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This may sound daft but, when Comets go though space they appear to have a tail, but space is a vacuum so what would be causing the tail is there is no resistance? | The sun. The tail of a comet doesn't indicate where it is going but rather where it is relative to the sun
Edit: _URL_0_ | [
"In the outer Solar System, comets remain frozen and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from the Hubble Space Telescope observations, but these detections have been questioned, and ... |
[Mores, Customs & Folkways] Do historians use literature to study areas that are well documented or is literature only used if there are no other sources? | Hi, history is more interdisciplinary than the question seems to imply - but it's also a big question.
Cultural history may involve study of fictional literature; for example, a student could examine how Shakespeare's portrayal of the Plantagenets in his history plays related to propaganda reinforcing Tudor / Elizabethan legitimacy. There, literature is a central part of historical study.
In other instances, it may be a way of locating supplementary details not recorded or with minor coverage elsewhere, particularly in the area of social history, customs and everyday life. It is certainly more useful for older history, particularly medieval and early modern, where there is not such a glut of evidence as there is in, for example, the second half of the twentieth century, but in most cases it isn't a binary either/or. And it must always be borne in mind that literature is fictional or mythical, and that there may not be ways to check whether a social habit, for example, was widespread, or fictional. A historian might cite an example from a well-known novel to liven up a book, if it is a good and relevant example.
But it would not be good practice at all to cite, say, a historical novel about the Second World War when writing a factually-based assessment of military planning: there are countless better secondary sources, never mind primary ones, and there may be artistic licence used. | [
"A study of cultural history could include fictional sources such as novels or plays. In a broader sense primary sources also include artifacts like photographs, newsreels, coins, paintings or buildings created at the time. Historians may also take archaeological artifacts and oral reports and interviews into consi... |
if bathroom hygiene is so important why don't we get sick after performing oral sex? | It's more a matter of frequency. If you consider all the times in a day you touch a person (shake hands, etc.) or touch something they touch (doorknobs, etc.), it ads up to a lot of exposure.
If you sucked that many dicks, every day, from that many random people, you would probably get sick a lot. | [
"Women may consider personal hygiene before practicing oral sex important, as poor hygiene can lead to bad odors, accumulation of sweat and micro-residue (such as lint, urine or menstrual blood), which the giving partner may find unpleasant. Some women remove or trim pubic hair, which may enhance their oral sex exp... |
how did people get enough heat to smelt metals before the industrial age? | Coal fire forges are able to reach temperatures of about 1900 degrees C which is more than enough to melt most ‘primitive’ metals such as iron, bronze, copper and steel. | [
"In the Old World, humans learned to smelt metals in prehistoric times, more than 8000 years ago. The discovery and use of the \"useful\" metals — copper and bronze at first, then iron a few millennia later — had an enormous impact on human society. The impact was so pervasive that scholars traditionally divide anc... |
How did scientists measure the radius of atoms and other stuffs? | The most accurate measurements are spectroscopic measurements, in which the energy between states of e.g. atoms is measured. These measurement happen typically with lasers, the frequencies of which can be very well controlled. This is the domain of atomic physics, which is mainly quantum mechanics dealing with discrete energy levels and interaction of matter with photons.
First, remember that the energy states of electrons orbiting a nucleus are quantised.
In a spectroscopic measurement, the frequency of a laser is scanned along a certain range while it passes through a sample, e.g. a gas of atoms. Most of the time, the light will not interact with the sample. Only when the frequency (and thus the energy of the photons that make up the light) is equal to the energy difference of two internal states of the atoms, some of the light can be scattered. In this way, the energy levels of atoms are measured very precisely.
Finally, one can calculate from theory what the electron orbits and the corresponding energies should be. These calculations depend however on some constants, such as the Bohr radius, which describes the distance between the nucleus and the electron in a hydrogen atom. By comparing these calculations to the results of the measurements, these constants are retrieved. (The Bohr radius is now known with a relative uncertainty of 0.2 parts per billion.) These constants can then be used in the theory to calculate the sizes of different atoms.
TL;DR: Experiments measure the spacing between energy levels, theory relate these energy differences to (among other things) the sizes of electron orbits. Both lasers and quantum mechanics are very accurate. | [
"The Van der Waals radius, \"r\", of an atom is the radius of an imaginary hard sphere which can be used to model the atom for many purposes. It is named after Johannes Diderik van der Waals, winner of the 1910 Nobel Prize in Physics, as he was the first to recognise that atoms were not simply points and to demonst... |
How is the infrastructure of the internet built? | The "internet" is simply a huge network. There are many subnetworks, and subnetworks of those networks, but it all is just a big web of connections.
Some huge telecommunication companies own huge fiber optic cable trunks, and they have an agreement to connect them. The top level ISPs are called Tier 1 ISPs. Tier 1 ISPs are the backbone of the internet, and provide service to huge areas. They then sell space to the lower level ISPs, called Tier 2 ISPs. These are the cable internet providers that you probably buy internet from. Tier 3 ISPs are much smaller and buy from Tier 2 ISPs. They are much cheaper and serve small areas.
Each computer on a network is assigned a certain address, called an IP address. Anybody on your network can access your computer through your unique IP address. Think of it like a home address.
Every single server on the internet has an IP address. Web servers do, game servers do, chat servers do, FTP servers, everything. It gets kind of annoying to memorize the IP addresses of every server you want to connect to, so DNS (domain name system) was invented. DNS servers basically route a domain name (such as _URL_0_) to an IP address of the server that its on (such as 74.125.239.135). If you want to try it out, go ahead and type in 74.125.239.135 into your browser.
The DNS root servers are managed by ICANN, which you may have heard of. Sometimes when you want to buy a domain from Godaddy or another registrar, they charge something like a 20 cent ICANN fee. ICANN is basically a nonprofit organization that manages the DNS for the world. You technically don't HAVE to use ICANN DNS servers. You can host your own DNS server and connect to it, and assign as many domain names as you want, but nobody else will be able to go to those domains unless they are using that DNS server. | [
"The infrastructure by which individuals, households, businesses, and communities connect to the Internet refers to the physical mediums that people use to connect to the Internet such as desktop computers, laptops, cell phones, iPods or other MP3 players, Xboxes or PlayStations, electronic book readers, and tablet... |
why does english pop up everywhere? like in anime, and foreign music they just say a line in english and then just back to their respective languages. | Because it's currently seen as the lingua franca of the western world I'd reckon | [
"The foreign language songs are often \"misheard\" into English by the creators and added as subtitles. The words are not translations but soramimis, English words that sound roughly the same as the original lyrics. For example, the animutation title \"French erotic film\" is a soramimi of the original Dutch lyrics... |
Border Between Portugal and Spain | Why specifically these borders and not somewhere else is a question that's beyond me, but Portugal, immediately after its Reconquista, was a County and vassal to the Kingdom of Galicia and later Leon. Afonso I of Portugal became independent mostly with papal support due to his role in driving out the Moors in present day Portugal. Since then borders have shifted and wasn't finalized for a few more hundred years.
The language thing is more clear - Portuguese used to be a lot more like Galician, but in the past thousand years or so they've become more and more different, with Castillan taking hold of the rest of Spain and slowly relegating other Iberian languages like Leonese, Aragonese, Basque, Catalan, and Asturian to secondary status. These languages all have similarities and were a varying degree of difference between Portuguese and Castillan. | [
"Despite these definitions, the Portugal-Spain border remains an unresolved territorial dispute between the two countries. Portugal does not recognise the border between Caia and Ribeira de Cuncos River deltas, since the beginning of the 1801 occupation of Olivenza by Spain. This territory, though under \"de facto\... |
- why do people want ivory so bad and why is it illegal? | Before the advent of plastics, ivory was a very durable alternative to wood. It was considered a luxury good because of its relative scarcity. Most countries have made ivory trade illegal because harvesting it requires killing of endangered elephants. | [
"Ivory has been traded for hundreds of years by people in regions such as Greenland, Alaska, and Siberia. The trade, in more recent times, has led to endangerment of species, resulting in restrictions and bans. Ivory was formerly used to make piano keys and other decorative items because of the white color it prese... |
what is the difference between a credit card reader and a chip-and-pin machine? | Chip and pin cards look [like this](_URL_0_), where you insert the chip into [the reader](_URL_1_), and are prompted to enter a PIN number (like an ATM) before you can make a purchase.
Traditional credit card readers just [swipe the magnetic strip](_URL_2_), and you sign the receipt.
**Edit**: Added images. | [
"POST cards are inserted into an expansion slot, and are available with connectors for the ISA (also supporting EISA), PCI, PCI Express, Mini PCIe (for laptops), Universal Serial Bus, or Low Pin Count bus, or for a parallel port. A typical card for desktop computers has a different bus interface on each edge; a car... |
Is there any hard data to suggest that an animal that has killed a human (like the bear on the front page) is actually likely to repeat this behavior? | Yes there is. Especially if they develop a taste for human meat. Carnivores frequently will attack humans if they are sick, weak, or old. We are quite easy to eat.
about lions in the 1800's that preyed on Keyan construction Workers _URL_0_ | [
"BULLET::::- Initially, there were a number of animal deaths from disease, toxic exposure, maternal killings, and park vehicles. The United States Department of Agriculture investigation found no violations of the Animal Welfare Act for the 29 deaths that happened September 1997 – April 1998.\n",
"BULLET::::- Ini... |
why is it that the majority of the police officers/military in corrupt states defend the corrupted governments? | Cops aren't as oppressed as those they help oppressed. Cops break the law a lot more than your average citizen and their position lets them get away with it. As long as they keep those in power they get to keep their jobs and the perks that come along with it. | [
"Police corruption is a major problem, owing partly to low wage and poor training. The police are generally viewed as the nation's third most corrupt institution, and corruption is widely seen as the main impediment to legitimate crime-fighting. In six years, three police chiefs have been fired for corruption or ab... |
What is the Western Han and Eastern Han in the context of the Han Dynasty? | They are the same dynasty ruled by the same family. The reason why there is the Western Han and the Eastern Han is because in between the two, a man named Wang Mang usurped power from the Western Han emperor and established the Xin Dynasty. After he was defeated and overthrown, the Han dynasty was reestablished in Luoyang (in the east), rather than in the old capital Chang'an (in the west), hence the name "Eastern Han". In some texts you might come across Former Han and Latter Han, which is the same as Western Han and Eastern Han. | [
"Han (, Old Chinese: \"*\") was an ancient Chinese state during the Warring States period of ancient China. It is conventionally romanized by scholars as Hann to distinguish it from the later Han dynasty (漢).\n",
"The Han dynasty (simplified Chinese: 汉朝; traditional Chinese: 漢朝; pinyin: Hàn Cháo; 206 BCE – 220 CE... |
When you rinse out a glass of red wine, why does the water turn gray? | Probably the pH change, which turns the anthocyanidins from their "native" reddish/purple color (at the low pH of the wine) to a blue color which, when diluted, looks a bit gray. This is also a decent technique for removing red wine stains: use a cleaner with a higher pH. _URL_0_ | [
"As red wine ages, the harsh tannins of its youth gradually give way to a softer mouthfeel. An inky dark color will eventually lose its depth of color and begin to appear orange at the edges, and eventually turn brown. These changes occur due to the complex chemical reactions of the phenolic compounds of the wine. ... |
Why aren't we crushed by the weight of the air over our heads? And why don't we feel the weight of the air lifted off of us when we go into a car or building? | [Atmospheric pressure](_URL_0_) is the measure of the amount of force the air exerts on you per area. So it _is_ already measuring the weight of air that exerts on some area. If your room is at one atm, it is pressurized. The weight of air is on you. | [
"The sensation of weight is caused by the force exerted by fluids in the vestibular system, a three-dimensional set of tubes in the inner ear. It is actually the sensation of g-force, regardless of whether this is due to being stationary in the presence of gravity, or, if the person is in motion, the result of any ... |
why do some people who's parents are immigrants have an accent while others don't ? | Accents tend to come more from peers than parents. So someone who grew up in an area where all the friends and neighbors share the same accent, or perhaps went to a private or parochial school where that was the case, will more likely have a similar accent. But when children go to assimilated schools, especially at the younger ages, they're more likely to get that accent than their parents'. | [
"Children are able to take on accents relatively quickly. Children of immigrant families, for example, generally have a more native-like pronunciation than their parents, but both children and parents may have a noticeable non-native accent. Accents seem to remain relatively malleable until a person's early twentie... |
When did winking become a thing? | I can tell you the OED's first use of this definition of the word "wink" if that's useful at all.
