Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
Unrepentant: Kevin Annett and Canada's Genocide	[ "You might want to be more specific about what exactly in the documentary you speak of." ]	[ "Asian cultures did expand into North America. Migrations from Sibera and Alaska were particularly notable. The Thule started colonizing Dorset lands as late as the 1200s: _URL_1_ There are no written records of any of this, so it has to be pieced together through archaeological evidence. No ones even really sure ...
What exactly does the UK mean by "killing encryption"?	[ "All information transmitted over the Internet could be decrypted at government request. Things like private Facebook groups, stored email, online transactions, that C4 you bought from a Tor store, you know, stuff terrorists might do. It's government trying to harm everyone, not just the very unfortunate very few t...	[ "Disclaimer: all of my knowledge comes from genetic algorithms in the realm of computer science, not biology. This argument doesn't seem to apply to biology, as the probabilities of modifying the coding DNA shouldn't decrease, but it's interesting. In computer science genetic algorithms, a lot of noncoding DNA prot...
How powerful would a magnetic field need to be to cause damaging effects to a person?	[ "search askscience for a better answer but it would have to be very strong, I think there might be affects before you get strong enough to make the dimagnetism of water what kills you" ]	[ "It varies, but not much individually. The problem is when everyone does it. It's kind of like why you're taught not to pick a flower from a garden when growing up. You alone, picking one flower, is not going to be noticed, it's not going to affect the plant or garden overall, but if everyone picks just 1, very s...
Why does it hurt when you bite your nail too close too the pink part?	[ "Underneath the nail is living tissue, the nail bed. This tissue exists to support & hold the nail to the finger, and there's blood vessels, nerves, and collagen in there that doesn't want to be damaged. Deeper down at the base of the nail is the nail matrix which is the part that grows the nail itself, and dee...	[ "Food takes time to reach the stomach, and you'll notice if you eat and then wait you'll be less hungry. Chewing more simply takes more time to do, and so you get full with less food" ]
Why do dragons show up in so many different cultural myths/legends/religions?	[ "I suggest you examine the List of Popular Questions. Here's a link! _URL_0_" ]	[ "Imagine country A has laws that are intended to encourage new businesses, and so the laws there make is hard for old businesses to claim \"Hey we did that first!\" or \"Hey, that almost the same as what we do!\" Suppose country B has laws that are meant to protect that country's companies, and stop cheap-o foreign...
What physical property makes certain materials transparent or translucent?	[ "Take a clear grocery bag, and stretch it. Starts off transparent, becomes translucent. In this case, some of the tangle of polymer chains that make up the bag line up and the result are these microscopic regions with more crystallinity that scatter light. So the bag looks cloudy and translucent -- still lets some ...	[ "I see this question on here maybe once a week. Basically light hits the water and is knocked into different angles. Then hits the object and bounces off it, hits the air and again gets knocked at different angles. So there’s less light reaching your eyes from that object. Or so every explanation I see here says (t...
When did servants become too expensive for the middle class?	[ "Given their wage rates and persisting popularity, I'm not sure they have become \"too expensive.\" Middle class Americans still resort to 2.5 million domestic workers that include maids, au-pairs and caretakers for elderly family members. Most of them now come from South America and especially the Philippines, the...	[ "I feel like this question is a bit outside of this subreddit's scope, it's really more of an economics question, plus if you look at [this graph](_URL_0_) then you can see that they were at very similar levels until around 20 years ago when they diverged, so anything following that violates the subreddits 20 year ...
Where are our memories stored?	[ "Currently evidence strongly indicates that memories are encoded in the pattern of connections between neurons ad the synapses between them. Each neuron in your brain gets input from many other neurons, usually at the end of thin tentacles called dendrites, and outputs to one or many neurons, usually at the end of ...	[ "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...
This, Quantum levitation thing.	[ "Look at [this picture](_URL_0_). Pretty much gets the idea across. The lines in the picture represent magentic field lines. Note how the disk is sorta \"pinched\" between them. In that fashion the disk is held in place." ]	[ "Technically the [Leidenfrost effect](_URL_0_) meets that criteria, since the liquid droplet is suspended by its own vapors." ]
Apart from "building credit" what are advantages for credit cards?	[ "Depending on the card, you can get rewards like cash back or credit towards travel. Also allows people to buy something they may not be able to afford immediately, by essentially financing the purchase and creating a payment plan (for better or worse)." ]	[ "If you don't like spending more money than you have to, you'll only buy a car big enough for your needs. A bigger car is more expensive, and uses a lot more gasoline than a little car. You wouldn't buy a big SUV if you didn't need it. Lean muscle mass burns energy - it's expensive for our bodies to build it, and k...
In TV and movies, when ever a police officer enters a dark house or room, they never turn on the light switch but instead they use their flashlights. Why is that?	[ "Another reason is that messing around with light switches in an unfamiliar house might be too distracting when in a situation where you might be attacked. Light switches can also be triggers for bombs, or hold evidence; just shining a light doesn't disturb the scene. You would hate to smear the bloody fingerprint ...	[ "Several insects navigate using the position of the sun (and moon) as a reference point. Sun is relatively stable on the sky, only moving as the earth revolves during the day, so when you move 100 meters in one direction, the sun is still in the same place relative to you. But if you have a lamp and move 100 meters...
How do animals eyes cope with wind resistance at such high speeds. Eg. Falcons or Cheetahs	[ "They have a [nictitating membrane.](_URL_0_) I've been reading up on birds ever since klenow introduced me to their respiratory system a few weeks ago. This is probably not all of the relevant information, but it's what I'm able to contribute." ]	[ "Legs would be blown into the windshield. [Here] (_URL_0_) is a youtube video showing exactly what would happen." ]
Why is it sometimes hard to respond to a really bad, or just plain stupid argument?	[ "You can debate somebody if their facts are wrong or their reasoning is wrong by correcting them. Some people are just so ludicrously wrong (possibly intentionally so) and devoid of logic that there's no place to grab into that you can fix their understanding because their entire worldview is completely fucked. *...	[ "Point a flashlight at a wall. You know the flashlight is delivering 'x' energy to that circle. Tilt the flash light at an angle. Now the circle stretches out into a bigger oval right? But it's still just delivering x energy, so there's less energy per unit of 'area.' The sun hitting the earth impacts things the sa...
