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What type of weapons would have been available to medieval peasants?	Many of them would have access to spears, which would probably constitute the bulk of their weaponry. Also, depending on the time and place, many would also be equipped as archers. Many small villages had competitions for archery on a regular basis, especially in England. The spears, in particular, are easy and super-c...	[ "As far back as medieval times, if not Biblical times, there was pressure from landowners to demand heaped bushels of commodities from their peasants, while at the same time peasants were obliged to purchase commodities from stricken containers. Rules outlawing this practice were circumvented through use of heavy r...
At what point did European settlers outnumber Native Americans in what would become the modern United States?	This is a huge, and interesting, question. I'm afraid our current data can only go so far in providing an answer. What follows is an analysis of the data, and the pitfalls of trying to definitively answer this question due to everything from notions of identity, evolving racial categories, and lack of solid sources. I ...	[ "Henry F. Dobyns estimates that immediately before European colonization of the Americas there were between 90 and 112 million people in the Americas; a larger population than Europe at the same time. \n", "With the advancement of European colonization in the territories of the contemporary United States, the Nat...
why does the body consume carbohydrates first and then fats when exercising?	The actual answer is a bit more complicated than that. What cells actually use for fuel is ATP, which is an energetic protein that we make using carbohydrates, fats, and other things as a fuel source. ATP is mostly produced by mitochondria, organelles inside cells, and muscle cells have a lot of mitochondria. At any ...	[ "Carbohydrates are the main source of energy in organisms for metabolism. They are an important source of fuel in exercise. A study conducted by the Institute of Food, Nutrition, and Human Health at Massey University investigated the effect of consuming a carbohydrate and electrolyte solution on muscle glycogen use...
What is actually happening when I hear my timber framed house 'crack'?	It would be better described as creaking rather than cracking. When a door creaks, the hinges aren't cracking, there's just resistance that builds up until friction can no longer stop the hinge from moving. The same applies to the beams in your house as some parts of the wood heat & expand faster than others.	[ "An investigation of the scene afterwards found that seventeen joints had given way causing a hole approximately long to open up in the stand. Several witnesses in the crowd reported hearing loud cracking noises prior to the collapse and one witness, who worked as a joiner, claimed to have seen the wooden boards sp...
why can't a country in a trade surplus be sustained in that position indefinitely?	It can. Imagine you have a job at a convenience store where they give you a 50% discount on baseball cards. You don’t care for them much, but your friend does. He regularly buys them from you for 90% of list. You never buy anything from him. Your friend has a trade deficit with you. The trade, though, is beneficial ...	[ "If a country's resources were not fully utilized, production and consumption could be increased at the national level without participating in international trade. The whole raison d'être of international trade would disappear, as would the possible gains. In this case, a State could even earn more by refraining f...
This Week's Theme: Immigrants and Emigrants	Current: Immigrants and Emigrants On Deck: Trauma In the Hole: The Balkans Remember to ask theme-related questions in [a new thread!](_URL_1_)! If your submission doesn't get automatically flaired, [send us a modmail](_URL_0_) with a link!	[ "\"The Emigrants\", the works about the Swedish emigration to North America, written by Vilhelm Moberg that have spread around the world have put a focus on many places in the municipality mentioned in the novels. Moberg himself was born on a farm just north-west of the town Emmaboda in 1898, where a monument stone...
- why is citizen kane considered to be the pinnacle of movie making?	It's less about being the pinnacle of movie-making and more about being the _start_ of modern movie-making. In _Citizen Kane_, director Orson Welles revolutionized how films were shot. There are a number of cinematic techniques that were introduced in _Citizen Kane_ including low angle shots, multiple dissolves, deep...	[ "In the decades since, its critical status as the greatest film ever made has grown, with numerous essays and books on it including Peter Cowie's \"The Cinema of Orson Welles\", Ronald Gottesman's \"Focus on Citizen Kane\", a collection of significant reviews and background pieces, and most notably Kael's essay, \"...
what is the difference between federal debt and u.s. treasury securities?	The debt is issued through the use of US Treasury securities. The government sells a bond, and the money collected from the bond buyer increases the debt until the bond is paid back.	[ "Treasury securities are backed by the full faith and credit of the United States, meaning that the government has promised to raise money from any available source to repay them. Although the United States is a sovereign power and may default on its debt, its strong record of repayment has given Treasury securitie...
why does semen lose its white color after 5 min?	Ok, so: semen contains very little actual spermatozoa and a lot of other components, one of which are alkaloids produced by prostate to - basically - neutralize the acidity in a vagina, so that the spermatozoa survive long enough to reach the egg. The alkaline stuff oxidises when it contacts the oxygen in air, which m...	[ "Semen that has a deep yellow color or is greenish in appearance may be due to medication. Brown semen is mainly a result of infection and inflammation of the prostate gland, urethra, epididymis and seminal vesicles. Other causes of unusual semen color include sexually transmitted infections such as gonorrhea and c...
sinuses	Sinuses are hollow cavities in the skull to lighten the bone structure. They are lined with mucous tissue, and can be subjected to allergens, causing the mucous to swell and produce mucus. This can plug up the sinus cavities and cause pressure and pain. Why your throat swells up and goes numb really has nothing to d...	[ "In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the \"true\" internal carotid ar...
if you start off completely awake and energized but then start dozing off during a boring class or a study session, what exactly is happening physiologically to cause this ?	Your brain notices that there's nothing of interest going on at the moment, and tries to shut down to conserve energy. Your studying might be important to you in a higher-function way, but at a core animal level, it's not food, sex, stimulation, or entertainment, and so you're just wasting energy and calories (and ther...	[ "Automatic behavior can also be exhibited whilst in the REM state—subjects can hold conversations, sit up and even open their eyes. Those acts are considered sub-conscious as most of the time the events cannot be recalled by the subject. It is most common when the subject has had under 10 hours sleep within a 36-ho...
if supermarkets have a defined science/art as to where products are located, why are they all different?	Numerous factors- 1 Store size. Different stores are different sizes, and shapes depending on the area they are situated and the availble space/ planned market.. What works for one floor plan doesn't neccesarily work for another. 2 customers. Customers in different areas like different things, so different branches ...	[ "Supermarkets are designed to \"give each product section a sense of individual difference and this is evident in the design of what is called the anchor departments; fresh produce, dairy, delicatessen, meat and the bakery\". Each section has different floor coverings, style, lighting and sometimes even individual ...
why do people with loads of money still attempt to earn more money? if you have millions in the bank isn't that more than enough?	Generally I would say that people who are millionaires tend to have a high performance drive. They desire to always perform better. This is what made them wealthy in the first place, and this is what makes them desire ever more wealth. You can always do better. Furthermore, once you reach the level of being a milliona...	[ "Author Ric Edelman writes: \"You don't make any money in bank accounts (in real economic terms), simply because you're not supposed to.\" On the other hand, he says, bank accounts and CDs are fine for holding cash for a short amount of time.\n", "It is not uncommon to come across individuals from whose company a...
