Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
If the English longbow was so feared by the other great european powers, why didn't they use longbows also?	[ "The longbow required years of practice, as well as yew trees for the making. Many monarchs did not want their people to be skilled archers with armor piercing weapons readily available. So the culture of the longbow was not readily transported to a different place. However, English archers did hire out as mercenar...	[ "Briefly, because the [pair potential](_URL_0_) between bonded atoms is asymmetric. When atoms are bonded, they sit at a certain equilibrium distance where electrostatic attraction balances repulsion from the Exclusion Principle. The balance can be thought of as a potential energy well with an approximately parabo...
How and why can the color of individuals eye’s change throughout the course of a day?	[ "There are no actual blue or green pigments in anybody's eyes. The color comes about from the structure of the pigments inside of there and how the light gets scattered through it. The only pigment in your eye is melanin, the same thing that changes the color of your skin. depending on your eye structure the light ...	[ "Apparently this is linked to circulation/temperature of the inner layer of the cornea. _URL_0_" ]
How can countries like US,Russia,France sell fighter jets and warships to other countries without worrying of it being used against them?	[ "In addition to what others have said nations often sell export variants of hardware. These versions are usually less capable than what is in the selling nations' arsenals. When the US sells planes they will usually have a less capable avionics and radar systems. US tanks are sold with export armor that is less cap...	[ "The most common business model is just to get as many eyes looking at your site as possible, for whatever reason, and then sell ad-space. Advertisers will pay for people just looking at their adverts, but they'll pay more if people click on those adverts, and they'll pay even more if you can use your knowledge abo...
Is it possible to take a photograph in the radio portion of the electromagnetic spectrum?	[ "This is essentially what radio telescopes do. Obviously it's not the same technology as with optical photography. The top few images [here](_URL_2_) are the Milky Way at different radio frequencies." ]	[ "You ever see an old movie or slideshow projector? Shine a light through a tiny picture then through a lens and it projects this massive image on the screen from a tiny picture. Turns out we can do that in reverse. Shine a light through a big picture and lens and we can project a tiny image on a tiny screen. Sc...
Why is Carfax, a commercially owned company, allowed to collect all kinds of information on our cars, and sell it to others for money?	[ "Every bit of information that is on Carfax is either: 1) Not information that qualifies for privacy protection 2) Information that is already public - this includes police records 3) Information that, somewhere down the line, you agreed to allow another company to sell, likely in a very long sale contract, onl...	[ "Yes. Imagine you break a stick and then put pieces back together with duct tape. Is repaired stick same as new? Of course not. It's the same with auto parts. They are prepared to deform in specific ways during collision but they only can deform once. During that process internal bonds between atoms inside part are...
If the barrels of guns weren't rifled, would there be more or less ricochet?	[ "Up close it wouldn’t make a difference. From further distances though the bullet from the non rifled barrel would slow down sooner, potentially begin to tumble. Same bullet in both guns but less speed = less kinetic energy = less ricochet. The further from your target the greater the difference would become." ]	[ "It's inaccurate to say that crumple zones are always safer than rigid frames -- it depends very much based on the type of collision and the position of the passengers. In a racecar, the type of collision and the position of the passenger is pretty consistent -- the driver is strapped in like an astronaut. It's bee...
How do we measure the mass of remote objects in space?	[ "If there's another object in orbit around it, like a planet with a satellite, then it's trivial. The [orbital period](_URL_0_) depends only on the semi-major axis of the orbit and the mass of the central body." ]	[ "Their workout equipment is designed to work around the fact that they're in microgravity. They don't just use free weights. Imagine something like a bowflex. It still provides the same exercise, even though there's no weight." ]
How exactly do Laser Thermometers work?	[ "They measure the level of infrared radiation coming from whatever they're pointing at. The laser is only there so you know what you're aiming at, and has nothing to do with actually reading the temperature." ]	[ "There’s a bunch of people in your tongue, and they have a weird name. They call themselves TRPM8, and they’re proteins. They specifically tell your tongue when it’s really really cold. Mint gums or candy have a chemical, called methonal, that tells them that they’re REALLY cold, and in turn, your tongue thinks yo...
Why are moods so random?	[ "You'll get some great - I hope! - answers here. I can't speak effectively to what those answers are, but I do know the subreddit /r/psychology might have some people who can really get into the nitty-gritty for you. They do ask that you avoid seeking advice there, but then so do we over here!" ]	[ "From the exact same XKCD article that you linked: > (Climates can be hard to predict—for example, in our world, Somalia and French Guiana both sit on the equator, at the eastern coast of a continent, and seem like they should both receive a tropical sea breeze. But coastal French Guiana is dense rain forest while...
Why do churches and religious groups get a Tax Break, even when churches and religious groups were obviously created to get the Tax Break?	[ "> when churches and religious groups were obviously created to get the Tax Break? How so? Churches and religious groups existed before the US did, so they can't have been created to get US tax breaks. They were created because people share certain religious beliefs. Simple as that." ]	[ "First off, weekday number is arbitrary. Weeks don't evenly divide months or years, so numbering the days of the week is just a convenience. There is a lot of tradition coming from the Jewish Torah (and its inclusion in the Christian Bible) about the numbering of the days of the week based in its depiction of the s...
Is it possible to use dirty water for flushing toilets rather than fresh water? What would be the complications in initiating such a task?	[ "It is possible, but only worth doing when you really need to save water. Systems that do this are commonly referred to as grey water systems. They gather the runoff from sinks, showers etc and pass it through a basic filter, at which point the water is called gray water. Gray water is then used for flushing toilet...	[ "Energy systems engineer here: they do. This happens all the time in Europe, and increasingly globally with infrastructure constantly expanding. My favourite example is that the French pay the swiss to take the electricity they can't use at night ( due to all the nuclear that need to constantly produce power). Th...
Sometimes when I'm about to fall asleep, I feel an almost electric like shock that jolts me awake.	[ "I have a similar sleeping condition where as I am about to fall asleep i hear a loud bang or crash sound. Sometimes it can be someone yelling very loud for just a brief second, or a gunshot or something similar that jerks me awake. It all takes place in my brain." ]	[ "There are a few factors at work here : Moſt chairs are deſigned to ſit at about knee height ; they generally ſupport your back, and more importantly, your butt and legs. Toilets are uſually lower, and they are made with a large hole in the middle, into which you ſink a little. This lower height, lack of ſupport,...
