Split (2)

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question stringlengths 3 301	answer stringlengths 9 26.1k	context list
What aspects of a speaker determine it's max volume?	Two things can go wrong with a speaker. The coil can push the cone too hard and it rips. This happens a lot with older paper speakers. You can put too much electricity through the coil (a little transformer) and burn it out. The volume produced is (sort of) the diameter of the cone times the travel in and out. That ...	[ "Due to the reactive nature of a speaker's impedance over the audio band frequencies, giving a speaker a single value for 'impedance' rating is in principle impossible, as one may surmise from the impedance vs. frequency curve above. The nominal impedance of a loudspeaker is a convenient, single number reference th...
what makes elements perform ionic and covalent bonds?(x-post from askscience)	Ionic bonds are a bit easier to visualize I think. You can sort think about it this way: Atoms are composed of a nucleus with protons and a bunch of electrons. Each proton carries a positive charge and each electron carries a negative charge. Like the poles on a magnet, the positively and negatively charged particles a...	[ "Going down the above table, there is a transition from covalent bonding (with discrete molecules) to ionic bonding; going across the table, there is a transition from ionic bonding to metallic bonding. (Covalent bonding occurs when both elements have similar high electronegativities; ionic bonding occurs when the ...
What did people do before coffee?	A similar question was asked about a month ago. You will find somewhat relevant answers in the comments. [Did the Ancient Romans have their own version of a "cup of coffee"? by which I mean a mild stimulant they would have used on a daily basis](_URL_0_)	[ "The history of coffee dates back to the 15th century, and possibly earlier with a number of reports and legends surrounding its first use. The native (undomesticated) origin of coffee is thought to have been Ethiopia.The earliest substantiated evidence of either coffee drinking or knowledge of the coffee tree is f...
What equipment would ancient Romans use against armoured opponents? ~107BC-395AD	Standard fighting equipment for a post-Marian legionnaire was the gladius, pilum, pugio, scutum, galea, and some sort of body armor, either the lorica squamata, lorica hamata, or, mainly imperial, lorica segmentata. This profile rarely if ever changed in any meaningful way, whether fighting naked Britons or Parthian ho...	[ "Siege warfare gave the Roman army significant offensive advantages over their enemies. Though the catapult was developed in ancient Greece, the Romans were able to replace the traditional Greek catapult made of wood making the most stressed components out of iron or bronze. This allowed for a reduction in size and...
why was black and white photography very high resolution at it's peak, but soon after when color photography was introduced, it was very bad quality?	Black and White film has one emulsion, color film has three emulsions (RGB). According to [Wikipedia](_URL_0_): > Photographic emulsion is a fine suspension of insoluble light-sensitive crystals in a colloid sol, usually consisting of gelatin. The light-sensitive component is one or a mixture of silver halides: sil...	[ "This made photography much more useful to science, allowed a more satisfactory rendering of colored subjects into black-and-white, and brought actual color photography into the realm of the practical.\n", "However, even if both techniques have inherent noise, it is widely appreciated that for color, digital phot...
How can a layman tell how reliable a source is?	I tell my students to start with a Google of the author. Is s/he affiliated with a university? With a think tank? NGO? Each of these will have differing goals in publishing, and you need to weigh them when considering a source. Then read her/his CV, paying attention to what has been published and in which journals. I...	[ "BULLET::::- Using Primary Sources as Evidence is the ability to locate, choose, understand and provide context for the past using primary sources. This approach to reading a source will be dependent on the kind of source being used and the kind of information the user is trying to find (e.g. reading to a book for ...
If genetic testing shows Ashkenazi Jewish people have much more relation to the semitic people, where did the Khazar jews end up after the empire collapsed?	This thread has a pretty good compilation of threads on the religion of the khazars _URL_0_ _URL_1_ By /u/gingerkid1234	[ "Much awareness of \"Ashkenazi Jews\" as an ethnic group stems from genetic studies of disease. Some regard these studies as exhibiting ascertainment bias which created an impression that Jews are more susceptible to genetic disease than other populations. They cite BRCA1 and BRCA2 mutations becoming identified as ...
Books on early fascism's relationship to liberalism and socialism?	Emilio Gentile (whose works have the additional quality of being, some times, available in an English translation) has spent a good portion of his career analyzing the early stages of the ambiguous definition of a "fascist ideology" within the environment of what he has defined "national radicalism". His early works ...	[ "In the book, Goldberg argues that both modern liberalism and fascism descended from progressivism, and that before World War II, \"fascism was widely viewed as a progressive social movement with many liberal and left-wing adherents in Europe and the United States\". Goldberg writes that there was more to fascism t...
Can a solar system or star get pulled into a different galaxy?	In around four billion years our galaxy will collide with the Andromeda galaxy (Since galaxies are largely empty space with the odd solid bit - it won't be quite as violent as it might seem - probably). Assuming that the two galaxies subsequently go on their merry ways (imagine a comet having a close pass with the sun...	[ "This galaxy is known to contain two counter-rotating populations of stars. That is, one set of stars is rotating in the opposite direction with respect to the other. One means for this to occur is by acquiring gas from an external source, which then undergoes star formation. An alternative is by a merger with a se...
Is the Higgs field an actual physical field of energy?	First off the Higgs field is as real a field as any other field and was predicted in the 60's. As to whether particles or fields are fundamental or mathematical tools, that is really a philosophical question.	[ "In the Standard Model, the Higgs field is a scalar tachyonic field \"scalar\" meaning it does not transform under Lorentz transformations, and \"tachyonic\" meaning the field (but not the particle) has imaginary mass, and in certain configurations must undergo symmetry breaking. It consists of four components: two...
Why is the direction of the torque vector significant?	The direction of the torque vector is only significant once an arbitrary convention (i.e. the right hand rule) has been chosen. Really I think it make more sense to think of toques and angular momenta as defined by a plane plus a direction of circulation than it does a vector. However, there's a nice property in three...	[ "Due to the way the torque vectors are defined, it is a vector that is perpendicular to the plane of the forces that create it. Thus it may be seen that the angular momentum vector will change perpendicular to those forces. Depending on how the forces are created, they will often rotate with the angular momentum ve...
law of conservation of mass	It's like when you're playing with your legos, buddy. You can take your house apart, make it into a car, move the bricks closer together or further apart. But you can't break the bricks, they're indestructible. Now pretend everything in the world is made of legos which are so tiny that you can't see them, those are cal...	[ "The law of conservation of mass can only be formulated in classical mechanics when the energy scales associated to an isolated system are much smaller than formula_1, where formula_2 is the mass of a typical object in the system, measured in the frame of reference where the object is at rest, and formula_3 is the ...
