Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
what happens to bullets which don't immediately hit something?	[ "across a straight plane - the bullet will lose momentum and gravity takes over and it eventually falls to the ground" ]	[ "Fast internet and faster servers. Human reaction times are on the order of 100ms or so. Ping time, which is round-trip packet flight time is often on the order of half that or so. Round trip is therefore on the order of human reaction if you give the server a little time to do stuff. Also, the server only sends b...
Why men get sleepy after orgasm?	[ "This is a weird thing to explain to a five year old." ]	[ "Well, usually we like to touch the people we value the most. So, laying next to each other is good. Plus it's warmer when it's cold. And it promotes Bonking. Which is good." ]
How much money did various medieval nobles make?	[ "Data from Spain, extracted from Fernández de Oviedo, Batallas y Quinquágenas: Alonso de Cárdenas, master of the Order of Santiago. 80,000 ducats per year. 15,000 vassals. Duke of Infantado. 60,000 ducats per year. 30,000 vassals. Duke of Medinaceli. 35,000-40,000 ducats per year. More than 8,000 vassals. Duk...	[ "If it's okay, I'd like to ask an add-on question: could anyone, theoretically, do the exam, or was it restricted to the middle classes? I mean, clearly a peasant would probably fail because of their poor education, but were they allowed to try?" ]
This may be a dumb question but how does a car/truck tire handle the weight from the vehicle and not pop?	[ "They're simply really big. The larger the area you have touching the ground, the more weight you can have. Let's say you put three tons balancing on a needle. You're taking all those three tons, and concentrating them on one single spot, and that needle is gonna pierce right down through the asphalt. However, say ...	[ "I am sure there will be physics papers published on this during the next months just like with the glowing sticky tape. One theory is briefly explained in the original video. As the rubber is stretched the molecules have to align in certain ways. This constricts them which increases the internal pressure of the ru...
What is it about the element Lead (Pb) that makes it so central to nuclear physics?	[ "> Ie that elements below it produce energy when fused and above it when fissioned? Actually, this is a property of nickel (Ni-62, Fe-58, and Fe-56 have the most binding energy per nucleon). The first stars in the universe only produced elements up to iron, since fusing past this does not yield energy. If you look ...	[ "Basically the same way a paramedic/nurse can work out your pulse in beats per minute without counting your heartbeat for a whole minute. Half life is an example of exponential decay, and so it follows a very regular, predictable mathematical pattern. If we have data about how it has decayed over time now, then we...
If the air pressure within a vessel increases will its buoyancy also increase?	[ "No. It will actually decrease, because the volume of water displaced, which is what gives the upward force, stays the same, but the mass of thing giving it downward force is greater if the way you increased the pressure was to add more gas to the volume." ]	[ "This is pretty much how we preserve food (think about packaged cakes which last for months on the shelf). The bread would dry out very quickly in vacuo as the water would evaporate and be pumped out by the vacuum pump. This is why twinkles and the like are packaged with argon or nitrogen gas. The proteins in the b...
Why do chords sound bad when played really low on a piano?	[ "Even if your piano is tuned, it can sound slightly off that far down the keyboard simply because of the way it's tuned. There are mathematical inaccuracies in tuning a piano that they account for by basically rounding. They perfectly tune middle C, and then essentially round up on the higher notes and down on the ...	[ "The structure of an LCD panel [isn't completely flat](_URL_0_). This isn't an accurate analogy in terms of structure, it's just the principle. If you imagine an LCD super zoomed in, think of it as looking down at a cityscape, all skyscrapers and such. If you look down at it directly from above, you can see the st...
Why does my cigarette lighter barley light when it's cold, but lights a huge flame when it's warm?	[ "Your cigarette lighter is burning liquid fuel that must be vaporized before it can mix with air and burn. That liquid fuel vaporizes more easily at high temperatures than at low temperatures. This is why it's harder to start a car engine when it's cold, and why engine block heaters solve the problem." ]	[ "I imagine you are talking about the internal combustion engine (ICE)that is commonly used around the world in automobiles. Think of the classic \"fire triangle\" when thinking of these engines. You need 3 things to make something burn: Fuel, Oxidizer, and heat. In an ICE these components are a Petroleum product s...
Does the big planets from our solar system have a solid surface like earth?	[ "Yes, current observations indicate that all of the gas giants have a rocky core. For instance, Jupiter, the largest planet, most likely has a rocky core, under a massive sea of liquid metallic hydrogen. It's predicted to be on the order of 60,000 °F (30,000 °C), but uncertainties in temperature, pressure, and exac...	[ "It boils down to they have water (in a nice liquid ocean). This implies that there is a heat source that's been going for a while (tidal heating) so life could live there if it wanted to." ]
why helicopters make a chop chop noise instead of a consistent buzz.	[ "[It's been explained before hope it helps. ](_URL_0_)" ]	[ "Imagine you wanted to send a digital file to a friend of yours, but all you have is a telephone and the binary data contents of the file. You tell your friend \"when I say beep you write down 1, when I say boop, you write down 0\", and then you read the contents of the file to him over the phone \"beep beep boop ...
Is it possible (however uncommon) for an isotope of the heavier elements to contain zero neutrons?	[ "No. Even two protons (called Helium-2 or Diproton) is too unstable to exist (for long enough to be detected, anyway). Adding more would just make it even less stable." ]	[ "People have been being knighted without actually qualifying since the late Middle Ages. The rank was associated with status, thus those who did not deserve it still desired it and were able to gain it through noble patronage. Two examples stick in my mind: -The knighting of the royal princes Louis and Charles of A...
the differences between existentialism and nihilism	[ "Existentialism in a nutshell: \"There is no intrinsic meaning to life, each human must find their own truths to live for and make life worthwhile.\" Nihilism in a nutshell: \"There is no intrinsic meaning to life and there's no reason to even search for purpose, because no such thing exists. Nothing has a poin...	[ "Here's a pretty good explainer. _URL_0_ Basically it comes down to different memory, different promises (reliability and service life), and different marketing." ]
Why we differentiate between married and unmarried women in a title (Mrs/Ms) and why don't we do the same for men?	[ "The title of ['Master'](_URL_0_) is fairly close to what you're looking for. It is abbreviated as 'Mstr'. It's fairly archaic, but was at one point the correct way to address a young man. It isn't directly tied to marital status, but is still similar to 'Miss'." ]	[ "From [wikipedia](_URL_0_): > A custom still sometimes practised is to leave the bottom button undone. This is said to have been started by King Edward VII (then the Prince of Wales), whose expanding waistline required it. Variations on this include that he forgot to fasten the lower button when dressing and this ...
