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train · 226k rows

question stringlengths 3 301	answer stringlengths 9 26.1k	context list
Were gas mask in World War 1 effective?	Up to a point they were yes. They required constant adaptation though as one type of filter was generally effective against one type of gas. For example the first gas attacks were using dichlore (nicknamed "Bertholite") a type of chlorine gas which were very soon countered by soldiers by pissing on some fabric and pu...	[ "Earlier versions of the gas mask prior to 1915s development of the small box respirator were crude and ineffective as no troops had yet been experienced poison warfare; even the idea of it from troops, was far-fetched. One of the first gas masks seen on the battlefields of the early world war was the British Hypo ...
How much do we use satellites?	All the time. While you may not directly use satellites for much of anything, pretty much everything is reliant on satellites in some method or another. Oddly enough, even some types of ATMs rely on satellites.	[ "As of 2013, there are 950 satellites of all types in Earth orbit. It is not possible to identify the exact number of these that are military satellites partly due to secrecy and partly due to dual purpose missions such as GPS satellites that serve both civilian and military purposes. As of December 2018 there are ...
if double jeopardy doesn't allow a person to be tried twice for the same crime even if there is new evidence, why are appeals allowed?	They aren't the same thing. Appeals are requests that a higher court take a look at the trial to make sure that everything was conducted properly and that the decision was correct. It isn't a new trial per se... so much as a continuation.	[ "Finally, the Court had held in \"Forman v. United States\" that a new trial following a reversal—no matter the ground—never constitutes double jeopardy: \"It is elementary in our law that a person can be tried a second time for an offense when his prior conviction for that same offense has been set aside by his ap...
If Earth spun a lot faster would we appear to be aging slower from the view of our satellites?	We already are. If a clock at sea level records twenty-four hours, a clock aboard a satellite in low Earth orbit records twenty-four hours minus about forty microseconds.	[ "This scenario is unique because it doesn't happen overnight, but rather over a given period of time: The Earth revolves at 1,000 miles an hour, but is gradually slowing down, yet this slowing is too slow to be noticed on human timescales. But what if it significantly slowed and eventually stopped? (The reason for ...
what makes music sound good? what causes it to release dopamine in the brain?	Others have attempted to answer your question regarding the biological processes by which music is interpreted by the brain as music rather than just a collection of repetitive sounds. But I don't see anyone taking a stab at explaining why certain sounds are "pleasant" or "unpleasant." It turns out that there is a f...	[ "Neuroplasticity allows the brain to grow and change, especially in the auditory and motor cortex. Listening and playing music helps both of these areas of the brain to develop more, which was found to be correlated to having an improves auditory imagery in many performers in a study conducted at Utrecht University...
why is it that a wet tissue or piece of cardboard or paper tear more easily? how does water affect the structural integrity of paper products?	Paper products are made from wood fibers that are basically matted together in random orientations like felt. As the paper dries, little hairs and random kinks in the fibers cause them to link up like tangled hair. Pressing/rolling operations enhance this effect. Paper fiber is very hydrophilic, meaning it can soak up...	[ "Direct water contact and excessive moisture in the environment can cause structural problems for parchment including: expansion of object; discoloration; alteration of surface coatings; gelatinization of skin; and realignment of fibers. \n", "Wet-strength additives ensure that paper retains its strength when it ...
what is the difference between analog and digital film.	It's essentially a matter of preference. Traditional photochemical film is widely regarded as having a more 'cinematic look' to it, due in part to the grain present on the image. While many directors and cinematographers have an affinity for film, such as Tarantino and Nolan, due to the high production costs and inconv...	[ "Digital cinema refers to the use of digital technology to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the ...
what is it in insecticide that causes houseflies to start spazzing out and moving uncontrollably?	Many insecticides work like a nerve gas in that they interfere with the electrical impulses that fire between nerve cells. This causes them to fire sporadically, which causes a whole host of issues that eventually lead to death.	[ "Pyrethrin is most commonly used as an insecticide and has been used for this purpose since the 1900s. In the 1800s, it was known as \"Persian powder\", \"Persian pellitory\", and \"zacherlin\". Pyrethrins delay the closure of voltage-gated sodium channels in the nerve cells of insects, resulting in repeated and ex...
How did we figure both the distance to the Sun, and the size of the Sun?	You are right that it is much easier to work out things relatively rather than absolutely when it comes to astronomy. Kepler's laws for planetary motion were well established by the middle of the 17th century. In particular the third law (that P^2 / a^3 is constant for all planets) means that we know the relative size...	[ "He attempted to measure the distance and size of the Sun. In about 90 BCE, Posidonius estimated the distance from the Earth to the Sun (see astronomical unit) to be 9,893 times the Earth's radius. This was still too small by half. In measuring the size of the Sun, however, he reached a figure larger and more accur...
why does doing something you love to do seem to make time go by faster?	You know the saying “a watched pot never boils”? When you’re doing something you don’t like you’re constantly looking at the clock. Say you work a dead end job at KFC and it’s dead af. You’re constantly looking at the clock to see if it’s time to clock out yet. Time flies when you’re having fun because you’re not activ...	[ "\"It's weird because you don't whilst you're doing it. You don't realise how much you're enjoying yourself sometimes. I really try and stop myself in my tracks now and say 'look what you've achieved, look what you've just done, look what you're doing'. I really try and do that, because if you don't, you're always ...
how is road data collected and stored?	A GPS device has a "GPS" part that listens to radio signals from satellites and triangulates the position of the car, and a map. Yes, the maps require some memory, but it's not too bad; unlike photos, maps are only a few colors, and so use up less memory. You can keep thousands of photos on a small flash drive; kee...	[ "Floating car data (FCD), also known as floating cellular data, is a method to determine the traffic speed on the road network. It is based on the collection of localization data, speed, direction of travel and time information from mobile phones in vehicles that are being driven. These data are the essential sourc...
why is there so much backlash against iggy azalea in the hip-hop community, but not against other white rappers?	Because she doesn't make good music, and she's made it to the mainstream music's Eye.	[ "The African-American hip hop artist Azealia Banks has criticized white rapper Iggy Azalea \"..for failing to comment on \"black issues\" despite capitalising on the appropriation of African American culture in her music.\" Banks has called Azalea a \"wigger\" and there have been \"...accusations of racism against ...
How powerful was the Ku Klux Klan in 1946?	Founded in 1915 by William J. Simmons, the Second Klan found mass appeal nationwide, with more chapters in the North than in the south, appealing to a larger white membership base than the first klan had. In both the south and the north the klan was a secret, vigilant organization modeled on other, similar, groups like...	[ "The Second Ku Klux Klan, which was formed in 1915, combined Protestant fundamentalism and moralism with right-wing extremism. Its major support came from the urban south, the midwest and the Pacific Coast. While the Klan initially drew upper middle class support, its bigotry and violence alienated these members an...
