Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
Why does the bigger headlight of my truck become yellow and foggy but the little one right next to it is still perfectly clear?	[ "The plastic used on the side lights is probably of different quality. The headlights also get hot...which likely cause the plastic to breakdown quicker. You can easily buff (polish) the headlight plastic to make them clear again. I'm also guessing this truck is a 2001 Toyota Tundra." ]	[ "Speculative, as I know of no scientific study on the subject, but I am an electronics technician and electronic warfare specialist who works with various radio and radar equipment. It's possible that the angle of your radio station relative to the freeway (and thus overpasses) is such that just as you go through t...
In WW2, Why did Germany open a second front with the USSR? Why wouldn't they wait until defeating Britain?	[ "It has been Hitler's dream for almost 20 years at that point to invade the Soviet Union and take Lebensraum (Living space) for the German people. Hitler wasn't about making logical decisions, Hitler was about making demands on his flights of fancy, on his whims, on his wishes, on his beliefs, etc and then everyone...	[ "Think of it in groups, where the top 2 teams in each group continue on to the next round. Let's assume, in the next round: * The Winner of Group A plays the 2nd place team of Group B * and * The Second place team in Group A plays the winner of Group B If the 2nd placed team of Group A was a particularly strong tea...
If there's enough food and resources in the world to go around, why is there so much poverty concentrated in certain parts of the world?	[ "Because the food and other resources are concentrated also. There are physical, logistic, and economic barriers to redistribution." ]	[ "How can [this](_URL_1_) and [this](_URL_0_) have different amounts of information on it if both are just pages? If you can find a way to make smaller 'marks' on a medium and read them again later you can fit more of them in the same space. At some point you can't make your handwriting smaller because otherwise yo...
If there was a gamma ray burst that hit the earth, what would human just walking around actually see?	[ "Guys... OP is not asking how fast or how probable it is. He's asking what a human would SEE in the event, if there's anything to see at all" ]	[ "This video created by Vsauce 3 (Jake Roper) does a very good job explaining this: _URL_1_ I hope this answers your question. He also did another video on a simmilar line of - could you survive: _URL_0_" ]
How does a disk become bootable?	[ "The computer is programmed (by a very low level program called the BIOS) to attempt to load the data at a particular location on the hard drive into memory when the computer starts up. This area is called the boot sector. To make a disk bootable, the installer puts the correct data in that very specific location ...	[ "Believe it or not, Microsoft have an excellent page on this: _URL_1_ Also, the \"dummies\" series have a good one, too: _URL_0_" ]
Today, large countries like China, Russia, and the US, are also the most powerful. In the past, how could relatively small countries like England and Japan occupy large countries like India and China?	[ "Industrialization basically. Other nations required more people to farm to get food and sustain themselves. Industrialization made it possible for one person to be much more productive. This means more people could be things other than farmers. Led to urbanization, factories, faster technological progress. Everyth...	[ "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...
Why doesn't acne occur on our palms?	[ "Acne is the blockage (and, sometimes, infection and inflammation) of a follicle and its accompanying sebaceous gland. These are not found on palms." ]	[ "This has been done. He even won an [Ig Nobel Prize](_URL_0_). There was no difference between his hands." ]
why do people donate thousands of dollars to streamers?	[ "I remember one person who gave away thousands like that was a 12 year old Saudi Arabian royal with insane cash. Basically, people with tons of cash. In that case, tons of cash and focusing on your priorities. Many young kids like streams." ]	[ "Better cuts of beef, better prep (like dry aging), better chefs to cook it. Also in a higher end restaurant you are going to be paying more for everything basically for the better service, atmosphere, location, etc. A nice steak at a high end restaurant is totally different from a $10 steak at TGI Fridays or somet...
How is the calorie content of food determined?	[ "A calorie is a unit of energy, specifically how much energy is needed to heat one gram of water 1 degree celsius. I should note that if you're American, when talking about food, what's measured is actually a different unit, kCals, which measures the energy required to heat one kilogram of water by 1C (so one calor...	[ "Competition among restaurants to show that they were giving the customer the best value for their dollar. \"Well, this place gives me this much food for $5, but that other place gives me even more for the same price!\"" ]
Is there any evidence of two seperate planets orbiting an object in the same path but not colliding?	[ "The simplest way for this to happen is for a smaller object to be a Trojan at a Lagrange point of a larger object. [The Trojan asteroids around Jupiter](_URL_0_) are an example. Saturn also has Trojan moons: Callysto and Telesto are co-orbital with the larger moon Tethys." ]	[ "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 does getting your tubes tied work?	[ "The eggs get released on schedule and you still have your period and all of that lovey mess it involves. The only difference is that the egg runs into the scar tissue/ligation point and stops. Eventually the egg just dies and is collected/reabsorbed by the body. & #x200B; As far as day to day life, as long as th...	[ "This is a very common question. You can use search to find [all the other really good answers](_URL_0_ ). This is instant, and faster than ust typing in your question every time. It's a way of cheating elections. Read the others, and then ask a more specific question." ]
Why look for water on other planets for other life?	[ "It might be possible that life can evolve in a liquid environment different than water. However for now we only have evidence that it evolves in water. It is also abundant in space and looking for it makes most sense." ]	[ "I love that question. Back when we were quite primitive, those people who would seek out different things and not be content with what they had, would go ahead and explore, possibly outrunning their competitors in the evolutionary race once ingenuity had been included into the important assets. It is really simple...
Why are hotel bed sheets almost exclusively white?	[ "It's cheap and easy to clean white sheets even if they get stained - throw them in with some bleach at high heat in an industrial washer and they'll look pretty good. You can't bleach stains out of sheets of another color and they can fade, so you have to take more care when washing them. White also has the advant...	[ "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." ]
if diseases like hiv are blood/vector borne, why don't humans and animals in western society contract it, via mosquitoes from one person to the next?	[ "Mosquitos (and other insects) have two tubes they pierce you with - one for injecting saliva, and another for withdrawing blood. It's basically a one-way system - fluid goes out of the insect through the saliva tube, and in through the blood tube. This means that any viruses sucked up through the blood tube won't...	[ "Intramuscular vs Intravenous needles. Blood draws are done from a vein, and the easiest one to hit on most people is the crook of the elbow. Assuming your right handed, they'll draw from the left because some people experience discomfort and can have a hard time using the arm for a while after the draw. The vaccin...
why does the rest of the Middle East hate Israel?	[ "A number of reasons, in decreasing importance: - provides a popular and convenient enemy as distraction from the horrific governments and shitty economic climates in most of the middle east - seen as European colonialists in Arab territory - religion - political differences. The mostly democratic Israel threat...	[ "\"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..." ]
How can the Department of Homeland Security actually run out of money? (since the House just failed to extend funding) A	[ "Congress doesn't budget for departments to build reserves like that, so when they stop cutting checks that's all she wrote" ]	[ "The Sun does create radio interference in such a situation (even though in most cases the Sun does not completely occult the signal Mars), and such an alignment occurs every 26 months. While I do not know the protocol for Curiosity, the way NASA has handled this in the past for Spirit and Opportunity is as follows...