just seen captain phillips, why are cargo ships sailing around the horn of africa so poorly defended?	International maritime law forbids arming merchant ships.	[ "Several factors combine to make the passage around Cape Horn one of the most hazardous shipping routes in the world: the fierce sailing conditions prevalent in the Southern Ocean generally; the geography of the passage south of the Horn; and the extreme southern latitude of the Horn, at 56° south. (For comparison,...
why can't robots move exactly like humans yet? what is holding engineers back?	The trouble is software. We have the technology to build the physical machine itself. We could build an artificial skeleton with artificial tendons and muscles and the necessary sensors, but developing the software to control it all simultaneously in a way that duplicates human movement is a daunting task.	[ "Robots able to co-exist and co-operate with people and reach or even surpass their performance require a technology of actuators, responsible for moving and controlling the robot, which can reach the functional performance of the biological muscle and its neuro-mechanical control.\n", "The tendency to build robo...
why can't the cellular infrastructure that is in place to provide 3g and lte just be used to create a giant wifi network?	Those networks use different standards to provide their signals. It's not like it's all using the same frequency for all of the various forms of wireless. [Source.](_URL_0_)	[ "3G networks have taken this approach to a higher level, using different underlying technology but the same principles. They routinely provide speeds over 300kbit/s. Due to the now increased internet speed, internet connection sharing via WLAN has become a workable reality. Devices which allow internet connection s...
why are "bologna" and "lasagna" pronounced so utterly differently?	We've Americanized the pronunciation of bologna a lot more than lasagna.	[ "\"Knöpfle\" means \"small buttons\" and describes the compact, round form of the pasta. In everyday language usage, the two names refer to the same product made from the same dough and are interchangeable. There is no clear distinction between the way the two names are used and usage varies from one region to anot...
I'm an extremely deep-sleeper, and have massive troubles waking up on time. Is there a scientific alarm solution?	I read about using sunlight/simulated natural light to help people wake up: _URL_0_ I use a similar thing but I go low-tech when trying to wake up my 5-year-old (not an easy task) and just turn on the light.	[ "Scientific studies on sleep having shown that sleep stage at awakening is an important factor in amplifying sleep inertia. Alarm clocks involving \"sleep stage monitoring\" appeared on the market in 2005. The alarm clocks use sensing technologies such as EEG electrodes and accelerometers to wake people from sleep....
how can banks detect if someone else is using your credit/debit card when the amount is small and the location of purchase is near?	What was the store? What was the time? Had you made any other purchases recently? Fraud detection systems work by finding patterns in your spending and flagging things that don't fit the pattern. If it's in a weird city when you're normally at work & not buying things at all, that's going to flag things. If you'...	[ "The Senate report identified \"data pass\", or the automatic transfer from the merchant after the transaction of the customer's credit card information. Information provided by the Federal Trade Commission and the National Association of Attorneys General, and information collected from telephone billing has found...
Why is Napoleon often portrayed with his right hand tucked into his vest?	The pose is quite common in period paintings: Directly bearing on the "hand-in" posture, and underpinning Nivelon's description of it as "manly boldness tempered with modesty," is Bulwer's "Sixth Canon for Rhetoricians," which claims that "the hand restrained and kept in is an argument of modesty, and frugal pronunci...	[ "The hand-in-waistcoat (also referred to as hand-inside-vest, hand-in-jacket, hand-held-in, or hidden hand) is a gesture commonly found in portraiture during the 18th and 19th centuries. The pose appeared by the 1750s to indicate leadership in a calm and firm manner. The pose is most often associated with Napoleon ...
albinism seems like a very disadvantageous mutation. how has it continued in the animal kingdom?	A mutation can appear more than once in time. Albino animals pretty much never have albino parents, it just appears randomly and likely subsides again as the chances of reproduction are lowered. The parents have instead carried an albino gene, without being albino themselves.	[ "Oculocutaneous albinism is generally the result of the biological inheritance of genetically recessive alleles (genes) passed from both parents of an individual such as OCA1 and OCA2. A mutation in the human TRP-1 gene may result in the deregulation of melanocyte tyrosinase enzymes, a change that is hypothesized t...
what happens when my computer is connecting to/loading a website/?	There's many steps, but here is a simple explanation: You send an "HTTP request" to the server. HTTP is the protocol commonly used to send/receive data on the internet. Let's just say it's like the format of when you write your address and destination address on an envelope. This request will look something like thi...	[ "Each time a user visits a website using Microsoft Internet Explorer, files downloaded with each web page (including HTML and Javascript code) are saved to the Temporary Internet Files folder, creating a web cache of the web page on the local computer's hard disk drive, or other form of digital data storage. The ne...
Why is the modern nation of Ghana located far southeast of the medieval kingdom of Ghana?	This question comes up from time to time. My answer in [this thread](_URL_0_) gives the specific context for how the Gold Coast colony came to be named Ghana. Also, [this post from last month](_URL_1_) provides additional context about the oral traditions that Danquah was drawing on to justify the connections.	[ "Ghana was inhabited in the Middle Ages and the Age of Discovery by a number of ancient predominantly Akan kingdoms in the Southern and Central territories. This included the Ashanti Empire, the Akwamu, the Bonoman, the Denkyira, and the Mankessim Kingdom.\n", "Thus, although the Ghana Empire was geographically d...
Why do old portraits all look so similar? I feel like I have no idea how these people really looked.	I don't think this is universally true; if you look at the portraits by Hans Holbein the Younger for example it starts to become very obvious that these people all look different. Some people have rather large noses, some people have rather wide or round or skinny cheekbones, some people have the most absurd tiny eyes,...	[ "Portraits are natural reflection of real people. The ability to achieve a true likeness was greatly valued until the mid-nineteenth century. However, once photographs became common, artists could use their skills to show something about the subject that no camera could match. In addition to showing the person, a g...
Chinese(?) coins	Based on your drawing the first one is from the period of the Daoguang 道光 Emperor, the 8th Qing emperor who ruled from 1820 to 1850. The second is from the reign of the Shunzhi 順治 Emperor, who was the third Qing emperor, ruling from 1644 to 1661. The side with Chinese characters just says the name of the empepror and t...	[ "Chinese coinage during the Spring and Autumn and Warring States periods includes some of the earliest coins produced in the world. However, they were mostly not the typical round shape of modern coins. They included cowrie shells, ant nose money, spade-shaped money and knife-shaped money.\n", "Chinese coins of t...
How are artifical sweeteners digested by the body?	It depends on the sweetener. They are very different molecules. Aspartame, brand name Equal, is basically a tiny protein molecule with an alcohol molecule stuck on the end. It gets broken apart into its component parts and they are digested separately. This generates about 4 calories per gram-- the same as sugar. Th...	[ "BULLET::::- Low-calorie sugars and artificial sweeteners are often made of maltodextrin with added sweeteners. Maltodextrin is an easily digestible synthetic polysaccharide consisting of short chains of glucose molecules and is made by the partial hydrolysis of starch.\n", "Sweet taste signals the presence of ca...
