.704}, {"text": "All right?", "start": 81.896, "duration": 0.935}, {"text": "And so I want to go\nover the concepts that", "start": 82.831, "duration": 3.17}, {"text": "are going to be potentially\non the exam on Friday,", "start": 86.001, "duration": 5.306}, {"text": "and I'll talk about\nthose concepts,", "start": 91.307, "duration": 2.235}, {"text": "and we'll do a\ncouple of problems", "start": 93.542, "duration": 1.368}, {"text": "here and there as we go.", "start": 94.91, "duration": 1.635}, {"text": "OK, so those are the metrics,\nthe specs, for exam three.", "start": 96.545, "duration": 5.571}, {"text": "But on Monday, I finished\nwith two minutes left,", "start": 106.221, "duration": 3.671}, {"text": "and I said, hey,\nthere's one more", "start": 109.892, "duration": 1.367}, {"text": "kind of acid-base definition.", "start": 111.259, "duration": 1.736}, {"text": "You won't be tested on it,\nbut it's the most general,", "start": 112.995, "duration": 2.202}, {"text": "and I've got to\ngive Lewis his due.", "start": 115.197, "duration": 1.835}, {"text": "So I just wanted to\njust show you like that.", "start": 117.032, "duration": 2.937}, {"text": "You won't be tested on\nLewis acids and bases,", "start": 119.969, "duration": 2.969}, {"text": "but I did throw this\nin there, and so", "start": 122.938, "duration": 2.67}, {"text": "I want to just, for one or two\nmore minutes, talk about this.", "start": 125.608, "duration": 3.603}, {"text": "Right?", "start": 129.211, "duration": 0.5}, {"text": "These are the things you\nare responsible for knowing.", "start": 129.711, "duration": 2.203}, {"text": "So an Arrhenius acid-base--", "start": 131.914, "duration": 1.768}, {"text": "OH, H plus.", "start": 133.682, "duration": 1.101}, {"text": "Bronsted-Lowry.", "start": 134.783, "duration": 1.969}, {"text": "It's proton transfer.", "start": 136.752, "duration": 2.736}, {"text": "And then there's\nLewis, who broasted", "start": 139.588, "duration": 1.802}, {"text": "these guys, because\nhe said, uh-uh,", "start": 141.39, "duration": 4.571}, {"text": "and this is the most general way\nto think about acids and bases.", "start": 145.961, "duration": 4.238}, {"text": "It is the most general.", "start": 150.199, "duration": 1.201}, {"text": "It is quite powerful, because\nyou go back to say this one,", "start": 151.4, "duration": 8.275}, {"text": "and so if this is a--", "start": 159.675, "duration": 3.136}, {"text": "what if we mix this with this?", "start": 162.811, "duration": 4.004}, {"text": "So here we have H.", "start": 166.815, "duration": 2.236}, {"text": "Now, remember, Lewis had all\nthe dots all over the place.", "start": 169.051, "duration": 2.903}, {"text": "He loved dots, and so\nthey're all over the place.", "start": 171.954, "duration": 3.47}, {"text": "And that's what if you had\nthis, this is a Lewis acid,", "start": 175.424, "duration": 4.771}, {"text": "because it is ready to receive.", "start": 180.195, "duration": 4.538}, {"text": "What is it ready to receive?", "start": 184.733, "duration": 1.702}, {"text": "No more atoms, only electrons.", "start": 186.435, "duration": 3.07}, {"text": "It is the most general\nway to think about it.", "start": 189.505, "duration": 3.136}, {"text": "All right?", "start": 192.641, "duration": 1.101}, {"text": "And this would be a\nLewis base, because it", "start": 193.742, "duration": 3.504}, {"text": "is ready to give a\npair of electrons", "start": 197.246, "duration": 4.104}, {"text": "and form a bond together.", "start": 201.35, "duration": 1.501}, {"text": "And that's what they do,\nor that's what they can do.", "start": 202.851, "duration": 3.737}, {"text": "So a Lewis acid and a Lewis\nbase is the most general form,", "start": 206.588, "duration": 4.705}, {"text": "and you really get rid of--", "start": 211.293, "duration": 1.502}, {"text": "so for Lewis, it's all\nabout electron transfer,", "start": 212.795, "duration": 4.471}, {"text": "electron pair transfer, pair\ntransfer, or bonds if you're--", "start": 217.266, "duration": 5.938}, {"text": "I'm just going to make it\nas general as possible.", "start": 223.204, "duration": 2.77}, {"text": "If you're going to mix\nan acid and a base,", "start": 225.974, "duration": 1.936}, {"text": "which I'll do in a\nsecond, it's a pair.", "start": 227.91, "duration": 2.869}, {"text": "Electron transfer is\nwhat it's all about,", "start": 230.779, "duration": 3.871}, {"text": "and what happens here?", "start": 234.65, "duration": 2.569}, {"text": "Well, you don't have\nany chemical identity,", "start": 237.219, "duration": 3.337}, {"text": "no more chemical identity.", "start": 240.556, "duration": 1.935}, {"text": "So it's full.", "start": 245.861, "duration": 0.734}, {"text": "You don't need the\nhydrogens anymore.", "start": 246.595, "duration": 1.568}, {"text": "You don't need the OH's.", "start": 248.163, "duration": 1.735}, {"text": "It's totally general.", "start": 249.898, "duration": 1.869}, {"text": "And this really opens\nit up, because now you", "start": 251.767, "duration": 2.336}, {"text": "can look at gases, liquid,\nsolids, all forms of matter,", "start": 254.103, "duration": 3.103}, {"text": "all elements in the table, and\nyou can think about them as", "start": 257.206, "duration": 2.435}, {"text": "whether they're going\nto have an acid-like", "start": 259.641, "duration": 2.169}, {"text": "or a base-like character in\nterms of electron transfer.", "start": 261.81, "duration": 2.97}, {"text": "So here's the general-- if you\nhad a Lewis acid and a Lewis", "start": 264.78, "duration": 4.671}, {"text": "base, and you mix them together.", "start": 269.451, "duration": 3.003}, {"text": "Then, you can see that\nif you got an electron", "start": 272.454, "duration": 3.904}, {"text": "pair that could then go--", "start": 276.358, "duration": 1.301}, {"text": "that one of them wants it,\nand the other can give it,", "start": 277.659, "duration": 2.236}, {"text": "and they can form\na bond, then that", "start": 279.895, "duration": 2.569}, {"text": "would be how you think about\nmixing a Lewis acid and a Lewis", "start": 282.464, "duration": 2.803}, {"text": "base.", "start": 285.267, "duration": 0.501}, {"text": "And again, this\nwon't be on the exam,", "start": 285.768, "duration": 3.203}, {"text": "but I just had to\ngive Lewis his due.", "start": 288.971, "duration": 3.736}, {"text": "OK, Lewis acids and bases\nare all about the electrons.", "start": 292.707, "duration": 5.206}, {"text": "And then the other thing I\ndidn't get to do on Monday", "start": 297.913, "duration": 2.202}, {"text": "was my Why This Matters,\nand so I want to do that.", "start": 300.115, "duration": 2.069}, {"text": "Now hair is very much affected\nby the softness of water.", "start": 302.184, "duration": 3.87}, {"text": "But instead of me showing\nyou lots of pictures of hair", "start": 308.891, "duration": 5.038}, {"text": "that I found randomly on the\ninternet, googling soft water,", "start": 313.929, "duration": 5.472}, {"text": "hard water, different\nforms of water, hair,", "start": 319.401, "duration": 4.004}, {"text": "I'm showing you pipes, because\nthat's much more actually", "start": 323.405, "duration": 3.237}, {"text": "relevant in terms of like, for\nexample, whether you can get", "start": 326.642, "duration": 2.469}, {"text": "water into your house at all.", "start": 329.111, "duration": 2.402}, {"text": "All right?", "start": 331.513, "duration": 0.901}, {"text": "And this is a real problem.", "start": 332.414, "duration": 2.736}, {"text": "If you have hard\nwater what it means", "start": 335.15, "duration": 1.835}, {"text": "is you've got\nminerals in the water.", "start": 336.985, "duration": 3.037}, {"text": "Right?", "start": 340.022, "duration": 0.734}, {"text": "Things like magnesium and\ncalcium ions are in the water.", "start": 340.756, "duration": 3.837}, {"text": "And what happens is, if you run\nthat through pipes, they tend", "start": 344.593, "duration": 3.937}, {"text": "to react and form and deposit.", "start": 348.53, "duration": 4.071}, {"text": "And you get these deposits\nof very, very hard mineral", "start": 352.601, "duration": 2.569}, {"text": "deposits around the edges that\neventually look like this.", "start": 355.17, "duration": 3.203}, {"text": "That's not a good thing.", "start": 358.373, "duration": 1.702}, {"text": "And so you need to soften the\nwater, and that's something", "start": 360.075, "duration": 3.537}, {"text": "you may have heard of.", "start": 363.612, "duration": 1.501}, {"text": "But now you really know how\nto think about it, because you", "start": 365.113, "duration": 2.403}, {"text": "can think about it in\nterms of all of the things", "start": 367.516, "duration": 2.069}, {"text": "that you've learned.", "start": 369.585, "duration": 2.469}, {"text": "And just as an example,\nif one of those minerals", "start": 372.054, "duration": 4.538}, {"text": "that's a problem is calcium--", "start": 376.592, "duration": 2.035}, {"text": "oh, it is, right?", "start": 378.627, "duration": 1.568}, {"text": "Magnesium is another one\nthat can cause this in pipes.", "start": 380.195, "duration": 5.205}, {"text": "You've got to somehow\ntake it out of the water", "start": 385.4, "duration": 3.571}, {"text": "or at least make it into a form\nthat makes it like insoluble,", "start": 388.971, "duration": 4.871}, {"text": "so it'll just flow, and\nit won't have a chance", "start": 393.842, "duration": 2.469}, {"text": "to come around and deposit on\nthe edge there of the pipe.", "start": 396.311, "duration": 5.306}, {"text": "And so what do you do?", "start": 401.617, "duration": 1.101}, {"text": "Well, you add, for example--", "start": 402.718, "duration": 2.502}, {"text": "oh, we've done this before.", "start": 405.22, "duration": 1.568}, {"text": "Right?", "start": 406.788, "duration": 0.501}, {"text": "What if I add soda,\nsomething called soda ash?", "start": 407.289, "duration": 4.004}, {"text": "Oh, we know what that is.", "start": 411.293, "duration": 1.635}, {"text": "That's Na2CO3, and that\nwill give me some ions.", "start": 412.928, "duration": 8.475}, {"text": "It'll give me some\nNa pluses, and it'll", "start": 421.403, "duration": 2.769}, {"text": "give me some CO3 2 minuses,\nand those are in aqueous.", "start": 424.172, "duration": 5.473}, {"text": "Now, this is all\npart of the stuff", "start": 429.645, "duration": 1.635}, {"text": "that we've been talking about.", "start": 431.28, "duration": 1.234}, {"text": "You're dissociating this\nto get ions in solution,", "start": 432.514, "duration": 2.436}, {"text": "but why do I want these ions?", "start": 434.95, "duration": 3.337}, {"text": "That's a water softener.", "start": 438.287, "duration": 1.735}, {"text": "Why?", "start": 440.022, "duration": 0.567}, {"text": "Because now you can see it.", "start": 440.589, "duration": 1.568}, {"text": "Right?", "start": 442.157, "duration": 0.501}, {"text": "Because this one\nhere, this one here", "start": 442.658, "duration": 3.403}, {"text": "is going to remove the calcium.", "start": 446.061, "duration": 3.437}, {"text": "So if I've got these\ncalcium, these minerals,", "start": 449.498, "duration": 2.369}, {"text": "in the water making it hard\nwater which leads to that", "start": 451.867, "duration": 4.037}, {"text": "and wreaks havoc on\nyour hair, then you", "start": 455.904, "duration": 4.204}, {"text": "get a little of this\nin there, and you're", "start": 460.108, "duration": 1.801}, {"text": "going to react with the calcium.", "start": 461.909, "duration": 1.403}, {"text": "Why?", "start": 463.312, "duration": 0.5}, {"text": "It's because of\nwhat we already saw.", "start": 463.812, "duration": 1.969}, {"text": "If I have this--", "start": 465.781, "duration": 1.968}, {"text": "this is something we've already\nlooked at-- if I have calcium 2", "start": 467.749, "duration": 3.17}, {"text": "plus, and I have some\nbicarbonate in there,", "start": 470.919, "duration": 3.137}, {"text": "CO3 minus, then we know that\nI can get precipitates, Ca--", "start": 474.056, "duration": 6.506}, {"text": "this is just what we looked\nat in the goody bag, right--", "start": 480.562, "duration": 2.503}, {"text": "plus CO2 plus H2O.", "start": 483.065, "duration": 4.404}, {"text": "That's the same kind of reaction\nthat we looked at already.", "start": 487.469, "duration": 3.504}, {"text": "We have calcium carbonate,\ncalcium carbonate.", "start": 490.973, "duration": 3.136}, {"text": "Why?", "start": 494.109, "duration": 0.601}, {"text": "Well, because this is\ngoing to give me these.", "start": 494.71, "duration": 3.536}, {"text": "This is a source for those\nwhich then eats up some calcium.", "start": 498.246, "duration": 5.239}, {"text": "And you think, well, now this\ncan take the calcium ions out,", "start": 503.485, "duration": 4.671}, {"text": "so that it runs through.", "start": 508.156, "duration": 2.369}, {"text": "That's what you want to do here.", "start": 510.525, "duration": 1.634}, {"text": "That's how you soften water.", "start": 512.159, "duration": 2.07}, {"text": "Well, you can add lime which\ngives me a source of OH minus,", "start": 514.229, "duration": 3.871}, {"text": "and that takes\nout the magnesium.", "start": 518.1, "duration": 2.401}, {"text": "And these are ways to change\nthe chemistry of water,", "start": 520.501, "duration": 2.537}, {"text": "so that you don't have\nas many ions, mineral,", "start": 523.038, "duration": 2.97}, {"text": "these calcium and magnesium\nions floating around that cause", "start": 526.008, "duration": 3.336}, {"text": "problems.", "start": 529.344, "duration": 1.368}, {"text": "So that was my Why This\nMatters, and now we", "start": 530.712, "duration": 1.835}, {"text": "turn to what I started\nwith which is exam three.", "start": 532.547, "duration": 3.304}, {"text": "Oh, look at that.", "start": 535.851, "duration": 2.702}, {"text": "I look at that, and\nthat's just happiness.", "start": 538.553, "duration": 3.003}, {"text": "Look at all those topics--", "start": 541.556, "duration": 1.936}, {"text": "X-rays XRD, defects, glasses,\nreaction rates, solubility,", "start": 543.492, "duration": 7.307}, {"text": "aqueous solutions, acids/bases.", "start": 550.799, "duration": 4.538}, {"text": "It's all there.", "start": 555.337, "duration": 1.535}, {"text": "It's all there, and it's all\nthere in you, and if not,", "start": 556.872, "duration": 6.206}, {"text": "you've got two days.", "start": 563.078, "duration": 2.903}, {"text": "So please, make it be there.", "start": 565.981, "duration": 4.337}, {"text": "Let's go through this.", "start": 570.318, "duration": 1.268}, {"text": "Let's go through this.", "start": 571.586, "duration": 0.935}, {"text": "I'm going to go through\nthis topic right there.", "start": 572.521, "duration": 1.935}, {"text": "So I'm going to tell\nyou the concepts that I", "start": 574.456, "duration": 2.035}, {"text": "want to make sure you know.", "start": 576.491, "duration": 1.201}, {"text": "OK, so here's the first one.", "start": 581.096, "duration": 1.168}, {"text": "So it's X-rays, and XRD.", "start": 582.264, "duration": 4.137}, {"text": "So what do I want you to know?", "start": 586.401, "duration": 2.202}, {"text": "Well, for example,\nI want you to know", "start": 588.603, "duration": 2.703}, {"text": "about how you have\ncharacteristic, characteristic,", "start": 591.306, "duration": 6.573}, {"text": "characteristic X-rays,\nand remember this?", "start": 597.879, "duration": 6.54}, {"text": "This comes from\nthose transitions.", "start": 604.419, "duration": 1.802}, {"text": "Right?", "start": 606.221, "duration": 0.5}, {"text": "So you get like the K and the\nL and the M. We say et cetera.", "start": 606.721, "duration": 6.307}, {"text": "We never really did\net cetera, but we've", "start": 613.028, "duration": 2.235}, {"text": "got a lot of K and L lines\nwe looked at, alpha, beta,", "start": 615.263, "duration": 7.541}, {"text": "but there's also the continuous.", "start": 622.804, "duration": 1.969}, {"text": "Right?", "start": 624.773, "duration": 0.5}, {"text": "So this was in--", "start": 625.273, "duration": 1.168}, {"text": "if you want-- this would be in\nthe topic of X-ray generation,", "start": 626.441, "duration": 4.571}, {"text": "and there's that Bremsstrahlung\nword that means breaking.", "start": 631.012, "duration": 9.243}, {"text": "Right?", "start": 640.255, "duration": 2.236}, {"text": "So if you just want\nto look at this,", "start": 642.491, "duration": 3.136}, {"text": "you might have a\ncurve that looks--", "start": 645.627, "duration": 2.436}, {"text": "OK, so we had things like this.", "start": 648.063, "duration": 1.501}, {"text": "Right?", "start": 649.564, "duration": 0.801}, {"text": "Oh, I'm going to try to\nmake it not look too bad,", "start": 650.365, "duration": 5.939}, {"text": "and there's another\none, and so on.", "start": 656.304, "duration": 3.938}, {"text": "And remember, so this would\nbe like intensity, intensity,", "start": 660.242, "duration": 6.573}, {"text": "and this would be like maybe a\nlambda going that way or maybe", "start": 666.815, "duration": 5.405}, {"text": "energy going that\nway or frequency.", "start": 672.22, "duration": 3.704}, {"text": "Right?", "start": 675.924, "duration": 0.5}, {"text": "Those would be like the x-axis,\nand these are those lines.", "start": 676.424, "duration": 5.306}, {"text": "Those are the lines, and they\ncome from the transitions", "start": 681.73, "duration": 3.069}, {"text": "that you get from like\nthe K level to the L level", "start": 684.799, "duration": 4.105}, {"text": "to the M level.", "start": 688.904, "duration": 0.9}, {"text": "Right?", "start": 689.804, "duration": 0.501}, {"text": "Remember, if you get the energy\nhigh enough of an incident", "start": 690.305, "duration": 5.606}, {"text": "electron onto a\ntarget, metal, then you", "start": 695.911, "duration": 6.006}, {"text": "can knock out electrons\nfrom that 1s shell.", "start": 701.917, "duration": 3.703}, {"text": "And then something\ncascades down,", "start": 705.62, "duration": 1.702}, {"text": "and that emits these lines here.", "start": 707.322, "duration": 1.935}, {"text": "So that'd be like K alpha,\nK alpha, K beta, et cetera.", "start": 709.257, "duration": 5.105}, {"text": "But then, you also,\neven at lower energies,", "start": 714.362, "duration": 2.837}, {"text": "even if you don't\nhave enough energy", "start": 717.199, "duration": 1.468}, {"text": "to knock out a 1s\nelectron, you still", "start": 718.667, "duration": 2.736}, {"text": "can slow an electron down as\nit goes through a metal atom.", "start": 721.403, "duration": 3.703}, {"text": "And that's where you get\nthis continuous spectrum", "start": 725.106, "duration": 3.737}, {"text": "and that limit of how much of\nthat type of X-ray you get.", "start": 728.843, "duration": 4.538}, {"text": "And it just depends\non the incident,", "start": 733.381, "duration": 2.403}, {"text": "on the voltage, on the\nmaximum incident electron", "start": 735.784, "duration": 3.537}, {"text": "you fire at it.", "start": 739.321, "duration": 0.634}, {"text": "So that's those\nfirst two topics.", "start": 739.955, "duration": 2.269}, {"text": "OK?", "start": 742.224, "duration": 2.202}, {"text": "Well, oh, we also did\nX-ray diffraction.", "start": 744.426, "duration": 5.172}, {"text": "Oh, that's fun, diffraction.", "start": 749.598, "duration": 3.903}, {"text": "OK, and this involves\nunderstanding Bragg,", "start": 753.501, "duration": 4.638}, {"text": "the Bragg condition, and\nalso selection rules.", "start": 758.139, "duration": 5.372}, {"text": "So let's just take a look at\nan example of the diffraction", "start": 767.549, "duration": 4.938}, {"text": "and selection rules.", "start": 772.487, "duration": 0.834}, {"text": "OK?", "start": 773.321, "duration": 0.501}, {"text": "So what would I want?", "start": 773.822, "duration": 1.234}, {"text": "So these are like\nthe kind of concepts", "start": 775.056, "duration": 1.769}, {"text": "that I want you to know about.", "start": 776.825, "duration": 2.502}, {"text": "How might it play out?", "start": 779.327, "duration": 0.968}, {"text": "So like, OK, so here's like\nan example of a spectrum.", "start": 780.295, "duration": 5.339}, {"text": "Now, that's an X-ray spectrum\nfor MgFeO4, magnesium ferrite,", "start": 785.634, "duration": 7.607}, {"text": "and it's a kind of steel.", "start": 793.241, "duration": 3.103}, {"text": "And you put it in, you\nmake a powder of it,", "start": 796.344, "duration": 1.769}, {"text": "and and you throw\nsome X-rays on it.", "start": 798.113, "duration": 2.269}, {"text": "Oh no, you throw just\none type of X-ray on it.", "start": 800.382, "duration": 3.837}, {"text": "All right?", "start": 804.219, "duration": 0.5}, {"text": "So for these X-ray\nspectra, what happened?", "start": 804.719, "duration": 2.102}, {"text": "I threw some K alpha on it,\nI showed right there, you", "start": 806.821, "duration": 3.504}, {"text": "got to say what you got.", "start": 810.325, "duration": 1.935}, {"text": "All right?", "start": 812.26, "duration": 1.135}, {"text": "You've got to know at\nleast the source of X-rays", "start": 813.395, "duration": 3.003}, {"text": "has this wavelength.", "start": 816.398, "duration": 2.469}, {"text": "Good.", "start": 818.867, "duration": 1.067}, {"text": "And if I have that\nspectrum, and say,", "start": 819.934, "duration": 1.802}, {"text": "what's the lattice constant?", "start": 821.736, "duration": 2.836}, {"text": "What's the structure?", "start": 824.572, "duration": 1.168}, {"text": "I can get that.", "start": 825.74, "duration": 1.569}, {"text": "How would I get that?", "start": 827.309, "duration": 0.867}, {"text": "How would I get that?", "start": 828.176, "duration": 0.868}, {"text": "So I would take this\nspectrum, and notice something", "start": 829.044, "duration": 5.705}, {"text": "is very much pointed out to\nme, a peak and a number, 35.5.", "start": 834.749, "duration": 5.139}, {"text": "Right?", "start": 839.888, "duration": 0.5}, {"text": "That's the 2 theta\nvalue for the 311 peak.", "start": 840.388, "duration": 4.204}, {"text": "Well, I think I'll\ntake that as a hint.", "start": 844.592, "duration": 2.103}, {"text": "Maybe I should think about that\nnumber, and OK, so let's see.", "start": 846.695, "duration": 3.503}, {"text": "From Bragg, so from\nBragg, you know", "start": 850.198, "duration": 4.905}, {"text": "that you got n lambda\nequals 2d sine theta,", "start": 855.103, "duration": 8.675}, {"text": "and remember that had to do with\nconstructive and destructive", "start": 863.778, "duration": 3.103}, {"text": "interference of waves, the\nwaves being the X-rays.", "start": 866.881, "duration": 3.037}, {"text": "And then we said, well, n is 1\nin our class, so that's just 1", "start": 869.918, "duration": 5.105}, {"text": "in 3,091.", "start": 875.023, "duration": 0.734}, {"text": "It doesn't have to be.", "start": 875.757, "duration": 1.201}, {"text": "You could have interference\noff of two planes down,", "start": 876.958, "duration": 3.07}, {"text": "three planes down,\nbut in this class,", "start": 880.028, "duration": 1.535}, {"text": "we're just doing the two\nplanes next to each other.", "start": 881.563, "duration": 2.135}, {"text": "So n is 1.", "start": 883.698, "duration": 1.135}, {"text": "OK?", "start": 884.833, "duration": 1.468}, {"text": "Now, I'll take that angle, and\nI'll round it to 18 degrees.", "start": 886.301, "duration": 3.837}, {"text": "So I'm going to say for theta\nequals 18 degrees, then--", "start": 890.138, "duration": 6.073}, {"text": "oh, wait, why is it 18?", "start": 896.211, "duration": 2.936}, {"text": "Because that's 2 theta.", "start": 899.147, "duration": 1.802}, {"text": "Right?", "start": 900.949, "duration": 0.5}, {"text": "Because remember, we\ntake spectra in 2 theta,", "start": 901.449, "duration": 2.569}, {"text": "but the theta in\nBragg is 1 theta.", "start": 904.018, "duration": 2.336}, {"text": "OK, that wasn't too hard.", "start": 906.354, "duration": 2.903}, {"text": "But now, I've got, let's see,\nsine theta is around 0.3,", "start": 909.257, "duration": 7.174}, {"text": "and oh, I got lambda.", "start": 916.431, "duration": 3.303}, {"text": "Lambda equals 1.54 nanometers,\nand so I can actually", "start": 919.734, "duration": 7.274}, {"text": "plug in now.", "start": 927.008, "duration": 2.002}, {"text": "I didn't even need the peak.", "start": 929.01, "duration": 2.002}, {"text": "I'm just plugging in the Bragg\ncondition, and I've got d.", "start": 931.012, "duration": 6.373}, {"text": "d equals 2.52\nAngstroms, so I'm done.", "start": 937.385, "duration": 5.939}, {"text": "No.", "start": 943.324, "duration": 1.235}, {"text": "No, I'm not done, because\nthe question says,", "start": 944.559, "duration": 2.336}, {"text": "what's the lattice constant?", "start": 946.895, "duration": 2.269}, {"text": "What's the lattice constant?", "start": 949.164, "duration": 1.167}, {"text": "This d, I didn't say--", "start": 950.331, "duration": 3.003}, {"text": "I did something very bad--", "start": 953.334, "duration": 1.202}, {"text": "I didn't say what d--", "start": 954.536, "duration": 2.636}, {"text": "d is in hkl.", "start": 957.172, "duration": 2.669}, {"text": "That's what an XRD does.", "start": 959.841, "duration": 3.87}, {"text": "XRD, that's a different\nthan diffraction, but the d,", "start": 963.711, "duration": 4.071}, {"text": "in Bragg, is the distance\nbetween the mirror planes", "start": 967.782, "duration": 4.204}, {"text": "that are scattering.", "start": 971.986, "duration": 1.836}, {"text": "All right?", "start": 973.822, "duration": 0.634}, {"text": "And so that's some\ncuts in the crystal.", "start": 974.456, "duration": 3.837}, {"text": "That's some hkl, and\nwe know from that era", "start": 978.293, "duration": 4.838}, {"text": "that there is an equation\nfor cubic crystals", "start": 983.131, "duration": 4.204}, {"text": "that gives us hkl\nwhich is a divided", "start": 987.335, "duration": 3.47}, {"text": "by the square root of h squared\nplus k squared plus l squared.", "start": 990.805, "duration": 8.008}, {"text": "And that is the lattice\nconstant of the crystal,", "start": 998.813, "duration": 7.574}, {"text": "and that would be the\ndistance between any planes,", "start": 1006.387, "duration": 3.337}, {"text": "any set of planes,\nin the crystal,", "start": 1009.724, "duration": 2.169}, {"text": "and that's what we need.", "start": 1011.893, "duration": 1.301}, {"text": "Now, I can use that,\ncombine it with the d,", "start": 1013.194, "duration": 5.739}, {"text": "and I can get that the lattice\nconstant is 8.38 Angstroms.", "start": 1018.933, "duration": 5.005}, {"text": "Good.", "start": 1023.938, "duration": 1.468}, {"text": "But the second question is--", "start": 1025.406, "duration": 2.635}, {"text": "you don't even need to do\nany math to answer that--", "start": 1028.041, "duration": 2.703}, {"text": "what is the lattice structure?", "start": 1030.744, "duration": 2.771}, {"text": "Here, we simply go to\nour selection rules,", "start": 1033.515, "duration": 3.169}, {"text": "and we know from before if\nthey're all even or all odd--", "start": 1036.684, "duration": 7.241}, {"text": "so here we have, let's\nsee, all these peaks--", "start": 1043.925, "duration": 1.867}, {"text": "220, 311, 400.", "start": 1045.792, "duration": 3.905}, {"text": "You can see, they're\nalways all even,", "start": 1049.697, "duration": 1.635}, {"text": "or they're always all odd.", "start": 1051.332, "duration": 1.302}, {"text": "From our selection rules,\nwhat kind of crystal is that?", "start": 1052.634, "duration": 2.569}, {"text": "It's got to be FCC.", "start": 1058.006, "duration": 2.202}, {"text": "All right?", "start": 1060.208, "duration": 0.834}, {"text": "It's got to be FCC.", "start": 1061.042, "duration": 1.768}, {"text": "So that's the answer\nto that question,", "start": 1062.81, "duration": 3.104}, {"text": "just from looking at\nthe peaks that you get", "start": 1065.914, "duration": 2.268}, {"text": "and matching them with the\nselection rules that you know,", "start": 1068.182, "duration": 3.637}, {"text": "that we've already talked about.", "start": 1071.819, "duration": 1.335}, {"text": "You could also, if you\ndidn't have the planes--", "start": 1075.823, "duration": 3.003}, {"text": "so this is an example, where\nyou're given all these planes.", "start": 1078.826, "duration": 3.17}, {"text": "You're given all these hkls,\nbut what if instead it's", "start": 1081.996, "duration": 2.303}, {"text": "like the one we had in class?", "start": 1084.299, "duration": 2.068}, {"text": "We went through this in class.", "start": 1086.367, "duration": 1.235}, {"text": "Here, I'm not given the planes.", "start": 1087.602, "duration": 1.301}, {"text": "I'm given instead\njust two theta values.", "start": 1088.903, "duration": 4.738}, {"text": "Well now, you've got to go\nand use the procedure of XRD,", "start": 1093.641, "duration": 4.271}, {"text": "and I'm not going\nto do that again.", "start": 1097.912, "duration": 1.468}, {"text": "We've already done\nthat pretty thoroughly,", "start": 1099.38, "duration": 2.603}, {"text": "but that's what you\nwould have to do here,", "start": 1101.983, "duration": 2.169}, {"text": "where you create your columns.", "start": 1104.152, "duration": 2.035}, {"text": "Remember the columns?", "start": 1106.187, "duration": 1.935}, {"text": "All right?", "start": 1108.122, "duration": 1.702}, {"text": "So you would simply make your\ncolumns, you make your sign,", "start": 1109.824, "duration": 2.436}, {"text": "your thetas, your 2 theta\ntheta sine squared thetas.", "start": 1112.26, "duration": 4.805}, {"text": "And then you normalize,\nyou take the lowest one,", "start": 1117.065, "duration": 3.97}, {"text": "and you normalize to 1.", "start": 1121.035, "duration": 3.27}, {"text": "Clear fractions, and then\nfind the hkl combinations,", "start": 1124.305, "duration": 3.103}, {"text": "and that's how you would\ngo from this to getting,", "start": 1127.408, "duration": 3.237}, {"text": "for example, the planes.", "start": 1130.645, "duration": 2.569}, {"text": "So those are some\nexamples of things", "start": 1133.214, "duration": 2.336}, {"text": "I want you to be able to\ndo with X-rays and XRD.", "start": 1135.55, "duration": 3.603}, {"text": "Let's move on.", "start": 1139.153, "duration": 1.735}, {"text": "Let's go to the next topic.", "start": 1140.888, "duration": 1.135}, {"text": "Let's do defects.", "start": 1142.023, "duration": 2.035}, {"text": "How about this, defects,\nbecause as we said,", "start": 1144.058, "duration": 5.205}, {"text": "it's just like life,\ncrystals, defects", "start": 1149.263, "duration": 2.903}, {"text": "are what make them interesting.", "start": 1152.166, "duration": 1.669}, {"text": "It's the same.", "start": 1153.835, "duration": 0.867}, {"text": "Everything, it's\nall about defects,", "start": 1154.702, "duration": 2.002}, {"text": "imperfections, those are\nthe interesting and exciting", "start": 1156.704, "duration": 2.703}, {"text": "things, so we've got to know\nabout them in chemistry,", "start": 1159.407, "duration": 3.47}, {"text": "of course.", "start": 1162.877, "duration": 2.87}, {"text": "So we've talked about a bunch\nof different kinds of defects.", "start": 1165.747, "duration": 3.136}, {"text": "The first one that\nwe talked about", "start": 1168.883, "duration": 2.169}, {"text": "were vacancies, vacancies, and\nthese could be interstitial.", "start": 1171.052, "duration": 8.075}, {"text": "These fall into the category of\npoint defects, point defects,", "start": 1181.996, "duration": 5.639}, {"text": "right?", "start": 1187.635, "duration": 0.501}, {"text": "You could also have\ninterstitial point defects,", "start": 1191.039, "duration": 4.471}, {"text": "interstitial or substitutional.", "start": 1195.51, "duration": 4.538}, {"text": "Those are the different\nkinds of defects we've", "start": 1203.184, "duration": 1.935}, {"text": "talked about for point defects.", "start": 1205.119, "duration": 2.236}, {"text": "Also, by the way, if it's an\nionic point defect, ionic point", "start": 1207.355, "duration": 4.137}, {"text": "defect, you need\nto make sure you", "start": 1211.492, "duration": 6.507}, {"text": "have charge neutrality, charge\nneutrality, plus two types.", "start": 1217.999, "duration": 7.974}, {"text": "There's Frenkel, and\nthere's Schottky.", "start": 1228.776, "duration": 2.303}, {"text": "You can think about\nSchottky, you remove,", "start": 1231.079, "duration": 4.971}, {"text": "but you've got to remove them\nin a way that's charge-balanced.", "start": 1236.05, "duration": 3.504}, {"text": "Right?", "start": 1239.554, "duration": 0.5}, {"text": "So in Schottky, you remove.", "start": 1240.054, "duration": 2.336}, {"text": "In an ionic crystal,\nyou've got to keep charge.", "start": 1242.39, "duration": 1.968}, {"text": "That's a new thing you've\ngot to keep track of.", "start": 1244.358, "duration": 2.269}, {"text": "And so if we had--", "start": 1246.627, "duration": 1.102}, {"text": "I'll go to this picture.", "start": 1247.729, "duration": 2.535}, {"text": "Well, you should\nknow this picture.", "start": 1250.264, "duration": 1.902}, {"text": "This is an important picture.", "start": 1252.166, "duration": 1.201}, {"text": "We showed it a lot--", "start": 1253.367, "duration": 1.102}, {"text": "vacancy, interstitial,\nself-interstitial,", "start": 1254.469, "duration": 3.069}, {"text": "substitutional.", "start": 1257.538, "duration": 1.035}, {"text": "And then if it's ionic,\nnow all of a sudden,", "start": 1258.573, "duration": 2.068}, {"text": "you've got charges in\nthere, and so you've just", "start": 1260.641, "duration": 2.103}, {"text": "got to make sure\nthings remain neutral.", "start": 1262.744, "duration": 2.936}, {"text": "Right?", "start": 1265.68, "duration": 0.901}, {"text": "In Schottky, you would remove\natoms to balance the charge,", "start": 1266.581, "duration": 4.371}, {"text": "and in Frenkel,\nyou move an atom.", "start": 1270.952, "duration": 2.869}, {"text": "Schottky remove, Frenkel move.", "start": 1276.524, "duration": 3.136}, {"text": "That just occurred to me,\nthat that's the same word", "start": 1279.66, "duration": 4.071}, {"text": "with just re in front of it.", "start": 1283.731, "duration": 2.736}, {"text": "That's exciting.", "start": 1286.467, "duration": 1.402}, {"text": "Well, so if I were to ask\nyou, for example, if I were to", "start": 1287.869, "duration": 2.736}, {"text": "ask you this.", "start": 1290.605, "duration": 1.268}, {"text": "You diffuse chromium into\none side of the ionic crystal", "start": 1291.873, "duration": 5.939}, {"text": "alumina to make it red\nand titanium on the other.", "start": 1297.812, "duration": 3.603}, {"text": "Would you expect oxygen\nvacancies, aluminum vacancies,", "start": 1301.415, "duration": 2.703}, {"text": "or no vacancies in each case?", "start": 1304.118, "duration": 4.371}, {"text": "Just follow the charge,\nfollow the charge.", "start": 1308.489, "duration": 6.473}, {"text": "So for example, if\nI had alumina, O3.", "start": 1314.962, "duration": 5.072}, {"text": "Well, if I were\nLewis, if I were Lewis", "start": 1320.034, "duration": 3.871}, {"text": "I would see this as 2Al3 plus.", "start": 1323.905, "duration": 6.406}, {"text": "Right?", "start": 1330.311, "duration": 0.501}, {"text": "This is how he saw ionic bonds.", "start": 1330.812, "duration": 3.536}, {"text": "Ah, I want to make\nsure this is clear.", "start": 1334.348, "duration": 7.174}, {"text": "I'm going to start over.", "start": 1341.522, "duration": 1.468}, {"text": "So I would have 2Al3 plus, and\nthen I would have a 3O2 minus.", "start": 1342.99, "duration": 9.777}, {"text": "Remember, O likes to\nbe 2 minus, and so", "start": 1352.767, "duration": 4.604}, {"text": "if I were to introduce\nsomething like Cr2O3,", "start": 1357.371, "duration": 6.006}, {"text": "well, this is 2Cr3 plus, so this\nis 2Cr3 plus, and 3O2 minus.", "start": 1363.377, "duration": 12.746}, {"text": "So if I substitute\naluminum with chromium,", "start": 1376.123, "duration": 5.473}, {"text": "then I'm charge-balanced.", "start": 1381.596, "duration": 2.369}, {"text": "Right?", "start": 1383.965, "duration": 0.5}, {"text": "I'm OK.", "start": 1384.465, "duration": 0.701}, {"text": "But if I substitute titanium,\nTiO2 is Ti4 plus and 2O2 minus,", "start": 1385.166, "duration": 11.778}, {"text": "you know this just\nfrom the formula.", "start": 1396.944, "duration": 1.802}, {"text": "Because if oxygen is 2 minus,\nthis thing's got to be neutral,", "start": 1398.746, "duration": 3.337}, {"text": "and so that's Ti4 plus.", "start": 1402.083, "duration": 2.636}, {"text": "But now, if I put a Ti\nin there, and I get one", "start": 1404.719, "duration": 2.636}, {"text": "in for an aluminum, I've\nknocked the charge by 1.", "start": 1407.355, "duration": 5.438}, {"text": "Right?", "start": 1412.793, "duration": 2.503}, {"text": "So this gives us\nan extra charge,", "start": 1415.296, "duration": 8.041}, {"text": "and that means you've\ngot to create vacancies,", "start": 1423.337, "duration": 2.636}, {"text": "create aluminum vacancies.", "start": 1425.973, "duration": 3.37}, {"text": "It's the only way to do it.", "start": 1429.343, "duration": 2.436}, {"text": "So for every three titanium\natoms that I put in,", "start": 1431.779, "duration": 2.436}, {"text": "I've got to take an\naluminum one out.", "start": 1434.215, "duration": 1.702}, {"text": "Right?", "start": 1435.917, "duration": 0.5}, {"text": "Otherwise, I'm not going\nto have charge balance,", "start": 1436.417, "duration": 2.903}, {"text": "not going to have\ncharge balance.", "start": 1439.32, "duration": 1.368}, {"text": "Right?", "start": 1440.688, "duration": 1.335}, {"text": "So that would be an example of\nplaying with an ionic crystal,", "start": 1442.023, "duration": 4.404}, {"text": "but remember, we also\nhad stress-strain curves.", "start": 1446.427, "duration": 2.736}, {"text": "Because when we talked\nabout line defects,", "start": 1449.163, "duration": 5.806}, {"text": "we talked about how that's a way\nfor metals and other materials", "start": 1454.969, "duration": 3.87}, {"text": "to undergo deformation.", "start": 1458.839, "duration": 1.402}, {"text": "And then we said,\nwell, how are we", "start": 1460.241, "duration": 1.702}, {"text": "going to conceptualize\nthese things happening,", "start": 1461.943, "duration": 4.437}, {"text": "and we did it with the\nstress-strain curve", "start": 1466.38, "duration": 1.735}, {"text": "and the mechanical\nresponse of materials.", "start": 1468.115, "duration": 2.469}, {"text": "So we learned about\nstress-strain curves", "start": 1470.584, "duration": 2.203}, {"text": "and fracture points,\nfracture and plastic", "start": 1472.787, "duration": 9.342}, {"text": "versus elastic regimes.", "start": 1482.129, "duration": 4.872}, {"text": "OK, I'll give an\nexample in a sec.", "start": 1487.001, "duration": 3.503}, {"text": "OK?", "start": 1490.504, "duration": 0.501}, {"text": "And finally, the last\nthing we did with defects", "start": 1493.841, "duration": 1.969}, {"text": "is we talked about\ntheir activation.", "start": 1495.81, "duration": 2.135}, {"text": "And so we know if something\nis thermally activated,", "start": 1497.945, "duration": 4.271}, {"text": "as are point defects, vacancies\nare thermally activated,", "start": 1502.216, "duration": 5.472}, {"text": "so are other types\nof point defects.", "start": 1507.688, "duration": 2.77}, {"text": "And we said that we need\nan Arrhenius relationship,", "start": 1510.458, "duration": 3.203}, {"text": "and that requires\nknowledge of an activation", "start": 1513.661, "duration": 3.904}, {"text": "energy for the defect to form.", "start": 1517.565, "duration": 2.702}, {"text": "So that was another\nreally important concept", "start": 1520.267, "duration": 3.037}, {"text": "that we covered.", "start": 1523.304, "duration": 0.767}, {"text": "Right?", "start": 1524.071, "duration": 0.834}, {"text": "So for example, here is like\na defect formation energy", "start": 1524.905, "duration": 4.538}, {"text": "question.", "start": 1529.443, "duration": 0.501}, {"text": "So let me go over here, stay\nwith this side, where I've got", "start": 1533.18, "duration": 5.639}, {"text": "some defects.", "start": 1538.819, "duration": 2.67}, {"text": "So one thing I\nwant to make clear,", "start": 1541.489, "duration": 4.004}, {"text": "the fraction of vacancies.", "start": 1545.493, "duration": 1.801}, {"text": "We talked about this.", "start": 1547.294, "duration": 0.868}, {"text": "We talked about an\nArrhenius behavior,", "start": 1548.162, "duration": 2.469}, {"text": "Arrhenius-like behavior, and\nthe fraction of vacancies", "start": 1550.631, "duration": 3.504}, {"text": "was the number of vacancies over\nthe number of possible sites.", "start": 1554.135, "duration": 4.971}, {"text": "That makes a lot of sense.", "start": 1559.106, "duration": 1.535}, {"text": "Now, if it's\nArrhenius, then this", "start": 1560.641, "duration": 1.735}, {"text": "is some constant times e to the\nminus activation energy divided", "start": 1562.376, "duration": 4.238}, {"text": "by KBT, where we use\nthe Boltzmann constant", "start": 1566.614, "duration": 4.07}, {"text": "if it's per atom.", "start": 1570.684, "duration": 2.236}, {"text": "Right?", "start": 1572.92, "duration": 1.768}, {"text": "So per vacancy, that activation\nenergy would be per vacancy.", "start": 1574.688, "duration": 4.305}, {"text": "But when I first introduced\nthis, I simply let a be 1,", "start": 1578.993, "duration": 4.438}, {"text": "but a is a constant.", "start": 1583.431, "duration": 2.235}, {"text": "This is a constant,\nand it can be whatever.", "start": 1585.666, "duration": 5.139}, {"text": "It's a constant.", "start": 1590.805, "duration": 0.767}, {"text": "It's called the\nanthropic factor,", "start": 1591.572, "duration": 4.671}, {"text": "and it's a constant related\nto as you would have", "start": 1596.243, "duration": 3.304}, {"text": "in any Arrhenius-like behavior.", "start": 1599.547, "duration": 2.602}, {"text": "Right?", "start": 1602.149, "duration": 1.235}, {"text": "Remember how it's like\na frequency factor,", "start": 1603.384, "duration": 2.669}, {"text": "this is related to all\nsorts of complexities", "start": 1606.053, "duration": 3.404}, {"text": "that we don't need to know about\nrelated to how vacancies form.", "start": 1609.457, "duration": 3.37}, {"text": "It's a constant that's in\nthere, and I let it be 1,", "start": 1612.827, "duration": 2.135}, {"text": "but I want to make sure\nwe put it in explicitly.", "start": 1614.962, "duration": 2.469}, {"text": "This n is the number\nof possible sites.", "start": 1621.902, "duration": 2.77}, {"text": "Right?", "start": 1624.672, "duration": 0.5}, {"text": "So maybe it's the number of\nlattice sites in the crystal,", "start": 1625.172, "duration": 4.538}, {"text": "number of possible sites.", "start": 1629.71, "duration": 1.301}, {"text": "But you might get\nthis could be related", "start": 1631.011, "duration": 3.07}, {"text": "to, for example, or to or\nfrom, things like the grams", "start": 1634.081, "duration": 9.376}, {"text": "that you have of something\nor maybe the volume", "start": 1643.457, "duration": 6.073}, {"text": "or the moles, et cetera.", "start": 1649.53, "duration": 1.034}, {"text": "Right?", "start": 1650.564, "duration": 0.501}, {"text": "So these are the kinds\nof problems we've done.", "start": 1651.065, "duration": 3.937}, {"text": "That gives you a sense of\nhow many sites did you have.", "start": 1655.002, "duration": 4.938}, {"text": "Right?", "start": 1659.94, "duration": 0.968}, {"text": "It could be per\ncentimeter cubed.", "start": 1660.908, "duration": 2.603}, {"text": "It could be per moles.", "start": 1663.511, "duration": 2.235}, {"text": "You go back and forth.", "start": 1665.746, "duration": 1.635}, {"text": "How much stuff do I have?", "start": 1667.381, "duration": 2.402}, {"text": "It's that kind of\nback and forth.", "start": 1669.783, "duration": 2.37}, {"text": "If I had a problem like this,\nthen I know I can set it up,", "start": 1672.153, "duration": 4.004}, {"text": "because I've got\ntwo temperatures.", "start": 1676.157, "duration": 2.836}, {"text": "You see the key here,\nthe concentration of 10", "start": 1678.993, "duration": 2.802}, {"text": "to the cubed per\ncentimeter cubed,", "start": 1681.795, "duration": 3.304}, {"text": "so don't let that throw you off.", "start": 1685.099, "duration": 1.334}, {"text": "It's simply two equations,\nwhere a bunch of stuff cancels.", "start": 1686.433, "duration": 4.472}, {"text": "Right?", "start": 1690.905, "duration": 1.001}, {"text": "So the fraction\nof vacancies, fv1,", "start": 1691.906, "duration": 4.904}, {"text": "would be 10 to the\n3rd divided by fv2,", "start": 1696.81, "duration": 4.705}, {"text": "and that's going to be 10 to\nthe 3rd over 10 to the 16th,", "start": 1701.515, "duration": 4.538}, {"text": "because the number\nof stuff cancels.", "start": 1706.053, "duration": 4.304}, {"text": "Right?", "start": 1710.357, "duration": 0.501}, {"text": "I didn't change that.", "start": 1710.858, "duration": 1.468}, {"text": "But this pre-factor cancels too.", "start": 1712.326, "duration": 2.336}, {"text": "You can put it there, A times\ne to the minus ea divided by KB", "start": 1714.662, "duration": 8.341}, {"text": "times 300 Kelvin--\nremember, so it was Kelvin--", "start": 1723.003, "duration": 3.771}, {"text": "divided by A times to the\nminus ea divided by KB times", "start": 1726.774, "duration": 8.909}, {"text": "the other temperature,\n900 Kelvin.", "start": 1735.683, "duration": 3.503}, {"text": "Right?", "start": 1739.186, "duration": 0.734}, {"text": "And so those cancel,\nthe stuff related to n", "start": 1739.92, "duration": 4.772}, {"text": "cancels, and I can just take\nthe number of vacancies.", "start": 1744.692, "duration": 3.069}, {"text": "Right?", "start": 1747.761, "duration": 0.668}, {"text": "So that's what's nice about\nhaving something like this.", "start": 1748.429, "duration": 1.768}, {"text": "You have two temperatures\nand a whole bunch of stuff", "start": 1750.197, "duration": 2.302}, {"text": "can cancel, and you can figure\nout then the activation energy", "start": 1752.499, "duration": 5.106}, {"text": "which doesn't change.", "start": 1757.605, "duration": 2.102}, {"text": "The activation energy is simply\nthe energy that you need,", "start": 1759.707, "duration": 3.803}, {"text": "so you can now solve for ea,\nand I think you get something", "start": 1763.51, "duration": 5.74}, {"text": "like 2.3 electron volts.", "start": 1769.25, "duration": 2.268}, {"text": "Remember that you could\nalso have plotted it.", "start": 1771.518, "duration": 2.403}, {"text": "You'd know that\nin this equation,", "start": 1773.921, "duration": 2.536}, {"text": "in the Arrhenius relationship,\nif you take the log,", "start": 1776.457, "duration": 3.804}, {"text": "then you have the minus\n1 over T relationship.", "start": 1780.261, "duration": 4.804}, {"text": "So remember that?", "start": 1785.065, "duration": 1.669}, {"text": "So if you take the\nT versus the log,", "start": 1786.734, "duration": 3.77}, {"text": "then you're going to get that.", "start": 1790.504, "duration": 2.102}, {"text": "Right?", "start": 1792.606, "duration": 2.269}, {"text": "We like plots, when we\nthink about Arrhenius,", "start": 1794.875, "duration": 2.169}, {"text": "because it makes it easier.", "start": 1797.044, "duration": 1.134}, {"text": "We can make it linear,\nwhere the slope of this", "start": 1798.178, "duration": 3.237}, {"text": "is minus ea, the slope, minus\nea over KB, in this case.", "start": 1801.415, "duration": 7.908}, {"text": "Right?", "start": 1809.323, "duration": 0.5}, {"text": "So we talked about these\nare all kinds of things", "start": 1809.823, "duration": 2.203}, {"text": "that we talked about.", "start": 1812.026, "duration": 1.034}, {"text": "And finally, getting\nto this stress-strain,", "start": 1813.06, "duration": 1.802}, {"text": "what if we looked at this?", "start": 1814.862, "duration": 1.835}, {"text": "This is the stress-strain,\nso now we're here.", "start": 1816.697, "duration": 3.303}, {"text": "We just did this.", "start": 1820.0, "duration": 1.135}, {"text": "We talked about that.", "start": 1821.135, "duration": 0.901}, {"text": "We talked about this,\nso stress-strain.", "start": 1822.036, "duration": 2.369}, {"text": "So if you were to be given\nplots like this, you should know", "start": 1824.405, "duration": 4.404}, {"text": "which one is most\nbrittle, which one", "start": 1828.809, "duration": 1.535}, {"text": "is the stiffest, the\nmost resistant to", "start": 1830.344, "duration": 2.936}, {"text": "changing elastically, and\nwhich one is the most ductile?", "start": 1833.28, "duration": 5.839}, {"text": "You can see that\nthe stiffest one", "start": 1839.119, "duration": 2.136}, {"text": "is going to be the one\nthat's the most resistant to", "start": 1841.255, "duration": 4.404}, {"text": "elastic deformation.", "start": 1845.659, "duration": 1.201}, {"text": "That's that linear\npart, that first part.", "start": 1846.86, "duration": 2.47}, {"text": "So there, it's\ngoing to be material", "start": 1849.33, "duration": 2.202}, {"text": "A. It's going to be A, because\nit's got the highest slope.", "start": 1851.532, "duration": 4.704}, {"text": "Right?", "start": 1856.236, "duration": 1.068}, {"text": "OK.", "start": 1857.304, "duration": 1.535}, {"text": "How about the most brittle?", "start": 1858.839, "duration": 1.134}, {"text": "Well, that's the one\nthat's going to break.", "start": 1859.973, "duration": 3.471}, {"text": "So it sort of looks like--", "start": 1863.444, "duration": 1.601}, {"text": "without deforming, without being\nable to undergo defamation,", "start": 1865.045, "duration": 3.404}, {"text": "that's brittleness.", "start": 1868.449, "duration": 1.968}, {"text": "It's going to crack\nbefore doing anything.", "start": 1870.417, "duration": 2.369}, {"text": "So that's B, right?", "start": 1872.786, "duration": 1.135}, {"text": "That's B.", "start": 1873.921, "duration": 1.468}, {"text": "And then the most ductile will\nbe the one that has the most", "start": 1875.389, "duration": 2.936}, {"text": "plastic deformation, because\nthat's what ductility is,", "start": 1878.325, "duration": 3.237}, {"text": "so that's going to be C. OK?", "start": 1881.562, "duration": 3.603}, {"text": "So remember\nstress-strain curves.", "start": 1885.165, "duration": 1.502}, {"text": "You've got this elastic\npart here, that's linear,", "start": 1886.667, "duration": 3.603}, {"text": "and then if it's a material--\nnot all materials have", "start": 1890.27, "duration": 4.004}, {"text": "plastic defamation.", "start": 1894.274, "duration": 2.736}, {"text": "Some are going to\nbreak before they", "start": 1897.01, "duration": 1.902}, {"text": "start deforming plastically, but\nif it can deform plastically,", "start": 1898.912, "duration": 4.038}, {"text": "then it's going to\nhave that yield point.", "start": 1902.95, "duration": 2.769}, {"text": "Right?", "start": 1905.719, "duration": 0.501}, {"text": "The yield stress, where then\nit starts becoming non-linear,", "start": 1906.22, "duration": 2.936}, {"text": "and then finally, it\nfractures somewhere else.", "start": 1909.156, "duration": 5.005}, {"text": "OK?", "start": 1914.161, "duration": 0.5}, {"text": "So those are\nstress-strain curves.", "start": 1914.661, "duration": 2.269}, {"text": "OK, let's move on.", "start": 1916.93, "duration": 3.404}, {"text": "Now, oh, with the next topic--", "start": 1920.334, "duration": 7.607}, {"text": "oh boy, I'm going to\nrun out of real estate--", "start": 1927.941, "duration": 4.004}, {"text": "we've got glasses, and here,\nthe most important thing", "start": 1931.945, "duration": 9.109}, {"text": "to know about is the curve.", "start": 1941.054, "duration": 2.737}, {"text": "That's how it all started.", "start": 1943.791, "duration": 1.167}, {"text": "Right?", "start": 1944.958, "duration": 0.501}, {"text": "I'm calling it The Curve.", "start": 1945.459, "duration": 1.401}, {"text": "Let's go all caps,\nbecause it's The Curve,", "start": 1946.86, "duration": 4.071}, {"text": "and what I mean by The\nCurve is the volume", "start": 1950.931, "duration": 3.17}, {"text": "per mole versus temperature.", "start": 1954.101, "duration": 6.373}, {"text": "We also talked about the\neffects of cooling rate,", "start": 1960.474, "duration": 10.077}, {"text": "and we also talked about\nthe effects of modifiers,", "start": 1970.551, "duration": 8.909}, {"text": "and in particular how the\nmodifier changes the viscosity", "start": 1979.46, "duration": 6.473}, {"text": "because it cuts the pasta.", "start": 1985.933, "duration": 2.469}, {"text": "OK, so but the framing of these\nconcepts was in The Curve,", "start": 1988.402, "duration": 6.406}, {"text": "and that's this one.", "start": 1994.808, "duration": 0.834}, {"text": "Oh, I have a picture of it.", "start": 1995.642, "duration": 1.435}, {"text": "There it is.", "start": 1997.077, "duration": 1.668}, {"text": "OK, they did specific--\nwe do volume per mole", "start": 1998.745, "duration": 2.369}, {"text": "is how we're looking at it in\nthis class, so volume per mole", "start": 2001.114, "duration": 2.47}, {"text": "versus temperature.", "start": 2003.584, "duration": 2.269}, {"text": "Now remember, if it's a\ncrystal, where am I going to go?", "start": 2005.853, "duration": 4.971}, {"text": "Let's go here.", "start": 2010.824, "duration": 1.568}, {"text": "If it's a crystal, then you've\ngot one melting point that", "start": 2012.392, "duration": 5.072}, {"text": "only depends on the material.", "start": 2017.464, "duration": 4.271}, {"text": "It only depends on the material,\nso that melting point is Tm,", "start": 2021.735, "duration": 6.44}, {"text": "and it's going to have a\nbig volume change as it goes", "start": 2028.175, "duration": 3.47}, {"text": "from liquid to crystal solid.", "start": 2031.645, "duration": 3.57}, {"text": "OK?", "start": 2035.215, "duration": 1.135}, {"text": "And so for example, I'm just\nbasically replotting it,", "start": 2036.35, "duration": 5.372}, {"text": "but you would have something\nlike this and something", "start": 2041.722, "duration": 2.869}, {"text": "like this and\nsomething like this,", "start": 2044.591, "duration": 2.269}, {"text": "and that's your melting point.", "start": 2046.86, "duration": 3.37}, {"text": "This would be the liquid,\nand this would be the solid,", "start": 2050.23, "duration": 2.936}, {"text": "and you know that, if it's\ngoing to undergo this big volume", "start": 2053.166, "duration": 2.47}, {"text": "change.", "start": 2055.636, "duration": 0.967}, {"text": "Then, it's the melting\npoint and it's a crystal.", "start": 2056.603, "duration": 3.237}, {"text": "But then we say, well,\nbut if it can't find--", "start": 2059.84, "duration": 2.736}, {"text": "by crystal I mean in opposition\nto glass, which we know", "start": 2062.576, "duration": 4.137}, {"text": "doesn't just mean your windows.", "start": 2066.713, "duration": 1.769}, {"text": "It means any amorphous material,\nmeaning it's not crystalline.", "start": 2068.482, "duration": 3.869}, {"text": "It didn't find the\nlattice structure.", "start": 2072.351, "duration": 2.537}, {"text": "Remember those three\nreasons, the musical chairs?", "start": 2074.888, "duration": 2.836}, {"text": "Whatever you're trying\nto crystallize, atoms", "start": 2077.724, "duration": 1.836}, {"text": "or molecules, they weren't able\nto find all the lattice sites,", "start": 2079.56, "duration": 4.003}, {"text": "not even withstanding\nsome defects here.", "start": 2083.563, "duration": 2.636}, {"text": "They simply couldn't do\nit, and so it's amorphous,", "start": 2086.199, "duration": 3.104}, {"text": "and it's a glass.", "start": 2089.303, "duration": 1.668}, {"text": "And in that case,\nwhat happens is it", "start": 2090.971, "duration": 3.235}, {"text": "super cools and then\nbecomes a solid at something", "start": 2094.206, "duration": 8.377}, {"text": "called the glass\ntransition temperature.", "start": 2102.583, "duration": 1.634}, {"text": "Which unlike the crystal\ncan have different values,", "start": 2104.217, "duration": 4.205}, {"text": "and those values can depend on\nthings like the cooling rate.", "start": 2108.422, "duration": 3.537}, {"text": "So if I cool it slower,\nif I cool it slower--", "start": 2111.959, "duration": 5.672}, {"text": "remember this is faster,\nfaster, slower, and please,", "start": 2117.631, "duration": 6.406}, {"text": "do not confuse time\nwith this axis.", "start": 2124.037, "duration": 2.469}, {"text": "This is just temperature.", "start": 2126.506, "duration": 1.669}, {"text": "So we can use the same--", "start": 2128.175, "duration": 1.968}, {"text": "this is volume per mole-- we can\nuse the same The Plot to think", "start": 2130.143, "duration": 4.939}, {"text": "about modifiers as well.", "start": 2135.082, "duration": 2.168}, {"text": "Because it's not-- this is\njust one plot, one curve", "start": 2137.25, "duration": 4.004}, {"text": "and another.", "start": 2141.254, "duration": 1.001}, {"text": "This happened to\nbe cooled slower,", "start": 2142.255, "duration": 1.869}, {"text": "so it was able to\nsuper cool more,", "start": 2144.124, "duration": 2.836}, {"text": "before it locked\nin the disorder,", "start": 2146.96, "duration": 2.169}, {"text": "and the other one's faster.", "start": 2149.129, "duration": 1.635}, {"text": "You could also imagine\nif you cut the pasta,", "start": 2150.764, "duration": 2.836}, {"text": "you change the viscosity.", "start": 2153.6, "duration": 3.07}, {"text": "And so now you're\nchanging something else", "start": 2156.67, "duration": 1.868}, {"text": "about the glass using\nchemistry, and you're", "start": 2158.538, "duration": 2.136}, {"text": "allowing it to find those\nlattice sites more easily.", "start": 2160.674, "duration": 3.437}, {"text": "You're allowing it to try\nto become crystalline,", "start": 2164.111, "duration": 2.035}, {"text": "to try to close pack\njust a little bit more.", "start": 2166.146, "duration": 2.736}, {"text": "So you can also get this,\nby cutting the pasta you", "start": 2168.882, "duration": 3.003}, {"text": "can get these kinds of changes.", "start": 2171.885, "duration": 3.403}, {"text": "So those are the things we\ntalked about with glass.", "start": 2175.288, "duration": 4.004}, {"text": "Now, next, we talked\nabout reactions.", "start": 2179.292, "duration": 6.741}, {"text": "OK.", "start": 2186.033, "duration": 0.5}, {"text": "What do we need to know about\nreactions, reaction rates?", "start": 2194.274, "duration": 7.441}, {"text": "So we want to know the order\nof some general reaction,", "start": 2201.715, "duration": 7.507}, {"text": "like aA plus bB--", "start": 2209.222, "duration": 2.67}, {"text": "remember this--\ngoes to cC plus dD.", "start": 2211.892, "duration": 3.737}, {"text": "And we want to know\nthe rate from--", "start": 2218.832, "duration": 8.075}, {"text": "basically, it's the\nmass conservation,", "start": 2226.907, "duration": 2.702}, {"text": "so from the coefficients.", "start": 2229.609, "duration": 3.437}, {"text": "OK, so that would\nbe, for example,", "start": 2233.046, "duration": 2.369}, {"text": "like minus 1 over a, d(A), dt--", "start": 2235.415, "duration": 4.104}, {"text": "that's a rate-- equals minus\n1 over b d(B), dt, et cetera.", "start": 2239.519, "duration": 6.44}, {"text": "Now, those come from\nthe coefficients,", "start": 2250.097, "duration": 2.068}, {"text": "but the rate law does not,\nthe rate law does not.", "start": 2252.165, "duration": 5.906}, {"text": "So these are simply\ninstantaneous rates,", "start": 2258.071, "duration": 2.202}, {"text": "but now I say, no, I\nwant a rate law that", "start": 2260.273, "duration": 2.837}, {"text": "gives me the dependence on these\nconcentrations at any time.", "start": 2263.11, "duration": 6.973}, {"text": "So the rate law would\nbe, for example,", "start": 2273.854, "duration": 6.339}, {"text": "like rate equals k times\nA to the m, B to the n.", "start": 2280.193, "duration": 9.143}, {"text": "Now, here's the thing.", "start": 2289.336, "duration": 2.335}, {"text": "These come from experiments.", "start": 2291.671, "duration": 4.572}, {"text": "Very important\ndistinction, right?", "start": 2301.481, "duration": 2.803}, {"text": "Those come from\nexperiments, and so you", "start": 2304.284, "duration": 2.836}, {"text": "could get the rate with\nrespect to A which would be--", "start": 2307.12, "duration": 2.536}, {"text": "I'm sorry.", "start": 2309.656, "duration": 0.601}, {"text": "The order with respect\nto A would be m,", "start": 2310.257, "duration": 3.336}, {"text": "the order with respect\nto B would be n,", "start": 2313.593, "duration": 2.169}, {"text": "and the overall\norder of the reaction", "start": 2315.762, "duration": 2.403}, {"text": "is m plus n, the overall order.", "start": 2318.165, "duration": 3.103}, {"text": "And then, we had one more\nitem here of conceptually", "start": 2324.604, "duration": 4.338}, {"text": "what I want you to know about,\nwhich is that the rate also", "start": 2328.942, "duration": 3.27}, {"text": "depends on temperature.", "start": 2332.212, "duration": 2.469}, {"text": "Sorry, the rate\nconstant, rate constant", "start": 2334.681, "duration": 5.005}, {"text": "depends on temperature.", "start": 2339.686, "duration": 3.07}, {"text": "So if I were to now\nsay, well, OK, I", "start": 2342.756, "duration": 2.235}, {"text": "want to know something about\nthe order of a reaction,", "start": 2344.991, "duration": 2.303}, {"text": "you might get a table like\nthis, and we did this in class.", "start": 2347.294, "duration": 3.77}, {"text": "You might get a\ntable just like this.", "start": 2351.064, "duration": 1.769}, {"text": "Here's a reaction.", "start": 2352.833, "duration": 0.934}, {"text": "It's W and X and Y,\nand it goes to Z.", "start": 2353.767, "duration": 4.638}, {"text": "Don't let the fact that you have\nthree reactants throw you off.", "start": 2358.405, "duration": 3.537}, {"text": "You've got a certain\nnumber of reactants,", "start": 2361.942, "duration": 1.701}, {"text": "they've got their coefficients,\nand they go to some product.", "start": 2363.643, "duration": 4.071}, {"text": "And now, you're given\nexperimental data, so", "start": 2367.714, "duration": 2.836}, {"text": "from this data, you\ncan get the order", "start": 2370.55, "duration": 3.07}, {"text": "of the reaction with respect\nto each one of these.", "start": 2373.62, "duration": 3.203}, {"text": "Right?", "start": 2376.823, "duration": 0.934}, {"text": "And that would then give you,\nof course, the overall order.", "start": 2377.757, "duration": 3.037}, {"text": "So let's see.", "start": 2380.794, "duration": 0.7}, {"text": "If we were to look at that\ndata, then what would we get?", "start": 2381.494, "duration": 6.006}, {"text": "So what you want to do in\nthese kinds of situations is,", "start": 2387.5, "duration": 7.308}, {"text": "first of all, don't panic.", "start": 2394.808, "duration": 2.402}, {"text": "By the way, on an exam,\nin general, don't panic,", "start": 2397.21, "duration": 2.603}, {"text": "and if you have a question,\nyou can ask a question,", "start": 2399.813, "duration": 2.202}, {"text": "but also show us what you know.", "start": 2402.015, "duration": 2.97}, {"text": "We will give you-- as you\nI hope have seen already--", "start": 2404.985, "duration": 2.903}, {"text": "we will give you as much\ncredit as we can for sharing", "start": 2407.888, "duration": 2.769}, {"text": "what you know.", "start": 2410.657, "duration": 0.601}, {"text": "You don't have to get everything\nright to get a lot of points.", "start": 2411.258, "duration": 3.536}, {"text": "Please share your knowledge.", "start": 2414.794, "duration": 3.137}, {"text": "So in this case, what\nwould the knowledge be?", "start": 2417.931, "duration": 1.969}, {"text": "Well, it would be that\nI want to compare stuff,", "start": 2419.9, "duration": 1.968}, {"text": "like trial 1 and 2.", "start": 2421.868, "duration": 1.502}, {"text": "And if I do that, you see,\nOK, trial 1, trial 2, then two", "start": 2423.37, "duration": 4.604}, {"text": "of them stay constant,\nbut W doubles.", "start": 2427.974, "duration": 3.137}, {"text": "OK?", "start": 2431.111, "duration": 0.967}, {"text": "So comparing 1 versus 2, you\ngot W goes to 2 two times,", "start": 2432.078, "duration": 12.012}, {"text": "but the rate is\nsame, so you know", "start": 2444.09, "duration": 4.572}, {"text": "the order is 0 with respect to\nW. But if I compare 1 versus 3,", "start": 2448.662, "duration": 9.809}, {"text": "then you know that,\nlet's see, x goes to 3x", "start": 2458.471, "duration": 6.273}, {"text": "and the rate goes to 3x,\nand so the order is 1.", "start": 2464.744, "duration": 9.743}, {"text": "And then finally, for Y--", "start": 2474.487, "duration": 2.136}, {"text": "I will just jump to it--", "start": 2476.623, "duration": 2.002}, {"text": "the order is 2, and you can\ndo that just by find one", "start": 2478.625, "duration": 6.773}, {"text": "where only Y changes.", "start": 2485.398, "duration": 2.236}, {"text": "You don't have to\nnecessarily find one", "start": 2487.634, "duration": 2.669}, {"text": "where just one changes.", "start": 2490.303, "duration": 1.335}, {"text": "Right?", "start": 2491.638, "duration": 2.002}, {"text": "Because if you knew\none is first order--", "start": 2493.64, "duration": 4.137}, {"text": "if you knew one, and then you\nhad another one, and they both", "start": 2497.777, "duration": 2.503}, {"text": "changed.", "start": 2500.28, "duration": 0.467}, {"text": "But maybe the rate\ndidn't change,", "start": 2500.747, "duration": 1.401}, {"text": "then you know they must have\nboth the same order, if they", "start": 2502.148, "duration": 2.403}, {"text": "change in opposite ways.", "start": 2504.551, "duration": 1.635}, {"text": "Right?", "start": 2506.186, "duration": 0.667}, {"text": "So you can get into\nthis in different ways,", "start": 2506.853, "duration": 1.768}, {"text": "just looking at these\nchanges from one to another", "start": 2508.621, "duration": 4.305}, {"text": "and thinking about\nwhat must happen", "start": 2512.926, "duration": 2.402}, {"text": "in terms of the\nrate law, in terms", "start": 2515.328, "duration": 1.635}, {"text": "of what you wrote out here.", "start": 2516.963, "duration": 2.069}, {"text": "But you could also ask\nquestions like with reactions,", "start": 2522.302, "duration": 5.405}, {"text": "OK, this is first order.", "start": 2527.707, "duration": 1.535}, {"text": "What's the dependence\nof the concentration", "start": 2529.242, "duration": 1.769}, {"text": "over time as a function\nof the rate constant?", "start": 2531.011, "duration": 2.635}, {"text": "Well, that just goes back to our\nunderstanding of the integrated", "start": 2533.646, "duration": 5.039}, {"text": "rate equation.", "start": 2538.685, "duration": 1.234}, {"text": "Right?", "start": 2539.919, "duration": 0.734}, {"text": "And so let's see, oh\nboy, now I need to find--", "start": 2540.653, "duration": 6.34}, {"text": "I'm going to go--", "start": 2546.993, "duration": 1.402}, {"text": "I hate to do this, XRD.", "start": 2548.395, "duration": 1.735}, {"text": "I hate to do this, but\nsometimes being first carries", "start": 2550.13, "duration": 8.575}, {"text": "a consequence.", "start": 2558.705, "duration": 0.801}, {"text": "OK.", "start": 2562.742, "duration": 1.635}, {"text": "So in this case--", "start": 2564.377, "duration": 1.235}, {"text": "first of all, by the\nway, you look at reaction", "start": 2565.612, "duration": 1.902}, {"text": "like that, you're like, well\nOK, from the coefficients", "start": 2567.514, "duration": 2.235}, {"text": "and the mass balance stuff, you\nknow that the change in oxygen,", "start": 2569.749, "duration": 3.671}, {"text": "for example, with\ntime, the instantaneous", "start": 2573.42, "duration": 2.202}, {"text": "rate would equal minus the\nchange in MO2 with time.", "start": 2575.622, "duration": 7.774}, {"text": "Well, that's not what\nthe question asked.", "start": 2583.396, "duration": 1.702}, {"text": "The question says\nit's first order.", "start": 2585.098, "duration": 2.469}, {"text": "So that's enough, because\nthis means that if I integrate", "start": 2587.567, "duration": 8.208}, {"text": "the rate law then-- first of\nall, if it's first order--", "start": 2595.775, "duration": 4.305}, {"text": "then d of MO2 with\nrespect to time", "start": 2600.08, "duration": 5.238}, {"text": "must equal some constant\ntimes the concentration of MO2", "start": 2605.318, "duration": 6.24}, {"text": "to the 1, first order.", "start": 2611.558, "duration": 3.904}, {"text": "And so now, if I\nintegrate this, I", "start": 2615.462, "duration": 2.135}, {"text": "take this concentration over\nhere, I put the dt over there.", "start": 2617.597, "duration": 3.136}, {"text": "You integrate it.", "start": 2620.733, "duration": 0.835}, {"text": "You've got all the\nintegrated rate laws.", "start": 2621.568, "duration": 1.668}, {"text": "We've gone through this already.", "start": 2623.236, "duration": 1.568}, {"text": "You know that you\nget that the log--", "start": 2624.804, "duration": 3.837}, {"text": "oh, we do logs--", "start": 2628.641, "duration": 1.669}, {"text": "are this MO2 equals the log\nof some starting concentration", "start": 2630.31, "duration": 7.941}, {"text": "minus Kt.", "start": 2638.251, "duration": 1.835}, {"text": "OK?", "start": 2640.086, "duration": 2.002}, {"text": "Why do we do that?", "start": 2642.088, "duration": 0.768}, {"text": "Because we like plotting\nthings, linear things.", "start": 2642.856, "duration": 2.469}, {"text": "We love linear.", "start": 2645.325, "duration": 3.036}, {"text": "So remember, we did this.", "start": 2648.361, "duration": 1.902}, {"text": "We went from these\nintegrated rate", "start": 2650.263, "duration": 1.902}, {"text": "laws to plots and\nback and forth,", "start": 2652.165, "duration": 2.235}, {"text": "and so that's also\nvery important.", "start": 2654.4, "duration": 2.636}, {"text": "OK.", "start": 2657.036, "duration": 1.268}, {"text": "Now finally, so the\nlast couple of things.", "start": 2658.304, "duration": 4.104}, {"text": "And I'm purposely giving these\nlast ones a little less time,", "start": 2662.408, "duration": 3.137}, {"text": "because they're the ones that\nwe've seen very recently,", "start": 2665.545, "duration": 2.636}, {"text": "and these are the\nones that we haven't", "start": 2668.181, "duration": 1.568}, {"text": "seen for almost a month.", "start": 2669.749, "duration": 2.136}, {"text": "Right?", "start": 2671.885, "duration": 1.635}, {"text": "Yeah, but you still gotta\nknow about solubility,", "start": 2673.52, "duration": 5.138}, {"text": "and so for solubility,\nremember what we did is we did", "start": 2678.658, "duration": 3.504}, {"text": "equilibrium and Le Chatelier,\nand we did the equilibrium", "start": 2682.162, "duration": 8.742}, {"text": "constants, the K's.", "start": 2690.904, "duration": 3.136}, {"text": "Like for example, Ksp is\nthe solubility product,", "start": 2694.04, "duration": 4.972}, {"text": "solubility product constant.", "start": 2699.012, "duration": 3.17}, {"text": "Right?", "start": 2702.182, "duration": 1.201}, {"text": "And then we also did\nice tables, and then we", "start": 2703.383, "duration": 6.373}, {"text": "talked about the common ion.", "start": 2709.756, "duration": 1.368}, {"text": "And so as an example,\nif I were to tell you,", "start": 2716.296, "duration": 2.469}, {"text": "well, OK, I'm going\nto take BaCl2.", "start": 2718.765, "duration": 2.803}, {"text": "I might have done this\none in class already.", "start": 2721.568, "duration": 2.035}, {"text": "If I add BaCl2 to a\nsaturated solution of BaSO4,", "start": 2723.603, "duration": 3.57}, {"text": "why does it cause precipitation?", "start": 2727.173, "duration": 3.937}, {"text": "Answer-- because\nof the common ion", "start": 2731.11, "duration": 1.669}, {"text": "effect, but you could\nwrite these out.", "start": 2732.779, "duration": 3.437}, {"text": "So you write out your\nsaturated solution,", "start": 2736.216, "duration": 3.336}, {"text": "so you write out\nyour BaSO4, and you", "start": 2739.552, "duration": 3.57}, {"text": "see that BaSO4 solid will\ngo to Ba2 plus in solution", "start": 2743.122, "duration": 10.911}, {"text": "plus SO4 2 minus in solution.", "start": 2754.033, "duration": 3.904}, {"text": "And so the common\nion effect tells you", "start": 2757.937, "duration": 2.836}, {"text": "that if I now add something else\nthat has something in common", "start": 2760.773, "duration": 3.971}, {"text": "with one of these, that\ngives me an ion in common,", "start": 2764.744, "duration": 3.237}, {"text": "then because of Le\nChatelier, you're", "start": 2767.981, "duration": 1.501}, {"text": "going to drive the\nreaction the other way.", "start": 2769.482, "duration": 3.036}, {"text": "That precipitates, because\nit forms a solid BaSO4.", "start": 2772.518, "duration": 2.436}, {"text": "So I've just done that.", "start": 2774.954, "duration": 0.934}, {"text": "Right?", "start": 2775.888, "duration": 0.501}, {"text": "I've given you BaCl2 which\ngives you a source of Ba2 plus,", "start": 2776.389, "duration": 3.837}, {"text": "and how do you figure\nout if you were", "start": 2780.226, "duration": 1.535}, {"text": "given amounts what happens,\nwhat the new equilibrium is?", "start": 2781.761, "duration": 5.105}, {"text": "You use ICE.", "start": 2786.866, "duration": 1.101}, {"text": "Right?", "start": 2787.967, "duration": 0.501}, {"text": "You use the ICE tables.", "start": 2788.468, "duration": 3.003}, {"text": "OK.", "start": 2791.471, "duration": 1.101}, {"text": "And then finally, we talked\nabout acids and bases.", "start": 2792.572, "duration": 5.639}, {"text": "Oh, I really hate to erase\ndefects, but here we go.", "start": 2798.211, "duration": 6.373}, {"text": "Defects are gone.", "start": 2804.584, "duration": 0.934}, {"text": "Arrhenius, I'm so sorry.", "start": 2805.518, "duration": 2.503}, {"text": "That was painful.", "start": 2808.021, "duration": 2.035}, {"text": "And the last topic here\nis acids and bases,", "start": 2810.056, "duration": 4.671}, {"text": "and this is the most recent\none, and so what do we have?", "start": 2814.727, "duration": 7.441}, {"text": "Well, got the acid equilibrium\nconstant, the base.", "start": 2822.168, "duration": 4.738}, {"text": "We did water.", "start": 2826.906, "duration": 2.469}, {"text": "We did pH.", "start": 2829.375, "duration": 1.602}, {"text": "Oh, we did p anything.", "start": 2830.977, "duration": 2.269}, {"text": "Right?", "start": 2833.246, "duration": 0.6}, {"text": "p equals negative log\nof the thing, pKa, pKb.", "start": 2833.846, "duration": 6.04}, {"text": "OK, and then we did, like\nfor example, the definitions,", "start": 2843.056, "duration": 5.305}, {"text": "so Arrhenius versus\nBronsted-Lowry definitions.", "start": 2848.361, "duration": 8.742}, {"text": "And so for example, if you're\ngiven a solution-- this is one,", "start": 2857.103, "duration": 3.737}, {"text": "just a simple\nexample of an acid--", "start": 2860.84, "duration": 4.071}, {"text": "and it's HOCN, and\nyou're given the acid.", "start": 2864.911, "duration": 2.002}, {"text": "And you know the pH,\nso you're given that.", "start": 2866.913, "duration": 3.203}, {"text": "Then the pH from that\ninformation you can get that", "start": 2870.116, "duration": 6.039}, {"text": "the concentration of H plus--\nwhich is also a H3O plus--", "start": 2876.155, "duration": 4.305}, {"text": "is 1.7 times 10 to the\nminus 3 moles per liter.", "start": 2880.46, "duration": 5.805}, {"text": "That's from the pH,\nand if you have that,", "start": 2886.265, "duration": 5.873}, {"text": "then you can go to the\nKa definition, which", "start": 2892.138, "duration": 5.105}, {"text": "is H plus concentration OCN\nminus divided by the acid HOCN", "start": 2897.243, "duration": 9.143}, {"text": "concentration, and\nyou've got it all.", "start": 2906.386, "duration": 2.535}, {"text": "Because if you're right the\nequilibrium equation, which", "start": 2908.921, "duration": 3.838}, {"text": "is what Ka describes, the\nequilibrium of this acid", "start": 2912.759, "duration": 5.572}, {"text": "dissociating into\nions, dissociating", "start": 2918.331, "duration": 4.037}, {"text": "into H plus and OCN minus,\nand so you can get Ka.", "start": 2922.368, "duration": 2.97}, {"text": "OK.", "start": 2925.338, "duration": 0.5}, {"text": "So what I hope is that\nthis got us in the mood,", "start": 2925.838, "duration": 2.57}, {"text": "that this got us all kind of\non the right page with respect", "start": 2928.408, "duration": 2.535}, {"text": "to these topics.", "start": 2930.943, "duration": 0.701}, {"text": "You've got two days.", "start": 2931.644, "duration": 1.368}]

