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train · 226k rows

question stringlengths 3 301	answer stringlengths 9 26.1k	context list
why do fans only propel air in one direction? if the blades are perfectly symmetrical should air be propelled from the front and the back of the fan?	Fans have a rotational symmetry, but have no symmetry in the direction of airflow. They propel air one direction only, toward the direction that the leading edge of fan blades point toward. Of course, you can reverse the airflow by simply reversing the fan rotation. However, many fans aren't symmetrical in this sense e...	[ "When the fan spins with the upper edge moving backwards and the lower edge forwards, the fixed half-duct is shaped to create a net backward flow of air, resulting in forward thrust. This backward flow over the upper surfaces also creates a net circulation of air around the rotor-wing combination, resulting in vert...
Does the Sun have Lagrangian points with the center of the Milky Way?	In short, no. The Lagrange points are specifically libration points of a three-body problem, typically the Sun-Earth-L_point and Earth-Moon-L_point systems. You can also construct them for essentially any masses you want but they need to be the significant attractors in the range. The Sun-Galaxy_center-L_point system...	[ "In astronomy, Lagrangian points are five positions in the orbital plane of two large orbiting bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies. The first three Lagrangian points (L, L, L) lie along the line connecting the two large bodies, while t...
how come so many crimes in the us carry draconian jail sentences or laughable fines at the same time?	* Part of the reason is that the laws become outdated so the fines were at one point suitable for the crime. * Another part of the reason is that often people will plea out and get a much lower sentence but it still gives the judge a chance to impose a harsh sentence if warranted.	[ "The criminal code listed three main categories of crime: contraventions (minor offenses), misdemeanors (offenses punishable by imprisonment or fines), and felonies (offenses punishable by penal servitude or death). Lower courts handled the majority of the cases that reached adjudication and levied fines in about n...
why do are some flowers from the same plant different coloured?	Some flowering plants can just naturally produce multiple colors of flower like how humans have more than one eye color, or have flowers that change color as they mature.	[ "Usually, the flowers are yellow, pink and white, but a different combination of flowers growing on the same single four o’clock plant can be found. Another interesting point is a color-changing phenomenon. For example, in the yellow variety, as the plant matures, it can display flowers that gradually change to a d...
why is it so near impossible to breathe in through your nose and out through your mouth simultaneously?	Well, because some flaps of tissue are normally supposed to move into place to prevent that from happening. Circular breathing gets around this by storing some exhaled air in the cheeks and continuing to exhale that while simultaneously breathing into the lungs through the nose. It's very, very hard to do and it takes ...	[ "The nasal airway may be compromised partially (where there is increased resistance to the flow of air due to narrowing of the lumen at some point in the upper respiratory tract) or completely obstructed. Such individuals may find it difficult or impossible to breathe through their nose alone. In about 85% of cases...
Can you break your own neck just using your hands?	It's a lot harder to break you neck then you see in the movies.	[ "A neck crank (sometimes also referred to as a neck lock, and technically known as a cervical lock) is a spinal lock applied to the cervical spine causing hyperextension, hyperflexion, lateral hyperflexion, hyperrotation or extension-distraction. This happens either through bending, twisting or elongating. A neck c...
how roger goodell still has a job if it seems most members of the nflpa and most people on nfl teams seem to think that he is incompetent.	Roger Goodell doesn't work for the NFLPA or the "people on NFL teams", he works for the owners of the teams. The owners (and Goodell) care about the business aspects, and under Goodell's watch the NFL's revenue has grown by about 4 billion dollars. The particular thing that Goodell has been able to do is unite the...	[ "During his Hall of Fame speech in 2006 Harry Carson does not directly mention CTE, but he does mention that he does not think the NFL is doing the best job they can to help out ex-NFL players. When he states \"I would hope that the leaders of the NFL, the future commissioner, and the player association do a much b...
On spaceship re-entry why wait to deploy parachute?	If you deploy a parachute immediately following reentry, it will need to be able to handle the dynamic pressure (and thus very high forces) due to supersonic flight. This can be done but the hardware will be very heavy. Alternatively, you can wait until later (because the vehicle is still slowing down to its subsonic ...	[ "The parachute quickly filled with water and dragged the capsule and its crew beneath the surface; in addition an electrical short caused by the water impact caused the reserve parachute to accidentally deploy. The capsule cooled in the freezing water, and the cosmonauts removed their pressure suits and donned thei...
Does scratching make a bugbite worse?	Scratching can tear the skin and allow infection a way in.	[ "Both the above argument and explanation require knowing the generalities that a) fleas often cause itching, and b) that one often scratches to relieve itching. The difference is in the intent: an argument attempts to settle whether or not some claim is true, and an explanation attempts to provide understanding of ...
what exactly happens when you get a "chill" up your back?	It is your hair follicles that are flexing, resulting in goose bumps and a tingly feeling. It is associated with an emotional response, like when you listen to nice music.	[ "A cold chill (also known as chills, the chills or simply thrills) is described by David Huron as, \"a pleasant tingling feeling, associated with the flexing of hair follicles resulting in goose bumps (technically called piloerection), accompanied by a cold sensation, and sometimes producing a shudder or shiver.\" ...
Hey historians! As a French gal I often get told pretty bad jokes about how I should just surrender whenever a challenge comes up. I'd like to know if the jokes are justified and the French were indeed complete idiots, or just something blown out of proportions	France's major surrender, and the one which most people are aware of was in 1940. Though faced with not much of a choice - the combined German military would have overwhelmed the French defensive forces still left, it was handled in a less than edifying manner by Petain, who acquiesced completely to the German demands...	[ "In the turbulent aftermath of the French Revolution Napoleon Bonaparte is accused of treachery and corruption. His reputation is saved by his skill in leading his men to victory in Italy and Egypt. But then he must rush home to France to restore order amidst political unrest, and to find peace or victory over the ...
How were Christian missionaries from the West perceived in the Mongolian Empire	I would recommend checking out John of Plano Carpini's writings of his travels to the court of Ogedei Khan. _URL_0_ When he travelled to the Guyuk Khan's court he bore with him a letter from Pope Innocent IV called Cum Non Solum. In it, the Pope inquires as to the Mongols future intentions, requests that Christians b...	[ "Christianity in Mongolia has ancient roots. Nestorianism had been practiced since the 7th century, and in the 13th century Western missionaries such as William Rubruck and Giovanni da Pian del Carpine and Armenian King Hethum I visited the region. The leaders of the Mongol Empire were traditionally tolerant of man...
why was ww2 filmed so well and did the other countries of the axis film too?	Pretty much all the major countries on both sides had dedicated film units assigned to the cover combat operations. The reason was both to capture the events for historical purposes and perhaps more importantly for propaganda purposes on the home front. Countries took advantage of their own movie industries to send ...	[ "The Axis powers similarly made films during the Second World War, for propaganda and other purposes. In Germany, the army high command brought out \"Sieg im Westen\" (\"Victory in the West\", 1941). Other Nazi propaganda films had varied subjects, as with \"Kolberg\" (1945), which depicts stubborn Prussian resista...