Could a vaccine for a disease actually be created by studying a person who is immune?	Studying survivors helps determine what mechanism may be used to make preventatives or treatments for diseases. For example, a very small number of people are [naturally resistant to HIV infection](_URL_0_). Their resistance can help scientists understand both the mechanisms of infection and could lead to treatment or ...	[ "Unlike traditional vaccines, in which attenuated or killed virus/bacteria is used to generate an immune response, viral immunotherapy uses genetically engineered viruses to present a specific antigen to the immune system. That antigen could be from any species of virus/bacteria or even human disease antigens, for ...
why do some animals, like cows, horses, goats, etc., seem to have no preference where they defecate, while others, like dogs or cats, seem to be much more fastidious about their habits?	Cows, horses, goats, etc are naturally herd animals that roam a large range. They are prey animals that rely on speed to escape predators or number for defense. Cats and Dogs are predators that have much smaller ranges, and therefore need to limit some of the signs they are present in order to hide and catch their pr...	[ "For example, some animals will avoid anything that has the odor of the urine of predators. Tiger urine is thus very effective at keeping away animals. Coyote urine has gained currency as a deer repellent. Fox urine is used to repel rabbits, groundhogs, woodchucks, squirrels and chipmunks. Bobcat urine repels moles...
how do helicopters with no tail helix work?	From Wikipedia, > NOTAR is the name of a helicopter anti-torque system which replaces the use of a tail rotor. Developed by McDonnell Douglas Helicopter Systems (through their acquisition of Hughes Helicopters), the name is an acronym derived from the phrase no tail rotor. The system uses a fan inside the tailbo...	[ "The tail rotor is powered by the helicopter's main power plant, and rotates at a speed proportional to that of the main rotor. In both piston and turbine powered helicopters, the main rotor and the tail rotor are mechanically connected through a freewheeling clutch system, which allows the rotors to keep turning i...
what happens if an undocumented/illegal immigrant/visa overstayer refuses to tell the police/immigration department where they are from?	Once they ran your finger prints you'd be deported with either a ten year or lifetime travel ban to the US. If you didn't say a word and your fingerprints came back inconclusive you'd be incarcerated until they could verify your identity. And they'd be pissed.	[ "Often, undocumented aliens or individuals lacking legal permission to enter, or remain, in the United States, when apprehended at the U.S. border are detained and placed in removal proceedings in front of an immigration judge. These individuals may include refugees seeking asylum. Under Section 235(b)(2) of the Im...
Have historians ever advised governments?	I can certainly think of a few examples, though perhaps not of the nature that you're hinting at. A significant number of British politicians studied history at university - Gordon Brown (the previous PM), John Prescott, David Blunkett and Alex Salmond are all qualified historians at an undergraduate level. Tristram Hu...	[ "In the decades immediately following the Second World War, most historical opinion was critical of the governments of the period. Certain historians, such as Robert Skidelsky in his \"Politicians and the Slump\", compared the orthodox policies of the Labour and National governments unfavourably with the more radic...
Why couldn't the Russians win the Russo-Japanese war against Japan?	I think the first question you have to ask is why do you think Russia should have won? Russia lost the war mainly because of the attitude the question has inherent in it, how could a European Great Power lose to an Asiatic island country? There was a huge amount of arrogance in the Russian Empire and the leadership...	[ "Russia suffered multiple defeats by Japan, but Tsar Nicholas II was convinced that Russia would win and chose to remain engaged in the war; at first, to await the outcomes of certain naval battles, and later to preserve the dignity of Russia by averting a \"humiliating peace\". Russia ignored Japan's willingness e...
why do we experience emotions that we consciously recognize as illogical or ridiculous?	Think of it this way. Our body has pain receptors that cause a feeling that 90% of humans hate and can't stand. Pain. They do this so that we realize we need to stop doing something that causes our bodies injury. A defense mechanism, if you will. Our brains eventually become conditioned to avoid things that cause pain ...	[ "Humans' subjective experience is that emotions are clearly recognizable in ourselves and others. This apparent ease of recognition has led to the identification of a number of emotions that are said to be basic, and universal among all people. However, a debate among experts has questioned this understanding of wh...
why do we need to change our tooth brush every 3 months?	This [video from the Applied Science channel on YouTube](_URL_0_) is a little beyond an ELI5 explanation, but the visuals are very easy to understand. Basically, as you brush your teeth, the abrasives in the toothpaste wear away the roughness on the bristles of the brush, making it less effective at removing food par...	[ "The effectiveness of an electric toothbrush depends not only on its type of action and on correct use, but also on the condition of the brush head. Most manufacturers recommend that heads be changed every three to six months at minimum, or as soon as the brush head has visibly deteriorated.\n", "BULLET::::- Bent...
what ever happend to "kony 2012"?	Well, a few of the leading guys who set it up had mental breakdowns so that sort of kaiboshed the whole endeavour. It also became pretty clear to anyone who cared to check that Kony was long past the point of relevancy and had essentially been on the run for years.	[ "\"Kony 2012\", a short film released on March 5, 2012. The film's purpose was to promote the charity's \"Stop Kony\" movement to make African cult and militia leader, indicted war criminal and the International Criminal Court fugitive Joseph Kony globally known in order to have him arrested by the end of 2012, whe...
is there a difference between ejaculating, and having an orgasm?	Males (and females too, but using males since OP is talking about males) can have an orgasm and not ejaculate and ejaculate and not have an orgasm. They just commonly happen together. Yes, sex would get the same result. Often, the same effect is more easily achieved with masturbation since you don't need a partner for...	[ "Ejaculation is the ejecting of semen from the penis, and is usually accompanied by orgasm. A series of muscular contractions delivers semen, containing male gametes known as sperm cells or spermatozoa, from the penis. It is usually the result of sexual stimulation, which may include prostate stimulation. Rarely, i...
Why is it so expensive to install personalized/residential solar panels? (I mean--How hard could it be?)	It isn't particularly difficult or expensive to install your own solar power system. For instance, [Home Depot](_URL_0_) sells packaged solar power systems with everything you need except the mounting equipment. All you would need to do is figure out how to mount everything and have an electrician wire it up to your pa...	[ "Another criticism of installing solar panels is their upfront cost. According to energyinfomative.org, the average cost for a residential solar system is between $15,000 and $40,000 (USD), and about $7 per watt. In the article, it says that at today's rates, it would take 10 years to pay off an average system. As ...
why do many animes have such nonsensical titles?	Is it possible that you are referring to the fact that their titles are often in Japanese? In other cases, the title is a direct translation of something that has a proverbial/metaphorical meaning to the Japanese, but not to the English.	[ "Animation such as \"Oban Star-Racers\" and \"Code Lyoko\", like \"Avatar: The Last Airbender\", are examples over which some critics and fans debate about the term anime and whether it is defined as a \"style\" rather than as a national product, which leaves open the possibility of anime being produced in other co...