1541 Thomas Elyot's *Image of Gouernance* (Governance)
"Of a mayster sturdy and fierce, a lyttell wynke to his seruant is a fearefull commaundement." | [
"Winking is one of the more subtle gestures, usually involving eye contact between those involved. In most cases it is only meant to be known by the sender and their intended receivers, but in some cases can be more widely intended.\n",
"However, winking in the Indian subcontinent often has similar connotations a... |
why do we use olive oil instead of frying oil when stirfrying vegetables? | Properly stir-frying anything requires using really high temperatures.
Most olive oil has a relatively low smoke point (the temperature at which it starts to break down & smoke). Stir-fry oils are generally things that handle temperatures better like corn, peanut, canola & soy.
There's also the bit that olives are not native to Asia, where stirfry recipes are from so the flavor profile of olive oil (which is relatively pronounced compared to many other cooking oils) is a poor match for the types of dishes you'd normally be stir frying. | [
"Olive oil is produced by grinding olives and extracting the oil by mechanical or chemical means. Green olives usually produce more bitter oil, and overripe olives can produce oil that is rancid, so for good extra virgin olive oil care is taken to make sure the olives are perfectly ripened. The process is generally... |
why european civilizations were so much more advanced in terms of everything compared to african and native american civilizations. and so when white ppl came to america they basically just took over with guns. | _URL_1_
_URL_0_
_URL_5_
_URL_2_
_URL_3_
_URL_4_ | [
"Between 1878 and 1898, European states partitioned and conquered most of Africa. For 400 years, European nations had mainly limited their involvement to trading stations on the African coast. Few dared venture inland from the coast; those that did, like the Portuguese, often met defeats and had to retreat to the c... |
the united states is over $22 trillion in debt. what does that mean? | Not a whole lot, actually. Somewhere between 70-80% of that debt is held by American citizens in the form of bonds, including savings bonds. Bonds are heavily used as a stable investment to protect your money from inflation (the rates on the bonds basically keep up with the rate of inflation). And none of the debt is callable, which means that the individuals holding the debt cannot just order to be paid everything due in advance of the payment schedule.
In effect, as long as the GDP grows at about the rate of inflation, the amount of debt that the US has is stable. If inflation shoots up, or if GDP falls heavily, it can get a little bit tricky. But that's why we've got the Federal Reserve to look out for those things well in advance and take action to mitigate it before it becomes a problem. | [
"The total national debt of the United States in the United States was $18.527 trillion (106% of the GDP) in 2014. The United States has the largest external debt in the world and the 14th largest government debt as a % of GDP in the world.\n",
"The U.S. public debt was $909 billion in 1980, an amount equal to 33... |
what is the bubonic plague, and would it be as fatal today as it was in the middle ages? | Bubonic plague is a specific kind of disease caused by the bacteria Yersinia pestis. (Pneumonic and septicemic plague are the other kinds, less famous because they didn't destroy Europe.) Yersinia lives in fleas, which live on rodents. As a result, plague was able to spread very quickly in a time when sailors could bring rats across the Mediterranean, and when huge numbers of people lived in crowded, filthy cities where parasites were a normal part of life.
Is it as deadly now? No. Antibiotics have made plague dramatically more survivable, while hygiene in the developed world means you're highly unlikely to get fleas. In fact, when plague was found in squirrels near Los Angeles, the only response was to close a few campgrounds. There are many fine things to worry about, but the Black Death isn't one of them. | [
"The reference above to bubonic plague seems improbable. Typhoid is far more likely; it was both endemic and epidemic at the period, killing Prince Albert in 1861, but bubonic plague had a heyday from 1348 to about 1700. Cholera is just possible; there were outbreaks in 1832 in Liverpool and reputedly as late as 18... |
[Medicine] Improper alcohol detoxification can kill a person. How then can people rehabilitate alcoholics? | have them (the addict) continue to consume alcohol as needed to avoid serious withdrawal symptoms.
However, the amount consumed per day is decreased continually over a span of several days, so that their dependance on ethanol is gradually reduced to zero. | [
"Alcohol detoxification is a process by which a heavy drinker's system is brought back to normal after being habituated to having alcohol in the body continuously for an extended period of substance abuse. Serious alcohol addiction results in a downregulation of GABA neurotransmitter receptors. Precipitous withdraw... |
What is a plausible scientific explanation for "glory clouds" in church services? | That's dust. Definitely dust, you can tell by the straight line it makes coming from the light. | [
"The Morning Glory cloud is a rare meteorological phenomenon consisting of a low-level atmospheric solitary wave and associated cloud, occasionally observed in different locations around the world. The wave often occurs as an amplitude-ordered series of waves forming bands of roll clouds.\n",
"A glory is an optic... |
how do cough suppressants, decongestants and expectorants work together to help with a cold? | None of the above help colds. They help the symptoms of a cold. Decongestants, fine. Cough suppressants and expectorants seem illogical if mixed but separately they might help the symptoms.
Many of this type of symptomatic "cure" has ingredients that defy strict logic. Despite this, people buy them. | [
"When laryngospasm is coincident with a cold or flu, it may be helpful for some sufferers to take acid reflux medication to limit the irritants in the area. If a cough is present, then treat a wet cough; but limit coughing whenever possible, as it is only likely to trigger a spasm. Drink water or tea to keep the ar... |
What causes the varied distribution of resources across the Earth? | It's not a random process. Certain minerals only form under a set of very precise geological conditions. Much like how you need just the right ingredients to make a cake, you need just the right conditions to produce certain types of rock. These conditions include depth below the surface, temperature, pressure, local rock composition, hydrothermal activity, volcanic-tectonic activity. If you happen to get all these factors just right, then a body of ore will form. An understanding of what conditions produce what types of ore is useful to geologists who predict the locations in which to search for ore. | [
"Resource distribution refers to the distribution of resources, including land, water, minerals, fuel and wealth in general among corresponding geographic entities (states, countries, etc.).Resource distribution refers to the geographic occurrence or spatial arrangement of resources on earth. In other words, where ... |
How did Italian-Americans react to the extremely racist Allied anti Axis propaganda films? | Can we broaden this to include Asian Americans? | [
"From the onset of the war, and particularly following Pearl Harbor many viewed Italian Americans with suspicion. Groups such as The Los Angeles Council of California Women's Clubs petitioned General DeWitt to place all enemy aliens in concentration camps immediately, and the Young Democratic Club of Los Angeles we... |
The ratio of the distance between a planet and its star vs the ratio of the distance between an electron and its nucleus, are the two ratios similar? | Compared to the radius of the sun, the Earth is 215 times farther away.
Compared to the radius of a proton, the average position of the ground state hydrogen electron is 62,350 times farther away.
Now, there are other planets and stars and other elements, but that gives you a rough picture. | [
"In practice, this ratio is almost always extremely small. For example, the Schwarzschild radius \"r\" of the Earth is roughly 9 mm ( inch); at the surface of the Earth, the corrections to Newtonian gravity are only one part in a billion. The Schwarzschild radius of the Sun is much larger, roughly 2953 meters, but ... |
Considering all dogs have 38 chromosomes, can a very small dog mate with(in some manner) and give birth to a very large dog's pups? | A family member of mine breeds dogs so I've seen newborn puppies firsthand. There were two simultaneous litters of puppies; one from a toy poodle, and one litter from a standard poodle. What was amazing is that these newborns were practically the same size, just the toy poodle had considerably less (2) than the standard who delivered 13. Humans have been able to alter the appearance and behavior of dogs but we have not so much affected their reproduction.
Thus, the small dog will deliver puppies of the "standard puppy size" which is about 3-4 inches which will then grow into dogs much larger than the bitch.
Edit for clarity: We - > Humans | [
"All animals have a set of DNA coding for genes present on chromosomes. In humans, most mammals, and some other species, two of the chromosomes, called the X chromosome and Y chromosome, code for sex. In these species, one or more genes are present on their Y chromosome that determine maleness. In this process, an ... |
why are vishnu and his avatars blue? | Blue is considered a divine/pure colour.
I.e. connected to the sky / the sea | [
"BULLET::::- Blue in Hinduism: Many of the gods are depicted as having blue-coloured skin, particularly those associated with Vishnu, who is said to be the preserver of the world and thus intimately connected to water. Krishna and Ram, Vishnu's avatars, are usually blue. Shiva, the destroyer, is also depicted in li... |
How long can a plant survive in space? | Depends on the environment. Plants can grow in microgravity with an artificial atmosphere, but if you're just talking about throwing a naked plant into space, the extreme temperatures would start rupturing cells immediately (areas in the sun would be very hot, and areas in shade would be well below freezing). Between these two extreme temperatures and the very low pressure, which would also accelerate the rate at which volatiles boiled off, the plant would start to die as soon as it was exposed to this type of environment. How long is likely a function of the species and plant size. | [
"In 1982, the crew of the Soviet Salyut 7 space station grew some Arabidopsis, thus becoming the first plants to flower and produce seeds in space. They had a life span of 40 days. \"Arabidopsis thaliana\" seeds were taken to the Moon on the Chang'e 4 lander in 2019, as part of a student experiment. \n",
"The pla... |
Why were brass knuckles made of brass? | I can't speak to the historical aspect but from an industrial aspect brass is pretty inexpensive and is usually cast in a mold. Forged steel would be much more labor intensive. Cast iron would be subject to rusting. Brass is a good tradeoff of strength, cost, and corrosion resistance. | [
"Brass knuckles, also sometimes called knuckles, knucks, brass knucks, knucklebusters, knuckledusters, an English punch or a classic, are weapons used in hand-to-hand combat. Brass knuckles are pieces of metal shaped to fit around the knuckles. Despite their name, they are often made from other metals, plastics or ... |
why did ants ( and other insects maybe idk) get an exoskeleton rather than a normal skeleton? | Because a hard outer shell doubles as protection from predators, as well as anchor points for muscles.
