Subset (10)

eli5 · 25k rows

Split (1)

train · 25k rows

query stringlengths 20 300	positive listlengths 1 1	negative listlengths 1 1
In movie, sieges on castles often depict arrows randomly flying into the crowds. Wouldn't they be more likely to aim at those carrying the siege equipment? How were those men even able to make it to the castle walls with such targets on them?	[ "Hi, hopefully one of the military flairs will drop by to address the specific scenario of firing on attackers in a siege, but meanwhile, you may be interested in a couple of threads addressing the general strategy of firing in volleys * [Did those showers of arrows really exist?](_URL_5_) - featuring /u/MI13 * [Wh...	[ "As /u/Arpikarhu says, it's a mirage. /u/LondonPilot used this explanation in a previous answer: When it's very hot, the ground gets heated by the sun. The ground then heats the layer of air closest to it, by conduction. Given time, the hot air will rise - but initially, the air near the ground is hotter. Light fro...
Why are freeway pavements made out of cement but street pavements are made out of asphalt?	[ "I'm not a civil engineer but I think it has to do with the amount and type of traffic the road is under. A residential street will only have to endure slow infrequent traffic but a major interstate has cars on it 24/7 including everything from motorcycles to your neighbors new double wide house. unlike concrete, I...	[ "With a manual transmission, if you don't depress the clutch pedal and attempt to select a gear, you'll be causing the syncromesh, essentially a small clutch, inside the gearbox to slip. Doing this puts excess stress and wear on the synchro so don't make a habit of it, you should use the actual clutch for moving of...
When Crusading armies came back to Christendom, what knowledge did they bring from the Middle East?	[ "They didn't just crusade in the Levant, and a lot of what they gathered was philosophically important, rather than technologically; there was quite a lot of warring in Iberia as well, and in 1085, Christians captured the city of Toledo with the contents of its famous library intact. A flurry of translation followe...	[ "depends on your measuring stick. people did what was best for them given the amount of natural resources, environment, etc around them. for example, maybe europeans had guns, but tomatoes originated in central america. where would you be without tomatoes? guns have little to no effect on your life, but i bet youv...
What are those "streamers" that are often seen next to atomic mushroom clouds?	[ "[Rockets used to gauge the strength of the blast](_URL_1_) [Edit: better source](_URL_0_)" ]	[ "Edited: I have heard two things... * Rockets sent up to record various aspects of the test. * Vertical smoke flares which are used to observe the shockwave Edit 2: [Seems like it is a combination of the two](_URL_0_): > Sounding rockets or smoke flares may be launched just before a device explodes so that their v...
When looking up the difinition of a word, how are we supposed to read the "Pronunciation" text.	[ "It's usually in [IPA](_URL_0_). This is a standardized system used for representing the sounds used in language." ]	[ "A sentence example might help: You need your password and login to access your account details. [NOUN] You need to log into your account to see the details. [VERB]" ]
Why do Humans get aroused watching others having sex?	[ "Our brains have [mirror neurons](_URL_1_), which fire both when we do thing X and when we see thing X being done by someone else. They allow us to hurt when others suffer, be happy when others are joyful, and, well, become aroused when others fuck. Edit: [Here](_URL_0_) is some support for my claim. I'm aware that...	[ "Why pay for the next Star Wars movie when old episodes of Buck Rodgers is available for free. They are pretty much the same, right? While many people see porn as a single use commodity, there is a core of hardcore porn fan (hardcore fans, not the porn). They have performers and series they like and follow, and whe...
During the Cold War, how close were we actually to war? Whether nuclear or conventional?	[ "During the 1983 Soviet nuclear false alarm incident, the situation got extremely close to serious danger. Stanislov Petrov was at command of the Oko nuclear early warning system. While he was serving, the warning system reported twice the launching of U.S. missiles. Petrov made the decision that these were false a...	[ "/u/flooey is right, but in addition to that: we have a lot more in common than people realize. For the vast, vast, vast majority of political issues that have been debated through the ages we have essentially a consensus on how to answer them. We are not going back to the gold standard, we don't want a king or que...
How difficult would it be to forge a government seal during the Middle Ages and are there any historical examples of this occurring?	[ "/u/keyilan gave an [excellent answer](_URL_0_) to a similar question in [this thread](_URL_1_)" ]	[ "Hi everyone. Since this is the kind of question that can attract non-expert responses, just a friendly reminder that all responses must comply with [sub rules](_URL_0_), and that [personal anecdotes](_URL_1_) are explicitly not permitted in /r/AskHistorians." ]
Why are there so many "engineers" for everything? As in: what even are "Social Engineers?"	[ "Engineering can generally refer to any activity that requires investigation, analysis, and design of a \"solution\" to some \"problem.\" Need to cross that river? Civil engineer will design a bridge. Need to blow up that bridge? Aerospace engineer will design the weapon. As far as a \"social\" engineer, this refer...	[ "It used to be done with a theodolite, (link attached). _URL_1_ This is a precision piece of surveying equipment. The surveyor would establish fixed points near the construction site and set the theodolite over the known point. Then, observations would be taken on the work in progress to insure its location was ac...
Why can't cancer just be "cut out" and what makes it inoperable?	[ "Inoperable means is wrapped around / through something important or behind something important. Not reachable w/out causing more damage. Also no tall cancers are clumps that can be snipped out. Mising bits is bad Cancer cells can become loose in the bloodstream and get lodged/grow else where, i.e. metastasized. ...	[ "Phones are already expensive. Using the absolute best parts available at the time to create some überdevice would cause the price to skyrocket and only a select few people would be able to afford it. It would probably cost the company more money to put something like this together than they could earn by selling i...
Why is the U.S. the closest ally of Japan even after WWII?	[ "Imperial Japan died at the end of World War II. The US then embarked on a nation building campaign that has never really been equaled. We rebuilt Japan from the ground up. Their economy, their society, their technology, everything. Then we forbade them from having a large military (they only have a Self Defense...	[ "The change came with the meeting between Nixon and Mao. Reading up on that meeting might be a place to start. The relationship between China (PRC) and Taiwan (ROC) is interesting. Both governments consider them to be one country. As long as the exiled-government-of-China-which-resides-in-Taiwan continued (and cont...
