Split (2)

train · 226k rows

question stringlengths 3 301	answer stringlengths 9 26.1k	context list
what is the origin of cracking your knuckles before a fight?	I'm guessing this has an origin in movies. Possibly one scene in one particular movie, or it may have evolved naturally as a movie trope. A very similar trope is the cocking of a gun. It's almost as if people in movie/TV-land can't aim a gun at someone without it making a "chk-chk" sound. That sound is there to add...	[ "It has been suggested that the sound of \"cracking\" knuckles derives from the collapse of cavitation in the synovial fluid within the joint. Movements that cause cracking expand the joint space, thus reducing pressure to the point of cavitation. It remains controversial whether this is associated with clinically ...
Could a volcano eruption theoretically be powerful enough to launch debris into orbit?	As others have pointed out, Io is already known to jet into space, the only issue on earth is overcoming the atmosphere. You don't actually need escape velocity, but you DO need something near it - 11 km/s will send something away such that it will never return (and, to put in context, would be in space within 10 seco...	[ "In 2017, NASA conducted a study to determine the feasibility of preventing the volcano from erupting. The results suggested that cooling the magma chamber by 35 percent would be enough to forestall such an incident. NASA proposed introducing water at high pressure 10 kilometers underground. The circulating water w...
Why don't we have satellites orbiting all of the planets in our solar system by now?	So, a point of misunderstanding here is the idea that we haven't been sending things to other planets. _URL_1_ this info graphic is pretty cool, and gives you a sense of how many things we actually have launched. Also, it actually is quite difficult to get things there, and costly. For instance, New Horizons, which i...	[ "Mercury and Venus are believed to have no satellites chiefly because any hypothetical satellite would have suffered deceleration long ago and crashed into the planets due to the very slow rotation speeds of both planets; in addition, Venus also has retrograde rotation.\n", "The Solar System's planets and officia...
When a new plant species is discovered, how do scientists determine what diseases to try it on, in order to see if it's a cure?	Simply put, they don't. Organic compounds are isolated and identified from the plant. These compounds can then be added to large "libraries" of compounds and chemicals used for testing. A scientist can then, for example, grow cancer cells in the lab and try each of the compounds to see whether they inhibit cell growt...	[ "Thousands of plant diseases have been recorded throughout the world, many of these causing heavy crop losses. Early detection and accurate diagnosis is essential for the effective management of plant disease. Thus the first step in studying any disease is its timely detection of the diseased plant. Quick initial d...
how does electricity "know" when to start flowing?	imagine you have a water pump, connect an empty pipe with a tap on the end and it will fill up the pipe with water. (ignore the air that's in the pipe) the same thing happens with a wire. if you connect a wire to the positive of a battery the wire also becomes positive.	[ "As soon as the ignition is switched on current flows to the first \"Startix\" solenoid and current flows from battery to starter. The generator delivers current once the engine starts and part of it goes to a second \"Startix\" solenoid that switches off the current from battery to starter. If the engine and gener...
why do goat eyes change shape?	Their pupils are horizontal and will always stay in landscape orientation regardless of how they move their head, like a kind of image stabiliser. This ensures that they can always have maximum visibility to look out for predators. I haven't yet seen a round goats pupil.	[ "Goats have horizontal, slit-shaped pupils. Because goats' irises are usually pale, their contrasting pupils are much more noticeable than in animals such as cattle, deer, most horses and many sheep, whose similarly horizontal pupils blend into a dark iris and sclera.\n", "Besides the myotonia, another distinguis...
how do land surveyors work?	I know a little about this so I will share what I can. You start out with a point of known elevation. This is your Bench Mark. You set up your eyepiece thing on top of the bench mark and then have someone with the measuring stick walk a measured distance away. After looking through the eyepiece you can find the stic...	[ "Surveying or land surveying is the technique, profession, art and science of determining the terrestrial or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are of...
why hasn't snapchat sued facebook?	Snapchat would need to have invented something unique enough to patent (probably not), patented it (probably not), and then be willing to sue Facebook, a ridiculously rich company with a fabulous legal team who would love the excuse to crush snapchat into the ground.	[ "\"Fraley v. Facebook, Inc.\" was a class-action case that alleged that Facebook had misappropriated users' names and likenesses in advertisements. The case settled in 2013, with checks to class members mailed in November 2016.\n", "Lane v. Facebook was a class-action lawsuit in the United States District Court f...
why we aren't all just freaking the hell out that we are all going to die and we have no understanding as to why we even exist and no clue what happens after we die?	Because it is too late to get scared now.	[ "\"It is because the human spirit knows, deep down, that all lives intersect. That death doesn't just take someone, it misses someone else, and in the small distance between being taken and being missed, lives are changed.\" \n", "\"Now I sit back and look at some of the things we did, and I say, 'What in the wor...
why is the steering inverted on motorcycles at high speeds?	You are turning the front wheel to the left, the wheel goes left slightly, and the entire bike (and you) keeps going straight. The bike goes from looking like this: l to looking like this: / See how the bottom of the bike moves to the left? you have turned the front wheel slightly left, moving the bottom of the b...	[ "Because of theoretical benefits, such as a tighter turning radius at low speed, attempts have been made to construct motorcycles with two-wheel steering. One working prototype by Ian Drysdale in Australia is reported to \"work very well.\" Issues in the design include whether to provide active control of the rear ...
Isn't it impossible for anything to enter a black hole?	No, this is an accident of the singularity in the Schwartzchild coordinates. From the reference frame of an entity whose world line crosses the event horizon, space remains locally flat at the horizon and said entity will cross the event horizon (and smack into the singularity, or else thread the eye of the singularity...	[ "In the case of a charged (Reissner–Nordström) or rotating (Kerr) black hole, it is possible to avoid the singularity. Extending these solutions as far as possible reveals the hypothetical possibility of exiting the black hole into a different spacetime with the black hole acting as a wormhole. The possibility of t...
To what extent did European technology affect imperialism?	Hey! I can only really speak for European imperialism in the Far East, as that's the course I took for IB (high school diploma). To a large extent, I would say that European technology did help in advancing imperialism - it certainly didn't hurt, let's say. It doesn't have to be limited to guns - when Commodore Perry ...	[ "Europe's expansion into territorial imperialism was largely focused on economic growth by collecting resources from colonies, in combination with assuming political control by military and political means. The colonization of India in the mid-18th century offers an example of this focus: there, the \"British explo...