Endoskeletons evolved to provide otherwise soft-bodied animals leverage to generate more power in their appendages without sacrificing as much flexibility as an exoskeleton. | [
"Like other insects, ants have an exoskeleton, an external covering that provides a protective casing around the body and a point of attachment for muscles, in contrast to the internal skeletons of humans and other vertebrates. Insects do not have lungs; oxygen and other gases, such as carbon dioxide, pass through ... |
do people who talk languages other than english think in those languages? | Do you think in English?
Seriously, when you think of a dog running across a field, do you imagine those words "a dog running across a field"? Or do you imagine an actual dog running across an actual field?
The only times that we actually think in words, is when we are thinking of a language. I could think "My name is Thomas" in those words, I could also think "Je m'appelle Thomas", or I could think in the abstract sense that Thomas and myself are one in the same.
It's similar to "how do deaf people think?" | [
"English is on the school program latest in 7th class, and it sounds somehow familiar so that everyone believes he knows English at once. Anyhow, most people can communicate a bit in English. It is being said: If you don't know how to speak English, just take a hot potato in your mouth and speak a funny Luxembourgi... |
How is corruption measured? | Transparency International publishes what they call a "Corruption Perception Index" made up from polls. They ask people how often in the past year (or whatever timeframe) they paid a bribe, and how much, and in what situation.
It is true that the data is not entirely reliable because of the very nature of the thing but they openly acknowledge this.
[From their Website:](_URL_0_)
> WHY IS THE CPI BASED ON PERCEPTIONS?
> Corruption generally comprises illegal activities, which are deliberately hidden and only come to light through scandals, investigations or prosecutions. There is no meaningful way to assess absolute levels of corruption in countries or territories on the basis of hard empirical data. Possible attempts to do so, such as by comparing bribes reported, the number of prosecutions brought or studying court cases directly linked to corruption, cannot be taken as definitive indicators of corruption levels. Instead, they show how effective prosecutors, the courts or the media are in investigating and exposing corruption. Capturing perceptions of corruption of those in a position to offer assessments of public sector corruption is the most reliable method of comparing relative corruption levels across countries. | [
"BULLET::::- Lack of measurement of corruption. For example, using regular surveys of households and businesses in order to quantify the degree of perception of corruption in different parts of a nation or in different government institutions may increase awareness of corruption and create pressure to combat it. Th... |
what happens to the food company when someone who is allergic to a secret ingredient consumes their food? will it be revealed? why has it not ever happened? | I think due to FDA regulations all ingredients must be listed, so the secrets are usually formulas and combinations. But the individual ingredients that people may be allergic to are listed. | [
"Allergic reactions are hyperactive responses of the immune system to generally innocuous substances, such as proteins in the foods we eat. Why some proteins trigger allergic reactions while others do is not entirely clear, although in part thought to be due to resistance to digestion. Because of this, intact or la... |
if it is illegal to melt down pennies, how is it legal to press them? | Are you talking about how it's legal for the US Mint to press them? Because they're authorized by law to do so.
If you're asking about those novelty machines that strech out a penny, it's because defacing the currency for non-fraudulent purposes isn't illegal. | [
"In anticipation of the business of melting down U.S. pennies and U.S. nickels for profit, the U.S. Mint, which is a part of the US Department of the Treasury, implemented new regulations on December 14, 2006, which criminalize the melting of pennies and nickels and place limits on export of the coins. Violators ca... |
why the american corn taste different from middle eastern corn or asian one? | They differ in species, soil composition, environment, exposure to the sun. These all could effect the taste. | [
"BULLET::::- Maize: Maize (\"Indian\" corn), is native to Mesoamerica and Peru, The varieties used in Europe and most of the world are from Central America. The corn grown in Peru is so sweet and unique in the world cause the characteristics it has and has very large grains and is not popular outside of Latin Ameri... |
what's the difference between tense, mood, and case? | Tense is the time of the action, past, future, happening right now. The tenses give a sense of when an action was completed, or if we expect the action to continue into the foreseeable future. It puts the verbs into a context of when.
Mood adds or removes a certain certainty or uncertainty or more commonly, obligation. We use modal verbs to add a stronger sense of obligation (must, have to) or soften a statement to suggestion (should). We don't really moods in English because we use these modal verbs, if you study Italian then you'll see mood a lot use with different verbs - "essere", to be, changes to "sia", for example, the actual verb "to be" changes the mood of the sentence, in English we add "should" and leave the next verb alone "he should leave".
Cases you'll see a lot in German, which is when the pronoun changes depending on who is doing what to whom. We have them in English too, but not to a greater degree as in German. For example, you don't say "I'll give the bucket to he", you say "I'll give the bucket to him". The possessive is "his bucket" - the cases that we have in English mean that you must change "he" to "him" and "he" to "his" depending on who is doing what to what/with what object. He is 'owning' his bucket".
This is my understanding of it, at least, having taught English for 10 years and studied Italian, German and French. | [
"The term \"tense\", then, particularly in less formal contexts, is sometimes used to denote any combination of tense proper, aspect, and mood. As regards English, there are many verb forms and constructions which combine time reference with continuous and/or perfect aspect, and with indicative, subjunctive or cond... |
if peanuts aren't actually nuts why do people with a nut allergy die from them? | Because peanut allergies are different from nut allergies. I'm allergic to peanuts but not nuts. | [
"Peanuts are legumes, not true nuts, but they share with true nuts the risk of causing allergic reactions, even in minute amounts. Pure peanut and nut-derived oils are not usually allergenic (as they do not typically contain the proteinaceous part of the plant), but avoiding them may be safer, as serious peanut and... |
why does my cat retain the ability to bound at 30 mph and jump vertically 5ft if he sleeps all day? | I assume your cat, like almost every cat, likes to jump up on things and tends to go bat-shit crazy in the middle of the night and run around like a maniac sometimes. This is its exercise.
Compare that to a reasonably fit human that works out regularly - not a gym nut or anything but just a guy who works out like twice a week to stay healthy and fit. He'll probably work out for what, a couple of hours? And that won't be nonstop, it'll be in sets with frequent breaks. So in reality he spends less than 30 minutes actually exercising, and he does that twice a week. So less than an hour per week exercising and he's perfectly fine.
TL:DR You only need to exercise a little to maintain your muscles. | [
"During a fall from a high place, a cat can reflexively twist its body and right itself using its acute sense of balance and its flexibility. This is known as the cat's \"righting reflex\". The minimum height required for this to occur in most cats (safely) would be around .\n",
"In addition to the righting refle... |
why don't we just use two or more different antibiotics, with different ingredients to kill off 100% of bacteria | We do. Antibiotic cocktails are quite common when resistance is suspected. But as /u/sablemint notes, any survivors - and there are likely to be some - then develop resistance more quickly. | [
"Antibiotics such as tetracyclines, rifampin, and the aminoglycosides streptomycin and gentamicin are effective against \"Brucella\" bacteria. However, the use of more than one antibiotic is needed for several weeks, because the bacteria incubate within cells.\n",
"Bacterial infections may be treated with antibio... |
how do different sound waves of the same wavelengths carry a different timbre? | There is a big difference between 'wavelength' and 'pitch'.
All sounds are made up of many pure sine waves overlaped on top of eachother. A pure sine wave is what you here when you strike a tuning fork.
Pitch means a note, like C# or D. Each note corresponds to a specific wavelength. But again, the sounds you hear in every day life are made of many of these wavelengths mixed together.
Something you perceive as a note with a specific pitch is a mixture dominated by a specific wavelength. But, there is still a whole mix of other wavelengths on top of that. That extra mixture is what makes a C# on a piano sound different than the same C# on a flute.
A sound without a specific pitch, like a crashing wave, has a pretty much even mixture of all wavelengths. This is also know as 'white noise' as analogous to white light.
To carry the analogy further, light you see is a mixture of wavelengths of color. All images are a mixture of wavelengths in different positions just like all sounds are mixtures of wavelengths at different times. This is why a red truck looks different than a red apple; even though they have the same dominate 'tone'.
If you are interested in explinations which are math intensive and outside the scope of eli5, check out [Fourier Transforms](_URL_0_)
tl;dr "two sound waves of the same length" cant carry different sounds, you need a mixture of many different wavelengths. | [
"Aside from pitch and loudness, another quality that distinguishes sound stimuli is timbre. Timbre allows us to hear the difference between two instruments that are playing at the same frequency and loudness, for example. When two simple tones are put together they create a complex tone. The simple tones of an inst... |
Were torches used in medieval times as much as movies make us believe and what were they made out off? | Were torches used as often as we see in movies?
No. Movies generally seem to show torches as the most common light source for medieval people, when in fact rushlights (reeds soaked in animal fat), tallow candles and simple oil lamps seem to have been much more common.
What were torches made of?
Usually a wooden handle (possibly with some metal fittings), some kind of fibre to act as a wick and oil or fat to serve as fuel (apparently some of them used other forms of fuel, like sulphur and pitch, which seems even less practical). The fibre is soaked in the fuel and either wrapped around the handle or stuffed inside, depending on the design.
How functional were they?
Based on modern reconstructions, not very. They are heavier and more difficult to carry than other forms of lighting, they can't be conveniently put down on a flat surface as most alternatives can and the light they produce is very flickery and difficult to see by. The only benefit seems to be that they are fairly easy to make and less prone to being blown out than a rushlight, which is the other simple-to-manufacture medieval light source. | [
"Lit torches (burning sticks) were likely the earliest form of incendiary device. They were followed by incendiary arrows, which were used throughout the ancient and medieval periods. The simplest flaming arrows had oil- or resin-soaked tows tied just below the arrowhead and were effective against wooden structures... |
why do monotonous noises (like the sound of an alarm clock) begin to sound like it has two different pitches after hearing it for a while? | i think that it may be because of our natural tendency to turn repetitive sounds into melodies. So a repetitive sound gets given different pitches by our brains. Its called the speech to song illusion. | [
"In electronic devices, it shows up as a low-frequency phenomenon, as the higher frequencies are overshadowed by white noise from other sources. In oscillators, however, the low-frequency noise can be mixed up to frequencies close to the carrier, which results in oscillator phase noise.\n",
"Many types of noise e... |
how come many fish were able to survive the great k–pg extinction, but pretty much no sea reptiles (mosasaurs, plesiosaurs, etc) were able to? | It takes a LOT of food and a very balanced ecosystem to keep a giant alpha predator alive. If the food diminishes or the ecosystem shifts, alpha predators die out pretty easily. | [
"A wide range of species perished in the K–Pg extinction, the best-known being the non-avian dinosaurs. It also destroyed a plethora of other terrestrial organisms, including some mammals, pterosaurs, birds, lizards, insects, and plants. In the oceans, the K–Pg extinction killed off plesiosaurs and the giant marine... |
how do bank errors leaving customers with extra money happen? | I have this saying: "As long as humans are involved, there will be human error."
Simple as that - someone at the bank done goofed. You are right - banks *do* have incredibly strict controls to prevent errors, but as long as human beings are punching keys and inputting information, there's going to be human error on occasion.