[Geology] What did continents of earth look like during the Cenozoic era?	[ "Well we live in the Cenozoic right now - here's a map of the Earth 30 mya. _URL_1_ If you want more maps here's a great resource! _URL_0_" ]	[ "It would help a lot if you could answer a few questions: 1) Which countries do you mean by \"coastal Asia?' A majority of Asian countries have a coastline. 2) Are you primarily interested in the history, the languages, or the culture?" ]
Since many plants die in the winter, does outdoor air quality significantly decrease during those months?	[ "I don't think the effect is immediately noticeable to everyday people, but climate scientists have discovered that the seasons play a role in global temperature and carbon dioxide content of the atmosphere. If you watch The Inconvenient Truth, one of the graphs Gore uses shows temperature as a slowly increasing si...	[ "It's because of sensory adaptation. If we're honest about the situation then we realize that going INTO a casino or a smelly car is just as likely to grab out attention. Sensory adaptation is what happens whenever your brain is exposed to the same stimulus for an extended period of time. So if you're inside for an...
israel and land claims	[ "Unfortunately, this a very wide area. Land claims take many different dimensions. I'm willing to discuss them all, but I don't want to flood you with more information than you want. I'll divide it up like this, you tell me which you'd like to know about, and I'll answer where possible: 1) Who controlled the area t...	[ "Hebrew University announced today they found a seal bearing the name of King Hezekiah. _URL_0_" ]
What have we discovered aboard the International Space Station and why should we care?	[ "Well most importantly how to survive in space. But if that doesn't grab you here is a list. _URL_0_" ]	[ "A lot of experiments to see what happens when there is little to no gravity going on. How it affects human body, how it affects, plants, animals, bacteria, equipement ect. It's also much easier to set up experiments that require very cold temperatures or very low pressures. [Here's a list.](_URL_0_)" ]
Is there any membrane that allows gases to pass but blocks liquids?	[ "Gore-Tex and similar stretched teflon membranes are famous for having that property. But from what I understand it only works with mixtures of gas and water, so raindrops and splashes and things like that, and if the membrane is completely wetted it'll still block the liquid but no gas will pass through either. So...	[ "Aluminium foil is not going to be permeable to cooking oil. You can test this yourself by making a foil bowl with no holes in it and sticking it in the oven and just cooking that for a while. Either you have holes in your foil or it is leaking over the sides. In either case, oil under the foil will tend to spread ...
Given current technology, what is the fastest space probe humans could make?	[ "There was Project Orion from the 1950's that was projected to reach 3.3% the speed of light (theoretically). _URL_0_" ]	[ "only if it's structure is perfectly non-[amorphous](_URL_0_) so that it wouldn't start contorting with the inertial effect commonly known as the [centrifugal force](_URL_1_). This would rule out glass and many plastics Also it would have to also be in a perfect vacuum so that air resistance, or friction with the a...
How to start investing money in the Stock Market.	[ "Save up about $1000. It needs to be cash, and it needs to be money you don't need for your basic necessities. Open up a door, go outside, put it on a hard surface and then set it on fire. Congratulations, now you know how the stock market works." ]	[ "Here is a [fantastic video](_URL_5_) from a great YouTube series. The series is about the author does a fun, informative bit about every major historical topic. The episode I linked above explains how Islam started and what the branches of Islam are about. It really is a great watch, its like 10 minutes long and ...
how commonly known would the story of the Iliad, have been in the second century BC classical world?	[ "A cup with a depiction of a scene of the Illiad was found in a grave of the first century AD in Denmark. I guess they knew what the scene meant." ]	[ "Check out this thread [here] (_URL_0_). It should provide a glut of answers as well as links to other threads on the same topic. The simple answer, however, seems to be that yes, there was an awareness of the toxicity of lead, at least among intellectuals." ]
What does it mean when my "connection is limited"?	[ "It typically means you are not connected to the Internet, but you have (at least some) access to local network resources. For example, computers on your home network can communicate and share files with each other, but you can't access an external website. This is typically the result of: - DNS configuration probl...	[ "Imagine driving a long distance on the road. Your destination is 160 miles away, so you drive along the highway at about 80mph and figure that you need about 2hours total. Then, in the middle of that 160mi, the road gets very bad (you had no chance of knowing that) so you can drive only 50mph. You don't know if th...
What's the difference between Hebrew, Jew, and Israelite?	[ "Hebrew- 1. The spoken/written language of the Hebrew people. 2. The Hebrew people were descendants of the biblical Abraham. 3. If you are familiar with the story of Moses, you will remember that the Hebrew people were being enslaved by Pharaoh. Israelite- 1. Technically, one who is a descendant of the biblical fig...	[ "The id is your desire for this cookie. (::) The ego is your practical plan to get this cookie. (::) The superego torpedoes your plan because it's my cookie, and stealing is wrong. Munch." ]
why do lips get chapped in cold weather compared to hot? Doesn’t the hot air absorb the moisture more?	[ "Hot air does make moisture move more, but that also includes nearby water sources, making the air more humid. The higher water content of the warm air doesn't suck from your lips as much as the very dry cold air. Plus, when it's warmer, you're sweating more, applying moisture more directly." ]	[ "The temperature sensors in your skin can only detect relative changes in temperature. Not absolute temperature. You can show this by doing a simple experiment with three cups of water. one cup of ice water, one cup of room temperature water, and one cup of hot water. Place a finger of your right hand in the ice w...
- Do Bees know that losing their stinger kills them?	[ "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...	[ "I'm more of an ecologist / entomologist in training than a botanist, but [this](_URL_0_) might help. The grass on your lawn certainly isn't like fungus and it isn't one big colony. Each grass plant has a few blades, but each grass plant is an individual. If you let your grass grow long enough (your neighbors woul...
Do octopuses have specific limbs that would be arms and legs or are they all the same?	[ "Your question also made me wonder about a follow up; do octopodes exhibit handedness? I found this cool article: _URL_0_ In it it also says: > Favourite arms are usually at the front of the animal, the team found. Meanwhile an octopus's rear limbs tend to shoulder much of the burden of locomotion, making them alm...	[ "> injured members The word you're looking for is _extremeties_ Working under the assumption that you're talking about amputation, the surgeons always try to preserve as much of the affected extremetie as possible. It depends on how much, and how exactly, the body part has been damaged, but they always try to amput...