transcripts/24iPsnbS6_0.json

@@ -0,0 +1 @@
+[{"text": "MARKUS KLUTE: Welcome back\nto 8.20 Special Relativity.", "start": 7.56, "duration": 2.79}, {"text": "In this short\nvideo, you're going", "start": 10.35, "duration": 2.01}, {"text": "to see how special\nrelativity, here shown as SR,", "start": 12.36, "duration": 4.98}, {"text": "fits into the general\nlandscape of physics theories.", "start": 17.34, "duration": 3.72}, {"text": "Very likely you have listened\nto 8.01 last semester", "start": 21.06, "duration": 4.92}, {"text": "or some previous time\nin your career at MIT.", "start": 25.98, "duration": 3.48}, {"text": "And once we enter the discussion\nof special relativity,", "start": 29.46, "duration": 5.79}, {"text": "it might seem to you\nthat what you learned", "start": 35.25, "duration": 2.52}, {"text": "there was simply incorrect.", "start": 37.77, "duration": 2.4}, {"text": "A better way to look at this\nis that each of those physics", "start": 40.17, "duration": 3.78}, {"text": "theories, they have\na range of validity,", "start": 43.95, "duration": 3.63}, {"text": "a range in which the\ntheory works and describes", "start": 47.58, "duration": 4.38}, {"text": "physical phenomena.", "start": 51.96, "duration": 1.77}, {"text": "And so here in this\npicture, I'd like", "start": 53.73, "duration": 2.37}, {"text": "to point out that even\nspecial relativity has", "start": 56.1, "duration": 4.17}, {"text": "its own range of validity.", "start": 60.27, "duration": 2.22}, {"text": "But let's start with\nclassical mechanics.", "start": 62.49, "duration": 2.59}, {"text": "So classical mechanics\ndescribes the motion", "start": 65.08, "duration": 2.87}, {"text": "of objects, a collision of\nobjects, a rotation of objects.", "start": 67.95, "duration": 4.17}, {"text": "In 8.02, you are\nstudying electrodynamics.", "start": 72.12, "duration": 4.32}, {"text": "But you do that typically at MIT\nin those courses at velocities", "start": 76.44, "duration": 4.26}, {"text": "which are modest--", "start": 80.7, "duration": 0.9}, {"text": "small velocities,\nsmall velocities", "start": 81.6, "duration": 2.13}, {"text": "compared to the speed of light.", "start": 83.73, "duration": 2.22}, {"text": "Once you accelerate,\nonce you have velocities", "start": 85.95, "duration": 3.45}, {"text": "which are really, really large,\nthen the description breaks.", "start": 89.4, "duration": 4.14}, {"text": "The validity of those\ntheories breaks.", "start": 93.54, "duration": 2.28}, {"text": "And that's where special\nrelativity comes in.", "start": 95.82, "duration": 2.76}, {"text": "And it's especially\nimportant when", "start": 98.58, "duration": 1.71}, {"text": "you discuss very fast moving\nbodies, fast moving reference", "start": 100.29, "duration": 4.74}, {"text": "frames, or behavior of light.", "start": 105.03, "duration": 2.83}, {"text": "And so this is what\nspecial relativity does.", "start": 107.86, "duration": 2.01}, {"text": "The range of validity is\nbasically fast-moving phenomena", "start": 109.87, "duration": 5.15}, {"text": "with high speed.", "start": 115.02, "duration": 2.23}, {"text": "But special relativity\nby itself doesn't", "start": 117.25, "duration": 2.07}, {"text": "help you to understand,\nfor example,", "start": 119.32, "duration": 1.8}, {"text": "object of small scales.", "start": 121.12, "duration": 1.35}, {"text": "In order to have a\nproper description here,", "start": 122.47, "duration": 2.46}, {"text": "you need to study\nquantum mechanics.", "start": 124.93, "duration": 2.19}, {"text": "If you have object\nof very mass large", "start": 127.12, "duration": 2.549}, {"text": "or with large\naccelerations, you need", "start": 129.669, "duration": 3.181}, {"text": "to enter a generalized\nview, general relativity.", "start": 132.85, "duration": 5.82}, {"text": "And if you, for example,\ncombine high velocities", "start": 138.67, "duration": 2.85}, {"text": "and small scales, you have to\nstudy quantum field theories.", "start": 141.52, "duration": 4.23}, {"text": "So the point of\nthis slide is really", "start": 145.75, "duration": 2.19}, {"text": "to point out that special\nrelativity has a specific use", "start": 147.94, "duration": 3.34}, {"text": "case.", "start": 151.28, "duration": 0.5}, {"text": "It's limited.", "start": 151.78, "duration": 1.71}, {"text": "It describes\nfast-moving objects.", "start": 153.49, "duration": 2.85}, {"text": "It doesn't describe\nlarge accelerations.", "start": 156.34, "duration": 3.16}, {"text": "So that is the\ngeneralization you get when", "start": 159.5, "duration": 2.42}, {"text": "you study general relativity.", "start": 161.92, "duration": 3.6}, {"text": "So in summary,\nspecial relativity", "start": 165.52, "duration": 2.09}, {"text": "is a complete description\nof physical phenomena", "start": 167.61, "duration": 3.45}, {"text": "at high speed.", "start": 171.06, "duration": 1.38}, {"text": "It is consistent\nwith 8.01 and 8.02.", "start": 172.44, "duration": 2.25}, {"text": "And you will later see that\nwhenever we find integration", "start": 174.69, "duration": 3.45}, {"text": "of motion for object\nat high speed,", "start": 178.14, "duration": 5.21}, {"text": "if we use smaller\nvelocities, we'll", "start": 183.35, "duration": 3.25}, {"text": "find the solutions\nof 8.01 and 8.02.", "start": 186.6, "duration": 4.218}, {"text": "When we combine\nspecial relativity", "start": 190.818, "duration": 3.072}, {"text": "with quantum mechanics,\nit describes quantum field", "start": 193.89, "duration": 2.28}, {"text": "theories.", "start": 196.17, "duration": 0.9}, {"text": "And as I was saying,\nthe generalization", "start": 197.07, "duration": 2.43}, {"text": "of special relativity, SR,\nis general relativity, GR.", "start": 199.5, "duration": 4.85}]

transcripts/2NMtS1ecb3o.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 1.936}, {"text": "[RUSTLING]", "start": 1.936, "duration": 1.452}, {"text": "[CLICKING]", "start": 3.388, "duration": 1.936}, {"text": "JASON KU: Welcome, everybody,\nto the second-to-last lecture", "start": 13.08, "duration": 3.24}, {"text": "of 6.006.", "start": 16.32, "duration": 2.67}, {"text": "In this lecture,\nwe've mostly covered", "start": 18.99, "duration": 2.88}, {"text": "all of the testable\nmaterial that we're", "start": 21.87, "duration": 2.7}, {"text": "going to have on the\nfinal, or on quiz 3.", "start": 24.57, "duration": 6.21}, {"text": "Today, really what\nwe're talking about", "start": 30.78, "duration": 1.949}, {"text": "is putting into context\nall the material", "start": 32.729, "duration": 2.821}, {"text": "that we've learned over\nthe course of the term", "start": 35.55, "duration": 4.37}, {"text": "at a high level and talk about\nwhere we can go from here", "start": 39.92, "duration": 4.32}, {"text": "in terms of other theory\nclasses and other classes", "start": 44.24, "duration": 2.82}, {"text": "in the department that are\nrelated to this material.", "start": 47.06, "duration": 2.28}, {"text": "Now, most things\nin the department", "start": 49.34, "duration": 2.4}, {"text": "are in some way related\nto this material.", "start": 51.74, "duration": 2.5}, {"text": "And so that's why there's\na foundational course.", "start": 54.24, "duration": 2.805}, {"text": "But we're going to try to talk\nabout it from a high level", "start": 57.045, "duration": 2.375}, {"text": "and talk about how some\nfuture things that you", "start": 59.42, "duration": 5.849}, {"text": "might be interested relate.", "start": 65.269, "duration": 1.421}, {"text": "OK, so we started out\nthe term, in lecture one,", "start": 66.69, "duration": 4.73}, {"text": "talking about 6.006, and\nwe had four main goals", "start": 71.42, "duration": 4.05}, {"text": "that we had for our course--\nreally three main goals", "start": 75.47, "duration": 5.64}, {"text": "Does anyone remember\nwhat those goals were?", "start": 81.11, "duration": 2.43}, {"text": "So you got to the\nlast one first.", "start": 89.16, "duration": 2.52}, {"text": "The first one was to solve\nhard computational problems,", "start": 91.68, "duration": 4.32}, {"text": "to be able to solve problems.", "start": 96.0, "duration": 3.06}, {"text": "So this is kind of like the\n\"let's make an algorithm\"", "start": 99.06, "duration": 4.65}, {"text": "part of the course.", "start": 103.71, "duration": 2.58}, {"text": "1, solve hard\ncomputational problems.", "start": 106.29, "duration": 4.845}, {"text": "I guess \"hard\" here maybe\nshould be in quotes because we", "start": 116.62, "duration": 4.11}, {"text": "saw in the last\nlecture what hard", "start": 120.73, "duration": 2.28}, {"text": "means in a technical sense.", "start": 123.01, "duration": 2.67}, {"text": "Hard could mean that there's\nno efficient algorithm that we", "start": 125.68, "duration": 5.67}, {"text": "know how to solve a problem on.", "start": 131.35, "duration": 1.787}, {"text": "That's getting a little\nbit of ahead of ourselves.", "start": 133.137, "duration": 2.083}, {"text": "Computational problems\nwith algorithms", "start": 135.22, "duration": 2.43}, {"text": "is really the key\npart about this goal.", "start": 137.65, "duration": 2.37}, {"text": "It's kind of the\nsame goal that you", "start": 140.02, "duration": 1.65}, {"text": "have in a class like\n6.0001 or 6.009.", "start": 141.67, "duration": 4.56}, {"text": "You're trying to\nconvince a computer", "start": 146.23, "duration": 2.16}, {"text": "that you solved a problem\non a finite set of inputs.", "start": 148.39, "duration": 6.54}, {"text": "But really what\nthis class is about", "start": 154.93, "duration": 2.25}, {"text": "is two other things, which\nis more about communication", "start": 157.18, "duration": 4.5}, {"text": "to people rather than computers.", "start": 161.68, "duration": 2.52}, {"text": "Your algorithm might be\ncorrect or efficient,", "start": 164.2, "duration": 3.81}, {"text": "but you need to be able to\ncommunicate that to humans.", "start": 168.01, "duration": 2.25}, {"text": "And that's what the\nother two goals are.", "start": 170.26, "duration": 2.46}, {"text": "So second one is\nargue correctness.", "start": 172.72, "duration": 8.43}, {"text": "Basically, the thing that\nI'm doing to my inputs", "start": 181.15, "duration": 4.47}, {"text": "is always going to lead\nme to a correct output.", "start": 185.62, "duration": 2.235}, {"text": "No matter what input I\ngive it, any valid input--", "start": 190.58, "duration": 2.56}, {"text": "there could be an infinite\nspace of possible inputs,", "start": 193.14, "duration": 3.6}, {"text": "and in this class,\nthat's the case,", "start": 196.74, "duration": 1.59}, {"text": "because we want our input size\nto grow arbitrarily large--", "start": 198.33, "duration": 4.44}, {"text": "we need to be able\nto argue correctness", "start": 202.77, "duration": 1.89}, {"text": "that it's going to return\nme the correct thing", "start": 204.66, "duration": 2.28}, {"text": "no matter what my inputs are.", "start": 206.94, "duration": 2.53}, {"text": "And in order to do that, that's\nessentially-- that's 6.042.", "start": 209.47, "duration": 4.67}, {"text": "This whole class has\nbasically been applied 6.042.", "start": 214.14, "duration": 4.8}, {"text": "I've given you some\nprocedures, and you", "start": 218.94, "duration": 3.42}, {"text": "have to prove things\nabout these procedures.", "start": 222.36, "duration": 1.89}, {"text": "Or most of the time,\nwe proved it for you,", "start": 224.25, "duration": 2.85}, {"text": "and then you've used\nthem as black boxes.", "start": 227.1, "duration": 2.31}, {"text": "But that's a lot of what\nthis class is about.", "start": 229.41, "duration": 4.68}, {"text": "And the third one\nis efficiency--", "start": 234.09, "duration": 1.94}, {"text": "argue that it's \"good,\"\nfor lack of a better thing.", "start": 238.61, "duration": 4.09}, {"text": "This is efficiency.", "start": 242.7, "duration": 1.63}, {"text": "What does \"good\" mean?", "start": 244.33, "duration": 2.69}, {"text": "Well, that was hard to know\nat the beginning of our class.", "start": 247.02, "duration": 3.48}, {"text": "And so we set up this model\nof computation, a framework,", "start": 250.5, "duration": 3.65}, {"text": "through which we could\ndetermine how good or bad", "start": 254.15, "duration": 3.99}, {"text": "our algorithms were by saying--", "start": 258.14, "duration": 2.1}, {"text": "by defining a model of\ncomputation, saying what things", "start": 260.24, "duration": 3.27}, {"text": "we can do in constant time, and\nthen just building off of that.", "start": 263.51, "duration": 4.65}, {"text": "So this is basically our\nmodel plus some asymptotics", "start": 268.16, "duration": 7.202}, {"text": "or something like that.", "start": 275.362, "duration": 0.958}, {"text": "Ran out of space.", "start": 279.84, "duration": 1.51}, {"text": "What?", "start": 281.35, "duration": 0.69}, {"text": "AUDIENCE: It's\nabout scalability.", "start": 282.04, "duration": 1.375}, {"text": "JASON KU: Yeah, this\nis about scalability.", "start": 283.415, "duration": 2.635}, {"text": "A model of computation tells\nus how much time we can spend,", "start": 286.05, "duration": 4.26}, {"text": "but it's compared\nto our input size.", "start": 290.31, "duration": 3.03}, {"text": "This is always about,\nhow does our algorithm", "start": 293.34, "duration": 3.51}, {"text": "perform relative to the rate\nthat our problem size grows?", "start": 296.85, "duration": 4.92}, {"text": "And so that's what\nwe mean by \"good.\"", "start": 301.77, "duration": 2.01}, {"text": "And in this class, we don't\ntend to talk about constant size", "start": 303.78, "duration": 3.81}, {"text": "problems.", "start": 307.59, "duration": 1.02}, {"text": "It's about how algorithms\ncan scale as you", "start": 308.61, "duration": 4.02}, {"text": "have arbitrarily large inputs.", "start": 312.63, "duration": 1.8}, {"text": "That's why we need\nrecursion and induction", "start": 314.43, "duration": 2.8}, {"text": "to be able to prove things\nabout our algorithms,", "start": 317.23, "duration": 2.0}, {"text": "because they're for arbitrary n.", "start": 319.23, "duration": 2.73}, {"text": "And that's why we need this\nrelative-to-input size,", "start": 321.96, "duration": 5.49}, {"text": "the growth factor of our\nalgorithm's performance,", "start": 327.45, "duration": 4.11}, {"text": "relative to the input.", "start": 331.56, "duration": 1.9}, {"text": "OK, and then the\nlast thing is, to me,", "start": 333.46, "duration": 5.91}, {"text": "one of the most\nimportant things,", "start": 339.37, "duration": 2.0}, {"text": "is communicating these\nthings to another human.", "start": 341.37, "duration": 3.66}, {"text": "So communication is key here.", "start": 345.03, "duration": 6.42}, {"text": "If you can always\nwrite good code", "start": 351.45, "duration": 2.13}, {"text": "that's always\nright, good for you.", "start": 353.58, "duration": 2.91}, {"text": "I can't do that all the time.", "start": 356.49, "duration": 3.44}, {"text": "But that might mean\nthat you can be very--", "start": 359.93, "duration": 4.38}, {"text": "a competent, independent\ncomputer programmer.", "start": 364.31, "duration": 4.47}, {"text": "But you are going to be limited\nin what you can do if you're", "start": 368.78, "duration": 5.73}, {"text": "only able to rely on yourself.", "start": 374.51, "duration": 3.63}, {"text": "A lot about computer science\nis working with others", "start": 378.14, "duration": 3.87}, {"text": "to solve computational problems.", "start": 382.01, "duration": 1.662}, {"text": "And when you're\nworking with others", "start": 383.672, "duration": 1.458}, {"text": "to solve computational\nproblems, you", "start": 385.13, "duration": 2.162}, {"text": "need to be able to\ncommunicate with them,", "start": 387.292, "duration": 1.708}, {"text": "and you need to be able\nto communicate them both", "start": 389.0, "duration": 2.49}, {"text": "what it is you're doing and\nwhy it is you're doing it--", "start": 391.49, "duration": 5.1}, {"text": "that you're doing the correct\nthing and that it's efficient.", "start": 396.59, "duration": 3.7}, {"text": "And so that's a big part\nabout what this course is.", "start": 400.29, "duration": 3.74}, {"text": "At the end of the\nday, on your quiz,", "start": 404.03, "duration": 2.31}, {"text": "if you write down Python\nscript for a correct algorithm,", "start": 406.34, "duration": 6.39}, {"text": "but we don't know\nwhat it's doing,", "start": 412.73, "duration": 1.98}, {"text": "but it's correct,\nwe're not going", "start": 414.71, "duration": 1.98}, {"text": "to give you full points on that,\nbecause you're not satisfying", "start": 416.69, "duration": 4.44}, {"text": "the conditions of this class.", "start": 421.13, "duration": 3.06}, {"text": "It's really about the\ncommunication here.", "start": 424.19, "duration": 2.42}, {"text": "OK, so just to review,\nsince we've not", "start": 426.61, "duration": 5.23}, {"text": "discussed how the most recent\nlecture fits into your problem", "start": 431.84, "duration": 6.12}, {"text": "sets.", "start": 437.96, "duration": 0.72}, {"text": "We didn't have any problem\nsets that covered complexity,", "start": 438.68, "duration": 5.39}, {"text": "so how does that fit in?", "start": 444.07, "duration": 1.25}, {"text": "Well, argue that the ways that\nwe're solving our problems", "start": 445.32, "duration": 3.45}, {"text": "are good.", "start": 448.77, "duration": 1.14}, {"text": "What we proved in the last\nlecture was that most problems", "start": 449.91, "duration": 2.73}, {"text": "cannot be solved good.", "start": 452.64, "duration": 3.32}, {"text": "They can't be solved\nin polynomial time", "start": 455.96, "duration": 2.76}, {"text": "with respect to the\nsize of your input.", "start": 458.72, "duration": 2.62}, {"text": "However, most of the\nproblems that we think about,", "start": 461.34, "duration": 4.67}, {"text": "in a sense, I can prove to\nyou that it's a yes solution.", "start": 466.01, "duration": 5.82}, {"text": "I can show you a simple\npath in this graph that", "start": 471.83, "duration": 4.08}, {"text": "has a certain length.", "start": 475.91, "duration": 2.01}, {"text": "Or I can show you a subset\nthat sums to a certain value", "start": 477.92, "duration": 3.84}, {"text": "in a particular problem.", "start": 481.76, "duration": 1.56}, {"text": "I can give you a\ncertificate that I", "start": 483.32, "duration": 1.83}, {"text": "can prove to you in a\nreasonable amount of time", "start": 485.15, "duration": 2.91}, {"text": "that, yes, I can\nprove to you that this", "start": 488.06, "duration": 2.16}, {"text": "is-- the answer to\nthis thing is correct.", "start": 490.22, "duration": 2.67}, {"text": "And that's what we talked\nabout in the last lecture.", "start": 492.89, "duration": 3.99}, {"text": "So not always \"good\"\nalgorithms to solve problems,", "start": 496.88, "duration": 23.33}, {"text": "but many problems we think\nabout can be either checked", "start": 520.21, "duration": 22.06}, {"text": "in polynomial time--", "start": 542.27, "duration": 2.73}, {"text": "this is the concept of having\na certificate that I could give", "start": 548.48, "duration": 3.24}, {"text": "you of polynomial\nsize that could", "start": 551.72, "duration": 1.89}, {"text": "be checked in polynomial time--", "start": 553.61, "duration": 2.43}, {"text": "in a sense, that's a way--", "start": 556.04, "duration": 2.62}, {"text": "check-- checked in\npolynomial time.", "start": 558.66, "duration": 3.86}, {"text": "This leads to our class\nof decision problems, NP.", "start": 562.52, "duration": 4.05}, {"text": "Or it can be solved by brute\nforce in exponential time.", "start": 566.57, "duration": 13.62}, {"text": "Most of the things that we've\ntalked about in this class", "start": 580.19, "duration": 2.46}, {"text": "fall into one of\nthese two categories.", "start": 582.65, "duration": 2.38}, {"text": "We can just brute force\nover the combinatorial space", "start": 585.03, "duration": 2.51}, {"text": "of possible outputs and check\nto see if they're correct.", "start": 587.54, "duration": 4.19}, {"text": "Or I can give you a certificate\nbasically saying, look,", "start": 591.73, "duration": 6.82}, {"text": "I can solve--", "start": 598.55, "duration": 0.65}, {"text": "actually, anything\nthat's of this form", "start": 599.2, "duration": 1.737}, {"text": "can be checked in this\nform, because there's", "start": 600.937, "duration": 1.833}, {"text": "only a polynomial number of\nthings to check-- or, sorry,", "start": 602.77, "duration": 2.8}, {"text": "an exponential possible\nnumber of certificates", "start": 605.57, "duration": 2.54}, {"text": "of polynomial length to check.", "start": 608.11, "duration": 2.4}, {"text": "But basically, this is\nsaying that the problems", "start": 610.51, "duration": 2.94}, {"text": "that we think of mostly fall\ninto these two categories.", "start": 613.45, "duration": 3.64}, {"text": "And so there usually\nare algorithms to solve", "start": 617.09, "duration": 3.17}, {"text": "the problems that\nwe care about, even", "start": 620.26, "duration": 4.45}, {"text": "if most random problems\nin terms of bit strings", "start": 624.71, "duration": 4.8}, {"text": "that we gave an analysis\nin the last lecture", "start": 629.51, "duration": 2.97}, {"text": "actually prove that most random\nproblems are not solvable.", "start": 632.48, "duration": 3.57}, {"text": "In a sense, the problems we\nthink about are not random.", "start": 638.57, "duration": 3.61}, {"text": "They kind of have this\nstructure that they", "start": 642.18, "duration": 1.79}, {"text": "can be checked pretty quickly.", "start": 643.97, "duration": 2.36}, {"text": "OK, so that's what\nwe mean when we", "start": 646.33, "duration": 3.4}, {"text": "are talking about complexity.", "start": 649.73, "duration": 1.8}, {"text": "For the purposes of\nthe final, you'll", "start": 651.53, "duration": 2.52}, {"text": "be able to see on your\nfinal exam practice problems", "start": 654.05, "duration": 5.1}, {"text": "that we're going to give you,\nmost of what we cover in terms", "start": 659.15, "duration": 6.3}, {"text": "of material on the final\nthat will be testing", "start": 665.45, "duration": 3.75}, {"text": "the lecture 19 material will\nbe in terms of the definitions.", "start": 669.2, "duration": 5.25}, {"text": "Do you understand what the\ndecision problem class NP is?", "start": 674.45, "duration": 4.89}, {"text": "EXP is?", "start": 679.34, "duration": 1.29}, {"text": "Do you know how these\nrelate to each other?", "start": 680.63, "duration": 2.04}, {"text": "EXP is definitely a\nsuperset of NP here.", "start": 682.67, "duration": 4.95}, {"text": "NP nestles inside here.", "start": 687.62, "duration": 1.65}, {"text": "They could be\nequal-- probably not.", "start": 689.27, "duration": 2.58}, {"text": "Those are the types of\nthings that we would address.", "start": 691.85, "duration": 3.63}, {"text": "Knowing a directionality\nof a reduction.", "start": 695.48, "duration": 3.21}, {"text": "If you have a problem\nA and a problem", "start": 698.69, "duration": 5.64}, {"text": "B, and I know that this one\nis difficult by some measure--", "start": 704.33, "duration": 8.96}, {"text": "I already happened to\nknow that it's very hard,", "start": 713.29, "duration": 3.78}, {"text": "like NP-hard or\nsomething like that.", "start": 717.07, "duration": 2.43}, {"text": "If this is a problem that\nI'm interested in knowing", "start": 719.5, "duration": 3.33}, {"text": "the complexity about,\nand I can prove", "start": 722.83, "duration": 2.73}, {"text": "that I can solve it if I\nhad a black box to solve B--", "start": 725.56, "duration": 6.15}, {"text": "any black box to\nsolve B, and I could", "start": 731.71, "duration": 2.22}, {"text": "make this reduction\nin polynomial time,", "start": 733.93, "duration": 3.32}, {"text": "and if this is hard, that\nmeans this can't be--", "start": 737.25, "duration": 3.98}, {"text": "that means that if\nthis is hard, then", "start": 743.77, "duration": 2.4}, {"text": "I better not be able to solve\nthis in polynomial time,", "start": 746.17, "duration": 3.69}, {"text": "because then I would be able to\nsolve this in polynomial time.", "start": 749.86, "duration": 2.65}, {"text": "So that's basically\nthe type of argument", "start": 752.51, "duration": 3.32}, {"text": "usually in a\ntrue/false question we", "start": 755.83, "duration": 1.77}, {"text": "might have on the\nfinal exam for you", "start": 757.6, "duration": 2.85}, {"text": "to kind of understand the basic\nhigh-level definitions involved", "start": 760.45, "duration": 4.68}, {"text": "in what was talked\nabout in lecture 19.", "start": 765.13, "duration": 4.02}, {"text": "Hardness-- the very most\ndifficult problems of these", "start": 769.15, "duration": 3.72}, {"text": "classes--", "start": 772.87, "duration": 0.72}, {"text": "and completeness--\nsorry, anything harder", "start": 773.59, "duration": 3.75}, {"text": "than things in these classes.", "start": 777.34, "duration": 1.95}, {"text": "Whereas completeness is\nthe ones that are in this", "start": 779.29, "duration": 3.03}, {"text": "set, but at least as hard as\nanything in those classes.", "start": 782.32, "duration": 3.57}, {"text": "So that's just to give\nyou a brief overview", "start": 785.89, "duration": 3.45}, {"text": "of the only material\nthat hasn't been tested", "start": 789.34, "duration": 3.36}, {"text": "but might be tested\non the final.", "start": 792.7, "duration": 3.21}, {"text": "So when we don't have\na good algorithm,", "start": 795.91, "duration": 4.17}, {"text": "we can actually prove\nthat it probably", "start": 800.08, "duration": 4.74}, {"text": "doesn't have a good algorithm.", "start": 804.82, "duration": 2.37}, {"text": "And that's a problem\nthat you'll be", "start": 807.19, "duration": 2.94}, {"text": "able to solve in\nfuture classes, if you", "start": 810.13, "duration": 2.46}, {"text": "continue along this track.", "start": 812.59, "duration": 1.78}, {"text": "OK, so what's the actual\ncontent that we talked about?", "start": 814.37, "duration": 4.34}, {"text": "This is a very\nhigh-level overview", "start": 818.71, "duration": 1.68}, {"text": "of why we're taking this class,\nwhy you're taking this class.", "start": 820.39, "duration": 3.27}, {"text": "But what is the content\nwe actually covered?", "start": 823.66, "duration": 2.91}, {"text": "I like to break it up into\nthree units and, in a sense,", "start": 826.57, "duration": 5.77}, {"text": "two subunits.", "start": 832.34, "duration": 1.95}, {"text": "So quiz 1 material and quiz 2\nmaterial was about showing you", "start": 834.29, "duration": 10.02}, {"text": "some nice black boxes.", "start": 844.31, "duration": 2.1}, {"text": "Basically, if I'm going to have\ninputs of non-constant size,", "start": 846.41, "duration": 3.81}, {"text": "it's going to be useful for\nme to be able to find things", "start": 850.22, "duration": 3.78}, {"text": "among those elements.", "start": 854.0, "duration": 2.24}, {"text": "So that's really what\nquiz 1 is all about--", "start": 856.24, "duration": 3.67}, {"text": "data structures\nfor finding things", "start": 859.91, "duration": 10.41}, {"text": "in non-constant size database.", "start": 870.32, "duration": 17.92}, {"text": "Sure.", "start": 888.24, "duration": 0.85}, {"text": "And when we were\nstoring these things,", "start": 889.09, "duration": 2.07}, {"text": "we want to support maybe two\ndifferent types of queries--", "start": 891.16, "duration": 3.135}, {"text": "ones that were intrinsic to\nthe items, what the items were,", "start": 899.52, "duration": 4.44}, {"text": "and ones based on what--\nan extrinsic order", "start": 903.96, "duration": 3.18}, {"text": "was placed on these items.", "start": 907.14, "duration": 3.21}, {"text": "And that was a way in\nwhich we broke down,", "start": 910.35, "duration": 3.033}, {"text": "how should I approach\nlooking at this problem?", "start": 913.383, "duration": 1.917}, {"text": "I want to be able to\nsupport queries and maintain", "start": 915.3, "duration": 2.97}, {"text": "an extrinsic order\non these things.", "start": 918.27, "duration": 1.65}, {"text": "I might want a sequence.", "start": 919.92, "duration": 2.17}, {"text": "This is a sequence\nextrinsic order.", "start": 922.09, "duration": 8.0}, {"text": "Or I want to be able to look\nup, is this thing in my set,", "start": 933.03, "duration": 6.13}, {"text": "by a key that we identify,\nwith a unique key.", "start": 939.16, "duration": 4.48}, {"text": "So this is some intrinsic\nqueries, and often order.", "start": 943.64, "duration": 7.29}, {"text": "A hash table doesn't maintain\nany order on my keys.", "start": 954.69, "duration": 4.35}, {"text": "But it does support\nintrinsic queries--", "start": 959.04, "duration": 1.89}, {"text": "is this thing in my set or not?", "start": 960.93, "duration": 1.99}, {"text": "But we did show you\nother set data structures", "start": 962.92, "duration": 2.48}, {"text": "that do support an\nintrinsic order that", "start": 965.4, "duration": 2.76}, {"text": "allows me to see what the next\nlarger and the next previous--", "start": 968.16, "duration": 4.17}, {"text": "the next larger and the next\nsmaller item is in my set.", "start": 972.33, "duration": 7.81}, {"text": "So here's a summary of those\ndata structures that we had.", "start": 980.14, "duration": 4.87}, {"text": "I'm not going to go into\nhow to use these things", "start": 985.01, "duration": 3.09}, {"text": "or how to choose\nfrom among them here.", "start": 988.1, "duration": 2.64}, {"text": "That's what your quiz 1\nreview lecture was all about.", "start": 990.74, "duration": 5.97}, {"text": "But basically, the idea here\nis, if we have a sequence,", "start": 996.71, "duration": 3.97}, {"text": "most of the time when\nyou're programming,", "start": 1000.68, "duration": 3.4}, {"text": "being able to push and\npop at the end of a list", "start": 1004.08, "duration": 3.24}, {"text": "is pretty good.", "start": 1007.32, "duration": 0.87}, {"text": "Which is why Python, the\nmost fundamental data", "start": 1008.19, "duration": 3.15}, {"text": "structure that you have,\nis a list, because it's", "start": 1011.34, "duration": 3.21}, {"text": "a super useful thing.", "start": 1014.55, "duration": 1.26}, {"text": "I just want to store\na bunch of things,", "start": 1015.81, "duration": 1.89}, {"text": "have random access to the,\nsay, 10th element to my thing,", "start": 1017.7, "duration": 6.81}, {"text": "but I'm not necessarily\nhaving to dynamically update", "start": 1024.51, "duration": 4.53}, {"text": "the order of these\nthings dynamically.", "start": 1029.04, "duration": 4.14}, {"text": "I don't necessarily\nhave to insert something", "start": 1033.18, "duration": 2.04}, {"text": "in the middle of the list.", "start": 1035.22, "duration": 1.47}, {"text": "But most of the\ntime, what I can do", "start": 1036.69, "duration": 1.649}, {"text": "is put it at the end of the\nlist and maybe swap it down", "start": 1038.339, "duration": 3.451}, {"text": "into place if I need to.", "start": 1041.79, "duration": 2.579}, {"text": "So that's why a list\nis super useful.", "start": 1044.369, "duration": 2.46}, {"text": "A sequence AVL tree,\nuseful, but not", "start": 1046.829, "duration": 4.801}, {"text": "as ubiquitous as a linked list--", "start": 1051.63, "duration": 1.89}, {"text": "I mean, as a dynamic\narray, sorry.", "start": 1053.52, "duration": 2.43}, {"text": "I said linked list,\nI meant Python list,", "start": 1055.95, "duration": 2.88}, {"text": "which is a dynamic array.", "start": 1058.83, "duration": 2.31}, {"text": "So the dynamic\narray tended to be,", "start": 1061.14, "duration": 2.28}, {"text": "in your coding practice, your\nmost common sequence data", "start": 1063.42, "duration": 4.5}, {"text": "structure here.", "start": 1067.92, "duration": 1.08}, {"text": "Though, we can get pretty\ngood for this insert", "start": 1069.0, "duration": 3.39}, {"text": "in the middle operation\nwith the sequence AVL.", "start": 1072.39, "duration": 2.94}, {"text": "OK, then on the set\ndata structure side,", "start": 1075.33, "duration": 3.63}, {"text": "I categorize these things into\na couple different categories", "start": 1078.96, "duration": 4.265}, {"text": "here in terms of the operations\nwe can support on these things.", "start": 1083.225, "duration": 2.625}, {"text": "These are all intrinsic\noperations-- finding things,", "start": 1085.85, "duration": 2.8}, {"text": "inserting, deleting things.", "start": 1088.65, "duration": 1.53}, {"text": "I think of the first three as\nbeing dictionary operations.", "start": 1090.18, "duration": 4.41}, {"text": "I want to just look up\nwhether something's there.", "start": 1094.59, "duration": 4.11}, {"text": "Whereas the last two are\norder-preserving operations,", "start": 1098.7, "duration": 5.22}, {"text": "where it matters what the order\nof these things are stored in.", "start": 1103.92, "duration": 4.14}, {"text": "And so as you can see from\nthe asymptotic complexity", "start": 1108.06, "duration": 6.54}, {"text": "of the various operations\nhere, the hash table", "start": 1114.6, "duration": 2.73}, {"text": "is actually super good if you\nwant the dictionary oper--", "start": 1117.33, "duration": 3.36}, {"text": "if you just want to support\ndictionary operations.", "start": 1120.69, "duration": 3.79}, {"text": "But in the cases where you need\nto maintain order dynamically,", "start": 1124.48, "duration": 3.68}, {"text": "a set AVL is the way to go.", "start": 1128.16, "duration": 3.43}, {"text": "But if you don't\nneed it dynamic,", "start": 1131.59, "duration": 1.41}, {"text": "but you still need\nthose order operations,", "start": 1133.0, "duration": 1.98}, {"text": "a sorted array is\njust good enough", "start": 1134.98, "duration": 2.01}, {"text": "if you don't need to\nchange what they are.", "start": 1136.99, "duration": 2.61}, {"text": "So that's a quick overview of\nquiz 1-type data structures", "start": 1139.6, "duration": 7.47}, {"text": "material.", "start": 1147.07, "duration": 1.32}, {"text": "But then we used most\nof these data structures", "start": 1148.39, "duration": 3.36}, {"text": "to get faster sorting algorithms\nin different contexts.", "start": 1151.75, "duration": 3.335}, {"text": "Basically, everything\non this list", "start": 1158.76, "duration": 2.25}, {"text": "involved making a data structure\nand exploiting that data", "start": 1161.01, "duration": 4.65}, {"text": "structure to get a\nbetter running time,", "start": 1165.66, "duration": 1.8}, {"text": "all except for\nmerge sort, really.", "start": 1167.46, "duration": 3.32}, {"text": "The first two we presented\nin terms of a priority queue,", "start": 1170.78, "duration": 4.95}, {"text": "whether we used a sorted\narray or an array.", "start": 1175.73, "duration": 2.97}, {"text": "We represented it at\nthe end of lecture eight", "start": 1178.7, "duration": 6.1}, {"text": "to get n-squared running time.", "start": 1184.8, "duration": 1.8}, {"text": "We generalized that down\nto n log n by using a heap.", "start": 1186.6, "duration": 3.78}, {"text": "That was a nice optimization.", "start": 1190.38, "duration": 2.1}, {"text": "But we also got interesting\ndata structures using an--", "start": 1192.48, "duration": 4.38}, {"text": "I mean, interesting sorting\nalgorithms using an AVL tree", "start": 1196.86, "duration": 3.87}, {"text": "because of the\npower of maintaining", "start": 1200.73, "duration": 1.98}, {"text": "a dynamic order over time.", "start": 1202.71, "duration": 2.58}, {"text": "But then exploiting a direct\naccess array to be able to sort", "start": 1205.29, "duration": 5.79}, {"text": "in linear time for\nsmall-bounded--", "start": 1211.08, "duration": 3.78}, {"text": "bounded in terms of\nthe input, polynomially", "start": 1214.86, "duration": 2.67}, {"text": "bounded in terms of the\ninput-- ranges of numbers.", "start": 1217.53, "duration": 3.09}, {"text": "So we leverage that direct axis\narray to get counting sort.", "start": 1220.62, "duration": 5.13}, {"text": "And then we kind of\namplified that effect", "start": 1225.75, "duration": 4.56}, {"text": "by sorting on a bunch\nof digits multiple times", "start": 1230.31, "duration": 4.08}, {"text": "to get basically polynomial\nblow-up in terms of the numbers", "start": 1234.39, "duration": 4.53}, {"text": "that we could sort\nin linear time.", "start": 1238.92, "duration": 2.65}, {"text": "So that's an overview of\nthe content of quiz 1.", "start": 1241.57, "duration": 4.956}, {"text": "In quiz 2, we were kind\nof like, OK, now you", "start": 1246.526, "duration": 4.954}, {"text": "know how to find things\nwithin a set of just", "start": 1251.48, "duration": 5.73}, {"text": "a flat list of things, you can\nput it in a data structure.", "start": 1257.21, "duration": 3.21}, {"text": "But in a sense, a graph is a\nspecial kind of data structure", "start": 1260.42, "duration": 4.29}, {"text": "that relates the different\nthings in your input.", "start": 1264.71, "duration": 4.23}, {"text": "So if you've got a\nbunch of vertices,", "start": 1268.94, "duration": 5.13}, {"text": "there's a relation now\nbetween those vertices", "start": 1274.07, "duration": 3.03}, {"text": "that are your edges.", "start": 1277.1, "duration": 1.3}, {"text": "And this is a super\nuseful framework", "start": 1278.4, "duration": 2.24}, {"text": "in talking about\ndiscrete systems,", "start": 1280.64, "duration": 2.34}, {"text": "because you can\nthink of a vertex", "start": 1282.98, "duration": 2.07}, {"text": "as a state of your system, and\nthen connect these transitions", "start": 1285.05, "duration": 4.11}, {"text": "as a graph.", "start": 1289.16, "duration": 1.26}, {"text": "That's the reason why--", "start": 1290.42, "duration": 2.61}, {"text": "I mean, graphs are\nawesome, but they're", "start": 1293.03, "duration": 2.94}, {"text": "awesome because they\ncan be used to model", "start": 1295.97, "duration": 2.17}, {"text": "so many different\nthings within our world.", "start": 1298.14, "duration": 2.45}, {"text": "It's not just about\nroad networks.", "start": 1300.59, "duration": 3.9}, {"text": "It can also be about playing\nyour favorite turn-based game,", "start": 1304.49, "duration": 5.38}, {"text": "like Tilt.", "start": 1309.87, "duration": 1.8}, {"text": "OK, so we talked about a lot\nof different types of problems", "start": 1311.67, "duration": 3.86}, {"text": "that you could solve,\nvarious algorithms,", "start": 1315.53, "duration": 1.8}, {"text": "with a focus on a bunch of\ndifferent ways of solving", "start": 1317.33, "duration": 3.96}, {"text": "single-source shortest paths.", "start": 1321.29, "duration": 2.34}, {"text": "And again, just like\nthe sorting algorithms", "start": 1323.63, "duration": 1.943}, {"text": "and just like the\ndata structures,", "start": 1325.573, "duration": 1.417}, {"text": "we presented multiple\nof them, because we", "start": 1326.99, "duration": 3.93}, {"text": "had this trade-off of\ngenerality of the graph", "start": 1330.92, "duration": 3.39}, {"text": "that they apply to contrasted\nwith the running time.", "start": 1334.31, "duration": 4.93}, {"text": "So I guess, in\nparticular, the top line", "start": 1339.24, "duration": 7.55}, {"text": "there is, in some sense,\nthe most restrictive.", "start": 1346.79, "duration": 2.82}, {"text": "We don't have any\ncycles in our graph.", "start": 1349.61, "duration": 1.89}, {"text": "That's a very special\ntype of graph,", "start": 1351.5, "duration": 1.5}, {"text": "and we're able to\nget linear time.", "start": 1353.0, "duration": 3.08}, {"text": "But then even if we do\nhave cycles in our graph,", "start": 1356.08, "duration": 2.1}, {"text": "we can do better if we\nhave a bound on the weights", "start": 1358.18, "duration": 3.24}, {"text": "in our thing, whether they be--", "start": 1361.42, "duration": 3.84}, {"text": "there's an easy conversion\nto a linear time algorithm", "start": 1365.26, "duration": 2.49}, {"text": "via an unweighted process,\nor whether these things are", "start": 1367.75, "duration": 3.42}, {"text": "non-negative, so there can't\nbe negative weight cycles,", "start": 1371.17, "duration": 2.31}, {"text": "and we don't have\nto deal with that.", "start": 1373.48, "duration": 1.56}, {"text": "OK, so that's quiz 2 material.", "start": 1375.04, "duration": 3.93}, {"text": "And then quiz 3\nmaterial was kind", "start": 1378.97, "duration": 3.3}, {"text": "of applying this graph material\nto a recursive framework.", "start": 1382.27, "duration": 5.64}, {"text": "What was our\nrecursive framework?", "start": 1387.91, "duration": 1.53}, {"text": "Everyone say it with me.", "start": 1389.44, "duration": 1.14}, {"text": "AUDIENCE: Dynamic programming.", "start": 1390.58, "duration": 1.1}, {"text": "JASON KU: Dynamic\nprogramming, and the framework", "start": 1391.68, "duration": 2.0}, {"text": "was SRT BOT, right?", "start": 1393.68, "duration": 2.09}, {"text": "Missing a letter,\nbut SORT BOT, right?", "start": 1395.77, "duration": 2.94}, {"text": "You can actually\nthink of the quiz 3", "start": 1398.71, "duration": 2.97}, {"text": "material as really an\napplication of the graph", "start": 1401.68, "duration": 4.92}, {"text": "material.", "start": 1406.6, "duration": 2.26}, {"text": "What are we doing in SORT BOT?", "start": 1408.86, "duration": 2.18}, {"text": "We're defining a\nset of subproblems.", "start": 1411.04, "duration": 3.31}, {"text": "These are a set of\nvertices in a graph.", "start": 1414.35, "duration": 2.97}, {"text": "What is the relationship doing?", "start": 1417.32, "duration": 1.92}, {"text": "It's saying, what\nare the relation", "start": 1419.24, "duration": 3.93}, {"text": "between the\nsubproblems, essentially", "start": 1423.17, "duration": 2.31}, {"text": "defining the edges of a graph?", "start": 1425.48, "duration": 3.29}, {"text": "And then this topological\norder and the base cases,", "start": 1428.77, "duration": 3.81}, {"text": "all of these things\nare just saying,", "start": 1432.58, "duration": 1.89}, {"text": "what is the problem that I\nwant to solve on this graph?", "start": 1434.47, "duration": 2.73}, {"text": "And how do I compute\nthat for things that", "start": 1437.2, "duration": 4.38}, {"text": "don't have any outgoing edges?", "start": 1441.58, "duration": 3.09}, {"text": "I need to start writing\non the board again.", "start": 1444.67, "duration": 2.28}, {"text": "This is graphs.", "start": 1446.95, "duration": 2.64}, {"text": "There was sorting in here, too.", "start": 1449.59, "duration": 5.34}, {"text": "This is basically\nan application.", "start": 1454.93, "duration": 1.8}, {"text": "OK, graphs was\nbasically a relationship", "start": 1461.07, "duration": 3.31}, {"text": "on these non-constant things.", "start": 1464.38, "duration": 1.95}, {"text": "So this was kind of\nlike useful black boxes", "start": 1470.16, "duration": 5.54}, {"text": "that you can just bundle up\nand stick in some inputs,", "start": 1475.7, "duration": 4.03}, {"text": "stick out some outputs,\nand you're golden.", "start": 1479.73, "duration": 3.47}, {"text": "Whereas quiz 3 was\nvery different,", "start": 1483.2, "duration": 2.79}, {"text": "the material in quiz\n3 is very different.", "start": 1485.99, "duration": 1.74}, {"text": "Dynamic programming, while\nit was, in some sense,", "start": 1487.73, "duration": 11.76}, {"text": "related to this graph material--", "start": 1499.49, "duration": 1.43}, {"text": "I'm constructing a graph--", "start": 1500.92, "duration": 1.98}, {"text": "I have to construct that graph.", "start": 1502.9, "duration": 1.71}, {"text": "There's a creative process in\ntrying to construct that graph.", "start": 1504.61, "duration": 4.05}, {"text": "I don't give you\na set of vertices.", "start": 1508.66, "duration": 1.53}, {"text": "Usually what I give\nyou are a set of--", "start": 1510.19, "duration": 3.99}, {"text": "a sequence or\nsomething like that.", "start": 1514.18, "duration": 1.59}, {"text": "And you have to construct\nvertices, subproblems,", "start": 1515.77, "duration": 4.07}, {"text": "that will be able to be\nrelated in a recursive way", "start": 1519.84, "duration": 3.03}, {"text": "so you can solve the problem.", "start": 1522.87, "duration": 1.42}, {"text": "This is a very much\nmore difficult thing", "start": 1524.29, "duration": 3.05}, {"text": "than these other\nthings, I think,", "start": 1527.34, "duration": 1.86}, {"text": "because there's a lot\nmore creativity in this.", "start": 1529.2, "duration": 3.36}, {"text": "In the same way\nthat just applying--", "start": 1532.56, "duration": 2.97}, {"text": "reducing to the graph algorithms\nwe have is fairly easy.", "start": 1535.53, "duration": 4.3}, {"text": "But actually doing some\ngraph transformations", "start": 1539.83, "duration": 3.08}, {"text": "to change the shape\nof the graph so", "start": 1542.91, "duration": 1.98}, {"text": "that you can apply\nthese algorithms, that's", "start": 1544.89, "duration": 2.25}, {"text": "a harder thing to do.", "start": 1547.14, "duration": 3.18}, {"text": "The difficulty with these\ntwo sets of materials", "start": 1550.32, "duration": 3.21}, {"text": "is very similar.", "start": 1553.53, "duration": 1.65}, {"text": "Figuring out what\nthe graph should be,", "start": 1555.18, "duration": 1.778}, {"text": "figuring out what the\nsubproblems should be", "start": 1556.958, "duration": 1.792}, {"text": "and how they relate, is really\nthe entire part of the--", "start": 1558.75, "duration": 3.846}, {"text": "the entire difficulty with\nsolving problems recursively.", "start": 1562.596, "duration": 4.794}, {"text": "And we've only given you a\ntaste of solving problems", "start": 1567.39, "duration": 2.82}, {"text": "recursively.", "start": 1570.21, "duration": 2.26}, {"text": "In future classes,\nlike 6.046, which", "start": 1572.47, "duration": 4.83}, {"text": "is the follow-on to this one in\nthe undergraduate curriculum,", "start": 1577.3, "duration": 4.19}, {"text": "this is all about\nintroduction to algorithms.", "start": 1581.49, "duration": 2.15}, {"text": "The next one's about design\nand analysis of algorithms.", "start": 1583.64, "duration": 3.57}, {"text": "It's quite a bit more\ndifficult, because we've mostly", "start": 1587.21, "duration": 6.92}, {"text": "left it to you to use the\nthings that we gave you", "start": 1594.13, "duration": 5.58}, {"text": "or make your own\nalgorithms based", "start": 1599.71, "duration": 2.64}, {"text": "on this very nice\ncookbook-like framework", "start": 1602.35, "duration": 4.56}, {"text": "that you can plug in a\nrecursive algorithm to.", "start": 1606.91, "duration": 2.7}, {"text": "Now actually, that\ncookbook is super", "start": 1609.61, "duration": 1.71}, {"text": "nice for any way of looking\nat a problem recursively,", "start": 1611.32, "duration": 4.89}, {"text": "but while in\ndynamic programming,", "start": 1616.21, "duration": 7.09}, {"text": "the inductive hypothesis of\ncombining your subproblems", "start": 1623.3, "duration": 5.43}, {"text": "is almost trivial,\nin other types", "start": 1628.73, "duration": 4.12}, {"text": "of recursive algorithms, that's\nnot necessarily the case.", "start": 1632.85, "duration": 4.27}, {"text": "Especially when\ninstead of looking", "start": 1637.12, "duration": 2.0}, {"text": "at all possible\nchoices, for example,", "start": 1639.12, "duration": 3.44}, {"text": "in a greedy algorithm\nwhere you're just", "start": 1642.56, "duration": 1.82}, {"text": "looking at one of the choices,\nthe locally best thing,", "start": 1644.38, "duration": 3.24}, {"text": "and recursing forward, you're\nnot doing all the work.", "start": 1647.62, "duration": 3.93}, {"text": "You're not locally\nbrute-forcing.", "start": 1651.55, "duration": 1.5}, {"text": "Your locally picking an optimal\nthing locally and hoping that", "start": 1653.05, "duration": 4.02}, {"text": "will lead you to good thing.", "start": 1657.07, "duration": 1.56}, {"text": "That's a much harder algorithmic\nparadigm to operate under.", "start": 1658.63, "duration": 5.88}, {"text": "And so that's more\nlike the material", "start": 1664.51, "duration": 2.61}, {"text": "that you'll be talking\nabout in 6.046.", "start": 1667.12, "duration": 3.06}, {"text": "So that's 006, a very quick\noverview of the content of this", "start": 1670.18, "duration": 9.38}, {"text": "class.", "start": 1679.56, "duration": 1.24}, {"text": "And we really like the structure\nof how this class is laid out,", "start": 1680.8, "duration": 4.43}, {"text": "because it gives you a\nfundamental idea of the things", "start": 1685.23, "duration": 2.91}, {"text": "people use to store information\non a computer and a sense", "start": 1688.14, "duration": 5.85}, {"text": "of how you solve\nproblems computationally", "start": 1693.99, "duration": 2.7}, {"text": "and how to argue that they're\ncorrect and efficient.", "start": 1696.69, "duration": 3.09}, {"text": "That's really what\nthis problem--", "start": 1699.78, "duration": 1.86}, {"text": "this course is about.", "start": 1701.64, "duration": 4.01}, {"text": "And if you feel like you\nenjoy this kind of stuff,", "start": 1705.65, "duration": 4.73}, {"text": "that's where you\ngo to take 6.046.", "start": 1710.38, "duration": 4.68}, {"text": "And 6.046 was actually\nthe first algorithms class", "start": 1715.06, "duration": 4.02}, {"text": "I ever took here at MIT,\nas a grad student actually.", "start": 1719.08, "duration": 4.665}, {"text": "This was hard for me.", "start": 1726.37, "duration": 2.94}, {"text": "It's actually hard to look at\nthese problems, these types,", "start": 1729.31, "duration": 4.08}, {"text": "and think in a\ncomputational way,", "start": 1733.39, "duration": 2.01}, {"text": "especially having not\ntaken this class, 6.006.", "start": 1735.4, "duration": 4.05}, {"text": "So hopefully you guys are\nall in a better position", "start": 1739.45, "duration": 2.97}, {"text": "than I was when I took it.", "start": 1742.42, "duration": 2.09}, {"text": "There's two ways I like to\nthink of the content in 6.046.", "start": 1744.51, "duration": 4.77}, {"text": "One is kind of just as\nan extension of 006.", "start": 1749.28, "duration": 3.6}, {"text": "It's the natural\nfollow-on to the things", "start": 1752.88, "duration": 1.92}, {"text": "that we do in this class.", "start": 1754.8, "duration": 1.77}, {"text": "They still talk about\ndata structures.", "start": 1756.57, "duration": 2.677}, {"text": "This isn't the core part of\n046, but they do touch on data", "start": 1763.15, "duration": 4.88}, {"text": "structures for\nmore complicated--", "start": 1768.03, "duration": 3.15}, {"text": "that have more complicated\nanalyses involved in them.", "start": 1771.18, "duration": 2.79}, {"text": "It's really about--\nusually in 046,", "start": 1773.97, "duration": 4.02}, {"text": "stating what the algorithm\nis doing is not so hard.", "start": 1777.99, "duration": 4.93}, {"text": "Basically, giving\nyou the algorithm,", "start": 1782.92, "duration": 3.06}, {"text": "number one here, is\nnot so difficult,", "start": 1785.98, "duration": 3.21}, {"text": "to state what's happening\nin the algorithm.", "start": 1789.19, "duration": 3.24}, {"text": "But the number two\nand number three here,", "start": 1792.43, "duration": 3.3}, {"text": "arguing that that thing is\ncorrect and arguing that thing", "start": 1795.73, "duration": 3.33}, {"text": "is efficient, that's where the\ncomplexity comes in in 046.", "start": 1799.06, "duration": 5.37}, {"text": "The analysis part is quite a\nbit more complicated in 046 than", "start": 1804.43, "duration": 3.93}, {"text": "in 006.", "start": 1808.36, "duration": 1.56}, {"text": "So they solve a problem called\nunion-find and give a much--", "start": 1809.92, "duration": 7.32}, {"text": "we talked a little bit\nabout amortization.", "start": 1817.24, "duration": 2.46}, {"text": "This goes into a much better-- a\nmuch more formal way of proving", "start": 1819.7, "duration": 4.59}, {"text": "things run in amortized time.", "start": 1824.29, "duration": 5.55}, {"text": "So this is basically\namortization via what", "start": 1829.84, "duration": 8.85}, {"text": "we call a potential analysis.", "start": 1838.69, "duration": 1.68}, {"text": "It's basically\nmaking that notion", "start": 1846.03, "duration": 5.022}, {"text": "that we talked about\nwhen we were talking", "start": 1851.052, "duration": 1.708}, {"text": "about dynamic arrays of, we're\nnot doing this expensive thing", "start": 1852.76, "duration": 4.38}, {"text": "too often.", "start": 1857.14, "duration": 1.17}, {"text": "Basically what we\ndo is we keep track", "start": 1858.31, "duration": 1.86}, {"text": "of the cost of all\nsequence of operations", "start": 1860.17, "duration": 2.97}, {"text": "and prove that the\naverage cost is small.", "start": 1863.14, "duration": 3.6}, {"text": "That's kind of what this\npotential analysis is doing.", "start": 1866.74, "duration": 3.498}, {"text": "It's a little bit\nmore formal process", "start": 1870.238, "duration": 1.542}, {"text": "for making that argument\na little more formal.", "start": 1871.78, "duration": 3.99}, {"text": "Right.", "start": 1875.77, "duration": 0.5}, {"text": "OK.", "start": 1876.27, "duration": 0.5}, {"text": "So then on the\ngraph side, this is", "start": 1876.77, "duration": 2.57}, {"text": "kind of an extension of\nquiz 1-type material.", "start": 1879.34, "duration": 3.27}, {"text": "This is, what is this\nunion-find data structure?", "start": 1882.61, "duration": 2.53}, {"text": "It's basically-- it's\na set type thing, where", "start": 1885.14, "duration": 6.26}, {"text": "I can make a set of\njust a single element,", "start": 1891.4, "duration": 5.9}, {"text": "I can take two sets, merge\nthem together, make them", "start": 1897.3, "duration": 4.92}, {"text": "their union, and then\ngiven an object, I say,", "start": 1902.22, "duration": 5.22}, {"text": "which set am I part of,\nessentially by electing", "start": 1907.44, "duration": 4.53}, {"text": "a leader within\na set and saying,", "start": 1911.97, "duration": 1.95}, {"text": "return me a pointer to that one.", "start": 1913.92, "duration": 3.36}, {"text": "And so this can be useful\nin dynamically maintaining,", "start": 1917.28, "duration": 3.45}, {"text": "say, the connected components\nin a dynamically changing graph", "start": 1920.73, "duration": 5.04}, {"text": "supporting the query of,\nam I in the same component", "start": 1925.77, "duration": 3.75}, {"text": "as this other guy?", "start": 1929.52, "duration": 1.83}, {"text": "That could be a very useful\nthing to know about a graph", "start": 1931.35, "duration": 2.52}, {"text": "as it's changing.", "start": 1933.87, "duration": 0.93}, {"text": "So that's an application\nof this problem.", "start": 1934.8, "duration": 2.34}, {"text": "And they get\nnear-constant performance", "start": 1937.14, "duration": 3.18}, {"text": "for a lot of these queries.", "start": 1940.32, "duration": 1.68}, {"text": "It's not quite,\nbut pretty close.", "start": 1942.0, "duration": 3.36}, {"text": "OK, on the graph\nside, they solve", "start": 1945.36, "duration": 2.01}, {"text": "a number of very useful\nproblems on graphs.", "start": 1947.37, "duration": 4.98}, {"text": "Minimum Spanning\nTree-- so I'm trying", "start": 1952.35, "duration": 3.42}, {"text": "to find a tree connecting\nall of the vertices", "start": 1955.77, "duration": 3.96}, {"text": "in a connected\ncomponent of my graph.", "start": 1959.73, "duration": 2.46}, {"text": "And I'm trying to find--\nin a weighted graph,", "start": 1962.19, "duration": 1.98}, {"text": "I'm trying to find\nthe spanning tree that", "start": 1964.17, "duration": 2.79}, {"text": "has minimum total weight.", "start": 1966.96, "duration": 2.28}, {"text": "So that's a problem--", "start": 1969.24, "duration": 1.78}, {"text": "a fundamental problem in\nweighted-graph algorithms.", "start": 1971.02, "duration": 4.61}, {"text": "They've solved this\nvia a greedy algorithm.", "start": 1975.63, "duration": 4.05}, {"text": "And network flows\nand I guess cuts.", "start": 1979.68, "duration": 10.68}, {"text": "So this is-- what is this?", "start": 1990.36, "duration": 1.67}, {"text": "This is, I'm given\na weighted graph.", "start": 1992.03, "duration": 3.81}, {"text": "Basically, each of the weights\ncorrespond to a capacity.", "start": 1995.84, "duration": 5.28}, {"text": "I could push water\nthrough along this edge.", "start": 2001.12, "duration": 2.76}, {"text": "And I may be given a source\nvertex and a sink vertex.", "start": 2003.88, "duration": 4.95}, {"text": "And I want to say, I\nwant to shove water", "start": 2008.83, "duration": 2.67}, {"text": "through the source\nvertex along the edges", "start": 2011.5, "duration": 4.32}, {"text": "with their various capacities.", "start": 2015.82, "duration": 2.07}, {"text": "And I'll get some\namount of water", "start": 2017.89, "duration": 2.25}, {"text": "on the other end in the source.", "start": 2020.14, "duration": 3.0}, {"text": "So the question is, what's\nthe most amount of water", "start": 2023.14, "duration": 3.332}, {"text": "that I can push through this?", "start": 2026.472, "duration": 1.208}, {"text": "Well, I could build\nthat pipe network", "start": 2027.68, "duration": 2.963}, {"text": "with the different things and\njust do this experimentally.", "start": 2030.643, "duration": 2.417}, {"text": "I just stick a bunch of--", "start": 2033.06, "duration": 1.96}, {"text": "maybe-- I'm a\nmechanical engineer,", "start": 2035.02, "duration": 1.8}, {"text": "so that maybe makes sense to me.", "start": 2036.82, "duration": 1.62}, {"text": "But you want to be able to\njust look at those numbers", "start": 2038.44, "duration": 2.76}, {"text": "and be able to tell me how\nmuch water can I push through.", "start": 2041.2, "duration": 3.06}, {"text": "That's what the max flow in\na network is talking about.", "start": 2044.26, "duration": 4.47}, {"text": "And we give you some polynomial\ntime algorithms in this class,", "start": 2048.73, "duration": 3.33}, {"text": "basically incremental algorithms\nthat, kind of like Dijkstra,", "start": 2052.06, "duration": 4.26}, {"text": "or kind of like Bellman-Ford,\nwill incrementally update", "start": 2056.32, "duration": 5.76}, {"text": "estimates to--", "start": 2062.08, "duration": 3.24}, {"text": "of a max flow and\nimprove them over time.", "start": 2065.32, "duration": 3.629}, {"text": "Then on the, basically,\ndesign paradigms,", "start": 2071.98, "duration": 10.5}, {"text": "you've got more involved making\nyour own divide-and-conquer", "start": 2082.48, "duration": 4.11}, {"text": "algorithms, dynamic programming\nalgorithms, greedy algorithms.", "start": 2086.59, "duration": 11.34}, {"text": "Basically, they go\na lot more in depth", "start": 2097.93, "duration": 2.97}, {"text": "in terms of how to design these\nalgorithms and these paradigms", "start": 2100.9, "duration": 3.39}, {"text": "than we do in this class.", "start": 2104.29, "duration": 2.79}, {"text": "And then the last thing is--", "start": 2107.08, "duration": 3.09}, {"text": "we only touched on complexity.", "start": 2110.17, "duration": 3.81}, {"text": "And in a sense, 046 is only\ngoing to touch on complexity.", "start": 2113.98, "duration": 4.42}, {"text": "It's a very big field.", "start": 2118.4, "duration": 2.12}, {"text": "But it will give\nyou the tools to be", "start": 2120.52, "duration": 3.59}, {"text": "able to prove that something is\nNP-hard, whereas we just kind", "start": 2124.11, "duration": 4.02}, {"text": "of say that, oh, there's this\nthing called a reduction.", "start": 2128.13, "duration": 3.96}, {"text": "We didn't give you any\nproblems in which you actually", "start": 2132.09, "duration": 4.23}, {"text": "had to reduce one\nproblem to another.", "start": 2136.32, "duration": 2.29}, {"text": "And you'll do a lot\nmore of that here.", "start": 2138.61, "duration": 2.13}, {"text": "So, reductions.", "start": 2140.74, "duration": 3.62}, {"text": "So in a big sense, 046 is\nreally just a natural extension", "start": 2144.36, "duration": 8.06}, {"text": "to the 006 material, plus\nsome additional stuff,", "start": 2152.42, "duration": 3.307}, {"text": "which I'm going to\nget to in a second.", "start": 2155.727, "duration": 1.583}, {"text": "Yeah, question?", "start": 2157.31, "duration": 0.63}, {"text": "AUDIENCE: Do you want\nto add randomization", "start": 2157.94, "duration": 1.75}, {"text": "for time paradigms?", "start": 2159.69, "duration": 1.67}, {"text": "JASON KU: I'm going\nto talk about that", "start": 2161.36, "duration": 1.89}, {"text": "slightly in a separate--", "start": 2163.25, "duration": 2.43}, {"text": "I'll get to your question\nin just a second.", "start": 2165.68, "duration": 1.98}, {"text": "I like to think of it as\na separate topic, which", "start": 2167.66, "duration": 3.75}, {"text": "I will go into right now.", "start": 2171.41, "duration": 2.19}, {"text": "The separate topic I like\nto think of it as, instead", "start": 2173.6, "duration": 3.3}, {"text": "of being the natural extension\nto the things in the 006 units,", "start": 2176.9, "duration": 6.14}, {"text": "what I'm going to do is kind\nof relax either what it means", "start": 2183.04, "duration": 5.8}, {"text": "to have a correct algorithm\nor relax what it means to--", "start": 2188.84, "duration": 4.315}, {"text": "what my model of computation is.", "start": 2195.78, "duration": 3.33}, {"text": "So 006, this is kind of\nas an extension of 006.", "start": 2199.11, "duration": 12.19}, {"text": "And this is kind of\nlike 6.046 as change", "start": 2211.3, "duration": 11.67}, {"text": "my definition of what it means\nto be correct or efficient.", "start": 2222.97, "duration": 3.904}, {"text": "So we've already kind of done\nthis a little bit in 006.", "start": 2230.59, "duration": 10.9}, {"text": "Basically, one of the\nthings that we can do,", "start": 2241.49, "duration": 2.05}, {"text": "which is what the question\nthat a student asked a question", "start": 2243.54, "duration": 3.47}, {"text": "about, was about\nrandomized algorithms,", "start": 2247.01, "duration": 2.1}, {"text": "which is a big part\nof 046 actually--", "start": 2249.11, "duration": 3.69}, {"text": "randomized analysis\nof algorithms", "start": 2252.8, "duration": 3.81}, {"text": "that are not deterministic.", "start": 2256.61, "duration": 1.8}, {"text": "It's not guaranteed that\nit'll give you the same output", "start": 2258.41, "duration": 2.73}, {"text": "every time or not\nguaranteed that it", "start": 2261.14, "duration": 2.79}, {"text": "will do the same\ncomputations over the course", "start": 2263.93, "duration": 2.94}, {"text": "of the algorithm every time.", "start": 2266.87, "duration": 1.8}, {"text": "But it exploits\nsome randomization.", "start": 2268.67, "duration": 2.01}, {"text": "And in 006, this is--", "start": 2281.65, "duration": 2.34}, {"text": "we've mostly not touched on\nthis, except in one area.", "start": 2283.99, "duration": 3.54}, {"text": "Where did we use randomization?", "start": 2287.53, "duration": 2.67}, {"text": "In hashing, right?", "start": 2290.2, "duration": 2.07}, {"text": "When we used hashing,\nwhat were we doing?", "start": 2292.27, "duration": 3.81}, {"text": "We changed the definition\nof correct versus efficient.", "start": 2296.08, "duration": 3.15}, {"text": "We didn't really change the\ndefinition, what we did was", "start": 2299.23, "duration": 2.97}, {"text": "we said that it was OK that\nsometimes our algorithm was", "start": 2302.2, "duration": 4.5}, {"text": "slower than we--", "start": 2306.7, "duration": 2.56}, {"text": "than on-- in expectation.", "start": 2309.26, "duration": 2.94}, {"text": "That's what we meant there.", "start": 2312.2, "duration": 1.73}, {"text": "We're relaxing the\nidea of efficient,", "start": 2313.93, "duration": 2.92}, {"text": "but we're still saying\nit's good, because most", "start": 2316.85, "duration": 1.98}, {"text": "of the time it is good.", "start": 2318.83, "duration": 2.22}, {"text": "So there's two types of\nrandomized algorithms.", "start": 2321.05, "duration": 3.81}, {"text": "They have these\nweird names based", "start": 2324.86, "duration": 2.34}, {"text": "on betting regions of\nthe world, shall we say?", "start": 2327.2, "duration": 4.86}, {"text": "There are-- this is L-O?", "start": 2332.06, "duration": 5.998}, {"text": "Los Vegas?", "start": 2338.058, "duration": 1.302}, {"text": "It is Las, OK, Vegas algorithms.", "start": 2339.36, "duration": 5.31}, {"text": "These are always correct,\nbut probably efficient.", "start": 2344.67, "duration": 9.308}, {"text": "In a sense, that's\nwhat hashing is.", "start": 2358.86, "duration": 3.12}, {"text": "I'm always going to give\nyou the right thing,", "start": 2361.98, "duration": 3.12}, {"text": "whether this thing\nis in my set or not.", "start": 2365.1, "duration": 2.04}, {"text": "But some of the time,\nit's inefficient.", "start": 2367.14, "duration": 3.27}, {"text": "I have to look through\na chain of length", "start": 2370.41, "duration": 2.46}, {"text": "of-- that's linear in the size\nof the things that I'm storing.", "start": 2372.87, "duration": 3.24}, {"text": "And this is in contrast to\na Monte Carlo algorithm,", "start": 2376.11, "duration": 7.78}, {"text": "which is always efficient for\nsome definition of efficient,", "start": 2383.89, "duration": 8.21}, {"text": "but only probably correct.", "start": 2392.1, "duration": 1.74}, {"text": "And I mean, I could define you a\nhash table that has Monte Carlo", "start": 2398.64, "duration": 4.53}, {"text": "semantics instead.", "start": 2403.17, "duration": 1.74}, {"text": "Say, for example, I\nsay that I'm going--", "start": 2404.91, "duration": 3.925}, {"text": "it's going to be exactly\nthe same as a hash table,", "start": 2408.835, "duration": 2.925}, {"text": "except instead of storing\nall the things that", "start": 2411.76, "duration": 2.4}, {"text": "collide in a place, I just\nstore the first two, say.", "start": 2414.16, "duration": 4.29}, {"text": "Well, actually, that's actually\ngoing to be always efficient.", "start": 2421.75, "duration": 3.15}, {"text": "I'm going to look\nthrough the things", "start": 2424.9, "duration": 1.5}, {"text": "and see if it's in there.", "start": 2426.4, "duration": 2.72}, {"text": "And the chains that I'm storing\nthere only have two things.", "start": 2429.12, "duration": 3.393}, {"text": "It's going to be\nalways efficient.", "start": 2432.513, "duration": 1.417}, {"text": "It's always going to\ngive me constant time.", "start": 2433.93, "duration": 2.22}, {"text": "But some of the time, it's\ngoing to be the wrong thing,", "start": 2436.15, "duration": 2.51}, {"text": "because I'm not storing\neverything in that chain.", "start": 2438.66, "duration": 2.97}, {"text": "So there's some probability that\nthat's not going to be correct.", "start": 2441.63, "duration": 3.57}, {"text": "And so that's a\ndifferent kind of--", "start": 2445.2, "duration": 2.28}, {"text": "maybe I want my hash\ntables to always be fast,", "start": 2447.48, "duration": 2.85}, {"text": "but I can afford to be\nwrong some of the time.", "start": 2450.33, "duration": 4.018}, {"text": "I don't know.", "start": 2454.348, "duration": 0.542}, {"text": "In practice, this is actually\nsometimes a good trade-off", "start": 2454.89, "duration": 3.0}, {"text": "in real systems.", "start": 2457.89, "duration": 2.01}, {"text": "Sometimes it's OK to be\nwrong some of the times,", "start": 2459.9, "duration": 2.59}, {"text": "if we get good performance.", "start": 2462.49, "duration": 2.74}, {"text": "OK, but generally can do better\nif you allow randomization.", "start": 2465.23, "duration": 18.54}, {"text": "And by better I mean, usually\nwe can get faster bounds", "start": 2483.77, "duration": 4.35}, {"text": "on a lot of problems if we allow\nrandomization and things aren't", "start": 2488.12, "duration": 4.65}, {"text": "necessarily always correct\nor always efficient.", "start": 2492.77, "duration": 3.9}, {"text": "So this is a big area in\n046 that requires a lot more", "start": 2496.67, "duration": 5.46}, {"text": "analysis using randomness\nand probability.", "start": 2502.13, "duration": 5.49}, {"text": "So if you need some\nprimers on that--", "start": 2507.62, "duration": 5.29}, {"text": "we didn't have a lot of this in\n006, but if you go on to 046,", "start": 2512.91, "duration": 4.735}, {"text": "that's going to be a really\nimportant thing for you", "start": 2517.645, "duration": 2.125}, {"text": "to brush up on.", "start": 2519.77, "duration": 2.37}, {"text": "The next part on 006 is kind\nof changing what our definition", "start": 2522.14, "duration": 5.97}, {"text": "of correct or efficient means.", "start": 2528.11, "duration": 2.1}, {"text": "I mean, we've\nrestricted ourselves", "start": 2530.21, "duration": 2.64}, {"text": "in this class to a class\nof problems where we only", "start": 2532.85, "duration": 3.27}, {"text": "talk about integers.", "start": 2536.12, "duration": 2.91}, {"text": "But there's tons of\nproblems in this world,", "start": 2539.03, "duration": 1.87}, {"text": "especially in\nscientific computing,", "start": 2540.9, "duration": 2.0}, {"text": "where I want to be able to find\nout what this real number is.", "start": 2542.9, "duration": 5.61}, {"text": "And I can't even store a\nreal number on my computer.", "start": 2548.51, "duration": 3.44}, {"text": "So what the hell, Jason?", "start": 2551.95, "duration": 1.51}, {"text": "What are you talking about?", "start": 2553.46, "duration": 2.25}, {"text": "I can't do that on a computer.", "start": 2555.71, "duration": 1.71}, {"text": "But what I can do is\nbasically compute things", "start": 2557.42, "duration": 4.26}, {"text": "in a numerical sense--\nnumerical algorithms.", "start": 2561.68, "duration": 4.11}, {"text": "And in 046, a lot of times\nwe put this in the context", "start": 2569.02, "duration": 3.69}, {"text": "of continuous optimization,\ncontinuous being the opportune", "start": 2572.71, "duration": 9.18}, {"text": "word here, not discrete systems.", "start": 2581.89, "duration": 1.86}, {"text": "You have a continuum of\npossible solutions, real numbers", "start": 2583.75, "duration": 4.47}, {"text": "essentially.", "start": 2588.22, "duration": 1.71}, {"text": "How do we do this on a computer\nthat's a discrete system?", "start": 2589.93, "duration": 2.415}, {"text": "Basically, in 046\nwhat you can do,", "start": 2596.35, "duration": 4.2}, {"text": "and in other numerical methods\nclasses, what you can say is,", "start": 2600.55, "duration": 3.87}, {"text": "well, I know that you can't\nreturn me a real number.", "start": 2604.42, "duration": 3.87}, {"text": "I got that.", "start": 2608.29, "duration": 0.63}, {"text": "Or you can maybe have\na model of computation", "start": 2608.92, "duration": 2.97}, {"text": "that allows integers\nto represent", "start": 2611.89, "duration": 2.88}, {"text": "other kinds of real numbers,\nlike radicals or rationals", "start": 2614.77, "duration": 3.632}, {"text": "or something like that.", "start": 2618.402, "duration": 0.958}, {"text": "And I can do\nmanipulations on those.", "start": 2619.36, "duration": 1.86}, {"text": "But really what these\nalgorithms are usually about", "start": 2621.22, "duration": 2.82}, {"text": "is computing real\nnumbers not completely,", "start": 2624.04, "duration": 4.62}, {"text": "but to some bounded precision.", "start": 2628.66, "duration": 2.91}, {"text": "And I pay for that precision.", "start": 2631.57, "duration": 2.76}, {"text": "The more bits of precision\nI want on my number,", "start": 2634.33, "duration": 3.12}, {"text": "I have to pay for them.", "start": 2637.45, "duration": 1.58}, {"text": "So