Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
How rocket thrusters work	[ "The \"cones\" themselves are shock diamonds, and are a characteristic of supersonic flow (so, they happen all the time in rocket and very high-performance jet engines). The shock diamonds occur because the exhaust is overexpanded by the nozzle, and is actually at lower pressure than the ambient air. As it moves aw...	[ "Basically, just like YOU keep up with earth : gravtity and momentum." ]
Why is "bury" pronounced as if theres an "a" in in it? Like "berry".	[ "Regional dialects. In my region the U is pronounced and we say \"Burr-ee\" I've also heard \"Be-urr-ee\"" ]	[ "Imagine you wanted to send a digital file to a friend of yours, but all you have is a telephone and the binary data contents of the file. You tell your friend \"when I say beep you write down 1, when I say boop, you write down 0\", and then you read the contents of the file to him over the phone \"beep beep boop ...
How do master keys work?	[ "Let's say that I own a building with 15 apartments, and I want to have 1 master key to open all of them. Each of these apartments has a unique key. None of them can open the other apartments' doors. So what the locksmith does is simple: Every lock has 2 possible \"combinations\" of teeth, grooves, etc. One of them...	[ "Hi there, while I don't claim to be an expert, I have studied the GDR extensively and I have not come across this anecdote before. It seems unlikely to me, for the following reasons: * Any goods imported into the GDR would have most likely been manufactured within the Communist Bloc, and therefore of questionable...
If I cut a rope into 4 pieces and braid them together, how much stronger will the resulting rope be in relation to it's original specs?	[ "What type of braid? Can you ensure that the strands don't twist when you braid them? You're right that there are a lot of \"depends.\" If the braid is not twisted, then best-case, each strand supports an equal load, so you'd expect your new rope to be 4X stronger than the old rope. However, if you introduce any un...	[ "Different algorithms to try and compress data. In general, RAR is slower than ZIP, but it will compress the data more, giving you a smaller file. RAR is especially good at compressing multimedia files. Another feature of RAR is that you can split it into many smaller chunks, so you can have, for instance, five 20M...
Why does a trial take years to go through even when it is obvious the crime was committed?	[ "Can you please define for the court when a crime is \"obvious\"? When is the evidence \"clear\"? Why do you point out a first degree murder and claim that this is something more 'obvious' and 'clear' than say, fraud or kidnapping? It takes a long time because it is a very serious accusation and in order to ensure ...	[ "The US banking system was [developed in the 70s](_URL_0_), and has not been updated since. They save up days worth of transactions and then actually perform them all at once, which saves them a lot of effort. If Bank A has 10,000 transactions totaling 1 million dollars to go to bank B, and Bank B has 10,000 transa...
Before the Panama Canal was built, were any attempts made to ship goods over the Isthumus of Panama?	[ "The Spanish did have a land trade route over the Isthumus of Panama. It was successful and saw most of the gold and silver mined in Peru and Bolivia cross it on the way to Spain. In the 1850's, Cornellius Vanderbilt carried people by steamship to Panama, had them cross the Isthumus, and take another steamboat to C...	[ "To add a concrete example to what's already been stated: [The Sahara desert fertilizes the Amazon rainforest.](_URL_0_) Equatorial trade winds carry mineral dust (carbonates and oxides, mostly) from the Bodele depression in the Sahara to South America, significantly increasing the productivity of the Amazon basin....
How do we know that our planet/solar system/galaxy/etc aren't the building blocks of an object in a much, much larger world?	[ "We don't. The concept of things being greater than we can perceive is kinda the only thing that keeps religion going. It is not just possible but probable that we are part of a larger structure of some sort. Unlike, say, mites we have a brain capable of understanding it though. We just have to get a better picture...	[ "I personally don't feel there is any rock solid defense against solipsism. A common scenario for this is the Brain in a Vat scenario. All that you perceive is fed into your brain from external inputs. If those inputs could be manipulated perfectly, you would have no way of separating whether you are experiencing r...
Did American helicopters during the Vietnam War play music out of loudspeakers as depicted in Apocalypse Now?	[ "Hi, re your title question, check out this recent response from /u/Bernardito * [Is Wagner's Ride of the Valkyries being blasted from helicopter-mounted speakers during the Vietnam War an invention of Hollywood, or based in historical fact?](_URL_0_)" ]	[ "They were easy to get a hold of because this was prior to the [National Firearms Act](_URL_3_). As to availability, [Thompson sold it by mail order and in stores](_URL_1_). Price doesn't seem to have been the determining factor. Only the civilian models used the circular drum magazine. The military [M1A1](_URL_4_)...
How does Emergen-C make carbonated drinks lose their fizz?	[ "I think it has to do with nucleation sites. The tablet gives bubbles a good place to form. The bubbles form easily because the liquid is super saturated with CO2, and so they \"want\" to leave solution. The same reason diet coke and mentos fountains work. The bubbles are just waiting for an easy way to release th...	[ "Did nobody here do the thing when you were kids in which you take a water balloon and then fill it half with air? The air acts as a shock absorber and it's actually super hard to get it to pop by throwing it against a surface, even throwing it hard just causes it to bounce. Good way to freak people out without ...
What would the speed of sound be through an incompressible object?	[ "I don't think a compression wave (sound) could pass through an incompressable substance at all." ]	[ "Imagine you wanted to send a digital file to a friend of yours, but all you have is a telephone and the binary data contents of the file. You tell your friend \"when I say beep you write down 1, when I say boop, you write down 0\", and then you read the contents of the file to him over the phone \"beep beep boop ...
Was/is there a reason there was Looney Tunes AND Merrie Melodies? Why didn't they just have one show?	[ "[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." ]	[ "News and scheduled programs have different airing times for the different time zones. Live programs (sports, or a presidential debate or something) are scheduled so as to attempt to be convenient for everyone. This often ends up being rather late on the east coast, and inconveniently early on the west coast. I don...
Where do large shareholders get their day to day money?	[ "CEO's that don't take a salary are generally extremely wealthy to begin with, so it's not much of a problem. If they weren't, then they would just sell a portion of their stock, and that solves the problem. The CEO of a company has control of a company to a much larger degree than his personal share of the stock i...	[ "The same is true of literally any product in the world. For example, when you buy groceries, you don't buy from farmers do you? You buy from a store, that buys from a distributor, that buys from farmers. The farmer sells in bulk to the distributor who sells in less bulk to the store who sells in single units to yo...