Is there any evolutionary benefit or reasoning behind poor vision in humans?	[ "Most of what I am reading here is completely wrong. The real answer is: Bad vision (nearsightedness, specifically) in modern humans is a side effect of the modern environment. It was selected against strongly in humans, which is why (until the last few generations) nearly all humans who weren't suffering from some...	[ "It's like a vestigial thing leftover from back when we did need them. Basically, it doesn't hurt our odds for survival, so it just sticks around." ]
If Potassium Iodide (KI) protects us from radiation, why we are not given KI before CT scans ?	[ "A few reasons. First of all, KI really only protects your thyroid gland. Your thyroid gland produces hormones that include iodine, so if you ate radioactive iodine, then eating more iodine (KI) helps reduce the amount of radioactive iodine that gets used in those hormones. The less used in the thyroid hormones, th...	[ "The main reason is the waste problem, and more specifically, the way it is handled. The current storage facilities were classed as safe and durable by the environmental ministry (then led by Angela Merkel), and now have been found unsuitable (guess what, metal containers in a salt mine rust quickly), which gives p...
Why Are Nvidia's GPU chips ideal for Deep Learning while CPUs like Intel's are not?	[ "The biggest difference between CPU and a GPU is that CPU is designed for general purpose computing, meaning it's supposed to be able to handle large amount of different tasks and change between them quickly. A GPU is more like a Chinese sweat shop, where you have tons of cores doing the exact same thing over and o...	[ "The cells that make up your body divide and multiply as a normal part of your life. When you have cancer, though, it causes your cells to go crazy and multiply out of control. Chemotherapy, the special name for the medicines that are used to fight cancer, works by killing cells that multiply quickly. For the mos...
How Are Jeans Distressed During Manufacturing?	[ "The big one is that they was the jeans in an industrial washing machine with a bunch of cinder blocks. This beats the shit out of the jeans making them appear distressed, worn, and softer. They also can use UV torches that fade the dye, sandpaper, etc." ]	[ "[Striped shirts](_URL_0_) tend to cause problems with video recording and, if the pattern is fine enough, photos. It is due to the creation of a [moire](_URL_1_) pattern where 2 sets of parallel lines that are not quite parallel (the lines on the shirt and the pixels on the sensor) create a illusion of density wav...
Why is the median household income gone relatively unchanged for the bottom 90% of Americans since the 70's?	[ "Fundamentally, like any market, the labor market is driven by supply and demand. If a company needs more workers than it can find who will agree to work at a particular wage, they'll have to raise the wage they're willing to pay until they can find enough workers. However, over the last several decades, two major ...	[ "Hi there -- while we've approved this question, we would like to remind potential respondents of our [current events](_URL_0_) (AKA \"20-year\") rule -- it's fine to discuss events through 1997 (inclusive) and their effects, but not events after 1997. Thanks!" ]
Humans become older because chromosomes become shorter so how humans are able to have offspring which chromosomes are not shortened? Where does this offspring get his non shortened chromosomes?	[ "First, your assertion that, \"Humans become older because chromosomes become shorter\" is not correct. It is true that telomere (i.e. the \"end caps\" of chromosomes) shortening is associated with aging, mortality and aging-related diseases. However, it is not known whether short telomeres are just a sign of cellu...	[ "Physically developing we are close to a bobcat or other animals in terms of lifespan. We have a much, much more complex world than any other animal does though. We have to eat that play-doh and stick that key in the electric socket to learn that we want to be a philosophy major or an architect. Bobcats can't build...
if I hit my shin or have another minor pain, why is rubbing it instinctively what happens. Why does that make it feel better?	[ "Rubbing the area simulates blood flow; which promotes healing. Rubbing also provides variations in the sensation; which gives the brain more to focus on than the initial trauma. It can also dislodge small irritants that may have attached to the area." ]	[ "Our brains didn't evolve with cars in mind. They evolved with, like, being hunted by a jaguar (or whatever) in mind. So your brain doesn't know what to do with a car. It thinks hey, we're sitting, our body's not really doing anything physical, there's very little activity or stimulus... this seems like a good time...
With our galaxy being pulled toward the Great Attractor, how does the expansion of the universe affect our speed toward it?	[ "My understanding is that we are moving towards the Great Attractor, as in overcoming expansion by that amount. Otherwise they would say we were be receding from the Great Attractor. Using the other posters math, that is instead how much expansion is slowing down our approach." ]	[ "Historically, gravity was thought of as a force between massive objects. Einstein's theory of general relativity trumped that with the idea that gravity is actually caused by the interaction between space and something called the \"stress-energy tensor\", which basically measures the density of energy (of which ma...
A few questions regarding the asteroid orbiting Earth NASA just announced..?	[ "So it doesn't seem like it could collide with the moon, the article there states that our gravity keeps it within 38-100 times the distance of our moon at all times, so its far to distent to do that. it isn't big enough to effect our tides in any way it is also fairly small, so with the naked eye id doubt, but wi...	[ "A long time ago in places like Greece, Rome and even before that in really, really long ago places like Sumeria, and Egypt people made up stories about the stars/planets and the pictures they thought groups of stars made. These stories were usually about beings they considered to be gods or demigods (the word demi...
How did cavemen "brush their teeth" and why didnt their teeth rot and fall out?	[ "From what I've read they ate a lot more rough course foods. Chewing things that are hard scrape our teeth for us kind of like it does for other animals. The problem for our modern teeth is we eat a lot of soft refined foods and a lot of sugar. That stuff just sits there and gets stuck which causes tooth decay." ]	[ "It depends on how much money they had. In a one way migration from town to town, If they were poor or even middle class they had it on them in a physical way, either in cash, coinage, or mostly they bought supplies with it (wagon, oxen, rifles, etc) before they left. Later migrations they might have a check or a b...
Why are anti-inflammatory drugs like ibuprofen a good idea when my body's natural response is to swell?	[ "Ok here it goes.... it takes blood flow and cells to regenerate and heal. When we are injured more blood is redirected to the area that swells. Swelling is fine and is a natural response to an injury but in some cases your body's healthy response can be unhealthy (like say if your throat was injured and swells... ...	[ "Inflation means that the longer you hold onto your money the less it's worth. This isn't always a bad thing, it encourages you to buy and sell things and otherwise contribute to the economy, it discourages people from 'hoarding their gold'. However if the USA dollar inflates faster than the global economy, busines...
What legal authority does President Obama and the US Military have to carry out military operations in Syria without an authorization for the use of military force from Congress?	[ "Under the War Powers Resolution of 1973 the President must explain to Congress a military action within 48 hours. Congress then has 60 days to either declare war, pass a resolution allowing continued military action, or demand withdrawal. At the end of that 60 day period, the President has 30 days to withdraw forc...	[ "Essentially the events in Crimea threaten to destabilize the European continent. To give you some scale Crimea is about roughly the same size as Belgium. The real scale of territory that Russia seized really did not hit me until I really compared them on a map. Anyway, since the Second World War there has not been...