Why some products have a variation of the warning "This product contains a chemical known to the State of California to cause cancer"? Why are they always California specific.	[ "California law establishes a civil liability for businesses that sell products or are in environments with a potentially harmful quantity of chemicals from an official list of potentially cancer-causing chemicals, unless they post the official warning. However, it's very expensive to do research whether your prod...	[ "Taxes. Delaware does not have a state corporate income tax for corporations that are based in Delaware but do no business in the state. Basically, if you operate your business entirely in, say, Iowa (the state with the highest state corporate income tax), but put your corporate headquarters in Delaware, you don't ...
Why is there such a gap between when a movie is released in theaters and when it becomes available on DVD or BluRay?	[ "If they released them at the same time they'd lose a lot of box office revenue because many people might rent the movie instead." ]	[ "To quote the great pop song from the '70s;Money, Money, Money, Money. MONEY.\" The record studio's pay the radio stations to play their songs. Simple as that." ]
If you continued to grind sand into finer and finer particles, would it ever begin behaving like a like a liquid?	[ "Powders with a spherical morphology that can slide past one another will behave like a liquid even with a rather large particle size. I have some spray dried silicon nitride powders at work that are ~30-40 um spherical agglomerates and you would think I was pouring liquid if you saw it come out of the bottle. The ...	[ "The peanut butter is heated to the point of being partially liquified when they pump it into the jars. The peanut pieces tend to rise slightly until the product cools enough to become more solid. Edit: If we want actual measurements (because \"peanuts are less dense than the peanut butter that you make from th...
What does being awarded "New-York Times Best Seller" mean and why does every book have it?	[ "There is one chosen each week, so there are 52 Best Seller's a year." ]	[ "It has to do with your bloodstream. When you go underwater, the nitrogen in your blood gets compacted down and dissolves. If you go to a high elevation quickly, the nitrogen escapes your blood, sorta like how fizz escapes from pop. This can lead to broken blood vessels and many horrible symptoms. This is called th...
How much does the earth's mass change over time?	[ "We lose about 3kg of hydrogen and 50g of helium each second (about 10^8 per year) due to [Jeans escape](_URL_0_). _URL_1_ We also gain 10^7 to 10^9 kg per year due to meteorites and such. _URL_2_ It balances out (to some degree). EDIT: Added a source." ]	[ "It varies, but not much individually. The problem is when everyone does it. It's kind of like why you're taught not to pick a flower from a garden when growing up. You alone, picking one flower, is not going to be noticed, it's not going to affect the plant or garden overall, but if everyone picks just 1, very s...
How does major news anchors get to locations of breaking news extremely quickly?	[ "News Anchors (presenters) are the people who typically sit behind the desk in front of the camera and report on the events from the studio. Journalists are the ones who actually report to live events as they happen. It's a combination of listening to police radio communications, social media, tippers, etc." ]	[ "They have a hand accelerator and hand brake installed in their car. [There are lots of companies that can install those kind of controls in almost any car.](_URL_0_)" ]
How can Netflix acquire the rights and permission to ship DVDs of a movie, but not acquire the rights and permission to Instant Stream it?	[ "Why indeed. What's the truth is that the digital streaming rights are negotiated completely separately to the DVD Rental rights, and movie studios see streaming as a threat to their big-ticket DVD sales, that's why hardly any new releases get authorized for streaming. Understand that Netflix WANTS to stream everyt...	[ "Wells Fargo, the company, didn't benefit much, if at all. However, Wells Fargo had monthly quotas of new accounts that their employees had to meet or they were subject to disciplinary action. Since it's quite difficult for a bank branch employee to generate interest in creating additional accounts (bank branches a...
When did the USA become the world naval power?	[ "_URL_0_ The British largely dismantled theirs following WWII, as their Empire was disintegrating. The European nations lack the political will/need to have large navies. The second largest Navy is the Russian Navy." ]	[ "Former Trident sailor here. I'd guess that 25% of the crew puked at some point, every patrol. It's noticeable. Sea sickness pills were common issue. The worst I ever saw was 35 degree rolls to each side (port and starboard) at 350ft (106.7m) deep, under a tropical storm in the Atlantic Ocean. So, yes-- on an Ohi...
Was "drunk driving" a problem when horses were the primary mode of transportation?	[ "There really wouldn't be much of a point. A well trained horse will know to avoid obstacles, not run into other horses, and even know how to take you home without any input from the rider if it's familiar enough with the rider's usual habits. Point being, with horses, yes, you can give them commands, but it's a l...	[ "Hello! This has been covered before on this sub.[ Here](_URL_0_) is the relevant section from the FAQ. [This post](_URL_1_) in particular from /u/idjet covers the topic quite well. To sum it up, the idea that clean water wasn't available in the Middle Ages and that people used beer or ale as a\"substitute\" for wa...
What, scientifically speaking, does alcohol do to your brain?	[ "Its effects are primarily due to an increase in the levels of the neurotransmitter GABA." ]	[ "We don't know the details, because it is very difficult to study because it is still an illegal drug in many places or there has not been enough time yet to legally study it." ]
Is there anything stopping another country from hacking into the systems involved with US elections and somehow influencing the outcome?	[ "Well, first and foremost there is no single system to compromise. Yeah state, and sometimes each county has its own system of doing things. This may be highly secured voting machines, or it may be paper ballots. Then each system is watched like a hawk. Both by the individuals overseeing the voting in each county, ...	[ "I'm not normally one to naysay a request for knowledge, but this is not exactly a topic that can be explained like you were five. It requires a fairly extensive level of prior knowledge and understanding just to pose that question, and any answer posted is likely to be incomplete, wrong, or misleading. Sorry, but ...