What is the longest "unbroken" chain of royal or dynastic succession in known history?	Japan has the oldest continuous, hereditary monarchy in the world -- and would, I believe, even qualify as oldest if we included non-hereditary or interrupted-hereditary successions. The Japanese royal family is still in the Yamato Dynasty, which took over the Japanese throne (according to legend) in about 660 BC under...	[ "This list of current longest ruling non-royal national leaders is a list of the current living longest ruling heads of nation-states or national governments, who are not royalty, and have served ten years or longer, sorted by length of tenure.\n", "Sobhuza's official incumbency of 82 years and 254 days is the lo...
Why is it that humans can be sustained on some leafy plants (spinach, lettuce, kale, etc) but not others (ferns, tree & and flower leaves, etc)?	It depends on what that source has to offer. Most leafy plants commonly eaten are considered "greens" like Kale, Spinach, Arugula, etc., and are eaten for the vitamin and mineral content. "Greens" are an essentially non-caloric or low calorie, nutrient dense source of minerals that would be difficult to consume through...	[ "The plants are relatively easy to grow and care for, having few insects that feed on them. Mites, though, are known to feed on the plants. The plants are also susceptible to leaf spotting, root rot and root strangulation. However the former two can be prevented by avoiding a damp soil and the latter by frequent we...
how to barcode scanners instantly detect what an item is, despite the barcode being at any angle and often on a crinkled surface, completeley changing the look of the code from the scanner's perspective?	The lasers that read the barcode hit it from many angles and scan it very quickly. Also barcodes have something like a checksum, where it's easy to recognize if the data that was read is garbage and needs to be read again. That's why when using hand scanners, like at the grocery store, sometimes it scans a valid item v...	[ "This application supports many different types of barcodes, including those used to identify products in commerce. The Barcode Scanner can automatically search the Web to identify a product with a barcode and use, for example, price-comparison information between vendors.\n", "By using the barcode center marker,...
Is there a historical reason why the US military says klick instead of kilometre?	It's not official, it is military slang, and is used purely because it is easier to say.	[ "BULLET::::- That when American servicemen heard the term during the Korean War, they heard the word as 'gook\" instead of k(g)uk which means \"national\" (maybe, thus, interpreted as nationalist) \"goo-goo\" (also \"gugu\"), a term used by the U.S. military to describe Filipinos.\n", "The slang term \"SWAG\" is ...
why do most websites have character limits for passwords while at the same time they force you to have an upper/lowercase letter, and a number to make your password more secure. wouldn't removing the character limit and allowing much longer passwords make them more secure than 16 characters?	Convention. There is no technical strength to doing so. Users who will use insecure passwords without the restrictions will use insecure passwords with the restrictions, and cracking these cases isn't all that much more demanding. Meanwhile, increasing password length does substantially increase security. It would be...	[ "Many policies require a minimum password length. Eight characters is typical but may not be appropriate. Longer passwords are generally more secure, but some systems impose a maximum length for compatibility with legacy systems.\n", "The full strength associated with using the entire ASCII character set (numeral...
Whats the difference between Centrifugal and Centripetal force?	Its often taught in PHY 101 courses that the centripetal force is "real" while the centrifugal force isn't. In a purely inertial sense, this is true, however it oversimplifies how we often times approach a lot of real problems in physics. A lot of the confusion comes from the fact that they both describe the same phe...	[ "In Newtonian mechanics, the centrifugal force is an inertial force (also called a \"fictitious\" or \"pseudo\" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis passing through the coordinate system's origin and parallel to the axis of rotation...
what's actually happening when someone overeats on a regular basis and their stomach "expands"? what about in reverse when their stomach gets "smaller"?	It's not just a figure of speech. Your stomach can physically expand/stretch. [Competitive eaters expand their stomachs for competition using water](_URL_0_). It really is like a balloon in a way. The size of the actual organ doesn't change, but it's elasticity and response to food can. The opposite is not true ho...	[ "Gastroparesis (gastro- from Ancient Greek γαστήρ - gaster, \"stomach\"; and -paresis, πάρεσις - \"partial paralysis\"), also called delayed gastric emptying, is a medical disorder consisting of weak muscular contractions (peristalsis) of the stomach, resulting in food and liquid remaining in the stomach for a prol...
rental car insurance.	I called my insurance company to make sure that my policy is the same whether I'm driving my car or a rental. It does except for what they call "loss of use." The way I understand it, if you crash the rental, insurance will cover damages to it, but the rental company can claim losses because it would have been making ...	[ "Most rental car companies offer insurance to cover damage to the rental vehicle. These policies may be unnecessary for many customers as credit card companies, such as Visa and MasterCard, now provide supplemental collision damage coverage to rental cars if the rental transaction is processed using one of their ca...
If Alpha Centauri had a solar system like ours, how big would the outer planet's orbit appear in the sky if visible with the naked eye?	If the planetary system was completely face on and if we assume that it's an Earth like planet orbiting at 1 AU, then it would appear approximately 4x10^-4 degrees wide. That's about 0.012 arc minutes, and a quick wiki check says that the best a human eye could do is around 1 arc minute. So no way you'll see it. Not...	[ "Viewed from near the Alpha Centauri system, the sky would appear much as it does for an observer on Earth, except that Centaurus would be missing its brightest star. The Sun would be a yellow star of an apparent magnitude of +0.5 in eastern Cassiopeia, at the antipodal point of Alpha Centauri's current right ascen...
Can you name some important historical travelogues?	Forgive me, I am not certain what you mean by 'undercover regions'. Lady Mary Wortley Montagu's travel writings on Turkey and other countries are used as primary sources. Her relish in appealing to her audiences means her writing isn't always reliable as verbatim records of events, but is insightful for us for a rang...	[ "BULLET::::- Travel Writing: The text of most of the best known historical British travel writers, including James Boswell, William Camden, William Cobbett, Daniel Defoe, Celia Fiennes, Charles Wesley and Arthur Young. The earliest source included in the GB Historical GIS is a survey of Wales written by Giraldus Ca...
During WW2, were there any significant acts of sabotage executed by the Axis powers on U.S. soil?	The case of Ex Parte Quirin is of note here, if only to show how inept German sabotage was for the time. A handful of covert German operatives deposited by submarine on the American eastern coast landed in uniform, to comply with the laws of war, buried their uniform, to get around the laws of war, and then started to ...	[ "During World War II PRR carried troops and matériel for the Allied war effort, and the Curve was under armed guard. The military intelligence arm of Nazi Germany, the \"Abwehr\", plotted to sabotage important industrial assets in the United States in a project code-named Operation Pastorius. In June 1942 four men ...
[mod post] coming soon...on rules and mods.	Can we make sure the rules do more to encourage searching for answers first? Especially around big news events, the old classics of '3d printing' and 'schrodingers cat' come up constantly too. A giant red bar that flashes up when you mouse over submit like on askscience or TIL might help.	[ "The purpose of Mod DB is to list the mods, files, tutorials and information of any games that are capable of being modded with user-made content. Community involvement is strongly encouraged, and any game mod with a website is allowed to post a screenshot gallery, news, and requests for help. Scott's intentions, f...