Does an itchy scab really mean it's healing?	Scabs itch for several reasons. First of all, scabs contain histamines, which naturally irritates the skin surrounding the scab, causing it to itch. Doctors theorize that this may be the body's natural way to help the body rid itself of the scab when the scab has served its purpose and is no longer needed - it itches, ...	[ "Itch is also associated with some symptoms of psychiatric disorders such as tactile hallucinations, delusions of parasitosis, or obsessive-compulsive disorders (as in OCD-related neurotic scratching).\n", "Ecthyma, the nonbullous form of impetigo, produces painful fluid- or pus-filled sores with redness of skin,...
Is there any historical reason/evidence as to why African nations never became a world power?	You may be interested in these questions about “[Why is Africa "less developed"?](_URL_0_)” on our Popular Questions page (which is linked at the top of every page in this subreddit, and in the sidebar).	[ "This is a list of the dates when African states were made colonies or protectorates of European powers and lost their independence. It only deals with modern times, thus the expansion of the Ancient Greeks, Roman Empire, and barbarian tribes into Africa is ignored. A number of regions such as the Congo and the Sah...
positivism in the social sciences	VERY basically (all of the positions I'm about to mention has many variants), Positivism says that the only things we should say are true about the way society works are those things that we can physically see happen, record as data, and examine mathematically. There is a "real world" out there, a "correct" answer to e...	[ "Positivism follows the goal of preventing social unrest by convincing the lower classes to accept the domination of the upper classes in exchange for things such as material benefits, guidance, and general improvement. Comte postulated that there are three stages of social evolution that humankind passes through, ...
Why does drinking water turn my chewing gum to stone but my saliva doesn't? [x-post from askreddit]	Temperature. The viscosity of butyl rubber is very temperature dependent. The 99 degree saliva keeps it at a low viscosity, 50 degree water makes it much tougher. It will eventually return to the softer state as it warms back up.	[ "Gum chewing is regarded as a helpful way to cure halitosis (bad breath). Chewing gum not only helps to add freshness to breath but can aid in removing food particles and bacteria associated with bad breath from teeth. It does this by stimulating saliva, which essentially washes out the mouth. Chewing sugar-free gu...
Can anyone explain why calculators disagree with my paper and pen, here?	If A is the cube root of 100,000 and x is any not-too-large number, then the cube root of 100,000+x is approximately A+x/(3\*A^(2)). With x=1, this says the cube roots should differ after the 4th or 5th decimal place. If you want to find real solutions to x^(3)+y^(3)=z^(3), then it's really easy, just pick any real x,...	[ "The use of calculators became common in United States math instruction in the 1980s and 1990s. Critics have argued that calculator work, when not accompanied by a strong emphasis on the importance of showing work, allows students to get the answers to many problems without understanding the math involved. However,...
if the president wanted to pardon somebody like the green river killer, could he legally do so?	No. The President can only pardon people for crimes against the United States, Gary Ridgway was convicted by the State of Washington. The Governor of Washington could pardon him if he/she so chooses.	[ "The legal and constitutional ability of a president to pardon himself (self-pardon) is an unresolved issue. During the Watergate scandal, President Nixon's lawyer suggested that a self-pardon would be legal, while the Department of Justice issued a memorandum opinion on August 5, 1974, stating that a president can...
identical twins vs. paternal twins	There's no such thing as paternal twins. They're "fraternal" twins (i.e. brotherly twins). Identical twins came from the same fertilized egg, which split into two embryos. Fraternal twins came from two eggs. One is a problem with an egg dividing into two, the other is a problem with the ovaries firing off two eggs ...	[ "Twins are two offspring produced by the same pregnancy. Twins can be either \"monozygotic\" ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or \"dizygotic\" ('fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm c...
Why is there not a neutron star at the middle of the solar system?	1) Not all supernovae create neutron stars. It's thought that Type 1A supernovae do not. 2) Supernovae spread their heavy elements over a very wide area, some of which helps a large amount of material cool and collapse and form molecular clouds and eventually stars. It's not known how many supernovae played a big ro...	[ "Each star in the system has about eighty times the mass of the Sun. It is not clear why this system is located away from the center of the cluster. It is possible that the system was formed in the core, but that it was ejected by dynamical interactions.\n", "It has been calculated that the neutron star contains ...
Why is the luminiferous aether theory false?	My keyboard got stuck in Canadian French, apologies in advance. That article doesnt explain why the speed of light is constant in different reference frames, it just shows that electromagnetism implies a speed for electromagnetic waves and then declares its constant in all reference frames. However, if there were a fi...	[ "The concept of a Universe filled with a luminiferous aether retained support among some scientists until the early 20th century. This form of aether was viewed as the medium through which light could propagate. In 1887, the Michelson–Morley experiment tried to detect the Earth's motion through this medium by looki...
What are the reasons why Taiwan and Philippines have a relatively good relationship with Japan?	Being Taiwanese I think I can answer at least part of this question. Taiwan is very fiercely opposed to the PRC, although the old lines of hatred are beginning to soften a bit with increased trade and the influx of those very rude and smelly mainland tourists. Taiwan has very much an independent schooling system which ...	[ "Similar to Taiwan, the Philippines has been much quieter than other Asian countries invaded by the Japanese during World War II, even though many atrocities were committed by the invading Japanese during the war, such as the systematic rape of Filipino women whom the Japanese referred to as comfort women. An estim...
What would antimatter look like if we could produce enough to make a macroscopic object out of it?	It would look the same as regular matter.	[ "Exposure to antimatter is the only known method for destroying a General Products hull until the 2007 novel \"Fleet of Worlds\". In the story \"Flatlander\", a GP Hull is exposed to a constant stream of diffuse antimatter during a visit to a star system with some exotic qualities. Whereas a conventional hull made ...
[Medicine - Dermotology] What is the latest research on acne? Are dermatologists getting any closer to finding a cure?	Everyone please remember that no one is allowed to give medical advice. Any comment advocating the use of medication or certain brand names will be deleted immediately. Please no more personal stories about what worked and what didn't. This is a science forum, and all answers should be scientific in nature.	[ "Complementary medicine options for acne in general have not been shown to be effective in trials. These include aloe vera, pyridoxine (vitamin B6), fruit-derived acids, kampo (Japanese herbal medicine), ayurvedic herbal treatments and acupuncture.\n", "For the treatment of acne, the most prescribed retinoid drug...
in the united states (and perhaps elsewhere), pickles are almost always served as a side to deli foods. why is this common and why did it start?	It's common because they are delicious, easy to preserve, and cheap. Pickles have been popular for a few thousand years.	[ "The exact origins of pickling are unknown, but it may have begun in the area of Mohenjo Daro, in the northwest of the Indian subcontinent, about 2400 B.C. Pickling was used as a way to preserve food for out-of-season use and for long journeys, especially by sea. Salt pork and salt beef were common staples for sail...