I have some hypothetical questions about magnetic spheres.	Based on what I can understand of your question you are horribly misunderstanding magnetism. Reason: Your spheres are impossible. Without a path to complete what I generally hear termed the "magnetic circuit" you are effectively looking at some sort of magnetic monopole type structure which is (as far as science unde...	[ "The spheres are to in diameter (larger than Geomag), approximately in weight, and are prone to surface corrosion, unlike most other magnetic construction toys. The bars with magnets at each end are long, or , or and flexible, or short rigid curves. Panel shapes include two types of interlocking triangles, interloc...
Why don't we create a small scale nuclear reactor to power cars individualy?	The cost is far too high for it to be reliable and consistent, and the waste produced would be difficult to manage, depending on the type of fuel used.	[ "Reactors used in nuclear marine propulsion (especially nuclear submarines) often cannot be run at continuous power around the clock in the same way that land-based power reactors are normally run, and in addition often need to have a very long core life without refueling. For this reason many designs use highly en...
in terms of microeconomics, how does piracy of digital goods affect supply, demand, sale, price, etc.?	Within a narrow context, piracy has two effects. It depresses or increases potential demand for a product at the rate at which the file spreads through a population. There's less than 1 to 1 correlation between the number of people with an illicit copy who drop out of the demand population. The number of people who wil...	[ "According to the same study, even though digital piracy inflicts additional costs on the production side of media, it also offers the main access to media goods in developing countries. The strong tradeoffs that favor using digital piracy in developing economies dictate the current neglected law enforcements towar...
why do emojis show up differently on ios vs android devices?	Well consider it like a different font type. It still conveys the same information, but it is a separate style.	[ "The second problem relates to technology and branding. When an author of a message picks an emoji from a list, it is normally encoded in a non-graphical manner during the transmission, and if the author and the reader do not use the same software or operating system for their devices, the reader's device may visua...
Did the Romans have some concept of 'standardized spelling'?	I think this depends entirely on what era you're looking at. So far as I am aware, there wasn't an institution in Rome that said "Ok, everyone, amicus is a second declension noun, not a fourth declension one!" I'm not sure how linguists would approach this issue, so I can't speak to how everyone agreed that it should ...	[ "In its spelling, it retains medieval Latin orthography, sometimes using \"oe\" rather than \"ae\", and having more proper nouns beginning with \"H\" (e.g., \"Helimelech\" instead of \"Elimelech\"). Unlike the edition of Rome, it standardizes the spelling of proper names rather than attempting to reproduce the idio...
if someone were to dip a live electrical wire into the ocean, wouldn't everyone swimming in the ocean at that time be electrocuted?	No. Electricity moves from one place to another place, along the path of least resistance. It doesn't spread out and electrocute everything that happens to be in the same body of water. In the case of an electrical wire in the ocean, it'd likely prove dangerous to things within a few feet of it (maybe even a few doz...	[ "There is no visible warning to electrified water. Swimmers will be able to feel the electricity if the current is substantial. If the swimmers notice any unusual tingling feeling or symptoms of electrical shock, it is highly likely that stray currents exist and everyone needs to get out. Swimmers should always swi...
why did we domesticate chickens for the use of eggs and not other birds?	Most likely because they tend to be slow, their eggs full of protein and they can't fly. Chickens are probably a lot easier to domesticate over a pigeon, for example.	[ "The domestication of poultry took place several thousand years ago. This may have originally been as a result of people hatching and rearing young birds from eggs collected from the wild, but later involved keeping the birds permanently in captivity. Domesticated chickens may have been used for cockfighting at fir...
Does the "subconscious" really exist?	As DeathSquid5000 said, it's really just a catch-all term for cognitive processing that you're unaware of, for example, a lot of decision-making processes (most of which seem to occur outside of awareness, although you'll likely be inclined to think otherwise). In terms of the singular, nebulous, primal, almost mystic...	[ "The word \"subconscious\" represents an anglicized version of the French \"subconscient\" as coined by the psychologist Pierre Janet (1859–1947), who argued that underneath the layers of critical-thought functions of the conscious mind lay a powerful awareness that he called the subconscious mind.\n", "Charles R...
Does tourettes exist in all languages and if so does it manifest itself differently in different cultures?	Verbal tourettes is just a very small part of the disorder at about 12% of the individuals who have it and of those only a small percent expel curse words. Most manifestations occur in physical repetitive motions such as tapping or twitching and can be as grand as siting down repeatedly. So yes it happens in all cult...	[ "Tripura has several diverse ethno-linguistic groups, which has given rise to a composite culture. The dominant cultures are Bengali, Manipuri, Tripuris, Jamatia, Reang, Naitong, Koloi, Murasing, Chakma, Halam, Garo, Hajong, Kuki, Mizo, Mogh, Munda, Oraon, Santhal, and Uchoi.\n", "In South Asia, they are known as...
How close to the Moon would you have to be before you would fall to the Moon instead of to the Earth?	"Zero velocity" is a little ambiguous in this context, since the earth and the moon are each moving with a different velocity. Let's take that to mean zero velocity with respect to the center of mass of the Earth-Moon system. In that case, we can define r_moon and r_earth to be your height from the center of each body,...	[ "BULLET::::- (~3 meters in diameter) may have passed as close as 0.97 lunar distances (371,000 km) from Earth (0.68 lunar distances (261,000 km) from the Moon on either April 14 or 15th, 2014, but the nominal orbit calculates an approach of 1.29 lunar distances (495,000 km) from Earth (1.23 lunar distances (473,000...
What would it mean if we proved that P = NP, or P != NP ?	A side remark: polynomial time is usually taken to be a short amount of time, and in the limit of large inputs it is much much much smaller than exponential time. However, even if someone proved that P=NP, it could still be the case that the complexity of a problem scales as n^(100000000) or something ridiculous like...	[ "The question of whether P equals NP is one of the most important open questions in theoretical computer science because of the wide implications of a solution. If the answer is yes, many important problems can be shown to have more efficient solutions. These include various types of integer programming problems in...
Why are mid-air manifestations of electricity jagged? (i.e. sparks, lightning bolts etc.)	This was a really interesting question that I didn't know the answer to so I looked it up. [This Scientific American article](_URL_0_) does a pretty good job of explaining it.	[ "ESD can create spectacular electric sparks (lightning, with the accompanying sound of thunder, is a large-scale ESD event), but also less dramatic forms which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices. Electric sparks require a field strength above app...