Why do some pore blockages become blackheads while others become zits?	[ "Both are blocked pores. Blackheads are open to the air so the blockage turns darker. Pimples and whiteheads are enclosed by skin so they stay whitish." ]	[ "> why do victims determine whether a criminal act occurred? They don't. Pressing charges is the victim asking the Prosecutor to bring charges. But the police could do that themselves if they think a crime has occurred; murder for example isn't likely to have the victim pressing charges." ]
Back during WW1 did Germany call the Canadians, France, etc the allies or did they call us something else?	[ "The Entente, due to the Triple Entente and Entente Cordiale." ]	[ "Jean François likely came from the French shanty Jean François de Nantes, which had a similar tune. There are similarities in the lyrics of the two songs: the French song has oué, oué, oué instead of away ah-yah, and at least one version of Jean François de Nantes uses the word terrien-landlubber-which m...
Why is the keyboard organized in the way that it is?	[ "also you can spell \"typewriter\" using only the top row of keys" ]	[ "Kind of like if you're looking through some legos for a number of different parts, you usually come across one that you need so your search goes quickly until there's one last part you need. It might take you awhile to find that last specific part. That explanation is probably wrong but that's what I would say to...
What's the best way to measure how many grams of powder are inside a small container?	[ "Are you planning on using all of it? If so, weigh the bottle now, empty it out into your reaction vessel, rinse it out with some of the solvent you're going to use, dry it, and weigh it again to figure out how much was in there. If you're looking for some way to eyeball the weight of a random powder, you're prett...	[ "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...
Why isn't everyone ambidextrous?	[ "I would personally give my left arm to be ambidextrous." ]	[ "This has been done. He even won an [Ig Nobel Prize](_URL_0_). There was no difference between his hands." ]
Why are there Nazis in the USA?	[ "Many of the posts here are very good, but, one thing that most people don't realize is that there were plenty of German sympathizers widely present prior to the U.S's entry into World War II. There were communities near me that were devoted to ex-pat Germans who totally supported what they was going on in the 'old...	[ "If you have Netflix there's a very good documentary titled \"the world without US\" It explains your exact question." ]
Are we able to observe a delay of 32 ms when using a mouse and looking at the screen/cursor?	[ "Yes. I used to work for Atari Games. Kids reaction times are so fast that they can sense a lag greater than or equal to two fields. That's 33.33 ms. So all fighting games were designed to read buttons and joysticks on one frame and change the motion of the character in the next frame. Anything slower was panned by...	[ "Music isn't a competition between band mates, but racing between racers is. Fast reaction to the start gun is part of that competition. Motorsport usually does use a form of countdown, but reaction time is still important, vitally so in the case of drag racing." ]
why aren't we funding solar power?	[ "People with the coal and oil want to keep making money from the coal and oil. They go to Congress and say how it is necessary for our economy and if we don't keep supporting it, thousands will lose jobs, whether or not it is true. Also, most of our infrastructure is already set up for fossil fuel use, the power pl...	[ "[Rates of myopia are skyrocketing](_URL_1_). Current research shows one possible reason behind the rise in rates of myopia (short-sightedness) since the industrial revolution is [lack of bright sunlight](_URL_0_) during eye development, but this is very recent and as such has not been conclusively proven." ]
How do computer programmers take the computer (read: mouse) courser into account for the programs? Do they have to write the code that mirrors the mouse movement or do they just create the interactive background?	[ "For most programs, the operating system/window manager draws the cursor and a program doesn't have to worry about that. A program will get notifications like \"the mouse has moved to (x, y)\" and can use that to know where the mouse currently is to do things like highlighting. For games with custom cursors, they m...	[ "If you lived a few thousand years ago, you could make a good map of the constellations of the zodiac piece-by-piece at night. Then, at sunrise or sunset, you could measure the angle between the sun and celestial objects that are visible even in daylight: the Moon, Venus, and Jupiter are the best choices. You then ...
After 1000 generations, separate populations of E Coli gained similar and sometimes identical mutations The E coli genome has millions of nucleotides. How deterministic or predictable is adaptive diversification?	[ "While not an answer to your question, a point which you might be missing (judging from the title: the \"The E coli genome has millions of nucleotides\" part). Genomes are large and mutations are random, so if we leave things to chance, the probability of independently repeated mutations in many individuals in th...	[ "First, it isn't really correct to say there's a scientific consensus about the safety of consumable GMO's. That's like saying there's a scientific consensus about the safety of eating non modified plants. There's some natural plants that are poisonous. You could conceivably make some GMO that are poisonous. The wa...
What would a bose-einstein condensate look like (supposing you could get several billion atoms in one place)?	[ "Just a cloud of gas. The condensation is in momentum space. Some would say that superfluid helium is a BEC though." ]	[ "Because what's considered \"high amounts\" of things in air is actually quite a tiny amount. For example, pollen count is measured in grains of pollen per cubic meter of air, and the websites that I see to track it have \"very high\" pollen levels at around 10. That's 10 grains of pollen per cubic meter. Hardly so...
renting, owning, leasing, apartments and houses	[ "Your friends are idiots. If you want to buy a house, go for it. If you don't, don't. Renting is not a waste of money if it's what you want." ]	[ "People [buy ad space on reddit](_URL_1_). (In the sidebar, disable adblock on reddit if you have it on and want to see the ads). People buy membership for additional features, [Reddit gold.](_URL_0_) Reddit sells stuff in the [Reddit Store](_URL_2_)." ]
I'm watching the John Adams miniseries and I'm confused about something. Can you help?	[ "I think Wikipedia used the wrong adjective there, the White House was still under construction and this is probably what it was referring to." ]	[ "I suppose it depends on what you mean by 'American'. With regards to the colonies that later formed the US, then the answer is no. If you include the colonies that later became Canada, then from 1624 to 1707, baronetcies were sold in the newly created Baronetage of Nova Scotia in order to fund the plantation of th...
How far do you have to go beneath the ocean floor before the earth becomes dry again?	[ "Based on OP's clarification, nobody has answered the question yet. All the answers so far basically state, \"There's water in the crust everywhere, so you'll never find crust without some sort of water.\" That answers the title's question, but OP doesn't want to know where the crust is no longer wet. He or she app...	[ "Incidentally, this is the problem that _URL_0_ is trying to solve. Here is the map of the overall plan: _URL_1_ There is enough solar energy in the Sahara desert in 6 hours to power the entire world in 1 year. From the Sahara, they plan on connecting Europe with underwater high voltage direct current lines. The p...