this is basic--", "start": 2639.03, "duration": 1.93}, {"text": "I think of these as\nan approximation--", "start": 2640.96, "duration": 1.95}, {"text": "approximation of real\nnumber to some precision,", "start": 2645.73, "duration": 15.87}, {"text": "and I pay for\nprecision with time.", "start": 2661.6, "duration": 11.89}, {"text": "So let's say I wanted to compute\nthe square root of a number.", "start": 2673.49, "duration": 3.83}, {"text": "I could have an algorithm\njust like the algorithms--", "start": 2677.32, "duration": 3.33}, {"text": "or I guess division,\nright, long division.", "start": 2680.65, "duration": 4.35}, {"text": "You all know the algorithm\nof long division.", "start": 2685.0, "duration": 2.4}, {"text": "You put the quotient under\nhere with these-- an AB", "start": 2687.4, "duration": 4.56}, {"text": "and you get the C\non top or whatever.", "start": 2691.96, "duration": 3.157}, {"text": "That's an algorithm.", "start": 2695.117, "duration": 0.833}, {"text": "That's a procedure using\nessentially small numbers.", "start": 2695.95, "duration": 3.81}, {"text": "I'm only talking about\nthe digits zero to nine", "start": 2699.76, "duration": 2.79}, {"text": "here when I'm doing\nthat algorithm.", "start": 2702.55, "duration": 1.92}, {"text": "So it's a procedure\nthat only uses", "start": 2704.47, "duration": 2.67}, {"text": "small integers to\ncompute arbitrary", "start": 2707.14, "duration": 2.97}, {"text": "precision of a division.", "start": 2710.11, "duration": 3.48}, {"text": "So that's an\nalgorithm, and I have", "start": 2713.59, "duration": 1.44}, {"text": "to pay time to get more digits.", "start": 2715.03, "duration": 3.66}, {"text": "So that's an\nexample of this kind", "start": 2718.69, "duration": 3.45}, {"text": "of-- how we live in the\nworld of real numbers", "start": 2722.14, "duration": 3.75}, {"text": "when all we have is\na discrete system.", "start": 2725.89, "duration": 3.16}, {"text": "And then the last category\nI'd like to talk about here", "start": 2729.05, "duration": 4.76}, {"text": "is really approximation\nalgorithms.", "start": 2733.81, "duration": 3.42}, {"text": "Whereas this is kind of an\napproximation algorithm,", "start": 2740.83, "duration": 2.7}, {"text": "I'm approximating\nmy outputs, this", "start": 2743.53, "duration": 2.34}, {"text": "is an approximation algorithm\nfrom the standpoint of,", "start": 2745.87, "duration": 4.81}, {"text": "well, there's a lot of problems\nthat I can't solve efficiently.", "start": 2750.68, "duration": 3.11}, {"text": "They're NP-hard.", "start": 2753.79, "duration": 0.75}, {"text": "They're in EXP or\neven harder problems.", "start": 2754.54, "duration": 6.15}, {"text": "But maybe I'm OK with not\ngetting the optimal solution.", "start": 2760.69, "duration": 5.49}, {"text": "So this is in the domain\nof optimization problems.", "start": 2766.18, "duration": 2.915}, {"text": "So most of the\ndynamic programming", "start": 2775.09, "duration": 3.182}, {"text": "problems that we gave you\nwere optimization problems.", "start": 2778.272, "duration": 2.208}, {"text": "They're the shortest\npaths problems.", "start": 2780.48, "duration": 1.23}, {"text": "Those are optimization problems.", "start": 2781.71, "duration": 1.333}, {"text": "Basically, the possible outputs\nare ranked in some way--", "start": 2783.043, "duration": 3.827}, {"text": "the distance of a path that you\nreturn or something like that.", "start": 2786.87, "duration": 5.34}, {"text": "They're ranked in some way.", "start": 2792.21, "duration": 1.36}, {"text": "There is an optimal one--", "start": 2793.57, "duration": 1.49}, {"text": "the one with the smallest\nmetric or something like that.", "start": 2795.06, "duration": 3.45}, {"text": "Well, in an approximation\nalgorithm what I do is, OK,", "start": 2801.05, "duration": 2.55}, {"text": "I get that it's computationally\ndifficult for you", "start": 2803.6, "duration": 3.12}, {"text": "to give me the longest\nsimple path in this graph,", "start": 2806.72, "duration": 3.27}, {"text": "or the shortest possible route\nfor my traveling salesman,", "start": 2809.99, "duration": 3.69}, {"text": "but maybe that's OK.", "start": 2813.68, "duration": 4.05}, {"text": "I mean, my engineering\nSpidey-sense", "start": 2817.73, "duration": 3.39}, {"text": "tells me that\nwithin 10% is fine.", "start": 2821.12, "duration": 3.36}, {"text": "So maybe instead of giving\nme the most optimal thing,", "start": 2824.48, "duration": 3.99}, {"text": "can I give you an\nalgorithm that's", "start": 2828.47, "duration": 1.44}, {"text": "guaranteed to be within\na certain distance", "start": 2829.91, "duration": 2.61}, {"text": "from the optimal thing?", "start": 2832.52, "duration": 2.49}, {"text": "Usually, we're looking for\nconstant factor approximations", "start": 2835.01, "duration": 2.85}, {"text": "which have low\nconstant, or maybe", "start": 2837.86, "duration": 4.77}, {"text": "even have to do for worse\nif such things don't exist.", "start": 2842.63, "duration": 3.39}, {"text": "OK, so that's\napproximation algorithms.", "start": 2846.02, "duration": 2.55}, {"text": "Can we get close to an optimal\nsolution in polynomial time?", "start": 2848.57, "duration": 4.96}, {"text": "OK.", "start": 2853.53, "duration": 1.55}, {"text": "And then the last way we could\nchange things in, especially", "start": 2855.08, "duration": 4.35}, {"text": "future classes, though sometimes\nthey talk about this in 046", "start": 2859.43, "duration": 3.54}, {"text": "as well, is we could change\nthe model of computation.", "start": 2862.97, "duration": 3.9}, {"text": "We could basically change\nsomething about our computer", "start": 2866.87, "duration": 3.27}, {"text": "to be put in some other weird\nparadigm of solving problems", "start": 2870.14, "duration": 4.77}, {"text": "with more power\nessentially, or you're", "start": 2874.91, "duration": 2.633}, {"text": "in a situation where\nthere's less power.", "start": 2877.543, "duration": 1.667}, {"text": "OK, so change in the\nmodel of computation.", "start": 2879.21, "duration": 2.985}, {"text": "So what we've been talking\nto you in terms of model", "start": 2892.59, "duration": 3.78}, {"text": "of computation is our word-RAM--", "start": 2896.37, "duration": 2.05}, {"text": "word-RAM.", "start": 2898.42, "duration": 0.5}, {"text": "And that essentially says I\ncan do arithmetic operations,", "start": 2901.83, "duration": 3.69}, {"text": "and I can look up stuff in\nmy memory in constant time.", "start": 2905.52, "duration": 2.79}, {"text": "And but if I allocate\na certain amount,", "start": 2908.31, "duration": 2.618}, {"text": "I have to pay that amount\nand that kind of thing.", "start": 2910.928, "duration": 2.042}, {"text": "So that's this word-RAM model.", "start": 2912.97, "duration": 3.35}, {"text": "But in actuality, all\nof your computers,", "start": 2916.32, "duration": 4.17}, {"text": "it's a lot easier\nfor me to figure--", "start": 2920.49, "duration": 2.85}, {"text": "to find and read memory\nthat's on my CPU in a register", "start": 2923.34, "duration": 5.43}, {"text": "than it is for me to go out\nto the hard disk, ask this--", "start": 2928.77, "duration": 3.3}, {"text": "well, in my day, it used to be\nthis movable mechanical head", "start": 2932.07, "duration": 4.02}, {"text": "that had to go and scan\nover a bit on a CD-ROM drive", "start": 2936.09, "duration": 4.71}, {"text": "and actually read\nwhat that thing was.", "start": 2940.8, "duration": 5.13}, {"text": "So we can add\ncomplexity to our model", "start": 2945.93, "duration": 3.12}, {"text": "to better account for the costs\nof operations on my machine.", "start": 2949.05, "duration": 5.55}, {"text": "One of those models is\ncalled the cache model--", "start": 2954.6, "duration": 2.76}, {"text": "cache model.", "start": 2961.83, "duration": 2.49}, {"text": "It's basically a\nhierarchy of memory.", "start": 2964.32, "duration": 4.5}, {"text": "I have my registers\non board my CPU.", "start": 2968.82, "duration": 3.42}, {"text": "I have maybe an L1 cache\nthat's close to my CPU.", "start": 2972.24, "duration": 3.87}, {"text": "Then I have another\nset of caches", "start": 2976.11, "duration": 1.44}, {"text": "and another set of\ncaches maybe out to RAM.", "start": 2977.55, "duration": 2.76}, {"text": "And reading from a hard disk, a\nsolid state drive of some kind,", "start": 2980.31, "duration": 3.21}, {"text": "that's the slowest\nthing to access.", "start": 2983.52, "duration": 2.82}, {"text": "And I can put a cost associated\nwith each of those things.", "start": 2986.34, "duration": 3.48}, {"text": "And instead of having to--", "start": 2989.82, "duration": 1.53}, {"text": "having all of our operations\nbe said to be constant,", "start": 2991.35, "duration": 6.41}, {"text": "the constants are\nactually different,", "start": 2997.76, "duration": 2.1}, {"text": "and I have to pay\nfor that difference.", "start": 2999.86, "duration": 2.43}, {"text": "And so that's\nextending our model", "start": 3002.29, "duration": 1.92}, {"text": "to be a little bit more\nrealistic to our machine.", "start": 3004.21, "duration": 2.94}, {"text": "Another one is we have\ncomputers right now that", "start": 3007.15, "duration": 4.47}, {"text": "operate in classical\nphysics, that exploit", "start": 3011.62, "duration": 3.3}, {"text": "things in classical physics.", "start": 3014.92, "duration": 1.77}, {"text": "But in actuality,\nour world allows", "start": 3016.69, "duration": 4.59}, {"text": "for even more complicated\ntypes of operations,", "start": 3021.28, "duration": 6.03}, {"text": "like quantum operations, where\nyou're exploiting entanglement", "start": 3027.31, "duration": 3.48}, {"text": "and superposition\nof different atoms", "start": 3030.79, "duration": 3.19}, {"text": "to potentially get operations\nthat I can act on my data that", "start": 3033.98, "duration": 5.31}, {"text": "are actually provably stronger\nthan the classical models", "start": 3039.29, "duration": 3.72}, {"text": "in some sense.", "start": 3043.01, "duration": 1.65}, {"text": "So this is a huge\nreason why there's", "start": 3044.66, "duration": 3.9}, {"text": "a lot of work\nbeing done in, say,", "start": 3048.56, "duration": 2.58}, {"text": "lots of industry research\nfacilities in figuring out", "start": 3051.14, "duration": 5.82}, {"text": "these models.", "start": 3056.96, "duration": 0.63}, {"text": "Because maybe if you can make\na big enough quantum computer,", "start": 3057.59, "duration": 3.16}, {"text": "you can break encryption and\nstuff in polynomial time.", "start": 3060.75, "duration": 3.05}, {"text": "And that's something that\nmaybe the NSA is interested in.", "start": 3063.8, "duration": 2.82}, {"text": "And I'm not going\nto go into that.", "start": 3066.62, "duration": 2.07}, {"text": "But, you know.", "start": 3068.69, "duration": 2.7}, {"text": "I mean, some people--", "start": 3071.39, "duration": 1.41}, {"text": "you look at artificial\nintelligence and things like", "start": 3072.8, "duration": 2.4}, {"text": "discussions around\nartificial intelligence,", "start": 3075.2, "duration": 2.43}, {"text": "my brain might be doing things\nthat a classical computer", "start": 3077.63, "duration": 6.8}, {"text": "cannot.", "start": 3084.43, "duration": 1.86}, {"text": "It could be using quantum\nsuperposition in some way.", "start": 3086.29, "duration": 3.6}, {"text": "And our computers that are\nin your phone and your laptop", "start": 3089.89, "duration": 4.257}, {"text": "and things like that aren't\nexploiting those operations,", "start": 3094.147, "duration": 2.333}, {"text": "so how could we ever\nget intelligence,", "start": 3096.48, "duration": 1.583}, {"text": "because in some sense, our\nbrains are more powerful.", "start": 3098.063, "duration": 3.557}, {"text": "And so a lot of what AI\nshould be looking into", "start": 3101.62, "duration": 3.45}, {"text": "is, what is the actual model\nof computation of our brains", "start": 3105.07, "duration": 4.98}, {"text": "that can give us the\npower to have sentience?", "start": 3110.05, "duration": 3.96}, {"text": "OK, so that's kind\nof quantum computing.", "start": 3114.01, "duration": 2.43}, {"text": "I don't know much\nabout it actually.", "start": 3116.44, "duration": 2.28}, {"text": "And then there's things like,\nmaybe I have more than one CPU.", "start": 3118.72, "duration": 6.23}, {"text": "I mean, most computers--\nall the computers you have,", "start": 3124.95, "duration": 2.71}, {"text": "even the ones in your phone,\nprobably have multiple cores.", "start": 3127.66, "duration": 3.42}, {"text": "In a sense, you have lots\nof CPUs running in parallel.", "start": 3131.08, "duration": 3.67}, {"text": "So this is like par--", "start": 3134.75, "duration": 2.37}, {"text": "there's one R in parallel?", "start": 3137.12, "duration": 1.415}, {"text": "Parallel computing basically\nsays, it's cheap for me", "start": 3148.08, "duration": 3.33}, {"text": "to make another\ncomputer potentially.", "start": 3151.41, "duration": 3.24}, {"text": "If I have two computers\nrunning on the same problem,", "start": 3154.65, "duration": 3.48}, {"text": "maybe I can get a\ntwo-fold speed-up on my--", "start": 3158.13, "duration": 3.642}, {"text": "on the time in which it\ntakes to solve my problem.", "start": 3161.772, "duration": 4.898}, {"text": "Now, suppose I had then 100\nCPUs running on a machine.", "start": 3166.67, "duration": 5.28}, {"text": "Maybe I can get\n100-fold speed-up.", "start": 3171.95, "duration": 1.74}, {"text": "And actually, in real\nlife, 100-fold speed-up", "start": 3173.69, "duration": 4.45}, {"text": "makes a difference.", "start": 3178.14, "duration": 1.86}, {"text": "It's, am I waiting for\nthis for 10 minutes?", "start": 3180.0, "duration": 3.06}, {"text": "Or am I waiting for\nthis for 1,000 minutes?", "start": 3183.06, "duration": 4.05}, {"text": "That's, like, all day.", "start": 3187.11, "duration": 1.92}, {"text": "I don't want to do that.", "start": 3189.03, "duration": 1.11}, {"text": "Maybe it's on weeks.", "start": 3190.14, "duration": 1.08}, {"text": "I don't even remember.", "start": 3191.22, "duration": 1.83}, {"text": "But parallel computing, if I\ncan get a 100-fold speed-up,", "start": 3193.05, "duration": 3.99}, {"text": "that might be a huge win.", "start": 3197.04, "duration": 1.83}, {"text": "But for some problems,\nit's not possible--", "start": 3198.87, "duration": 3.91}, {"text": "if I have k CPUs, can I\nget a k-factor speed-up?", "start": 3202.78, "duration": 6.42}, {"text": "It's not always possible to do.", "start": 3209.2, "duration": 3.19}, {"text": "And so parallel computing\nis another paradigm", "start": 3212.39, "duration": 2.94}, {"text": "in which there's a lot of\ninteresting theory going on.", "start": 3215.33, "duration": 5.59}, {"text": "There's a lot of\ncomplications there,", "start": 3220.92, "duration": 1.76}, {"text": "because there are a\ncouple different models.", "start": 3222.68, "duration": 2.34}, {"text": "You can have multicore\nset-up, where", "start": 3225.02, "duration": 1.77}, {"text": "you have a lot of computers\nthat are accessing", "start": 3226.79, "duration": 2.01}, {"text": "the same bank of memory.", "start": 3228.8, "duration": 2.13}, {"text": "And then you don't want them\nall to be reading and writing", "start": 3230.93, "duration": 2.76}, {"text": "from them at different times,\nbecause you don't necessarily", "start": 3233.69, "duration": 3.03}, {"text": "know what their state is,\nand you get these collisions,", "start": 3236.72, "duration": 2.653}, {"text": "which are something\nthat you really have", "start": 3239.373, "duration": 1.667}, {"text": "to think about in this world.", "start": 3241.04, "duration": 2.28}, {"text": "Or you have situations\nwhere maybe I", "start": 3243.32, "duration": 2.64}, {"text": "have a bunch of\nnano-flies or something", "start": 3245.96, "duration": 3.03}, {"text": "that are going around, and\nthey have very small computer", "start": 3248.99, "duration": 3.06}, {"text": "brains themselves.", "start": 3252.05, "duration": 3.06}, {"text": "But they can talk to each\nother and pass information", "start": 3255.11, "duration": 2.552}, {"text": "to each other, but\nthey don't have access", "start": 3257.662, "duration": 1.708}, {"text": "to one central network\nrepository of information.", "start": 3259.37, "duration": 2.86}, {"text": "That's what we call a\ndistributed parallel system,", "start": 3262.23, "duration": 3.23}, {"text": "where all of the\nCPUs that you have", "start": 3265.46, "duration": 3.48}, {"text": "can interact with each\nother maybe locally,", "start": 3268.94, "duration": 2.79}, {"text": "but don't have access to\nthe same memory system.", "start": 3271.73, "duration": 4.15}, {"text": "So they have to work\ntogether to learn information", "start": 3275.88, "duration": 4.88}, {"text": "about the system.", "start": 3280.76, "duration": 1.08}, {"text": "OK, so that's a brief overview\nof the different directions", "start": 3281.84, "duration": 6.42}, {"text": "this class, 6.006,\nand theory in general,", "start": 3288.26, "duration": 3.27}, {"text": "could lead you-- into a huge\narray of different branches", "start": 3291.53, "duration": 4.29}, {"text": "theory and different\nproblems that you", "start": 3295.82, "duration": 2.46}, {"text": "could address with different\ntypes of computers.", "start": 3298.28, "duration": 3.51}, {"text": "So I know this is a very\nhigh-level lecture and maybe", "start": 3301.79, "duration": 5.43}, {"text": "less-applied than some\nof you might like.", "start": 3307.22, "duration": 3.51}, {"text": "But I hope this gives you a good\nunderstanding of the directions", "start": 3310.73, "duration": 4.8}, {"text": "you can go after this\nclass that I think", "start": 3315.53, "duration": 3.87}, {"text": "are really excited in terms\nof how to solve problems", "start": 3319.4, "duration": 3.72}, {"text": "computationally.", "start": 3323.12, "duration": 1.77}, {"text": "So with that, I'd\nlike to end there.", "start": 3324.89, "duration": 4.52}]

transcripts/2YPu29d8RZY.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 1.984}, {"text": "[RUSTLING]", "start": 1.984, "duration": 2.48}, {"text": "[CLICKING]", "start": 4.464, "duration": 3.472}, {"text": "MARKUS KLUTE: Welcome back\nto 8.20, Special Relativity.", "start": 19.35, "duration": 3.022}, {"text": "In this section, you're\ngoing to take a journey", "start": 22.372, "duration": 1.958}, {"text": "through our solar\nsystem and beyond.", "start": 24.33, "duration": 2.97}, {"text": "1977 marks the first flight\nof the Voyager program.", "start": 27.3, "duration": 3.48}, {"text": "Voyager is an MIT-led program\nwith the original mission", "start": 30.78, "duration": 4.44}, {"text": "to study planetary systems.", "start": 35.22, "duration": 2.55}, {"text": "Now, Voyager 1 and Voyager\n2, two spacecrafts,", "start": 37.77, "duration": 3.57}, {"text": "are studying the\ninterstellar space.", "start": 41.34, "duration": 2.58}, {"text": "Those two probes are\nstill sending back now,", "start": 43.92, "duration": 2.85}, {"text": "more than 40 years\nlater, information", "start": 46.77, "duration": 3.03}, {"text": "about measurement of their\nsurroundings back to Earth.", "start": 49.8, "duration": 4.41}, {"text": "Those are the two furthest-away\nobjects we were able to send.", "start": 54.21, "duration": 4.62}, {"text": "What we have here in 8.20--", "start": 58.83, "duration": 1.86}, {"text": "and it's IAP, so we are a\nlittle bit more ambitious--", "start": 60.69, "duration": 3.89}, {"text": "our mission is to bring\nus to Alpha Centauri.", "start": 64.58, "duration": 3.21}, {"text": "Alpha Centauri is the\nclosest star and planetary", "start": 67.79, "duration": 3.06}, {"text": "system to our solar system.", "start": 70.85, "duration": 3.3}, {"text": "It's actually not just one\nstar, but multiple stars.", "start": 74.15, "duration": 3.18}, {"text": "And our journey brings\nus to Proxima B,", "start": 77.33, "duration": 3.42}, {"text": "which is a planet in the\nAlpha Centauri system.", "start": 80.75, "duration": 5.11}, {"text": "So we have a very\nfancy spacecraft.", "start": 85.86, "duration": 2.52}, {"text": "It's able to travel with a\nconstant velocity of 0.943 c,", "start": 88.38, "duration": 5.33}, {"text": "speed of light.", "start": 93.71, "duration": 2.01}, {"text": "The gamma factor is 3, and the\npath which it's going to take", "start": 95.72, "duration": 5.07}, {"text": "is 5 light years long.", "start": 100.79, "duration": 2.91}, {"text": "Alice is our ground control.", "start": 103.7, "duration": 3.72}, {"text": "She is going to stay on Earth.", "start": 107.42, "duration": 1.59}, {"text": "And Bob is going to take this\njourney with Virgin Galactic.", "start": 109.01, "duration": 4.71}, {"text": "After some time, Bob is\ngoing to arrive on Proxima B.", "start": 113.72, "duration": 4.46}, {"text": "So your first challenge\nis to now calculate", "start": 118.18, "duration": 4.39}, {"text": "how long does this trip\ntake from Alice's and Bob's", "start": 122.57, "duration": 3.84}, {"text": "perspective?", "start": 126.41, "duration": 1.87}, {"text": "So I ask you to stop the video\nhere and just work this out.", "start": 128.28, "duration": 3.5}, {"text": "So for Alice, the time\nneeded is 5 light years", "start": 134.64, "duration": 3.93}, {"text": "divided by 0.9, by\nthe velocity of 0.943,", "start": 138.57, "duration": 3.75}, {"text": "times the speed of light.", "start": 142.32, "duration": 1.38}, {"text": "And that gives us 5.3 years.", "start": 143.7, "duration": 2.79}, {"text": "So after 5.3 years, Alice\nis observing Bob's arrival", "start": 146.49, "duration": 5.58}, {"text": "on Proxima B. For Bob,\nthe length of this path", "start": 152.07, "duration": 4.9}, {"text": "is Lorentz contracted--", "start": 156.97, "duration": 3.3}, {"text": "5 light years\ndivided by 3, which", "start": 160.27, "duration": 2.19}, {"text": "is the gamma factor, which\nresults to 1.67 light years.", "start": 162.46, "duration": 5.04}, {"text": "So for him, the journey\ntakes only 1.77 years--", "start": 167.5, "duration": 4.11}, {"text": "1.67 light years divided by\n0.943 times the speed of light.", "start": 171.61, "duration": 5.77}, {"text": "So apparently, the time\nexperienced by Alice and Bob", "start": 177.38, "duration": 4.31}, {"text": "for the very same\njourney is different.", "start": 181.69, "duration": 3.01}, {"text": "So this now is the\nfirst part, where", "start": 184.7, "duration": 1.79}, {"text": "we enter discussions\nof paradoxes", "start": 186.49, "duration": 4.2}, {"text": "in special relativity.", "start": 190.69, "duration": 1.44}, {"text": "And this will bring\nus, ultimately,", "start": 192.13, "duration": 1.68}, {"text": "to an understanding of the twin\nparadox later in this course.", "start": 193.81, "duration": 4.91}]

transcripts/3FVlVP5MKV4.json

@@ -0,0 +1 @@
+[{"text": "The following\ncontent is provided", "start": 0.58, "duration": 1.86}, {"text": "by MIT OpenCourseWare under\na Creative Commons license.", "start": 2.44, "duration": 3.9}, {"text": "Additional information\nabout our license", "start": 6.34, "duration": 2.16}, {"text": "and MIT OpenCourseWare\nin general", "start": 8.5, "duration": 2.37}, {"text": "is available at ocw.mit.edu.", "start": 10.87, "duration": 1.86}, {"text": "GEORGE CHURCH: OK.", "start": 22.81, "duration": 0.75}, {"text": "Welcome back.", "start": 23.56, "duration": 1.35}, {"text": "We're going to go through a very\nspecific example of association", "start": 24.91, "duration": 6.27}, {"text": "studying, illustrating this\nextremely important statistic,", "start": 31.18, "duration": 3.36}, {"text": "the chi-square statistic\nin the simplest case.", "start": 34.54, "duration": 4.62}, {"text": "That simple case will be a\nsingle allele combination,", "start": 39.16, "duration": 6.93}, {"text": "two alleles and two possible\nphenotypic outcomes,", "start": 46.09, "duration": 6.3}, {"text": "HIV resistance and\nHIV non-resistance.", "start": 52.39, "duration": 4.92}, {"text": "So to set up this\nassociation study, which", "start": 57.31, "duration": 2.97}, {"text": "would be computational,\nlet's talk a little bit", "start": 60.28, "duration": 3.51}, {"text": "about the biology here.", "start": 63.79, "duration": 1.199}, {"text": "All viruses need to get\ninto your cells somehow.", "start": 68.89, "duration": 3.66}, {"text": "HIV has a number of\nproteins to which it binds", "start": 72.55, "duration": 4.89}, {"text": "on the surface of your cell.", "start": 77.44, "duration": 1.17}, {"text": "These proteins are not-- they're\nnot designed to bind HIV.", "start": 78.61, "duration": 3.6}, {"text": "They do something else.", "start": 82.21, "duration": 1.27}, {"text": "This is in a family of\nchemokine receptors.", "start": 83.48, "duration": 2.33}, {"text": "This is involved in\nintracellular signaling,", "start": 85.81, "duration": 3.15}, {"text": "and so it's a receptor\nnormally for these chemokines.", "start": 88.96, "duration": 5.4}, {"text": "But it is also a\nreceptor for the virus.", "start": 94.36, "duration": 3.72}, {"text": "And in the human population,\nas we alluded to earlier,", "start": 98.08, "duration": 6.43}, {"text": "there are at least two\nalleles, two common alleles.", "start": 104.51, "duration": 3.32}, {"text": "One of them, the top\none, capital CCR5,", "start": 107.83, "duration": 4.89}, {"text": "has this long,\nopen reading frame.", "start": 112.72, "duration": 1.5}, {"text": "And this you could translate\nby your pearl strip", "start": 114.22, "duration": 2.97}, {"text": "that you wrote for\nthe problem set.", "start": 117.19, "duration": 1.89}, {"text": "And the DNA sequences\nin the middle here", "start": 119.08, "duration": 3.37}, {"text": "and the protein sequence derived\nfrom it is on the top strand.", "start": 122.45, "duration": 5.46}, {"text": "And that's the capital CCR5.", "start": 127.91, "duration": 1.879}, {"text": "And the little delta or\ndeletion Ccr5 is below it.", "start": 129.789, "duration": 4.111}, {"text": "You've locked out 32\nbase pairs, which is not", "start": 133.9, "duration": 3.33}, {"text": "an interval multiple of three.", "start": 137.23, "duration": 1.47}, {"text": "And as you know\nfrom last lecture,", "start": 138.7, "duration": 2.97}, {"text": "that means it's going to be\na different genetic code.", "start": 141.67, "duration": 2.31}, {"text": "At every point downstream, this\nis going to be frame-shifted,", "start": 143.98, "duration": 3.21}, {"text": "and so you get a whole\nnew set of amino acids", "start": 147.19, "duration": 2.29}, {"text": "for the entirety of the rest\nof the carboxy terminus.", "start": 149.48, "duration": 4.92}, {"text": "So this in black\nhere-- so we're showing", "start": 154.4, "duration": 3.23}, {"text": "here in the single-letter code\na somewhat realistic folding", "start": 157.63, "duration": 5.1}, {"text": "of the-- schematic folding\nof the protein, showing here", "start": 162.73, "duration": 3.18}, {"text": "disulfide between two cysteines.", "start": 165.91, "duration": 2.43}, {"text": "Transmembrane region, we\nhave these hydrophobic alpha", "start": 168.34, "duration": 3.66}, {"text": "helices.", "start": 172.0, "duration": 0.84}, {"text": "And finally, in the\nblack amino acids,", "start": 172.84, "duration": 2.94}, {"text": "the C terminus, the\nend of the protein", "start": 175.78, "duration": 2.34}, {"text": "are all substituted in\nthis deletion mutant.", "start": 178.12, "duration": 3.45}, {"text": "Now that is sufficient to\ncause resistance to the virus.", "start": 181.57, "duration": 5.31}, {"text": "It probably has some\neffect on its ability", "start": 186.88, "duration": 2.49}, {"text": "to bind chemokines or react\nto them in some other way.", "start": 189.37, "duration": 4.12}, {"text": "And presumably, this is not--", "start": 193.49, "duration": 3.68}, {"text": "there is some deleterious\neffect we do not know about.", "start": 197.17, "duration": 2.97}, {"text": "But in any case,\nwe can assess this.", "start": 200.14, "duration": 3.075}, {"text": "We can make a genetic\nassay for this.", "start": 203.215, "duration": 2.235}, {"text": "And we can look in\nhuman populations", "start": 205.45, "duration": 4.62}, {"text": "for their resistance to HIV and\nfor the presence of either two", "start": 210.07, "duration": 4.8}, {"text": "alleles of the resistance or\ntwo alleles of the susceptible.", "start": 214.87, "duration": 6.57}, {"text": "Now I'm kind of biasing\nyou here in this.", "start": 221.44, "duration": 2.25}, {"text": "We haven't done the\nassociation study.", "start": 223.69, "duration": 1.633}, {"text": "I really shouldn't be referring\nto it as resistant or not,", "start": 225.323, "duration": 2.417}, {"text": "but I think it helps\nyou visualize it.", "start": 227.74, "duration": 2.61}, {"text": "We'll be rigorous enough\nin the next slide.", "start": 230.35, "duration": 2.11}, {"text": "So here is, if you will,\nthe big allele, right?", "start": 232.46, "duration": 4.85}, {"text": "It's the original.", "start": 237.31, "duration": 1.28}, {"text": "It's the non-deleted allele.", "start": 238.59, "duration": 1.54}, {"text": "So when you do a PCR\nassay where you're", "start": 240.13, "duration": 2.43}, {"text": "amplifying with two primers\nacross the region that", "start": 242.56, "duration": 3.54}, {"text": "could be deleted\nor not, you'll tend", "start": 246.1, "duration": 2.1}, {"text": "to get a large\namplification product.", "start": 248.2, "duration": 2.16}, {"text": "You prime synthesis\nuntil you get something", "start": 250.36, "duration": 3.81}, {"text": "which has 403 base pairs.", "start": 254.17, "duration": 2.185}, {"text": "And there's enough of it\nthat you can display it", "start": 256.355, "duration": 2.0}, {"text": "on electrophoretic gel,\nand it migrates slowly", "start": 258.355, "duration": 2.745}, {"text": "because it's large.", "start": 261.1, "duration": 2.22}, {"text": "If you have a homozygote\nfor the deletion allele--", "start": 263.32, "duration": 2.79}, {"text": "we'll not call it the HIV\nresistance allele just yet--", "start": 266.11, "duration": 4.29}, {"text": "then you'll get a\n371-base-pair PCR product.", "start": 270.4, "duration": 4.8}, {"text": "And if you have\nthe heterozygote,", "start": 275.2, "duration": 1.5}, {"text": "you'll get both, the large and\nthe small allele represented", "start": 276.7, "duration": 3.39}, {"text": "on this electrophoretic assay.", "start": 280.09, "duration": 1.47}, {"text": "A very simple, very robust\nDNA PCR-based assay.", "start": 281.56, "duration": 4.26}, {"text": "So now let's ask whether\none allele or the other", "start": 289.32, "duration": 6.11}, {"text": "is more abundant in people\nwhich are observed to be", "start": 295.43, "duration": 5.25}, {"text": "seropositive or seronegative.", "start": 300.68, "duration": 1.98}, {"text": "Seropositive means\nthat they have", "start": 302.66, "duration": 2.04}, {"text": "circulating antibodies\nin their serum", "start": 304.7, "duration": 2.82}, {"text": "which react positively\nto the HIV virus.", "start": 307.52, "duration": 4.53}, {"text": "And so that's not\nnecessarily, but is commonly", "start": 312.05, "duration": 5.11}, {"text": "associated with being heavily\nexposed to the HIV virus,", "start": 317.16, "duration": 3.26}, {"text": "and therefore\nbasically infected.", "start": 320.42, "duration": 2.28}, {"text": "Seronegative means\nthat you are--", "start": 322.7, "duration": 4.62}, {"text": "it's an indication\nthat you're resistant.", "start": 327.32, "duration": 2.19}, {"text": "Now we could do this as\na two-by-two matrix here", "start": 329.51, "duration": 4.125}, {"text": "of alleles versus\noutcomes, or we", "start": 333.635, "duration": 3.555}, {"text": "could do it as a\nthree-by-two where we", "start": 337.19, "duration": 2.25}, {"text": "have genotypes versus outcomes.", "start": 339.44, "duration": 2.94}, {"text": "The three genotypes are\nbig-big, little-little,", "start": 342.38, "duration": 4.05}, {"text": "and big-little heterozygote.", "start": 346.43, "duration": 1.635}, {"text": "But let's just do it-- just keep\nit simple in terms of alleles.", "start": 348.065, "duration": 2.625}, {"text": "If there is a selective advan--", "start": 350.69, "duration": 2.19}, {"text": "or there's a\nperceivable association", "start": 352.88, "duration": 4.98}, {"text": "between the seropositive,\nseronegative, and the allele,", "start": 357.86, "duration": 3.93}, {"text": "you should be able to see it\nin both the genotype or just", "start": 361.79, "duration": 3.565}, {"text": "the allele.", "start": 365.355, "duration": 0.5}, {"text": "The allele is simpler.", "start": 365.855, "duration": 1.155}, {"text": "It's a two-by-two matrix.", "start": 367.01, "duration": 1.53}, {"text": "And so these are the data,\njust these four boxes here.", "start": 368.54, "duration": 4.68}, {"text": "The big allele is 1,278 observed\nnegative and 1,368 observed", "start": 373.22, "duration": 7.53}, {"text": "positive for a total of 2,646.", "start": 380.75, "duration": 3.06}, {"text": "You can see that\nthere are fewer total", "start": 383.81, "duration": 2.67}, {"text": "in the population surveyed\nof the deletion mutant.", "start": 386.48, "duration": 3.577}, {"text": "This is consistent with the\nclaim that I made all along.", "start": 390.057, "duration": 2.333}, {"text": "It's about 9% in general\nhuman population,", "start": 392.39, "duration": 2.85}, {"text": "and it's 9% of this population.", "start": 395.24, "duration": 1.995}, {"text": "That's good.", "start": 397.235, "duration": 2.005}, {"text": "But now you have to\ncorrect for that.", "start": 399.24, "duration": 1.64}, {"text": "You need to-- you\ncan't just ask,", "start": 400.88, "duration": 3.24}, {"text": "is it more frequent here or not?", "start": 404.12, "duration": 1.47}, {"text": "You have to correct for\nthe actual frequencies", "start": 405.59, "duration": 2.52}, {"text": "in the population.", "start": 408.11, "duration": 0.78}, {"text": "And the way that's done is you\ncalculate another table, which", "start": 408.89, "duration": 6.33}, {"text": "is the expected number of each\nof these combinations of big", "start": 415.22, "duration": 6.6}, {"text": "with seronegative,\nbig with seropositive,", "start": 421.82, "duration": 1.86}, {"text": "and so forth, under\nthe assumption", "start": 423.68, "duration": 2.19}, {"text": "that it's completely random.", "start": 425.87, "duration": 1.965}, {"text": "You know the allele\nfrequencies in the population,", "start": 427.835, "duration": 2.385}, {"text": "but say that they just randomly\nassociated with whether it's", "start": 430.22, "duration": 3.405}, {"text": "seropositive or seronegative.", "start": 433.625, "duration": 1.545}, {"text": "You use these totals\nhere and the frequencies", "start": 435.17, "duration": 2.61}, {"text": "in the population to\ngenerate this expected end", "start": 437.78, "duration": 3.75}, {"text": "of the random assumption.", "start": 441.53, "duration": 1.17}, {"text": "And then you look for\ndeviation of the real ones", "start": 442.7, "duration": 3.09}, {"text": "of the observed\nversus the expected.", "start": 445.79, "duration": 1.715}, {"text": "So any deviation between the\nexpected and the observed", "start": 454.99, "duration": 4.32}, {"text": "is going to be\nsignificant in this.", "start": 459.31, "duration": 1.59}, {"text": "So you want to do is take the\ndifference between the observed", "start": 463.49, "duration": 3.23}, {"text": "and expected.", "start": 466.72, "duration": 0.71}, {"text": "So we're working on\na statistic here,", "start": 467.43, "duration": 2.41}, {"text": "a type of measure\nthat will determine,", "start": 469.84, "duration": 2.28}, {"text": "how far from expectation\nare the observations", "start": 472.12, "duration": 3.36}, {"text": "on the left-hand side\nin this two-by-two?", "start": 475.48, "duration": 3.27}, {"text": "And so for every square\nin the two-by-two,", "start": 478.75, "duration": 3.39}, {"text": "you find a corresponding\nexpected number", "start": 482.14, "duration": 2.64}, {"text": "and you subtract it.", "start": 484.78, "duration": 1.14}, {"text": "That's the starting point.", "start": 485.92, "duration": 1.29}, {"text": "But you don't care whether\nit's negative or positive.", "start": 487.21, "duration": 3.66}, {"text": "You want to make it positive.", "start": 490.87, "duration": 1.51}, {"text": "So the trick we'll often use\nis to take the square of that.", "start": 492.38, "duration": 2.598}, {"text": "So you could take\nthe absolute value.", "start": 494.978, "duration": 1.542}, {"text": "You take the square for the\nchi-square, oddly enough.", "start": 496.52, "duration": 3.11}, {"text": "And then you want to put it\non some kind of standard scale", "start": 499.63, "duration": 3.84}, {"text": "so that when you do a chi-square\nfor any kind of phenomenon,", "start": 503.47, "duration": 3.57}, {"text": "you'll be able to compare.", "start": 507.04, "duration": 1.2}, {"text": "And the way you do that is you\ndivide by the expected number.", "start": 508.24, "duration": 3.63}, {"text": "Or as this puts it on, if\nthese numbers were really huge,", "start": 511.87, "duration": 4.53}, {"text": "this would bring them down.", "start": 516.4, "duration": 3.13}, {"text": "Very small, it'll\nbring the same point.", "start": 519.53, "duration": 2.34}, {"text": "And so you take the sum over\nall the squares in here,", "start": 521.87, "duration": 3.45}, {"text": "and that's 15.6.", "start": 525.32, "duration": 1.94}, {"text": "And that's saying that it\ndeviates from the expectation", "start": 527.26, "duration": 5.89}, {"text": "by this amount normalized as\na fraction of the expected.", "start": 533.15, "duration": 5.49}, {"text": "Now to determine just a little\nsidelight on the chi-square,", "start": 538.64, "duration": 5.34}, {"text": "in order to determine\nthe probability of 15.6", "start": 543.98, "duration": 3.42}, {"text": "being significant,\nwhat does that", "start": 547.4, "duration": 1.41}, {"text": "mean, looking at this at 15.6?", "start": 548.81, "duration": 1.952}, {"text": "You want to turn this\ninto a probability,", "start": 550.762, "duration": 1.708}, {"text": "because probabilities are the\ncommon language that we can all", "start": 552.47, "duration": 2.67}, {"text": "share our surprise at this\nbeing different from expected,", "start": 555.14, "duration": 4.29}, {"text": "the null hypothesis that\nthis is the same as expected.", "start": 559.43, "duration": 2.825}, {"text": "And so in order\nto evaluate that,", "start": 562.255, "duration": 1.375}, {"text": "you have to ask how\nmuch freedom there--", "start": 563.63, "duration": 2.22}, {"text": "degrees of freedom.", "start": 565.85, "duration": 1.18}, {"text": "This is jargon for,\nhow many different ways", "start": 567.03, "duration": 5.26}, {"text": "can these two numbers vary?", "start": 572.29, "duration": 1.72}, {"text": "Well, since we know\nthe total number,", "start": 574.01, "duration": 2.96}, {"text": "when we observe the number of\nCCR5, that fixes in the columns", "start": 576.97, "duration": 7.15}, {"text": "the number of deletions, right?", "start": 584.12, "duration": 1.68}, {"text": "Because it's just going to be\nthe number of big alleles taken", "start": 585.8, "duration": 3.45}, {"text": "from the total.", "start": 589.25, "duration": 1.48}, {"text": "So in a way, the degrees\nof freedom is just one.", "start": 590.73, "duration": 2.18}, {"text": "You fixed this one number, and\nthe other one is now known.", "start": 592.91, "duration": 4.44}, {"text": "And the same thing's true\nfor rows and columns.", "start": 597.35, "duration": 2.08}, {"text": "So the rows minus--", "start": 599.43, "duration": 1.19}, {"text": "it's just one and\nthe columns is one.", "start": 600.62, "duration": 2.49}, {"text": "And so the whole\ndegrees of freedom", "start": 603.11, "duration": 1.83}, {"text": "is the product that rows\nand columns, which is one.", "start": 604.94, "duration": 2.97}, {"text": "So you plug this in.", "start": 607.91, "duration": 0.93}, {"text": "If you look in your\nstandard statistical--", "start": 608.84, "duration": 1.92}, {"text": "or your favorite statistical\nbook or software package, Excel", "start": 610.76, "duration": 3.84}, {"text": "or whatever, you plug\nin this chi-square value", "start": 614.6, "duration": 2.82}, {"text": "and this degrees of freedom,\nand you get this probability,", "start": 617.42, "duration": 2.95}, {"text": "which is very significant.", "start": 620.37, "duration": 1.52}, {"text": "Generally better than 5%\nmeans that you will only", "start": 621.89, "duration": 5.22}, {"text": "be wrong 20% of the time.", "start": 627.11, "duration": 2.32}, {"text": "Some people would prefer to--", "start": 629.43, "duration": 2.69}, {"text": "this means you'll be wrong eight\ntimes in 10,000 or something", "start": 632.12, "duration": 4.21}, {"text": "like that.", "start": 636.33, "duration": 0.5}, {"text": "Very, very infrequently.", "start": 636.83, "duration": 2.64}, {"text": "OK.", "start": 639.47, "duration": 1.17}, {"text": "Now this is great.", "start": 640.64, "duration": 1.84}, {"text": "This is a two-by-two matrix.", "start": 642.48, "duration": 1.25}, {"text": "We found an association.", "start": 643.73, "duration": 1.56}, {"text": "We have a plausible\nmolecular mechanism", "start": 645.29, "duration": 2.79}, {"text": "in the previous slide.", "start": 648.08, "duration": 1.56}, {"text": "But how was it that\nwe pulled CCR5 out", "start": 649.64, "duration": 3.69}, {"text": "of-- this rabbit out of the hat?", "start": 653.33, "duration": 1.5}, {"text": "I mean, why CCR5?", "start": 654.83, "duration": 2.43}, {"text": "There are 40,000-some\ngenes in the human genome.", "start": 657.26, "duration": 3.09}, {"text": "Yes?", "start": 660.35, "duration": 0.57}, {"text": "AUDIENCE: What is it?", "start": 660.92, "duration": 0.875}, {"text": "I was curious as to,\nwhat population is it?", "start": 661.795, "duration": 4.165}, {"text": "I mean, in which there's\nslightly more seropositive", "start": 665.96, "duration": 5.272}, {"text": "or seronegative people.", "start": 671.232, "duration": 0.958}, {"text": "This must be a particular--", "start": 672.19, "duration": 2.754}, {"text": "GEORGE CHURCH: Oh, yeah.", "start": 674.944, "duration": 2.286}, {"text": "This is a case\ncontrol study where", "start": 677.23, "duration": 1.89}, {"text": "you try to get a roughly\nequal number of negatives", "start": 679.12, "duration": 2.88}, {"text": "and positives that are matched\nfor socioeconomic group", "start": 682.0, "duration": 3.45}, {"text": "and race and gender\nand things like that.", "start": 685.45, "duration": 2.37}, {"text": "So that's a setup.", "start": 687.82, "duration": 1.51}, {"text": "But then the-- if there's not\na huge risk ratio for the two", "start": 689.33, "duration": 6.29}, {"text": "alleles, then you'll expect them\nto be close to the population", "start": 695.62, "duration": 2.66}, {"text": "frequency, which means\nthat you can't just", "start": 698.28, "duration": 1.75}, {"text": "look at it on inspection\nand say, oh, yeah.", "start": 700.03, "duration": 2.46}, {"text": "All the seropositive\nare the big allele.", "start": 702.49, "duration": 2.79}, {"text": "We wouldn't need a\nchi-square at that point.", "start": 705.28, "duration": 2.88}, {"text": "But this is pretty close to\nthe population frequency,", "start": 708.16, "duration": 3.79}, {"text": "and so that's why we\nhad to do a chi-square.", "start": 711.95, "duration": 4.0}, {"text": "OK.", "start": 715.95, "duration": 1.5}, {"text": "But the question\nthat we're taking now", "start": 717.45, "duration": 5.73}, {"text": "is, how did we pick CCR5?", "start": 723.18, "duration": 1.45}, {"text": "And I introduced this as\nbeing a putative receptor", "start": 724.63, "duration": 3.56}, {"text": "for the virus, but one of\nthe first pieces of evidence", "start": 728.19, "duration": 2.842}, {"text": "that this was a putative\nreceptor for the virus", "start": 731.032, "duration": 1.958}, {"text": "was this association study.", "start": 732.99, "duration": 2.71}, {"text": "So how was it that it hit\nthe chemokine receptor?", "start": 735.7, "duration": 3.632}, {"text": "Well, you could say, well,\nbecause some kind of hunch", "start": 739.332, "duration": 2.208}, {"text": "about chemokines being\ninvolved in immunology,", "start": 741.54, "duration": 2.49}, {"text": "and immunology being\nimportant in fighting viruses,", "start": 744.03, "duration": 3.69}, {"text": "but that wouldn't suggest\nthat it's an actual receptor.", "start": 747.72, "duration": 2.64}, {"text": "I think these are--", "start": 753.51, "duration": 1.64}, {"text": "there's all kinds of\ninspired guesswork.", "start": 755.15, "duration": 1.93}, {"text": "There's biochemistry happening\nbehind the scene, and so on.", "start": 757.08, "duration": 2.925}, {"text": "But let's just put that\naside for the moment", "start": 760.005, "duration": 2.17}, {"text": "and take the more\ngeneral case that you", "start": 762.175, "duration": 1.625}, {"text": "wanted to test not just\nthis one hypothesis,", "start": 763.8, "duration": 2.64}, {"text": "that CCR5 is involved,\nbut you've implicitly", "start": 766.44, "duration": 2.67}, {"text": "then tested or explicitly\ntested every gene.", "start": 769.11, "duration": 3.812}, {"text": "You've gone through\nevery gene and you've", "start": 772.922, "duration": 1.708}, {"text": "taken either the most\ncommon alleles or you've", "start": 774.63, "duration": 3.12}, {"text": "sequenced your own\ngenome and you've", "start": 777.75, "duration": 1.59}, {"text": "found the alleles that you have,\nwhether they're common or rare.", "start": 779.34, "duration": 3.275}, {"text": "You don't care.", "start": 782.615, "duration": 0.625}, {"text": "And you want to ask,\nwhat's the association?", "start": 783.24, "duration": 2.82}, {"text": "Let's consider the upper\nright-hand panel here", "start": 790.85, "duration": 4.35}, {"text": "where we have some risk ratio,\na fairly subtle one, 1.5.", "start": 795.2, "duration": 5.46}, {"text": "Remember, we were talking\nabout risk ratios of 75", "start": 800.66, "duration": 2.64}, {"text": "in the case of autism.", "start": 803.3, "duration": 1.05}, {"text": "This is just 1.5.", "start": 804.35, "duration": 1.02}, {"text": "Very subtle risk ratio, just\nlike I think in the last one", "start": 805.37, "duration": 4.02}, {"text": "could have been a\nsubtle risk ratio.", "start": 809.39, "duration": 1.86}, {"text": "And the x-axis is going to\nbe the number of alleles", "start": 813.93, "duration": 4.535}, {"text": "that you're\nhypothetically testing.", "start": 818.465, "duration": 2.115}, {"text": "This could be related\nto the number of genes", "start": 820.58, "duration": 1.92}, {"text": "that you're testing,\nor it could be", "start": 822.5, "duration": 1.98}, {"text": "more than the number of\ngenes that you're testing,", "start": 824.48, "duration": 1.56}, {"text": "because you can have more\nthan one allele per gene", "start": 826.04, "duration": 2.04}, {"text": "that you might want to test.", "start": 828.08, "duration": 1.167}, {"text": "Is this allele of this gene\nimportant in this disease,", "start": 829.247, "duration": 3.153}, {"text": "or is this other one?", "start": 832.4, "duration": 1.245}, {"text": "For example, sickle\ncell is important,", "start": 833.645, "duration": 2.085}, {"text": "but various other hemoglobin\nmutations are not.", "start": 835.73, "duration": 3.51}, {"text": "This chemokine deletion is\nimportant and maybe another one", "start": 839.24, "duration": 2.67}, {"text": "isn't.", "start": 841.91, "duration": 0.72}, {"text": "Many chemokine mutations\nwill be neutral.", "start": 842.63, "duration": 3.11}, {"text": "OK.", "start": 845.74, "duration": 0.5}, {"text": "So as you increase the number\nof genes and alleles from--", "start": 846.24, "duration": 3.77}, {"text": "here's 10 to the fourth on up--", "start": 850.01, "duration": 2.67}, {"text": "then the number of sib pairs--", "start": 852.68, "duration": 3.24}, {"text": "so this is a simulation covering\nall kinds of experiments", "start": 855.92, "duration": 4.65}, {"text": "that you could do\nwhere you can use", "start": 860.57, "duration": 3.03}, {"text": "computational\nmethods to help guide", "start": 863.6, "duration": 1.86}, {"text": "the design of experiments.", "start": 865.46, "duration": 2.4}, {"text": "If you did an\nexpensive experiment", "start": 867.86, "duration": 1.59}, {"text": "and you just happened to\nuse too few patients and too", "start": 869.45, "duration": 3.87}, {"text": "many alleles, then you may\nhave misused your resources.", "start": 873.32, "duration": 3.255}, {"text": "You should have maybe done\nfewer alleles and more patients", "start": 876.575, "duration": 2.535}, {"text": "or something like that.", "start": 879.11, "duration": 2.68}, {"text": "And this provides\nsome guidance here.", "start": 881.79, "duration": 1.82}, {"text": "But you can see\nthat in order to get", "start": 883.61, "duration": 1.68}, {"text": "to a very large\nnumber of alleles,", "start": 885.29, "duration": 1.98}, {"text": "you need a fairly\nmodest increase", "start": 887.27, "duration": 1.68}, {"text": "in the number of patients.", "start": 888.95, "duration": 1.09}, {"text": "And that's due to\nthe exponential term", "start": 890.04, "duration": 4.43}, {"text": "that you have in these\nprobability distributions.", "start": 894.47, "duration": 4.69}, {"text": "So you actually--\nbut nevertheless,", "start": 899.16, "duration": 1.97}, {"text": "it's a big deal cost-wise\ngoing up from, say,", "start": 901.13, "duration": 5.49}, {"text": "400 patients to 1,600.", "start": 906.62, "duration": 4.5}, {"text": "Nevertheless, it's\nonly linear in patients", "start": 911.12, "duration": 2.85}, {"text": "while it's exponential in the\nnumber of alleles you can test,", "start": 913.97, "duration": 4.47}, {"text": "so that's the good news.", "start": 918.44, "duration": 2.03}, {"text": "And you can see some\nof these other panels", "start": 920.47, "duration": 1.75}, {"text": "show the effect of\nvarying other parameters.", "start": 922.22, "duration": 4.35}, {"text": "For example, here\non the left you've", "start": 926.57, "duration": 1.92}, {"text": "got varying the population\nfrequency of the allele.", "start": 928.49, "duration": 3.99}, {"text": "As you get to very,\nvery rare alleles", "start": 932.48, "duration": 3.15}, {"text": "on the right hand of the\nhorizontal axis here, then", "start": 935.63, "duration": 4.26}, {"text": "the number of sib pairs--", "start": 939.89, "duration": 4.32}, {"text": "brothers-sisters,\nbrother-brothers", "start": 944.21, "duration": 1.8}, {"text": "that you need-- starts\nto go through the roof.", "start": 946.01, "duration": 2.19}, {"text": "And now it's exponential\non both axes,", "start": 948.2, "duration": 4.86}, {"text": "or that is to say that\nit's a direct relationship.", "start": 953.06, "duration": 2.31}, {"text": "Question?", "start": 955.37, "duration": 0.54}, {"text": "AUDIENCE: What's that\nz value over there?", "start": 955.91, "duration": 1.718}, {"text": "GEORGE CHURCH: Hmm?", "start": 957.628, "duration": 0.792}, {"text": "AUDIENCE: What's that\nz value of over there?", "start": 958.42, "duration": 2.53}, {"text": "GEORGE CHURCH: Oh, that's\nthe population frequency that", "start": 960.95, "duration": 4.345}, {"text": "you're--", "start": 965.295, "duration": 0.5}, {"text": "AUDIENCE: On the bottom?", "start": 965.795, "duration": 1.199}, {"text": "GEORGE CHURCH: Hmm?", "start": 966.994, "duration": 0.946}, {"text": "Well, on-- on the one we were\njust talking about on the left,", "start": 967.94, "duration": 4.86}, {"text": "the population frequency\nis the horizontal axis,", "start": 972.8, "duration": 2.52}, {"text": "and it varies from near unity\nto 10 to the minus nine.", "start": 975.32, "duration": 5.34}, {"text": "It's a very rare\nallele frequency.", "start": 980.66, "duration": 3.3}, {"text": "On the right, the one we\nstarted with, the top right,", "start": 983.96, "duration": 3.78}, {"text": "we just picked 0.5,\nwhich would be very--", "start": 987.74, "duration": 3.24}, {"text": "be around here on the left-hand\nend of the left-hand quadrant.", "start": 990.98, "duration": 4.84}, {"text": "So you pick one of these\nallele frequencies, a fairly--", "start": 995.82, "duration": 2.66}, {"text": "where it's equal\nfrequency of the two", "start": 998.48, "duration": 1.95}, {"text": "alleles in the\npopulation as where you", "start": 1000.43, "duration": 2.62}, {"text": "do the rest of the simulation.", "start": 1003.05, "duration": 1.25}, {"text": "You can think of\nall these panels", "start": 1004.3, "duration": 2.43}, {"text": "could be some\nmulti-dimensional display,", "start": 1006.73, "duration": 1.74}, {"text": "but I wanted to take\nthem out one at a time.", "start": 1008.47, "duration": 2.76}, {"text": "And actually, I did\nall these in Excel", "start": 1011.23, "duration": 3.48}, {"text": "using the equations that are\npresent in this reference", "start": 1014.71, "duration": 3.92}, {"text": "that's given in the slides here.", "start": 1018.63, "duration": 2.44}, {"text": "A good sign of a\nwell-written paper", "start": 1024.53, "duration": 1.77}, {"text": "is for a sort of\naverage individual", "start": 1026.3, "duration": 2.309}, {"text": "to be able to reproduce it.", "start": 1028.609, "duration": 2.891}, {"text": "So we have how many--\nso we've been talking", "start": 1031.5, "duration": 5.2}, {"text": "about new polymorphisms.", "start": 1036.7, "duration": 2.34}, {"text": "In fact, the question that\ncame up during the break", "start": 1039.04, "duration": 2.25}, {"text": "was, if selection and drift\ncause allele frequencies to fix", "start": 1041.29, "duration": 6.779}, {"text": "fairly rapidly, drift\nin small populations,", "start": 1048.069, "duration": 3.511}, {"text": "normal-sized\npopulations will drift", "start": 1051.58, "duration": 1.95}, {"text": "in fairly short evolutionary\ntimes and selection", "start": 1053.53, "duration": 4.303}, {"text": "if you have a high selection\ncoefficient of cost fixation.", "start": 1057.833, "duration": 2.417}, {"text": "Why do we have any allele\nfrequencies at all?", "start": 1060.25, "duration": 1.89}, {"text": "Why isn't everything fixed at\n100% for one particular allele?", "start": 1062.14, "duration": 4.5}, {"text": "And the answer is mutation.", "start": 1066.64, "duration": 1.53}, {"text": "And where all these new\nmutations or polymorphisms", "start": 1068.17, "duration": 2.408}, {"text": "come from-- actually,\nthese should probably", "start": 1070.578, "duration": 1.792}, {"text": "be called mutations,\nbecause most of them", "start": 1072.37, "duration": 2.1}, {"text": "have frequencies less than 1%.", "start": 1074.47, "duration": 2.31}, {"text": "Well, here's a specific model\nwhich doesn't follow all", "start": 1076.78, "duration": 3.103}, {"text": "the assumptions we had before,\nbut we'll use a different--", "start": 1079.883, "duration": 2.417}, {"text": "we'll use a back-of-the-envelope\ncalculation to give you", "start": 1082.3, "duration": 2.333}, {"text": "a feeling for what\nis true for the--", "start": 1084.633, "duration": 3.517}, {"text": "what is likely to be the case\nfor the human population.", "start": 1088.15, "duration": 2.77}, {"text": "So the human population,\nthere's a little bit", "start": 1090.92, "duration": 2.39}, {"text": "of unknown in some\nof these parameters,", "start": 1093.31, "duration": 2.99}, {"text": "so you should take these all\nwith a grain of salt. Actually,", "start": 1096.3, "duration": 2.5}, {"text": "everything I say\nyou should take.", "start": 1098.8, "duration": 1.42}, {"text": "But the number of\npopulations that we've", "start": 1100.22, "duration": 4.25}, {"text": "had since a bottleneck\nin the human population--", "start": 1104.47, "duration": 3.75}, {"text": "maybe there were as few\nas 10 to the fourth humans", "start": 1108.22, "duration": 3.12}, {"text": "at some point or another.", "start": 1111.34, "duration": 2.28}, {"text": "Maybe less.", "start": 1113.62, "duration": 1.68}, {"text": "But since that time, there have\nbeen about 5,000 generations.", "start": 1115.3, "duration": 2.91}, {"text": "And during that\ntime, our population", "start": 1118.21, "duration": 1.68}, {"text": "has now grown to\nsix billion people.", "start": 1119.89, "duration": 2.25}, {"text": "That's the n prime nn.", "start": 1122.14, "duration": 3.57}, {"text": "And the mutation rate, as\nmentioned earlier in response", "start": 1125.71, "duration": 6.073}, {"text": "to a question, is\naround 10 to the minus", "start": 1131.783, "duration": 1.667}, {"text": "eighth per base pair per\ngenome per generation.", "start": 1133.45, "duration": 6.13}, {"text": "And so the genome size\nis about six billion.", "start": 1139.58, "duration": 2.69}, {"text": "Coincidentally, the same\nas the population size.", "start": 1142.27, "duration": 2.16}, {"text": "Total coincidence.", "start": 1144.43, "duration": 1.95}, {"text": "Then 10 to the minus eight\ntimes that number of base pairs", "start": 1146.38, "duration": 3.45}, {"text": "means you have\nabout 60 mutations", "start": 1149.83, "duration": 2.49}, {"text": "or so occurring in a generation.", "start": 1152.32, "duration": 4.99}, {"text": "So you've got a steady\nflow of new mutations.", "start": 1157.31, "duration": 2.74}, {"text": "Now if you take\nthat-- just roughly", "start": 1160.05, "duration": 1.57}, {"text": "speaking, if you take that\nover 5,000 generations,", "start": 1161.62, "duration": 2.31}, {"text": "you've got 60 times 5,000.", "start": 1163.93, "duration": 2.7}, {"text": "You've got a very large number--", "start": 1166.63, "duration": 1.86}, {"text": "on the order of 10 to\nthe fourth mutations", "start": 1168.49, "duration": 3.21}, {"text": "that have accumulated\nin our population.", "start": 1171.7, "duration": 1.93}, {"text": "Assuming relatively\nlittle drift because", "start": 1173.63, "duration": 3.26}, {"text": "of this exponentially growing\npopulation and relatively", "start": 1176.89, "duration": 2.67}, {"text": "little selection, then\nthis is the number", "start": 1179.56, "duration": 3.27}, {"text": "that might have accumulated.", "start": 1182.83, "duration": 1.41}, {"text": "You can do subtle corrections\nfor this exponential growth.", "start": 1184.24, "duration": 4.68}, {"text": "The number of mutations\nyou got at the beginning", "start": 1188.92, "duration": 3.073}, {"text": "will have higher frequency,\nbut there'll be fewer of them,", "start": 1191.993, "duration": 2.417}, {"text": "because population was smaller.", "start": 1194.41, "duration": 1.332}, {"text": "But anyway, you\nget the picture, is", "start": 1195.742, "duration": 1.458}, {"text": "that the total\nnumber of mutations", "start": 1197.2, "duration": 1.89}, {"text": "in any one of this that\nare new since that new--", "start": 1199.09, "duration": 3.27}, {"text": "since 5,000 generations ago\nwill be on the order of 10", "start": 1202.36, "duration": 4.03}, {"text": "to the fourth in your body, not\nall of them doing good for you.", "start": 1206.39, "duration": 5.99}, {"text": "And for each of those\nrare mutations--", "start": 1212.38, "duration": 2.717}, {"text": "they might have a frequency of\nabout 10 to the minus five--", "start": 1215.097, "duration": 2.458}, {"text": "there will be about 10 to\nthe fourth people on Earth", "start": 1221.67, "duration": 4.348}, {"text": "that will share that very\nrare mutation with you.", "start": 1226.018, "duration": 2.042}, {"text": "10 to the minus 5\nsounds very rare,", "start": 1228.06, "duration": 2.782}, {"text": "but when you multiply it\nby six billion people,", "start": 1230.842, "duration": 1.958}, {"text": "there are a lot of people\nwho share that with you.", "start": 1232.8, "duration": 2.34}, {"text": "It's a new mutation.", "start": 1235.14, "duration": 1.85}, {"text": "OK.", "start": 1236.99, "duration": 0.5}, {"text": "So the take-home is--", "start": 1237.49, "duration": 1.49}, {"text": "and this is from\nthis reference here.", "start": 1238.98, "duration": 3.36}, {"text": "High genomic\ndeleterious mutations", "start": 1242.34, "duration": 3.36}, {"text": "accumulate over these 4,000--", "start": 1245.7, "duration": 3.48}, {"text": "some large number\nof generations.", "start": 1249.18, "duration": 1.92}, {"text": "And they would confound\nlinkage methods", "start": 1251.1, "duration": 2.7}, {"text": "and they would\nconfound assumptions", "start": 1253.8, "duration": 2.04}, {"text": "that say that the\ncommon alleles--", "start": 1255.84, "duration": 2.28}, {"text": "common alleles are causative.", "start": 1258.12, "duration": 4.07}, {"text": "OK.", "start": 1262.19, "duration": 0.51}, {"text": "So let's say we've done\nan association study.", "start": 1262.7, "duration": 2.25}, {"text": "Either we've done it\non one gene, picked", "start": 1264.95, "duration": 2.25}, {"text": "one out of the hat\nlike CCR5, or we've", "start": 1267.2, "duration": 2.28}, {"text": "done it on a full genome\nsurvey, 40,000 genes,", "start": 1269.48, "duration": 2.58}, {"text": "all the alleles we know of.", "start": 1272.06, "duration": 3.06}, {"text": "In order to do the latter,\nwe had to have a big patient", "start": 1275.12, "duration": 3.06}, {"text": "population.", "start": 1278.18, "duration": 1.69}, {"text": "But let's say we've done that.", "start": 1279.87, "duration": 1.25}, {"text": "Now we want to prove that\nthat association is--", "start": 1281.12, "duration": 3.9}, {"text": "that great statistic\nthat we got out,", "start": 1285.02, "duration": 1.83}, {"text": "if we have a large enough\npatient population,", "start": 1286.85, "duration": 1.89}, {"text": "is still just a statistic.", "start": 1288.74, "duration": 2.25}, {"text": "What will constitute proof is\nafter we find the association,", "start": 1290.99, "duration": 4.05}, {"text": "we make a copy of that\nmutation, isolated away", "start": 1295.04, "duration": 3.51}, {"text": "from the three million\nother polymorphisms that", "start": 1298.55, "duration": 2.55}, {"text": "are floating around\nin your body,", "start": 1301.1, "duration": 2.77}, {"text": "and we do some kind of test.", "start": 1303.87, "duration": 1.52}, {"text": "Ideally, we would\nmake an isogenic pair", "start": 1305.39, "duration": 3.12}, {"text": "of humans that only differ\nby this one mutation.", "start": 1308.51, "duration": 2.94}, {"text": "That is not generally considered\nmedically feasible or ethical.", "start": 1311.45, "duration": 7.53}, {"text": "But somehow or another, you\ncan do it on human cells", "start": 1318.98, "duration": 2.61}, {"text": "or you can do it in a\nmammalian model system.", "start": 1321.59, "duration": 5.52}, {"text": "But you have to make\nsomething that's", "start": 1327.11, "duration": 1.77}, {"text": "close to isogenic, a\ncopy of this mutation,", "start": 1328.88, "duration": 2.7}, {"text": "and show that it has a\nphenotype that makes sense.", "start": 1331.58, "duration": 3.22}, {"text": "And then, just to make\nsure you haven't introduced", "start": 1334.8, "duration": 2.27}, {"text": "other mutations, the\nreally careful scientists", "start": 1337.07, "duration": 3.24}, {"text": "will then revert that one\npolymorphism and show now", "start": 1340.31, "duration": 3.3}, {"text": "you no longer have\nthat phenotype.", "start": 1343.61, "duration": 2.46}, {"text": "OK.", "start": 1346.07, "duration": 0.96}, {"text": "So let's walk\nthrough an example.", "start": 1347.03, "duration": 4.45}, {"text": "Here's the third\nexample in this lecture", "start": 1351.48, "duration": 4.51}, {"text": "of a very specific\nallele where we've", "start": 1355.99, "duration": 2.8}, {"text": "shown the molecular\nbasis of it, and it's", "start": 1358.79, "duration": 2.22}, {"text": "the second example\nwhere it's not coding,", "start": 1361.01, "duration": 2.148}, {"text": "and it's the second example\nwhere it's going to repeat.", "start": 1363.158, "duration": 2.292}, {"text": "So this is just to--", "start": 1365.45, "duration": 1.71}, {"text": "I'm not giving you a\nrandom sample here.", "start": 1367.16, "duration": 1.71}, {"text": "I'm specifically biasing this\ntowards very interesting genes,", "start": 1368.87, "duration": 4.77}, {"text": "very interesting traits\nthat are associated", "start": 1373.64, "duration": 3.6}, {"text": "with non-coding\nrepetitive alleles.", "start": 1377.24, "duration": 2.91}, {"text": "In this case, the trait\nthat got the attention", "start": 1380.15, "duration": 3.6}, {"text": "of these researchers-- it\nisn't necessarily proven", "start": 1383.75, "duration": 3.12}, {"text": "that this is the relationship.", "start": 1386.87, "duration": 2.37}, {"text": "But the association\nthat was studied", "start": 1389.24, "duration": 1.65}, {"text": "was between anxiety-related\ntraits, anxiety,", "start": 1390.89, "duration": 4.35}, {"text": "and a polymorphism in the\nserotonin transporter.", "start": 1395.24, "duration": 3.6}, {"text": "This is a science paper.", "start": 1398.84, "duration": 3.3}, {"text": "Now the next step\nin this is to--", "start": 1402.14, "duration": 2.4}, {"text": "OK, that was found associated.", "start": 1404.54, "duration": 2.28}, {"text": "There were lots of other alleles\nrandomly being moved around,", "start": 1406.82, "duration": 6.51}, {"text": "because these are humans.", "start": 1413.33, "duration": 1.74}, {"text": "We have no control over who\nmates with who, or very little.", "start": 1415.07, "duration": 4.362}, {"text": "So you get what you're given.", "start": 1422.21, "duration": 1.98}, {"text": "You can do the survey\nas best you can.", "start": 1424.19, "duration": 1.83}, {"text": "But now in order to move it\ntowards a mechanistic basis", "start": 1426.02, "duration": 4.59}, {"text": "and a proof of introducing\njust this one point mutation.", "start": 1430.61, "duration": 3.69}, {"text": "Now what is the mutation\nfound in this case of anxiety", "start": 1434.3, "duration": 3.75}, {"text": "relationship in this\nserotonin transporter?", "start": 1438.05, "duration": 2.74}, {"text": "It's upstream of the first\nRNA encoding axon one.", "start": 1440.79, "duration": 4.34}, {"text": "It is a 44 base pair deletion\nin a repetitive region,", "start": 1445.13, "duration": 3.95}, {"text": "in a region which might be\nresponsible for promoting", "start": 1449.08, "duration": 4.03}, {"text": "transcription.", "start": 1453.11, "duration": 1.65}, {"text": "You have the short and the long\nalleles, just like in the CCR5.", "start": 1454.76, "duration": 3.93}, {"text": "In this case, it's in a\nputative promoter element.", "start": 1458.69, "duration": 2.76}, {"text": "And when you make this\nconstruct and you hook it up", "start": 1461.45, "duration": 3.57}, {"text": "to a luciferase enzymatic\nactivity in vitro,", "start": 1465.02, "duration": 5.95}, {"text": "in cultured cells so\nyou don't actually", "start": 1470.97, "duration": 2.12}, {"text": "have to construct\na mutant human,", "start": 1473.09, "duration": 3.21}, {"text": "you can now see the\nlong allele always", "start": 1476.3, "duration": 2.19}, {"text": "produces higher\nlevels of expression", "start": 1478.49, "duration": 3.33}, {"text": "than the short allele.", "start": 1481.82, "duration": 1.05}, {"text": "And these little error bars\non top of each of the measures", "start": 1482.87, "duration": 5.22}, {"text": "show your statistical measure\nof standard deviation,", "start": 1488.09, "duration": 3.63}, {"text": "as we did in the first lecture.", "start": 1491.72, "duration": 3.195}, {"text": "And if the black mean, which\nis the height of the bar,", "start": 1494.915, "duration": 5.235}, {"text": "is different from the white\nmean by more than a couple", "start": 1500.15, "duration": 3.143}, {"text": "of these standard deviations,\nwhich is the root mean", "start": 1503.293, "duration": 2.167}, {"text": "square of the standard\ndeviations of each", "start": 1505.46, "duration": 3.24}, {"text": "of the measures, then you call\nit statistically significant.", "start": 1508.7, "duration": 4.09}, {"text": "And that's what these\ntriple stars mean.", "start": 1512.79, "duration": 2.0}, {"text": "It's the statistical\nshorthand for this", "start": 1514.79, "duration": 2.37}, {"text": "is statistically significant\nat the cutoff that we're using.", "start": 1517.16, "duration": 3.06}, {"text": "Say, 5%.", "start": 1520.22, "duration": 1.68}, {"text": "Now in this case, it's\nkind of showing off", "start": 1521.9, "duration": 1.86}, {"text": "because every one of\nthem is statistically", "start": 1523.76, "duration": 1.75}, {"text": "significant by two different--", "start": 1525.51, "duration": 4.04}, {"text": "completely different\nassays here.", "start": 1529.55, "duration": 1.56}, {"text": "But the point is\nthis does not prove", "start": 1531.11, "duration": 2.16}, {"text": "that anxiety is meaningfully\nassociated with this.", "start": 1533.27, "duration": 6.27}, {"text": "But it does prove that this\nrepetitive polymorphism", "start": 1539.54, "duration": 5.04}, {"text": "is causally capable of\ndifferential transcription", "start": 1544.58, "duration": 8.25}, {"text": "levels for a reporter gene.", "start": 1552.83, "duration": 2.82}, {"text": "So by introducing it into\na clean cellular system,", "start": 1555.65, "duration": 7.65}, {"text": "you can test at least\npart of the mechanism that", "start": 1563.3, "duration": 3.12}, {"text": "might be involved in the\nassociation that originally", "start": 1566.42, "duration": 2.37}, {"text": "got your attention.", "start": 1568.79, "duration": 2.73}, {"text": "Now as you can\nsee, we're getting", "start": 1571.52, "duration": 2.97}, {"text": "into a fairly mature and fairly\nnew phase of human genetics.", "start": 1574.49, "duration": 6.66}, {"text": "Some of the concepts\nthat are used here", "start": 1581.15, "duration": 1.71}, {"text": "will be useful in a\nvariety of other systems", "start": 1582.86, "duration": 2.58}, {"text": "where we have relatively little\ncontrol over the genetics.", "start": 1585.44, "duration": 3.42}, {"text": "But certainly in humans,\nthere's a very large need.", "start": 1588.86, "duration": 4.65}, {"text": "And where this\nhappened historically", "start": 1593.51, "duration": 2.73}, {"text": "is with Mendelian linkage,\nwhich would involve", "start": 1596.24, "duration": 2.85}, {"text": "very large families with\na complete pedigree,", "start": 1599.09, "duration": 4.86}, {"text": "multi-generation,\ngreat-grandfathers and mothers,", "start": 1603.95, "duration": 3.21}, {"text": "all the way down, hundreds\nof people in a family.", "start": 1607.16, "duration": 3.615}, {"text": "And that's the problem, because\nthere aren't that many diseases", "start": 1610.775, "duration": 2.625}, {"text": "for which you have\nlarge families", "start": 1613.4, "duration": 1.375}, {"text": "with simple Mendelian\ninheritance.", "start": 1614.775, "duration": 1.895}, {"text": "Common diseases tend to\nbe much more complicated,", "start": 1616.67, "duration": 2.34}, {"text": "involving multiple\ngenes simultaneously", "start": 1619.01, "duration": 2.91}, {"text": "and small families.", "start": 1621.92, "duration": 3.36}, {"text": "Then there's linkage\ndisequilibrium,", "start": 1625.28, "duration": 3.72}, {"text": "which depends on\nthese common alleles", "start": 1629.0, "duration": 5.633}, {"text": "where the population has\ngone through a particularly", "start": 1634.633, "duration": 2.167}, {"text": "small bottleneck and where\nyour common allele is", "start": 1636.8, "duration": 3.84}, {"text": "a pretty good distance away\nfrom the causative one.", "start": 1640.64, "duration": 2.76}, {"text": "But it allows you to\nmap it into a ballpark,", "start": 1643.4, "duration": 2.58}, {"text": "and then you hunker down and\ndo the more expensive testing", "start": 1645.98, "duration": 5.22}, {"text": "of hypotheses for all and\nsequencing and looking", "start": 1651.2, "duration": 2.76}, {"text": "for potentially\ncausative alleles.", "start": 1653.96, "duration": 1.728}, {"text": "Once you find a potentially\ncausative allele, something", "start": 1655.688, "duration": 2.292}, {"text": "that looks suspicious,\nmaybe something", "start": 1657.98, "duration": 2.02}, {"text": "that's in a coding region\nthat it's conserved--", "start": 1660.0, "duration": 2.33}, {"text": "that's the first priority,\ndespite all the counterexamples", "start": 1662.33, "duration": 3.18}, {"text": "I've given.", "start": 1665.51, "duration": 1.27}, {"text": "And then you go ahead.", "start": 1666.78, "duration": 1.23}, {"text": "But the problem is that\nyou're at the mercy", "start": 1668.01, "duration": 1.792}, {"text": "of the recombination\nthat might have occurred", "start": 1669.802, "duration": 1.875}, {"text": "in that population, but you get\nto very interesting populations", "start": 1671.677, "duration": 2.803}, {"text": "like people of African\nAmerican descent", "start": 1674.48, "duration": 4.29}, {"text": "where the population\nis very old, hasn't", "start": 1678.77, "duration": 2.88}, {"text": "passed through a\npopulation bottleneck.", "start": 1681.65, "duration": 2.7}, {"text": "The useful linkage\ndisequilibrium", "start": 1684.35, "duration": 2.52}, {"text": "is on a couple of kilobases\nrather than hundreds", "start": 1686.87, "duration": 3.45}, {"text": "of kilobases, so it\nactually is hard to find", "start": 1690.32, "duration": 2.19}, {"text": "things that are linked.", "start": 1692.51, "duration": 1.32}, {"text": "That is to say, insists\nbut not causatives.", "start": 1693.83, "duration": 2.58}, {"text": "Insists to the causative allele.", "start": 1696.41, "duration": 2.97}, {"text": "Instead, you have to look\ndirectly for causative alleles.", "start": 1699.38, "duration": 2.64}, {"text": "And that's where-- now you look\nfor common causative alleles.", "start": 1702.02, "duration": 2.82}, {"text": "This has the problem that\nwe've been talking about,", "start": 1707.765, "duration": 2.125}, {"text": "which is that maybe common\nalleles aren't often causative.", "start": 1709.89, "duration": 4.97}, {"text": "They've been selected out.", "start": 1714.86, "duration": 1.47}, {"text": "So then you