Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
why it stings to pee after ejactulation	[ "Um, it doesn't? I sometimes get the split stream when there are sex juices partially blocking, but that's it." ]	[ "Post-coital tristesse is the term you are looking for! Do a google search and surf around, there are several perspectives, but the most fascinating to me is that the Greeks characterized this phenomenon and discussed it. Aka I don’t have a simple hard and fast answer for you, but that’s the name." ]
Is it true that most common cause of plane crashes in ww1 was poor/ distracted pilots?	[ "[A survey of causes of death in British pilots](_URL_0_) found that 58% died from enemy action while 42% died in operational mishaps including training in the first year of the war. Although some of the crashes are going to be due to distraction and error, there will be others due to mechanical failures and bad we...	[ "Basically, in the 1990s the Internet was exploding. It was new territory and people were scrambling to stake their claims. Websites like _URL_0_, Yahoo, and even services like AOL were making billions of dollars seemingly overnight and with very little overhead. People with a little bit of programming skill were g...
why is it more efficient to produce energy by fusion instead of nuclear power?	[ "Fusion is nuclear power, just a different type. If you fuse together elements lighter than iron they release energy, if you split atoms (fission) heavier than iron they release energy. Fusion is the process which generates power in the stars and generally releases more energy with less harmful by-products than fis...	[ "While there are some organisms with more than 2 sexes, like [Tetrahymena,](_URL_0_) no organisms combine more than 2 gametes at a time. Plants do something sort of close though. Most species of flowering plants use a process called double fertilization. When the sperm (delivered by a pollen grain) arrive at the eg...
How do we solve problems that don't have constant acceleration?	[ "This is literally why calculus was invented! If you’re at all interested in physics you should take it. Algebra-based physics sacrifices a lot to accommodate students’ math skills: the real universe is built out of calculus." ]	[ "Sound was, and is, fairly easy to approximate, even high school students can walk across large fields and measure the difference in time between when they see their friend bang a gong and when they hear it half a mile away, if not ideally farther. The same measurement can be made watching fireworks if you know the...
When 13 people were shot yesterday in Chicago it barely made national news, but when the shooting at the navy yard happened it had full blown coverage _URL_0_	[ "A few reasons. Chicago has one of the highest gun crime rates in the country, so reporting a gun crime there doesn't grab much attention on the national media. Also, The shooting in Washington happened involving military personnel on a military base. The concept of military personnel being made victims is a sensat...	[ "There are several staging areas in studio 8H in Rockefeller center, most of the time the audience isn't straight on, meaning the soundstage isn't directly in front of them. So the only way they can watch many sketches is on the TV(s) mounted on the walls and rails. Other times when the cut happens for the joke for...
If lightning is hotter than the surface of the sun, then how do people survive lightning strikes?	[ "Its related to the amount of time and area exposed. A lightning strike is really quick, and if you were teleported to the sun's surface for that amount of time you would have more issues with the low pressure than the temperature" ]	[ "This phenomenon is called the \"Pain Gate Theory\". When you injure yourself, pain signals travel from the site of injury to your brain. When you do something else to that part of the body, for example rubbing it with your hand, this also sends signals to your brain. However, because both signals are coming fr...
Why was/is Man of Steel so divisive?	[ "The main problem with Superman as a character is that most of the folks writing him in movies stumble over the Jesus allegory and forget that there are other aspects to his character that make him more grounded. The whole \"invulnerable\" thing also gives writers trouble because they can't think outside the box it...	[ "[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." ]
Does relativity mean that as temperature increases, the mass of the particles also increases?	[ "It's best not to look at the \"increased mass\" of individual particles, because that effect doesn't really exist, but rather at the energy of the whole system. If the system increases in energy, its mass increases by E/c^2 . So when a liter of water increases by ten degrees, its mass increases by about 465 picogr...	[ "This occurs for the same reason why the hottest part of the day is usually around 3 PM. To picture this, imagine a pot of water on the stove as the earth and the fire beneath the pot as the sun. The flame is set on high like the months of June during the solstice until the water's temperature reaches 50C. Then, li...
Could we tell there was life on Earth from 40 light years away?	[ "If its orbit did not cross the Sun from our perspective we would not be able to detect life on Earth. All we could see is the Sun wobbling because of the Earth, but the since our orbit is fairly far out, and we are a fairly small planet, we probably would not even be able to detect that at 40ly (though correct me ...	[ "Let me give you an example using a bit of math. If I have a point in 2D space, I need 2 coorinates to describe its position, x and y. The distance to the point is sqrt(x^2 + y^2) Ok now in 3D space I need three points: x, y, z. The distance to the point is sqrt(x2 + y2 + z2). See the pattern? Ok now about about 4D...
When and why did the black death stopped spreading?	[ "According to [Wikipedia](_URL_0_): > An epidemic of plague dies out after a few months because it has no host in which the bacteria can survive. However, that does not mean the infection is not surviving somewhere, in a rodent or flea or warm place, to act as a reservoir, so sooner or later it breaks out again. T...	[ "They kept covered - think long sleeves and broad-brimmed hats." ]
Why does the helicopters on Manhattan heliport have colors around the blades, when you look at them with Google maps?	[ "The blades were likely moving. Photographs from satellites are often composites of several photos taken in different colors. For example the camera would take a picture with all the red, then the green, then the blue and it would be stitched together afterwards. I believe this has to do with how the data is read f...	[ "The lights know your there a couple ways. Most common is what we call an induction loop. Basically copper wire is placed in the asphalt in a loop then a small amount of electricity is fed into that loop of wire. When your vehicle stops over this loop of wire the metal from the vehicle changes the amount of inducti...
How come drinking tea seems to make you pee way more than drinking water?	[ "Not exactly ELI5 but Caffeine (in tea) is a diuretic and stimulates urination. So the ELI5 is... the stuff that gives you energy in tea makes you go pee pee too!" ]	[ "Caffeine is a vasoconstrictor, meaning it shrinks the size of blood vessels in your brain. That's why caffeine is an ingredient in excedrin, and migraine drugs like imitrex are also vasoconstrictors. Shrinking blood vessels in the brain reduces pressure in the brain. Tolerance is the body getting used to this effe...
Why is bird poop white, where as almost all other poop is brown?	[ "Most of bird poop is in fact brown(or green). The white portion you see is the urine in the form of uric acid, as birds do not urinate like mammals do. If you care to know, uric acid is used as a waste product because it is less toxic compared to ammonia(the urinary waste of fish) and Urea(mammals and amphibians) ...	[ "Others have already answered the actual question so I feel like I can be a little pedantic. A meteorite will not leave a contrail because it's not a meteorite until it's sitting comfortably on the ground. We have these three similar words that mean slightly different things. Meteoroid is the smallish piece of roc...