When the moon passes in front of the sun we experience an eclipse. We are in the shadow of the Moon. Why don't we ever experience being in the shadow of Mercury, Venus, or artificial satellites?	[ "The reason we experience a solar eclipse is because of something called \"The Solar Eclipse Coincidence\" The Moon happens to be about 400 times smaller than the Sun, but the Sun happens to be about 400 times further from the Earth than the Moon is." ]	[ "If you imagine producing a dark matter particle at the LHC, just think about what would happen to it. The whole point of dark matter is that it interacts very very weakly with normal matter, so the particle would fly right out of the detector and we'd never see it. This shows up in the data analysis as missing ene...
In WWI, had France crossed through Belgium ignoring their neutrality to get a one-up on Germany, would the Treaty of London have Forced Britain to attack France?	[ "The treaty was joint, not several, so it really did not oblige Britain to attack any one. It was more moral indignation that played a role in British intervention." ]	[ "Brunei was supposed to join the Federation of Malaysia, which is a federation consisting of Malaya (itself a federation), Singapore, North Borneo and Sarawak. However, it faced a rebellion on its own front, the [Brunei Revolt](_URL_0_). Further, a referendum was held in each territory and the Bruneians didn't seem...
Why does it take up to 10 business days for a direct deposit to be processed.	[ "you deposited a check. not direct deposit. direct deposit is a specific form of deposit used by employers to dispense pay roll. all you did was use the mobile app to deposit a check. when you deposit a check, the bank sometimes places a hold on it to verify the check is legit. because if it's not legit they take t...	[ "Are DoD Employees working again? Yes, and No. A large portion of DoD has returned to work, based on the legal interpretation of POMA [(Pay our Military Act)](_URL_51_) by the Secretary of Defense. In short, civilians that are considered to be \"helping/supporting the military\" were told to report back to work...
When condoms are listed as 99% effective, is that per use? How is that number determined?	[ "Condoms come along with a small information package that tells you what the failure rates are. Here is an example: \"Pregnancy rates for birth control methods. (For one year of use in the United States)\" For \"Male latex condom\" it states 2% for \"Lowest Expected Rate of Pregnancy\" - so it means that if users d...	[ "A simpler explanation of why one-time pad encryption can't be cracked: Let's say our adversary is sending encrypted text messages in English. With most encryption systems, you can try decrypting that message with every possible key. Most keys will just give you random-looking characters, and one will give you a pr...
why is carbon monoxide (CO) poisonous while carbon dioxide (CO2) is mostly harmless, despite only differing by one oxygen molecule?	[ "The shape of carbon monoxide molecule and the electron bonds holding it together mimic the oxygen molecule well enough for it to take its place in the large molecule that carries oxygen in the blood. If carbon monoxide blocks the site, the oxygen doesn't get to the cells. Carbon dioxide is completely the wrong sha...	[ "Coca-Cola Light and Diet Coke are different names for the same product in different countries. Coke Zero is a different drink. Diet Coke isn't just a sugar free variant of Coca Cola - it has an entirely different recipe, and so it has a different taste. Coke Zero, introduces in 2005, uses the same formula as Coca ...
How is it that certain bodyparts "fall asleep"?	[ "You've put enough pressure on a nerve or nerves somewhere along its path so they stop working properly. And the brain can't tell the foot what to do or really feel what happens to it since the nerve isn't working. This is sometimes called \"pinched nerve\" even if it isn't a proper medical term. From the [Institut...	[ "From what I understand the nervous system doesn't really do anything differently per se. I think it's more a matter of which part/parts of the brain are sending the signal. I believe the Medulla is what normally controls things like breathing, but once you start doing it consciously, it may be that more frontal lo...
How do we know plastic takes 100s-1000s of years to decompose?	[ "If you know that something degrades by X amount over a certain amount of time, you can extrapolate how long it would take to completely degrade. Similar to a half life" ]	[ "This comes from Malcolm Gladwell. He is a pop psych writer and no one should listen to him. The [10,000 hour deal has been debunked](_URL_0_) in a study." ]
How do jet fighters (modern day) dodge missiles?	[ "The most important way they dodge missiles in modern air combat is to not get shot at. That means, taking out anti-aircraft before sending in planes with long range weapons (on aircraft or ground/sea launched). Using stealth to get in fairly close and attack more conventionally. Or using a \"stand off\" weapon, su...	[ "Star Trek has some battle scenes that has craft all on differing headings and axes. I think the Battle of Wolf 359, vs the Borg was a good example. But I agree. It seems that they always rendez vous eye to eye" ]
If Voyager 1 is traveling at 60,000Km/h then how is it not destroyed by a collision with even a tiny meteoroid ?	[ "1) The speed relative to the Earth and the speed relative to the micrometeoroids isn't the same thing; those little bits and pieces can be traveling at whatever speed they currently are at, which will be all over the place. 2) Space is rather empty, so while the damage would be high and bordering on catastrophic, ...	[ "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...
How far are we from a cure for HIV/AIDS?	[ "Viruses in general does not have a cure. There are vaccines but they only prevent infection and does not help after an infection have manifested itself. In some cases it is also possible to help the immune system combat the virus with immune strengthening drugs but this is limited. The issue with HIV is that it in...	[ "Xenotransfusion has been attempted in the 1600s, with mixed results, with sheep blood. Ape and chimp blood might work, as would pig blood as they all have similar Rh factors. Source: _URL_0_ Also, dog to cat transfusions can be done, bit only once as the cat will make antibodies to the blood. Also, apes, dogs, ca...
ELI5: Why does it take 60 seconds for some sites/apps to figure out that I entered my password incorrectly, but it only takes a few seconds if I got my password right?	[ "As a security measure some sites will deliberately implement a delay after a failed authentication attempt to inhibit brute for attempts to get into the account." ]	[ "- If you want to predict the weather for Nov 1st, and the simulation gets you the result on Nov 23rd, it's pretty useless. - While the simulation runs, people wait for the results. Salaries are expensive; computers, less so. So, you want the computers to give the results quickly so that highly-paid people can cont...