Why isn't the motion of the Earth used to produce energy?	[ "If we did we would eventually slow the Earth down which would have disastrous effects." ]	[ "Same reason you don't keep turning the ignition key for hours in your car when it won't start -- there's no point in doing it, it won't get better." ]
Why are bloody noses so.. bloody?	[ "The nose is filled with lots and lots of tiny, flimsy capillaries that supply the olfactory cells with blood. There's a lot more surface area inside your nose than you'd think and therefore a lot more blood vessels! the inside of your nose is designed to maximise its surface so you can smell things more effectivel...	[ "Basically, your blood pressure is higher than atmospheric pressure. Fluids (air, blood, etc) always flow from areas of high pressure towards areas of low pressure." ]
How do vocalists that perform nightly not lose their voices after performances?	[ "Practice, proper technique and physical conditioning. The voice can go on for hours on end, day after day if the muscles that support the vocal cords and the abominal muscles are strong. Source: in college I studied vocal performance, and I was in a traveling choir that sang 2+ hour long concerts 20 nights in a ro...	[ "During our primeval evolutionary history, someone would only become the focus of interest for everyone you know if they were a close friend, a great leader, a highly desirable mate, or an enemy. As a result, we instinctively group celebrities into one of these categories. If you're not appealing to sex, goofiness,...
Why is Julius Caesar typically depicted as being a 'good guy'?	[ "I would be curious to know if Caesar's reputation was due to propaganda by his heir, Augustus. It would have been in his interest for Caesar to have been a great man, Augustus had a long reign and a lot of time to drill that idea home, and, the men who murdered Caesar, ie, the opposing view, didn't last long." ]	[ "I heard it had a lot to do with the invention / discovery of the camera obscura. This helped people understand perspective / proportions / etc better. Here's a quick article I found about it - but there are a ton of others, videos, books, etc that talk about it in more depth. _URL_0_" ]
Can any of Maxwell's equations be deduced from the others?	[ "None of Maxwell's equations can be derived from the others. Although as a cool side note, the continuity equation can be derived from Maxwell's equations. If any one of Maxwell's equations could be derived from the others, it would be redundant. In the interest of \"elegance\", we wouldn't list it as one of Maxw...	[ "The components in mobile devices, including the CPU, operate at lower voltage levels and take less current than those in a desktop or laptop. This means less power dissipation and no need for a fan. Clock rates aren't the primary driver. Watts = Voltage x Current" ]
Whenever evolution discussing the appearance of land animals is shown, we see a progression of fish, proto-amphibian, and lizard. What was the procession "out of the water" leading to insects?	[ "The early evolution of insects is really unclear, that's why you didn't learn about it in school the way you learned about mammalian or reptilian evolution. The oldest fossil evidence is Rhyniognatha from the Devonian (400mya) - about the same time jawed fishes and early sharks were evolving. It was something k...	[ "You have to understand that arms (or forelegs) came before the wing. The wing contains the same bones as an arm and hand, and are modified from this, the wing didn't start from a stub. This article contains several theories of how wings might have been used before they were used to fly: _URL_0_" ]
Where does the large budget for modern movies go into?	[ "it goes to the thousands of people and hundreds of companies that work on the movie. & #x200B; for every named person in the credits, there's 100 people that aren't named. everything from makeup helpers, to guys that put up the set pieces, to second unit photography, to post production crew, to guy that orders t...	[ "It stays in their campaign fund and can only be used for campaign expenses. Most candidates run a debt, so there isn't much left over. When there is, they can use it for a future campaign." ]
Can an Algorithm have complexity = constant / n ?	[ "If you define the complexity of an algorithm in the usual way, using the number of steps a Turing machine will take to accept/reject a word in a formal language, then moving to an accepting/rejecting state constitutes a step, hence the fastest algorithm possible is O(1). Note that a function like f(n) = 1+1/n is n...	[ "If you are cooking potatoes you don't need to look at them to know when they're done. You can simply set a timer and take them off it rings. In the same way we usually know how many iterations of some calculation is needed until we should arrive at the correct result. In some instances this is not exactly the cas...
Gambler's Fallacy. After a fair coin is tossed & lands on "heads" 500 times the chances of it landing heads again are 50/50.	[ "A fair coin toss can only land two ways, heads or tails. 50/50. The fallacy is believing in trends and disregarding the honest odds, numbers don't lie but our feelings cloud our judgements. You can flip the coin 100 times and just because it landed on heads 100 times you'd either be lead to think that either a, it...	[ "[Neither](_URL_1_). Most of the time those percentages refer to “percent of women that did not get pregnant while using the method for a year”. That is, taking tho 99.9% figure: In a given year of using condoms, 1 out of 1000 women got pregnant. But your source may use a different method, so take a close look at t...
What is the dome on the front of this wind turbine?	[ "It’s a [product of GE](_URL_0_) used to make your wind turbine more efficient. That one is probably a test sample." ]	[ "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." ]
Would a compass work in a Faraday cage?	[ "Yes, static magnetic fields penetrate conductive enclosures. Static electric fields do not. I encounter this daily - I use aluminum for shielding, but must still account for earth's field. It is possible to design a \"zero field chamber,\" which I use to zero a gaussmeter, but I don't know how it works." ]	[ "No it is a myth, this doesn't actually happen it has been perpetuated by many websites emails etc. but the Coriolis effect doesn't happen in plugholes ." ]
Graph theory [mathematics] question.	[ "Are you asking what the probability that any cycle will occur or are you asking what the probability that a cycle of length k will occur for each k < n? Claim: Your graph will always have at least one cycle. Proof: Let P = p_1 p_2 ... p_k be the longest directed path in your graph. The arc out of vertex ...	[ "Say you have a banana and an apple. How many ways can you arrange those on a table? You can put the banana on the table. You can put the apple on the table. You can put both on the table, or you can put none of them on the table. There are four ways total that you can arrange these fruits. This represents 2 to the...
what happends if a blind person takes LSD?	[ "Not going to answer fully, but I would like to say that visuals are less than 3% of the magic and wonder that is LSD." ]	[ "You seem to be describing a variant of the [ladder paradox](_URL_0_), just using a train and tunnel instead of a ladder and a garage, he he. > What does the outside observer see? The outside observer sees the front guillotine make a cut, then later after the train has passed further through the tunnel, the back g...