Books regarding Shaka Zulu	John Laband is the major academic-bridging-popular authority on Zulu kingship and the early kingdom, although others have written important works recently, and some metadiscussion like Dan Wylie's Myth of Iron: Shaka in History (2006) are still valuable. There are others who work on a variety of aspects of the kingd...	[ "Shaka Zulu is a 1986 South African television series directed by William C. Faure and written by Joshua Sinclair for the South African Broadcasting Corporation (SABC), based on Sinclair's novel of the same name (1985). It is based on the story of the king of the Zulu, Shaka (reigned 1816 to 1828), and the writings...
how do animals get the flu in the wild and where does the bacteria originate?	The virus is just another life form that happens to live in that population of animals. There are plenty. The problem with diseases that originate in other animals is that when a different type of host takes it, they're out of equilibrium. It's not actually in the viruses best interest to kill the host, because then i...	[ "Bacteriophages are viruses that infect bacteria and archaea. The International Committee on Taxonomy of Viruses officially recognises 28 genera of bacteriophages that belong to 11 families. They are important in marine ecology: as the infected bacteria burst, carbon compounds are released back into the environment...
Looking for literature on Caucasus region. Any suggestions?	[The Caucasus: An Introduction](_URL_0_) by Thomas De Waal is a great place to start if your interested in the region. Culturally and politically it is one of the most fascinating areas on the planet.	[ "The history of the Caucasus region may be divided into the history of the Northern Caucasus (Ciscaucasia), historically in the sphere of influence of Scythia and of Southern Russia (Eastern Europe), and that of the Southern Caucasus (Transcaucasia; Caucasian Albania, Georgia, Armenia, Azerbaijan) in the sphere of ...
when did the idea of featuring other artists in songs become the new norm?	I would say it has become more and more frequent in the last 10-15 years, but it's hard to say exactly when. I think a big part of it is that newer artists can showcase their talents with people who are already established, while big names can draw up more interest by grouping up with other famous artists.	[ "During the following days, the number of involved artists grew up to 56 different acts. Other artists, including Ivano Fossati, Fiorella Mannoia, and Subsonica, had to decline the invitation because they could not reach the remaining acts in Milan during the recording session of the song, which was decided to be h...
did people sound like they do in black and white movies in real-life or was it an affected accent? if it was, why did they do it in the movies?	Some people did actually talk like that. Specifically the very rich of New England. It’s called the transatlantic or mid-Atlantic accent. It was specifically taught to kids in boarding schools. Not naturally occurring accent, but one developed to sound kind of British and kind of American.	[ "The making of the picture posed several problems. Perhaps foremost was the fact that the characters of the program were portrayed as blacks but were in fact entirely voiced by whites. This had posed no problem on the radio, but obviously would not be suitable for a film where the actors could be seen as well as he...
do memories occupy a physical space in the brain?	Memories are pretty much connections between nerve cells, the more numerous (edit: and stronger) the connections the better you can remember something. Since this is a physical connection, theoretically there is a limit to how much we can remember. However we dont know how much of our brain is available to store mem...	[ "Spatial memories are formed after an animal gathers and processes sensory information about its surroundings (especially vision and proprioception). In general, mammals require a functioning hippocampus (particularly area CA1) in order to form and process memories about space. There is some evidence that human spa...
what is cybernetics?	AFAIK it is a cross-branch study of how everything depends on everything. Something like how the entire internet is one big spiderweb of different and seemingly unrelated issues that have a common line between them, cybernetics aims at studying how the different types of systems in the environment around us interact su...	[ "Cybernetics is the study of the communication and control of regulatory feedback both in living and lifeless systems (organisms, organizations, machines), and in combinations of those. Its focus is how anything (digital, mechanical or biological) controls its behavior, processes information, reacts to information,...
how do you speak louder?	Put your hand on your belly. Now practice inhaling and exhaling in such a way that your belly expands and contracts, moving your hand outward and inward. Once you've got that down, practice talking loudly while making your hand move inward.	[ "BULLET::::- \"Yelling:\" When people yell, raise their voices, or talk in a mean tone, they fuel their own anger. Many are unaware when they start to raise their voices. People should ask others to respond when the volume is rising and thank them.\n", "A speaker may fail to react as a listener to their own speec...
Why when I look up I see the sky as blue, but pictures of Earth don't see everything as blue?	The peak of extraterrestrial (solar) radiation is at [~480 nm](_URL_4_). The color would appear yellow-greenish. Through [Rayleight scattering](_URL_1_) on atmospherical particles, the peak of terrestrial (solar) radiation is shifted far into the [UV region](_URL_3_), giving a clear sky it's blue color. Rayleight sc...	[ "The daytime sky on Earth is blue because light from the Sun strikes molecules in Earth's atmosphere scattering light in all directions. Blue light is scattered more than other colors, and reaches the eye in greater quantities, making the daytime sky appear blue. This is known as Rayleigh scattering.\n", "The sky...
Help! I loved and want to re read this primary source from a college course on the crusades. But I forgot the title/author...	You're most likely thinking of Usama ibn Munqidh and the Kitāb al-I'tibār.	[ "BULLET::::- \"The Oxford Illustrated History of the Crusades\", editor (Oxford, Oxford University Press, 1995, paperback 1997, now reissued as \"The Oxford History of the Crusades\", paperback, 1999, translated into Russian, German and Polish)\n", "Thomas Scott Asbridge is a medieval history scholar at Queen Mar...
automatic windshield wipers	Some cars have water sensors somewhere on them. When they get wet, their electrical conductivity changes. The car's computer detects this and turns the windshield on. Advanced ones can even detect the rate at which water is coming, meaning they can adjust the speed as well.	[ "A windshield wiper or windscreen wiper (British English) is a device used to remove rain, snow, ice and debris from a vehicle's front window. Almost all motor vehicles, including cars, trucks, buses, train locomotives, and watercraft with a cabin—and some aircraft—are equipped with one or more such wipers, which a...
can wood fires generate UV rays?	We can model the flame of a wood fire as a black body radiator, since the glow of the flame largely comes from the heated solids given off from combustion. A blackbody radiator emits light purely as a function of its temperature: as the object gets hotter, it emits shorter wavelengths of light. The sun is somewhere ar...	[ "In regions continuously exposed to sunlight, UV rays can cause biochemical damage to plants, and eventually lead to DNA mutations and damages in the long run. When one of the main molecules involved in photosynthesis, photosystem II (PSII) is damaged by UV rays, it induces responses in the plant, leading to the sy...
Were ancient/medieval far east civilizations aware of western civilizations like the ancient Greeks and Romans and/or the Byzantines and vice versa?	I've looked into Rome's relations with China before, but I've never come across any evidence that the Koreans or Japanese were aware of Rome. Even to the Chinese, Rome was so far away as to be vaguely mythical. There is some evidence that the Romans had trade contact with Southeast Asia - a couple of Roman sources ment...	[ "The knowledge of the ancient \"Western world\" was partly preserved during this period due to the survival of the Eastern Roman Empire and the introduction of the Catholic Church; it was also greatly expanded by the Arab importation of both the Ancient Greco-Roman and new technology through the Arabs from India an...
i switch my tv off at the wall, but the little red standby light stays on for nearly a minute afterwards. how?	[Capacitors](_URL_0_) store electricity. This is why many electric appliances have warnings that you shouldn't poke around in them, even if unplugged. Some hold enough charge to stop your heart if you short it.	[ "BULLET::::- A signal to turn off remote transmitters may be played; is usually a series of touch tones. Once the transmission has been cut off there will usually only be video static on television stations or radio static on radio stations. In the digital age, a black screen is displayed as no transmission is able...
why we can't be friends with russia now that leadership has changed since the cold war, and how its justifiable to be friends with cuba even though they were the biggest concern in the cold war.	1. Cuba was absolutely NOT the biggest concern in the cold war. 2. You can't be friends with a country ruled by a corrupt, expansionist dictator. Especially not one who has meddled in our country's election.	[ "After the end of the cold war and the establishment of the Russia Federation, new ties have been made. Russia with its strong diplomatic relations with Arab States from the Soviet Era, is trying to regain its strength by supporting their causes, especially in the Security Council.\n", "Efforts to strengthen dipl...