I've seen several paintings depicting how people dressed in the antebellum South. They seemed to wear heavy, European clothing, such as large dresses. Why is it that the style of clothing seems so out-of-sync with the actual warm climate?	[ "I got a really terrific answers, with pictures!, from /u/colevintage and /u/grantimatter when I asked about this during AskHistorians Fashion Week. [Did early modern and early, modern, women's clothing in the West reflect different climates?](_URL_0_) Colevintage talked about how women adapted European fashions fo...	[ "Mid to late afternoon is actually the hottest part of the day. The coldest part of the day is just after sunrise, when there hasn't been any heat from the sun for the entire night. This is also why temperatures vary by season; Long days in the summer have more hours of direct sunlight and long winter nights nights...
What exactly is the FBI trying to find in the raid on Michael Cohen's office and what are they going to do with what they find?	[ "The news that's come out about the raid indicate that the FBI is investigating campaign finance violations relating to payments made to Stormy Daniels and possibly others. That's all the detail we have that's been reported so far; the FBI doesn't usually reveal a whole lot of information until an investigation con...	[ "Karachi (largest city in Pakistan) is currently experiencing some large problems; both in crime, and politically. This is in part due to [Altaf Hussain](_URL_0_) who is the founder and leader of the [Muttahida Quami Movement](_URL_1_) - a political party in pakistan based in the city of Karachi. The problems surro...
If matter cannot be created nor destroyed, what happens at black holes? Does it simply turn to energy?	[ "Matter can be created and destroyed. \"Conservation of matter\" applies only to chemical reactions. There is, however, a conservation of mass energy. Matter which falls into a black hole changes its mass, charge, and spin by that of the particles of the matter. The black hole's \"temperature\" also increases." ]	[ "X rays do not escape from within the event horizon either. The ones we see were never inside, but emitted from near the surface. To answer your question though, no, it would be pitch black. All the photons inside would be traveling towards the singularity, none would be traveling towards your eyes." ]
In an urban neighborhood why do some streets have sidewalks, and others, even along the same street, do not?	[ "It seems like your local institution that sets these things up is just incompetent... or it could be that you're just misinterpreting it as random when really the sidewalks are placed only in areas that will receive enough foot traffic for them to be worth it. Also your description definitely makes it sound sub-ur...	[ "In many cases, the package doesn't require a signature to be dropped off. If the package isn't too valuable, it's much easier for the delivery person to leave the package at your doorstep instead of waiting for you to come to the door (if you're even home in the first place.) More expensive packages will often req...
Why does lifting weights make your muscles bigger?	[ "It's not true that muscle cells divide and more and more are made. Muscle cells are generally not made during your lifetime, but instead hypertrophy and grow in size due to the stress placed on them during activity. They'll eventually have more mitochondria for better aerobic oxidation. Muscle cells can die, but t...	[ "The thing to understand is that volume of a sound (in dB) is not an absolute constant but instead depends on how far away your eardrum is from the source of the sound; this makes sense, further things are quieter. If a speaker and headphones are emitting at the same volume, the speaker will do less damage because ...
Why is counseling for mental health issues expensive and/or difficult to get?	[ "Mental health services require trained professionals. Psychologists need a masters, psychiatrists need medical degrees. These are expensive and hard to get, so the supply of people that can fill these rolls is both limited and expensive. Just pike regular doctors that you go to for a check up. The difference here ...	[ "Most of the time the people who go to these places are either already successful or some kind of athlete. The majority of the people you are talking about already have a lot of money to finance these trips. The alternative is usually some kind of athlete like the ones you see on YouTube doing extreme sports (base ...
What is happening when my nose clogs up?	[ "The reason your nasal congestion \"never seems to end\" has more to do with the swelling and inflammation in your sinuses than with mucus production. The allergic reactions you're having cause your sinuses swell, thus blocking the airways. Blowing your nose can help remove mucus, but it does nothing to decrease th...	[ "You die. And are apparently miserable and in pain until you do. _URL_0_" ]
Is it a coincidence that bee eyes resemble honey combs?	[ "Look at bubbles. When you get a lot of bubbles together in a sink (but only 1 layer thick) you'll see that they pack into hexagons. That fundamental \"rule\" is what drives both the hexagonal packing of honeycomb cells and the compound eyes of the bees, and so many other things in nature. Many circles packed as c...	[ "Because the human mind is an expert at pattern and relationship/structure detection and recognition. That is essentially how we think. We are masters of pattern recognition, so when you glance at a word your pattern mind kicks in and you have no conscious choice but to 'decode' that pattern. (you read the word). B...
There are probes around Jupiter and Saturn. We've even investigated Pluto. So what about Neptune?	[ "[Voyager 2](_URL_1_) passed by decades ago and studied it in some detail but not as its own mission. There have been a few proposed missions (see farther down on the page) designed to study the atmosphere/weather, the rings, the moons, etc. Really it just comes down to funding for planetary science and what the c...	[ "Money and politics pretty much, NASA's budget is nothing compared to what is used to be and back then US was completing with Russia to be the first to the moon" ]
Could a lot of bees take down an elephant?	[ "The bees don't necessarily have to sting the outer portion of the animal to kill it. If we're dealing with a highly defensive form of bee (such as the Africanized Honey Bee), then you're going to have a very strong alarm response, thus causing thousands of bees to descend on the target, so many in fact that they c...	[ "It has happened in some places. Most prisons are built pretty strong, so they would hold off pretty well until the cavalry arrived. Second, why would they come do this? There isn't much honor among thieves. The new boss probably doesn't want to risk their entire operation to get the old boss out." ]
What is the difference between alzheimers and dementia, and how are they diagnosed?	[ "Dementia is a loss of brain function that occurs with certain diseases. Alzheimer's disease (AD), is one form of dementia that gradually gets worse over time. It affects memory, thinking, and behavior." ]	[ "[The Straight Dope covered this](_URL_0_). Basically, they started out as being made by two different production teams, but after a certain point, they became essentially interchangeable, but they kept both names going." ]
I always see scenes in movies of psych ward patients getting ice baths--was this ever an effective treatment and what was the rationale?	[ "It was a prescribed treatment, but it wasn't an especially effective one. Or at least not in actually treating the mental illness, it was somewhat effective in getting people to stop acting up because nobody enjoyed sitting in the ice water. The \"reasoning\" was that the mental ill were classified as either manic...	[ "It's real. The military keeps records of sniper kills, the range, the weapon used...etc. Traditionally it wasn't publicly discussed and was sort of a \"don't talk about fight club\" rule among snipers, but Hollywood has popularized the term." ]
Why does my nose run like a faucet when it's cold and windy?	[ "Now, your runny nose may not seem like rocket science, but it does involve a bit of thermodynamics. One of the main functions of the nose is to warm and humidify the air that we breathe so that when it reaches your lungs, it's nice and conditioned. And in order to do this, the nose has to add some moisture to it. ...	[ "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...