If an object was heated up and placed in a perfect vacuum would it stay hot forever?	[ "no. heat transfers through convection, conduction and radiation. Radiation continues in a vacuum, so heat can leave that way." ]	[ "Scientists are looking for the holy grail of cold fusion. That is fusion that is accomplished without putting in the vast amounts of energy you refer to with multiple laser beams. Even without finding 'cold' fusion, we may be able to start a fusion process going with many laser beams, and then use part of the ener...
Is there any evidence that the dinosaurs were able to "roar" as they do in films such as "Jurassic Park"?	[ "Sort of. As you can see in Jurassic park 3, they can find out the shape of the voice box and get an idea of the nature of their vocals. They probably couldn't work it out exactly, and a lot of Jurassic Park is sort of filled in gaps." ]	[ "Short answer, volcanoes. Even though everything on the surface of the earth was frozen, the mantel was just as hot if not hotter than today, and plate tectonics still took place. All these volcanoes still dumped massive amounts of CO2 in the atmosphere. A green house effect ensued and warmed everything back up. Ov...
What causes 'clumsiness' in people?	[ "Poor [Proprioception](_URL_0_). Proprioception is the term for knowing where different parts of your body are relative to one another, and how you're moving. It's the principle that lets you touch the tip of your nose with your eyes closed, etc." ]	[ "Because you are not paying attention to what time it is. Your focus is on the task at hand. (Space filler because autobot will delete answer) Because you are not paying attention to what time it is. Your focus is on the task at hand. Because you are not paying attention to what time it is. Your focus is on the t...
Why is it widely believed that information is conserved?	[ "Mostly because of time-reversal symmetry. If you lose information, it means you cannot \"rewind\" the movie of the universe while still following the laws of physics - else you allow information to come out of black holes. And as far as we know, the universe is time-reversal invariant (well, CPT invariant but what...	[ "Before I answer, may I ask who the speaker is for this particular lecture? Or if you have a link for me to listen to? I would like to know where they are coming from in their argument." ]
What causes a "headrush?"	[ "In most cases, a head rush is caused by orthostatic hypotension. Essentially, standing up from a sitting or lying position causes blood to pool in your lower extremities, resulting in significantly decreased blood pressure. This, in turn, causes the symptoms you described. Now, normally when your blood pressure ...	[ "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." ]
What does the US gain from the Iran deal?	[ "You have to understand: There was never any \"Iranian nuclear threat\" -- that was just a cooked-up pretext for a war, just like \"WMDs in Iraq\" was just a pretext. There was never any actual evidence of a nuclear weapons program in Iran. _URL_1_ _URL_4_ _URL_9_ _URL_8_ _URL_10_ _URL_6_ _URL_7_ _URL_0_ _URL_3_ _U...	[ "If your next door neighbor is trampling flowers in your backyard, and your much larger, much bigger neighbor from across the street decides to try and stop him, it's in your interest to just let him do that, whether with implicit or explicit approval. ... especially when you can't get to that corner of the backyar...
Why is it that unhealthy food tastes so good?	[ "Foods that have high concentrations of fat and sugars were scarce on the african plains our species grew up in. These foods are high energy foods that were important for our survival. Because they were rare and difficult to attain we evolved sophisticated mechanisms that make us crave them." ]	[ "The human brain is partly designed to assess risk and keep us out of danger. All the things you listed have potential danger associated with them, be it physical danger, or danger to our pride, self-esteem, etc" ]
Why do containers such as wine and beer bottles do the whole “glug glug glug” thing when being emptied?	[ "Air displacement. When pouring a bottle upside down or covering the entire seal as it empties it creates a vacuum. The positive pressure from outside moves to the low pressure inside the bottle." ]	[ "So basically it runs through a list of ranked elements. You usually want the higher ranks first in the list, so if it sees an element ranked lower then the next one down, it swaps them. It goes through the list in one direction, then once it reaches the end it goes back through the list in the other direction. It ...
Why does inbreeding affect genes negatively?	[ "Imagine you are made of genetic soup. Some people have ingredients that just don't go well together and make the soup taste bad. But that's ok, because when you have a kid, we just take some of my soup and some of my wife's soup and pour it in together. So even though my soup has some bad ingredients, her ingredie...	[ "At least with respect to continental Europe, there were fairly clear rules about the degree of relationship (Consanguinity) within which marriage was allowed. At first that followed Roman civil law, prohibiting marriages any closer than first cousins. In the 9th century this was expanded to 7 degrees, so anyone up...
If the Sun suddenly exploded, what exactly would happen? Would we even know right away?	[ "The sun is 149,600,000 km from Earth. If we assume it would explode at the fastest velocity it ejects stuff from it 3200 km/s. Then it would take just shy of 13 hours for the explosion to reach us. It takes 8.5 minutes for us to begin to see the explosion, so you would still have the better part of 13 hours to see...	[ "This video created by Vsauce 3 (Jake Roper) does a very good job explaining this: _URL_1_ I hope this answers your question. He also did another video on a simmilar line of - could you survive: _URL_0_" ]
Are bombs really that faulty? Why is so much unexploded ordinance found?	[ "It's a matter of sheer scale and numbers. Like /u/DuxBelisarius pointed out, the German bomber offensive was miniscule compared to the combined Allied bomber offensives. Britain was bombing Germany by night, and the Americans were bombing by day. Furthermore, the sheer numbers in their formations were much higher....	[ "There is actually a [PBS documentory](_URL_1_) coming out on the 23rd this year - Starts on May 21st. Similar things had been used by the British prior in the war, but as i remember it the 23rd was made up of [set designers](_URL_0_), (magician's?) and similar artists. It was a huge misdirection, not just the i...
How can 'compressing' a file reduce its size when it still contains all the data as its uncompressed version?	[ "Assuming lossless compression, all it does is more effieciently store the data. Data is binary (1's and 0's), so if the uncompressed file has a sequence like 111111110000100001111, the compressed file takes the fact that there are groups of the same numbers (I don't know what is actually looks like) so like 5x1,4x...	[ "The same reason your clothes could fit vaccuum sealed into a few small moving boxes, but typically we have them hung loose in the closet. They are easier to manipulate, use, and put back away, and you find paying for more closet space a fair trade off to the time and energy of vacuum packing and unpacking your clo...
Why does food shrink when you cook them?	[ "Burgers and bacon both contain fat and water which is rendered out of the meat when cooked. Bacon especially loses most of its weight in fat (grease) when cooked." ]	[ "Actually, the \"steam\" that you see isn't steam at all - it's condensed water vapour. [Steam](_URL_0_) refers to the gaseous state of water, and you can't see it. What you see from cold objects is also condensed water vapour. The two phenomena are one and the same, and they occur when the humidity of the air (how...
