Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
Someone taught me a magical cure for hiccups that I've been using since I was a child. Why on earth does it work?	[ "the real secret is distraction, I can stop your hiccups by asking you three random questions" ]	[ "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." ]
Why it feels so good to scratch rashes, poison ivy, bug bites, etc. if it is not a good thing to do.	[ "There is a natural small release of \"good feeling\" chemicals in the brain when you scratch anything. This came about through evolution. If you have a mite or dangerous parasite your itching will kill it or at least it is worth a shot is what your brain tells you. This is my understanding as a five year old not v...	[ "In short, Neuroplasticity. Pain and pleasure are both literally \"just in your mind\". By that, I mean that what our minds interpret as pain or pleasure is dictated by the firing of certain neurons in our brains. The pain and pleasure areas lie fairly closely together in the brain. Neurons from one \"area\" can gr...
How do mobile services, that are disabled while in airplane mode, interfere with an airplane?	[ "They don't. However, if an airplane was built incorrectly, it is possible that the signals send out by your mobile phone - mostly radio and microwaves - could induce an electric current in either the instruments or control circuit of an airplane, and while this is incredibly unlikely the result could be that you ...	[ "As stated already, you always need reception, there's no way around that. To explain the lack of SIM, you need only look at the meaning of the abbreviation: Subscriber Identity Module. A SIM is not actually required to make a phone call, it's just required to identify you and associate your phone with ...
Racist groups like the KKK and Neo-Nazis seem to view each other as allies today, but during WWII, how did the KKK feel about Hitler and the Nazi Party?	[ "Not to discourage anyone who wants to post, but [this](_URL_0_) older thread covers this question, and got a pair of extremely impressive answers from /u/Georgy_K_Zhukov and /u/kieslowskifan." ]	[ "In 1952, Stevenson campaigned on the record of the Democratic Party since 1932. The argument was basically that it would be better to trust the legacy of the New Deal to the party that created it than to the GOP, which they called the \"Party of Hoover.\" The problem with that strategy is that it was the same one ...
Can a neutron be polarized because of its quark composition?	[ "A similar question was asked [here](_URL_0_) recently. > Is there any truly neutral particle(s)? If by \"truly neutral\" you mean elementary particles with zero electric charge, then there are the neutrinos, the photon, the gluons, and the Z-boson." ]	[ "Engineering new chaperone proteins is probably a ways off. There are potentially easier ways to treat prion diseases, anyway. Essentially, susceptible protein must \"nucleate\", or turn into an aggregate of the prion form. This process is sufficiently slow as to be negligible in vivo, though; nucleated prion prote...
Where do all the chromosomes “go” during mitosis?	[ "All the chromosomes split like the 1 or 2 you see in the pictures. It's just so much easier to see what's going on and to fit a diagram on the page without drawing every single chromosome. For example, [here's what mitosis looks like in onion cells.](_URL_0_) The cells look really crowded and onions only have 8 ch...	[ "> If a proton beam is fired at a target of lithium or tungsten and neutrons are produced, where did the neutrons come from? They came from spallation reactions. > What happens to the protons and the target's atoms? [Here](_URL_0_) is a document with some nice figures, explaining spallation, and contrasting it wit...
For this new subreddit, can we determine a format for questions to be asked in? (i.e. "Explain THE DEBT CEILING like I'm five.")	[ "Explain ___ like I'm five or Explain __ LI5 would be great in my opinion, and having a loose format like TIL also helps when browsing the main page (to easily identify which subreddit the post is from based on the title)." ]	[ "Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Whistling ](_URL_6_) 1. [ELI5: How does whistling work? And how is it different from blowing? ](_URL_0_) 1. [ELI5: How does whistling work? (Wind/air pressure to sound with whistles, bottles, or lips.) ](_URL_4_) 1. [ELI5:How does whistling work...
What substances can reflect other parts of the electromagnetic spectrum?	[ "Yes, the frequency-dependence of a material's reflectivity is typically quite complicated. All substances reflect some portions of the electromagnetic spectrum to some extent, and transmit or absorb more in other portions. For instance, take a look at this [reflectance spectrum of grass](_URL_1_), soil, and wate...	[ "Air near the ground heats quicker than the above due to the ground getting hot. The hot air expands and changes its refractive index. What you're seeing is light passing through different densities of air, hence it shimmers." ]
How did ancient mines work?	[ "You have excellently clarified your original question with some more specific ones, but you might attract more, and better, answers if you specify a narrower time period or location. Did you have any in mind?" ]	[ "Do you have a particular geographical region or time period in mind? You're more likely to get a good answer if you are more specific than \"people in the past\"." ]
Why do leg muscles cramp?	[ "There isn't really a \"benefit\" to reacting that way; that's just a limitation that's there. It's like how there's no benefit to a car's brakes getting hot when you use them; that's just something that happens and you mitigate it if you can." ]	[ "When humans dream their brain reacts like it is real. Your brain has you walk, talk, etc. To prevent your body from acting based on the dream, you release a chemical that causes the signals from your brain to do nothing. Like cutting the strings on a puppet. But some people do not release the chemical, or not ev...
Did France have any other option but to surrender to Germany?	[ "You said you mean WWII. France never surrendered in 1940. They signed a cease-fire, which created Vichy France. This smaller state compassing Southern France kept on controlling the French colonies, until they went to the Free French forces. The Free French themselves just kept on fighting until the end of the war...	[ "If I recall correctly, they did decide to convert to the metric system a good number of years ago. so the obvious answer would be any other way then that." ]
When did it become standard practice for doctors/hospitals to keep detailed records of patients' medical history?	[ "In medieval Europe, medical texts usually did not document patient information like we do today. They described diseases and treatments, but did not give patient examples for the most part. Henry VIII's physician kept very detailed records, though, although this was a little later when this was becoming more commo...	[ "It was always prevalent, it's just that with the advent of social media and similar things that the stories spread like wildfire instead of being local stories that aren't able to gain any traction. The advent of everyone having a phone with a camera on it as well is leading to the rise of mass awareness, as befor...
