Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
Why did knights wear armour if they knew swords would pierce them?	[ "The media would have you believe that every sword user was a highly trained combat expert, and every sword stroke was a killing blow, but the fact of the matter is far different. Melee combat is a hectic environment; people are moving rapidly around you, sweat impairs your vision, clothes and colors can cause you ...	[ "It's like concept cars. They're putting all of these extreme ideas on display, and the ready-to-wear version will be more subdued. It's meant to show the idea. Project Runway sometimes does a competition where the designers have to make 2 looks. One ready to wear, and one avant garde, but they have to have the sam...
Does the removal of leaves from suburban land very year cause damage to soil quality?	[ "Generally leaf litter is a positive contributor to soil health in a number of ways, including but not limited to: 1. Recycling elements such as carbon dioxide and nitrogen to be absorbed again by plants, and playing a part in the nitrogen cycle. 2. Providing important food to microflora and fauna, which in turn wo...	[ "One theory is that [we're too clean](_URL_0_). By keeping our kids clean and not letting them chew on UFOs (unidentified floor objects), we're either preventing their immune systems from building a proper \"database\" of pathogens early on, or we're preventing them from coming into contact with symbiotic species t...
Why do women hate the toilet seat being left up so much?	[ "Men use it either up or down, so they check first if it's in the right position. Women always use it down, so they feel this gives them the right not to check. So sometimes they land on the raw porcelain or practically fall in. Pretty stupid, then. I used to think they wanted the top seat down too, so it looks ...	[ "Why not look at this as an opportunity to do a bit of science yourself? I can't think of an easier experiment to set up." ]
Why do the bonds between humans and dogs/cats seem so much stronger and more intimate than those between the animals themselves? My cat is much more attached to me than she was ever to her mother or her daughter (with whom she lives).	[ "You may seem as a better provider and do not conquest for territory as much (i.e. you don't hog the litter box) you're like a savior that opens the tuna can. Also, you're like 8 times their size, make friends in high places etc... [Edit] Omg gold on my 6th or so post in my reddit career?? I... I.. I'd like to than...	[ "It has to do with the terms used in a phylogenetic tree and direct lineage. Think for a moment about siblings and sexual reproduction. As you know males are XY in their sex chromosome and females are XX. In terms of the mom (the main store) the one X is ALWAYS conserved (in the case of a male) or both conserved (i...
Why do some tail lights appear to flicker in dashcam videos?	[ "Old filament lights won't do this, modern LED lights will, the brightness of the light is varied by switching the supply on and off rapidly the on time and off time can be varied, the longer it's on the brighter the light, this switching happens at something like a thousand times a second, the human eye can't dete...	[ "Non-expert here, but isn't it just an adrenaline surge? It's just the muscles getting twitchy in preparation to bolt at any second. _URL_0_" ]
Why were Africa and the Americas able to be colonized so easily? Why did they never form the sort of outward focused empires that Europe and Asia did?	[ "Hi there! You might be interested in one of our past threads: * [The native americans and several other cultures did not experience the same technological advancements as europe. What has caused this diffrence?](_URL_0_) Much more lower-quality IMO: * [Why did all of the other continents develop so much quicker th...	[ "No selection pressure, particularly. The two below answers are basically correct - they weren't black to start with, and they stay out of the sun. Between them, that means there is no significant advantage to being darker and no genetic hypermelanism to inherit, so the average colour of the population doesn't chan...
How did the KGB work?	[ "The KGB was a network of informants. They had their ears everywhere. & #x200B; This presented the problem. If you said something that someone thought might get them favor, they passed it on. Eventually, it would reach the ears of an actual KGB agent, who were allowed to do whatever they saw fit to eliminate dissi...	[ "Not to discourage anyone who wants to post, but [this](_URL_0_) older thread covers this question, and got a pair of extremely impressive answers from /u/Georgy_K_Zhukov and /u/kieslowskifan." ]
Why are cats so fascinated by boxes?	[ "The safest place in nature is a hole or cave where you're protected on 5 sides and only exposed on one. Evolution favors safe behavior like this, so it has become instinct. An open box is the modern equivalent-only open on one side, danger can only come from one direction, so they feel safe. It's also the reason c...	[ "The basic principle behind calculus is fairly easy to understand. Imagine painting the walls around a round ship window. It's got that neat brass stuff, and you don't want to paint that so you have masking tape. So how do use straight masking tape on a round window? You use some small strips. You can start with ...
What is drawing unemployment? Do you have to pay it back?	[ "The laws/rules vary from place to place, but generally, no, you don't have to pay unemployment back. The money comes from taxes or insurance rates paid by your employer. In most places, you become eligible for unemployment after getting terminated or laid off without fault. For example, you'd be eligible if you go...	[ "America has regulations for this: _URL_0_ > * Illustration must be less that .75 or more than 1.5, in linear dimension, of the currency > * Illustration must be one-sided. > * Destroy or erase anything used in the making of the illustration that contains an image or part of the illustration." ]
How do we have pictures of our galaxy?	[ "We don't have pictures, it's more of a painting. Ex. You're sitting in a room, you could make a bird's eye view of the room without being at the bird's eye point of view. So what scientists/astrophysics nerds along with programmers have done, is made a map of everything in our galaxy (drawn it out from our PoV, w...	[ "The same way you can see your house if you are in it. It looks different from if you were looking at it from the outside, but you can still see the walls." ]
Why does the body drastically change more when you stop working out compared to when you never worked out in the first place?	[ "Your muscle mass is determined by many things, including age, nutrition, hormonal factors and most importantly the physical demands you place upon your body. If you've never worked out in the first place, your muscle mass will be what you require for your everyday life (quite muscular if you're a blacksmith or som...	[ "Johnny loves math, he's very good at it. But every summer break in between grades, he doesn't practice his math. He does other things like skating, baseball, and playing spin the bottle. No math equations or learning takes place all summer long. When Johnny returns to school, his brain hasn't kept up on math what...
If you peeled surface of the Moon and laid it over the Earth, how much area would it cover?	[ "The moon has a surface area of approximately 37,930,000 square kilometers. By comparison, Earth has a surface area of 510,072,000 square kilometers, approximately 13.4 times larger. The surface area of the moon is roughly equal to that of Africa and Australia combined. By comparison, Mars has a surface area of 144...	[ "For what it's worth, NASA did print it out (or someone did). The (almost) full mural was hanging out at the AAS conference in Seattle a couple weeks ago (AAS is the biggest conference of astronomers every year). It was printed at 240 pixels per inch and was 25 feet long by 7.5 feet tall ([pic with info](_URL_0_)...