What Would You Guys Say Was History's Most Influential Event On Our Modern World?	Too vague: Define 'modern.' And 'our.'	[ "Historians in recent decades have argued that from a worldwide standpoint, the most important feature of the early modern period was its globalizing character. The period witnessed the exploration and colonization of the Americas and the rise of sustained contacts between previously isolated parts of the globe. Th...
why did we need a stylus 15 years ago for touch screens but not now?	Back then, touch screens were based on pressure applied to the screen. Your finger applies pressure to quite a large area, so detecting the correct position of your finger isn't easy. Styluses apply pressure to a very small area, which makes it easy to detect them. Today, capacitive touch screens can very accurately d...	[ "The stylus is the primary input device for personal digital assistants. It is used on the Nintendo DS and 3DS handheld game consoles, and the Wii U's Wii U GamePad. Some smartphones, such as Windows Mobile phones, require a stylus for accurate input. However, devices featuring multi-touch finger-input are becoming...
What would happen if you shot a nuclear bomb?	So far as I understand it, nothing would happen. Nuclear bombs are not detonated by simple kinetic impact with the ground. They are detonated by complex systems designed to compress or fuse nuclear material into a supercritical mass. The conventional explosives inside a nuke are generally quite stable.	[ "BULLET::::- Nuclear missiles deliver a devastating payload. A direct hit on a city will kill half of the current living civilians. Between one and three hits are required on the hardened buildings that players place to destroy them. Missiles can only be shot down by silos in defense mode, which have a small random...
how are we able to increase things like our lung capacity or condition? aside from practice and condition training, what incites the improvement?	Lung capacity doesn't change but the way the body utilises the oxygen does. That's why people living at high altitudes with lower oxygen are able to function. Some develop more red blood cells to transport the oxygen and others get better at the exchange where air from the lungs crosses into the bloodstream Athletes...	[ "Lung capacity can be expanded through flexibility exercises such as yoga, breathing exercises, and physical activity. A greater lung capacity is sought by people such as athletes, freedivers, singers, and wind-instrument players. A stronger and larger lung capacity allows more air to be inhaled into the lungs. In ...
How did evolution create DNA error-checking function?	Very slowly. That is always the answer to something like this, so slowly that the tiny steps along the way are really difficult to imagine. When thinking of evolution of complex cellular machinery, survival of the fittest isn't always the easiest way to imagine it. First realize that not all mutations are going to be ...	[ "The error threshold is a concept in the origins of life (abiogenesis), in particular of very early life, before the advent of DNA. It is postulated that the first self-replicating molecules might have been small ribozyme-like RNA molecules. These molecules consist of strings of base pairs or \"digits\", and their ...
question: when-where-why did hate towards muslim begin?	I don't think I really understand the question? Muhammad and Muslims encountered "hatred" virtually from the outset. As confusing a historical document as the Qur'an may be this is clear from the Qur'an itself. Q37:36 for instance has the unbelievers respond to Muhammad's preaching by asking: > And [they] said: Shal...	[ "The rise in islamophobia in the United States, after the attacks on the World Trade Center, is an example of symbolic interactionism in practice. After the attacks on the World Trade Center on September 11, 2001, \"Arabs and Muslims (as well as Latinos, South Asians, and other individuals who were mistakenly perce...
Before genetics and evolution were discovered, what did people think caused family resemblance?	By Darwin’s time, and long before, there was a well organized and systematic approach to selective breeding of domestic animals. That’s where Darwin got a lot of his understanding from; the first chapter in [Origin of Species](_URL_0_) is called “Variation Under Domestication” and deals with topics that are obviously b...	[ "Modern genetics began with the work of the monk Gregor Mendel in the 19th century, on the inheritance of traits in pea plants. Mendel found that visible traits, such as whether peas were round or wrinkled, were inherited discretely, rather than by blending the attributes of the two parents. In 1900, Hugo de Vries ...
How many third Party Presidents have been elected in America?	Well...we got some problems here. Millard Fillmore was never elected President. He succeeded to the Presidency upon the death of Pres. Zachary Taylor, also a Whig. So Filmore was neither elected, nor from a "third party." Secondly, what matters also is how you define a "party" and a "third" party. I'm assuming you...	[ "The only three U.S. Presidents without a major party affiliation were George Washington, John Tyler, and Andrew Johnson, and only Washington served his entire tenure as an independent. Neither of the other two were ever elected president in their own right, both being vice presidents who ascended to office upon th...
What branch of the US Military was this a Uniform for in ~1862?	So there are a few parts to this that make me think he may be wearing a State's militia uniform. 1. Is that while it is similar to what the Regular Army would have been wearing around that time, its just a bit off. Compare it for instance to the M1833 Coat for Officer worn before and after the Mexican War in th...	[ "During the years 1860-1865 there were three distinct types of uniform in use by the United States Armed Forces. Styles used were traditional similar to those used in the Napoleonic Wars, a regimental dress such as used during the American Revolutionary War and a specialist dress similar to those worn by Lancers an...
what causes people to sometimes sneeze when exiting at dark environment (i.e. indoors) and enter a bright one (i.e. sunny day)?	Ahem. Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do we sneeze when we look at a light? ](_URL_3_) ^(_3 comments_) 1. [Why does staring at light help me sneeze? ](_URL_6_) ^(_4 comments_) 1. [ELI5: Why does looking at bright lights help us sneeze? ](_URL_2_) ^(_6 comments_) 1. [ELI5: Why...	[ "The photic sneeze effect is a genetic tendency to begin sneezing, sometimes many times consecutively (due to naso-ocular reflex), when suddenly exposed to bright light. This condition tends to occur more severely after one has emerged into the light after spending time in a dark environment. Although the syndrome ...
why does our conscious mind (morality, discipline,..) take a backseat when we are aroused/excited or in a tight situation (like public confrontation), etc.?	Many different modules in brain, do different things at different times. Older, primal modules, necessary for survival, care little what newfangeled expansions to brainspace say about situations it evolved to master countless generations before the rest of what is now you ever took shape. Old modules, never offline....	[ "As explained by the founder of cognitive therapy, Aaron Beck, our chronic thoughtflows (stream of consciousness) tend to dominate our inner experience and stimulate our behavior and emotions. If we want to change our inner experience (for instance from a negative mood to a more positive mood) we need to take charg...
What is the density of a Galaxy?	It doesn't have a uniform density (not even on large scales) and the average density depends critically on how much you include in the volume. Typical distances between nearby stars in the galactic disk (where we are) are a few light years. They are so far away that the gravitational influence of individual neighbor s...	[ "The density of stars increases toward the center in most galaxies. In small galaxies, this increase continues into the very center. In large galaxies, there is usually a \"core\", a region near the center where the density is constant or slowly rising. The size of the core – the \"core radius\" – can be a few hund...
What makes some powdered drink mixes dissolve so quickly?	Starbucks instant coffee is a combination of: 1) Freeze-dried instant coffee, which is highly water-soluble and hydrates pretty much instantly, and; 2) Extremely finely-ground whole coffee, which is light enough to enter suspension. These allows the oil-soluble flavors that are normally missing in instant coffee to b...	[ "Liquid–solid mixing is typically done to suspend coarse free-flowing solids, or to break up lumps of fine agglomerated solids. An example of the former is the mixing granulated sugar into water; an example of the latter is the mixing of flour or powdered milk into water. In the first case, the particles can be lif...