Why did Thomas Jefferson oppose the idea of the Industrial Revolution so much that he broke the constitution, he supported, to purchase the Louisiana territory	[ "This is a common misconception about Jefferson's views. Jefferson was not opposed to advancements in technology. Indeed he himself incorporated many new industrial technologies in his plantation at Monticello. What Jefferson was opposed to was the domination of the country through a commercial oligarchy, as had oc...	[ "> no such undisturbed sequence has actually been found, meaning that our fossil records are inaccurately formed. Can somebody disprove this? That's absolutely incorrect. There are such a fantastically large number of counter-examples that I don't know where to start. Modern lake beds, ocean beds, rivers, alluvial ...
Do other animals have heart attacks, or is that only a human thing?	[ "[This article](_URL_4_) is about a myocardial infarction (heart attack) in a dog but mentions that this is a rare event. I found some other examples of myocardial infarction in rats, mice, dogs, cats and cows. _URL_0_ _URL_3_ _URL_2_ _URL_1_ A myocardial infarction is damage to heart tissue (mostly cardiac muscle)...	[ "While I can't speak as much for household pets, egg laying hens have altered laying cycles influenced by artificial lights to increase efficiency. There was also a study done on wildlife near highways that showed a level of disorientation in animals near the artificially lit roads (as if it wasn't already obvious)...
Why do meal combinations become "boring" and unpleasant over time?	[ "Our bodies need a lot of different things in order to be healthy. Vitamins, minerals, etc. Different foods may have different toxins that the body has to deal with and expel, or it may have different vitamins that are absorbed differently and that enhance or inhibit absorption (ie: vitamin C and iron... calcium a...	[ "With some of the music I listen to, there's so much going on that you don't get it all from a single listen. Take a band like Rush, for example, where all three members are at or near the top in their field: one day you hear more vocals, another day it's more drums, other days it can vary, and so on, and it takes ...
How does hand sanitizer "evaporate"?	[ "Hand sanitizer has a high alcohol content which requires less energy to evaporate than water. Also, because it's on your hands, it is pulling heat from you very quickly (you'll notice it makes your hands cold)." ]	[ "They use a wavelength of light that is cancer causing. Do you want to sit under a cancer causing light? Plus, they aren't all that effective to stop, say a sneeze from transmitting to another person. It takes some time to kill the germs." ]
Why does it seem like you get the deepest, best sleep right before your alarm goes off?	[ "About 20-25% of your sleep consists of the REM-sleep. After the first deep-sleep-Phase where your brain frequency reaches it's minimum, your brain waves speed up again until you are in the REM- sleep. This whole cycle repeats several times. But the REM- phases become longer, therefore in the early morning hours yo...	[ "Two social psychological concepts come to mind here. State dependent memory encoding and Erickson Arousal theory of learning. State dependent learning states that what ever state of mind you are in during encoding is the state of mind where recall would be optimal. Erickson arousal theory states that learning is m...
What is partially hydrogenated coconut oil?	[ "Your misunderstanding is here: > Hydrogenation is something you do to unsaturated fats. Unsaturated sites (i.e. C-C double bonds) are catalytically hydrogenated, which can produce trans fats. Hydrogenation is something you do to unsaturated hydrocarbons containing double bonds. In fats, a C=C is hydrogenated to ...	[ "It's not obvious what it should mean. So having the FDA regulate it wouldn't be fair to the people whose products don't meet the FDA definition." ]
Why do spins/jumps in sports continuously get more intense?	[ "It's primarily two things: 1. Better equipment. Technology plays a larger role in these things than most people realize. Simply the fact that modern equipment is lighter, stronger, has more flex, rebound and spring allows athletes to do things that were literally impossible 20 years ago. 2. Athletes start training...	[ "I ran track in highschool and followed the scene a bit. Most of seems to come from simple observation of past history. In the example you mentioned it is just that nobody has ever passed that mark. No matter how hard people train and repeat the cycle, nobody has done it. Basically they just figure that if nobody c...
Does Acid Rain still happen in the United States? I haven’t heard anything about it in decades.	[ "yes and no. The severity of the problem has been reduced a lot because of air emission rules limiting discharge of acid-forming gases (sulfur and nitrogen oxides are the main problem). Restrictions such as requiring the use of \"clean coal\" (low sulfur coal) or use of air scrubbers for discharge stacks have resul...	[ "Firstly, because \"malicious intent\" isn't really a crime most places. Secondly, it's because schools seldom, if ever, actually have malicious intent. The intent is almost always pure, even if the execution is flawed. Sometimes schools do get sued. But they generally don't have many go against them, because very ...
Why is there no E in the grading scale?	[ "F is short for \"fail\" and is not part of the normal letter system, it's just coincidence that it happens to fall near the beginning of the alphabet. It's just like P for Pass, I or N for Incomplete, etc. Fun fact, some school systems feel that \"fail\" is too harsh and have actually introduced \"E\" as the lowe...	[ "> Middle English orthography was unstable, but when the sound /k/ appeared at the end of a syllable, two spellings tended to be used: > 1. If /k/ was preceded by a long vowel, it was spelled \"k\" (today's \"like\" used to be spelled \"lik\"). Adding \"ke\" at the end (like) is alater development. > 2. If /k/ wa...
How do stocks and bonds benefit businesses?	[ "u/demanbmore and u/ooobs are both right. What I would add is more philosophical and fundamental: stocks benefit businesses in the ways they described, but, in a very real sense, stocks define business. The whole idea of a \"company\" is that a group of people can pool their resources to engage in an endeavor tha...	[ "No expert but I'm going to take a guess. It gets darker and colder causing more people to spend time indoors than outdoors. Because of this, they'll get more viewers. More viewers = more money." ]
What happens to anchored, flexible objects like long hair in simulated gravity like that on a rotating space station?	[ "A simulated gravitational force due to an accelerating reference frame is identical to a real gravitational force. The differences will come from the fact that you are asking about a rotating reference frame, rather than one that is accelerating in a straight line. The rotation causes ~~two~~ one addition forces:...	[ "if I might add a question to be answered: I'd like to know if behavioral tendencies would also play a role in their orientation? (e.g. would schooling fish all swim in the same orientation/direction in zero g?)" ]
How did kings, emperors and popes give speeches before microphones?	[ "More of course can be said, but we do have some older threads about this topic which will be of interest. I'd recommend you check out [this thread](_URL_6_) by /u/iphikrates or else [this one](_URL_7_) by /u/Celebreth." ]	[ "Very carefully. In seriousness, it's a challenge. It requires applying a critical eye to everything, and trying to validate the information. For Alexander the Great, for instance, there are only accounts much later, but there are tons of them, and history shows that there was a massive spread of Greek culture ov...