If Black Holes consist of a single point of singularity where nothing can escape, does that mean they release almost no heat?	You would think that, but actually black holes radiate a very very small amount of light, called [Hawking radiation](_URL_0_). So someone sitting outside a black hole sees it as having a very very small, but nonzero, temperature. I'm not sure it makes any sense to talk about temperature inside the event horizon.	[ "Once a body collapses to within its Schwarzschild radius it forms what is called a black hole, meaning a space-time region from which not even light can escape. It follows from a theorem of Roger Penrose that the subsequent formation of some kind of singularity is inevitable. Nevertheless, according to Penrose's c...
how does insurance fraud even work?	Get insurance on something, break it on purpose, tell the insurance company it was an accident, get money.	[ "Another basis for fraud is over-insurance, in which someone insures property for more than its real value. This condition can be difficult to avoid, especially since an insurance provider might sometimes encourage it to obtain greater profits. This lets fraudsters profit by destroying their property, because they ...
When Voyager exits the heliosphere, will the solar system leave it behind?	Not sure if I'm misinterpreting your question, but it will have similar momentum relative to the solar system before and after it exits the heliosphere. So, I think the answer is no. It's not like an object which exits a car or a plane and then is suddenly subject to drag and friction that it didn't experience before. ...	[ "On August 30, 2007, \"Voyager 2\" passed the termination shock and then entered into the heliosheath, approximately 1 billion miles (1.6 billion km) closer to the Sun than \"Voyager 1\" did. This is due to the interstellar magnetic field of deep space. The southern hemisphere of the Solar System's heliosphere is b...
Why did Stalin really insist on a western front?	The reason Stalin demanded a second front was to relieve some of the pressure on the eastern front which would allow for a quicker victory. Consider that prior to July of 1943 almost all of Germany's assets were committed to the eastern front (save for the DAK). A second front means Germany has to divert resources to...	[ "After the war, Stalin sought to retain Soviet dominance across Eastern Europe while expanding its influence in Asia. Cautiously regarding the responses from the Western Allies, Stalin avoided immediately installing Communist Party governments across Eastern Europe, instead initially ensuring that Marxist-Leninists...
how do capacitors work and what do they do on a motherboard? also why do they leak?	Think about capacitors as a water holder with large hole to fill but it has a small hole that leaks the water anyway. It takes short time to fill it up but longer time to empty, it's used in electronics to save the electric charge for sometime.	[ "Capacitors are connected in parallel with the power circuits of most electronic devices and larger systems (such as factories) to shunt away and conceal current fluctuations from the primary power source to provide a \"clean\" power supply for signal or control circuits. Audio equipment, for example, uses several ...
When a subsea cable is damaged, how do internet companies know the location where the fault occured?	They can inject a signal at one end and wait for it to reflect off the damaged section. Divide the time delay between the input signal and the reflection by the speed of light in the cable and that tells you how far away the fault is. This works with both electrical and fiber-optic cables.	[ "Cable fault location is the process of locating periodic faults, such as insulation faults in underground cables, and is an application of electrical measurement systems. In this process, mobile shock discharge generators are among the devices used.\n", "Locating faults in a cable system can be done either with ...
what would happen if the us adopted a compulsory voting policy? (i.e. fine/community service for people who don't vote)	In other countries where mandatory voting is implemented, such as Egypt and Peru, citizens indicate in exit polls (by majority) that they couldn't explain why they voted for the person they did. In short, compulsory voting would not make voters more educated and informed about the people running for office, and thus ma...	[ "Since enactment of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996, federal law has prohibited noncitizens from voting in federal elections, punishing them by fines, imprisonment, inadmissibility and deportation. Exempt from punishment is any noncitizen who \"reasonably believed at the time...
if your heart has roughly 1 billion beats before natural failure, why is cardio exersize good for you?	Two reasons. - Cardio doesn't just exercise your heart. It exercises your lungs and your muscles associated with endurance. This helps your body a LOT, doing things like assisting your metabolism to keep your weight down, adding to your bone density from the impacts, lowering your blood pressure, and increasing your s...	[ "People experiencing some forms of heart failure have a significant decrease in the contractile ability of muscle cells in the heart (cardiomyocytes). This impaired contractility occurs through a number of mechanisms. Some of the main problems associated with decreased contractility in those with heart failure are ...
the large increase in the cost college today compared to the '80s and it's relation to the rise of student loan debt	I wrote this about six months ago, just my opinion. I hope I broke it down well enough, I'd be glad to answer any questions you have! _URL_0_	[ "\"The Economist\" reported in June 2014 that U.S. student loan debt exceeded $1.2 trillion, with over 8 million debtors in default. Public universities increased their fees by a total of 27% over the five years ending in 2012, or 20% adjusted for inflation. Public university students paid an average of almost $8,4...
Why are tornado watches and warnings almost always in the evening?	You're not wrong - the most common time of day for tornadoes to occur is in the late afternoon. One of the necessary components of tornado formation is ample convective energy, which can only occur when it's warm near the surface but cold above. Thus, the best conditions happen after the ground has been heated by the ...	[ "A watch does not mean that the severe weather is actually occurring, only that atmospheric conditions have created a significant risk for it. If severe weather actually does occur, a tornado warning or severe thunderstorm warning would then be issued. Note that a watch is not required for a warning to be issued; t...
why doesn't water go into your various holes when you take a bath? (possibly nsfw)	apparently, a BOT flagged my comment, so ill say it again: the body is made up of various muscles that cling to prevent the release of fecal matter and bodily fluids. the body also has internal pressure than prevents entry of liquids to certain parts screw you ellen pao	[ "A baby bath tub with a non-skid design is safe. If the water is deeper than a few inches, the baby may slip into the water and could possibly drown. An infant can easily slip under the water. The infant can be burned if the water temperature is too hot. How often an infant is bathed is a decision made by the paren...
why are chinese people in the uk buying so much baby milk powder?	They don't trust the shit they can buy in China. It wasn't too long ago that people were caught [intentionally poisoning milk products to increase profits](_URL_0_).	[ "On 25 September 2008, the EU announced a ban on imports of baby food containing Chinese milk. The European Commission also called for tighter checks on other Chinese food imports; isolated contaminated products were found in the Netherlands, and the French authorities ordered all Chinese dairy products off the she...
how can you poll a small population (1-2 thousand) and use it as an estimate for how hundreds of thousands will vote?	It's called the Law of Large Numbers. Say we were polling a class of 40 students for favorite ice cream flavor, and there were two options (vanilla, chocolate). Suppose that, across the whole population of 40, 15 students liked vanilla and 25 liked chocolate. So 37.5% of the class likes vanilla, and 62.5% of the class...	[ "Polls basically involve taking a sample from a certain population. In the case of the \"Newsweek\" poll, the population of interest is the population of people who will vote. Because it is impractical to poll everyone who will vote, pollsters take smaller samples that are intended to be representative, that is, a ...