On stealth aircraft, how is it possible, that radars can 'see' out of the airframe, but enemy radars cannot see in?	Stealth does not mean radar cannot see it. The shape of the aircraft or item uses the inherit flaws of radar to mask itself. Radar works by waves being emitted, hitting and object, and returning to the receiver. If the waves bounce off at a different angle, say away from the receiver, then the object is not seen. Al...	[ "The radar emissions can be detected by enemy anti-aircraft systems with relative ease once there is no covering terrain, allowing the aircraft to be targeted. The use of terrain-following radar is therefore a compromise between the increased survivability due to terrain-masking and the ease with which the aircraft...
how is it that the monty hall problem and the gambler's fallacy don't contradict each other?	The key to the Monty Hall problem is that the door that's removed from play is never the door with the prize and never the door you initially chose. So if you choose a door at random, you initially have a 1/3 chance of being right and a 2/3 chance of being wrong. One of the doors you didn't choose is then removed ...	[ "The gambler's fallacy, also known as the Monte Carlo fallacy or the fallacy of the maturity of chances, is the mistaken belief that, if something happens more frequently than normal during a given period, it will happen less frequently in the future (or vice versa). In situations where the outcome being observed i...
Why don't rats learn to avoid rat poison?	They're extremely tentative about new foods they discover themselves. If a rat they trust offers or leads them to food, they're less tentative, but still have a strong association between the smell of the food and how they feel after eating it. Ninja edit: does anyone know the name of this phenomenon? (aversion to a ...	[ "When examining taste avoidance, however, the rat may avoid a food yet still enjoy it and choose it over others. In further tests, the rats were tested with another sucrose solution but this time it was paired with a drug that gave positive, euphoric effects, such as amphetamine, cocaine, and morphine. The rats sho...
when photos are taken of the international space station (and from it of earth), why aren't there satellites visible in the photos?	Space is big. We have a whole lot of satellites in orbit, but space is big. The biggest satellites are about the size of a car now imagine trying to see a car from a country away.	[ "4. There are no stars in any of the photos; the Apollo 11 astronauts also stated in post-mission press conferences that they did not remember seeing any stars during EVA. Conspiracists contend that NASA chose not to put the stars into the photos because astronomers would have been able to use them to determine whe...
why is there such a stigma against smoking tobacco in the us?	Enough people complained. There's no conspiracy here. Tobacco costs our healthcare system [billions](_URL_0_). Also, it's fucking annoying to us non-smokers.	[ "Debates on tobacco harm reduction tend to be geographically defined arguments, because of the varying legal, moral, and historical status of tobacco, and the different types of tobacco products and use in different cultures around the world. For instance, cigarette smoking is the dominant form in the United States...
what stops flies from moving to the back of the bus when it accelerates?	The air in the bus. There might be a bit of delay but the bus moving forward causes the air from the back of the bus to front to be pushed along forward as the air can't go anywhere else. So the fly will move with the air and be accelerated by the bus' forward motion.	[ "Flies are capable of great manoeuvrability during flight due to the presence of the halteres. These act as gyroscopic organs and are rapidly oscillated in time with the wings; they act as a balance and guidance system by providing rapid feedback to the wing-steering muscles, and flies deprived of their halteres ar...
why do standardized tests each have unique and seemingly arbitrary score ranges? (e.g. sat 400-1600, act 1 to 36, lsat 120-180, mcat 472 to 528, usmle step 1 1-300)	The short answer is that it is arbitrary. The longer answer is that the scoring systems reflect the priorities of the test makers. Many test creators intentionally set the lowest score far above 0 to make it more obvious that they are interval scales, not ratio scales. In other words, a score of 900 on the SAT is no...	[ "Two well-known tests in the United States that have scaled scores are the ACT and the SAT. The ACT's scale ranges from 0 to 36 and the SAT's from 200 to 800 (per section). Ostensibly, these two scales were selected to represent a mean and standard deviation of 18 and 6 (ACT), and 500 and 100. The upper and lower b...
How do we guarantee an object in space is a certain distance (light-years) away?	We can measure the angle in the sky between a close star and a distant background star, then wait six months and measure it again. As the Earth is now 300 million km from its original position after six months of orbit, a closer star would appear to be at a slightly different angle. Closer stars appear to shift by a bi...	[ "BULLET::::- NASA astronomers report that the Hubble Space Telescope can now precisely measure distances up to 10,000 light-years away by using spatial scanning, a ten-fold improvement over earlier measurements. ()\n", "BULLET::::- The distance to about 20 million stars will thus be measured with a precision of 1...
Post-Civil War, How were the Confederate Soldiers treated in terms of pension, health care, respect, etc?	A good deal of the American welfare states lies in the idea of providing pension for soldiers, their widows, and orphans. See Theda Skocpol's Protecting Soldiers and Mothers. Confederates were pensioned by individual states. This [website](_URL_0_) gives an overview. As the intro to the site says, "The veteran was...	[ "For much of the war, Confederate soldiers were relatively comfortable and well supplied. However, by the spring of 1864, the situation tightened. On March 4, 1864, Confederate General Order No 28 said that officers and enlisted men would receive one ration per day, giving no consideration for body servants. A numb...
How does the curvature of spacetime cause acceleration from a stand-still?	> The ball is not initially in motion In the sense of relativity, it is undergoing constant acceleration. It's only after it's released that it follows an unaccelerated path through spacetime. > does the curvature of space induce a motion? It's an apparent acceleration, not a real one (in fact, it's Earth's surf...	[ "Accelerations in special relativity (SR) follow, as in Newtonian Mechanics, by differentiation of velocity with respect to time. Because of the Lorentz transformation and time dilation, the concepts of time and distance become more complex, which also leads to more complex definitions of \"acceleration\". SR as th...
how do nfl plays work? how does the offense call plays/audible without the defense figuring it out?	They have playbooks with secret words associated with particular plays. Some words called are nonsense, others tell the team that memorized the plays what to do. The opposing team didn't get to see the playbook so they don't know what it means.	[ "Distinct from the offensive strategies or philosophies, which govern how a team moves the ball down the field, whether a team relies on downfield passes, short passes, inside runs, etc. are the ways in which plays are called. These play calling systems often developed alongside certain offensive strategies, though...
the "greedo shot first" controversy	There's a scene in the first Star Wars (A New Hope, episode IV) where Greedo, a bounty hunter, tracks down Han, who has a price on his head. In the original version, Han shoots Greedo first, which establishes him as kind of a badass. In the special edition released in the 90s, George Lucas felt the need to change it so...	[ "The Price of Folly is a 1937 British drama film directed by Walter Summers and starring Leonora Corbett, Colin Keith-Johnston and Judy Kelly. The screenplay concerns a man who, after a failed attempt to kill a woman, finds himself blackmailed over the incident.\n", "Battle of Greed is a 1937 American western fil...
why do metal scissors turn magnetic after a lot of use?	It doesn't, normally. They are either being stored in the presence of a magnetic field, or are being used to cut something magnetic, or are cutting nearby something magnetic. Sometimes people use a magnet to hold scissors onto something. It's possible that someone did this with one set of scissors and now it i...	[ "BULLET::::- Magnets can pick up magnetic items (iron nails, staples, tacks, paper clips) that are either too small, too hard to reach, or too thin for fingers to hold. Some screwdrivers are magnetized for this purpose.\n", "If a piece of copper wire was wound, around the nail and then connected to a battery, it ...