What was the best army in the world during the 1770s and why where they the best?	I think you'll find that among historians terms like "best fighting force" don't typically have much in the way of concrete meaning. If someone in 1838 had asked if the British were a "better fighting force" than Afghan tribal fighters I think most people would have agreed. They had better training, better equipment, b...	[ "According to historian Alexander Mikaberidze, the French army remained the finest army of its day by a good margin. The fusion of the legacy of the Ancien Régime with the formations of the French revolution and Napoleon's reforms had transformed it into a military machine that had dominated Europe since 1805. Each...
Does a perfectly black object exists ?	Absorbing all wavelengths is not the same as being black. Some of the objects that work best as approximations of black bodies (which means an object that absorbs all radiation and emits in a Planck spectrum) are actually quite hot, like molten metal and dense plasma.	[ "In astronomy, objects such as stars are frequently regarded as black bodies, though this is often a poor approximation. An almost perfect black-body spectrum is exhibited by the cosmic microwave background radiation. Hawking radiation is the hypothetical black-body radiation emitted by black holes, at a temperatur...
why do good questions and topics get downvoted?	The first 1-3 votes on any post is extremely important. If a topic is down voted people are more likely to see it as negative regardless of the content. There was a scandal on reddit awhile ago where one of the meme generator sites was giving like 2-6 votes on any meme's generated using that site, those 2-6 votes were...	[ "BULLET::::- Upvote/Downvote: Users can rank answers based on how relevant or helpful they found the answers to be. This feature is intended to help maintain the quality of content posted online. The more upvotes an answer receives, the higher it is ranked, and it shows up on top of the searches related to the ques...
why politicians are treated with such pomp if they're supposed to be public servants.	Formally - as the politicians themselves or various political scientists would tell us - it's because it's not the politicians receiving honours but the office they represent. An ambassador is a representative of the government which is the representative of the people. A good analogy is the customary standing ovation...	[ "Public servants can engage in political activities such as supporting a candidate in an election or taking leave without pay to run in an election, but they have to maintain their political impartiality as public servants. In order to comply with the non-partisanship values in the Act, public servants must only do...
Was Judaism present in Palestine prior to the end of the "Babylonian Captivity" or did it arise in Mesopotamia before being introduced by the returning descendants of the original deportees?	In short, yes. The Babylonian exile did not encompass all the Jews in Judea. From Stern, Ephraim (November–December 2000). "The Babylonian Gap". Biblical Archaeology Review. 26. "From 604 BCE to 538 BCE —there is a complete gap in evidence suggesting occupation. ... I do not mean to imply that the country was uninha...	[ "The Jewish exiles in Babylon were not slaves or prisoners, nor were they badly treated, and when the Persians gave permission for them to return to Jerusalem the majority elected to remain where they were. They and their descendants formed the diaspora, a large community of Jews living outside Judea, and the 1st c...
How corrupt was the railroad industry in the wild west days?	The railroad industry in the nineteenth century was unregulated and widely despised by the farmers that had to deal with them. The loyal order of Husbandry, better known as the Grange, was a collective movement by farmers and ranchers to bring the railroad industry under some sort of regulation. Early attempts at the s...	[ "The arrival of the railroad on July 4, 1879 brought with it businesses, development and new residents, both respectable and dubious. Murderers, robbers, thieves, gamblers, gunmen, swindlers, vagrants, and tramps poured in, transforming the eastern side of the settlement into a virtually lawless brawl. Among the no...
what use are coaches of top tier athletes like federer or tiger woods?	You don't always need to be better than someone (do you think Coach K at Duke can beat any of his players 1 on 1) at a sport to coach them, you observe them to see flaws in their game (amateurs watching TV--especially with slow motion replays can usually spot areas that require improvement). Also, a coach can focus ...	[ "Raonic has had fourteen coaches. Of these, eleven played professional tennis before coaching (Guillaume Marx, Frédéric Niemeyer, Galo Blanco, Ivan Ljubičić, Carlos Moyá, John McEnroe, Richard Krajicek, Mark Knowles, Dušan Vemić Goran Ivanišević and Fabrice Santoro)while three are career coaches (Casey Curtis, Ricc...
Did the Romans actually have naval battles in amphitheaters (naumachia) and, if so, how did they look like and how did they succeed in flooding the whole Colosseum (or other amphitheaters)?	Hi there, this is a previous thread with an answer from /u/searocksandtrees that includes some links about the Colosseum. This is not to discourage further comment -- we need more info on this -- but it may get you started. _URL_0_	[ "It appears it would have been difficult to flood the amphitheatre, but, because few records survive on the operation of the Colosseum, it is impossible to say for certain where the naval battles took place. Suetonius writes that Titus' brother and successor, Domitian, staged sea-fights in the amphitheatre, but he ...
How (by natural processes) are nutrients added and changes made in an area of soil over time to make it fertile?	This highly depends on the geology of the area. One example is coral atolls. In tropical, but shallow seas, coral reefs build up and up until they break the surface to create a small baren island. Seafaring birds tend to be the first visitors. The birds eat fish and leave deposits on the island. Some times their feces...	[ "As potential sources of nutrients, only C (via photosynthesis) and N (from biological fixation) can be produced \"in situ\". All the other elements (P, K, Ca, Mg, etc.) must be present in the soil. In Amazonia, the provisioning of nutrients from the decomposition of naturally available organic matter fails as the ...
What is the oldest youth subculture like punk, ska, hipster, sukeban, ganguro and do all eras have examples of them?	'Subcultures' are a relatively modern phenomenon, at least the extreme proliferation of them is. Most people until fairly recently haven't had the economic resources to have too many clothes at all, or leisure clothes that exist for solely fashionable reasons. That said, youth have been influenced by social and fashi...	[ "Youth of Today is an American hardcore punk band, initially active from 1985 to 1990 before reforming in 2010. The band played a major role in establishing the \"Youth Crew\" subculture of hardcore, both espousing and evolving the philosophies of the straight edge and vegetarian lifestyles.\n", "Youth music genr...
the stock market, investing, and whatever the "dow jones" is.	The stock market allows you to buy small pieces of public companies. Small portions of companies, called shares, are sold to markets in what is called an 'initial public offering' in order to raise money for the company to expand and fund its operations. Sometimes companies also sell additional shares to the markets ...	[ "The Dow Jones Industrial Average (DJIA), or simply the Dow (), is a stock market index that indicates the value of 30 large, publicly owned companies based in the United States, and how they have traded in the stock market during various periods of time.\n", "Dow Futures are financial futures which allow an inve...