Risks of overconsumption of artificial Vitamin C tablets?	[ "Vitamin C increases oxalate formation and absorption in the gut. Oxalate is poorly soluble and can complex with calcium as well. This can lead to deposition in tissues such as joints and the kidney. When deposition in the kidney reaches a critical level crystals can form. These crystals as common known as kidney s...	[ "Some of the chemicals in the toothpaste [block your ability to taste sweetness](_URL_1_), which makes the sourness of oranges a bit overwhelming. A similar thing happens with [miracle berries, which block bitter and sour tastes](_URL_0_)." ]
Don't the bacteria in probiotic yogurt just die in our stomach acid?	[ "Some do, some don't. There are bacteria that can survive the acid of our stomachs (and even higher levels of acid). H. pylori, for example, is a pathogen that specifically infects the stomach. (and I'm intentionally not saying anything about the efficacy of probiotics)" ]	[ "I ain’t no scientist but here is my two cents... Fruit is designed to ferment (rot) as part of its ability to seed. When fruit falls from a tree (or is picked) the fruit starts to ferment which releases natural sugars making it sweet and juicy - eventually you’ll see the pips, seeds or stones becoming easier to re...
Does the Big Bang Theory, with everything starting from a point, violate Heisenberg's Uncertainty Principle?	[ "Everything was very hot as well and a larger momentum uncertainty allows smaller position uncertainty. Anyway, the universe was probably never so small that this would have mattered." ]	[ "The main indicator of expansion of the universe is redshift, a result of the doppler effect. When something moves, the sound it makes is distorted in frequency (see [this image](_URL_0_)). That's why formula 1 cars and ambulances sound different when driving towards you than driving away from you. The same thing...
Why are some college programs so rigorous?	[ "so they can say whomever got through that program are the Best of the Best? also, nowadays (with grade inflation), you've to mess up a lot to fail a class. also, a lot of programs do that to weed out the non-serious candidates, so the better candidates can enjoy a smaller class size & better resources. lastly, it ...	[ "I would have to guess probably the efficiency of the code itself. I wrote a program that converts images to black and white in real time (shows the conversion on screen) and before I streamlined the code it didn't matter how fast the pc was it took the same length of time to process basically. once i streamlined i...
Is dark matter uniformly distributed throughout the universe or is it concentrated in specific areas?	[ "It's mostly in halos around galaxies, extending far beyond the visible luminous matter, but occasionally it can be separated from the visible matter that it tends to be associated with, as has happened in the case of the [Bullet cluster](_URL_0_), where two galaxy clusters have collided and the hot intracluster ga...	[ "On the earth end the communication is done with very large, highly directional radio dishes (essentially radio telescopes), for example, the [Deep Space Network](_URL_4_). The high directivity of the antennas lets you receive more signal while at the same time ignoring most of the background noise. There isn't rea...
Unlike other democracies, the US has repeatedly reverted to a two-party system throughout virtually all of its history (even when the parties involved have changed). Is this a result of something structurally distinct about America, just force of habit, or something else?	[ "I would like to challenge the claim that we have actually been a two party system. On the surface it's true but V. O. Key documents in his book \"Southern Politics in State and Nation\" that in fact that Democrats in the South during the first half of the 20th century often (though not always, see Virginia) had mu...	[ "Simple: because (most) (common time) music is made for dancing — and humans have two feet, and can step forward and back. Start - left foot forward - right foot forward - one foot back - another foot back (start). Feel free to substitute \"step right\" or \"step left\" or \"lift\" or \"put down\" or \"shake it al...
How do motor boat engines not get water logged?	[ "Same reason your car motor doesn't get water logged when you drive in rain or puddles. The motor is not in the water. It's spins a shaft which is also attached to a propeller, that goes into the water." ]	[ "If it didn't rain for a really long time then they would. Lakes hold a LOT of water so it would take a long time to dry up. A little rainfall has more impact than you would think because a lot of rain that lands on the ground will eventually trickle down into the lake after a while" ]
What happens when you can't pay a bill at a restaurant?	[ "They call the cops and you get to explain to them why you stole a bunch of food. Assuming of course that you can't find some way to pay for your meal." ]	[ "The economy would shrink by 80 billion dollars. The government would likely make up for that by printing another 80 billion dollars -- like they do for all money that gets too damaged for circulation. Essentially, he'd be giving it to the government, with a small printing fee." ]
Why humans got to the point of changing who they are completely just to fit in.	[ "It makes evolutionary sense. We're social animals - without cooperation we would never have made it." ]	[ "Hi OP, this is a cultural question, so it would greatly assist anyone considering answering if you could specify which culture you're asking about. For example, the name of a cultural group / country / geographic region, plus a rough time period. Otherwise, this question is simply too broad, as it encompasses almo...
Why is refrigeration not required for single use coffee creamer shots?	[ "They are [ultra high temp pasteurized](_URL_0_) and sealed, like shelf stable boxed milk is. As long as they are unopened, no bacteria, etc. can grow inside the container." ]	[ "Obviously, someone might steal it from you if you carried it around with you. And if you steal something, you can't just put it in the bank now, can you? Especially if you're an outlawed pirate." ]
Why do many animals have a ligher color of fur / skin on their bellies? This looks like a disadvantage	[ "Animals with a light colored belly and dark colored top have a type of coloration called countershading. It is thought to be advantageous. The dark coloration is camouflaging for the animal when viewed from above, while the light belly is camouflaging when viewed from below (usually blending into the sky). Counter...	[ "Setting aside the terminology of \"race\", it's entirely down to selective pressures of the different environments. In equatorial regions where the sun is plentiful, having a lot of melanin is useful in protecting against cancer. The further north/south you go from there, the less sun there is, so having less mela...
[Medicine] How does limb reattachment work?	[ "This is known as [replantation](_URL_1_). [For digit and hand replants, you basically repair and reattach the bones, then tendons \$to provide support for other soft tissue structures\$, followed by connecting the arteries, veins, and nerves via very delicate suturing. ](_URL_2_) > In the majority of amputatio...	[ "Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s): You can find the basic answer with a google / wiki search. Please start there and come back with a more specific question. If you disagree with this decision, please send a [message to the moderators.](_URL...
If we could drain the ocean, could we breath or live on the deepest parts or would pressures, temperatures, and oxygen levels be too extreme for us to live such as high altitudes?	[ "Instead of draining the ocean, what about a cofferdam down to the ocean floor? Something like a giant tube all the way down so that you were at the elevation of the bottom of the ocean. Are you interested in whether we could breath there or if the pressure would be too high?" ]	[ "There are a few different kinds of moon pools. The easiest one to understand are basically a hole in the floor above the waterline of a drilling platform or ship with multiple hulls that lets you look down into the water. You're probably thinking of moon pools below the water line though. Imagine taking a cup, tur...