I have a cold and am curious, what defenses will the virus encounter (in order, from entry)?	First, there are physical barriers. Skin, for example. Then, assuming you got it through contact between your mucous membranes (mouth, nose, eyes) and particles containing the virus, there are antimicrobial agents in these mucous membranes (though most of these are geared toward being antibacterial, not antiviral) as...	[ "The common cold virus is typically transmitted via airborne droplets (aerosols), direct contact with infected nasal secretions, or fomites (contaminated objects). Which of these routes is of primary importance has not been determined. The viruses may survive for prolonged periods in the environment (over 18 hours ...
Do hormones in diet get broken down before they can work?	Well first off, estrogen, and most phyto-estrogens (estrogen like molecules from plants) are not proteins: they're metabolites of cholesterol. So the action of proteases in the stomach and small intensites isn't especially relevant. And neither the protein denaturing effect of cooking & #x200B; However, chemicals th...	[ "A suppressed or \"wrecked\" metabolism is another cause of obesity commonly cited by Holtorf. Holtorf claims the metabolism, when subjected to repeated or overzealous dieting and exercise, will regulate itself by repressing thyroid hormone levels in the body, resulting in a hypothyroid state. Even the return to no...
Did Americans travel to Australia to participate in the Australian Gold Rush?	Yes, it happened pretty much as you suggest, but people were crossing the oceans in every direction in search of gold, including from Australia to the US and then back. We have records of Europeans coming to California, and of Americans going to Canada and Australia in search of gold. Similarly people from around the w...	[ "The 1907–08 All Golds arrived back in Australia on 9 April. They spread themselves around the eight clubs that were preparing for the season and helped advise them on the rules of rugby league. The team watched the first round of the competition before heading to Newcastle and playing the first game of rugby leagu...
if two objects are traveling and hit each other does that produce more energy than a single object hitting a wall? why or why not?	It’s all relative. To an observer in space, with the earth’s rotation, the car and the wall may be moving towards each other at equal speed. Or, it may be moving away, and the car is moving faster to catch up with it. Momentum has a lot to do with it... the car’s resting state has it moving at the same speed as the ...	[ "During the collision of small objects, kinetic energy is first converted to potential energy associated with a repulsive force between the particles (when the particles move against this force, i.e. the angle between the force and the relative velocity is obtuse), then this potential energy is converted back to ki...
Why do I have to reinflate my bike tires every couple weeks or so, but I very rarely have to reinflate my car tires?	Bike tires have higher surface area to volume ratio, thinner rubber, and much higher air pressures than car tires. All of those things increase the rate at which air diffuses out of the tire, both in absolute and in relative terms.	[ "One disadvantage of patching a tire is that due to the process requiring one to remove the tire from the wheel, the tire must be balanced again when it is put back on the wheel. Tire sealant also creates an imbalance in the tire, but since it is a temporary repair, it is considered less of an issue. However, the i...
Why do microwave ovens and wireless routers operate on the same frequencyrange (~2.4GHz)?	There's only so much electromagnetic spectrum available; the FCC doesn't regulate microwave ovens (the EM field they produce is just noise). The rest of the bandwidth is incredibly valuable, and all of it, essentially, has been claimed for other purposes. You can see the full chart [here](_URL_0_). A tiny fraction is a...	[ "Previous considerations represent typical problems characterizing terrestrial radio links using microwaves for the so-called backbone networks: hop lengths of few tens of kilometers (typically 10 to 60 km) were largely used until the 1990s. Frequency bands below 10 GHz, and above all, the information to be transmi...
What causes something that has been balancing for a prolonged amount of time to fall over, without anything touching it?	Suggestions, more or less in decreasing order of probability: - Wind/air currents - Thermal effects on object or surface (expansion/contraction of something thermally causing slight changes over time in size, ultimately changing the geometry enough to move from stable to unstable) - Effects of extremely minor gravitat...	[ "Some objects are in \"resting contact\", that is, in collision, but neither bouncing off, nor interpenetrating, such as a vase resting on a table. In all cases, resting contact requires special treatment: If two objects collide (\"a posteriori\") or slide (\"a priori\") and their relative motion is below a thresho...
if we're eating at different times of the day, how does our stomach separate the properly digested food to pass on to the next stage and not send through the food we may have just eaten?	a couple of things to note: first, the mouth is there basically to mash stuff up. this increases the surface area of the food (to help digestion in the next step) and mixes it with saliva, which begins breaking down some of the really basic carbohydrates. if you put a saltine in your mouth and don't chew it up, you'll...	[ "Segmentation also occurs during and shortly after a meal within short lengths in segmented or random patterns along the intestine. This process is carried out by the longitudinal muscles relaxing while circular muscles contract at alternating sections thereby mixing the food. This mixing allows food and digestive ...
why does a limb hurt after the blood comes back when you sleep on it?	You're not cutting off blood flow when this happens. If that were the case your limb would turn purple and eventually die due to a lack of oxygen. Under normal operating conditions nerve endings are synchronized, firing off and receiving signals from the brain in unison. Nerve endings regularly fire off a "hey I'm her...	[ "Diseases such as peripheral vascular disease can also result in local hypoxia. For this reason, symptoms are worse when a limb is used. Pain may also be felt as a result of increased hydrogen ions leading to a decrease in blood pH (acidity) created as a result of anaerobic metabolism.\n", "Lameness is accompanie...
If Hitler wanted to create a Third Reich, what were the First and Second Reich? Was there a particular aspect of the previous Reichs he wanted to recreate?	The First Reich was the Holy Roman Empire (Heiliges Römisches Reich), and the Second Reich was the German Empire (Deutsches Reich, or the Kaiserreich). Mainly, he was seeking to emulate a strong, united, "German" Germany, that was able to forge her own destiny and become a powerful player in world affairs.	[ "The 1920 National Socialist Program stated as its first point, \"We demand the unification of all Germans in the Greater Germany on the basis of the people's right to self-determination.\" Hitler argued in a 1921 essay that the German Reich had had a single task of, \"incorporating the ten million German-Austrians...