I remember one time a customer called in to say that he noticed he had an extra $50,000 in his account, wondered where it came from. Did some digging around through our systems, and figured it out. A third party had walked into a branch to make a deposit into his friend's account, didn't have the account number handy so the teller looked it up by the account holder's name. Even though it was a fairly uncommon name, our bank had *two* customers with the same name. Guess where the money went?
It was an easy enough fix, and it did not cause any problems with the other customer, but it is still clearly a bank error. Very, very rare (I've seen it maybe twice), but it does happen.
Another more common error I see is "check encoding errors", where someone is manually typing in the information from the checks and types in some digits wrong - such as transposing two numbers, and the money ends up in the wrong account. I see that a few times a year.
Basically, as long as human beings are part of the process of handling the transactions, there will be errors. The error rate is extremely low, but our bank processes several billion individual transactions each day, so a few creep into the system here and there.
> Also- if you did withdraw and use the money completely, how is this against the law?
Well, no, you can't keep it. In the terms and account agreements that you agree to when you open your account, there are disclaimers about bank errors. Pretty much every bank, credit union or financial institution will have a disclaimer about the bank's ability to make corrections, and that you would be responsible for returning any misapplied funds. | [
"However, the problem is exacerbated by some of the banks themselves for failing to implement any controls which prevent companies or fraudsters taking monies from business and consumer accounts. The problem of cancelled and obsolete direct debits being wrongfully revived or re-implemented is estimated to cost UK c... |
Did European explorers/settlers encounter any Native American urban centers in the in modern-day USA and Canada? | > the Pueblo Indians had urban centers, but I'm not sure what happened to them
Many are alive and well. Consider Acoma Pueblo and Taos Pueblo, both of which were founded around 1000 years ago and both currently home to between 4500 and 5000 people. Others didn't survive, such as Hawikuh - an old Zuni pueblo that was the first to encounter Coronado's *entrada*. It was one of the legendary Seven Cities of Cibola, which the Spanish believed to have reserves of gold to rival the Aztecs and the Inca (but were sorely disappointed when they actually arrived). The Spanish held it for a time, but eventually abandoned and has now become a ruin. Even at its peak, however, its population estimates are considerably lower that modern Acoma and Taos. But the Southwest isn't my area of expertise so I'll leave a more detailed discussion of that area to others.
Instead, let's turn our attention east.
While Coronado was marching through the Southwest, de Soto was [snaking his way through the Southeast](_URL_1_). Along the way, he encountered several prominent Mississippian polities. Among them were the Apalachee, which I'll get to in a moment, and Coosa.
##**COOSA**
To discuss Coosa, I'm going to introduce you to two Muscogee terms (anglicized a bit for ease of reading): italwa (*etvlwv*) and talofa (*tvlofv*). An italwa is major political center and all its subsidiary elements (by extension, it also refers to a nation and its people). A talofa is town or city in the physical sense - its buildings and its boundaries. Coosa was both.
As an italwa, it was perhaps the most extensive in what's now the US at the time of European contact. It stretched some 400 miles long. If you refer back to the map, it bordered the Chiscas to the northeast, and its southwestern limit was Talisi (which the neighboring Atahachi italwa was trying to bring into its own sphere of influence as de Soto came through). It was a large and populous nation, with many large towns surrounded by extensive fields of maize and beans, stream-side vineyards, and plum orchards. It was the heir, and probably a direct continuation of, the older Etowah italwa (which is rather redundant actually, since the name "Etowah" is derived from *etvlwv* as well), which had been based nearby. I marked their locations on [GoogleMaps](_URL_2_) for you. The location of the Etowah talofa is clearly labeled, with the Coosa talofa is now submerged by a reservoir.
Since I haven't been able to find a decent reconstruction of Coosa, I thought I'd show [this reconstruction](_URL_0_) of its predecessor. The reconstruction of the Etowah talofa gives you an idea, in general, of what Coosa talofa would have looked like when de Soto arrived, but the specifics would have been different of course. In particular, the Etowah reconstruction is much more sparsely populated than Coosa was (and likely more sparsely populated than Etowah actually was too). The population estimates for the Coosa talofa at the time of de Soto range from 2500 to 5000, with the population for the whole italwa at 50,000+. Like Etowah, Coosa had a plaza surrounded by three igan halwa (*ekunhvlwv*), or "mounds" if you want the more familiar term. It had at least two distinct districts. One for the common people, and another for the elites. The elite district was built later, at the same time the Etowah talofa was abandoned, which is why it appears that Coosa is the direct continuation of the Etowah italwa - it just moved its capital. Unlike Etowah, Coosa did not have elaborate defensive structures like the palisade walls or moat. When the italwa's capital moved, its leadership must have felt secure in their hegemony over the region and deemed such defenses unnecessary (this was not true for the up-and-coming Atahachi italwa to the southeast, where most of the talofa had defensive fortifications).
The micco (*mekko*, or "chief") of Coosa when de Soto arrived was described as an erudite and cultured man in his mid-20s. He had an air of sophistication about him that reminded the Spanish of the nobility of Europe. Despite his cooperation with the Spanish, he and many of the other high-ranking members of Coosa society were taken captive. This caused a panic in the talofa, as well as the neighboring talofa. The people fled, but the Spanish pursued and captured many of them. The micco negotiated the release of most of his people, but he, his sister, and a few of the prominent members of Coosa society remained captives and were forced to escort de Soto and his men through the remainder of the Coosa italwa. Once they reached Talisi, the micco and most of the other nobles were freed, but de Soto kept the micco's sister. Her fate is unknown, though she either escaped or, more likely, died at the Battle of Mabila that happened shortly thereafter.
After de Soto, about a century goes by before there's additional European contact with Coosa. By this time, its power had waned considerably. It was no longer a great italwa stretching along the southern Appalachians. Instead, it had allied three other italwas in the area to form the Mother Towns of the Creek Confederacy. | [
"This district, a nationally significant distinction, provides material evidence of one of the earliest instances of interaction between native people and European explorers on the west coast of what is now the United States of America. This distinction is based on the two historical encounters, Sir Francis Drake's... |
why does light/sound propogate as a wave? why not a straight line? | They both do propagate in a straight line just as a wave in the water does. A sound wave or water wave is a varying pressure, not space. And luckily google gave me the answer [from Reddit](_URL_0_) on what varies in a photon:
> The wave is not the path that the photon takes. The wave is a representation of the electromagnetic field associated with that photon. | [
"This two-dimensionality, compared with the apparent four-dimensionality of light, is because light travels in rays (0D at a point in time, 1D over time), while by Huygens–Fresnel principle, a sound wave front can be modeled as spherical waves (2D at a point in time, 3D over time): light moves in a single direction... |
are there gradual forms of depression or is it purely binary? | As someone who is very depressed, it's gradual. Never binary. You have good days, you have bad days. | [
"A half century ago, diagnosed depression was either endogenous (melancholic), considered a biological condition, or reactive (neurotic), a reaction to stressful events. Debate has persisted for most of the 20th century over whether a unitary or binary model of depression is a truer reflection of the syndrome; in t... |
why is it that it's possible to shake a cup with a bunch of dice in it to the point that they can all stack on top of each other? | It's not just being shaken randomly. If you'll note, the predominant motion is a circular swinging. What they're doing is forcing the dice to the edge of the cup and getting them to swirl around. If done right, that forces the dice to assume a vertical stack inside the cup. It takes practice of course, but it's no more magic than any physical trick like that. | [
"Each round, each player rolls a \"hand\" of dice under their cup and looks at their hand while keeping it concealed from the other players. The first player begins bidding, announcing any face value and the minimum number of dice that the player believes are showing that value, under all of the cups in the game. O... |
how come putin has the same power in russia now as a prime minister as he had as a president? | Vladimir Putin *is* the President of Russia. Has been since 2012. Before that he was Prime Minister. Before *that*, he was President.
It is fairly accepted that he was still running things when he was Prime Minister, though and that the president at the time (Dmitry Medvedev) was merely his puppet. | [
"In his first speech after being endorsed, Medvedev announced that, as president, he would appoint Vladimir Putin to the post of prime minister to head the Russian government. Although constitutionally barred from a third consecutive presidential term, such a role would allow Putin to continue as an influential fig... |
What was the military organization, equipment, and tactics of Carthage like during the Punic Wars? | In large part, the Carthaginian armies during the first Punic War were largely composed of mercenary troops from a variety of different areas under the control of Carthage (think North Africa, Spain and southern Gaul).
During this period, the command was generally along the lines of the Romans - upper class members who could afford the armour and weapons with ~~the King~~ senior general (Roman = consul) in overall command. ~~This changed in the 2nd and subsequent wars when a more professional command structure was instituted (ala Hannibal)~~
In the 2nd Punic War, the makeup of the forces lent more heavily on a formal African contingent made up primarily of heavy infantry spearman - think Greek Phalanx based and you won't be too far off the mark - with Phoenician/Spanish swordsman and then irregulars based around Gaulish troops.
Cavalry were where the Carthaginians had it over the Romans as their javelin equipped Nubians were considered the best in the world at the time.
The general tactics were for the Numidians to ride up to the Roman lines and conduct fast skirmishes to break up the Roman ranks. These were then followed up by the heavy cavalry (mainly Libyan/Phoenician) who drove into the Roman infantry. Into this hole was then marched the heavy spear equipped infantry supported by sword wielding heavy infantry and the lesser equipped lighter Gaulish irregulars.
Elephants also formed a basis for "shock troops" and would generally be used on the flanks and/or on the front with infantry in support.
There is a good book on Scribd that goes into much more detail on the make up of forces during the Punic Wars. You can find it [here](_URL_0_). | [
"Carthage's military battled the Greeks over control of the island of Sicily. These encounters influenced the development of the Carthaginians' weapons and tactics, causing Carthage to adopt the Greek-style hoplite soldier fighting in the phalanx formation. However, the Carthaginian war machine faced its biggest ch... |
what are you supposed to do when an emergency vehicle passes you on the opposite side of the road? | If there is a physical obstruction in the median (for example trees, bushes, dirt etc.) then you do not need to do anything but if it is just yellow lines or there is a big enough opening for them to cross onto your side of the road then you should pull over until they pass.
This is so that if for example traffic is heavy on the other side of the road they can cross over to your side or if the street entrance they have to go into would normally be blocked on their side of the road to get where they need to go. | [
"Depending on local laws, vehicles on the road may be required to yield the right of way to emergency responders who are using their warning devices. For example, in Utah, when an emergency vehicle is on the road while using its warning devices, all cars are required to pull over to the side of the road, stop, and ... |
what is a generator in electricity? | It's like an *electron pump* that pushes electrons away from one end and toward the other end. This creates a *voltage* (electric pressure) which is then used to power the flow of electricity through wires and other things. | [
"In electricity generation, a generator is a device that converts motive power (mechanical energy) into electrical power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. The first elect... |
why are media companies so obsessive about pirating movies or music online, when just a few years ago people would record movies off of tv or music from the radio and it wasn't a big deal? | They were making a big deal about it then, that's why they would put in warnings and videos about piracy, but they had to crackdown harder on internet privacy because the ease of it caused piracy numbers to skyrocket creating a bigger problem | [
"Rather than destroying film studios, videotape sales became increasingly important to their revenue. The press discussed the VCR \"and the viewing habits it has engendered — the Saturday night trip down to the tape rental store to pick out for a couple of bucks the movie you want to see when you want to see it\". ... |
Were there any devout Christians among the Nazis who participated in the Holocaust? How did they come to terms with the things they had done? How did they justify their actions in front of the altar of God? | Not sure if this would be considered devout. Josef Tizo was a Catholic priest and also one of the leaders of the Slovaks Peoples Party a Clerical-Fascist party that was installed in power during WW2. It was also founded by another Catholic priest Andrej Hlinka, for which their paramilitary, the Hlinka Guard was named.