Why do I see colors when I shut my eyes? Is it just my imagination?	[ "It's called an afterimage. Basically, your rod and cone cells adapt to overstimulation (bright light or intense color) by dampining their response to it. When you look away or close your eyes, that patch of receptor cells is still sending out a dampened response, creating the afterimage." ]	[ "from what Ive found, the question has to many variables to nail down exactly, as each case is typically different. some research says its the swelling and shrinking of blood vessels, while others attribute it to memory association. In short, its a well documented phenoma with a variety of reasons and speculations ...
Why does only half the population have the psoas minor muscle?	[ "Tack on question: Is it possible that the difference is a result of the fact that the white people have picked up DNA from other species in genus homo (like the neanderthal) where the groups that stayed in Africa did not? edit: [Article on interbreeding with neanderthal](_URL_0_)" ]	[ "A lot of the characteristics we are attracted to are from basic instincts in our brain. Hour glass figures on women are representative of a good body for childbirth. An upside down triangle body on a man is representative of a physically strong man, who is resistant to disease. Some people are attracted to differ...
If I'm in a spaceship travelling at near light speeds, does the distance between me and my end goal shrink or expand?	[ "Lengths can only contract, they can never be made longer than the proper length, in special relativity." ]	[ "You're thinking correctly. In fact, after a redshift of about z=2, the angular size of objects increase with distance! Galaxies look bigger in the sky the further out we look. Here's [a graph of angular scale](_URL_0_) as a function of redshift (~distance). The units on the y-axis are kiloparsecs per arcsec." ]
What is Math Linguistics?	[ "Quite simply, it's a way of trying to understand a language by analyzing it statistically. It's especially relevant to artificial intelligence, especially things like automated translations. Computers don't understand language; in fact, the only thing they can really do is crunch numbers. So to translate from one ...	[ "By response of said stimuli. When it goes too far a, say, kitten will signal it with body language and sound. And their partner will respond by licking the damaged area and going on a little less violently. If you have a kitten at home you can easily try this. If your kitten scratches or bites too hard, let out a...
How dangerous is the Americium-241 source found in common household smoke detectors?	[ "You might want to get in the habit if finding out how dangerous something is before you do it, not after. Don't inhale or ingest it, don't put it on your skin. You should live. The gamma and beta aren't anything crazy. That is normal background for some places. 1 millisievert/h is hot, and the reason you don't wan...	[ "Because the data that is gathered from someone's private life, taken out of context, can hurt them. Even if you have 'nothing to hide', what is taken out of context can sometimes be damning. Like say you had a lot of Muslim friends, and you decided one day you wanted to buy a pressure cooker because you need one f...
What was the official German flag during WW2?	[ "The Hakenkreuzflagge, the symbol of the Nazi party, became Germany's official flag in 1935, including trade flag, to be flown by merchant men. The Reichsflaggengesetz was enacted as part of the Nuremberg Laws (which included the racial purity laws) during the Reichsparteitag der Freiheit (Party Congress of Liberty...	[ "These areas are labeled on both the first and second maps, so we can understand the third map to follow the same idea. The first map has a note below the key stating \"Ungeordnete kleine Gebiete sind weiß gelassen\" which means \"Insignificant small territories were left white.\" The second map labels them \"nich...
What stops people sitting in the emergency exit seats on a plane from pulling the window and killing everyone?	[ "OK, nobody has explained it yet. First of all, the door is 20-30kgs heavy, and you have to pull it out then turn it and toss it through in an emergency. In the air, the pressure is really high inside the plane, and low outside the plane. This means the air pressure forces the door closed, so you'd never be able t...	[ "Here's a way of thinking about it. When you first choose a door, there is a 1 in 3 chance of picking the door with a prize behind it. You are more likely to have picked a door with no prize. You would, theoretically, expect to pick a door with no prize 2 out of 3 times. Then, a door with no prize is eliminat...
Why do railway electrification systems use third/fourth rails or overhead lines instead of the 2 the train already rolls along?	[ "Electricity (in the copious quantities needed to power a train) is dangerous. The rails the train rolls on have to be very sturdily attached to the ground, even through switches and crossovers. Making that sturdy connection using only insulated support components is \"too hard\". Rather, those rails are thoroughly...	[ "Imagine a bathtub full of water, the water represents electricity. The bathtub has a faucet, which represents the generation of electricity. Imagine now that there are little holes in the bottom of the bathtub, all plugged up. When ever a home needs power, unplug the drain and let the water flow out. Now imagine ...
Why is fat stored on the belly and not on other parts of the body?	[ "From an evolutionary standpoint it was to protect your vital organs. When you put on fat it stores it around your torso first where the most important organs are then it starts piling it on your arms and legs. That's why it's the last to be lost." ]	[ "Its a perspective thing basically you see it more during the day so the changes are less noticeable but when you sleep there is a bigger time gap so more changes happen" ]
Although the gravity of a black hole is too strong to allow light to escape, is light even emitted?	[ "Nothing can escape an event horizon. Thus, it is impossible for anything inside of an event horizon to interact with anything outside of one. By the way, an event horizon isn't a physical thing. It's simply a point in space (well, a sphere of points) which stuff can only cross in one direction. General relativity ...	[ "No. While our eyes are very limited in the range of the electromagnetic spectrum that they can detect, humans have been able to build all kinds of wonderful gizmos to pick up EM radiation (photons) with frequencies that our eyes can't detect. We can put a measurement device somewhere, see what kind of EM radiation...
Why are internet speeds in America so slow	[ "It mainly has to do with the monopoly that ISP's hold over different areas. Most people have one choice for their internet provider. It's not like you can switch to a different company if you aren't happy with their shit service. Another thing is that the capacity for fast internet exists it's just that they have...	[ "Basically the rent is too damn high. It takes billions of dollars to lay cables and set up the infrastructure and current cable companies already have deals with cities to be exclusive." ]
Friday Free-for-All \| February 23, 2018	[ "I just want to take a moment to thank Dan Monroe, Director and CEO of the Peabody Essex Museum in Salem, MA. His continued neglect of the Phillips Library Collections, and ensuring that the collection was unavailable both physically and digitally to researchers over the past 2 years (and for the forseeable futur...	[ "Simple answer, it can't be done. That is a reddit-level site \"feature\" which is part of their anti-spam measures. Longer answer, there are ways which it could be 'hacked', through CSS tricks or link flair. The problem there is that it would require either an incredible amount of manual work from the mods, or els...