Would a water pump work better with rigid lines, or soft lines?	[ "Plumber for ten years now. Go with pex you will not regret it. In fact just forget that pvc(and cpvc) water lines exist(as a new or replacement option) and you will be better for it. Pex is slightly more flexible than pvc and not brittle like pvc. It is far stiffer than clear vinyl hose and will last far longer. S...	[ "I live in coastal New England. One thing to note is our winters are extremely unpredictable. Last year we had like 20 feet of snow, this year we haven't had any (and am only getting a few inches from this storm). How do you budget in something that can cost anywhere from five million to nothing. Another thing to ...
Why do we get old? What's getting worse in quality of a single cell that is considered old?	[ "All the time our cells get damaged and dies. New cells are created in order to replace them. Every time cells copy and duplicate themselves they have to copy and duplicate the DNA, too. The DNA is ordered in sequences called chromosomes. When a chromosome is duplicated, a short sequence of the DNA at its end gets ...	[ "We are not seeing it in real time. If you're looking into a mirror the light has to bounce off of you, into the mirror, back to you eyes and then your brain has to interpret the signals. You are not seeing in real time, you are seeing into the past (sorta), similar to when you look at a star and you see it as it w...
How do Geiger Counters work?	[ "When radioactive stuff breaks down, it gives off energy and particles, like gamma rays and alpha / beta particles. These rays and particles can pass through a lot of materials, kinda like light through a piece of paper. Some makes it through, some keeps going. In the Geiger counter there is a tube of gas, like ne...	[ "One hot topic recently has been the detection of gravitational waves. Just as there is a spectrum for electromagnetic waves, there's also a [gravitational wave spectrum](_URL_2_). One point has been discovered so far, by LIGO, the Laser Interferometer Gravitational-Wave Observatory. It's essentially a telescope th...
A larger person will be made up of more cells than a smaller person. Does this mean that they have a higher chance of developing tumours?	[ "Height has been correlated with higher incidence of cancer, see e.g. [this open-access review]( _URL_0_). The authors do suggest the higher number of cells as a possible rationale, but there are a lot of other possible explanations e.g. chemical signals which cause greater body growth may also cause greater growth...	[ "They'd both experience the call as taking the same amount of their time. (So if they both texted each other the number of seconds they thought elapsed during the conversation when they were done, they'd both send the same number to the other person.) But, for both of them, that amount of time would be longer tha...
How the heck did the Persians screw up invading a tiny Western Peninsula (known as Greece)?	[ "I've written some replies on this topic before: * [Preceding the Persian invasion of Greece, what factors prepared them to stave off such an overwhelming threat?](_URL_1_) * [Why wasn't Xerxes more prepared to face the Greeks?](_URL_0_) And in reply to your specific question: * [Why was the invasion of Greece by X...	[ "Enron basically used non-GAAP (generally accepted accounting principles) accounting methods to cover up their massive overleveraged position, (i.e., they had way more debt than equity). By keeping this debt off their books, they could overstate earnings. However, when people, including the SEC (Securities Exchange...
how do archaeologists decipher unspoken, dead languages?	[ "First of all, keep in mind that all studies of ancient languages are theories, or loose estimations. No one can REALLY know for sure. That being said, things such as imagery and even living conditions help. For example, say a throne is found in a temple, with a large hieroglyph carved on the back. Clearly, this sy...	[ "It's [subvocalization](_URL_1_). Apparently rather than engaging their vocal chords, [some deaf people engage their forearms](_URL_0_), so that's a different kind of inner monologue." ]
Why are people on death row kept alive for so long?	[ "In case we find out we were wrong." ]	[ "Every time you make a copy of a cell, there is a chance for errors. For example when you photocopy a first print, it is pretty crisp and close to the original, but there are a few minor discrepencies. Now if you photocopy the copy, it gets more distorted, and so on until some letters get hard to read, it gets diff...
Did Russia have a difficult time recovering from burning all of their land during Napoleon's invasion?	[ "I dont really know all that much about the question in itself, but remember that the capital at the time was NOT moscow. It was St. Petersburg. Also I would assume that there was still enough non-burned rural land in western Russia, afterall the Grande Army could not have covered everything, so there probably was ...	[ "Short answer, volcanoes. Even though everything on the surface of the earth was frozen, the mantel was just as hot if not hotter than today, and plate tectonics still took place. All these volcanoes still dumped massive amounts of CO2 in the atmosphere. A green house effect ensued and warmed everything back up. Ov...
Why do some people say FDR's New Deal didn't help end the Depression, rather that WW2 actually did it?	[ "It's not completely wrong but it's not right either. Under FDR the American government took on a lot of reforms that would help the American people. While it's true that the amount of government spending and new employment supporting the American war machine was extremely helpful for the economy these reforms also...	[ "The biggest determining factor was which service you were affiliated with. Marines were sent almost exclusively to the Pacific theater, due to their focus on amphibious warfare and the island-hopping nature of that fight. Since both major theaters involved a significant ocean voyage, the navy was involved in both ...
After learning a new language as an adult after a base language is known, what goes on in your brain as you speak the 2nd language? Does your brain translate the thoughts to the 1st language then to the 2nd language? How does this compare to learning 2 languages from birth?	[ "I can't speak from a neuroscience perspective, but I have learned a second language as an adult. Initially I translated thoughts in my head as I was speaking, but the more fluent I became the less I had to think in my native language. Over time concepts become directly linked to the foreign words in your head, and...	[ "Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Does all the dust and dirt we breathe in during our lives just build up in our lungs? ](_URL_1_) ^(_48 comments_) 1. [ELI5 : What happens to objects that you breathe into your lungs? ](_URL_0_) ^(_13 comments_) 1. [ELI5: How does the l...
Standing up to fast?	[ "It's called [orthostatic hypotension](_URL_0_), which is just medical Greek for straightening-up low-[blood]-pressure. Some people, when standing up quickly, sometimes get dizzy. It's caused by temporary low blood pressure. It typically passes after a few seconds. It doesn't happen to everyone- apparently, it's ne...	[ "This is called as some white cloak disorder or something similar. Had read it on the net. This happens to me every time my doc measures my BP. The only remedy to this is to tell your doc that this happens before he measures your BP and while noting it down, the doc might normalise it." ]
What is stopping 911 dispatch centers from adopting texting capabilities?	[ "Phone calls are live data stream. Its transferred in real time. Text messages are not. They're queued and sent whenever the network wants.. When the network is busy, like after a disaster, text msgs are delayed minutes or hours later" ]	[ "Paramedics rarely if ever carry blood on an ambulance. We use normal saline solutions or Ringers Lactate for volume replacement. Hospitals can do blood typing in a matter of minutes so it's not a huge inconvenience if they don't know immediately." ]
Why does Apple allow competitor apps (like Google Maps) to be available on iTunes?	[ "Because if the best Apps are blocked, there's less reason for someone to buy the phone." ]	[ "Taxis have been under an immense amount of regulation. There were restrictions on how much they could charge, restrictions on how many taxis are allowed, and so on. Taxi medallions in New York (essentially a piece of paper giving you the right to operate a taxi) were going for over a million dollars. Uber and Lyft...