Why are the letter keys on a keyboard arranged in a seemingly random fashion, not in alphabetical order?	[ "In 1875, Christopher Sholes with assistance from Amos Densmore rearranged the typewriter keyboard so that the commonest letters were not so close together and the type bars would come from opposite directions. Thus they would not clash together and jam the machine. The new arrangement was the \"QWERTY\" arrangeme...	[ "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...
Wasps parasitize an incredibly diverse range of species, including plants and animals. Did this tendency to parasitize come from a common ancestor which shifted hosts, or is there just something about wasps which makes them tend to evolve parasitic relationships?	[ "The common thing that wasps (incredibly diverse submembers of the incredibly diverse order hymenoptera) seem to share as a contributing factor for developing parasitic/parasitoid strategies are their anatomy. An ovipositor for example is a very useful device for placing your soon-to-be-offspring into a \"relativel...	[ "When a mosquito bites you, its saliva acts to keep the blood from coagulating so it can drink more. Our bodies detect this saliva and send a compound called histamine in response to the foreign substance. Histamine acts as an inflammatory agent to fight infections, which is why the bug bite swells. It also makes ...
why do dogs tilt their head when you talk to them?	[ "This article is speaking of humans, but I imagine the same applies for dogs. Seems to make sense for the head-titling interactions I had with my dog. \"Tilting the head sideways can be a sign of interest, which may be in what is said or happening..... Tilting can similarly indicate curiosity, uncertainty or query...	[ "It's completely cultural. Some languages are tonal, which means that a word's tone is an inherent part of its pronunciation. If you change the tone from a falling one to a rising tone, you've mispronounced it and have likely said a different word entirely. In Mandarin questions are indicated by adding the word \"m...
the change in income tax law between 2017 and 2018.	[ "There were two big changes that affect non-itemizing tax filings. 1) Some of the tax brackets decreased. This is a proportional decrease in paid tax per dollar that will be a few percent for most people. 2) The standard deduction increased by close to 5,000 dollars to $12,000. What this means is that without itemi...	[ "So, I don't know if you know this, but Blackstone did just what you are suggesting. After the housing crash of 2009, they went out and bought up homes in different cities. They put them all under the umbrella of a REIT (real estate investment trust) called \"Invitation Homes\" and then spun it out in an IPO a few...
Where do neutrons come from?	[ "[Shortly](_URL_0_) after the big bang, the universe was filled with a [quark-gluon plasma](_URL_2_), which upon cooling led to the creation of bound states like protons and neutrons. The subsequent epoch of [Big Bang nucleosynthesis](_URL_1_) is responsible for the creation of heavier nuclei, like Helium." ]	[ "Your brain consists of neurons that are connected to one another, and these connections strengthen over time through repetition. In your whole lifetime you've learned that the way to evade an object flying at your head is to move certain muscles. So when some neurons send a signal \"there's something flying at my ...
Why is it legal to fire missiles against uncertain targets with a drone?	[ "This doesn't seem like a very ELI5 kind of question. There's no simple way to explain an answer to really any of your questions, and you'd be even less likely to get an unbiased one. I mean, look at the comments so far." ]	[ "I'm a journalist. I can tell you straight up : it's for audience. These videos create shock, which is the best hook television news has over the viewer. The whole ethics speech they'll give you about people having the right to see it is BS. Television is a business, news or not, sadly. This is even more true in th...
Do we understand the process of particle annihilation?	[ "There are certain properties that are conserved (i.e., do not change) in an interaction; energy is one of them. However, the form that the energy takes can change. Thus, for example, when an electron and positron collide, what is happening is that the energy in the initial system (electron plus positrion) is being...	[ "Have you ever wondered what's inside your bouncy ball? Imagine it was too small to cut but you really, really wanted to know. What you might want to try is throwing it into something so hard that it breaks and you can see the smaller parts. Of course, if you only have another bouncy ball because that's the only th...
Why do people laugh at pain?	[ "I'm not a scientist, but from what I know laughter is the body's natural expression of relief. When you were in the tall grass and you heard a rustling, you got tense and clutched your spear and faced the attacking sabre- nope, it's just a mouse. This is where you laughed, and other people around you realised it w...	[ "They're vulnerable areas that you reflexively want to protect. In nature, tickling teaches how to protect your sensitive areas, how to fight others while not doing harm or damaging (too severely) social bonds. The purpose of play, basically." ]
What does Putins anti-gay law say, and why is it so bad?	[ "If i'm not mistaken, the law forbids promotion of non-traditional sexual relations among minors. That itself is absurd, but the bigger problem is that the text of the law is so ambiguous that any public expression of \"non-traditional love\" o even any public comment can be punished. (Sorry for my english, not my...	[ "Hi, I've approved the post, but just a note to you and potential respondents: this subreddit has a 20-year rule against discussing current events, so any answers will have to cut off at 1997. If you're looking for answers that can include 1998-2012, do consider x-posting elsewhere, eg. a foreign affairs sub like /...
Is weed (cannabis, pot, marijuana) actually a "weed"? or does it ever grow like one?	[ "The term \"weed\" is used to make it seem less valuable as a medical substance. (make it seem more like a nuisance, street drug, etc, as opposed to a valuable medicine.) Hence the term \"weed\" is actually offensive to some users. \"Marijuana\" is also offensive, though less so. It is the Spanish word for Cannabi...	[ "There is this guy, who goes by the chosen name of The Doctor. He belongs to a species that mastered time. And so he has a time machine (called the TARDIS) which is also a space ship that travels as the speed of plot. Basically he can go anywhere or anywhen within a few minutes. He travels the universe doing good. ...
How important was Emperor Pedro II in regards to the wide adoption and use of the telephone?	[ "Unknowingly put myself in the week's themes. Not necessarily a travel focused question. Sorry about that :(" ]	[ "[Wikipedia](_URL_0_) has some good comments on it. I remember the notes about Napoleon from elementary school history. > There is a popular story that Napoleon changed the rule of the road in the European countries he conquered from keep-left to keep-right. Some justifications are symbolic, such as that Napoleon...