What's different between the Windows/IE situation in 1998 and the iOS/Safari situation today?	[ "Microsoft had almost complete market control back then. If you bought a computer, it had Windows on it in 99% of cases. Even now, [Apple's marketshare](_URL_0_) is small compared to windows, and there are viable alternatives like ubuntu even for the average consumer. Therefore, if you don't like safari, you can si...	[ "Well in NYC Clinton as a gay area is pretty new in the citys history. (mid 80s, and had a bunch to do with being cheap if not safe and parts of gay life happening on the docs near by) Before that it was the West Village and that had to do with cheap real estate and a bohemian and artistic community, and was a gay ...
Are artistic traits, such as being able to draw exceptionally or excelling in the musical arts, dependent on one's genes?	[ "'Artistic' is probably not a genetic trait. But if you break it down into its component parts, then each of the following things are at least PARTLY genetic: hand-eye coordination, fine motor movement, gross motor movement, depth perception, color perception, tonal perception, dexterity, muscle composition, flexib...	[ "> If a DNA sample is drawn from a crime scene, is it possible (with the use of software) to accurately recreate the face of the offender solely from that? No. The closest you could do is to clone the sample and see the face of the cloned human. That should be pretty similar. It would probably take, say, 18-20 year...
How does hot grease affect pipes?	[ "If you're talking about pouring hot grease down the sink drain, I wouldn't. It may be nice and liquid while you're pouring, but it will cool off quick when it hits the cool pipes, and unless you've got lots and lots of hot water to follow up, you will end up with possibly clogging your drain. Let the grease hard...	[ "Because the pipeline crosses most of the east coast, and is the means by which several states get their fuel, while the leak only happened to be in Alabama, any leak along the entire pipeline shuts the whole thing down for as long as the repair takes." ]
Can someone explain why we use the 'number' infinity? And also how if you continually take 1 away from infinity how it will never reach a numerical number?	[ "Infinity is a concept, an idea. It is not a number and it follows its own rules which are not always consistent depending on the infinity type in question. You cannot remove a finite number of 1 and get infinity down to a finite number. By definition there are an never ending stream of '1' that make up your infini...	[ "Think of it like a hose... and a room made of sponge. The light bulb is a hose, spraying water (light) everywhere. The room is a sponge, absorbing the water (light) all the time. The moment you turn the light off, it's like closing the faucet to which the hose is attached. It stops spraying water (light) everywhe...
Sports owners typically own real businesses outside of their actual team. Is there anything stopping them from underpaying one of their top players (for salary cap purposes) and then “employing” them in their real companies and making up for it?	[ "Yes -- Generally the leagues specifically have rules against this, so its quite as simple as that, its not allowed. In Europe, this gets even more wacky and complicated too. However, this wasn't always the case in every sport, for example a commonly known exception to this was the American Football player Hershel ...	[ "The idea is that in free-market capitalism an employer should be able to pay whatever they want to somebody to work in a particular position and if that wage is too low, then the person would find a job that pays better somewhere else. The \"effective\" minimum wage would be wherever the market of employers and po...
How do periods sync?	[ "> you tend to get your period around the same time They don't, it is a myth. What can happen is similar to when turn signal sync up; any regular cycles of different speeds will periodically sync up and diverge just through their unrelated operations. They are not connected in any way, you just notice them more whe...	[ "I did not know the female folk had their own thing, that's pretty rad. I would also like to know why." ]
When we get sick, we take drugs like pseudoephedrine which mask our symptoms. However symptoms are our bodies' method of eliminating the cold. Does this slow our healing time?	[ "It depends on the illness. In the common cold, the symptoms are due to inflammation from your immune system, causing postnasal drip. Masking these symptoms shouldn't slow down your healing. In something like influenza or bronchitis, a cough actually helps to keep the airways clear. Suppressing a cough in these ins...	[ "Antiviruses hook system calls to add their verification routines. System calls addresses are stored in the system service dispatch table (SSDT). Simply put, when a program wants to open a file, it tells Windows \"Open file.txt please\", and Windows looks at the SSDT where is the function to open a file, and calls ...
Can both pressure and vacuum exert identical magnitudes of stress inside a pressure vessel?	[ "First, -20 psi [gauge pressure](_URL_0_) isn't possible because atmospheric pressure is only about 15 psi. However, let's say that you'd like to compare a pressure vessel's stress profile at -1 atm and 1 atm gauge pressure, with the first condition corresponding to vacuum. You are correct that [pressure vessel the...	[ "For reference, the Millennium problem about the well-posedness of the Navier-Stokes equations can be found at: _URL_2_ One of the more recent results is due to Terence Tao from 2014/2016 _URL_1_ _URL_0_ He shows that an averaged version of the Navier-Stokes equations exhibits finite time blow-up, which suggests th...
What's the deal with fusion reactors like ITER and why do they keep getting bigger but still don't work?	[ "We have made functional fusion reactors, the Joint European Torus actually works quite well, and the ITER should be significantly better but isn't completed yet. So far fusion isn't commercially successful because it takes more power to create the fusion than it gets back out and cannot run continuously but it d...	[ "The thing about galaxies (clusters of stars) is that they are by definition very bright objects. And we detect exoplanets typically by pointing a telescope at a star and waiting for something to pass between the star and us. Any planet further than us from the sun will never pass between us and the sun - and will ...
How much energy could you produce by solar panneling the entire sahara desert?	[ "[2.8 quadrillion watts](_URL_1_) with current technology. [4.3 quadrillion watts](_URL_0_) with the theoretical maximum of current technology. Impurity band semiconductors could possibly get higher, as much as [9.8 quadrillion watts](_URL_2_). Of course this is completely ignoring the difficulty of getting the en...	[ "It depends on many factors: * Energy consumption rate * Body weight and fat * Age * Genetics * Many, many other ones" ]
How does the immune system of a plant work? What are the similarities and differences compared to the human immune system?	[ "Plant immunity is quite different from animals. They generally sacrifice infected tissue, cutting off nutrients so it dries up and dies. They also have alarm hormones that are released when tissue detects attack. This causes the rest of the plant to carry out a general immune response like producing toxic compound...	[ "Never heard of anyone trying to grow in vitro wood. It's possible that someone is doing it somewhere but I doubt there's much money in such a prospect. The reason in vitro meat is desirable is because mass animal farming is highly destructive to the environment. Mass tree farming is not nearly so. Done properly it...