Why is the sky overwhelmingly orange in the south of England during the severe storm in Ireland?	As I answer this, your question is 15 hours old, so you may have found out by now that it's [dust from the Sahara](_URL_0_). Ophelia spent a lot of time out in the Atlantic, and generated a long entrainment of dust-laden air from Northwestern Africa. We get this kind of phenomenon in Texas occasionally, if there's a d...	[ "The eruption of Tambora caused Hungary to experience brown snow. Italy's northern and north-central region experienced something similar, with red snow falling throughout the year. The cause of this is believed to have been volcanic ash in the atmosphere.\n", "In Ireland snow began to fall in the east of the cou...
why would the u.s. want to spy on germany?	First, you need to understand three things. 1) Allies still compete on the global stage. They compete for resources globally, they negotiate treaties in an adversarial manner (that's how negotiations work) and alliances wavier and change. Allies also have competing alliances. Germany v. North Korea? Sure. Germany ...	[ "However, propaganda experts at the time and historians since have argued the main goal of these and similar posters was to actually frighten people into not spreading rumors – or truths – containing bad news that might hurt morale or create tension between groups of Americans, since the FBI (in charge of dealing w...
Why are super computers used to model decay of nuclear weapons? and what kind of calculations do they perform?	Just to kind of give you an idea of how complicated calculations are for nuclear reactions, I'm going to give a plug to /u/NuclearEngineer's reddit university lecture #2. [here](_URL_0_). If you go to the bottom of the lecture, you'll see that you need to calculate up to 10^18 meshes just to get a single point in time...	[ "After the United States' 1992 moratorium on live nuclear testing, the Stockpile Stewardship Program was created in order to find a way to test, and maintain the nuclear stockpile. In response, the National Nuclear Security Administration began to simulate the nuclear warheads using supercomputers. As the stockpile...
how do meterologistists calculate wind chill	It's a formula. In the US, the formula that is used is: Wind Chill = 35.74 + 0.6215T - 35.75V^0.16 + 0.4275TV^0.16 Where V is in the wind speed in miles per hour, and T is the temperature in degrees Fahrenheit. Windchill temperature is defined only for temperatures at or below 10 °C (50 °F) and wind speeds above 4.8...	[ "In November 2001, Canada, the United States, and the United Kingdom implemented a new wind chill index developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG/TI). It is determined by iterating a model of skin temperature under various wind speeds and temperatures using s...
How much of an annoyance did British Commandos and other special operations cause the Germans in WWII?	Some raids had a major strategic impact: the raid on [Saint-Nazaire](_URL_1_), for example, put an important drydock on the French Atlantic coast out of action. Others were more regional in their impact, like the attack on the [Glomfjord power plant](_URL_5_) in Norway. Others were pure showpieces, like the disastrous ...	[ "During the Second World War, the British set up the Combined Operations Headquarters to organise harassing raids against the Germans in Europe. The first operation conducted by a \"commando\" formation, known as Operation Ambassador, took place in July 1940, but it was a small-scale operation that resulted in negl...
Does the human sinus cavity hold pressure?	Hi there. All paranasal sinus cavities are continuous with the outside world [(via ostia)](_URL_1_) and should not hold pressure unless in a pathological state (sinus infection, tumor growth, sinusitus, etc). Animals also have paranasal sinuses, and in some species they are very large and elaborate. [This picture](_UR...	[ "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...
Before knowing DNA's role in the cell, how did we think traits were passed on to the next generation?	People have always known that when two creatures mate, they produce children that look somewhat like a blend of both, but sometimes with occasionally big changes (they called these "sports"). This "blending" heredity was the "folk" heredity for most of human history. In the late 19th century, scientists/natural philos...	[ "To answer this, he made two basic assumptions: (i) before a self-replicating cell could come into existence, DNA molecules were synthesized in the primordial soup by random addition of the 4 nucleotides without the help of templates and (ii) the nucleotide sequences that code for proteins were selected from these ...
what does a complex root represent?	I can explain like you're 15... If we take a quadratic function like > [y = x^2 - 4](_URL_1_) To find the "roots" we set y=0 and solve the equation. In this case we get x^2 = 4 or x = ±2 You can plainly see that the function crosses the x axis at +2 and -2 However, for > [y = x^2 + 4](_URL_0_) The graph never c...	[ "When a cubic equation has three real roots, the formulas expressing these roots in terms of radicals involve complex numbers. It has been proved that when none of the three real roots is rational—the \"casus irreducibilis\"— one cannot express the roots in terms of real radicals. Nevertheless, purely real expressi...
if i wore my +2 reading glasses long enough for regular distance viewing, would my eyes eventually adapt to 20/20 with them on?	The upside down glasses is more of a brain processing task. Eventually your brain will figure out the information and flip it. How objects focus depends on the physical structure of your eye. Your eyes are only slightly physically adjustable when you are young. This is actually a pressing problem for the younger gener...	[ "Bi-focal spectacles and tri-focal eyeglasses are commonly ground to provide refractory correction ideal for reading, that is, 12 to 24 inches (30 to 60 cm), when the wearer is looking downward through them. These glasses, used for reading, are therefore not ideal for safe walking, where correction for 4½ to 5 feet...
why disney and comcast are attempting to purchase major parts of 21st century fox, and why murdoch family has no problem with handing off its valuable entertainment assets away?	They would never "hand away" valuable assets. They want to sell them for a gigantic fortune. Good deal!	[ "Several Fox investors said they would be open to terminate the company's agreement with Disney if Comcast followed through on its plan to launch a rival all-cash bid for $60 billion. Murdoch's family trust controlled 39% of Fox due to shares it held with special voting rights. However, under the company's by-law, ...
Do prison inmates have higher than average levels of testosterone?	Are you asking if testosterone and criminal behavior/aggression are linked? Then the answer is [not really](_URL_0_). The scientist and writer Robert Sapolsky wrote a great essay called "The Trouble with Testosterone" which covers this exact question. He cites a number of studies that showed that testosterone doesn't...	[ "Studies have also found that women in prison score significantly lower on psychopathy than men, with one study reporting only 11 percent of violent females in prison met the psychopathy criteria in comparison to 31 percent of violent males. Other studies have also pointed out that high psychopathic females are rar...
Did ancient cultures name their dogs/cats? if so, what were some common/stereotypical names?	Of course they named their animals! The Roman poet Ovid re-tells the story of Diana and Actaeon in his epic Metamorphoses (III.206-252), in which the hunter Actaeon accidentally gets a peep at Diana while she is bathing. Mortals can't see a goddess nekked without consequences, and so Diana makes Actaeon's own hunti...	[ "Adrian Frankllin, senior lecturer of the School of Sociology and Social Work at the University of Tasmania and author of \"Animals and Modern Cultures\", told the \"Sunday Tasmanian\" in 2001: \"In the 1950s and '60s dogs and cats were given 'dog' and 'cat' names. [...] Cats had names like 'Blackie' and 'Spotty', ...