Difference between coal and charcoal.	[ "Coal is a fossil fuel, its the remains of living organisms compressed underground over millions of years. The charcoal you put in your BBQ is made of wood, it's compressed wood pulp that is dried and charred to make it easier to burn." ]	[ "Here's a pretty good explainer. _URL_0_ Basically it comes down to different memory, different promises (reliability and service life), and different marketing." ]
How is a person who doesn't vaccinatε but is disease free a danger to anyone when he does not have any diseases to spread to others?	[ "Others captured the gist of it, but wrote it in confusing ways. Just because you aren't currently sick, does not mean you will not contract a disease in the future. If there are 100 people and one isn't vaccinated it is not a big deal, even there is no one to give it to that one person, and even if one person do...	[ "I don't go to school, sorry kids no tax for you. Fuck da poolice, sorry officer no tax for you. I am a young, fit and healthy person, eh hospitals can have a tiny bit. Defense? BOOO MAKE PEACE NOT WAR! None for you buddy. 100% on roads, I use roads. If everyone thought like this, Results = schools underfunded, h...
Why can't we build oil pipelines that won't burst?	[ "Material degrades over time. It'd be impossible to make a perfect pipeline. It's simply too big to ensure zero leaks ever and still be economically worth building" ]	[ "Building is often done in bulk, dozens of houses at a time, which means you get economies of scale, not just in the materials etc, but in the laying on of services. Building a row of houses needs a trench dug for the sewer connections, for example, but you can do the whole row at one time - likewise the foundation...
Why can't we launch all our garbage into space, perhaps directly into the Sun? [seriously]	[ "It takes a ton of energy, and the cost is prohibitive. [Here is a good explanation why](_URL_0_) Here are some other discussions on this topic. _URL_2_ _URL_1_ _URL_3_ _URL_4_" ]	[ "Go light a bucket of gasoline on fire, it'll take a few minute to burn depending on the depth/width and whatnot. Now imagine something hundreds of billions of times larger." ]
why are a venomous snake's pupils football shaped, while a nonvenomous snake's pupils are round?	[ "They aren't. Cobras and night adders have round pupils, some non poisonous snakes have slit pupils. Pupil shape is probably more correlated to what time of day they are most active at, with vertical pupils being more associated with nocturnal activity. They may also have links to camouflage. [Source](_URL_0_)" ]	[ "The value of coins used to be based on the precious metals they contained. Pennies were copper, and other coins were silver, which is why the dime was smaller than a quarter or half-dollar, and about the size of the less valuable penny. There used to be a coin called a half-dime, which was even smaller than a dime...
How far did the Romans travel?	[ "Individual Romans traveled to China, at least. [This old post](_URL_0_) from /u/Tiako talks about some Romans visiting China circa the reign of Antoninus Pius. During the reign of Nero an equestrian was sent to the Baltic coast to acquire amber, according to Pliny's Natural History. Pliny also writes about expedi...	[ "They didn't. This is a myth, and not a particularly good one. [This page](_URL_0_) does a good job showing how silly the idea is." ]
Why cant we feel our organs rubbing against each other?	[ "You sure as shit can when you have a kidney infection, such an eerie fucking feeling. Like bouncing water balloons with nerves attached that send shooting pain when you move...never again do I want to feel my organs." ]	[ "Imagine you grew up flying in a plane. The ground looks like different colors. There's a green area over here, and a brown area over there. When you land for the first time, you're surprised that the green area is actually made up of large trees, and the brown area is made of rocks and shrubs. There are thousands ...
Wouldn't pesticides have to be non-water soluble to resist rain? If so, what is the point of washing fruit and vegetables before eating them?	[ "Pesticides used directly on food crops are not supposed to resist rain, at least not to the extent that they persist and poison people. Pesticides are often washed away by rain which is often part of the guidelines for use - rain can shorten the preharvest interval that is needed before crops can be harvested. The...	[ "By the time you swallow food, it's been mashed up until it's soft and coated in saliva so that it's lubricated to slide right down your throat. Most pills have neither of those characteristics." ]
How is it possible to cool helium past the lambda point?	[ "The specific heat only diverges at a critical point if the system has an infinite volume. So none of our samples of helium-4 will have a divergent specific heat. The specific heat will get large in a similar way to the infinite volume system, but when you get close enough to the critical point it will \"soften\" o...	[ "The other guy was close: it's called supercooling and you can read about it on [Wikipedia](_URL_0_) or here's a good [video explaining supercooling](_URL_1_)." ]
why are something’s edible and taste good (vegetables/fruit) and other stuff like grass, leaves and other plants are inedible or we have no reason to eat/ nutritional value? What makes the edible stuff taste nice and the other stuff taste bad.	[ "A big part of the reason is that the crops we eat have been altered significantly by human farmers since the invention of agriculture to make them tastier. For instance, wild carrots are harder to chew and have a stronger flavor than domesticated carrots and are also mildly toxic. Meanwhile, wild bananas are smal...	[ "I'll generally explain capsaicin, the chemical that makes peppers spicy. Essentially, the chemical excites the same neural pathways that are excited by heat, causing our brain to interpret the sensation as a burning. There's generally no actual damage done, but our brain is tricked into believing that our mouth is...
Am I breeding super bacteria in my kitchen sink? If not, why?	[ "Similar question: are our hot water headers a breeding ground for thermophiles?" ]	[ "Not sure if this helps but what you describe is common for two things. A pan can be old, usually passed down through generations having been seasoned over the years from every meal that was cooked in it. Usually cast iron. The other thing that seems more likely to your question is when someone uses a traditional s...
How was the life of a public executioner in medieval ages?	[ "To piggyback on your question: were executioners generally people who enjoyed killing or displayed sociopathic tendencies? Did the general publics perception of executioners line up with the reality? What experiences did someone need to get the role of executioner?" ]	[ "People care less about obeying rules when they are about to die. At this point what do they have to lose? Did Jerry over in cell D12 make a rude comment about your mother? Maybe Jerry should get stabbed 12 times with a sharpened tooth brush. What are the guards going to do about it? Kill you? lol!" ]
Why do big oil companies spend millions on stopping electric cars instead of investing that money in advancing the technology? It would seem that the ground breakers stand to make a lot of money.	[ "We have had the promise of electric cars for a very long time and the reason they haven't come to fruition is simply the relatively weak power density of batteries vs gasoline. A subcompact car with a 10 gallon tank has the power density of [7 teslas](_URL_0_). Another issue is the incredibly high cost of lithium...	[ "Ultimately it's not the click that the website is being paid for. It's the user buying something from the site that they visited. The sites buying ad space know that some percentage of people who click the ad who actually buy something or otherwise bring in money to that advertiser. Just having more people click...