What were battles between Native American tribes like?	[ "I can't speak for all tribes, but let me forward you to [this answer I gave before](_URL_0_). In short, it depended upon the goal of the battle -- was it a raid to take slaves/captives, a reprisal raid for an insult, or something else?" ]	[ "Is there a specific region and time period you are interested in? If not, your question would break our \"poll type\" question rule." ]
What was American society like before 9/11?	[ "We weren't always obsessed with terrorists; that's the biggest difference. When we had military engagements, we went in, took care of business, and left. While there might have been government spying then as well, it would have been an even bigger deal when it was uncovered, instead of even somewhat justified. So ...	[ "Hi there -- while we've approved this question, we would like to remind potential respondents of our [current events](_URL_0_) (AKA \"20-year\") rule -- it's fine to discuss events through 1997 (inclusive) and their effects, but not events after 1997. Thanks!" ]
Why has humanity survived for uncountable generations when all things deteriorate over time? Wouldn't the quality of genetic material passed on get worse?	[ "> ELI5: How does Evolution work? Fixed that for you. Those who were of inferior genetic configuration were sorted out by procreating less." ]	[ "Let's say you have a 7 lane interstate. At each end there is a toll booth. In the past payments were processed manually and there was a receipt that had to print, but the printers were slow. Only do much traffic could get through. Fast forward to the future where you pay with the touch of a button and get an insta...
Why is salt water supposed to help heal wounds and bruises?	[ "In the case of mouth sores and lacerations, the idea is that warm salt water helps draw some fluid out of the affected area, thus reduce swelling, and speed up healing." ]	[ "You know how a lemon battery works? One metal object, another different metal object, and an acid electrolyte between them. Replace the former metal object with foil, replace the latter metal object with your fillings and replace your saliva for the lemon juice. Now you have electrons whizzing between the foil and...
What is identity theft? How can someone become someone else?	[ "Identity theft is a catch-all term meaning that someone has taken information that identifies you and uses it to pretend to be you. Usually, it involves going into your social media accounts and posting spam messages or opening up credit card accounts in your name. They generally don't physically present themselve...	[ "There's an option on most mid-grade wifi appliances called exclusion (I think?). Anyways, it's designed to do exactly this, make it appear like you're the only one on the network. I've never really looked in to how it works, but I'd imagine it's just blocking arp traffic to anything that's not the AP. If you want ...
Did Venus used to resemble Earth, and is it possible with global warming that the Earth could one day have the same atmospheric conditions and runaway greenhouse effect that Venus currently has?	[ "The major difference between Venus and Earth is thought to be the temperature difference (caused by being closer to the sun) shifting the equilibrium of the [silicate-carbonate cycle](_URL_2_). On Earth the cycle generally means that carbon gets locked up in carbonates - that's the major reservoir of carbon on ou...	[ "Funnily enough, plants are our primary machines that combat atmosphere pollution. Plants use sunlight to convert carbon dioxide in the air with water from their roots to form sugars and oxygen. So essentially, planting a lot of trees will consume the carbon dioxide we pump into the air with coal and oil plants, al...
Do we have conclusive evidence of water existing outside Earth?	[ "When something is hot, it gives off light at specific wavelengths. We know what kind of light water molecules produce, so we can detect them. Another place where we see water is on comets, which have a large amount of ice. This evaporates when comets move near the sun, and the tail of the comet is largely water."...	[ "We do, there was the Galileo probe around Jupiter, the Cassini probe around Saturn, and there's another one on the way to Jupiter." ]
Why is Nickelback so universally hated, even by the likes of other musicians yet they've continued to win/get nominated for awards?	[ "I really just think everyone is jealous. They keep pumping out the tunes that (as detestable as it might be to think) a lot of people (clearly not Redditors) like. Why? Chad K, when he writes, researched what makes a hit. What keys, what lyrics etc. of all the top 50 songs, and he writes their music using that. Th...	[ "Nielsen does this, they tell you how on [their website](_URL_0_), but basically they just randomly select people and track everything they do by asking them to write down everything and walk around the streets with microphones to record whatever people are listening to. They aggregate the data and produce the rati...
If Earth has the conditions for life to be created, why did it only happen once?	[ "We don't know. We don't know if it's happened just once. We cannot form a complete characterization of the conditions on Earth throughout the Hadean and Paleoarchean to begin assessing how many times life may or may not have arisen. It may have happened numerous times. The lineage in existence today may simply hav...	[ "Because the shuttle itself was expensive, unreliable and overall a boondoggle. Reusable reentry vehicles are prone to wear and tear that single use vehicles are not. There are a number of factors, but safety and cost are primary among them." ]
Does Cuddling With Animals Release Oxytocin?	[ "As a followup of sorts, do children experience an increase in oxytocin when they cuddle toys or stuffed animals? Particularly when they are emulating a parent-child relationship?" ]	[ "[This article explains why.](_URL_0_) TL;DR \"Cute Aggression\" is the brains response that could be protective, or a way of venting extreme feelings of giddiness and happiness" ]
Why do we have to become Lucid in order to control our dreams?	[ "My understanding of lucid dreaming is that it is when you are aware that you are dreaming during the dream, that this awareness allows you to control the dream to some extent, and that it is all a skill which can be improved with practice. I've only been able to do it a few times and never consistently, but it doe...	[ "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...
do airplanes need yaw?	[ "Airplanes need yaw control not to intentionally yaw the plane (unless you're doing some really fancy stunt), but rather to be able to counteract unwanted yaw. Generally rotating about the yaw will not do anything useful and will be actively bad for 'normal' flights, so yaw control is there to try and correct for e...	[ "Y=(AX+B) mod N is the standard. I wouldn't use it to encrypt communication from Russian subs, but it works for most stuff. A and B are chosen constants, N is your range, X is the seed, Y is the output, which becomes the next seed." ]
Why do we send millions of dollars of aid to Saudi Arabia, one of the wealthiest countries in the world?	[ "The US provides about $1.5 million in the form of International Military Education and Training (IMET), which is joint military training in order to advance our common interests in bilateral security operations. Basically it is training Saudi military officers to work with US military forces in the event that is r...	[ "Karachi (largest city in Pakistan) is currently experiencing some large problems; both in crime, and politically. This is in part due to [Altaf Hussain](_URL_0_) who is the founder and leader of the [Muttahida Quami Movement](_URL_1_) - a political party in pakistan based in the city of Karachi. The problems surro...