The party ruled from 1939-1945, pretty much the duration of the war. And its record is not pretty. The party not only acquiesced to every single Nazi request, but participated enthusiastically. This included the "Final Solution", the party actively used the state to find and deport Slovakia's Jews to the Polish death and concentration camps in 1942. This was on top of variations of the Nuremburg Laws (The Jewish Code as known locally) that had been enacted in 1941.
The leadership of the Catholic church was supportive initially, an apostolic blessing from Pope Pius XII was given to President Tiso after his ascension. They were not so pleased as the antisemitic nature of the clerical-fascist regime took hold. In general, Tiso was supported by large numbers of ordinary Catholic priests and deplored by the bishops and the Vatican itself. Though there are lots of exceptions, such as Bishop Jan Vojtaššák, who thoroughly supported Tiso and the persecution of the Jews.
While opposed by the Church, the Vatican made no effort to excommunicate or restrict Tiso (or his prime minister, also a Catholic priest).
After the war, Tiso would be tracked down and arrested by the American occupying forces and handed over to a judicial tribunal in Czechoslovakia the Americans had organized. This was prior to the takeover by the Communists. Tiso was condemned to death and executed in 1947 for his crimes against Slovakia's citizens, including Jews.
In 1995, the Catholic Church did a good job of offending Jews when Pope John Paul II proposed beautifying previously mentioned Tiso supporter Bishop Jan Vojtaššák for his opposition to the Communist state. Despite that Jan Vojtaššák had not found a persecution of Jews he could not support.
Some Sources:
Dr. Pavol Mest’an, Slovak historian, director of Museum of Jewish Culture of Bratislava
The Vatican, the Catholic Church, the Catholics and the Persecution of the Jews during World War II: The Case of Slovakia in Jews and non-Jews in Eastern Europe by Yeshajahu Jelinek, University of Minnesota, 1974 (at the time, he jumped back to Israel's Hebrew University after his stint in Minnesota)
There is another book specifically on Slovakian Jews was contributed to by Yeshajahu Jelinek, The Tragedy of the Jews of Slovakia: 1938-1945 Slovakia and the Final Solution of the Jewish Question, published in 2002 I have yet to read. | [
"During the Holocaust, the Roman Catholic Church played a role in the rescue of hundreds of thousands of Jews from being murdered by the Nazis. Members of the Church, through lobbying of Axis officials, provision of false documents, and the hiding of people in monasteries, convents, schools, among families and the ... |
many american football players have brain diseases in their old age because they have so many concussions during their career. why don't rugby players, who don't wear helmets, have this problem? | Because American Football players wear helmets and protective armor, they regularly crash into each other way more violently than rugby players would, leading to the apparently paradoxical effect that football players' "protection" actually make the sport more dangerous.
In a similar case, the introduction of soft, cushy gloves in boxing has lead to significantly more deaths in boxing matches, since boxers were now able to hit their opponent's head with great force without breaking their own hands. | [
"Other organizations continued to publish study results that linked repeated concussions and long-term health problems contrary to reports by the MTBI Committee. A 2003 report by the Center for the Study of Retired Athletes at the University of North Carolina, for example, found a connection between numerous concus... |
When history says "Alexander founded a new city," what is being described here? | Hi, not discouraging responses here, but fyi there was a fairly lengthy thread on this topic last week that would be worth catching up on - see here
* [In ancient times I've heard that historical figures "built cities" like Alexander did at Bucephala in honor of his horse. How did a ruler in Greco times go about establishing a city? What did that at a minimum constitute?](_URL_3_) featuring /u/ikahjalmr
Also
* [Who populated the cities founded by Alexander the Great?](_URL_1_) featuring /u/Daeres
* [How did Alexander the great build alexandria?](_URL_0_) featuring /u/Docimus
Of possible tangential interest
* [How were cities founded by traveling armies in antiquity?](_URL_2_)
* [There's a legend that Hercules himself founded my city (Cádiz, Spain) 3000 years ago. Can anyone direct me to that legend or tell me something about it?](_URL_4_) | [
"The exact quote found in \"Guardians of the Lost Library\", \"The city was founded by Alexander the Great in the fourth century B. C. to be the capital of his empire!\" is a bit ambiguous, meaning either that it was Alexander's direct personal intention or that it was about to happen independently of whatever Alex... |
Do we have any idea what the relationship between Sumer/Mesopotamia and Egypt was? | According to [this website](_URL_0_) "There is no mention of the Egyptians in the Sumerian archives, or vice-versa, and there is no direct evidence that they had a noticeable influence on one another, except for their propensity to build giant pyramids and ziggurats. Although on a modern map they appear to be quite close, they seemed to have been completely unaware of each other’s existence. Back then, the world was a much larger place." | [
"The majority of Sumerian deities belonged to a classification called the \"Anunna\" (“[offspring] of An”), whereas seven deities, including Enlil and Inanna, belonged to a group of “underworld judges\" known as the \"Anunnaki\" (“[offspring] of An” + Ki). During the Third Dynasty of Ur, the Sumerian pantheon was s... |
if i have an electrical circuit, run a current through it, and then suddenly interrupt the circuit, what happens to the electricity still within the circuit? | Imagine a channel of water. On one end you pump in water, on the other end you suck water away. Imagine that you suddenly stop doing both. The water briefly builds up due to leftover inertia and then it stops moving.
Same thing in a circuit. The electrons are slowly moving through your circuit. If you interrupt it the electrons stop moving. Electricity is the movement of the electrons in one direction, not the electrons themselves.
The brief buildup also has an equivalent in electricity, inductance in electrical circuits is equivalent to inertia in water flows. So if you take a big coil (lots of inductance) and you suddenly interrupt a current flowing through it you get a pretty damn big spark. That's how spark plugs in your car work. | [
"All lines and all electrical equipment must be protected against prolonged overcurrent. If the cause of the overcurrent is nearby then automatically that current is interrupted immediately. But if the cause of the overcurrent is outside the local area then a backup provision automatically disconnects all affected ... |
When did nations begin to regularly levy taxes? | Can you winnow this question down more, whether geographically, temporally or both? It's quite broad, considering that taxation was introduced, disappeared, and reintroduced at varying times as well as varying regions throughout history.
Are you talking about taxation in antiquity? Late medieval European feudal taxation? Or specifically state taxation of the early modern period? Taxation in coin, or taxation in kind?
Please be more specific.
| [
"The history of taxation in the United States begins with the colonial protest against British taxation policy in the 1760s, leading to the American Revolution. The independent nation collected taxes on imports (\"tariffs\"), whiskey, and (for a while) on glass windows. States and localities collected poll taxes on... |
What are those curvy distortions in the air above a hot stove? | The index of refraction (how much the speed of light changes through a medium) of a gas depends on its temperature. What you are seeing is light going through regions whose temperature is changing (and possibly also a changing composition, e.g. leaky propane above a bbq). You can see it more clearly with [Schlieren imaging](_URL_0_). | [
"BULLET::::- Forced air stoves have a fan powered either by a battery, an external source of electricity, or a thermoelectric generator. This fan blows high velocity, low volume jets of air into the combustion chamber, which when optimized results in more complete combustion of the fuel.\n",
"Certain stove design... |
what happens during an internet outage? | There can be a million reasons ... The chain from you to the data center is: PC -- > LAN -- > Router/Modem -- > Landline/cable/fibre to some more central place (plus converters) -- > Another Router/Modem -- > fatter line to data center -- > [more hardware] -- > interconnection with other ISPs -- > repeat until you reach your destination page.
literally anything in that chain can break or in the case of routers be misconfigured. | [
"BULLET::::- On October 22, 2012, a major outage occurred, affecting many sites such as Reddit, Foursquare, Pinterest, and others. The cause was a memory leak bug in an operational data collection agent.\n",
"One way natural disasters impact internet connection is by damaging end sub-networks (subnets), making th... |
Why do scientists currently refer to Dark Matter as matter? Isn't it possible that the evidence for Dark Matter may actually be an incomplete understanding of gravity or other forces? | > Isn't it possible that the evidence for Dark Matter may actually be an incomplete understanding of gravity or other forces?
Yes, it's possible. Actually several scientists have thought of this and proposed alternate theories aimed to refine gravitation. They are [MOND](_URL_0_) and it's relativistic version, [TeVeS](_URL_2_).
They are good at explaining the galaxy rotation problem. However, MOND cannot explain [gravitational lensing](_URL_1_). TeVes can, but it's not completely consistent with the observations. Particularly, the behavior of the Bullet Cluster pointed out by thiosk is *not compatible with any current modified gravity theories* - quoted from [TeVeS](_URL_2_).
So far Dark Matter is the theory that best explains the observations.
ninja edit: accuracy | [
"Although the existence of dark matter is generally accepted by the scientific community, some astrophysicists, intrigued by certain observations which do not fit the dark matter theory, argue for various modifications of the standard laws of general relativity, such as modified Newtonian dynamics, tensor–vector–sc... |
What is an inertial frame of reference? | It's a reference frame that's not accelerating. If you're just floating in space, you're in an inertial frame of reference. If you're on an accelerating spaceship, you're not, so you feel like there's something pulling you towards the engines when it's really just the engines accelerating towards you. | [
"An inertial reference frame (or inertial frame in short) is a frame in which all the physical laws hold. For instance, in a rotating reference frame, Newton's laws have to be modified because there is an extra Coriolis force (such frame is an example of non-inertial frame). Here, \"rotating\" means \"rotating with... |
Looking at maps of Yugoslavia, its clear that large parts of Serbia, Croatia and Bosnia had ethnic majorities from one of the other nations. Did this cause problems before the 90's? Were there any attempts to change the internal borders? | The only real evidence I can find of any internal attempts to change borders prior to the late 80s/ early 90s was the Nazi and Fascist Italy attempting to "persuade" Croatia to become independent, to push for more autonomy so to speak.
When Yugoslavia as a whole was invaded by Axis powers in 1941, Croatia was given independence from Yugoslavia by the Nazis, who then encouraged the Croatians to participate in the killing of Serbs within its borders (these killings seem to be more motivated by religious rivalries as opposed to nationalist or ethnic motives).
It was throughout this war that the Chetniks (Royalists determined to see the re-establishment of a monarchy) and the Partisans (communists) fought for control of Yugoslavia from the Axis powers (led by Nazi Germany). During this war, Josip Broz Tito distinguished himself when he led the Partisans to victory over both the Axis powers and the Chetniks. He had a dedicated following, dedicated enough that when the war came to an end, it was decided that the exiled monarch (King Peter II, the last King of Yugoslavia) would stay in exile.