How does one actually make a musical composition?	[ "Composer here. It's similar to writing a book or making a painting. You find a reason to write and a message to convey, then use your knowledge of music, theory, and instrumentation to tell your story. To create melody, some composers may improvise on an instrument until they hear something they like. I personal...	[ "In the past, the hardest thing about writing a new program wasn't the programming language. It was understanding how your programming tools worked. To use C as an example, in order to write your first program, you would need to: 1. Understand how your text editor worked, a non-trivial task on a text only, mouseles...
Why are the larger berries/grapes always sweet, while the smaller ones are always sour?	[ "It's probably due to how ripe the fruit is. The longer a fruit stays attached the plant, the larger it will get. As it gets older/riper, the fruit changes its sugar/acid composition, to more sugar less acid, making it sweeter. The small less ripe ones have less sugar and more acid, making them sour." ]	[ "Your brain has a gating mechanism. Basically if you feel the same sensation for an extended time, your brain decides that feeling isn't important anymore and ignores it. This includes all sorts of things, like the feeling of your teeth on your tongue, your lips touching, the clothes on your skin, your phone in you...
Did Nazi Germany have anti-association laws?	[ "I'm not crazy about looking to Nazi law as a source of how the government worked. Insofar as there were such laws under the Third Reich, they were generally subordinated to the Führerprinzip, meaning that absolute subordination to the will of one's superiors was what was generally valued, rather than legalistic o...	[ "This article looks pretty relevant, Neural Correlates of Reexperiencing, Avoidance, and Dissociation in PTSD: [\\[PDF link warning\\]](_URL_0_). Quote from article: > As predicted, state reexperiencing severity was associated positively with right anterior insula activity and negatively with right rostral anterior...
Why didn't samurai or lower japanese warriors use shields?	[ "Samurai were primarily mounted archers. Firing a bow and controlling a horse at the same time didn't lend itself to using a shield, you didn't have a free hand for it. Foot soldiers initially used spears, eventually supplemented by matchlock muskets. While it is possible to use a short spear with a shield, the Jap...	[ "Back then people still needed jobs, now they dont and can practice harder for longer. And science helps by showing then methods on improving motions. You cam find cool videos on youtube" ]
What is the Deep Web?	[ "internet locations that aren't accessed or indexed by search engines like google. it's like an elite nightclub: you only can find it if you already know where to go, you won't ever \"stumble\" upon it." ]	[ "The Tor Project is Awesome. If you can afford a VPN-That's better!" ]
Due to rapid expansion of the universe, will this result in our Milky Way being isolated from other galaxies to the point where we see nothing but darkness when we try to observe space?	[ "Yes! This is actually covered in Lawrence M. Krauss' [A Universe From Nothing](_URL_0_) (which is absolutely worth reading, and it's only 120 pages!). Essentially, yes, 1.5 to 2 trillion years from now, the universe will have expanded so much that there will be no method of observation into the cosmos. Even fo...	[ "Both light and gravity waves want to travel at \"instantaneous\" speed. The problem is that the maximum speed allowed in the fabric is the [speed of causality](_URL_0_). Causality is the relation of a cause and effect. And the speed of casuality is the maximum speed the effect can travel away from the source. So i...
Why does it feel good when pressure is applied (like in massages) on a paining area of your body? Shouldn't it cause the pain to increase rather than subside?	[ "\"Pain Gate Theory\", is the one I learnt is the most likely. Extra stimulation covers up pain signals." ]	[ "The rate at which a human brain processes information is not constant. It changes based on a number of factors. When you feel a sudden threat, your body releases hormones that trigger a change in the rate at which your brain can process information. If your brain is processing information more quickly, your percep...
Since you can't create energy out of nothing do wind turbines take energy out of the wind, if eventually we build enough of them will wind cease to exist?	[ "No, because the conservation of energy argument only applies to closed systems (ie, systems for which there is no net energy input or output. However this is not the case for earth, since the sun is constantly putting energy into the earth. Indeed the origin of wind is due to the atmospheric pressure differentials...	[ "Fans have a rotational symmetry, but have no symmetry in the direction of airflow. They propel air one direction only, toward the direction that the leading edge of fan blades point toward. Of course, you can reverse the airflow by simply reversing the fan rotation. However, many fans aren't symmetrical in this se...
Why are sinkholes always round?	[ "Round is pretty much the default shape for things. It's what you get when nature has no reason to prefer one direction over another." ]	[ "What you're looking for is the shape known as the [geoid](_URL_0_), the shape the earth's oceans would take under the influence of gravity and rotation alone. Recent advances in satellite geodesy, or the measurement of Earth's fundamental properties, allow us to model the geoid to remarkably high precision; th...
What did the Germans think when they first saw a tank in WW1?	[ "* [WWI Anti-Tank Weapons and Methods] (_URL_1_) * [How did the Germans react to the first use of Tanks?] (_URL_0_) These answers I've given should answer your question. In short, while the Tank did cause some panic early on, countermeasures were quickly taken, and it's mechanical unreliability was also noted. It a...	[ "Not to discourage any further answers, but you find these older answers to be informative: [What would \"boot camp\" and PT have been like for Roman soldiers around the time of the Punic Wars?](_URL_0_) by /u/Celebreth [I have just joined the Roman army, what is my life going to be like now](_URL_1_)? [People from...
Can you get someone sick before symptoms even appear?	[ "Common cold symptoms may appear as early as 16 hours after exposure. That gives a person around a day to transmit a cold to another person before symptoms appear. the person won't be able to do this via cough or sneeze since those are symptoms, but hand-to-hand transmissions can spread the virus as well." ]	[ "The movie was [Days of Thunder](_URL_0_) and he was talking about [Slipstreaming or Drafting](_URL_1_). As to your question, this depends on * The velocity of the cars * Geometry of both cars * Atmosphere status (temperature, rain, snow ... although they have very little effect at higher speeds) On the street it's...