How can Jupiter protects earth from asteriods and comets when its orbit is 12 years long? Is earth vulnerable when Jupiter is on the opposite side of the Sun?	[ "Keep in mind that because or orbital trajectories, it is almost statistically impossible for a direct collision path in objects in space. Instead what is far more likely to happen is that gravity will \"bend\" orbits and eventually collide in hundreds/thousands/millions of years. Therefore the objects in the solar...	[ "Point a flashlight at the wall and turn it on. See the small circle? Now, let's say your flashlight is delivering xyz power to the wall. So xyz power is landing in that circle, right? Tilt the flashlight in any direction. The circle spreads out across the wall doesn't it? But you didn't change the batteries or any...
How do scientists determine the weight of far-away planets?	[ "They use [Doppler spectroscopy](_URL_0_) to determine the relative motions and period of the star and planet. [Orbital mechanics](_URL_2_) then gives the mass ratio of both. Edit: [Dannei's comment](_URL_1_) is a far more complete and instructive answer to this question." ]	[ "Math. After we were able to accurately monitor and figure out the body's course it was simply (not that simple) math and physics that told us where it would go. (EX: at day 12 month 5 yr 1981 it was here, on day 27 3rd month yr 1984 it was here, insert big math problem, and we now know that on day 1 month 1 yr 198...
Why do small animals such as squirrels have such 'jerky' movements?	[ "They’re small and agile meaning there is less weight hindering fast movements. Also from the size perspective, I imagine it would look somewhat similar to our movements in terms of speed and range of motion (if that’s the right way to phrase it, could be wrong). In some it is quite likely aided by the threat of pr...	[ "So basically it runs through a list of ranked elements. You usually want the higher ranks first in the list, so if it sees an element ranked lower then the next one down, it swaps them. It goes through the list in one direction, then once it reaches the end it goes back through the list in the other direction. It ...
What makes classical music "good for the brain" as opposed to other genres of music?	[ "They actually debunked that, same with that nonsense about listening to classical music in the womb making your child smarter. It was all just BS to sell some cds. I'll see if I can find an article about it, and I'll edit this to put it in. And now to see if this answer is long enough, or if it will get auto-modd...	[ "Imagine any drug you take is like a key and that key can only fit into certain keyholes (receptors) on certain doors (target organ/tissue/nerve etc). There are different types of muscle relaxers (keys) that open certain doors and causes a reaction to occur behind that door (this is the drug action). This is how th...
If I looked at the night sky during the Jurassic, would I recognize any constellation?	[ "It is doubtful that many constellations would be recognizable. Even over the course of 100,000 years, there are significant differences. I created [these images](_URL_0_) using [Stellarium](_URL_1_)." ]	[ "We make good guesses based on what little examples of skin have been preserved as impressions in stone, and what other animals we know that are similar are like. As we learn more, our guesses get better and hopefully more accurate. This is why we now believe that many dinosaurs had feathers, when we didn't before....
New inventions gender?	[ "Except for borrowed foreign words, the conventions for the gender of new words are based largely on the endings of similar existing words. Exceptions tend to be very old and \"grandfathered-in,\" rather than new. Regardless of the gender you choose for your invented word, people are likely going to use what sounds...	[ "Not my field, but the most plausible candidate I've heard of is Paul Otlet in the early 20th century: _URL_1_ _URL_0_ I disagree that his idea of \"electric telescopes\" maps clearly onto our idea of \"computers,\" as the second article claims, but Otlet definitely had the idea of a global information network (as ...
With aneutronic fusion, how would you determine that fusion was occurring?	[ "You don't need to detect neutrons to know that fusion reactions are occurring. [Here](_URL_0_) is a list of candidate reactions for aneutronic fusion reactors. You can detect any of these reactions simply by detecting the particles in the final state." ]	[ "I'd be simpler just to build a [fusor](_URL_1_) with deuterium. _URL_0_" ]
Medically speaking, is losing one's will to live and dying actually a thing or are there always other causes?	[ "Depression can worsen health problems. I don't think an otherwise healthy person who is seriously depressed has ever just died, but in people who are old and/or sick, their attitude and \"will to live\" can have a significant impact on their chances of living." ]	[ "Ok, so in the chest cavity between the ribs and lungs there is space, which normally has lower than the atmospheric pressure. This allows the lungs to expand and fill with air when we open our airways and use our breathing muscles. If there is communication between this space and the outside (from a stab wound etc...
Why any country would ever need more nukes than can destroy the surface of our planet (as many have already)? Aside from fighting aliens, obviously.	[ "> Why any country would ever need more nukes than can destroy the surface of our planet (as many have already)? What we already have isn't anywhere near what would be needed to destroy the surface of the planet. The earth is REALLY big, like 510,000,000 km^2 worth of surface area. A 1 MT bomb (which is larger th...	[ "When cells divide they make pretty much exact copies of themselves. Introduce radiation to the equation and the copying process goes screwy and the new cell is different. Rinse and repeat over and over and you end up with body cells which are completely different in shape size and function to what they were origin...
How does the amount of chromosomes affect the complexity of an organism?	[ "Well, \"complexity\" of an organism is kind of hard to define. Are humans (46 chromosomes) more complex, on a genetic level, than chimpanzees (48 chromosomes)? I think your question is not really about number of chromosomes but really about the sheer amount of genetic material, or maybe even the number of genes, ...	[ "Basically, they get more experience at writing code for that hardware and learn how to optimize it. It's like getting more practice with a set of paints. You don't get more colors to work with, but you learn how better to use the ones you do have." ]
Were living conditions in the Soviet Union during the Cold War really as terrible as we're always told, or is it just a case of exaggerated history by the victorious Western nations?	[ "I agree that history is written by the victors, but I live in an area that has a pretty large number of immigrants from that area and the ones that I've spoken to about it have all said the same thing. Rampant corruption leading to horrible living conditions for all but a very tiny handful of wealthy elite." ]	[ "Hi there, those interested in recommending things to OP! While you might have a title to share, this is still a thread on AskHistorians, and we still want the replies here to be to an /r/AskHistorians standard - presumably OP would have asked at /r/history or /r/askreddit if they wanted non-specialist opinion. So ...