High Alemannic (Swiss German) is not very easy for Standard German speakers to understand. Did the Swiss ever perceive themselves as having their own "language", distinct from German?	Follow up question. There were and still are French and Italian dialects in Switzerland. However, French and Italian cantons largely switched to standard versions of those languages with some differences and abandoned the dialects in every day speech. How come this did not happen to German cantons?	[ "Linguistically, Swiss German forms no unity. The linguistic division of Alemannic is rather into Low, High and Highest Alemannic, varieties all of which are spoken both inside and outside Switzerland. The only exception within German-speaking Switzerland is the municipality of Samnaun where a Bavarian dialect is s...
Why is the color green so often used to picture poison?	Hmm, I'd never thought about this before, but the obvious connection is with Paris Green, or an earlier similar compound, Scheele's Green These days it's possible to simply buy a bunch of paints in different colors from an art store, and though some are listed as "permanent" and some "impermanent", most of them can b...	[ "Like other common colors, green has several completely opposite associations. While it is the color most associated by Europeans and Americans with good health, it is also the color most often associated with toxicity and poison. There was a solid foundation for this association; in the nineteenth century several ...
what exactly are "means of production"?	Facilities, machines, tools, resources, capital etc. The means of production is everything you need to produce stuff that isn't humans, more or less.	[ "BULLET::::- Means of production: the means of production are a combination of the means of labor and the subject of labor used by workers to make products. The means of labor include machines, tools, equipment, infrastructure and \"all those things with the aid of which man acts upon the subject of labor, and tran...
Why are some animal droppings always in such uniform shapes and sizes?	In the colon there are band-like structures called taenia and out-pouchings of the colon called haustra. There are varying numbers of taenia along the length of the bowel and also between species. As liquid is absorbed from the colon the faeces begins to take shape and the number and size of the taenia and haustra have...	[ "The animal's small size is reflected in its food choices. Due to its smaller mouth, body anatomy, and masseter muscle, it tends to concentrate on food items up to 3 cm in diameter, while larger species eat items up to 6 cm in diameter.\n", "BULLET::::- Placozoa, small, flattened, multicellular animals around 1 m...
Quantaum teleportation and how it works?	> I got out of it is that an object from one place can be broken down to particles and teleport to another place where the particles will be put back together. That doesn't sound right to me. Let me try to explain the textbook quantum teleportation technique (the actual experiments probably differ from this). First...	[ "In quantum teleportation, a sender wishes to transmit an arbitrary quantum state of a particle to a possibly distant receiver. Quantum teleportation is able to achieve faithful transmission of quantum information by substituting classical communication and prior entanglement for a direct quantum channel. Using tel...
what are the implications of a company trademarking common words?	If you make an app game, you can't have a title of the game be similar to Candy Crush Saga. I believe they trademarked they phraise and not the words.	[ "A trademark is a word, phrase, or logo that identifies the source of goods or services. Trademark law protects a business' commercial identity or brand by discouraging other businesses from adopting a name or logo that is \"confusingly similar\" to an existing trademark. The goal is to allow consumers to easily id...
why do t-shirts get those tiny little holes in the bottom?	Does your boyfriend wear a belt with a buckle, or jeans with a steel button? The hole in the bottom of his shirt is probably caused from rubbing against one of those.	[ "BULLET::::- Crazy Quilt - All the designs on the T-shirts are cut out randomly. After the block are cut, they are then glued to one piece of fabric or bed sheet. The blocks are then zigzagged down. Potential issues: part of a graphic may be covered up by another overlapping graphic and if they aren’t done right th...
In the Antebellum American South, what would happen if a white woman gave birth to a mixed race child? In particular, what would happen to that child?	u/georgy_k_zhukov answers this in part in [this comment]( _URL_0_ef9gdqk) to the [related thread](_URL_0_) about white male - slave female sexual relations.	[ "The great majority of families of free people of color recorded in the US census in the Upper South in the first two decades after the Revolutionary War have been found to have descended from unions between white women (indentured servants or free) and black men (whether indentured servants, slave or free) in colo...
why didn't humans in the new world speciate?	They probably would have, given enough time. But they were only separate for 20,000 years. It would take much more time than that for the groups to become incapable of carrying each other's children.	[ "During the 16th and 17th centuries, some \"conversos\" migrated to the Americas, often the Castilian territories of the Viceroyalties of New Spain (North and Central America) and Peru (South America and Colombia). Legal emigration to the New World was strictly controlled and required proof of three generations of ...
how were private citizens and companies able financially support themselves and rebuild after the destruction of ww2?	Heavy investments of national banks, The US. Marshall plan. Nationwide recovery plans. Countries had to be rebuild, roads, houses and factories. This means that there was enough work to be done, there were workers enough, just money was required, and countries back then could print their own money.	[ "Since government borrowing to pay for the war had attracted a majority of private capital, little capital was available for corporations to borrow; the War Finance Corporation was designed to make such capital available. After the armistice in late 1918, the Corporation assisted in the transition to peacetime by f...
Since children are growing and constantly have dividing cells, why do they have lower cancer rates than adults (who are not growing)?	Cancer develops when cells malfunction, and when the malfunction is not handled by the immune system. Cells can malfunction for three reasons: cell was faulty to start with (genetics), cell was exposed to something that causes malfunction (a carcinogen), or cell randomly malfunctions. Of those three reasons, genetic...	[ "Rates of some cancers such as lung cancer and melanoma decreased among adolescents and young adults in the United States during this period. One hypothesis for this decline is the launching of prevention campaigns, such as smoking prevention and skin cancer awareness. Cervical cancer also declined among adolescent...
why semen smells like the pool	The pool should smell like chlorine semen should not. Either see a doctor, or stop frequenting your local pool. One of them is not right.	[ "The seminal plasma provides a nutritive and protective medium for the spermatozoa during their journey through the female reproductive tract. The normal environment of the vagina is a hostile one (c.f. sexual conflict) for sperm cells, as it is very acidic (from the native microflora producing lactic acid), viscou...
Why does my green laser pointer reflect orange on a pink tennis ball?	Tennis balls often use fluorescent dyes. These absorb light with a shorter wavelength, and emit light with a longer one. In order to 'activate' the dye, the light needs to have a short enough wavelength. Normal yellow tennis balls use a dye that absorbs blue and near UV light and emits yellow. As your green laser has...	[ "Some balls used in televised pool games are colored differently in order to make them distinguishable on television monitors. Specifically, the 4 ball is colored pink instead of dark violet, and the 12 is white with a pink stripe, to make it easier to distinguish their color from the black 8 ball, and similarly th...