A Serial Killer expert on the podcast 'Accused' claimed that the late 70s saw such a high number of serial killers because they were raised by men who were traumatised by World War II. How accurate is this?	[ "OP, it would be worth x-posting this question to /r/AskSocialScience; they may be able to cite or recommend some studies for this." ]	[ "I've read a lot about historic climate shifts and I don't think I've come across this theory. Most accounts of the Little Ice Age place its start around the 14th century. In the 1310s there were a sequence of years with catastrophic rains during the growing season, leading to famine, and of course beginning in 134...
How does masturbation affect my body and mind?	[ "It doesn't. Religious propaganda that claims masturbation affects the mind is actively, callously, and intentionally abusive. The real intent - the only intent - is to keep young people in perpetual emotional turmoil and so consumed by guilt, fear, and shame that they don't have the inner strength to question doc...	[ "Redistributing load on muscles and joints prevents harm and aches that would occur more frequently in a prolonged loading scenario. tl;dr feels good man" ]
How sleeping tablets work?	[ "So the most common sleeping aid (hypnotic) you might see prescribed is zopiclone. The ELI5 version is that it binds to a receptor in your brain which enhances a neurotransmitter inhibitor. This inhibitor relaxes certain brain functions, and can produce sleepiness among other things. Similar drugs (benzodiazepines)...	[ "There are specialist advertising/marketing agencies that come up with them, and it really is a special art form. They have to find a name that a) is unique enough that it won't be confused with any other drug, and b) doesn't sound like it describes a medical condition or treatment, because the regulators won't app...
Would a coat of ultra-hydrophobic material on the bottom of boats help reduce wear from seawater?	[ "The bigger issue is aggregation of all the random organisms in the seawater. Barnacles, and random other things." ]	[ "I've actually built one for a science fair before. I used _URL_0_ as a reference guide: _URL_2_ _URL_1_ It worked, but know going in that you will not get a huge amount thrust. Your setup would probably do better, but it will still most likely not be a lot. What I ended up doing that had a more striking visual eff...
Why does the upload of data take so much more time than the download of it?	[ "for home internet connections. it's because the isp doesn't want you running servers. and if you want to run servers, you have to pay more. but there's no reason you can't have equal upload. it's just the isp doesn't give it to you." ]	[ "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 is stopping me from creating my own ISP from my house?	[ "The fact that you don't have your own infrastructure connecting servers and computers to the Internet." ]	[ "You answered it. Its one way. They have satellite internet that covers the globe. You have to transmit back. Do you want a huge 500ft tower in your pocket?" ]
What happens if a child is born in or above international waters? Which country are they then a citizen of?	[ "Most countries don't care where you are born, but who your parents are." ]	[ "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]...
If looking through a periscope, would a short-sighted person be able to see less far than a normal person?	[ "In a simple, mirrors-only periscope a near-sighted person would need their glasses otherwise everything would appear blurry. However, more modern periscopes use lenses for focus and/or magnification, so they can be individually focused based on your eyesight like binoculars or a telescope." ]	[ "How can [this](_URL_1_) and [this](_URL_0_) have different amounts of information on it if both are just pages? If you can find a way to make smaller 'marks' on a medium and read them again later you can fit more of them in the same space. At some point you can't make your handwriting smaller because otherwise yo...
Can you get vitamin D from the moon/moonlight?	[ "Based on values obtained from the Wikipedia for Moonlight and Sunlight, the light of the sun can vary between 120,000 lux and 400-200 lux depending on atmospheric conditions. The average lux value of moonlight is around 0.1. With that in mind while it may be theoretically possible to utilise moonlight to produce v...	[ "We don't, or at least not directly. The ultraviolet radiation drives [a chemical reaction]( _URL_0_ ) in our skin that creates it." ]
What cancer patients actually die of?	[ "That fully depends on the kind of cancer. In the brain it might simply be that it doesn't allow enough bloodflow to pass trough the veins, so the brain dies of lack of oxygen." ]	[ "In the days and weeks leading up to the surrender, there were a lot of survival methods tried out by various Nazis. Friendliness was tried, definitely. Others just tried to disappear, blend into the population and act like \"normal Germans\". The guards at some camps murdered political prisoners. Most of the highe...
How do we sing in key when our voices sound different in our heads?	[ "Your head isn't thick enough to have an effect on the frequency that you hear. When you listen to a recording of your own voice, what's missing is the deeper harmonics that result from the sound travelling through you skull to the bones in your ear, but it doesn't really affect the accuracy with which you can judg...	[ "One word: Repetition. You know all those song lyrics because you listened to the songs thousands of times. Names are easily forgotten because in our own minds, names are not nearly as important as the idea behind them. You often forget names quickly because you instead incorporate the idea of the person (who t...
Why does college football continue to use the multiple bowls method instead of switching to a playoff system?	[ "They just switched to a playoff format this year. But the answer to your question if it was for prior years is simple. Money." ]	[ "Since it goes state to state as far as rules my first inclination would be power. If you live in a state with a powerful majority party, it's in the interest of that states party to go for winner take all so that the party ,with it's deep reach in all districts, can try to coerce said districts to support the cand...
How can a TV remote controller last for months, while game controllers (ie. the WiiU controller) can barely make it through the day?	[ "A TV remote is just a tiny infrared flashlight basically. It only sends signals and uses any power while you push down the buttons. A game controller is constantly talking to the game system via radio frequencies." ]	[ "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 does jumping on the trampoline just before someone lands make them launch way higher?	[ "It basically turns into the same effect as a see-saw. You when you land, it causes the restoration the trampoline to tighten to make up for the giant spot you just stretched. When it tightens, it makes other pits, such as ones people are standing in, to become smaller, thus pushing them upwards. Same thing as the ...	[ "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...