Does the change in an electron’s wave function and probability density function happen instantaneously when it changes energy state?	[ "No, it doesn’t happen instantaneously. For example if you have a particle in an excited state with one lower-energy state (the ground state), the time-dependence of the wavefunction is something like exp[iEt/~~h~~], where E is a “complex-valued energy” E = E_0_ - iΓ/2. E_0_ is the actual energy of the excited ...	[ "The Bohr model can't really 'prove' Planck's black-body law. It assumes (ad-hoc) that angular momentum is quantized, without any rationale, really. (Except the one given later by de Broglie in terms of de Broglie-wavelengths) The Bohr model doesn't obey the uncertainty principle, the Schrödinger equation does. Not...
What do banks do with our money?	[ "Invest it in order to make money themselves. In return they give us interest on the money we store in them, and provide services like loans in the form of mortages and credit cards." ]	[ "Advertising, mostly, but also being able to fund grassroots campaigns to help \"get out the vote\". Its really appalling how often the candidate who spends the most wins." ]
why does a Geiger Counter have that distinctive sound when detecting radiation instead of just beeping the intensity?	[ "Radiation particles striking a gas filled vacuum tube create a \"spark\" (keeping it simple for a 5 year old). The tube is hooked up directly to a speaker so you're hearing the actual noise. By not introducing another layer of circuitry to transform the no3ose into a beep, you keep the cost and complexity down. Fi...	[ "winds a spring, the spring then slowly turns a tube, typically made of metal, with bumps punched in it (think like a braille tube) this tube runs across little bits of metal that work sort of like tuning forks, the bumps \"flick\" the tuning forks and they make a sound. depending on where on the barrel the notch i...
How were foreign volunteers of Spanish civil war treated when they returned to their countries?	[ "In America, during the McCarthy hearings, the leaders of the Veterans of the Abraham Lincoln Brigade were subpoena'ed by the House Unamerican Activities Committee and accused of running a Communist front organization, which they denied. Interviewed decades later, most Abraham Lincoln Brigade veterans claimed to ha...	[ "OP, you need to clarify: are you white, black, Native, or some class of immigrant? Rich or poor? Are you (presumably) free or are you a slave? How old are you? There are a lot of variables to \"a man,\" and most males wouldn't have fought at all." ]
Are there any planetary orbital features that we know to be theoretically possible, but have never found an example of in any exoplanet?	[ "Most of the time we don't have the tools to find something. We don't have a clear confirmation of anything orbiting exoplanets. There is a very strong indication that [this planet](_URL_1_) has rings and [Kepler-1625 b](_URL_2_) probably has a moon, but that's it. * We haven't found any trojans (orbiting 60 degree...	[ "For shapes called [homoeoids](_URL_0_), there is a [generalization of Newton's shell theorem](_URL_1_). In potential theory (for gravitating systems or electrostatics) this theorem is often used to invert the Laplacian for ellipsoidal distributions." ]
Why does America continue to support Israel despite everyone in that area hating us for it?	[ "Every arab state, with two or three partial exceptions, was invented out of thin air after WW1 and drawn on a map. The difference is, israel represents a national home for an ethnic group that previously did not have one whereas a country like syria does not; syrians are levantine arabs who are divided by faith, a...	[ "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...
Is the sleep you get after being really drunk (i.e. passing out) the same as a regular night’s sleep?	[ "No, it isn't. Alcohol causes problems with the placement and duration of REM stages, causes disruptions in sleep maintenance, as well as problems with SWS stages. It isn't the same for everyone, and it actually depends on how much alcohol a person has had. EDIT: For those asking about [cannabis and sleep.](_URL_0_...	[ "The exact how is a little more complicated then i really understand, but roofies (rohypnol, pharmaceutical name flunitrazeoam) are a benzodiazepine. That type of medication is usually used for anti anxiety, insomnia, and in some cases preventing seizures. You might be more familiar with another member of that fami...
How does the Voyager spacecraft know its orientation, location and speed in space?	[ "Voyager has a sun sensor and [star tracker](_URL_0_) that keeps track of the star Canopus. There are a number of thrusters so it can adjust its orientation and it has 3 gyroscopes to keep it stable. I believe the location and speed are calculated values and somewhat approximate. Since there is no friction velocit...	[ "They use [spectrographs](_URL_0_), a device which measures the light that comes off that planet. This works because most substances have their own spectral fingerprint, which is very recognizable. For example, if you hold salt in a candleflame and look at the spectrum, it will have a bright orange emission line, ...
online quiz/test websites that require facebook login. why do they require that, what information do they get and what do they do with it?	[ "A lot of information is shared in both ways, mostly interests. Also, it means the site can hold logins of users without being responsible for password security and stuff. All security of user data and such is on Facebook's hands." ]	[ "Cooked something really nice? Show it. Lost a few/lot of extra pounds? Show your transformation off. Have kids that make you feel proud to be their parents? Show why you are. Have cats that you love? Sure why not, just show it, people love animals. People like to show others things that they are proud of." ]
Why is it that teachers have such a low salary? And isn't it counter productive to say they need more teachers but offer the same pay for more work?	[ "The recognition that there is a need for better education and the work load for teachers is too high does not directly translate into more money being available to hire or pay for teachers. Funding will not automatically materialize just because people on the ground want more. What happens is that people are given...	[ "Neighbor across the street: \"Hey Tommy, will you mow my lawn?\" Tommy: \"Sure, I'll do it for $5/hr.\" Neighbor: \"How about $3?\" Tommy: \"I want $5.\" Neighbor: \"OK, well I'll just ask your brother.\" Tommy: \"My brother and I and all the neighborhood kids decided together that we weren't going to mow lawns fo...
How does shoe/tire tread improve traction even though it's decreasing the contact area?	[ "It doesn't. That's why you use slick tires, which have no treads, for track racing. Treads only exist to help you deal with water or fine debris (e.g. dust) on the road/floor. A slick tire would hydroplane and lose all traction on even a slightly wet road, whereas treads allow that water to go somewhere else and k...	[ "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...
I can't seem to find a definitive conclusion to the safety of Genetically Modified Organisms for human consumption. Can someone please clear out the fog?	[ "The DNA itself isn't going to hurt you. If it codes for a toxin to be produced in the organism, you could be hurt. If it codes for something harmless to be produced, you would not be." ]	[ "To broaden this just a little bit, what was the public awareness of the bomb's nature in general (as opposed to the long-lasting effects)? Did the public in the United States (or Japan or Europe) know that the bombs were not conventional bombs immediately after they were dropped? If not, when did the general publi...