What size must an asteroid have in order to completely destroy planet Earth?	Depends on the velocity, but there's certainly no asteroid in the Solar System even remotely capable of doing anything close to gravitationally unbinding the Earth. The Earth's gravitational binding energy is about 2 x 10^32 J. The kinetic energy of an object (assuming its velocity v is much lower than the speed of lig...	[ "Data shows asteroid to have a diameter of about . Scientists think that could be the exposed core of an early planet that could have been as large as Mars and lost its surface in a series of violent collisions.\n", "He has also questioned whether the current size of an asteroid thought to be large enough to crea...
How did mood swings while a woman is on her period evolve?	["Culture plays a significant role in the recognition, evaluation, and expression of menstrual symptoms...."](_URL_0_) That's just one of many results I got when I googled on culture and menstrual symptoms. Perhaps someone with some real knowledge on medical anthropology will chime in.	[ "The different phases of the menstrual cycle correlate with women's moods. In some cases, hormones released during the menstrual cycle can cause behavioral changes in females; mild to severe mood changes can occur. The menstrual cycle phase and ovarian hormones may contribute to increased empathy in women. The natu...
Is it possible to accurately predict the death of a given star?	No. The problem is that the changes which will result in the star exploding all occur deep within the core of the star, and it takes of order a million years for structural changes in the core to be visible on the surface. This not coincidentally about the same amount of time it takes for the thermal energy in the co...	[ "Alternatively, one could say that a sun is selected from all the possible stars every day, being the star that one sees in the morning. The plausibility of the \"sun will rise tomorrow\" (i.e., the probability of that being true) will then be the proportion of stars that do not \"die\", e.g., by becoming novae, an...
why is corn so different from other grains?	Several millenia of selectively breeding for more and larger grains. Ancient corn looked much closer to other grains.	[ "\"Corn\" was originally the dominant type of grain in a region (indeed \"corn\" and \"grain\" are themselves cognates from the same Indo-European root). It means usually cereals in general in the British Isles, but has come to mean exclusively maize in North America.\n", "Corn is grown in most parts of the count...
why are wood baseball bats in mlb milled to have a concave bore at the tip?	There are several reasons, the biggest of which are removing weight to increase swing speed, and improving the overall balance of the bat. Source: Catcher from 2nd place 1992 Little League team.	[ "When baseball was in its beginning years, baseball players made their own bats. This allowed players to experiment with different shapes and sizes of the bats. It did not take long for players to realize that the best bats were those with rounded barrels. Wood bats are rare at most levels other than the pros. The ...
What causes scoliosis?	Well, it's idiopathic because we literally don't know. You've listed some of the known causes of scoliosis. Not really sure what you're getting at? I don't know if a medieval torture device would have any beneficial effect. Probably because you'd have to be in that thing for a tremendous amount of time before the tis...	[ "Scoliosis, is a medical condition where a person's spine has several irregular curves that are located between the neck and the pelvis. Symptoms of scoliosis in mild cases usually exhibit abnormal posture, back pain, tingling or numbness in the legs and in worse cases can exhibit breathing problems, fatigue, perma...
Does the quality of the genes you pass on deteriorate as you get older?	Yes age does affect quality of genes. * More mutations accumulate in genes as we age. * In a woman, the germline cells are kept separate at the fetal stage of development. At each menstrual cycle, due to hormonal surge before ovulation, some of these cells are released from "hibernation" and end up being eggs. This ...	[ "Premature aging syndromes including Werner syndrome, Ataxia telangiectasia, Ataxia-telangiectasia like disorder, Bloom syndrome, Fanconi anemia and Nijmegen breakage syndrome are associated with short telomeres. However, the genes that have mutated in these diseases all have roles in the repair of DNA damage and t...
if i can hold my breath underwater for let's say, 5 minutes...why doesn't it take someone 5 minutes to choke me to death?	well inside your neck there are little tubes called arteries and veins. when someone squeezes your neck it cuts off the blood flow to your brain. if you just hold your breath then your blood flow is not cut off. so its lack of blood flow to your brain that kills you. it is possible to choke someone unconconcious within...	[ "Johnson's \"Water cell\" stunt requires her to hold her breath while she picks a series of locks that fasten chains and secure the lid of the cell. She averages 2 minutes and 48 seconds underwater on one breath, however she has occasionally taken up to 3 minutes and 18 seconds to free herself. The longest time she...
I've read that Hitler blamed jews largely for Germany surrendering WWI. What precisely did he think they did?	Hitler's blaming the Jews for Germany's defeat, stemmed from a nationalist myth that developed in Germany after WWI, largely thanks to the writings of members of the German military (esp. General Ludendorff) and the Nationalist Far Right (the German People's Party, the Stahlhelm, etc.), called the "Dolchstosslegende": ...	[ "Hitler shifted the blame of Germany's loss in the First World War upon \"enemies from within\". In the face of economic hardship as triggered by the Treaty of Versailles (1919), Jews who resided in Germany were blamed for sabotaging the country. The Nazis therefore classified them as the most inferior race and use...
Has the expansion rate of the universe always been strictly increasing?	> So did the acceleration start ultra-rapid, slow down, and increase again? Yes, you got it. In the earliest moments of the universe, it is hypothesized that (and there is some indirect evidence for) the universe was expanding extremely rapidly for an extremely short time -- this bout of expansion is called [inflati...	[ "While it was long believed that the expansion rate has been continuously decreasing since the Big Bang, recent observations of the redshift-distance relationship using Type Ia supernovae have suggested that in comparatively recent times the expansion rate of the Universe has begun to accelerate.\n", "Current evi...
why can we not/do we not store and reuse as much expended energy in cars as possible?	First two ideas that spring to mind: 1 - added financial expense to the vehicle makes it less likely to sell compared with competition. 2 - added weight from all the didgeridoos mentioned, resulting in increased fuel consumption and therefore lower efficiency at best equal to the energy regained but probably not.	[ "It is essential that a vehicle have a source of energy to drive it. Energy can be extracted from external sources, as in the cases of a sailboat, a solar-powered car, or an electric streetcar that uses overhead lines. Energy can also be stored, provided it can be converted on demand and the storing medium's energy...