When did Americans start using French words and phrases, and why are they so prevalent?	Although English is a Germanic language, approximately 30% of English vocabulary comes from French in one form or another. This is largely caused by an event called the Norman Conquest, in which a group of people called Normans, who inhabited Northern France and had a degree of Scandinavian ancestry, invaded and conque...	[ "As American soldiers and officials traveled through the area for the first time following the War of 1812, they initially used the French spelling. But when large numbers of lead miners streamed into the country south of the river in the 1820s, the U.S. government began to refer to it differently in debates and le...
Could we use magnetism as opposed to rocketry to launch objects/people/spaceships into orbit?	People talk about doing something like this: The mass driver, which is similar to some designs for high-speed trains. _URL_0_ In most cases it's not practical to launch from Earth's surface to orbit with one of these, since you have to launch at high speed through the atmosphere, and your capsule would ...	[ "The science of electromagnetic propulsion does not have origins with any one individual and has application in many different fields. The thought of using magnets for propulsion continues to this day and has been dreamed of since at least 1897 when John Munro published his fictional story \"A Trip to Venus\". Curr...
why are there so many contradictory ideas about what humans should be eating, but other animals are very straightforward in knowing what to eat?	We have the technology to make whatever we want and the resources to get whatever we want. We have a lot more choices than an animal does. It also helps that we're omnivores and able to make any type of food digestible and tasty, while many other animals are stuck being unable to digest one thing or the other. Animals...	[ "Ultimately, \"Eating Animals\" discusses the ethics of food. It suggests that our food choices directly reflect the ethical values we stand for. When people eat meat, Foer claims, they are implying that satisfying their desire for meat is more important than letting animals live well, or even live at all. This can...
In the 1920s, what did people feel nostalgia towards?	This is not to prevent anyone from writing you a full, new answer, but you may be interested in these two answers of mine: [Why are people today fascinated with the Victorian era?](_URL_0_) [Dang kids! Or: Why does each generation have such an exaggerated view of fashion in previous ones?](_URL_1_)	[ "In the eighteenth century, scientists were looking for a locus of nostalgia, a nostalgic bone. By the 1850s nostalgia was losing its status as a particular disease and coming to be seen rather as a symptom or stage of a pathological process. It was considered as a form of melancholia and a predisposing condition a...
The USA had a large percentage of German immigrants in the early 20th century. What was life like for them during WWI and WWII? Did many serve the Allies or did any go back to the “Fatherland”? Also why did the US sell to the British and not the Germans before they entered both wars?	One of the first things you need to think about is why the Germans came over to the US. The vast majority of immigrants came after the failed Democratic revolutions in the 1890s, so they wanted to live in Republican state. That being said while these Germans hated the Kaiser they didn't want war between the US and Germ...	[ "Before 1900, the main factors in German-American relations were very large movements of immigrants from Germany to American states (especially Pennsylvania, the Midwestern United States, and central Texas) throughout the 18th and 19th centuries.\n", "But immigrants from Germany, as well as German Americans from ...
Does brushing your tongue harm your taste buds?	Dentist here. To answer your question about tongue brushing and potential damage to our taste receptors. Yes and No. Let's start with how it would be a Yes, and work in to the final answer of No: If you are using a hard bristled toothbrush, highly corrosive toothpaste (usually whitening toothpaste or something with ...	[ "Tongue cleaning can cause discomfort. Improper use of a tongue cleaner may induce the gag reflex and/or vomiting. Overuse of a tongue cleaner may also cause damage to the taste buds. Some people have inappropriately used the tongue cleaner to scrape or brush the lingual tonsils (tongue tonsils).\n", "The tongue ...
if redbull lost a lawsuit over their "gives you wings" slogan, how do the current commercials still include the slogan without a small disclaimer included?	Actually, that law suit (for $13.5 million) was not because of the tagline "give you wings" (which is clearly understood as humor). The law suit was over the fact that Red Bull oversold the drink's ability to improve concentration and energy, specifically, it did not provide any scientific evidence to support their cl...	[ "In 1999, animated advertisements were part of the early GEICO Direct ads as well as the \"Dumb Things\" campaign. The 15-second long commercials, animated by Bill Plympton, featured a curious little man walking up to an object and eventually getting hurt due to his curiosity about the object. One of the commercial...
What gods were foreign and then adopted by the Greeks and Romans through trade/war/etc?	A few of the most famous examples of Roman religious syncretism are the cults of Isis, Mithras, and Sulis. Isis was an Egyptian goddess of magic and mother of Horus, God of the Pharaoh. She was an incredibly important figure in the Egyptian pantheon so it's no small wonder that her cult thrived under the rule of the P...	[ "In the subsequent Greco-Roman period, there is evidence that the worship of non-indigenous deities was brought to the region by merchants and visitors. These included Bel, a god popular in the Syrian city of Palmyra, the Mesopotamian deities Nabu and Shamash, the Greek deities Poseidon and Artemis and the west Ara...
If the salt water in the ocean accumulated over time was there ever a point where it was all freshwater?	Perhaps briefly (on a geological timescale), when the atmosphere cooled enough for the first rains to fall, the resultant bodies of water may have been pure enough to be considered freshwater with less than 500ppm of dissolved salts. There were almost surely multiple phases of the early Earth's surface water inventory...	[ "Scientific theories behind the origins of sea salt started with Sir Edmond Halley in 1715, who proposed that salt and other minerals were carried into the sea by rivers after rainfall washed it out of the ground. Upon reaching the ocean, these salts concentrated as more salt arrived over time (see Hydrologic cycle...
why does adding salt to desserts make them seemingly sweeter?	Salt changes the electrochemical reactions that happen in the chemoreceptors on your tongue (taste buds). The effect is different for different types of receptors; bitter receptors are inhibited, while sweet receptors have their sensitivity enhanced. Sweet becomes sweeter and bitter becomes less bitter (but only up to ...	[ "Desserts can contain many spices and extracts to add a variety of flavors. Salt and acids are added to desserts to balance sweet flavors and create a contrast in flavors. Some desserts are coffee-flavored, for example an iced coffee soufflé or coffee biscuits. Alcohol can also be used as an ingredient, to make alc...
why did a law need to be passed telling federal employees that they couldn't participate in insider trading?	This is how I understand it. Can someone please fill in the details or correct me on this? Part of the reason is because, technically, a lot of what they were doing wasn't "insider" trading. Typically, insider trading happens (e.g.) when you work for a company or are someway involved in a company and you happen to k...	[ "U.S. insider trading prohibitions are based on English and American common law prohibitions against fraud. In 1909, well before the Securities Exchange Act was passed, the United States Supreme Court ruled that a corporate director who bought that company's stock when he knew the stock's price was about to increas...
the future of computer storage: storage capacity vs compression abilities	So far, capacity has kept increasing rapidly. You used to buy the biggest drive you could afford, knowing that it was going to be filled up all too soon anyway, but that you'd be able to get a bigger one in a few years. These days, the capacity of a hard drive tends to be much larger than anyone needs, especially with...	[ "It is estimated that the total amount of data that is stored on the world's storage devices could be further compressed with existing compression algorithms by a remaining average factor of 4.5:1. It is estimated that the combined technological capacity of the world to store information provides 1,300 exabytes of ...