Identifying an unknown compound using only spectroscopy.	[ "Do you know what resolution the NMR was? It's throwing me off that there is no splitting." ]	[ "Still decoding the song. You can verify this by looking at the spectrum analyzer while on mute." ]
What's so difficult about creating cross-console game servers?	[ "Well, both the Xbox and PlayStation have matchmaking built into them, which only works with other Xboxes and PlayStations. For a developer, it's much easier to just use that, than develop a separate server and then host those servers, because that takes a huge amount of computing power, and especially for somethin...	[ "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...
Why do falling oil prices also imply tanked economies?	[ "Part of it is also tied to the price of oil extraction. Alberta for instance has been experiencing an economic boom because of the oil sands, however when the market value of petrol drops below whatever it costs to extract and process oil from those oil sands(IIRC $75 a barrel around 2000), it becomes a better str...	[ "Prior to burning fossil fules, we had a balance of CO2 producers (mammal life breathing oxygen and exhaling CO2) and oxygen producers (plant life). We're damaging the oceans and clearing forests while burning fossil fuels, which releases tons of extra CO2 with less plant life to convert it. It's not like there's a...
How Do Car Insurance Companies Justify not Paying for the Full Cost of Repairs After a Wreck	[ "They do pay the entire repair — minus your deductible. You can pay more to have a $0 deductible, but more typically they are $500 or so to keep you from making a millions claims for every little ding." ]	[ "Well some of the high end brands just destroy their leftover stock, though I know [that was an issue](_URL_0_) and some may have changed (mainly by selling them to a country they don't care about). The cheaper brands just sell it to other stores, TJ-Maxx and Marshalls basically exist for this, they buy up all the ...
Were slaves really transported like this?	[ "The captains basically saw two ways to pack slaves. One way was to transport fewer slaves than the ship could actually carry in hopes of reducing the disease and deaths among slaves, this was called \"loose packing\". The other that you inquire about was the cruel way, \"tight packing\". This way meant that the sl...	[ "If you're new to the thread, please don't post the Mythbusters episode again. Mythbusters is entertaining but it's not history (or more specifically, it's not historical proof of anything.) The short answer is no, not that we know of. /u/davidaop, our pirate expert, and I have both answered [questions about th...
why are fevers helpful?	[ "A fever is the body's attempt to kill intruders(bacteria, viruses, etc) by making the conditions inside your body less ideal for said intruders. Unfortunately, your body also happens to be in your body so you suffer the effects of the raised body temperature such as sweating. A really high fever is the body saying...	[ "The Viet Cong were very aware of the anti-war mentality of Americans. It was central to their strategy for ultimately winning, in fact. They believed that if they could bring the frontlines out of remote areas and in front of news cameras, the American public would object to seeing such slaughter. And it did work....
In temperatures over 37 degrees, do fans still make you cooler, or do they make you hotter?	[ "This depends on the vapor pressure of water in the air. If the vapor pressure is below saturation at 37 C, there is some chance that the body will be losing heat from water evaporating from the skin. In this case the fan blowing at you may make you cooler. If the vapor pressure of water equals the saturation pre...	[ "When you blow to cool things down part of the air comes from your lungs, but a greater part is pulled from the surrounding air by the vacuum you create blowing. When you blow to heat something up you get much closer and try to minimize the surrounding air. There is a good video I will try to find asking people how...
How do doctors determine a baby or toddler's vision prescription? Most vision tests I've taken rely heavily on input from the patient, in which case a baby would have little to no understanding of what was going on, therefore not able to give the responses needed for a vision test.	[ "They use a device called an [autorefractor](_URL_0_). It projects an image onto the retina, and uses a camera to see if the image in is focus. It then rapidly adjusts the focus of the projector until the image on the retina is in focus, which allows it to calculate how out-of-focus your eye is. They often uses aut...	[ "Almost certainly not. In fact, it's kind of up for debate whether bees \"know\" anything at all. Their neurological systems are so simplistic, it's been argued that they aren't even really sentient in the way humans are. They're basically robots following the incredibly simple programming they're born with. It's b...
If Water Evaporates at 100 Celsius, How does the Ground Dry Off In the Sunlight?	[ "Water boils at 100C. Water evaporates at any temperature, and will even evaporate as ice (actually, it's called sublimation). wikipedia: _URL_0_" ]	[ "I'm a semiconductor reliability engineer, and I used to do a lot of ESD failure analysis: Integrated circuits have very, very tiny features. Electrostatic discharges don't have a lot of total charge, but the rate of charge flow (current) can exceed several amps for a short period of time. Since the features that ...
Why do guys get random erections?	[ "Sexually mature men can control their arousal. During puberty, hormones are all over the place causing all spontaneous arousal, etc." ]	[ "Moisture in the air helps to dissipate the electrical charge and not allow it to build up into a noticeable zap. And dry air does not." ]
What causes the "sinking heart feeling" whenever something bad happens, and why does it even happen in the first place?	[ "That would most probably be your body dumping adrenaline into your blood when something happens, the effect is almost instant. Part of the fight, flight, freeze, or fawn response." ]	[ "Anthems are designed to do this. I don't know exactly what it is, but many anthems have similar effects.try listening to some other ones." ]
Generally, how did medieval European armies assign combat roles? I don't have a specific place or time in mind, so whatever you may know would be great!	[ "There are a ton of misconceptions popular media pushes about pre-gunpowder combat. [There was a discussion about it](_URL_1_) on the short answer thread two weeks ago, as well as [this answer from about a month ago](_URL_0_) on medieval troop divisions that might get closer to what you're asking." ]	[ "Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How did we figure out how many protons each element has? ](_URL_0_) 1. [ELI5: How did scientists figure out how many protons are in an atom? Or, even, what an atom is made of? ](_URL_1_)" ]
If they're going to show commercials anyway, why do networks limit the number of episodes of a current show they allow to stream, even on their own websites?	[ "They want to encourage people to actually watch the show on television. Television ads bring in a lot more money than any ads online." ]	[ "Because it's not always the store putting out those coupons. Sometimes, it's the company who makes that brand of soda, or spaghetti sauce, or crackers, or whatever that wants you to buy their brand over the others. So they attach coupons to the shelf so you see their stuff first, and think \"this is a good deal\...
