| [{"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}] |