How is the supermoon caused?	[ "\"Supermoon\" is merely a coincidence. The moon orbits the earth in an elliptical pattern. This means it will have a point in the orbit that is closest to earth, and a point that is farthest from Earth. The moon also goes through phases, from new to full and back to new. A Supermoon is the name we give it when the...	[ "[Earthshine on a Young Moon: Explaining the Lunar Farside Highlands](_URL_0_) is one recently trending hypothesis for what scientists describe as topographic dichotomy (maria on one side vs highlands on the other). And you're right, the crust appear to be thicker on the far side." ]
The moon is one light second away from the Earth, does that mean if I am viewing the moon from a telescope I am seeing 1 second in the past?	[ "Technically everything you're seeing is from the past. It's just that on short distances like from your monitor to your eyes, it's a teeny tiny bit of time. As the distances increase, the time you're seeing goes further back." ]	[ "The average speed of Apollo 11 was [5500 km/hr](_URL_0_) = 1528 m/s. At that speed, the effect of relativistic time dilation is 1:1.00000000001298521 s, which over the course of a 73 hour, 27 min flight would be 3.4e-6 seconds. This is a minimum estimate of the relativistic time dilation effect. The maximum speed ...
Since most major ISPs are disliked, why do no smaller ISPs with better business practices pop up?	[ "Investment. It takes millions of dollars and years of getting construction permits to dig up roads or putting up new poles to put in wires. Back in the 90's many ISPs existed, because everyone was piggybacking on existing telephone connections. But once you had to deploy new hardware to telephone network, then ...	[ "Building is often done in bulk, dozens of houses at a time, which means you get economies of scale, not just in the materials etc, but in the laying on of services. Building a row of houses needs a trench dug for the sewer connections, for example, but you can do the whole row at one time - likewise the foundation...
Who discovered the optical prism? How?	[ "Since this is a question about the history of science you can try asking at r/AskHistorians" ]	[ "Because people AROUND the person wearing sunscreen need to see. If it's refracted, there would be mirror-coated people hanging around, blinding everyone" ]
Does Gandhi deserve to be as idolised as Indian school textbooks would have us believe?	[ "This is a good question, but I don't think we have a lot of people on this subreddit that are familiar with Indian school textbooks. Could you perhaps elaborate with some specifics on how he is depicted?" ]	[ "You answered your own question. Influential people often get streets named after them. There are streets named after JFK, Washington, and Lincoln to name a few in many large towns as well." ]
Why do car brands reuse their model names? No other branch does this.	[ "because they don't change that much from year to year. camry will always be a mid-sized satisfactory driving appliance." ]	[ "Three ways: * A shorter form of the name of the compound or active ingredient. eg: Tylenol is derived from the chemical name for the compound, N-aceTYL-para-aminophENOL. * They licensed the drug under a certain chemical name and use that. FDA: Acetaminophen is the sold name of Paracetamol * They use somet...
Why haven’t we designed cars with interiors that don’t trap solar heat, turning themselves into a lethally hot oven?	[ "There's really no way to cool down a sealed metal box set out in the sun without running the engine. The safety feature is called 12 years of publicly funded education. The coolest it can get without some sort of energy added to a cooling system is the outside temperature and that's not good enough to stop infants...	[ "They use a wavelength of light that is cancer causing. Do you want to sit under a cancer causing light? Plus, they aren't all that effective to stop, say a sneeze from transmitting to another person. It takes some time to kill the germs." ]
Why do most US History classes skim over the period from the end of the Civil War to WWI?	[ "Maybe it's just because of where I grew up, but we learned a lot about Reconstruction, industrialization, the Spanish-American War and the various political movements that happened between 1870 and 1910. That being said, relative to the Civil War and WWI, there are more important periods in US history." ]	[ "Is this a homework question? It says in our [rules](_URL_2_): Our users aren't here to do your homework for you, but they might be willing to help. Remember: AskHistorians helps those who help themselves. Don't just give us your essay/assignment topic and ask us for ideas. Do some research of your own, then come t...
Were Slavs targeted by the Nazis as part of the Final Solution?	[ "You're friend is technically correct in that Slavs weren't targeted as part of \"the final solution\" aka the Holocaust. The \"extermination phase\" of the Holocaust targeted the Jews and the Roma. Other groups like Homosexuals, trade unionists, communists, etc. were interned in concentration camps and millions of...	[ "You might be interested in past posts on the topic: * [_Were there known instances of 'breeding' slaves for certain traits/purposes during North American slavery?_](_URL_1_) ^(03 Feb 2013 \| 41 comments) ^(answered by /u/Talleyrayand) * [_Selective Breeding During American Slavery_](_URL_0_) ^(14 Dec 2015 \| 2 c...
Is it possible to feel "high" without using drugs?	[ "Another way that I can't find in the replies, though I don't recommend anyone try it out, is near-death experiences. Many reports of near-death experiences are identical to psychedelic experiences induced by psychedelics (LSD, magic mushrooms, mescaline cacti, DMT, etc.) and other compounds (ketamine, high doses o...	[ "I'm sorry that I'm no expert, but I remember reading about this the last time a similar question was asked: _URL_0_ Basically, you percieve time faster after your run because of endorphines released during the work out, which means that the music seems slower. This is apparently also why a lot of rock musicians pl...
The "helicopter" sound when rear windows are rolled down.	[ "Thank Christ you hear it too!!! Everyone I ever drive with says they don't hear it!" ]	[ "Basically you are hearing the muscular waves or [peristalisis](_URL_1_). More detailed explanation here at [Discovery Health](_URL_0_)." ]
What do the symbols connecting the elements mean?	[ "These bonds show the 3 dimensional structure of the molecule. The plain lines are in the plane of the page. The solid wedge shape signifies a bond coming out of the page towards you. The dashed line signifies a bond going into the page away from you. It's as simple as that. Chemists use this to show a 3D structure...	[ "You just have to memorize the chart. There's no trick to it. You should get used to this if you will eventually have to take Organic Chemistry. Here's a [picture](_URL_0_) of the chart to help you out. All you really need to do is figure out how many chemical bonds you have, and how many lone pairs you have, and t...