Why do MMA fighters do down in just a few, if not one, punch while boxers take dozens and keep standing?	[ "As an MMA fighter, you can also fight on the ground. So falling can mean something different & if you do it right, you could possibly get the advantage. If you're talking about KOs, it's all in the gloves." ]	[ "Think of the packages like a fire hose, the water traveling through them is the data (such as streaming Netflix, watching YouTube, Etc). The 2Mb/s (Megabits per second) is like a garden hose. The 100Mb/s is like a fire hose. However that's not all there is to an internet connection. If you visit [_URL_2_] (_URL_1...
Is there any real proof that educational recordings that you listen to whilst sleeping actually work?	[ "Current consensus is that \"educational recordings that you listen to whilst sleeping\" do not work. Sources: * [50 Great Myths of Popular Psychology: Shattering Widespread Misconceptions](_URL_0_) * as well as all current textbooks in neuroscience =) All the experiments were done in the 50s, as it was when the cl...	[ "I think the responses you've got so far indicate that it isn't very reliable. The whole thing is based on a sample. A sample of people are given set top boxes that monitor what they are watching. This sample is then scaled up to the whole population with weighting bias added in so that they can account for the 'av...
How does an A.C motor work?	[ "Mehdi Saghadar - Electroboom channel does a few videos teaching about AC. Assuming you know how AC works, skip to the 8 minute 10 second mark and watch Mehdi do his thing. _URL_0_ Otherwise watch 'em all. He goes into shockingly funny detail about how things work." ]	[ "Air conditioners have become more efficient over time with better compressors, ~~better~~ safer refrigerants, and better insulation (pipes, ducts, and buildings themselves). In the US government standards on efficiency ([SEER](_URL_2_)) have also increased accordingly. You can't buy older, less efficient AC units ...
what measures prevent scammers from establishing GoFundMe on false premises, and just walking away with money?	[ "Laws against fraud. If I raise $5 million to develop a \"widget,\" and then I just take the money and go to Mexico, chances are there are going to be some people who will call the FBI on me. But, hopefully, a person's common sense and intuition will prevail. PS. people are arrested all of the time for Gofundme fra...	[ "Unfortunately there isn't always a way to tell. There are mechanical kiosks at big box stores that copy keys for a small price. In that case there is no verification, like you said - There's no proof that you aren't a theif required for copying a key. Edit: That's why most landlords buy keys with \"DO NOT COPY\" ...
As historians, how do you feel knowing things that the people of the times could not possibly have known?	[ "There are certainly events where one has to make a deliberate effort not to judge with hindsight. The best example was given to me by a professor in a class on Weimar Germany: German history in the 1920s was not, and should not be seen or written as, 'Waiting for Hitler'. There is certainly a tendency to see histo...	[ "Hello prospective respondents. Everyone loves to talk about food (and drinks!), so just a reminder of which sub we're in: it's /r/AskHistorians so no personal anecdotes, urban myths or conjecture. Respondents here are expected to have expertise in the subject, offer in-depth information and cite *reputable s...
What were typical Irish foods before the introduction of the potato?	[ "I have always enjoyed the observation of E. Estyn Evans in his classic study, Irish Folkways (1957: \"Butter spread thickly on fresh bread is a tasty if simple food, and one suspects that in pre-famine times, the staple was butter and oatcake rather than oatcake and butter. When bread was made from gritty quern-gr...	[ "Read Bill Bryson's book, At Home. There is pretty much an entire chapter on the history of condiments and such. Fascinating." ]
How can google search the entire web in less than a second and my local computer takes 10 seconds to find a file on my computer?	[ "Indexing. Google basically keeps a list of keywords and the websites they appear in. When you search something it just needs to access this list. You can also enable indexing in your computer, either through the windows settings (just google \"windows indexing\") or using a program like [everything search engine](...	[ "They don't, although you can have an experience like they do. If you just use the system without any changes and updates, it will work exactly as it always had. But looking at just phones for example: every year there are new phones out and old phones get binned. Samsung releases new galaxy models all the time, so...
What would happen if a nuclear bomb was detonated in a 1km thick block of steel?	[ "Now that I think about it, you could calculate the effects to get a very rough idea of what would happen. I could try if you want, but I would need you to answer pretty much only a single question: What is the yield of the device? Using that I can calculate the probable internal pressure of the block, a rough est...	[ "It's similar to the principles behind a volcano. Pressure keeps building up and building up in one specific point. However, there is some strong material resisting that pressure, in the volcano case it is the dirt, rock, and metal sitting above it, and in the book case it's the pages sitting under the press. Howev...
In Star Trek, if the universal translator translates alien languages, how can Klingons still speak Klingon in front of Humans and not have it sound English?	[ "Dramatic effect, really. You need the universal translator for the plots to make sense without your audience having to learn Klingon, but you don't want to ditch the cool 'alien culture' aspects. Bam, you're boned, you just have to fudge it." ]	[ "Bell's Theorem put a limit on quantum mechanics. The simplest way of phrasing it is that a \"local hidden variables\" theory cannot explain experimental data. Local means that any sort of signaling happens at the speed of light or slower. Hidden variables means \"maybe there's some other thing that is more fundame...
Why is the US military spending so much money on the F-35 joint strike fighter?	[ "If you have specialized jets for each need, then the response time could be far greater than is required. Think about like there was an ambulance for burns, an ambulance for gun shots, and an ambulance for cardiac arrest. Maybe no one's having a heart attack, but someone shot up a bank. There's only 2 gunshot ambu...	[ "It's not actually feasible, nor is it actually happening. All those articles about cool 3D renderings that have nothing to do with what NASA is working on. There is a guy there who has made a few powerpoint slides and a picture of an optical table, but there are no plans to make a faster than light spaceship." ]
Radio Wave Contradiction	[ "The signals in your ethernet and fiber optic cables are also travelling at (effectively) the speed of light, but you still have a multiple-millisecond lag because your NIC, router, modem, and the two dozen routers between you and your target all need time to, you know, route. Any walkie-talkie I've ever used has...	[ "Interference. You can stop it by using a hard-wired connection instead of wireless. Failing that, reposition your wireless access point or your microwave." ]
the subreddits fifth-,sixth-, and seventh- world problems	[ "Satire, all satire. They make fun of \"first world problems\" and take it way further." ]	[ "Honestly, I think it may be better if you posted this to /r/locksmiths of the more active /r/lockpicking . I would expect that in the security-concious modern world mere 'tradition' would not be a reason that the practice has continued." ]
Why do house gecko's have low awareness but move really fast.	[ "Their speed is mostly for catching insects. They avoid predators using camouflage and hiding rather than speed generally." ]	[ "Many mating displays are a way of showing off how much extra energy you have to spend. Generally, having good genes means you hunt better and get sick less often; only creatures with strong genes can spend the time and energy doing a mating dance. Thus, by watching to see who does the best mating dance, potential ...