Could gamma rays be used to take pictures like x-rays?	[ "Gamma rays are commonly used in industrial radiography. When the objects are too big for regular X rays but need to be inspected (rocket engines, bridge welding etc…) Factories would use a linear accelerator to produce gamma rays while field radiography (i.e. the bridge) would use a radioactive source to get gamm...	[ "As /u/SVFeingold said it is easier to make a copy of a key from a picture than it is to copy the lock. The bigger issue here, from what I got in the link you attached, is that picture was of all of the master keys for the TSA. When you travel you are supposed to use a TSA approved lock on your baggage which the T...
What are those lines that are on a driver's license?	[ "They're a security measure used to combat fake identification cards." ]	[ "Not sure but I've seen them pressed more often when I order for multiple people. I think it's just a shorthand so the customer knows which drink is which and which box has which burger. So when my mom orders for me and my sister and herself she can easily give my me coke, my sister her root beer, etc.." ]
What are some less known(to the average redditor) but interesting mythical monsters?	[ "You may be interested in looking for a copy of 'The Book of Imaginary Beings' by Jorge Luis Borges - a compendium of interesting facts and stories about mythical beasts. I picked one at random and came across the Catoblepas. First described by Pliny the Elder, apparently anything which looks upon this animal's eye...	[ "Hi, I'm Dr Jim Leary, lecturer in Archaeology and Director of the [Archaeology Field School](_URL_3_) at the University of Reading in England. I'm going to be here in AskHistorians to give an AMA on the 10th of November at 5pm GMT. I'll be talking about my work on round mounds, which included recently [discoverin...
What exactly is common law and is it legitimate?	[ "Common Law is the law developed over generations by judges over a long period of time. It's the law built up from long traditions and precedents that exists prior to legislative bodies passing specific statutes. The English common law developed in the Middle Ages, and forms the basis of law in England and its form...	[ "This CGP Grey video does a really good job of explaining it all. _URL_3_" ]
What's the difference between regular, virgin, and extra virgin olive oil?	[ "Extra virgin cold press is the first extraction press of the olive. Subsequent presses are virgin. Regular olive oil can be mixed with different other vegetable oils." ]	[ "VPN creates a 'tunnel' between 2 computers. Everyone can see where the tunnel goes, but no one can look inside. TOR is a series of relay stations, where the station only know the previous and next station, so no single station knows the whole route." ]
Historically, how likely was it you would be killed by wild animals in say Greek and Roman times and beyond?	[ "I can't give you accurate statistics, and 'Greek and Roman times' is fairly vague, but I can tell you that there were no animals that preyed on humans in Southern Europe since about 30000 BCE, which is the most recent fossil record of the Panthera leo spelaea, or cave lion, which inhabited Europe until the aforeme...	[ "BTW, for those that are downvoting this question, I would appreciate it if you could take a moment to explain the motivation. On reddit in general I could care less if something I write gets downvoted, but here in askHistorians it decreases the chances something I ask will get answered so if I am breaking some sor...
What were opium dens like in San Francisco?	[ "[Here is a generic image of an opium den](_URL_1_) from San Francisco ca. 1880 when the anti-Chinese/anti-opium movement was taking hold. And [here is a photograph of an opium pipe saddle](_URL_0_) from Virginia City, ca.1890. The pipe bowl would have sat on top of the opening, and saddle would have been affixed t...	[ "I have [an earlier answer](_URL_0_) on trans or at least gender-bending people in early modern-19th century Southeast Asia, if you're interested!" ]
Why does windchill make you colder?	[ "Not all the air is the same temperature. The air around your body is warmer because your body heats it up, creating an insulating layer of air. Wind causes this warm air to be displaced by new cold air, which makes you feel colder." ]	[ "I'm pretty sure part of it has to do with water (sweat) molecules being knocked off of your skin (evaporating) more easily, and water evaporating off your skin takes some heat with it, which is why you sweat in the first place" ]
How 'successful' has the process of a nation splitting in the past been	[ "The textbook modern example for peaceful splits is the 'velvet divorce' between the Czech Republic and Slovakia. The countries went their separate ways in 1993 after failing to work out a mutually satisfactory system for continuing their union. Despite some tension, they generally enjoy good relations today, with ...	[ "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 did Hitler manage to get most of Germany on his side, despite his extreme nazi ideology and violent rise to power?	[ "Not a historian, but my understanding is that the punitive terms of the Treaty of Versailles were so oppressive that Germany was driven into bankruptcy, and Hitler promised, and delivered, economic salvation. Jews were made scapegoats, and if you read history, Hitler did not invent that idea. Nor did hatred of Jew...	[ "Britain was occupied by Rome from 43 AD to 410 AD, which is shorter than most other areas. During that time, the island was never fully occupied, and they always lived besides the Anglo-Saxons in Scotland. The geographic isolation also plays an important role. On the main land, Spain, France and Italy may have be...
Why there are not much political movement to unify different countries that has very, very similar languages?	[ "Just because two different countries have a very similar language, doesn't mean they also have very similar cultural and political beliefs, nor a shared history. When people still see themselves as a distinct group different from those in another country, there is going to be little push to unite into one country....	[ "When you're describing (genetic differentiation due to geographic separation) is known to evolutionary biologists as [allopatric speciation](_URL_0_). The answer is that it depends on the [evolutionary pressures](_URL_2_) exerted on the populations. [Punctuated equilibrium](_URL_1_) says that populations tend to ...
Why do Humans have two testicles?	[ "1 for backup. 3 would cause too much risk of them tangling up or crushing each other. (one is already slightly higher than the other to reduce this risk)" ]	[ "Think about how incredibly dangerous and taxing it is for a woman to have a child. They're unable to mate for a year minimum, risk death and have a huge need to then care for the child. If you're a male who has invested in a woman, there is a very clear incentive for you to make sure that she doesn't go through th...
Why the US congress is trying to class pizza a vegetable	[ "Food in school has to meet various nutritional requirements. It had to include like 1 serving of veg, 1 serving of protein or whatever. It was lobbied by the food manufactures that the tomato paste used as sauce on school pizzas should be considered a vegetable. It ends up being more cost effective, although obv...	[ "I think it's also important to consider how much power the large food corporations have. They provide research funding to help promote their own products which creates a lot of contradictory/confusing information out there. For example, some people who helped develop the government recommended food guide in Canada...