What is the aluminum-foil-looking material on spaceships, and what does it do?	[ "I think you are referring to Multi-layer insulation (MLI). It consists of several layers of thin opaque foils which are kept separate by layers of webbing or by letting the outer layers crinkle, thereby reducing the thermal conduction significantly. Therefore the only way of heat transportation left in space (si...	[ "The sugar in the honey is drawing the moisture out of the bread. Honey is a _URL_0_ which is a hygroscopic substance. _URL_1_ \"Hygroscopic substances include cellulose fibers (such as cotton and paper), sugar, caramel, honey, glycerol, ethanol, methanol, diesel fuel, sulfuric acid, methamphetamine, many fertiliz...
Did the American Founding Fathers know a lot about Islam and expect the government to handle it?	[ "I don't understand the question or what you are trying to imply about Islam being something that must be \"dealt with\"." ]	[ "This submission has been removed because it is [soapboxing](_URL_1_.), [promoting a political agenda, or moralizing](_URL_0_). We don't allow content that does these things because they are detrimental to unbiased and academic discussion of history." ]
What causes a Star to enter its Red Giant phase?	[ "When the hydrogen in the core is exhausted, the core contracts and starts fusing helium. The core burns at a hotter temperature and gives off more energy, which causes the star to expand. This energy is distributed over a larger surface area, so the surface of the star is cooler than before." ]	[ "Awesome question, you’re right that the research about this kinda sucks. If you are good at interpreting/understanding research articles then check this out, if not then I’ll cover the details below so don’t worry: _URL_0_ Generally, research of this nature is done using model organisms, in the case of this study...
Why is the Philippine peso worth about twice as much as a Japanese Yen when the Philippines is a 3rd World country while Japan is a 1st world country?	[ "Exchange rate of currencies do not equal the total value of a currency or the economy backing it. I´m going to steal my favorite metaphor in regards to this question: As a whole the Japanese Yen is more valuable than the Peso but it has been divided into smaller and more denominations. Think of it like a Pizza, Ja...	[ "The change came with the meeting between Nixon and Mao. Reading up on that meeting might be a place to start. The relationship between China (PRC) and Taiwan (ROC) is interesting. Both governments consider them to be one country. As long as the exiled-government-of-China-which-resides-in-Taiwan continued (and cont...
Will all galaxies eventually be sucked in to their black hole centers?	[ "contrary to popular belief black holes are not vacuum cleaners. If you are in a stable orbit around a black hole you shall remain in a stable orbit around a black hole. The vast majority of the galaxy is in a stable orbit around our central black hole." ]	[ "Your question may not phrased that clearly, but if I understand your question to be whether, in a periodic universe (like the surface of a sphere) matter's gravitational field \"wraps around the universe\" and tugs back on itself, then the answer is \"yes\". However matter tugs on itself equally from all direction...
Why are the lyrics "joy to the world! The Lord is come!" Instead of "the Lord has come?"	[ "It's simply an archaic english form of the phrase you offered." ]	[ "Because we count the hours that are, not the hours that are not. The original 12-hour clock of the Babylonians (and the Romans and the Greeks) counted the number of hours during the day, and the number of hours during the night. They divided the day into 12 periods, and called each one an hour. There was the f...
How do you lose memories when you get older?	[ "The basic ELI5 for this is simple That every time you remember something, you´re not remembering the original memory, but the last time you remembered the memory, so the memory deforms with time. This allows memories to change with time, be forgotten and even distorted with external feedback (see the Mandela effec...	[ "I think we develop a \"been there, done that\" mentality in ways. I can not watch cartoons now. No matter what the topic. The irony is I just can't pay attention to cartoons." ]
What does it mean when people describe the magnet in an MRI as "100,000 times (or so) stronger than earth's magnetic field?" Certainly we couldn't repel all of the solar wind hitting earth (many times over) with one MRI machine?	[ "That sort of phrase describes the strength of the magnetic field inside the bore at its peak. The magnetic field outside the magnet bore is significantly less, and drops off fairly quickly (especially in the case of shielded magnets)." ]	[ "More plausible than a dyson sphere is a dyson swarm or a dyson ring. In a sphere the poles are not subject to centrifugal force to counter the gravitational pull so the structure will suffer extreme tension. A dyson ring or rings can be put around a star at diferent inclinations and they will have the advantage of...
I have to wear very strong glasses, would it be at all possible to create something that counteracted my poor vision and looked perfectly crisp when I looked at it with the naked eye?	[ "I'm gonna try and find this link, but I definitely saw something (probably in IEEE Spectrum) about exactly this: a printing pattern that looked normal to people with terrible eyesight EDIT: I did a quick google, and I can't find this. I swear it exists, but I can't find it. Consider my comment invalid." ]	[ "Well, obviously you already know how you can overlay graphics on top of a still image. Creating an arrow or label on top of a photo isn't so hard, from that perspective. It's the movement and real-time camera sync that's hard. So how do you do it when the image moves and changes constantly? Well, the cameras posit...
How do apps keep up with updates in OS(android,iOS etc.)	[ "Well often times they don't bother, but in general os updates are announced in advance and are fairly well documented so devs can get pre-release versions to test their app and keep up. OS updates aren't released as frequently - minor ones only a few times a year and the big ones less so - often times about once ...	[ "Satellites are on a set orbit. The scientists put the satellite into that orbit to begin with, so they know when and where in space the satellite is going to be. When they launch a new satellite, they just calculate the appropriate trajectory and launch time to get the new satellite into space without hitting the ...
Is there a theoretical maximum for a how reflective a surface can be?	[ "/u/isison is close, though in the optical coating industry these are usually referred to as dielectric mirrors, not photonic mirrors. The simplest type is commonly called a \"quarter wave stack\". By stacking quarter wavelength [optical] thicknesses of material, you can achieve arbitrarily good reflection (as clos...	[ "I fear the graph is still up to date - no new records since them. JT-60U still has the highest triple product. ITER should beat it, but not before 2027. It should release 10 times more fusion power than necessary input power when run with DT plasma (2035+), a huge milestone. After that it is \"just\" making a viab...