If the ice caps carrying on melting at their current rate, roughly when will Arctic shipping lanes become a major thing?	[ "Somewhere around 2040-2060 according to a [recent study](_URL_0_)." ]	[ "The wiki article you linked seems to answer your question to a certain degree: > Olympic returned to civilian service after the war and served successfully as an ocean liner throughout the 1920s and into the first half of the 1930s, although increased competition, and the slump in trade during the Great Depressi...
My diploma refers to the 'rights, responsibilities privileges and immunities appertaining thereto' of the degree. Was there a time in history that these were really meaningful?	[ "This is still relevant in some professions even today See this discussion of the phrase by a recently graduated \"Doctor of Medicine\" _URL_3_ variations are common > all the rights and privileges thereunto appertaining For the United States things are pretty limited, but generally the rights and privileges are...	[ "Here is a wikipedia article and 2 discovery articles that will help you understand more about this topic. Although there are common rat-like ancestors, there are also better intermediate examples that were amphibious and maybe give a better resemblance. On the size thing, there are only speculations of course, bu...
What happens to cars that are recalled due to safety issues?	[ "Typically, you just go to your local dealership and they fix the car for you. Rarely will you get a new car, or a loaner car, since these fixes are often things that take only a few hours. They're really no more inconvenient (usually) than standard maintenance." ]	[ "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...
Do thrusters work in deep space?	[ "You have mass that is accelerating away from the space ship. For every action there is an equal and opposite reaction... as the thruster allows mass to accelerate in one direction away from the ship, the ship is pushed in the opposite direction. Edit - Imagine you are floating in space, and have a wrench in your h...	[ "A few different ways; - [Lasers](_URL_0_) for really close things like the moon. - [Parallax](_URL_2_) used for nearby planets and stars. - [Standard candles](_URL_1_), the brightness of a specific type of supernova which gives a good range. - [Red Shift](_URL_3_) for things very far away. For more detail on how a...
What prevents a tower crane from toppling over?	[ "So... For one thing, they have a big 'ol counterweight on the back end of the crane, so that when they lift heavy things, the heavy things put less stress on the metal truss structure that holds the train. They also make said truss structure super sturdy so that it can withstand the tremendous forces it is subject...	[ "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...
Does the colour of coffee have any relation to how long it stays hot or it's temperature?	[ "The coffee with two scoops will cool faster, and it has nothing to do with color. Water has higher heat capacity than coffee, which means that the higher relative water content, the more heat it needs to lose for it to decrease in temperature. _URL_0_" ]	[ "The main idea behind baggage x-rays is that a bag has to be scanned thoroughly in a short period of time, and that different items are to be scanned. To help with that, they use colours since we are more prone to notice colour difference. The colours vary with density- increasing tends to blue so the dense metals ...
In the recent Falklands referendum, Argentina requested for there to be no international observers from Latin America, why?	[ "Argentina doesn't think the issue is whether or not the people living there want to be part of Argentina; they claim that the people are British citizens, living on illegally stolen Argentine land. So by taking part in observing the referendum, Chile and Mexico look like they're saying the result of the vote is im...	[ "This has essentially been answered by the preceding comments, but what hasn't been contributed is this: _URL_0_. Muster and enrollment records, transfer lists, honours lists, etc, for the period of 1730 through 1898. Worth having, OP, if you're writing or researching the topic academically. To succinctly summarise...
What is that weird feeling we all get when we accidentally miss a step or take a step thinking that it the ground should have been "higher" or "lower".	[ "Adrenaline. Your body briefly feels like it is freefalling and the panic response floods you EDIT : although I would have said that the feeling started from my stomach" ]	[ "We don't hear our voices in the exact way they come out of our throats/mouths. Because of the echoing of bone and sinuses in our heads, the sound is different to ourselves. Someone could easily believe they are emoting more with their voice than they really are, because the subtle little changes might only be hear...
What is entropy, and can it be reversed? If so, how?	[ "Entropy is basically disorder. Things naturally have a tendency to go from a more ordered to more disordered state. On a local level, it is possible to reverse entropy, but it takes energy. A good example, someone bumping the table knocks your neat tower of Jenga blocks into a messy pile. You can stack them back u...	[ "Have to recommend you watch this video by \"vsauce\" on Youtube: _URL_0_" ]
How is it that approaching rain has a smell? What is it that we're smelling an hour before a storm arrives?	[ "My old organic chemistry professor explained the smell of rain coming in class once. It's also on his [website](_URL_0_): > People often think that they can smell rain coming before it actually starts to rain. Strange, as we would be in rough shape if we actually could smell water as it makes up most of our bodie...	[ "Because weather (and most other systems) evolve forward temporally from some starting conditions, we can't go from now and model the past weather because what the weather is now has emerged from past conditions and not the other way around. However, weather models are tested using what is called \"hindcasting,\" w...
why do otherwise heterosexual men molest boys so often?	[ "I challenge the premise of your question. Logically, someone attracted sexually to young boys is by definition not heterosexual. What is the basis for \"otherwise heterosexual\" in this context?" ]	[ "Imagine you’re a wrinkled shirt. Masseuse straightens you out so you’re nice and unwrinkled. But some people are so use to be wrinkled, they don’t know how it feels to be unwrinkled. That’s my best ELI5. I tried." ]
How can I use the touchscreen of my phone even after putting on a screen guard or a protective mirror on meaning I’m not directly touching the touch screen?	[ "There are 2 types of touch screens, 1 of them works by touch, the other one is more complicated one. Phones use the more complicated solution, as this allows you to use a nice looking glass screen. Multiple times a second, your phone sends an electric signal on an layer behind the screen, starting in an corner, an...	[ "It's not going to be spoiled in the true sense. Spoiled is when food has bacteria/microbes growing in it that have started to change the food in some way, as a byproduct of starting to digest the food item. Almost all surfaces are covered in microbes, and certainly anything in a regular home is. Whether there are ...