is capsaicin really good at stopping cancer?	[ "You know what else stops the growth of cancer cells in the lab? A blowtorch. There are literally thousands of substances that preliminary studies show might fight cancer. Some have side effects more severe than cancer, some only work on mice or in lab conditions, some work, but not as well as existing medicines, ...	[ "Serious follow up question. My nipples get hard while eating spicy food. Is there a logical reason for this? Edit: Well, 4 years into this Reddit thing, and this is my top comment 😅" ]
Why we use words such as "al dente" or "a la carte"	[ "\"English\" is a hodge-podge of other languages. Trying to separate things out and say \"this word is proper English, but this one isn't\" is fraught with all kinds of danger, because pretty much everything comes from another language. More importantly, language is about conveying meaning and intent. \"Al ...	[ "Explain ___ like I'm five or Explain __ LI5 would be great in my opinion, and having a loose format like TIL also helps when browsing the main page (to easily identify which subreddit the post is from based on the title)." ]
[Physics] If matter can't move faster than light, how did the inflationary epoch of the big bang make the universe much bigger than one lightsecond in radius in one second?	[ "Matter can't move through the coordinates of spacetime with a velocity of c, but that speed limit does not apply to the changing geometry of spacetime itself. Inflation is not the spreading of matter through space, rather it's the early expansion of spacetime itself." ]	[ "The signal travels the same speed but you can fit more waves in the same time span. Mid-visible range wavelength is 550 nanometers. Radio waves can vary between 1 millimeter to kilometers. Which means you can fit 1,000 to 1,000,000,000 waves in the same time span. Thus you can send more bits of information in the ...
How does devaluing a currency "stimulate exports" in any real sense of the term? Doesn't the stimulation only occure because the exporters DON'T change their prices to account for their now weakend currency?	[ "Good question. I think you are just missing one point, the value on the Canadian side. The assumption would be that if the price does not change on the US side (ie. still $100 USD) then their buying behaviour wouldn't change. They would still buy the same amount of product. On the Canadian side of the transaction,...	[ "You have a lemonade stand. You sell it for 50 cents a cup. One day you find out it's going to be very hot outside and people are going to want more lemonade. You figure you can get away with selling it for a little more since the demand is there. So you start charging 80 cents. You notice that the number of people...
What is the purpose of UV protected clothing if I've never gotten a sunburn under normal clothes?	[ "Many normal clothes are indeed very good at blocking UV, so in some cases it simply means they checked. In some cases it means the fabric has been treated to be unusually effective despite being quite thin." ]	[ "It's like concept cars. They're putting all of these extreme ideas on display, and the ready-to-wear version will be more subdued. It's meant to show the idea. Project Runway sometimes does a competition where the designers have to make 2 looks. One ready to wear, and one avant garde, but they have to have the sam...
Why are so many grown up child actors short?	[ "Child actors are very often small for their age. It allows them to play younger. It's easier to direct an eight year old that looks six than a six year old. It also makes them seem more charming and precocious for the age they're playing. Well, small kids often grow into small adults." ]	[ "here's a previous thread: _URL_1_ Top answer basically says that the were present in warm climates, but they always had full sized doors to shut when the shop was closed (you can actually see tall doors backing up the small ones in [this clip from back to the future](_URL_0_))." ]
Why, when I am around a camp fire, does the smoke always flow towards me?	[ "The best answer here is going to include the phrase \"confirmation bias\" I guarantee it." ]	[ "Imagine vectors as a moving fluid, say water. If water is entering form somewhere (i.e. a water source), then there is a positive divergence. If water is getting sucked out (i.e. a sink), then there is negative divergence. Now imagine that the water is spinning, like in a toilet. If the toilet water is spinning cl...
Are mammals born with the same number of nerve endings as an adult? Or do new ones grow as the animal grows?	[ "I think it would depend on the mammal and the body part. I know that some nerve endings can regenerate. In the case of marsupials, at least, I would be willing to bet they grow more after birth, since they exit the womb much less developed than other mammals and need to live in the pouch. In the middle of a move, ...	[ "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...
Why does water feel cold when it's running on a tap, but then it doesn't taste as cold when you drink it?	[ "I assume it has to do with the fact that the temperature difference between your hand and the running water is constant because the water is being refreshed whereas the water in your mouth is sitting still and water molecules close to your skin warm up and will take away heat from your mouth less quickly making it...	[ "Capillary action, and your legs have this giant artery called the Femoral Artery. As the blood moves through the leg and foot (that is uncovered) it is cooled by the outside air easier, and returned to the body a bit cooler. With the capillaries spread over the feet, and skin it gets more surface area to cooler ai...
How did UDT navigate dark waters when visibility is nothing?	[ "Most of the time they did dead reckoning. That is to say that they went in a straight line until they either hit something or until they figure they have gone far enough. This did actually work sometimes but at least it brought you closer to your target. They would also pop their heads/periscope above the water fo...	[ "A lot of man power, often in the form of navvies, who are actually named after their work on the canals - naval engineers. The average navvie could dig a trench 4 foot wide, 4 foot deep, and 30 foot long in a day. And lift it all above their head. Hire enough people, and you can build anything big enough. Liz Mc...
What makes America so in love with their military?	[ "Americans have never really had the displeasure of seeing their own military used as an occupying force against them. Most other countries have." ]	[ "\"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..." ]
Why do humans have such a bad grasp of time?	[ "While we survived and grew as a species by being able to remember what didn't work from the past and plan for advancements in the future the main survival instinct has always kept us focused in the now. The now is there immediate danger is, where hunger and thirst are. The need to survive moment to moment is the m...	[ "Not quite. For a start there are leap-years. You're about a quarter of a day out each year until we throw in an extra day to tidy up. Without this the seasons would slowly drift out of synch with the year. Also there's the precession of the equinoxes, which means that eventually though the planet will be in the sa...
Why are captchas still so popular?	[ "OCR isn't as easy to implement as you might think, which is why there are captchas that are harder and harder to read popping up, instead of captchas being pushed out entirely. Additionally, a newer form of captcha, the kind where you press play on a brief advertisement, and then get a text line to re-type, is gai...	[ "1. How does one spell what one doesn't understand? 2. It gives time to think amidst the stress. 3. Homophones." ]
What effect does cooking food have upon the nutrition within?	[ "Depends what you are cooking and what you are measuring. Cooking can break down some compounds, losing nutrition. On the other hand, only about half the protein in a raw egg is absorbable by the human digestive system. Cook it, and it becomes nearly twice as nutritious." ]	[ "Nervous system is all about the action potential in the neurons. All neurons signalling is an active chemical function. Energy is required to produce this function, and as a result lower temperatures drive down the energy available for the reaction to occur. This also happens in cells, making it impossible to main...