In the HRE, why were some kingdoms, like Prussia or Austria, technically inside the empire, but had territory outside of it?	The Holy Roman Empire is not a standard Empire. It is more akin to a confederation of small German lands that are tied together in a confederation. While I can't talk about why or how it was formed, by the 18th century, Prussia and Austria (or rather the House of Hohenzollern and the House of Habsburg) gained lands thr...	[ "Before unification, German territory (excluding Austria and Switzerland) was made up of 27 constituent states. These states consisted of kingdoms, grand duchies, duchies, principalities, free Hanseatic cities and one imperial territory. The free cities had a republican form of government on the state level, even t...
why don’t locusts destroy entire forests / rainforests and take over the world?	They're usually solitary animals, but when the right mix of vegetation growth and heavy drought occurs their population peaks at the same moment that the availability of food plummets. When that happens, their behavior changes and they start to swarm in search of food. They tend to choose farmland since it's easy pic...	[ "Several species of Orthoptera are considered pests of crops and rangelands or seeking warmth in homes by humans. The two species of Orthoptera that cause the most damage are grasshoppers and locusts. Locust are historically known for wiping out fields of crops in a day. Locust have the ability to eat up to their o...
why do birds choose not to eat dead worms after it rains?	It is a simple matter of supply and demand; all the birds which would eat worms are already stuffed. You see worms on the ground and the birds are uninterested, but this doesn't mean they didn't eat any.	[ "These birds forage in soft mud, probing or picking up food by sight. They mainly eat insects and earthworms, and occasional plant material. They are difficult to see, being well camouflaged in their habitat. When flushed from cover, they fly straight for a considerable distance before dropping back into vegetation...
why are companies or products allowed to advertise themselves as #1 or the best.	What about when trailers say this is the number one movie in America before it even comes out?	[ "Benefits to a company of good brand recognition include speeding up new product acceptance, enabling market share penetration by advertising, and resisting price erosion. During the decision process for software buying, usually 95% of customers buy a brand that they were previously aware of, 90% buy a brand that t...
if central heating is a closed system, why do we only use water. aren't there better solutions with different thermal properties?	Water is used because it has excellent properties for use in heating systems and it's relatively inexpensive, plentiful, non-toxic and easy to handle. There are some substances with 'better' thermal properties but they're expensive, toxic, etc. Ammonia for example has a slightly higher specific heat capacity than wat...	[ "Where alternatives to electricity exist, hot-water central heating systems can use water heated in or close to the building using high-efficiency condensing boilers, biofuels, heat pumps or district heating. Ideally hot water heating should be used. This can be converted in the future to use other technologies suc...
when a seed is a seed, is there anything alive in it? how does it gain life?	A seed is alive, in the same way a human embryo is alive. The bulk of a seed (and the part we eat in some plants) is a starchy substance, meant to be broken down and used as fuel by the baby plant before it can get to sunlight. Compare that to the yolk sack in many animal eggs. There is a tiny plant embryo somewhere in...	[ "The seeds are dispersed short distances by wind, but can travel longer distances by water, animals, and people. The vast majority of seeds (95%) are found in the top of the soil within a few meters of the parent plant. Seeds may stay alive in the seed bank for more than five years.\n", "Seeds may be viable for h...
Are there any documented incidences of intentional mistranslation through interpreters which resulted hostile relations amongst nations or tribes?	Around Kenedy, Texas in 1901, a bad interpreter led to shoot out between Karnes sheriff W. T. "Brack" Morris and tenant farmer/vaquero [Gregorio Cortez](_URL_1_) who was falsely accused of stealing a horse. The shootout led to a famous statewide manhunt as Cortez elluded posses as he attempted to escape across the US/M...	[ "The Indian Removal Act and the Trail of Tears led to a major enumeration of Native Americans, and many controversies and misunderstandings about blood quantum that persist to this day. As they were being forcibly driven out of their ancestral homelands and subjected to genocide, many Natives understandably feared ...
we can freeze human sperm and eggs indefinitely, without "killing" them. why can't we do the same for whole people, or even just organs?	Because sperm and eggs are just single cells. Organs and organisms are collections of cells that must operate in unison or the entire organism dies. If you have 5 million sperm cells and your freezing/thawing process kills half of them, you still have 2.5 million viable sperm cells to rely on, and only need one for su...	[ "However, the freezing process is still somewhat damaging. Therefore, men wishing to donate sperm or have it stored for future use must make six sperm deposits for every one child they wish to have, due to the 50% survival rate of the sperm in each deposit. The sperm is then put into straw shaped vials, and placed ...
the pros and cons of higher education tenure of professors.	As a pro, professors are insulated against changes in administration that might scrap unprofitable or unpopular work. As a con, they might turn into senile alcoholics.	[ "Tenure-track professors in the United States are usually subject to an up-or-out system. Newly hired professors, most often with the rank of assistant professor, must impress their department with their accomplishments to be awarded tenure, usually but not always combined with promotion to associate professor. Tho...
why my microwave at 1500 watts, has trouble heating things evenly.	Something called constructive and destructive wave interference. A microwave uses waves of energy to excite the water in your food, which makes it warmer. However, a property of waves is that if two waves collide with each other when they are at the same maximum peak, they form a wave with a peak twice as big (twice ...	[ "Microwave ovens produce heat directly within the food, but despite the common misconception that microwaved food cooks from the inside out, 2.45 GHz microwaves can only penetrate approximately into most foods. The inside portions of thicker foods are mainly heated by heat conducted from the outer .\n", "At very ...
What exactly are the differences between Active ingredients and Inactive ingredients in medicine?	* Binders/Fillers(They aren't mutually exclusive): Sucrose, corn starch, and mineral oil * Ph Buffers: Calcium carbonate * Anti caking(during manufacturing): talc, and sodium polyphosphate(not sure) * Flavoring: natural and artificial flavor, and adipic acid * Coloring: red 40 lake, yellow 6 lake, yellow 5 (tartrazine...	[ "In contrast with the active ingredients, the inactive ingredients are usually called excipients in pharmaceutical contexts. The main excipient that serves as a medium for conveying the active ingredient is usually called the vehicle. Petrolatum and mineral oil are common vehicles.\n", "Therapeutically, modern dr...
What part of history do you find the least interesting?	Two classicists walking past the Modern History department, one turns to the other and scorns: "Pfft, Journalists"	[ "This book also contains more parodies of various recent cultural and historical events of the time. For example, there is one image of a bunny tying himself to Gollum, seeking the ring at the top of the hill, and also a bunny pouring pepper into Sauron's eye from \"The Lord of the Rings\", and an image of the , an...
Why does decoherence produce probabilistic outcomes?	Decoherence basically implies that the wavefunction splits into two (or more) parts, that are now so different (decoherent) that they will never ever interact again. If you look at it from the outside, it looks like the Universe is splitting into two parallel universes that differ only in where the particle (the shar...	[ "Quantum decoherence implies that irreversible macroscopic phenomena (hence, all classical measurements) render histories automatically consistent, which allows one to recover classical reasoning and \"common sense\" when applied to the outcomes of these measurements. More precise analysis of decoherence allows (in...
why is it that medical doctors can deal with a single species(humans),veterinary doctors are(assumed?)able to deal with every other species?	Most veterinary doctors don't deal with all species, you most often go to a different doctor for your snake than your horse. Also vets tend to not go nearly as in depth as human doctors. People will do a lot for their pets but there is a lot less options for animal medicine than human medicine. Like animal organ trans...	[ "Most veterinary physicians work in clinical settings, treating animals directly. These veterinarians may be involved in a general practice, treating animals of all types; they may be specialized in a specific group of animals such as companion animals, livestock, zoo animals or equines; or may specialize in a narr...
why does the sky feel bigger the closer you get to equator?	This is an odd question, the angle you can view of the sky is actually smallest at the equator and largest at the poles. However, because of the temperature, clouds are frequently higher in warmer climates, so maybe the clouds being higher makes you feel like the sky is larger?	[ "The larger the size of the sphere (the planet where an observer is located) the less curved the horizon is. William Jackson Humphreys' calculations showed that an observer could see all the way around a planet nearly six times larger in radius than the Earth, with the same atmosphere as the Earth, because of loomi...