Do acidic and alkaline foods effect the ph of the blood? If so, what physiologically is happening during that and what is happening to balance ph?	[ "While you can probably change the pH of your blood slightly and temporarily, your blood has its own natural buffer system to keep the pH constant: carbonic acid and the bicarbonate buffering system. Basically, when something acidic or basic is introduced to the blood, this equilibrium system will basically \"add\"...	[ "I'll have a crack at explaining this at ELI5 level. You know about powers of ten? Going from 10, to 100, to 1,000? Those represent three powers of ten. You could say that 1,000 could be written as 10^3. You could also say, \"Hey, I'm going to say this number and it means not juust the number, but the power of ten...
Some of these business related questions I have inside, a lot pertain to financials.	[ "a) valuation is a guessing game in many ways. It has to do with current sales as well as future projections. It basically comes down to how much people are willing to pay. What you want to see is a good return on your investment so people don't really care about gross revenues as much as they do net profits. They ...	[ "A big one is, well, most of the bible. Was there a united monarchy? If so, what did it look like? Is there something behind the Exodus narrative, or is it a myth to give the Israelites a history separate from the other Canaanite groups?" ]
is there a chemical reason we don’t make banana jam or jelly? Or is it just some weird flavour preference that the whole world seems to share?	[ "Jams and jellies didn’t come out of taste preference. They were invented so people could enjoy that fruit year round. Since Bananas are good all year people never preserved them, and therefore, never became a type of jam or jelly." ]	[ "PB & J is very cheap and easy to prepare. Restraunts that cater to convenience have to produce meals at a quality and for a price that customers would rather pay for than use their own time and resources to make. Things like ham sandwiches will be made with nicer meats, cheeses, and breads than the average person ...
What happened to the Global Cooling scare of the 1980's?	[ "There wasn't a Global Cooling scare in the 1980s. The people who claim there was are lying in order to sell their bigger lie that there's doubt about global warming. > Where does the myth come from? Naturally enough, there is a kernel of truth behind it all. Firstly, there was a trend of cooling from the 40’s to ...	[ "There is more that can be (and has been) said, but you may be interested in these two answers by /u/Chamboz (as well as others linked within them) regarding why scholars no longer hold with the idea of a precipitous and constant fall: [The Ottoman Decline Thesis is completely discredited, but does the theory have ...
Why is it ok to keep baked good that contain egg/milk out at room temperature but not fried or scrambled eggs.	[ "Baked goods typically have very little water per unit volume so they are reasonably inhospitable to bacteria. Also for most baked goods you've cooked the eggs and milk all the way through, killing any resident bacteria. So they'll last about a week. With scrambled or fried eggs you don't always cook the egg all th...	[ "The bacteria that grows on meats (esp chicken and pork) are matured and the meat may be rotten by that date. If cooked, bacteria is killed and the meat is given a new state, which is cooked. Think of it as the meat being given a new life after getting close to dying." ]
Why are the winters in Chicago is harsher than Istanbul while both are at same latitude?	[ "Because there is nothing between Chicago and the North Pole but flat plains. Turkey is itself mountainous. Furthermore the prevailing winds move West to east at that latitude, which contributes to Western Europe's mild winters which doesn't effect Turkey, but the Mediterranean does and it is large and warm enough ...	[ "A big part of it is where the sensors are. I'm in DC, but my understanding is that all of the weather reports are based on measurements being picked up at Dulles which is an airport a few miles into Virginia, away from the city." ]
why would amazon receive 3 billion in subsidies if they had a headquarters in New York?	[ "Governments give tax breaks and subsidies to corporations to lure them in to their area. The idea is that bringing that business to the area will, ultimately, bring more business and jobs to the area which, theoretically, will bring jobs to the locals and more tax revenue for the government. Again, theoretically, ...	[ "Reddit is hosted on AWS, which is many massive server farms. One of the advantages of providers like AWS is that when high traffic hits, you can have your system automatically spin up additional servers to handle the load, and then to shut them back down once the demand goes down." ]
Why do you get white when you mix all colors of light, but brown when you mix all colors of paint?	[ "The full spectrum of all colors of light together looks white. So in essence if a surface absorbed no light it would reflect all the colors, meaning it reflects white light. Now for colored paint. Objects appear a certain color to your eye, this is the color of light it doesn't absorb. You see reflections of unab...	[ "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...
Could you feel a surface that has no friction?	[ "Yes, you would still feel it. For example, if you apply a force perpendicular to the surface of the frictionless object with your finger, then the object would exert an equal and opposite force on your finger. This is the so called normal force, which prevents your finger from penetrating the object." ]	[ "> So, we are all on this rock going fast around the Sun -- does that mean that time is somewhat slowing down for us when compared to someone who is just floating in space? That depends what you mean by \"floating in space.\" There is no absolute reference frame that we can call the \"reference frame of empty space...
Why after a night of extremely heavy drinking do I wake up at a reasonable time contrary to if I was to go to bed without drinking?	[ "I wouldn't call this a definitive answer, but after a night of drinking I always wake up after a few short hours because I'm so dehydrated. After downing a gallon or so of water, I always fall right back asleep." ]	[ "Your eyelids are raised by a muscle that is partially controlled by the part of your nervous system (the \"sympathetic\" nervous system) that is responsible for activating and energising your body (you may have heard of it in relation to the \"fight or flight\" response). When you get very tired that part of your ...
Why do widescreen movies still have a black stripe on the top and bottom even though I own a widescreen tv?	[ "Your TV is probably 16:9 aspect ratio. There are [almost 100 film formats](_URL_0_ ) and only a couple are 16:9. In a movie house, the curtains move to show the right shape piece of screen. Your TV can't do that, black bars are the best it can do." ]	[ "Curse_of_kintave is wrong. Well, he's right about the signal being encoded diagonally on the tape and being read/written with heads in a spinning drum that is tilted, effectively making the heads tracking the diagonal signal on the tape. It's a clever trick to encode way more signal on a relatively slow moving tap...
If you go at the speed of sound could you run on water?	[ "[Identity concealed] is not correct. You can run on water ([just watch this cute little lizard do it!](_URL_0_)), and you can do it at a speed significantly slower than the speed of sound. The exact speed required depends on the surface area and shape of your feet, the frequency and force of your steps, and the su...	[ "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...