How are professional dart players able to make their shots with such precision?	[ "Practice. They spent lots and lots of hours practicing throwing darts. It took them just as long to figure out how to get a dart shot as it did for you to figure out how to get a baseball throw. You just don't think about it, because you probably remember very little of how godawful you were at throwing baseballs ...	[ "[Here](_URL_0_)'s a great video by Steve Mould on Tom Scott's channel which explains it. Essentialy it's because the viscosity (thickness) of water changes at different temperatures, changing how it splashes as it's poured." ]
What was Denmark's role in WWII and how significant was it?	[ "Denmark didn't play an important role in WWII. The Germans quickly occupied Denmark in 1940 as a staging ground for the attack to Norway. The Danish military initially resisted but surrendered after two hours. The Danish government was left in place and life continued pretty normal until 1943. The UK occupied the ...	[ "While not a scientific answer to your question at all, I want to suggest the excellent movie [Before the Fall](_URL_5_) (German Titel: Napola – Elite für den Führer) to anyone interested in this topic, which is a story about pupils in an elite high school in the German Reich." ]
Why does our moon not rotate?	[ "It does rotate, and the dark side is a misnomer. the \"Dark side\" frequently faces the sun, which is what we call \"New moon\". About once a month, give or take. However the moon is tidally locked to the earth, meaning that it rotates at the same speed as it orbits the earth. For every single orbit it makes arou...	[ "* it isn't very big, and would have to spin really, really fast to simulate 1g * spinning makes it hard to dock with * part of the point is to do experiments in a weightless environment." ]
where did the "black people love watermelon" stereotype come from?	[ "The [watermelon stereotype](_URL_0_) isn't just about liking watermelon. It's part of larger stereotype of blacks being lazy & simpleminded. The old images involved a bunch of blacks sitting around doing nothing but eating watermelon. The implication is that blacks are lazy and , without the white man pushing them...	[ "The rotisserie chicken you see in the front of stores is a loss leader. The store loses money on each chicken sold. However, when you put it in your cart and walk around with it, you smell the chicken and get hungry, thus buying more." ]
Is time truly infinite in a black hole?	[ "We can observe black holes indirectly, via their affect on light in various solar systems, notably binary star systems. We cant \"truly\" know how they behave until we are able to closely observe one. Even if we could launch probes into one, by our current theory it would take nearly infinite time to reach the eve...	[ "The Big Bang theory actually concerns itself with the evolution of the universe since moments after whatever initially happened. If we try to use the theory to extrapolate from the first moments it can represent to the actual beginning of time, the equations give us a singularity - basically, a divide by zero....
Rubber is an insulator. Why can balloons hold a static charge?	[ "Most balloons are made of latex these days, but the same principle holds regardless. It is because of their insulating properties that they become statically charged. When you rub a balloon, or any other insulator on another, electron transfer occurs. This build-up of electrons is responsible for the static shock ...	[ "Food Scientist here: Looked up the ingredients online but could not find the exact ingredients for the icing. However I will give it my best shot. It has too do with the amount of solids that is in the icing (mainly sugar and corn starch). The sugar will bind to the water, and will keep the water from forming very...
Why do statutes of limitation exist?	[ "It's to stop frivolous wastes of time. For most crimes, there's a certain point where the crime just doesn't matter anymore. Also, defendants have the right to defend themselves, and if it happened a long time ago they may not be able to produce exonerating evidence (because it may have been lost, they may have fo...	[ "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_" ]
If the constitution protects a citizen's right to bare arms, why are there certain types of knives (switchblades) that are illegal?	[ "A lot of our constitutional rights have limits on them. For instance, there is the right to free speech, but there are still laws against slander, libel, or saying things that cause immediate danger (like yelling \"fire\" in a crowded area). Arms are the same way - you can't own fully automatic weapons (without go...	[ "Basically, instead of responding to your argument, I make up an easier argument to fight, pretend that it's what you mean, and respond to that instead. Typically the fake argument (the \"straw man\") is a more extreme version of the original argument, but not always. So if you said something like \"I think we shou...
how does the nutritional value of food change as it's cooked?	[ "There are parts of food that cannot be broken down effectively by our digestive system alone. For example, the cell walls of vegetables can't be broken by our stomach or intestines. Chewing helps but because the cells are so small, it doesn't help much. But when you cook it, those cell walls are broken open from t...	[ "The main reason is the way the atoms/molecules behave When applying heat to something, you increase the kinetic energy (speed, since mass is constant) of its particles. A heavier particle needs more energy to speed up by the same amount. Another application of that is rotation. When applying (input) heat you expec...
Just as we can create and manipulate an electromagnetic field, is it physically possible to create or manipulate a gravitational field?	[ "Why without mass? You can't create an electromagnetic field without charge. Anyway, to answer your question we can create gravitational fields by putting lots of heavy stuff in one place, as Cavendish did when he measured the gravitational constant. Gravity is indistinguishable from acceleration, so we could mimic...	[ "We aren't really sure why, but it doesn't seem that something like that can be done. Think about it like your bladder; you can build up a need to urinate, but you cannot urinate so much that your bladder is more than empty." ]
Difference between parole and probation?	[ "Parole is a supervised period after being in jail; probation is supervison without jail time." ]	[ "[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." ]
Why you wake up when you get close to dying in a dream	[ "I use to have a dream where I died and would just float for a while above my body. It was incredibly unnerving . I imagine though you would wake up from the increased heart rate and adrenaline in you system from the fright of the dream though." ]	[ "To confirm that you're ready. What if the game just started and something came along and killed your guy?" ]
Why is it that people can't eat most raw meats without getting food poisoning, but carnivores can?	[ "Ahh, but you are capable of eating and digesting raw meat. It'll take a bit longer to digest than cooked meat, and won't be as tasty, but there's nothing about it that your digestive tract cannot handle. Your ancestors ate plenty of raw meat. We are warned against eating raw meat because where meat it processed ca...	[ "Cats and dogs are faster breeders and their offspring can become adult and self sufficient much faster then human babies. It's a bit like the \"quantity vs quality\" thing: humans are much more complex than cats and dogs especially when it comes to the brain, and so they need much more time to develop. So cats and...