What was the ultimate fate of all the lead in tetraethyl lead added to gasoline during most of the 20th century?	A lot of lead was rained out into the oceans which are slowly ingesting it. The primary delivery method is by rainfall and the atmosphere only carried the lead for a few days so most of it is in the northern hemisphere (where the sources were) and less in the southern hemisphere. I'm not sure how the budget of ocean...	[ "The 20th century saw an increase in worldwide lead exposure levels due to the increased widespread use of the metal. Beginning in the 1920s, lead was added to gasoline to improve its combustion; lead from this exhaust persists today in soil and dust in buildings. Blood lead levels worldwide have been declining sha...
Why can our immune systems get rid of some viruses, where others can stay in the body for the rest of our lives?	One thing you need to know about HIV. It is smarter than you. It identifies and gets inside your CD4+ T cells (and some other cells) without alerting the other cells, hijacks the inner mechanisms of the cell, forces the infected cell to make thousands of copies of the virus, all the while shutting down the natural buil...	[ "The body uses its immune system to protect itself from bacteria, viruses and other disease-causing beings, and when it fails to do so immunodeficiency diseases occur. One such disease is acquired immunodeficiency syndrome (AIDS) which is most commonly a result of an infection by the human immunodeficiency virus (H...
what is stopping us from capturing the co2 emitted from coal-burning power plants before it escapes into the atmosphere?	We can do it, or something like it anyway, called [Carbon Capture and Storage](_URL_0_). The main thing stopping us is that it costs money, and doesn't provide any profit to the people running the power plant, so they don't have a reason to do it.	[ "The current emphasis on removing CO from the flue gases emitted by fossil fuel power plants has led to much interest in using amines for removing CO. (See also: Carbon capture and storage and Conventional coal-fired power plant.)\n", "There are currently 200 cofiring plants in the world, including 40 in the US. ...
the new instagram tos and selling photos. can facebook use your photos now too?	Facebook can and has been selling users photos without their consent for a long time now. This policy is very profitable... And since Facebook bought instagram they are going to do the same thing.	[ "In 2015, after Facebook bought Instagram there was an option that Instagram could use its own users photos for ad purposes. This new policy was hidden in their user agreement. Users could opt out but the only way was to delete their account at before a certain deadline. Hiding this in their user agreement privacy ...
AskHistorians Podcast Episode 003 Discussion Thread - On Human Sacrifice in Mesoamerican Cultures	I did not like it. There is no added value IMHO if all you do is have someone with vastly inferior audio quality read prepared questions to you, and you reading the prepared answers of one of our flaired users. It's actually much nicer to just go here, read discussions, read follow-up questions/answers, and understa...	[ "In 1521, Spanish explorers such as Hernán Cortés conquered the Aztec capital of Tenochtitlan and made observations of and wrote reports about the practice of human sacrifice. Bernal Díaz del Castillo, who participated in the Cortés expedition, made frequent mention of human sacrifice in his memoir \"True History o...
Did Prescott Bushes Nazi connections help his son George H.W Bush advanced in the CIA? Were those Nazi connections ever brought up during either Bush campaign?	According to the Anti-Defamtion League the charges of Bush being a nazi sympathizer are "untenable and politically motivated." So those connections don't exist and even if they did I don't see how they would help his son advance in the CIA?	[ "The book observes that when George H.W. Bush was at Phillips Academy his roommate was the nephew of George de Mohrenschildt, and that in later years, Bush and De Mohrenschildt fraternized in Dallas. In 1962, de Mohrenschildt befriended Lee Harvey Oswald. Baker also makes a connection between the Bushes and the Wat...
why is there a stereotype of asians being smart?	Their culture tends to be quite strict and success-oriented. Currently in most parts of China, you are only allowed to have one child. This "One-child policy" was implemented in 1979. And while there are negative effects to this (like many female babies being discarded since males are "better"), it is a decent form of ...	[ "In modern times, Asians have been perceived as a \"model minority\". They are categorized as more educated and successful, and are stereotyped as intelligent and hard-working, but socially inept. Asians may experience expectations of natural intelligence and excellence from whites as well as other minorities. This...
How long could a person go without sleep, with only 3 or 4 meals a day?	> I'd imagine that most of your energy comes from food, and not sleep... The question isn't energy, it is mental maintenance. Something about the brain requires a period of relaxation from conscious thought. You might compare it to a busy office worker who accumulates documents without the ability to file them away ...	[ "Randy Gardner holds the scientifically documented record for the longest period of time a human being has intentionally gone without sleep not using stimulants of any kind. Gardner stayed awake for 264 hours (11 days), breaking the previous record of 260 hours held by Tom Rounds of Honolulu. LCDR John J. Ross of t...
reddit, fb, etc is filled with people complaining about common core. i feel like i am only getting one side of the story, as there must be people out there that believe in it and support it. common core supporters, what are the benefits and why are they not better understood?	I'm a teacher and I like the common core. AMA! Common Core very simply is just a set of Math and Language Arts standards that a lot of states have adopted. You can read them for yourself [here](_URL_0_). I like them more than my old state's standards because there are fewer of them. For instance, I used to have to ...	[ "Advancing one Catholic perspective, over one hundred college-level scholars signed a public letter criticizing the Common Core for diminishing the humanities in the educational curriculum: The \"Common Core adopts a bottom-line, pragmatic approach to education and the heart of its philosophy is, as far as we can s...
What was everyday life like for LGBT people in Colonial North America?	So I would like to address the quote and your second question first, and then I will move on to your other questions. First, technically yes, homosexuality could be punishable by death in British North America prior to America's gained independence. [The English Sodomy Act of 1533-34](_URL_0_) declared the sentence o...	[ "Despite societal prejudices, some LGBT people were able to live fairly open lives and still become successful, especially in the fields of literature and arts. Sor Juana Inés de la Cruz (1648–1695), considered the greatest lyric poet of the colonial period (1521–1821), was a Mexican nun presumed by many to be a le...
Could someone with myopia or hyperopia see clearly (in focus) underwater.	The [Moken](_URL_1_), so-called "sea gypsies" of Thailand have self trained to be able to focus their vision underwater. The reason most of us cannot focus underwater is the difference in the refractive index between the human lens and water is less than between air and ~~water~~ the lens, therefore less bending, an...	[ "People with amblyopia also have problems of binocular vision such as limited stereoscopic depth perception and usually have difficulty seeing the three-dimensional images in hidden stereoscopic displays such as autostereograms. Perception of depth, however, from monocular cues such as size, perspective, and motion...