Why are Australian video game prices always higher than America's prices?	[ "Australians are used to paying more, so companies charge more because they know we'll pay. Often referred to by companies by use of terms like 'localisation price adjustments'. Other 'reasons' (weak excuses that don't stack up) include transport, cost of business, taxes, exchange rate, etc. none of which explain ...	[ "Websites look at the billing address you used and based on the state the address is in, they match it to that states current tax rate." ]
How do gas pumps know when to stop pumping fuel?	[ "They have a shutoff similar to the float in the water tank of a toilet. The shutoff triggers when it senses the nozzle is \"submerged\". It can also trigger if the nozzle is angled weird and enough gas splashes against it on its way down into the tank." ]	[ "With some difficulty. This was an issue in the Apollo 11 landing. Neil Armstrong had to send a message back about slosh in the descent engine tanks, and the Apollo 12 descent stage was modified as a result. But in a launch, the tanks are tall and narrow. They start off full and there is little side to side motion ...
How is buying insurance not a waste of money?	[ "In terms of the pure mathematics, you are correct, over the long run, you likely will pay more into insurance than you get out. That is the entire business model of the insurance industry. But insurance isn't an investment, it is about catastrophic loss. It is dumb to insurance something like a TV or cell phone, s...	[ "My personal reasoning was, when I lived in a not-so-nice area, to act as a deterrent against being a target of a crime." ]
Why do some smart phone apps demand so many permissions?	[ "Mostly because the programmer that wrote them was lazy. He's using a SDK that simplifies access to different parts of the phone, such as accessing the gallery, accessing contacts, an so on. The default state is that all modules are active, then the programmer should deactivate the modules not used. If he doesn't, ...	[ "For colleges there are scholarships and grants that are limited to specific races, ethnicities, and genders. For both jobs and colleges they need to know that information for legal purposes in case they get sued for discrimination in the future." ]
Do pets know they are pets or do they think they are humans?	[ "I don't think they know the concept of even being anything." ]	[ "I would say yes. [Here's](_URL_0_) an article about Dr. Clara M. Davis, a pediatrician who did a ton of experiments where she presented a bunch of foods to infants and allowed them to pick whatever they wanted. She did find that infants did know what foods to choose, but the choices that were given were inherently...
How do we know so much about planets that are hundreds of light-years away?	[ "The same way that astronomers find out almost everything. They use [spectrography](_URL_0_). Absorbtion colors - the specific colors of light that get emitted when light is absorbed by matter - tell you exactly what element or molecule did the absorbtion and emission. This process works with suns, atmospheres, pla...	[ "Scientist would probably start sending radio waves in that direction. That is all that could be done as we have not hope to do anything else." ]
What are the point of tokens?	[ "Additionally: security. Since you can only use tokens at the establishment they don't have to worry nearly as much about the hundreds of dollars worth of credits sitting in the cash box of a dozen or more machines. They just need the one or two money changers to be extra secure." ]	[ "That mosque is not in Timbuktu. It is the [Great Mosque of Djenne](_URL_0_), in the city of Djenne which is about 500 km south-west of Timbuktu in Mali. Anyhow, those are wooden timbers called toron. They are used to [support scaffolding]( _URL_2_) when adobe is reapplied to the exterior of the mosque, or when r...
How high above the surface of Venus would the atmospheric pressure be the same as Earth's at sea level?	[ "[This](_URL_0_) says that Earth's surface pressure is .985 bar. [This](_URL_1_) says that Venus' is 92 bar, with a scale height of 15.9 km (that is, the distance at which its atmospheric pressure falls off by a factor of 1/e). A simple calculation shows that at about 72.1 km above the surface it will have about ...	[ "Found [a handy plot for Voyager 2](_URL_0_) and it had exceeded escape velocity for the sun and since Voyager is faster, it too must have exceeded escape velocity. Looking at the plot, the blue line shows the escape velocity. The escape velocity drops as you get farther from the sun since the gravitational pull of...
What makes some materials oven-safe but not microwave-safe or vice versa?	[ "The dielectric properties of the material. In oven safe, the material has to take external heating, which will be a function of its heat transfer capacity ie if you heat it too fast, one area will expand too quickly, stressing the material and causing the break. For microwave safe, the dielectric properties desc...	[ "There are a few different technologies. I assume you are thinking of the touch screen on your phone screen. That works because the screen is electrified just a little bit, not enough for you to even notice. When you touch the screen it messes up the electrical field. The computer can measure how the field changes ...
Why do Italians consider that ordering cappuccino after lunch is rude/offensive?	[ "Because cappuccino is a breakfast only beverage. It can be tolerated if you use it for a snack mid-afternoon, but usually it's strictly morning beverage. For us Italians someone ordering a cappuccino after lunch is not rude, we see it as \"stupid\" or a distinction between a foreigner and a local. It's like eating...	[ "_URL_0_ Reportedly cows tend to feed more around sundown when the nutritional content of plants is higher. > “A series of USDA studies looked at animals’ ability to choose different forages. The researchers cut hay in the morning and in the evening and used this in the choice tests. They’ve done it with cattle, g...
Why do all mammals have a 4 appendage skeletal structure?	[ "technically because of [HOX genes](_URL_1_) and related things like [homebox](_URL_0_). That is, similar genes in all ancestors" ]	[ "Evolution. People who didn't get that weird feeling when dangling their limbs from the trees they were sleeping on were killed by cheetahs." ]
How are cells in tissues supplied with the nutrients they need (Aminoacids for Proteinbiosynthesis for example) ?	[ "Nutrients are in blood. Blood vessels are porous. Nutrients move from blood vessels to space between cells (and waste products move from space between cells to blood vessels). Nutrients enter cell (in one of several different ways) from space between cells. Note that some amino acids are synthesized inside the cel...	[ "We don't need them any more than other animals do, it's just that if you don't eat a balanced diet your life expectancy and quality of life will both be lowered. Animals can survive on one or two foods, but like us they'll be healthier if they get a diverse diet. Store bought pet food usually contains a mix of d...