How much mutation would have to occur to a genome before an organism is no longer considered the same organism?	New organism, as in a new species? As for sexually reproducing species, I know one rule of thumb is that a member of one species cannot produce viable offspring with a member of a different species. There are some exceptions, such as hybrids (Horse + Donkey = Mule). However, normally the offspring of hybrid species ...	[ "The human mutation rate is higher in the male germ line (sperm) than the female (egg cells), but estimates of the exact rate have varied by an order of magnitude or more. This means that a human genome accumulates around 64 new mutations per generation because each full generation involves a number of cell divisio...
What are some of the negative effects of a diet heavy in soy products/soy protein?	I'm going to take a wider view of this question. ilovelegos413 brought up a good point with the estrogen mimic issue. I have a question for you though, why consume a diet heavy in soy-protein in the first place? There are many cheaper, less processed protein sources that have a lesser chance of affecting the endoc...	[ "According to the American Cancer Society, \"There is growing evidence that eating traditional soy foods such as tofu may lower the risk of cancers of the breast, prostate, or endometrium (lining of the uterus), and there is some evidence it may lower the risk of certain other cancers.\" There is insufficient resea...
what makes a circular paper airplane fly so well?	Stability. 1. Circles are very hard to deform compared to other shapes. This means the "wing" will not flutter or collapse, which is the main problem when working with paper. 2. Having all of that weight at the bottom means it won't flip over, and won't roll over. It also looks like it is placed so that the more it b...	[ "Altogether, the aerodynamic forces co-interact, creating turbulence that amplifies small changes in the surface of the paper aircraft. Modifications can be made to most paper airplanes by bending, curving or making small cuts in the trailing edges of wings and in the airplane's tail, if it has one.\n", "Paper mo...
how do countries handle the vast discrepancies between international postage costs?	There is an organization called the Universal Postal Union that helps sort things out. Established in 1874, it is perhaps the oldest international governance organization in the world. It is now part of the UN. They have a system to balance the books when there is a mail imbalance between countries, where in your ex...	[ "Since the introduction of the Goods and Services Tax, separate stamps were introduced for domestic and international postage in 2001. Stamps inscribed \"International Post\" are not valid for domestic postage. Domestic stamps can be used for overseas postage but contribute less than face value towards the postage ...
if it's the other harmful chemicals in cigarettes that give cancer etc rather than the nicotine itself, why can't we mix nicotine with other non-harmful chemicals since people only smoke cigarettes for the nicotine?	You can, that's the idea behind the patches, nicorette gum, and vaping. Nicotine itself isn't completely harmless though, stimulant addictions bring their own issues.	[ "Nicotine itself, however, is addictive but not otherwise very harmful, as shown by the long history of people safely using nicotine replacement therapy products (e.g., nicotine gum, nicotine patch). Nicotine increases heart rate and blood pressure and has a range of local irritant effects but does not cause cancer...
Water droplets can generate electricity, right? Like in the Kelvin water dropper. Would there be a reliable way to harvest energy by gathering rainwater in tall buildings, then using gravity to generate electricity? Or something?	Suppose you have a 500 foot tall building, with a roof area of 10000 square feet, and maybe 40 inches of rainfall in a year. That's 2,081,000 pounds of water 500 feet above ground, for 391.9 kWh of potential energy. (Assuming of course that every drop is gathered and converted at 100% efficiency.) In 2010, the average...	[ "Hydro power is generated when the natural force from the water's current moves a device (fan, propeller, wheel) that is pushed by the force of the water. Ordinary water weighs 8.36 lbs per gallon (1 kg per liter). The force make the turbine mechanism spin, creating electricity. As long as there is flow, it is poss...
why are houses by the sea often more colorful than houses elsewhere?	Good question and I am no expert but i think the bright colors contribute to the whole "island vibe"	[ "In the early 1950s and 1960s, when many of the city's inhabitants were poor, the small houses were all painted white and blue. These colors, representing the sea and sky, were considered the city's official colors. Later, when there was financial growth, people began painting their houses in other colors.\n", "T...
Nothing can escape a black hole, not even light, so if you sent something straight at a black hole would the gravity of the black hole cause it to move faster than the speed of light?	No, a black hole cannot cause anything to move faster than light.	[ "BULLET::::- At the event horizon, formula_30 the speed of light shining outward away from the center of black hole is formula_31 It can not escape from the event horizon. Instead, it gets stuck at the event horizon. Since light moves faster than all others, matter can only move inward at the event horizon. Everyth...
polynesian people look very different from east asian people, yet are hypothesized to have expanded out of east asia only a few thousand years ago. how have the come to look so strikingly different, so quickly?	Polynesians are thought to be descended from Taiwanese aborigines or Formosan people of Taiwan, which are a different ethnic group from the Han Chinese which mostly populate Taiwan today.	[ "Most Native Indonesians are genetically close to Asians while the more eastern one goes the more people show Melanesian affinity. Geneticist Luigi Luca Cavalli-Sforza claims that there is a genetic division between East and Southeast Asians. In a similar manner, Zhou Jixu agrees that there is a physical difference...
how come most (all?) mammals have separate liquid and solid waste disposal systems?	Because the point of urine is only partially to get rid of urea. Mostly the point of it is to balance fluids and electrolytes. The kidneys have very finely tuned control over the amount of water lost. If they dumped into the bowels, the bowels would reabsorb a lot of the water, erasing the work of the kidneys. Addition...	[ "Most animals have excretory systems for elimination of soluble toxic wastes. In humans, soluble wastes are excreted primarily by the urinary system and, to a lesser extent in terms of urea, removed by perspiration. The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The system produc...
how iv fluid goes into our veins and ends up as pee	All of the organs in your body are connected by your blood. It's how the food that you eat can be sent to your muscles for fuel, how hormones released by your brain can cause your heart to race when you are scared, and how waste from your bodily processes ends up in your bladder. Waste products are released into your b...	[ "Interstitial fluid forms at the arterial (coming from the heart) end of capillaries because of the higher pressure of blood compared to veins, and most of it returns to its venous ends and venules; the rest (up to 10%) enters the lymph capillaries as lymph. Thus, lymph when formed is a watery clear liquid with the...
why doesn't wind cause the air pollution in china to disperse?	Because the sources of that air pollution are pumping it out faster than the wind can carry it away. There may also be some temperature inversions inhibiting sir movement, depending on the season and specific location.	[ "Air pollution (sulfur dioxide particulates) from reliance on coal is a major issue, along with water pollution from untreated wastes and use of debated standards of pollutant concentration rather than Total Maximum Daily Load. There are water shortages, particularly in the north. The eastern part of China often ex...
why are some drugs absorbed through the gut, and some through intestine?	The location in the body at which a drug is absorbed is indeed dependent on its molecular structure. Some drugs can pass right through your cells and into the bloodstream, while others must pass through specialized proteins channels that allow them to make it through the cell to the bloodstream. You ask why certain dru...	[ "Although the absorption in the human digestive system is mainly a function of the small intestine, some absorption of certain small molecules nevertheless does occur in the stomach through its lining. This includes:\n", "The small intestine is where most chemical digestion takes place. Many of the digestive enzy...