What is Dynamic DNS? How is it different than regular DNS?	[ "There's little technical difference, mainly just what the service is expected to be used for. When a DNS server responds telling you the address for _URL_0_, it also says \"you can remember that for (perhaps) 24 hours, it won't change\". That cuts down the load on the DNS server and saves you or your ISP wasting t...	[ "The supreme court had previously held that making private copies available for use by others was legal in Canada (see BMG vs. John Doe). As such, there was no legal copyright infringement that copyright holders could use as leverage to get (the subpoenas required to get) ISPs to disclose the identities of the file...
Slow charge vs fast charge overnight	[ "It doesn't matter. It automatically regulates power supply to prevent anything from damaging the battery; for instance, when the phone reaches 100% it stops charging, and only starts charging when it falls below like 98%-95%." ]	[ "It's not well studied, but cognitive performance is altered on days in which you \"catch-up\" by sleeping extra. _URL_16_ In addition, adolescents tend to phase shift their circadian rhythms on weekends when they sleep extra. _URL_15_" ]
Why did the allied forces punish Germany so harshly in the Treaty of Versailles?	[ "> Didn't they know that they would be sowing the seeds for resentment and future hostilities? Resentment, maybe. Future hostilities? Eh...The Allies didn't have a crystal ball on hand. Germany was given (more or less) the treatment of the era when you lost a (major) war--loser pays. In the Franco-Prussian war of...	[ "Britain was occupied by Rome from 43 AD to 410 AD, which is shorter than most other areas. During that time, the island was never fully occupied, and they always lived besides the Anglo-Saxons in Scotland. The geographic isolation also plays an important role. On the main land, Spain, France and Italy may have be...
On a linear scale, can we "see" further into outer space or inner space?	[ "Well electrons get to be somewhere in the 10^-18 meters while neutrinos are somewhere between 10^-21 and 10^-24 meters (depending on energy levels). The most distance object ever observed is on the order of 10^26 meters (13.42 billions light years). Those are just things we have \"seen.\" Theoretically we get the ...	[ "well one way is by having sets of infinity. A fun example I like to use is from D & D. One place, an evil otherworldly plane named Baator (think Hell) is made up of nine layers. Each layer is a world to itself, and is infinitely vast. No matter how far you go you won't reach another layer without special means. Bu...
Why do we have pimples/acne?	[ "If anyone here has good tips for acne, feel free to share them. Mines not terrible, but could always be better." ]	[ "You each got 50% of your dad's genes, some overlap and some don't, some get activated earlier than others." ]
why are Girl Scouts and Boy Scouts gender segregated?	[ "Girl Guides. But they aren't, at least not any more. Girls can and do freely join Scouting bodies that were previously devoted exclusively to boys. The reason for the segregation was because boy scouts was created very early in the 1900's by Robert Baden-Powell as a very traditional organization in a time when wo...	[ "There is no evidence to support a difference in swimming speed. However, the difference in the mass of X and Y chromosomes _is_ used in many artificial sex selection methods." ]
Why does wind feel cold, even though the air it is comprised of may be at a comfortable temperature?	[ "It's basically to do with thermodynamics and the time your body is in contact with the surrounding air. Humans cool down by dilating blood vessels and effectively making their skin as hot as possible. When two materials with different temperatures come into contact, the hotter one transfers heat onto the colder on...	[ "Afaik, motion sickness is when your inner ear fluid (responsible for your balance) says you are moving but your other senses knows you are sitting in one spot in the car. The two signals mixup and your brain cant handle the conflicting information - hence out comes the breakfast. When you actually feel the moving ...
By which time in history the Byzantine history officially starts?	[ "You're not going to get a firm answer on when it 'officially' starts, because it's really a matter of preference. /u/tiako had a post here about some of the boundaries you can make: _URL_0_ Given that the population of the Roman Empire/Byzantine Empire considered themselves Roman, and there's no firm date you can...	[ "I am by no means an expert on this topic, but I can point you towards a very good book I read a few years ago. [Arc of Justice by Kevin Boyle](_URL_0_) discusses the trial of [Ossian Sweet](_URL_1_), an African-American physician who killed a white man in self-defense in 1925 Detroit. The man was part of a white m...
How do we know that action must be least ( stationary ) ?	[ "You can show that if you define the Lagrangian L = T - V, then stationary action implies Newton's law; see any analytical mechanics book for the proof. But in a more modern perspective, least action is a basic postulate of physics. You can derive it from the quantum [path integral](_URL_0_) in a classical limit, b...	[ "I have a longer comment as an add on to Mediumtim's comment, but I just wanted to add one more thing that didn't fit in my other comment. > Heisenberg stated that absolute position and absolute momentum together have no meaning in nature In the mathematics of QM, an absolute position or momentum (even on there ow...
Do you burn more calories running in hot weather than in cold? or does it make any difference.	[ "Cold. Burn more energy simply to keep your core temperature stable." ]	[ "Nervous system is all about the action potential in the neurons. All neurons signalling is an active chemical function. Energy is required to produce this function, and as a result lower temperatures drive down the energy available for the reaction to occur. This also happens in cells, making it impossible to main...
Why does the raidio only play certain songs by an artist and not any song that is good by them? Even old artists with no albums to promote.	[ "To put it simple, it's been analysed that the audience stay on the station when the music is recognisable." ]	[ "Your router does a lot of load balancing, and transmits data through different channels. Depending on the number of devices connected, and their location relative to the router/other wireless networks, wireless devices will be automatically assigned different channels to use. Not all channels are created equally,...
Why do governments or businesses commit to policy/plastic waste changes 2-5+ years in the future? Why not sooner?	[ "It takes a while to implement the changes. How would you like it if the law changed overnight and you had to pay fees/go to jail next day without having a chance to adapt yet." ]	[ "Can you please define for the court when a crime is \"obvious\"? When is the evidence \"clear\"? Why do you point out a first degree murder and claim that this is something more 'obvious' and 'clear' than say, fraud or kidnapping? It takes a long time because it is a very serious accusation and in order to ensure ...