Does refrigerating ice slightly above its freezing point slow down melting?	[ "Yes. For conduction and convection forms of heat transfer the rate of heat transfer is directly proportional to the temperature difference between the atmosphere and the object. If your ice is 32F (assuming you haven't cooled it past its freezing point) and you refrigerate it at 32.1F your ice will melt about 100 ...	[ "There are lots of ways for animals to traverse the earth, not to be trite. Addressing your specific example, this wiki. _URL_1_ Indonesia was at one time linked to the rest of the islands in that part of the world, when sea levels were lower due to so much water being bound up in polar glaciers. When the glaciers...
Can dogs, cats and other animals know that it is themselves they are looking at in a mirror?	[ "[Animals species that have passed the Mirror Test](_URL_1_) [Animals species that have failed the Mirror Test](_URL_0_)" ]	[ "Same as humans. They have brains, sense organs, hormones, instincts, experience and subsequent problem solving, etc. Granted humans have a sophisticated language and mediums that facilitate mass communication and education, but even with the absence of that there is still instinct and learning -- a newborn babe wi...
Can you be vaccinated through donated blood?	[ "For all intents and purposes, no. Most blood products you receive are sent through a filter that removes the vast majority of white blood cells. In extremely rare circumstances white blood cells that have been transfused are able to engraft and live on in the body. There was a case recently of a severe food alle...	[ "It is called the Hygiene Hypothesis. It states that the lack of childhood exposures to bacteria, parasites, infectious agents, etc, leads to an increased susceptibility to allergies, autoimmune diseases, and even autism. Note that this is still a hypothesis, and any studies thus far have not provided concrete caus...
How were the laws of physics formed?	[ "This is an open question. It may have been determined at random at the moment of creation or the constants we see may be the only constants a universe can have, or there could be some other non-random determining factor. In short, we have no idea." ]	[ "Technically F = dp/dt = ma assumes constant mass. Some people try to derive the rocket equation by taking dp/dt = m dv/dt + v dm/dt, but notice that the v in the second term should be the exhaust velocity of the propellant, not v which is the velocity of the rocket. This derivation ...
How can the predators on "To Catch a Predator" be arrested? If they haven't molested or communicated with a child, what are they charged with?	[ "In most states, online solicitation with the belief that the other person is below the age of consent is a crime." ]	[ "Most assume that the laws all behave the same for antimatter. It makes the most sense. The biggest difference between a proton and a positron even though one is ordinary matter and the other antimatter is their mass to charge ratio, but otherwise they behave similar. However, there are two caveats: CP violation, a...
What is Steam video gaming and how is it different than other gaming platforms?	[ "Steam is a platform that largely integrates a store, library/rights management, and a \"community\" (some online multiplayer functions, friends, messaging, sharing, etc) in a single application. For the large part, it became popular as it was the only \"big\" platform of its kind for quite a while, and some pop...	[ "Cars came around in an era where there were significant concerns about \"vertical integration.\" The concern is that an automaker can undercut another retailer that sells their product and drive them out of business. So some states passed laws against them doing just that. Those laws are specifically tied to cars ...
The Venezuela crisis	[ "I'll be honest, it's VERY hard to explain this situation shortly as it's a pot that has been boiling for over 20 years. I'd recommend spending a couple minutes reading this amazing and well-written response in another thread in /r/OutOfTheLoop _URL_0_" ]	[ "A guy on Gawker published violentacrez's real name, which caused a lot of subreddits to ban all Gawker links." ]
Historians of reddit! Any records describing ancient viking songs?	[ "Not an answer to your question, but maybe of interest to you. There's an album by the group Sequentia (who specialize in early music) titled [Edda: Myths From Medieval Iceland](_URL_0_) In it they've attempted to re-construct what a telling of the Edda might have sounded like when it was performed. You can [li...	[ "Hi everyone. Since this is the kind of question that can attract non-expert responses, just a friendly reminder that all responses must comply with [sub rules](_URL_0_), and that [personal anecdotes](_URL_1_) are explicitly not permitted in /r/AskHistorians." ]
Has laughter always been universal?	[ "Other primates laugh. Gorillas, for instance, sound a bit strange when they laugh as it's only one \"ha\" at a time. It just seems to be a natural reaction and has changed as we have evolved." ]	[ "Fish yawn as territorial or mating displays it's commonly accepted that all vertebrates yawn. Nobody knows why though here's an article on [why we think people yawn](_URL_0_). [Here is an article about fetal yawning](_URL_1_)" ]
What does my bank gain by increasing my line of credit?	[ "The more money you spend on a card, the more money they make from merchant fees. Making money from those who pay interest on cards is simply gravy." ]	[ "They don't. It's a marketing ~~lie~~ gimmick. I used to work for a company that did a similar thing by mail. New customers were supposed to sign up by a certain time for special rates but as a specific matter of policy we'd give those rates to anyone who mailed back the special offer." ]
Why do Internet providers always offer extremely low upload speeds and much higher download speeds?	[ "ISPs usually have terms of service that discourage customers from using their Internet connection to operate servers. It doesn't make sense to offer high upload speeds under those circumstances--and the rest of the comments are also true, regular users just don't need that much upload bandwidth as it's mainly used...	[ "There are clear probate laws that handle most cases, explaining how one's possessions (called their estate) should be distributed. A person, called the executor of the estate, is approved by the courts to settle the person's affairs. They distribute the money in bank accounts, sell their house, whatever is needed....
Say I'm standing in a space suit in a perfect vacuum chamber with a golf ball sized black hole next to me. Would anything happen? What would happen if I poked my finger in it? Could I pull it back out?	[ "By \"golf ball sized black hole\", do you mean that the radius of the event horizon is that of a golf ball, i.e. 21.35 mm? If so, you're in big trouble, but you won't have time to recognize it before you're sucked in, since it'll take less than 50 nanoseconds to suck you in. To calculate the mass of this black hol...	[ "I want to hear more detail. The smaller forces would mean if you dip below your point of neutral buoyancy it would take longer for you to rise back up. And similarly if you gave a particularly powerful stroke while treading water and rose above the surface some you would sink back down much slower. So I can only i...
Would someone treated with an AED feel the shock?	[ "Some AEDS can be used to cardiovert, cardioversion is a carefully timed shock to convert the heart from a dangerous rhythm during which a patient may be concious, to a more correct one. Patients can and do feel this pain, though whether or not they do is inherently specific to the situation. There can be burns t...	[ "It's difficult to design a pump that's not too rough on the blood cells. Artificial hearts (which do exist) tend to rough them up a little, which causes clotting and can lead to heart attacks/strokes as well as immune responses." ]
Why do we not recall any memories when we were a baby?	[ "Your brain's neuron pathways aren't developed enough to make permanent, long term memories. Also, the capacity to store memories is not infinite. As you make more, and more complicated, memories your brain has to make more room. It does this by getting rid of unimportant information." ]	[ "As far as I'm aware it's fairly simple, falling out of trees sucks. You're a monkey! You love being in trees, swinging from branches and all that jazz, in fact you love trees so much you even sleep in them. But, if you are sleeping you can't see what's going on, you can't move about when you don't have a full pic...