What causes a PSU that blows up to also sometimes take other PC parts with it?	[ "The PSU is the \"power supply unit\", so when it \"blows up\" you could have transient voltages making it to the motherboard, hard drives, etc. The job of the PSU is to convert 120 V or 220 V AC to the 5V and 12V DC that the computer parts use. When the PSU gets shorted or damaged, you could have 120V dumped into ...	[ "WEAKNESS LEAVING THE BODY PUSSY!! no, jk Its the \"fight or flight\" response you may have heard about in school. Your body just went through a trauma of being pushed pretty hard so your bodies response is \"oh shit, im about to fuckin die. I better eject all this preworkout and protein semen shake so I dont have...
Why does water boil in a vacuum?	[ "Water boils at a given temperature for a given pressure. If the pressure is reduced the temperature, or energy, needed to cause a boil is reduced. A vacuum would need very little. Try taking some really hot water that hasn't reached a boil yet, placing it in a glass tube with a plunger. If you pull on the plunger,...	[ "As the OP have mentioned in a comment above, fast moving fluids, in this case air, have lower pressure. Animals breath by expanding the chest cavity which causes the pressure surrounding the lung to lower. This causes the higher pressure outside air to rush in and inflate the lung. But if the pressure outside sudd...
Why is it cheaper to add phone service to a bundle?	[ "It make their subscriber numbers look more impressive which helps their stock prices. It psychologically helps customers think they got a good deal, which makes them less likely to cancel service. It also makes it a bigger pain in the ass for you to cancel service because it adds hassle to you having to find repla...	[ "You may have a flag on your account that says you qualify for the promotion while he doesn't. If you've had your account longer, have better credit/payment history, or if he's locked into another kind of contract he may get different offers. Basically the computer looks at all the accounts and says \"Accounts with...
why do colleges and even high schools emphasize plagiarism so much	[ "The issue with plagiarism isn't that you're getting your ideas from elsewhere, it's that you're taking credit for those ideas and passing them off as your own (even if in some sense, they were). Sourcing other people's work in the text is the important part, not abstaining from doing extraneous research." ]	[ "Well, let's look at this through a metaphor for a minute. Can I cook something that's truly original? After all, the ingredients that I will cook with are the same ingredients that have been used for many other dishes over the year. And yet, chefs \"invent\" new dishes all the times, or find new ways to make fair...
We have "click to play" for flash why don't web browser have "click to see" for image	[ "Videos are a lot more disruptive than still images. moving pictures, forced audio, etc. Plus, most of the time you don't want a video to play until you're actually ready since you'll miss something. Not so with an image. Also, the whole Click To Play for Flash is a somewhat new thing, and stems from Flash being r...	[ "Simply put for the same reason drinking water when you're not thirsty isn't as refreshing as when you're REALLY thirsty. Anticipating the bodies' needs doesn't trigger the same reward responses in the brain as fulfilling a need that is already present. Your muscles don't NEED to stretch right now, so you can't ant...
Why are fish only able to grow to a specific size, depending on the size of their tank?	[ "It's a myth. Fish don't grow to the size of their tank. Their growth may be somewhat stunted by things like poor water quality due to the undersized tank, but they don't magically adjust their growth to fit the size of the container, and in any case, it's a serious health issue and not something that should be con...	[ "Simply put for the same reason drinking water when you're not thirsty isn't as refreshing as when you're REALLY thirsty. Anticipating the bodies' needs doesn't trigger the same reward responses in the brain as fulfilling a need that is already present. Your muscles don't NEED to stretch right now, so you can't ant...
How do we know what other planets/stars are made of?	[ "[Emission Spectra](_URL_0_) Sorry I dont know how to answer the question more thoroughly." ]	[ "We dont, but if you would have an item that gathered carbon out of the atmosphere for the last few thousands years you could check how the ratio was changing. We use very old trees to do that, the oldest living one is around 6000 years old and It's a bristlecone pine. Also antarctic ice could be used to further an...
Why do they use a helium/oxygen mixture when scuba diving? Why not normal air?	[ "[To avoid the bends](_URL_0_): nitrogen from 'normal air' gets into the bloodstream at high pressures, but then bubbles out when pressure drops; helium doesn't have that problem, and, being a noble gas it's not reactive with other elements, so Helium doesn't have any other major health issues from breathing it, it...	[ "It's all about having an atmosphere, since that's what helicopters need to fly. [This article explains it quite nicely ](_URL_0_) Here's a relevant quote: *\"Elysium was that—unlike an airplane cabin—its atmosphere wasn’t canned up in some hollow tube. A landing spacecraft could enter its air like it would on Eart...
How does water become super heated or super frozen without actually boiling or freezing? How can it still be in a liquid state?	[ "When water freezes, the Hydrogen atoms are relaxed enough to go from forming bonds with 3 neighbors to 3.4 neighbors. In order to do this, the have to rearrange - rotate slightly. Say you're a water molecules, which way do you rotate? If your neighbors all agree to a direction, the choice is obvious, if not, you ...	[ "This wiki should answer your questions: _URL_0_ At the critical point, the properties of a gas and a liquid converge such that you have one phase. The critical temperature is the highest temperature that 2 phases can coexist, the critical pressure is the vapor pressure at the critical temperature and the critical...
What causes the direction in which wind blows?	[ "Wind flows from areas of high pressure to low pressure. The closer the high and low pressure areas are together, the stronger the \"pressure gradient\", and the stronger the winds will flow. Others will certainly be able to add to this." ]	[ "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." ]
why are car batteries already "good enough" that they haven't changed much while all other battery technology has improved?	[ "Car batteries require a very powerful, but short burst of energy to get the engine started. This is very different of what we expect of other battery use cases: small size and long endurance. In that sense a car battery acts more like a capacitor than a battery. Therefore car batteries are still lead-acid based i...	[ "Dynamic range. Your eye can resolve a candle a mile away at night, or the sun shining on white walls at noon, basically at the same time. Phone cameras are more limited, and tend to adjust for the brightest object in the field of view. That tends to darken everything else relative to your eyesight." ]
Why Apple laptops are so expensive compared to their PC counterparts.	[ "If you buy a high end PC, you pay roughly the same as a Mac. The difference is that Apple doesn't make low-end products." ]	[ "It's completely preposterous, I'm afraid. \"Conventional\" medicine is a science that will adopt new treatments if they work and discards those that do not. Steve Jobs died because he left a cancerous pancreatic tumor essentially untreated for nine months." ]
If a person stands up too quickly, they sometimes blackout and or fall over. Why?	[ "ELI5: When you make your head higher it takes a moment for the blood to catch up to it. ELI10: When you stand up it's harder for your blood to reach your head because it wants to fall down into your legs and feet. Not enough blood to the brain = dizziness or even lights out. Normally, as you stand up your body com...	[ "I don't so much think of it as an evolutionary thing. There's really no benefit to being confused. It comes down to computing power. Your brain just takes a minute to recall old information/piece together new information to develop an idea of where you are and how you got there. I'm currently in flight school and...