What is the purpose of breathing into a bag when stressed?	[ "Having a panic attack will cause you to breathe more rapidly. This will create an imbalance in your body, because you are getting too much oxygen. Breathing in to a bag is a way to decrease the amount of oxygen in the air you breathe and increase the carbon dioxide levels. So the rapid breathing we do to get enou...	[ "One of the easiest ways to to write a short paper on the book. It doesn't need to be a proper academic review, simply a few bullet points and/or paragraphs where you sum up the book, its arguments, and its evidence. I usually write about 1-3 pages this way of bullet points with a couple sentences about each poi...
How does the whole putting your phone in rice thing work?	[ "It doesn't really work with anything more than a few drops. Basically water only evaporates when the air isn't already full of water, and it evaporates the fastest when there's no water vapour in the air. The idea is that in a closed container or bag, all the water vapour will be absorbed by the rice,allowing wate...	[ "Electrical engineer standing by me: in all actuality if you washed something and immediately had it completely dry it wouldn't damage it, but getting it completely dry is extremely difficult and will corrode it if left wet" ]
Why aren't there 128bit or higher computers? Is 64bit enough for everything we need?	[ "As far as memory size goes, 64 bit is far enough, and most architectures only actually support 48 bits of address space. This doesn’t apply to data word size, where, for specialized applications, there are indeed sizes higher than 64 bits in modern CPUs." ]	[ "Say you have a banana and an apple. How many ways can you arrange those on a table? You can put the banana on the table. You can put the apple on the table. You can put both on the table, or you can put none of them on the table. There are four ways total that you can arrange these fruits. This represents 2 to the...
Why do sharks (a predator) have eyes on the side of their head (typical of prey)	[ "fish have their own deal going on. Everything you know about land predators evolved separate from anything going on in the ocean. and sharks dont rely on their vision as much as their smell." ]	[ "The fleshy part of your ear. Sound bounces off of it and your brain uses that to determine whether it's behind or in front of you. Fun experiment; Use Play-Doh to change the shape of your ear. You won't be able to determine if a sound is above, below, in front of, or behind you. [Here](_URL_0_) is a decent video."...
Are boiling bubbles the same kind of bubbles as carbonic bubbles i.e. in water?	[ "No. Boiling bubbles are made of steam, that is, H2O in gaseous form. By contrast it appears you're referring to bubbles made of CO2, or you may be confusing these with carbonic acid." ]	[ "There is many different types of smoke detectors out there. Some can't see the difference between smoke and steam, but the more complex ones does a good job of separating the two. The ones I use at work now is: * optical. (Think LED in one end of chamber and a photo-resistor in the other end. Mesures the amount o...
How far can the human eye see without any "help" (binoculars etcs)	[ "Our naked eye can actually see the Andromeda galaxy from a dark area, which is 2.6 million light years from Earth. That's considered the furthest object you can see with the naked eye I believe." ]	[ "You can actually figure this out with some basic knowledge and assumptions. If you assume that the moon is much closer to Earth than the sun is and travels at approximately constant speed, and know that the longest lunar eclipse is about three hours, and have an idea of the radius of the Earth, you can compare the...
Why haven't any countries intervened with Russia after they have lied and straight up invaded?	[ "It's pretty obvious what is happening over there, but the problem is that it's not possible to impose military action onto Russia to get them to stop, because they are on par with the world powers that would oppose them. This would lead to war. The best that could happen would be that the Security Council rules t...	[ "Greetings everyone. In the few minutes this sub has been up, it's attracting sub-standard responses. Just a reminder of a few of the rules: * no responses covering events/conditions post-1994, per this sub's \"20-year rule\" prohibiting discussion of current events * no anecdotes * no speculation OP: your question...
How do silencers work?	[ "One of the main sources of sound from a firearm being fired is muzzle blast - the propellant gases that actually move the bullet itself shooting out of the end of the barrel after the bullet and displacing air, creating noise. A suppressor consists of a hollow cylinder containing a series of baffles inside that al...	[ "Here is a great video explaining it. _URL_0_" ]
In university, why dentistry is seperate major from medicine?	[ "Medical student here. You're thinking about this backwards. Dentistry can be separate because you don't need to understand the intricate workings of the entire body. You can dedicate all of your time to every aspect of the mouth, because you don't need most of the knowledge gained in medical school. If it was ...	[ "I don't understand your question. Education doesn't tend to cause problems down the road. I can't think of a time when I thought \"dammit, my life would be so much better now had I been less educated.\" EDIT: OK, it seems you're asking about student loans, not education. Well, it's because the benefits outweigh th...
Why is our planet covered in water but other planets & moons in our solar sytem aren't?	[ "Actually, some solar system bodies, like Europa, [more water](_URL_1_) than Earth. There's also plenty of water on Ganymede and Titan... The last of which has actually lakes and even [rivers](_URL_0_) composed of methane sculpting its surface of frozen water." ]	[ "I think the simple answer is that right now we only have one example of life to study. Finding life on any other body will either provide a second opportunity to study life or proof that life on earth may have similar origins to that discovered. Either way it would be a historically and scientifically significant ...
Risk or non-risk of an interest-based currency/bank system.	[ "To any readers out there: If I'm not right, please let me know So there are two parts to this: > ...creating debt that is impossible to pay back, since there's simply not enough money existing to pay it back I think you have your scale wrong. The amount of money being lent is certainly high, but it is *no...	[ "I'm going to summarise, because it's a very big subject... Some economists like Acemoglu and Robinson would argue that conditions in Britain during the Renaissance were somewhat similar to those in Germany and North Italy, leading to the creation of institutions that focus on wealth creation, rather than wealth ...