Earthquakes can shift Earth's axis and rotation? Why? How?	[ "Earthquakes involve the movement of rock. If that movement is in the vertical plane, it means that you are changing the mass distribution. That changes the moment of inertia. That can lead to miniscule variations in rotation." ]	[ "You're right to be confused. It is 100% wrong as depicted in the movie, and a lot of people of wondered about why they made such a grave error considering the rest of the movie was somewhat realistic. It is likely that the reason this happens in the movie is that it makes things more dramatic. Artistic license i...
How do maggots get into a closed container with meat in it?	[ "IIRC I took a course in college where I believe I was taught that meat basically has naturally occurring tiny little eggs in it from parasites. It's one of the reasons why eating raw meat isn't good for humans. Cooking the meat, however, will destroy these parasites/eggs and thus you have perfectly edible meat. Me...	[ "What about a fly buzzing around? They're not attached to the bus so therefore don't benefit from the momentum of the moving vehicle so why don't they splat into the back of the bus?" ]
Why is it that only the surface of my tea stains my mug, usually leaving just a brown ring, as opposed to staining the entire inside brown?	[ "Due to surface energy, the water in your cup has a [concave meniscus](_URL_0_). When the meniscus evaporates it leaves some of the tea solids behind on the wall. I can't remember if this effect is massive if you let a whole cup evaporate though..." ]	[ "Is there anyone here that could elaborate on terra petra? The article makes it sound like it was just the sour-dough equivalent of soil, but the book describes it as so much more than that. There was a process of doing a prolonged controlled burn of the jungle (it wasn't just simple slash and burn), and it was fil...
Does scar tissue out perform its replaces tissue in anyway?	[ "Even minor injuries would uniformly be fatal if we did not have the ability to scar. The healing of wounds may not be perfect, but our bodies are able to stop bleeding, heal wounds in skin, internal organs, bones... Having made many thousands of wounds, I personally am amazed at how good we are at healing, not how...	[ "The long and short of it is that it depends. Sharecropping was incredibly common. Sharecropping was the practice of dividing up plantation land and letting former slaves work there. The catch was their rent was a good portion of the crops which was paid to their former master. Many former slaves went into debt in ...
Why does the world (besides the United States) hate Israel so much?	[ "The modern state of Israel was created after WW2 to create a home for the displaced Jews from Europe. President Truman strong-armed the rest of the Allies into supporting the plan. To create the state, Palestine was carved up, and Israel was handed a prime spot in the middle of Muslim country, including the city o...	[ "\"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..." ]
What is so monumental about Einstein's Photoelectric effect?	[ "It proved that energy from light is transferred in discrete units, which lead to the development of quantum theory. Essentially, low frequencies of light would not induce the photoelectric effect no metter how intense the light was. This suggested that the light had to pass some kind of minimum energy barrier, but...	[ "Get thee to a museum and consider the originals! Prints and computer screens are better than nothing, but they aren't the same. I was in high school in the 60s and had a classmate; football player, super strong athlete, and he liked to draw stuff. Always doodling. He went on a field trip to a museum and saw Van Go...
/psychology What do psychologists use to determine and classify personality?	[ "While what /u/masterkrabban says is right and there is a lot of debate, if you wanted just the most widely accepted personality theory you would probably want to stick within [the big five](_URL_0_) model. The crazy thing is that the standard test for it [the NEO](_URL_1_) is actually a privately owned test and no...	[ "A few different ways; - [Lasers](_URL_0_) for really close things like the moon. - [Parallax](_URL_2_) used for nearby planets and stars. - [Standard candles](_URL_1_), the brightness of a specific type of supernova which gives a good range. - [Red Shift](_URL_3_) for things very far away. For more detail on how a...
why don't the fingerprints on my left hand resemble the fingerprints on my right?	[ "Because fingerprints are caused by chemical reactions in the womb. While genetics affects the shape of your hand and fingers and therefore, to some degree, has some impact on your fingerprints, the actual process isn't genetic. All this is a long way of saying that your fingerprints are the closest thing to random...	[ "Soooo many things. Temperature, current water AND salt levels in your body, your diet (not just week-to-week, but also day-to-day, and sometimes meal-to-meal), hormones, exercise, current and previous health routines, sleep patterns, and the consistency of all of these factors. If you want to start having more \"g...
What is the entropy operator in QM?	[ "I don't know of any entropy operator, but the entropy can be written as the trace of an operator. Specifically the [density operator](_URL_1_) (ρ). The [Von Neumann entropy](_URL_0_) is defined by: S = - Tr[ρ ln(ρ)]. If you're not familiar, the trace of an operator is simply the sum of its eigenvalues. And that ex...	[ "It depends on your favorite interpretation. Copenhagen: Things collapsed because there were measurements in the universe. Many worlds: Things are still entangled but we only see a part that \"looks\" classical due to decoherence. And so on. > How can we even suppose a freshly prepared qubit, if it contains hidden...
Why does fish spoil so much faster than other types of meat?	[ "Fish live in the cold, so their biological processes, and their native bacteria, aren't slowed down much by refrigeration. The \"biological processes\" are what make fish turn color and lose taste quickly. While the bacteria that live in the fish are what eventually make it \"go bad\"." ]	[ "Bacteria is a tiny, single-celled organism. Bacteria can exist on its own in the world, or inside of other living things: plants, animals, you, me. Not all bacteria are bad, though, and we have beneficial bacteria living inside our bodies every day. Whereas Viruses are also microscopic beings, but they behave diff...
Anyone heard of Admiral Karpfanger and my great-grandpops Reinhold Walker - missing since 1938?	[ "I did some google-fu and found the [ship referenced on this wiki-list](_URL_2_). It pointed to two further sources. [_URL_0_](_URL_0_) which contains some information prior to German service, and the [Miramar Ship Index](_URL_1_) which has further information but requires a subscription. That list and [Wreck Site]...	[ "Hi OP, I've temporarily removed your post per our rule to protect personal privacy - _URL_0_. Could you either remove the link to your grandfather's docs, or modify the images to block out his name (and the names of any other people not serving in an official capacity), and any other identifying information. Then ...