"Photons" of different EM spectrum?	All electromagnetic waves are made of photons -- visible light, radio waves, X-rays, gamma rays, ultraviolet light, infrared light, you name it.	[ "EM radiation can have various frequencies. The bands of frequency present in a given EM signal may be sharply defined, as is seen in atomic spectra, or may be broad, as in blackbody radiation. In the photon picture, the energy carried by each photon is proportional to its frequency. In the wave picture, the energy...
why is being deaf or blind much more common than say having no taste, touch, or smell?	Part of it is confirmation bias. Blind people are really obvious, deaf people are fairly obvious. You wouldn't know someone couldn't smell or taste just by looking at them. Localized loss of touch is not uncommon. But you have so many touch receptors in so many places, there are few conditions that will systemicall...	[ "This interplay of various ways of conceiving the world could be compared to the experience of synesthesia, where stimulus of one sense causes a perception by another, seemingly unrelated sense, as in musicians who can taste the intervals between notes they hear (Beeli \"et al\"., 2005), or artists who can smell co...
how can the un give sanctions for nuclear weapons to some countries and not to others?	The nuclear nonproliferation treaty recognized the then-nuclear states as legit, and called on them to disarm to some degree (which they haven't) and tried to prevent nuclear capability from further spreading. It's called, creatively, The Treaty for the Non-Proliferation of Nuclear Weapons (NPT) of 1970. Edit: India...	[ "According to the Charter of the United Nations, only the UN Security Council has a mandate by the international community to apply sanctions (Article 41) that must be complied with by all UN member states (Article 2,2). They serve as the international community's most powerful peaceful means to prevent threats to ...
What language/script is this? Where can I have it translated?	This is almost certainly Yiddish(essentially late medieval German in Hebrew script). I do not myself read Yiddish but /r/Judaism and /r/Yiddish would be able to help here.	[ "The text has also been widely translated under different titles into Asian languages such as Burmese, Khmer, Thai, Malay, Persian, Sinhala, as well as into Dutch, English, French, German, Greek, Spanish and Russian. \n", "It has been translated into at least 17 languages, including Hebrew, Spanish, Dutch, Hungar...
What oscillates in light?	The thing that oscillates is the electromagnetic field of the photon itself. It is a self-sustaining electromagnetic field. A changing magnetic field induces an electric field, and vice versa.	[ "When discussing the quantum theory of light, it is very common to use an electromagnetic oscillator as a model. An electromagnetic oscillator describes an oscillation of the electric field. Since the magnetic field is proportional to the rate of change of the electric field, this too oscillates. Such oscillations ...
Medieval French translation help (again!)	Looks like an ancient french version of the actual « cuillère » ("spoon"). Source : french and historian	[ "The Medieval Translator (French \"Traduire au Moyen Age\") is an annual volume of studies dedicated to translation in the Middle Ages and the study of translation of medieval texts. First published in 1991, it has been published since 1996 by Brepols. The volume comprises a collection of papers read at the Cardiff...
Who were the Desert Fathers? What was their impact on early Christianity? What happened to them and the desert monastic movement?	The desert fathers emerge toward the end of the fourth century as Christianity transitioned from a fringe cult to an accepted community in the pantheon of faiths. While earlier Christian communities had faced persecution and martyrdom, in this new period asceticism became the hallmark of true commitment to the faith. T...	[ "The Desert Fathers were Christian hermits, and ascetics who had a major influence on the development of Christianity and celibacy. Paul of Thebes is often credited with being the first hermit monk to go to the desert, but it was Anthony the Great who launched the movement that became the Desert Fathers. Sometime a...
how did my plane yesterday depart late but it was able to reach the destination before it's original scheduled arrival time?	We generally do not fly "as fast as we can go". We fly at a speed that is calculated by our airline to be a nice balance of speed and fuel economy. However, if a flight is behind schedule and could potentially impact the departure times of flights further down the line, then we can be authorized to kick it up a notch, ...	[ "After flying , the aircraft passed the control tower back at Carswell on March 2 at 10:22 am, marking the end of the circumnavigation, and landed there at 10:31 a.m. after having been in the air for 94 hours and one minute, landing two minutes before the estimated time of arrival calculated at take-off.\n", "BUL...
How did Taiwan handle the massive influx of Chinese refugees following the Chinese Civil War? How did the Kuomintang "set up shop", so to speak?	In the memoir of Taiwanese author [Chiung Yao](_URL_0_), she said because her father was an intellectual and easily found another professor job, her family received a Japanese style house the size of twenty ["tatami"](_URL_1_) from the university. Her family was still extremely poor despite being better off than most r...	[ "Prior to the 1950s emigration from Taiwan (ROC) (then called Formosa) was negligible. In 1949, the Chinese Communist Party took control of mainland China, and 2 million refugees, predominantly from the Republic of China (ROC) Nationalist government, military, and business community, fled to Taiwan. Since the 1950s...
Why did the Tlaxcalans allow Cortes to remain in Tenochtitlan/Mexico?	There's two big misconceptions that are commonly held about post-Conquest Mexico: that Hispanicization progressed rapidly and the native population faced discrimination equally. I covered in a [previous post](_URL_2_) how life in Mesoamerica basically continued on with business as usual for almost a generation after th...	[ "Cortés stayed in the city of Tlaxcala for 20 days and forged an alliance with the Tlaxcalans to bring down Tenochtitlan. Cortes added 6,000 Tlaxcala warriors to his ranks and arrived to Tenochtitlan in November 1519. They were received by Emperor Moctezuma II, who understood the potential danger of a Spanish-Tlaxc...
moving matter from a neutron star	If you were to bring a chunk of neutron star matter to the Earth, it would expand. Before I can explain this I have to explain what's actually going on in a neutron star. When a star 'dies' it collapses in on itself and blows off its outer layers of gas. The core that's left is called a stellar remnant. This remnant ...	[ "When they are formed, neutron stars rotate in space. As they compress and shrink, this spinning speeds up because of the conservation of angular momentum—the same principle that causes a spinning skater to speed up when she pulls in her arms.\n", "These stars gradually slow down over the eons, but those bodies t...
we see ordinary city pigeons in most major cities, but never in between (e.g., chicago and denver but not in north dakota). how do they get there?	1. Pigeons and doves are the same thing. People tend to call them pigeons in cities and doves in the country. They are common in cities and in rural areas. North Dakota has seven types of pigeons/doves. 2. City pigeons are often domesticated pigeons that were released back into the wild (in this case, cities). So huma...	[ "Several species of local marshland birds and water birds including the little egret, the little green heron and cinnamon bittern, and migratory birds form Northern Hemisphere have been spotted there. Binoculars will come in handy for bird watching. The visitors can also enjoy a leisurely walk, jog or cycle along i...
it is said that there are more possible games of chess than there are atoms in the observable universe. how is something like this calculated?	I don't think there is an easy way to calculate the exact number of games. One can estimate though and get a ballpark figure. Claude Shannon, father of information theory, was the first one to publish his ballpark estimate. It is based on the assumption that, on average the number of moves available to white, and then ...	[ "BULLET::::- Chess on an Infinite plane: One type of infinite chess. Seventy-six pieces are played on an unbounded chessboard. The game uses orthodox chess pieces, plus guards, hawks, and chancellors. The absence of borders makes pieces effectively less powerful (as the king and other pieces cannot be trapped in co...
since a country can print its own currency indefinitely, why can't the us for example just arbitrarily pay off all its debt that way?	Yes. The more money in circulation, the less it's really worth, period.	[ "Another, less used means of maintaining a fixed exchange rate is by simply making it illegal to trade currency at any other rate. This is difficult to enforce and often leads to a black market in foreign currency. Nonetheless, some countries are highly successful at using this method due to government monopolies o...