Are there any possible dangers to using solar energy?	[ "I think your concerns of affecting weather patterns, presumably by reducing the heat absorption into the ground, won't be a big issue. Consider the figure on page 12 of [this thesis on solar energy use](_URL_0_). Extrapolating for future growth, and noting that the real distribution would be much more even, the ac...	[ "It depends entirely on the type of contact. The ones I have are designed for me to wear 24/7 (including while I'm asleep) for a month at a time. The main concern is the fact that your cornea (the clear part in front of your pupil) has no blood vessels. But it's still living tissue that needs oxygen, so it actually...
If there are more stars in space than we can count, is possible we would get to a point where we can't look any further due to stars in the way?	[ "Nice work, you've discovered Olbers' Paradox :) This was a much-discussed problem in antiquity. _URL_0_ Take a read of the wiki page, it's very good at explaining. And ask away if there is more you want to know." ]	[ "Try remembering something while staring closely at something and then while staring into the distance. During a car ride through the countryside, mom (who's a doctor) told me to look at the mountains to relax my eyes and brain. Looking closely at objects makes your eyes strain and lowers brain concentration. Sta...
How has Obama fared during his two terms as POTUS?	[ "This is more of an opinion or discussion question than a concept you're looking to have explained. Not really a topic for ELI5. Maybe /r/askreddit" ]	[ "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 /...
Why are racial slurs more frowned upon than gender slurs?	[ "The only time I've ever let someone get by with a \"cunt\" bomb, was when my father, who I'd never heard use that word in my entire 25 years of life to that point, applied it to my sister that had just cost him an extremely large chunk of his life's savings. No one in that room dared say a word after he dropped th...	[ "It's all about relativity. If the Hulk ran for a quarter mile, he'd only appear to be moving a few dozen widths of his body size. If a dragonfly then traveled the same distance and speed, it'd appear to be moving thousands of widths of its body size. So they cover the same distance but relative to their body size ...
What are some good books on ancient letters, texts and other primary sources?	[ "I'm gonna plug two things. The first is the [Book List](_URL_1_) here. You can look into whatever area you're interested in. I think the AH book list is entirely secondary sources, but it's helped me quite a bit. The second is the Fordham [ancient history sourcebook](_URL_0_), which has a bunch of primary sources ...	[ "I don't have the time to answer this in depth, but 1913: The Year Before the Great War by Charles Emerson seems to be exactly what you're looking for. Be careful not to adopt a teleological view of history - even though it's obvious to us that WWI 'will happen', people at the time weren't quite so convinced. T...
Why do transformers have so many coils?	[ "Short answer: inductance. A transformer with an open secondary is a simple inductor. With a sinusoidal source voltage the primary current is proportional to the inductance. Fewer turns, lower inductance, higher current. Calculating the optimum number of turns, wire gauge, and core size is complicated." ]	[ "suppose you are assigned to make sure a big bag of skittles gets eaten. two cores means two people eating, a faster clock speed means each person eats faster." ]
Why people's jaws chatter when they are cold?	[ "It's the same as shivering in general. It's your bodies way of trying to produce heat. The muscles use energy to shiver and that energy use produces heat. When it's your jaw muscles shivering your teeth chatter together." ]	[ "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." ]
Why do people say that bitcoin mining isn't profitable?	[ "> Also, I don't pay for my electric bill Most people do pay for their electric bill, and the amount of Bitcoin you can mine with just a PC is worth less than the electricity it takes to mine it. Even not counting that, running constantly will reduce the life of your computer parts, and the returns are so incredibl...	[ "\"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..." ]
Before 1991, has there ever been a time where there was really only one Great Power? How likely is it that the United States is to remain the only Great Power for long?	[ "The British Empire at its height probably? They controlled the seas and at that time, that meant controlling the world." ]	[ "In the early Roman Empire, Emperors would attempt to maintain the illusion of living in a Republic although they held all the real power and the position of Senator was mostly for social prestige, not for influencing the Empire politically. This was referred to as the Principate, and lasted until roughly 280 AD. L...
What are imaginary numbers good for, and how do they solve problems other types of numbers can't?	[ "Complex numbers are essentially a 2d object packed into one dimension. A complex number is c = a + ib So we can plot them on the [Argand plane](_URL_0_) like we would with a 2d vector. You can essentially think of it as if a complex number contains more information than a real (or imaginary) number. It's a little ...	[ "Let's say you're a game developer, and you wanted to give out codes for people to get into the beta of your game. You decide to do this by giving access to one person to start, and then every Friday everyone in the program can invite 4 friends. So on the initial day, you only have 1 person playing. But after the 1...
If the British monarch had a child while visiting the states, and then fulfilled all the requirements, could that child grow up to be President and the King/Queen of England?	[ "If a British monarch were to give birth abroad, they would most likely have declared whatever place she was to give birth in as part of \"international territory\". By doing so, the baby would be granted whatever citizenship the mother had. This happened in Canada for the birth of Princess Margaret of the Netherla...	[ "In my economic history course there was a comparative study of landownership in pre-industrial France and England, in which differences in the size of estates and smallholdings was due to the fashion in which properties were consolidated or split up through the generations. In France (maybe this held true for else...
Why is the Middle East so violent with its own nations compared to Asia, Europe, Americas, etc?	[ "In general conflict was a part of human history since the first man chipped a stone with another stone. Specifically about the middle east, up until the end of ww1 most of it was controlled by the ottomans, and it was peaceful relatively to Europe that had several major conflict in the span of one century. Once ww...	[ "One thing to point out is the terrain. Iraq is in the populous parts of the country pretty flat, with a semi good road network across the country making it easy to move people around, and larger cities and towns to organize around. Afghanistan is some of the most inhospitable terrain on earth. With little nation...