Why is the sound of a baby crying incredibly annoying?	[ "It's an evolutionary trait. Feeling annoyed by a baby crying makes it so you are going to try and help the baby stop crying (or try to kill it, like some people). It's also why a heavy sleeper may be woken easily by something like a baby crying." ]	[ "Turn off the motion smoothing function. It drives me nuts too. _URL_0_" ]
How did the original Native Hawaiians find Hawaii in the first place?	[ "There is actually a certain degree of confusion on this. Hawaii was settled by Polynesians from the Marquesas sometime in the first millennium CE--the exact date isn't known because the direct evidence and proxies don't quite match up. Now, by and large the Polynesian/Oceanic method of discovering new islands is w...	[ "If you're really asking 'why', no one knows. Luck. Chance. Possibly something else entirely. It's a deeply philosophical question. If you're asking how, tools. Tools made the difference. Humans were lucky enough to learn to use tools, to develop fire. That was what pushed us into the dominant position." ]
Book recommendation on ancient and medieval Japan?	[ "One of the most fascinating aspects of Japanese history for me is in the food history. Japan has, and still does have a rich history of food culture to the point that it [washoku] is a considered a UNESCO Intangible Cultural Heritage. Through the food consumed, you can certainly learn a lot of about the day to day...	[ "Check out Yuri Slezkine,[ Arctic Mirrors: Russia and the Small Peoples of the North](_URL_0_)" ]
Why is lobbying legal?	[ "Let me answer that question with another question: what do you think \"lobbying\" is?" ]	[ "Explain it like you're five? So somebody like an American version of Justin Bieber isn't swept into office because of his fan base." ]
How exactly did lowering of the graphite parts of the control rods on Chernobyl's RBMK plant result in reactivity surge?	[ "Here's a great video explaining it: _URL_0_ Long story short, there were graphite rods attached to the bottoms of the control rods. Fully pulled out, the graphite rods didn't reach the bottom of the reactor. With the water boiled off, the bottom of the reactor became ~~nearly~~ supercritical. When they scrammed th...	[ "One of my personal favorite castles is the Crusader fortress of [Krak de Chevaliers](_URL_14_). It was never taken by force, was eventually only captured by treachery. It is an excellent example of the medieval European use of castle construction to defend and consolidate contested territory. Some interesting defe...
How evenly matched were Roman gladiatorial fights?	[ "Well they were pretty well balanced, which can be said pretty safely because otherwise the Romans didn't enjoy it! Gladiatorial fights, when they became commercialized for entertainment, were just that. Entertainment. And just like in our sports while it's only so fun to watch a great team beat up a bad one, the R...	[ "Remember that many ancient accounts exaggerate numbers, and many are not truly reliable. With respect to the Second Punic War, however, it is accepted that the armies were very large. On the demographic and economic impact of the war in Italy, see _URL_1_." ]
Why do we say we get on a train but get in a cab?	[ "We use \"on\" for any vehicle where you can walk around after boarding, \"in\" for a smaller vehicle that you enter but are then unable to walk around. On a bus, but in a car. On an airliner, but in a fighter plane." ]	[ "I recommend reading 'At Home' by Bill Bryson. He goes through this in detail. From what I recall, houses used to be just one big room, animals, people, servants all in the one place. Over the centuries, people got bette at building walls, so they built these buildings higher - this showed your wealth and was much ...
Why is America's Income Inequality so High?	[ "Its because the US has a lot of extremely wealthy people. Its not because the poor are so poor, its just that the rich are so rich. _URL_0_ Notice how many of the people on this list are from the US?" ]	[ "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 would happen if two super massive black holes were to collide or merge together?	[ "You'd get one big black hole with mass equal to the sum of the masses of the merging black holes. (Note, though, that they would have to actively collide; you could easily wind up with two black holes orbiting each other until they lose enough energy through gravitational waves to merge.)" ]	[ "So, you don't actually observe the astronaut crossing the event horizon. What happens, from your frame of reference, is that the astronaut gets more and more time dilated, and moves slower and slower as they approach the event horizon. This means that the light gets dimmer and dimmer, because the time between each...
Does the gas station I fill up at really matter?	[ "Nearly all gasoline comes from the same source for a given region. Some \"premium\" brands will add compounds to the gasoline at their filling stations that they claim improve performance or clean out the fuel lines. If you believe those claims then it could make a difference to buy gasoline with those additives....	[ "Both are unleaded. The difference is the octane rating, which affects how quickly is burns. Engines with a higher compression ratio need premium to prevent knocking." ]
Measles is thought to 'reset' the immune system's memory. Do victims need to re-get childhood vaccinations, e.g. chickenpox? And if we could control it, is there some good purpose to which medical science could put this 'ability' of the measles virus?	[ "There are already lots of immunosuppressive drugs available, which can - compared to measles or HIV suppress parts selectively. Ciclosporin and similar drugs are much more effective and can be switched off easily (stop taking it), something that cannot be said about a lot of viruses. To avoid gvhd and similar unwa...	[ "Machine learning is a discipline that develops algorithms to get computers (aka thinking machines) to learn without having to be explicitly taught. It works very similar to the way our brains work. When you are born, your brain is a blank slate, and is hard wired to detect common patterns and associations. You gue...
How does an Independent platform for President work?	[ "Political parties are not an official part of the US government. People appear on the ballot representing themselves, not necessarily representing a party. Anyone who meets the requirements to be president can file paperwork to run with the Federal Election Commission and can file in each state to appear on the ba...	[ "Some amount of money paid to each citizen no strings, as an alternative to social security. I think the numbers pay out to similar costs. And the benefits are supposed to be substantial. It's already in practice at a small scale in Alaska." ]
Why are weeds not considered regular plants?	[ "A weed is just a wild plant we don't want. \"wild plant\" is just one that a person hasn't planted. So they are considered plants, they're just unwanted and wild, so we use \"weed\" to refer to them." ]	[ "Taxes... If the government had a way of guaranteeing that they would get their cut off the money being made then it would be legal." ]
Why do Muslims get angry when Muhammad depicted, but not when Jesus, Moses, Abraham, Isac, etc are, despite all of them being being prophets of God in the faith of Islam like that pamphlet told me?	[ "I was once told by a Muslim that Mohammed requested that no images be made of him as he didn't want to be worshiped as an idol. Interestingly, the vast majority of Middle Eastern art I've seen is abstract, geometrical or of something like flowers. They don't tend to go in for portraits as a rule. Source: I live in...	[ "The state of Utah was essentially founded by Mormons. The group felt persecuted on the east coast and began what they describe as a pilgrimage to the promised land, where they could live, grow, and worship in their own way. Their final point of rest was Salt Lake, Utah, a relatively nice place to do all of those t...