In the HRE, why were some kingdoms, like Prussia or Austria, technically inside the empire, but had territory outside of it?	[ "The Holy Roman Empire is not a standard Empire. It is more akin to a confederation of small German lands that are tied together in a confederation. While I can't talk about why or how it was formed, by the 18th century, Prussia and Austria (or rather the House of Hohenzollern and the House of Habsburg) gained land...	[ "Paradox games starting scenarios are roughly historically accurate, then they go from there based on random number generators and player actions. Total War games, not really. Factions in Rome are much more fluid than Julii/Brutii/Scipii, and many units are made up, etc." ]
Does water freeze or boil in space?	[ "Boils first. While cold, the pressure outweighs this. The water would vaporize instantly. What little is left would instantly freeze. Boiling is less about temperature and more about pressure. Think of the core of Jupiter, while insanely hot, it is solid as if frozen due to pressure. EDIT: Well, I was posting to ...	[ "A lot of experiments to see what happens when there is little to no gravity going on. How it affects human body, how it affects, plants, animals, bacteria, equipement ect. It's also much easier to set up experiments that require very cold temperatures or very low pressures. [Here's a list.](_URL_0_)" ]
In the TV Series Vikings and The Last Kingdom, certain warriors are often seen to fight in pitched battles using two one-handed weapons. Is there any evidence to suggest that warriors would actually do this?	[ "More can always be said, but here are some previous threads about this topic: /u/nanashi_shino on [A lot of movies, shows, games, and fantasy novels have fighters using two swords to fight in combat. Was dual wielding swords ever an actual skill that was used in real fights?](_URL_1_) /u/Peli-kan on [Is there a re...	[ "The problem with this question is that what monks did and what they wrote that they did are not exactly similar. We know that monasteries usually relied on the protection of a local lord as well as the inviolate nature of the church. My field is European monastic history and I've never seen any textual mentio...
Why is the abbreviation for pounds "lbs"?	[ "From Wikipedia: > The unit is descended from the Roman libra (hence the abbreviation \"lb\"); the name pound is a Germanic adaptation of the Latin phrase libra pondo, \"a pound by weight\"." ]	[ "Not just the US, but it tends to make the price seem cheaper: $49.99 looks better than $50 even though it is only 1c difference. It's a mind game" ]
How many joules do I need to power a cell phone?	[ "It depends on the voltage source. If the voltage drops below a certain point the cellphone will stop charging. (Your cellphone always assumes to be plugged into a USB port, which has 5V. If the voltage drops way below 4,8V the cellphone would first reduce the charging power or stop the charging completely. This de...	[ "It depends on many factors: * Energy consumption rate * Body weight and fat * Age * Genetics * Many, many other ones" ]
Everything going on in Ferguson. Beginning to now.	[ "Unarmed kid got shot by the police. People angrily protested. The police got pissed. The protests turned into riots. The police continue to escalate to respond to the riots. The rioters aren't backing down, so the FAA declared Ferguson a no fly zone earlier today and now they're rolling out tanks into the streets ...	[ "Just a reminder to people considering to post: historical examples only please, and preferably well sourced. Not 'your opinion as a communist', not 'this is what I think is wrong with democracy'." ]
I saw a poster on the London Underground that stated 'Every 15 minutes, somebody in the UK starts to lose their eyesight.' How did they come to this statistic?	[ "They probably took a yearly rate of roughly 525k people per year, and evenly distributed them. Would probably be difficult to know whether they were getting it from insurance claims, or public health info, or what... but if you look around you can probably find a study with yearly rates." ]	[ "This is a sort of standard demographics/population biology question; I tried to answer it just now naively, assuming exponential mortality, but got a silly answer; you'd need to have the actual data from [tables like these](_URL_0_) along with a profile of current demographics and do some calculations on them. A g...
Did Romans living in the early Roman Empire recognise they lived in an empire rather than a republic?	[ "In the early Roman Empire, Emperors would attempt to maintain the illusion of living in a Republic although they held all the real power and the position of Senator was mostly for social prestige, not for influencing the Empire politically. This was referred to as the Principate, and lasted until roughly 280 AD. L...	[ "Before RICO laws it was hard to take down an entire organization because the mob boss could never be connected to any specific crime. The Mob boss would talk to his under-boss about an illicit act. The under-boss would pass the info along to a caporegime (a sort of lieutenant) who would then instruct one of his ga...
Why are resistors so strangely incremented?	[ "Resistors come in different tolerances, generally 1%, 5%, 10%, or 20%. The incremental values are based on the tolerance. For example 10% increments starting at 100 ohms would be 100, 110, 121, 133.1, etc. You can sort of see how some seemingly unusual values are arrived at." ]	[ "It is hard to start a motor, it would take a long long time to start on low. Going 0 3 2 1 let's the fan start on High which gets it up to speed in a timely manner" ]
Do your grades in highschool really affect you in the real world?	[ "They affect your ability to get into good colleges. Going to a good college can really help your future and make your life easier. More to the point, the skills you learn while earning good grades help make you better qualified for many jobs." ]	[ "The Taxes tanken from our checks are estimates. Sometime people pay too much or too little. When doing our taxes we figure out how much we really owed. Some payed too much and get a refund. Some paid too little and need to make up the difference" ]
How does auto-completion work (on text)	[ "Early systems had nothing to do with machine learning. It just used dictionaries. Advanced systems used a primitive form of learning, such as suggesting words you used a lot (and you were able to add new words to the dictionary such as addresses, names and slang to prevent it from autocorrect it every time). These...	[ "They pretty much don't. However website owners have the option to tell Google \"hey, I have a site here, check it out!\" When pages don't link to each other, website owners have the option to host a special file, named sitemap, that does list all content that should be searched for." ]
How were women forcibly sterilized in the US?	[ "Most forced sterilizations in the US were done at the order of eugenics boards, targeting those with disabilities or criminals. In many instances the victims were told they were simply doing some routine medical procedure and not informed that they were being sterilized." ]	[ "This [Wired article](_URL_0_) gives a good, ELI5-level discussion of the history and issues. I can't attest as to its accuracy, but I have no reason to question it either. TL;DR: Some conservatives (and in one case, apparent fascist troll) stacked the nomination ballots legally, causing a backlash in the final vo...
What is a Grand Duchess/Duke, who is eligible to become one, and what do they do?	[ "A Grand Duke, is usually the ruling monarch of a minor nation. The title is less of senior Duke and more of a junior King. Small provinces changed hands frequently in Europe, often without changing nobility, and often found themselves as independent states. That noble would find themselves as the head of state, m...	[ "I'm in the car right now (not driving), so hopefully someone can better elaborate. Rosalind Franklin took X-ray photographs (crystallography?) of the DNA double helix. She was working with James Watson and Francis Crick who published the information and received the Nobel Prize for the work. Franklin was not award...
Why do pupils dilate on drugs?	[ "Your pupils are like a fist. It takes energy and concentration to keep making a fist with your hands. In the same way, it takes energy for your brain to keep your eyes contracted. Dilated pupils are relaxed pupils...a fist unclenched. So with some drugs, your brain stops paying attention to contracting your pupils...	[ "Without getting too complicated, it limits the potential speed difference between the drive wheel on one side and the drive wheel on the other side. Let's say you are driving on icy roads and one tire is on dry pavement while the other sits on slippery ice. Without LSD when you hit the gas the wheel on the ice wil...