What makes a good cigar?	[ "What makes a good cigar? A committed Cuban." ]	[ "Different ingredients, different storage situations, different flavirong, different length of time they are aged." ]
When is the last time the Queen's Guard had to use it's military power?	[ "Guards at the royal palaces are made up of soldiers from one of the 6 different guards regiments in the British Army (Grenadier, Coldstream, Welsh, Irish and Scots Guards in the infantry and the Life Guards in the cavalry). These are regular regiments of the British Army and are regularly deployed to combat zones ...	[ "They typically don't do \"cool movie things\" because real life isn't a cool action movie. About the most they've done recently (at least, publicly) is get in trouble with prostitutes, get drunk, and sneak into the white house when they shouldn't. Behind the scenes, they're responsible for keeping the President sa...
Why does a strobe light, particularly 11-17hz, trigger motion sensors?	[ "I'm going to speculate that the sensor uses a pulsed infrared LED and a phototransistor to measure presence of hands. Pulsed light is better than steady because you can tell reflected from ambient light. Your strobe is probably matching the pulse frequency of the LED, making the sensor \"think\" that there's a ref...	[ "It's based on you experiences you have had with these genres. For example, I used to listen to the most annoying alarm clock every morning because it was the only thing loud enough to wake me. One day I was walking through a store and heard a sound with the same frequency going over the PA and immediately felt ang...
How to convert energy into mass? according to the formula: E=mc2. It's supposed to be possible, but how? Is there any example?	[ "A common way is to accelerate a charged particle, like a proton, to very high speed. Speed is energy, so when the proton collides with something, there is a chance that the energy will be converted to mass. For example, at Fermilab protons were accelerated to an energy of around 1 TeV and collided head on. The col...	[ "The example usually given is imagine two mirrors on opposing sides inside a box, and you bounce a particle of light between them. It takes said particle a fixed amount of time to ping between the two mirrors because the speed of light is fixed(See EEP). If you were to run with the box, the particle would have a gr...
Why when some people are about to engage in a physical altercation do they start to shake, heart pump and lose peripheral vision?	[ "Your body has some really complex biology, and it is very, very good at helping you survive. The reactions you are talking about, like increased heart rate and dilated pupils, as well as tightening of the bladder and the release of hormones like epinephrine, are caused by this really cool thing called the sympathe...	[ "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...
Why is the price of gold so high relative to its actual uses?	[ "It doesn't corrode, which worth every penny for things like medical or military equipment. Basically, if you are building something very expensive, you would rather use gold than something cheaper that might corrode and fail." ]	[ "Think of a rare baseball card. If there's only 10 of them in existence, then everyone would want them and they would be willing to trade hundreds of chocolate bars for it. Now think if they printed 990 more of that rare baseball card. Now everyone has one, and no one is willing to trade a chocolate bar for it." ]
As a rule, do languages simplify their grammatical features over time?	[ "You might get better answers to this question over at /r/linguistics" ]	[ "Because phone companies use planned-obsolescence to slow down older devices artificially in order to push newer devices. OR Because newer software is more taxing on the hardware than older versions was. Both of these have some truth in them, I recall several instances where it was claimed that around the release ...
What are the most common reasons countries "decide" to become another, and how? E,g. Castile-Aragon to Spain, Prussia to Germany, etc.	[ "They merge with another country. Prussia merged with other German principalities and united as Germany. Spain was formed through marriage and conquest. To unite a new kingdom made of dozens of former nations, they rebranded the country with a new name." ]	[ "I can only speak to the US. Originally, the capital of the US was New York City. This angered the agrarian types since New York was the business center of the country. Thomas Jefferson in particular didn't like New York as the capital. So one day Alexander Hamilton, the secretary of the treasury approached George ...
Before you give blood, they ask you a series of questions, including if you've ever had sex with a man who's had anal sex with another man before. How come they don't ask if you've had sex with another man who's had anal sex with another woman?	[ "They just ask simple questions that might make you statistically higher risk for having HIV/AIDS. For example, you can be a prostitute or use illegal drugs and protect yourself from HIV/AIDS, but statistically, people who are prostitutes, use illegal drugs, or men who have sex with other men, are as a group much h...	[ "If you ask for 1 pen, it costs you two dollars. If you ask for 100 000 pens, they will only cost you one dollar each. I prefer selling you 100 000 pens at half price, than selling you 1 at full price and have 99 999 sitting around doing nothing. In a similar way, if you ask for a small amount of money, you pay a b...
Can anyone please recommend books about the bronze age collapse?	[ "[1177 BC: The Year Civilization Collapsed](_URL_0_) by Eric H Kline" ]	[ "For podcasts; Dan Carlin has a several episode series on the Roman Empire, and the entire \"History of Rome\" podcast is excellent." ]
How exactly do laser thermometers work?	[ "I believe the device you are referring to is actually called a pyrometer (please ignore me if you are talking about something else). Most objects undergo a process called blackbody radiation, which means that they emit light from their surfaces which has a wavelength (a way of classifying light) that depends on th...	[ "Non smart person here. My guess is it has something to do with light bouncing off particles in the air. Which is the reason why less light reaches the target. Because. of the dust and dander and other air born things absorb some and reflect the rest in different directions and those are the light rays we see." ]
How are dark matter and dark energy not just copouts / fudge factors / begging the question?	[ "Astronomers always proposed the existence of unseen bodies to explain anomalous gravitational behavior. It led to the discovery of Neptune, for example, when a small decceleration of Uranus was detected. The precession of Mercury's perihellion was also atributed to a hypothetical planet called Vulcan. Dark matter ...	[ "We do use antimatter currently for practical uses, ever heard of a PET scan? It would be the ultimate energy storage medium because gathering meaningful amounts of antimatter from nature is impractical. The best place to find it now is in the van Allen radiation belts." ]
Why do deep sounds seem to travel further?	[ "Low frequency waves are long. Quite long. Some take as much as 20-30 ft to fully develop. They go right through most walls, whereas high frequencies (very short wavelengths) get stuck in a pillow. It's the same reason why it takes so much more power to drive bass speakers than treble & midrange." ]	[ "I don't know of any, and I would be surprised if there were any, since it would require really high frequencies. Consider an organism that is 0.1mm in every dimension (a spere, for example). A sine wave at 1 MHz would have a peak-to-peak displacement of 0.1mm, the length of the organism's body! Since that's not ve...