Can a satellite maintain an orbit forever under ideal conditions?	Purely from Newtonian gravity - i.e., the gravity you learn about in high school - there's no decay under ideal conditions. But we've known that picture of gravity is wrong for nearly a century. The more modern theory, Einstein's theory of general relativity, allows for gravitational radiation, and any orbit will radia...	[ "Each satellite has a design life of twelve years, with an orbital maneuver life of 15 years, which means that each satellite has been designed and fueled to maintain its assigned orbital position (within 0.1 degrees) for 15 years. After that point, the satellite must be decommissioned. The AfriStar satellite has d...
Do satellites travel with the rotation of the earth or against and if they go both ways would two identical satellites going opposite directions at the same altitude have to travel at different speeds to maintain orbit?	Most satellites are in prograde orbits, meaning that they orbit in the same direction that the earth rotates. This is because retrograde orbits, which orbit opposite the direction of the earth's rotation, require more fuel to launch. Think of it like this. If you're in a car going 5 mph and you want to get a projectil...	[ "Because a satellite in an eccentric orbit moves faster near perigee and slower near apogee, it is possible for a satellite to track eastward during part of its orbit and westward during another part. This phenomenon allows for ground tracks which cross over themselves, as in the geosynchronous and Molniya orbits d...
Scientists: What is the coolest thing you've learned in your field?	I can make a big list actually, of moments I just had to stop and take a moment to digest that. Some of them: 1. The first time I saw the first division of a C. elegans embryo under a microscope. Its quite big so you can see all the aspects of cell division happening with your own eyes and its the most magical thing I...	[ "Described by Discovery as a \"commercial free hour of \"MythBusters\" mashups, hosted by Kari Byron\", the show features about ten minutes of new material—experiments and quizzes presented by Kari, as well as TV celebrity and scientist appearances, pitching the idea that \"science is cool\"—interwoven in fifty min...
why is vibrato singing considered good?	Long notes can sound boring. Vibrato is intended to add some colour and variety during the course of the note. Vibrato is a skill... but an equally important skill is knowing when and how to use it. It probably shouldn't be used in every note, or for the whole length of the note. The speed and the intensity of the vib...	[ "Vibrato is often perceived to create a more emotional sound, and it is employed heavily in music of the Romantic era. The acoustic effect of vibrato has largely to do with adding interest and warmth to the sound, in the form of a shimmer created by the variations in projection of strongest sound. A well-made violi...
Was every desert once a body of water?	It's hard to say definitively whether or not every desert was once under a body of water, but desertification of once arable land is possible with poor land management, such as what happened with Africa after the Romans cut down all the trees. Sand is kind of always there, it's the vegetation and bio-mass that gets car...	[ "Scientists agree that the existence of a desert in the place where the Sahara desert is now located is due to a natural climate cycle; this cycle often causes a lack of water in the area from time to time. There is a suggestion that the last time that the Sahara was converted from savanna to desert it was partiall...
What happens to gut flora if a person is dying of starvation or dehydration?	Depending on where in the gut you're looking at, it may change. During starvation, your stomach acid may become more concentrated, and stronger - thus a small amount of bacteria in the proximal duodenum (small bowel coming right off the stomach) may be killed. This would be very minimal, since there are glands in the p...	[ "The underlying starvation, malnourishment, and usually dehydration, associated with emaciation, affect and are harmful to organ systems throughout the body. The emaciated individual experiences disturbances of the blood, circulatory, and urinary systems; these include hyponatremia and/or hypokalemia (low sodium an...
how were length/liquid measurements kept the same everywhere?	The short answer was, they didn't. Standards varied heavily from region to region. Keep in mind, back then, travel/trade was a lot harder, so the effects were much less noticeable. In some cases, once things were more developed, they would have a standard- then they'd copy that standard and ship them around the worl...	[ "Before the 1843 changeover, different units were used to measure length. One pic (dzera à torky) was equal either to 0.64 m or 0.623 m), while a different pic (dzera à rabry) was equal to 0.48 m or 0.467 m). Some other units are given below:\n", "The history of the measurement of length dates back to the early c...
Why can't you tame a Zebra?	"Taming" isn't all-or-nothing. There's a range of behaviors that includes whether the animal attacks humans, runs away from humans, tolerates being touched, tolerates various medical examinations and procedures, responds to commands, actively seeks human company, and so on. The zebras at the San Francisco Zoo will do ...	[ "Zebras have four gaits: walk, trot, canter and gallop. They are generally slower than horses, but their great stamina helps them outrun predators. When chased, a zebra will zig-zag from side to side, making it more difficult for the predator to attack. When cornered, the zebra will rear up and kick or bite its att...
Is the earths ozone layer capable of changing position?	Well, the ozone layer is ubiquitous through the stratosphere. In fact, the predominant sources of ozone are in the tropics, and it's overturning circulations like the Brewer-Dobson that transport ozone to the poles through the year - at least until the polar vortex develops, which cuts off that transport. You don't re...	[ "The ozone hole is usually measured by reduction in the total \"column ozone\" above a point on the Earth's surface. This is normally expressed in Dobson units; abbreviated as \"DU\". The most prominent decrease in ozone has been in the lower stratosphere. Marked decreases in column ozone in the Antarctic spring an...
how does paypal make money/stay in business?	If you are a merchant selling something through them they take a 2.9% + $0.30 cut of your profit.	[ "PayPal's services allow people to make financial transactions online by granting the ability to transfer funds electronically between individuals and businesses. Through PayPal, users can send or receive payments for online auctions on websites like eBay, purchase or sell goods and services, or donate money or rec...
Three questions about the Napoleonic army.	During a campaign, an officer was generally allowed a small Wagon to carry personal effects and anything necessary for his work in the field. This would range from a tent and necessary notes to liquor and personal reading. Naturally the higher the rank the more you'd be able to have bit the more you'll also need for yo...	[ "Napoleon led a new army to the Battle of the Nations at Leipzig in 1813, in the defence of France in 1814 and in the Waterloo Campaign in 1815, but the Napoleonic French army would never regain the heights of the Grande Armée of June 1812.\n", "Under Napoleon I, the French Army conquered most of Europe during th...