About how many people died in the battles fought by the historic figure Mohammad?	Absolutely no way of knowing.Some historians have even suggested the historical Mohammed did not exist, although they've since largely disavowed that position. Sources are very very limited, especially for the earliest Islamic expansions. Sorry!	[ "The sum total of all casualties on all sides in all the battles of Muhammad might be more or less 1000. A contemporary Islamic scholar, Maulana Wahiduddin Khan, says that \"during the 23-years in which this revolution was completed, 80 military expeditions took place. Fewer than 20 expeditions actually involved an...
why do ancient chinese buildings have those curved roofs?	It's a bit like asking why Gothic architecture was covered in gargoyles. A variety of people likely included them for a variety of reasons, but most likely used them to imitate those who had used them before. The sweeping roof designs of Chinese architecture were reserved largely for palaces and temples and other buil...	[ "Chinese buildings may be built with bricks, but wooden structures are the most common; these are more capable of withstanding earthquakes, but are vulnerable to fire. The roof of a typical Chinese building is curved; there are strict classifications of gable types, comparable with the classical orders of European ...
Do all elements on the periodic table, like hydrogen and helium, have a half-life? If so, how long would it take for all of them to decay?	The answer is maybe. It depends on if the proton can decay. Current theoretical estimates put that half life around 10^35 years. It has not been seen, but people are looking. There are many "stable" isotopes that have a half life. We call them stable since their half lives are far longer than the age of the univer...	[ "Additionally, about 30 nuclides of the naturally occurring elements have unstable isotopes with a half-life larger than the age of the Solar System (~10 years or more). An additional four nuclides have half-lives longer than 100 million years, which is far less than the age of the solar system, but long enough for...
official eli5 united states presidential election thread	I've heard this brought up before once or twice, but is there any particular reason election day is not a national holiday? It strikes me that making it one would increase the voter turnout, but I'm not well-versed in politics or sociology(or history).	[ "The United States presidential election of 2008 was sponsored by the Commission on Presidential Debates (CPD), a bipartisan organization that sponsored four debates that occurred at various locations around the United States (U.S.) in September and October 2008. Three of the debates involved the presidential nomin...
the physiological difference between tablet, gel-cap, chewable, and liquid medicines?	There really isn't a ton of difference. There is a reason that over-the-counter meds generally come in more forms than prescription meds, and the reason is that consumers like variety while doctors just like to pick the one that works. Over-the-counter meds have more bells and whistles because the average person likes ...	[ "Tablet coatings protect tablet ingredients from deterioration by moisture in the air and make large or unpleasant-tasting tablets easier to swallow. For most coated tablets, a cellulose ether hydroxypropyl methylcellulose (HPMC) film coating is used which is free of sugar and potential allergens. Occasionally, oth...
what is that horrible painful massive 'lump' in your chest when you drink or eat something too fast?	Food and fluids get transported through your esophagus. Where the esophagus connnects to the stomach, a) it has to pass through an ligamentous opening in the diaphragm, which is a rather narrow passage and b) there is a sphincter muscle that is usually contracted to prevent stomach acid to flow back into the esophagus....	[ "Chest pain or pressure are common symptoms. A small effusion may be asymptomatic. Larger effusions may cause cardiac tamponade, a life-threatening complication; signs of impending tamponade include dyspnea, low blood pressure, and distant heart sounds.\n", "Presents as a sensation of food getting stuck (dysphagi...
in the nba, what are "waivers" and how does it affect the "salary cap"?	waivers work like this take the teams from worst (76ers) to best (GS Warriors) and rank them in order based on standings. This is the priority list for waiver claims so when players hit waivers, each team has a potential chance to land that player. NBA teams release players to the waiver wire, where he can stay fo...	[ "In North American sports contracts, waivers is a type of player transaction. A player under contract to a team is placed on \"waivers\" for a specified period of time; during this time other teams may submit a claim for that player's contract. Based on a priority system, the team with the highest priority earns ei...
What did early christians do when they gathered during the first two or three centuries?	I hope someone will come along and discuss what we can sift from the New Testament; from Paul's letters to Christians in the 50s and 60s, from the Synoptic Gospels in the 70s and 80s, and the Johanine works. There's a lot to say about how Jewish early Christianty was (short answer; pretty Jewish, but there was a lot of...	[ "Early Christianity arrived in the 2nd century and soon gained converts in the towns and among slaves. More than eighty bishops, some from distant frontier regions of Numidia, attended the Council of Carthage in 256. By the end of the 4th century, the settled areas had become Christianized, and some Berber tribes h...
There is a thread on r/books about "High Hitler", a book about Hitler's drug use. Is this book considered to be accurate?	I have [written](_URL_1_) about Ohler's book [before](_URL_0_) and adapted from that: Ohler's book suffers from a problem that both academic and pop history tend to both have if they are done shoddly: The superelevation of one aspect of history, which results in an almost mono-causal explanation. From Hitler's decisio...	[ "The book covers the years before and during Hitler's ascent to power in Germany—roughly 1922 through 1941, focusing on widely varying impressions of Hitler by Americans who managed to observe him close up. Few outsiders took the man himself seriously even whilst acknowledging the steadily growing power and popular...
What would be the consequences of a global, significant and sustained population decrease on the economy?	The problems arise when the population has more older people than younger people, as it poses significant challenges to social programs and other societal institutions that depend upon a relatively large workforce to be sustainable. There are already countries facing this issue right now, like Japan, which sells more a...	[ "Further, even in countries which have both large population growth and major ecological problems, it is not necessarily true that curbing the population growth will make a major contribution towards resolving all environmental problems. However, as developing countries with high populations become more industriali...
Anglo-Irish Trade War	Difficult to get but "Republicans & Imperialists: Anglo-Irish Relations in the 1930's" by Deirdre McMahon is the only study of the Economic War that I have seen. In the back there are charts on the Imports and Exports of the Irish Free State/Éire during this period: In the first half of 1931 total Irish exports were...	[ "The Anglo-Irish Trade War (also called the Economic War) was a retaliatory trade war between the Irish Free State and the United Kingdom from 1932 to 1938. The Irish Government refused to continue reimbursing Britain with land annuities from financial loans granted to Irish tenant farmers to enable them to purchas...
How much training would the average Roman Legionary have received before fighting in Julius Caesar's armies?	I don't want to discourage any other answers, but similar questions have been asked before, and are in the FAQ, [here.](_URL_0_)	[ "Under Julius Caesar, officers all came from aristocratic families that contained senators of the highest standings. Common soldiers, however, whether Roman or not, could rise through the ranks if they displayed outstanding ability and loyalty. Caesar also raised each legionary's salary to 900 sesterces a year and ...
why don't muslim leaders speak out against violence?	They do. It's not their fault that the media prints every "call to violence" announcement but never prints the responding "call against violence" announcements. [Here's just a few](_URL_0_).	[ "We often hear claims Muslims don't condemn terrorism and that Islam condones violence. As Muslims, we want to state clearly that those who commit acts of terror in the name of Islam are betraying the teachings of the Koran and the Prophet Mohammed. We reject anyone – of any faith – who commits such brutal acts and...