get into\nthe scenario, what if we", "start": 1716.33, "duration": 2.07}, {"text": "wanted to look at all alleles?", "start": 1718.4, "duration": 1.53}, {"text": "Well, theoretically, there's\nnothing wrong with that.", "start": 1719.93, "duration": 3.84}, {"text": "It'd be great.", "start": 1723.77, "duration": 1.68}, {"text": "We could do the\nassociation studies.", "start": 1725.45, "duration": 1.62}, {"text": "We'd have to have fairly\nlarge populations.", "start": 1727.07, "duration": 3.24}, {"text": "But you saw it was linear\nwith an exponential increase", "start": 1730.31, "duration": 2.34}, {"text": "in the number of hypotheses, and\nyou could rank those hypotheses", "start": 1732.65, "duration": 3.06}, {"text": "by a priori likelihood and\nso forth, but it's expensive.", "start": 1735.71, "duration": 3.57}, {"text": "And so the discussion\nnow has to include", "start": 1739.28, "duration": 3.54}, {"text": "a little bit of discussion\nof the new technologies that", "start": 1742.82, "duration": 4.29}, {"text": "might make this less expensive,\nand a discussion of how we got", "start": 1747.11, "duration": 3.36}, {"text": "the first genome and how\nthe new technologies might", "start": 1750.47, "duration": 2.43}, {"text": "be a little different.", "start": 1752.9, "duration": 1.68}, {"text": "But we're going to do this\nin the context of computation", "start": 1754.58, "duration": 2.49}, {"text": "in the sense of, how do we\ndeal with random and systematic", "start": 1757.07, "duration": 2.74}, {"text": "errors?", "start": 1759.81, "duration": 0.5}, {"text": "As we plan our\nstrategy for getting", "start": 1760.31, "duration": 3.06}, {"text": "each of our genomes, personal\ngenomes sequence for $1,000", "start": 1763.37, "duration": 3.27}, {"text": "or so, how do we choose\nwhich technology to pursue?", "start": 1766.64, "duration": 4.21}, {"text": "Which ones have the\nlowest intrinsic, random,", "start": 1770.85, "duration": 3.2}, {"text": "and systematic errors?", "start": 1774.05, "duration": 1.3}, {"text": "So we needed to study\nthe first genome", "start": 1775.35, "duration": 1.76}, {"text": "to see, what would we mean by\nrandom and systematic errors?", "start": 1777.11, "duration": 4.08}, {"text": "How many people here know what\nthe difference is already?", "start": 1781.19, "duration": 3.6}, {"text": "A few.", "start": 1787.37, "duration": 0.52}, {"text": "OK.", "start": 1787.89, "duration": 0.5}, {"text": "But anyway, whether you do or\nnot, it's good for the soul", "start": 1788.39, "duration": 3.33}, {"text": "to go through some\nreal examples of this.", "start": 1791.72, "duration": 2.7}, {"text": "A random mutation\nis something which", "start": 1794.42, "duration": 1.74}, {"text": "occurs every time you\ndo the experiment.", "start": 1796.16, "duration": 2.88}, {"text": "You get a different error.", "start": 1799.04, "duration": 2.64}, {"text": "And a systematic\none is something", "start": 1801.68, "duration": 4.56}, {"text": "where if you do it over\nand over the same way,", "start": 1806.24, "duration": 2.32}, {"text": "you'll get the same\nerror or a simple class", "start": 1808.56, "duration": 2.36}, {"text": "of errors occurring more\nthan once, over and over.", "start": 1810.92, "duration": 4.59}, {"text": "So for sequencing, the process\ninvolves picking something", "start": 1815.51, "duration": 4.535}, {"text": "that you want to\nsequence-- we'll", "start": 1820.045, "duration": 1.375}, {"text": "call it a clone or a template.", "start": 1821.42, "duration": 1.53}, {"text": "Then actually doing\nthe sequencing", "start": 1822.95, "duration": 1.86}, {"text": "and then assembling\nthis into a meaningful", "start": 1824.81, "duration": 3.09}, {"text": "interpreted sequence.", "start": 1827.9, "duration": 1.79}, {"text": "And this is an\nexample where we might", "start": 1829.69, "duration": 4.81}, {"text": "have chosen these big clones.", "start": 1834.5, "duration": 6.87}, {"text": "In other words, you might\nfragment the genome up randomly", "start": 1841.37, "duration": 2.55}, {"text": "into large clones of\n100 kilobases called", "start": 1843.92, "duration": 2.22}, {"text": "bacterial artificial\nchromosomes, for example.", "start": 1846.14, "duration": 2.55}, {"text": "And then that's all\nrandom, and so there's", "start": 1848.69, "duration": 2.46}, {"text": "a shotgun of that scale.", "start": 1851.15, "duration": 1.77}, {"text": "And then we break it up\nrandomly into smaller pieces,", "start": 1852.92, "duration": 2.92}, {"text": "which provide us with\nlittle sequences.", "start": 1855.84, "duration": 1.64}, {"text": "And then in the computer,\nwe assemble these by methods", "start": 1857.48, "duration": 2.46}, {"text": "that we'll discuss in\nthe next lecture, which", "start": 1859.94, "duration": 4.47}, {"text": "can take even fairly different\nsequences than assemble them.", "start": 1864.41, "duration": 3.19}, {"text": "In this case, we're talking\nabout very similar sequences.", "start": 1867.6, "duration": 3.44}, {"text": "And then you assemble the little\nsequences into big sequences,", "start": 1871.04, "duration": 2.783}, {"text": "and you assemble\nthe big sequences", "start": 1873.823, "duration": 1.417}, {"text": "into even bigger sequences, and\nthen you have the whole thing.", "start": 1875.24, "duration": 2.67}, {"text": "But you can see there's a lot\nof opportunity for error here.", "start": 1877.91, "duration": 3.468}, {"text": "We make it look\nsimple in this slide,", "start": 1881.378, "duration": 1.542}, {"text": "but we're going to talk about\nrandom and systematic errors", "start": 1882.92, "duration": 3.06}, {"text": "in a moment.", "start": 1885.98, "duration": 2.04}, {"text": "Where did we get\nthose sequences,", "start": 1888.02, "duration": 1.59}, {"text": "those little sequences\nthat we want to assemble?", "start": 1889.61, "duration": 2.73}, {"text": "We're going to go through\na few methods in a moment,", "start": 1892.34, "duration": 2.26}, {"text": "but the most common\none by far I think", "start": 1894.6, "duration": 2.54}, {"text": "that generates over\n90% of the human genome", "start": 1897.14, "duration": 3.24}, {"text": "sequence in the\nlast couple of years", "start": 1900.38, "duration": 2.04}, {"text": "is capillary electrophoresis\nof fluorescently labeled", "start": 1902.42, "duration": 4.71}, {"text": "polymerase terminated products.", "start": 1907.13, "duration": 2.19}, {"text": "When you electrophoresis\nthings, you're", "start": 1909.32, "duration": 2.07}, {"text": "separating DNA fragments,\nwhich are n nucleotides long,", "start": 1911.39, "duration": 5.985}, {"text": "from a DNA fragment which is\nn plus one nucleotides long.", "start": 1917.375, "duration": 3.255}, {"text": "That's a very subtle\ndifference as n gets big.", "start": 1920.63, "duration": 2.4}, {"text": "As n gets big, it\ngets harder and harder", "start": 1923.03, "duration": 2.25}, {"text": "to separate n from n plus one.", "start": 1925.28, "duration": 2.115}, {"text": "As it does so, you start\ngetting all kinds of errors.", "start": 1927.395, "duration": 2.925}, {"text": "The total number of errors here\nin the lower left-hand corner", "start": 1930.32, "duration": 3.99}, {"text": "is the number of insertions\nplus the number of deletions", "start": 1934.31, "duration": 2.43}, {"text": "plus the number of\nsubstitutions plus n, which", "start": 1936.74, "duration": 3.57}, {"text": "is an abbreviation for no call.", "start": 1940.31, "duration": 3.33}, {"text": "It means the software felt\nthat it was so close that it", "start": 1943.64, "duration": 3.36}, {"text": "couldn't call it at all.", "start": 1947.0, "duration": 1.0}, {"text": "It just said it's n.", "start": 1948.0, "duration": 0.83}, {"text": "I don't know whether\nit's an A, C-- it", "start": 1948.83, "duration": 1.583}, {"text": "doesn't know whether it's an A,\nC, G, or T. Calls it a no call.", "start": 1950.413, "duration": 3.977}, {"text": "And so if you look\nthrough this table,", "start": 1954.39, "duration": 2.27}, {"text": "it shows on the vertical axis\nfor each of these six bar", "start": 1956.66, "duration": 7.02}, {"text": "charts is as you go up\non the vertical axis,", "start": 1963.68, "duration": 4.14}, {"text": "you go from very\nshort reads where", "start": 1967.82, "duration": 2.43}, {"text": "it's easy to separate n from\nn plus one electrophoretically", "start": 1970.25, "duration": 2.7}, {"text": "to very long ones where\nyou start accumulating", "start": 1972.95, "duration": 2.55}, {"text": "insertions deletion\nerrors, insertion deletion", "start": 1975.5, "duration": 3.18}, {"text": "substitution, and n.", "start": 1978.68, "duration": 1.56}, {"text": "They all go up with length.", "start": 1980.24, "duration": 1.93}, {"text": "And so you can think of that\nas a random error superimposed", "start": 1982.17, "duration": 4.22}, {"text": "on the systematic error of if\nyou always do the experiments,", "start": 1986.39, "duration": 3.99}, {"text": "the same base pair is always\nat the end of your run,", "start": 1990.38, "duration": 3.24}, {"text": "it's going to always have\na higher random error rate.", "start": 1993.62, "duration": 2.64}, {"text": "So this is kind of a combination\nof random and systematic error.", "start": 1996.26, "duration": 3.04}, {"text": "So let's go through\nsome examples here.", "start": 1999.3, "duration": 3.38}, {"text": "We have just\nisolating the template", "start": 2002.68, "duration": 3.09}, {"text": "to prepare it for sequencing,\nthere are systematic errors.", "start": 2005.77, "duration": 5.58}, {"text": "If you have certain\nkinds of repeats,", "start": 2011.35, "duration": 1.92}, {"text": "long, inverted repeats, or\ncertain kinds of restriction", "start": 2013.27, "duration": 3.09}, {"text": "elements that the bacteria\ndoesn't like or likes", "start": 2016.36, "duration": 2.79}, {"text": "to chew up, then you\nwon't get the clone.", "start": 2019.15, "duration": 3.81}, {"text": "And that would plague the early\npart of the Genome Project,", "start": 2022.96, "duration": 2.55}, {"text": "is you'd keep trying again\nand again the same way,", "start": 2025.51, "duration": 2.612}, {"text": "and you just wouldn't\nget certain clones.", "start": 2028.122, "duration": 1.708}, {"text": "It's as if there\nwas a hole there.", "start": 2029.83, "duration": 1.53}, {"text": "You know that there's\nsomething there,", "start": 2031.36, "duration": 1.583}, {"text": "but you couldn't clone it.", "start": 2032.943, "duration": 2.077}, {"text": "Sequencing-- hairpins can\nform in the single strand", "start": 2035.02, "duration": 3.54}, {"text": "of nucleic acids\nwhere you're trying", "start": 2038.56, "duration": 1.5}, {"text": "to separate n from n plus one.", "start": 2040.06, "duration": 2.04}, {"text": "And those hairpins then take\nout the gel electrophoresis", "start": 2042.1, "duration": 4.89}, {"text": "and make it seem like it's much\nsmaller than it actually is.", "start": 2046.99, "duration": 3.81}, {"text": "Tandem repeats cause\na problem in all three", "start": 2050.8, "duration": 2.76}, {"text": "of these stages in sequencing.", "start": 2053.56, "duration": 3.42}, {"text": "You get some\npolymerase stuttering", "start": 2056.98, "duration": 2.55}, {"text": "and you get little artifacts.", "start": 2059.53, "duration": 2.189}, {"text": "In assembly repeats,\nyou're assembling", "start": 2061.719, "duration": 3.091}, {"text": "by sequence alignment.", "start": 2064.81, "duration": 2.5}, {"text": "If you have a\nrepeat, the repeat's", "start": 2067.31, "duration": 1.46}, {"text": "going to align just\nas well because it's", "start": 2068.77, "duration": 2.34}, {"text": "a repeat within the\ngenome as a repeat", "start": 2071.11, "duration": 2.105}, {"text": "due to experimental repeating,\nand so the alignment", "start": 2073.215, "duration": 2.125}, {"text": "can be off.", "start": 2075.34, "duration": 1.56}, {"text": "The errors that you got\nfrom these earlier steps", "start": 2076.9, "duration": 2.25}, {"text": "make it hard to assemble.", "start": 2079.15, "duration": 1.71}, {"text": "Polymorphisms look like errors.", "start": 2080.86, "duration": 1.71}, {"text": "Chimeric clones means\nyou've got things", "start": 2082.57, "duration": 2.01}, {"text": "that have been misassembled\nearly on here, and so on.", "start": 2084.58, "duration": 7.43}, {"text": "OK.", "start": 2092.01, "duration": 2.66}, {"text": "When we do this random\nselection of big clones", "start": 2094.67, "duration": 5.232}, {"text": "and random selection of\nlittle clones for sequencing,", "start": 2099.902, "duration": 2.208}, {"text": "we want to know when to quit.", "start": 2102.11, "duration": 1.95}, {"text": "Now you could say,\nwell, we're going", "start": 2104.06, "duration": 1.83}, {"text": "to quit once we get\nit all assembled,", "start": 2105.89, "duration": 1.56}, {"text": "but you need to accumulate\na certain amount of data", "start": 2107.45, "duration": 2.67}, {"text": "in advance before you\ntry to assemble it.", "start": 2110.12, "duration": 1.95}, {"text": "And so there are\nvarious calculations", "start": 2112.07, "duration": 3.75}, {"text": "as to when to quit.", "start": 2115.82, "duration": 1.29}, {"text": "And this is related to\nthe Poisson distribution,", "start": 2117.11, "duration": 2.47}, {"text": "but it's not exactly.", "start": 2119.58, "duration": 1.07}, {"text": "And in fact, one of the\nstudies done in 1988", "start": 2120.65, "duration": 4.11}, {"text": "made some poor\nassumptions about--", "start": 2124.76, "duration": 4.23}, {"text": "remember, we mentioned\nin the first lecture", "start": 2128.99, "duration": 3.33}, {"text": "the assumptions of the\nPoisson distribution", "start": 2132.32, "duration": 3.99}, {"text": "that make it an\napproximation-- when", "start": 2136.31, "duration": 1.86}, {"text": "it becomes an approximation\nto a more formal distribution", "start": 2138.17, "duration": 4.14}, {"text": "like the binomial.", "start": 2142.31, "duration": 0.87}, {"text": "Anyway, that approximation,\nyou should be getting,", "start": 2143.18, "duration": 3.24}, {"text": "as you get higher\nand higher coverage,", "start": 2146.42, "duration": 1.71}, {"text": "meaning more and more\nexperimental repeats,", "start": 2148.13, "duration": 4.11}, {"text": "you'll eventually\nfill all the gaps.", "start": 2152.24, "duration": 2.22}, {"text": "And that means you'll get\n100% complete coverage,", "start": 2154.46, "duration": 4.17}, {"text": "and it should asymptotically\napproach that.", "start": 2158.63, "duration": 2.28}, {"text": "Well, if you use the\nPoisson incorrectly,", "start": 2160.91, "duration": 2.94}, {"text": "as authors did in 1988, you\nbasically go off to infinity.", "start": 2163.85, "duration": 4.23}, {"text": "You get 200% coverage, which\nis physically impossible.", "start": 2168.08, "duration": 4.72}, {"text": "But both an earlier\nstudy, which they ignored,", "start": 2172.8, "duration": 2.6}, {"text": "and a more recent\nstudy got it right.", "start": 2175.4, "duration": 2.43}, {"text": "And these are slightly\ndifferent measures,", "start": 2177.83, "duration": 3.18}, {"text": "but they both converge on 100%.", "start": 2181.01, "duration": 3.24}, {"text": "And I urge you to\nlook at that if you're", "start": 2184.25, "duration": 1.98}, {"text": "designing an experiment\nwith simple formula.", "start": 2186.23, "duration": 3.33}, {"text": "On the other hand, if you want\nto design the experiment more", "start": 2189.56, "duration": 2.97}, {"text": "explicit, you eventually\nget to a point", "start": 2192.53, "duration": 2.55}, {"text": "where a simple analytic\nformula won't do,", "start": 2195.08, "duration": 2.73}, {"text": "and you have to do Monte Carlo.", "start": 2197.81, "duration": 1.35}, {"text": "We treated this\nin the first class", "start": 2199.16, "duration": 2.13}, {"text": "of analytic versus numeric\ndifferentiable equations", "start": 2201.29, "duration": 3.54}, {"text": "and then many other cases.", "start": 2204.83, "duration": 1.51}, {"text": "The simulation you\nwant to do is beyond--", "start": 2206.34, "duration": 3.04}, {"text": "is too hard to do analytically.", "start": 2209.38, "duration": 2.9}, {"text": "So Gene Myers set up-- just\nlisted all the things he", "start": 2212.28, "duration": 3.74}, {"text": "thought would be--", "start": 2216.02, "duration": 1.77}, {"text": "could affect the ability to\nassemble a genome sequence.", "start": 2217.79, "duration": 4.68}, {"text": "The read length and types of\nrepeats, and all this stuff", "start": 2222.47, "duration": 5.52}, {"text": "was simulated.", "start": 2227.99, "duration": 1.17}, {"text": "And he cranked the simulation on\nreal human genome size projects", "start": 2229.16, "duration": 4.35}, {"text": "and came to the conclusion\nthat you could do a shotgun", "start": 2233.51, "duration": 2.7}, {"text": "assembly of a mammalian genome.", "start": 2236.21, "duration": 2.25}, {"text": "A company called\nCelera was formed.", "start": 2238.46, "duration": 1.86}, {"text": "Gene Myers was hired\nas the computer guru.", "start": 2240.32, "duration": 4.2}, {"text": "They put together a\nlarge stable of computers", "start": 2244.52, "duration": 2.73}, {"text": "and they started doing this on\nthe human and the mouse genome.", "start": 2247.25, "duration": 3.81}, {"text": "The human genome was in the\nend not done by this method,", "start": 2251.06, "duration": 2.58}, {"text": "but the mouse genome was, and\nit was a pretty good assembly.", "start": 2253.64, "duration": 2.91}, {"text": "So the Drosophila genome\nmissing the Drosophila repeats", "start": 2256.55, "duration": 3.12}, {"text": "was also done by this method.", "start": 2259.67, "duration": 1.69}, {"text": "So this is scaled\nvery gracefully", "start": 2261.36, "duration": 2.51}, {"text": "from the first shotgun sequence,\nwhich was on a four kV plasmid", "start": 2263.87, "duration": 5.61}, {"text": "to mammalian size genomes.", "start": 2269.48, "duration": 3.03}, {"text": "No mammalian genome is\ncompletely sequenced,", "start": 2272.51, "duration": 2.16}, {"text": "so we can't really\ndeclare victory.", "start": 2274.67, "duration": 1.77}, {"text": "But the sort of simulation\nthat he did here", "start": 2276.44, "duration": 3.51}, {"text": "has played out very nicely.", "start": 2279.95, "duration": 1.155}, {"text": "Right here in Boston,\nthere will be--", "start": 2283.76, "duration": 2.22}, {"text": "when we start\nthinking of the future", "start": 2285.98, "duration": 1.5}, {"text": "of sequencing\ntechnology, we would all", "start": 2287.48, "duration": 1.68}, {"text": "like-- this is almost\nuncontroversial as", "start": 2289.16, "duration": 2.88}, {"text": "to how much we desire that the\ngenome not cost $3 billion,", "start": 2292.04, "duration": 4.05}, {"text": "but it costs $1,000.", "start": 2296.09, "duration": 1.83}, {"text": "And now there are\na number of people", "start": 2297.92, "duration": 2.19}, {"text": "who are taking very definite\nsteps to get us to that point.", "start": 2300.11, "duration": 6.87}, {"text": "To understand systematic\nand random errors that", "start": 2306.98, "duration": 3.06}, {"text": "can occur in these\nsteps, let's take", "start": 2310.04, "duration": 2.04}, {"text": "this dideoxy gel electrophoresis\nwe've been talking about here.", "start": 2312.08, "duration": 3.48}, {"text": "You have four different\ncolored terminators.", "start": 2315.56, "duration": 2.1}, {"text": "These is where the polymerase\ncan't go any further", "start": 2317.66, "duration": 3.09}, {"text": "because there's a\nblocking group here,", "start": 2320.75, "duration": 2.782}, {"text": "which is fluorescent labeled.", "start": 2323.532, "duration": 1.208}, {"text": "And if the template\non the far left", "start": 2324.74, "duration": 1.98}, {"text": "here is ready to accept\nan A, you'll get an A.", "start": 2326.72, "duration": 3.6}, {"text": "And this n and n minus\none will separate", "start": 2330.32, "duration": 3.75}, {"text": "on this electrophoresis and\nthe four colors will give you", "start": 2334.07, "duration": 2.97}, {"text": "this four-colored pattern\nwhere the intensity reflects", "start": 2337.04, "duration": 3.66}, {"text": "good termination\nat that position,", "start": 2340.7, "duration": 2.97}, {"text": "and you can basically\ngo along reading it.", "start": 2343.67, "duration": 2.16}, {"text": "G, C, G, G, A, T.", "start": 2345.83, "duration": 2.16}, {"text": "Now this is in the\nwell-behaved part.", "start": 2347.99, "duration": 1.77}, {"text": "An example of a systematic error\nthat you get in this extension", "start": 2349.76, "duration": 3.75}, {"text": "occurs here in the upper\nright-hand corner of slide 40.", "start": 2353.51, "duration": 3.81}, {"text": "Now you've got-- because\nof one of these hairpins", "start": 2357.32, "duration": 2.19}, {"text": "that I mentioned\nbefore, you've got", "start": 2359.51, "duration": 1.458}, {"text": "a pile-up of seven nucleotides\nall at the same position.", "start": 2360.968, "duration": 3.732}, {"text": "A completely\nalternative method that", "start": 2364.7, "duration": 1.542}, {"text": "doesn't involve\ngel electrophoresis", "start": 2366.242, "duration": 1.458}, {"text": "is called pirA\nsequencing, and this", "start": 2367.7, "duration": 2.22}, {"text": "is an equivalent that can be\ndone with fluorescent addition.", "start": 2369.92, "duration": 4.56}, {"text": "Instead of separating\nthem in time", "start": 2374.48, "duration": 2.28}, {"text": "by their size in\nelectrophoresis,", "start": 2376.76, "duration": 2.79}, {"text": "in time you ask serially,\ndo you want an A here?", "start": 2379.55, "duration": 3.57}, {"text": "If yes, then you\nget a little green--", "start": 2383.12, "duration": 2.28}, {"text": "you get a little\npeek of representing", "start": 2385.4, "duration": 3.67}, {"text": "the release of pyrophosphate\nor the incorporation", "start": 2389.07, "duration": 2.67}, {"text": "of fluorescent A.", "start": 2391.74, "duration": 1.315}, {"text": "And then you ask,\ndo you want a T,", "start": 2393.055, "duration": 2.075}, {"text": "and so forth, and you go along.", "start": 2395.13, "duration": 1.32}, {"text": "And each signal means\nyes to the answer", "start": 2396.45, "duration": 3.78}, {"text": "that it's ready for\nthat particular base.", "start": 2400.23, "duration": 2.32}, {"text": "And you can see this\ndoesn't have any problems", "start": 2402.55, "duration": 1.94}, {"text": "with this hairpin region.", "start": 2404.49, "duration": 1.56}, {"text": "So when you have a\nsystematic error,", "start": 2408.69, "duration": 1.5}, {"text": "you have to change\nthe method that you're", "start": 2410.19, "duration": 1.708}, {"text": "using fairly radically.", "start": 2411.898, "duration": 1.772}, {"text": "The opposite strand or a\ncompletely different method.", "start": 2413.67, "duration": 3.765}, {"text": "If you have-- early on,\nwe had huge differences", "start": 2420.23, "duration": 4.05}, {"text": "in intensity of the\nfluorophores and new enzymes", "start": 2424.28, "duration": 3.48}, {"text": "and new fluorophores were\ndeveloped by Tabor and Matthews", "start": 2427.76, "duration": 3.39}, {"text": "and Glaser, and so forth.", "start": 2431.15, "duration": 1.3}, {"text": "And this was a huge advance\nin making everything uniform", "start": 2432.45, "duration": 4.13}, {"text": "and eliminating\nsystematic errors.", "start": 2436.58, "duration": 2.74}, {"text": "So the sort of things that are\non the horizon that hopefully", "start": 2439.32, "duration": 2.63}, {"text": "will be discussed\ntomorrow in Boston,", "start": 2441.95, "duration": 3.09}, {"text": "we've talked about this short\nnumber of base extensions", "start": 2445.04, "duration": 6.06}, {"text": "like power\nsequencing, the longer", "start": 2451.1, "duration": 1.98}, {"text": "extensions in capillary\narrays, which, capillary arrays", "start": 2453.08, "duration": 3.9}, {"text": "are changing from\nlow-end capillaries", "start": 2456.98, "duration": 1.71}, {"text": "into microfabricated chips.", "start": 2458.69, "duration": 3.09}, {"text": "I'll show an example of a\nmass spec in just a moment.", "start": 2461.78, "duration": 2.235}, {"text": "Sequencing by\nhybridization on arrays", "start": 2467.15, "duration": 1.83}, {"text": "will illustrate as a prelude,\nas an example of Affymetrix", "start": 2468.98, "duration": 4.05}, {"text": "technology in this slide.", "start": 2473.03, "duration": 4.83}, {"text": "OK.", "start": 2477.86, "duration": 0.51}, {"text": "So the idea here, this is\nmainly for re-sequencing.", "start": 2478.37, "duration": 4.38}, {"text": "Some of the ways of reducing\nthe cost of sequencing", "start": 2482.75, "duration": 3.03}, {"text": "the human genome will not\napply to sequencing brand", "start": 2485.78, "duration": 2.7}, {"text": "new genomes.", "start": 2488.48, "duration": 0.78}, {"text": "But still, we need\nto pursue them,", "start": 2489.26, "duration": 1.71}, {"text": "because this may be the way that\nwe get the $1,000 human genome,", "start": 2490.97, "duration": 2.91}, {"text": "even if we don't get other ones.", "start": 2493.88, "duration": 2.38}, {"text": "And here, you know the\nsequence, except there's", "start": 2496.26, "duration": 3.47}, {"text": "a possibility that there could\nbe a polymorphism at any base.", "start": 2499.73, "duration": 2.81}, {"text": "Could be any single base\nsubstitution at any base.", "start": 2502.54, "duration": 3.1}, {"text": "And so you don't\nnecessarily know", "start": 2505.64, "duration": 1.695}, {"text": "in advance what the common\nones are or the rare ones,", "start": 2507.335, "duration": 2.355}, {"text": "but you do know the\ncanonical sequence.", "start": 2509.69, "duration": 2.73}, {"text": "And so at every position, you'll\nmake a 25-mer oligonucleotide", "start": 2512.42, "duration": 6.33}, {"text": "which will bind to a\nfluorescently labeled", "start": 2518.75, "duration": 1.77}, {"text": "version of your genome,\nor a piece of your genome.", "start": 2520.52, "duration": 3.39}, {"text": "And this is actually developed\nfor HIV re-sequencing", "start": 2523.91, "duration": 2.85}, {"text": "by Affymetrix.", "start": 2526.76, "duration": 1.41}, {"text": "And at this middle\nposition, you'll", "start": 2528.17, "duration": 3.45}, {"text": "put in all four possible\nsubstitutions, T, G, C, or A.", "start": 2531.62, "duration": 7.165}, {"text": "And you'll consider\neach possible template.", "start": 2538.785, "duration": 6.085}, {"text": "So if you have the\ntemplate, which is-- let's", "start": 2544.87, "duration": 1.88}, {"text": "say these are the\ntwo alleles that", "start": 2546.75, "duration": 1.417}, {"text": "occur in a human population\nor in your sample.", "start": 2548.167, "duration": 3.653}, {"text": "You can have this sequence and\nthen all the variations on it,", "start": 2551.82, "duration": 3.36}, {"text": "stepping along, changing T,\nG, C, A for the first base,", "start": 2555.18, "duration": 4.273}, {"text": "the second base, the\nthird base, and so forth,", "start": 2559.453, "duration": 1.917}, {"text": "till you hit this one.", "start": 2561.37, "duration": 0.917}, {"text": "And this is where the\nreal polymorphism occurs.", "start": 2562.287, "duration": 2.253}, {"text": "And you could have either\nthis as the context", "start": 2564.54, "duration": 2.49}, {"text": "or this as the context.", "start": 2567.03, "duration": 2.28}, {"text": "And this is schematic And\nthis is the real data.", "start": 2569.31, "duration": 3.0}, {"text": "These are real data\ndown here where", "start": 2572.31, "duration": 1.86}, {"text": "you have the context of\nthe A allele or the context", "start": 2574.17, "duration": 2.97}, {"text": "of the C allele.", "start": 2577.14, "duration": 1.05}, {"text": "You can have the homozygotes\nor the heterozygotes.", "start": 2578.19, "duration": 3.45}, {"text": "And in the homozygous A,\nyou can see it lights up", "start": 2581.64, "duration": 3.063}, {"text": "the best, the best\nhybridization when you have", "start": 2584.703, "duration": 1.917}, {"text": "the A in the middle position.", "start": 2586.62, "duration": 1.208}, {"text": "The middle position\nis most sensitive", "start": 2587.828, "duration": 1.552}, {"text": "to hybridization changes.", "start": 2589.38, "duration": 1.87}, {"text": "And for the C, you have\nit in the C row here.", "start": 2591.25, "duration": 5.03}, {"text": "And remember, you're\nchanging all the bases", "start": 2596.28, "duration": 2.13}, {"text": "in every position.", "start": 2598.41, "duration": 0.75}, {"text": "One, two, three, four.", "start": 2599.16, "duration": 0.917}, {"text": "This is the one where the middle\nbase of the middle position", "start": 2600.077, "duration": 3.073}, {"text": "is in the right context.", "start": 2603.15, "duration": 1.63}, {"text": "So this is in the A\ncontext and the C context.", "start": 2604.78, "duration": 2.33}, {"text": "And in the heterozygote, you\nget both the A and the C.", "start": 2607.11, "duration": 3.36}, {"text": "And so this has\nbeen done on HIV.", "start": 2610.47, "duration": 2.25}, {"text": "It's been done on\nBRCA1, on mitochondria.", "start": 2612.72, "duration": 2.01}, {"text": "And now they've applied\nit with whole wafers", "start": 2614.73, "duration": 2.91}, {"text": "to the entire human genome.", "start": 2617.64, "duration": 1.99}, {"text": "And this probably costs on\nthe order of $3 million or so.", "start": 2619.63, "duration": 5.0}, {"text": "Mass spectrometry is\nanother way that's", "start": 2624.63, "duration": 1.77}, {"text": "used, probably not for\nsequencing the whole genome,", "start": 2626.4, "duration": 2.125}, {"text": "but it's used for single\nnucleotide polymorphisms.", "start": 2628.525, "duration": 3.065}, {"text": "This costs on the order\nof $0.50 per polymorphism.", "start": 2631.59, "duration": 5.07}, {"text": "If there's three million\nof them in your genome,", "start": 2636.66, "duration": 3.99}, {"text": "that's a lot of $0.50.", "start": 2640.65, "duration": 3.093}, {"text": "[LAUGHTER]", "start": 2643.743, "duration": 3.387}, {"text": "And here's what it looks\nlike when you read it out.", "start": 2647.13, "duration": 2.55}, {"text": "It's really just\nlike electrophoresis.", "start": 2649.68, "duration": 2.01}, {"text": "You can now separate\nan addition of an A", "start": 2651.69, "duration": 5.43}, {"text": "from an addition of a G. And the\ndifference in mass between an A", "start": 2657.12, "duration": 5.415}, {"text": "and a G, this is\neven more subtle", "start": 2662.535, "duration": 1.395}, {"text": "than the difference of\nan n and an n plus one.", "start": 2663.93, "duration": 1.917}, {"text": "This is just a difference\nbetween an A and a C.", "start": 2665.847, "duration": 1.958}, {"text": "It's detectable in this.", "start": 2667.805, "duration": 1.105}, {"text": "In fact, it's detectable\nand quantitative enough", "start": 2668.91, "duration": 2.67}, {"text": "that you can pool samples.", "start": 2671.58, "duration": 1.332}, {"text": "This is a bit of a stunt,\nbut it's an important stunt", "start": 2672.912, "duration": 2.208}, {"text": "to show that this is really\na very precise method, albeit", "start": 2675.12, "duration": 4.98}, {"text": "still fairly expensive.", "start": 2680.1, "duration": 2.43}, {"text": "Now just in closing,\nI want to give you", "start": 2682.53, "duration": 2.79}, {"text": "the simplest possible\nexample of how we", "start": 2685.32, "duration": 4.26}, {"text": "can search through sequences.", "start": 2689.58, "duration": 1.44}, {"text": "Next week, we'll give you\na much more rigorous way", "start": 2691.02, "duration": 2.083}, {"text": "that you can look\nthrough the sequences", "start": 2693.103, "duration": 1.625}, {"text": "with very extensive differences\nbetween the sequences.", "start": 2694.728, "duration": 2.362}, {"text": "But here, the theme\nof today's talk", "start": 2697.09, "duration": 3.02}, {"text": "is the subtle\npolymorphism differences", "start": 2700.11, "duration": 2.73}, {"text": "that occur between you and me.", "start": 2702.84, "duration": 1.53}, {"text": "And here, one different--\nso generally, you're", "start": 2704.37, "duration": 2.79}, {"text": "looking for exact matches.", "start": 2707.16, "duration": 1.32}, {"text": "And a good way to look\nfor exact matches is--", "start": 2708.48, "duration": 2.97}, {"text": "good ways are hashing, suffix\narrays, and suffix trees", "start": 2711.45, "duration": 3.12}, {"text": "where basically\nin each of these,", "start": 2714.57, "duration": 1.93}, {"text": "you're looking for using\na word, a word either", "start": 2716.5, "duration": 4.61}, {"text": "that's built up and stored\nfrom the end, the suffix,", "start": 2721.11, "duration": 3.72}, {"text": "one letter at a\ntime, or it's a chunk", "start": 2724.83, "duration": 2.7}, {"text": "that you might have as a hash.", "start": 2727.53, "duration": 1.62}, {"text": "And you make up a lookup table.", "start": 2729.15, "duration": 2.142}, {"text": "And the size of\nthat lookup table--", "start": 2731.292, "duration": 1.458}, {"text": "it's a trade-off between\nspeed of searching", "start": 2732.75, "duration": 1.792}, {"text": "and the size of the table.", "start": 2734.542, "duration": 1.268}, {"text": "The size is going to be-- if\nthe word is n nucleotides long,", "start": 2735.81, "duration": 3.568}, {"text": "it's going to be four to the n.", "start": 2739.378, "duration": 1.292}, {"text": "It's going to be the\nstorage space you", "start": 2740.67, "duration": 1.583}, {"text": "have to put on disk\nor RAM, RAM if you", "start": 2742.253, "duration": 3.307}, {"text": "want it to be a fast search.", "start": 2745.56, "duration": 1.35}, {"text": "And so 16 is the magic number,\nsort of in the ballpark", "start": 2746.91, "duration": 3.48}, {"text": "for a human genome,\nbecause four to the 16th", "start": 2750.39, "duration": 2.1}, {"text": "is four billion sequences\nyou can represent.", "start": 2752.49, "duration": 2.91}, {"text": "But it's a huge table.", "start": 2755.4, "duration": 1.27}, {"text": "You have to have a table of\nfour billion times however", "start": 2756.67, "duration": 2.66}, {"text": "many bytes you need to\nstore the positions.", "start": 2759.33, "duration": 4.8}, {"text": "Typically, about four\nbytes of storage.", "start": 2764.13, "duration": 2.34}, {"text": "If you cut back on\nthis a little bit,", "start": 2766.47, "duration": 1.59}, {"text": "you'll end up with\ncollisions where", "start": 2768.06, "duration": 1.458}, {"text": "you'll have two things that\nhave the same hash or suffix.", "start": 2769.518, "duration": 3.792}, {"text": "If you make it--", "start": 2773.31, "duration": 1.62}, {"text": "and that's if you\nmake it smaller.", "start": 2774.93, "duration": 1.423}, {"text": "It'll take less space.", "start": 2776.353, "duration": 0.917}, {"text": "If you make it\nbigger, it'll take", "start": 2777.27, "duration": 1.41}, {"text": "a ridiculous amount of RAM.", "start": 2778.68, "duration": 2.34}, {"text": "And then here's a\nkind of whimsical--", "start": 2781.02, "duration": 4.05}, {"text": "another example of pearl\nwhere you not only want", "start": 2785.07, "duration": 2.43}, {"text": "to find all the mutations\nhere at a very high density--", "start": 2787.5, "duration": 2.61}, {"text": "a ridiculously high density,\nnot one particular base", "start": 2790.11, "duration": 2.97}, {"text": "for every few base pairs.", "start": 2793.08, "duration": 1.538}, {"text": "You not only want to find them,\nbut you want to correct them.", "start": 2794.618, "duration": 2.542}, {"text": "And here, the pearl\ndoes the substitution.", "start": 2797.16, "duration": 2.97}, {"text": "And after gene therapy,\neverybody walks out happy.", "start": 2800.13, "duration": 3.635}, {"text": "OK.", "start": 2803.765, "duration": 0.5}, {"text": "[LAUGHTER]", "start": 2804.265, "duration": 2.095}]

transcripts/3IxWLibV_tU.json

@@ -0,0 +1 @@
+[{"text": "YUFEI ZHAO: We've been\nspending the past few lectures", "start": 16.602, "duration": 2.208}, {"text": "discussing Szemeredi's\nRegularity Lemma.", "start": 18.81, "duration": 2.94}, {"text": "And one of the\nfirst applications", "start": 21.75, "duration": 2.31}, {"text": "that we discussed of\nthe Regularity Lemma", "start": 24.06, "duration": 2.67}, {"text": "is the triangle removal Lemma.", "start": 26.73, "duration": 2.85}, {"text": "So today, I want to\nrevisit this topic", "start": 29.58, "duration": 2.16}, {"text": "and show you a strengthening\nof the Removal Lemma", "start": 31.74, "duration": 3.12}, {"text": "for which new regularity\ntechniques are needed.", "start": 34.86, "duration": 3.0}, {"text": "But first, recall the\ngraph removal Lemma.", "start": 42.03, "duration": 3.06}, {"text": "In the graph removal Lemma,\nwe have that for every graph H", "start": 57.69, "duration": 5.9}, {"text": "and epsilon bigger than zero,\nthere exists some delta such", "start": 63.59, "duration": 6.45}, {"text": "that if an N vertex graph\nhas fewer than delta", "start": 70.04, "duration": 14.69}, {"text": "and to the number of vertices\nof H, many copies of H,", "start": 84.73, "duration": 10.54}, {"text": "then it can be made H-free by\nremoving fewer than epsilon N", "start": 95.27, "duration": 18.35}, {"text": "squared edges.", "start": 113.62, "duration": 0.9}, {"text": "Even in the case when\nH is a triangle, when", "start": 118.23, "duration": 2.835}, {"text": "this is called a triangle\nremoval Lemma, even", "start": 121.065, "duration": 1.875}, {"text": "in that case, basically\nthe regularity method", "start": 122.94, "duration": 3.39}, {"text": "is more or less the only\nway that we currently", "start": 126.33, "duration": 1.95}, {"text": "know how to prove this theorem.", "start": 128.28, "duration": 2.1}, {"text": "So we saw this a\nfew lectures ago.", "start": 130.38, "duration": 3.93}, {"text": "What I would like\nto discuss today", "start": 134.31, "duration": 2.01}, {"text": "is a variant of\nthis result where", "start": 136.32, "duration": 3.33}, {"text": "instead of considering\ncopies of H,", "start": 139.65, "duration": 4.38}, {"text": "we're now considering\ninduced copies of H. OK?", "start": 144.03, "duration": 5.43}, {"text": "So this is the induced\ngraph removal Lemma", "start": 149.46, "duration": 5.55}, {"text": "where the only difference is\nthat the hypothesis is now", "start": 155.01, "duration": 4.77}, {"text": "going to be changed to\ninduced copies of H.", "start": 159.78, "duration": 5.13}, {"text": "And the conclusion\nis that you can", "start": 164.91, "duration": 1.68}, {"text": "make the graph induced H-free.", "start": 166.59, "duration": 4.74}, {"text": "So let me remind\nyou, the difference", "start": 171.33, "duration": 1.59}, {"text": "between the induced\ngraph subgraph", "start": 172.92, "duration": 2.94}, {"text": "and the usual subgraph.", "start": 175.86, "duration": 3.18}, {"text": "So we say that H is an induced\ncopy of G, induced subgraph", "start": 179.04, "duration": 13.18}, {"text": "of G. If one can obtain H from\nG by deleting vertices of G.", "start": 192.22, "duration": 30.622}, {"text": "You're not allowed\nto delete edges,", "start": 222.842, "duration": 1.458}, {"text": "but only allowed\nto delete vertices.", "start": 224.3, "duration": 2.61}, {"text": "So in other words,\nthe four cycle", "start": 226.91, "duration": 8.61}, {"text": "is not an induced\nsubgraph because, well,", "start": 235.52, "duration": 9.69}, {"text": "if you select four vertices, you\ndon't generate this four cycle.", "start": 245.21, "duration": 3.06}, {"text": "You get extra edges.", "start": 248.27, "duration": 1.02}, {"text": "So it is a subgraph, but\nnot an induced subgraph.", "start": 249.29, "duration": 2.77}, {"text": "So it is a theorem, the\ninduced graph removal Lemma.", "start": 260.05, "duration": 3.24}, {"text": "So it's a theorem,\nand let's discuss", "start": 263.29, "duration": 1.5}, {"text": "how we may prove that theorem.", "start": 264.79, "duration": 1.43}, {"text": "Question.", "start": 266.22, "duration": 0.5}, {"text": "OK, question is, why is it\nstronger than the graph removal", "start": 270.55, "duration": 2.45}, {"text": "lemma?", "start": 273.0, "duration": 1.81}, {"text": "So it's not stronger, but\nwe'll see the relationship", "start": 274.81, "duration": 5.25}, {"text": "between the two.", "start": 280.06, "duration": 1.21}, {"text": "So I claim that it is more\ndifficult to do this theorem.", "start": 281.27, "duration": 5.06}, {"text": "Any more questions?", "start": 286.33, "duration": 2.61}, {"text": "So let's pretend for a second\nthat whatever's in here", "start": 288.94, "duration": 8.38}, {"text": "is not quite true.", "start": 297.32, "duration": 1.285}, {"text": "So here's an example.", "start": 298.605, "duration": 0.875}, {"text": "For example, if your H is\nthree isolated vertices.", "start": 306.11, "duration": 8.25}, {"text": "So what is that saying?", "start": 314.36, "duration": 1.53}, {"text": "We're looking at\ncopies of H which", "start": 315.89, "duration": 2.34}, {"text": "are three isolated vertices.", "start": 318.23, "duration": 1.47}, {"text": "So really you are looking at\ntriangles in g complement.", "start": 319.7, "duration": 6.63}, {"text": "So this is exactly the\ntriangle removal lemma", "start": 326.33, "duration": 3.71}, {"text": "in the complement of g, but\nyou can't get rid of these guys", "start": 330.04, "duration": 5.26}, {"text": "by removing edges.", "start": 335.3, "duration": 1.38}, {"text": "So we need to make\nthe modification", "start": 336.68, "duration": 1.68}, {"text": "where instead of\nremoving these edges,", "start": 338.36, "duration": 2.22}, {"text": "we need to both remove and\nadd by adding or deleting.", "start": 340.58, "duration": 7.5}, {"text": "So maybe at the same time.", "start": 351.49, "duration": 1.268}, {"text": "So you're allowed to add some\nedges, delete some edges.", "start": 352.758, "duration": 2.292}, {"text": "But in total, you change no more\nthan epsilon n squared edges.", "start": 355.05, "duration": 3.738}, {"text": "So those are sometimes also\nknown as the edit distance.", "start": 358.788, "duration": 2.292}, {"text": "You're allowed to change edges.", "start": 365.69, "duration": 2.84}, {"text": "So you can add edges\nand delete edges.", "start": 368.53, "duration": 2.28}, {"text": "Any questions about\nthe statement?", "start": 376.09, "duration": 1.85}, {"text": "All right, so let's\nthink about how would you", "start": 380.88, "duration": 3.67}, {"text": "prove this result following\nthe proof that we did", "start": 384.55, "duration": 3.21}, {"text": "for the triangle removal lemma.", "start": 387.76, "duration": 2.9}, {"text": "So let's pretend that\nwe go through this proof", "start": 390.66, "duration": 2.68}, {"text": "and think about\nwhat could go wrong.", "start": 393.34, "duration": 1.89}, {"text": "So remember in the application\nof the removal lemma,", "start": 395.23, "duration": 2.61}, {"text": "so the recipe has three steps.", "start": 397.84, "duration": 2.41}, {"text": "The first step we\ndo a partition.", "start": 400.25, "duration": 2.204}, {"text": "So we partition applying\nSzemeredi's regularity lemma", "start": 405.42, "duration": 3.8}, {"text": "to this partition.", "start": 409.22, "duration": 1.67}, {"text": "And the second step\nis do a cleaning,", "start": 410.89, "duration": 5.51}, {"text": "and the two key things\nthat happen in the cleaning", "start": 416.4, "duration": 3.42}, {"text": "is we remove low density pairs\nof parts and irregular pairs.", "start": 419.82, "duration": 11.31}, {"text": "And the third step\nwe claim that once we", "start": 433.94, "duration": 2.44}, {"text": "do the cleaning, once\nwe remove those edges,", "start": 436.38, "duration": 3.51}, {"text": "the resulting\ngraphs should be H3.", "start": 439.89, "duration": 2.34}, {"text": "Because if we're not H3, then\nby considering the vertex parts", "start": 442.23, "duration": 4.74}, {"text": "where H lie and applying\nthe counting lemma,", "start": 446.97, "duration": 2.49}, {"text": "you can generate many\nmore copies of H.", "start": 449.46, "duration": 3.97}, {"text": "So these were the three\nmain steps in the proof", "start": 453.43, "duration": 2.12}, {"text": "of the triangle removal lemma.", "start": 455.55, "duration": 1.98}, {"text": "So let's see what\nhappens when we", "start": 457.53, "duration": 2.52}, {"text": "try to apply this strategy\nto the induced version.", "start": 460.05, "duration": 3.48}, {"text": "I mean, the partition you still\ndo the regularity partition.", "start": 463.53, "duration": 4.23}, {"text": "Nothing really changes there.", "start": 467.76, "duration": 2.61}, {"text": "So let's see in the\ncleaning step what happens.", "start": 470.37, "duration": 4.05}, {"text": "For low density pairs--", "start": 474.42, "duration": 2.04}, {"text": "well, so now we need to think\nabout not just low density", "start": 476.46, "duration": 2.79}, {"text": "pairs, but also\nhigh density pairs.", "start": 479.25, "duration": 2.45}, {"text": "Because in the induced, we\nthink about edges and non-edges", "start": 481.7, "duration": 3.07}, {"text": "at the same time.", "start": 484.77, "duration": 1.18}, {"text": "So you might think of a\nstrategy which is like the edge", "start": 485.95, "duration": 3.08}, {"text": "density is less than n.", "start": 489.03, "duration": 2.43}, {"text": "So less than epsilon, then\nyou remove all those edges.", "start": 491.46, "duration": 4.02}, {"text": "And if the edge density is\nbigger than 1 plus epsilon,", "start": 495.48, "duration": 2.97}, {"text": "then you add all\nof those edges in.", "start": 498.45, "duration": 3.65}, {"text": "So this is the\nnatural generalization", "start": 502.1, "duration": 1.76}, {"text": "of our strategy for\ntriangle removal", "start": 503.86, "duration": 1.96}, {"text": "lemma for the induced setting.", "start": 505.82, "duration": 1.58}, {"text": "So so far,\neverything's still OK.", "start": 507.4, "duration": 3.17}, {"text": "But now what would you do\nfor the irregular pairs?", "start": 510.57, "duration": 2.92}, {"text": "That's problematic.", "start": 517.97, "duration": 3.06}, {"text": "Previously for\ntriangle removal lemma,", "start": 521.03, "duration": 2.79}, {"text": "we just said if a pair is\nirregular, get rid of that pair", "start": 523.82, "duration": 3.45}, {"text": "and it will never show\nup in the counting stage.", "start": 527.27, "duration": 4.17}, {"text": "But that strategy\nno longer works.", "start": 531.44, "duration": 3.1}, {"text": "Because for example, if\nyour graph H being counted", "start": 534.54, "duration": 5.33}, {"text": "is this here, you do the\nregularity partition,", "start": 539.87, "duration": 8.76}, {"text": "and one of your\npairs is irregular.", "start": 548.63, "duration": 3.92}, {"text": "So you, let's say, get rid of\nall those edges in between.", "start": 552.55, "duration": 3.69}, {"text": "Then maybe you have\nsome embedding of H", "start": 556.24, "duration": 4.44}, {"text": "where you are going to\nuse the removed edges.", "start": 560.68, "duration": 5.225}, {"text": "And now you don't\nhave a counting lemma.", "start": 570.01, "duration": 4.03}, {"text": "You cannot say, I found this\ncopy of H in my changed graph.", "start": 574.04, "duration": 7.03}, {"text": "And by the counting lemma I\ncould get many copies of H", "start": 581.07, "duration": 2.58}, {"text": "because you have no control over\nthis irregular pair anymore.", "start": 583.65, "duration": 3.97}, {"text": "So the fact that you\nhave to add and remove", "start": 587.62, "duration": 3.26}, {"text": "makes it unclear\nwhat to do here,", "start": 590.88, "duration": 1.78}, {"text": "and this is a big obstacle\nin the application", "start": 592.66, "duration": 2.15}, {"text": "of the regularity lemma to\nthe induced removal lemma", "start": 594.81, "duration": 4.56}, {"text": "application.", "start": 599.37, "duration": 2.94}, {"text": "Any questions about\nthis obstacle?", "start": 602.31, "duration": 2.04}, {"text": "So make sure you understand\nwhy this is an issue.", "start": 608.55, "duration": 2.39}, {"text": "Otherwise you won't\nreally appreciate", "start": 610.94, "duration": 2.9}, {"text": "what will happen next.", "start": 613.84, "duration": 2.71}, {"text": "So somehow we need to find some\nkind of regularity partition", "start": 616.55, "duration": 5.08}, {"text": "to get no irregular pairs.", "start": 621.63, "duration": 3.54}, {"text": "So the question\nis, is there a way", "start": 625.17, "duration": 4.61}, {"text": "to partition so that there\nare no irregular pairs?", "start": 629.78, "duration": 6.8}, {"text": "For those of you who have\nstarted your homework", "start": 642.13, "duration": 2.4}, {"text": "problem on time, you realize\nthat the answer is no.", "start": 644.53, "duration": 4.62}, {"text": "So one of the\nhomework problems is", "start": 649.15, "duration": 1.62}, {"text": "for you to show that for\nthe specific graph known", "start": 650.77, "duration": 2.93}, {"text": "as the half graph.", "start": 653.7, "duration": 1.0}, {"text": "So there was an\nexample in homework", "start": 658.11, "duration": 2.478}, {"text": "that for the half graph--", "start": 660.588, "duration": 1.042}, {"text": "so you'll see in the\nhomework what this graph is--", "start": 668.665, "duration": 3.135}, {"text": "you cannot partition it so that\nyou get rid of all irregular", "start": 671.8, "duration": 3.25}, {"text": "pairs.", "start": 675.05, "duration": 0.5}, {"text": "Irregular pairs are\nnecessary in the statement", "start": 675.55, "duration": 2.79}, {"text": "of regularity lemma.", "start": 678.34, "duration": 1.31}, {"text": "So what I want to show\nyou today is a way", "start": 682.24, "duration": 2.1}, {"text": "to do what's called a strong\nregularity lemma in which you", "start": 684.34, "duration": 5.06}, {"text": "obtain a somewhat different\nconsequence that will allow", "start": 689.4, "duration": 3.6}, {"text": "you to get rid of\nirregular pairs", "start": 693.0, "duration": 2.438}, {"text": "in the more restricted setting.", "start": 695.438, "duration": 1.292}, {"text": "So this is the issue,\nthe irregular pairs.", "start": 699.73, "duration": 2.37}, {"text": "Before telling you what\nthis regularity lemma is,", "start": 708.42, "duration": 2.37}, {"text": "I want to give you a\nsmall generalization", "start": 710.79, "duration": 4.26}, {"text": "of the induced graph removal\nlemma, or just a different way", "start": 715.05, "duration": 3.3}, {"text": "to think about the statement.", "start": 718.35, "duration": 2.19}, {"text": "And you can think of it as\na colorful version instead", "start": 720.54, "duration": 3.18}, {"text": "of induced where you\nhave edges and no edges.", "start": 723.72, "duration": 5.25}, {"text": "You can also have colored edges.", "start": 728.97, "duration": 2.1}, {"text": "So colorful removal\nlemma, although this name", "start": 731.07, "duration": 3.12}, {"text": "is not standard.", "start": 734.19, "duration": 1.11}, {"text": "So colorful-- so when\nwe talk about graphs,", "start": 741.58, "duration": 4.03}, {"text": "it's colorful graph\nremoval lemma.", "start": 745.61, "duration": 3.43}, {"text": "So for every k, r, and epsilon,\nthere exists delta such", "start": 749.04, "duration": 8.45}, {"text": "that if curly H is a set of\nr edge of the complete graph", "start": 757.49, "duration": 20.53}, {"text": "on little k vertices.", "start": 778.02, "duration": 2.57}, {"text": "So edge coloring just\nmeans using r colors", "start": 780.59, "duration": 3.21}, {"text": "to color the edges.", "start": 783.8, "duration": 0.9}, {"text": "So there are no restrictions\nabout what are allowed,", "start": 784.7, "duration": 2.83}, {"text": "what are not allowed.", "start": 787.53, "duration": 0.92}, {"text": "So just a set of\npossible r colorings.", "start": 788.45, "duration": 3.843}, {"text": "Then if the complete graph--", "start": 792.293, "duration": 9.707}, {"text": "say it slightly differently.", "start": 807.823, "duration": 1.167}, {"text": "So then every r edge coloring\nof the complete graph", "start": 808.99, "duration": 15.66}, {"text": "on n vertices with fewer than\ndelta fraction of its k vertex", "start": 824.65, "duration": 18.2}, {"text": "subsets, say k vertex subgraphs,\nbelonging to the script H.", "start": 842.85, "duration": 17.46}, {"text": "So every such graph can be made\ncurly H free by recoloring,", "start": 860.31, "duration": 14.36}, {"text": "so using the same r colors, a\nfewer than epsilon fraction.", "start": 874.67, "duration": 15.04}, {"text": "So less than epsilon fraction\nof the edges of this kn.", "start": 889.71, "duration": 11.0}, {"text": "So in particular, the\nversion that we just stated,", "start": 903.36, "duration": 3.18}, {"text": "the induced version, so the\ninduced graph removal lemma,", "start": 906.54, "duration": 9.72}, {"text": "is the same as having two\ncolors and H having exactly one", "start": 916.26, "duration": 15.19}, {"text": "red-blue coloring of k\nof the complete graph", "start": 931.45, "duration": 13.17}, {"text": "on the same number\nof vertices as H.", "start": 944.62, "duration": 4.16}, {"text": "So you color red the edges\nand blue the non-edges,", "start": 948.78, "duration": 3.15}, {"text": "for instance.", "start": 951.93, "duration": 1.72}, {"text": "And you're saying, I want to\ncolor the big complete graph", "start": 953.65, "duration": 5.03}, {"text": "with red and blue in such a way\nthat there are very few copies", "start": 958.68, "duration": 4.08}, {"text": "of that pattern.", "start": 962.76, "duration": 1.14}, {"text": "So then I can recolor\nthe red and blue", "start": 963.9, "duration": 1.83}, {"text": "in a small number of places to\nget rid of all such patterns.", "start": 965.73, "duration": 4.02}, {"text": "So having a colored\npattern somewhere", "start": 969.75, "duration": 2.19}, {"text": "in your graph in this\ncomplete graph coloring", "start": 971.94, "duration": 2.67}, {"text": "is the same as having\nan induced subgraph.", "start": 974.61, "duration": 4.56}, {"text": "Yeah?", "start": 979.17, "duration": 0.58}, {"text": "AUDIENCE: So after done--", "start": 979.75, "duration": 1.38}, {"text": "like the statement after done\nis a really long sentence.", "start": 981.13, "duration": 2.846}, {"text": "Can I--", "start": 983.976, "duration": 0.584}, {"text": "YUFEI ZHAO: Yeah, OK.", "start": 984.56, "duration": 3.46}, {"text": "So every r edge coloring of kn\nwith a small number of patterns", "start": 988.02, "duration": 9.36}, {"text": "can be made h-free by recoloring\na small fraction of the edges.", "start": 997.38, "duration": 6.33}, {"text": "So like in a triangle\nremoval lemma,", "start": 1003.71, "duration": 1.92}, {"text": "every graph with a small\nnumber of triangles", "start": 1005.63, "duration": 3.54}, {"text": "can be made\ntriangle-free by removing", "start": 1009.17, "duration": 2.37}, {"text": "a small number of edges.", "start": 1011.54, "duration": 1.17}, {"text": "Any other questions?", "start": 1018.02, "duration": 3.69}, {"text": "So this is a restatement of\nthe induced removal lemma", "start": 1021.71, "duration": 5.369}, {"text": "with a bit more generality.", "start": 1027.079, "duration": 3.27}, {"text": "It's OK if you like\nthis one more or less,", "start": 1030.349, "duration": 2.611}, {"text": "but let's talk about the\ninduced version from now on.", "start": 1032.96, "duration": 2.85}, {"text": "But the same proofs that\nI will talk about also", "start": 1035.81, "duration": 2.64}, {"text": "applies to this version where\nyou have somewhat more colors.", "start": 1038.45, "duration": 4.26}, {"text": "So the variant of the\nregularity lemma that we'll need", "start": 1046.349, "duration": 4.591}, {"text": "is known as a strong\nregularity lemma.", "start": 1050.94, "duration": 2.43}, {"text": "To state the strong\nregularity lemma,", "start": 1067.32, "duration": 1.89}, {"text": "let me recall a notion that came\nup in the proof of Szemeredi's", "start": 1069.21, "duration": 3.21}, {"text": "regularity lemma.", "start": 1072.42, "duration": 2.4}, {"text": "And this was the\nnotion of an energy.", "start": 1074.82, "duration": 2.92}, {"text": "So recall that if you have\na partition, denoted P. So", "start": 1077.74, "duration": 7.19}, {"text": "if this is a partition of\nthe vertex set of a graph, G,", "start": 1084.93, "duration": 7.05}, {"text": "and here n is the\nnumber of vertices,", "start": 1091.98, "duration": 5.79}, {"text": "we defined this notion of energy\nto be this quantity denoted", "start": 1097.77, "duration": 11.62}, {"text": "q, which is basically a\nsquared mean of the densities", "start": 1109.39, "duration": 7.4}, {"text": "between vertex parts\nappropriately normalized", "start": 1116.79, "duration": 5.22}, {"text": "if the vertexes do not\nall have the same size.", "start": 1122.01, "duration": 4.92}, {"text": "In the proof of Szemeredi's\nregularity lemma,", "start": 1132.86, "duration": 5.83}, {"text": "there was an important\nenergy increment", "start": 1138.69, "duration": 2.07}, {"text": "step which says that if you have\nsome partition p that is not", "start": 1140.76, "duration": 11.49}, {"text": "epsilon regular, then there\nexists a refinement, Q.", "start": 1152.25, "duration": 12.068}, {"text": "And this refinement has\nthe property that Q has", "start": 1164.318, "duration": 5.602}, {"text": "a small number of pieces, or\nnot too large as a function of P", "start": 1169.92, "duration": 7.52}, {"text": "So it's bounded at\nleast in terms of P.", "start": 1177.44, "duration": 3.73}, {"text": "But also if P is not epsilon\nregular, then the energy of Q", "start": 1181.17, "duration": 7.2}, {"text": "is significantly larger than\nthe energy of P. So remember,", "start": 1188.37, "duration": 6.79}, {"text": "this was an important step in\nthe proof of regularity lemma.", "start": 1195.16, "duration": 3.42}, {"text": "So to state the strong\nregularity lemma,", "start": 1203.13, "duration": 4.25}, {"text": "we need that notion of energy.", "start": 1207.38, "duration": 1.918}, {"text": "And the statement of the\nstrong regularity lemma,", "start": 1209.298, "duration": 2.042}, {"text": "if you've never seen this\nkind of thing before,", "start": 1211.34, "duration": 1.958}, {"text": "will seem a bit\nintimidating at first", "start": 1213.298, "duration": 1.582}, {"text": "because it involves a whole\nsequence of parameters.", "start": 1214.88, "duration": 4.35}, {"text": "But we'll get used to it.", "start": 1219.23, "duration": 1.41}, {"text": "So instead of one\nepsilon parameter,", "start": 1223.88, "duration": 2.91}, {"text": "now you have a sequence\nof positive epsilons.", "start": 1226.79, "duration": 9.155}, {"text": "And part of the strength\nof this regularity lemma", "start": 1235.945, "duration": 2.085}, {"text": "is that depending on the\napplication you have in mind,", "start": 1238.03, "duration": 3.09}, {"text": "you can make the sequence\ngo to zero pretty quickly.", "start": 1241.12, "duration": 3.45}, {"text": "Thereby increasing the strength\nof the regularity lemma.", "start": 1244.57, "duration": 4.24}, {"text": "So there exists some m\nbound, which depends only", "start": 1248.81, "duration": 4.94}, {"text": "on your epsilons such that\nevery graph has not just one,", "start": 1253.75, "duration": 14.21}, {"text": "but now we're going to get a\npair of vertex partitions P", "start": 1267.96, "duration": 8.21}, {"text": "and Q with the\nfollowing properties.", "start": 1276.17, "duration": 6.76}, {"text": "So first, P refines--", "start": 1282.93, "duration": 4.25}, {"text": "so Q refines P. So it's\na pair of partitions,", "start": 1287.18, "duration": 9.81}, {"text": "one refining the other.", "start": 1296.99, "duration": 1.66}, {"text": "The number of parts\nof Q is bounded", "start": 1302.4, "duration": 2.85}, {"text": "just like in the usual\nregularity lemma.", "start": 1305.25, "duration": 2.01}, {"text": "The partition P\nepsilon 0 regular.", "start": 1310.07, "duration": 4.89}, {"text": "And here is the new part\nthat's the most important one.", "start": 1317.72, "duration": 4.63}, {"text": "Q is very epsilon regular.", "start": 1322.35, "duration": 4.87}, {"text": "So it's not just\nepsilon 0 regular,", "start": 1327.22, "duration": 2.03}, {"text": "it's epsilon sub the number\nof parts of P regular.", "start": 1329.25, "duration": 4.16}, {"text": "So you should think of\nthis as extremely regular", "start": 1336.33, "duration": 7.05}, {"text": "because you get to choose what\nthe sequence of epsilon is.", "start": 1343.38, "duration": 4.9}, {"text": "And finally, the energy\ndifference between P and Q", "start": 1348.28, "duration": 4.44}, {"text": "is not too big.", "start": 1352.72, "duration": 1.26}, {"text": "This is the statement of\nthe strong regularity lemma.", "start": 1363.69, "duration": 3.14}, {"text": "It produces for you\nnot just one partition,", "start": 1366.83, "duration": 1.92}, {"text": "but a pair of partitions.", "start": 1368.75, "duration": 2.03}, {"text": "And in this pair\nof partitions, you", "start": 1370.78, "duration": 2.02}, {"text": "have one partition, P,\nwhich is similar to the one", "start": 1372.8, "duration": 4.68}, {"text": "that we obtained from\nSzemeredi's regularity lemma", "start": 1377.48, "duration": 2.18}, {"text": "is some epsilon 0 regular, but\nwe also get a refinement Q.", "start": 1379.66, "duration": 6.49}, {"text": "And this Q is extremely regular.", "start": 1386.15, "duration": 5.1}, {"text": "So you can think\nthat is P, then Q", "start": 1391.25, "duration": 8.26}, {"text": "is an extremely\nregular refinement", "start": 1399.51, "duration": 2.53}, {"text": "of P. Any questions\nabout the statement", "start": 1402.04, "duration": 6.17}, {"text": "of the strong regularity lemma?", "start": 1408.21, "duration": 1.75}, {"text": "So the sequence of\nepsilons gives you", "start": 1413.86, "duration": 1.75}, {"text": "flexibility on how to apply it,\nbut let's see how to prove it.", "start": 1415.61, "duration": 4.2}, {"text": "And the proof is once you\nunderstand how this works,", "start": 1419.81, "duration": 3.99}, {"text": "conceptually it's pretty short.", "start": 1423.8, "duration": 3.27}, {"text": "But let me do it slowly\nso that we can appreciate", "start": 1427.07, "duration": 3.3}, {"text": "this sequence of epsilons.", "start": 1430.37, "duration": 4.6}, {"text": "And the idea is that we\nwill repeatedly apply", "start": 1434.97, "duration": 3.3}, {"text": "Szemeredi's regularity lemma.", "start": 1438.27, "duration": 1.3}, {"text": "So start with the\nregularity lemma.", "start": 1446.03, "duration": 2.48}, {"text": "We'll apply it\nrepeatedly to generate", "start": 1448.51, "duration": 4.47}, {"text": "a sequence of partitions.", "start": 1452.98, "duration": 3.56}, {"text": "So first, let me remind you\na statement of Szemeredi's", "start": 1456.54, "duration": 5.08}, {"text": "regularity lemma.", "start": 1461.62, "duration": 0.99}, {"text": "This is slightly\ndifferent from the one", "start": 1462.61, "duration": 1.71}, {"text": "that we stated, but comes\nout of the same proof.", "start": 1464.32, "duration": 4.01}, {"text": "So for every epsilon,\nthere exists some m0", "start": 1468.33, "duration": 5.11}, {"text": "which depends on epsilon such\nthat for every partition P0,", "start": 1473.44, "duration": 8.06}, {"text": "so starting with\nsome partition--", "start": 1481.5, "duration": 5.03}, {"text": "so actually, let me\nstart with just P.", "start": 1486.53, "duration": 1.98}, {"text": "So if you start with some\npartition of the vertex set", "start": 1488.51, "duration": 6.41}, {"text": "of g, there exists a refinement\nP prime of P into at most--", "start": 1494.92, "duration": 15.67}, {"text": "OK, so the refinement has is\nsuch that with each part of P", "start": 1510.59, "duration": 16.93}, {"text": "refined into at\nmost m0 parts such", "start": 1527.52, "duration": 11.44}, {"text": "that P prime, the new\npartition, is epsilon regular.", "start": 1538.96, "duration": 5.69}, {"text": "So this is a statement of\nSzemeredi's regularity lemma", "start": 1552.47, "duration": 2.43}, {"text": "that we will apply repeatedly.", "start": 1554.9, "duration": 1.95}, {"text": "So in the version that\nwe've seen before,", "start": 1556.85, "duration": 2.02}, {"text": "we would start with\na trivial partition.", "start": 1558.87, "duration": 3.63}, {"text": "And applying\nrefinements repeatedly", "start": 1562.5, "duration": 3.24}, {"text": "in the proof to get a partition\ninto a bounded number of parts", "start": 1565.74, "duration": 4.14}, {"text": "such that the final\npartition is epsilon regular.", "start": 1569.88, "duration": 4.2}, {"text": "But instead, in the proof\nof the regularity lemma", "start": 1574.08, "duration": 2.94}, {"text": "if you start with not\na trivial partition", "start": 1577.02, "duration": 2.16}, {"text": "but start with a given partition\nand run this exact same proof,", "start": 1579.18, "duration": 4.92}, {"text": "you find this consequence.", "start": 1584.1, "duration": 2.28}, {"text": "Except now you can guarantee\nthat the final partition", "start": 1586.38, "duration": 2.94}, {"text": "is a refinement of the\none that you are given.", "start": 1589.32, "duration": 2.25}, {"text": "So let's apply the\nstatement, and we obtain", "start": 1595.88, "duration": 7.06}, {"text": "a sequence of partitions of g--", "start": 1602.94, "duration": 7.7}, {"text": "the vertex set of g--", "start": 1610.64, "duration": 1.82}, {"text": "starting with P0 being a\ntrivial partition, and so on.", "start": 1612.46, "duration": 14.79}, {"text": "Such that each partition,\neach P sub i plus 1", "start": 1627.25, "duration": 10.08}, {"text": "refines the previous\none, and such", "start": 1637.33, "duration": 12.61}, {"text": "that each P sub i plus 1 is\nepsilon sub a P sub i regular.", "start": 1649.94, "duration": 9.43}, {"text": "So you apply the regularity\nlemma with parameter", "start": 1662.36, "duration": 3.1}, {"text": "based on the number of\nparts you currently have.", "start": 1665.46, "duration": 3.69}, {"text": "Applied to the\ncurrent partition,", "start": 1669.15, "duration": 1.86}, {"text": "you get a finer partition\nthat's extremely regular.", "start": 1671.01, "duration": 5.81}, {"text": "And you also know\nthat the number", "start": 1676.82, "duration": 2.1}, {"text": "of parts of the new\npartition is bounded in terms", "start": 1678.92, "duration": 5.43}, {"text": "of the previous partition.", "start": 1684.35, "duration": 2.387}, {"text": "All right.", "start": 1703.138, "duration": 2.977}, {"text": "Any questions so far?", "start": 1706.115, "duration": 0.875}, {"text": "So now we get this\nsequence of partitions.", "start": 1711.51, "duration": 4.28}, {"text": "We can keep on doing this.", "start": 1715.79, "duration": 1.53}, {"text": "So g could be arbitrarily\nlarge, but eventually we", "start": 1717.32, "duration": 5.83}, {"text": "will be able to obtain\nthe last condition here,", "start": 1723.15, "duration": 2.83}, {"text": "which is the only thing\nthat is missing so far.", "start": 1725.98, "duration": 3.19}, {"text": "So since the energy is\nbounded between 0 and 1,", "start": 1729.17, "duration": 10.34}, {"text": "there exists some i at\nmost 1 over epsilon 0", "start": 1739.51, "duration": 7.14}, {"text": "such that the energy goes\nup by less than epsilon 0.", "start": 1746.65, "duration": 9.21}, {"text": "Because otherwise your\nenergy would exceed 1.", "start": 1766.39, "duration": 2.31}, {"text": "So now let's set\nP to be this Pi,", "start": 1773.37, "duration": 5.22}, {"text": "and Q to be this,\nthe refinement--", "start": 1778.59, "duration": 5.33}, {"text": "the next term in the partition.", "start": 1783.92, "duration": 1.75}, {"text": "And what we find is that the--", "start": 1790.47, "duration": 4.21}, {"text": "so then you have basically\nall the conditions.", "start": 1794.68, "duration": 2.43}, {"text": "So p is epsilon 0 regular,\nbecause it is epsilon--", "start": 1797.11, "duration": 5.97}, {"text": "the previous term, which is\nat most epsilon 0 regular.", "start": 1803.08, "duration": 4.79}, {"text": "And you have this one as\nwell, and this one as well.", "start": 1807.87, "duration": 4.1}, {"text": "And we want to show that\nthe number of parts of Q", "start": 1811.97, "duration": 2.73}, {"text": "is bounded.", "start": 1814.7, "duration": 2.26}, {"text": "And that's basically\nbecause each time there", "start": 1816.96, "duration": 2.35}, {"text": "was a bound on the number\nof parts which depends only", "start": 1819.31, "duration": 3.48}, {"text": "on the regularity\nparameters, and you're", "start": 1822.79, "duration": 2.1}, {"text": "repeating that bound a\nbounded number of times.", "start": 1824.89, "duration": 3.09}, {"text": "So Q is-- so it's bounded as\na function of the sequence", "start": 1830.52, "duration": 14.09}, {"text": "of epsilons-- this infinite\nvector of epsilons,", "start": 1844.61, "duration": 2.4}, {"text": "but it is a bounded number.", "start": 1847.01, "duration": 2.17}, {"text": "You're only iterating this\nbound a bounded number of times.", "start": 1849.18, "duration": 5.143}, {"text": "And that finishes the proof.", "start": 1854.323, "duration": 1.167}, {"text": "Any questions?", "start": 1860.946, "duration": 1.417}, {"text": "It may be somewhat mysterious\nto you right now why we do this,", "start": 1869.77, "duration": 3.41}, {"text": "so we'll get that\napplication a second.", "start": 1873.18, "duration": 1.66}, {"text": "But for now, I just want to\ncomment a bit on the bounds.", "start": 1874.84, "duration": 3.17}, {"text": "Of course, the bounds depend\non what epsilon i's do you use.", "start": 1886.09, "duration": 6.04}, {"text": "And typically, you\nwant the epsilon i's", "start": 1892.13, "duration": 1.77}, {"text": "to decrease with more\nparts that you have.", "start": 1893.9, "duration": 3.45}, {"text": "And with almost all\nreasonable applications", "start": 1897.35, "duration": 2.67}, {"text": "of this regularity lemma,\nthe strong regularity lemma--", "start": 1900.02, "duration": 4.43}, {"text": "so for example, with epsilon\ni being some epsilon divided", "start": 1904.45, "duration": 8.51}, {"text": "by, let's say, i plus 1 or\nany polynomial of the i's--", "start": 1912.96, "duration": 5.18}, {"text": "or you can even let it decay\nquicker than that, as well.", "start": 1918.14, "duration": 4.09}, {"text": "You see, basically what\nhappens is that you", "start": 1922.23, "duration": 4.08}, {"text": "are applying this m0 bound.", "start": 1926.31, "duration": 3.0}, {"text": "m0 applied in succession\n1 over epsilon times.", "start": 1935.3, "duration": 10.06}, {"text": "In the regularity lemma, we\nsaw that the m0 that comes out", "start": 1949.25, "duration": 4.55}, {"text": "of Szemeredi's graph regularity\nlemma is the tower function.", "start": 1953.8, "duration": 3.33}, {"text": "So the tower function,\nthat's a tower of i", "start": 1959.872, "duration": 4.098}, {"text": "is defined to be the exponential\nfunction iterated i times.", "start": 1963.97, "duration": 8.356}, {"text": "So of course, I'm\nbeing somewhat loose", "start": 1972.326, "duration": 1.594}, {"text": "here with the exact dependence,\nbut you get the idea", "start": 1973.92, "duration": 3.33}, {"text": "that now we want to apply\nthe tower function i times.", "start": 1977.25, "duration": 4.8}, {"text": "Instead of iterating\nthe exponential i times,", "start": 1995.22, "duration": 2.13}, {"text": "now you iterate the\ntower function i times.", "start": 1997.35, "duration": 3.03}, {"text": "And some of you laughing, this\nis an incredibly large number.", "start": 2000.38, "duration": 2.912}, {"text": "It's even larger than\nthe tower function.", "start": 2003.292, "duration": 1.708}, {"text": "So in literature, especially\naround the regularity lemma,", "start": 2009.49, "duration": 4.04}, {"text": "this function where you\niterate the tower function i", "start": 2013.53, "duration": 3.49}, {"text": "times is given the name wowzer.", "start": 2017.02, "duration": 2.853}, {"text": "[LAUGHTER] As in, wow,\nthis is a huge number.", "start": 2019.873, "duration": 7.407}, {"text": "So it's a step up in\nthe Ackerman hierarchy.", "start": 2027.28, "duration": 3.12}, {"text": "So if you repeat the\nwowzer function i times,", "start": 2030.4, "duration": 3.08}, {"text": "you move up one ladder\nin the Ackerman hierarchy", "start": 2033.48, "duration": 3.16}, {"text": "and this hierarchy of\nrapidly growing functions.", "start": 2036.64, "duration": 4.42}, {"text": "But in any case, it's bounded\nand that's good enough for us.", "start": 2041.06, "duration": 2.5}, {"text": "Any questions so far?", "start": 2050.695, "duration": 0.875}, {"text": "Yeah?", "start": 2056.38, "duration": 0.57}, {"text": "AUDIENCE: What do you\ncall like [INAUDIBLE]", "start": 2056.95, "duration": 2.907}, {"text": "YUFEI ZHAO: Yes, so\nquestion is, what do you", "start": 2059.857, "duration": 1.833}, {"text": "call wowzer iterated?", "start": 2061.69, "duration": 2.23}, {"text": "I'm not aware of a\nstandard name for that.", "start": 2063.92, "duration": 3.25}, {"text": "Actually, even the\nname wowzer somehow", "start": 2067.17, "duration": 1.81}, {"text": "is very common in the\ncombinatorics community,", "start": 2068.98, "duration": 3.159}, {"text": "but I think most people\noutside this community", "start": 2072.139, "duration": 2.06}, {"text": "will not recognize this word.", "start": 2074.199, "duration": 1.311}, {"text": "Any more questions?", "start": 2080.139, "duration": 2.25}, {"text": "So another way it's a step\nup in Ackerman hierarchy.", "start": 2082.389, "duration": 3.756}, {"text": "So it's enumerated one,\ntwo, three, four, you know,", "start": 2086.145, "duration": 2.125}, {"text": "if you keep going up.", "start": 2088.27, "duration": 0.9}, {"text": "All right.", "start": 2092.994, "duration": 3.346}, {"text": "Another remark about this\nstrong regularity lemma", "start": 2096.34, "duration": 4.95}, {"text": "is that it will be\nconvenient for us-- actually,", "start": 2101.29, "duration": 3.62}, {"text": "some are more essential compared\nto our previous applications--", "start": 2104.91, "duration": 3.04}, {"text": "to make the