What people does the Assyrians descend from?	This is a somewhat controversial topic within the Syriac christian community. Basically there are two main schools of thought: those who identify as Assyrians and descendants from the ancient Assyrians and those who identify as Arameans and their descendants. I will let someone with the 'Assyrian' origin point of view ...	[ "In Church tradition, the Assyrians are descended from Abraham's grandson (Dedan son of Jokshan), progenitor of the ancient Assyrians. Along with the Arameans, Phoenicians, Armenians, Greeks and Nabateans, they were among the first people to convert to Christianity and spread Eastern Christianity to the Far East.\n...
you know how you can tense up certain muscles in your foot or leg and pretty immediately give yourself a cramp? why do your muscles have those 'pressure points' or non-random cramp areas, and why is it so easy to bring about a cramp in them?	I tried to read up on this, and also asked my doctor about it, and it seems to not be totally known, in part because there can be a lot of different reasons depending on the person and circumstances. I think these are usually technically muscle spasms rather than cramps, although they're similar. Some possible causes...	[ "A cramp is a sudden, involuntary muscle contraction or over-shortening; while generally temporary and non-damaging, they can cause significant pain, and a paralysis-like immobility of the affected muscle. Onset is usually sudden, and it resolves on its own over a period of several seconds, minutes or hours. Cramps...
how can the hubble space telescope keep its lens pointed in the same spot to take long exposure shots when it's orbiting the earth every 97 minutes?	Hubble uses six gyroscopes to know exactly where it's pointing. These are devices that act a bit like a compass, and always point in the same direction even when the telescope is orbiting. Next it has four reaction wheels which actually move the telescope. These just use Newton's 3rd law of motion; if the wheel spins ...	[ "The Hubble Space Telescope has three fine guidance sensors (FGSs). Two are used to point and lock the telescope onto the target, and the third can be used for position measurements - also known as astrometry. Because the FGSs are so accurate, they can be used to measure stellar distances and also to investigate bi...
what do fireworks event companies do the rest of the year? how do they stay profitable?	Sporting events mostly. A lot of minor league baseball teams have displays at the end of weekend games. Same with other sports as well.	[ "Fireworks Entertainment was an independent studio founded by Jay Firestone in 1996 to produce, distribute and finance television shows and feature films. Fireworks was acquired by Canwest Global in May 1998, and was later sold to ContentFilm (production company of The Cooler), a British company, in April 2005. Ove...
Why didn't land animals evolve to dinosaur size again after their extinction?	From our [FAQ](_URL_5_) (which I wrote, hence the copypasta): There have been much larger terrestrial mammals in the past. [Paraceratherium](_URL_6_) is an example. There are also mammals alive today that are as large or larger than the largest dinosaurs (blue whales!). However, the fact remains that some dinosaurs ...	[ "BULLET::::- Archibald argued that the withdrawal of shallow seas from Earth's continents during the Late Cretaceous reduced the size of and fragmented the coastal plain habitats preferred by large dinosaur species and that this fragmentation may have driven some taxa extinct.\n", "After the Cretaceous–Paleogene ...
what is computer science?	So, this rundown is my own, and the idea here is to have a pseudo-historical list running in descending order of abstraction. Basically, I'll start with the most abstract and general ideas of the field, and work down towards nitty gritty practical bits that emerged. But anyway, the main idea of computer science is to ...	[ "Computer science is known by its near synonyms, like Information Technology (IT) and Computing. At the beginning, only a few students can get computer science education, but as time passes, it’s popular in ordinary people. In UK, in 1981, only A level students can get it, but in 2014, even common pupils can study ...
What defines the maximum and minimum wavelength of electromagnetic radiation?	There is no maximum or minimum wavelength, any wavelength can be transformed into another one with the right choice of reference frame. A possible exception to this is if quantum gravity breaks Lorentz symmetry, and then there will be some minimum Planck-scale wavelength.	[ "The electromagnetic spectrum extends from below frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. That would be wavelengths from 10 to 10 kilometers. The long wavelength limit is the size of...
when i wake up at 3 am to pee, why does keeping my eyes closed for my trip to the bathroom seem to help me get back to sleep faster?	Your brain has this thing called a circadian rhythm. What it's designed to do is make you sleepy at night time and wakeful during the day. Unfortunately, your body doesn't have a clock inside of it so it has to rely on cues outside of you to know when it's night and when it's day. One of the cues your body uses is ligh...	[ "\"Urinating in bed is frequently predisposed by deep sleep: when urine begins to flow, its inner nature and hidden will (resembling the will to breathe) drives urine out before the child awakes. When children become stronger and more robust, their sleep is lighter and they stop urinating.\"\n", "Mowrer detailed ...
When a hot surface (a grill) is radiating hot air, why is there distortion in the air above it?	The angle at which air refracts light changes based on density. There is a temperature and density gradient between the hot grill and relatively cool surrounding air.	[ "Convection causes the temperature of the air to vary, and the variation between the hot air at the surface of the road and the denser cool air above it creates a gradient in the refractive index of the air. This produces a blurred shimmering effect, which affects the ability to resolve objects, the effect being in...
Is there any evidence that essential oils actually do anything other than smell good?	Essential oil simple means that is possess a smell similar to the plant it is derived from. It isn't based on anything medical related. Now that doesn't mean that they arn't good for you, it just means that it is a large category that isn't related to anything medical. Its sort of like asking if the category food is go...	[ "Essential oils are volatile and liquid aroma compounds from natural sources, usually plants. They are not oils in a strict sense, but often share with oils a poor solubility in water. Essential oils often have an odor and are therefore used in food flavoring and perfumery. They are usually prepared by fragrance ex...
how do they move sculptures that are to big for trucks?	> Edit: ah dicks, forgot ELI5 Ha. It's ok. It's still evident this is a legit ELI5 question. I really wish there were a better answer, but they pretty much just [close down all the roads](_URL_0_). It's super inconvenient (which is why they try to do it late at night). LA has something of a habit of frequently inc...	[ "The articulated haulers relatively small size also make them able to drive on public roads between different worksites at a large construction project—something that is impossible for the largest haul trucks, which might even have to be disassembled to be moved between different locations. For transportation betwe...
Does "alcoholism" or "alcoholic" have a scientific definition, or is it a more subjective term?	The DSM-IV-TR has definitions for alcohol abuse and alcohol dependence - [link](_URL_0_). It's important to note that (a) The DSM V is due very shortly and (b) There are many researchers who feel that the DSM does not use the best model. In regards to your question, it's worth noting that the criteria are a combinat...	[ "The term \"alcoholism\" is commonly used amongst laypeople, but the word is poorly defined. The WHO calls \"alcoholism\" \"a term of long-standing use and variable meaning\", and use of the term was disfavored by a 1979 WHO expert committee. \"The Big Book\" (from Alcoholics Anonymous) states that once a person is...
how can an aircrafts engine work at such high altitudes where humans struggle to breathe due to lack of oxygen?	The aircraft require less power at high altitude because of less air resistance but very few aircraft can operate at very high levels due to the lack of air.	[ "The human body can adapt to high altitude through both immediate and long-term acclimatization. At high altitude, in the short term, the lack of oxygen is sensed by the carotid bodies, which causes an increase in the breathing depth and rate (hyperpnea). However, hyperpnea also causes the adverse effect of respira...