Tito also received aid from the Soviets during this war, and the Soviets also helped him set up the Socialist Federal Republic of Yugoslavia in 1945. I'm harping on about Tito here because of the defining role he played in keeping Yugoslavia together during his reign as President.
Tito modeled his secret police on the Soviet KGB, they acted in a manner similar to the KGB, often extrajudicially and almost always omnipresent. Tito used his secret police to crack down on any feelings of nationalism, purging any and all growth of nationalism. The suppression of nationalistic feelings and an odd mix of deference and repression is what held Yugoslavia together during Tito's reign.
Tito allowed all ethnic groups to speak their own language. Eg; Croatians could speak Croatian and Serbians could speak Serbian and so on. However, in relation to Albanians, Tito took an incredibly harsh stance, arresting and imprisoning many Albanians for expressing their ethnic identity. According to Matas, almost half of the political prisoners in Yugoslavia were Albanians. This is significant because Matas also asserts that Yugoslavia had more political prisoners outside the USSR than the rest of Europe combined.
I may have gone on a bit long about the role of Tito but that's because he was instrumental in keeping Yugoslavia together. When he died in 1980, the Presidency became decentralised and the country was held together by the ideological force of Communism. It was when communism collapsed in 1989 (with the Fall of the Berlin Wall etc.) that Yugoslavia lost its unifying factor and ethnic tensions began to rise.
Edit: In my studies on this, I haven't found any evidence of attempts to change internal borders during Tito's rule
Resources:
Matas, David (1994). No More: The Battle Against Human Rights Violations. ISBN 1-55002-221-0.
Finlan, Alastair (2004). The Collapse of Yugoslavia 1991–1999. New York, USA: Osprey Publishing. ISBN 978-1-4728-1027-4.
Corbel, Josef (1951). Tito's Communism. Denver, Colorado: The University of Denver Press. | [
"Within Yugoslavia, separating Croatia and Slovenia from the rest of Yugoslavia is an invisible line of previous conquests of the region. Croatia and Slovenia to the northwest were conquered by Catholics or Protestants, and benefited from European history; the Renaissance, French Revolution, Industrial Revolution a... |
Tesseract 4th dimension | The square doesn't have to be within the other cube. When you see a tesseract drawn... What you're looking at is a 2 dimensional representation of a 3 dimensional representation of a 4 dimensional shape. If you were to build one out of matchsticks and view it front on at the correct angle, you'd start to get the illusion of two cubes occupying the same space (that's the reason for one cube being smaller for fake perspective).
But as I said it doesn't have to be inside. If you draw a square, and draw a smaller square within it, then connect the corners... You end up with a 2d representation of a cube. At the same time... The second smaller square does not have to be within the bounds of the first square... It can be offset for a different perspective. | [
"A tesseract is an example of a four-dimensional object. Whereas outside mathematics the use of the term \"dimension\" is as in: \"A tesseract \"has four dimensions\"\", mathematicians usually express this as: \"The tesseract \"has dimension 4\"\", or: \"The dimension of the tesseract \"is\" 4\".\n",
"The term 't... |
why do instruments sound different if sound is just vibrating air? | It all has to do with what they call timbre.
Different instruments may be capable of playing the same note or pitch, but they all do it differently. Not only is the pitch (or frequency of the note) being sounded, but also other frequencies get sounded, too. These might be overtones, or multiples of the intended frequency, or other non-multiple frequencies. Which additional frequencies are sounded, and their relative strengths compared to the pitch frequency, color the overall sound. That is the instrument’s timbre.
The timbre is a function of many properties of the instrument. An instrument that creates sound through cavity resonance, like a clarinet, will excite different frequencies than an instrument that creates sound through vibrating a string, like an electric guitar. And then different models of the same instrument can excite different frequencies through the use of different materials, or different playing skills, or slight changes in design, etc.
Hope this helps! | [
"Pitched musical instruments are often based on an acoustic resonator such as a string or a column of air, which oscillates at numerous modes simultaneously. At the frequencies of each vibrating mode, waves travel in both directions along the string or air column, reinforcing and canceling each other to form standi... |
there are people who claim that drinking beer gives them a "happy-go-lucky" drunk, but drinking whiskey or liquor makes them a "mean" drunk. what could cause this? | It's mostly due to accelerated drunkenness. 1 shot of 80 proof liquor is roughly equivalent to 1 beer. So taking a shot is like drinking a whole beer in a matter of seconds. Even if you sip liquor, most people will end up drinking it faster if you are out with the boyz. So people that claim that a certain liquor makes them act a certain way probably just got drunk faster than they expected. | [
"There is a lack of medical consensus about whether moderate consumption of beer, wine, or distilled spirits has a stronger association with heart disease. Studies suggest that each is effective, with none having a clear advantage. Most researchers now believe that the most important ingredient is the alcohol itsel... |
If the population of rome was so large in its early history, why is there so little written down? | Why are you equating size of settlement with presence of surviving written literature? The two are in no way correlated. We have a plethora of sources from democratic Athens, including tragedy, comedy, history, and philosophy, and that city was absolutely tiny compared to Rome as far as population. We have only scraps from her contemporary equals in population--Corinth, Miletus, Syracuse, for instance.
Meanwhile, Carthage was one of the biggest cities in the Mediterranean in the Hellenistic period and barely a word of written literature survives from there. Throw in Gadir (Cadiz) as well. Or Tyre, or Sidon. The list of what survives today has more to do with subject matter, tastes, and the accident of preservation.
There were plenty of texts being written in the early Roman period. Livy drew upon the now-lost works of Quintius Fabius Pictor (3rd century) and Lucius Calpurnius Piso Frugi. Ennius and Naevius both wrote epic poems on Roman subjects, only fragments of which survive. Plautus and Terrence are well-preserved examples of early Roman comedy, but they were just two of many poets who were producing for the stage at the time. | [
"The size of the population of Rome at the time also needs to be considered. In its early days, Rome was still a city-state of only regional significance, and its territory did not stretch beyond 50 km (30 mi) from the city. Cornell notes that the estimates of the population of Rome in the late 6th century BC, base... |
why isn't the data on a black box saved 'in the cloud'? | Some of the newer devices can upload data, but it's a recent development that hasn't yet spread to every airline in every territory.
It's a lot of data to push, if you don't have a good connection. Many planes just don't have that sort of bandwidth. | [
"For Backblaze B2 Cloud Storage, data is stored in Backblaze Storage Pods and Vaults using Reed-Solomon erasure coding. Encryption is handled entirely by the user and client software used to manage the stored data, making it immune to government subpoena or data breach and protecting the data during transfer and ul... |
if there are over 7 billion people in the world & only a limited number of features on the face (eyes, nose, chin, etc.)that can determine how a person looks, why is it that almost everyone looks different? | There may be a limited number of features on human face, but there is a near infinite number of tiny changes you can make to them.
Subtle changes in size, shape, and position of each of the individual features all add up to give everyone their own unique look.
Recognizing faces is immensely important for non-verbal human communication, as well as being able to identify friends and family, and therefore the human brain evolved to be very, very good at facial recognition. | [
"Judgments made by others are greatly influenced by facial appearance from multiple cues. There is a wealth of information that people gather simply from a person's face in the blink of an eye, such as gender, emotion, physical attractiveness, competence, threat level and trustworthiness. One of the most highly dev... |
when big movie producers send out movies to be reviewed by critics, shouldn't it be easy to catch who uploaded the dvdscr? | It's a decent idea.
Amazon tried to do something simillar for their e-book sale, they thought of placing 1-2 random spelling mistakes in each one, to see who uploaded something at a torrent tracker. But eventually they abandoned the plan.
I'm not answering your question though :( | [
"By clicking on the name of critics closest to your film tastes, you get a list of the movies they've seen that you haven't; in order from their highest rated films, down to the lowest rated. This method allows critics to not only use recommendations for what movies to go see, also what movies to avoid seeing.\n",
... |
why are fruits that can be grown on the east coast so much more expensive to purchase than produce in california? | /u/friend1949 explained why the shipping costs don't add significantly to the price, but that doesn't explain why the east coast produce is *more* expensive.
Part of the answer is that the farms on the east coast are smaller, and don't have the economies of scale. But also locally grown produce is *perceived* as being better, thus allowing stores to charge more. It *is* better in many cases, but the perception is what's important and that applies across the board. Two well known examples of being better are fresh picked strawberries and tomatoes. (I think it was Garrison Keillor who described the pink, flavorless, mass-produced tomatoes as "strip mined.")
Apples, which you mentioned, are more interesting because they have names attached to their varieties, some of which are well-known trademarks, valuable as such. Most of the Oregon apples that I see on the east coast are Red Delicious - consistent, predictable, with a long shelf life, and a slightly sweet but bland flavor. Kids are very happy with them, but all it took was one trip to a Pennsylvania apple orchard during apple season to show me how boring they are.
Compare that to Honeycrisp, a more recent variety that's both patented and trademarked by the University of Minnesota. (According to Wikipedia, the patent has expired in the US, and the trademark may be at risk.) It's usually sweeter than the better known varieties, has a bit more flavor, and decent shelf life. For whatever reason, their marketing has been successful and it commands a premium (often a dollar per pound more in the stores I frequent compared to other north east varieties).
I also tried some Sweet Tango apples this year. This is a newer variety, also from U. Minn, and descended from the Honeycrisp. But, in spite of having much smaller supplies, it was cheaper than the Honeycrisp. Why? Because it's not as well known. Maybe someday it will be. | [
"Compared to other states, California has a large agriculture industry (including fruit, vegetables, dairy, and wine production), but at less than 2% of the GDP, it makes a relatively minor direct contribution to the state's overall economy. The total economic contribution is likely more than double this value (see... |
why can't you compress a rar file with rar or zip? | Compression is a technique for finding patterns in a file and writing it in a way that takes more space. For example instead of writing "aaaaaaaa" you may write 8*"a" which is much shorter. Or instead of writing "abcdefgh" you may write "a"-"h". However if you have already compressed a file and written it in the shortest way you can think of then another compression program will not have much luck trying to compress it further.
If you think of your file as a sponge. It consists of a sponge material and a lot of air. This is practical for cleaning but not very practical for transport. So you put in though a vacuum sealing machine to suck all the air out and put on a plastic seal to keep all the air out. Now the sponge is much smaller. But you read of another way to do it by using a vice. However when you put the already compressed sponge in the vice you can not get it much smaller. This is like trying to compress an already compressed file. | [
" files are archives that store multiple files. ZIP allows contained files to be compressed using many different methods, as well as simply storing a file without compressing it. Each file is stored separately, allowing different files in the same archive to be compressed using different methods. Because the files ... |
Considering the universe is constantly expanding, what would happen if you suddenly stopped in place? | Weird as it might sound, the expansion of the Universe doesn't actually mean that you're moving at all. It means that the distance we measure between two fixed points will grow with time. It's a statement about how we measure distances - or in other words, the geometry of the Universe - rather than what the stuff in the Universe is doing. So there's no point asking what would happen if you stopped in place, because to a very good approximation (ignoring our motion around the Sun, within the galaxy, etc., which are negligible on cosmic scales), you're stopped already! | [
"The expansion of the universe reaches an infinite degree in finite time, causing expansion to accelerate without bounds. This acceleration necessarily passes the speed of light (since it involves expansion of the universe itself, not particles moving within it), causing more and more objects to leave our observabl... |
Why were so many Nazi war criminals released very early into their prison sentences? | Not only were Nazi war criminals released relatively early into their sentences, but also Japanese war criminals. This largely took place in the mid-1950's, not only by the United States, but the majority of the Western Allies, who realised that there was limited political value in holding war criminals, who were seen as a relic of the immediate post-war disgust by the Allies of atrocities committed by the Axis forces.