why will the sun burn something through a magnifying glass but if the sun hits eye glasses it wont burn your eyes?	Because glasses don't so much magnify as distort the light going through them to focus it where the eye needs it. You can create a heat spot with some lenses but you have to aim them directly at the sun and angle them just right so generally it's not an issue.	[ "The omnidirectional burning glass effect can occur with a crystal ball that is brought into full sunlight. The image of the sun formed by a large crystal ball will burn a hand that is holding it, and can ignite dark-coloured flammable material placed near it.\n", "Viewing the Sun through light-concentrating opti...
how do different shipping companies interact to ship goods worldwide?	Yes for the most part the railroads pay rent when on another's rails and in case of ocean lines will pay other companies for space on their ships if they don't have a ship going in the timeframes the person sending the stuff wants it done.	[ "The international shipping industry can be divided into four closely related shipping markets, each trading in a different commodity: the freight market, the sale and purchase market, the newbuilding market and the demolition market. These four markets are linked by cash flow and push the market traders in the dir...
If I shine a laser pointer at the moon, will any photons reach it?	Yes. Simply because of the sheer number of photons your laser is emitting. E = ħ c / λ E = energy per photon... ħ = plancks constant = 6.626x10^-34 J s c = speed of light = 3.00x10^8 m/s λ = wavelength = 540 nm = 540x10^-9 m E = (6.626x10^-34 J s) x (3.00x10^8 m/s) / 540x10^-9 m = 3.68x10^-19 J then...4.85 mJ = 4....	[ "At the Moon's surface, the beam is about wide and scientists liken the task of aiming the beam to using a rifle to hit a moving dime away. The reflected light is too weak to see with the human eye. Out of photons aimed at the reflector, only one is received back on Earth, even under good conditions. They can be i...
Why have composers become less prolific?	Classical music has been many different things. We put together a lot of music and musicians under that umbrella, but that doesn't mean all are equal. Bach and Telemann lived in a world rather different from that of Mozart, and 20th century composers lived in an even more different era. During Bach and Telemann's liv...	[ "However, the increase of power and variety obtainable by two performers instead of one offers a legitimate inducement to composers to write original music in this form, and the opportunity has been by no means neglected, although cultivated to a less extent than might have been expected.\n", "With the decline of...
How much does recycling actually save us, in terms of cost?	Popular Mechanics has a nice article about recycling. [Here](_URL_0_) Summary: Environmentally there is no debate that it is worth it, even when including energy costs like pickup and sorting. > Aluminum, for example, requires 96 percent less energy to make from recycled cans than it does to process from bauxite. At...	[ "The amount of money actually saved through recycling depends on the efficiency of the recycling program used to do it. The Institute for Local Self-Reliance argues that the cost of recycling depends on various factors, such as landfill fees and the amount of disposal that the community recycles. It states that com...
Big Question in several parts: How do we know how Ancient Egyptian and Ancient Mesopotamian words were pronounced?	Have you checked out * [Do we know what ancient languages actually sounded like?](_URL_1_): On many ancient languages, including Egyptian and Akkadian. * [How do we know what ancient Egyptian words sounded like?](_URL_0_) * [this post on Ancient Egyptian pronunciations](_URL_2_)	[ "In the history of the Egyptian language, the early 2nd millennium saw a transition from Old Egyptian to Middle Egyptian. As the most used written form of the Ancient Egyptian language, it is frequently (incorrectly) referred to simply as \"Hieroglyphics\".\n", "Ancient Egyptian texts are of particular interest d...
Is it theoretically possible to purposefully cause loss of all past memories in a human?	Kind of. [Electroconvulsive therapy](_URL_1_) tends to result in [retrograde amnesia](_URL_3_), which what you're asking about. There are a few cases where individuals lost sections of memory preceding their brain surgery. The most famous of these would be [Henry Molaison](_URL_2_), better known in psychology as H.M.....	[ "Neuroscience has shown that memories are vulnerable to disruption for several hours after they form. Holmes and colleagues proposed that because of this visuospatial distractors like Tetris, if administered within six hours of a traumatic event could help prevent symptoms of flashbacks. Also there is some evidence...
After someone has experienced near-fatal trauma, is there any evidence to suggest that keeping them from "falling asleep" will contribute to their survival?	There is no evidence that keeping someone awake will keep the victim alive. The reason you keep the casualty awake is so the person attending to the casualty, who, we assume, has no formal medical training, has a quick easy way to ensure the casualty is in no immediate threat of death. If a casualty is in the hospita...	[ "BULLET::::- Almost all postulated cases of SHC involve persons with low mobility due to advanced age or obesity, along with poor health. Victims show a high likelihood of having died in their sleep, or of being unable to move once they had caught fire.\n", "The greatest life threat due to GHB overdose (with or w...
how does the placebo effect work? if the body is capable of defeating a pathogen, why does it only do that when it is 'tricked'?	its not that id only does that when your sick, its your brain that doesnt want to recognize youre getting better The human brain is capable of many weird things, like making an amputaded arm hurt like hell even tho its not there Placebos make you believe youre getting better, removing such obstacles Its a pretty dee...	[ "Effectors are proteins encoded by pathogens, which act to effect a response from a host cell - often modulating the host immune response. Where a host variety is able to recognise and mount a resistance response to the presence of an effector, the effector is referred to as an Avirulence protein.\n", "Pathogens ...
Why isn't the Spanish Civil War more Important in European and American history?	To put a short-answer to a complicated question, the Spanish Civil war was overshadowed by the European Civil War, by the long and bloody Second World War. The World War negated the long-term political consequences of Franco's victory, deprived him of material resources to invade any other countries. The war also over...	[ "The Spanish Civil War exposed political divisions across Europe. The right and the Catholics supported the Nationalists as a way to stop the expansion of Bolshevism. On the left, including labor unions, students and intellectuals, the war represented a necessary battle to stop the spread of fascism. Anti-war and p...
Resources on the impact of scandinavian settlement on ecclesiastical culture in Anglo-Saxon England?	The Anglo-Saxon Chronicle is probably worth a look even though I can't remember anything specifically useful it. The Winchester and Abingdon specifically I think.	[ "After 867, Northumbria came under control of the Scandinavian forces, and there was an influx of Scandinavian immigrants. Their religion was pagan and had a rich mythology. Within the Kingdom of York, once the raids and war were over, there is no evidence that the presence of Scandinavian settlers interrupted Cath...