Will a tank full of water weigh the same if you add a whale to the same tank?	[ "Whales are basically the same density as water, which is what makes them seem \"weightless\" in water. You can see a similar effect with very low density objects that are \"weightless\" in air, like non-helium balloons. But balloons and whales still have weight, and their presence will still cause the whole tank t...	[ "Essentially what you are asking about is targeted fat loss. [Here is a pretty decent article](_URL_0_) explaining that targeted fat loss just isn't possible. Now, as to whether or not the fat will shift position because of an increase in muscle mass - I find it hard to believe you would be able to increase the ma...
Why isn't America's massive debt being considered a larger problem?	[ "US debt is not the same as personal debt. US debt is sold as a point of investment in the form of government bonds. It is also one of the safest forms of investment as the US has never defaulted on any of its bonds when they have come due, and they do not all come due at once. We also have a better debt to GDP ra...	[ "We don't have nearly as much to protest about. Other countries protest over things that are killing people. We protest over not having enough money to buy a third iPad." ]
Did ancient peoples write novels? If not, when did novels start to be written?	[ "It would be worth x-posting this to /r/AskLiteraryStudies. Meanwhile, here are some previous posts that may be of interest * [What other Latin Novels do we know of?](_URL_0_) - various Greek works * [What is the world's first novel?](_URL_1_) - Satyricon * [What is the earliest known fiction book, and what was it ...	[ "Well, I can't tell you what day-to-day astrology was like for the average person, but I can tell you something about astrology in the 17th century. [This](_URL_0_) is a nocturnal. Basically, you can use it to tell you what time it is using the stars, and a rough idea of your position. That particular nocturnal i...
If heat means molecular motion and zero means no molecular motion, then what happens below zero?	[ "On the absolute scale, Kelvin, where 0 degrees is no molecular motion there are no negative degrees. It stops at 0. Be kinda cool if negative made the molecules go backwards like back in time." ]	[ "It does! Water at 10 C is about 4 times as viscous as water at 90 C. Because the viscosity is so low at any temperature you can't see or feel the difference, but it affects the sound of pouring water in a way you can hear. _URL_0_ _URL_1_ Viscosity arises from the interactions between molecules, and for liquids is...
Pushing a truck, how to figure out equivalent to pushing a sled?	[ "The easiest way to answer your question is to buy a double hook scale like [THIS](_URL_0_) ($20) and tow the truck with it. Do the same with various masses on the sled and you will have your answer. The amount of force to get the sled moving will probably be higher than to get the truck moving because it will lik...	[ "If you can't find an answer here you can always try e-mailing whatif@xkcd.com and hope it gets featured there, because it sounds like a question that would fit. Sorry I can't help any further =/" ]
If so, what's the difference between a Sith Lord and someone using the dark side of the force?	[ "A Sith Lord is trained as a Sith Lord. He or she learns not only the Force, but a certain code of ethics as well, questionable as they may be. Someone who uses the Dark Side of the Force is just someone who has figured out how to use the Dark Side of the Force. Most likely, they were trained, at least to some de...	[ "The process you are interested in is called [baryogenesis](_URL_1_). It is not yet known how this process occured, but there are several proposals. In order to find a viable model it must obey the famous sakharov conditions (B,C, CP violation and departure from thermal equilibrium) I think the two most widespread ...
Do geosynchronous satellites only orbit around the Equator? If no, how do they maintain orbit?	[ "\"Geosynchronous\" simply means having an orbital period that is the same as one sidereal day (23h 56m). There are a variety of orbital trajectories that meet this definition. The orbit that everyone always thinks of when they hear the term \"geosynchronous\" that must be in the plane of the equator is the geosta...	[ "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...
Why manual car drivers change gear at a very high rpm (6k+ rpm typically), while automatic cars shift up at a rather low rpm (below 4k)	[ "Manual car drivers can change gears whenever they want, but if they change at a high RPM, it is because they want to accelerate as fast as possible, because peak power is usually produced towards the top of the RPM range." ]	[ "The human eye has an incredible dynamic range that we are just not able to reproduce with a camera. Dynamic range is the visual perception of the difference between the dark and well-lit areas of a scene. Our eyes are able to distinguish both dark and light right next to each other. Cameras are typically better e...
What happens to wildlife in a blizzard?	[ "More deer do die during really bad winter conditions, but it's surprising how ridiculously tough they are. During the end of fall they undergo a number of bodily and behavior changes: they eat way more food to pack on insulating layers of fat, they shed their summer coats and grow a winter hide of hollow fur that ...	[ "It is because freezing is a separation method - see [freeze fractionation](_URL_0_). When ice forms, it prefers to form with pure water, and this pushes any dissolved solutes into the remaining, non-frozen solution. This ends up concentrating the solution at the point of the vial where it last freezes. The reverse...
Why don't we just make a giant magnifying glass to heat water/create steam for a power plant?	[ "There is a more efficient version. [This is a solar system.](_URL_0_) [Here's another.](_URL_1_) They reflect light from the sun onto a pipe filled with a fluid, probably petroleum, which then is used to heat water." ]	[ "They may have been talking about the concept of using a high-powered laser to push a ship equipped with a mirror. That is a variation of [Beam Powered Propulsion](_URL_0_). Given enough energy and enough time, that could propel a ship to near light speed. It isn't that space has no gravity - gravity exists everywh...
Why Does Bottled Water Have an Expiration Date?	[ "All products for human consumption in the US are required to have expiration dates. This includes water. The time the companies give is their best guess at when the water will be compromised by either the degrading plastic or when contaminents will start to get in through the bottle." ]	[ "Your question reminded me of this frikkin awesome documentary of about planned obsolescence. [Video snippet](_URL_0_), and the whole documentary, I can't find... but Im sure someone else may be able to. ELI5 version: Because companies want you to keep them in business." ]
What is the 9th circuit court of appeals?	[ "The United States Court of Appeals for the Ninth Circuit is a U.S. Federal court with appellate jurisdiction over the district courts in the following districts: District of Alaska District of Arizona Central District of California Eastern District of California Northern District of California Southern District of...	[ "This is a post WW2 phenomena. Tech was becoming a thing. Computers, atomics, etc Planned obsolescence required new, better model names, 1, 2, 3... At some point the univac 4 needed to be better just by the sound. Univac 400 vs the IBM 401. Jump a head to the nth degree. The univac 9000 or the OS X for that mat...

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