parts equitable.", "start": 2107.95, "duration": 1.962}, {"text": "So P and Q equitable.", "start": 2113.15, "duration": 5.56}, {"text": "And basically, the parts\nare such that all the--", "start": 2118.71, "duration": 3.465}, {"text": "the partitions are such that\nall the parts have basically", "start": 2122.175, "duration": 2.893}, {"text": "the same number of vertices.", "start": 2125.068, "duration": 1.167}, {"text": "So I won't make it\nprecise, but you can do it.", "start": 2126.235, "duration": 4.25}, {"text": "It's not too hard to do it.", "start": 2130.485, "duration": 1.125}, {"text": "And you can prove\nit similar to how", "start": 2131.61, "duration": 3.57}, {"text": "I described how to modify the\nproof of the regularity level.", "start": 2135.18, "duration": 3.85}, {"text": "So I won't belabor\nthat point, but we'll", "start": 2139.03, "duration": 2.21}, {"text": "use the equitable version.", "start": 2141.24, "duration": 1.23}, {"text": "All right, so how does one\nuse this regularity lemma?", "start": 2145.79, "duration": 4.97}, {"text": "Let me state a\ncorollary, and let", "start": 2150.76, "duration": 2.7}, {"text": "me call this a corollary\nstar because you actually", "start": 2153.46, "duration": 2.39}, {"text": "need to do some work\nto get it to follow", "start": 2155.85, "duration": 2.58}, {"text": "from the strong\nregularity lemma.", "start": 2158.43, "duration": 1.45}, {"text": "But the corollary is\nthe version that we", "start": 2159.88, "duration": 1.667}, {"text": "will apply that if you\nstart with a decreasing", "start": 2161.547, "duration": 4.873}, {"text": "sequence of this epsilon,\nthen there exists a delta such", "start": 2166.42, "duration": 10.795}, {"text": "that the following is true.", "start": 2177.215, "duration": 1.125}, {"text": "Every n vertex graph has an\nequitable vertex partition,", "start": 2182.65, "duration": 18.71}, {"text": "call it i through the\nk, and a subset Wi", "start": 2201.36, "duration": 10.17}, {"text": "of each Vi such that the\nfollowing properties hold.", "start": 2211.53, "duration": 8.05}, {"text": "First, all the W's\nare fairly large.", "start": 2219.58, "duration": 5.38}, {"text": "They're at least\nconstant proportion", "start": 2224.96, "duration": 2.11}, {"text": "of the total vertex set.", "start": 2227.07, "duration": 1.47}, {"text": "Between every pair of Wi Wj,\nit is epsilon sub k regular.", "start": 2233.04, "duration": 9.48}, {"text": "And this is the point\nI want to emphasize.", "start": 2250.89, "duration": 1.75}, {"text": "So here there are not you\nregular pairs anymore.", "start": 2252.64, "duration": 2.72}, {"text": "So it is every.", "start": 2255.36, "duration": 1.81}, {"text": "So no irregular pairs\nbetween the Wi's,", "start": 2261.274, "duration": 3.596}, {"text": "and also we need\nto include the case", "start": 2264.87, "duration": 3.87}, {"text": "when i equals the j, as well.", "start": 2268.74, "duration": 2.16}, {"text": "So each Wi is\nregular with itself.", "start": 2270.9, "duration": 2.595}, {"text": "And furthermore, the edge\ndensities between the V's are", "start": 2277.06, "duration": 8.79}, {"text": "similar to the edge densities\nbetween the corresponding W's.", "start": 2285.85, "duration": 5.97}, {"text": "And here it is for\nmost pairs for all", "start": 2291.82, "duration": 6.24}, {"text": "but at most epsilon\nk square pairs.", "start": 2298.06, "duration": 5.49}, {"text": "Epsilon 0, yeah.", "start": 2310.32, "duration": 1.425}, {"text": "At most epsilon 0.", "start": 2311.745, "duration": 1.115}, {"text": "Any questions about\nthe statement?", "start": 2320.66, "duration": 1.745}, {"text": "So let me show you\nhow you could deduce", "start": 2337.44, "duration": 3.51}, {"text": "the corollary from the\nstrong regularity lemma.", "start": 2340.95, "duration": 3.57}, {"text": "So first, let me\ndraw your picture.", "start": 2356.95, "duration": 1.77}, {"text": "So here you have a\nregularity partition.", "start": 2363.07, "duration": 3.276}, {"text": "And so these are your\nV's, and inside each V", "start": 2371.01, "duration": 7.145}, {"text": "I find a W such that\nif I look at the edge", "start": 2378.155, "duration": 12.185}, {"text": "sets between pairwise\nblue sets, including", "start": 2390.34, "duration": 3.01}, {"text": "the blue sets with themselves,\nit is always very regular.", "start": 2393.35, "duration": 5.6}, {"text": "And also, the edge densities\nbetween the blue sets", "start": 2398.95, "duration": 5.67}, {"text": "is mostly very\nsimilar to the edge", "start": 2404.62, "duration": 2.97}, {"text": "density between their\nambient white sets.", "start": 2407.59, "duration": 2.52}, {"text": "OK, so let me say a few words--", "start": 2420.04, "duration": 1.87}, {"text": "I won't go into\ntoo many details--", "start": 2421.91, "duration": 1.97}, {"text": "about how you might\ndeduce this corollary", "start": 2423.88, "duration": 2.4}, {"text": "from the strong\nregularity lemma.", "start": 2426.28, "duration": 2.19}, {"text": "So first let me\ndo something which", "start": 2431.28, "duration": 2.04}, {"text": "is slightly simpler, which\nis to not yet require", "start": 2433.32, "duration": 6.51}, {"text": "that the blue sets, Wi's,\nare regular with themselves.", "start": 2439.83, "duration": 4.496}, {"text": "So without requiring this\nas regular so we can obtain", "start": 2451.48, "duration": 8.15}, {"text": "the Wi's by picking\na uniform random part", "start": 2459.63, "duration": 14.03}, {"text": "of the final partition,\nQ, inside each part of P", "start": 2473.66, "duration": 14.21}, {"text": "in the strong regularity lemma.", "start": 2487.87, "duration": 1.77}, {"text": "So you have the strong\nregularity lemma,", "start": 2495.92, "duration": 1.92}, {"text": "which produces for you a\npair of partitions like that.", "start": 2497.84, "duration": 6.24}, {"text": "So it produces for you\na pair of partitions.", "start": 2504.08, "duration": 2.94}, {"text": "And what we will do is to pick\none of these guys as my W,", "start": 2507.02, "duration": 6.54}, {"text": "pick one of these\nguys at random,", "start": 2513.56, "duration": 1.488}, {"text": "and pick one of\nthose guys at random.", "start": 2515.048, "duration": 1.542}, {"text": "Because W is so extremely\nregular, most of these pairs", "start": 2520.73, "duration": 5.89}, {"text": "will be regular.", "start": 2526.62, "duration": 3.12}, {"text": "So with high\nprobability, you will not", "start": 2529.74, "duration": 3.87}, {"text": "encounter any\nirregular pairs if you", "start": 2533.61, "duration": 5.19}, {"text": "pick the W's randomly as parts\nof Q. So that's the key point.", "start": 2538.8, "duration": 6.77}, {"text": "Here we're using that\nQ is extremely regular.", "start": 2545.57, "duration": 3.27}, {"text": "So all the Wi Wj is\nregular for all i not equal", "start": 2560.93, "duration": 6.49}, {"text": "to j with high probability.", "start": 2567.42, "duration": 2.298}, {"text": "But the other thing that we\nwould like is that the edge", "start": 2573.55, "duration": 2.94}, {"text": "densities between the W's\nare similar to those between", "start": 2576.49, "duration": 4.32}, {"text": "the V's.", "start": 2580.81, "duration": 1.93}, {"text": "And for that, we will use this\ncondition about their energies", "start": 2582.74, "duration": 3.28}, {"text": "being very similar\nto each other.", "start": 2586.02, "duration": 1.53}, {"text": "So the third\nconsequence, C, is--", "start": 2590.65, "duration": 6.15}, {"text": "it's a consequence\nof the energy bound.", "start": 2596.8, "duration": 5.4}, {"text": "Because recall that in our proof\nof the Szemeredi regularity", "start": 2610.82, "duration": 3.69}, {"text": "lemma there was\nan interpretation", "start": 2614.51, "duration": 2.22}, {"text": "of the energy as\nthe second moment", "start": 2616.73, "duration": 7.13}, {"text": "of a certain random\nvariable which we called z.", "start": 2623.86, "duration": 3.48}, {"text": "And using that interpretation,\nI can write down", "start": 2631.64, "duration": 3.19}, {"text": "this expression like that.", "start": 2634.83, "duration": 5.49}, {"text": "We are here assuming\nfor simplicity", "start": 2640.32, "duration": 3.54}, {"text": "that Q is completely\nequitable, so all the parts", "start": 2643.86, "duration": 4.17}, {"text": "have exactly the same size.", "start": 2648.03, "duration": 1.62}, {"text": "Z of Q is defined to be the\nedge density between Vi and Vj", "start": 2649.65, "duration": 6.09}, {"text": "for random ij.", "start": 2655.74, "duration": 5.27}, {"text": "So this is a random variable z.", "start": 2661.01, "duration": 2.76}, {"text": "So you pick pair\nof parts uniformly,", "start": 2663.77, "duration": 4.64}, {"text": "or maybe with some weights\nif they're not exactly equal.", "start": 2668.41, "duration": 2.7}, {"text": "And you evaluate\nthe edge density.", "start": 2671.11, "duration": 3.37}, {"text": "So this energy difference\nis the difference", "start": 2674.48, "duration": 3.17}, {"text": "between the second moments.", "start": 2677.65, "duration": 1.68}, {"text": "And because Q is\na refinement of P,", "start": 2679.33, "duration": 7.38}, {"text": "it is the case that this\ndifference of L2 norms", "start": 2686.71, "duration": 9.16}, {"text": "is equal to the second\nmoment of the difference", "start": 2695.87, "duration": 4.99}, {"text": "of the random variables.", "start": 2700.86, "duration": 1.62}, {"text": "So we saw a version\nof this earlier", "start": 2702.48, "duration": 2.28}, {"text": "when we were discussing\nvariance in the context", "start": 2704.76, "duration": 3.15}, {"text": "of the proof of the\nsimilar irregularity lemma.", "start": 2707.91, "duration": 2.61}, {"text": "Here it's basically the same.", "start": 2710.52, "duration": 1.29}, {"text": "You can either look at this\ninequality part by part of V,", "start": 2711.81, "duration": 4.62}, {"text": "or if you like to be\na bit more abstract", "start": 2716.43, "duration": 4.62}, {"text": "then this is actually a\ncase of Pythagorean theorem.", "start": 2721.05, "duration": 3.12}, {"text": "If you view these as vectors\nin a certain vector space,", "start": 2729.91, "duration": 4.44}, {"text": "then you have some\northogonality.", "start": 2734.35, "duration": 1.75}, {"text": "So you have this sum\nof squares identity.", "start": 2736.1, "duration": 4.278}, {"text": "Where does part A come from?", "start": 2745.86, "duration": 1.932}, {"text": "So part A, we want the parts,\nthat Wi's to be not too small,", "start": 2747.792, "duration": 4.548}, {"text": "but that comes from a bound\non the number of parts of Q.", "start": 2752.34, "duration": 23.221}, {"text": "So so far this more or\nless proves the corollary", "start": 2775.561, "duration": 3.249}, {"text": "except for that we\nsimplified our lives", "start": 2778.81, "duration": 4.24}, {"text": "by requiring just that the i\nnot equal to j, the Vi Vj's are", "start": 2783.05, "duration": 6.63}, {"text": "regular.", "start": 2789.68, "duration": 1.42}, {"text": "But in the statement\nup there, we also want", "start": 2791.1, "duration": 2.7}, {"text": "the Vi's-- so the Wi's ice to\nbe regular with themselves,", "start": 2793.8, "duration": 3.85}, {"text": "which will be important\nfor application.", "start": 2797.65, "duration": 3.79}, {"text": "So I won't explain how to do\nthat, and part of the reason", "start": 2801.44, "duration": 4.23}, {"text": "is that this is also one\nof your homework problems.", "start": 2805.67, "duration": 3.5}, {"text": "So in one of the homework\nproblems problem set 3,", "start": 2809.17, "duration": 2.75}, {"text": "you were asked to prove\nthat every graph has", "start": 2811.92, "duration": 3.51}, {"text": "a subset of vertices that is of\nleast constant proportion such", "start": 2815.43, "duration": 5.67}, {"text": "that it is regular with itself.", "start": 2821.1, "duration": 3.78}, {"text": "And the methods\nyou use there will", "start": 2824.88, "duration": 1.89}, {"text": "be applicable to handle the\nsituation over here, as well.", "start": 2826.77, "duration": 5.44}, {"text": "So putting all of these\ningredients together,", "start": 2832.21, "duration": 2.82}, {"text": "we get the corollary whereby\nyou have this picture,", "start": 2835.03, "duration": 4.99}, {"text": "you have this partition.", "start": 2840.02, "duration": 1.59}, {"text": "I don't even require\nthe Vi's to be regular.", "start": 2841.61, "duration": 2.58}, {"text": "That doesn't matter anymore.", "start": 2844.19, "duration": 1.45}, {"text": "All that matters is that between\nthe Wi's they are very regular,", "start": 2845.64, "duration": 3.59}, {"text": "and that there are no irregular\nparts between these Wi's.", "start": 2849.23, "duration": 5.22}, {"text": "And now we'll be able to go back\nto the induced graph removal", "start": 2854.45, "duration": 7.16}, {"text": "lemma where previously we had\nan issue with the existence", "start": 2861.61, "duration": 5.31}, {"text": "of irregular pairs in the use of\nSzemeredi regularity partition,", "start": 2866.92, "duration": 4.96}, {"text": "and now we have a tool\nto get around that.", "start": 2871.88, "duration": 3.37}, {"text": "So next we will see how\nto execute this proof,", "start": 2875.25, "duration": 5.05}, {"text": "but at this point hopefully\nyou already see an outline.", "start": 2880.3, "duration": 3.54}, {"text": "Because you no longer need to\nworry about this thing here.", "start": 2883.84, "duration": 6.838}, {"text": "Let's take a quick break.", "start": 2890.678, "duration": 1.042}, {"text": "Any questions so far?", "start": 2894.76, "duration": 1.07}, {"text": "Yes?", "start": 2900.6, "duration": 0.88}, {"text": "AUDIENCE: Why are we\nable to [INAUDIBLE]", "start": 2901.48, "duration": 10.06}, {"text": "YUFEI ZHAO: OK, so\nthe question was,", "start": 2911.54, "duration": 1.5}, {"text": "there was a step where we were\nlooking at some expectations", "start": 2913.04, "duration": 4.13}, {"text": "of squares.", "start": 2917.17, "duration": 2.13}, {"text": "And so why was\nthat identity true?", "start": 2919.3, "duration": 4.37}, {"text": "So if you look back to the\nproof of Szemeredi's regularity", "start": 2923.67, "duration": 2.58}, {"text": "lemma, we already saw an\ninstance of that inequality", "start": 2926.25, "duration": 2.682}, {"text": "in the computation\nof the variance.", "start": 2928.932, "duration": 1.458}, {"text": "So you know that the\nvariance of x, on one", "start": 2937.86, "duration": 3.41}, {"text": "hand it is equal to where\nmu is the mean of x.", "start": 2941.27, "duration": 9.2}, {"text": "And on the other hand, it\nis equal to this quantity.", "start": 2950.47, "duration": 5.2}, {"text": "So you agree with this formula?", "start": 2960.41, "duration": 2.95}, {"text": "And you can expand it to\nprove it, and the thing that--", "start": 2963.36, "duration": 5.0}, {"text": "the question that you\nraised basically you", "start": 2968.36, "duration": 2.63}, {"text": "can prove by looking at\nthis formula part by part.", "start": 2970.99, "duration": 3.69}, {"text": "Any more questions?", "start": 2979.25, "duration": 1.352}, {"text": "So let's now prove the\ninduced graph removal lemma.", "start": 2989.76, "duration": 4.59}, {"text": "And we'll follow the\nregularity partition,", "start": 2994.35, "duration": 2.76}, {"text": "but with a small\ntwist that Instead", "start": 2997.11, "duration": 2.4}, {"text": "of using Szemeredi's\nregularity lemma,", "start": 2999.51, "duration": 2.34}, {"text": "we will use that\ncorollary up there.", "start": 3001.85, "duration": 1.89}, {"text": "So let's prove the induced\ngraph removal lemma.", "start": 3011.56, "duration": 3.32}, {"text": "So the three steps.", "start": 3020.82, "duration": 0.98}, {"text": "First, we do partition.", "start": 3021.8, "duration": 1.651}, {"text": "So let's suppose you have a--", "start": 3030.05, "duration": 3.32}, {"text": "so we suppose g is like above.", "start": 3036.85, "duration": 2.25}, {"text": "You have very few\ninduced copies of H.", "start": 3039.1, "duration": 6.1}, {"text": "Let's apply the corollary to get\na partition of the vertex set", "start": 3045.2, "duration": 5.97}, {"text": "of g into k parts.", "start": 3051.17, "duration": 6.49}, {"text": "And inside each part\nI have a W. Satisfying", "start": 3057.66, "duration": 7.03}, {"text": "the following properties\nthat each Wi Wj", "start": 3064.69, "duration": 7.26}, {"text": "is regular with the\nfollowing parameter which", "start": 3071.95, "duration": 6.567}, {"text": "will come out of later when we\nneed to use the counting lemma.", "start": 3078.517, "duration": 2.583}, {"text": "But it's some number, but\ndon't worry too much about it.", "start": 3081.1, "duration": 2.64}, {"text": "So here I'm going to--", "start": 3087.05, "duration": 3.26}, {"text": "so let's say H has\nlittle H vertices.", "start": 3090.31, "duration": 5.375}, {"text": "So between Wi Wj\nit is this regular.", "start": 3105.405, "duration": 2.655}, {"text": "So we actually have not\nyet used the full strength", "start": 3108.06, "duration": 2.67}, {"text": "of the corollary where I can\nmake the regularity even depend", "start": 3110.73, "duration": 8.01}, {"text": "on k.", "start": 3118.74, "duration": 0.78}, {"text": "So we will not need\nthat here, but we'll", "start": 3119.52, "duration": 2.13}, {"text": "need it in a later application.", "start": 3121.65, "duration": 2.44}, {"text": "So the exponent is little H.", "start": 3124.09, "duration": 7.03}, {"text": "OK, so other properties are that\nthe densities between the Vi's", "start": 3131.12, "duration": 7.77}, {"text": "and the Wi's do not differ\nby more than epsilon over 2", "start": 3138.89, "duration": 10.02}, {"text": "for all but a small fraction--", "start": 3148.91, "duration": 4.79}, {"text": "so epsilon k squared over 2--", "start": 3153.7, "duration": 2.78}, {"text": "pairs.", "start": 3156.48, "duration": 0.5}, {"text": "And finally, the sizes of the\nWi's are at least delta 0 times", "start": 3165.15, "duration": 7.86}, {"text": "n where delta 0 depends\nonly on epsilon.", "start": 3173.01, "duration": 4.0}, {"text": "Epsilon and H.", "start": 3184.31, "duration": 3.29}, {"text": "This is the partition step,\nso now let's do the cleaning.", "start": 3201.21, "duration": 4.11}, {"text": "In the cleaning step,\nbasically we're not going to--", "start": 3208.21, "duration": 6.62}, {"text": "I mean, there is no longer an\nissue of irregular pairs if we", "start": 3214.83, "duration": 2.79}, {"text": "only look at the Wi's.", "start": 3217.62, "duration": 2.48}, {"text": "So we just need to think\nabout the low density pairs", "start": 3220.1, "duration": 3.46}, {"text": "or whatever the\ncorresponding analog is.", "start": 3223.56, "duration": 3.15}, {"text": "And what happens here is\nthat for every i less than j,", "start": 3226.71, "duration": 5.49}, {"text": "and crucially including\nwhen i equals to j,", "start": 3232.2, "duration": 5.59}, {"text": "if the edge densities\nbetween the W's is too small", "start": 3237.79, "duration": 8.54}, {"text": "then we remove all\nedges between Vi and Vj.", "start": 3246.33, "duration": 12.46}, {"text": "And if the edge density\nbetween the Wi's is too big,", "start": 3263.07, "duration": 8.74}, {"text": "then we remove all edges.", "start": 3271.81, "duration": 3.585}, {"text": "So we add all edges\nbetween Vi and Vj.", "start": 3278.28, "duration": 3.28}, {"text": "How many edges do we end\nup adding or removing?", "start": 3300.9, "duration": 2.07}, {"text": "So the total number of edges\nadded or removed from g is--", "start": 3306.56, "duration": 14.9}, {"text": "in this case, so if\nthe edges density", "start": 3321.46, "duration": 5.22}, {"text": "in g between the Vi's and\nVj's is also very small,", "start": 3326.68, "duration": 5.48}, {"text": "then you do not remove\nvery many edges.", "start": 3332.16, "duration": 3.95}, {"text": "But most pairs of Vi and\nVj have that property.", "start": 3336.11, "duration": 5.08}, {"text": "So you tidy up\nwhat kind of errors", "start": 3341.19, "duration": 2.46}, {"text": "you can get from here\nand there, and you", "start": 3343.65, "duration": 4.49}, {"text": "find that the total number of\nedges that are added or removed", "start": 3348.14, "duration": 3.75}, {"text": "from g is less than, let's\nsay, epsilon n squared.", "start": 3351.89, "duration": 7.26}, {"text": "Maybe even get an\nextra factor of 2,", "start": 3359.15, "duration": 1.68}, {"text": "but you know, upon changing\nsome constant factors,", "start": 3360.83, "duration": 3.48}, {"text": "it's less than\nepsilon n squared.", "start": 3364.31, "duration": 3.87}, {"text": "So this is some small\ndetails you can work out.", "start": 3368.18, "duration": 5.29}, {"text": "Here we're using--\nasking, how is", "start": 3373.47, "duration": 2.31}, {"text": "the density between Vi and\nVj related to Wi and Wj?", "start": 3375.78, "duration": 3.63}, {"text": "Well, for most pairs of i\nand j they're very similar.", "start": 3379.41, "duration": 4.13}, {"text": "And there's a small fraction\nof them that are not similar,", "start": 3383.54, "duration": 2.64}, {"text": "but then you lump everything\nin to this bound over here.", "start": 3386.18, "duration": 6.13}, {"text": "So maybe I need to--", "start": 3400.29, "duration": 2.922}, {"text": "let me just put a 2\nhere just to be safe.", "start": 3403.212, "duration": 1.708}, {"text": "All right.", "start": 3408.69, "duration": 2.09}, {"text": "So we deleted a very\nsmall number of edges,", "start": 3410.78, "duration": 4.81}, {"text": "and now we want to show\nthat the graph that", "start": 3415.59, "duration": 2.16}, {"text": "has resulted from\nthis modification", "start": 3417.75, "duration": 3.99}, {"text": "does not have any\ninduced H sub-graphs.", "start": 3421.74, "duration": 3.51}, {"text": "And the final step\nis the counting step.", "start": 3431.48, "duration": 3.63}, {"text": "So suppose there\nwere any induced", "start": 3435.11, "duration": 5.85}, {"text": "H left after the modification.", "start": 3440.96, "duration": 5.9}, {"text": "So I want to show that, in fact,\nthere must be a lot of H's--", "start": 3446.86, "duration": 3.16}, {"text": "induced H's originally\nin the graph,", "start": 3450.02, "duration": 2.14}, {"text": "thereby contradicting\nthe hypothesis.", "start": 3452.16, "duration": 2.176}, {"text": "So where does this\ninduced H sit?", "start": 3461.69, "duration": 3.52}, {"text": "Well, you have the V's,\nand inside the V's you have", "start": 3465.21, "duration": 9.86}, {"text": "the W's.", "start": 3475.07, "duration": 0.5}, {"text": "So suppose my H is that\ngraph for illustration.", "start": 3484.17, "duration": 9.03}, {"text": "And in particular,\nI have a non-edge.", "start": 3493.2, "duration": 3.57}, {"text": "So I have an edge, and\nI also have a non-edge.", "start": 3496.77, "duration": 3.6}, {"text": "So between these two,\nthat's the non-edge.", "start": 3500.37, "duration": 2.525}, {"text": "So suppose you find a copy\nof H in the cleaned-up graph.", "start": 3507.95, "duration": 6.64}, {"text": "Where can that cleaned up--", "start": 3514.59, "duration": 1.52}, {"text": "this copy of H sit?", "start": 3516.11, "duration": 1.83}, {"text": "Suppose you find it here.", "start": 3517.94, "duration": 1.85}, {"text": "The claim now is that if this\ncopy of H existed here, then", "start": 3523.44, "duration": 8.69}, {"text": "I must be able to find\nmany such copies of H", "start": 3532.13, "duration": 4.92}, {"text": "in the corresponding\nyellow parts.", "start": 3537.05, "duration": 2.04}, {"text": "Because between the yellow\nparts you have regularity,", "start": 3541.94, "duration": 8.11}, {"text": "and you also have the\nright kinds of densities.", "start": 3550.05, "duration": 5.4}, {"text": "Because if they didn't have\nthe right kind of density,", "start": 3555.45, "duration": 2.26}, {"text": "we would have cleaned\nit up already.", "start": 3557.71, "duration": 1.5}, {"text": "So that's the ideal.", "start": 3562.9, "duration": 3.1}, {"text": "If you had a copy\nof this H somewhere,", "start": 3566.0, "duration": 3.72}, {"text": "then I zoom into\nthe yellow parts,", "start": 3569.72, "duration": 2.1}, {"text": "zoom into these W's, and I find\nlots of copies of H in between", "start": 3571.82, "duration": 5.34}, {"text": "the W's.", "start": 3577.16, "duration": 2.27}, {"text": "So suppose-- let\nme write this down.", "start": 3579.43, "duration": 1.5}, {"text": "So suppose the little V's, so\nthe vertices, lies in the--", "start": 3580.93, "duration": 16.76}, {"text": "so I'm just indexing\nwhere a little v lies.", "start": 3597.69, "duration": 2.85}, {"text": "The little v lies\nin big V sub phi", "start": 3600.54, "duration": 2.685}, {"text": "V for some phi which since the\nvertices of H2 went through k.", "start": 3603.225, "duration": 11.375}, {"text": "So now we apply counting lemma\nto embed induced copies of H", "start": 3614.6, "duration": 20.05}, {"text": "in g where the vertex\nV in H is mapped", "start": 3634.65, "duration": 11.06}, {"text": "to a vertex in the\ncorresponding W.", "start": 3645.71, "duration": 8.745}, {"text": "And we would like to know that\nthere are lots of such copies.", "start": 3660.63, "duration": 4.81}, {"text": "And the counting Lemma--", "start": 3665.44, "duration": 1.22}, {"text": "or rather, some variant, but I\nshould read the counting lemma", "start": 3666.66, "duration": 5.07}, {"text": "that we did last time and view\nit as a multi-partite version.", "start": 3671.73, "duration": 5.21}, {"text": "Apply this so far part to part.", "start": 3676.94, "duration": 4.5}, {"text": "So we find that the number\nof such induced copies", "start": 3681.44, "duration": 8.9}, {"text": "is within a small error.", "start": 3690.34, "duration": 1.84}, {"text": "So that regularity parameter\nmultiplied by the number", "start": 3696.63, "duration": 11.07}, {"text": "of edges of H, which we\nalready canceled out,", "start": 3707.7, "duration": 3.99}, {"text": "multiplied by the\nproduct of these Wi's.", "start": 3711.69, "duration": 9.325}, {"text": "So it's within\nthis error of what", "start": 3724.49, "duration": 4.17}, {"text": "you would suspect if you\nnaively multiply the edge", "start": 3728.66, "duration": 4.59}, {"text": "densities together along\nwith the vertex densities.", "start": 3733.25, "duration": 3.703}, {"text": "So these factors are for the\nedges that you want to embed,", "start": 3749.28, "duration": 6.51}, {"text": "and then I also need to\nmultiply the densities", "start": 3755.79, "duration": 3.67}, {"text": "for the long edges.", "start": 3759.46, "duration": 1.05}, {"text": "So 1 minus these edge densities.", "start": 3771.378, "duration": 3.164}, {"text": "So one way you can think\nof it is just consider", "start": 3774.542, "duration": 1.958}, {"text": "the complement in g.", "start": 3776.5, "duration": 2.01}, {"text": "So consider the complement of\ng to get this version here.", "start": 3778.51, "duration": 3.99}, {"text": "And then finally, the product\nof the vertex set sizes.", "start": 3782.5, "duration": 3.74}, {"text": "And the point is that this\nis not a small number.", "start": 3798.0, "duration": 4.5}, {"text": "So hence the number of\ninduced copies of H in g", "start": 3802.5, "duration": 13.37}, {"text": "is at least on the order of--", "start": 3815.87, "duration": 5.58}, {"text": "well, OK?", "start": 3821.45, "duration": 0.92}, {"text": "So it's at least some\nnumber, which is basically", "start": 3824.91, "duration": 5.68}, {"text": "this guy over here.", "start": 3830.59, "duration": 1.29}, {"text": "So epsilon over 4 raised to--", "start": 3831.88, "duration": 3.94}, {"text": "all of these are constants,\nso that's the point.", "start": 3835.82, "duration": 2.0}, {"text": "All of these guys are\nconstants, minus--", "start": 3837.82, "duration": 1.92}, {"text": "so here is the main term,\nand then the error term.", "start": 3845.05, "duration": 3.053}, {"text": "And then the product of\nthese vertex set sizes,", "start": 3853.79, "duration": 3.42}, {"text": "and we saw that each vertex\nset is not too small.", "start": 3857.21, "duration": 2.47}, {"text": "So you have lots of\ninduced copies of H in g.", "start": 3865.84, "duration": 4.195}, {"text": "Yep?", "start": 3870.035, "duration": 1.395}, {"text": "AUDIENCE: How do you\ndo in the case where", "start": 3871.43, "duration": 3.17}, {"text": "the density between [INAUDIBLE]", "start": 3874.6, "duration": 10.14}, {"text": "YUFEI ZHAO: OK, so can\nyou repeat your question?", "start": 3884.74, "duration": 2.62}, {"text": "AUDIENCE: How are you\ndealing with the [INAUDIBLE]", "start": 3887.36, "duration": 5.685}, {"text": "YUFEI ZHAO: OK.", "start": 3893.045, "duration": 0.625}, {"text": "So question, how do we deal\nwith the all but epsilon", "start": 3893.67, "duration": 2.19}, {"text": "over two pairs?", "start": 3895.86, "duration": 1.22}, {"text": "So that comes up in\nthe cleaning step", "start": 3897.08, "duration": 2.295}, {"text": "in what I wrote\nin red in dealing", "start": 3899.375, "duration": 2.385}, {"text": "with the number of total edges\nthat are added or removed.", "start": 3901.76, "duration": 6.02}, {"text": "So think about how many\nedges are added or removed.", "start": 3907.78, "duration": 2.55}, {"text": "In these non-exceptional pairs,\nthe number of edges that are", "start": 3910.33, "duration": 5.11}, {"text": "added or removed--", "start": 3915.44, "duration": 0.87}, {"text": "let's just think\nabout added edges.", "start": 3926.47, "duration": 2.2}, {"text": "So if the density of V is\ncontrolled by that of W,", "start": 3928.67, "duration": 17.26}, {"text": "then the number of edges added--", "start": 3945.93, "duration": 2.98}, {"text": "or removed, in that case--", "start": 3948.91, "duration": 1.82}, {"text": "from all such pairs along with--", "start": 3950.73, "duration": 5.5}, {"text": "yeah.", "start": 3956.23, "duration": 0.5}, {"text": "So you have epsilon n\nsquared edges changed.", "start": 3956.73, "duration": 4.68}, {"text": "On the other hand, if this is\nnot true then you only have", "start": 3966.54, "duration": 11.24}, {"text": "epsilon k squared such pairs ij\nfor which this cannot be true.", "start": 3977.78, "duration": 5.22}, {"text": "So you also only have at\nmost epsilon n squared edges", "start": 3983.0, "duration": 3.38}, {"text": "added or removed in such cases.", "start": 3986.38, "duration": 3.47}, {"text": "That answers your question?", "start": 3989.85, "duration": 2.792}, {"text": "Yes?", "start": 3992.642, "duration": 1.265}, {"text": "AUDIENCE: Is that number 0?", "start": 3993.907, "duration": 1.125}, {"text": "YUFEI ZHAO: Is which number 0?", "start": 3997.755, "duration": 1.869}, {"text": "AUDIENCE: The number of induced\nedges for the [INAUDIBLE]", "start": 3999.624, "duration": 5.696}, {"text": "YUFEI ZHAO: The--", "start": 4005.32, "duration": 1.2}, {"text": "AUDIENCE: Yeah, the top board.", "start": 4006.52, "duration": 1.431}, {"text": "YUFEI ZHAO: Top board?", "start": 4007.951, "duration": 0.917}, {"text": "Good.", "start": 4018.84, "duration": 0.56}, {"text": "So asking about this number.", "start": 4019.4, "duration": 2.295}, {"text": "So that should have been 2.", "start": 4021.695, "duration": 1.125}, {"text": "Yes?", "start": 4028.58, "duration": 1.44}, {"text": "AUDIENCE: I don't\nsee k anywhere.", "start": 4030.02, "duration": 2.153}, {"text": "YUFEI ZHAO: OK, so question, you\ndon't see k appearing anywhere.", "start": 4032.173, "duration": 2.667}, {"text": "So the k in the\ncorollary, do you mean?", "start": 4034.84, "duration": 2.053}, {"text": "AUDIENCE: Yeah.", "start": 4036.893, "duration": 0.927}, {"text": "YUFEI ZHAO: So that\nhasn't come up yet.", "start": 4037.82, "duration": 1.71}, {"text": "So it comes up implicitly\nbecause we need to lower bound", "start": 4039.53, "duration": 4.65}, {"text": "the sizes of these W's.", "start": 4044.18, "duration": 2.535}, {"text": "So this is partly why we need\na bound on the number of parts,", "start": 4051.82, "duration": 3.06}, {"text": "but it is true that we do\nnot need epsilon k to depend", "start": 4054.88, "duration": 3.27}, {"text": "on k in this application yet.", "start": 4058.15, "duration": 1.71}, {"text": "I will mention a different\napplication in the second", "start": 4059.86, "duration": 2.28}, {"text": "where you do need that k.", "start": 4062.14, "duration": 1.09}, {"text": "OK, so the number of induced H\nin g is at least this amount.", "start": 4068.81, "duration": 4.11}, {"text": "And that's a small lie.", "start": 4072.92, "duration": 1.16}, {"text": "You need to maybe consider this\nis the number of homomorphic.", "start": 4074.08, "duration": 5.7}, {"text": "Well, actually, no, we're OK.", "start": 4079.78, "duration": 1.95}, {"text": "Never mind.", "start": 4081.73, "duration": 0.784}, {"text": "So you can set delta to\nbe this quantity here,", "start": 4091.12, "duration": 8.489}, {"text": "and then that\nfinishes the proof.", "start": 4099.609, "duration": 1.601}, {"text": "So you have lots of\ninduced copies of H", "start": 4101.21, "duration": 2.29}, {"text": "in your graph which\ncontradicts the hypothesis.", "start": 4103.5, "duration": 4.265}, {"text": "So that finishes the proof\nof the induced removal lemma,", "start": 4107.765, "duration": 2.835}, {"text": "and basically the proof is\nthe same as the usual graph", "start": 4110.6, "duration": 3.509}, {"text": "removal lemma except\nthat now we need", "start": 4114.109, "duration": 2.401}, {"text": "some strengthened\nregularity lemma which", "start": 4116.51, "duration": 3.75}, {"text": "allows us to get rid\nof irregular parts", "start": 4120.26, "duration": 3.03}, {"text": "but in a more\nrestricted setting.", "start": 4123.29, "duration": 1.6}, {"text": "Because we saw you cannot\ncompletely get rid of irregular", "start": 4124.89, "duration": 2.839}, {"text": "parts.", "start": 4127.729, "duration": 0.5}, {"text": "Any questions?", "start": 4131.72, "duration": 0.78}, {"text": "Yes?", "start": 4136.109, "duration": 0.74}, {"text": "AUDIENCE: [INAUDIBLE]", "start": 4136.849, "duration": 4.624}, {"text": "YUFEI ZHAO: So I want to\naddress the question of why", "start": 4141.473, "duration": 2.167}, {"text": "did I state this\ncorollary in this more", "start": 4143.64, "duration": 2.31}, {"text": "general form of a decreasing\nsequence of epsilons?", "start": 4145.95, "duration": 3.57}, {"text": "So first of all, with\nstrong regularity lemmas,", "start": 4149.52, "duration": 2.25}, {"text": "the strength is sometimes\nalways nice to--", "start": 4151.77, "duration": 3.419}, {"text": "it's always nice to state\nit with this extra strength.", "start": 4155.189, "duration": 2.25}, {"text": "Because it's the\nright way to think", "start": 4157.439, "duration": 2.641}, {"text": "about these types of theorems.", "start": 4160.08, "duration": 2.69}, {"text": "That the regularity\non the parts depends--", "start": 4162.77, "duration": 2.56}, {"text": "you can make it depend\non the number of parts", "start": 4165.33, "duration": 3.449}, {"text": "so that you get much stronger\ncontrol on the regularity.", "start": 4168.779, "duration": 3.391}, {"text": "But there are also\nsome applications.", "start": 4172.17, "duration": 1.57}, {"text": "For example, whether\nI will state next,", "start": 4173.74, "duration": 3.23}, {"text": "an application where you do\nneed that kind of strength.", "start": 4176.97, "duration": 3.24}, {"text": "So here's what's known as\nthe infinite removal lemma.", "start": 4180.21, "duration": 3.689}, {"text": "Here we have not\njust a single pattern", "start": 4187.26, "duration": 2.429}, {"text": "or a finite number of patterns\nwe want to get rid of.", "start": 4189.689, "duration": 2.971}, {"text": "For now we have\ninfinitely many patterns.", "start": 4192.66, "duration": 2.67}, {"text": "So for every curly H, which\nis a possibly infinite set", "start": 4195.33, "duration": 13.55}, {"text": "of graphs.", "start": 4208.88, "duration": 2.16}, {"text": "The graphs themselves\nare always finite,", "start": 4211.04, "duration": 2.05}, {"text": "but this may be\nan infinite list.", "start": 4213.09, "duration": 2.39}, {"text": "And an epsilon parameter.", "start": 4215.48, "duration": 4.35}, {"text": "There exists an H0 and a\ndelta positive parameter", "start": 4219.83, "duration": 6.52}, {"text": "such that every n vertex\ngraph with at most delta--", "start": 4226.35, "duration": 11.88}, {"text": "so less than delta--", "start": 4238.23, "duration": 2.95}, {"text": "V to the H induced\ncopies of H for every H", "start": 4241.18, "duration": 11.4}, {"text": "in this family with\nfewer than H0 vertices.", "start": 4252.58, "duration": 7.625}, {"text": "So every graph\nwith this property", "start": 4263.67, "duration": 4.0}, {"text": "can be made curly H free.", "start": 4267.67, "duration": 7.24}, {"text": "So it means free of--", "start": 4274.91, "duration": 2.67}, {"text": "induced curly H free by\nadding or removing fewer", "start": 4277.58, "duration": 14.81}, {"text": "than epsilon n squared edges.", "start": 4292.39, "duration": 1.99}, {"text": "So now instead of\na single pattern", "start": 4298.23, "duration": 1.43}, {"text": "you have a possibly infinite\nset of induced patterns and a", "start": 4299.66, "duration": 3.71}, {"text": "want to make your\ngraph curly H free--", "start": 4303.37, "duration": 6.33}, {"text": "induced curly H free.", "start": 4309.7, "duration": 2.23}, {"text": "And the theorem is\nthat if there exists", "start": 4311.93, "duration": 3.98}, {"text": "some finite bound, H0, such\nthat if you have few copies--", "start": 4315.91, "duration": 7.41}, {"text": "so for all the patterns\nup to that point--", "start": 4323.32, "duration": 3.14}, {"text": "then you can do\nwhat you need to do.", "start": 4326.46, "duration": 1.59}, {"text": "So take some time to even\ndigest this statement,", "start": 4331.05, "duration": 2.34}, {"text": "but it's somehow infinite\nversions-- the correct infinite", "start": 4333.39, "duration": 2.61}, {"text": "version of the\nremoval lemma if you", "start": 4336.0, "duration": 2.22}, {"text": "have infinitely many patterns\nthat you need to remove.", "start": 4338.22, "duration": 3.127}, {"text": "And I claim that the\nproof is actually", "start": 4341.347, "duration": 1.583}, {"text": "more or less the same proof\nas the one that we did here,", "start": 4342.93, "duration": 2.71}, {"text": "except now you need\nto take your epsilon", "start": 4345.64, "duration": 2.12}, {"text": "case, as in this\ncorollary, to depend on k.", "start": 4347.76, "duration": 4.14}, {"text": "You need to in some way look\nahead in this infinite pattern.", "start": 4351.9, "duration": 4.77}, {"text": "So here in proof, this epsilon\nk from corollary depends on k.", "start": 4356.67, "duration": 13.49}, {"text": "And also it depends on\nyour family of patterns H.", "start": 4370.16, "duration": 12.63}, {"text": "Finally, I want to\nmention a perspective--", "start": 4382.79, "duration": 2.55}, {"text": "a computer science\nperspective on these removal", "start": 4385.34, "duration": 3.682}, {"text": "lemmas that we've been\ndiscussing so far.", "start": 4389.022, "duration": 1.708}, {"text": "And that's in the\ncontext of something", "start": 4394.75, "duration": 1.76}, {"text": "called property testing.", "start": 4396.51, "duration": 1.08}, {"text": "And basically, we would\nlike an efficient--", "start": 4417.83, "duration": 5.52}, {"text": "efficient meaning fast--\nrandomized algorithm", "start": 4423.35, "duration": 8.55}, {"text": "to distinguish graphs that\nare triangle-free from those", "start": 4431.9, "duration": 19.92}, {"text": "that are epsilon far\nfrom triangle-free.", "start": 4451.82, "duration": 3.927}, {"text": "Where being epsilon far\nfrom triangle-free means", "start": 4459.33, "duration": 3.04}, {"text": "that you need to change more\nthan epsilon n squared edges", "start": 4462.37, "duration": 10.19}, {"text": "here. n is, as usual, the number\nof vertices to make the graph", "start": 4472.56, "duration": 12.75}, {"text": "triangle-free.", "start": 4485.31, "duration": 0.63}, {"text": "So the distance, the\n[INAUDIBLE] distance", "start": 4485.94, "duration": 2.1}, {"text": "is more than epsilon away\nfrom being triangle-free.", "start": 4488.04, "duration": 4.71}, {"text": "So somebody gives you\na very large graphing.", "start": 4492.75, "duration": 2.7}, {"text": "n is very large.", "start": 4495.45, "duration": 1.38}, {"text": "You cannot search through\nevery triple vertices.", "start": 4496.83, "duration": 3.57}, {"text": "That's too expensive.", "start": 4500.4, "duration": 1.2}, {"text": "But you want some way to test\nif a graph is triangle-free", "start": 4501.6, "duration": 4.68}, {"text": "versus very far away\nfrom being triangle-free.", "start": 4506.28, "duration": 3.271}, {"text": "So there's a very simple\nrandomized algorithm", "start": 4514.27, "duration": 2.4}, {"text": "to do this, which is\nto just try randomly", "start": 4516.67, "duration": 7.33}, {"text": "sample a random\ntriple of vertices", "start": 4524.0, "duration": 6.85}, {"text": "and check if it's a triangle.", "start": 4530.85, "duration": 2.24}, {"text": "So you do this.", "start": 4541.86, "duration": 1.85}, {"text": "And just to make our\nlife a bit more secure,", "start": 4543.71, "duration": 5.62}, {"text": "let's try it some\nlarger number of times.", "start": 4549.33, "duration": 3.99}, {"text": "So some c of epsilon some\nconstant number of times.", "start": 4553.32, "duration": 5.84}, {"text": "And if you find a triangle--", "start": 4559.16, "duration": 3.73}, {"text": "so if you don't find\na triangle, then we", "start": 4562.89, "duration": 5.88}, {"text": "return that it's triangle-free.", "start": 4568.77, "duration": 5.314}, {"text": "Otherwise we return that it is\nepsilon far from triangle-free.", "start": 4578.35, "duration": 5.094}, {"text": "So that's the algorithm.", "start": 4591.98, "duration": 1.316}, {"text": "So it's a very\nintuitive algorithm,", "start": 4596.56, "duration": 2.91}, {"text": "but why does it work?", "start": 4599.47, "duration": 2.71}, {"text": "So we want to know that,\nindeed, somebody gives you", "start": 4602.18, "duration": 2.87}, {"text": "one of these two possibilities.", "start": 4605.05, "duration": 1.32}, {"text": "You run that algorithm, you can\nsucceed with high probability.", "start": 4606.37, "duration": 3.97}, {"text": "Question?", "start": 4610.34, "duration": 1.204}, {"text": "AUDIENCE: [INAUDIBLE]", "start": 4611.544, "duration": 2.836}, {"text": "YUFEI ZHAO: So let's talk\nabout why this works.", "start": 4614.38, "duration": 4.12}, {"text": "So theorem, for\nevery epsilon, there", "start": 4618.5, "duration": 3.84}, {"text": "exists a c such that\nalgorithm succeeds", "start": 4622.34, "duration": 5.984}, {"text": "with probability bigger than\n2/3, and 2/3 can be any number.", "start": 4628.324, "duration": 9.436}, {"text": "So any number that you\nlike because you can always", "start": 4637.76, "duration": 2.24}, {"text": "repeat it to boost that\nconstant probability.", "start": 4640.0, "duration": 2.901}, {"text": "So there are two cases.", "start": 4646.2, "duration": 2.12}, {"text": "If g is triangle-free,\nthen it always succeeds.", "start": 4648.32, "duration": 6.75}, {"text": "You'll never find\nthis triangle, and it", "start": 4655.07, "duration": 1.65}, {"text": "would return triangle-free.", "start": 4656.72, "duration": 1.715}, {"text": "On the other hand, if g is\nepsilon far from triangle-free,", "start": 4664.26, "duration": 11.08}, {"text": "then triangle removal\nlemma tells us", "start": 4675.34, "duration": 4.89}, {"text": "that g has lots of triangles.", "start": 4680.23, "duration": 3.683}, {"text": "Delta n cubed triangles.", "start": 4687.23, "duration": 1.62}, {"text": "So if we sample c being, let's\nsay, 1 over delta times--", "start": 4692.1, "duration": 11.61}, {"text": "delta here is a function of\nepsilon from the triangle", "start": 4703.71, "duration": 3.06}, {"text": "removal lemma.", "start": 4706.77, "duration": 1.87}, {"text": "So we find that the probability\nthat the algorithm fails", "start": 4708.64, "duration": 6.32}, {"text": "is at most--", "start": 4714.96, "duration": 1.83}, {"text": "so you have a lot of triangles.", "start": 4731.71, "duration": 2.11}, {"text": "So very likely you will\nhit one of these triangles.", "start": 4733.82, "duration": 2.76}, {"text": "So the probability that the\nalgorithm fails is at most 1", "start": 4736.58, "duration": 3.44}, {"text": "minus delta n cubed divided\nby total number of triples", "start": 4740.02, "duration": 5.76}, {"text": "raised to 1 over delta.", "start": 4745.78, "duration": 2.46}, {"text": "And this is 1 minus at\nmost 1 minus 6 delta raised", "start": 4748.24, "duration": 4.85}, {"text": "to 1 over delta, and it's\nat most e to the minus 6.", "start": 4753.09, "duration": 4.81}, {"text": "So less than 1/3 in particular.", "start": 4757.9, "duration": 3.99}, {"text": "So this algorithm succeeds\nwith high probability.", "start": 4761.89, "duration": 3.15}, {"text": "Now, how big of a c do you need?", "start": 4765.04, "duration": 1.81}, {"text": "Well, that depends on the\ntriangle removal lemma.", "start": 4766.85, "duration": 3.24}, {"text": "So it's a constant.", "start": 4770.09, "duration": 2.2}, {"text": "So it's a constant,\ndoes not depend", "start": 4772.29, "duration": 2.12}, {"text": "on the size of the graph.", "start": 4774.41, "duration": 3.11}, {"text": "But it's a large\nconstant, because we", "start": 4777.52, "duration": 1.84}, {"text": "saw in the proof\nof regularity lemma", "start": 4779.36, "duration": 2.2}, {"text": "that it can be very large.", "start": 4781.56, "duration": 1.13}, {"text": "But you know, this\ntheorem here is basically", "start": 4786.8, "duration": 2.7}, {"text": "the same as a triangle\nremoval lemma.", "start": 4789.5, "duration": 3.73}, {"text": "So it's highly\nnon-trivial if it's true.", "start": 4793.23, "duration": 2.4}, {"text": "Even though the algorithm is\nextremely naive and simple.", "start": 4795.63, "duration": 3.84}, {"text": "I just want to finish\noff with one more thing.", "start": 4799.47, "duration": 1.95}, {"text": "Instead of testing\nfor triangle-freeness,", "start": 4801.42, "duration": 1.8}, {"text": "you can ask what other\nproperties can you test?", "start": 4803.22, "duration": 2.88}, {"text": "So which graph\nproperties are testable", "start": 4806.1, "duration": 6.49}, {"text": "in default in that sense?", "start": 4812.59, "duration": 1.18}, {"text": "So distinguishing\nsomething which", "start": 4816.95, "duration": 2.09}, {"text": "has the property, so P versus\nepsilon far from this property", "start": 4819.04, "duration": 8.03}, {"text": "P.", "start": 4827.07, "duration": 5.05}, {"text": "And you have this\ntester which is you", "start": 4832.12, "duration": 1.94}, {"text": "sample some number of vertices.", "start": 4834.06, "duration": 2.96}, {"text": "So this is called\nthe oblivious tester.", "start": 4837.02, "duration": 1.78}, {"text": "So you sample k\nvertices, and you try", "start": 4842.12, "duration": 6.64}, {"text": "to see if it has that property.", "start": 4848.76, "duration": 3.95}, {"text": "So there's a class of\nproperties called hereditary.", "start": 4852.71, "duration": 3.927}, {"text": "So hereditary properties\nare properties", "start": 4860.05, "duration": 2.51}, {"text": "that are closed under\nvertex deletion.", "start": 4862.56, "duration": 3.15}, {"text": "And these properties are--", "start": 4871.32, "duration": 2.41}, {"text": "lots of properties that you're\nseeing are of this form.", "start": 4873.73, "duration": 2.93}, {"text": "So for example, being H3 is this\nform being planar so this one", "start": 4876.66, "duration": 8.12}, {"text": "being induced H3, so this\none being three-colorable,", "start": 4884.78, "duration": 6.926}, {"text": "being perfect,\nthey're all examples", "start": 4891.706, "duration": 2.244}, {"text": "of hereditary properties.", "start": 4893.95, "duration": 1.65}, {"text": "Properties that if your\ngraph is three-colorable,", "start": 4895.6, "duration": 2.61}, {"text": "you take out some vertices,\nit's still three-colorable.", "start": 4898.21, "duration": 3.48}, {"text": "And all the\ndiscussions that we've", "start": 4901.69, "duration": 2.43}, {"text": "done so far, in particular\nthe infinite removal lemma.", "start": 4904.12, "duration": 3.84}, {"text": "If you phrase it in the form\nof property testing given", "start": 4907.96, "duration": 4.05}, {"text": "the above discussion, it implies\nthat every hereditary property", "start": 4912.01, "duration": 11.05}, {"text": "is testable.", "start": 4923.06, "duration": 0.57}, {"text": "In fact, it's testable\nin the above sense", "start": 4926.86, "duration": 4.11}, {"text": "with a one-sided error\nusing an oblivious tester.", "start": 4930.97, "duration": 5.14}, {"text": "One-sided error means that up\nthere if it's triangle-free,", "start": 4936.11, "duration": 3.72}, {"text": "then it always succeeds.", "start": 4939.83, "duration": 1.43}, {"text": "So here one of the cases\nthat always succeeds.", "start": 4941.26, "duration": 4.85}, {"text": "And the reason is that\nyou can characterize", "start": 4946.11, "duration": 2.04}, {"text": "a hereditary property\nby a curly H induced H3", "start": 4948.15, "duration": 9.2}, {"text": "for some curly H. Namely,\nyou're putting everything", "start": 4957.35, "duration": 4.44}, {"text": "into H that do not\nhave this property.", "start": 4961.79, "duration": 4.01}, {"text": "This is a possibly\ninfinite set of graphs,", "start": 4973.97, "duration": 4.61}, {"text": "and that completely\ncharacterizes", "start": 4978.58, "duration": 1.92}, {"text": "this hereditary property.", "start": 4980.5, "duration": 2.2}, {"text": "And if you read out the\ninfinite removal lemma,", "start": 4982.7, "duration": 2.76}, {"text": "it says precisely, using\nabove this interpretation,", "start": 4985.46, "duration": 4.49}, {"text": "that you have a property\ntesting algorithm.", "start": 4989.95, "duration": 4.4}]

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+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 2.43}, {"text": "[RUSTLING]", "start": 2.43, "duration": 1.944}, {"text": "[CLICKING]", "start": 4.374, "duration": 1.458}, {"text": "DAVID HSU: My name is David Hsu.", "start": 10.197, "duration": 1.333}, {"text": "Welcome to another installment\nof my lecture series", "start": 11.53, "duration": 2.46}, {"text": "on urban energy\nsystems and policy.", "start": 13.99, "duration": 2.55}, {"text": "This is a class taught by the\nDepartment of Urban Studies", "start": 16.54, "duration": 2.43}, {"text": "and Planning at MIT.", "start": 18.97, "duration": 2.023}, {"text": "And what we're going\nto talk about today", "start": 20.993, "duration": 1.667}, {"text": "is the next installment of\ntalking about renewables", "start": 22.66, "duration": 3.48}, {"text": "and renewable energy.", "start": 26.14, "duration": 1.54}, {"text": "We're going to talk\nabout solar today.", "start": 27.68, "duration": 1.64}, {"text": "And this, again, is a\nfundamental building block", "start": 29.32, "duration": 2.64}, {"text": "for how we are going\nto decarbonize cities.", "start": 31.96, "duration": 3.39}, {"text": "The readings for today\nare on the syllabus.", "start": 35.35, "duration": 2.02}, {"text": "If you have the PDF\nhard copies, you", "start": 37.37, "duration": 1.58}, {"text": "can click through to the\nreadings in the pink links", "start": 38.95, "duration": 2.91}, {"text": "here on this page.", "start": 41.86, "duration": 2.7}, {"text": "I'll just recap what I\nsaid in the last lecture.", "start": 44.56, "duration": 2.91}, {"text": "You have a renewable toolbox.", "start": 47.47, "duration": 2.19}, {"text": "The exciting thing is\nthat our building blocks,", "start": 49.66, "duration": 2.34}, {"text": "like solar, wind, storage,\ngeothermal, electrolysis,", "start": 52.0, "duration": 3.93}, {"text": "are all becoming\ncheaper quickly.", "start": 55.93, "duration": 2.19}, {"text": "They're all cleaner\ntechnologies.", "start": 58.12, "duration": 1.71}, {"text": "But they are fundamentally\ndifferent technologies", "start": 59.83, "duration": 2.43}, {"text": "than the fossil fuel\nsystem that we've", "start": 62.26, "duration": 1.74}, {"text": "built our civilization on.", "start": 64.0, "duration": 2.83}, {"text": "So we need to build about 47\ntimes more solar, about 28", "start": 66.83, "duration": 3.8}, {"text": "times more wind than we've\nbuilt in the last 40 years,", "start": 70.63, "duration": 3.27}, {"text": "to basically provide enough\nenergy to decarbonize", "start": 73.9, "duration": 3.03}, {"text": "our energy system.", "start": 76.93, "duration": 1.68}, {"text": "That gives you a very\nlengthy to do list,", "start": 78.61, "duration": 2.58}, {"text": "but an exciting to do\nlist for your careers.", "start": 81.19, "duration": 2.7}, {"text": "Your to do list includes\nfinancing, generation,", "start": 83.89, "duration": 2.7}, {"text": "transmission, distributing\npower, balancing power,", "start": 86.59, "duration": 2.71}, {"text": "making sure that\npower is reliable,", "start": 89.3, "duration": 1.52}, {"text": "making sure that the energy\nsystems are resilient,", "start": 90.82, "duration": 2.13}, {"text": "and siting these\nenergy resources.", "start": 92.95, "duration": 3.15}, {"text": "Last time we talked\nabout wind basics.", "start": 96.1, "duration": 2.26}, {"text": "We talked about capacity\nfactors as a key concept", "start": 98.36, "duration": 2.93}, {"text": "to understand intermittency.", "start": 101.29, "duration": 2.805}, {"text": "Today we're going to\ntalk about solar basics.", "start": 104.095, "duration": 1.875}, {"text": "And we're going to\nuse solar technologies", "start": 105.97, "duration": 1.708}, {"text": "as an example of adoption\ncosts, or learning curves,", "start": 107.678, "duration": 3.152}, {"text": "and siting issues.", "start": 110.83, "duration": 1.5}, {"text": "And the next lecture, we'll talk\nabout storage and geothermal.", "start": 112.33, "duration": 3.06}, {"text": "Those are technologies that\nare developing new niches", "start": 115.39, "duration": 2.46}, {"text": "in the energy system, and may be\ncritical building blocks going", "start": 117.85, "duration": 3.96}, {"text": "forward, but haven't\nquite developed", "start": 121.81, "duration": 1.92}, {"text": "into the same kind of\ncompetitive technology", "start": 123.73, "duration": 4.559}, {"text": "that solar and wind have become.", "start": 128.289, "duration": 2.5}, {"text": "So just to review\nbasically, here's", "start": 130.789, "duration": 2.371}, {"text": "a diagram from MacKay's book.", "start": 133.16, "duration": 1.77}, {"text": "This is a solar, basically\nconverts incident", "start": 134.93, "duration": 3.03}, {"text": "light on the Earth into energy.", "start": 137.96, "duration": 2.25}, {"text": "Of course, you have\nto capture the portion", "start": 140.21, "duration": 3.06}, {"text": "of the electromagnetic\nenergy in the ray.", "start": 143.27, "duration": 3.04}, {"text": "And so this diagram simply\nshows that at the equator,", "start": 146.31, "duration": 2.81}, {"text": "you capture the full amount of\nthe energy landing in Nairobi", "start": 149.12, "duration": 4.2}, {"text": "with a horizontally-mounted\nground panel,", "start": 153.32, "duration": 2.88}, {"text": "a panel simply lying\nflat on the ground.", "start": 156.2, "duration": 2.55}, {"text": "Whereas at 52 degrees latitude,\nCambridge, United Kingdom,", "start": 158.75, "duration": 4.59}, {"text": "or Cambridge,\nMassachusetts, are the same,", "start": 163.34, "duration": 2.16}, {"text": "you actually only capture\nabout 60% of the energy", "start": 165.5, "duration": 3.81}, {"text": "because a 52 degree angle\ndoesn't capture the full ray", "start": 169.31, "duration": 3.66}, {"text": "energy of the\nelectromagnetic energy,", "start": 172.97, "duration": 3.06}, {"text": "or the sunlight\nfalling on the Earth.", "start": 176.03, "duration": 2.37}, {"text": "Helpfully, however, as\nthis last line points out,", "start": 178.4, "duration": 3.0}, {"text": "52 degrees is about the\npitch of a roof angle.", "start": 181.4, "duration": 3.0}, {"text": "So if you lay solar panels\nflat on a roof in Cambridge,", "start": 184.4, "duration": 3.88}, {"text": "Massachusetts, and\nthose are pointed", "start": 188.28, "duration": 2.24}, {"text": "in the direction of the sun,\npredominantly South, coming", "start": 190.52, "duration": 3.09}, {"text": "from the South in the\nnorthern hemisphere,", "start": 193.61, "duration": 1.8}, {"text": "then you can capture the full\namount of the solar energy", "start": 195.41, "duration": 3.24}, {"text": "falling on the roof.", "start": 198.65, "duration": 2.49}, {"text": "This is why we have different\nmaps for solar resources.", "start": 201.14, "duration": 3.52}, {"text": "This is a map of the global\nhorizontal irradiation.", "start": 204.66, "duration": 3.293}, {"text": "This is the amount of\nenergy you would capture", "start": 207.953, "duration": 1.917}, {"text": "if you laid a solar panel\nsimply down on the ground flat", "start": 209.87, "duration": 3.51}, {"text": "facing up at the sky.", "start": 213.38, "duration": 1.92}, {"text": "As you can see,\naround the equator,", "start": 215.3, "duration": 2.34}, {"text": "there are relatively\nhigh amounts", "start": 217.64, "duration": 2.01}, {"text": "of global horizontal radiation.", "start": 219.65, "duration": 2.13}, {"text": "And, of course, slightly\noff the equator,", "start": 221.78, "duration": 3.15}, {"text": "you also get a lot of\nglobal horizontal radiation", "start": 224.93, "duration": 3.75}, {"text": "probably due to climate.", "start": 228.68, "duration": 1.32}, {"text": "This map probably incorporates\nnot only climate, but also", "start": 230.0, "duration": 4.29}, {"text": "the level of radiation that's\nmeasured in these places.", "start": 234.29, "duration": 4.23}, {"text": "For the direct,\nnormal irradiation,", "start": 238.52, "duration": 2.13}, {"text": "this is how much\nenergy you'd capture", "start": 240.65, "duration": 2.37}, {"text": "if you laid a solar panel\nat the precise angle", "start": 243.02, "duration": 3.69}, {"text": "to capture the maximum\namount of irradiation.", "start": 246.71, "duration": 3.66}, {"text": "And you can see that it's\na much more balanced view.", "start": 250.37, "duration": 2.65}, {"text": "This probably includes\nclimate, probably includes", "start": 253.02, "duration": 2.93}, {"text": "weather conditions,\nbut actually is based", "start": 255.95, "duration": 2.67}, {"text": "on empirical measurements.", "start": 258.62, "duration": 1.11}, {"text": "And you can see that\nthere, solar is actually", "start": 259.73, "duration": 3.0}, {"text": "a resource that's spread\nfairly well around the world,", "start": 262.73, "duration": 3.22}, {"text": "especially closer\nto the equator.", "start": 265.95, "duration": 2.9}, {"text": "The northern, southern\nhemispheres also", "start": 268.85, "duration": 1.71}, {"text": "have abundant solar potential.", "start": 270.56, "duration": 3.68}, {"text": "So if you look at the total\nphotovoltaic power potential,", "start": 274.24, "duration": 3.17}, {"text": "again, a good\nmessage from this map", "start": 277.41, "duration": 2.79}, {"text": "is that photovoltaic power is\nevenly spread across the world.", "start": 280.2, "duration": 4.68}, {"text": "It can be accessed\nin many countries.", "start": 284.88, "duration": 2.67}, {"text": "Quite importantly, it can be\naccessed in parts of countries,", "start": 287.55, "duration": 2.79}, {"text": "depending on climate, depending\non incident solar radiation.", "start": 290.34, "duration": 5.35}, {"text": "And, of course, we can also\nuse solar tracking devices", "start": 295.69, "duration": 3.51}, {"text": "because the sun\ntends to come low", "start": 299.2, "duration": 2.52}, {"text": "from the south in the\nnorthern hemisphere,", "start": 301.72, "duration": 2.85}, {"text": "you might have a\nhouse that's not", "start": 304.57, "duration": 3.93}, {"text": "pointed in the right direction.", "start": 308.5, "duration": 1.31}, {"text": "It may not be pointed East West.", "start": 309.81, "duration": 2.53}, {"text": "You may want a rooftop facing\nto the South where the sun is.", "start": 312.34, "duration": 4.05}, {"text": "As the sun comes over\nat different portions", "start": 316.39, "duration": 2.61}, {"text": "of the year-- it's higher in\nthe sky in the summer and lower", "start": 319.0, "duration": 3.21}, {"text": "in the sky in the winter--", "start": 322.21, "duration": 1.45}, {"text": "you may want a\nsolar collector that", "start": 323.66, "duration": 1.73}, {"text": "actually has different\nangles, angles", "start": 325.39, "duration": 1.86}, {"text": "that can tilt to capture\nthis seasonal variation", "start": 327.25, "duration": 2.61}, {"text": "between summer and winter, and\nmay even tilt as the sun moves", "start": 329.86, "duration": 4.29}, {"text": "throughout the sky.", "start": 334.15, "duration": 1.9}, {"text": "So that's a two axis\nsolar tracking panel.", "start": 336.05, "duration": 3.74}, {"text": "Another technology that could\nbe used to capture solar energy", "start": 339.79, "duration": 4.29}, {"text": "is called concentrated\nsolar power.", "start": 344.08, "duration": 2.67}, {"text": "This is a CSP plant, or\na solar thermal tower.", "start": 346.75, "duration": 3.78}, {"text": "This is Crescent Dunes\nin the American West.", "start": 350.53, "duration": 3.69}, {"text": "This is actually\n10,000 heliostats.", "start": 354.22, "duration": 2.58}, {"text": "These are those tracking\nmirrors I showed you.", "start": 356.8, "duration": 2.62}, {"text": "But instead of tracking\nthe sun directly,", "start": 359.42, "duration": 2.27}, {"text": "what these mirrors are doing\nare actually tracking the sun,", "start": 361.69, "duration": 3.33}, {"text": "reflecting the sun\nto this one point,", "start": 365.02, "duration": 2.4}, {"text": "and super heating\nup a fluid here", "start": 367.42, "duration": 2.97}, {"text": "that's used to drive\na steam turbine.", "start": 370.39, "duration": 2.05}, {"text": "So these 10,000 mirrors\nare moving in concert,", "start": 372.44, "duration": 3.29}, {"text": "are all moving differently,\nall concentrating the sun", "start": 375.73, "duration": 2.88}, {"text": "on this one point to\nsuperheat the site", "start": 378.61, "duration": 2.7}, {"text": "and create superheated liquid\nor steam to drive a turbine", "start": 381.31, "duration": 3.69}, {"text": "to create energy.", "start": 385.0, "duration": 1.53}, {"text": "Of course, what we're going\nto talk about mostly today", "start": 386.53, "duration": 2.25}, {"text": "is much humbler,\nsmaller technology.", "start": 388.78, "duration": 2.49}, {"text": "It's the solar\nphotovoltaic panel.", "start": 391.27, "duration": 2.46}, {"text": "A utility-scale solar\narray is composed", "start": 393.73, "duration": 3.39}, {"text": "of many of these\nmodules, a rooftop", "start": 397.12, "duration": 2.79}, {"text": "on a residential installation,\nor in a, let's say,", "start": 399.91, "duration": 3.57}, {"text": "camping cabin would probably\nbe based on one standard panel.", "start": 403.48, "duration": 3.45}, {"text": "This is a solar\npanel installation", "start": 406.93, "duration": 2.01}, {"text": "on top of a big box store.", "start": 408.94, "duration": 1.95}, {"text": "But solar panels are\nfundamentally modular.", "start": 410.89, "duration": 3.25}, {"text": "They can be deployed\nin different ways.", "start": 414.14, "duration": 1.788}, {"text": "And we're going to spend most\nof our time talking today", "start": 415.928, "duration": 2.292}, {"text": "about why solar photovoltaics,\nthat modular technology,", "start": 418.22, "duration": 3.95}, {"text": "has gotten cheap much faster\nthan other technologies.", "start": 422.17, "duration": 4.14}, {"text": "And so if you look at the\nfundamental cell efficiency,", "start": 426.31, "duration": 3.7}, {"text": "this is how efficiently a solar\ncell converts incident energy", "start": 430.01, "duration": 5.27}, {"text": "to electricity.", "start": 435.28, "duration": 1.48}, {"text": "This is what's called the\nchampion graph that NREL does.", "start": 436.76, "duration": 2.6}, {"text": "Every year, they\nupdate this graph.", "start": 439.36, "duration": 2.08}, {"text": "And you can see\nsteadily, there are", "start": 441.44, "duration": 1.61}, {"text": "these different trajectories\nof different technologies.", "start": 443.05, "duration": 2.91}, {"text": "The technologies are\nall in upper left.", "start": 445.96, "duration": 2.52}, {"text": "They range from\nmulti junction cells", "start": 448.48, "duration": 1.92}, {"text": "to crystalline silicon\ncells, to emerging", "start": 450.4, "duration": 3.27}, {"text": "photovoltaic technologies.", "start": 453.67, "duration": 1.56}, {"text": "You can see these technologies\nhave all developed over time", "start": 455.23, "duration": 3.0}, {"text": "and gotten better.", "start": 458.23, "duration": 2.0}, {"text": "The best research\ncell efficiency", "start": 460.23, "duration": 2.07}, {"text": "is 47% conversion of incident\nsunlight into electricity.", "start": 462.3, "duration": 5.41}, {"text": "But your average\nsolar panel that's", "start": 467.71, "duration": 2.66}, {"text": "deployed on most solar arrays\nranges from 20% to 25%.", "start": 470.37, "duration": 5.365}, {"text": "What MacKay says in\nhis book, that he'd", "start": 475.735, "duration": 1.625}, {"text": "be shocked if there's better\nresearch cell, or better", "start": 477.36, "duration": 3.57}, {"text": "efficiencies.", "start": 480.93, "duration": 0.93}, {"text": "Efficiencies have\ngone up over time.", "start": 481.86, "duration": 2.7}, {"text": "But that's not the key story\nI want to focus on today.", "start": 484.56, "duration": 2.49}, {"text": "It's the fact that solar\npanels have gotten much cheaper", "start": 487.05, "duration": 3.15}, {"text": "much more quickly, even\nthough the research", "start": 490.2, "duration": 2.4}, {"text": "efficiency, or the efficiency\nof most solar panels", "start": 492.6, "duration": 2.82}, {"text": "sold has stayed relatively\nconstant, around 20%.", "start": 495.42, "duration": 5.14}, {"text": "So if you look at-- this\ngraph from the BP Statistical", "start": 500.56, "duration": 4.04}, {"text": "Review of World Energy.", "start": 504.6, "duration": 1.77}, {"text": "It shows the share of global\nelectricity generation by fuel.", "start": 506.37, "duration": 3.66}, {"text": "And you can see that oil and\ncoal and hydroelectricity", "start": 510.03, "duration": 4.62}, {"text": "are all relatively flat.", "start": 514.65, "duration": 2.07}, {"text": "Natural gas has trended up.", "start": 516.72, "duration": 1.959}, {"text": "But the one that's quite\nremarkably trending up", "start": 518.679, "duration": 2.24}, {"text": "is renewables.", "start": 520.919, "duration": 1.051}, {"text": "And renewables is\ntrending up both in terms", "start": 521.97, "duration": 1.92}, {"text": "of wind and solar.", "start": 523.89, "duration": 1.367}, {"text": "If you look on the right-hand\ngraph and renewables", "start": 525.257, "duration": 2.083}, {"text": "as a share of power\ngeneration by region,", "start": 527.34, "duration": 2.22}, {"text": "in every single\nregion of the world,", "start": 529.56, "duration": 1.65}, {"text": "renewables seem to be on this\nvery steep, increasing curve.", "start": 531.21, "duration": 4.74}, {"text": "That curve is\nreminiscent of this", "start": 535.95, "duration": 2.13}, {"text": "putting of what's called\na cumulative distribution", "start": 538.08, "duration": 2.25}, {"text": "function.", "start": 540.33, "duration": 0.78}, {"text": "And this is basically simply\na sum of a bell curve.", "start": 541.11, "duration": 4.96}, {"text": "And you get this S curve by\nsumming up the bell curve.", "start": 546.07, "duration": 2.79}, {"text": "So using different\nparameters for the mean", "start": 548.86, "duration": 2.42}, {"text": "or the standard deviation,\nyou get different steepness", "start": 551.28, "duration": 2.97}, {"text": "of S curves between this\nmustard-colored curve", "start": 554.25, "duration": 2.55}, {"text": "and this green curve.", "start": 556.8, "duration": 2.4}, {"text": "And so just to point out how\nthat is the sum of these bell", "start": 559.2, "duration": 2.81}, {"text": "curves, those\nS-shaped curves come", "start": 562.01, "duration": 2.52}, {"text": "from these green, and mustard,\nand blue, and red bell curves.", "start": 564.53, "duration": 4.5}, {"text": "The reason why this is\nimportant is because this", "start": 569.03, "duration": 2.97}, {"text": "is an idea about how\ninnovations diffuse,", "start": 572.0, "duration": 3.39}, {"text": "that you may have\nseen this famous curve", "start": 575.39, "duration": 3.0}, {"text": "called the diffusion\nof innovations", "start": 578.39, "duration": 1.56}, {"text": "curve that was coined\nby Everett Rogers.", "start": 579.95, "duration": 2.58}, {"text": "And you may have heard\nthis phrase, \"innovators", "start": 582.53, "duration": 2.04}, {"text": "and early adopters.