Will blonde/redhead people really go extinct some day?	[ "Being recessive isn't enough of a reason for a gene to be eliminated from the gene pool. Blue eyes are recessive as well... Genes are only eliminated from the gene pool if they reduce fertility or increase mortality. There are no clear negative effects caused by having red or blonde hair - as a red-head myself I c...	[ "Apart from how crazy this post has become, I want to clarify your question because you seem to be asking about two very separate things. 1. Were (some) ancient Greeks pale-skinned and fair-haired as contemporary native English speakers use those terms? 2. In what way did ancient Greeks 'found' Western culture or c...
Are there limits (low or high) to the frequencies that lasers can emit?	[ "There are technical limitations, especially if you are talking about lasers and not about stimulated emission (the physics lasers are based on). To make a laser you need a resonant cavity and an amplifying medium, both at the frequency you are making the laser. Finding amplifying mediums is very difficult at certa...	[ "Others have already given good answers, so I'll just suggest that you study Fourier Series. A Fourier series is a way of breaking down any wavefunction as a sum of sines and cosines. It takes an infinite sum to get perfect precision, but it is easy to get to the point where a human ear cannot tell the differenc...
How does radiation cause mutations in animals or humans?	[ "When cells divide they make pretty much exact copies of themselves. Introduce radiation to the equation and the copying process goes screwy and the new cell is different. Rinse and repeat over and over and you end up with body cells which are completely different in shape size and function to what they were origin...	[ "Miller and urey did an experiment some 50 years ago. They took basic chemicals and put it in a special flask that simulated prehistoric conditions such as lightning and volcanic acitivty. Macromolecules like DNA, RNA, and fats formed. Probably one of the coolest experiments ever in my opinio" ]
What is the mathematical proof for The Big Bang?	[ "The biggest proof isn’t exactly mathematical but observed. There is a 4 kelvin background radiation uniformly spread everywhere we look. It is thought to be the remnants of the explosion. Nasa actually has a pretty comprehensive list _URL_0_ It was less like someone sat down and did the math and more like someone ...	[ "if 1+1 is 2, why can't I have ice cream for dinner?" ]
Who were the Tarascans?	[ "Did you know that the askhistorians podcast has two episodes dedicated to the Tarascans? [Episode 13](_URL_0_) talks about their origins, and [Episode 14](_URL_1_) talks about their conflict with the Aztecs, and the Spanish conquest. Beyond that, someone like /u/Ucumu or /u/mictlantecuhtli would be most likely to ...	[ "While you wait for an answer to your question you might be interest in [these](_URL_1_) [previous](_URL_0_) answers regarding the slave trade conducted by Arabs and others across the Sahara and the Indian Ocean." ]
What cues do flies use to avoid being swatted?	[ "[They have eyes on the backs of their heads.](_URL_0_)" ]	[ "I notice a lot of these natural selection questions are a lot easier to understand if you question the fate of the opposite, in this case the answer becomes clearer if you ask instead \"What happened to the living things that didn't try their best to produce offspring?\" Well they had fewer heirs and eventually di...
what is the difference between objectivity and subjectivity?	[ "here's the easy way to look at it: objectivity: facts. subjectivity: opinions." ]	[ "Easy, one digs up old maps, one redraws old maps, whilst the other debates old maps until the ends of time. But no seriously, I think that is it at a fundamental level. Archeology seems a lot more hands on though, and therefore the most rewarding I think. I know a dutch specialist in Meso-America. He gets to spend...
Why exactly is it that when siblings (or closely related people) reproduce, there are problems?	[ "It's because lots of defective alleles (versions of genes) are recessive (you need two copies for them to cause a problem) and rare. So they almost never cause problems because it's very unlikely that both parents have the same defective allele. Even if you have a defective allele and pass it to your child, your m...	[ "The movie was [Days of Thunder](_URL_0_) and he was talking about [Slipstreaming or Drafting](_URL_1_). As to your question, this depends on * The velocity of the cars * Geometry of both cars * Atmosphere status (temperature, rain, snow ... although they have very little effect at higher speeds) On the street it's...
If I was in space and manage to enter back to the atmosphere in a very slow way, would I still burn?	[ "No, but you wouldn't be in orbit. The reason spacecraft go so fast when they re-enter is that they have travel around 5 km/s to maintain orbit. Parabolic spacecraft like Spaceship One don't have this problem." ]	[ "Yes but you need a really really accurate scale. And it needs to be the right kind of scale too, a balance is not affected by local gravity (as long as there is some gravity). A balance would give you the same weight even on the surface of the Moon as it does on Earth. Things like [local gravity anomalies](_URL_0_...
Pointers in Programming?	[ "Memory locations in a computer are accessed by their address. This address is just a number: you can think of them like individual street numbers on a VERY long street. Sometimes different programs or parts of a program need to use the same data. Instead of sending all the data, it is easier just to send the addre...	[ "Within the Milky Way galaxy, position can be computed relative to known pulsars. Once you have your position, navigation becomes a matter of doing the same for your destination, relative to those same pulsars and yourself." ]
How do you weight a black hole ?	[ "Masses of supermassive black holes are estimated by studying the motion of very close stars, which is affected by the hole's gravitational field which in turn depends on its mass. In the case of the Sombrero galaxy's SMBH the existence and the mass estimate were deduced based on the high speeds observed for the st...	[ "One reason is that we have not had a reproducible way to measure mass that ties it to more fundamental units. There is effort to fix this in the form of the [watt balance](_URL_0_), which measure the mass of an object in terms of electrical units with more fundamental definitions. In order for this to become a ne...
Why are smart phone cameras lacking an IR filter?	[ "Because somewhere in design phase, a product engineer or a product manager said....no we aren't going to put one in. Why they did that, because they're cost constrained, not convinced of the benefit, didn't find a good vendor, etc etc etc." ]	[ "It costs money by private cell providers to implement that system,. And there's no profit to be made. The only reason they would do it is if the law demanded it and the gov was going to pay to costs of it." ]
Why does Pakistan not recognize Armenia as a sovereign state?	[ "When the Soviet Union dissolved, both Armenia and Azerbaijan declared Independence, and continued their war over the dispiuted Nagorno-Karabakh region, put on hold when there were absorbed into the Soviet Union in 1918. Nagorno-Karabakh had also declared independence from both. The UN currently recognizes it as pa...	[ "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 /...