Why do Boxers/Fighters wake up so early, only to go to bed early ? Wouldn't it be the same if the woke up later and went to sleep later ?	[ "Aside from I think it being personal preference, there's something to be said about developing discipline that a fighter needs. They need to eat healthy, train consistently, and be willing to sacrifice time that would be spent drinking/partying on focusing on helping their bodies. Going to bed early means reducing...	[ "I watched the protests and movements in Hong Kong religiously for about a month. Of course there were many highs and lows of population in the streets throughout, but the streets tended to fill up after work and school hours and would die back down around 2 or 3 am. Those that were skipping school or work to prote...
Is it valid to say that 9 repeating is the same as -1?	[ "There is a sense in which this is true, for the same reason that 1 + 2 + 4 + 8 +... = -1. Specifically, we can write your number as 9 + 9\\10 + 9\\10^2 + 9\\10^3 + ..., or 9\\Σ10^(n) where n runs from 0 to infinity. The analytic continuation of the series Σx^(n) is 1/(1 - x) for x ≠ 1, so we can say that your ...	[ "Put five apples onto a table. Now take no apples away. Now take no apples away again. Keep taking no apples away, and when you've finished, tell me how many times you were able to take no apples away from the five apples on the table." ]
Earth's escape velocity is 11.2 km/s, but would anything happen if a land vehicle were to move that fast across Earth's surface?	[ "It would burn up like a meteor. The density of the atmosphere is too high at the surface. If we neglect that effect, and also neglect drag, friction, etc. then yes, it would escape the Earth. The funny thing about escape velocity is that direction doesn't matter as long as there is no impact against the surface ...	[ "The problem of carrying sufficient fuel cannot be overstated. Since the amount of propellant you need rises exponentially with the mass of the spacecraft, you very quickly approach a limit where it just isn't possible to realistically get the mass out of Earth orbit. Another (often forgotten) issue is where do you...
Before Columbus, did "new world" peoples have any written/oral history which referenced the "old world"?	[ "Probably related - are there any oral traditions among indigenous peoples referring to the Viking settlement either in the New World or Greenland?" ]	[ "depends on your measuring stick. people did what was best for them given the amount of natural resources, environment, etc around them. for example, maybe europeans had guns, but tomatoes originated in central america. where would you be without tomatoes? guns have little to no effect on your life, but i bet youv...
How refrigerators work?	[ "In the refrigeration cycle, there are five basic components: fluid refrigerant; a compressor, which controls the flow of refrigerant; the condenser coils (on the outside of the fridge); the evaporator coils (on the inside of the fridge); and something called an expansion device. Here’s how they interact to cool yo...	[ "[This is someone's doctoral thesis which contains information on the vibration of flat plates. On page 38 of the PDF (31 of the document), you will see some vibrational modes drawn for a flat plate. The higher-frequency AA mode ought to look familiar.](_URL_0_) While this is water and not a flat plate, the behavio...
Why can't we fry stuff in substances like water, as opposed to frying them in oil?	[ "Not a very scientific answer, but \"frying\" in oil is the same as \"boiling\" in water. Water doesn't boil at near hot enough temperature as oil boils, which causes that nice crunchy texture to food. Frying and boiling mean the same thing in cooking, essentially." ]	[ "You can figure out what components are in the food through a series of chemical tests. So if you want to know how much fat is in the food, you could extract out the fat using an organic solvent, filter out the non-dissolved parts, and weigh how much each part weighs. Or if you want to know how much salt is in the ...
how does an egg contain enough energy to make a chicken?	[ "Almost enough, but not quite. The egg lets in air, so the developing chick can breathe. And the hen (or incubator) provides thermal energy, keeping the developing chick warm. Other than that, yes. Eggs are nutritious! Also, I have to point out that until hatching, the chick just kinda sits around growing. Which d...	[ "Emergence. _URL_0_ Radiolab did an excellent episode/podcast on it. But in essence, we don't really know. How does the brain work when it is 'just' a collection of cells?" ]
How limiting is developing software on older systems like Mac OS System 7 or Windows 95 compared to newer systems?	[ "Do you mean besides there being almost no user base for an operating system that old? Or that it is no longer maintained by the developer of that OS, so no bug patches, security or driver updates? Or that the hardware it runs on is also likely to be ancient? Or that you won't have access to the latest API?" ]	[ "Imagine you are a travelling salesman, and you spend most of your time driving from place to place across the country. Today you need to get from Denver to Dallas. You could use High Level Navigation. You know how to get from Denver to Wichita, Wichita to Oklahoma City, and Oklahoma City to Dallas. String those to...
When did humans begin adding a second storey on buildings?	[ "Follow up question: Was it because it became more efficient to add stability and move up (rather than buy(?) more land sideways), or for some other reason?" ]	[ "Just as a follow-up question - with this sort of topic, is it possible to give a really solid answer if there is no source that says \"there is no evidence of this?\" This isn't my field at all, so I'm really curious about how this sort of question is answered. Is a better response one that examines where such a s...
Why does drinking water (depraving yourself of oxygen) help you when you're out of breath?	[ "Being out of breath and being deprived of O2 are different. Your blood hold O2 quite well, well enough that one breath can sustain you for minutes. It isn't so good at holding CO2 (produced by metabolic processes in the body like making muscles move). The CO2 essentially must be dissolved in the liquid of the bloo...	[ "very simple, Air is a horrible transfer medium for energy, Water is a good tranfter medium for energy. It takes longer for the energy in the air to flow to the ice cube then the energy in the water to flow in the ice cube, When when there is steam in the air, its still maybe 50% humidity compared to 100% humidity...
Why does the body need blood?	[ "Your cells require oxygen and other nutrients, and blood is the \"conveyor belt\" that takes those things to the cells. Your blood is the freeway of your body, where delivery men dive around delivering fuel and tools." ]	[ "it scares off most things that would bite us and it attracts other humans' attention, which before our culture shifted away from common interest in helping each other meant help would come quickly." ]
Why do bridges from the 17 & 1800s seem to last longer than our bridges today?	[ "Over engineering. For the most part modern bridges are built to last indefinitely with maybe a bit of regular maintenance and inspection, but things dont always go exactly as planned. But with modern science we can analyze every force that will act on a bridge down to every last nut and bolt. We can predict where ...	[ "A quick [PubMed](_URL_0_) search for these drugs brings up a vast amount of peer-reviewed papers, some of which are free even if you are not at a University with access. The short answer is that even though these early compounds were effective, the side effects were astronomical. We've moved towards more specific...
Why does Russia want Crimea?	[ "It hosts the naval base that hosts their black sea/Mediterranean fleet which is pretty strategically important. That would be the biggest reason by far." ]	[ "This CGP Grey video does a really good job of explaining it all. _URL_3_" ]
If photosynthesis creates 6O2., and cellular respiration uses 6O2, then how is any oxygen being released for us to use.	[ "Not all of the glucose produced in photosynthesis is used for respiration. Some is used to make cellulose, some to make starch. There's a lot of oxygen left over then." ]	[ "Rockets are complicated. Saturn V is a three-stage rocket with 7.8 Mlbs, 1.2 Mlbs, and 0.2 Mlbs thrust. All three stages are used to insert into earth orbit with a significant amount of fuel left over for injecting into a trans-lunar orbit. The SpaceX mars spacecraft is a two stage rocket with 29 to 31 Mlbs for th...