Why and how was homosexuality legalized in the Ottoman Empire? Were they entering into a new era of progressivism? Also how did the 'ulemas and locals react?	[ "Hey! I started to type up a response to this before I came across /u/PaxOttomanica's excellent response to the question [\"What lead to the Ottoman Empire decriminalizing homosexuality in 1858? Was there a lot of opposition and controversy around this?\"](_URL_0_) I hope you find his answer satisfactory!" ]	[ "You're going to need to narrow down your time frame here, keep in mind you're asking about a time frame of 1000 years over a very, very large area of land with vastly different cultures. You'll be more likely to receive an answer if you narrow the question down to a more specific time." ]
What would we try to learn from the next Milky way supernova?	[ "We have a lot more neutrino detectors in place now, so we can make more detailed measurements of some internal processes." ]	[ "Ok, so can somebody explain exactly how we all die in the event of a GRB direct hit? I mean, is the energy so high that the earth is \"turned to dust\" in it's wake? Does it bathe us with radiation so heavy that we all like \"microwave\" instantly?" ]
What are some examples of interesting dreams from history?	[ "The first thing that comes to mind is the story of Constantine's conversion. The story goes that right before a great battle for control of Rome where he's heavily outnumbered, Constantine has a dream. In it he sees a cross and is told \"With this sign, you will counter.\" He paints the symbol on his troops shield...	[ "Hi everyone. Since this is the kind of question that can attract non-expert responses, just a friendly reminder that all responses must comply with [sub rules](_URL_0_), and that [personal anecdotes](_URL_1_) are explicitly not permitted in /r/AskHistorians." ]
Why is there a sex offender registry but no murderer registry?	[ "Everyone's explanations seem to neglect the fact that murderers typically don't get out of prison." ]	[ "_URL_2_ columnist William Saletan waded into this issue several years ago with similar questions to yours. Here's an article posted AFTER his initial article and several followups, all of which can be reached via links within the article. It's an interesting journey with commentary from psychologists, statistician...
when did it become gramatically acceptable to put the dollar sign after the numeric as in "10$"?	[ "I've never seen that before. Where are you seeing it?" ]	[ "Cause the UK pays service workers a living wage. They build it into the price of the entrees. The US wants the struggle to be real so they pay like $3.52 per hour to service workers and tipping is supposed to makeup for the shit hourly pay." ]
Why do some fruits have pits or seeds with cyanide in them?	[ "To discourage animals able to digest the seed (rather than just pooping it out) from eating the seed. In this way it is more likely to have the offspring survive, and thus reproduce themselves." ]	[ "Evolution. People who didn't get that weird feeling when dangling their limbs from the trees they were sleeping on were killed by cheetahs." ]
What inventions by the Nazi's are still in use today?	[ "Nazi scientists made significant progress in rocketry. Wernher von Braun, who is considered a Father of Rocket Science, was the designer of the Nazi's V-2 rocket. Although the Nazis were less interested in using rockets for space flight and more interested in using rockets as long-range missiles (in replacement of...	[ "[Wikipedia](_URL_0_) has some good comments on it. I remember the notes about Napoleon from elementary school history. > There is a popular story that Napoleon changed the rule of the road in the European countries he conquered from keep-left to keep-right. Some justifications are symbolic, such as that Napoleon...
Who is allowed to legally immigrate to the United States?	[ "Anyone, everyone... if you follow the proper process. This process (of course) can take years, and even a decade to reach full residency/citizenship." ]	[ "[From the bottom of that article:](_URL_0_) Why are there differences in processing times among regions and offices? Visa offices face different challenges operating in different countries and regions, and even in different offices within the same region. Various factors can affect the time it takes to process...
If there is an absolute cold, is there an absolute hot?	[ "There is an [absolute hot](_URL_0_), but it's not a limit like absolute zero is: it's another name for the Planck temperature, the point at which the energy of your particles is so high that you need a theory of quantum gravity to be able to describe their interaction. There are other definitions as well, but I ha...	[ "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_)." ]
Is it possible that minerals/compounds that are scarce/nonexistent on earth, are abundant in other parts of space?	[ "Sure. You see Jupiter? It contains about 20% helium by mass, while on Earth helium is incredibly scarce." ]	[ "So you're getting two different sets of answers based on two different readings of your questions. First, conservation of mass is a thing. Re-arranging molecules won't let you get a higher mass. Even fixing gasses probably won't get you there, because you are expending energy in the process of re-arrangement. Seco...
why does the UK have to pay the EU 2bn euros?	[ "The EU receives regular financial contributions from all of its member states. Rather than setting a flat tax rate, the EU chooses an amount for each country to pay on a case-by-case basis. The EU just re-evaluated those amounts for all its members. Those who had economic contraction now owe less, while those with...	[ "[This thread](_URL_0_) in /r/unitedkingdom makes an attempt at it, with fewer conspiracy theories than in the bigger subs. TL;DR - it's a negotiation. No one involved in a negotiation would ever want the details of the things they're giving way on made public, but in order for any negotiation to work, both sides h...
Why do tongues stick to frozen poles, while wet fingers do not?	[ "My fingers have gotten stuck to frozen poles. That was in Michigan when the temperature was -30 with windchill." ]	[ "[This](_URL_0_) previous thread explains it as [entrainment](_URL_2_). When changing the diameter of your lips, the airflow is subject to the [Bernoulli effect](_URL_1_) where it speeds up. When the air moves faster, it draws in more surrounding air which is cooler than your body temperature, thus making it feel c...
What would happen if we put our waste in volcanoes and let the lava do the work?	[ "You are on the right track, lava is quite dense so most of the trash would 'float' on top of it, just burning from the high temperature. Really it would be the same as an open fire." ]	[ "Firstly - There are several countries that have changed enviromental policies, especially in Europe. However, the main reason some countries aren't doing more is that those kind of policies won't win your next election. Higher taxes on fossil fuels and meat for example is a good method to reduce CO2 emmisions, but...
Do you get more wet running or walking in the rain?Assuming the distance is the same	[ "Saw this video awhile back. I highly recommend watching it. It's a little long but he really gets into it. I won't spoil it but no one has yet posted the true correct answer. _URL_0_" ]	[ "very simple, Air is a horrible transfer medium for energy, Water is a good tranfter medium for energy. It takes longer for the energy in the air to flow to the ice cube then the energy in the water to flow in the ice cube, When when there is steam in the air, its still maybe 50% humidity compared to 100% humidity...
What happens with plane after emergency landing on water?	[ "It sinks and depends on where it went down divers or recovery crews are sent to recover the black boxes to see why the plane failed. If a plane sinks the cost of repairing the water and impact damage usualy makes the idea of refusbishing the plane and putting it back in to service quite unrealistic." ]	[ "Need more detail! Was the pilots voice being played through the speakers? If so, are your headphones wireless? Or did the headphones not cancel out the noise like you thought they should? Edit-- * If playing through the speakers, your headphones are wireless and the signal sounded fine: digital comm problem (im...
Who was the first state(s) to recognize Irish independence as of their revolt in the early 20th century? Why?	[ "The revolutionary Irish Republic from 1919 to 1922, before the Anglo-Irish Treaty and the formation of the Irish Free State came closest to recognition by the Soviet Union, mostly due to pro-labour, socialist and soviet sympathies within the Irish Republic. However, no formal recognition took place as the Soviet U...	[ "Unfortunately, this isn't a subject area which I can talk specifically about, hence I felt making a comment would be uncouth, however, all the same, for the sake of other responders, I though it'd be useful to say that I think you'll have to be more specific here (for the sake of getting the response you want) . F...