Has our use of artificial lighting affected the sleep cycle of household pets?	While I can't speak as much for household pets, egg laying hens have altered laying cycles influenced by artificial lights to increase efficiency. There was also a study done on wildlife near highways that showed a level of disorientation in animals near the artificially lit roads (as if it wasn't already obvious). Las...	[ "BULLET::::- Artificial night-time lighting has various effects on humans (not to mention wildlife) and exposure to optical radiation affects human physiology and behavior, both directly and indirectly. Many areas are not well understood, and a position statement from the Illumination Engineering Society (IES) emph...
why the smoke out of factories sticks around in the sky for so long?	If your cigarette was 50m tall and 10m wide the smoke would probably hang around a lot longer too. It's quite simply pumping out millions of times more than your cigarette is.	[ "A smokestack industry is a basic, usually cyclical, manufacturing industry. The factories stereotypically used in such industries that have flue gas stacks, hence the name, and produce a high volume of pollution. During the earliest era of electric power development, coal fired electric stations in urban areas wer...
how do the call in competitions for radio stations work?	You guys really think they're sitting there counting phone calls? Come on. They just pick up a random caller when they're in a break and can record the call, and say "you're the seventh caller!" The point of doing the contest isnt to give away the dumb tickets, it's to get people calling into the station and excited a...	[ "Contesting (also known as \"radiosport\") is a competitive activity pursued by amateur radio operators. In a contest, an amateur radio station, which may be operated by an individual or a team, seeks to contact as many other amateur radio stations as possible in a given period of time and exchange information. Rul...
Does Earth get energy from stars other than the sun?	If by energy you mean light and heat. Then essentially yes as being able to see the stars at night is there light (which is a form of energy) reaching us. But in the main way earth 'uses' the Suns energy, photosynthesis other stars do not contribute at all really. Could go far more in depth but not really sure if this...	[ "The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers (864,000 miles)...
How safe is fusion power - particularly from a waste perspective?	> Obviously there's no way for any form of energy production to have zero impact. Solar has basically zero impact, aside from equipment upkeep costs and up-front infrastructure development. But there are no waste products, radiation, or fuel (except light from the Sun) or anything like that. Same thing for wind and...	[ "Proponents believe that much of the ITER criticism is misleading and inaccurate, in particular the allegations of the experiment's \"inherent danger.\" The stated goals for a commercial fusion power station design are that the amount of radioactive waste produced should be hundreds of times less than that of a fis...
Is it possible to create human-animal hybrids?	It's absolutely possible, but there's no guarantee that the embryo would develop enough to ever be born. [This is a lecture slide from my Animal Development class](_URL_0_) that shows early developmental experimentation. They literally did nothing but cut pieces from embryos of 2 different species and swapped them to s...	[ "Some hybrids between similar species have been achieved by housing males of one species and females of the other together to limit the choice of mate. To create a \"natural\" macropod hybrid, young animals of one species have been transferred to the pouch of another so as to imprint into them the other species. In...
how do doctors anchor an artificial heart?	A donor heart is used for the ventricles, so the ventricles attach right to the native atria. The vessels are pretty durable, but the atria moreso I believe. There's a pretty long rest period post surgery to give stuff time to heal back into a more natural pace as well, which helps.	[ "An artificial heart is distinct from a ventricular assist device (VAD) designed to support a failing heart. It is also distinct from a cardiopulmonary bypass machine, which is an external device used to provide the functions of both the heart and lungs and are used only for a few hours at a time, most commonly dur...
Why are dyslexia and dysgraphia different?	For the same reason that learning to understand conversation in a foreign language with ease is less of a feat than becoming a fluent speaker: producing language is a different task than consuming it. The two overlap, but are still very different propositions.	[ "Dyslexia is thought to have two types of cause, one related to language processing and another to visual processing. It is considered a cognitive disorder, not a problem with intelligence. However, emotional problems often arise because of it. Some published definitions are purely descriptive, whereas others propo...
how do the web sites that charge for reverse number lookups and background checks get their information?	They buy the information from other data aggregators.	[ "\"Reporting entities\" are required to identify their customers using the 100 point check system. Accounts may be opened, but can only be operated (i.e. withdrawals made) by an identified customer; and an unidentified customer is blocked from making withdrawals. Generally, identification can be transferred from on...
do any of the 'close relatives to humans' (apes, monkeys and the like) have a relationship with another species like the one humans have with canines (or even equines)?	Additionally when humans and chimps became two different species, from that point on humqns evolved away from that point but the chimps we see around now, have they also evolved away from that point? Or are they still the same chimps they were so many years ago?	[ "Humanity's closest living relatives are common chimpanzees and bonobos. These primates share a common ancestor with humans who lived between six and eight million years ago. It is for this reason that chimpanzees and bonobos are viewed as the best available surrogate for this common ancestor. Barbara King argues t...
Do humans have a distinct walking/ running pattern?	Yes. It's possible to [identify individuals based on a video of how they walk](_URL_0_). I haven't seen the current state of the art, but the early systems could be defeated by putting a pebble in one shoe to throw off how you walk. I've even seen a system that will lock a cell phone if it doesn't recognize the walkin...	[ "The word \"walk\" is descended from the Old English \"wealcan\" \"to roll\". In humans and other bipeds, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support. In contrast, running begins when both feet are off the gro...
Have we seen atoms yet?	So as you know, the answer is: Yes. What techniques can we use to see atoms? The gif you show was made using [Scanning Tunneling Microscopy](_URL_0_). I recommend you check out the [video that GIF was taken from](_URL_2_), if nothing else than for the music. IBM actually started showing us micrographs of individual a...	[ "BULLET::::- Researchers at the Massachusetts Institute of Technology showed the first photograph demonstrating the appearance of an atom, using x-rays to simulate a pattern of iron and sulphur atoms, within the mineral marcasite, magnified more than 10,000,000 times.\n", "There is an established and long philoso...