How did Egypt become so thoroughly Arabised?	Egypt was under the control of the Arabs directly for six consecutive centuries, and then under the control of people who likely used Arabic for government functions due to the varied origins of the Mamluks themselves. So, in short, for almost a thousand years it was under the control of administrators who spoke Arabic...	[ "During the 20th century, Egypt experienced several waves of revolutions to regain control of their nation from colonial rulers as to create a modern nation-state. Much of Egypt was Muslim at the time although there were significant numbers of Jews and Christians as well, but many of the political revolutions that ...
Has the U.S. Military ever conducted assassinations of foreign leaders in the past?	Going off that, of the assassinations done by either CIA or military was it widely known who did it or did people think it was different countries?	[ "FAR is most significantly known for having killed the U.S. ambassador to Guatemala, John Gordon Mein, in 1968. Also killed that year were two U.S. military advisers, Colonel John Webber and Ernest Munro, although they might have been killed at the command of PGT leader Leonardo Castillo Johnson.\n", "In the Unit...
terryology.	He's just mixing up multiplication and addition. He thinks 1 X 1 is the equivalent of holding up one index finger for each hand and seeing 2 fingers. He also said everyone thinks √4 is 2, so √2 must be 1, but it's not because we're told it's 2, which proves that he knows nothing about simple arithmetics.	[ "Occupational therapy—often abbreviated OT—is the \"use of productive or creative activity in the treatment or rehabilitation of physically, cognitively, or emotionally disabled people.\" Most commonly, occupational therapists work with people with disabilities to enable them to maximize their skills and abilities....
what is the difference between a bison and a buffalo?	You can find pictures on the internet easily so let me explain why the words got mixed up. We keep them separate because they aren't that closely related. * ~~In Europe, Asia, and Africa there are only Buffalo. There used to be Bison in Europe but they went extinct thousands of years ago.~~ I read a little more ab...	[ "The American bison (\"Bison bison\") is a North American species of bison, also commonly known as the American buffalo. These bison once roamed the grasslands of North America in massive herds; their range roughly formed a triangle between the Great Bear Lake in Canada's far northwest, south to the Mexican states ...
how to best describe/explain ionization energy and electron affinity?	Ionization energy is the amount of energy that must go into an atom to remove an electron. As you remove more electrons, the amount of energy required becomes larger and larger because of the effective nuclear charge. This pulls the electrons closer and closer to the nucleus, which results in higher energy to pull it o...	[ "Electron affinity can be defined in two equivalent ways. First, as the energy that is released by adding an electron to an isolated gaseous atom. The second (reverse) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion. Either convention can ...
What happened to the Rockefellers fortune?	This is a complicated question because when people see that the brothers had such a large sum they automatically assume the same thing you did. That wealth typically creates more wealth. The trouble is no one takes into account the time value of money. Which states that money today is more valuable than money tomorrow ...	[ "At the time of his death, \"Forbes\" estimated Rockefeller's net worth was $3.3 billion. Initially, most of his wealth had come to him via the family trusts that his father had set up, which were administered by Room 5600 and the Chase Bank. In turn, most of these trusts were held as shares in the successor compan...
what would happen if a massive planet came very close to earth, as in, would our gravity change?	The planets would disrupt each others orbit, draw each other closer together and then shoot apart again, over and over and over like this for years as gravity ripped chunks off of each with every pass, each time getting closer together. Those chunks would hit both planets turning them into lifeless balls of molten r...	[ "The absence of close orbiting super-Earths in the Solar System may also be the result of Jupiter's inward migration. As Jupiter migrates inward, planetesimals are captured in its mean-motion resonances, causing their orbits to shrink and their eccentricities to grow. A collisional cascade follows as their relative...
which one is more environmental friendly - eating with a disposable plate and cutlery to save water; or eating with normal plate and wash them with water and soap?	Washing your dishes is more environmentally friendly. The water is not destroyed in the washing process.	[ "Besides ingredient quality, there are also sanitation requirements. It is important to ensure that the food processing environment is as clean as possible in order to produce the safest possible food for the consumer. A recent example of poor sanitation recently has been the 2006 North American E. coli outbreak in...
why do animals in a particular ecological niche often look so similar even if they are completely unrelated?	This is a concept called "convergent evolution." Basically, if the pressures on one creature were such that flight was advantageous to survival in a particular environment, those same pressures could easily select for similar variations should they happen to randomly arise in another species. This is particularly t...	[ "In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, and so face the same environmental factors. When occupying similar ecological niches (that is, a distinctive way of life) similar problems can lead to similar solutions. The British anatomist Richard Owe...
non-native speaker here, why is "biannually" considered to be twice a year, but "biweekly" only once every two weeks instead of two times per week?	"Biweekly" can refer to either twice a week or two times a week. The same for "bimonthly" (i.e. once a month or two times a month). The issue stems from the prefix "bi-", which is inherently ambiguous in that it can mean either occuring twice or occuring every two. English offers us an alternative with 'ann...	[ "Biweekly means either occurring every two weeks, or occurring twice every week. This causes ambiguity when the term is used. As a result, in the United Kingdom, Ireland, Australia and New Zealand, the term fortnightly is more commonly used for an event that occurs every two weeks.\n", "The custom of \"At Home\" ...
why are people/businesses moving to the south and not detroit?	A lot fewer unions in the south is a big part. Also rules and regulations setup over decades that are unfriendly to new business in Detroit.	[ "All of these changes in the area's transportation system favored low-density, auto-oriented development rather than high-density urban development, and industry also moved to the suburbs. The metro Detroit area developed as one of the most sprawling job markets in the United States by the 21st century, and combine...