What are the heat related consequences of urination?	When urine leaves your body it is body temperature. Your body either heats, or is heated, by the cold or hot food and liquids you eat. Urinating itself does not change your body temperature as you are evacuating this temperature stabilized liquid.	[ "The temperature at which the urine is examined is a very important factor to consider in the process of uroscopy. When a patient urinates, the urine will be warm, so it is necessary for it to stay warm for proper evaluation. The external temperature should be the same as the internal temperature. When the temperat...
why does the western world (say usa and western europe) get involved in armed local conflicts all over the world even if it doesn't have to?	Several reasons. 1) We have interconnected economies. So having trade access to resources means that some conflict that you would not think would affect a country really do affect them. 2) We now have invented weapons that are capable of destroying civilization as we know it with a push of a button. Limiting who ge...	[ "There is significant debate over whether the lack of any major European general wars since 1945, is due to cooperation and integration of liberal-democratic European states themselves (as in the European Union or Franco-German cooperation), an enforced peace due to intervention of the Soviet Union and the United S...
What portion of the world's current gold supply was part of Atahualpa's ransom?	Let's assume that Hernando Pizarro was telling the truth about the size of the ransom and that all the promised ransom was received. Here is the description from Hernando Pizarro > for that he could give them ten thousand plates, and that he could fill the room in which he was up to a white line, which was the he...	[ "In 1532, Francisco Pizarro was paid a ransom amounting to a roomful of gold by the Inca Empire before having their leader Atahualpa, his victim, executed in a ridiculous trial. The ransom payment received by Pizarro is recognized as the largest ever paid to a single individual, probably over $2 billion in today's ...
Why was the practice of presenting men, who refused to enlist in the army, a white feather supported by early feminist organizations?	The so-called 'Order of the White Feather' was created in Britain in 1914 by a former admiral, and essentially involved handing out 'white feathers' to anyone, specifically men, not seen as supporting the war effort, ie not enlisting. Some British women's organizations handed out feathers, an act that symbolizes 'cowar...	[ "Despite their obvious distinctions from men, women were eager to volunteer. Many of the servicewomen came from restricted backgrounds; therefore they found the army liberating. Other reasons women volunteered included escaping unhappy homes or marriages, or to have a more stimulating job. The overwhelming reason f...
In the Byzantine Empire, what type of names did people have?	That depends on the time period and location. Up until around the sixth century, you can see a lot of emperors having Latinate names, like Flavius Sabbatius Iustinianus (not that I'm biased!), Constantinus, or Iulianus. Later, more Hellenic names appear, like Basileios the Bulgar-Slayer or Alexios Komnenos. It's wor...	[ "Many peoples neighboring on the Byzantine Empire used names expressing concepts like \"The Great City\", \"City of the Emperors\", \"Capital of the Romans\" or similar. During the 10th to 12th century Constantinople was one of the largest two cities in the world, the other being Baghdad.\n", "Of Byzantine origin...
To what extent did the Soviet-Polish war cause Poland to be successfully invaded in 1939?	The Polish army was strong for a country of its economical development - it was well trained and equipped with modern arms. However, they were unable to stand up to the full power of a grand power such as Germany, and even less the power of two grand powers (Germany and the Soviet Union). The Soviet-Polish war and the...	[ "The Polish–Soviet War (February 1919 – March 1921) was an armed conflict between Soviet Russia and Soviet Ukraine on the one hand and the Second Polish Republic and the short-lived Ukrainian People's Republic on the other. The war was the result of conflicting expansionist ambitions. Poland, whose statehood had ju...
why is perpetual energy from gravity impossible?	Gravity pulls things down. You can exploit this for energy, but only once. Once the object has exhausted its "gravitational potential" (i.e. hit the ground) you can't extract any more without first picking it up again. We do extract energy from falling water in hydroelectric dams, but again the water can only pass t...	[ "Gravity also acts at a distance, without an apparent energy source, but to get energy out of a gravitational field (for instance, by dropping a heavy object, producing kinetic energy as it falls) one has to put energy in (for instance, by lifting the object up), and some energy is always dissipated in the process....
When I see gray, what wavelengths am I seeing?	Many times the color grey is generated by a mixture of compounds. Some which absorb and some which reflect. For instance if you mix white paint with black paint you will end up with a grey color because the mixture contains compounds which reflect all light and compounds which absorb all light. So at any given poin...	[ "Wavelengths and frequencies in gray indicate dominant wavelengths and frequencies, not actual range of spectrum composing a specified color, which extends farther to both sides and is averaged by receptors to give a near-spectral appearance.\n", "The normal three kinds of light-sensitive photoreceptor cells in t...
how do people get hd clips from tv to the internet?	A PC with a "Capture Card" of one kind or another. HD material from a cable/satellite box gets fed into the computer, where it's "captured", and can then be edited and uploaded. It's not legal, but it is rather easy with modern software.	[ "The Slingbox is a TV streaming media device made by Sling Media that encodes local video for transmission over the Internet to a remote device (sometimes called placeshifting). It allows users to remotely view and control their cable, satellite, or digital video recorder (DVR) system at home from a remote Internet...
Are there any animals whose blood is not red?	Yes, but it's not particularly common. A common example is the [horseshoe crab](_URL_0_), which has hemocyanin in place of hemoglobin. Vertebrate blood's red color comes largely from hemoglobin, which is bright red when oxygenated and a darker red when deoxygenated. Hemocyanin is blue when oxygenated and colorless w...	[ "Vertebrate blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some mollusks use a fluid called hemolymph instead of blood, the difference being that hemolymph ...
degrees of education	Associate's Degree: 2 years Bachelor's Degree: 4 years Master's Degree: Bachelor's + 2 years Doctoral/Ph.D: Bachelor's + 4-6 years.	[ "The Master of Education (M.Ed. or Ed.M.; Latin \"Magister Educationis\" or \"Educationis Magister\") is a master's degree awarded by universities in many countries. This degree in education often includes the following majors: curriculum and instruction, counseling, school psychology, and administration. It is oft...
why has easter turned into a time to celebrate finding chocolate/eggs from a bunny?	You might ask why did Easter turned into a Christian holiday "celebrating" the torture and death of their god when it is actually (and originally) about the Spring Equinox and fertility.	[ "Traditional Easter foods commonly consumed in Australia include Hot Cross Buns, recalling the cross of the Crucifixion, and chocolate Easter Eggs – symbolic of the promise of \"New Life\" offered by the Resurrection. Although chocolate eggs are now eaten throughout the period, eggs were traditionally exchanged on ...
Why we're African slaves not more common in the uk?	There was a legal question regarding whether or not the state of enslavement could exist on British soil. The situation was ambiguous, and certain West Indian plantation owners did bring slaves back to Britain with them, as personal valets/maids and the like. However, it became increasingly common, as the 18th century ...	[ "In the book \"\", the author Charles Mann cites sources that speculate that the reason African slaves were brought to the British Americas was because of their immunity to malaria. Britain did not have large numbers of African slaves, there were plenty of unemployed workers who could come as indentured servants. I...