How did the Turkish people start off?	[ "The Turkic nation-states that exist today are Turkey, Azerbaijan, Turkmenistan, Uzbekistan, Kyrgyzstan and Kazakhstan. There are also the Crimean Tatars, Tatars in other parts of what is now Russia and eastern Europe, the Bashkirs in Bashkortostan (Russia), the Uighurs in Xinjiang (China), and some other smaller T...	[ "on Antarctica, here are some previous posts to check out for previous responses: [Do we know or do we have any evidence of any Peoples or societies that existed on the Antarctic landmass before it got covered in ice?](_URL_1_) [Is it possible that the native inhabitants on the Tierra del Fuego peninsula explored o...
Why are neutrinos considered leptons and not in their own group?	[ "Leptons are fundamental particles with a non-zero lepton number. Lepton number is a conserved quantity in a reaction. If neutrinos aren't considered leptons, then we wouldn't have conservation of lepton number, which helps determine which reactions are allowed or forbidden." ]	[ "The common methods? Nuclear pants are the common method. Neutron research facilities tend to be built at them. Another way is use a particle accelerator to create unstable nuclei that decay by neutron emission. The [Spallation Neutron Source](_URL_0_) collides protons into mercury to produce neutrons." ]
If two organisms of different species produce a fertile hybrid, are those two species now technically the same species?	[ "That is only one definition of a species, and, by itself, it's not a good one. Plants of different species form hybrids rather readily, and the concept completely falls over when you look at asexual species. Ultimately the definition of what constitutes a species is fuzzy at best, and an absolute mess at worst. I ...	[ "Are you referring to American slavery? That is normally what folks on here are referring to. Be a little more specific please; if this is about America, I can tell you that the answer is \"no\" but only because Americans certainly knew that African slaves were \"human,\" or at the very least the law recognized the...
How can babies breathe in water during pregnancy, but we can't breathe underwater once we are born and out of the womb?	[ "Babies don't breathe at all during pregnancy. Instead, they get oxygen directly from the mother's blood via the placenta, and expel carbon dioxide the same way. In essence, they breathe using their mother's lungs. However, in the womb, babies will make breathing motions, pulling amniotic fluid into their lungs, wh...	[ "The same reason you can walk through an airplane isle even though you are unable to move at hundreds of miles an hour (or fly). The same reason you are able to survive walking around outside even though the earth is spinning around at thousands of miles per hour. Ir more precisely, why you can swim in a pool even...
Evolutionarily speaking, why are humans so much more vulnerable to bad hygiene than other species?	[ "Humans also have larger lifespans than most mammals, which means they live to experience the detrimental effects of bad hygiene. E.g., your general dog that lives 12 to 15 years will never experience their teeth falling out from neglect compared to a human who's average lifespan runs to about 80 years. Other anima...	[ "Hi OP, this is a cultural question, so it would greatly assist anyone considering answering if you could specify which culture you're asking about. For example, the name of a cultural group / country / geographic region, plus a rough time period. Otherwise, this question is simply too broad, as it encompasses almo...
Why haven't companies like Western Union, and other firms that serve the same purpose, die due to PayPal and Venmo?	[ "A large number of people use only cash, so an online service that draws from a bank account they don't have would be useless." ]	[ "A number of reasons. Looking true to life is not the best test of an artist. If you want something photorealistic you just get a photo. More to the point the point of art is not that it's technically difficult but that it produces something we find pleasing. Good art, like good music, doesn't have to be hard work....
The difference between European-style football and South American-style football, and what I should look for in the final game of the World Cup.	[ "I would say that's incorrect from NPR. It's more that most nations have a traditional playing style e.g. Italy: deep defensive line and counter attacking, brazil: attacking with lots of flair, England are stereotyped as playing long balls up to a target man. Recently Spain have been defined by their possession bas...	[ "I've always been fascinated by the wide variety of \"Fall of Rome\" arguments and how they're affected by historical perspective. I was wondering: **Does your historical specialty advocate a certain theory for the fall of the Roman Empire? or what's a unique argument for the fall of the Roman Empire that you've co...
What is a soft spot on a babies head?	[ "A babies head is too large to fit through the vaginal canal at birth. The head had two soft spots that allow the head to compress so it can squeeze through. The soft spots firm up after a month and a half or so." ]	[ "There are authors who claim the practice began during the colonial period as an early \"mens\"/ \"ladies\" designation for an illiterate populace (the sun and moon being popular symbols for the genders during those times). The book : The Little Red Schoolhouse: A Sketchbook of Early American Education has the fo...
Why is it that in English, some Latin/Roman names are shortened, such as Octavian (from Octavianus), whereas other names, such as Longinus, are not?	[ "As a tangent, if that's ok, why does English use Leonardo and Michelangelo but not Raffaello? Is it related to /u/CubicZircon's answer about when the name was imported?" ]	[ "Comic book writers at the time wanted the character's name to scream what he / she does - especially where a character appears in many different short stories that someone might pick one up for no apparent reason in the middle of the story. Rather than having to read through the first episodes to understand that \...
What specifically caused the failure of the Delorean car?	[ "It's engine was crap, but so was the stainless body which was impossible to keep clean, it was expensive, and slow. Basically, John DeLorean bit off FAR more than he could chew. The man was a dreamer with an inflated sense of self-worth, and attempted (when nobody else would, for good reason) to start a brand new...	[ "Really simple. Because the ticket sites can't afford the server power and high end technicians on something that only happens once in a blue moon." ]
Why do kids in school sometimes call their teacher "mom" by accident?	[ "Isn't it usually the only other female that you have as much contact with as your actual mother? I mean you see her almost every day and she's still in a position of power. What I want to know is why after you say it that you become super embarrassed." ]	[ "Every time you make a copy of a cell, there is a chance for errors. For example when you photocopy a first print, it is pretty crisp and close to the original, but there are a few minor discrepencies. Now if you photocopy the copy, it gets more distorted, and so on until some letters get hard to read, it gets diff...
How are big boats able to float on water despute their massive weight?	[ "Because they displace that weight with the sheer size of the hollowed out size of the ship. The volume of water moved by the hull matches the weight of the hull. Archimedes principle - _URL_0_" ]	[ "I'm not positive what you mean when you say \"deal with fog\". If you mean when coming into port then they would have used lighthouses just like today. If you mean dealing with fog while in open waters then one was was to use the sun during the day since you can usually still tell where it is in the sky even throu...