What was the general fitness like of Soldiers, for instance those fighting in WW1, WW2 and Korea/Vietnam, if everyone was smoking tobacco all the time?	This is a good question. I'm struggling a little bit with sources here but I will try to answer without delving too much into speculation. In terms of the very young soldiers during WW1 (14-18), I doubt this would have been much of a problem. Many of this age range who did smoke would have started during the war (if t...	[ "Reports suggest that persistently high rates of smoking in the military contribute to the high incidence of male smoking, and negate the efficacy of anti-smoking measures, as many men start smoking during their mandatory 2-year military service. The Public Health Graduate School of Yonsei University completed a 13...
how movie committees choose which films make the nominations for oscars/bafta's and seem to ignore some of the big films of the year?	_URL_0_ > The Sci-Fi Ghetto reflects a long-lasting stigma which has been applied towards the science fiction genre, which frequently leads creators and marketers to shun "Sci-Fi", "Science Fiction" or "Fantasy" labels as much as possible, even on shows that have clear science fiction or fantastical elements. It als...	[ ", the United Kingdom has submitted sixteen films for Oscar consideration, with two of them getting Oscar nominations. Most of these films were made by directors from or based in Wales, and were partially or completely filmed in the Welsh language.\n", "The 64th British Academy Film Awards, more commonly known as...
I am a Norse villager circa 950 AD. What is my daily routine like?	to OP: Can you specify what region you are interested in? The daily routine of a villager from Birka would be different from one from Truso, Uppsala, Somewhere in Varangian Russsia, or Viking colonised British Isles.	[ "Norges Bygdeungdomslag (\"Norwegian Rural Youth\") is a Norwegian youth organization, founded in 1946, aimed at promoting rural culture, and based on a Christian platform. In its heyday, it had close to 20,000 members, although the membership has now dropped to around 6,000 (as of 2011).\n", "Houses in the villa...
why aren't "season tickets" to your favorite bands a thing?	I can't speak for everywhere, but the bands I would subscribe too aren't in my area more than once a year, and when they are - it's part of a bigger concert. I would much prefer to just buy tickets on the fly, for flexibility and the economics of it.	[ "The National Football League has enjoyed success in selling out many of their venues from season ticket sales alone. Out of 32 teams in the league, 24 claim to have waiting lists from under 1,000 people to over 150,000. For some fans, this means a wait not just of years, but decades. This is due mostly to the NFL'...
if before the universe there was nothing, then the universe was created, shouldn't there be a field of nothing at the possible edge of the universe?	A common misconception about the expansion of the universe is to imagine it's expanding in all directions in three dimensions. You envision a balloon that we're inside. The balloon is getting bigger, and you say 'there must be an actual balloon around this space'. In reality, the universe as we know it is the surfac...	[ "A Universe from Nothing: Why There Is Something Rather than Nothing is a non-fiction book by the physicist Lawrence M. Krauss, initially published on January 10, 2012 by Free Press. It discusses modern cosmogony and its implications for the debate about the existence of God. The main theme of the book is how \"we ...
The role of firearms in the Hussite Wars	The chief obstacle to effective small arms in the earlier 15th c. was the lack of knowledge about manufacturing gunpowder. This is before real chemistry: the only way to arrive at a mostly-pure potassium nitrate, to separate it from salt, and from the calcium and sodium nitrates that often occurred in manure heaps as ...	[ "Hussite forces in Bohemia developed war wagons - medieval weapon-platforms - around 1420 during the Hussite Wars. These heavy wagons were given protective sides with firing slits; their heavy firepower came from either a cannon or from a force of hand-gunners and crossbowmen, supported by infantry using pikes and ...
Why is chicken the ubiquitous cheap protein it is today, while other poultry, e.g. ducks, remain fairly costly and niche?	Unfortunately, I can't give you a historical answer. I can give you a modern answer though, as I actually looked into keeping either chickens or ducks a few months ago. At first glance, ducks are the clear winner. Campbell ducks average 285 eggs, 31 ounces each, per year, and consume between 2.4-3.0 lbs of food per po...	[ "Chicken now provides some 20% of the animal protein eaten by the world's human population in the form of meat and eggs. Chickens are often raised intensively in battery farms; this facilitates production but has been criticised on animal welfare grounds. Other species including ducks, geese, pheasants, guineafowl ...
how schools choose their curriculum?	In some countries, it is dictated by law what subjects must be touched upon. These laws are created under the advisement of a national school board, consulting experts, etc. Each school is then free to choose their own classes and class content within the confines of these national laws/guidelines. Certain hours must ...	[ "\"School choice\" is a term for K–12 public education options in the United States, describing a wide array of programs offering students and their families alternatives to publicly provided schools, to which students are generally assigned by the location of their family residence. In the United States, the most ...
the supreme court chose not to take up the cases on gay marriage. if the 6th circuit court upholds bans in ky, oh, tn and fl, what happens now?	They may reconsider taking up the issue next term. There are no current splits so the Supreme Court prefers to let it play out in the lower courts until that becomes a bigger issue. They do not want to take the flack for cowardly politicians, who are trying to pass the issue to them.	[ "Attorney General Patrick Morrisey announced on October 9 that he would no longer defend the suit since the U.S. Supreme Court had declined to review a similar Virginia case that had found that state's denial of marriage rights to same-sex couples unconstitutional. Judge Chambers ruled on November 7 that the state'...
Cold Fusion: What do people think of the new paper from Giuseppe Levi et al?	But is it really fusion? I don't think they claim that. They claim that an "unknown process" results in the heat production. Here are the unanswered questions I had from reading the introduction and conclusion (I don't have time to be bothered with the middle!): 1. How do we know the hydrogen enriched nickel was not...	[ "After 1989 Schwinger took a keen interest in the non-mainstream research of cold fusion. He wrote eight theory papers about it. He resigned from the American Physical Society after their refusal to publish his papers. He felt that cold fusion research was being suppressed and academic freedom violated. He wrote: \...
when a plane turns in the air why don't things slide?	This is called a coordinated turn. The pilot (or autopilot) controls the angle of the wings to balance the plane through the turn, like you would do while riding a bike. It makes for a more pleasant ride. The net force of gravity plus the turn is straight out the bottom of the plane, just not towards the center of t...	[ "Anyone in an aircraft that is making a coordinated turn, no matter how steep, will have little or no sensation of being tilted in the air unless the horizon is visible. Similarly, it is possible to gradually climb or descend without a noticeable change in pressure against the seat. In some aircraft, it is possible...
if there's only so much gold available in the world, why does goldschlager and edible gold flakes for baked goods exist. aren't we depleting our supply?	The amount of gold in edible uses is so miniscule as to not matter. One of gold's properties is that it can be pounded out super thin so things like use in Goldschlager or even when gold leaf is applied to a dome it's only molecules thick. An entire capitol dome covered in real gold leaf may only use like 2 lbs of gold...	[ "Because it is so soft, however, 24 karat gold is rarely used. It usually is alloyed to make it stronger and to create different colors; goldsmiths may have some skill in that process. The gold may be cast into some item then, usually with the lost wax casting process, or it may be used to fabricate the work direct...