If I'm blonde, a recessive trait, and my mom is a red-head, also recessive, could I still possibly pass on red-hair to my offspring?	[ "the way i understand the genetics of hair color, there are two sets of alleles. One set determines if the hair is red or not, and the other if it is brown or blond. If you have two copies of the allele positive for red hair (recessive), you will have red hair. Blond hair is also recessive, you need two copies of t...	[ "Amber is tree resin, it was liquid and sticky when it came out of the tree so all sorts of stuff got stuck in it fairly often. And since it's a carbon compound from a tree it can be radioisotope dated, some part of carbon in trees is always radioactive carbon-14 coming from the air where it's created by cosmic ra...
How do babies not drown during water birth?	[ "They’re going from one “water” environment to another water environment pretty quickly, so there isn’t really a change in their environment when they come out. Their lungs are still collapsed at that point, so it’s not until they take their first breath of air that they start breathing actual air!" ]	[ "To add to what /u/hiearthpeople said, cetaceans sleep in a pod with one eye open. They all swim in a circle, and the eye that is facing the outside of the circle corresponds to the opposite side of their brain. That means they swim clockwise and counterclockwise depending on what hemisphere of the brain they are r...
Why can't we harvest the energy produced by lightning in order to power our homes and devices?	[ "Even if you could do so, and because of the random and sporadic nature of lighting you really can't, the very cost of building the massive capacitors to store it would be cost prohibitive compared to the small amounts of energy you might recoup." ]	[ "There are a few reasons: A) It could be fake, as ET_phone_1900FatGirl pointed out. B) It is difficult to prove that the people in the show are performing an illegal activity. How can law enforcement know it's not fake? Could it be water, not moonshine, in the bottles? While the show could theoretically be used a...
Why is contracting Chickenpox a much more serious problem if you're an adult than a child? What are the differences between the adult and child that account for this difference?	[ "I found an old comment thread, and it appears that back then, the reason was not entirely known. It may be interesting to read anyway. _URL_0_" ]	[ "Why wouldn't they be? If 4lb boxes of cheerios cost > 4x more than 1lb boxes of cheerios, you could combine 4 1lb boxes and get a 4lb box and profit. But you can't combine 4 televisions into one big television. I don't know about TVs, but in general, larger objects with tiny features tend to be more difficult to m...
[Astronomy] What is the deal with all of the stars that don't appear to be part of a galaxy?	[ "Those are either stars from our own galaxy, or other distant galaxies that are too far away to be resolved beyond a small point of light, depending on the picture you're looking at." ]	[ "Since the question has already been answered, I'm just going to throw in a plug for my favourite app for answering these kinds of questions, [Google Sky Map](_URL_0_). Just point it at whatever is confusing you, and it tells you what and where everything is." ]
What causes raindrops to be different sizes?	[ "A raindrop gets bigger in the cloud by combining with other drops, also called coalescence. Coalescence happens in the air, and the cloud, so the raindrops that combine in the air, are larger than the ones that don't. Another reason why raindrops vary in size is because a raindrop can be ripped into pieces on a wi...	[ "When you take a pill it's not 100% the labeled medication. There are other ingredients that help it do its job and release when and how it is supposed to. Sometimes a medicine needs more extra ingredients to do its job so you end up with a bigger pill." ]
Why do farmers choose to grow GMO?	[ "> GMO is destroying life of farmers...in India a farmer commits a suicide every 30 minutes. This is an urban legend that has been debunked countless numbers of times. _URL_3_ _URL_4_ _URL_2_ _URL_1_ _URL_0_" ]	[ "This is a very common question. You can use search to find [all the other really good answers](_URL_0_ ). This is instant, and faster than ust typing in your question every time. It's a way of cheating elections. Read the others, and then ask a more specific question." ]
During its creation, how exactly did the Earth cool down?	[ "Radiation going into space. Every object will emit electromagnetic radiation, with the spectrum and intensity depending on the temperature of the object. This is called thermal radiation. On the other hand, in the solar system objects also receive radiation from the sun. Ultimately, an equillibrium will be reached...	[ "Ice cream needs to be constantly stirred while it freezes. That way you entrain air into the mixture and get a nice texture. A home ice cream maker has three parts - a bowl, a paddle, and a turntable. The bowl is filled with coolant, which you freeze. When you pour the ingredients into that bowl, they will eventua...
Is there a way to trigger an endothermic reaction without moving components?	[ "I can't think of anything that would use zero moving parts, but if you can live with one valve you can try opening a cylinder of pressurized gas and letting it escape through a coil around your bismuth container. Evaporative cooling with water or ammonia could work too, but that would probably be more complicated....	[ "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." ]
Why does human eyesight deteriorate? What can be done to stop the process?	[ "It is mainly due to a reduction in [accommodation](_URL_0_). The lenses in our eyes need to change shape in order to focus at different depths. As we age, the lenses harden and don't change shape as easily. This is termed [presbyopia](_URL_1_). It is also why older people tend to wear bifocals. Since their eyes ca...	[ "Take a picture of a cloud, then wait a couple minutes and take another picture of the same cloud. You think it will look the same, after all it doesn't look like its changing as you stare at it. But you will find that there is a noticeable difference between the 2 photos. It's just such a gradual and constant chan...
Where was the original city of Alexandria?	[ "You will need to first clarify which Alexandria you mean when you refer to the \"original city\" because that will impact the answer. If you mean where was the first city named Alexandria, that is a different answer than asking where the earliest settlement for the most famous Alexandria was located. There were ma...	[ "I did some google-fu and found the [ship referenced on this wiki-list](_URL_2_). It pointed to two further sources. [_URL_0_](_URL_0_) which contains some information prior to German service, and the [Miramar Ship Index](_URL_1_) which has further information but requires a subscription. That list and [Wreck Site]...
How do huge structures get buried?	[ "I know I know I know this one!!! Weather moving dust/sand around and stuff is definitely a component like other people have mentioned, however, my ecology teacher who specialized in architectural archeology explained how or was EARTH WORMS*! Some species dig up to 6 feet straight down... And carry the soil up. Ii...	[ "As a follow up question, how are the farmers/owners of that land compensated today? Battlefields of WW1 are still claiming victims and damaging property with exploding ordinances. Wouldn't this not be covered under insurance as acts of war are pretty much never covered? Or is there a special fund or type of insur...
Why is sunset earlier at the beginning of December than it is on the winter solstice?	[ "If I am not misstanke the reason it the [Analemma](_URL_0_) of the sun. If you take a picture of the sun at the same time during a year is move in a figure 8 like in this picture _URL_0_#/media/File:Analemma_fishburn.tif The sun will be at the lowers location it location on the sky more a lot horizontally at the t...	[ "Yes, this is called the [Shapiro Delay](_URL_1_). In the Solar System, you can see this from spacecraft messages passing near the Sun ([image](_URL_0_)), or by most of the major planets, Jupiter being the next biggest contributor of course. In addition, when pulses from a pulsar pass by a binary companion ([image]...