Would a helium filled balloon float on Mars?	You can solve this with the ideal gas law, pV = nRT. Pressure x Volume = #molecules x ideal-gas-contant x temperature. Mars' atmosphere is made of carbon dioxide, which has a molar mass of 44g/mol. Air, which is basically an 80-20 mix of nitrogen and oxygen, has a molar mass of 29 g/mol. Helium is 4g/mol. Helium is ...	[ "BULLET::::- Mars has a very thin atmosphere – the pressure is only 1/160th of earth atmospheric pressure – so a huge balloon would be needed even for a tiny lifting effect. Overcoming the weight of such a balloon would be difficult, but several proposals to explore Mars with balloons have been made.\n", "Fully i...
Japan and the UK were allies in WW1. What happened to this alliance post WW1 and pre WW2?	Japan's entry into the First World War was a highly measured response. Japan acted against German interests in the Pacific, most notably invading the German concession at Tsingtao. Japan did not put its economy on a wartime footing and only after repeated entreaties by the British did she send some military force into ...	[ "The onset of the First World War in Europe eventually showed how far German–Japanese relations had truly deteriorated. On 7 August 1914, only three days after Britain declared war on the German Empire, the Japanese government received an official request from the British government for assistance in destroying the...
how do glute muscles become weak?	The same way any other muscle gets weaker. Over time and extended periods of low use, they deteriorate and lose mass.	[ "Muscle coactivation allows muscle groups surrounding a joint to become more stable. This is due to both muscles (or sets of muscles) contracting at the same time, which produces compression on the joint. The joint is able to become stiffer and more stable due to this action. For example, when the bicep and the tri...
why is fertilizer the primary ingredient in many homemade bombs?	It's the nitrogen//nitrogen-based chemicals in the fertilizer. The nitrogen stuff is great for growing crops... but it's also good for explosives. You can search for "nitrogen explosive compounds", but read here this one example of why: _URL_0_	[ "A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin (other than liming materials) that is applied to soils or to plant tissues to supply one or more plant nutrients essential to the growth of plants. Many sources of fertilizer exi...
how is it that someone (like myself) is allergic to almost every antibiotic? what makes the body hate them so much?	Essentially an allergy is an immune response to a foreign substance. For you, the antibiotics has 'proteins' antigens which trigger the white cells of you immune system to attack them. This appears as massive inflammation due to degranulation of mast cells releasing imflammatory proteins etc. Typically presenting as ...	[ "Aside from these ambient allergens, allergic reactions can result from foods, insect stings, and reactions to medications like aspirin and antibiotics such as penicillin. Symptoms of food allergy include abdominal pain, bloating, vomiting, diarrhea, itchy skin, and swelling of the skin during hives. Food allergies...
Is cancer a preventable disease?	You addressed it in your post, but I just want to point it out as well : "Prevention" in medicine is like "safety" in engineering. It depends on what you mean by "prevention". If by prevention you mean complete prevention, as in cancer risk is gone...no. Not going to happen. But for what you are asking, yes. You can...	[ "Cancer prevention is defined as active measures to decrease cancer risk. The vast majority of cancer cases are due to environmental risk factors. Many of these environmental factors are controllable lifestyle choices. Thus, cancer is generally preventable. Between 70% and 90% of common cancers are due to environme...
What is the maximum rate of rainfall possible?	There are some great answers so far, but I think everyone is missing the point. /u/evilmercer is not asking what the maximum observed rate has been historically, but what the maximum theoretical rate of rainfall is. Given the wording of his question, I believe he is seeking two separate answers: * What is the maximu...	[ "The maximum annual rainfall ever recorded was 1500 mm for every year. The highest rainfall recorded in a single day was 850 mm. The average total annual rainfall is 1500 mm. The average annual temperature is 32 °C, and the average maximum temperature is 35 °C, while the average minimum temperature is 28 °C. In the...
Do the Strong and Weak Forces have a field like Gravitation and EM?	Yes, but unlike gravity and EM, their fields have very short interaction lengths. They are mediated by W+-/Z bosons and gluons, respectively.	[ "The strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). The strong force is the fundamental force mediated by gluons, acting upon quarks, antiquarks, and the gluons themselves. The (aptly named) strong interaction is th...
What are some lesser known epidemics of the past?	The bubonic epidemic no one ever hears about: [The Plague of Justinian](_URL_0_). It is estimated to have killed over twenty-five million people, only 25% of the casualties caused by the Black Death, but the PoJ was the first recorded instance of a (confirmed) Yersinia pestis epidemic.	[ "It appears that epidemic meningitis is a relatively recent phenomenon. The first recorded major outbreak occurred in Geneva in 1805. Several other epidemics in Europe and the United States were described shortly afterward, and the first report of an epidemic in Africa appeared in 1840. African epidemics became muc...
why can you only know an electron's position if you give up on knowing its momentum and vice versa?	It's not that you don't know the electron's momentum and position at the same time. Electrons don't have well-defined momentum and a well-defined position at the same time. Electrons operate under the rules of quantum mechanics, where they actually exists as a probability wave. And the position and momentum of...	[ "This principle of uncertainty holds for many other pairs of observables as well. For example, the energy does not commute with the position either, so it is impossible to precisely determine the position and energy of an electron in an atom.\n", "An elegant illustration of the uncertainty principle is Heisenberg...
Are thoughts physical objects?	Thoughts are webs of electricity traveling through different sections of your brain. Most are reactionary responses to outside stimuli, and then chained together based on memories that surface during the process... I try not to think about it really; that our entire lives are just a chain of reactionary electric char...	[ "Before asking whether any such objects exist outside me, I ought to consider the ideas of these objects as they exist in my thoughts and see which are clear and which confused. (Descartes, Meditation V: On the Essence of Material Objects and More on God's Existence).\n", "BULLET::::- \"Brain and Consciousness\" ...
why on mobile devices can i find nothing except live and cover songs on youtube?	Youtube checks the user-agent header and blocks certain videos from appearing on mobile. Music videos seem to be a popular choice for such filtering. I don't know why it's done, but you can get around it. You need to change your user agent header so you appear to be coming from a desktop browser. (or strip it altogeth...	[ "There are now over 100,000 videos posted on YouTube using “Sa Isang Sulyap”—all in all, these videos have been viewed more than 400 million times. It is also one of the most downloaded songs today by mobile phone users.\n", "YouTube (owned by Google Inc.) is the premier site for finding music videos for both ind...
why is the distribution of elements on earth not uniform?	Basically because each element is chemically unique, and therefore behaves differently to other elements in given conditions. Take for example crystallisation from a magma. As the magma cools, certain elements are able to form stable crystalline structures (minerals). Different minerals can start to crystallise at d...	[ "The organization of elements on the periodic table in to horizontal rows and vertical columns makes certain relationships more apparent (periodic law). Moving rightward and descending the periodic table have opposite effects on atomic radii of isolated atoms. Moving rightward across the period decreases the atomic...
when smoking, why does your throat hurt only when you breathe in air?	You're breathing in hot air and chemicals that get absorbed by your lungs and cooled down by the time they're breathed out. You should probably look into quitting it's super unhealthy :).	[ "Many compounds of smoke from fires are highly toxic and/or irritating. The most dangerous is carbon monoxide leading to carbon monoxide poisoning, sometimes with the additive effects of hydrogen cyanide and phosgene. Smoke inhalation can therefore quickly lead to incapacitation and loss of consciousness. Sulfur ox...