The year is 50 BCE. I am a Roman merchant sailing through the Eastern Mediterranean trying to sell my wares. Would the Greek spoken in Alexandria, Antioch, Athens etc. be the same or would I need to know multiple language to engage in business?	They spoke a type of Greek known as 'Koine Greek'. Koine is a little different to creole or pidgin languages in a rather interesting way - wheras the creole that emerged from centers of migration was a result of the interaction of different languages, Koine was when different regions spoke a version of the same languag...	[ "During the 7th century BC, Greeks traders from Massalia (Marseille) traded throughout the coastal commercial centres of the region without establishing a permanent presence and later founded the trading cities of Emporion (Ampurias) and Rhode (Roses). Part of this Greek trade was transported by Phoenician ships. T...
I am not sure if this is the appropriate place for the question, but here goes. With the amount of information generated today - is there a concern about what future historians can tell about today's world?	First of all, "more information is generated today" is a highly subjective statement and one which - from my perspective anyway - ought to be greeted with considerable justified skepticism. :) I would, however, agree that a greater absolute volume of text is generated. Keep in mind that we have basically comprehensive...	[ "Big History seeks to retell the \"human story\" in light of scientific advances by such methods as radiocarbon dating, genetic analysis, thermodynamic measurements of \"free energy rate density\", along with a host of methods employed in archaeology, anthropology, and world history. David Christian of Macquarie Un...
During the civil wars of Marius to Augustus, how many legions were from Rome? Italy? The provinces?	All legions were from Italy. At least sort of. Only Roman citizens could serve in the legions, and Roman citizenship was not widespread in the provinces until well into the Principate. With very few exceptions legions were raised in Italy--indeed, consular and proconsular armies were always raised in Italy, although ad...	[ "Generals, during the recent Republican civil wars, had formed their own legions and numbered them as they wished. During this time, there was a high incidence of \"Gemina\" (twin) legions, where two legions were consolidated into a single organization (and was later made official and put under a legatus and six du...
Prevalence of bayonet wounds in European armies, pre American Civil War?	Can't find any peer-reviewed articles at the moment, but this is a breakdown of types of trauma that British military surgeons dealt with during the napoleonic wars, according to M.Crumplins ["Men of Steel: Surgery in the Napoleonic Wars "](_URL_0_): 62,0% : Musket-, Rifle-, Pistol Bullets 13,5% : Sword, Saber 8,0...	[ "During the American Civil War (1861–1865) the bayonet was found to be responsible for less than 1% of battlefield casualties, a hallmark of modern warfare. The use of bayonet charges to force the enemy to retreat was very successful in numerous small unit engagements at short range in the American Civil War, as mo...
how is the cable company making money?	The aside from premium networks, cable company pays pretty much the same costs no matter how many customers they have. It costs a million dollars to service a city whether there are 100 customers in that city or 100,000. So the more customers they have, the more profit they make, bundling allows them to have more cu...	[ "Presently, cable is provided to most cities and towns, depending on the region, by companies such as Rogers, Shaw, Vidéotron, Cogeco, Cable Axion, and EastLink. Most of these \"first-generation\" cable companies do not compete with each other, as the CRTC has traditionally licensed only one cable provider per mark...
What's up with Rosetta, the space probe that landed on the comet?	Rosetta didnt land on the comet. Rosetta orbits the comet. It was Philae who was on board of rosetta that landed on the comet. Philae's landing wasnt so smooth and batteries died due not receiving enough solar energy. Months later the comet got closer to the sun where philae was able to recharge its batteries and conti...	[ "\"Rosetta\" is a space probe designed to rendezvous with the comet 67P/Churyumov–Gerasimenko, perform flybys of two asteroids (2867 Šteins and 21 Lutetia), and carry lander \"Philae\" until its landing on 67P. This page records a detailed timeline of this mission.\n", "In August 2014, ESA probe \"Rosetta\" began...
Were flappers considered masculine by 1920's standards?	You definitely have the right idea. The roles of women were being challenged during WWI, working in industrial and professional jobs. Which, in a large part, led into the struggle during the 1920s of what was acceptable for women. While the extreme version of the flapper we tend to think of was well beyond what most wo...	[ "1926, there was an early association in the public mind between unconventional appearance, outrageous behavior, and the word \"flapper\". A report in \"The Times\" of a 1915 Christmas entertainment for troops stationed in France described a soldier in drag burlesquing feminine flirtatiousness while wearing \"short...
why does everything sometimes look yellow outside after a thunderstorm?	> > > Most thunderstorms occur in the late afternoon. By this time of day, the sun is beginning to set. The orange hue is caused by the same process that causes the vivid colors at sunsets. Shorter wavelengths of light (blue) are scattered quickly, leaving only the yellow-orange-red end of the spectrum. _URL_0_	[ "Just prior to the tornado touching down eyewitness accounts recalled that an approaching thunderstorm with several intense lightning strikes turned the northwest sky a dark “black-yellow-green” color. The US Weather Bureau (predecessor of today's National Weather Service) observations that evening recorded a tempe...
Was the crucifixion of Jesus as told in the New Testament more extreme then a normal Roman execution of the day?	It is hard to say, really. We don't really have that much information on how crucifixions would actually be carried out, as the only detailed sources are passion pieces, which are flawed as history. It is probable that crucifixion was actually just one term for a whole range of execution methods, such as impalement, th...	[ "In the three synoptic gospels, various supernatural events accompany the crucifixion, including darkness of the sky, an earthquake, and (in Matthew) the resurrection of saints. The tearing of the temple veil, upon the death of Jesus, is referenced in the synoptic. The Roman soldiers did not break Jesus' legs, as t...
After Columbus' first voyage to the New World, why did the Spanish crown allow other countries to find out about his discoveries? Was there any attempt to keep the existence of a new continent (or "India" anyway) to the West a secret?	/u/Lynx_Rufus That would have been very difficult, considering Columbus [had to stop in Lisbon on his return voyage due to bad weather](_URL_0_).	[ "The third expedition by Columbus in 1498 was the beginning of the first successful Castilian (Spanish) colonization in the West Indies, on the island of Hispaniola. Despite growing doubts, Columbus refused to accept that he had not reached the Indies. During the voyage he discovered the mouth of the Orinoco River ...
Is all geometry locally Euclidean?	Objects that can be represented as Euclidian if you zoom in far enough are called manifolds. The surface of a sphere, like the Earth (I believe) is a manifold. However there are geometries that can not be approximated as Euclidean on arbitrarily small scales. For example, the singularity of a black hole. At the singul...	[ "In geometry, Euclidean space encompasses the two-dimensional Euclidean plane, the three-dimensional space of Euclidean geometry, and similar spaces of higher dimension. It is named after the Ancient Greek mathematician Euclid of Alexandria. The term \"Euclidean\" distinguishes these spaces from other types of spac...
Would Earth be able to maintain its orbit if the planets closer to the sun and further from the sun disappeared?	Yes. It would do so even better without Jupiter's perturbation.	[ "The Solar System is stable in human terms, and far beyond, given that it is unlikely any of the planets will collide with each other or be ejected from the system in the next few billion years, and the Earth's orbit will be relatively stable.\n", "As the Sun dies, its gravitational pull on the orbiting bodies su...

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