Do all polar compounds have a less dense solid phase than their liquid phase like water/ice?	[ "Short answer is no. For example, liquid methanol has a density of 0.786 g/cm^3, while solid methanol has a density of 0.791 g/cm^3. The reason ice is less dense than water is because of hydrogen bonding, not necessarily because it is polar (although without this polarity hydrogen bonding wouldn't happen). In liqui...	[ "Briefly, because the [pair potential](_URL_0_) between bonded atoms is asymmetric. When atoms are bonded, they sit at a certain equilibrium distance where electrostatic attraction balances repulsion from the Exclusion Principle. The balance can be thought of as a potential energy well with an approximately parabo...
Why do cats jump into your lap for pets purring, then out of no where hiss and try to bite you (while still purring)?	[ "Cats give much more subtle signals than dogs. Most of the time of they are hissing or biting you have missed the communication that they are done with whatever you are doing" ]	[ "This can happen when you go to a page that instantly redirects you to another page. When you hit \"Back\", you go back to the redirect and get instantly redirected again. That's why if you hit \"Back\" really fast, you sometimes manage to get past the redirect before it has time to process. A better solution would...
Someone told me that ethanol takes more fuel / energy to produce than it provides. Is this true? Please explain.	[ "Ethanol from corn is not carbon neutral. The oil powered farm equipment and the oil based fertilizer and the fossil fuel energy of production all add up to more energy than burning the ethanol gives back. Basically, we are converting oil into ethanol." ]	[ "A few things to keep in mind about agriculture: Generally, the closer to the equator you are, the better corn will grow. It needs lots of heat. In modern times corn is still not grown for grain in northern areas. The other thing corn needs is moisture. Even today with modern irrigation equipment there are areas of...
why do we shiver after peeing?	[ "Never even once. What the hell is this?" ]	[ "Nobody knows why or even if it works, but that and variations of it are common practise in many countries. Cultural memes are like that, they spread, even if they don't have any real function." ]
How does file compression work?	[ "Imagine that you had a picture, and you chopped it up into tiny squares much smaller than a postage stamp. Then you assigned each one a color number between 0 and 255. Then you had to write down the color numbers, in order, on a piece of paper. Well in some sections of the picture, like the sky, you will have r...	[ "_URL_0_ The wikipedia article is excellent and better than any of the answers in here so far. If you have specific parts you don't understand, ask away and I can help explain them to you." ]
How effective/practical are solar panels in cities where it is cloudy a lot?	[ "It is very viable even in a place such as Vancouver. The issue is that the return on investment is much much longer than sunnier places. A typical home photovoltaic array will recoup its cost in 15-20 years in good conditions. In Vancouver it may be more like 25-30 years to recoup cost. It typically depends on how...	[ "We won’t know until we learn more about the connection and economics of the situation. We could come up with tons of scenarios, but until stuff is more released we don’t know. Hell we don’t even know if any of the companies attempting to do this type of stuff (it’s more companies than just SpaceX, SpaceX just hits...
At what age do Orangutans grow their facial flanges, and how long do they take to grow?	[ "I took a primatology class in college and was told that there are two types of male orangs. The flanged males are big dominate guys and they will fight over females with other males to gain dominance and the right to mate. The unflanged males are sneaky bastards. They chose not to waste energy fighting other males...	[ "You're thinking correctly. In fact, after a redshift of about z=2, the angular size of objects increase with distance! Galaxies look bigger in the sky the further out we look. Here's [a graph of angular scale](_URL_0_) as a function of redshift (~distance). The units on the y-axis are kiloparsecs per arcsec." ]
The difference between flanger, phaser, and chorus.	[ "A flanger makes the same sound come slightly later. A chorus is the same, only modulated and multiplied. A phaser is a device that fires a beam of energy in multiple phases, much more powerful than a laser and more energy efficient than the competing disruptor, it is a primary offensive and defensive weapon on Fed...	[ "Uk Language? Pills will get you proper munted. Like out yer bonce. It'll make you think chubbers are buff and pull shapes all night. Draw makes you want to cotch. Then you get bare munch and need to smash a mint Aero and Potnoodle, maybe a maccie d's. Chang will make you Brap." ]
Why is "speed of light" the only time where a speed is used to quantify a distance? i.e. lightyears	[ "It isn't. People often say thing likes \"My house is about 20 minutes from the beach\" when they mean \"a distance which when traveled by car averages 20 minutes.\" Also I have heard things like \"san francisco is an hour and a half from LA\" (by plane) In tokyo I will tell people I am 5 mintues from the station....	[ "They just do. All massless objects travel at c in vacuum. It's the default. They don't get \"a boost\". In QFT no detail is put into how they are created, they are just emitted or absorbed in an instant. When they are emitted they propagate at c. This turns out to be an accurate model of reality. Any set of obs...
Which geographical locations on Earth are least prone to environmental disasters?	[ "[Dug up an article I saw in the past](_URL_2_)" ]	[ "To give a slightly different example that /u/Vampire_Seraphin's a current excavation off of the coast of Sri Lanka at a fishing village called Gotavaya is the first marine excavation of an ancient shipwreck in Indian waters. It is dated from the first century BCE/CE, which was the peak of the ancient trade, but as...
Why do your collarbones/shoulders ache when you're dehydrated?	[ "I believe the pain you are talking about is the referred pain from your diaphragm when you overexert it through exercise. The sensory nerve responsible for feeling pain from the diaphragm (at least the middle of it) actually originates from the spine near your neck. So any pain from the diaphragm will be sent back...	[ "It will freeze-dry at night and boil in vacuum during the day. With a bit of practice, salt and spices you could probably do a decent beef jerky. Be warned that the surface of the moon is rich in calcium oxide and other basic compounds, which are bad for you and will make the steak taste bitter. Use only clean su...
Why do people spasm as they fall asleep?	[ "_URL_1_ \"[When we drift of into sleep, the body undergoes changes in temperature, breathing and muscle relaxation. The hypnic jerk may be a result of the muscles relaxing. The brain misinterprets this as a sign of falling and signals our limbs to wake up; hence the jerking legs or arms.](_URL_0_)\"" ]	[ "Non-expert here, but isn't it just an adrenaline surge? It's just the muscles getting twitchy in preparation to bolt at any second. _URL_0_" ]
Why do traffic lights' yellow light vary in time from light to light?	[ "You will need a longer yellow light for roads with a faster speed limit. You just need more time to react at 60 mph than you do at 35." ]	[ "You're thinking of the two clocks as ticking like this: \|---\|---\|---\|---\|---\| \|----\|----\|----\|----\| Both in the same \"direction\", with one ticking slow, and, therefore, necessarily, one ticking fast. But relatively-moving clocks in special relativity don't tick like that. They tick along different \"directio...