What is the oldest known religion?	[ "Here are two similar questions with extensive answers: [What is the earliest religion that we know about and what did they believe?](_URL_13_) [What is the world's earliest known form of religion and what did the group believe?](_URL_12_)" ]	[ "There is a good deal of room for fresh responses to this question. But I briefly summarised the main controversies [in an earlier thread here](_URL_0_). The short answer is that we have no certainties about this at all, only a lot of supposition and a certain amount of reasonable deduction. Even the discovery of f...
During the Golden Age of piracy in the Carribean, what where the chances of an unprotected merchant ship being boarded? And if boarded, was the crew likely to be killed?	[ "You might be interested in [this recent AMA](_URL_0_) by renowned piracy expert Benerson Little." ]	[ "A) Cardiac arrest can hurt, but it does not always hurt. Sometimes your heart simply stops. There is an entire phenomena called a silent heart attack were you have no pain and few symptoms. B) Nope. Not waking them up is part of what defines \"peacefully passing in your sleep\". Even if it were something that wou...
Does the '5 gallon bucket' air conditioner work if I use ice from my freezer?	[ "Well, the total heat in the system will be higher than zero because the freezer isn't completely efficient. When the freezer cools and freezes the water, the water loses a certain amount of heat energy over the temperature change + phase change. ...but in order to move that heat somewhere else, the freezer needs t...	[ "Biology student + Was a mouth breather - Sore throat - You'll inhale more microbes and bacteria since there is no filtration system in your mouth - Your teeth gum will be exposed more to bacteria, resulting in inflammation. - Bacteria in your teeth will flourish since they have more oxygen resulting in more teeth ...
With the recent announcement of sperm blocking birth control, what happens to the sperm that get blocked?	[ "re: Vasectomies In a vasectomy, the sperm doesn't go anywhere. The vas defrentia (singular: vas deferens) are severed, or clamped, or severed and clamped depending on the urologist's choice. Sperm continues to be produced but cannot exit through the penis, as the tubing that allows egress is blocked. Sperm cont...	[ "Basically, it's paint. Take a look at [this](_URL_0_) picture. One half of his face is covered in sunscreen, the other half isn't. The sunscreen isn't transparent to UV, so it will be absorbed, preventing sunburn and lowering your temperature." ]
Have humans evolved major differences in the brain that affect things like intelligence, logic and creativity, or are these simply varied based on social and cultural influences?	[ "Humans have evolved different traits, but it is not known which. From an evolutionary perspective, many different cultures have definitely been seperated long enough for biological differences to evolve. But it is not clear in which areas differences have evolved. For instance, I can see no reason that one culture...	[ "Setting aside the terminology of \"race\", it's entirely down to selective pressures of the different environments. In equatorial regions where the sun is plentiful, having a lot of melanin is useful in protecting against cancer. The further north/south you go from there, the less sun there is, so having less mela...
How does Percussive Maintenance work? (a.k.a smacking something like a TV until it works again)	[ "There are a bunch of theories ... but most probably if you have broken solder-joints or weak connectors it can smack them back into place so the set starts to work again." ]	[ "“The state itself is a non-entity for the peasant and he can neither see nor comprehend it, but he knows the landlord because he lives with him.” – F. Marwitz If you look at the East German states before the emancipation of the peasantry (the dates vary, but for a reference, Prussia emancipated its peasants in 180...
What does the "in A minor" or "in D minor" in classical music songs mean?	[ "I'm going to have to say the \"feeling\" explanation is incorrect. It's true that minor songs can feel \"sad\" but there are plenty of minor key songs that don't. The \"in D minor\" in classical music refers to the key and the mode. The key is D and the mode is minor. They both refer to the pattern of notes. Note...	[ "There is a back door into every house. People put alarms all over their house. Have a key? You can get in the front door. When you need to break in you use the back door. Now only bad people use the back doors. So when someone comes in the back door, the alarm goes off. Your crack is a bad person, technically. He ...
Why was there never a Half-Life 3?	[ "It just...didn't happen. Valve envisioned the episodes of HL2 to be HL3, they were never going to make a new full game, so we got some of it. But Episode 3 will never be released, thus the plot will never be completed. No one really knows why, as Valve has more than enough resources. & #x200B; A general synopsis ...	[ "It is impossible to make any software absolutely perfect. Development is a very long process and releases are timed with an estimate on when it will be done and coordinated with marketting. Would you rather every game be delayed at the last minute because a clipboard animates like a shield?" ]
Why does everything sound loud at night?	[ "In my experience, it’s just relative. Think of when you turn the AC way up in your car and then play the radio for a while. When you turn the fans off, the music seems kinda loud. The music didn’t actually get louder, but ambient noise decreased. At night, far far fewer people are out driving or operating machiner...	[ "You could have [tinnitus](_URL_0_). You should see a doctor if you want any further information, since asking for medical advice is not allowed in this forum." ]
Why are computer error messages a mixture of numbers and letters instead of an actual useful and understandable message?	[ "That mixture of numbers and letters is a useful and understandable message. It's just not intended to be useful or understandable to you. The programmers who wrote the code can use that information to help debug the root cause of the crash. There's no way to make an error message for every possible contingen...	[ "Lower right corner, there is your tray, click on the icon that looks like a keyboard, and change the setting to US English, or just US. If you don't have this little icon, look for a little taskbar that can be anywhere on your screen, usually at the top. Change it to US settings. It happens whenever you change yo...
What is the biggest known war between Native American nations in the Americas? (North America, Mesoamerica and South America)	[ "Roughly a year ago I wrote an answer about [evidence for large scale conflicts in North America before contact](_URL_0_) that you may find useful. Other comments in that thread discuss fortifications throughout North America, as well as diving into warfare patterns." ]	[ "This is not quite the case. Swords and bows have not appeared in \"every culture.\" The melee weapon of choice in the ancient Andes, for instance, was the mace. These are represented in the art of several cultures: [Moche](_URL_4_) warriors, both [mythical](_URL_5_) and [real](_URL_6_) are seen on ceramics; Recuay...
Why isn't the minimum wage on a sliding scale that is automatically adjusted for inflation?	[ "There are many (not all) Republicans who oppose automatic increases because they have constituents who oppose any minimum wage at all. There are many (not all) Democrats who oppose automatic increases because they don't want to lose the issue. The ability to make raising the minimum wage a campaign issue every few...	[ "Because they would get sued. The legal system isn't like some kind of beep-boop robot that overlooks totally obvious loopholes. Any company that claimed \"No, we were really advertising the endorsement of Bill Gates, plumber, from Bumfuck, Nebraska.\" would get laughed out of court. As /u/Snewzie pointed out with ...