Why were the Janissaries Shia Muslims?	[ "The Bektashi order is not Shi'a. They're a bit more syncretic than other Sunni Sufi orders, in that they revere Ali and his family more than is common, but to classify them as Shi'a would be a mistake. See Taşköprüzade's entry on Hajji Veli Bektash in his \"Shaqa'iq al-Nu'maniyya\". He's very adamant (in the 16th ...	[ "Or would you put it down to factors such as the Army, Parliament, the Major General rule, religion at the time?" ]
What causes an animal to be "albino" and why is it always super rare?	[ "It is not super rare when compared to genetic abnormalities, there are a lot of ways the melanin synthesis pathway can break. Look at this [biosynthetic pathway](_URL_0_) or this [simplified version](_URL_1_), if one of those enzymes (the arrows here) mutate the organism might survive but lose the ability to form ...	[ "They are nocturnal and evolved to navigate by the light of the moon. But this smaller brighter moon is much much closer and messes with their internal compass." ]
How are games with huge open worlds made?	[ "Sometimes it's all designed by a person, sometimes it's generated by algorithms, sometimes it's a mix of both. Minecraft worlds are procedurally generated. There's an algorithm that generates them based on an initial \"seed\" value. The first two elder scrolls games worked in a similar way. The world in Elder Scro...	[ "SDK (source development kits), modding tools, 3D design tools, audio production software and many other means. To explain it in detail would overwhelm you." ]
How exactly do therapy dogs work? How do they provide a form of therapy?	[ "People with PTSD often have trouble relating to other people and become withdrawn. A good dog is basically always happy to see you which can make someone smile. They don't judge you if you wake up with a night terror or cry in the shower or get pass out drunk because you are stressed out. They give you something l...	[ "Governments give tax breaks and subsidies to corporations to lure them in to their area. The idea is that bringing that business to the area will, ultimately, bring more business and jobs to the area which, theoretically, will bring jobs to the locals and more tax revenue for the government. Again, theoretically, ...
Was 'The Black Prince', Edward, Prince of Wales (1330-1376) of mixed race?	[ "No. His nickname came either from his black armor or his personality. To top it off the nickname was only used 150 years after his death! And if you look at his genealogy you will notice that all of his ancestors are from typical european noble stock." ]	[ "Depending on a lot of different variables, DNA has a half-life in the neighborhood of [500 years](_URL_2_). DNA from 1665 would be relatively fresh, then. For comparison's sake, the oldest complete genome (to the best of my knowledge) came from a 700,000 year-old [horse](_URL_0_) that was preserved in permafrost. ...
Why can't we make a dinosaur like in Jurassic Park?	[ "The simplest answer I believe is how life cannot be grown in a test tube. When something is cloned, it has its DNA put into a female of the same species. Because there are no T-Rexs walking around, there is no way to replicate one. OR: Scientists saw the movie and realized there would be dire consequences." ]	[ "We are already doing it! Engineered proteins have been made on an industrial scale for ~ 30 years in the biopharma industry. The first recombinant protein treatment was approved by the fda in 1982 _URL_0_" ]
Why are automobile engines made with cylindrical pistons?	[ "The function of the cylinder is to contain a little gasoline explosion, directing the force out in on direction (moving the piston). A round shape is the strongest shape for containing the explosion, because it has no weak corners to crack, or weak flat areas to bulge out. A linear shape (a cylinder rather than a ...	[ "Basically they all start from the oil we pump out of the ground.All of these things are inside that oil. We then heat the oil in a large tube that has many different levels. As the oil heats up all the different parts become a gas at different temperatures and they settle in the level where the temperature is cool...
What specifically occurs when you select the "Remove USB Safely" Option?	[ "The most important thing is the the computer checks that all pending writes are completed, and no programs have files on the drive open. If all of this checks out, it closes down the background programs that are used to access the disk, and removes it from the list of available disks (together called 'unmounting'....	[ "Its all CYOA. The company making the product can't advertise that it kills 100% bacertia. This is because of human error. If someone uses their product the wrong way, and gets sick, they can sue the manufacturer for false advertising, and in this society, they stupid person would probably win. Same thing with The...
Why do lionesses leave the safety of the pride to give birth?	[ "One of the major causes of cub mortality is from infanticide by male lions during a pride takeover. Very young cubs (e.g. a few weeks old) are far more likely to be killed by a male lion during a takeover compared to a [cub that is a little bit older](_URL_0_) (Pusey & Packer 1987). When female lions retreat to gi...	[ "Hello everyone, Unfortunately, we have already had to remove a number of poor quality responses in this thread, including many asking about the deleted comments, which merely compound the issue. If you're here to answer the question, please make every effort to answer the question, not talk about the show, make...
When was it decided that WWI and WWII were world wars, and who determined when they were deemed over?	[ "Well Germany used a word, Weltkrieg, which basically means World War. When they used the term, they were referring to a sort of apocalyptic struggle that would determine what country would dominate the entire world. When WWI broke out, most countries did not call it World War. Britain, France, and Russia referre...	[ "The world currently adheres to the Gregorian colander, which sets the year 1 AD at the believed birth year of Jesus Christ. (The calender does not have a 0 year, it goes from 1 BC to 1 AD) Anything before that is marked as BC or Before Christ. (Or BCE for Before the Common Era) Anything after is marked AD or Ano ...
What happens when I cut a magnet in half? Are the two smaller magnets weaker than the original?	[ "All magnets have a north and a south. When you cut them into 2 you will have 2 magnets each with a North and South but weaker field. Magnets are composed of tiny magnets that work together when aligned in the same direction." ]	[ "This question is pretty tough to imagine. Here's something that might help: Imagine you live on a [Möbius strip](_URL_0_). You're facing straight down at all times. You leave a ghost image of yourself as you go around the strip. Travel fully around and you get back to where you started, still looking the same way....
How could the Big Bang singularity have been infinitely dense?	[ "You're right and that article is taking liberties. The \"big bang\" theory doesn't say anything about the \"instant\" of creation; the theoretical cosmologists studying it start a small amount of time after when there \"would be\" a singularity." ]	[ "How to you put all the matter in one spot and at the same time not condense it? That violates quantum mechanics." ]
Why do the batteries in my phone and laptop heat up when I use them?	[ "Two reasons, one, batteries have an internal resistance, and when current flows through anything with resistance, heat is produced. The second reason is that batteries work through a chemical reaction, one which is not 100% efficient in producing electrical power, some energy is lost to the creation of heat. Charg...	[ "Metals are good conductors. Microwaves induce a current in these metals. Depending on the geometry of the conductor, the voltage might be very large across certain paths through the air -- especially if there are two pointy ends of metal with a small gap between. It may be easier for current to cause dielectric br...