Why the asteroid belts haven't coalesced to form other planets.	[ "Couple reasons. First, Jupiter's gravity has too much of an effect in that area of the solar system for a planet to form. Second, there's not much stuff in the asteroid belt - the total mass is about 4% of the moon - and everything is far apart from each other." ]	[ "A long time ago in places like Greece, Rome and even before that in really, really long ago places like Sumeria, and Egypt people made up stories about the stars/planets and the pictures they thought groups of stars made. These stories were usually about beings they considered to be gods or demigods (the word demi...
Roman architecture is so revered for being one of the strongest and best engineered. Yet, so few of their important buildings remain. What happened?	[ "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...	[ "A) Endeavor is being moved to Los Angeles to be put on display in a museum. B) The space shuttles are pretty much flying bricks. They're meant to fall out of the sky allowing some degree of control. Their wings cannot provide the needed lift, and the engines aren't designed for forward movement through the atmosph...
Why do plant cells have chloroplasts and mitochondria, but animals cells seem to lack those?	[ "Animal cells do have mitochondria. However, you are correct in that they don't have chloroplasts. Plant cells use chloroplasts to collect energy from light and transform it into chemical energy, but animal cells don't need this because animals don't get their energy from light. They get it from the food they eat."...	[ "See [here](_URL_0_) for a study showing the divergence times among the major lineages of mammals. It shows that most orders of mammals branched off from each other in the Cretaceous, and that most within-order diversity post-dates the end-Cretaceous extinction. The order Rodentia, which contains rodents, didn't ac...
What were the historical relations between China and Korea like?	[ "It was only a vassal state in certain dynasties such as the Chosun dynasty. However kingdoms like the Goguryeo were actually powerful enough to match some Kingdoms in China (key word being some)." ]	[ "As with many things in life the answer is money. I'd say your guess is right. Apple and Samsung are frenemies." ]
If quantum physics deals with phenomenon on a microscopic scale, what is the largest observable quantum phenomenon?	[ "Depends on whether you're talking about pure quantum effects, such as superposition, entanglement, or wave-particle duality, or macroscopic effects which cannot be explained without quantum physics, such as ferromagnetism (as mentioned by coniform), or semiconductors. If it's the former, quantum interference has b...	[ "The Bohr model can't really 'prove' Planck's black-body law. It assumes (ad-hoc) that angular momentum is quantized, without any rationale, really. (Except the one given later by de Broglie in terms of de Broglie-wavelengths) The Bohr model doesn't obey the uncertainty principle, the Schrödinger equation does. Not...
How did the B vitamins get different numbers and why are there gaps in that numbering system?	[ "The basic gist of it is that scientists in the early 1900s identified vitamins, usually by what deficiencies they prevented, and started naming them A,B,C,etc. but as it turns out, the what they originally thought was one vitamin B turned out to be many different compounds so it was split up into B1,2,3,etc. And o...	[ "One thing that may explain it that in the UK and maybe all of Europe, a car keeps its license plate for the life of the car. So they need a format to basically print a VIN number." ]
Do molecules actually look like their displayed formulae?	[ "No depiction of atoms or molecules really portray them in any real sense. In fact at that size \"appearance\" doesn't really make sense. The particles making them up exist only as these \"vibrations\" that we describe with the quantum mechanic wave functions. These rather abstract wave functions describe the proba...	[ "It really depends on what you mean by \"see.\" If you mean see with the unaided eye, then no we cannot. If you mean unambiguously detect and visualize, then we can. _URL_0_" ]
In what regime does the potential energy of a system depend on generalized velocity?	[ "Charged particles in a magnetic field. The Lagrangian has a term in it proportional to A·v, where A is the vector potential and v is the velocity. This isn't really a \"potential energy\", but it's a term in the Lagrangian which is not a kinetic energy. This is probably the simplest and most well-known...	[ "Think about things bouncing around. Imagine a box with a fan in it. Put 20 balls in ithe box. Now imagine a basket to one side just the right size for the balls. Turn on the fan. The balls jump around randomly. At some point a ball will fall into the basket. This will happen at a given rate which will depends on h...
Does the brain interact with programming languages like it does with natural languages?	[ "There has been at least one study that has looked at programmers looking at code, and trying to figure out what it is doing, while in a fMRI machine. The study indicates that when looking at code and trying to figure out what to do, the programmers brains actually used similar sections to natural language, but mor...	[ "If you were to build a 'super' car, would it be the fastest? The car that uses the least fuel? The one that can carry the most cargo? The one with the most amounts of seats? The one that fits in every parking space because its small? Different people create different languages for different reasons. Some are supe...
What substance has the highest dielectric constant?	[ "Dielectric constants can depend very sensitively on a number of parameters: frequency range of interest, temperature, pressure, applied electric or magnetic bias fields, etc. For most common materials at STP in the visible range, the highest dielectric constant typically doesn't get much larger than that of silic...	[ "I think you'd need to ask Eratosthenes in what medium his calculations were performed, and he's unlikely to answer. That sort of information is not preserved, although we know that some of his (now fragmentary) works laid out much of the scientific and mathematical reasoning of various projects. Sand was a common ...
Tidal effect of the Moon on Earth in perspective..	[ "There are a couple of diagrams [here](_URL_0_) that illustrate the direction and relative magnitude of tidal acceleration over the surface of the earth. Note that I would not describe this exactly as \"the moon's gravity tugging on the Earth's surface water.\" This can at least potentially be misleading; for exa...	[ "Point a flashlight at the wall and turn it on. See the small circle? Now, let's say your flashlight is delivering xyz power to the wall. So xyz power is landing in that circle, right? Tilt the flashlight in any direction. The circle spreads out across the wall doesn't it? But you didn't change the batteries or any...
Why do flies and other flying insects not have the reaction to fly away when a huge hand is swatting them away constantly?	[ "Insects do not have a brain. All their actions are based on a complex set of reflexes to various of events. Being swatted away is unlikely to be something they are even capable of remembering." ]	[ "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...
How is Apple "largest publicly traded corporation in the world by market capitalization" but not the largest company in terms of revenue?	[ "Market capitalisation measures what people think your company is worth, as reflected in the share price multiplied by the number of shares you have sold. Revenue just measures how much money your comapny has grossed in sales. A company can have high sales and low profits, which would reflect poorly on it and affec...	[ "It's a joke. I first heard it on Saturday Night Live when they did a skit called \"the change bank\". Basically it was a bank that gave you change for your money. Say you have a fifty dollar bill and you want 2 twenties and a ten, they can do that for you. At the end of the skit the bank CEO says, \"You may ask h...

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