How does Vanta Black work when it comes to absorbing light?	[ "Vantablack consists of a lattice of alligned carbon nanotubes of specific width to trap the electromagnetic waves of wavelengths specific to visible light. Within the layer of vantablack that is coasted onto a substrate the light continuously bounces between the nanotubes becoming more and more absorbed, of which ...	[ "> and we never will see the object disappear into the black hole We will. You'll quickly receive the last photon ever. Mathematically the intensity will never go to zero, but a 10^-100000000 chance to receive another photon in the future isn't going to matter in any way. If you want to have something that stays vi...
How do we know that the universe is 13,7 billion years old when time is relative? Who's time do we follow in this assumption?	[ "When we say the age of the universe is about 13.8 billion years, we mean as elapsed in the so-called isotropic frame, which is operationally defined as the CMB rest frame (the unique frame in which the CMB is isotropic). For more details, see [this thread](_URL_0_)." ]	[ "We don't. The concept of things being greater than we can perceive is kinda the only thing that keeps religion going. It is not just possible but probable that we are part of a larger structure of some sort. Unlike, say, mites we have a brain capable of understanding it though. We just have to get a better picture...
Did the Nazis have plans following a successful invasion of Russia and the UK?	[ "Some answers can be found in our popular questions page, under [Axis post war plans](_URL_0_)." ]	[ "There was no need to because: - Sweden already produced and sold iron ore. - Shipping is by far the cheapest means of transportation. Kiruna (the place where most of the ore comes from) is nearer to Narvik than to any other navable port/waterway. - Baltic sea tends to freeze. In the end, it would have been a total...
How do they measure rain and snow?	[ "No, because as the surface area that the container covers increases, so does the amount of precipitation that it's catching. Assuming you're not at the edge of the clouds dropping the precipitation, the amount of rain/snow per unit area (let's say 1 mL per square meter) stays the same. So, if I have a container th...	[ "They often have a number of people who fill in viewing diaries in return for a small payment. Extrapolation to the whole population, similar to opinion polls, gives the total audience. Other methods use recording boxes to work out what channel the tv is timed to over time." ]
Why did the 2008 financial crisis happen? If the problem started in the US why other economies were so heavily affected why some weren't affected as much? What makes such crisis so unpredictable?	[ "A lot of people who were supposed to assess the riskiness of a lot of investments weren’t giving accurate risk assessments. Some of the risk-assessors didn’t fully understand how complicated their task actually was. Some of those risk-assessment groups lied about the risk associated with the loans — some borrowers...	[ "The type of crime where being 'least expected' actually matters is exceedingly rare. Most crime is not Ocean's 11-style heists, but either interpersonal conflicts (where the location of the crime is dependent on the location of the individual you're targeting) or opportunistic crime (where the location of the crim...
Is it possible to change the shape of a subatomic particle?	[ "You can change the \"shapes\" of atoms, nuclei, and in principle any composite particle. You just have to subject them to some kind of external field, for example an electric field." ]	[ "Nothing \"tells it to\" the changes dont happen during a creatures life, the changes come from mutations in the genes of offspring and nature decides which ones live and which ones die. When a mutation happens its usually bad but rarely a mutation can be beneficial. Take polar bears. Some time a long time ago a be...
Does gravity cause relativistic effects, or is it the other way around?	[ "Because of the Equivalence Principle(s) in GR, gravitational forces are no different from inertial forces which arise in non-inertial frames. For these inertial forces though, we have to introduce an extra force to introduce deviation from linear motion. Gravity, on the other hand, needs to preserve free motion wh...	[ "> If the time dilation (w.r.t. a \"far off\" observer) approaches infinity as one approaches the event horizon of a black hole, how can anything ever fall into a black hole from an external observer's point of view? You're exactly right. Things crossing the event horizon seem to take forever from an outside point...
Is there an example of a Non-native culture that has successfully integrated its aboriginal population, and if so, how did it do so?	[ "On a recent trip to Queenstown in NZ, I was surprised to see the amount of respect show towards the Maori population and their culture. It was odd, as an Australian, to see such a proud embracing of a country's indigenous cultural heritage. I was watching the NZ morning news and the weather was read twice, once in...	[ "Seems like the American occupations of Germany and Japan fit your bill. They were pretty militaristic, nationalist-type polities before 1939; now they are liberal democracies where the mere mention of upgrading the military is controversial." ]
How can astronomers tell the difference between gravitational lensing and refraction?	[ "It turns out that refraction has wavelength dependence, whereas lensing is a manifestly wavelength independent phenomenon. Astronomers actually probe data for wavelength dependent 'lensing' to test for this in order to confirm that what they're seeing is lensing and not simply refraction." ]	[ "Various reasons, but generally it's atmospheric distortion due to temperature gradients. Think about opening your door in the winter and watching the air shimmer as the heat goes out, or looking over a hot car in the summer. Same effect, larger distances.:)" ]
A new video game is coming out that takes place from 303 BC to the rise of Augustus. The game is NOT focused solely on Rome but also Europe, Northern Africa, and Western Asia. I know next to nothing about the events of this time period, what are some good books to inspire my gameplay?	[ "Question for OP. Since I didn't see it in the post, is the game Imperator: Rome?" ]	[ "Your book may not necessarily be obsolete, or an unreliable source. This is the checklist I use for evaluating books. Publisher: is it published by an academically reputable publishing house? Author credentials: is the author qualified within the field they’re writing about? Citations: has this book been cited i...
Why do wind turbines spin much faster when there is no out wind. Also, I see them barely moving when it's quite windy out.	[ "Both are good explanations : /u/ZenitalEquidistant > The pitch (angle) of the blades can be changed to make the turbine spin faster or slower for a given amount of wind. The energy market changes by the minute, and it may be at some times it's simply not economical to run the turbine as fast as it will go. /u/att...	[ "Let's imagine that you have a small water mill and a glass. If you use the glass directly on the water mill, the water mill will not turn regularly because you need to refill your glass with water. Now, let's use a funnel between your glass and your mill. You are now able to run your mill. (Most of sand mill toys...

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