\"", "start": 584.57, "duration": 1.41}, {"text": "And he adopts this idea of a\nbell curve of different people", "start": 585.98, "duration": 4.38}, {"text": "or different organizations\nwilling to adopt technologies", "start": 590.36, "duration": 2.94}, {"text": "in different ways.", "start": 593.3, "duration": 1.12}, {"text": "There's innovators and early\nadopters who are first.", "start": 594.42, "duration": 2.72}, {"text": "There's an early majority, late\nmajority, and there's laggers.", "start": 597.14, "duration": 2.61}, {"text": "And if you take this bell curve\nof behaviors and add it up,", "start": 599.75, "duration": 3.63}, {"text": "you get this distribution,\nthis S-shaped distribution", "start": 603.38, "duration": 3.09}, {"text": "of adoption.", "start": 606.47, "duration": 1.14}, {"text": "And that's really what we\nwant to talk about today", "start": 607.61, "duration": 2.64}, {"text": "because if you look at\nthis S-shaped curve,", "start": 610.25, "duration": 2.61}, {"text": "this is a curve from\na New York Times", "start": 612.86, "duration": 2.94}, {"text": "article by Nicholas Felton.", "start": 615.8, "duration": 2.61}, {"text": "And you can see\nthat our adoption", "start": 618.41, "duration": 1.68}, {"text": "of different technologies\nover the last century", "start": 620.09, "duration": 2.4}, {"text": "have essentially followed\nthis S-shaped curve.", "start": 622.49, "duration": 3.03}, {"text": "We have electricity which has a\nkind of bump here in the 1920s,", "start": 625.52, "duration": 3.69}, {"text": "but looks roughly S-shaped.", "start": 629.21, "duration": 1.74}, {"text": "You see rapid adoption\nof refrigerators.", "start": 630.95, "duration": 2.76}, {"text": "You see rapid\nadoption of color TVs.", "start": 633.71, "duration": 2.34}, {"text": "And the point of this\ncolumn by Nicholas Felton", "start": 636.05, "duration": 2.43}, {"text": "a number of years ago\nwas that these curves get", "start": 638.48, "duration": 2.19}, {"text": "increasingly steep over time.", "start": 640.67, "duration": 2.19}, {"text": "Of course, we can't assume\nthat this is a causal process,", "start": 642.86, "duration": 3.15}, {"text": "or this is a inevitable\nor ineluctable process.", "start": 646.01, "duration": 3.318}, {"text": "Obviously, some of\nthese technologies", "start": 649.328, "duration": 1.542}, {"text": "like clothes, dryers,\nmicrowaves, color TVs, cell", "start": 650.87, "duration": 2.76}, {"text": "phones, computers,\nVCRs, could only", "start": 653.63, "duration": 2.55}, {"text": "exist if electricity\nexisted beforehand.", "start": 656.18, "duration": 2.82}, {"text": "You see the track\nof the telephone", "start": 659.0, "duration": 3.09}, {"text": "has a much more mixed,\nnot S-shaped curve.", "start": 662.09, "duration": 4.0}, {"text": "So we shouldn't assume\nthat a S-shaped curve is", "start": 666.09, "duration": 2.63}, {"text": "inevitable or\nineluctable, we obviously", "start": 668.72, "duration": 2.34}, {"text": "have to do things to\nadopt these technologies.", "start": 671.06, "duration": 3.0}, {"text": "The progress of our\ntechnologies may not", "start": 674.06, "duration": 2.13}, {"text": "be completely\npredictable or linear.", "start": 676.19, "duration": 3.63}, {"text": "But the point I want to\nmake about solar power", "start": 679.82, "duration": 2.66}, {"text": "is that solar power has\ndeclined by price by about 90%", "start": 682.48, "duration": 3.75}, {"text": "in the last 10 years.", "start": 686.23, "duration": 1.26}, {"text": "This is, again, that graph\nfrom Our World in Data.", "start": 687.49, "duration": 2.52}, {"text": "And the key point of this being\npart of your renewable toolbox", "start": 690.01, "duration": 3.51}, {"text": "is that you want to\nwork with technologies", "start": 693.52, "duration": 2.1}, {"text": "that are getting cheaper and\nalso happen to be cleaner.", "start": 695.62, "duration": 3.12}, {"text": "So if you look at all\nthe energy or electricity", "start": 698.74, "duration": 2.73}, {"text": "generating technologies\non this graph,", "start": 701.47, "duration": 2.13}, {"text": "again, nuclear's\ngotten more expensive.", "start": 703.6, "duration": 2.43}, {"text": "Coal stayed relatively flat.", "start": 706.03, "duration": 1.68}, {"text": "Gas has gotten cheaper, but not\nas quickly as solar power has", "start": 707.71, "duration": 3.93}, {"text": "gotten cheaper.", "start": 711.64, "duration": 0.84}, {"text": "Solar thermal towers, the\nconcentrating solar technology", "start": 712.48, "duration": 3.51}, {"text": "I showed you a few\nslides ago, that kind", "start": 715.99, "duration": 2.61}, {"text": "of awesome installation\nin the desert,", "start": 718.6, "duration": 2.73}, {"text": "though it's awesome\nin how it looks,", "start": 721.33, "duration": 1.95}, {"text": "it has not necessarily\ngone cheap as quick", "start": 723.28, "duration": 3.54}, {"text": "as the humble solar panel.", "start": 726.82, "duration": 2.93}, {"text": "And, also, of\ncourse, onshore wind", "start": 729.75, "duration": 2.37}, {"text": "has declined rapidly over time.", "start": 732.12, "duration": 3.16}, {"text": "And, again, if you\nlook at these curves,", "start": 735.28, "duration": 2.43}, {"text": "you can see that lithium\nion batteries since 1992", "start": 737.71, "duration": 3.45}, {"text": "are also steeply\ndecreasing in price.", "start": 741.16, "duration": 2.65}, {"text": "And I think I said\nin the last lecture", "start": 743.81, "duration": 1.61}, {"text": "that this is called\nthe learning rate.", "start": 745.42, "duration": 2.34}, {"text": "For every doubling in\ncumulative capacity,", "start": 747.76, "duration": 1.98}, {"text": "price has declined\nan average of 18.9%.", "start": 749.74, "duration": 3.96}, {"text": "Solar technologies,\nelectrolyzers,", "start": 753.7, "duration": 2.37}, {"text": "are also following\na very rapid curve.", "start": 756.07, "duration": 4.3}, {"text": "And, again, the key\npoint is that, yes,", "start": 760.37, "duration": 3.51}, {"text": "coal is a dirty fuel.", "start": 763.88, "duration": 3.12}, {"text": "But nuclear is also a low\ncarbon or clean resource.", "start": 767.0, "duration": 4.98}, {"text": "I would argue that\nnuclear will probably", "start": 771.98, "duration": 2.67}, {"text": "be a critical or important\nfirm resource for the future.", "start": 774.65, "duration": 4.38}, {"text": "But the problem is, our existing\nways of building nuclear power", "start": 779.03, "duration": 3.03}, {"text": "plants have only gotten\nmore expensive over time.", "start": 782.06, "duration": 2.52}, {"text": "They've not demonstrated\nany learning rate,", "start": 784.58, "duration": 2.67}, {"text": "whereas solar photovoltaics\nhave a learning rate of 36%.", "start": 787.25, "duration": 4.86}, {"text": "Offshore wind has a\nlearning rate of 10%.", "start": 792.11, "duration": 2.64}, {"text": "Onshore wind has a\nlearning rate of 23%.", "start": 794.75, "duration": 2.85}, {"text": "And lithium ion\nbatteries, which are", "start": 797.6, "duration": 2.61}, {"text": "crucial to electrifying\nvehicles and all", "start": 800.21, "duration": 3.0}, {"text": "of our electronic devices,\nhave a learning rate of 19%.", "start": 803.21, "duration": 4.14}, {"text": "You can perhaps,\nif not count on it,", "start": 807.35, "duration": 3.84}, {"text": "assume that some of\nthese learning rates", "start": 811.19, "duration": 2.22}, {"text": "will continue in the near\nfuture that will only", "start": 813.41, "duration": 2.52}, {"text": "make these technologies more\ncompetitive in the near future.", "start": 815.93, "duration": 4.58}, {"text": "And so a key question is, why\nhave the solar prices declined?", "start": 820.51, "duration": 3.78}, {"text": "This is a topic that\nmy colleague Jessika", "start": 824.29, "duration": 2.63}, {"text": "Trancik at MIT has studied.", "start": 826.92, "duration": 2.4}, {"text": "And she studied in a 2016\npaper all the various factors", "start": 829.32, "duration": 4.77}, {"text": "leading to these\ndeclines in solar prices,", "start": 834.09, "duration": 3.27}, {"text": "or this learning rate.", "start": 837.36, "duration": 1.08}, {"text": "And it's also\nimportant to point out", "start": 838.44, "duration": 1.5}, {"text": "that, as the\nNicholas Felton graph", "start": 839.94, "duration": 2.61}, {"text": "I showed you a few\nslides ago, it's", "start": 842.55, "duration": 2.28}, {"text": "not necessarily\nineluctable, or inevitable,", "start": 844.83, "duration": 3.12}, {"text": "or fated for all these\nthings to happen.", "start": 847.95, "duration": 3.43}, {"text": "But it is a little strange,\nand it is a little weirdly", "start": 851.38, "duration": 3.08}, {"text": "wonderful how they follow a\nfairly consistent pattern,", "start": 854.46, "duration": 3.39}, {"text": "even if different factors\nare leading to these price", "start": 857.85, "duration": 3.06}, {"text": "declines.", "start": 860.91, "duration": 1.23}, {"text": "For example, in\nJessika Trancik's paper", "start": 862.14, "duration": 2.13}, {"text": "she decomposes the\nsources of price decline", "start": 864.27, "duration": 3.54}, {"text": "from 1980 to 2001, from 2001 to\n2012, and the overall effect.", "start": 867.81, "duration": 6.52}, {"text": "And so she finds that the\noverall effect, the biggest", "start": 874.33, "duration": 3.47}, {"text": "contribution to solar prices\ndeclining is the efficiency.", "start": 877.8, "duration": 4.95}, {"text": "Nonsilicon material\ncosts have also improved.", "start": 882.75, "duration": 3.87}, {"text": "Silicon prices\nthemselves have improved.", "start": 886.62, "duration": 3.12}, {"text": "The usage of silicon\nhas improved.", "start": 889.74, "duration": 1.89}, {"text": "The wafer areas have improved.", "start": 891.63, "duration": 1.41}, {"text": "Plant sizes have gotten bigger.", "start": 893.04, "duration": 1.84}, {"text": "The yields have gotten better.", "start": 894.88, "duration": 1.29}, {"text": "And there's been\nslight impact on price.", "start": 896.17, "duration": 2.99}, {"text": "But you can see\nfrom 1980 to 2001,", "start": 899.16, "duration": 2.46}, {"text": "and 2001, 2012, a lot of\nthese different factors", "start": 901.62, "duration": 3.84}, {"text": "play in at different times.", "start": 905.46, "duration": 1.69}, {"text": "In other words,\nfor some reason, we", "start": 907.15, "duration": 2.21}, {"text": "have these fairly steady\ndeclines in solar,", "start": 909.36, "duration": 2.34}, {"text": "though they're not\ncompletely linear when", "start": 911.7, "duration": 1.77}, {"text": "graphed on a logarithmic graph.", "start": 913.47, "duration": 2.01}, {"text": "But it's also weirdly wonderful\nhow all these different factors", "start": 915.48, "duration": 3.24}, {"text": "play together.", "start": 918.72, "duration": 1.08}, {"text": "And when one part\nof the industry", "start": 919.8, "duration": 1.77}, {"text": "improved in one part\nof the technology,", "start": 921.57, "duration": 2.73}, {"text": "other parts of industry were\nthen able to, let's say,", "start": 924.3, "duration": 3.21}, {"text": "improve others.", "start": 927.51, "duration": 1.15}, {"text": "For example, Germany\nwas a pioneer in solar", "start": 928.66, "duration": 2.87}, {"text": "until China pioneered\nlarge-scale manufacturing", "start": 931.53, "duration": 3.24}, {"text": "of solar panels.", "start": 934.77, "duration": 2.37}, {"text": "If we break down\nsome of these changes", "start": 937.14, "duration": 3.28}, {"text": "and attribute them\nto larger categories,", "start": 940.42, "duration": 3.65}, {"text": "you can see that there's\nan overall effect", "start": 944.07, "duration": 2.04}, {"text": "of public and private research\nand development funding.", "start": 946.11, "duration": 3.21}, {"text": "There are some effects\nof learning by doing.", "start": 949.32, "duration": 2.01}, {"text": "The more you do something, the\nbetter you learn how to do it.", "start": 951.33, "duration": 2.85}, {"text": "Economies of scale--\nthe more of something", "start": 954.18, "duration": 2.19}, {"text": "you build, it\nactually gets cheaper", "start": 956.37, "duration": 2.16}, {"text": "if you build it in large\nvolumes, and other factors.", "start": 958.53, "duration": 2.99}, {"text": "But, again, between 1980\nand 2001, and 2001, 2012,", "start": 961.52, "duration": 3.94}, {"text": "you actually see the really\ndifferent contributions", "start": 965.46, "duration": 2.37}, {"text": "from these different factors.", "start": 967.83, "duration": 3.37}, {"text": "And so another question\nis, will solar prices", "start": 971.2, "duration": 1.91}, {"text": "continue to decline?", "start": 973.11, "duration": 1.695}, {"text": "And this is that\nlearning rate graph", "start": 974.805, "duration": 2.025}, {"text": "showing solar actual\nasset costs by year.", "start": 976.83, "duration": 4.53}, {"text": "This is from a recent paper by\nWay, Ives, Mealy and Farmer.", "start": 981.36, "duration": 4.05}, {"text": "And what's really entertaining\nabout this graph to me", "start": 985.41, "duration": 2.685}, {"text": "is that you can see the\ndifferent projections", "start": 988.095, "duration": 1.875}, {"text": "for solar costs.", "start": 989.97, "duration": 1.033}, {"text": "And the important\nthing about this graph", "start": 991.003, "duration": 1.667}, {"text": "is that, in every single\ncase, the empirically-observed", "start": 992.67, "duration": 3.69}, {"text": "capacity cost has been lower\nthan the projected costs.", "start": 996.36, "duration": 3.45}, {"text": "In fact, for some reason, a lot\nof integrated assessment models", "start": 999.81, "duration": 3.57}, {"text": "keep on projecting\nthat solar is not", "start": 1003.38, "duration": 1.92}, {"text": "going to get cheaper faster.", "start": 1005.3, "duration": 1.33}, {"text": "They have a shallower curve.", "start": 1006.63, "duration": 2.58}, {"text": "But in reality, solar\nhas gotten much cheaper", "start": 1009.21, "duration": 2.6}, {"text": "much more quickly than\nanyone ever projected", "start": 1011.81, "duration": 2.295}, {"text": "in the first place.", "start": 1014.105, "duration": 2.545}, {"text": "The authors of this\npaper argue and forecast", "start": 1016.65, "duration": 4.05}, {"text": "that solar prices will\ncontinue to get cheaper", "start": 1020.7, "duration": 2.31}, {"text": "because they look at\nother empirical cost", "start": 1023.01, "duration": 2.52}, {"text": "declines over time.", "start": 1025.53, "duration": 1.92}, {"text": "If you look at wind, wind has\nbeen on a similar trajectory", "start": 1027.45, "duration": 4.139}, {"text": "of decline.", "start": 1031.589, "duration": 0.99}, {"text": "And in all of these\ncases, many models", "start": 1032.579, "duration": 2.581}, {"text": "keep on predicting that\nwind is going to cost", "start": 1035.16, "duration": 2.37}, {"text": "more than it actually has.", "start": 1037.53, "duration": 1.589}, {"text": "So this leads to the question,\nif solar and wind continue", "start": 1039.119, "duration": 2.881}, {"text": "to get cheaper more\nquickly than we expect,", "start": 1042.0, "duration": 2.609}, {"text": "what might happen in\nthe energy transition?", "start": 1044.609, "duration": 2.581}, {"text": "The authors of\nthis paper actually", "start": 1047.19, "duration": 1.44}, {"text": "argue that there could be a fast\ntransition between clean energy", "start": 1048.63, "duration": 3.27}, {"text": "and fossil fuels, a slow\ntransition, or no transition", "start": 1051.9, "duration": 3.48}, {"text": "at all, where fossil fuels\nremain in our energy system.", "start": 1055.38, "duration": 4.17}, {"text": "And clean energy\nsimply adds to it.", "start": 1059.55, "duration": 2.05}, {"text": "But they actually\nargue that based", "start": 1061.6, "duration": 1.91}, {"text": "on the probability of technical\nand technological process,", "start": 1063.51, "duration": 2.68}, {"text": "which could be low,\nmedium, or high,", "start": 1066.19, "duration": 2.66}, {"text": "we'd actually save\nquite a bit of energy", "start": 1068.85, "duration": 2.04}, {"text": "if we had a fast\ntransition to renewables.", "start": 1070.89, "duration": 2.94}, {"text": "That would actually result in\nless costs in this scenario", "start": 1073.83, "duration": 3.96}, {"text": "than it would if we continue\nto use fossil fuels.", "start": 1077.79, "duration": 2.58}, {"text": "And that's assuming\nthat solar and wind", "start": 1080.37, "duration": 1.74}, {"text": "prices continue to get cheaper.", "start": 1082.11, "duration": 1.98}, {"text": "If we have a slower,\nmedium transition,", "start": 1084.09, "duration": 2.52}, {"text": "then we will still save money\nover a no transition scenario.", "start": 1086.61, "duration": 3.42}, {"text": "It just won't be as much.", "start": 1090.03, "duration": 1.65}, {"text": "And it won't be as fast.", "start": 1091.68, "duration": 3.16}, {"text": "If you look at some of\nthe price breakdowns", "start": 1094.84, "duration": 2.03}, {"text": "of solar installation\ncosts, this", "start": 1096.87, "duration": 1.86}, {"text": "is, again, the cost to actually\ninstall and get solar running,", "start": 1098.73, "duration": 5.07}, {"text": "you can see that NREL\ndid a study in 2015", "start": 1103.8, "duration": 2.82}, {"text": "looking at benchmark prices\nand price breakdowns.", "start": 1106.62, "duration": 3.09}, {"text": "And you can see in a\nlot of these cases,", "start": 1109.71, "duration": 1.89}, {"text": "that residential, small\ninstallations are much more", "start": 1111.6, "duration": 3.24}, {"text": "expensive than commercial\nlarge installations,", "start": 1114.84, "duration": 2.4}, {"text": "or utility-scale installations.", "start": 1117.24, "duration": 2.25}, {"text": "But when I point out to you\nis that the actual hardware,", "start": 1119.49, "duration": 3.09}, {"text": "the solar module, the inverter,\nthe rack, and the balance", "start": 1122.58, "duration": 2.46}, {"text": "of system, are actually\nnot much different", "start": 1125.04, "duration": 2.52}, {"text": "between residential\nand commercial", "start": 1127.56, "duration": 1.65}, {"text": "and utility-scale installations.", "start": 1129.21, "duration": 2.01}, {"text": "The panels are basically\nthe same panel.", "start": 1131.22, "duration": 2.68}, {"text": "It might cost different amounts\nto mount them and put them", "start": 1133.9, "duration": 3.83}, {"text": "in a rack.", "start": 1137.73, "duration": 0.78}, {"text": "But the costs are\nnot very different", "start": 1138.51, "duration": 1.62}, {"text": "between even a single solar\npanel on a residential house", "start": 1140.13, "duration": 3.36}, {"text": "versus utility-scale solar.", "start": 1143.49, "duration": 2.04}, {"text": "The big difference is\nbetween the soft costs.", "start": 1145.53, "duration": 2.95}, {"text": "The labor is slightly higher to\ninstall on a residential house,", "start": 1148.48, "duration": 3.59}, {"text": "probably because we\nhaven't achieved economies", "start": 1152.07, "duration": 2.16}, {"text": "of scale or large volumes.", "start": 1154.23, "duration": 2.02}, {"text": "But the soft costs\nare a big difference.", "start": 1156.25, "duration": 2.9}, {"text": "Why residential?", "start": 1159.15, "duration": 1.2}, {"text": "Rooftop solar is\nmuch more expensive", "start": 1160.35, "duration": 1.98}, {"text": "than utility-scale solar.", "start": 1162.33, "duration": 2.07}, {"text": "And so if I had to urge\nurban planners in cities", "start": 1164.4, "duration": 3.06}, {"text": "to work on one problem, I would\nargue that if we were to--", "start": 1167.46, "duration": 3.91}, {"text": "if we were able to decrease\nthe soft cost of installation,", "start": 1171.37, "duration": 3.29}, {"text": "then rooftop solar could be\ncompetitive with utility-scale", "start": 1174.66, "duration": 3.51}, {"text": "solar installations.", "start": 1178.17, "duration": 2.69}, {"text": "And so NREL also\ndid a study in 2018,", "start": 1180.86, "duration": 2.85}, {"text": "showing a road map to achieving\ncheaper solar electricity.", "start": 1183.71, "duration": 4.92}, {"text": "This shows the 2017\nreal levelized cost", "start": 1188.63, "duration": 3.185}, {"text": "of energy, something\nwe've talked", "start": 1191.815, "duration": 1.375}, {"text": "about in this class before.", "start": 1193.19, "duration": 1.84}, {"text": "This shows what the goal\nis, $0.05 per kilowatt hour", "start": 1195.03, "duration": 4.25}, {"text": "for a residential PV system.", "start": 1199.28, "duration": 2.4}, {"text": "And it shows that the\nroadmap for cheaper rooftop", "start": 1201.68, "duration": 4.05}, {"text": "or residential\nsolar goes entirely", "start": 1205.73, "duration": 2.22}, {"text": "through soft cost reduction.", "start": 1207.95, "duration": 1.39}, {"text": "This is a waterfall\ndiagram again.", "start": 1209.34, "duration": 2.19}, {"text": "You can see all the things\nyou can do to get to the goal.", "start": 1211.53, "duration": 2.9}, {"text": "But, obviously, the\nbulk of the savings", "start": 1214.43, "duration": 2.37}, {"text": "comes from reducing soft cost.", "start": 1216.8, "duration": 1.98}, {"text": "That's reducing permitting.", "start": 1218.78, "duration": 1.44}, {"text": "That's reducing design costs.", "start": 1220.22, "duration": 1.32}, {"text": "That's reducing\ndesign complexity.", "start": 1221.54, "duration": 2.43}, {"text": "It's making permitting\neasier at city hall.", "start": 1223.97, "duration": 2.76}, {"text": "If urban planners\nand policy makers", "start": 1226.73, "duration": 2.73}, {"text": "were to focus their\nattention on this,", "start": 1229.46, "duration": 1.62}, {"text": "we could have equally\ncheap rooftop solar.", "start": 1231.08, "duration": 3.27}, {"text": "And that would probably\nnot have the same land-use", "start": 1234.35, "duration": 2.43}, {"text": "impacts as utility-scale solar.", "start": 1236.78, "duration": 1.995}, {"text": "Now, let's go to\nthe MacKay graphs", "start": 1241.42, "duration": 1.86}, {"text": "for a second, MacKay\npapers for a second,", "start": 1243.28, "duration": 2.16}, {"text": "because I think they\nusually show points", "start": 1245.44, "duration": 2.16}, {"text": "about the energy density\nper area required", "start": 1247.6, "duration": 2.61}, {"text": "for renewable technologies.", "start": 1250.21, "duration": 1.41}, {"text": "This brings us into\ntalking about siting.", "start": 1251.62, "duration": 3.12}, {"text": "This is a graph of a vertical\naxis and energy consumption", "start": 1254.74, "duration": 3.81}, {"text": "per person the population\ndensity of people", "start": 1258.55, "duration": 2.82}, {"text": "per square kilometer.", "start": 1261.37, "duration": 1.56}, {"text": "And you can see, the\nworld has generally", "start": 1262.93, "duration": 2.01}, {"text": "in the last two centuries,\nboth consumed more energy", "start": 1264.94, "duration": 3.0}, {"text": "and gotten more dense.", "start": 1267.94, "duration": 1.77}, {"text": "The United States had\nhigher energy consumption", "start": 1269.71, "duration": 2.22}, {"text": "at the beginning and\nlower population densities", "start": 1271.93, "duration": 3.75}, {"text": "than the world.", "start": 1275.68, "duration": 1.175}, {"text": "Developing countries\ntend to have", "start": 1276.855, "duration": 1.375}, {"text": "lower energy consumption and\nhigher population densities.", "start": 1278.23, "duration": 3.66}, {"text": "England, over the\nlast four centuries,", "start": 1281.89, "duration": 3.06}, {"text": "has gotten to very high\nenergy consumption per person,", "start": 1284.95, "duration": 2.73}, {"text": "though not as high as\nthe US, but much higher", "start": 1287.68, "duration": 2.37}, {"text": "population densities\nthan the US.", "start": 1290.05, "duration": 3.53}, {"text": "And what MacKay does is graph\nsimply where we are currently.", "start": 1293.58, "duration": 4.35}, {"text": "This is the United States.", "start": 1297.93, "duration": 1.41}, {"text": "And he uses this graph to\nshow that if you multiply", "start": 1299.34, "duration": 3.66}, {"text": "these factors together, you can\nget these kind of isoclines,", "start": 1303.0, "duration": 3.06}, {"text": "or these gradient lines.", "start": 1306.06, "duration": 2.25}, {"text": "And you can see that the\nenergy consumption of the US", "start": 1308.31, "duration": 2.61}, {"text": "and the size of the circle is\nthe population of the country", "start": 1310.92, "duration": 2.88}, {"text": "is basically approaching what\ncan be provided by energy", "start": 1313.8, "duration": 2.67}, {"text": "crops, which is to\nsay, given this energy", "start": 1316.47, "duration": 2.37}, {"text": "consumption per\nperson for the US,", "start": 1318.84, "duration": 1.53}, {"text": "and given this\npopulation density,", "start": 1320.37, "duration": 2.1}, {"text": "we could supply all of our\nenergy needs with energy crops,", "start": 1322.47, "duration": 3.66}, {"text": "assuming we use the entire\nUnited States for energy crops.", "start": 1326.13, "duration": 3.9}, {"text": "If we add other\npossible technologies,", "start": 1330.03, "duration": 2.73}, {"text": "you can see the limit for\nwind power is further out.", "start": 1332.76, "duration": 3.87}, {"text": "Of course, that would require\nus to use much of the US", "start": 1336.63, "duration": 2.64}, {"text": "for wind power.", "start": 1339.27, "duration": 1.11}, {"text": "And the US has enough\nenergy density.", "start": 1340.38, "duration": 3.01}, {"text": "So we would have to use the\nentire country for wind power.", "start": 1343.39, "duration": 2.72}, {"text": "But you can see\ncountries like Germany,", "start": 1346.11, "duration": 1.99}, {"text": "the United Kingdom,\nand Japan, are already", "start": 1348.1, "duration": 1.97}, {"text": "at the limit for what\nwind power can provide.", "start": 1350.07, "duration": 2.28}, {"text": "South Korea does\nnot have enough land", "start": 1352.35, "duration": 2.16}, {"text": "to provide all of its\nenergy through wind power.", "start": 1354.51, "duration": 3.825}, {"text": "If you look at these\nother technologies", "start": 1358.335, "duration": 1.625}, {"text": "that MacKay discusses,\nsolar PV parks", "start": 1359.96, "duration": 3.82}, {"text": "in sunny locations\nor northern Europe", "start": 1363.78, "duration": 2.52}, {"text": "are concentrating solar power.", "start": 1366.3, "duration": 1.71}, {"text": "You can see that they\nhave lower energy--", "start": 1368.01, "duration": 2.13}, {"text": "the higher energy densities\nor lower land take.", "start": 1370.14, "duration": 2.61}, {"text": "So the frontier gets\npushed further out.", "start": 1372.75, "duration": 3.61}, {"text": "So for one of the\nstudents from Singapore,", "start": 1376.36, "duration": 2.63}, {"text": "he asked how much,\nwhat technologies could", "start": 1378.99, "duration": 2.76}, {"text": "we use to supply Singapore?", "start": 1381.75, "duration": 2.49}, {"text": "You can see that it's\npossible to use the UK", "start": 1384.24, "duration": 3.81}, {"text": "sun before conversion--", "start": 1388.05, "duration": 2.04}, {"text": "sorry, and the desert\nsun before conversion.", "start": 1390.09, "duration": 2.55}, {"text": "Those are things that\nthe population and energy", "start": 1392.64, "duration": 3.24}, {"text": "consumption of Singapore\nwould fit into.", "start": 1395.88, "duration": 2.16}, {"text": "Obviously, it's not\nentirely possible to convert", "start": 1398.04, "duration": 2.82}, {"text": "all of Singapore into\nenergy production.", "start": 1400.86, "duration": 2.4}, {"text": "But this gives you a back\nof the envelope estimate", "start": 1403.26, "duration": 2.79}, {"text": "of how much energy,\nor how much land you", "start": 1406.05, "duration": 2.22}, {"text": "need to provide that energy.", "start": 1408.27, "duration": 3.08}, {"text": "And so this brings\nme to the paper", "start": 1411.35, "duration": 1.67}, {"text": "by Carley et al 2020,\nwhich focuses on energy", "start": 1413.02, "duration": 3.75}, {"text": "infrastructure and NIMBY-ism.", "start": 1416.77, "duration": 2.44}, {"text": "And let's just start with what\nis a systematic literature", "start": 1419.21, "duration": 2.4}, {"text": "review.", "start": 1421.61, "duration": 0.84}, {"text": "A systematic\nliterature review is", "start": 1422.45, "duration": 1.59}, {"text": "a paper where you set particular\nsearch terms and parameters.", "start": 1424.04, "duration": 4.53}, {"text": "You extract the relevant\nacademic literature.", "start": 1428.57, "duration": 2.243}, {"text": "The reason why you do this\nkind of literature search", "start": 1430.813, "duration": 2.167}, {"text": "is that there's just too\nmuch literature to read.", "start": 1432.98, "duration": 2.22}, {"text": "So we occasionally write\npapers to summarize", "start": 1435.2, "duration": 2.34}, {"text": "what's been written.", "start": 1437.54, "duration": 1.65}, {"text": "And then you code and\nanalyze and summarize", "start": 1439.19, "duration": 2.25}, {"text": "all the papers you find.", "start": 1441.44, "duration": 1.38}, {"text": "And you categorize the\nvital data they use,", "start": 1442.82, "duration": 2.7}, {"text": "what kind of methods and\nfindings they come to.", "start": 1445.52, "duration": 3.35}, {"text": "And so the findings of\nthis particular systematic", "start": 1448.87, "duration": 2.32}, {"text": "literature review is\nthat on page 1 they say,", "start": 1451.19, "duration": 3.27}, {"text": "knowledge, trust, and\npositive perceptions", "start": 1454.46, "duration": 2.37}, {"text": "of the benefits of\nprojects are positively", "start": 1456.83, "duration": 2.4}, {"text": "correlated with support\nfor projects with variation", "start": 1459.23, "duration": 2.22}, {"text": "across energy types.", "start": 1461.45, "duration": 1.5}, {"text": "They actually say that we don't\nfocus on the positive aspects", "start": 1462.95, "duration": 3.09}, {"text": "of energy projects enough.", "start": 1466.04, "duration": 1.59}, {"text": "And our study of energy\ninfrastructure and often", "start": 1467.63, "duration": 2.73}, {"text": "NIMBY-ism were often focused\non some of the drawbacks", "start": 1470.36, "duration": 3.0}, {"text": "of these policies.", "start": 1473.36, "duration": 0.96}, {"text": "And people ask, or asked\nin survey literature,", "start": 1474.32, "duration": 2.94}, {"text": "much more about the drawbacks.", "start": 1477.26, "duration": 2.74}, {"text": "And so, and also they\nfind in this paper", "start": 1480.0, "duration": 2.6}, {"text": "that in our assessment,\nit's not clear that NIMBY--", "start": 1482.6, "duration": 3.0}, {"text": "which stands for \"Not\nIn My Backyard\"--", "start": 1485.6, "duration": 2.76}, {"text": "traditionally defined is\noften being evaluated.", "start": 1488.36, "duration": 2.97}, {"text": "At best, we have a set of\ninconsistent findings regarding", "start": 1491.33, "duration": 2.58}, {"text": "the weight that people give\nto the proximity of energy", "start": 1493.91, "duration": 2.67}, {"text": "infrastructure.", "start": 1496.58, "duration": 1.89}, {"text": "And, finally, they say on page\n13 the high rates of support", "start": 1498.47, "duration": 3.02}, {"text": "or found literature\nmay seem to contradict", "start": 1501.49, "duration": 2.43}, {"text": "what is often portrayed\nas significant opposition.", "start": 1503.92, "duration": 3.25}, {"text": "And so this leads us to the\nquestion, how much opposition", "start": 1507.17, "duration": 3.14}, {"text": "is there really to\nenergy infrastructure?", "start": 1510.31, "duration": 2.58}, {"text": "Do we actually have\nsignificant opposition", "start": 1512.89, "duration": 2.37}, {"text": "to energy infrastructure?", "start": 1515.26, "duration": 1.17}, {"text": "We have a million anecdotes\nabout this happening", "start": 1516.43, "duration": 2.34}, {"text": "in many places.", "start": 1518.77, "duration": 1.23}, {"text": "But this paper is trying to\nget at the existing survey", "start": 1520.0, "duration": 2.94}, {"text": "literature, summarizing\na lot of papers,", "start": 1522.94, "duration": 2.43}, {"text": "trying to understand, what\nis the actual opposition?", "start": 1525.37, "duration": 3.0}, {"text": "Does it actually fit\ninto our definition", "start": 1528.37, "duration": 2.79}, {"text": "of \"not in my\nbackyard\" sentiments?", "start": 1531.16, "duration": 3.56}, {"text": "And so I like this graph.", "start": 1534.72, "duration": 1.44}, {"text": "Actually it's in this\npaper quite a bit.", "start": 1536.16, "duration": 1.75}, {"text": "It's a way of\nsummarizing the papers.", "start": 1537.91, "duration": 2.18}, {"text": "They look at these\nindependent variables,", "start": 1540.09, "duration": 2.55}, {"text": "whether or not\nthey're considered", "start": 1542.64, "duration": 2.4}, {"text": "in the literature,\nterms of knowledge,", "start": 1545.04, "duration": 2.4}, {"text": "gender, trust,\nbenefits of energy,", "start": 1547.44, "duration": 3.18}, {"text": "and drawbacks of\nenergy infrastructure.", "start": 1550.62, "duration": 2.16}, {"text": "And they look at the total\nportfolio of energy types.", "start": 1552.78, "duration": 2.85}, {"text": "Total portfolio--\nand then that's", "start": 1555.63, "duration": 1.47}, {"text": "composed of wind, solar, nuclear\npower plants, fossil fuels,", "start": 1557.1, "duration": 4.14}, {"text": "and transmission and\ndistribution lines.", "start": 1561.24, "duration": 1.98}, {"text": "And the red, yellow,\nand blue columns", "start": 1563.22, "duration": 2.79}, {"text": "represent percent of papers\nthat include this factor,", "start": 1566.01, "duration": 4.29}, {"text": "the percent of papers that\nfind it to be statistically", "start": 1570.3, "duration": 2.52}, {"text": "significant, and the\npercent of papers that find", "start": 1572.82, "duration": 2.22}, {"text": "it to have a positive effect.", "start": 1575.04, "duration": 2.008}, {"text": "So what's important to\nnote from this graph, what", "start": 1577.048, "duration": 2.042}, {"text": "I want to point out,\nis that wind, solar,", "start": 1579.09, "duration": 2.85}, {"text": "nuclear, fossil fuels,\nand transmission lines", "start": 1581.94, "duration": 2.1}, {"text": "have very different profiles\nin terms of who supports it.", "start": 1584.04, "duration": 5.02}, {"text": "Not many researchers\nhave considered", "start": 1589.06, "duration": 2.45}, {"text": "asking people about their actual\nknowledge of wind projects.", "start": 1591.51, "duration": 3.7}, {"text": "But if you include\na gender variable,", "start": 1595.21, "duration": 2.27}, {"text": "you'll often find that one\ngender, I'm guessing female,", "start": 1597.48, "duration": 3.75}, {"text": "is actually quite\nsupportive of wind projects.", "start": 1601.23, "duration": 3.493}, {"text": "Not all the papers find this\nas statistically significant.", "start": 1604.723, "duration": 2.417}, {"text": "But almost all the papers\nfind this support of gender", "start": 1607.14, "duration": 3.24}, {"text": "to be a very strong factor\nin supporting wind power.", "start": 1610.38, "duration": 4.03}, {"text": "If you look at a\ndifferent technology,", "start": 1614.41, "duration": 1.64}, {"text": "let's say, nuclear technology,\nonly about half of the papers", "start": 1616.05, "duration": 4.44}, {"text": "asked people their actual\nknowledge of nuclear power.", "start": 1620.49, "duration": 3.27}, {"text": "Only about 50% of\npapers find it to be", "start": 1623.76, "duration": 1.83}, {"text": "statistically significant.", "start": 1625.59, "duration": 1.27}, {"text": "And, actually, they find that\nknowledge of nuclear power", "start": 1626.86, "duration": 3.53}, {"text": "is quite positively correlated\nwith support for nuclear power.", "start": 1630.39, "duration": 5.13}, {"text": "At the same, time if you\ninclude gender, almost 100%", "start": 1635.52, "duration": 3.21}, {"text": "of the papers include gender.", "start": 1638.73, "duration": 1.65}, {"text": "2/3 of them find to be\nstatistically significant.", "start": 1640.38, "duration": 2.41}, {"text": "And they don't find a strong\npositive effect of gender", "start": 1642.79, "duration": 3.59}, {"text": "sentiment about nuclear power.", "start": 1646.38, "duration": 2.28}, {"text": "What I'm trying to\npoint out this graph", "start": 1648.66, "duration": 1.92}, {"text": "is that all of these factors,\nknowledge, gender, trust,", "start": 1650.58, "duration": 3.63}, {"text": "benefits, and drawbacks,\nhave different profiles.", "start": 1654.21, "duration": 3.85}, {"text": "Some of these\ntechnologies like solar", "start": 1658.06, "duration": 1.88}, {"text": "have extremely\npositive correlations", "start": 1659.94, "duration": 3.06}, {"text": "with the benefits\nof solar power,", "start": 1663.0, "duration": 2.97}, {"text": "whereas the drawbacks are\nquite often asked about", "start": 1665.97, "duration": 2.28}, {"text": "and have very little\ndifference in how", "start": 1668.25, "duration": 2.13}, {"text": "people feel about solar power.", "start": 1670.38, "duration": 1.83}, {"text": "What I encourage you to do\nis just look at this graph.", "start": 1672.21, "duration": 2.5}, {"text": "Look at these different\nfactors on the top.", "start": 1674.71, "duration": 2.25}, {"text": "Look at the energy technologies.", "start": 1676.96, "duration": 1.4}, {"text": "And think about how you might\nappeal to different people", "start": 1678.36, "duration": 3.27}, {"text": "to support different\ntechnologies.", "start": 1681.63, "duration": 1.86}, {"text": "Obviously, the profile\nfor fossil fuels", "start": 1683.49, "duration": 5.01}, {"text": "is quite different than the\nprofile for transmission", "start": 1688.5, "duration": 2.55}, {"text": "and distribution lines.", "start": 1691.05, "duration": 1.36}, {"text": "And so we should think\nabout this research,", "start": 1692.41, "duration": 2.9}, {"text": "and think about how\nto use it to get", "start": 1695.31, "duration": 1.62}, {"text": "people to support these\ndifferent technologies that we", "start": 1696.93, "duration": 2.49}, {"text": "do need.", "start": 1699.42, "duration": 1.7}, {"text": "So another paper I\nwant to talk about", "start": 1701.12, "duration": 1.94}, {"text": "is written by my colleague\nLarry Susskind at MIT.", "start": 1703.06, "duration": 3.21}, {"text": "It's just written this year\nabout sources of opposition", "start": 1706.27, "duration": 2.82}, {"text": "to renewable energy.", "start": 1709.09, "duration": 1.56}, {"text": "And to summarize this\npaper, a team of students--", "start": 1710.65, "duration": 3.23}, {"text": "many students I know\nfrom our department--", "start": 1713.88, "duration": 1.75}, {"text": "helped build this\ndatabase of opposition", "start": 1715.63, "duration": 2.01}, {"text": "to renewable energy projects.", "start": 1717.64, "duration": 2.54}, {"text": "And they did this by reviewing\nopen access media reports", "start": 1720.18, "duration": 3.69}, {"text": "and published scholarship\nto identify instances", "start": 1723.87, "duration": 2.94}, {"text": "in which conflict or\nopposition paused,", "start": 1726.81, "duration": 2.1}, {"text": "delayed, or canceled a\nutility-scale renewable energy", "start": 1728.91, "duration": 2.79}, {"text": "project.", "start": 1731.7, "duration": 0.99}, {"text": "There were media\nreports on projects", "start": 1732.69, "duration": 1.77}, {"text": "that had been defeated,\nincluding some concerns", "start": 1734.46, "duration": 2.79}, {"text": "about these projects that did\nnot lead to stoppage or delay.", "start": 1737.25, "duration": 3.15}, {"text": "They did not include\nthese in their study.", "start": 1740.4, "duration": 2.35}, {"text": "So essentially what\nthey did is they", "start": 1742.75, "duration": 1.82}, {"text": "went and looked\nat media reports,", "start": 1744.57, "duration": 1.56}, {"text": "and looked for projects\nin which there actually", "start": 1746.13, "duration": 2.28}, {"text": "had been delays or opposition.", "start": 1748.41, "duration": 3.49}, {"text": "What they find in\nthis database, they", "start": 1751.9, "duration": 1.89}, {"text": "find 53 projects equivalent\nto 9,586 megawatts", "start": 1753.79, "duration": 5.19}, {"text": "that were affected.", "start": 1758.98, "duration": 1.39}, {"text": "They find that 34% of the\nprojects were delayed.", "start": 1760.37, "duration": 2.72}, {"text": "50% of the projects were\ncanceled permanently.", "start": 1763.09, "duration": 2.49}, {"text": "And 26% of the\nprojects were resumed", "start": 1765.58, "duration": 3.36}, {"text": "after being stopped for\nseveral months or years.", "start": 1768.94, "duration": 3.09}, {"text": "In terms of the\nenergy transition,", "start": 1772.03, "duration": 1.83}, {"text": "this is a very\nconcerning finding", "start": 1773.86, "duration": 2.1}, {"text": "because we know we need to\nbuild solar and wind much more", "start": 1775.96, "duration": 3.0}, {"text": "rapidly than in the past to\nachieve our decarbonization", "start": 1778.96, "duration": 3.06}, {"text": "goals.", "start": 1782.02, "duration": 2.13}, {"text": "And they have seven\ndistinct hypotheses", "start": 1784.15, "duration": 1.92}, {"text": "regarding the sources of\nopposition and barriers", "start": 1786.07, "duration": 2.58}, {"text": "to renewable energy development.", "start": 1788.65, "duration": 2.19}, {"text": "First, communities could\nbe expressing concerns", "start": 1790.84, "duration": 3.33}, {"text": "about possible\nenvironmental impacts,", "start": 1794.17, "duration": 1.6}, {"text": "including impacts on wildlife.", "start": 1795.77, "duration": 2.64}, {"text": "There could be challenges to\nproject financing and revenue", "start": 1798.41, "duration": 2.52}, {"text": "generation.", "start": 1800.93, "duration": 1.62}, {"text": "There could be\npublic perceptions", "start": 1802.55, "duration": 1.38}, {"text": "of unfair\nparticipation processes", "start": 1803.93, "duration": 2.04}, {"text": "or inadequate inclusion in light\nof regulatory requirements.", "start": 1805.97, "duration": 3.94}, {"text": "There could be a\nfailure to respect", "start": 1809.91, "duration": 1.55}, {"text": "tribal rights, including\nthe right to consultation.", "start": 1811.46, "duration": 3.18}, {"text": "There could be health\nand safety concerns.", "start": 1814.64, "duration": 2.37}, {"text": "The intergovernmental disputes.", "start": 1817.01, "duration": 2.37}, {"text": "And there could be potential\nimpacts on land and property", "start": 1819.38, "duration": 2.64}, {"text": "value.", "start": 1822.02, "duration": 1.52}, {"text": "In the paper, one of the\nnotable findings, I think,", "start": 1823.54, "duration": 2.55}, {"text": "is that they find that\nmost opposition to projects", "start": 1826.09, "duration": 2.97}, {"text": "is not composed of a single\nsource of opposition.", "start": 1829.06, "duration": 3.87}, {"text": "As they characterize\nit, only 20%", "start": 1832.93, "duration": 2.4}, {"text": "of the sources of opposition\nhave one rationale", "start": 1835.33, "duration": 5.52}, {"text": "or one basis for opposition.", "start": 1840.85, "duration": 2.01}, {"text": "Most projects represent multiple\nconcerns or multiple sources", "start": 1842.86, "duration": 4.65}, {"text": "of opposition, or a\ncollision of different groups", "start": 1847.51, "duration": 2.58}, {"text": "that may be opposed\nto the project.", "start": 1850.09, "duration": 2.74}, {"text": "Now, this is a very\nconcerning finding", "start": 1852.83, "duration": 2.18}, {"text": "in terms of what\nwe are going to be", "start": 1855.01, "duration": 1.74}, {"text": "able to site in terms of\nour future renewable energy", "start": 1856.75, "duration": 2.97}, {"text": "projects.", "start": 1859.72, "duration": 1.21}, {"text": "But one thing I actually\nnoticed about this paper", "start": 1860.93, "duration": 2.06}, {"text": "is that I actually thought back\nto other studies I've seen.", "start": 1862.99, "duration": 3.72}, {"text": "This is a graph from the\nUS Energy Information", "start": 1866.71, "duration": 3.09}, {"text": "Administration.", "start": 1869.8, "duration": 0.93}, {"text": "And this actually shows how\nmuch generation capacity we've", "start": 1870.73, "duration": 2.67}, {"text": "added over the last 22 years.", "start": 1873.4, "duration": 3.03}, {"text": "In 1990, you can see that our\nenergy, our renewable energy", "start": 1876.43, "duration": 4.02}, {"text": "generation is actually dominated\nby hydroconventional and", "start": 1880.45, "duration": 4.17}, {"text": "hydropumped storage.", "start": 1884.62, "duration": 1.62}, {"text": "Even by 2005, we had very little\nwind and very little solar.", "start": 1886.24, "duration": 3.93}, {"text": "And by 2021, 16 years\nlater, we basically", "start": 1890.17, "duration": 3.48}, {"text": "had this massive\nexplosion of wind,", "start": 1893.65, "duration": 1.68}, {"text": "and this very rapid explosion\nof solar that is probably", "start": 1895.33, "duration": 3.69}, {"text": "only increasing this year also.", "start": 1899.02, "duration": 2.79}, {"text": "But what I realized\nwhen I calculated", "start": 1901.81, "duration": 1.96}, {"text": "this is that you\nhad this question", "start": 1903.77, "duration": 3.47}, {"text": "about whether the findings of\nthis paper are generalizable.", "start": 1907.24, "duration": 3.21}, {"text": "The Susskind et al\npaper finds 53 projects", "start": 1910.45, "duration": 3.09}, {"text": "over the years 2008 to 2021.", "start": 1913.54, "duration": 2.52}, {"text": "And that basically\nis 9,586 megawatts,", "start": 1916.06, "duration": 4.66}, {"text": "which is 9.6 gigawatts.", "start": 1920.72, "duration": 2.15}, {"text": "But from that graph\nI just showed you,", "start": 1922.87, "duration": 1.86}, {"text": "the Energy Information\nAdministration", "start": 1924.73, "duration": 1.83}, {"text": "finds roughly over the same\nperiod of time 2005 to 2021,", "start": 1926.56, "duration": 3.78}, {"text": "that we added 185 gigawatts.", "start": 1930.34, "duration": 3.0}, {"text": "So if you calculate\nthe percentage,", "start": 1933.34, "duration": 2.28}, {"text": "essentially the\nSusskind paper is", "start": 1935.62, "duration": 1.44}, {"text": "looking at 5% of the projects.", "start": 1937.06, "duration": 2.52}, {"text": "And so there's three\nperhaps stupid questions", "start": 1939.58, "duration": 2.73}, {"text": "that we need to ask about\nthis question of permitting", "start": 1942.31, "duration": 3.36}, {"text": "and sources of opposition\nto renewable energy.", "start": 1945.67, "duration": 2.79}, {"text": "First, how big is the\nproblem of permitting?", "start": 1948.46, "duration": 2.34}, {"text": "If these opposition sources\nare expressing themselves", "start": 1950.8, "duration": 3.27}, {"text": "through denying\npermits for projects,", "start": 1954.07, "duration": 2.04}, {"text": "we can find 5% of the projects\nhave been blocked or opposed,", "start": 1956.11, "duration": 4.05}, {"text": "does that mean that our other\n185 gigawatts of projects that", "start": 1960.16, "duration": 3.81}, {"text": "were built, could we have\nhad another 185 gigawatts", "start": 1963.97, "duration": 3.39}, {"text": "of projects if 50% of the\nprojects were canceled?", "start": 1967.36, "duration": 3.42}, {"text": "Or do we find in this\ncase the projects that", "start": 1970.78, "duration": 3.96}, {"text": "were canceled or opposed, and\nthe vast majority of projects", "start": 1974.74, "duration": 3.33}, {"text": "are actually built without\nas much controversy?", "start": 1978.07, "duration": 5.1}, {"text": "And so this brings me to the\nquestion of permitting reform,", "start": 1983.17, "duration": 2.833}, {"text": "which we started the class,\nwhich is discussed quite a bit", "start": 1986.003, "duration": 2.417}, {"text": "in Congress, and we in class.", "start": 1988.42, "duration": 1.56}, {"text": "How pervasive is this problem?", "start": 1989.98, "duration": 2.26}, {"text": "And, finally, are\nthe future problems", "start": 1992.24, "duration": 1.95}, {"text": "we're going to have around\nsources of opposition", "start": 1994.19, "duration": 2.0}, {"text": "or permitting similar to\nthe past problems that have", "start": 1996.19, "duration": 3.39}, {"text": "been found in this database?", "start": 1999.58, "duration": 1.71}, {"text": "Those are all open\nquestions for us", "start": 2001.29, "duration": 1.5}, {"text": "to consider in class discussion.", "start": 2002.79, "duration": 1.83}, {"text": "I look forward to seeing\nyou in class tomorrow.", "start": 2004.62, "duration": 4.43}]

transcripts/3fSY92mJwQY.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 1.936}, {"text": "[RUSTLING]", "start": 1.936, "duration": 2.42}, {"text": "[CLICKING]", "start": 4.356, "duration": 0.968}, {"text": "MATTHEW VANDER HEIDEN:\nHello, everybody.", "start": 10.66, "duration": 1.71}, {"text": "Last time, I introduced\nthe idea of the TCA cycle,", "start": 12.37, "duration": 5.01}, {"text": "tricarboxylic acid cycle.", "start": 17.38, "duration": 2.2}, {"text": "Also known as the citric acid\ncycle, because citric acid", "start": 19.58, "duration": 2.99}, {"text": "is a tricarboxylic acid,\nas you'll see later today.", "start": 22.57, "duration": 3.12}, {"text": "Also known as the\nKrebs cycle, named", "start": 25.69, "duration": 2.01}, {"text": "after Hans Krebs,\nwho discovered it", "start": 27.7, "duration": 4.11}, {"text": "in the early part\nof the last century.", "start": 31.81, "duration": 3.73}, {"text": "The TCA cycle is the\nseries of reactions", "start": 35.54, "duration": 2.79}, {"text": "that occurs in the\nmitochondrial matrix", "start": 38.33, "duration": 2.1}, {"text": "and it allows the complete\noxidation of two carbon", "start": 40.43, "duration": 3.12}, {"text": "units, derived from many things,\nincluding pyruvate, derived", "start": 43.55, "duration": 3.54}, {"text": "from glucose and glycolysis and\nenables the complete oxidation", "start": 47.09, "duration": 5.82}, {"text": "of that carbon to CO2.", "start": 52.91, "duration": 2.61}, {"text": "Now, it's a cycle\nbecause those two carbon", "start": 55.52, "duration": 2.55}, {"text": "units from pyruvate or other\nsources enter the cycle,", "start": 58.07, "duration": 4.98}, {"text": "combine with 4-carbon\noxaloacetate,", "start": 63.05, "duration": 2.88}, {"text": "and combine to make\n6-carbon citrate.", "start": 65.93, "duration": 2.31}, {"text": "Hence the citric\nacid cycle, or TCA", "start": 68.24, "duration": 3.3}, {"text": "cycle, that is then oxidized\nback to 4 carbon units,", "start": 71.54, "duration": 4.26}, {"text": "forming a cycle\nthat allows cells", "start": 75.8, "duration": 5.76}, {"text": "to release lots of energy.", "start": 81.56, "duration": 1.71}, {"text": "Complete oxygen\nenables, ultimately,", "start": 83.27, "duration": 2.1}, {"text": "complete oxidation\nof glucose to CO2.", "start": 85.37, "duration": 2.64}, {"text": "We've talked many times\nhow this releases energy.", "start": 88.01, "duration": 2.55}, {"text": "And it also generates\nlots of intermediates", "start": 90.56, "duration": 2.19}, {"text": "for the cell that can be\nused to make other stuff.", "start": 92.75, "duration": 3.51}, {"text": "Last time, I alluded to the\nfact that citrate can be", "start": 96.26, "duration": 3.03}, {"text": "used, say, to make fatty acids.", "start": 99.29, "duration": 3.09}, {"text": "Today, what I want to\ndo is I want to dive", "start": 102.38, "duration": 1.98}, {"text": "into the details of how\nthis TCA cycle occurs", "start": 104.36, "duration": 4.65}, {"text": "and the consequences\nof the way it works,", "start": 109.01, "duration": 2.97}, {"text": "and how that affects other\naspects of metabolism.", "start": 111.98, "duration": 3.66}, {"text": "You'll see that it\nactually affects", "start": 115.64, "duration": 2.28}, {"text": "the ability of\ndifferent organisms,", "start": 117.92, "duration": 3.52}, {"text": "whether or not they\ncan make things", "start": 121.44, "duration": 1.61}, {"text": "from intermediates\nin this cycle,", "start": 123.05, "duration": 2.88}, {"text": "because of how the cycle works.", "start": 125.93, "duration": 1.735}, {"text": "Now, to start.", "start": 137.75, "duration": 0.645}, {"text": "Of course, if we're going\nto start from pyruvate.", "start": 141.15, "duration": 3.83}, {"text": "Pyruvate, of course,\nhas three carbons.", "start": 147.87, "duration": 3.34}, {"text": "And so if we're going to\ngenerate a two-carbon acetate", "start": 151.21, "duration": 4.55}, {"text": "group, we have to lose CO2.", "start": 155.76, "duration": 2.13}, {"text": "And as I described a\ncouple lectures ago,", "start": 164.22, "duration": 3.06}, {"text": "acetate is also\nthe thing that we", "start": 167.28, "duration": 2.46}, {"text": "can derive from\nmetabolism of ethanol,", "start": 169.74, "duration": 2.97}, {"text": "showing us two things--", "start": 172.71, "duration": 2.01}, {"text": "metabolized glucose to\npyruvate or ethanol itself--", "start": 174.72, "duration": 3.03}, {"text": "can both be turned into acetate.", "start": 177.75, "duration": 2.07}, {"text": "But really, the donor is\nthis molecule, acetyl-CoA.", "start": 179.82, "duration": 6.12}, {"text": "Which is basically also a\ncarboxylic acid, but rather", "start": 185.94, "duration": 3.3}, {"text": "than being a carboxylic\nacid, instead makes this", "start": 189.24, "duration": 2.94}, {"text": "a thioester bond, which\nactivates this carbon", "start": 192.18, "duration": 3.7}, {"text": "as a leaving group, such that it\ncan combine with oxaloacetate,", "start": 195.88, "duration": 19.88}, {"text": "which you'll remember\nfrom gluconeogenesis,", "start": 215.76, "duration": 5.37}, {"text": "releasing that S-CoA molecule\nto generate six-carbon citric.", "start": 221.13, "duration": 11.63}, {"text": "So, this is citric.", "start": 255.73, "duration": 0.96}, {"text": "You can see that we've made\na bond from this carbon", "start": 256.69, "duration": 3.42}, {"text": "on the acetate, losing this\nS-CoA group to this carbon", "start": 260.11, "duration": 5.59}, {"text": "oxaloacetate to make this\nsix-carbon citrate molecule,", "start": 265.7, "duration": 4.59}, {"text": "which is a one, two, three--", "start": 270.29, "duration": 1.88}, {"text": "three-carboxylic acid,\nor tricarboxylic acid.", "start": 272.17, "duration": 4.29}, {"text": "Hence the name\ncitric acid cycle,", "start": 276.46, "duration": 2.82}, {"text": "tricarboxylic acid cycle.", "start": 279.28, "duration": 2.17}, {"text": "Now, these six\ncarbons can then--", "start": 281.45, "duration": 3.14}, {"text": "or this six-carbon\ncitrate molecule", "start": 284.59, "duration": 2.31}, {"text": "can then be oxidized, generating\ntwo CO2 molecules that", "start": 286.9, "duration": 6.84}, {"text": "are released, and\nultimately reforming", "start": 293.74, "duration": 2.66}, {"text": "oxaloacetate that can pick up\nanother two-carbon acetyl-CoA", "start": 296.4, "duration": 5.38}, {"text": "to generate another citrate,\nand around and around the cycle", "start": 301.78, "duration": 3.33}, {"text": "goes, allowing in\nthe end the net entry", "start": 305.11, "duration": 4.92}, {"text": "of two carbons,\neffectively from acetate,", "start": 310.03, "duration": 3.81}, {"text": "and release of two\ncarbons as CO2.", "start": 313.84, "duration": 4.8}, {"text": "Now, as I alluded to, this\ncan come from pyruvate.", "start": 318.64, "duration": 5.55}, {"text": "It can come from\nacetate itself, vinegar.", "start": 324.19, "duration": 3.48}, {"text": "It can come from alcohol.", "start": 327.67, "duration": 1.53}, {"text": "It turns out that when\nyou break down fat,", "start": 329.2, "duration": 1.8}, {"text": "you also break it\ninto two carbon units.", "start": 331.0, "duration": 4.18}, {"text": "And so this cycle becomes\nvery useful for cells,", "start": 335.18, "duration": 3.5}, {"text": "because it allows the oxidation\nof many different molecules", "start": 338.68, "duration": 4.92}, {"text": "to completely turn\nthat carbon into CO2.", "start": 343.6, "duration": 5.2}, {"text": "Now, if we're going to\ndo this from glucose,", "start": 348.8, "duration": 4.57}, {"text": "however, you'll remember that\npyruvate has three carbons.", "start": 353.37, "duration": 12.38}, {"text": "And so if we're going\nto turn pyruvate", "start": 365.75, "duration": 1.94}, {"text": "into acetate, or acetyl-CoA, we\nhave to lose a carbon of CO2.", "start": 367.69, "duration": 6.75}, {"text": "We have to lose\nthis carbon as CO2.", "start": 374.44, "duration": 3.49}, {"text": "Now, we saw this before,\nthat we can do this via--", "start": 377.93, "duration": 3.77}, {"text": "this is exactly how\nwe generated ethanol", "start": 381.7, "duration": 5.1}, {"text": "when we did fermentation\nof pyruvate to ethanol,", "start": 386.8, "duration": 6.03}, {"text": "but that molecule\ndidn't generate acetate,", "start": 392.83, "duration": 3.3}, {"text": "It generated acetaldehyde.", "start": 396.13, "duration": 2.4}, {"text": "The difference, of course, being\nwhether or not this carbon gets", "start": 398.53, "duration": 3.66}, {"text": "oxidized in the case\nof acetate to the acid,", "start": 402.19, "duration": 2.64}, {"text": "or in acetaldehyde in\nethanol metabolism,", "start": 404.83, "duration": 2.37}, {"text": "where it remains an aldehyde.", "start": 407.2, "duration": 2.37}, {"text": "Now obviously, you can\nmake ethanol and then", "start": 409.57, "duration": 2.76}, {"text": "turn that ethanol into acetate.", "start": 412.33, "duration": 2.25}, {"text": "And that's a pathway that I\nguess certainly would work.", "start": 414.58, "duration": 3.22}, {"text": "However, that's not the way\nit happens in most organisms.", "start": 417.8, "duration": 3.62}, {"text": "Most organisms actually\ndirectly produce", "start": 421.42, "duration": 5.76}, {"text": "acetate, or more correctly,\nacetyl-CoA from pyruvate.", "start": 427.18, "duration": 4.69}, {"text": "So let's take a look\nat that reaction.", "start": 431.87, "duration": 2.33}, {"text": "So here once again is pyruvate.", "start": 438.5, "duration": 1.87}, {"text": "And if we turn\nthat pyruvate into", "start": 444.49, "duration": 3.42}, {"text": "this two-carbon\nacetyl-CoA, let's", "start": 447.91, "duration": 6.68}, {"text": "look here what has to happen.", "start": 454.59, "duration": 2.8}, {"text": "Well, the first\nthing is that we have", "start": 457.39, "duration": 4.67}, {"text": "to decarboxylate this molecule.", "start": 462.06, "duration": 5.99}, {"text": "And so that generates a CO2.", "start": 468.05, "duration": 3.56}, {"text": "We have to lose that one carbon.", "start": 471.61, "duration": 3.81}, {"text": "Also, as I pointed\nout, if we do this", "start": 475.42, "duration": 4.59}, {"text": "as if we did it in\nethanol metabolism,", "start": 480.01, "duration": 2.31}, {"text": "we'd be left with an aldehyde.", "start": 482.32, "duration": 2.38}, {"text": "But this is an acid, and so this\ncarbon also has to be oxidized.", "start": 484.7, "duration": 6.23}, {"text": "We know how to do that.", "start": 490.93, "duration": 1.11}, {"text": "We can donate those electrons\nto something like NAD,", "start": 492.04, "duration": 7.2}, {"text": "so the NAD is reduced to NADH.", "start": 499.24, "duration": 3.81}, {"text": "And we had to add this\nS-CoA molecule, which", "start": 503.05, "duration": 7.72}, {"text": "I'll come to in a minute.", "start": 510.77, "duration": 2.68}, {"text": "And so each of\nthese steps ends up", "start": 513.45, "duration": 6.28}, {"text": "making a fairly\ncomplicated reaction.", "start": 519.73, "duration": 3.99}, {"text": "Obviously, several co-factors\nare going to be involved.", "start": 523.72, "duration": 3.078}, {"text": "You should be able to guess\nthat just by looking at it.", "start": 526.798, "duration": 2.292}, {"text": "Obviously, I already\ndrew up there NAD.", "start": 529.09, "duration": 2.31}, {"text": "If we're going to\ndecarboxylate, remember", "start": 531.4, "duration": 3.06}, {"text": "this is a alpha\ncarboxylic, an alpha", "start": 534.46, "duration": 9.29}, {"text": "ketoacid-- the ketone group is\nalpha to the carboxylic acid.", "start": 543.75, "duration": 4.42}, {"text": "And so if we're doing\nalpha decarboxylation,", "start": 548.17, "duration": 3.02}, {"text": "as you might guess,\nwe need a co-factor.", "start": 551.19, "duration": 2.31}, {"text": "That co-factor, as\nI told you before,", "start": 553.5, "duration": 1.71}, {"text": "is the co-factor factor\nthiamine pyrophosphate.", "start": 555.21, "duration": 2.64}, {"text": "And finally, there's\nthis S-CoA group.", "start": 557.85, "duration": 4.09}, {"text": "We need to describe\nwhat that is.", "start": 561.94, "duration": 3.38}, {"text": "However, before delving\ninto those, and there's", "start": 565.32, "duration": 3.87}, {"text": "actually a couple other factors\nthat are needed as well,", "start": 569.19, "duration": 2.97}, {"text": "I want to mention\none other issue", "start": 572.16, "duration": 3.99}, {"text": "about this reaction, in\nthat this reaction happens", "start": 576.15, "duration": 4.83}, {"text": "in the mitochondria,\nbecause that's also", "start": 580.98, "duration": 3.84}, {"text": "where the TCA cycle happens.", "start": 584.82, "duration": 1.95}, {"text": "So, recall that if we divide\nthe cell into two compartments", "start": 586.77, "duration": 4.05}, {"text": "like an eukaryotic cell,\nhere we have the cytosol", "start": 590.82, "duration": 3.06}, {"text": "and the mitochondria\nin a eukaryotic cell.", "start": 593.88, "duration": 2.76}, {"text": "As we've already talked about,\nhaving different compartments", "start": 596.64, "duration": 3.0}, {"text": "helps facilitate different\nmetabolic reactions,", "start": 599.64, "duration": 2.753}, {"text": "because you can have different\nconditions in the two", "start": 602.393, "duration": 2.167}, {"text": "compartments.", "start": 604.56, "duration": 1.3}, {"text": "And so as we said, glycolysis\noccurs in the cytosol.", "start": 605.86, "duration": 9.38}, {"text": "Glucose to pyruvate.", "start": 615.24, "duration": 1.85}, {"text": "And last time I\nmentioned, the TCA cycle", "start": 617.09, "duration": 9.63}, {"text": "occurs in the mitochondria.", "start": 626.72, "duration": 4.62}, {"text": "And so that means if we're\ngoing to fully oxidize", "start": 631.34, "duration": 3.36}, {"text": "the pyruvate carbon\nto CO2 using the TCA", "start": 634.7, "duration": 4.2}, {"text": "cycle in the mitochondria,\nthat pyruvate", "start": 638.9, "duration": 2.61}, {"text": "has to get from the cytosol to\nthe mitochondria, or at least", "start": 641.51, "duration": 3.33}, {"text": "carbons from the pyruvate\nhave to get there.", "start": 644.84, "duration": 2.568}, {"text": "It turns out, you'll\nsee in a minute,", "start": 647.408, "duration": 1.542}, {"text": "acetyl-CoA is a\nvery large group.", "start": 648.95, "duration": 1.92}, {"text": "And so pyruvate\nitself is transported", "start": 650.87, "duration": 2.88}, {"text": "into the mitochondria.", "start": 653.75, "duration": 1.89}, {"text": "And that's where\nthe reaction occurs", "start": 655.64, "duration": 1.62}, {"text": "to turn it into acetyl-CoA that\ncan then enter the TCA cycle", "start": 657.26, "duration": 3.36}, {"text": "and oxidize.", "start": 660.62, "duration": 1.92}, {"text": "However, what this means is\nthat a transporter is actually", "start": 662.54, "duration": 4.83}, {"text": "needed to get this across\nthe mitochondrial membranes", "start": 667.37, "duration": 3.24}, {"text": "and into the matrix of the\nmitochondria where the TCA", "start": 670.61, "duration": 2.61}, {"text": "cycle happens.", "start": 673.22, "duration": 1.942}, {"text": "And I like to mention\nthis because it turns out", "start": 675.162, "duration": 1.958}, {"text": "the pyruvate carrier--", "start": 677.12, "duration": 1.17}, {"text": "that is, the\ntransporter-- the way", "start": 678.29, "duration": 1.5}, {"text": "that it actually gets that\npyruvate from the cytosol", "start": 679.79, "duration": 3.03}, {"text": "into the mitochondria\nactually was", "start": 682.82, "duration": 2.4}, {"text": "an unknown thing\nabout metabolism", "start": 685.22, "duration": 1.83}, {"text": "until 2012, so\nnot that long ago.", "start": 687.05, "duration": 3.33}, {"text": "Sometimes one can be\nleft with the feeling,", "start": 690.38, "duration": 4.77}, {"text": "listening to these metabolism\nclasses or reading a textbook,", "start": 695.15, "duration": 3.54}, {"text": "that everything about metabolism\nhas been known forever,", "start": 698.69, "duration": 3.66}, {"text": "but it's actually not true.", "start": 702.35, "duration": 1.59}, {"text": "Here's a very key, central\npart of the pathway that", "start": 703.94, "duration": 3.57}, {"text": "was actually just\ndiscovered, at least", "start": 707.51, "duration": 2.25}, {"text": "at the time of this lecture,\nless than 10 years ago.", "start": 709.76, "duration": 2.46}, {"text": "It also illustrates that not\nall metabolism is completely", "start": 715.04, "duration": 4.3}, {"text": "understood.", "start": 719.34, "duration": 3.17}, {"text": "Now, let's get back to this\nreaction, how you turn pyruvate", "start": 722.51, "duration": 4.47}, {"text": "into acetyl-CoA.", "start": 726.98, "duration": 2.61}, {"text": "And I want to go through\nnow and point out", "start": 729.59, "duration": 2.31}, {"text": "that several\nco-factors are needed.", "start": 731.9, "duration": 3.1}, {"text": "And so I already mentioned\none of them, S-CoA,", "start": 735.0, "duration": 4.46}, {"text": "which is shorthand\nfor coenzyme A. So,", "start": 739.46, "duration": 7.03}, {"text": "I need to tell you what that is.", "start": 746.49, "duration": 3.38}, {"text": "You hopefully are already\nfamiliar with TPP plus,", "start": 749.87, "duration": 4.98}, {"text": "thiamine pyrophosphate.", "start": 754.85, "duration": 1.32}, {"text": "We talked about\nthat when we talked", "start": 756.17, "duration": 3.12}, {"text": "about how you do alpha\ndecarboxylation to generate", "start": 759.29, "duration": 3.6}, {"text": "ethanol from pyruvate,\nalso used here", "start": 762.89, "duration": 2.55}, {"text": "for the alpha\ndecarboxylation reaction.", "start": 765.44, "duration": 3.18}, {"text": "Redox reaction\nhappens, and so we", "start": 768.62, "duration": 2.58}, {"text": "needed NAD plus to get\nconverted into NADH.", "start": 771.2, "duration": 6.56}, {"text": "We talked a lot about how that\nserves as an electron carrier,", "start": 777.76, "duration": 3.36}, {"text": "but it turns out that there's\ntwo additional electron", "start": 781.12, "duration": 3.0}, {"text": "carriers that are\ninvolved in this reaction.", "start": 784.12, "duration": 3.27}, {"text": "One of them is called\nFAD and the other one", "start": 787.39, "duration": 4.56}, {"text": "is called lipoic acid.", "start": 791.95, "duration": 2.205}, {"text": "Now you might say,\nwhy do we need", "start": 798.12, "duration": 1.58}, {"text": "all these electron carriers?", "start": 799.7, "duration": 2.37}, {"text": "Well, these are just\ndifferent molecules", "start": 802.07, "duration": 2.19}, {"text": "that can carry two\nelectrons, similar to NADH.", "start": 804.26, "duration": 6.34}, {"text": "And effectively, what these can\ndo by having multiple electron", "start": 810.6, "duration": 3.83}, {"text": "carriers--", "start": 814.43, "duration": 1.05}, {"text": "one can build chains of\noxidation and reduction", "start": 815.48, "duration": 4.2}, {"text": "reactions.", "start": 819.68, "duration": 1.26}, {"text": "And it turns out these chains\nof oxidation reduction reactions", "start": 820.94, "duration": 3.18}, {"text": "really become central to\nenergy transfers in biology,", "start": 824.12, "duration": 4.08}, {"text": "because building\nthese chains allows", "start": 828.2, "duration": 2.49}, {"text": "more easy stepwise\nrelease of energy", "start": 830.69, "duration": 3.33}, {"text": "as one moves across these\noxidation reduction reactions.", "start": 834.02, "duration": 3.64}, {"text": "Which remember, as I\nalluded to earlier, really", "start": 837.66, "duration": 2.51}, {"text": "are at the core of bioenergetics\nand a lot of what allows energy", "start": 840.17, "duration": 6.72}, {"text": "release from these pathways.", "start": 846.89, "duration": 3.09}, {"text": "What I mean by this\nwill be more explicit", "start": 849.98, "duration": 3.51}, {"text": "as we go through what some of\nthese co-factors look like.", "start": 853.49, "duration": 4.86}, {"text": "So, I'm not going to draw TPP\nplus or NAD again, but let's", "start": 858.35, "duration": 7.2}, {"text": "define what some of these\nother cofactors look like.", "start": 865.55, "duration": 4.54}, {"text": "So, let's start with coenzyme\nA. So, coenzyme A, it turns out,", "start": 870.09, "duration": 9.32}, {"text": "is useful.", "start": 879.41, "duration": 1.8}, {"text": "It's actually involved in\nlots of acylation reactions.", "start": 881.21, "duration": 5.15}, {"text": "What's an acylation reaction?", "start": 886.36, "duration": 1.71}, {"text": "Well, that's basically if you're\nmaking a carbon-carbon bond", "start": 888.07, "duration": 4.68}, {"text": "by adding a molecule of greater\nthan one carbon, so two carbons", "start": 892.75, "duration": 3.45}, {"text": "or greater, to something else.", "start": 896.2, "duration": 1.83}, {"text": "That's an acylation\nreaction, as we", "start": 898.03, "duration": 2.04}, {"text": "did with adding the two-carbon\nacetate to oxaloacetate", "start": 900.07, "duration": 4.74}, {"text": "to make citrate.", "start": 904.81, "duration": 1.65}, {"text": "And you'll actually see\ncoenzyme A will come up", "start": 906.46, "duration": 2.22}, {"text": "in this in many, many\nlectures throughout the rest", "start": 908.68, "duration": 2.43}, {"text": "of the course.", "start": 911.11, "duration": 1.29}, {"text": "Why this becomes useful\nis because it activates", "start": 912.4, "duration": 4.35}, {"text": "this basically carbon to\nthe left of, in this case,", "start": 916.75, "duration": 8.78}, {"text": "the ketone.", "start": 925.53, "duration": 0.92}, {"text": "Because, by having\nthat thioester there,", "start": 926.45, "duration": 2.88}, {"text": "ends up activating that carbon\nand allows it to carry out", "start": 929.33, "duration": 4.29}, {"text": "these acylation reactions.", "start": 933.62, "duration": 3.45}, {"text": "Coenzyme A itself is\nderived from a vitamin", "start": 937.07, "duration": 3.93}, {"text": "called pantothenic acid.", "start": 941.0, "duration": 3.285}, {"text": "And as a vitamin,\nthis is something", "start": 948.67, "duration": 4.05}, {"text": "that you have to\nget from the diet.", "start": 952.72, "duration": 2.65}, {"text": "Now, when we\nabbreviate coenzyme A,", "start": 955.37, "duration": 3.32}, {"text": "which is often\nabbreviated S-CoA,", "start": 958.69, "duration": 3.75}, {"text": "you get the sense that it's\nthis little tiny molecule", "start": 962.44, "duration": 2.52}, {"text": "that's just stuck on sulfur--", "start": 964.96, "duration": 1.74}, {"text": "stuck on to the end to\nmake this thioester bond.", "start": 966.7, "duration": 2.91}, {"text": "But it turns out coenzyme A is\nactually a giant molecule, one", "start": 969.61, "duration": 3.12}, {"text": "of the reasons why you\nactually synthesize acetyl-CoA", "start": 972.73, "duration": 6.66}, {"text": "in the mitochondria,\nbecause it's", "start": 979.39, "duration": 1.41}, {"text": "hard to transport\nthis giant molecule.", "start": 980.8, "duration": 3.37}, {"text": "And so this is what\npantothenic acid looks like.", "start": 984.17, "duration": 4.82}, {"text": "So, if I put an acid group here\nand a hydroxyl group there,", "start": 1007.92, "duration": 5.48}, {"text": "that would be pantothenic\nacid, the thing", "start": 1013.4, "duration": 2.13}, {"text": "that's in your cereal, on\nthe side of your cereal box.", "start": 1015.53, "duration": 4.545}, {"text": "Then there's these\nadditional pieces.", "start": 1025.47, "duration": 2.22}, {"text": "This is the active\nend of the molecule,", "start": 1027.69, "duration": 9.69}, {"text": "that's that sulfur\nfrom the S-CoA,", "start": 1037.38, "duration": 2.459}, {"text": "and then this side of the\nmolecule is esterified to two", "start": 1039.839, "duration": 5.341}, {"text": "phosphates, which\nare esterified to--", "start": 1045.18, "duration": 3.63}, {"text": "I'm not going to\ndraw it out, but this", "start": 1051.477, "duration": 1.583}, {"text": "would have an adenine base\nand a phosphate there.", "start": 1053.06, "duration": 6.14}, {"text": "So basically, this is\nADP, with a phosphate", "start": 1059.2, "duration": 8.34}, {"text": "added to the 3 prime\nposition of the ADP molecule,", "start": 1067.54, "duration": 4.2}, {"text": "added to pantothenic acid,\nadded to this short chain", "start": 1071.74, "duration": 4.26}, {"text": "with the sulfur on the end.", "start": 1076.0, "duration": 1.56}, {"text": "And this whole molecule\ntogether is coenzyme A.", "start": 1077.56, "duration": 3.99}, {"text": "And so when we say\nacetyl-CoA, it's", "start": 1081.55, "duration": 1.98}, {"text": "this giant molecule,\nS-thioester to the carbonyl,", "start": 1083.53, "duration": 9.1}, {"text": "the acid on acetate, to CH3.", "start": 1092.63, "duration": 4.32}, {"text": "And so that would be,\nbasically, acetyl-CoA.", "start": 1096.95, "duration": 3.73}, {"text": "And so one convenient\nthing about this", "start": 1100.68, "duration": 3.35}, {"text": "is it's much easier than\ndrawing that big molecule,", "start": 1104.03, "duration": 2.58}, {"text": "but it is a little bit\nmisleading in terms", "start": 1106.61, "duration": 4.32}, {"text": "of its size.", "start": 1110.93, "duration": 1.74}, {"text": "So, that's coenzyme A.", "start": 1112.67, "duration": 3.3}, {"text": "Next one I want to\ntalk about is FAD", "start": 1115.97, "duration": 6.27}, {"text": "which stands for flavin\nadenine dinucleotide.", "start": 1122.24, "duration": 8.88}, {"text": "So, flavin adenine dinucleotide\nis an electron carrier,", "start": 1134.6, "duration": 3.51}, {"text": "just like NAD plus.", "start": 1138.11, "duration": 1.725}, {"text": "And it's derived from\nthe vitamin riboflavin,", "start": 1145.33, "duration": 6.15}, {"text": "also referred to as vitamin B2.", "start": 1151.48, "duration": 3.0}, {"text": "Another thing from the side of\nyour cereal box, and basically", "start": 1157.24, "duration": 4.17}, {"text": "looks like this.", "start": 1161.41, "duration": 2.03}, {"text": "So, like NAD, it's\na dinucleotide.", "start": 1163.44, "duration": 8.23}, {"text": "And so here's ADP, just\nlike we do for CoA, or just", "start": 1180.14, "duration": 5.13}, {"text": "like one end of NAD.", "start": 1185.27, "duration": 2.16}, {"text": "One difference is that the\nother nucleotide down here", "start": 1187.43, "duration": 3.9}, {"text": "actually isn't\ntechnically a sugar.", "start": 1191.33, "duration": 2.68}, {"text": "It's ribitol instead of ribose.", "start": 1194.01, "duration": 3.23}, {"text": "What does that mean?", "start": 1197.24, "duration": 1.0}, {"text": "It doesn't have an aldehyde.", "start": 1198.24, "duration": 1.7}, {"text": "Instead, it is just\na five-carbon chain", "start": 1199.94, "duration": 4.77}, {"text": "where all of the\ncarbons are alcohols.", "start": 1204.71, "duration": 3.3}, {"text": "And so since\nthere's no aldehyde,", "start": 1214.45, "duration": 1.8}, {"text": "it doesn't form a ring.", "start": 1216.25, "duration": 1.95}, {"text": "And the base on this\nend, as a nicotinamide,", "start": 1245.15, "duration": 4.53}, {"text": "is this flavin group,\nwhich looks like this.", "start": 1249.68, "duration": 17.5}, {"text": "And so this is FAD, which\nis in the oxidized form.", "start": 1267.18, "duration": 8.56}, {"text": "Turns out, in the\noxidized form, FAD", "start": 1275.74, "duration": 3.51}, {"text": "is yellow, hence riboflavin--\n\"flavin\", yellow.", "start": 1279.25, "duration": 6.27}, {"text": "And the reason it's\nyellow-- you see", "start": 1285.52, "duration": 1.89}, {"text": "there's a conjugated double\nbond here across this part.", "start": 1287.41, "duration": 3.36}, {"text": "It turns out this is the\nactive part of the molecule,", "start": 1290.77, "duration": 3.69}, {"text": "and it works as follows.", "start": 1294.46, "duration": 1.44}, {"text": "And so if you have\na hydride ion,", "start": 1295.9, "duration": 2.64}, {"text": "remember the way we can\ntransfer two electrons.", "start": 1298.54, "duration": 3.06}, {"text": "Can transfer the two\nelectrons that way,", "start": 1306.39, "duration": 2.88}, {"text": "and that allows it to generate.", "start": 1309.27, "duration": 1.65}, {"text": "And I'll just draw\nthe middle, here.", "start": 1310.92, "duration": 2.7}, {"text": "Active part of the molecule.", "start": 1313.62, "duration": 2.7}, {"text": "So, that would be\nthese two nitrogens.", "start": 1331.18, "duration": 2.33}, {"text": "We've added two electrons to it.", "start": 1333.51, "duration": 1.84}, {"text": "And so this is\nabbreviated FADH2,", "start": 1335.35, "duration": 5.24}, {"text": "or the reduced form of FAD.", "start": 1340.59, "duration": 4.11}, {"text": "And it is colorless,\nbecause now you no longer", "start": 1344.7, "duration": 4.36}, {"text": "have that conjugated double\nbond system, loses its color.", "start": 1349.06, "duration": 3.75}, {"text": "And so you can follow whether\nFAD is oxidized or reduced", "start": 1352.81, "duration": 3.78}, {"text": "by just looking at color change.", "start": 1356.59, "duration": 3.96}, {"text": "So, that's FAD.", "start": 1360.55, "duration": 1.95}, {"text": "It's an electron carrier,\ncarries electrons", "start": 1362.5, "duration": 3.39}, {"text": "by a hydride transfer,\nvery similarly", "start": 1365.89, "duration": 3.24}, {"text": "to what we described\nfor NAD, but obviously", "start": 1369.13, "duration": 3.24}, {"text": "a different molecule.", "start": 1372.37, "duration": 2.52}, {"text": "And the last molecule,\nthe last co-factor", "start": 1374.89, "duration": 4.11}, {"text": "that we need for this\nreaction, is lipoic acid.", "start": 1379.0, "duration": 6.91}, {"text": "Which, unlike most\nthings in metabolism,", "start": 1385.91, "duration": 2.31}, {"text": "doesn't have an abbreviation\nand also functions", "start": 1388.22, "duration": 4.62}, {"text": "as an electron carrier.", "start": 1392.84, "duration": 1.86}, {"text": "And so lipoic acid\nlooks like this.", "start": 1394.7, "duration": 2.34}, {"text": "So, that is lipoic acid.", "start": 1417.57, "duration": 3.24}, {"text": "This is in the oxidized form.", "start": 1420.81, "duration": 4.38}, {"text": "And so where it's\noxidized is here", "start": 1425.19, "duration": 2.91}, {"text": "at this sulfur-sulfur bond.", "start": 1428.1, "duration": 1.56}, {"text": "So, you can think of this as\nthe same as a disulfide bond", "start": 1429.66, "duration": 3.72}, {"text": "that you learned about from\nProfessor Yaffe in proteins.", "start": 1433.38, "duration": 3.73}, {"text": "And so this is the oxidized\nform of the disulfide bond.", "start": 1437.11, "duration": 4.28}, {"text": "If I take this hydride, transfer\ntwo electrons across that bond,", "start": 