Does a satellite experience centrifugal force or centripetal force?	It depends on your frame of reference. In an inertial frame stationary with respect to the Earth, the satellite is only subject to a centripetal force (gravity). In a reference frame co-rotating with the satellite, the centripetal force is still there, and there is additionally a centrifugal force equal and opposite t...	[ "Newton's idea of a centripetal force corresponds to what is nowadays referred to as a central force. When a satellite is in orbit around a planet, gravity is considered to be a centripetal force even though in the case of eccentric orbits, the gravitational force is directed towards the focus, and not towards the ...
how was the internet made? like how did they discover coding, etc?	Computers predate the internet by several decades, but the origins of the internet can be traced back to a US Military project in the 1960's called Arpanet. They wanted to see if they could get computers to communicate with each other. The first data packet was sent from a computer at UCLA to one at Stanford in 1969. T...	[ "As the Internet grew from a forum for sharing information to a marketplace for doing business, a technology matured that allowed computers to transact with each other more easily. Out of these Internet roots, web service technology was born.\n", "While the Internet began with a U.S. Government research project i...
Does boiling the same tap water multiple times change anything in it?	Boiling water multiple times reduces the dissolved oxygen and any other dissolved gases, as the solubility for these decreases with temperature. No new minerals are added or dissolved upon multiple boils - whatever minerals come out of your tap are mostly unchanged during the events you describe, but one major chemica...	[ "The traditional advice of boiling water for ten minutes is mainly for additional safety, since microbes start getting eliminated at temperatures greater than and bringing it to its boiling point is also a useful indication that can be seen without the help of a thermometer, and by this time, the water is disinfect...
What did people in the 'Old West' name their pets?	I'm honestly more curious about horse names	[ "Bob and Larry narrates that a long time ago, way out in the West somewhere, on a ranch known as the Okie-Dokie corral, there lived a group of cowboy brothers. One of the brothers named Reuben greets the viewers with \"'Allo, little doggies!\" After that, the rest of the brothers were introduced, who are all named ...
How did Italians preserve the tomatos needed for many of their dishes, prior to the invention of canning?	Sorry, other poster is dead wrong, tomatoes were eaten fresh only rarely before the invention of commercial canning, getting down on fresh tomatoes is a pretty modern thing, your pre-canning tomato breeds would not make for tasty fresh eating, pretty acidic. But they were certainly preserved, it's a smart question you'...	[ "The misconception that the tomato has been central to Italian cuisine since its introduction from the Americas is often repeated. Though the tomato was introduced from the Spanish New World to European botanists in the 16th century, tomato sauce made a relatively late entry in Italian cuisine: in Antonio Latini's ...
why does the burn of putting your leg in hot water seem to come a second or so after it’s been pulled out?	So there’s ‘two’ nervous systems that usually work together. This is an example of where one takes over first. - CNS = Brain. It controls the actions you think about so it takes longer to work. - PNS = No Brain. Controls reflex actions, ones you don’t have to think about, so it’s faster. The leg in hot water reaction...	[ "If the burn has been initially noticed, then HF should be washed off with a forceful stream of water for ten to fifteen minutes to prevent its further penetration into the body. Clothing used by the person burned may also present a danger. Hydrofluoric acid exposure is often treated with calcium gluconate, a sourc...
Why don’t everyday movements cause sub-concussive impacts?	This is counterintuitive, but if the density of the egg in your example is roughly the same as the density of the fluid (so that it can float in it) then shaking the jar wouldn't make it bounce, it would keep floating roughly in the middle no matter what you do. Sudden acceleration only causes problems proportional to...	[ "Other issues arise when one attempts to locate a movement's impact in all arenas. Impacts are most often studied at the political level, and yet it has been proven that they have individual, cultural, institutional, and international effects as well. Lastly, and most importantly, there is the issue of causality. I...
why are commercials so bad? why dont companies hire comedians or any other kind of professional to create commercials for them?	Cost. Using big stars or producers is expensive, add on the cost of the time slot for the commercial and it cuts into company money. The smaller the business, the lower quality production	[ "BULLET::::- Advertising: Some moviegoers complain about commercial advertising shorts played before films, arguing that their absence used to be one of the main advantages of going to a movie theater. Other critics such as Roger Ebert have expressed concerns that these advertisements, plus an excessive number of m...
What exactly are virtual particles? For example, a Weyl Fermion is apparently exciting for semiconductor applications, but what properties does it have that make it so?	Virtual particles appear in perturbative field theory. When calculating observables in a field theory, it is almost always impossible to solve the problem exactly, so you develop a method to compute things approximately (this is called perturbation theory). The most useful way to do this is to introduce Feynman diagram...	[ "Optical properties of semiconductor quantum dot-inorganic nanotube hybrids reveal efficient resonant energy transfer from the quantum dot to the inorganic nanotubes upon photoexcitation. Nanodevices based on one-dimensional nanomaterials are thought for next-generation electronic and photoelectronic systems having...
why is the water contained in a source like soda any less beneficial?	Soda is > 90% water (probably 98% or so). If you want to drink 8 glasses of water a day, 8 sodas would do it but the sugar and sodium would be terrible for you're health. Someone who says they don't drink any water, just soda, or that drinking soda doesn't count as water has no idea what they're talking about. It w...	[ "Bottled noncarbonated drinking water competes in the marketplace with carbonated beverages (including carbonated water) sold in individual plastic bottles. Consumption of water often is considered a healthier substitute for sodas.\n", "By itself, carbonated water appears to have little impact on health. While ca...
how are some mods in gaming compatible to new game versions while other mods need to be updated? (eg. skyrim - compatible after patch but minecraft - mods need updates)	It depends on what those mods were doing to the game files, and what was changed in those files between versions. For example, if you alter the "running speed" value in the movement script, it's not likely the company is going to change the way movement works between versions, so your mod will still work. For a count...	[ "Mods (short for modifications) are an optional upgrade for characters within the game. Once the player's account reaches level 50, Mods become available to any of their characters that are level 50 or above. There are different categories of mods, each of which yields a different primary effect on the stats of the...
Why do specific laws apply to the universe?	Physicists are much better at answering 'how' than why. E.g: "How do magnets work?" "How does gravity work?" Why is a much more philosophical question and is, in a sense, much less defined (and therefore less interesting :P) than actually learning how things work.	[ "Since the current laws of physics are only known to be valid in this universe, it is possible that the laws of physics are different in parallel universes, giving a God-like entity more power. If the number of universes is unlimited, then the power of a certain God-like entity is also unlimited, since the laws of ...
what exactly happens to your skin when it reacts to posion ivy?	It's called a type IV hypersensitivity reaction, more commonly known as an allergic reaction. This is a special type of allergic reaction that is not caused by histamine like most allergies are. This type of reaction is due to T cells attacking your own cells because they have an antigen (poison ivy) in them and your i...	[ "The pentadecylcatechols of the oleoresin within the sap of poison ivy and related plants causes the allergic reaction; the plants produce a mixture of pentadecylcatechols, which collectively is called urushiol. After injury, the sap leaks to the surface of the plant where the urushiol becomes a blackish lacquer af...