How does cancer spread if it is not a virus or a bacteria but just a mutation in a single cell?	[ "Cancer is a broad class of diseases that have one thing in common. The cells in the body that are cancerous are unable to stop dividing. So in the simplest case, the tissue simply keeps growing. The more dangerous cancers (the ones that spread) acquire multiple mutations that allow the cells to not only keep divid...	[ "Every time you make a copy of a cell, there is a chance for errors. For example when you photocopy a first print, it is pretty crisp and close to the original, but there are a few minor discrepencies. Now if you photocopy the copy, it gets more distorted, and so on until some letters get hard to read, it gets diff...
Why is the Iron Cross an acceptable symbol?	[ "My personal experience does differ from yours in that I have seen people get flak for using the symbol. In any case, it undeniably has more public usage than the swastika. This is because the swastika was an explicitly Nazi symbol, while the iron cross had been the symbol of the German army since the late 19th cen...	[ "Follow up: When did 666 become widely seen as The Devil's Number?" ]
Why does smoking cigarettes "stain" everything with the smell but marijuana goes away rather quickly?	[ "Because cigarette smokers tend to smoke more frequently than marijuana smokers. so the smell has more chances to build up." ]	[ "Crops are a lot less diverse than weeds. When we develop a crop, we plant the exact same plant over and over again. In extreme cases like the Cavendish banana (the one you probably eat), all the plants are genetically clones of each other. So if one disease works against one plant, it would like work against th...
If we could disregard civic disturbance, would planes flying at a lower height be more or less efficient?	[ "Planes are generally more efficient the higher they can get - the shorter distance is trivial for a 7km difference on a radius of 6570 km, while the vastly decreased air resistance at altitude is a huge benefit to both speed and fuel economy. The strong winds can be a great help in one direction, and relatively ea...	[ "Data. Pure, gooey, delicious data. Seriously though - the Airlines are collecting data on a massive scale. If they notice an uptick in travel to/from one city they will use that information to update how their resources are distributed." ]
How elevators know what floor to go to and how they stop perfectly nearly every single time	[ "A certain number of rotations of the gears causes a specific change in height of the elevator. This isn't something that has any drift to it, it's pretty constant on the kind of scale we care about. A little tuning and you have it set with all the heights. Not much to it." ]	[ "Hey, I can answer this! So here's how it works: internally, the game has each question and answer stored in some kind of [tree structure](_URL_0_). Question nodes have children, answer nodes do not. That's why the game starts off with really generic questions, and gets more specific as the game goes on. The game j...
(kind of NSFW) Why my testicles ache if I get sexually excited for long but do not ejaculate at the end?	[ "Educated guess here. Lots of blood and lubricating fluid builds up in all the \"tubes\" of your genitals when you sexually excited, and the tubes expand a bit for better flow. The \"plan\" is all that fluid is expelled in an ejaculation, then all the blood flow goes back to the rest of your body and all your \"tub...	[ "A number of sperm cells die each time when freezing. You just need a small number to survive, and the survivors can still carry out the job. In fact, you only need 1 sperm cell out of trillions. Unfortunately, this doesn’t work for whole humans. 70% of a live human is still a dead human." ]
how can someone open a credit card under my name.	[ "Did he actually open it under your name? If he did, you would see the bank summary and transactions as far as I know. He probably added you as an authorized card holder to one of his accounts. I have cards from my parents that are like that" ]	[ "I do monitor multiple sign ups from the same IP on websites. We trigger a flag for the admins when we get 50+ signups in the same day from that IP. Then it is reviewed by humans because for all we know it could be a school." ]
How long have humans been celebrating birthdays?	[ "The Romans certainly celebrated birthdays- not only for individuals but also for the founding of temples and cities (what we might call annual celebrations or anniversaries). [Cicero](_URL_2_) references the fact that his daughter's birthday (natalis) coincidentally occurs on the birthday of a local temple to Sa...	[ "It is sort of evolution. You start out with our ancestors cracking open eggs and slurping the liquids inside. Some other ancestor found wild grass seeds and chewed on them. A third one saw a calf drinking from an utter. A fourth one found salt either in a cave or on a rocky shore. A fifth one ate some sugar beets ...
What is causing the background static/white noise being heard in VHF signals?	[ "Mostly, it comes from the circuits inside your radio. Real world components are not perfect, and they introduce noise. Thermal noise is another factor. The random movement of matter always causes some white noise in a radio. You can reduce this by operating your radio at temperatures closer to absolute zero, but o...	[ "[Standing waves](_URL_0_) If you shake a string at right frequency \"knot\" points will form that stay stationary. This is due to the wave created by the shaking and the wave reflected from the other end interfering with each other. Video: Standing waves on a string _URL_2_ Objects that are more complex than a st...
Why is it so hard to consciously act normal?	[ "Doing any work effortlessly involves using muscle memory or \"cached memory\" gained through former experience. Thinking about it consciously throws the system off and puts extra \"load\" on the brain and requires more processing power. For eg. a good way to throw a player of his game would be to make him think a...	[ "Imagine you're trying to find a coffee shop in a city. If you've been there recently, it should be pretty easy to find. If it's been 10 years since you've been to the coffee shop or the city, it might take you a LONG time to find. It also might take long to find if you've been to other, similar coffee shops in the...
Behaviorism and how it is used to teach/educate children	[ "For very young toddlers who are barely starting to develop a sense of reasoning, basic negative and positive reinforcement is pretty much the only way to instill elementary parameters of proper behavior, mostly for their own safety and that of others (telling them \"good job\" when they put on weather-appropriate ...	[ "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...
why water molecules are known to have a slight adhesive effect, but you can slip on a puddle of water	[ "They adhere to eachother, but the force isn't particularly strong. It's a lot weaker than the friction forces that would normally exist between your shoes and dry pavement. By obstructing that contact, they're reducing friction by a lot." ]	[ "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...