1441.39, "duration": 7.84}, {"text": "then it goes to-- and I'll\njust draw here the active end.", "start": 1449.23, "duration": 4.445}, {"text": "Then we go here to the\nreduced form of lipoic acid,", "start": 1459.37, "duration": 5.74}, {"text": "and there's no\nabbreviation for oxidized", "start": 1465.11, "duration": 2.91}, {"text": "or reduced lipoic acid.", "start": 1468.02, "duration": 1.68}, {"text": "It's just lipoic acid,\noxidized lipoic acid, reduced.", "start": 1469.7, "duration": 4.26}, {"text": "And how they're\noxidized and reduced", "start": 1473.96, "duration": 2.25}, {"text": "is basically very similar\nto the disulfide bonds", "start": 1476.21, "duration": 5.34}, {"text": "that you saw in proteins being\noxidized, disulfide bond being", "start": 1481.55, "duration": 5.22}, {"text": "oxidized, or it can be reduced\nto not be a disulfide bond.", "start": 1486.77, "duration": 5.58}, {"text": "Now, it turns out that these\ncofactors, our TPP, FAD,", "start": 1492.35, "duration": 10.41}, {"text": "and lipoic acid, are\nall stably associated", "start": 1502.76, "duration": 4.92}, {"text": "with different subunits\nof a multi-protein complex", "start": 1507.68, "duration": 6.38}, {"text": "that assembles to catalyze that\nreaction to convert pyruvate", "start": 1514.06, "duration": 6.24}, {"text": "to acetyl-CoA.", "start": 1520.3, "duration": 3.03}, {"text": "The enzyme or\nenzyme complex that", "start": 1523.33, "duration": 2.28}, {"text": "carries this out is\nreferred to as PDH,", "start": 1525.61, "duration": 3.6}, {"text": "sometimes abbreviated\nPDC, which stands", "start": 1529.21, "duration": 3.42}, {"text": "for the pyruvate\ndehydrogenase complex.", "start": 1532.63, "duration": 13.48}, {"text": "So, pyruvate dehydrogenase, PDH,\npyruvate dehydrogenase complex,", "start": 1546.11, "duration": 4.08}, {"text": "PDC.", "start": 1550.19, "duration": 1.6}, {"text": "This complex is basically\nthree different polypeptides", "start": 1551.79, "duration": 4.67}, {"text": "that come together\nto form a complex", "start": 1556.46, "duration": 2.19}, {"text": "and catalyze that reaction.", "start": 1558.65, "duration": 2.31}, {"text": "Now, where this complex sits--", "start": 1560.96, "duration": 2.65}, {"text": "so, this is the mitochondria.", "start": 1563.61, "duration": 2.03}, {"text": "This is the matrix.", "start": 1565.64, "duration": 2.13}, {"text": "That's where this pyruvate\ndehydrogenase reaction occurs.", "start": 1567.77, "duration": 2.76}, {"text": "That's where the\nTCA cycle occurs.", "start": 1570.53, "duration": 2.64}, {"text": "And this PDH\ncomplex is basically", "start": 1573.17, "duration": 2.46}, {"text": "sitting here at the\nmembrane on the matrix side", "start": 1575.63, "duration": 3.96}, {"text": "of the membrane.", "start": 1579.59, "duration": 2.86}, {"text": "Now, the three\ndifferent polypeptides", "start": 1582.45, "duration": 2.27}, {"text": "that come together\nto form this complex", "start": 1584.72, "duration": 2.25}, {"text": "are creatively named\nE1, E2, and E3, four.", "start": 1586.97, "duration": 8.04}, {"text": "Enzyme one, two, and three.", "start": 1595.01, "duration": 2.67}, {"text": "And each of these,\nas I alluded to,", "start": 1597.68, "duration": 3.33}, {"text": "is associated with a\ndifferent co-factor.", "start": 1601.01, "duration": 3.557}, {"text": "And so E1 is associated\nwith thymine pyrophosphate.", "start": 1609.71, "duration": 7.05}, {"text": "E2 is associated\nwith lipoic acid.", "start": 1616.76, "duration": 10.75}, {"text": "And E3 is associated with FAD.", "start": 1627.51, "duration": 5.165}, {"text": "Now, let's go\nthrough the mechanism", "start": 1637.09, "duration": 3.03}, {"text": "for how this pyruvate\ndehydrogenase reaction works.", "start": 1640.12, "duration": 5.225}, {"text": "So remember, this is the\nactive part of TBP plus.", "start": 1702.47, "duration": 5.48}, {"text": "It is bound in the\nactive site of E1.", "start": 1707.95, "duration": 4.5}, {"text": "And it reacts with pyruvate to\ncatalyze alpha decarboxylation,", "start": 1712.45, "duration": 11.15}, {"text": "just like we described\nfor conversion of pyruvate", "start": 1723.6, "duration": 4.95}, {"text": "to alcohol.", "start": 1728.55, "duration": 1.56}, {"text": "So, you're going to see\nexactly the same mechanism", "start": 1730.11, "duration": 3.69}, {"text": "that we drew before.", "start": 1733.8, "duration": 2.69}, {"text": "So, that decarboxylates\nthe alpha-keto acid,", "start": 1755.98, "duration": 4.47}, {"text": "just like we saw to\ngenerate acetaldehyde.", "start": 1760.45, "duration": 6.99}, {"text": "The difference is rather\nthan resolve this such", "start": 1773.39, "duration": 3.9}, {"text": "that this carbon has\nthe same oxidation state", "start": 1777.29, "duration": 2.49}, {"text": "and make acetaldehyde, instead\nthe next step of this reaction", "start": 1779.78, "duration": 4.74}, {"text": "is going to be oxidized\nby reducing lipoic acid.", "start": 1784.52, "duration": 11.71}, {"text": "So, the active\npart of lipoic acid", "start": 1796.23, "duration": 2.81}, {"text": "that is in the active\nsite of the E2 subunit.", "start": 1799.04, "duration": 5.49}, {"text": "So this will now regenerate\nE1, but what we're left with,", "start": 1880.75, "duration": 6.42}, {"text": "then, is this.", "start": 1887.17, "duration": 3.65}, {"text": "Now, this intermediate\nbound to E2.", "start": 1890.82, "duration": 3.99}, {"text": "Here's where coenzyme\nA can come in, which", "start": 1905.13, "duration": 9.04}, {"text": "will then generate acetyl-CoA.", "start": 1914.17, "duration": 10.09}, {"text": "But now we are left with\nE2 in the reduced state,", "start": 1927.65, "duration": 12.24}, {"text": "rather than being in\nthe oxidized state.", "start": 1939.89, "duration": 3.06}, {"text": "So E2 has to be re-oxidized\nin order for this complex", "start": 1942.95, "duration": 5.04}, {"text": "to carry out the next\ncatalytic cycle, and the way", "start": 1947.99, "duration": 4.83}, {"text": "that works is as follows.", "start": 1952.82, "duration": 2.31}, {"text": "So you have FAD bound on E3.", "start": 1955.13, "duration": 6.0}, {"text": "And so you have a hydride\nion from the oxidation of E3", "start": 1961.13, "duration": 13.42}, {"text": "that can be transferred to FAD.", "start": 1974.55, "duration": 3.57}, {"text": "That will generate FAD from the\noxidized to the reduced form.", "start": 1978.12, "duration": 9.38}, {"text": "So re-oxidize lipoic acid\non E2, reduce FAD to FADH2,", "start": 1987.5, "duration": 8.7}, {"text": "and then that FADH2\ncan be re-oxidized back", "start": 1996.2, "duration": 3.81}, {"text": "to FAD via transferring\nthose electrons to NAD", "start": 2000.01, "duration": 6.41}, {"text": "plus to generate NADH.", "start": 2006.42, "duration": 5.3}, {"text": "So in this case, FADH2\nre-oxidized the FAD, NAD", "start": 2011.72, "duration": 5.46}, {"text": "plus reduced to NADH.", "start": 2017.18, "duration": 3.9}, {"text": "And so, effectively,\nwhat this happens", "start": 2021.08, "duration": 3.33}, {"text": "is that enzyme E1\nand E2 cooperate", "start": 2024.41, "duration": 4.68}, {"text": "to call what's referred to as\noxidative alpha decarboxylation", "start": 2029.09, "duration": 13.74}, {"text": "of pyruvate, while\nadding -CoA, so that's", "start": 2042.83, "duration": 4.26}, {"text": "where you get acetyl-CoA, with\nreduction of lipoic acid in E2,", "start": 2047.09, "duration": 8.0}, {"text": "and then E3 re-oxidizes\nthe lipoic acid in E2", "start": 2055.09, "duration": 5.28}, {"text": "while generating NADH.", "start": 2060.37, "duration": 4.039}, {"text": "This NADH, once it's\ngenerated, of course", "start": 2064.409, "duration": 2.268}, {"text": "those electrons have\nto go somewhere,", "start": 2066.677, "duration": 1.542}, {"text": "so they, like in glycolysis--", "start": 2068.219, "duration": 2.19}, {"text": "it also needs to regenerate\nto NAD at some point.", "start": 2070.409, "duration": 3.48}, {"text": "This is ultimately the\nelectrons that end up on oxygen,", "start": 2073.889, "duration": 4.231}, {"text": "and it's really this series\nof electron transfers,", "start": 2078.12, "duration": 4.47}, {"text": "with oxygen being a good\nelectron acceptor, that", "start": 2082.59, "duration": 2.91}, {"text": "ultimately allows controlled\nenergy release during carbon", "start": 2085.5, "duration": 5.07}, {"text": "oxidation.", "start": 2090.57, "duration": 1.169}, {"text": "And cells, you'll see, can\nuse that to make ATP or do", "start": 2091.739, "duration": 3.331}, {"text": "other kinds of work.", "start": 2095.07, "duration": 3.87}, {"text": "So, the net reaction\nand/or another way", "start": 2098.94, "duration": 3.78}, {"text": "to draw the pyruvate\ndehydrogenase reaction", "start": 2102.72, "duration": 4.44}, {"text": "would be as follows, and that's\ntaking pyruvate to acetyl-CoA.", "start": 2107.16, "duration": 8.23}, {"text": "And so we're going to take\ncoenzyme A and release CO2.", "start": 2118.89, "duration": 9.09}, {"text": "This is done by TPP\nplus, as part of E1.", "start": 2127.98, "duration": 14.52}, {"text": "That involves converting\nthe lipoic acid in E2", "start": 2142.5, "duration": 10.16}, {"text": "from the oxidized to\nthe reduced state.", "start": 2152.66, "duration": 3.42}, {"text": "That lipoic acid then\nhas to be re-oxidized.", "start": 2156.08, "duration": 4.05}, {"text": "If something's\noxidized, something else", "start": 2160.13, "duration": 2.13}, {"text": "has to be reduced.", "start": 2162.26, "duration": 1.53}, {"text": "That's FAD on E3,\nwhich also then cycles", "start": 2163.79, "duration": 6.3}, {"text": "between the oxidized\nand reduce state.", "start": 2170.09, "duration": 3.93}, {"text": "And ultimately, those\nelectrons ended up", "start": 2174.02, "duration": 3.42}, {"text": "being transferred to NAD\nplus to generate NADH.", "start": 2177.44, "duration": 6.57}, {"text": "And so the PDH complex\nis basically a chain", "start": 2184.01, "duration": 8.37}, {"text": "of electron transfer reactions.", "start": 2192.38, "duration": 8.63}, {"text": "And it's the first example of\na chain of electron transfer", "start": 2201.01, "duration": 4.68}, {"text": "reactions.", "start": 2205.69, "duration": 0.54}, {"text": "We're going to see that there\nis the electron transport", "start": 2206.23, "duration": 2.4}, {"text": "chain in the mitochondria,\neffectively does", "start": 2208.63, "duration": 3.27}, {"text": "the same thing.", "start": 2211.9, "duration": 0.97}, {"text": "And by coupling oxidation\nand reduction reactions", "start": 2212.87, "duration": 3.53}, {"text": "across chains of molecules like\nthis, effectively as a preview,", "start": 2216.4, "duration": 4.08}, {"text": "allows the stepwise energy\nrelease of these oxidation", "start": 2220.48, "duration": 3.45}, {"text": "reactions to occur.", "start": 2223.93, "duration": 4.24}, {"text": "So remember, if we burn glucose,\ncompletely oxidize it in one", "start": 2228.17, "duration": 3.38}, {"text": "step, where those electrons\nare directly transferred", "start": 2231.55, "duration": 2.2}, {"text": "to oxygen in combustion.", "start": 2233.75, "duration": 1.76}, {"text": "Lots of energy released,\nbut all in one step.", "start": 2235.51, "duration": 3.21}, {"text": "By doing these stepwise\nelectron transfers,", "start": 2238.72, "duration": 2.49}, {"text": "we can then basically break\nup that energy release", "start": 2241.21, "duration": 3.9}, {"text": "in a way that can be\ncaptured by cells to do work.", "start": 2245.11, "duration": 4.08}, {"text": "Here, the way\nenergy is captured,", "start": 2249.19, "duration": 1.86}, {"text": "it's not so obvious in this\nelectron transport reaction.", "start": 2251.05, "duration": 3.81}, {"text": "But effectively,\nyou're using oxidation", "start": 2254.86, "duration": 3.72}, {"text": "of the ketone on pyruvate, with\ndecarboxylation to the acid", "start": 2258.58, "duration": 8.19}, {"text": "to generate, rather than just\nthe acid, a thioester bond.", "start": 2266.77, "duration": 3.63}, {"text": "And that's that thioester bond--", "start": 2270.4, "duration": 2.07}, {"text": "as well as NADH, that's\nenergy as well-- but it's", "start": 2272.47, "duration": 2.64}, {"text": "really that thioester bond that\nthen can be recaptured later", "start": 2275.11, "duration": 3.51}, {"text": "to drive synthesis of\ncitrate in the TCA cycle.", "start": 2278.62, "duration": 4.8}, {"text": "Now, next what I want to do is\nI want to discuss the TCA cycle", "start": 2286.48, "duration": 5.49}, {"text": "reactions.", "start": 2291.97, "duration": 0.63}, {"text": "Now that you see how you\ncan get acetyl-CoA, at least", "start": 2292.6, "duration": 2.82}, {"text": "from pyruvate, I want to\ndiscuss how you can now", "start": 2295.42, "duration": 3.03}, {"text": "use that acetyl-CoA and\noxidize it back to combine it", "start": 2298.45, "duration": 5.46}, {"text": "with oxaloacetate,\nand oxidize it back", "start": 2303.91, "duration": 4.05}, {"text": "to make citrate, and then\noxidize it back to oxaloacetate", "start": 2307.96, "duration": 3.39}, {"text": "to run the TCA cycle.", "start": 2311.35, "duration": 4.14}, {"text": "OK, great.", "start": 2315.49, "duration": 2.47}, {"text": "So, the first reaction\nof the TCA cycle.", "start": 2317.96, "duration": 16.16}, {"text": "Here's acetyl-CoA.", "start": 2334.12, "duration": 5.97}, {"text": "It will combine\nwith oxaloacetate.", "start": 2340.09, "duration": 13.44}, {"text": "This reaction is catalyzed by an\nenzyme called citrate synthase,", "start": 2366.42, "duration": 31.71}, {"text": "and generates the six-carbon\ntricarboxylic acid citrate.", "start": 2398.13, "duration": 7.35}, {"text": "So, how does this reaction work?", "start": 2405.48, "duration": 3.86}, {"text": "Here's drawing acetyl-CoA\nin a slightly different way.", "start": 2447.99, "duration": 4.93}, {"text": "If I redraw this\nas the enol, this", "start": 2452.92, "duration": 32.7}, {"text": "will generate citrate via,\neffectively, that mechanism.", "start": 2485.62, "duration": 60.72}, {"text": "Next, citrate is\nconverted by adding water", "start": 2549.61, "duration": 12.99}, {"text": "across this carbon-carbon,\nor by removing water", "start": 2562.6, "duration": 5.85}, {"text": "across this carbon-carbon\nbond, to generate", "start": 2568.45, "duration": 8.34}, {"text": "this intermediate\ncalled cis-aconitate.", "start": 2576.79, "duration": 2.47}, {"text": "So this intermediate is\ncalled cis-aconitate.", "start": 2611.989, "duration": 2.671}, {"text": "so all I did was\ndehydrate across that bond", "start": 2618.26, "duration": 3.18}, {"text": "so there's a double bond there.", "start": 2621.44, "duration": 1.9}, {"text": "And then if I re-add\nwater across that bond,", "start": 2623.34, "duration": 12.84}, {"text": "I generate this molecule\ncalled isocitrate.", "start": 2636.18, "duration": 23.46}, {"text": "So effectively, to convert\ncitrate to isocitrate,", "start": 2662.24, "duration": 4.26}, {"text": "I'm moving the hydroxyl\ngroup from that carbon", "start": 2666.5, "duration": 3.48}, {"text": "to this carbon.", "start": 2669.98, "duration": 1.65}, {"text": "To do that, I basically\ndehydrate, make a double bond,", "start": 2671.63, "duration": 4.13}, {"text": "remove water, re-add\nwater across that bond", "start": 2675.76, "duration": 2.95}, {"text": "in the opposite direction\nto generate this molecule,", "start": 2678.71, "duration": 3.24}, {"text": "isocitrate.", "start": 2681.95, "duration": 1.6}, {"text": "This reaction is carried out\nby an enzyme called aconitase,", "start": 2683.55, "duration": 16.66}, {"text": "and converts citrate\nto isocitrate.", "start": 2700.21, "duration": 5.3}, {"text": "I think it's a little\neasier to see this reaction", "start": 2705.51, "duration": 5.31}, {"text": "if I draw it a\nslightly different way.", "start": 2710.82, "duration": 2.27}, {"text": "So, this here is\njust drawing citrate", "start": 2772.59, "duration": 2.3}, {"text": "by just slightly rotating the\nmolecule to look like that.", "start": 2774.89, "duration": 6.67}, {"text": "And so I'm basically\nremoving water here.", "start": 2781.56, "duration": 2.93}, {"text": "And then I'm now just\nadding water back", "start": 2811.04, "duration": 6.06}, {"text": "in the opposite orientation\nto generate isocitrate.", "start": 2817.1, "duration": 23.75}, {"text": "Now, you'll notice\nwhen I drew this--", "start": 2848.83, "duration": 4.47}, {"text": "if you look at citrate, this\nis actually a symmetrical", "start": 2853.3, "duration": 3.6}, {"text": "molecule, so the top half and\nthe bottom half of citrate", "start": 2856.9, "duration": 6.48}, {"text": "are identical.", "start": 2863.38, "duration": 2.32}, {"text": "And so what's interesting\nabout nature is", "start": 2865.7, "duration": 3.71}, {"text": "that it treats these carbons--", "start": 2869.41, "duration": 2.1}, {"text": "the green carbons that\ncame from acetyl-CoA--", "start": 2871.51, "duration": 2.55}, {"text": "different from the side\nof the molecule that", "start": 2874.06, "duration": 3.21}, {"text": "comes from oxaloacetate.", "start": 2877.27, "duration": 2.94}, {"text": "And effectively, nature always\nmoves the hydroxyl group", "start": 2880.21, "duration": 5.16}, {"text": "to this carbon that\ncame from oxaloacetate,", "start": 2885.37, "duration": 3.45}, {"text": "and never moves\nit to this carbon", "start": 2888.82, "duration": 2.85}, {"text": "that came from acetyl-CoA.", "start": 2891.67, "duration": 3.6}, {"text": "This is an example\nwhere enzymes--", "start": 2895.27, "duration": 2.97}, {"text": "nature treats a symmetrical\nmolecule like citrate", "start": 2898.24, "duration": 4.71}, {"text": "in an asymmetrical way.", "start": 2902.95, "duration": 2.13}, {"text": "And this has consequences for\nhow carbon is actually traced", "start": 2905.08, "duration": 4.83}, {"text": "through the entire TCA cycle.", "start": 2909.91, "duration": 2.49}, {"text": "Because even though you\nmight think things could get", "start": 2912.4, "duration": 2.19}, {"text": "scrambled at citrate,\nthey never do.", "start": 2914.59, "duration": 2.64}, {"text": "Meaning an isocitrate-- it's\nalways these green carbons", "start": 2917.23, "duration": 4.35}, {"text": "that came from acetyl-CoA.", "start": 2921.58, "duration": 1.74}, {"text": "You never get\nthose green carbons", "start": 2923.32, "duration": 1.86}, {"text": "on the other side of isocitrate.", "start": 2925.18, "duration": 3.78}, {"text": "And so when we go\nthrough the TCA cycle,", "start": 2928.96, "duration": 2.01}, {"text": "I'll keep these carbons\ngreen until the point where", "start": 2930.97, "duration": 3.06}, {"text": "you can no longer distinguish\nwhich carbon came from", "start": 2934.03, "duration": 4.26}, {"text": "came from which reaction.", "start": 2938.29, "duration": 1.295}, {"text": "The next reaction is\nwe're going to oxidize", "start": 2942.16, "duration": 5.58}, {"text": "this carbon of isocitrate.", "start": 2947.74, "duration": 4.29}, {"text": "So if we're going to\noxidize that carbon,", "start": 2952.03, "duration": 2.52}, {"text": "those electrons have\nto go somewhere.", "start": 2954.55, "duration": 2.82}, {"text": "And so if we oxidize\nthe carbon, we", "start": 2976.31, "duration": 3.84}, {"text": "can use NAD plus as an electron\nacceptor, reduce it to NADH.", "start": 2980.15, "duration": 9.09}, {"text": "That generates\nthis intermediate.", "start": 2989.24, "duration": 9.01}, {"text": "So hopefully this is clear\nto everybody at this point,", "start": 3020.46, "duration": 3.48}, {"text": "but just in case.", "start": 3023.94, "duration": 2.21}, {"text": "So, this carbon\nhere and isocitrate.", "start": 3029.23, "duration": 5.33}, {"text": "If I oxidize that\nalcohol to the ketone,", "start": 3034.56, "duration": 15.01}, {"text": "now I generate a hydride ion.", "start": 3049.57, "duration": 2.04}, {"text": "Those two electrons and the\nhydrogen can go to NAD plus", "start": 3051.61, "duration": 2.67}, {"text": "and reduce it to NADH.", "start": 3054.28, "duration": 2.79}, {"text": "That generates\nthis intermediate.", "start": 3057.07, "duration": 2.52}, {"text": "It's called oxalosuccinate.", "start": 3062.43, "duration": 3.79}, {"text": "Which then, if you\nnotice, the oxalosuccinate", "start": 3066.22, "duration": 5.64}, {"text": "is now a beta keto acid.", "start": 3071.86, "duration": 4.56}, {"text": "So alpha, beta.", "start": 3076.42, "duration": 6.0}, {"text": "The acid group is\nbeta to the ketone,", "start": 3082.42, "duration": 3.31}, {"text": "so it's a beta keto acid.", "start": 3085.73, "duration": 1.95}, {"text": "Remember, beta\ndecarboxylation is favorable,", "start": 3087.68, "duration": 4.59}, {"text": "and so I can lose that CO2.", "start": 3092.27, "duration": 3.59}, {"text": "And what I'm left with\nis this molecule, which", "start": 3095.86, "duration": 19.31}, {"text": "is called alpha keto glutarate.", "start": 3115.17, "duration": 10.93}, {"text": "So this whole reaction\nhere, the oxidation", "start": 3126.1, "duration": 8.27}, {"text": "of the alcohol to\nthe ketone, followed", "start": 3134.37, "duration": 2.22}, {"text": "by beta decarboxylation\nof oxalosuccinate", "start": 3136.59, "duration": 3.42}, {"text": "to alpha ketoglutarate,\nis carried out", "start": 3140.01, "duration": 2.55}, {"text": "by an enzyme called\nisocitrate dehydrogenase.", "start": 3142.56, "duration": 6.12}, {"text": "And of course,\njust to remind you,", "start": 3154.31, "duration": 16.352}, {"text": "here's that beta keto\nacid in oxalosuccinate.", "start": 3170.662, "duration": 7.998}, {"text": "And so that can decarboxylate,\nleading this enol.", "start": 3184.51, "duration": 16.06}, {"text": "Which can, of course, rearrange\nback to the ketone that we see,", "start": 3200.57, "duration": 15.23}, {"text": "an alpha ketoglutarate.", "start": 3215.8, "duration": 6.45}, {"text": "Now, if you look at\nalpha ketoglutarate,", "start": 3222.25, "duration": 7.46}, {"text": "you'll notice that-- and\nI will redraw over here.", "start": 3229.71, "duration": 7.155}, {"text": "So, this here is just me\nredrawing alpha ketoglutarate,", "start": 3251.94, "duration": 6.69}, {"text": "which is often\nabbreviated alpha kG.", "start": 3258.63, "duration": 5.33}, {"text": "Just drew it as a straight line.", "start": 3263.96, "duration": 2.41}, {"text": "Now, if you'll notice,\nalpha keto glutarate", "start": 3266.37, "duration": 2.93}, {"text": "is a alpha ketoacid.", "start": 3269.3, "duration": 3.45}, {"text": "And so here the acid group\nis alpha to the ketone.", "start": 3272.75, "duration": 4.87}, {"text": "So, an alpha keto acid.", "start": 3277.62, "duration": 2.0}, {"text": "It's effectively\njust like pyruvate,", "start": 3279.62, "duration": 2.55}, {"text": "but has this additional\npieces on it.", "start": 3282.17, "duration": 2.94}, {"text": "And it turns out the next\nstep in the TCA cycle", "start": 3285.11, "duration": 3.63}, {"text": "is the exact\nreaction that we saw", "start": 3288.74, "duration": 4.08}, {"text": "with pyruvate dehydrogenase.", "start": 3292.82, "duration": 3.42}, {"text": "It's alpha decarboxylation,\noxidative alpha", "start": 3296.24, "duration": 5.01}, {"text": "keto acid decarboxylation,\nas follows.", "start": 3301.25, "duration": 21.03}, {"text": "So, we carry out.", "start": 3322.28, "duration": 2.81}, {"text": "This is a molecule\ncalled succinyl-CoA.", "start": 3357.15, "duration": 7.56}, {"text": "And so, you'll see what happened\nthere is decarboxylated here,", "start": 3364.71, "duration": 6.12}, {"text": "this carbon, while oxidizing\nthis ketone to the acid", "start": 3370.83, "duration": 7.2}, {"text": "and adding -CoA.", "start": 3378.03, "duration": 1.77}, {"text": "That's a redox reaction.", "start": 3379.8, "duration": 1.6}, {"text": "So NAD, NADH, it turns out this\nis exactly the same mechanism--", "start": 3381.4, "duration": 7.43}, {"text": "so I don't need\nto draw it again--", "start": 3388.83, "duration": 1.53}, {"text": "that I just showed you for\npyruvate dehydrogenase.", "start": 3390.36, "duration": 4.38}, {"text": "So it needs all the\nsame cofactors--", "start": 3394.74, "duration": 1.98}, {"text": "TPP plus, lipoic acid, FAD.", "start": 3396.72, "duration": 4.05}, {"text": "And in fact, it even shares some\nof the same enzyme complexes,", "start": 3400.77, "duration": 6.24}, {"text": "subunits, as pyruvate\ndehydrogenase.", "start": 3407.01, "duration": 4.71}, {"text": "And so this is a reaction\nthat's catalyzed by alpha", "start": 3411.72, "duration": 5.61}, {"text": "ketoglutarate dehydrogenase.", "start": 3417.33, "duration": 2.13}, {"text": "Like pyruvate dehydrogenase,\nthis is a complex,", "start": 3422.52, "duration": 3.69}, {"text": "and so it has a unique\nE1, which makes sense.", "start": 3426.21, "duration": 3.44}, {"text": "Remember, E1 of\npyruvate dehydrogenase", "start": 3429.65, "duration": 2.35}, {"text": "was actually the subunit\nthat bound the pyruvate.", "start": 3432.0, "duration": 3.03}, {"text": "E1 of alpha ketoglutarate\ndehydrogenase is unique.", "start": 3435.03, "duration": 2.79}, {"text": "It binds alpha ketoglutarate\ninstead of pyruvate.", "start": 3437.82, "duration": 2.58}, {"text": "However, they share\nthe same E2 and E3s,", "start": 3440.4, "duration": 4.35}, {"text": "and so the E2s and\nE3s would carry out", "start": 3444.75, "duration": 3.39}, {"text": "exactly the same reaction\nand play the same part", "start": 3448.14, "duration": 4.2}, {"text": "in the mechanism of how you\ndo this alpha oxidative alpha", "start": 3452.34, "duration": 6.06}, {"text": "decarboxylation to turn\nalpha ketoglutarate", "start": 3458.4, "duration": 2.7}, {"text": "into succinyl-CoA.", "start": 3461.1, "duration": 4.23}, {"text": "Now, remember in\npyruvate dehydrogenase,", "start": 3465.33, "duration": 2.01}, {"text": "once we got that\nacetyl-CoA, we then", "start": 3467.34, "duration": 1.77}, {"text": "use this CoA group to drive\ncondensation with citrate.", "start": 3469.11, "duration": 3.57}, {"text": "Well, in this case,\nwhat happens is", "start": 3472.68, "duration": 1.86}, {"text": "you don't want to combine\ncondensation here.", "start": 3474.54, "duration": 3.57}, {"text": "Instead, what is\ngoing to happen is", "start": 3478.11, "duration": 2.58}, {"text": "you want to use this CoA\ngroup to now generate ATP.", "start": 3480.69, "duration": 7.47}, {"text": "And so this is going to\ncouple release of the CoA", "start": 3488.16, "duration": 7.05}, {"text": "to generate an ATP equivalent.", "start": 3495.21, "duration": 2.22}, {"text": "It's actually GTP that's\ngenerated by the TCA cycle.", "start": 3497.43, "duration": 5.32}, {"text": "And so, this is\ngoing to generate", "start": 3502.75, "duration": 11.88}, {"text": "this molecule, succinate.", "start": 3514.63, "duration": 4.86}, {"text": "And the enzyme that does this\nis called succinic bio-kinase.", "start": 3519.49, "duration": 8.3}, {"text": "So, let's go through over\nhere how this enzyme works.", "start": 3536.93, "duration": 4.275}, {"text": "So here's succinyl-CoA,\nbasically using favorable loss", "start": 3552.8, "duration": 12.15}, {"text": "of the CoA breaking the\nthioester bond to generate", "start": 3564.95, "duration": 15.97}, {"text": "this acid anhydride.", "start": 3580.92, "duration": 1.83}, {"text": "We saw an acid anhydride\nbefore in glycolysis.", "start": 3582.75, "duration": 5.4}, {"text": "Remember, we made\n1-3-bisphosphoglycerate,", "start": 3588.15, "duration": 2.91}, {"text": "so that's a good\nphosphate donor.", "start": 3591.06, "duration": 3.12}, {"text": "And then that can be used\nto generate succinate,", "start": 3594.18, "duration": 4.93}, {"text": "and transferring that\nphosphate to GDP to make GTP,", "start": 3599.11, "duration": 6.45}, {"text": "just like\n1-3-bisphosphoglycerate,", "start": 3605.56, "duration": 3.06}, {"text": "was able to transfer\nthe phosphate", "start": 3608.62, "duration": 1.8}, {"text": "from the acid anhydride to\nADP to make ATP in glycolysis.", "start": 3610.42, "duration": 7.95}, {"text": "So, the next step is to\noxidize this carbon-carbon bond", "start": 3620.95, "duration": 13.54}, {"text": "in succinate.", "start": 3634.49, "duration": 2.91}, {"text": "So if we're going to oxidize\na carbon-carbon bond,", "start": 3637.4, "duration": 4.29}, {"text": "those electrons have\nto go somewhere.", "start": 3641.69, "duration": 2.4}, {"text": "So there's our\ncarbon-carbon bond.", "start": 3650.67, "duration": 3.12}, {"text": "And so if we\ngenerate hydride ion", "start": 3661.67, "duration": 11.53}, {"text": "just like we did in other\noxidation reactions,", "start": 3673.2, "duration": 5.07}, {"text": "but this hydride ion is\ntransferred not to NAD,", "start": 3678.27, "duration": 5.61}, {"text": "but instead to FAD, a\ndifferent electron carrier,", "start": 3683.88, "duration": 6.63}, {"text": "to generate if FADH2.", "start": 3690.51, "duration": 4.17}, {"text": "Now, I should point out\nsuccinate, like citrate, is", "start": 3694.68, "duration": 3.69}, {"text": "a symmetrical molecule.", "start": 3698.37, "duration": 1.68}, {"text": "But at this point, nature\ndoesn't tell the difference.", "start": 3700.05, "duration": 3.63}, {"text": "Once it generates\nsuccinate, this molecule", "start": 3703.68, "duration": 3.76}, {"text": "now gets scrambled.", "start": 3707.44, "duration": 1.31}, {"text": "And so everything\ndownstream of succinate,", "start": 3708.75, "duration": 2.58}, {"text": "you no longer know which\ncarbons came from acetyl-CoA.", "start": 3711.33, "duration": 3.42}, {"text": "This generates this\nmolecule called fumarate,", "start": 3725.77, "duration": 4.77}, {"text": "and this reaction is carried\nout by an enzyme called", "start": 3730.54, "duration": 8.48}, {"text": "succinate dehydrogenase,\noften abbreviated SDH", "start": 3739.02, "duration": 13.0}, {"text": "for succinate dehydrogenase.", "start": 3752.02, "duration": 2.55}, {"text": "Now, the next reaction\nis, we're going", "start": 3757.85, "duration": 7.05}, {"text": "to add water across this\ndouble bond of fumarate.", "start": 3764.9, "duration": 5.62}, {"text": "And that generates this\nintermediate, malate.", "start": 3808.27, "duration": 5.425}, {"text": "This reaction is\ncarried out by an enzyme", "start": 3817.95, "duration": 4.68}, {"text": "called fumarate hydratase.", "start": 3822.63, "duration": 9.3}, {"text": "And it's simply adding\na water molecule", "start": 3831.93, "duration": 3.39}, {"text": "across that double bond.", "start": 3835.32, "duration": 3.15}, {"text": "Once we have malate,\nif you look what's", "start": 3838.47, "duration": 3.24}, {"text": "the difference between\nmalate and oxaloacetate,", "start": 3841.71, "duration": 4.74}, {"text": "the difference is that in\noxaloacetate, this carbon", "start": 3846.45, "duration": 5.1}, {"text": "is a ketone.", "start": 3851.55, "duration": 1.41}, {"text": "Whereas in malate,\nit's an alcohol.", "start": 3852.96, "duration": 2.43}, {"text": "And so if we want to turn\nthis carbon from the alcohol", "start": 3855.39, "duration": 2.76}, {"text": "into the ketone, that is, of\ncourse, a oxidation reaction,", "start": 3858.15, "duration": 6.34}, {"text": "and so those electrons\nhave to go somewhere.", "start": 3864.49, "duration": 7.98}, {"text": "Don't need to draw\nthe mechanism again.", "start": 3872.47, "duration": 4.32}, {"text": "It's basically just\nthe hydride transfer", "start": 3876.79, "duration": 4.29}, {"text": "to oxidize this to an\nalcohol, to the ketone.", "start": 3881.08, "duration": 4.64}, {"text": "That oxidation couples to a\nreduction of NAD plus to NADH.", "start": 3885.72, "duration": 5.46}, {"text": "This is carried out by an enzyme\ncalled malate dehydrogenase.", "start": 3891.18, "duration": 6.913}, {"text": "And doing this\ncompletes the TCA cycle,", "start": 3907.19, "duration": 5.79}, {"text": "regenerating oxaloacetate,\nthat can then", "start": 3912.98, "duration": 3.18}, {"text": "recombine with\nanother acetyl-CoA", "start": 3916.16, "duration": 2.52}, {"text": "to go through another\nround of the cycle.", "start": 3918.68, "duration": 5.52}, {"text": "You'll notice that going\nthrough this cycle,", "start": 3924.2, "duration": 4.5}, {"text": "there's two CO2s lost.", "start": 3928.7, "duration": 3.39}, {"text": "One of them is lost here\nat the isocitrate to alpha", "start": 3932.09, "duration": 6.93}, {"text": "ketoglutarate reaction.", "start": 3939.02, "duration": 1.84}, {"text": "So, this decarboxylation\nfrom oxaloacetate", "start": 3940.86, "duration": 4.555}, {"text": "to alpha ketoglutarate.", "start": 3945.415, "duration": 1.255}, {"text": "That beta decarboxylation,\nthat's the first CO2.", "start": 3946.67, "duration": 3.33}, {"text": "The other one is lost here\nat the alpha ketoglutarate.", "start": 3950.0, "duration": 3.405}, {"text": "The alpha ketoglutarate\ndehydrogenase step,", "start": 3957.37, "duration": 2.73}, {"text": "where you have this\nalpha decarboxylation", "start": 3960.1, "duration": 3.87}, {"text": "to take alpha ketoglutarate\nto succinyl-CoA", "start": 3963.97, "duration": 3.57}, {"text": "oxidative alpha decarboxylation.", "start": 3967.54, "duration": 4.74}, {"text": "Now, what's cool about\nthis, as you noticed,", "start": 3972.28, "duration": 3.39}, {"text": "we just discussed all the\nreactions of the TCA cycle.", "start": 3975.67, "duration": 5.1}, {"text": "And I showed you, reminded\nyou, of some chemistry", "start": 3980.77, "duration": 2.69}, {"text": "that you've already\nseen, but unless you", "start": 3983.46, "duration": 2.55}, {"text": "count the chemistry we showed\nyou earlier for how the PDH", "start": 3986.01, "duration": 3.465}, {"text": "and alpha ketoglutarate\ndehydrogenase", "start": 3989.475, "duration": 1.875}, {"text": "reactions work with E1, E2\nand E3, with lipoic acid, FAD.", "start": 3991.35, "duration": 4.26}, {"text": "That was obviously\nnew for today.", "start": 3995.61, "duration": 1.69}, {"text": "But other than that,\neverything else", "start": 3997.3, "duration": 2.3}, {"text": "was chemistry that\nyou've already seen.", "start": 3999.6, "duration": 2.64}, {"text": "And this really\npoints out the point", "start": 4002.24, "duration": 1.65}, {"text": "that I made earlier, that\nmetabolism is really variations", "start": 4003.89, "duration": 3.57}, {"text": "on relatively few reactions.", "start": 4007.46, "duration": 1.77}, {"text": "We've just repurposed some of\nthe same tricks, if you will,", "start": 4009.23, "duration": 3.4}, {"text": "that we're used in\nglycolysis, and allowed", "start": 4012.63, "duration": 3.07}, {"text": "it to now do an entire different\npathway, the TCA cycle.", "start": 4015.7, "duration": 4.39}, {"text": "It also points out how Hans\nKrebs was-- well, is still--", "start": 4020.09, "duration": 2.78}, {"text": "remarkable, able to figure\nout from chemistry alone,", "start": 4022.87, "duration": 3.66}, {"text": "because there's actually quite\na bit of logic to the way", "start": 4026.53, "duration": 2.88}, {"text": "metabolism works.", "start": 4029.41, "duration": 2.62}, {"text": "Now, I want to say this again.", "start": 4032.03, "duration": 1.25}, {"text": "Note there were two carbons\nthat entered acetyl-CoA,", "start": 4033.28, "duration": 3.0}, {"text": "and two carbons that\nwere lost to CO2.", "start": 4036.28, "duration": 3.77}, {"text": "But if you look,\nthe green carbons", "start": 4040.05, "duration": 2.64}, {"text": "remain in the same places\nuntil they get to succinate.", "start": 4042.69, "duration": 4.5}, {"text": "and so the two\ncarbons that enter", "start": 4047.19, "duration": 2.13}, {"text": "are not lost on the\nfirst turn of the cycle.", "start": 4049.32, "duration": 3.03}, {"text": "It's actually two carbons\nthat came from oxaloacetate", "start": 4052.35, "duration": 5.46}, {"text": "that are converted to CO2\nas that acetyl-CoA goes", "start": 4057.81, "duration": 4.41}, {"text": "through the cycle.", "start": 4062.22, "duration": 1.12}, {"text": "And so to oxidize the exact\ncarbons from acetyl-CoA to CO2", "start": 4063.34, "duration": 4.58}, {"text": "requires more than\none turn of the cycle.", "start": 4067.92, "duration": 5.3}, {"text": "You'll also notice that\nthe cycle is oxidation.", "start": 4073.22, "duration": 4.44}, {"text": "And so oxidation reactions,\nof course, release energy.", "start": 4077.66, "duration": 4.01}, {"text": "We've talked about that.", "start": 4081.67, "duration": 1.0}, {"text": "And so it's favorable.", "start": 4082.67, "duration": 2.4}, {"text": "And the products, if you will,\nare three NADH molecules.", "start": 4085.07, "duration": 6.965}, {"text": "You can say plus one more NADH\nif we're going all the way", "start": 4092.035, "duration": 4.465}, {"text": "from glucose or from pyruvate.", "start": 4096.5, "duration": 4.529}, {"text": "Glucose derived pyruvate because\nthe pyruvate dehydrogenase", "start": 4101.029, "duration": 3.091}, {"text": "reaction also generates an\nNADH to make that a acetyl-CoA.", "start": 4104.12, "duration": 5.529}, {"text": "One FADH2, as well\nas one GTP molecule.", "start": 4109.649, "duration": 8.71}, {"text": "And so lots of\noxidation going on here.", "start": 4118.359, "duration": 3.21}, {"text": "We completely oxidized\ntwo carbons to CO2,", "start": 4121.569, "duration": 2.781}, {"text": "so that's energy release.", "start": 4124.35, "duration": 2.879}, {"text": "But you notice you only get\none GTP from the molecule.", "start": 4127.229, "duration": 5.05}, {"text": "Now, this GTP, of\ncourse-- that reaction,", "start": 4132.279, "duration": 3.231}, {"text": "the succinic\nthiokinase reaction,", "start": 4135.51, "duration": 2.429}, {"text": "like the reactions\nwe saw on glycolysis,", "start": 4137.939, "duration": 2.071}, {"text": "is such that it can generate\nGTP at a high DGP-GDP", "start": 4140.01, "duration": 4.53}, {"text": "ratio, or ATP-ADP ratio.", "start": 4144.54, "duration": 1.678}, {"text": "Remember, those are equivalent.", "start": 4146.218, "duration": 1.292}, {"text": "Those energy charge are similar,\nand so that makes sense.", "start": 4147.51, "duration": 3.389}, {"text": "But most of the energy\nreleased is actually", "start": 4150.899, "duration": 4.351}, {"text": "reducing NAD and FAD\nto NADH and FADH2.", "start": 4155.25, "duration": 4.71}, {"text": "And of course, these need\nto transfer their electrons", "start": 4159.96, "duration": 5.34}, {"text": "somewhere else, and\nthat's the role of oxygen.", "start": 4165.3, "duration": 3.12}, {"text": "Oxygen, remember, is a\nvery good electron donor,", "start": 4168.42, "duration": 2.83}, {"text": "and so it's the ultimate\ntransfer of those electrons", "start": 4171.25, "duration": 3.229}, {"text": "from these molecules to oxygen\nthat also provide energy", "start": 4174.479, "duration": 6.271}, {"text": "that the cell can use to do\nwork, but it does so, in a way,", "start": 4180.75, "duration": 3.99}, {"text": "by charging up different\nratios in the cell.", "start": 4184.74, "duration": 5.17}, {"text": "So the NAD-NADH or\nthe FADH2-FAD ratios.", "start": 4189.91, "duration": 6.92}, {"text": "And just like we talked about,\nthe ratio or the energy of ATP", "start": 4196.83, "duration": 5.19}, {"text": "is in the interconversion\nbetween ATP and ADP.", "start": 4202.02, "duration": 3.15}, {"text": "It's the ratio that drives\nthe free energy change.", "start": 4205.17, "duration": 4.02}, {"text": "The same thing exists for an\nNADH and NAD, FADH2 and FAD.", "start": 4209.19, "duration": 4.59}, {"text": "And so charging up these ratios\nwhile passing through the TCA", "start": 4213.78, "duration": 3.21}, {"text": "cycle, and the ultimate\ndownstream transfer", "start": 4216.99, "duration": 2.82}, {"text": "of those electrons\nto oxygen, really", "start": 4219.81, "duration": 2.73}, {"text": "is where most of the energy\nis captured as carbon", "start": 4222.54, "duration": 4.11}, {"text": "is oxidized through\nthe TCA cycle.", "start": 4226.65, "duration": 3.57}, {"text": "And exactly how that works and\nhow it can be related to ATP", "start": 4230.22, "duration": 4.86}, {"text": "will be something that'll be\nmore explicit in the coming", "start": 4235.08, "duration": 2.67}, {"text": "lectures.", "start": 4237.75, "duration": 1.55}, {"text": "Now, I want to point out\napart from the oxidation,", "start": 4239.3, "duration": 3.9}, {"text": "there's actually lots of\nintermediates made here.", "start": 4243.2, "duration": 3.16}, {"text": "And it turns out, a bunch\nof these intermediates", "start": 4246.36, "duration": 2.09}, {"text": "are useful for\ncells to make stuff.", "start": 4248.45, "duration": 3.16}, {"text": "So we talked about\ngluconeogenesis.", "start": 4251.61, "duration": 1.64}, {"text": "Gluconeogenesis needs\nelectron balance.", "start": 4253.25, "duration": 1.92}, {"text": "We get NADH from the\nTCA cycle, and so you", "start": 4255.17, "duration": 2.97}, {"text": "can think of gluconeogenesis\nas an alternative", "start": 4258.14, "duration": 3.15}, {"text": "to fermentation to\ndispose of electrons.", "start": 4261.29, "duration": 2.15}, {"text": "Well, you can use the\nNADH from the TCA cycle", "start": 4263.44, "duration": 2.56}, {"text": "to run gluconeogenesis as well.", "start": 4266.0, "duration": 2.98}, {"text": "But beyond the cofactors,\nthe carbon itself.", "start": 4268.98, "duration": 2.64}, {"text": "So citrate, I've alluded\nto now a few times,", "start": 4271.62, "duration": 2.84}, {"text": "is important as a\nprecursor to make fat.", "start": 4274.46, "duration": 2.67}, {"text": "We'll discuss that in\nlater lectures, too.", "start": 4277.13, "duration": 2.49}, {"text": "But other intermediates\nin this pathway", "start": 4279.62, "duration": 3.09}, {"text": "are useful for various amino\nacids and nucleic acids.", "start": 4282.71, "duration": 4.0}, {"text": "And so there's\nlots of things that", "start": 4286.71, "duration": 2.63}, {"text": "can come from the\nTCA cycle that cells", "start": 4289.34, "duration": 3.15}, {"text": "can find useful to do,\nnot just catabolism,", "start": 4292.49, "duration": 5.35}, {"text": "but also anabolic processes.", "start": 4297.84, "duration": 4.04}, {"text": "Now, the way the TCA\ncycle works, though,", "start": 4301.88, "duration": 4.21}, {"text": "is that there's\nactually an issue", "start": 4306.09, "duration": 2.57}, {"text": "if you want to use the\nintermediates from the TCA", "start": 4308.66, "duration": 3.48}, {"text": "cycle to make stuff.", "start": 4312.14, "duration": 2.98}, {"text": "And so what is that issue?", "start": 4315.12, "duration": 4.77}, {"text": "Well, the TCA cycle functions\nat a site as a cycle.", "start": 4319.89, "duration": 5.528}, {"text": "And so, if we're going to\ntake things in and out of it,", "start": 4325.418, "duration": 2.292}, {"text": "that has consequences\nfor how the cycle runs.", "start": 4327.71, "duration": 4.02}, {"text": "Now there's a couple\nwords for this", "start": 4331.73, "duration": 3.01}, {"text": "that I want to just\nintroduce to you.", "start": 4334.74, "duration": 2.46}, {"text": "The first one is cataplerosis\nand the second one", "start": 4337.2, "duration": 3.17}, {"text": "is anaplerosis.", "start": 4340.37, "duration": 2.83}, {"text": "And so cataplerosis is\nthe act of removing stuff", "start": 4343.2, "duration": 9.48}, {"text": "from a metabolic cycle.", "start": 4352.68, "duration": 1.545}, {"text": "So, we're going\nto remove citrate", "start": 4358.03, "duration": 1.65}, {"text": "from the cycle to make fat.", "start": 4359.68, "duration": 1.44}, {"text": "That's cataplerosis.", "start": 4361.12, "duration": 1.74}, {"text": "And anaplerosis is adding\nstuff back to a metabolic cycle", "start": 4362.86, "duration": 14.68}, {"text": "so it can continue to function.", "start": 4377.54, "duration": 3.84}, {"text": "Viewing this is really evident\nif you think of the TCA cycle", "start": 4381.38, "duration": 3.75}, {"text": "as a chicken and egg problem.", "start": 4385.13, "duration": 2.2}, {"text": "So, the very first\ntime acetyl-CoA", "start": 4387.33, "duration": 2.34}, {"text": "was generated, how\ndo you start the TCA", "start": 4389.67, "duration": 3.05}, {"text": "cycle in the first place?", "start": 4392.72, "duration": 1.77}, {"text": "You can't add it\nto the TCA cycle", "start": 4394.49, "duration": 2.31}, {"text": "unless you have\noxaloacetate to combine", "start": 4396.8, "duration": 3.12}, {"text": "with the acetyl-CoA,\nwhich can then", "start": 4399.92, "duration": 2.13}, {"text": "generate another oxaloacetate.", "start": 4402.05, "duration": 3.12}, {"text": "So where does the first\noxaloacetate come from?", "start": 4405.17, "duration": 4.33}, {"text": "Well, we already talked\nabout one reaction.", "start": 4409.5, "duration": 2.06}, {"text": "We talked about it in the\ncontext of gluconeogenesis.", "start": 4411.56, "duration": 3.48}, {"text": "That can solve this problem.", "start": 4415.04, "duration": 1.36}, {"text": "And so we have pyruvate.", "start": 4416.4, "duration": 1.82}, {"text": "And so we talked\nearlier today how", "start": 4418.22, "duration": 2.16}, {"text": "we can do oxidative\ndecarboxylation of pyruvate", "start": 4420.38, "duration": 5.34}, {"text": "to give acetyl-CoA.", "start": 4425.72, "duration": 2.73}, {"text": "But we talked to in\nthe gluconeogenesis", "start": 4428.45, "duration": 1.71}, {"text": "lecture how we can add a\nCO2 pyruvate to generate", "start": 4430.16, "duration": 5.31}, {"text": "oxaloacetate.", "start": 4435.47, "duration": 1.8}, {"text": "So if I do those\ntwo reactions, now I", "start": 4437.27, "duration": 2.64}, {"text": "have all the carbon I\nneed to generate a citrate", "start": 4439.91, "duration": 6.49}, {"text": "and start off the TCA cycle.", "start": 4446.4, "duration": 4.79}, {"text": "Now obviously, if\nI do cataplerosis", "start": 4451.19, "duration": 4.94}, {"text": "and I remove that citrate\nI made to make fat,", "start": 4456.13, "duration": 3.09}, {"text": "well, now I need\ntwo pyruvate again", "start": 4459.22, "duration": 1.98}, {"text": "to generate the next citrate\nif I'm using this pathway,", "start": 4461.2, "duration": 4.74}, {"text": "because every time I bring\nan acetyl-CoA into the cycle,", "start": 4465.94, "duration": 3.48}, {"text": "I need an oxaloacetate\nto combine it with.", "start": 4469.42, "duration": 3.24}, {"text": "And so if I remove something,\nI have to add something back.", "start": 4472.66, "duration": 3.18}, {"text": "And so pyruvate to oxaloacetate,\nthe pyruvate carboxylase", "start": 4475.84, "duration": 3.9}, {"text": "reaction is an example of\nan anaplerotic reaction.", "start": 4479.74, "duration": 6.11}, {"text": "Now what this means,\nthough, is that in order", "start": 4485.85, "duration": 4.05}, {"text": "to do an anaplerosis,\nyou have to be", "start": 4489.9, "duration": 2.7}, {"text": "able to generate\nfour-carbon oxaloacetate,", "start": 4492.6, "duration": 4.35}, {"text": "or a four-carbon molecule.", "start": 4496.95, "duration": 2.83}, {"text": "Now, pyruvate carboxylase,\npyruvate to oxaloacetate,", "start": 4499.78, "duration": 2.81}, {"text": "allows you to do that.", "start": 4502.59, "duration": 1.212}, {"text": "We can take a\nthree-carbon molecule", "start": 4503.802, "duration": 1.458}, {"text": "and generate four-carbon\noxaloacetate.", "start": 4505.26, "duration": 2.82}, {"text": "However, if we start from\na two-carbon molecule", "start": 4508.08, "duration": 4.86}, {"text": "like acetate or acetyl-CoA\nthat enters the cycle,", "start": 4512.94, "duration": 7.27}, {"text": "it's actually not so simple to\ntake that two-carbon molecule", "start": 4520.21, "duration": 4.2}, {"text": "and turn it into\nfour-carbon oxaloacetate.", "start": 4524.41, "duration": 2.94}, {"text": "And in fact, humans\nlack any enzymes", "start": 4527.35, "duration": 3.72}, {"text": "that allow them to\ntake a two-carbon unit,", "start": 4531.07, "duration": 2.37}, {"text": "to take acetate or\nacetyl-CoA, and turn it", "start": 4533.44, "duration": 3.24}, {"text": "into anything that's\nlonger than net-- turn", "start": 4536.68, "duration": 4.32}, {"text": "it into anything that's\nlonger than two carbons.", "start": 4541.0, "duration": 3.27}, {"text": "And this has\nimportant implications", "start": 4544.27, "duration": 1.83}, {"text": "for human physiology,\nbecause what it says", "start": 4546.1, "duration": 2.97}, {"text": "is that we can't make\nglucose from anything", "start": 4549.07, "duration": 3.3}, {"text": "that starts with something\nless than three carbons long.", "start": 4552.37, "duration": 4.21}, {"text": "So if you drink alcohol and\nyou metabolize that alcohol", "start": 4556.58, "duration": 3.17}, {"text": "to acetate, it turns\nout you take fat", "start": 4559.75, "duration": 2.76}, {"text": "and you break down fat\nalso to acetyl-CoA,", "start": 4562.51, "duration": 2.82}, {"text": "to acetate two carbons long.", "start": 4565.33, "duration": 2.19}, {"text": "There is no way to turn\nthose molecules into glucose,", "start": 4567.52, "duration": 5.94}, {"text": "because you cannot generate\nthe oxaloacetate to do", "start": 4573.46, "duration": 3.15}, {"text": "the anaplerosis that's\nnecessary to get it there.", "start": 4576.61, "duration": 4.87}, {"text": "What this means is\nthat our body can only", "start": 4584.23, "duration": 5.79}, {"text": "store calories that come\nfrom two carbon units,", "start": 4590.02, "duration": 3.18}, {"text": "fat or alcohol, as fat.", "start": 4593.2, "duration": 2.4}, {"text": "We can never turn them back\ninto glucose or make glycogen.", "start": 4595.6, "duration": 5.602}, {"text": "And this is very relevant\nfor those of you that", "start": 4601.202, "duration": 1.958}, {"text": "go to medical\nschool, because it's", "start": 4603.16, "duration": 1.417}, {"text": "relevant to our physiology.", "start": 4604.577, "duration": 2.093}, {"text": "And that is, when\nour bodies exhaust", "start": 4606.67, "duration": 2.04}, {"text": "all of our stores of\nglucose, what happens?", "start": 4608.71, "duration": 2.61}, {"text": "Our liver can no longer\ndo gluconeogenesis.", "start": 4611.32, "duration": 2.82}, {"text": "And so what happens?", "start": 4614.14, "duration": 0.99}, {"text": "Now it has to switch over\nto doing something else.", "start": 4615.13, "duration": 2.32}, {"text": "It has to work with\ntwo carbon units.", "start": 4617.45, "duration": 1.92}, {"text": "And ultimately, this is\nketone metabolism, which we'll", "start": 4619.37, "duration": 2.78}, {"text": "talk about in a few lectures.", "start": 4622.15, "duration": 3.45}, {"text": "It also said that the body--", "start": 4625.6, "duration": 2.055}, {"text": "that this is also the basis\nof a very old adage that's", "start": 4631.31, "duration": 3.75}, {"text": "out there that some of\nyou may have heard--", "start": 4635.06, "duration": 2.22}, {"text": "that you need to have\nsome other fuel if you're", "start": 4637.28, "duration": 2.94}, {"text": "going to burn fat.", "start": 4640.22, "duration": 2.04}, {"text": "The basis for that is that\nfat is turned into two carbon", "start": 4642.26, "duration": 3.48}, {"text": "units, acetyl-CoA units.", "start": 4645.74, "duration": 2.1}, {"text": "And so if you're going to\ntake those acetyl-CoA units", "start": 4647.84, "duration": 2.34}, {"text": "and ultimately burn them\naway, turn them into CO2,", "start": 4650.18, "duration": 2.91}, {"text": "you need a source\nof oxaloacetate,", "start": 4653.09, "duration": 2.1}, {"text": "or your TCA cycle won't work.", "start": 4655.19, "duration": 2.4}, {"text": "And you don't need a lot of\nsomething, but it is true.", "start": 4657.59, "duration": 2.7}, {"text": "You can't start just with\nacetyl-CoA as a human and turn", "start": 4660.29, "duration": 4.71}, {"text": "it into CO2, so you need some--", "start": 4665.0, "duration": 1.86}, {"text": "at least a little\nbit of oxaloacetate", "start": 4666.86, "duration": 2.34}, {"text": "to get your TCA cycle started.", "start": 4669.2, "duration": 3.21}, {"text": "Now, that's a problem that we as\nhumans and other mammals face,", "start": 4672.41, "duration": 4.925}, {"text": "but it turns out there's\nlots of microbes out there", "start": 4677.335, "duration": 2.125}, {"text": "that grow just fine on\nacetate or on alcohol,", "start": 4679.46, "duration": 3.42}, {"text": "even if it's only carbon source.", "start": 4682.88, "duration": 2.1}, {"text": "And so those organisms\nmust have some way", "start": 4684.98, "duration": 3.57}, {"text": "to build stuff from\ntwo carbon units.", "start": 4688.55, "duration": 2.28}, {"text": "That is a way to use two carbon\nunits and do an anaplerosis.", "start": 4690.83, "duration": 4.45}, {"text": "And it turns out the way\nthey do this is via something", "start": 4695.28, "duration": 2.33}, {"text": "called the glyoxylate cycle.", "start": 4697.61, "duration": 2.8}, {"text": "And so the glyoxylate cycle\nis an alternative version", "start": 4703.05, "duration": 3.17}, {"text": "of the TCA cycle that\neffectively uses two enzymes", "start": 4706.22, "duration": 3.39}, {"text": "that we lack as mammals.", "start": 4709.61, "duration": 2.4}, {"text": "And so I'll quickly\ntell you about it here.", "start": 4712.01, "duration": 2.22}, {"text": "So, this is isocitrate\nfrom the TCA cycle.", "start": 4727.92, "duration": 9.5}, {"text": "And some microbes have an\nenzyme called isocitrate lyase.", "start": 4737.42, "duration": 10.85}, {"text": "And what isocitrate lyase does\nis basically splits citrate", "start": 4748.27, "duration": 10.16}, {"text": "in half, such that the top\nportion of the molecule", "start": 4758.43, "duration": 4.83}, {"text": "is another TCA cycle\nintermediate, succinate.", "start": 4763.26, "duration": 6.93}, {"text": "And the bottom\nportion of a molecule", "start": 4770.19, "duration": 3.96}, {"text": "is this two carbon\naldehyde called glyoxylate.", "start": 4774.15, "duration": 8.7}, {"text": "Glyoxylate can react with\nacetyl-CoA by another enzyme", "start": 4782.85, "duration": 18.04}, {"text": "that we lack as humans\ncalled malate synthase.", "start": 4800.89, "duration": 7.5}, {"text": "And I don't have time to\nshow the mechanism again,", "start": 4811.03, "duration": 3.85}, {"text": "but malate synthase basically\nadds the two carbons", "start": 4814.88, "duration": 4.28}, {"text": "from acetyl-CoA to the\naldehyde, the carbonyl,", "start": 4819.16, "duration": 7.02}, {"text": "the aldehyde carbonyl of\nglyoxylate in a reaction that", "start": 4826.18, "duration": 3.72}, {"text": "is, for all intents and\npurposes, exactly what happens", "start": 4829.9, "duration": 3.72}, {"text": "in citrate synthase.", "start": 4833.62, "duration": 2.43}, {"text": "That will generate this\nmolecule, which is malate, also", "start": 4836.05, "duration": 15.88}, {"text": "in the TCA cycle.", "start": 4851.93, "duration": 2.44}, {"text": "And so having these two extra\nreactions, isocitrate lyase", "start": 4854.37, "duration": 3.62}, {"text": "and malate synthase,\ngives microbes", "start": 4857.99, "duration": 3.93}, {"text": "the ability to have\nacetyl-CoA be anaplerotic.", "start": 4861.92, "duration": 6.12}, {"text": "And so how does that work?", "start": 4868.04, "duration": 1.41}, {"text": "Well, that's because if we start\nwith one oxaloacetate, four", "start": 4869.45, "duration": 6.39}, {"text": "carbons, and acetyl-CoA, two\ncarbons, can run the TCA cycle", "start": 4875.84, "duration": 10.56}, {"text": "and make citrate, six carbons.", "start": 4886.4, "duration": 4.71}, {"text": "Turn that citrate\ninto isocitrate.", "start": 4891.11, "duration": 2.774}, {"text": "Use isocitrate lyase to generate\nglyoxylate, two carbons.", "start": 4897.95, "duration": 11.14}, {"text": "Plus succinate.", "start": 4909.09, "duration": 2.46}, {"text": "That succinate can run through\nsuccinate dehydrogenase", "start": 4915.31, "duration": 6.76}, {"text": "to generate malate,\nwhich you can", "start": 4922.07, "duration": 1.98}, {"text": "go through malate dehydrogenase\nto generate oxaloacetate.", "start": 4924.05, "duration": 4.14}, {"text": "This glyoxylate can start\nwith a second acetyl-CoA.", "start": 4928.19, "duration": 7.74}, {"text": "Two carbons come\ntogether, generate malate.", "start": 4935.93, "duration": 3.96}, {"text": "That generates a\nsecond malate molecule,", "start": 4939.89, "duration": 2.88}, {"text": "which can then exit the cycle\nas malate or oxaloacetate", "start": 4942.77, "duration": 7.41}, {"text": "or whatever you want.", "start": 4950.18, "duration": 1.95}, {"text": "And so basically, it allows\ntwo acetyl-CoAs to net", "start": 4952.13, "duration": 4.29}, {"text": "generate an oxaloacetate,\nand so net generates a way", "start": 4956.42, "duration": 4.62}, {"text": "to do an anaplerosis\nfrom two carbon units", "start": 4961.04, "duration": 4.05}, {"text": "by having this malate\nsynthase reaction", "start": 4965.09, "duration": 6.07}, {"text": "and this isocitrate\nlyase reaction", "start": 4971.16, "duration": 6.2}, {"text": "and run this alternative\nversion of the TCA cycle,", "start": 4977.36, "duration": 3.57}, {"text": "called the glyoxylate cycle.", "start": 4980.93, "duration": 3.06}, {"text": "And it's a nice way how life--\nagain, no new chemistry here,", "start": 4983.99, "duration": 4.11}, {"text": "just variations on what\nwe've already shown--", "start": 4988.1, "duration": 2.64}, {"text": "repurposed the\nsimilar chemistries", "start": 4990.74, "duration": 1.95}, {"text": "that it's already using\nas a way to live off", "start": 4992.69, "duration": 3.93}, {"text": "of carbon sources that contain\nonly two carbons, like ethanol", "start": 4996.62, "duration": 7.92}, {"text": "or acetate.", "start": 5004.54, "duration": 2.81}, {"text": "So in closing today,\nthe last thing", "start": 5007.35, "duration": 4.05}, {"text": "I want to talk\nabout, very briefly,", "start": 5011.4, "duration": 3.03}, {"text": "is how the TCA\ncycle is regulated.", "start": 5014.43, "duration": 6.18}, {"text": "And we don't need to\nspend a ton of time", "start": 5020.61, "duration": 2.01}, {"text": "on this, because it really\nfollows principles that", "start": 5022.62, "duration": 6.09}, {"text": "make sense, particularly when\nwe think about things that we've", "start": 5028.71, "duration": 5.63}, {"text": "already talk about.", "start": 5034.34, "duration": 1.48}, {"text": "And so, regulation of the TCA\ncycles is of course important,", "start": 5035.82, "duration": 3.98}, {"text": "and it's really a critical hub,\nboth for anabolic and catabolic", "start": 5039.8, "duration": 3.63}, {"text": "pathways.", "start": 5043.43, "duration": 0.52}, {"text": "So, you needed to get energy\nto fully oxidize carbon,", "start": 5043.95, "duration": 2.99}, {"text": "but it's also a useful\nplace to get stuff.", "start": 5046.94, "duration": 3.312}, {"text": "And before I talk\nabout regulation,", "start": 5050.252, "duration": 1.458}, {"text": "I just want to point out that\nmany of the enzymes in the TCA", "start": 5051.71, "duration": 2.88}, {"text": "cycle, even though we talk\nabout it in the mitochondria", "start": 5054.59, "duration": 3.06}, {"text": "and we're about to talk\nabout regulation in terms", "start": 5057.65, "duration": 2.34}, {"text": "of catabolism--\nthat is oxidation,", "start": 5059.99, "duration": 2.67}, {"text": "ways to release energy--", "start": 5062.66, "duration": 2.4}, {"text": "many of these enzymes are\nalso in other locations", "start": 5065.06, "duration": 2.64}, {"text": "in the cell, because there's\nfunctions for them in making", "start": 5067.7, "duration": 4.47}, {"text": "stuff that is very different\nthan what goes on in the TCA", "start": 5072.17, "duration": 2.85}, {"text": "cycle.", "start": 5075.02, "duration": 0.99}, {"text": "And the regulation that\nI'll tell you about,", "start": 5076.01, "duration": 3.45}, {"text": "and that comes up on\nMCAT exams and stuff", "start": 5079.46, "duration": 2.82}, {"text": "like that, usually\ntalks about this pathway", "start": 5082.28, "duration": 3.18}, {"text": "as a catabolic pathway, as a\nway to make CO2, to make ATP.", "start": 5085.46, "duration": 4.48}, {"text": "However, recognize\nthat there's also", "start": 5089.94, "duration": 3.44}, {"text": "variations on this pathway that\ncan use in anabolic things,", "start": 5093.38, "duration": 4.23}, {"text": "making stuff.", "start": 5097.61, "duration": 1.11}, {"text": "And that regulation is something\nthat really is not necessarily", "start": 5098.72, "duration": 4.98}, {"text": "what we're going\nto talk about here", "start": 5103.7, "duration": 1.89}, {"text": "and is a little bit\nless well-understood.", "start": 5105.59, "duration": 4.2}, {"text": "But at least the\nregulation, in terms", "start": 5109.79, "duration": 1.74}, {"text": "of catabolism, if we put it in\ncontext of glucose metabolism--", "start": 5111.53, "duration": 7.39}, {"text": "so here's glycolysis, turning\nglucose into pyruvate.", "start": 5118.92, "duration": 6.97}, {"text": "And then that\npyruvate can operate", "start": 5132.34, "duration": 3.21}, {"text": "through the pyruvate\ndehydrogenase reaction", "start": 5135.55, "duration": 4.74}, {"text": "to generate acetyl-CoA.", "start": 5140.29, "duration": 4.14}, {"text": "That acetyl-CoA can\ncombine with oxaloacetate", "start": 5144.43, "duration": 5.76}, {"text": "to generate citrate.", "start": 5150.19, "duration": 3.592}, {"text": "That citrate, of course,\ncan be used to generate fat,", "start": 5153.782, "duration": 3.748}, {"text": "as we've talked about.", "start": 5157.53, "duration": 2.87}, {"text": "That can go to isocitrate.", "start": 5160.4, "duration": 1.68}, {"text": "Isocitrate to alpha\nketoglutarate.", "start": 5164.94, "duration": 4.33}, {"text": "That's catalyzed by\nisocitrate dehydrogenase,", "start": 5169.27, "duration": 4.23}, {"text": "which I will abbreviate IDH.", "start": 5173.5, "duration": 2.13}, {"text": "Alpha ketoglutarate\nto succinate.", "start": 5175.63, "duration": 4.12}, {"text": "More correctly, to succinyl-CoA\nby alpha ketoglutarate", "start": 5179.75, "duration": 11.08}, {"text": "dehydrogenase, Alpha KGDH.", "start": 5190.83, "duration": 4.41}, {"text": "And then this back\nto oxaloacetate.", "start": 5195.24, "duration": 2.91}, {"text": "And so the main enzymes\nthat are typically", "start": 5198.15, "duration": 3.06}, {"text": "discussed as being regulated\nare alpha ketoglutarate", "start": 5201.21, "duration": 3.92}, {"text": "dehydrogenase,\nisocitrate dehydrogenase,", "start": 5205.13, "duration": 2.98}, {"text": "and pyruvate dehydrogenase.", "start": 5208.11, "duration": 2.07}, {"text": "I also drew glycolysis.", "start": 5210.18, "duration": 3.01}, {"text": "And I'll just write over\nhere, gluconeogenesis up here,", "start": 5213.19, "duration": 5.07}, {"text": "because we can now see\nmore fully how this plays", "start": 5218.26, "duration": 6.31}, {"text": "in with citrate acting\nas a positive regulator", "start": 5224.57, "duration": 5.19}, {"text": "with gluconeogenesis and\nan inhibitor of glycolysis.", "start": 5229.76, "duration": 6.07}, {"text": "Again, we're full in citrate,\nstop running glycolysis,", "start": 5235.83, "duration": 5.58}, {"text": "start running gluconeogenesis.", "start": 5241.41, "duration": 3.54}, {"text": "Now, the other regulation.", "start": 5244.95, "duration": 1.74}, {"text": "If you have a lot of\nacetyl-CoA, stop making it", "start": 5246.69, "duration": 3.39}, {"text": "from pyruvate. acetyl-CoA is\na negative regulator of PDH.", "start": 5250.08, "duration": 4.74}, {"text": "This is carbon oxidation.", "start": 5254.82, "duration": 2.73}, {"text": "Releases a lot of energy,\ngenerates a lot of ATP,", "start": 5257.55, "duration": 3.48}, {"text": "generates a lot of NADH.", "start": 5261.03, "duration": 3.12}, {"text": "If you have lots\nof those things,", "start": 5264.15, "duration": 1.86}, {"text": "no reason to keep\nsending carbon into", "start": 5266.01, "duration": 3.38}, {"text": "acetyl-CoA to go\ninto the TCA cycle.", "start": 5269.39, "duration": 3.57}, {"text": "Ultimately, we have to send\nthose electrons somewhere.", "start": 5272.96, "duration": 3.773}, {"text": "So if there's\nnowhere to put them,", "start": 5276.733, "duration": 1.417}, {"text": "low oxygen also inhibits\npyruvate dehydrogenase.", "start": 5278.15, "duration": 4.35}, {"text": "And of course, if you need\nmore energy, if ADP is high,", "start": 5282.5, "duration": 4.17}, {"text": "that activates\npyruvate dehydrogenase.", "start": 5286.67, "duration": 3.33}, {"text": "So at least in terms of glucose,\ncomplete glucose oxidation,", "start": 5290.0, "duration": 4.32}, {"text": "a lot of regulation happens\nat pyruvate dehydrogenase.", "start": 5294.32, "duration": 3.96}, {"text": "And a lot of it\nreally makes sense.", "start": 5298.28, "duration": 3.77}, {"text": "High levels of ATP,\nhigh levels of NADH,", "start": 5302.05, "duration": 5.4}, {"text": "also inhibit isocitrate\ndehydrogenase and alpha", "start": 5307.45, "duration": 6.72}, {"text": "ketoglutarate dehydrogenase.", "start": 5314.17, "duration": 4.52}, {"text": "Makes sense.", "start": 5318.69, "duration": 1.15}, {"text": "Succinol-CoA high, inhibit alpha\nketoglutarate dehydrogenase.", "start": 5319.84, "duration": 5.15}, {"text": "High levels of ADP, need\nto release more energy,", "start": 5324.99, "duration": 7.23}, {"text": "activate alpha\nketoglutarate dehydrogenase.", "start": 5332.22, "duration": 4.08}, {"text": "Again, these are the feedbacks\nthat people talk about", "start": 5339.18, "duration": 2.85}, {"text": "on board exams.", "start": 5342.03, "duration": 1.56}, {"text": "Good to know, but you can\nalmost guess what they", "start": 5343.59, "duration": 2.64}, {"text": "would be from first principles.", "start": 5346.23, "duration": 1.98}, {"text": "Because remember,\nthis is a pathway", "start": 5348.21, "duration": 1.59}, {"text": "that releases a lot of energy.", "start": 5349.8, "duration": 1.86}, {"text": "High energy high\nATP, high NADH--", "start": 5351.66, "duration": 3.21}, {"text": "don't run the cycle, don't\nenter carbon in the cycle.", "start": 5354.87, "duration": 3.3}, {"text": "Low energy, high ADP,\nput carbon in the cycle,", "start": 5358.17, "duration": 5.73}, {"text": "run the cycle faster.", "start": 5363.9, "duration": 1.86}, {"text": "Makes sense.", "start": 5365.76, "duration": 1.14}, {"text": "Also makes sense of the\nreciprocal regulation", "start": 5366.9, "duration": 2.58}, {"text": "of glycolysis and\ngluconeogenesis.", "start": 5369.48, "duration": 3.58}, {"text": "Great.", "start": 5373.06, "duration": 0.5}, {"text": "Next time, we will\ntalk more about", "start": 5373.56, "duration": 4.56}, {"text": "how we can oxidize fatty acids,\nfat, by accessing acetyl-CoA", "start": 5378.12, "duration": 8.64}, {"text": "and entering it into the cycle.", "start": 5386.76, "duration": 1.62}, {"text": "Thanks.", "start": 5388.38, "duration": 1.55}]

transcripts/3jtSEeDiYvE.json

@@ -0,0 +1 @@