What makes some cancer "inoperable"?	Sometimes the cancer can occur in places where it would otherwise kill the patient. Like a tumor deep inside the brain might require a surgeon to do too much damage getting it out, or risk breaking up the tumor and causing it to spread in the body (the cancer cells can take up residence in other places, including the w...	[ "Overdiagnosed patients cannot benefit from the detection and treatment of their \"cancer\", because the cancer was never destined to cause symptoms or death. They can only be harmed. There are three categories of harm associated with overdiagnosis:\n", "Although most benign tumors are not life-threatening, many ...
resting membrane potential. why it hyper/hypopolarizes?	The potassium and sodium ion concentrations are what cause the neuron to fire. Or actually they allow the action potential to propagate along the nerve. A nerve cell starts off polarized,meaning the outside of the membrane is positively charged and the inside is negatively charged. the outside contains excess sodium ...	[ "This phase is also known as the \"plateau\" phase due to the membrane potential remaining almost constant, as the membrane slowly begins to repolarize. This is due to the near balance of charge moving into and out of the cell. During this phase delayed rectifier potassium channels allow potassium to leave the cell...
How fast was the decline of civilisation in Europe (including Britain) after the fall of the Roman empire?	This is a difficult question to answer, due to the size of the empire and how different regions reacted differently to the decline of Roman authority, but generally I would say that though decline was visible in the West, it was a gradual one. In the Eastern Mediterranean, not much has changed at all - Egypt was as pro...	[ "By comparison, what is now the territory of China experienced 0.1 per cent annual growth from 1 CE to 1800 CE. After population decline following the disintegration of the western half of the Roman state in the fifth and sixth centuries, Europe probably re-attained Roman-era population totals in the twelfth and th...
do people in other countries have the same view of the moon that i do if we look at it at the same time?	Because the moon is tidally locked (the sun only shines on one side at any given time), only one side of the moon is illuminated. This is why we had to send spacecraft to the far side of the moon to see what it looked like. In other countries, the moon may be in a different position in the sky due to its position on E...	[ "Generally, the Moon can be viewed even with the naked eye, however it may be more enjoyable with optical instruments. The primary lunar surface features detectable to the naked eye are the lunar maria or \"seas\", large basaltic plains which form imaginary figures as the traditional \"Moon Rabbit\" or familiar \"M...
why is it now 4k and 8k instead of 2160p and 4320p	Well, for one thing, it's easier to say, and easier to remember. But I believe the real reason is that using the horizontal pixel count a more consistent number to use over vertical, since number of vertical pixels changes according to the aspect ratio of a movie, e.g. 1.78:1, 1.85, 2.35:1, etc all have a different h...	[ "The term \"2160p\" could be applied to any format with a height of 2160 pixels, but it is most commonly used in reference to the 4K UHDTV resolution of due to its association with the well-known 720p and 1080p HDTV formats. Although is both a 4K resolution and a 2160p resolution, these terms cannot always be used ...
What would have Mary called her son?	Jesus is his name as passed through a number of transitions through other languages. The original Hebrew or Aramaic name would be something like Yoshua. Some modern groups make a big deal of calling Jesus by his "real" name. Earlier centuries didn't worry about that though. It was common for names of biblical figures,...	[ "The birth of Mary is narrated in the Quran with references to her father as well as her mother. Mary's father is called \"Imran\". He is the equivalent of Joachim in Christian tradition. Her mother, according to al-Tabari, is called \"Hannah\", which is the same name as in Christian tradition (Saint Anne). Muslim ...
why don't artists just release their entire album as singles to increase chart performance and song sales?	A lot of artists produce songs which are meant to be listened together and in sequence as they enhance and compliment one another. If they were sold individually and listened to individually they would sound a lot worse because the artist would have failed to create an atmosphere needed to enjoy some of their works. S...	[ "As the decades passed, the recording industry concentrated more on album sales than singles sales. Musicians eventually expressed their creative output in the form of full-length albums rather than singles, and by the 1990s many record companies stopped releasing singles altogether (see \"Album Cuts\", below). Eve...
what is the physiology behind being gay, lesbian, bisexual, transgender?	We're not really clear on it yet. There's some studies that suggest that transgendered people have brains that are physically closer to that of the sex they identify as, and some theories about hormone differences while in utero altering brain chemistry, but there's no real concrete answers yet.	[ "The concepts of gender identity and transgender identity differ from that of sexual orientation. Sexual orientation describes an individual's enduring physical, romantic, emotional, or spiritual attraction to another person, while gender identity is one's personal sense of being a man or a woman. Transgender peopl...
How were the craters on the side of the moon facing earth created?	[Here are Earth and Moon, to scale](_URL_0_) Does that answer the question?	[ "The crater was discovered in January 2008 during the first flyby of the planet by \"MESSENGER\" spacecraft. It contains a large (), nearly circular pit crater. Multiple examples of pit craters have been observed on Mercury on the floors of impact craters, leading to the name pit-floor craters for the impact struct...
what type of data is obtained from underground nuclear tests?	The main purpose of a test is find out whether the device can be safely armed and successfully detonated. The tests are performed underground for environmental and safety purposes, but can make taking precise measurements difficult. If buried at an adequate depth, yields can be roughly estimated based on the size o...	[ "Nuclear Data Incorporated was a manufacturer of scientific measuring devices for high energy physics laboratories. Application areas included X-ray analysis and radiation monitoring. In the 1960s, they built minicomputers to automate their laboratory devices, such as the ND 812. Over time they replaced these custo...
How dense does air get in the compressor of a jet engine?	For an isentropic (idealized) compressor, the density change is equal to the pressure change raised to the power of 1/gamma (1/1.4 for air). So a (high end) compressor ratio of 40:1 will give a density ratio of 14:1. At sea level, you're looking at 1.2 kg/m^3 ambient density, so it'd be compressed to ~17 kg/m^3. Less ...	[ "Air was initially compressed (and heated) by the inlet spike and subsequent converging duct between the center body and inlet cowl. The shock waves generated slowed the air to subsonic speeds relative to the engine. The air then entered the engine compressor. Some of this compressor flow (20% at cruise) was remove...
Why did the Romans have so much trouble with the Germanic tribes?	I wouldn't say I'm an expert on the Germanic tribes, but having read fairly extensively on Caesar, Varus and Germanicus, I can give you some background. The Romans actually did a pretty good job of whipping German butt. At the end of the first century BCE, Tiberius (soon to be emperor) and his legates had done a damn...	[ "The Empire's historical relationship with Germanic tribes was sometimes hostile, at other times cooperative, but ultimately fatal, as it was unable to prevent those tribes from assuming a dominant role in the relationship. By the early 5th century, as a result of severe losses and depleted tax income, the Western ...
How did mammoth hunting cultures harvest the meat?	you should also try to ask this over at r/askanthropology but the current thinking is that the mammoth would be butchered where it fell. Bison (Bison bison), were much smaller and they tended to be butchered where they fell as well. There is a paper where they experimented by butchering a dead zoo elephant but I don'...	[ "Several woolly mammoth specimens show evidence of being butchered by humans, which is indicated by breaks, cut marks, and associated stone tools. How much prehistoric humans relied on woolly mammoth meat is unknown, since many other large herbivores were available. Many mammoth carcasses may have been scavenged by...

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