Does getting in shape before having a kid change the child’s genetics/shape?	While the vast majority of the baby's characteristics will be determined genetically, there is growing evidence that some characteristics can be altered epigenetically in the womb. Basically, your DNA is the instruction manual for your cells to make stuff, but it can be chemically modified based on your environment to...	[ "The pattern the child develops after age five demonstrates the specific parenting styles used during the developmental stages within the child. These attachment patterns are associated with behavioural patterns and can help further predict a child's future personality.\n", "It has been observed that the first bo...
what does my dog stop every 5 feet to smell something?	In the same way we would admire a sunset or a beautiful picture of the ocean, dogs admire things by smelling them. It helps them become more familiar with their surroundings and it's just enjoyable for them.	[ "Preston claimed that his dog could smell human traces years or months after a suspect walked over the ground, on heavily trafficked streets, or both. He claimed that his dog could smell underwater, and, in a case against a man who was eventually freed on DNA evidence, Preston claimed that his dog could track a hum...
why is it that the quality of light at sunrise tends to seem so much bluer and brighter, and the quality of light at sunset tends to seem so much redder and dimmer?	The difference between the colors observed during a sunrise and the colors observed during a sunset is most likely caused by differences in the ~~density and temperature~~ composition of the atmosphere. If atmospheric conditions are held constant, the colors during a sunrise should in theory look identical to the color...	[ "Sunset colors are typically more brilliant than sunrise colors, because the evening air contains more particles than morning air. Sometimes just before sunrise or after sunset a green flash can be seen.\n", "During sunrise and sunset, sunlight is attenuated because of Rayleigh scattering and Mie scattering from ...
how do recycling centers sort between aluminum, plastic, cardboard, etc?	People with hands and regrets about their life choices. This is why many systems request you sort them yourself.	[ "BULLET::::- Many items from unsoiled paper, cardboard, glass, plastic bottles and jugs, aluminum cans and plastic tarps to corrugated polypropylene signs can be recycled depending on the services available in a given municipality or county. In many cases, such services are less costly than disposal of the same ite...
a digital rental (amazon etc.) clearly takes less resources than a redbox rental (aka create disk, ship disk, maintain machine etc.) yet it costs ~6x as much.	cost has nothing to do with prices (except to say that if cost > price, you wouldnt offer the product) Willingness to pay dictates price. And people are willing to pay more for a digital rental because they are easier to use on impulse without driving to a physical location.	[ "Although the service itself could be used free of charge, premium content was available to purchase from various stores in the shopping complex and in certain spaces. Users could browse and pay for items, such as virtual clothing and furniture, by accessing a shop and using its PlayStation Store interface. Items w...
difference between salt, spices, and herbs	Herbs are leaves (and sometimes nearby structures, like stems), spices are specifically not leaves. Both herbs and spices are additives, which means whether they are herbs or spices can be situational. In culinary terms, onions and garlic can be a spice or they can be a vegetable, depending how they are prepared. Sa...	[ "In general use, herbs are plants with savory or aromatic properties that are used for flavoring and garnishing food, medicinal purposes, or for fragrances; excluding vegetables and other plants consumed for macronutrients. Culinary use typically distinguishes herbs from spices. \"Herbs\" generally refers to the le...
what would happen if you are in a submarine 10.000m deep in the ocean and a window cracks and breaks?	besides all of the destruction of the sub, you and especially compressible things there would be an effect present called sonoluminesce. As the bubble of air in your submarine gets smaller and smaller due to the water rushing in the air gets so hot that it will start to glow for a very short amount of time. like a twin...	[ "This public demonstration almost ended in a disaster. After reaching a depth of 30 ft the craft began to lay down by the stern. As the submarine sank down the thin walls could not take the water pressure any more and started to crack. The water pressure proved too much for the weak pumps and the propeller wheel wa...
do twins have the same voices?	They tend to be similar, because the have the same genes and share the same experiences. But nongenetic factors can make their voices drift apart. If one lived in Maine and the other Mississippi, they'd start to pick up the local accent. And if one became a professional opera singer while the other became a professi...	[ "The Twins are first seen with the Merovingian smoking a hookah in his restaurant in \"The Matrix Reloaded\". They smirk at the fact that neither Trinity, nor Morpheus, nor Neo appear to have the same intellect as does the Merovingian. The Twins rarely speak, but when they do so, it is with a slow paced English acc...
how do wifi packets know which device to go to?	Each individual device has an address called a MAC address (different to an IP address). When a wireless hub (your WiFi access point) broadcasts a 'frame', which is the digital information containing a packet of data for a computer, the frame has the MAC address of the intended client included in there. Because wirele...	[ "Individual packets may take different routes to the destination and arrive at the destination out of order. The destination computer verifies the correctness of the data in each packet (using information in the trailer), reassembles the original item using the packet number information in the header, and presents ...
Why is mission control in Houston but we launch space shuttles from Florida? (X-post from /r/OutOfTheLoop)	I can answer the first part of your question (why Houston). Historian of technology Layne Karafantis has written about the history of Mission Control. In brief, Houston was selected for several reasons: "Access to water transportation by large barges, a moderate climate, availability of all-weather commercial jet servi...	[ "NASA's Christopher C. Kraft Jr. Mission Control Center (MCC-H, initially called Integrated Mission Control Center, or IMCC), also known by its radio callsign, Houston, is the facility at the Lyndon B. Johnson Space Center in Houston, Texas, that manages flight control for America's human space program, currently i...
why it seems to take longer to walk towards a place (like a store) vs walking away from a place (going back home)? [x-posted to elic]	You associate a much larger area as being "home" than the area that is the store. On the trip there your brain doesn't feel you have arrived until you enter the store, but on the return trip your brain feels at home as soon as you enter your neighborhood.	[ "BULLET::::- Move freely at their own leisure for up to three hours, choosing where to go and what to see, so that everyone's journey is unique; (they may also feel free to exit the premises at any point);\n", "In Australian Aboriginal society, Walkabout is a rite of passage during which males undergo a journey d...
what did old movies mean when they said "[this movie] has been formatted to fit this screen."	Movie screens where always wider than the normal home television. They have to alter the film in order to correctly fit your television screen. "Full Screen" versions of movies have black bars at the top and bottom of the screen. What many people don't realize is that the black bars aren't covering anything because the...	[ "Nostalgia for old Hollywood movies would be a theme of Donen's next film: \"Movie Movie\" (1978), produced by Lew Grade's ITC Entertainment and scripted by Larry Gelbart and Sheldon Keller. The film is actually two shorter films presented as an old fashioned double feature, complete with a fake movie trailer and a...
why is1/x divergent but not 1/x^2?	1/x doesn't go to 0 fast enough to overcome the fact that there's an infinite number of terms. 1/x^2 does.	[ "A bitwise XOR is a binary operation that takes two bit patterns of equal length and performs the logical exclusive OR operation on each pair of corresponding bits. The result in each position is 1 if only the first bit is 1 \"or\" only the second bit is 1, but will be 0 if both are 0 or both are 1. In this we perf...
How was the treatment of Helots by Sparta different than the treatment of slaves in the American South?	Tricky question. I don't know anything about the treatment of slaves in the American South. However, I can tell you that there are a few fundamental differences between 19th-century chattel slavery and the helot system used by the ancient Spartans. The main thing is that helots were not the personal property of the Sp...	[ "Sparta had a special type of slaves called \"helots\". Helots were Messenians enslaved during the Messenian Wars by the state and assigned to families where they were forced to stay. Helots raised food and did household chores so that women could concentrate on raising strong children while men could devote their ...

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