If there was a house at the same level as the ISS, but is connected rigidly to the earth and moved alongside it, would the house have earth-like gravity?	[ "So you're imagining something like a giant tower raising the house to an altitude of 400km. Doing some math, gravity at this altitude is 8.69 m/s^(2). That's measurably lower than on the surface and you may be able to realize if you let something fall and use a chronometer to see how much it takes to hit the groun...	[ "Put a slinky in a long glass tube and fix one end of the slinky to one end of the tube. Now lay the tube on your desk. The slinky is all curled up . Next, stand the tube upright. One end of the slinky is fixed to the top of the tube and the bottom of the slinky dangles down. What if you held the tube at an angle.....
Can a chemical immediately affect the body? i.e. In movies people are drugged and they nod off instantly. Is this possible?	[ "As others have said, nitrous oxide (dental anesthetic) and morphine will conk you out like magic. However, the \"chloroform rag\" trope is bullshit. Chloroform will make you a little drowsy after smelling it for a while but it's not the insta-KO the movies make it out to be. Source: I'm a synthetic chemist and use...	[ "All modern digital computers can only perform simple manipulations on binary numbers. However, because those simple operations are done in the hardware, they are blazingly fast, micro- or nano-seconds. So if you want to do more complex mathematical operations, you have to write programs to do it by running lots of...
Would I die without sleep? Why or why not?	[ "Sleep cannot be stopped. After a maximum of about 11 days of being awake you will start to experience 'micro-sleeps'. Basically your brain shuts down for a fraction of a second to a minute. It doesn't matter what you're doing this will happen. Consider these to be like a blackout. You don't know you're doing them ...	[ "This video created by Vsauce 3 (Jake Roper) does a very good job explaining this: _URL_1_ I hope this answers your question. He also did another video on a simmilar line of - could you survive: _URL_0_" ]
Why can't the Mexican military bring the drug cartels under control?	[ "Because the drug cartels pay them more money than the government and commit acts of violence towards them and their family if they don’t obey." ]	[ "One thing to point out is the terrain. Iraq is in the populous parts of the country pretty flat, with a semi good road network across the country making it easy to move people around, and larger cities and towns to organize around. Afghanistan is some of the most inhospitable terrain on earth. With little nation...
What is the widely accepted hypothesis as to how the Egyptian pyramids were built?	[ "Traditionally there's been no consensus, because no proposed method met all the criteria needed for it to be accepted as consensus. These included, utilizing only technologies the Egyptians were known to have, could be built in the time period allotted for that pyramid, etc. However, there is now a proposed meth...	[ "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 aren't cheap cars made to look expensive?	[ "You ever read about the Star-Bellied Sneetches? When the non-star bellied sneetches went through the star-on machine, the star-bellied sneetches paid even more to go through a star-off machine to sustain their difference (and thus, their superiority). If you make cheap cars look like expensive cars, people will ...	[ "Becsuse all tux's basically look the same, just different sizes and are a basic loose fit. Easy for many men to wear the same thing. But theres a bajillion styles of wedding dresses and different styles for different shapes and they're usually fitted. Odds of finding a generic sized dress in a style you like that ...
Is perpetual motion achievable in the vacuum of space?	[ "Even the vacuum of space isn't a complete vacuum. There are still dust particles, there is still friction, the density of particles is exceptionally low so friction is practically zero, but something in space slowly loses energy to friction. It will also be impacted by the radiation pressure of nearby stars. Perpe...	[ "Quoting [Wikipedia](_URL_0_) (a bit naughty, but it's a nice way to express what I think): > The proposed theory is inconsistent with quantum mechanics and critics have ruled it out on those grounds. Which is essentially saying what you pointed out, yes. If what they're doing is as easy as it sounds - just runnin...
How could I require to filter out all visible light for rats from a low light screen?	[ "I have some trouble understanding the question. If I understand correctly, this is a simple issue of blocking the correct spectral range. You can achieve this by combining color glass filters, which you can get in pretty much any price range, shape and flavor, e.g. [here](_URL_0_). If the remaining light is too l...	[ "I had to consult his Nobel prize lecture to get some of the experimental details. It is well worth a read. _URL_0_ Lenard seems to have worked with electrons with energies around 30 keV (that is, accelerated by 30000 volts). Electrons of these energies will be fairly efficiently absorbed by materials on a length s...
How do police trace my location via my phone call, if my GPS is turned off?	[ "Police were able to trace phone calls before GPS. Look at any old movie prior to 2000. For cell phones, any time you make a call, the signal from your phone goes to a local cellular tower. Calls to that tower are logged and can serve to form a rough estimate of your general location. By using multiple cellular tow...	[ "It costs money by private cell providers to implement that system,. And there's no profit to be made. The only reason they would do it is if the law demanded it and the gov was going to pay to costs of it." ]
why do some people (me) get afraid and have difficulty sleeping alone thinking someone's there even though we are in the safe zone of out house? Also, why do we fill those dark spots in the corner of our vision with anything scary or dangerous?	[ "Probably has something to do with our natural instincts and being aware at night. In the past if you slept alone or away from other humans, you're more likely to get picked off since humans are pack animals." ]	[ "Basically, we have 2 types of light detectors in our eyes, ones for colour and ones for black and white. The ones that detect colour are mostly concentrated around the centre of the eye, while the one that see black and white and more present around the edges. Thus, in the dark, aka lack of colour, the ones which ...
Are modern respirator masks (ie for spray painting) as effective as military gas masks?	[ "No they are designed for specific threats. Both use a combination of filters and activated charcoal for absorption of the agents but beyond a superficial similarity they are very different. As it is war gases including mustard, dirty mustard, Lewisite, and all the nerve gases can be absorbed across the skin in fat...	[ "Small models. If you go to Mount Rushmore or the Crazy Horse memorial they have the scale model on display that the artists used for planning purposes. These models are perfect replicas of what's going to get built, but at a small scale that you can actually walk around. By taking measurements off these models and...