While there continued to be a desire to punish those who had committed such atrocities, it was also countered by a perceived need to move on from the war, and engage in the Cold War.
Especially in regards to Japanese war criminals, it was felt that releasing them would strengthen ties to Japan, and limit the perception of a punitive occupation. While I don't have similar sources for Nazi war criminals, it seems likely that the Western Allies held similar conceptions in relation to West Germany, which was the centre point of the Cold War at the time.
Another aspect was that the Soviets still had a large number of German POWs at the time. By releasing war criminals early, the Western Allies were able to claim that they had legitimate claims to representing freedom and international cooperation. The influence of international religious and pacifist organisations also influenced diplomats and politicians, as well as the general public, with a growing campaign for clemency.
Sources:
Wilson S., Cribb R., Trefalt B., and Aszkielowicz D., "Japanese War Criminals and the Politics of Justice, 1945-1958" 2017.
| [
"Most of the perpetrators of Nazi war crimes were never charged, and returned unremarked to civilian life. The West German Central Prosecution Office of Nazi War Criminals only charged about a hundred former \"Einsatzgruppe\" members with war crimes. And as time went on, it became more difficult to obtain prosecuti... |
Sports in History | Related:
[What were the most popular sports in your fields (pun totally intended)? Is the game still around? How has it changed? Why did it die?] (_URL_3_)
[What were and where were the earliest known sports and tests of skill?] (_URL_2_)
[Over the last few centuries, how did organized sports grow from a pastime, to the crazy multi-billion dollar industry that it is today?] (_URL_1_)
[Why isn't Soccer the most popular sport in the former 'white' dominions of the British Empire?] (_URL_0_) | [
"The roots of modern sports can be found in the mid-nineteenth century in Great Britain and the United States where first professional sports were organised in mining and industrial towns and cities. Back then, sport competition was conducted mostly on local and national level. First signs of globalization in that ... |
Please steer me in the right direction about Civil wars in Republican Rome | Could you elaborate a bit?
* What's the paper for?
* Where have you searched for sources?
* What have you found so far?
* What do you know already? (You do know *something*.)
Anything else you may think is relevant. | [
"In 49 BC, the last Republican civil war was initiated after Julius Caesar defied senatorial orders to disband his army following the conclusion of hostilities in Gaul. He crossed over the Rubicon river with the 13th Legion, a clear violation of Roman Law, and marched to Rome. The Optimates fled to Greece under the... |
how does diet coke cause cancer? was that just media hype for a while, or is there legitimacy behind it? | Diet Coke contains Aspartame, which is an artificial sweetener that many people believed for a long time helped contribute to cancer, specifically brain cancer.
While there are people that will argue this is true and swear by it, the overwhelming majority of the medical industry believes that it is not carcinogenic in any way if consumed at levels that are likely in everyday life.
This is intuitive because Aspartame breaks down into Aspartic Acid, Methanol, and Phenylalanine in your small intestine before it is absorbed into your blood stream. All 3 of these things are likely to be found in higher concentrations after you eat a steak, for example. So unless you think steak causes cancer, it isn't any more likely that Aspartame does.
Please don't confuse this as saying that Aspartame is completely harmless, or that it's even effective as a dieting aid; it just doesn't cause cancer.
TL;DR Either steak causes cancer too, or neither do | [
"Studies on laboratory rats during the early 1970s linked high volumes of cyclamate and saccharin with the development of bladder cancer. As a result, the United States Congress mandated that further studies of saccharin be performed and required that all food containing saccharin bear a label warning that the swee... |
clueless about economics. how will the dow dropping 1,400+ points today and a potential recesssion/etc affect everday working people like me? those who aren't wealthy. | Immediately, it won't, outside of any 401k you may have. If the market rebounds within a month or so, you probably won't see much impact overall. If the drop lingers, then you can see potential layoffs and reduced hours from employers. | [
"BULLET::::- On December 10, 2016, Dent predicted that the Dow Jones Industrial average could fall 17,000 points as a result of Donald Trump's election win. Less than two weeks later, Dent reversed his opinion and thinks there is short term growth for the US stock market, but demographic forces will keep the econom... |
The rule of India by East India Company is famously cited as a case of Corporation ruling an entire country. How did this work in practise? Did they separate their Commercial activities and Governance? | Follow up question: what was the British people's opinion of this rule by the East Indian company? Did they have any anxieties about a company having so much power or was it mostly just accepted? | [
"The Company Rule in India refers to areas in the Indian subcontinent which were under the rule of British East Indian Company. The East Indian Company began its rule over the Indian subcontinent starting with the Battle of Plessey, which ultimately led to the vanquishing of the Bengal Subah and the founding of the... |
Do worms have a home? | They just kind of roam around eating tasty soil. No set place of residence other than the entire patch of soil they came off of | [
"Acorn worms are solitary worm-shaped organisms. They generally live in burrows (the earliest secreted tubes) and are deposit feeders, but some species are pharyngeal filter feeders, while the family Torquaratoridae are free living detritivores. Many are well known for their production and accumulation of various h... |
How much difference was there in the way different ancient Mediterranean people dressed and clothed themselves, before the dominance of the Roman Empire? | Unfortunately I can't give you a very full answer at the moment as I am away from my computer for today, but I can write something more detailed tomorrow. Until then, I would recommend this website: _URL_0_
Along the side you can see there is a section dedicated to costume. It does not deal with North Africa but many of the same issues apply. One of the major problems is that we have only very scattered information on what "the man on the street" wore, as clothing does not preserve, and so we are dependent on portraits. As is the case today, clothing in a portrait does not necessarily reflect everyday ware. | [
"The clothing of ancient Italy, like that of ancient Greece, is well known from art, literature & archaeology. Although aspects of Roman clothing have had an enormous appeal to the Western imagination, the dress and customs of the Etruscan civilization that inhabited Italy before the Romans are less well imitated (... |
What is the fastest you can move, taking into account relativity? | Massive objects can get asymptotically close to the speed of light given enough force. | [
"The description of motion in relativity requires more than one concept of speed. Coordinate speed is the coordinate distance measured by the observer divided by the coordinate time of the observer. Proper speed is the local proper distance divided by the local proper time. For example, at the event horizon of a bl... |
POW mail in WWII: were mail ships neutral or was mail routed through neutral countries/states, or... | I believe this was answered in another thread, so to make a long story short, the [Red Cross did most of the leg work of delivering mail to prisoners of war](_URL_1_), at least in the European theater. Mail would be routed through a neutral country such as [Portugal, Switzerland or Sweden] (_URL_0_), then sent on to the POW camps, typically by rail. As the Red Cross was considered an illegitimate target by all belligerents, RC shipments were considered to be out of bounds for targeting. However, due to the fact on the ground that most shipment lines were used for military purposes as a priority, RC shipments could and would occasionally be destroyed.
This model was attempted in the Pacific, however, the Japanese had not signed on to the different Conventions regarding treatment of Prisoners of War, and it was much more difficult for the RC to get supplies or correspondence to them. | [
"Military mail was subjected to censorship when it was the primary means for deployed servicemen to communicate with their families. The following text was printed on the message (non-address) side of standardized postcard \"Subron 4 Standard Form No. F14 471-A-S/M Base. PH-7-15-41-20M.\" distributed to naval perso... |
what is this 'google dream code' thing i keep seeing every where and what is it used for? | Think of your own brain, and imagine you are five (slaps knee), lying down on a field of grass looking up at all of the funny shaped clouds in the sky.
You notice one cloud looks like something, but you can't quite put your finger on it. You think of every single thing you've ever seen in your life that kind of looks like this cloud, and naturally, this takes you awhile because you're young. Finally, after a bit, you realize that this cloud looks like a dog! So you start imagining dogs in all of the funny scenarios you've seen them in, until you notice another cloud you want to think about next.
This is a pretty good analogy of what's going on in [Google's DeepDream project](_URL_1_). Essentially, Google made an [artificial brain](_URL_3_) modeled after our own and is testing how much this brain knows by feeding it "cloud images" and seeing what it thinks about. You know how you thought that cloud looked like a dog? Well, perhaps at five years old, you were really into dogs and hence know a lot about them. Same thing with DeepDream: If you give it a "cloud image" and it outputs a bird-like image, then you know that this artificial brain in particular must be "trained" to know what birds look like, especially if you have a bird-like cloud in your cloud image.
The important thing to realize is that these "cloud images" do NOT have to be pictures of clouds! They can be anything: a selfie of yourself, a landscape picture, etc. The artificial brain will essentially just emphasize the features it's been trained to recognize. If you look at the [example gallery](_URL_0_), you can see some pretty psychedelic results. The purpose of this project is mainly for researching and improving these artificial brains, and making them better for more applicable things in the future.
**TL;DR** Google made a robot brain and is seeing what it recognizes by giving it "cloud images", and examining the results so they can make the brains better.
[Google gives a more complicated and thorough explanation of all of this in their research blog!](_URL_2_)
| [
"McPhee launched www.dreamdoctor.com in 1997. It was among the first sites on the Internet devoted entirely to providing credible information about dreams and sleep. Through it, he had amassed the largest database of dreams in the world. With it, he broke their code. Taking a scientific approach to dream interpreta... |
Why did elevated beds arise in some cultures while others use beds low to the ground? | **EDIT: /u/extesser is right, it's mostly dominated by heat conduction and not a temperature gradient. I'll leave the post untouched for the history books, since it sparked some interesting replies!**
_________________________________________________________
I can only speak for the Vikings in Norway. Temperature is one reason for why it emerges. Cold air sinks, hot air rises.
If you're a Viking living in a longhouse(ref: _URL_0_ ), sleeping on the floor might just kill you. Get up on a bench, and you're much better off.
Ideally you'd want to stay up against the roof if you wanted to stay as warm as possible - but smoke from the firepits collect there so the practical middleground would be benches or elaborate furniture with legs.
I can't speak about what they do in the tropics, but I know from personal experience that bugs alone make elevated beds an attractive solution. | [
"Platform bed development was closely intertwined with the evolution of the modern bed. The earliest humans most probably slept on the ground. It would have been cold, hard and offered no protection from crawling insects or small animals. Readily available piles of leaves and branches could be covered with animal p... |
If a mosquito bites a person who is HIV positive, then bites me, will I become HIV positive? | [This](_URL_0_) is a pretty good answer. | [
"When mosquitoes bite a person, they do not inject the blood of a previous victim into the person they bite next. Mosquitoes do, however, inject their saliva into their victims, which may carry diseases such as dengue fever, malaria, yellow fever, or West Nile virus and can infect a bitten person with these disease... |
if california's housing market is already incredibly overpriced, why does it keep rising? | Supply and demand. More people want to live there than there are places to live.