How is dying after stinging someone an advantage to bees evolutionary?	[ "The life and death of individual bees matter very little in a hive of bees. Workers are not involved in reproduction, so their death in preserving the rest of the hive - more importantly, the reproducing parts (drones and queens) - is actually advantageous. It follows the concept of the selfish gene. Their deaths ...	[ "_URL_0_ In summary: * The immune response has to kill some of your own cells because the pathogens are hiding inside. * Histomine causes your blood vessels dilate which also leads to some swelling * Cytokines make you more sensitive to pain Weakness and pain are probably not disadvantageous as it could slow the sp...
What is the significance of the location of a gene?	[ "The topolgy of the DNA is very important. Well-regulated genes may be affected by the same regulating proteins, which means they must be in close proximity to one another. This does not mean that they are adjacent to each other on a linear stretch of DNA, but that they are close to one another when folded and wrap...	[ "It's pretty much nutrition. An example of the effect this can have is the difference between North and South Koreans. North Koreans are definitely shorter than South Koreans, even though the two groups are quite similar genetically, primarily because they eat less, and less good, food." ]
How does Germany and Japan handle atrocities of WW2 like concentration camps and Unit 731 in their history books?	[ "Not a historian but I have been to both countries. Germans are very ashamed to even give you directions to the concentration camps. Japanese still sell some comic books and even video games aggrandizing WWII. The Germans make education on such atrocities mandatory, the Japanese do so much less." ]	[ "Nuclear engineer here. 1, U235 absorbs neutrons of much lower energies than 238; the spectra are almost exclusive. That's why you need moderation (= slowing down the neutrons). Fast neutrons 'ignore' U235, slow neutrons 'ignore' U238. 2, Now how exactly would you 'add' U238 into enclosed, solid state ceramic fuel...
Does using a credit card really boost your credit rating? If so, how much of an effect does this have?	[ "Some of the answers to this question are disastrously wrong, and reflect commonly held misconceptions and misinformation. Credit cards are a mystery to many people, shrouded in magic and myth as to how they work behind the scenes and how to leverage them to your advantage. I highly suggest you go over to /r/person...	[ "They actually debunked that, same with that nonsense about listening to classical music in the womb making your child smarter. It was all just BS to sell some cds. I'll see if I can find an article about it, and I'll edit this to put it in. And now to see if this answer is long enough, or if it will get auto-modd...
Why aren't sperm cells killed when frozen for preservation?	[ "Human cells, when frozen, all cellular functions are slowed down near zero/still.. Including the process of cellular death, which is a physiological process that depends on enzymes and energy. So, the sperm is caught in a time freeze... can not live or die... until rewarmed back to the living world" ]	[ "Many. Malaria plasmodium parasites, for example, have two stages to their life cycle one that occurs in mosquitos (sexual reproduction) and one that occurs in the bloodstream of humans (asexual reproduction and maturation). Without either stage, without entering either host, the parasite will not reproduce. If a m...
The stages in a lawsuit.	[ "Civil (private person/company v. private person/company) or criminal?" ]	[ "The \"Pixel\" takedown notice has nothing to do with patent trolls. That was DMCA abuse. Both DMCA abuse and Patent trolls have been fairly significant issues for several years." ]
What causes the urge to "hug" a pillow while sleeping?	[ "Crushing loneliness when knowing it's the only thing you can hug." ]	[ "Changed the flair from \"Earth Sciences\" to \"Psychology\". Although φ is not my field, I believe you will find a large part of your answer by researching the concepts of \"imprinting\" and particularly of \"cuteness\" (no, really - it's a thing; at least the way it was defined by Lorenz it is...) and the researc...
In Stanley Kubrick's "Full Metal Jacket", an American soldier indiscriminately guns down Vietnamese civilians from the helicopter. Did this kind of blatant killing of civilians happen in the war? Was this scene accurate?	[ "Hello everyone, Unfortunately, we have already had to remove a number of poor quality responses in this thread, including many asking about the deleted comments, which merely compound the issue. In this thread, there have been a large number of incorrect, speculative, or otherwise disallowed comments, and as such...	[ "hi! in addition to /u/Jack_of_all_offs' link, here are a few more related discussions you may find of interest * [To what extent was the Tiananmen Square movement actually motivated by democracy?](_URL_1_) * [I've just read that there was no massacre of students in Tiananmen Square on June 4th 1989. What's the dea...
How does the moon create ocean waves?	[ "If you are talking about ordinary ocean waves, it doesn't. The moon causes the tides (which are technically waves), but the waves you see on the ocean are caused by wind, not the moon." ]	[ "Wifi and cellular systems use microwave radiation (like your microwave oven, except far far less power). Microwave radiation rips absorbed quite readily by polar molecules like water and fats. (this is how microwave ovens cook food, imparting the energy of microwave radiation into kinetic energy of water and fat m...
How long time did it take for a piece of silk to get from China to Rome via the Silk Road?	[ "I'm not sure how long it would take for the piece of silk, but it's 4,600 miles and takes at least half a year to travel if you're just traveling it, according to the New York Times. \"(The Silk Road) s some 4,600 miles long and takes at least half a year to traverse. And it passes through regions whose temperatu...	[ "The \"Confucius Genealogy Compilation Committee\" maintains a family line for, you guessed it, Confucius, [going along the main line of descent.](_URL_0_) As Confucius lived from the 6th-5th century BC (and the line actually goes back a bit further than Confucius), this is a very ancient line to say the least. I'm...
How is an American 18 year old student, fresh out of high school, even remotely allowed to start taking on $5,000+ in debt every year for the purpose of higher education?	[ "Questions about the US are generally better in r/askanamerican." ]	[ "Infants and children need bonding and attachment. When they get hurt, they aren’t sure what to do and rely on the adults around them for comfort and care. We as adults teach children that it’s ok to fall and get back up from it to keep going. It’s what we were taught as children and now as adults it’s easier to st...
Why Toaster Strudel frosting packets don't freeze in the freezer?	[ "Food Scientist here: Looked up the ingredients online but could not find the exact ingredients for the icing. However I will give it my best shot. It has too do with the amount of solids that is in the icing (mainly sugar and corn starch). The sugar will bind to the water, and will keep the water from forming very...	[ "The secret parts of the recipe are the methods of preparation, and the amounts of each individual ingredient. All they have to declare for USDA regulations are the relative amounts of each ingredient, and certain things (\"natural flavors\") don't have to be directly specified. As far as keeping it secret inside t...