+[{"text": "[SQUEAKING]", "start": 0.0, "duration": 2.44}, {"text": "[RUSTLING]", "start": 2.44, "duration": 1.952}, {"text": "[CLICKING]", "start": 4.392, "duration": 0.976}, {"text": "DAVID HSU: Hi, everyone,\nand welcome back to the MIT", "start": 10.74, "duration": 3.0}, {"text": "class on urban energy systems.", "start": 13.74, "duration": 2.23}, {"text": "Wherever you're seeing this\nlecture, please subscribe.", "start": 15.97, "duration": 3.21}, {"text": "You can either find\nit on the web page", "start": 19.18, "duration": 2.0}, {"text": "where you found this video\nor ask the instructor.", "start": 21.18, "duration": 4.48}, {"text": "So let's get back to\nthe topic for today,", "start": 25.66, "duration": 3.96}, {"text": "which is going to be\ncities and decarbonization.", "start": 29.62, "duration": 3.23}, {"text": "What is the role of cities?", "start": 32.85, "duration": 2.22}, {"text": "Again, I'm David\nHsu, and if you're", "start": 35.07, "duration": 2.94}, {"text": "thinking about how\ncities can take action", "start": 38.01, "duration": 3.33}, {"text": "or what their role is\nin decarbonization,", "start": 41.34, "duration": 2.01}, {"text": "you have found the right\nplace and your people.", "start": 43.35, "duration": 3.75}, {"text": "So I want to cover just\nbriefly how you're going", "start": 47.1, "duration": 2.67}, {"text": "to prepare for class this week.", "start": 49.77, "duration": 1.38}, {"text": "This is our second class.", "start": 51.15, "duration": 1.27}, {"text": "I want to make sure that\neveryone's caught up.", "start": 52.42, "duration": 2.75}, {"text": "First, the introductory\nreading from last week", "start": 55.17, "duration": 2.52}, {"text": "is fairly short and scalable.", "start": 57.69, "duration": 1.93}, {"text": "So it's easy to catch up,\nbut you should catch up.", "start": 59.62, "duration": 3.03}, {"text": "And it's particularly important\nto look at MacKay chapter 2.", "start": 62.65, "duration": 4.46}, {"text": "Again, it's MacKay chapter 2.", "start": 67.11, "duration": 2.962}, {"text": "There's the initial problem\nset due Monday night.", "start": 70.072, "duration": 3.128}, {"text": "You can just access\nthe problem set", "start": 73.2, "duration": 2.28}, {"text": "by going directly to this Google\nform, the link on the screen.", "start": 75.48, "duration": 4.585}, {"text": "You should do the\nreading for this week", "start": 80.065, "duration": 1.625}, {"text": "that's on the syllabus.", "start": 81.69, "duration": 1.14}, {"text": "I also show the reading for\nthis week on the next page.", "start": 82.83, "duration": 3.51}, {"text": "And then you should watch the\nrest of this video lecture.", "start": 86.34, "duration": 2.97}, {"text": "And during the reading and while\nwatching the video lecture,", "start": 89.31, "duration": 2.957}, {"text": "it's important for you to\nwrite down the questions", "start": 92.267, "duration": 2.083}, {"text": "that you have for discussion.", "start": 94.35, "duration": 1.443}, {"text": "And then I want you to\nfeel free to share them", "start": 95.793, "duration": 1.917}, {"text": "on Slack, whenever,\nasynchronously, or in our class", "start": 97.71, "duration": 3.51}, {"text": "meeting on Tuesday.", "start": 101.22, "duration": 3.05}, {"text": "So the material for today--", "start": 104.27, "duration": 1.44}, {"text": "again, I won't go over them.", "start": 105.71, "duration": 1.17}, {"text": "These are all in your syllabus.", "start": 106.88, "duration": 1.26}, {"text": "But these will also\nbe in the slides,", "start": 108.14, "duration": 1.542}, {"text": "so you can follow the links.", "start": 109.682, "duration": 1.478}, {"text": "The first four readings\nare the required readings,", "start": 111.16, "duration": 4.716}, {"text": "a kind of gathering of\nvery different readings.", "start": 115.876, "duration": 3.774}, {"text": "And the last two readings\nare optional readings", "start": 119.65, "duration": 2.4}, {"text": "that give additional information\nto the articles above.", "start": 122.05, "duration": 5.65}, {"text": "So what I want to start\nwith is MacKay chapter 2,", "start": 127.7, "duration": 2.719}, {"text": "what he calls the\nbalance sheet, and it's", "start": 130.419, "duration": 2.216}, {"text": "an important set\nof concepts simply", "start": 132.635, "duration": 2.255}, {"text": "so we can think about\nthe energy system.", "start": 134.89, "duration": 2.61}, {"text": "And very simply, what MacKay\nis trying to do in his book", "start": 137.5, "duration": 3.36}, {"text": "is contrast these\nred and green bars.", "start": 140.86, "duration": 3.51}, {"text": "Energy consumption is\non the left and red,", "start": 144.37, "duration": 3.06}, {"text": "and energy production is\non the right in green.", "start": 147.43, "duration": 2.71}, {"text": "And so when MacKay\ntitles his book", "start": 150.14, "duration": 2.42}, {"text": "Sustainable Energy--\nwithout the hot air, what", "start": 152.56, "duration": 2.37}, {"text": "we're trying to do is\nreplace our current level", "start": 154.93, "duration": 2.76}, {"text": "of consumption with entirely\nrenewable resources,", "start": 157.69, "duration": 3.253}, {"text": "and that's how we're going to\nachieve a sustainable energy", "start": 160.943, "duration": 2.417}, {"text": "system.", "start": 163.36, "duration": 1.12}, {"text": "And so a sustainable\nenergy system", "start": 164.48, "duration": 3.02}, {"text": "would be if our total\nconceivable sustainable", "start": 167.5, "duration": 2.76}, {"text": "production sources,\non the right,", "start": 170.26, "duration": 2.01}, {"text": "are greater than our\ntotal consumption.", "start": 172.27, "duration": 2.52}, {"text": "And an unsustainable\nenergy system", "start": 174.79, "duration": 2.07}, {"text": "would be where our total\nconsumption of energy", "start": 176.86, "duration": 2.61}, {"text": "is larger than our total\nconceivable sustainable", "start": 179.47, "duration": 2.52}, {"text": "production.", "start": 181.99, "duration": 0.79}, {"text": "And, of course, these\ntwo bars will change over", "start": 182.78, "duration": 2.27}, {"text": "time as our expectations\naround consumption change", "start": 185.05, "duration": 4.05}, {"text": "and our technologies\nand our institutions", "start": 189.1, "duration": 3.54}, {"text": "and our markets for\nsustainable production change.", "start": 192.64, "duration": 2.25}, {"text": "But that's the challenge.", "start": 194.89, "duration": 1.29}, {"text": "The challenge is to try to\nput these two in balance", "start": 196.18, "duration": 2.67}, {"text": "and at least have total\nsustainable production that", "start": 198.85, "duration": 2.7}, {"text": "is enough to meet all\nof our societal needs,", "start": 201.55, "duration": 3.24}, {"text": "or our global societal needs,\nfor energy consumption.", "start": 204.79, "duration": 3.93}, {"text": "And so what that might look like\nis the key forms of consumption", "start": 208.72, "duration": 3.9}, {"text": "on the left-hand stack in red--", "start": 212.62, "duration": 2.4}, {"text": "that is the energy we need\nfor transportation, including", "start": 215.02, "duration": 3.09}, {"text": "cars, planes, and freight.", "start": 218.11, "duration": 2.25}, {"text": "It's the energy we\nneed to heat and cool", "start": 220.36, "duration": 1.95}, {"text": "the spaces that we live in.", "start": 222.31, "duration": 1.53}, {"text": "That can wildly differ\nacross countries.", "start": 223.84, "duration": 2.58}, {"text": "It's a basic need for lighting\nso we can see at night.", "start": 226.42, "duration": 3.72}, {"text": "It's a growing need for\nenergy for information systems", "start": 230.14, "duration": 3.39}, {"text": "and our other gadgets.", "start": 233.53, "duration": 2.64}, {"text": "The fifth point, food--", "start": 236.17, "duration": 1.83}, {"text": "a tremendous amount\nof energy goes", "start": 238.0, "duration": 1.83}, {"text": "into growing and transporting\nand keeping our food cold.", "start": 239.83, "duration": 5.7}, {"text": "And, finally, the\nmanufacturing--", "start": 245.53, "duration": 2.04}, {"text": "for all the technologies\nor all the gadgets", "start": 247.57, "duration": 2.49}, {"text": "we need to do transportation\nor heating and cooling,", "start": 250.06, "duration": 3.09}, {"text": "like information\nsystems and food,", "start": 253.15, "duration": 1.68}, {"text": "we have to make these\nthings in the first place,", "start": 254.83, "duration": 2.324}, {"text": "and that requires a\ntremendous amount of energy.", "start": 257.154, "duration": 2.925}, {"text": "On the right-hand side, our\nsustainable production stack", "start": 260.079, "duration": 3.151}, {"text": "has a number of categories.", "start": 263.23, "duration": 1.63}, {"text": "The good thing is-- and I'll try\nto emphasize this in the class", "start": 264.86, "duration": 2.9}, {"text": "repeatedly-- is that we have\nmany sustainable technologies", "start": 267.76, "duration": 4.32}, {"text": "that can produce energy.", "start": 272.08, "duration": 1.87}, {"text": "We have wind and solar.", "start": 273.95, "duration": 2.21}, {"text": "Solar energy can be\nharnessed in the form", "start": 276.16, "duration": 2.07}, {"text": "of photovoltaic or solar cells\nthat produce electricity.", "start": 278.23, "duration": 4.2}, {"text": "We can harness solar energy\nthrough thermal energy,", "start": 282.43, "duration": 3.255}, {"text": "and we can also harness\nsolar energy through biomass,", "start": 285.685, "duration": 3.195}, {"text": "by harvesting the\npotential of the Earth", "start": 288.88, "duration": 2.58}, {"text": "to engage in\nphotosynthesis, create crops", "start": 291.46, "duration": 2.52}, {"text": "that we then can use\nfor other things,", "start": 293.98, "duration": 2.53}, {"text": "including burning in engines.", "start": 296.51, "duration": 3.38}, {"text": "Hydroelectric power is producing\nelectricity directly from--", "start": 299.89, "duration": 4.02}, {"text": "or mechanical storage\ndirectly from-- hydropower.", "start": 303.91, "duration": 4.14}, {"text": "Wave energy and tide energy\nare two sources of energy", "start": 308.05, "duration": 3.54}, {"text": "that come from the Earth\non a regular basis.", "start": 311.59, "duration": 4.41}, {"text": "Geothermal energy also\ncomes from the Earth.", "start": 316.0, "duration": 2.91}, {"text": "The heat inside the Earth can\nbe harnessed to produce energy.", "start": 318.91, "duration": 3.15}, {"text": "And finally, nuclear, And MacKay\nputs it with a question mark", "start": 322.06, "duration": 3.708}, {"text": "because it's not\nclear whether or not", "start": 325.768, "duration": 1.542}, {"text": "nuclear energy or nuclear\npower counts as sustainable.", "start": 327.31, "duration": 2.94}, {"text": "It is low carbon, but as I\nsaid in an earlier class,", "start": 330.25, "duration": 3.99}, {"text": "we have questions\nabout how do we handle", "start": 334.24, "duration": 2.79}, {"text": "the fuel for nuclear\npower plants,", "start": 337.03, "duration": 3.01}, {"text": "how do we handle the waste\nfrom nuclear power plants,", "start": 340.04, "duration": 2.21}, {"text": "and whether or not\nthat will be fully", "start": 342.25, "duration": 1.65}, {"text": "sustainable in the long run.", "start": 343.9, "duration": 3.06}, {"text": "And so I want to cover two\nphysical concepts from MacKay", "start": 346.96, "duration": 2.6}, {"text": "chapter 2 that I\nthink are basically", "start": 349.56, "duration": 2.31}, {"text": "going to be the most important\nphysical concepts you", "start": 351.87, "duration": 2.79}, {"text": "need to understand this class.", "start": 354.66, "duration": 2.28}, {"text": "And the first one,\nquite simply, is energy.", "start": 356.94, "duration": 2.85}, {"text": "It's the quantitative\nproperty of doing work.", "start": 359.79, "duration": 3.97}, {"text": "Energy can be neither\ndestroyed nor created,", "start": 363.76, "duration": 2.97}, {"text": "one of our fundamental\nlaws of thermodynamics.", "start": 366.73, "duration": 3.75}, {"text": "Energy can be transformed into\nlight, heat, or mass, hence", "start": 370.48, "duration": 4.74}, {"text": "the famous equation by\nEinstein, E equals mc squared,", "start": 375.22, "duration": 4.65}, {"text": "energy equals mass times\nof speed of light squared.", "start": 379.87, "duration": 3.63}, {"text": "This is a fundamental\nfinding out of relativity.", "start": 383.5, "duration": 3.61}, {"text": "And, of course, energy can\ntake many different forms.", "start": 387.11, "duration": 3.07}, {"text": "And we use it in many different\nforms in our energy system.", "start": 390.18, "duration": 2.9}, {"text": "Energy can be kinetic.", "start": 393.08, "duration": 1.68}, {"text": "It can be chemical.", "start": 394.76, "duration": 1.68}, {"text": "We can have potential energy.", "start": 396.44, "duration": 1.65}, {"text": "We have mechanical\nenergy, let's say,", "start": 398.09, "duration": 1.74}, {"text": "stored in the elastic\nproperties of materials", "start": 399.83, "duration": 2.49}, {"text": "and, of course, biological\nenergy, which is fundamentally", "start": 402.32, "duration": 3.21}, {"text": "chemical energy, but\nwe have different modes", "start": 405.53, "duration": 2.46}, {"text": "of perhaps using that chemical\nenergy in our muscles,", "start": 407.99, "duration": 2.88}, {"text": "in animals, in ecosystems.", "start": 410.87, "duration": 2.96}, {"text": "And we're going to\nmeasure energy in terms", "start": 413.83, "duration": 1.75}, {"text": "of units of kilowatt-hours.", "start": 415.58, "duration": 1.98}, {"text": "You'll see energy referred to in\nterms of British Thermal Units,", "start": 417.56, "duration": 3.66}, {"text": "BTUs, something only used\nin the US and America", "start": 421.22, "duration": 3.87}, {"text": "or the United States.", "start": 425.09, "duration": 1.32}, {"text": "Therms, joules, calories,\nare all units for energy.", "start": 426.41, "duration": 3.99}, {"text": "They can all be converted\nto kilowatt-hours.", "start": 430.4, "duration": 2.82}, {"text": "A specific category I just\nwant to highlight below", "start": 433.22, "duration": 2.79}, {"text": "is fossil fuels are sometimes\nmeasured in barrels of oil,", "start": 436.01, "duration": 4.26}, {"text": "short tons of coal, cubic\nfeet of natural gas.", "start": 440.27, "duration": 3.21}, {"text": "That's because\nthat's how we measure", "start": 443.48, "duration": 1.5}, {"text": "the things we trade\nin commodity markets", "start": 444.98, "duration": 2.28}, {"text": "for commoditized fossil fuels.", "start": 447.26, "duration": 2.16}, {"text": "But, again, the amount of\nenergy in a barrel of oil", "start": 449.42, "duration": 3.06}, {"text": "and a short ton of coal and\ncubic foot of natural gas", "start": 452.48, "duration": 3.48}, {"text": "can be converted\nto kilowatt-hours.", "start": 455.96, "duration": 3.08}, {"text": "So just to give you a\nfew examples, example 1,", "start": 459.04, "duration": 2.75}, {"text": "you may have had the\nfrustrating experience", "start": 461.79, "duration": 2.25}, {"text": "of having gone to\nthe gym, foolishly", "start": 464.04, "duration": 3.15}, {"text": "counting your calories,\nrealizing you worked out", "start": 467.19, "duration": 2.7}, {"text": "for an hour on a\nrunning treadmill,", "start": 469.89, "duration": 1.85}, {"text": "and it's only equivalent\nto three Oreos.", "start": 471.74, "duration": 2.8}, {"text": "You can also look at example 2.", "start": 474.54, "duration": 1.98}, {"text": "The average American household\nuses per year about 11,000", "start": 476.52, "duration": 3.72}, {"text": "kilowatt hours in electricity.", "start": 480.24, "duration": 2.31}, {"text": "Each person uses 300\nmillion BTUs total", "start": 482.55, "duration": 4.5}, {"text": "per year, which is approximately\n2.3 gallons of oil,", "start": 487.05, "duration": 4.35}, {"text": "7.89 pounds of coal,\nand 252 cubic feet", "start": 491.4, "duration": 3.9}, {"text": "of natural gas per day.", "start": 495.3, "duration": 2.195}, {"text": "Now, it's just\nworth pointing out", "start": 497.495, "duration": 1.375}, {"text": "that the first example, in\nterms of the American household,", "start": 498.87, "duration": 3.06}, {"text": "is in kilowatt-hours but\nonly counts for electricity.", "start": 501.93, "duration": 3.6}, {"text": "That's for the whole\nhousehold per year.", "start": 505.53, "duration": 2.35}, {"text": "The second sentence\nmeasures each person", "start": 507.88, "duration": 2.33}, {"text": "on a per-capita basis but then\nbreaks the millions of BTUs", "start": 510.21, "duration": 5.04}, {"text": "into different units because\nof the different sources", "start": 515.25, "duration": 3.0}, {"text": "of energy.", "start": 518.25, "duration": 0.909}, {"text": "And this is to say that,\nwhen we do these comparisons,", "start": 519.159, "duration": 2.811}, {"text": "we want to be careful\nabout the units we use,", "start": 521.97, "duration": 2.43}, {"text": "the averaging over time,\nand the sources of energy,", "start": 524.4, "duration": 3.21}, {"text": "because the original\nsource of energy", "start": 527.61, "duration": 2.22}, {"text": "may not actually be how much\nenergy we use in the end.", "start": 529.83, "duration": 2.95}, {"text": "And we'll talk about that\nmore in a few slides.", "start": 532.78, "duration": 4.07}, {"text": "Another key physical concept\nwe have to talk about", "start": 536.85, "duration": 2.42}, {"text": "or will be very useful\nis power, and that's", "start": 539.27, "duration": 3.27}, {"text": "the quantitative\nrate of doing work.", "start": 542.54, "duration": 2.7}, {"text": "That is power is\nenergy per time.", "start": 545.24, "duration": 4.41}, {"text": "It's a rate.", "start": 549.65, "duration": 1.35}, {"text": "The units we use\nof that are watts,", "start": 551.0, "duration": 2.7}, {"text": "or equal to joules per second.", "start": 553.7, "duration": 2.64}, {"text": "Other forms of power that\nyou might be familiar with", "start": 556.34, "duration": 3.81}, {"text": "are ergs, amperes in terms of\nelectrical current, horsepower", "start": 560.15, "duration": 4.71}, {"text": "in terms of the engine in\nyour car or other motors,", "start": 564.86, "duration": 4.36}, {"text": "and lumens are the amount\nof energy passed off", "start": 569.22, "duration": 4.86}, {"text": "per second from\nan LED light bulb", "start": 574.08, "duration": 2.82}, {"text": "but measured over a sphere\naround a light bulb.", "start": 576.9, "duration": 2.462}, {"text": "So it's actually weighted by\nthe area around the light bulb", "start": 579.362, "duration": 2.458}, {"text": "or what degree of area is\nputting out how much energy.", "start": 581.82, "duration": 6.77}, {"text": "So to just use the same\nexample as the previous slide,", "start": 588.59, "duration": 4.2}, {"text": "you could say, I\nworked out for an hour,", "start": 592.79, "duration": 2.0}, {"text": "and I only worked off the\nequivalent of three Oreos.", "start": 594.79, "duration": 2.85}, {"text": "But maybe it sounds\nperhaps more impressive", "start": 597.64, "duration": 2.34}, {"text": "if you say, \"My workout\nmaintained a steady power", "start": 599.98, "duration": 2.79}, {"text": "output of three Oreos per hour!\"", "start": 602.77, "duration": 4.45}, {"text": "Another key concept\nwe have to cover", "start": 607.22, "duration": 2.06}, {"text": "that links energy and climate\nis emissions intensity.", "start": 609.28, "duration": 3.36}, {"text": "And emissions are measured\nin terms of greenhouse gases,", "start": 612.64, "duration": 3.66}, {"text": "usually measured in metric-ton\ncarbon dioxide equivalent,", "start": 616.3, "duration": 3.67}, {"text": "which is abbreviated MTCDE,\nor mt-CO2-e, and so on.", "start": 619.97, "duration": 6.183}, {"text": "And the reason why\nwe have to measure it", "start": 626.153, "duration": 1.667}, {"text": "in terms of metric-ton\ncarbon dioxide equivalent", "start": 627.82, "duration": 3.57}, {"text": "is that there's a lot of\ndifferent greenhouse gases,", "start": 631.39, "duration": 2.37}, {"text": "and some of them, for\nexample, methane, CH4,", "start": 633.76, "duration": 3.42}, {"text": "has much more global warming\npotential than carbon dioxide.", "start": 637.18, "duration": 3.46}, {"text": "So a single ton of\nmethane has about 84 times", "start": 640.64, "duration": 4.52}, {"text": "the global warming potential\nof a ton of carbon dioxide", "start": 645.16, "duration": 4.26}, {"text": "early in its life.", "start": 649.42, "duration": 1.02}, {"text": "That declines over time\nto about 20 metric tons", "start": 650.44, "duration": 3.54}, {"text": "of carbon dioxide equivalent.", "start": 653.98, "duration": 1.44}, {"text": "So this is just to say that,\nif we have different greenhouse", "start": 655.42, "duration": 3.33}, {"text": "gases, we measure\nthem or make them", "start": 658.75, "duration": 2.28}, {"text": "all equivalent to a\nmetric ton of carbon", "start": 661.03, "duration": 2.04}, {"text": "dioxide equivalent\nduring their lifetime.", "start": 663.07, "duration": 3.47}, {"text": "We can also measure emissions\nintensity by the type of gas,", "start": 666.54, "duration": 4.2}, {"text": "as the example I just gave\nyou in terms of methane,", "start": 670.74, "duration": 3.09}, {"text": "also nitrous oxide and\nfluorohexane, I think,", "start": 673.83, "duration": 3.36}, {"text": "are another greenhouse gas.", "start": 677.19, "duration": 1.83}, {"text": "You can measure in emissions\nintensity per unit of energy.", "start": 679.02, "duration": 3.3}, {"text": "This much greenhouse\ngas is created", "start": 682.32, "duration": 2.01}, {"text": "in terms of this much energy.", "start": 684.33, "duration": 2.4}, {"text": "You can measure greenhouse\ngases per activity,", "start": 686.73, "duration": 2.85}, {"text": "per dollar of GDP, or by region.", "start": 689.58, "duration": 2.16}, {"text": "People use lots of\ndifferent intensities.", "start": 691.74, "duration": 2.07}, {"text": "And the reason why\nI want to focus", "start": 693.81, "duration": 1.417}, {"text": "on this key concept\nof intensity is", "start": 695.227, "duration": 1.973}, {"text": "that, as we look at different\nparts of the system,", "start": 697.2, "duration": 2.26}, {"text": "we're going to look\nat the intensity", "start": 699.46, "duration": 1.16}, {"text": "of the different\nparts of the system", "start": 700.62, "duration": 1.5}, {"text": "to get a whole picture of where\ngreenhouse gases are coming", "start": 702.12, "duration": 2.97}, {"text": "from, just like we're going\nto look at energy intensity", "start": 705.09, "duration": 2.82}, {"text": "in terms of how much\nenergy do you need", "start": 707.91, "duration": 1.71}, {"text": "for different activities,\nhow much energy do", "start": 709.62, "duration": 2.49}, {"text": "different regions\nof the world use.", "start": 712.11, "duration": 2.35}, {"text": "And so to give you a few\nexamples of the Conference", "start": 714.46, "duration": 3.35}, {"text": "of the Parties, the COP\nmeetings that the UN Framework", "start": 717.81, "duration": 3.33}, {"text": "Convention on Climate\nChange runs every year--", "start": 721.14, "duration": 4.56}, {"text": "they have reporting inventory.", "start": 725.7, "duration": 1.53}, {"text": "And when every country which\nis party to the Paris Agreement", "start": 727.23, "duration": 4.23}, {"text": "has to report its greenhouse\ngas emissions and, frankly,", "start": 731.46, "duration": 2.713}, {"text": "the actions that they're taking\nto reduce their greenhouse", "start": 734.173, "duration": 2.417}, {"text": "gases.", "start": 736.59, "duration": 0.82}, {"text": "They have to measure or report\ntheir greenhouse gases in terms", "start": 737.41, "duration": 3.11}, {"text": "of a specific inventory format.", "start": 740.52, "duration": 1.86}, {"text": "So I have linked to that here.", "start": 742.38, "duration": 1.66}, {"text": "You can click on\nit, and you can see", "start": 744.04, "duration": 1.88}, {"text": "how countries report different\nkinds of greenhouse gases.", "start": 745.92, "duration": 3.75}, {"text": "It's because\ncountries can only see", "start": 749.67, "duration": 2.34}, {"text": "the source of the activities\nthat create greenhouse gases.", "start": 752.01, "duration": 4.09}, {"text": "So it's easier for us to\nmeasure how many barrels of oil", "start": 756.1, "duration": 2.93}, {"text": "we burned or how many short\ntons of coal we burned or, let's", "start": 759.03, "duration": 3.96}, {"text": "say, how much land\nuse conversion has", "start": 762.99, "duration": 1.77}, {"text": "led to how much methane or\nhow much carbon dioxide.", "start": 764.76, "duration": 3.24}, {"text": "We can also measure, let's say,\nour greenhouse gas emissions", "start": 768.0, "duration": 4.2}, {"text": "per unit of electricity because\nelectricity comes from a grid.", "start": 772.2, "duration": 4.45}, {"text": "The grid is a technology\nwe'll talk about a lot", "start": 776.65, "duration": 1.99}, {"text": "in in this class that mixes\ndifferent sources of energy", "start": 778.64, "duration": 2.98}, {"text": "together.", "start": 781.62, "duration": 0.72}, {"text": "And so we try to get an average\nintensity of greenhouse gas", "start": 782.34, "duration": 3.9}, {"text": "emissions per unit\nof electricity", "start": 786.24, "duration": 2.04}, {"text": "in different regions.", "start": 788.28, "duration": 1.77}, {"text": "Another emissions\nintensity factor", "start": 790.05, "duration": 1.98}, {"text": "that people look at quite\noften is air quality.", "start": 792.03, "duration": 2.35}, {"text": "You can look at how many\ngreenhouse gases or how", "start": 794.38, "duration": 2.72}, {"text": "much particulate matter is\nproduced by certain activities,", "start": 797.1, "duration": 4.05}, {"text": "like vehicle miles traveled\nor number of cars on the road.", "start": 801.15, "duration": 4.87}, {"text": "So just to give you an example\nof what carbon emission", "start": 806.02, "duration": 2.25}, {"text": "intensity looks like, this is\nthe carbon emission intensity", "start": 808.27, "duration": 3.63}, {"text": "of economies in 2018, and this\nis from Our World in Data.", "start": 811.9, "duration": 4.26}, {"text": "And you can see,\nactually, it's measured,", "start": 816.16, "duration": 2.04}, {"text": "on the bottom legend here, in\nterms of amount of kilograms", "start": 818.2, "duration": 4.74}, {"text": "of carbon dioxide equivalent,\nthe carbon dioxide intensity,", "start": 822.94, "duration": 4.59}, {"text": "per dollar of GDP measured\nin international 2011 prices.", "start": 827.53, "duration": 5.02}, {"text": "And you can see, by\nthat measure, actually,", "start": 832.55, "duration": 2.51}, {"text": "a lot of the developed world,\nsuch as Australia, Europe,", "start": 835.06, "duration": 3.9}, {"text": "North America, and\nparts of Latin America", "start": 838.96, "duration": 2.91}, {"text": "don't look very intense,\nif only because they", "start": 841.87, "duration": 2.7}, {"text": "don't produce that\nmany greenhouse", "start": 844.57, "duration": 1.74}, {"text": "gases per dollar of GDP output.", "start": 846.31, "duration": 3.36}, {"text": "Now, like we talked\nabout in the last class", "start": 849.67, "duration": 2.76}, {"text": "in terms of population,\nwhat does this hide?", "start": 852.43, "duration": 3.513}, {"text": "Well, there's a couple\nof things with the map.", "start": 855.943, "duration": 1.917}, {"text": "Sometimes the area of the\nmap distorts the actual area", "start": 857.86, "duration": 3.6}, {"text": "or total emissions.", "start": 861.46, "duration": 1.26}, {"text": "Small places don't look like\nthey have as much impact", "start": 862.72, "duration": 2.58}, {"text": "as big places, even\nthough that really has", "start": 865.3, "duration": 2.01}, {"text": "nothing to do with the average.", "start": 867.31, "duration": 1.65}, {"text": "But the more important\npoint from a map like this", "start": 868.96, "duration": 2.76}, {"text": "is that it hides the fact\nthat the rich countries,", "start": 871.72, "duration": 2.97}, {"text": "like Australia, Europe,\nNorth America, and parts", "start": 874.69, "duration": 3.81}, {"text": "of Latin America, simply\nhave much larger GDPs.", "start": 878.5, "duration": 3.21}, {"text": "So it looks like the carbon\ndioxide output per GDP is low.", "start": 881.71, "duration": 5.74}, {"text": "But if we look at the\nper-capita CO2 emissions,", "start": 887.45, "duration": 2.48}, {"text": "like the point at\nour last class,", "start": 889.93, "duration": 1.552}, {"text": "you can see that, for a\nrelatively small number", "start": 891.482, "duration": 1.958}, {"text": "of people in those rich,\ndeveloped countries,", "start": 893.44, "duration": 2.25}, {"text": "they have very high CO2\nemissions per capita.", "start": 895.69, "duration": 3.06}, {"text": "And so your map basically\nchanges diametrically.", "start": 898.75, "duration": 2.988}, {"text": "And you can see the difference\nbetween richer countries", "start": 901.738, "duration": 2.292}, {"text": "and poor countries.", "start": 904.03, "duration": 1.05}, {"text": "And overwhelmingly,\nthe richer countries", "start": 905.08, "duration": 2.22}, {"text": "are more responsible for\ncarbon dioxide emissions.", "start": 907.3, "duration": 4.48}, {"text": "If we look at this\nsimilarly in a scatterplot,", "start": 911.78, "duration": 3.54}, {"text": "you can, again,\nsee that it looks", "start": 915.32, "duration": 2.07}, {"text": "like, on an emission\nintensity basis,", "start": 917.39, "duration": 2.165}, {"text": "India and the United States\nare not that different.", "start": 919.555, "duration": 2.125}, {"text": "Of course, the\ndifference is, in terms", "start": 921.68, "duration": 2.22}, {"text": "of the output of the economy\non a per-capita basis,", "start": 923.9, "duration": 3.09}, {"text": "the average person\nin the United States", "start": 926.99, "duration": 2.37}, {"text": "produces much more and\ninevitably consumes much more", "start": 929.36, "duration": 3.36}, {"text": "than your average person\nin India or Pakistan.", "start": 932.72, "duration": 2.22}, {"text": "So even though we have\nequivalent emissions intensity", "start": 934.94, "duration": 3.87}, {"text": "per dollar, we simply\nproduce and consume", "start": 938.81, "duration": 2.91}, {"text": "much more in the\nricher countries.", "start": 941.72, "duration": 1.98}, {"text": "And I make this point because,\nafter the Kyoto Protocol", "start": 943.7, "duration": 4.02}, {"text": "and after the George\nW. Bush administration", "start": 947.72, "duration": 3.03}, {"text": "chose to leave the\nKyoto Protocol,", "start": 950.75, "duration": 1.95}, {"text": "one of their arguments\nwas that the US actually", "start": 952.7, "duration": 2.94}, {"text": "had a lower carbon emission\nintensity, or at least", "start": 955.64, "duration": 3.54}, {"text": "a comparable carbon\nemission intensity,", "start": 959.18, "duration": 2.43}, {"text": "to some developing countries.", "start": 961.61, "duration": 1.77}, {"text": "Of course, this hid the\nfact that the United States", "start": 963.38, "duration": 3.39}, {"text": "is both richer and consumes much\nmore and produces much more.", "start": 966.77, "duration": 4.63}, {"text": "So that's just a way to talk\nabout what intensities may tell", "start": 971.4, "duration": 3.65}, {"text": "us and what they may hide also.", "start": 975.05, "duration": 3.05}, {"text": "Now I'll get to a\nreally key diagram", "start": 978.1, "duration": 2.04}, {"text": "that I rather love\nin this class.", "start": 980.14, "duration": 1.96}, {"text": "So I'll start off this class by\ntalking about Sankey diagrams.", "start": 982.1, "duration": 3.77}, {"text": "And you can find a\nSankey diagram for the US", "start": 985.87, "duration": 2.22}, {"text": "and every state at this web\nlink at part of the bottom", "start": 988.09, "duration": 3.09}, {"text": "from Lawrence Livermore\nNational Laboratory.", "start": 991.18, "duration": 2.91}, {"text": "What a Sankey diagram is\nis basically a flow chart,", "start": 994.09, "duration": 3.18}, {"text": "and it's a flow chart between\nthe sources on the left.", "start": 997.27, "duration": 2.368}, {"text": "And you can see all of\nour energy sources, solar,", "start": 999.638, "duration": 2.042}, {"text": "nuclear, hydro, wind,\ngeothermal, natural gas, coal,", "start": 1001.68, "duration": 3.24}, {"text": "biomass, and petroleum.", "start": 1004.92, "duration": 1.56}, {"text": "And you can see all of the\nultimate uses on the right.", "start": 1006.48, "duration": 3.6}, {"text": "And the final--", "start": 1010.08, "duration": 1.63}, {"text": "I guess what we'd call\nfinal consumption is", "start": 1011.71, "duration": 2.0}, {"text": "in residential buildings,\ncommercial buildings,", "start": 1013.71, "duration": 1.96}, {"text": "industrial buildings,\nand transportation.", "start": 1015.67, "duration": 2.24}, {"text": "Of course, this\nfinal category here", "start": 1017.91, "duration": 2.55}, {"text": "is also a kind of a statement\nabout where does the energy go", "start": 1020.46, "duration": 3.12}, {"text": "in the first place.", "start": 1023.58, "duration": 1.32}, {"text": "Only about 50% of the energy\nor less that we actually", "start": 1024.9, "duration": 4.35}, {"text": "burn from the original\nsources goes into these uses", "start": 1029.25, "duration": 5.16}, {"text": "in these sectors.", "start": 1034.41, "duration": 1.53}, {"text": "About, actually, looks like\none third of the energy", "start": 1035.94, "duration": 3.12}, {"text": "goes to what we call\nenergy services.", "start": 1039.06, "duration": 2.64}, {"text": "And rejected energy\nis the byproduct", "start": 1041.7, "duration": 2.79}, {"text": "of that combustion, usually,\nthat we don't capture", "start": 1044.49, "duration": 3.57}, {"text": "for actual energy services.", "start": 1048.06, "duration": 1.35}, {"text": "So to give you an\nexample, you can see how--", "start": 1049.41, "duration": 2.79}, {"text": "I said before, the electric\ngrid mixes many different types", "start": 1052.2, "duration": 3.72}, {"text": "of energy sources--", "start": 1055.92, "duration": 1.71}, {"text": "solar, nuclear, hydro, wind,\nall these, natural gas, and coal", "start": 1057.63, "duration": 4.89}, {"text": "all feed into the electric grid.", "start": 1062.52, "duration": 1.95}, {"text": "But when we feed that energy\ninto the electric grid,", "start": 1064.47, "duration": 2.46}, {"text": "into power plants, we basically\nonly take a fraction of it.", "start": 1066.93, "duration": 3.12}, {"text": "It looks like about one\nthird of the electricity,", "start": 1070.05, "duration": 2.7}, {"text": "one third of the energy\nin those energy sources,", "start": 1072.75, "duration": 2.16}, {"text": "actually goes to things like\nresidential, commercial,", "start": 1074.91, "duration": 3.07}, {"text": "and industrial.", "start": 1077.98, "duration": 0.77}, {"text": "But about 2/3 of\nit gets rejected,", "start": 1078.75, "duration": 2.26}, {"text": "which means that it's\nheat energy going out", "start": 1081.01, "duration": 2.54}, {"text": "of the chimney of a\ncoal-fired power plant,", "start": 1083.55, "duration": 2.64}, {"text": "or might be energy lost in\nthe electric grid that's", "start": 1086.19, "duration": 2.52}, {"text": "simply lost because\nof the resistance", "start": 1088.71, "duration": 1.86}, {"text": "of the electrical wires.", "start": 1090.57, "duration": 2.01}, {"text": "And so this kind of\ngraph, I actually", "start": 1092.58, "duration": 2.25}, {"text": "find tremendously\nuseful to summarize", "start": 1094.83, "duration": 2.55}, {"text": "what the sources\non the left are,", "start": 1097.38, "duration": 2.4}, {"text": "the ultimate uses of the\nenergy are on the right,", "start": 1099.78, "duration": 3.03}, {"text": "and also some of the\ninterim steps where", "start": 1102.81, "duration": 2.103}, {"text": "we might be able to\ncapture some of the energy", "start": 1104.913, "duration": 1.917}, {"text": "back in terms of energy\nefficiency or at least", "start": 1106.83, "duration": 2.49}, {"text": "think about how our\nintermediate technologies,", "start": 1109.32, "duration": 2.25}, {"text": "like the electric grid,\nactually use energy", "start": 1111.57, "duration": 2.61}, {"text": "and how much of the intrinsic\nenergy in the fuel source", "start": 1114.18, "duration": 3.06}, {"text": "are we using.", "start": 1117.24, "duration": 1.53}, {"text": "To take one example\nfrom this graph,", "start": 1118.77, "duration": 2.52}, {"text": "I think it does a really\ngood job of showing you,", "start": 1121.29, "duration": 2.17}, {"text": "for example, that\nelectricity overwhelmingly", "start": 1123.46, "duration": 2.06}, {"text": "goes into residential\nbuildings, commercial buildings,", "start": 1125.52, "duration": 2.34}, {"text": "and industrial buildings\nor industrial activities,", "start": 1127.86, "duration": 3.325}, {"text": "but you can see that there is\nno link between electricity", "start": 1131.185, "duration": 2.375}, {"text": "generation and transportation,\nso a very small orange line", "start": 1133.56, "duration": 3.03}, {"text": "here, 0.02 quads.", "start": 1136.59, "duration": 3.572}, {"text": "And once again, I\nshould have pointed out", "start": 1140.162, "duration": 1.708}, {"text": "is that the total US\nenergy consumption in 2021", "start": 1141.87, "duration": 2.7}, {"text": "was at 97 quads.", "start": 1144.57, "duration": 1.83}, {"text": "It's pretty easy mentally to\nround that up to about 100.", "start": 1146.4, "duration": 3.18}, {"text": "So this is actually\n0.02%, roughly,", "start": 1149.58, "duration": 3.66}, {"text": "of all the energy in\nthe US or electricity", "start": 1153.24, "duration": 3.06}, {"text": "is used for transportation.", "start": 1156.3, "duration": 1.41}, {"text": "You can see, overwhelmingly,\nthat the majority of energy", "start": 1157.71, "duration": 3.03}, {"text": "for transportation, 24.3 quads,\nor about 24% going to the US,", "start": 1160.74, "duration": 5.7}, {"text": "comes from petroleum.", "start": 1166.44, "duration": 1.35}, {"text": "And originally, that came from\nabout 35 quads of-- or 35%", "start": 1167.79, "duration": 5.25}, {"text": "of our initial energy sources.", "start": 1173.04, "duration": 2.46}, {"text": "And you can see some\nportion goes off", "start": 1175.5, "duration": 1.77}, {"text": "to industrial activities.", "start": 1177.27, "duration": 1.38}, {"text": "But the vast majority\nof the energy", "start": 1178.65, "duration": 1.8}, {"text": "that drives our transportation\nsystem is petroleum.", "start": 1180.45, "duration": 3.24}, {"text": "And you can see that, when\nwe burn petroleum or gasoline", "start": 1183.69, "duration": 4.05}, {"text": "in our internal\ncombustion engines,", "start": 1187.74, "duration": 2.16}, {"text": "a very small fraction-- it\nlooks like about 20% of it--", "start": 1189.9, "duration": 3.27}, {"text": "is actually used for\nmoving the car forward.", "start": 1193.17, "duration": 3.36}, {"text": "About 80% of the energy actually\ngoes out of the tailpipe", "start": 1196.53, "duration": 3.42}, {"text": "either in the form of heat out\nof the tailpipe or else air", "start": 1199.95, "duration": 3.84}, {"text": "resistance.", "start": 1203.79, "duration": 0.57}, {"text": "That is not really what\nwe are trying to do.", "start": 1204.36, "duration": 2.17}, {"text": "We're trying to move goods and\nservices and people around.", "start": 1206.53, "duration": 3.91}, {"text": "And so this is\njust, again, a way", "start": 1210.44, "duration": 1.817}, {"text": "of saying that there's lots\nof different kinds of Sankey", "start": 1212.257, "duration": 2.333}, {"text": "diagrams.", "start": 1214.59, "duration": 0.63}, {"text": "This is a nice one that\nit has proportional flows", "start": 1215.22, "duration": 2.82}, {"text": "between sources, intermediate,\ntransforming technologies,", "start": 1218.04, "duration": 3.78}, {"text": "and usages.", "start": 1221.82, "duration": 1.14}, {"text": "It also shows you\nwhat efficiency level", "start": 1222.96, "duration": 2.58}, {"text": "is being achieved in\nthese different sectors.", "start": 1225.54, "duration": 2.34}, {"text": "This is essentially an\naccounting exercise,", "start": 1227.88, "duration": 2.29}, {"text": "but if you can find a\nSankey diagram for a given", "start": 1230.17, "duration": 2.36}, {"text": "region or a city\nor a country, it", "start": 1232.53, "duration": 2.263}, {"text": "gives you a really\ngood picture of where", "start": 1234.793, "duration": 1.667}, {"text": "the energy is coming from and\nwhere the energy is going to.", "start": 1236.46, "duration": 3.7}, {"text": "So we want to use\nthese Sankey diagrams", "start": 1240.16, "duration": 1.86}, {"text": "to think about what our pathways\nare to deep decarbonization.", "start": 1242.02, "duration": 3.48}, {"text": "Deep decarbonization-- I\nthink I've said before,", "start": 1245.5, "duration": 2.59}, {"text": "if I haven't said it before--", "start": 1248.09, "duration": 1.52}, {"text": "it is both a goal and a process.", "start": 1249.61, "duration": 2.53}, {"text": "We know that climate\nscience tells us--", "start": 1252.14, "duration": 2.66}, {"text": "the IPCC has told us through an\nexhaustive scientific process", "start": 1254.8, "duration": 3.93}, {"text": "that we need to achieve net-zero\nanthropogenic greenhouse gas", "start": 1258.73, "duration": 3.69}, {"text": "emissions by 2050.", "start": 1262.42, "duration": 1.71}, {"text": "Deep decarbonization\nis both the goal", "start": 1264.13, "duration": 2.49}, {"text": "of getting to net-zero\nemissions by 2050,", "start": 1266.62, "duration": 3.06}, {"text": "and also, it's this process.", "start": 1269.68, "duration": 1.44}, {"text": "We're decarbonizing\nfor the next 28 years", "start": 1271.12, "duration": 2.76}, {"text": "to lessen the effects\nof climate change.", "start": 1273.88, "duration": 3.16}, {"text": "And so the first deep\ndecarbonization plan", "start": 1277.04, "duration": 2.75}, {"text": "started in 2015.", "start": 1279.79, "duration": 2.25}, {"text": "The Deep Decarbonization\nPathways Project", "start": 1282.04, "duration": 2.7}, {"text": "started 2015 for a\nnumber of countries", "start": 1284.74, "duration": 1.86}, {"text": "to try to think about\nwhat analytical or policy", "start": 1286.6, "duration": 3.03}, {"text": "or technology\npathways we needed.", "start": 1289.63, "duration": 1.83}, {"text": "It was updated in\nthis paper in 2020", "start": 1291.46, "duration": 2.04}, {"text": "that you read for this class.", "start": 1293.5, "duration": 1.77}, {"text": "That was quickly followed by\nthe White House Mid-Century", "start": 1295.27, "duration": 2.91}, {"text": "Strategy, which was the Obama\nadministration's commitment", "start": 1298.18, "duration": 2.82}, {"text": "to the Paris Agreement to reduce\ngreenhouse gas emissions by 80%", "start": 1301.0, "duration": 3.39}, {"text": "by 2050.", "start": 1304.39, "duration": 1.17}, {"text": "But just four years later,\nyou have a series of reports", "start": 1305.56, "duration": 2.67}, {"text": "from academics and\nNGOs looking at ways", "start": 1308.23, "duration": 3.78}, {"text": "to get to 100%\nreduction by 2050,", "start": 1312.01, "duration": 2.74}, {"text": "which is what the IPCC\nsays we need to do by 2050.", "start": 1314.75, "duration": 4.56}, {"text": "And so the key thing I\nwant to say in this class", "start": 1319.31, "duration": 2.93}, {"text": "but also in the paper I\nreferred to last time last week,", "start": 1322.24, "duration": 4.625}, {"text": "the paper on deep\ndecarbonization", "start": 1326.865, "duration": 1.375}, {"text": "that I wrote recently, is\nthat many of these plans", "start": 1328.24, "duration": 2.73}, {"text": "agree what the\ntechnology pathways are.", "start": 1330.97, "duration": 2.2}, {"text": "So we should focus as\nurban policy analysts", "start": 1333.17, "duration": 4.67}, {"text": "and urban planners\nand people who work", "start": 1337.84, "duration": 1.68}, {"text": "in cities on implementation.", "start": 1339.52, "duration": 2.28}, {"text": "We should focus on geography.", "start": 1341.8, "duration": 1.53}, {"text": "We should focus on\nthe politics of it.", "start": 1343.33, "duration": 1.77}, {"text": "And, frankly, as planners, we\nshould look at the land use", "start": 1345.1, "duration": 3.12}, {"text": "and built environment\nimplications", "start": 1348.22, "duration": 2.01}, {"text": "of deep decarbonization.", "start": 1350.23, "duration": 3.19}, {"text": "So look at the Sankey diagram\nfrom Williams et al., 2020.", "start": 1353.42, "duration": 3.63}, {"text": "They look at the reference\ncase for energy use", "start": 1357.05, "duration": 5.725}, {"text": "in the United States.", "start": 1362.775, "duration": 0.875}, {"text": "And this is a reference case\nI think the Energy Information", "start": 1363.65, "duration": 2.73}, {"text": "Administration puts\nout every year.", "start": 1366.38, "duration": 2.88}, {"text": "You can see on\nthe left-hand side", "start": 1369.26, "duration": 1.44}, {"text": "that, overwhelmingly,\nthe reference case, which", "start": 1370.7, "duration": 2.55}, {"text": "is usually fairly\nconservative, shows", "start": 1373.25, "duration": 2.07}, {"text": "that we will get\nmost of our energy", "start": 1375.32, "duration": 2.22}, {"text": "from-- we get most of our energy\ncurrently from uranium, coal,", "start": 1377.54, "duration": 3.31}, {"text": "natural gas, a little\nbit from biomass,", "start": 1380.85, "duration": 2.21}, {"text": "and a large portion\nfrom petroleum.", "start": 1383.06, "duration": 2.4}, {"text": "You can see renewables\nhere are relatively small--", "start": 1385.46, "duration": 2.7}, {"text": "geothermal, solar,\nwind, and hydro.", "start": 1388.16, "duration": 2.7}, {"text": "And all the energy goes through\nthe intermediate steps--", "start": 1390.86, "duration": 3.03}, {"text": "electricity generation,\npipeline gas, petroleum refining", "start": 1393.89, "duration": 3.48}, {"text": "outputs, or liquid fuels.", "start": 1397.37, "duration": 1.98}, {"text": "It gets transmitted\nthrough the electric grid,", "start": 1399.35, "duration": 1.95}, {"text": "and it ultimately\ngoes to buildings,", "start": 1401.3, "duration": 1.92}, {"text": "which are residential and\ncommercial buildings together.", "start": 1403.22, "duration": 2.52}, {"text": "It goes to industry, and\nit goes to transportation.", "start": 1405.74, "duration": 2.76}, {"text": "Again, you can see\nhere from buildings", "start": 1408.5, "duration": 2.19}, {"text": "that, overwhelmingly,\nabout half of the energy", "start": 1410.69, "duration": 2.4}, {"text": "comes from the grid, and\nhalf the energy comes", "start": 1413.09, "duration": 1.92}, {"text": "from pipeline gas.", "start": 1415.01, "duration": 1.44}, {"text": "Transportation, almost all\nthe energy we currently use", "start": 1416.45, "duration": 3.15}, {"text": "comes from petroleum.", "start": 1419.6, "duration": 3.12}, {"text": "And industry uses a variety of\nenergy technologies and fuels.", "start": 1422.72, "duration": 4.35}, {"text": "Now let's contrast that with\nthe Williams paper on what", "start": 1427.07, "duration": 3.6}, {"text": "a 100%-renewable-energy\nfuture would look like.", "start": 1430.67, "duration": 3.31}, {"text": "There's a couple of\nthings to notice here.", "start": 1433.98, "duration": 1.98}, {"text": "First, all of our renewables,\nthe 100% renewable sources", "start": 1435.96, "duration": 3.14}, {"text": "we are going to need, have taken\nover completely-- geothermal,", "start": 1439.1, "duration": 3.84}, {"text": "solar, wind, hydro, and biomass.", "start": 1442.94, "duration": 2.26}, {"text": "There's no coal, no natural\ngas, and no petroleum.", "start": 1445.2, "duration": 3.8}, {"text": "Overwhelmingly, about\n2/3 of the energy", "start": 1449.0, "duration": 1.98}, {"text": "will go through\nthe electric grid.", "start": 1450.98, "duration": 1.9}, {"text": "It will be generated\nas electricity,", "start": 1452.88, "duration": 2.36}, {"text": "either goes through\nthe grid or be", "start": 1455.24, "duration": 2.0}, {"text": "used to produce\nhydrogen. Hydrogen will", "start": 1457.24, "duration": 2.35}, {"text": "produce various liquid\nand gaseous fuels.", "start": 1459.59, "duration": 3.76}, {"text": "And if you look at what the\nfuture looks like in 2050", "start": 1463.35, "duration": 2.54}, {"text": "according to this paper or\nthis technology pathway,", "start": 1465.89, "duration": 3.282}, {"text": "you can see that buildings\nhave to overwhelmingly get", "start": 1469.172, "duration": 2.208}, {"text": "their energy from electricity.", "start": 1471.38, "duration": 1.83}, {"text": "Industry will still use\na variety of inputs,", "start": 1473.21, "duration": 2.1}, {"text": "but all those inputs will be\nfrom intermediate steps that", "start": 1475.31, "duration": 3.57}, {"text": "have transformed our renewable\nenergy into the kinds of fuels", "start": 1478.88, "duration": 3.82}, {"text": "we need to drive\nindustrial processes.", "start": 1482.7, "duration": 1.88}, {"text": "And you can see\nthat transportation", "start": 1484.58, "duration": 2.19}, {"text": "is going to come\noverwhelmingly from electric.", "start": 1486.77, "duration": 3.03}, {"text": "About 50% of our energy\nin transportation", "start": 1489.8, "duration": 2.39}, {"text": "will come from electric.", "start": 1492.19, "duration": 1.0}, {"text": "Some of it will come from,\nI think, liquid fuels,", "start": 1493.19, "duration": 3.15}, {"text": "and some will come\nfrom compressed gases,", "start": 1496.34, "duration": 3.63}, {"text": "such as hydrogen and\nmaybe natural gas", "start": 1499.97, "duration": 2.7}, {"text": "or methane produced from\nrenewable resources.", "start": 1502.67, "duration": 5.04}, {"text": "And let's just look at the\nimplications from this,", "start": 1507.71, "duration": 2.16}, {"text": "and this is to read the numbers\noff those previous two graphs.", "start": 1509.87, "duration": 3.42}, {"text": "And then you look\nat the power sector.", "start": 1513.29, "duration": 2.34}, {"text": "You can see that petroleum,\nnatural gas, and coal,", "start": 1515.63, "duration": 2.49}, {"text": "as I said, have to be\neliminated completely, 100%.", "start": 1518.12, "duration": 4.17}, {"text": "Biomass has to grow\nby 3 and 1/2 times.", "start": 1522.29, "duration": 3.66}, {"text": "Nuclear power, in the\n100% renewable case,", "start": 1525.95, "duration": 2.85}, {"text": "is actually\neliminated completely", "start": 1528.8, "duration": 1.56}, {"text": "because I think Williams et\nal. do not define nuclear", "start": 1530.36, "duration": 2.88}, {"text": "as a renewable energy source.", "start": 1533.24, "duration": 1.74}, {"text": "But the key things,\nthe most dire, I think,", "start": 1534.98, "duration": 3.09}, {"text": "or most challenging things\nwe have to deal with", "start": 1538.07, "duration": 3.18}, {"text": "are growing our solar energy\nshare by about a factor of 46.", "start": 1541.25, "duration": 4.86}, {"text": "We have to grow our share\nfrom wind by a factor of 27.", "start": 1546.11, "duration": 3.75}, {"text": "Hydro and geothermal are going\nto be relatively small players", "start": 1549.86, "duration": 3.06}, {"text": "in this forecast.", "start": 1552.92, "duration": 1.23}, {"text": "And that's just for the\nelectric power sector.", "start": 1554.15, "duration": 2.83}, {"text": "If you look at buildings,\nresidential/commercial,", "start": 1556.98, "duration": 2.24}, {"text": "you can see two things.", "start": 1559.22, "duration": 1.63}, {"text": "Not only does electricity\nhave to decline in total use,", "start": 1560.85, "duration": 4.76}, {"text": "but we have to completely\neliminate natural gas.", "start": 1565.61, "duration": 2.82}, {"text": "And we have to increase our\nuse of biomass just slightly.", "start": 1568.43, "duration": 4.59}, {"text": "Now, the key thing\nis that the reason", "start": 1573.02, "duration": 1.95}, {"text": "why we're declining our\ntotal use of electricity", "start": 1574.97, "duration": 2.7}, {"text": "is that it's more efficient.", "start": 1577.67, "duration": 1.218}, {"text": "But at the same\ntime, the electricity", "start": 1578.888, "duration": 1.542}, {"text": "we do use is going to\nbe used to do things", "start": 1580.43, "duration": 2.52}, {"text": "that natural gas\ncurrently does, like we're", "start": 1582.95, "duration": 2.22}, {"text": "going to get heating and cooling\nfrom electricity rather than", "start": 1585.17, "duration": 3.42}, {"text": "from natural gas as we do now.", "start": 1588.59, "duration": 2.17}, {"text": "And so this is one\nimportant point", "start": 1590.76, "duration": 1.492}, {"text": "I want to highlight\nfrom Sankey diagrams.", "start": 1592.252, "duration": 1.708}, {"text": "If you look at the total\nprimary energy in buildings,", "start": 1593.96, "duration": 2.73}, {"text": "it actually has to\ngo down by about 50%.", "start": 1596.69, "duration": 2.738}, {"text": "And this is the point I think\nI made in the last class, which", "start": 1599.428, "duration": 2.542}, {"text": "is, if you look back here,\nthe total amount of energy--", "start": 1601.97, "duration": 4.2}, {"text": "it looks like, I think,\nroughly 100 quads,", "start": 1606.17, "duration": 2.01}, {"text": "also 100 exajoules I think is\nhow this paper measures it.", "start": 1608.18, "duration": 3.28}, {"text": "And if you look\nat the next slide,", "start": 1611.46, "duration": 1.68}, {"text": "you can see that the\nwidth of these flows", "start": 1613.14, "duration": 2.12}, {"text": "have gone down quite a bit,\nwhich is just to make the point", "start": 1615.26, "duration": 3.42}, {"text": "that I think I said to\nyou last week, which", "start": 1618.68, "duration": 1.83}, {"text": "is that not only do our uses\nhave to become more efficient,", "start": 1620.51, "duration": 3.94}, {"text": "we also have to simply reduce\nthe total amount we're using.", "start": 1624.45, "duration": 4.07}, {"text": "And the remaining 50%\nhave to become renewable.", "start": 1628.52, "duration": 2.37}, {"text": "So we actually need a\ncomplete transformation", "start": 1630.89, "duration": 1.92}, {"text": "of our energy system both\non the consumption side", "start": 1632.81, "duration": 2.7}, {"text": "and the production side.", "start": 1635.51, "duration": 2.18}, {"text": "If you look at the\nTong paper, this", "start": 1637.69, "duration": 3.39}, {"text": "is going to shift a little bit\nto this question of existing", "start": 1641.08, "duration": 3.42}, {"text": "energy infrastructure.", "start": 1644.5, "duration": 1.56}, {"text": "This is a paper written\nin 2019 in Nature.", "start": 1646.06, "duration": 3.78}, {"text": "And in this paper,\nthey say our estimates", "start": 1649.84, "duration": 2.1}, {"text": "suggest that little or no new\nCO2-emitting infrastructure", "start": 1651.94, "duration": 4.17}, {"text": "can be commissioned, and that\nexisting infrastructure may", "start": 1656.11, "duration": 2.88}, {"text": "need to be retired early or be\nretrofitted with carbon capture", "start": 1658.99, "duration": 3.54}, {"text": "and storage technology in order\nto meet the Paris Agreement", "start": 1662.53, "duration": 3.0}, {"text": "climate goals.", "start": 1665.53, "duration": 1.15}, {"text": "So this paper is basically\ngoing to show us that we have", "start": 1666.68, "duration": 2.96}, {"text": "existing infrastructure--\nobviously,", "start": 1669.64, "duration": 1.74}, {"text": "the energy infrastructure\nthat we use every day--", "start": 1671.38, "duration": 2.327}, {"text": "and if we want to meet our\nParis Agreement climate", "start": 1673.707, "duration": 2.083}, {"text": "goals, which is\nkeeping, preferably,", "start": 1675.79, "duration": 2.13}, {"text": "global average temperatures less\nthan 1.5 degrees Celsius higher", "start": 1677.92, "duration": 4.35}, {"text": "than pre-Industrial\nera, we actually", "start": 1682.27, "duration": 2.37}, {"text": "need to build no more fossil\nfuel infrastructure, which", "start": 1684.64, "duration": 3.99}, {"text": "is CO2-emitting infrastructure.", "start": 1688.63, "duration": 1.65}, {"text": "And we may have to retire some\nof the energy infrastructure", "start": 1690.28, "duration": 2.64}, {"text": "that we have early before\nit's planned lifetime.", "start": 1692.92, "duration": 3.48}, {"text": "This is part of the struggle.", "start": 1696.4, "duration": 2.16}, {"text": "This is why you have\nactivists trying", "start": 1698.56, "duration": 1.71}, {"text": "to retire coal-fired\npower plants", "start": 1700.27, "duration": 3.27}, {"text": "and avoid building new\npipelines and natural gas plants", "start": 1703.54, "duration": 3.45}, {"text": "or having, let's say, gas bans\nfor new appliances in parts", "start": 1706.99, "duration": 4.35}, {"text": "of Massachusetts and\nCalifornia and other states.", "start": 1711.34, "duration": 3.012}, {"text": "So just to show\nyou what this looks", "start": 1714.352, "duration": 1.458}, {"text": "like, all these categories\nin the legend here--", "start": 1715.81, "duration": 2.907}, {"text": "commercial buildings,\nresidential buildings,", "start": 1718.717, "duration": 1.833}, {"text": "international transport,\nroad transport, industry,", "start": 1720.55, "duration": 2.083}, {"text": "electricity-- these\nkinds of technologies", "start": 1722.633, "duration": 2.357}, {"text": "have a natural lifetime\nin terms of they", "start": 1724.99, "duration": 3.51}, {"text": "have a committed CO2\nemission from existing", "start": 1728.5, "duration": 3.3}, {"text": "and proposed infrastructure.", "start": 1731.8, "duration": 1.66}, {"text": "And you can see that our\nexisting infrastructure", "start": 1733.46, "duration": 2.24}, {"text": "is overwhelmingly dominated\nby industry and electricity.", "start": 1735.7, "duration": 3.15}, {"text": "And road transport\nis this blue wedge,", "start": 1738.85, "duration": 2.22}, {"text": "and buildings are\nactually relatively small.", "start": 1741.07, "duration": 2.255}, {"text": "And those are all\nthings that are", "start": 1743.325, "duration": 1.375}, {"text": "going to phase out\nnaturally over time", "start": 1744.7, "duration": 2.22}, {"text": "because infrastructure gets old.", "start": 1746.92, "duration": 1.66}, {"text": "If you don't maintain it,\nand you don't rebuild it,", "start": 1748.58, "duration": 2.63}, {"text": "then it wears out, and\nyou can't use it anymore.", "start": 1751.21, "duration": 2.95}, {"text": "We've had more proposed\ninfrastructure,", "start": 1754.16, "duration": 2.18}, {"text": "but that proposed infrastructure\ncannot be built if we need", "start": 1756.34, "duration": 4.17}, {"text": "to try to meet our\nParis Climate goals.", "start": 1760.51, "duration": 2.58}, {"text": "At the same time, in\nthe B panel here, we", "start": 1763.09, "duration": 3.93}, {"text": "have the committed emissions\nfrom different countries.", "start": 1767.02, "duration": 3.1}, {"text": "And you can see the\nlifetime of infrastructure", "start": 1770.12, "duration": 2.09}, {"text": "in China is relatively\nlong and a large portion", "start": 1772.21, "duration": 4.23}, {"text": "of the future problem\nbecause so much of it", "start": 1776.44, "duration": 2.67}, {"text": "has been built fairly recently.", "start": 1779.11, "duration": 1.89}, {"text": "You can see the\nrest of the world", "start": 1781.0, "duration": 1.53}, {"text": "is actually only about 2/3 of\nthe problem that China poses.", "start": 1782.53, "duration": 4.53}, {"text": "And, actually, the US has\na relatively small future", "start": 1787.06, "duration": 2.67}, {"text": "committed emissions because\nthe nature of our technology.", "start": 1789.73, "duration": 3.34}, {"text": "Of course, there's been\nmany more proposed projects,", "start": 1793.07, "duration": 2.99}, {"text": "but the point of this paper is\nthat we cannot actually build", "start": 1796.06, "duration": 4.112}, {"text": "the proposed infrastructure,\nand we may have to retire some", "start": 1800.172, "duration": 2.458}, {"text": "of those existing infrastructure\nearly to avoid going over", "start": 1802.63, "duration": 3.36}, {"text": "our climate limits.", "start": 1805.99, "duration": 2.02}, {"text": "So another kind of interesting\ngraph in this paper which", "start": 1808.01, "duration": 2.69}, {"text": "I like quite a bit is\na population pyramid,", "start": 1810.7, "duration": 2.22}, {"text": "but it's a population\npyramid showing", "start": 1812.92, "duration": 2.91}, {"text": "the proportions of the\npopulation of people by age.", "start": 1815.83, "duration": 3.69}, {"text": "It actually shows\nthe age structure", "start": 1819.52, "duration": 1.77}, {"text": "of our global\nelectricity-generating", "start": 1821.29, "duration": 2.19}, {"text": "capacity.", "start": 1823.48, "duration": 1.02}, {"text": "And I want to simply\nmake a point about what", "start": 1824.5, "duration": 2.43}, {"text": "the different nature of the\nproblem in China and the US", "start": 1826.93, "duration": 3.36}, {"text": "are.", "start": 1830.29, "duration": 0.6}, {"text": "You can see on the\nleft-hand side--", "start": 1830.89, "duration": 2.49}, {"text": "this is the rest of the\nworld, in some ways,", "start": 1833.38, "duration": 2.34}, {"text": "dominated by the US.", "start": 1835.72, "duration": 1.03}, {"text": "You can see around\n15 or 17 years ago,", "start": 1836.75, "duration": 2.42}, {"text": "we've built quite a bit\nof natural gas or oil", "start": 1839.17, "duration": 2.85}, {"text": "infrastructure.", "start": 1842.02, "duration": 1.445}, {"text": "You can see the\nrest of the world", "start": 1843.465, "duration": 1.375}, {"text": "has more recently been\nbuilding gas and oil", "start": 1844.84, "duration": 2.61}, {"text": "infrastructure,\nthese yellow bars.", "start": 1847.45, "duration": 1.843}, {"text": "And you can see on\nthe right-hand side--", "start": 1849.293, "duration": 1.667}, {"text": "this is electricity\ngeneration from coal,", "start": 1850.96, "duration": 3.27}, {"text": "and that is overwhelmingly\ndominated by coal-fired power", "start": 1854.23, "duration": 2.85}, {"text": "plants built in China mostly\nin the last 12 or 14 years.", "start": 1857.08, "duration": 4.48}, {"text": "The reason why we\nuse this graph is", "start": 1861.56, "duration": 1.52}, {"text": "to look at the\nnature of the problem", "start": 1863.08, "duration": 1.5}, {"text": "and what particular sectors\nwe're going to have to tackle", "start": 1864.58, "duration": 2.863}, {"text": "or which particular\npower plants we have", "start": 1867.443, "duration": 1.667}, {"text": "to tackle to avoid creating more\ngreenhouse gas emissions that,", "start": 1869.11, "duration": 4.2}, {"text": "again, will put us beyond our\nParis Agreement targets, that", "start": 1873.31, "duration": 3.03}, {"text": "will then finally jeopardize\nthe climate of the planet.", "start": 1876.34, "duration": 6.89}, {"text": "So this brings me to\ncities, which is--", "start": 1883.23, "duration": 3.41}, {"text": "numerous recent studies show\nthat most US greenhouse gas", "start": 1886.64, "duration": 3.06}, {"text": "emissions or global\ngreenhouse gas", "start": 1889.7, "duration": 1.74}, {"text": "emissions in some of these\nstudies are from cities.", "start": 1891.44, "duration": 2.7}, {"text": "But the key point of this\nliterature I want to highlight", "start": 1894.14, "duration": 2.52}, {"text": "is that the exact\nproportion depends", "start": 1896.66, "duration": 1.86}, {"text": "on how and where you count.", "start": 1898.52, "duration": 2.75}, {"text": "The Jones et al.", "start": 1901.27, "duration": 1.11}, {"text": "2018 paper and the\nGoldstein et al 2020 paper", "start": 1902.38, "duration": 3.36}, {"text": "both find that higher incomes\nand lower population densities", "start": 1905.74, "duration": 3.36}, {"text": "are highly correlated\nwith higher carbon", "start": 1909.1, "duration": 2.01}, {"text": "footprints and energy use.", "start": 1911.11, "duration": 3.03}, {"text": "The Gurney et al 2018, 2020,\nand 2021 reports and papers", "start": 1914.14, "duration": 5.07}, {"text": "find that a majority\nof road and fossil fuel", "start": 1919.21, "duration": 2.7}, {"text": "infrastructure or use can\nbe associated with cities.", "start": 1921.91, "duration": 4.068}, {"text": "The Moran paper is\nquite interesting,", "start": 1925.978, "duration": 1.542}, {"text": "and it finds that, both\nin China and the US,", "start": 1927.52, "duration": 3.9}, {"text": "the largest 10 cities\nplus 5%, or the top 5%--", "start": 1931.42, "duration": 4.26}, {"text": "of suburban residents\nby income are", "start": 1935.68, "duration": 2.4}, {"text": "responsible for more than a\nmajority of the greenhouse", "start": 1938.08, "duration": 2.49}, {"text": "gas emissions from both\ncountries, China and the US,", "start": 1940.57, "duration": 3.39}, {"text": "which is to say that, if we\nfocused just on the largest 10", "start": 1943.96, "duration": 3.57}, {"text": "cities and the most\ncarbon-intensive suburbs, now", "start": 1947.53, "duration": 3.742}, {"text": "we could actually make\na significant difference", "start": 1951.272, "duration": 1.958}, {"text": "in the greenhouse gas\nemissions of the countries.", "start": 1953.23, "duration": 2.22}, {"text": "It is also kind of\nrecapping the moral argument", "start": 1955.45, "duration": 2.46}, {"text": "I made to you in the last\nclass, which is that the richest", "start": 1957.91, "duration": 3.69}, {"text": "people in both countries have a\ndisproportionate responsibility", "start": 1961.6, "duration": 4.65}, {"text": "to lower the greenhouse gas\nemissions just in the same way", "start": 1966.25, "duration": 2.61}, {"text": "that the US has a\ndisproportionate responsibility", "start": 1968.86, "duration": 2.28}, {"text": "to lower its greenhouse gas\nemissions relative to the rest", "start": 1971.14, "duration": 2.61}, {"text": "of the world.", "start": 1973.75, "duration": 1.17}, {"text": "Finally, the Seto in the\n2021 and the Wiedmann et al.", "start": 1974.92, "duration": 3.9}, {"text": "papers, 2021, show different\nresearch and planning", "start": 1978.82, "duration": 3.553}, {"text": "frameworks for how do we really\ncount these greenhouse gas", "start": 1982.373, "duration": 2.417}, {"text": "emissions.", "start": 1984.79, "duration": 0.5}, {"text": "And so there's debate\nabout how you count it,", "start": 1985.29, "duration": 2.23}, {"text": "but there's this emerging\nconsensus in the literature", "start": 1987.52, "duration": 3.06}, {"text": "that cities are responsible\nfor a large proportion", "start": 1990.58, "duration": 2.82}, {"text": "of greenhouse gas emissions\nin many countries,", "start": 1993.4, "duration": 2.98}, {"text": "including China and the US.", "start": 1996.38, "duration": 2.45}, {"text": "Just to highlight a\nfew of the key issues", "start": 1998.83, "duration": 1.8}, {"text": "why it's hard to get\nan exact proportion,", "start": 2000.63, "duration": 2.34}, {"text": "depends on different\ndefinitions of cities", "start": 2002.97, "duration": 2.16}, {"text": "or what an urban area is.", "start": 2005.13, "duration": 1.83}, {"text": "It depends which emissions\nyou count, upstream emissions,", "start": 2006.96, "duration": 3.24}, {"text": "like things that you import\nin the form of fuels or goods;", "start": 2010.2, "duration": 4.41}, {"text": "downstream emissions, the things\nthat you export out of the city", "start": 2014.61, "duration": 2.88}, {"text": "or waste energy or\nwaste products that", "start": 2017.49, "duration": 2.43}, {"text": "go outside of the city;\nand goods and services.", "start": 2019.92, "duration": 2.25}, {"text": "There's all different ways\nto count the emissions", "start": 2022.17, "duration": 1.56}, {"text": "from all of these things.", "start": 2023.73, "duration": 1.042}, {"text": "The C40 annual report that\nI assigned in the reading", "start": 2024.772, "duration": 3.668}, {"text": "gets to some of these issues.", "start": 2028.44, "duration": 2.77}, {"text": "Finally, some\ninteresting questions", "start": 2031.21, "duration": 1.88}, {"text": "that are not always\naccounted for-- cities", "start": 2033.09, "duration": 2.13}, {"text": "clearly shape local\nmicroclimates.", "start": 2035.22, "duration": 1.58}, {"text": "Do we count that as\npart of climate change,", "start": 2036.8, "duration": 2.57}, {"text": "because that actually changes\nhow people subsequently", "start": 2039.37, "duration": 2.27}, {"text": "use energy in cities?", "start": 2041.64, "duration": 1.222}, {"text": "And there's this kind of\nfundamental question--", "start": 2042.862, "duration": 1.958}, {"text": "how do you measure affluence?", "start": 2044.82, "duration": 1.56}, {"text": "Do you measure in terms\nof wealth or income?", "start": 2046.38, "duration": 2.25}, {"text": "I suspect if we measured\nthese in different ways,", "start": 2048.63, "duration": 2.819}, {"text": "you'd find different\nplaces responsible", "start": 2051.449, "duration": 2.551}, {"text": "for different levels of\ngreenhouse gas emissions.", "start": 2054.0, "duration": 2.699}, {"text": "Just again, to kind\nof make this argument", "start": 2056.699, "duration": 1.77}, {"text": "about how we measure\nthings matters", "start": 2058.469, "duration": 2.52}, {"text": "and also how intensity may\nshow us a different picture,", "start": 2060.989, "duration": 3.281}, {"text": "this is from the Gurney et al.", "start": 2064.27, "duration": 1.25}, {"text": "2020 paper.", "start": 2065.52, "duration": 1.44}, {"text": "The left-hand panel\nshows absolute emissions.", "start": 2066.96, "duration": 2.83}, {"text": "You can see the\nabsolute emissions", "start": 2069.79, "duration": 2.119}, {"text": "in this country basically\nalmost identically", "start": 2071.909, "duration": 3.0}, {"text": "mimics the spatial or\nurban spatial structure", "start": 2074.909, "duration": 3.031}, {"text": "of the country, where all the\nred areas and the left coast", "start": 2077.94, "duration": 5.07}, {"text": "are high concentrations\nof absolute emissions.", "start": 2083.01, "duration": 3.39}, {"text": "Of course, if you measure\non a per-capita basis,", "start": 2086.4, "duration": 2.1}, {"text": "you might say, OK,\nout West, people", "start": 2088.5, "duration": 1.83}, {"text": "are relatively inefficient.", "start": 2090.33, "duration": 1.758}, {"text": "But we should also\nhighlight the fact", "start": 2092.088, "duration": 1.542}, {"text": "that there's these\ninterrelationships", "start": 2093.63, "duration": 1.56}, {"text": "between these two areas.", "start": 2095.19, "duration": 1.87}, {"text": "Places out here in the West\nis a high concentration", "start": 2097.06, "duration": 3.08}, {"text": "of fossil fuel\nproduction/generation.", "start": 2100.14, "duration": 2.37}, {"text": "But where is that energy going?", "start": 2102.51, "duration": 2.19}, {"text": "That energy is going to cities.", "start": 2104.7, "duration": 1.68}, {"text": "And so we think back to MacKay's\nleft-hand bar of consumption.", "start": 2106.38, "duration": 4.71}, {"text": "I would argue to all the\nurban planners in the room--", "start": 2111.09, "duration": 2.68}, {"text": "and I've said this to my\ncolleagues in city government--", "start": 2113.77, "duration": 2.96}, {"text": "that we should not be\ncomplacent about the fact", "start": 2116.73, "duration": 2.19}, {"text": "that we think we have relatively\nlow per-capita emissions", "start": 2118.92, "duration": 3.72}, {"text": "in cities.", "start": 2122.64, "duration": 0.78}, {"text": "We have to be\nresponsible for the fact", "start": 2123.42, "duration": 2.04}, {"text": "that energy is being\nused elsewhere,", "start": 2125.46, "duration": 1.95}, {"text": "that we consume in the\nform of fuels, goods", "start": 2127.41, "duration": 3.27}, {"text": "and services, food, and\nwe export our waste also.", "start": 2130.68, "duration": 3.6}, {"text": "So that is the\nplace where cities", "start": 2134.28, "duration": 1.89}, {"text": "can have a big impact on\ngreenhouse gas emissions.", "start": 2136.17, "duration": 2.58}, {"text": "But it may be a different\nkind of efficiency.", "start": 2138.75, "duration": 2.01}, {"text": "We might have to think\nabout how much we consume,", "start": 2140.76, "duration": 2.94}, {"text": "why we consume energy, and how\ndo we do it more efficiently,", "start": 2143.7, "duration": 3.45}, {"text": "and, hopefully, ultimately\nreduce our consumption to meet", "start": 2147.15, "duration": 2.85}, {"text": "our decarbonization goals.", "start": 2150.0, "duration": 2.665}, {"text": "Finally, I'll just flash\nthrough the readings", "start": 2152.665, "duration": 1.875}, {"text": "quickly because we'll talk\nabout them more in class.", "start": 2154.54, "duration": 3.12}, {"text": "The Hsu et al 2019 paper--\nthis is actually not my paper.", "start": 2157.66, "duration": 3.12}, {"text": "It's written by a\ncolleague, Angel Hsu", "start": 2160.78, "duration": 2.7}, {"text": "at University of North Carolina.", "start": 2163.48, "duration": 1.77}, {"text": "It is a research roadmap for\nhow do we spend more time", "start": 2165.25, "duration": 2.94}, {"text": "or how do we spend more thinking\nabout quantifying the climate", "start": 2168.19, "duration": 3.96}, {"text": "mitigation actions that nonstate\nor subnational governments", "start": 2172.15, "duration": 4.68}, {"text": "could take.", "start": 2176.83, "duration": 0.69}, {"text": "And this is getting at\nthat measurement question.", "start": 2177.52, "duration": 2.38}, {"text": "How are we going to measure\ngreenhouse gas emissions?", "start": 2179.9, "duration": 2.42}, {"text": "And how are we going\nto measure what", "start": 2182.32, "duration": 1.5}, {"text": "action those entities take?", "start": 2183.82, "duration": 1.993}, {"text": "And just to give you\nan example, there's", "start": 2185.813, "duration": 1.667}, {"text": "different ways to count how\ncities take climate action", "start": 2187.48, "duration": 4.08}, {"text": "in comparison to state targets.", "start": 2191.56, "duration": 1.77}, {"text": "And those targets may\nbe different still", "start": 2193.33, "duration": 2.28}, {"text": "than national-level targets.", "start": 2195.61, "duration": 2.01}, {"text": "And so there's a question--\nare we going to double count?", "start": 2197.62, "duration": 2.91}, {"text": "In some cases, or,\nactually, most cases,", "start": 2200.53, "duration": 3.13}, {"text": "cities are more ambitious\nthan their states.", "start": 2203.66, "duration": 2.9}, {"text": "Cities are often more ambitious\nthan national governments.", "start": 2206.56, "duration": 3.53}, {"text": "We want to avoid\ndouble counting.", "start": 2210.09, "duration": 2.2}, {"text": "We want to assume--", "start": 2212.29, "duration": 1.23}, {"text": "we want to count\ncities considering", "start": 2213.52, "duration": 3.72}, {"text": "how those cities are going\nto act relative to cities", "start": 2217.24, "duration": 2.76}, {"text": "without targets.", "start": 2220.0, "duration": 1.27}, {"text": "So this paper will get at that.", "start": 2221.27, "duration": 1.97}, {"text": "We'll just talk\nabout more in class.", "start": 2223.24, "duration": 2.04}, {"text": "And this brings me to\nthis optional reading", "start": 2225.28, "duration": 2.73}, {"text": "by Markolf et al., which\nis \"Pledges and Progress.\"", "start": 2228.01, "duration": 3.93}, {"text": "This is a Brookings\nInstitution report.", "start": 2231.94, "duration": 1.98}, {"text": "It looks at the 100 largest\ncities across nine states.", "start": 2233.92, "duration": 3.21}, {"text": "They find that number of\ncities, these 100 cities,", "start": 2237.13, "duration": 3.3}, {"text": "have all set fairly ambitious\ngoals, everything on the blue", "start": 2240.43, "duration": 4.77}, {"text": "here on the right.", "start": 2245.2, "duration": 1.74}, {"text": "The parentheses shows you\nwhen they set the goal.", "start": 2246.94, "duration": 2.64}, {"text": "And you can see\nBoston, where we are--", "start": 2249.58, "duration": 2.85}, {"text": "actually, Cambridge is also\nin the graph somewhere.", "start": 2252.43, "duration": 2.61}, {"text": "But Boston,\nMassachusetts, in 2005--", "start": 2255.04, "duration": 2.19}, {"text": "so they're going to have\nan 80% reduction by 2050,", "start": 2257.23, "duration": 3.18}, {"text": "as all of these cities did,\nalso meeting the White House's", "start": 2260.41, "duration": 6.21}, {"text": "targets in 2016.", "start": 2266.62, "duration": 2.52}, {"text": "It's commensurate with the\nnational targets in 2016.", "start": 2269.14, "duration": 2.31}, {"text": "You can see a number\nof these cities", "start": 2271.45, "duration": 1.5}, {"text": "here in the left have set\nless ambitious targets--", "start": 2272.95, "duration": 2.79}, {"text": "50% reduction, let's\nsay 40% reduction.", "start": 2275.74, "duration": 3.15}, {"text": "But they may have\nmore closer targets.", "start": 2278.89, "duration": 3.31}, {"text": "So this might be an\ninterim goal on the way", "start": 2282.2, "duration": 2.09}, {"text": "to a more ambitious\ntarget down the road.", "start": 2284.29, "duration": 3.42}, {"text": "But the take-home from\nthis Markolf report--", "start": 2287.71, "duration": 2.7}, {"text": "and I'll let you\nlook at your leisure", "start": 2290.41, "duration": 1.602}, {"text": "because I think\nsome of you will be", "start": 2292.012, "duration": 1.458}, {"text": "quite interested in\nparticular cities--", "start": 2293.47, "duration": 2.033}, {"text": "you can see what\nthe difference is", "start": 2295.503, "duration": 1.417}, {"text": "between their current emissions\ninventory and their target", "start": 2296.92, "duration": 2.417}, {"text": "emissions.", "start": 2299.337, "duration": 0.733}, {"text": "And you can see in the\ncase of Chicago, Illinois,", "start": 2300.07, "duration": 3.24}, {"text": "they set a 2015-- they had a\n2015 greenhouse gas inventory.", "start": 2303.31, "duration": 4.8}, {"text": "They had a target emission in\nthe year of that inventory,", "start": 2308.11, "duration": 2.508}, {"text": "and it looks like\nChicago is emitting", "start": 2310.618, "duration": 1.542}, {"text": "about 50% more emissions\nthan they targeted in 2015.", "start": 2312.16, "duration": 4.08}, {"text": "I actually find this\nreport quite hopeful", "start": 2316.24, "duration": 2.1}, {"text": "because it takes a serious look\nat all these cities and says,", "start": 2318.34, "duration": 2.92}, {"text": "well, we should take\ncities seriously", "start": 2321.26, "duration": 2.27}, {"text": "in terms of the climate\naction goals we're studying.", "start": 2323.53, "duration": 2.4}, {"text": "But in order to\ntake them seriously,", "start": 2325.93, "duration": 1.87}, {"text": "we also have to hold them\naccording to the plans", "start": 2327.8, "duration": 2.51}, {"text": "that they're setting.", "start": 2330.31, "duration": 0.97}, {"text": "So it looks like\nBoston is closer", "start": 2331.28, "duration": 2.69}, {"text": "to its target of 10%\nhigher inventory emissions", "start": 2333.97, "duration": 3.63}, {"text": "than it had planned for in 2016.", "start": 2337.6, "duration": 3.21}, {"text": "That 10% hopefully gives us--\nor that inventory difference", "start": 2340.81, "duration": 4.08}, {"text": "gives us a good place\nto target our actions.", "start": 2344.89, "duration": 2.37}, {"text": "Other places, let's\nsay, Los Angeles--", "start": 2347.26, "duration": 1.86}, {"text": "looks like it's actually\nahead of its goals.", "start": 2349.12, "duration": 1.833}, {"text": "It's actually 10% less in terms\nof greenhouse gas emissions", "start": 2350.953, "duration": 3.237}, {"text": "than they planned for in 2013.", "start": 2354.19, "duration": 1.92}, {"text": "So cities-- looks like almost\noverwhelmingly temperate cities", "start": 2356.11, "duration": 3.72}, {"text": "except for Minneapolis,\nbut all of these fairly", "start": 2359.83, "duration": 2.97}, {"text": "temperate-region\ncities are doing", "start": 2362.8, "duration": 1.62}, {"text": "better than they expected.", "start": 2364.42, "duration": 1.41}, {"text": "Some of these cities here--", "start": 2365.83, "duration": 1.98}, {"text": "I guess Chicago is\na cold climate city,", "start": 2367.81, "duration": 2.46}, {"text": "and Tucson is the opposite.", "start": 2370.27, "duration": 1.59}, {"text": "But for different reasons,\nTucson and Chicago", "start": 2371.86, "duration": 2.7}, {"text": "are wildly over the goals\nthey set in 2014 and 2015.", "start": 2374.56, "duration": 5.22}, {"text": "And so I'll just stop here,\nand I will talk more in class", "start": 2379.78, "duration": 3.75}, {"text": "this week.", "start": 2383.53, "duration": 0.75}, {"text": "We'll talk the results\nof our carbon calculators", "start": 2384.28, "duration": 2.22}, {"text": "that you did for homework.", "start": 2386.5, "duration": 1.89}, {"text": "We will put some questions\nfor discussion on the board,", "start": 2388.39, "duration": 2.49}, {"text": "and we'll just start\nour discussion.", "start": 2390.88, "duration": 1.89}, {"text": "And we'll have some news\nitems to talk about in class.", "start": 2392.77, "duration": 2.92}, {"text": "Thank you very much.", "start": 2395.69, "duration": 1.05}, {"text": "I hope you guys have a\ngreat rest of your weekend--", "start": 2396.74, "duration": 3.77}]