How do civil engineers calculate how much weight a bridge can hold?	[ "There's a class in college called \"statics\" and \"dynamics\". Where you learn about how much weight various materials can support and what happens if the weight is applied at an angle and how you can add support with cables and such." ]	[ "It depends. In the US and other 1st-world countries, you can use tax records, asset prices (assets are stocks, real estate, etc.), salary data and other freely-available data to come up with a good guess. Other countries might require some more guesswork, but the principle is the same." ]
Questions about the speed of light	[ "1. No, you would see it moving away from you at the speed of light. (Eerie, right?) 2. No, they would record the same speeds. Most importantly, the theory of relativity does not distinguish between being \"stationary\" and moving at a constant velocity. When you really think about it, what does being stationary e...	[ "The formula E = mc^(2) holds only when in the rest frame of the particle (or system of particles). A single light particle has no rest frame, and so it's not the correct formula. The full formula, valid for all particles (massless or not) and in any frame is E^(2) = (mc^(2))^(2)+(pc)^(2), where p is the mo...
What is the definition of observation (in a quantum mechanical sense)?	[ "An observation is just an external interaction. It's not quite the same thing (there exist interactions which do not count as observations), but for most purposes you can treat them as the same. So the fact that something interacts with the inside of the box is what causes the superposition to collapse. Of course,...	[ "When you add two spins of 1/2, you can make either 0 or 1. When you then add a spin of 1/2 to zero, the only possible total spin is 1/2. When you add 1/2 to 1, the possibilities are 1/2 or 3/2. So the possible spins for a three quark system with no orbital angular momentum are 1/2 or 3/2. If the system is made of ...
How can the HDD in my laptop last 5-10 years, yet I have had to replace 2 HDDs in my Synology NAS within the last 2 years?	[ "You probably are buying cheap non enterprise grade drives that aren't meant to be on 24/7" ]	[ "A couple factors: Age, Location, history * Age: Rome was founded almost 3000 years ago. The colosseum was built almost 2000 years ago. In that time materials physically fail (wood rots, concrete erodes). People also broke roman structures down for materials from time to time * Location: Rome...
When did we start to bury our dead?	[ "Might get a better answer over at [/r/AskHistorians.](_URL_0_)" ]	[ "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...
How does a B-2 Bomber fly and maintain stability without a vertical stabilizer?	[ "The B-2 uses what's called a split rudder to maintain yaw stability. [Here](_URL_0_) you can see the split rudder in operation. Each split-rudder is actually two separate panels that swing out opposite vertically of each other. When the left split-rudder opens it produces drag and causes the B-2 to yaw left into t...	[ "Edit: STSCI people have [posted an explanation](_URL_4_). There's also a [youtube video](_URL_3_) which explains it around 1:45. The long and short of it is that Hubble was tracking background stars throughout those images, and its orbit around the Earth meant that the comet had noticeable parallax which cause...
How come in North American colonial political cartoons there is almost always a dog present somewhere in the artwork?	[ "Could you provide an example of what you are referring to? I don't think I've ever noticed dogs in early American political cartoons, but I do know that dogs both domesticated and semi-feral, were common fixtures of both urban and rural life in the 18th century. Dogs in art could imply both servility or loyalty, ...	[ "Mate, you're going to need to come up with a better example. That JFK cover is from 2013, ahead of the 50th anniversary of his assassination, a time when folks were inclined to overlook JFK's flaws. The 1968 Nixon cover is an allusion to the popular belief that Nixon lost the 1960 presidential election because of...
Do pet pythons recognize their owners and show any animal traits that dogs/cats do?	[ "Ball pythons, and most pythons can't see very well. They rely on heat and smell. So if you smell of a mouse and are warm blooded (your hand for example), you are asking to get bit. Other than that I had a very loving 12yr old ball python and she never struck at me or anyone that came close." ]	[ "Brains easily perform many, many tasks hat are difficult for computer. Take that we know brains are optimized for pattern-finding. Consider intelligent life forms have to interact with a real 3-world and real time. Which means they can check their expectations. Testings a supposition is as simple as rotating an o...
Why does high levels of hunger sometimes make me nauseous or even make me throw up?	[ "When it accompanies hunger, especially extreme hunger, nausea is typically a symptom of mild to moderate hypoglycemia. Sometimes, this can be an indicator of developing Type 2 diabetes. If you experience it again, I would get your blood sugar checked. If it is below 70 mg/dL, you might be in trouble. (Although thi...	[ "Your mind relies on two senses to judge where your body is in space and how it's moving: your sight, and something called the vestibular sense, which relies on the structures of your inner ear help determine motion. Usually, those two things agree with each other, and everything's fine. But let's take the common...
Did the pyramids or any other ancient tombs actually have elaborate traps or is it just a Hollywood thing?	[ "Apparently things like false doors were more common so that robbers would waste a lot of time trying to dig into a wall with nothing behind it. It's a lot easier to make a false door than some kind of mechanism with a trigger and moving parts." ]	[ "A follow up question for when this is answered: if it is possible to make one, would it be possible to mass-produce? I’ve heard of Roman “fast food”, so the concept was there, but if someone went back in time with the knowledge to do so, would it be achievable to get a Roman McDonald’s chain up and running?" ]
Why does my radio go static when I turn towards it or move my hand in a specific way?	[ "The radio waves are interfered with by a large bag of water. The bag of water is your body." ]	[ "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." ]
How is it that the US economy flourished and expanded so extraordinarily during the late 1940s and 1950s when the government was so burdened with war debt?	[ "The USA was more or less the only fully intact industrial economy. We supplied everything. To everyone." ]	[ "Generally, a country will only choose to go to war if they believe that the benefits of winning are worth the losses they will take getting that victory. The thing about the Cold War is that there were very few upsides to any potential conflict and a mountain of downsides." ]
Why does it takes a year or more for a movie to be released after filming, but a TV show can be released within two months after filming?	[ "My guess would be that editing a film takes a lot more time then editing a TV show." ]	[ "The human brain is great at recognizing patterns and is very used to making predictions about the environment. For example, due your experience, when you're walking in the street your brain tells you \"people are walking in a certain direction and they're going to keep doing so\". When you experience something new...
Why do most animals store more fat in the belly than in other body parts?	[ "Well, what are the alternatives? On your head would either snap your neck or impede your vision, so we only store a little there. Same with the arms and legs. At some point you won't be able to move at all. Hands or feet would be even worse, as that would make it impossible to walk or grab anything. The Butt is a...	[ "Because the beer and pizza is instant gratification. You spend the money and you get the item and enjoy it. With the clothes, you spend the money but won't necessarily wear the items right away. So you put them in your closet and wait to wear them. Since there's no instant gratification you are subconsciously not ...