Why can Phosphate have five bonds? (More than an octet)	First off, I want to say that d-orbitals are not involved in the bonding of hypervalent main group compounds like PCl5. The central atoms in molecules like PCl5, SF6, etc. still obey the octet rule. Many introductory resources claim otherwise, but there is ample computational evidence that that this is the case. I can ...	[ "The octet rule is a chemical rule of thumb that reflects observation that elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. The rule is especially applicable to carbon, nitrogen, oxygen, and the halogens, but als...
The New Testament largely covers the final three years of Jesus's life; is there any more known about the first 30 years of his life?	The simple answer is no. Apocryphal sources exist but are universally pretty late. Even the length of Jesus' ministry isn't exactly known. We assume it was a three year ministry because of the Gospel of John, but the interesting point there is that the Gospel of John isn't a common source for information concerning th...	[ "For a \"century and a half\", then, after Jesus' death, we have no means whatever of substantiating even the existence of the Gospels, as now bound up in the New Testament. There is a perfect blank of 140 years; and a most serious one it is.\n", "Although Lindsey did not claim to know the dates of future events ...
how wind can push my car sideways when my wheels are pointed straight forward?	Eh? When does your car move sideways?	[ "Before entry to the bend, the car is turned towards the bend slightly, but quickly, so as to cause a rotating motion that induces the rear of the car to slide outwards. Power is applied which applies further sideways movement. At the same time, opposite lock steering is applied to keep the car on the desired cours...
why is it that there are plenty of tropical small islands throughout the pacific (guam, us virgin islands, etc) but there are hardly such islands in the atlantic ocean?	The pacific ocean is a hotbed for volcanic activity. Under water volcano explodes, creates an island, plants and animals move in. Pretty neat	[ "The Hawaiian Islands are about from North America and from Asia, and it is because of this isolation that the Hawaiian Islands have extraordinary numbers of unique species. Only a species that could fly or swim immense distances could reach the archipelago. But whereas Polynesians, and later, Europeans, have large...
how do night contacts work?	My understanding is they reshape the eye. The degree of how concave or convex the lens of the eye causes near sightedness or far sightedness. Sleep contacts temporarily shape your eyes back to neutral.	[ "Hand signals are a form of sign system used by divers to communicate when underwater. Hand signals are useful whenever divers can see each other, and some can also be used in poor visibility if in close proximity, when the recipient can feel the shape of the signaller's hand and thereby identify the signal being g...
based off of this photo that keeps going around reddit what would actually happen to the moon and this person.	Alot of shrapnel, if not that then the lack of oxygen after a couple of days.	[ "In November 1969, a nude photo of Wilson made a trip to the Moon. As a joke, NASA ground staff hid a small nude photo of her (along with fellow playmates Angela Dorian, Cynthia Myers and Leslie Bianchini) inside the schedule of Apollo 12's mission commander, Pete Conrad. Although it is certain that the photo made ...
The lack of a strong socialist party in the US linked to the absence of feudalism?	I think the contention that feudalism was a heavy contributor to socialism is a pretty weak one. What is Lipset's evidence for that assertion? I think the rise of socialism is a heck of a lot more complex than "the struggle against feudalism and the ravages of industrialization took on a class conscious character in a ...	[ "Socialism in the United States has been composed of many tendencies, often in important disagreements with each other as it has included utopian socialists, social democrats, democratic socialists, communists, Trotskyists and anarchists. The socialist movement in the United States has historically been relatively ...
why do we still take test and learn the same as how people did in the whole of history when technology has advanced so far?	Learning has advanced a great deal since formal education began. There are some things that have become redundant, and some things may seem useless. For instance, why bother learning that there are 4 quarts in a gallon when I can just look it up? But many people, myself included, would argue that a fundamental understa...	[ "\"Section 1:\" The use of Science has improved tremendously in many ways for humans. The knowledge of science has grown considerably. However, the way we manage knowledge has remained the same for centuries. We are no longer able to access the breadth of scientific breakthroughs. Alternatively, the technology has ...
why is norway so horrendously expensive?	It is difficult to transport anything to Norway because the land is very difficult to traverse and the sea can be incredibly rough. However though it does have large income from oil it also has an extremely generous social welfare system and that means high taxes and that means expensive goods and services.	[ "BULLET::::- Cost of living. Norway is among the most expensive countries in the world, as reflected in the Big Mac Index and other indices. Historically, transportation costs and barriers to free trade had caused the disparity, but in recent years, Norwegian policy in labor relations, taxation, and other areas hav...
Prior to the rise of Ataturk, what made someone in the Ottoman Empire a “Turk”?	Short answer: ethnicity and language (both in place well before the 19th century), plus some negative experiences with other nationalities (mostly in the 19th-20th centuries, triggering the rise of Turkish nationalism.) When you read the memoirs of the future political and military leaders of Turkey, at one point almos...	[ "With the establishment of the Turkish National Movement, the partitioning of the Ottoman Empire, and the abolition of the sultanate, the Ottoman era and the Empire came to an end, and with Atatürk's reforms, the Turks created the modern, secular nation-state of Turkey on the political front. On 3 March 1924, the O...
I hoped this isn't looked down upon in this subreddit, but I think that it's inevitable. Either way, I'm curious. How accurate are the age of empire games?	Off the top of my head: Age of Empires 3 is completely made up. * Specifically, there were no Ottomans in the New World and no Russians except on the Pacific Coast * The Ottomans did [invade](_URL_1_) Malta in 1565. New Brunswick is a real place. * The [Sepoy Rebellion](_URL_2_) really did happen, and I remember so...	[ "On 24 February 2017 Ashen announced a sequel to \"Terrible Old Games You've Probably Never Heard Of\", titled \"Attack of the Flickering Skeletons: More Terrible Old Games You've Probably Never Heard Of\", again through Unbound, was released on 2 November 2017.\n", "Alessio Cavatore comments: \"Anyone who knows ...
if trees initially were non-biodegradable, and a fungus adapted to degrade them could the same be done for plastic?	Sure and we are working on it. But its a slow process and we are producing literally thousands of tonnes of plastic every day. Recycle.	[ "Biodegradable additives have the potential to significantly reduce the accumulation of plastics in the environment. Plastics are ubiquitous in everyday life and are produced and disposed of in huge quantities each year. Many common plastics, such as polyethylene, polypropylene, polystyrene, poly(vinyl chloride), a...