How is the Citizen's United constitutional amendment an "attack on the First Amendment"?	[ "Campaign finance is all about speech. Suppose for example you support the politics of someone, and you want to give him the ability to spread his message to others. So you want to give him some money to take a train to the next town; that is you exercising your right to express ideas. It is also \"campaign finance...	[ "[Here's](_URL_0_) a report from WBUR's Radio Boston on why some towns in New Hampshire receive higher Federal scrutiny of their elections procedures under section 5 of the Voting Rights Act of 1965. tl;dl In 1970 New Hampshire had a literacy test and unusually low voter turnout triggered the oversight." ]
Did Horses actually help miners strike gold?	[ "I have studied the history of mining for a long time, and I have never run into this assertion. There are stories that link a prospector's discovery of gold or silver to the wandering of a burrow, and the prospector having to chase the creature, which leads to the accidental discovery of an ore body. But I never h...	[ "This question is getting a lot of traffic after being [tweeted by @reddit](_URL_5_), so I thought I'd welcome those of you that haven't visited /r/AskHistorians before to the subreddit. Please do bear in mind that in order to keep the quality of answers here high we have [strict rules on comments](/r/AskHistorians...
What at the basic subatomic level makes it possible for some matter to displace other matter? Basically, why is the steel knife more likely to cut the cheese than the other way around?	[ "This isn't a subatomic process, it's an atomic and molecular property. Think of it like a boat plowing through waves. The knife-boat had atoms that are very strongly bonded to one another while the cheese-water is more held together by hydrogen bonding which is very weak by comparison" ]	[ "Angles my friend. Try taking a knife and sliding it across a piece of fruit like a razor, then try the same thing smashing it perpendicular. One won't do a damn thing, the other slices the fruit wide open." ]
What's the difference between the "Top" and "Best" in reddits sorting options?	[ "\"Top\" is the comments with the most points. This doesn't always work so well because old comments will hover near the top and stay there, as that's what most people will see first. \"Best\" works on the ratio of up/downvotes to predict where the comment will end up, allowing a relatively new comment to reach the...	[ "There is actually an explanation for this. All your brain gets is signals without mich further information. So it must decide what problem to fix first. Now there is an alarm for hunger and pain at once. Worst case for hunger is starving. That takes about three weeks. Worst case for pain is fatal injury. That can ...
why do my torrent downloads always slow down at the end?	[ "Kind of like if you're looking through some legos for a number of different parts, you usually come across one that you need so your search goes quickly until there's one last part you need. It might take you awhile to find that last specific part. That explanation is probably wrong but that's what I would say to...	[ "Here's a [picture](_URL_0_) that might help explain. That figure is the \"analemma\". You can create such a thing by taking a picture of the same location in the sky (assuming the Sun is there) at the same time of day throughout the year. What you'll notice is that the Sun doesn't just trace a line back and forth,...
If the Moon is slowly moving away from us, what will happen to the Earth when this actually happens?	[ "The Moon will never leave orbit. Its track widens at a rate of only a few centimeters per year, and given current rates of change, the Earth will become tidally locked with the Moon (keeping the same face constantly toward each other) long before it can to leave orbit. At that point its orbit will stop expanding, ...	[ "There's a chemical called melanin within skin cells that protects the skin from harmful sun rays. As these rays increase melanin moves to the surface to protect you more. As these rays decrease, the melanin is no longer needed, and so it moves back and so you 'lose' your tan. (I know this is a simple explanation b...
Can a non-native English speaker become an elementary school teacher in the USA?	[ "Provided they can speak understandable English and are able to pass certification then sure. There are no rules about being native to teach." ]	[ "Most have a [relay phone](_URL_0_) in their homes - they use an interpreter. [TTY](_URL_1_) is also available on mobile phones, landlines, and in 911 centers." ]
Human consumption of other animal's milk.	[ "Milk is pasteurized (heated quickly to kill germs) before being sent out to market. This has nothing to do with lactose intolerance. Lactose is a type of sugar naturally present in milk, and it's that sugar that gives some people stomach problems when they drink it. For most of history, all mammals became lactose...	[ "- Cannibalism was noted in some South Pacific, north/south American and Caribean cultures. - There were child soldiers used in various roles in [Colombia](_URL_2_), and in [Chechnya](_URL_2_), among many other non-african nations. - I would be surprised if there was any culture on earth where cross-dressing or str...
When exercising, is fat near the part of the body being exercised being used more?	[ "Nope. Muscles near the area are worked out, obviously, but fat is a whole-body issue. Like a fuel tank- it runs down in all areas." ]	[ "I'm sorry that I'm no expert, but I remember reading about this the last time a similar question was asked: _URL_0_ Basically, you percieve time faster after your run because of endorphines released during the work out, which means that the music seems slower. This is apparently also why a lot of rock musicians pl...
How does windchill work?	[ "temperature and heat transfer are not the same thing. convection is a phenomena where air flow increases heat transfer. if it feels like 40 when its 50, all that means is that roughly the same amount of heat transfer from a person to the outside is happening if it was 40 and no wind. also because a themometer meas...	[ "Celsius was derived fairly simply. Basically the freezing point and boiling point of water were set and the difference between them divided in 100 segments. This is sometimes referred to as centigrade. Centi being 100. Farenheit was derived from taking the freezing point of pure water and salt water and divided by...
Why do we have baby teeth then adult teeth?	[ "Our teeth do not continuously grow in size as we age and if we only got one set of teeth we would either have to spend the first decade or more of our lives without teeth, or we would have to spend all our lives with tiny inefficient teeth. Both would have meant our species died out long ago." ]	[ "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" ]
What is happening biologically when you get a brain freeze?	[ "When you put cold food to the roof of your mouth, it contracts the capillaries in your sinuses which causes pain sensing nerves to trigger, making your head hurt." ]	[ "[This](_URL_0_) previous thread explains it as [entrainment](_URL_2_). When changing the diameter of your lips, the airflow is subject to the [Bernoulli effect](_URL_1_) where it speeds up. When the air moves faster, it draws in more surrounding air which is cooler than your body temperature, thus making it feel c...

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