Was there ever a King to directly lead a given attacking army into battle?	[ "If you go back in time there certainly was. A classic example would be the battle of Agincourt where the English king Henry V led his army from the center of the battle line. You can read \"The face of battle\" by John Keegan for a fine account of the battle including many kingly deeds performed in the thick o...	[ "Federal courts can issue orders (but don't always - for instance cannabis is federally illegal, but the executive has decided not to enforce it, bit messy). These can be enforced by various legal means, much as they would be enforced against a company or individual. Note that until the courts decide a case, the st...
Why, if the moon is rotating, do we only ever see the same side of it?	[ "Because it's orbiting at the same rate it rotates. Imagine someone circling you, but turning so that their front always faces you anyway. Technically we don't see the same side, though. The orbit's not totally regular, so you can actually see about 58% of the moon's surface over time." ]	[ "Usually a movie set is relatively brightly lit while everything else is in as close to total darkness as possible. This acts to reduce the amount of light which can bounce off them, then off things on the set in order to be visible to the camera. Also eyes just really aren't that reflective. Look closely at your e...
If quarks are too small to observe with current technology then how do we know so much about them?	[ "Through a process known as lepton scattering. Leptons are smaller, simpler particles like electrons that are not made of quarks. When leptons are shot at a hadrons, particles made of multiple quarks, they bounce off in a way that indicates there is some sort of structure within. This is analogous to Rutherford sca...	[ "Because we can predict their passing in the sky with accuracy (diabolical accuracy might I add) That is the power of Newton's mathematics. (Next time your kids ask you what is math good for this is a good example: math can explain and predict basically everything that is going on in the universe) By calculating i...
Why do we perceive temperature in air differently than in water?	[ "Ability of the material to transfer heat. The better its thermal conductivity, the faster it can become very, very uncomfy when it has another temperature than you and is in contact with you. e.g. 200°C air in oven - > no problems for a couple of seconds. 90°C in water - > 2nd degree burns within seconds." ]	[ "We are endothermic and have a high metabolic requirement--one that is further stressed when we are submerged. Animals with gills, on the other hand, are almost exclusively poikilothermic and require much less oxygen. For us, the challenge is getting enough oxygen from the water to sustain our metabolism." ]
What exactly are the 4th and 5th dimensions, and how would they look to us?	[ "The fourth dimension is typically believed to be Time. If the 3D universe is Height, Width and Depth like a cardboard box. Hang the cardboard box from a wire, the wire represents a timeline. If you slide the box down the wire, each centimeter can represent one second of time. You move the 3D object in the 4D spac...	[ "I love this question. There is a movie called Waking Life that addresses this idea. The whole movie is on YouTube right now for free and is awesome. Check it out. But at the minute 40:35 is when your question gets talked about. _URL_8_" ]
Was the night sky clearer before electric lights?	[ "Absolutely! In fact, a few years ago an astronomer named John Bortle created a scale to quantify the interference caused by light pollution on the visibility of celestial objects ([Bortle Scale](_URL_0_)). Sadly, there are few places left on Earth where one can observe the heavens as our ancestors did before the i...	[ "It's debatable. How do you compare the environmental impact of burning gas and adding more CO2 to the climate change problem with the possible environmental impact of lithium ion technology production? They're not really the same thing, so economists and environmentalists will have to look hard at the ramification...
What purpose do neutrons serve in atomic nuclei? Why are they necessary?	[ "First a semantic point. Atoms do not exist to serve a goal. The neutrons do not \"serve a purpose\" because there is no purpose to the whole thing. Anyhow, neutrons allow the atom to be stable, by distancing the protons from each other a bit. They are spacers. _URL_0_" ]	[ "I don't have your exact answer but a relevant fact: nuke plants are considered slow to start and stop, and are therefore treated as part of the baseload (left on for long periods of time), while other types of plants (such as natural gas, hydroelectric) are pretty quick to adjust and are used for most adjustments....
The difference between an symphony, concerto, sonata, and waltz etc and so on.	[ "/r/classicalmusic will be happy to help further and provide some good examples. A symphony is a large work, commonly four movements (sections) long. A series of any movements for any instrument is called a suite. NB there is a pause between movements which should never have applause! A concerto is a work for a s...	[ "Ask Reddit is for personal opinions, stories, and the like. Essentially subjective answers to questions without hard answers. Something like \"whats your favorite food\" is a good post there ELI5 is for getting a simplified answer or explanation to a question that you don't understand. A good thread here would som...
Why is it that big semi trucks last for hundreds of thousands of miles, but some cars start breaking at just about 100,000?	[ "I myself work in the mining industry in australia. Recently was at a site near coober pedy in the middle of nowhere. Maintenance is a big part of it. The road trains we had are tri-drive kenworth 908s or something but would do 6 trips a day so close to 600kms a day from site to rail siding and back a few times but...	[ "Where were you in Europe? Any climate that doesn't freeze will have great roads, and climate that freezes will have bad roads, and anyone that has warn and cold snaps during the winter will have horrible roads." ]
So what exactly happens when your foot falls asleep? Why does it hurt?	[ "Lack of circulation leads to lack of oxygen in the tissues. The peripheral nerves are the first ones to be affected by lack of oxygen, especially the sensory nerve endings. They basically stop sensing things (heat, touch, pressure). The feeling of your foot being \"asleep\" is actually the feeling of having very l...	[ "It's the same thing as being in a car for an extended period of time. While you aren't really making a lot of big movements, you are making a very very large amount of tiny movements. Every second you're adjusting, balancing, making sure things are going smoothly, watching all of the people, etc - so while y...
Why is yawning so "contagious", to the point where we need only hear or see an image of a yawn to do it ourselves?	[ "Yawning and stretching increases blood pressure and preps our muscles for activity. Having yawns be shared among a group of animals/humans makes us more alert and prepared, which was probably advantageous to our survival in the past. Watching [Vsauce's video](_URL_0_) may be more clear than my stolen summary." ]	[ "Mirror neurons are a special type of neuron family that fire both when the organisms behavior is performed and when behavior is observed. The simplest to understand type is the motor mirror neuron. These neurons will fire similarly when performing an action (i.e. grasping something) and when observing that same ac...

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