What causes that heart-broken feeling in your gut?	[ "The [vagus nerve](_URL_0_) can cause that 'sinking' feeling in your stomach, chest, and even throat. It has a lot to do with stress and anxiety." ]	[ "Hey, I made a quick [video](_URL_4_) to answer your video! If you don't want to watch the video here's what I run over: - Sometimes our thoughts wander, leading us to a thought that we may see as sad or depressing! This can be done subconsciously and without us knowing! - Stimuli can affect our mood, for example: ...
What prevents voter fraud in states with no ID requirement to vote?	[ "Depending on the state it could be fairly easy to impersonate a registered voter and vote in their place. But in actuality, voter fraud involving mistaken identity virtually never happens. I don't remember the exact number, but in my state the number of documented cases like this is in the single digits. The estim...	[ "They basically just keep track of how much energy they provided to the communal grid, and how much their customers drew from the communal grid. They can produce it at a certain price, and prove their customers drew that power out the other side, so it doesn't really matter where the specific electrons came from as...
Why intervention is Libya considered a failure despite successfully saving human lives and toppling a brutal dictatorship?	[ "Critics point to the emergence of a largely lawless Libya which is in the control of various militias. This had led to the state becoming a prime breeding ground for radical groups to base themselves out of as well as create a hub for the international trafficking of weapons." ]	[ "Greetings everyone. In the few minutes this sub has been up, it's attracting sub-standard responses. Just a reminder of a few of the rules: * no responses covering events/conditions post-1994, per this sub's \"20-year rule\" prohibiting discussion of current events * no anecdotes * no speculation OP: your question...
Did the impact of the asteroid that destroyed life on earth at the end of the Cretaceous affect the placement of tectonic plates?	[ "There is one proposal that the impact may have triggered a period of intense volcanic activity in India (there was already some volcanic activity there, the idea is that the impact triggered a particularly intense episode), which might have had some effect on the future motion of the subcontinent. But there are no...	[ "I suggest reading David Fromkin's A Peace to End All Peace: The Fall of the Ottoman Empire and the Creation of the Modern Middle East. Mr. Fromkin describes how and why the Allies, through the Sykes-Picot agreement, drew the lines of the Middle East. He also points to imperial ambitions and Europe's lack of unders...
When European countries started trade with the Japanese in the 16th century, did they adopt any Japanese styles of armor or weaponry?	[ "Suits of Japanese armour became a fashionable gift for nobles to send each other but they were considered curios and would not have been worn on the battlefield. The portrait of Sir Neil O'Neill by John Michael Wright from the 1680's displays a suit of Japanese armour that O'Neill had been gifted." ]	[ "For the basics, I'd start with Nehemiah Levtzion's (older) Ancient Ghana and Mali. Susan Keech McIntosh has a paper reviewing developments since that book was published, \"Reconceptualizing Early Ghana\" (Canadian Journal of African Studies 42 (2008), 343\\-373). Susan McIntosh and Rodney McIntosh have a wide rang...
Since a fetus shares the same life supply as its mother, how can the child end up with a completely different blood type?	[ "The Placenta. It acts as a nutrient exchange between fetal blood and maternal blood so they don't need to mix at any point." ]	[ "Because breast milk is made of human fat and protein and formula is made of cows milk protein. That’s like saying why can’t we use peanut butter to make steak substitute? The protein is not engineered- it is natural - just not human." ]
Why are french female given name so popular in the english speaking world ?	[ "> Jacques, pronunced exactly like Jack, is a common male french given name that doesn't exist in english Isn't it [ʒak](_URL_0_), though?" ]	[ "\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..." ]
the concept of domain and range	[ "You have some function f(x). It's basically a black box; you put some number x in, and it will do some math on it and spit out some number y. You can plot the answers on a graph if you like; that's how most people visualize functions. The domain of f(x) are all the possible values of x that you can put in and get ...	[ "You can find the gravitational field as a function of distance from the center of the Earth [here](_URL_0_)." ]
how apes with a simillar muscle mass are so much stronger than humans.	[ "Think about your own body. How does everything move? All of your joints rotate, they do not slide in a linear motion. The size of your muscle determines the amount of linear force it can generate. But this alone doesn't dictate how much strength you will have for the motion. The other factor is the lever arm: wher...	[ "There is a site, _URL_9_, that does an ELI5 for each xkcd strip. This particular strip is explained here: _URL_9_/wiki/index.php/1545:_Strengths_and_Weaknesses Your question isn't answered directly in the Wiki, but it does contain a link to the MCA (Most Common Ancestor) wiki article, here: _URL_11_" ]
How do night vision goggles work and do they work like in movies?	[ "Night vision goggles have a few tricks up their sleeves. First of all, they use infrared light - infrared light are like colors of light that your eyes can't see - but they're around us all the time. This helps to see in the dark because there can be more infrared light around than visible, especially at night. Th...	[ "The stars you can see depend on your latitude (north-south), but not on your longitude (east-west) because the earth is constantly spinning around." ]
Would it make any sense to store data in DNA molecules since they are so tiny and volume-efficient?	[ "This is currently being researched: [Towards practical, high-capacity, low-maintenance information storage in synthesized DNA](_URL_0_). As I understand it, the storage density is very high but it is very slow to preform reads/writes as compared to traditional hard drives. The authors of this article suggest that ...	[ "To give a really simple example.... Say you want to compress a text file that contains: \"AAAAAAAAAAAAAAAAAAAA\" Originally that file is 20 characters long. You can compress it by doing this instead: \"Ax20\" You've now reduced it to 4 characters with no loss of information. In reality, compression works similarly...
Why are dragons so frequently associated with the European Middle Ages? Weren't they originally part of Nordic mythology?	[ "In the medieval period, dragons were strongly associated with the devil and the heroes who killed them were usually saints. Since medieval people were pretty keen on stories about how the devil and his agents were constantly threatening mankind and being defeated by the forces of christianity, they had a lot of dr...	[ "The American Midwest is a flat steppe that runs from the Artic of Northern Canada, to the deserts of Northern Mexico. The lack of natural barriers(mountains) for such a long stretch allows cold Artic air to mix with hot tropic air which creates the conditions necessary for tornadoes to form." ]
What was Africa's influence if any, on ancient Japanese and Chinese culture?	[ "Well, here's a slice of something I read not too long ago. Not a huge influence but: Yasuke (c. 1556-?) was a black (African) retainer who for a short time was in the service of the Japanese warlord Oda Nobunaga. The name \"Yasuke\" (彌介) was given to him after he took service with Nobunaga; his original name is no...	[ "They probably didn't. [Sweet potatoes, a south american crop, are found in Polynesia](_URL_0_), and [chicken, an Asian bird, is found in south america](_URL_1_), both pre-contact. Also, [Polynesia DNA is found in south america](_URL_2_)." ]
Why can organisms lift more than their body weight?	[ "Because we don't use weight to lift. We use a force. Chemical energy in our muscles is converted into a force that pushes up on the object being lifted. If the force we can exert is bigger than the force of gravity, the object will move." ]	[ "The orbit was chosen so that the things that needed to be done for ISS - both construction and servicing - were within the payload capabilities of the available vehicles. If it was in a higher orbit, the launch vehicles would be able to bring less payload to that orbit. How bit of an issue depends on the payload m...