I know there was at least a discussion amongst the British to use blankets as a vector for spreading smallpox in N. America, in 1760s. What about purely European conflicts? Does biological warfare make any notable appearances in 17-18th century, at least as an idea?	[ "As a follow-up - Conversely, do accusations of conscious spreading of a disease make their way into the propaganda of European continental conflicts?" ]	[ "Wicca did not exist during the crusades. It was invented during the 20th century and is an amalgamation of (supposedly) pre-Christian pagan beliefs. One of Wicca's core beliefs is that witches were not satanic: they were practitioners of pre-Christian religions, so traditions were carried through time and persecut...
Why are cars made with the capability to go at 100+ MPH when the speed limits are usually about 70-75 MPH (in the United States)?	[ "Because taking 30 seconds to get up to highway speed would suck ass, and depending on what you are doing with the vehicle (hauling cargo, towing, driving up steep hills etc) you might need the extra power. Also there are times when it's fine to go as fast as you want l, like if you like taking your car to private...	[ "In pharmacology the figures of [EC50](_URL_3_) and [IC50](_URL_2_) are measures of how much of a substance is required to induce a desired effect or to inhibit function. These numbers vary a lot depending on the site of action, nature of the pharmacological compound, type of interaction, etc. It is all covered und...
What is the difference between psychological science and psychology? And what is the difference between psychology and sociology?	[ "All psychological science is psychology but not all psychology is science. Some psych is more qualitative and clinical than quantitative and empirical. Much actually. If you go to the American psychology associations site you will see over 59 divisions. Some are highly scientific-others not so much. Psychology stu...	[ "Another question, to flesh out certain aspects :How was trading with Mexico different during the war was the south trading more with Mexico from sheer proximity? What was the south's/the U.S's view and relation on Mexico after the war? (how did it contrast with before?)" ]
why can puppies consume mothers milk but lactose is bad for them?	[ "Puppies, kittens and AFAIK all other mammals can process lactose when they're young. This ability is lost after the young are weaned so only adult animals are lactose intolerant." ]	[ "_URL_0_ \"The Milwaukee protocol (MP), a procedure reported to prevent death after the onset of rabies symptoms, has been performed over 26 times since its inception in 2004 but has only saved one life. Overwhelming failure has lead health officials to label the protocol, a red herring.\"" ]
How did the American accent become different to the original settlers' English accents?	[ "It's the English accent that probably changed the most. The way the English spoke in the 17th century is not the way they spoke from the 19th century through to today. The way the settlers (and the 17 century English) spoke would be more like you'd find in various east coast places from Boston to Atlanta. Accents...	[ "From what I've read they ate a lot more rough course foods. Chewing things that are hard scrape our teeth for us kind of like it does for other animals. The problem for our modern teeth is we eat a lot of soft refined foods and a lot of sugar. That stuff just sits there and gets stuck which causes tooth decay." ]
Why do most big trucks adamantly say "NOT FOR HIRE" (box trucks, U-haul, big rigs etc). Who are these lawless people in the streets attempting to rent trucks at whim?	[ "DOT regulations have very different requirements for a private vehicle and a for hire vehicle when you get to medium duty and heavy duty vehicles. They are required to display either the commercial DOT licence number, or a large not for hire sign." ]	[ "They are not exactly synonymous. There is a distinction, especially in urban planning terminology. Road is just any type of traffic surface. Street is a road in a city or other built environment. Avenue is a street with trees on the sides. Boulevard is a large avenue with multiple lanes of traffic and trees on the...
What exactly is happening when you "learn to bike"?	[ "And what causes the learning to happen \"instantly? First you do not know how to ride, then snap and you do." ]	[ "I don't have a ton of experience with Bitcoin, but AFAIK, you can download a wallet app, meet with someone and exchange cash for Bitcoin (you pay cash, then simply transfer the bitcoin to your wallet by snapping an image of their QR code), and walk away. You completely bypass any bank, that's the entire point of B...
Did Ming-era Chinese recognize European Jesuits as belonging to the same religion as Nestorians who had arrived 900 years earlier?	[ "Followup: What relationship, if any, did the Chinese perceive between each of these groups and Manichaeans?" ]	[ "Could you perhaps present us with your original source so we can see what the author writes about it? I think I know the answer, but I would like to know what exactly the author wrote. Also, could you remove the bonus question? We do not allow discussions of events after 1993." ]
Are all meteorites and asteroid gray like seen in the pictures? if so, why?	[ "Well, [here's a picture](_URL_0_) of a pallasite meteorite. These show up with green areas because of the minerals present. A lot of what we find in meteorites is iron and nickel, and those are both gray/silver, and so that does skew meteorites somewhat to the easy ones to identify." ]	[ "Do you mean for example a steak will go red to brown when opened? Yes the sealed trays contain a 'modified atmosphere' to make the meat stay red, as it is exposure to oxygen which turns the meat from red to brown. I've done a quick Google but can't find specifics for which gases are used. The colour on its own ha...
Why does there only seem to be help for children/young adults, or the elderly.	[ "> Whenever I look up help for suicidal feelings, self injury, eating disorders etc, national suicide prevention hotline: 1 (800) 273-8255 self harm hotline: 1-800-366-8288 eating disorder hotline: 1-847-831-3438 (Not trying to answer your question, just making sure you have these for your friend)." ]	[ "People who see things happen call up the news and say, \"Hey, you should come down here and cover this.\" Organizations that are having big events issue press releases that say, \"Hey you should come down here and cover this.\" Really big organizations have regular (daily, weekly) press briefings that they don...
How does Netflix profit by releasing an entire season of a show at once?	[ "Sometimes the better business model isn't to exploit your customers as much as possible, but to actually offer what your customers want. People like having the whole season available at once. The image/reputation of a company has long term advantages in terms of profits." ]	[ "[This](_URL_0_) article might help you see how the prices can be so low. If you compare to, say, Walmart, Walmart has to pay for the physical space of their stores and all the employees working in the front of the stores. Like Amazon, they also pay for their website and their warehouses. But Amazon lacks the costs...