If I setup a funnel to catch the wind, would it speed up the wind's speed? If so, to what degree and what is the maximum of this?	[ "Ignoring some confounding complexities, the conservation of volume alone yields a very simple relation: A x v = constant, where A is the cross-sectional area of a pipe and v is the velocity of the fluid. So if you restrict the cross-sectional area by half you double the speed of air flow, for example." ]	[ "Your car acts as a [Helmhotz resonator](_URL_1_), just like when you blow in a bottle, but the frequency is obviously much lower because a car is much larger than a wine bottle. You can also look [here](_URL_0_) for more comments." ]
Why does Argentina want the Falkland Islands so badly?	[ "Having an external issue is a good way to keep the population from being concerned about internal problems, of which there are plenty in Argentina." ]	[ "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...
Why has Nationalism failed to become a primary source of Identity in the Arab States, where it has succeeded elsewhere?	[ "I will rather openly admit that I don't really understand the question. I thought Nationalism was the mindset that Ethnicity was important, and that each People should have their own Nation and all that. But then you argue against \"Nationalism in the Middle East\" by saying for example that minorities in Syria th...	[ "Hey all, lurker turned member here. Saw this and couldn't not put my two cents in. I'm an LPG contractor for Calor in the UK, and I've had insight and heard a lot of details in a lot of meetings over the years. Simple answer? Oil, as we are all so constantly reminded, is a finite resource. Why use your own when yo...
What is this Bronie phenomenon?	[ "Oh, for a moment there I thought I had stumbled into /r/circlejerk." ]	[ "Nostalgia, too ~ a lot of older guys that now have lots of money are reliving their youth - they either had one when they were young & want another, or wanted one when they were young and can now afford to pay the big bucks to get one." ]
In HBO's "Rome", Julius Caesar enrages the senate by letting Gauls and Celts become senators. This is pure fiction, right? When were people from the provinces able to become senators in ancient Rome?	[ "Caesar did in fact make many Gauls and provincials citizens, and it really angered the senate and aristocracy. There was a joke at the time that Gauls would peel off their dirty cloths, put on a toga and ask \"which way to the senate house?\" In \"Rubicon\" it's argued that he does this in order to place high-rank...	[ "Not a historian, but the answer to the first part of your question is somewhat widely available. One of the difficulties is defining the term \"literacy\" as it applies to ancient populations. Sometimes a person was considered \"literate\" if they could sign their name. Others were \"literate\" if they could copy ...
If my organs were stolen, and the police found the person who illegally bought my organs, would I get them back?	[ "Here's how this would go: 1. The police would notify you that they had found your organs. 2. The person with your organs would be brought to court. 3. In the wait for the court date, you would die. 4. The person with your organs would eventually be sentenced to prison time." ]	[ "Let's say you wanted to gamble at the horse track. You think Three-Legged Limpet is the horse to win on (despite having only three legs). You decide to place a $100 bet, but you don't have $100 on you now (payday isn't until tomorrow). The bookie agrees to take only $20, with the understanding that you will pay up...
Why does your nose run when it gets cold?	[ "Basically your body wants to warm up the air to protect your esophagus and trachea so it pumps a lot of blood to your nose (which does heat the air up) and all this oxygen causes your sinuses to go into overdrive." ]	[ "To keep balance we need our arms to swing roughly in time with our legs, when at walking pace this is quite slow and easy to do, when running we need to do it quicker. By bending the arm it lets us move it forward and backward quicker so is better for running, but when walking the energy required to keep the arm b...
How do/did mood rings work?	[ "short answer- they don't Longer answer- they are filled with a liquid crystal that changes colors based on temperature. As your body heats/cools, that temperature change also heats/cools the metal of the ring, which heats/cools the liquid crystals inside the ring." ]	[ "from what Ive found, the question has to many variables to nail down exactly, as each case is typically different. some research says its the swelling and shrinking of blood vessels, while others attribute it to memory association. In short, its a well documented phenoma with a variety of reasons and speculations ...
Sword carrying in Europe, 1500-1800	[ "It was expected of German students to train in fencing, facial scars from their endless duels were worn with pride. Even today you can still see some (very) old German academics with those distinct scars. Until ~1790 they were allowed to carry their swords at all time, after that only when traveling. Which was the...	[ "You have excellently clarified your original question with some more specific ones, but you might attract more, and better, answers if you specify a narrower time period or location. Did you have any in mind?" ]
Why was synth used so much in 80s music?	[ "Simply put, because it was new, it became popular very fast, and people liked it." ]	[ "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" ]
How is blood flow directed within the brain?	[ "Metabolic autoregulation whereby regions of greater metabolic activity cause increased local production of mediators such as C02, lactate, H, K, ADP which cause dilatation of local blood vessels and increased local blood flow. The cerebral circulation also is maintained across a broad range of blood pressures by...	[ "Autopilots are based on a [negative feedback loop](_URL_0_). A motor moves a control surface, until that control surface has the desired effect. When the control surface has had the desired effect, it is not moved any further. As for what is the \"desired effect\", the most common scenario is to use a flight direc...
What do historians mean when they say Feudalism is a debunked theory, and why do they believe this? What were alternative means of regulating economics/distributing property and resources present at the time to feudalism?	[ "Hi there -- while more can always be said on this topic, you may be interested in [this section of our FAQ](_URL_0_) and [this older AMA on feudalism](_URL_1_) while you wait for more answers." ]	[ "More can be written, but you might like to read [\"How common were western movie style shoot outs and duels in the wild west?\"](_URL_2_) , with answers by /u/gamblekat [here](_URL_0_), /u/verticaljeff [here](_URL_2_c7w2yxd/) , \\[deleted] [here](_URL_2_c7w31ij/), and to some extent /u/SnowblindAlbino [here](_URL_...
Since light has properties of both a wave and a particle, and on the atomic level even solid structures aren't completely touching, why doesn't visible light penetrate something like the surface of a desk?	[ "Light does penetrate solids, but it quickly loses intensity (and the objects heat up) so that reasonably thick objects appear opaque. You can see this for yourself if you hold some papers up to a light bulb, and you keep adding more sheets of paper until you can't see the light anymore." ]	[ "Sight works on light reflecting off of a surface and stimulating receptors in your eye that convert these stimuli into a signal that your brain can understand. These molecules do not reflect enough light for the receptors in your eyes to be stimulated." ]

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