why can two people catch exactly the same virus yet one person may get the "less common symptoms" also.	[ "Most symptoms of an illness, such as fever and rash, are actually your body reacting to and fighting off the infection. Different people's bodies will react in different ways. It is also possible they they caught a different strain of the disease." ]	[ "E-mail works in a similar way to the post office. You write a message and hit send, it gets passed off and the address read to see where it goes. It gets sent to that location where the address gets read and sorted into the correct mail box. Multiple clients and multiple servers all over the world just like mail b...
Do animal species other than humans have cultural variation?	[ "Yes, there are many examples. These are just a few: * Chimpanzees: [Ex. 1](_URL_2_), [Ex. 2](_URL_3_), [Ex. 3](_URL_0_); there are [many more](_URL_1_). * [Monkeys](_URL_6_) * Whales: [Ex. 1](_URL_5_), [Ex. 2](_URL_4_) * Birds: [Ex. 1](_URL_8_), [Ex. 2](_URL_7_)" ]	[ "While we have specialists in the field here, /r/AskAnthropology is more directly suited to questions of this sort, so I would suggest you X-post there!" ]
Is hydrogen radioactive? And if Yes why?	[ "Hydrogen has seven known isotopes. Two of them are stable (hydrogen-1 and deuterium). One of them (tritium) has a half-life of 12 years. The rest decay in a matter of zeptoseconds. Only the first three are relevant for fusion reactors." ]	[ "Suppose we are sneaking around at night. I can signal you to do something by blinking my flashlight, that is the basics of communication. Radio waves are the same sort of thing as visible light, just with a much larger wavelength. We can and do do the same sort of thing with UV light in television remotes, but we ...
What causes hypergolic fuels to react on contact?	[ "The molecules have energy at the start. They are rotating, vibrating and moving around. There is a spread of energies and so some of the molecules will have enough to react. If the reaction adds enough thermal energy to the system, then more molecules with have enough to react i.e. a chain reaction. Thermodynamics...	[ "You're right to be confused. It is 100% wrong as depicted in the movie, and a lot of people of wondered about why they made such a grave error considering the rest of the movie was somewhat realistic. It is likely that the reason this happens in the movie is that it makes things more dramatic. Artistic license i...
Why is the time a little different on the ISS compared to Earth	[ "It's a very tiny effect for the ISS, but since it is orbiting the Earth with some speed relative to the ground, a very small time dilation happens because of special relativity. Technically, when you are walking away from someone, you are also going a little bit slower than them, but it's all relative to the speed...	[ "Well i dont sleep good at night time very often, so when i get home from school i crash right away. Im guessing its just based on your body clock and what time you eat/go to sleep. Basically it just depends what your daily schedule is...." ]
When a plane crashes into a house, who pays for it?	[ "Yes, the aircraft will have insurance, and that insurance will cover the cost. It's really no different to if a car drives into a house and damages it. Source: I'm a pilot, all the aircraft I fly have insurance. If my work requires me to fly an aircraft that I'm not familiar with (or even if I am familiar with it)...	[ "Need more detail! Was the pilots voice being played through the speakers? If so, are your headphones wireless? Or did the headphones not cancel out the noise like you thought they should? Edit-- * If playing through the speakers, your headphones are wireless and the signal sounded fine: digital comm problem (im...
How does the stamps-as-currency system work in prison? How do you turn that into actual money?	[ "In prison, many, many people are unable to afford goods purchased through commissary. So, literally anything that you can get through it(snacks, paper, envelopes, writing utensils, hygiene products, etc) becomes a battering tool for those that have it." ]	[ "It's how poor students would pay teachers many years ago. Before schools were publicly funded, families had to pay for their kids to attend school. This resulted more in a barter system where kids of farmers would pay with apples or frequently potatoes." ]
Why do some peoples' joints ache before it rains?	[ "From my undergraduate-level understanding of physics and engineering, atmospheric pressure drops when it rains. When atmospheric pressure drops, your joints will swell because the fluid around them expands since the atmosphere isn't compressing it as much as it was before. Swollen joints are stiff and achy, at lea...	[ "You are on the correct trail in researching Milankovitch cycles. The question of does it effect weather is really one of time-scales. The characteristic time scale of Axial precession (wobble) is 26,000 years so any effect on our 'weather' would be on similar time-scales. It is basically impossible for something w...
Does anyone know the best non-fiction book about "Bleeding Kansas" (the history of Kansas from 1854 through the Civil War)?	[ "The Nicole Etcheson book was offered by the History Book Club when it first came out. It was the first serious historical work on the topic of Bleeding Kansas in thirty years, when it was published, back in 2004. Amazon still has a paper back edition for sale, but the History Book Club no longer stocks the hard co...	[ "The way history class goes in Saudi Arabia is pretty much as follows: (We'll ignore the fact that much of the recent history glosses over some very important subjects) Grade 1-3: History of the Prophet Muhammad Grade 4-5: History of the Rashidun Khalifs (First 4 khalifs after the Prophet Muhammad) Grade 6-8: Hist...
What exactly is the reaction happening when I clean tarnished silver with bicarb, Aluminium, and hot water?	[ "Aluminium is naturally very reactive, but is often covered in a thin layer of passivating aluminium oxide that prevents the rest of the aluminium from reacting. Aluminium oxide is amphoteric, and thus easily soluble in alkaline or acidic solutions. The hot bicarb solution is alkaline, and dissloves the aluminium o...	[ "\"One of the most common ingredients used was dihydrogenated tallow dimethyl ammonium chloride (DHTDMAC), which belongs to a class of materials known as quaternary ammonium compounds, or quats. This kind of ingredient is useful because part of the molecule has a positive charge that attracts and binds it to negati...
Why do I want salty food so much when I drink?	[ "Beer makes you piss, and piss has salt in it." ]	[ "I'm only speculating but it could be Pavlovian response. You've probably heard of Pavlov's dog where the scientist would ring a bell and then give the dog some food, repeat, repeat, repeat. Eventually the dog would associate the bell with food and begin salivating at the sound of the bell, whether there was any fo...

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