How does one generate a single photon?	Get a single atom into an excited state, then given enough time it'll calm itself down and poop out a photon.	[ "The generation of a single photon occurs when a source creates only one photon within its fluorescence lifetime after being optically or electrically excited. An ideal single-photon source has yet to be created. Given that the main applications for a high-quality single-photon source are quantum key distribution, ...
why can men keep producing children in old age but women have the menopause?	We actually don't know. We don't know why human woman experience menopause. It's a somewhat rare phenomenon in the animal kingdom too. While there are a couple of other species that also experience menopause (non-human primates, elephants, whales) it is not a common thing. Of course we got a couple of hypothesises, bu...	[ "BULLET::::- Women become less fertile as they get older. For women aged 35, about 94% who have regular unprotected sexual intercourse get pregnant after three years of trying. For women aged 38, however, only about 77%. The effect of age upon men's fertility is less clear.\n", "There is criticism of the claim th...
why do parents work so hard to manage the sleep of young children (and is there an alternative)?	These parents are often exhausted and would really, really like to get more rest. That's why they are so keen on having their child sleep.	[ "Besides physical developmental advantages, co-sleeping may also promote long-term emotional health. In long-term follow-up studies of infants who slept with their parents and those who slept alone, the children who co-slept were happier, less anxious, had higher self-esteem, were less likely to be afraid of sleep,...
To what extent do we know that more bombs were dropped on Laos during the Vietnam War, than all the bombs dropped on Japan and Germany combined during WWII?	The question isn't entirely clear, but to answer in the way I think you intended: we know for sure. The simple reasons are: 1) WWII lasted for about half a decade, while the Vietnam war lasted a full decade. 2) technological advances made it possible for planes to carry a bigger payload during the Vietnam war An exam...	[ "Massive aerial bombardment against Pathet Lao and NVA forces was carried out by the United States. It has been reported that Laos was hit by an average of one B-52 bombload every eight minutes, 24 hours a day, between 1964 and 1973. US bombers dropped more ordnance on Laos in this period than was dropped during th...
What do the dot product/the tensor product of two vectors represent geometrically?	The dot product of u and v is \|u\|\|v\|cos(θ), where θ is the angle between u and v. The tensor product of u and v is a bit more complicated. This is also called the outer product of u and v. If we represent u as a column vector, then the outer product u ⊗ v is the matr...	[ "In mathematics, a small middle dot can be used to represent product; for example, \"x\" ∙ \"y\" for the product of \"x\" and \"y\". When dealing with scalars, it is interchangeable with the multiplication sign: \"x\" ⋅ \"y\" means the same thing as \"x\" × \"y\", but × is easily confused with the letter \"x\". How...
Methane synthesis from CO2 and sea water?	_URL_1_ is the only large scale attempt I know of. They have a 25kW demo system running and a few-MW system is supposed to be ready this year I think. Their site doesn't say anything about efficiency but the process is simple: Water electrolysis and the Sabatier process, 4 H2+CO2- > CH4 + 2 H2O. It's been used for dec...	[ "Methane (CH4) is a greenhouse gas that is over 20 times more potent than CO2, and has an atmospheric lifetime of about 12 years. It is produced through natural processes (i.e. the decomposition of plant and animal waste), but is also emitted from many man-made sources, including coal mines, natural gas and oil sys...
i found this mentioned on /r/science, can someone explain what "'twisted' light" is?	I haven't seen the post but from what I can guess from the name they are using circular polarised light. And the way this is interesting is that you can encode more information. Lets say that you see a photon, this is the equivalent of 1 in binary. The lack of a photon is 0. But now with circular polarised light you c...	[ "Twisting the optical metamaterial effects its \"space\" into new coordinates. The light that travels in real space will be curved in the twisted space, as applied in transformational optics. This effect is analogous to starlight when it moves through a closer gravitational field and experiences curved spacetime or...
when animals are fighting, why do they sometimes pause in the middle of the fight and stare into empty space?	They're not staring into empty space. They're using their peripheral vision. Their, and your, peripheral vision is more effective at seeing movement.	[ "Actual fighting in contests is rare because of the risk of injury to both participants. It is most likely to occur when individuals are similarly sized, or when the contested resource is essential for reproduction or survival. Even when agonistic behaviour escalates to fighting, restraint may be used. Fish such as...
Anyone know about Americans who immigrated to the USSR during the Depression?	In the Finnish-American community, peraps 7,000 migrated to the USSR (specifically, Karelia along the Finnish border) among leftist Finns who believed in the ideal of "building a socialist utopia" under Stalin. The book Karelian Exodus by Ronald Harpelle, Varpu Lindstrom, and Alexis Pogorelskin covers this topic.	[ "Despite all of this, The Great Depression caused mass immigration to the Soviet Union, mostly from Finland and Germany. Soviet Russia was at first happy to help these immigrants settle, because they believed they were victims of capitalism who had come to help the Soviet cause. However, when the Soviet Union enter...
I remember reading somewhere that the soviets were delivering tanks into the field via aircraft during a major battle...	The Russians were actually behind the curve in moving tanks during WW2. Most militaries had moved to gliders pulled behind heavy bombers. But the Russians were still using bombers with light tanks strapped underneath them. The most common was the T27 which was too small to be properly called a tank only weighing 2.7...	[ "Later, the Soviets used heavy bombers to land on the battlefield carrying T-27 tankettes and T-37 tank light tanks, and experimented with air-dropping light tanks (both with and without parachutes). In 1941, airborne units were issued T-40 amphibious tanks.\n", "In 1945 the Soviet Union also tested captured Japa...
I need your help in identifying strange lights in the sky	[Iridium Flare.](_URL_1_) [See if there was one](_URL_0_) given time and location.	[ "The area is best known for sightings of the Min Min lights, mysterious shimmering lights that appear at night. The lights are said to be caused by atmospheric refraction that occurs when cold air is trapped below warmer air, a phenomenon known as Fata Morgana.\n", "One early account of the lights dates from Sept...
Why did African spiritual beliefs dissappear in U.S. but continue to exist in South American countries?	Well i'd like to make the first comment, that African spiritual beliefs didn't dissipate in the North American Colonies, but rather evolved over time. The study of these perceived "Africanisms" in African-American culture is still very much being studied and debated among historians. I covered this to a much heavier ex...	[ "In the beginning of the 18th century, Christianity began to spread across North Africa; this shift in religion began displacing traditional African spiritual practices. The enslaved Africans brought this complex religious dynamic within their culture to America. This fusion of traditional African beliefs with Chri...
why do i need to press ctrl alt delete before i can use my school's computer?	It's a security feature to make sure that you're typing your password into the real login screen, and the last person to use the machine didn't leave it running a fake login screen to collect people's passwords. For historical reasons, the Ctrl-Alt-Del combination can only be read by Windows, it will never pass that k...	[ "BULLET::::- Control-Alt-Delete, often abbreviated as Ctrl-Alt-Del, is a computer keyboard command on PC compatible systems that can be used to reboot a computer, and summon the task manager or operating system. It is invoked by pressing the Delete key while holding the Control and Alt keys: Ctrl+Alt+Delete. Thus, ...

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