If a glass jar free falls and shatters on the floor, can any shards fly higher than the altitude from which the jar fell?	[ "There's no physical law forbidding it, but the center of mass of the shards will never be higher than the center of mass of the original object at the drop point.* *Assuming a regular system in which potential energy constitutes the entire available energy (e.g., no explosive chemical reactions, etc.)." ]	[ "Your whole high school is in the gym for an assembly. The presentation comes to an end and everyone needs to leave all at once. If you never open the doors, people will never leave. If you open one door, how long will it take for everyone to leave? If you open all the doors, how long will it take for everyone t...
I've heard the internet weighs the same as a strawberry. How can data, like text saved on a hard drive, weigh anything at all?	[ "Basically, [information has energy](_URL_0_). Note that information in the scientific sense isn't technically the same as information in the normal layman sense, but it's kind of similar (for the purposes of the calculation, we're assuming they're equivalent). So once you figure out approximately [how much data is...	[ "Google is faster, because Google has already done all the searching ahead of time, and built an index. Imagine you have a thousand page book, and I ask you to tell me every page with the word \"cat\" on it. The way your computer does the search is by flipping through each page one by one looking for the word \"cat...
Why do big factories empty there waste in lakes, rivers, oceans etc. instead of a big hole?	[ "That is no better and more expensive. You have create that big hole, to start. Then it seeps into the soil until it reaches the water table where it does pretty much the same damage as dumping it in the river a few hundred metres away." ]	[ "Your question is like: > Why do people keep telling me to take a pill my doctor prescribes when in ye olden days people didn't have access to the same pills? Clean water is way easier to get now than it was then. Since you have access to clean water you should use it. In the same way, getting a doctor to prescri...
If a new word is invented in [Language A], who decides what it translates to in other languages (example: computer, in English translates to: equipo/Spanish, ordinateur/French, računalo/Bosnian... etc.)?	[ "It depends. Some places have an active language policy whereby there's a board of people who come up with or approve neologisms ('new words') like France and its Académie française and Quebec's Office québécois de la langue française. English doesn't have this, so we tend to take the words of new concepts from wha...	[ "Lots of trial and error. I pick up a red apple, point to it and say \"bagu\". What did I mean? Apple? Round? Red? Food? Fruit? Sweet? Juicy? You really don't know. Until I pick up another thing..let's say a red ballon \"bagu!\". Hm probably not apple, not food, not fruit not sweet, not juicy. But could still be...
Why do dogs go alone when they feel really sick or near to die?	[ "Actually, a lot of animals go off somewhere to be alone when they feel sick. I think, though I'm not exactly sure, that it has to do with feeling vulnerable. When an animal is sick, it is weak and cannot protect itself, so it goes somewhere quiet / secluded / safe where it cannot be bothered by other animals." ]	[ "Captains deliberately going down with their ship is rare. There is a big difference of \"go down with the ship\" and \"being the last man to leave\". The first is more a military thing, based on honor. Some Japanese captains did this in World War 2. Last man to leave is entirely practical, to show that the captai...
Since North Korea has a history of military provocation and human rights violations, why don't countries sanction it completely?	[ "As always, international politics are complicated. Here are a few things to take into consideration: - Humanitarian issues. People in North Korea starve to death every day. A complete blockade would only make this worse. - NK isn't without allies. Most prominently, China is an ally of theirs, and China is a major...	[ "Because the technology was in it's infancy in 2014. Deep packet inspection was just being pioneered by the Chinese. Once it became possible to record your every website click the first ones to do it were the NSA. But now that shit's commercial and cheap enough and intelligent enough to make life really suck if y...
Why didn't the Russians discover the New World sooner, since they're so close to Alaska, or vice versa?	[ "You seem to be a bit confused about Russia's history. For most of Russian history, \"Russia\" was considered to be mainly of territory to the west of the Ural Mountains. No one beside \"barbarian tribes\" lived on the other side in Siberia. It was only in the 1700s when Vitus Bering made the first expedition to ma...	[ "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 does coffee not hydrate you, even though it's main component is water?	[ "It does hydrate you, though less than non-caffeinated beverages. There is some diuretic (makes you pee) effect from the caffeine, but if anything the water component of the coffee and the impact of the caffeine balance each other out." ]	[ "Hot air carries more moisture than cold air. When hot air full of moisture approaches a window (or any cold surface), the air cools and the water in the air condenses onto the surface. To counter this, buildings either have air vents next to the windows (similar to a windshield in a car) or have double/triple pane...
How did doctors find out which parts of the brain control different things (like individual emotions, pain, happiness, all 5 senses, etc etc)	[ "Most of the original discoveries were made by observing and documenting patients who had a brain injury which disabled or damaged a certain part of the brain and working out by the deficits in their perception or action, what that part was responsible for (for example google \"Phineas Gage\" if you haven't already...	[ "We know what the various structures within an eyeball do- the rods, cones, and so on. Some structures have to do with color, or depth perception, or other visual elements. By dissection of other species eyeballs and seeing the similarities and differences in the numbers and types of structures scientists are abl...
How did NASA plot Voyager's course to avoid objects that might affect its path through our solar system?	[ "They used the patched conics method. With this you basically reduce the equation to a 2 body equation. You are orbiting the earth, then you are orbiting the sun, then you are orbiting jupiter, then you are orbiting the sun again, then saturn... Of course this like any other simplification is going to introduce er...	[ "Very careful simulation based on testing data. Engineers have experimentally gathered data about all the different materials used to make the telescope. This data includes failure points given applied loads, vibrational frequencies, etc. They can use this along with a computational model of the sattelite to predic...
what the deal is with the rich not paying enough taxes. I hear a lot of talk about it on Reddit and I want the facts. I want to understand the problem based on the numbers.	[ "Simply put, many rich people make money by earning things like dividends and interest, instead of traditional income. These are called \"Capital gains\" and they are taxed at a lower rate than \"income\". In numbers: Income tax ranges from 10% to 35% Long term capital gains is 15% no matter what." ]	[ "How do we continue to slowly get smaller and smaller architecture in processors? I guess I am trying to understand what limits the shrinking of architexture. Essentially, why cant architexture rapidly decrease in size faster than Moores law predicted? Sorry, if this is a super complicated answer, I just always hav...