What exactly is happening when a side ache happens when running?	[ "As we inhale, air enters our lungs and our diaphragm moves down. When we exhale, our diaphragm moves up. Running pushes/shoves around the internal organs, creating a noisy and crazy environment for the bone-connecting bands that attach to the diaphragm, often resulting in sudden pain/sudden muscle jerk or cramping...	[ "We aren't allowed to give medical advice. This is because none of us here can properly examine and diagnose you over the Internet. Go see a doctor." ]
In the beginning, the universe was created. This made a lot of people very angry and has been widely regarded as a bad move.	[ "The very creation of the universe causes people to fight." ]	[ "We can divide divide spacetime into regions bounded by your forward and reverse [light cones](_URL_0_). The region of spacetime inside your forward light cone is the \"absolute future\", meaning that all observers agree that these events have not happened yet. The region inside your backward light come is the \"ab...
When an electron of an atom goes to a lower energy state does energy emitted have any specific direction?	[ "It depends on what caused the electron to return to ground state. In [spontaneous emission](_URL_1_), the direction is random. In [stimulated emission](_URL_0_), the emitted photon will have the same phase and direction as the photon that stimulated the emission." ]	[ "When you shoot an arrow from a bow, the energy of the bow is transferred to the arrow. It gradually (doesn't seem like it, I know) pushes the arrow downrange, from a full stop at full draw, to full speed when the arrow leaves it. All that pent up energy of the bow at full draw is efficiently transferred to the arr...
Prior to the knowledge of electricity, what were static shocks called?	[ "Have a look at [this](_URL_0_) earlier answer by /u/hillsonghoods!" ]	[ "Hi there, not to discourage further comment on this topic (the origins of \"chivalry\" are interesting), but there have been quite a few threads about PTSD in the premodern world. These may be of interest for you as you wait for more comments: _URL_0_" ]
How can a ruling in a Washington state court overrule executive action?	[ "It was not a Washington State court. It was a Federal Judge who lives in Washington State. There is a very big difference. As to how the Federal Judge can overrule an executive order? That is one of the purposes of Federal Judges and the Judicial Branch's check and balance against the Executive." ]	[ "By using advertising disclaimers like \"limited quantities\" or \"while supplies last\", which in many states exempts those items from raincheck laws." ]
Why is asking what someone makes considered such a personal question?	[ "Because if it becomes widely known that you make significantly more than your social circle, you might have people asking you for money, people jealous of you, etc... But if it becomes widely known that you make significantly less than your social circle, you might be looked down upon, and be viewed with pity, ...	[ "To get you to spend $29.95 on their \"work from home\" information package." ]
In terms of germs, does wiping off a surface (without a cleaning fluid) actually do anything?	[ "Technically yes, you can wipe superficial bacteria off. But there are many more that can just as easily disregard your pitiful paper towel and stick to wherever they please, hence why washing your hands with soap is such a good idea. You could even clean the surface of your teeth by wiping them, yet the spaces be...	[ "It depends on the type of touchscreen. The touchscreen on an iPhone uses the conductivity of your skin to determine where you touch (which is why you can't use it with your average pair of gloves). Considering the screen is glass (on an iPhone at least), it would take a long time for you to wear through that by dr...
Why are our keyboards Qwerty?	[ "QWERTY keyboards were designed for typewriters, the design was made to avoid people from pressing two keys too quickly after one another to avoid the typewriter from getting jammed. QWERTY is what people got used to and now its what everyone uses. There's another type of keyboard that was designed to allow users t...	[ "[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." ]
How do prisoners remain fit without any proper equipment and diet?	[ "You can stay fairly fit by doing basic body exercises such as push-ups, sit-ups, crunches, jumping jacks, etc. A lost of Prisons even have gyms and outdoor areas. In addition, they still feed the inmates, they're not starving to death. They also aren't eating junk food such as McDonalds or Potato Chips. If they wa...	[ "Since it looks like this will go unanswered by an actual historian, I'll point out that weightlifting is not a modern invention. The classical Greeks were famous for weight training, and we do have some artifacts from them, but they were dar from the only ones. [This](_URL_0_) is a good (non academic) overview. I...
How do "trademarked" names work?	[ "They are the first to trademark it, although they likely have to prove they're using the trademark, and they MUST police the trademark themselves (make sure nobody else tries to use it anywhere else). If they fail to police their trademark, and it can be shown that the infringer has been using the trademark for a ...	[ "Here is a great video explaining it. _URL_0_" ]
What's that joke that went around amongst pilots during WWII where the punchline was "if you see nothing, it's the Luftwaffe?"	[ "It's not a joke among pilots, but among ordinary soldiers. The joke is from late in the war, and the point is that the Gemans had completely lost air dominance. > It was with good reason that Eisenhower had categorically stated in a D-Day briefing to the troops: 'If you see fighter aircraft over you, they will b...	[ "The posted comments are right, I'm sure, but I think that there's another issue. You never start counting something at zero. If you have five elephants and you're going to count them, you don't say zero elephants, one elephant, two elephants...etc. You say one elephant, two elephants, three elephants, four elephan...
Why can my mobile phone record a video with 24 frames per second while the same camera can only shoot 3 photos per second with a similar resolution?	[ "Because it's not similar resolution. 1080p video is about 2mpx. Still shots from the same camera are likely 4-6 times that." ]	[ "Imagine that someone hands you a sketchbook filled with drawings, and tells you to flip through them quickly to give the illusion of motion. That's displaying a video. Imagine that someone hands you a blank sketchbook and a pencil, and tells you to flip through the pages and draw exactly what he tells you to in re...
If a human enters earth's atmosphere they burn up at terminal velocity. Why don't we burn up upon reaching terminal velocity when skydiving?	[ "Terminal velocity is based on the density of the air. Normal skydivers are jumping from an altitude where the density is only slightly lower than on the ground. Therefore, the terminal velocity is around 120 MPH. If a human were to enter the earth's atmosphere from space, the terminal velocity would be much higher...	[ "Imagine your perspective from a car, in every aspect. Your vision is taken up almost entirely by the car, and not the road. You are focused on the road, but in reality, most of your FOV is the car itself, which relative to you, is not moving. You are also feeling the air inside the car, not the outside air. Howeve...
What time do they use in space?	[ "The ISS operates on UTC, which is the same as GMT. The astronauts and cosmonauts launch from Kazakhstan, which is UTC+5 or +6 depending on the time 0f year, since they don't observe DST. Once onboard, they transition to UTC. All visiting spacecraft are set to UTC as well so they arrive during the crew's \"daytime\...	[ "Nøt sure how old it is but in my country, norway, we oftes say \"with/against the sun\". (With the sun being the same as with the clock). Quite independent of any mechanical apparatus." ]

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