what is software and how does it all work?	That's a very broad question, so rather than go into detail, I'll just give some very high-level answers, and you can ask for clarification as needed. > how does software work? Software is simply a set of instructions for a computer to follow. The "how" is fairly complex, but it boils down to setting voltages on...	[ "\"Software\" refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. Software is that part of a computer system that consists of encoded information or computer instructions, in contrast to the physical hardware from which the system is built. Computer software in...
why do different regions of usa sell varying octanes of gas? i can buy 85 octane in idaho, but can't find anything less than 87 in arizona.	Elevation. "Octane" is a description of how much compression the fuel can be put under before it spontaneously ignites. The higher the octane number, the more pressure the fuel can take before it just ignites. An engine wants to take the fuel/air mixture as close to this point as possible (but not past it) before the ...	[ "The octane rating of typical commercially available gasoline varies by country. In Finland, Sweden and Norway, 95 RON is the standard for regular unleaded gasoline and 98 RON is also available as a more expensive option. \n", "Most states do not mandate certain standard gasoline grade octane ratings. In the Unit...
what causes laziness? is it a physical condition?	I guess everyone is too lazy to reply, OP. There are some good explanations for this, but my vague, non-scientific understanding is, it is indeed a physical condition, one that we inherited from our ancestors. I'm sure you can find a more technical/accurate/correct explanation of this, but here's the gist of it. Our b...	[ "Laziness is a habit rather than a mental health issue. It may reflect a lack of self-esteem, a lack of positive recognition by others, a lack of discipline stemming from low self-confidence, or a lack of interest in the activity or belief in its efficacy. Laziness may manifest as procrastination or vacillation. St...
What was the basis of the Nazi war machine? How did the managed economy of the Nazis work?	The Nazis did not nationalize all off industry; now they forced Jews to sell their businesses for peanuts to non-Jewish owners, under the policy of Aryanization/Arisierung - that was in 1938. However they placed limited on what owners could do with their property, effectively the nazi state managed an increasing part ...	[ "Hitler completely reorganized the economic landscape in Germany. The economic chamber of the Third Reich consisted of over two hundred organizations and national councils involved in industry, commercial, and craft lines. Large public works programs, such as the construction of the Autobahn, stimulated the economy...
how to talk to children	Reading your username makes me question your intentions.	[ "BULLET::::- \"So Much to Say\" (1980), regarding the language of children from birth to age five. It proposes that children are driven to talk because they have \"something to say,\" have private emotions and thoughts to report.\n", "Children who have delayed speech or other mental illnesses cannot grasp the con...
did thousands of people die trying 'food' that we now know is poisonous?	Probably. And more than a few avoided food that we know is fine. Many people in Europe in the 1400s thought fruit was slightly poisonous and shouldn't be given to young children. Many people used to think tomatoes were toxic.	[ "There have been cases where people died after eating foods containing palytoxin or poisons similar to it. In the Philippines people died after eating \"Demania reynaudii\", a crab species. After eating bluestripe herring some people died in Madagascar. People who had eaten smoked fish and parrotfish experienced ne...
When people say some metals are "better" at conducting electricity what does this mean, do they conduct faster or more efficiently?	Both. The conductivity of a material is the constant that relates the current per unit area to the applied electric field. σ = J/E. So using a more conductive material you could design a circuit that moves the same amount of current using a weaker field (more efficient) or moves more current at the same field (faster...	[ "Metals (e.g., copper, platinum, gold, etc.) are usually good conductors of thermal energy. This is due to the way that metals bond chemically: metallic bonds (as opposed to covalent or ionic bonds) have free-moving electrons that transfer thermal energy rapidly through the metal. The \"electron fluid\" of a conduc...
3g/4g.	That's a pretty broad question. I think it's really 3 questions in one, so I'll try to tackle each one individually. What's the difference between 2G, 3G, and 4G? Imagine there is a deliver service. At the beginning they have a very basic setup of just a few horses that run on small local roads. It can only deli...	[ "4G is the fourth generation of broadband cellular network technology, succeeding 3G. A 4G system must provide capabilities defined by ITU in IMT Advanced. Potential and current applications include amended mobile web access, IP telephony, gaming services, high-definition mobile TV, video conferencing, and 3D telev...
Does "smell" expand at different rate, due to surrounding temperature?	Absolutely. When you smell something, molecules from whatever source you're smelling are in your nose. But they had get there from the source - they had move. As it happens, temperature is actually a measure of molecular motion; when things get hotter, the molecules are moving faster. And if the molecules are moving fa...	[ "Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, the kinetic energy of its molecules increases. Thus, the molecules begin vibrating/moving more and usually maintain a greater average separation. Materials which contract with increasing temperat...
Why did American snipers in World War 2 were given the Springfield 1903 when the M1 Garand uses the same type of ammunition and is Semi-Automatic?	Short answer. Because that's what they had on hand. Short answer number 2. Because nobody had bothered developing the M1 as a sniper platform until late in the war. Long answer. Well, nobody was bothering with the M1 until late in the war. Seriously, that's about the gist of it. None of this mess about "Semi autos...	[ "The US entered the war with the M1 Garand as its service rifle. However, due to its size and weight, it was not an ideal weapon for some specialist roles such as engineers, tank crew, radio operators etc. So the lighter and smaller M1 Carbine was introduced in mid-1942. A semi-automatic weapon it used different am...
why are asians buying real estate all over the world, causing a housing crisis in various cities?	It's not "Asian", it's only Chinese. China is about to implode and the people know it. The Chinese stock market is ludicrously overpriced because everyone in China buys stocks on margin, and when the price blips, everyone is leveraged to ridiculous levels and goes bankrupt overnight, so the blip becomes a catastrophe. ...	[ "Housing in Asia has an important role in economic growth. In the early 1990s large urbanization in Hong Kong, Singapore, Thailand, Philippines and other Southeast Asia countries brought about a large housing price appreciation. Asia attracted global economic interest up until the economic crash of 1997. A decade l...
why can we tell an airplane is pitched up when looking straight down the aisle.	Cause of your ears. Your ears have, on the inside of your skull, structures in them that are filled with fluid. The insides of these structures are lined with little sensory nerves that "tell you" where the fluid is. Since gravity pulls the fluid downward, these organs tell you which way is down.	[ "After the initial pitch-up, the pilot places the elevators in the neutral position. Failure to do this will cause the aircraft to continue pitching up during the upright part of the maneuver, and downward in the inverted part, resulting in something resembling a barrel roll. The pilot then applies full aileron, ac...

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