Why do we rub our eyes when we're tired?	[ "As a man that has had every eye problem under the sun. I would say it's to help to meimobian glands excrete more oil to stop the moisture evaporating as quickly, which happens when we're tired. I'll happily be proven wrong though.." ]	[ "Nobody knows why or even if it works, but that and variations of it are common practise in many countries. Cultural memes are like that, they spread, even if they don't have any real function." ]
Sunday Digest \| Interesting & Overlooked Posts \| June 29, 2015–July 05, 2015	[ "OK, taking a brief break from AMA duties, here is my weekly rundown! /u/keyilan on [\"For historians of Ancient China, how does the PRC government influence current historiography?\"](_URL_1_) /u/lost_scribe on [\"Where did the trope of barbarians disdaining \"decadent\" Roman/Greek/fantasy cultures come from?\"](...	[ "The US Department of Energy published a study [pdf:[1]] in 2008, showing a decrease of one-half of one percent (0.5%) daytime energy usage during the extended DST hours established in 2005. Conversely, most of Indiana did not observe DST until 2006; when they switched, the result appeared to be an increase in ener...
What is under your average downtown city street?	[ "Pretty much. [Here's an example of what it looks like in New York City](_URL_0_) - quite possibly one of the most built-up underground of American cities." ]	[ "It depends completely on the municipal or state agency responsible for engineering the roads. In many areas there is no actual standard and its just done for aesthetic reasons, aka it sounds cool. Source: I work in public safety and deal with mapping on a daily basis" ]
why does alcohol make you feel warm?	[ "Heat is produced when parts of your body are functioning. When you move muscles, when your stomach digests stuff, when your liver processes stuff. All of this takes energy. As the energy is used heat is produced. When you drink alcohol your liver goes into overdrive to metabolize the alcohol. This produces a lot o...	[ "Space blanket's work by providing a reflective surface. A fair amount of heat that escapes ones body is due to radiative processes (as opposed to conduction [touching], or convection [breeze]). By wrapping you in the mylar blanket, any heat that is radiated from your body just bounces back! In the meantime, it als...
How has Banksy managed to remain so anonymous?	[ "The short answer is that most everyone appreciates that his anonymity is a part of the wonder of Banksy, including Banksy. Banksy isn't making art to be famous, just to be Banksy. People love that, and it gets reinforced. If Banksy came out with a line of laundry detergent or a book about how to make Banksy style...	[ "you get over the novelty. thats been my experience. there is this guy at work who i used to think was a gargoyle at first but now i don't notice that he's a gargoyle. same thing for stunningly attractive people. you get over it." ]
Why is it that alcohol in combination with paracetamol can cause liver damage due to glutathione issues but alcohol on its own does not?	[ "The issue is a highly toxic metabolite of paracetamol (acetaminophen) known as NAPQI. Normally, only a small amount of the drug goes down the pathway to NAPQI, and the amount that does is harmlessly conjugated to glutathione. It takes a sizeable dose to get enough NAPQI to run out of glutathione and start getting ...	[ "It's a process called photobleaching. Light comes into your eye and hits the back of the eye (the retina). The retina then, through a somewhat complicated process, sends signals to the brain (this is an oversimplification). There is a shield that protects your retinas from getting too much light called the retina...
Why the aging process is altered by traveling at the speed of light.	[ "It's not. It's a misunderstanding. As you approach the speed of light time slows down more and more for you....... from the point of view of an outside observer. As far as you're concerned you age normally." ]	[ "Another possible answer that has Ben discussed is this: When you are 5, and have a birthday party, you haven't had many birthdays and so your brain is working very hard to remember, absorb, and understand, all of the workings of a birthday. This is why time 'feels' long when we are younger, our brains notepad is w...
Can meteor impacts crack tectonic plates?	[ "The meteor that hit the Yukatan Peninsula went all the way to the mantle, bringing up pieced of peridotite up in the rebound. It shattered it massively. It all depends on the size of the meteor." ]	[ "Not enough energy to. It's like lighting a match in a snow storm and expecting it to melt everything. Sure, the match is hot, but theres a lot more cold than there is hot." ]
If you move can you take your homing pigeons with you, or do they always return to your old house?	[ "If you don't let your homing pigeons out, they eventually identify where they currently are as their 'home'." ]	[ "Hi, you may be interested in a couple of previous threads * [Modern cities bristle with parking lots used by commuters, businesses, and residents. Before the automobile, how did urban centres like London, Paris, and New York \"park\" their horses, carriages, and buggies when not in use?](_URL_0_) featuring /u/henr...
How has the average American's diet changed over time?	[ "Michael Pollan's \"Omnivore's Dilemma\" and \"In Defense of Food\" looks at how nutrition (and the concept of nutrition) has changed over the last 50-60 years." ]	[ "This is a fascinating question! I am also curious in when and how this happened. I imagine it was state by state, so perhaps not all at once? Or was it only after the 19th amendment was passed?" ]
Railroad crossings don't seem to have sensors or something to warn conductors of a vehicle/object stuck on the track, why?	[ "Small subway style trains might be able to stop within a .25 mile or so depending on their speed. A large freight train with hundreds of cars, some of of which maybe be carrying tankers of flammable or hazardous chemicals can not stop quickly. It can easily take a mile or more for them to safely stop. An emergency...	[ "This has essentially been answered by the preceding comments, but what hasn't been contributed is this: _URL_0_. Muster and enrollment records, transfer lists, honours lists, etc, for the period of 1730 through 1898. Worth having, OP, if you're writing or researching the topic academically. To succinctly summarise...
How did Germany gain so much military power while under the Weimar Republic?	[ "They didn't. They gained it under the Third Reich." ]	[ "In a nutshell, the company used creative accounting measures to use the chance of future profitability to provide cash immediately. The best example is the building of various power plants, which would take years of construction. However, they could immediately offset the cost by booking future profits, thereby se...
Why are our dominant hands not considerably more muscular than our other hand?	[ "I know a lot of tennis players with massive right hands and skinny lefts. I guess it depends a lot on how you use them. The average guy probably uses his left and right a close amount without even realizing it" ]	[ "Its to do with the connections between your visual cortex and your motor cortex. To use a computer analogy, its like the graphics card working fine but a fault in the cable that causes distorted images on your computer monitor. You have to translate the visual image into precise muscle movements that will draw the...

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