The two obvious next questions are "Why is the supply so low?" and "Why is the demand so high?".
**Why is the Supply so low?**
Short answer: Few people actually want it to rise.
The current homeowners don't, because their home price keeps going up with less competition. A lot of the "original" residents don't, because they want the city to retain it's quaint, artistic charm and not be dominated by skyscrapers. The will of these people is expressed in restrictive regulations, and because of them, the only new housing that makes money is luxury housing. (Because if a place is expensive to build, it will be expensive to rent.) People rebel against this, dragging it out in court for years or just torching the construction sites, so the supply is not keeping up with the demand. The root cause is frankly that a lot of people there don't understand or believe basic economics. There's actually no such thing as a "luxury house". (You can buy a mansion in Detroit for $1.) It's all just supply and demand, and by preventing new housing from being built, _every_ house is turning into a "luxury house." A normal-looking 1 bedroom, 900sqft single-family home in the city recently sold for $3 million.
**Why is the Demand so high?**
The tech industry and foreign investors.
Tech pays big bucks and is still booming. The average starting salary is $90k and I personally know a guy who took a $400k pay CUT in order to work in a cooler part of the industry. People there are loaded.
Foreign investors have also jumped in, raising the demand even more. They see the problems with the supply of housing, so it's a no-brainer to invest.
So there's tons of demand and the supply can't keep up. This makes prices ridiculous. | [
"The state’s high rent prices have translated into increased homelessness, more households spending half their income on housing, and an exodus of low and middle income households leaving to states with lower cost of living. The housing shortage negatively impacts the Economy of California. A 2016 McKinsey & Compan... |
When a person loses their vision in one eye, is their loss of depth-perception permanent or does the brain find a way to adapt? | There are many monocular cues to depth such as parallax, relative size, atmospheric perspective, etc. you can find a list [here](_URL_3_). Some of these are both relative cues (something is farther away than something else) and some are absolute (something is this far away). If you close one of your eyes, the world doesn't suddenly seem totally flat. However, binocular cues like binocular disparity can lead to some special sensations of depth like [stereopsis](_URL_1_). Consider the difference, for example, between looking at the objects on the table in front of you and the experience of seeing them at different distances vs. looking at a photograph of the same table in which you can tell which objects are nearer and farther away, but it lacks the same sense of depth. Or, if you've ever been to a 3D movie, the difference between that and a 2D movie. The sensation of something coming off of the screen toward you is caused by stereopsis from binocular disparity, which occurs when light from objects falls on different relative positions of your retinas. This is the same principle behind the [stereoscope](_URL_0_). However, even with a single eye you can approximate this by moving a picture side-to-side quickly so that it falls on different positions of the same eye. This is sometimes called [wiggle steroscopy](_URL_2_).
See [this](_URL_4_) recent post on the same topic. | [
"It is known that the act of visual perception is a cognitive exercise and not merely a stimulus response. In other words, perception is a learned ability which we develop in infancy. Kenneth Ogle of the Mayo Clinic, reported 1967 that left and right-eye information can be presented alternatively to the left and ri... |
When / why did it become a custom to put your hand on your heart for patriotic moments (specifically US pledge of allegiance and national anthem) | The hand over one's heart is a civilian salute. It is for use by civilians (people who are not in a nation's armed forces) at moments that would be appropriate for a military salute.
Some countries (the US, Italy, etc.) use the hand over the heart as a civilian salute, some (Latin American countries for example) have different civilian salutes - like the hand across the chest with the palm facing down - while others (UK, Canada) have no official civilian salute.
In the US, prior to 1942, the Bellamy Salute (similar to the Roman/Nazi salute) was the official civilian salute. | [
"The recital was accompanied with a salute to the flag known as the Bellamy salute, described in detail by Bellamy. During World War II, the salute was replaced with a hand-over-heart gesture because the original form involved stretching the arm out towards the flag in a manner that resembled the later Nazi salute.... |
I know why the inter-war Germany was called 'Weimar Republic', but who started using that term? And when? And did it have a positive/negative connotation? | The name "Weimar Republic" was not really used much during the existence of the Republic. The Republic used "Deutsches Reich" as the official name, and "Republik" in various compounds, but Weimar was an informal title at best. Some Anglophone publications used Weimar Republic yet this was typically a minor naming convention. The actual town of Weimar had a rather strained relationship with the Republic. It was the site of the Republic's constitutional convention, chosen mostly because it was away from the chaos of Berlin, and the was the center for Gropius's Bauhaus movement. Yet the largely conservative Weimar population had little love for the Republic and many locals resented the Bauhaus for bringing in foreigners and Jews into Goethe's birthplace. Hitler and the NSDAP though were the ones who popularized the name Weimar Republic, and he and other NSDAP propagandists used it as a slur. The name stuck after 1933 and filtered into opponents of the regime as well as outside of Germany. This [google Ngram](_URL_1_) for English shows the post-1930 pickup, as does this [Ngram](_URL_0_) for "Weimarer Republik." As both Ngrams indicate, the Weimar Republic clearly became the "Weimar Republic" after 1945.
The fact that historians and other writers use Weimar Republic when the actual government in question did not is not terribly unusual. There are other examples of Anglophone names that are anachronistic or inaccurate. The Polish-Lithuanian Commonwealth is one, as is the Byzantine Empire. One notable example that sometimes strikes pedants is the use of Tsar after Peter I. Peter I accepted the title All-Russian Imperator in 1721 and it became the first title used by subsequent Romanovs. This was part of Peter I's efforts at building up his prestige and self-styling as a modern European monarch who had no peers. The tsar title implied he was still Muscovite, but imperator is a more ambitious. Subsequent Romanovs would use the imperial title as their main title, and tsar became relegated to various monarchical appendages that signified areas over which the tsar had suzerainty, such as the Tsar of Kazan, Tsar of Siberia, etc. The title Tsar also entered into the vernacular as a shorthand for the Russian ruler in the non-Russian world, but subsequent emperors after Peter I sometimes preferred Tsar over Emperor, such as the archconservative Alexander III. | [
"The 1918–1933 republic, which was also called German Reich, was ignored and denounced by the Nazis as a historical aberration. The name \"Weimar Republic\" was first used in 1929 after Hitler referred to the period as the \"\"Republik von Weimar\"\" (Republic of Weimar) at a rally in Munich with the term later bec... |
Who were the most influential figures in the Bolshevik Party who weren't executed during the purges? Why did Stalin spare them? | I think most influential is pretty subjective and the range of purges meant pretty much everyone who -was- overly influential and famous got purged. And the remainder of the Communist party in the aftermath of Stalin's purges was absolutely subordinated to him (with the possible exception of Beria)
The closest I can think of would be someone like Anastas Mikoyan. If you look at Soviet Politburo membership list basically everyone on it from 1917-mid 1930s who wasn't firmly on Stalin's side all the way through got shot. | [
"Eventually almost all of the Bolsheviks who had played prominent roles during the Russian Revolution of 1917, or in Lenin's Soviet government, were executed. Out of six members of the original Politburo during the 1917 October Revolution who lived until the Great Purge, Stalin himself was the only one who remained... |
French Colonies Gone Wrong | It is hardly just France, The Belgian Congo and Portuguese Angola are hardly examples of successful states. For every successful colonial state you can point towards another that has been unsuccessful. | [
"The French were unhappy about the loss of this valuable colony, and planned to regain them in any future conflict with Britain. In 1764, the French launched incursions against the coast of Senegal from Gorée angering the British cabinet. In 1779 during the American War of Independence a French force landed and sei... |
when two tvs in tvs same house are run through the same cable service, why does one seem to always lag behind the other? | A modern TV contains electronics which decode the digital HDMI signal and then turn it back into a picture and sound. Unfortunately these usually introduce a delay, and on some models it can be a notable fraction of a second, and it's not a standardized amount. | [
"In the 1980s, it was more common to split one cable television feed into two separate channels – one that aired during the daytime and the other at night; this method was used in particular by cable systems to account for headend infrastructures that limited the number of channels that could be carried on a single... |
What actually is going on as electrons move through a circuit? | The best way to think of it is that the electrons in a wire are moving because of the electric field in the wire. The electric field is established in the wire when you connect it to the battery terminals, and the speed at which it propagates through the wire is the speed of light in that wire (or circuit).
You're basically right about the resistor; the propagation of electrons is impeded in that they scatter off impurities and such, causing the electrons to lose energy and the resistor material to gain thermal energy. | [
"Therefore, in this wire the electrons are flowing at the rate of . At 60 Hz alternating current, this means that within half a cycle the electrons drift less than 0.2 μm. In other words, electrons flowing across the contact point in a switch will never actually leave the switch.\n",
"Electrons can move (slowly) ... |
why can't leaded engines use unleaded petrol? | Neither of those is correct. The leaded gasoline vapor can be compressed more than unleaded without spontaneously exploding due to the temperature increase. The compression ratio is determined by engine geometry, so an engine designed for leaded gas will compress unleaded gas to the point where it spontaneously ignites, throwing off the cycle and damaging the engine.
EDIT: I didn't explain why they would design for such a high compression ratio. A higher compression ratio generally allows you to be more efficient and cleaner. However, most governments have decided that these benefits do not outweigh the negatives of putting a ridiculous amount of lead in the air. | [
"Lead replacement petrol (LRP) was developed for vehicles designed to run on leaded fuels and incompatible with unleaded fuels. Rather than tetraethyllead it contains other metals such as potassium compounds or methylcyclopentadienyl manganese tricarbonyl (MMT); these are purported to buffer soft exhaust valves and... |
From where do we measure distances between celestial bodies? (center-to-center? surface-to-surface?) | I think the answers provided so far can be fairly misleading.
The real answer is, the order of magnitude between celestial bodies is SIGNIFICANTLY greater than the size of the bodies.
Analogy: Lets say you're measuring the distance between two marbles that are 100 feet away from each other. Then you ask - is my distance measurement from center to center or is it from surface to surface? Well, the difference offers you 0.5 inches in precision, but you really can't measure distance to that precision anyway, so you say '100 feet' or '101 feet'. But you don't have it down to the 0.1 inch scale that you can say 'surface to surface distance' or vice versa.
jswhitten's response is a good example. He says the moon is 400,000 km away - actually it's 384,000 km away. The rounding error is 16,000 km, which is greater than the diameter of earth! So we're not that precise. Especially when we're talking about the distance to farther planets, because their orbits are elliptical, which results in big error bars in your distances anyway. | [
"When a horizontal angle measurement is made between two known points on land, the observer will be located at the apex of a triangle, with the other two corners of this triangle consisting of the landmark pair. The observer will also be sitting on a set of points that fall along a large circle. The diameter of the... |
why does our heartbeat and blood pressure lower in our sleep and why is it important for our body to do so? | * You are lying down. It takes more effort for your heart to pump blood straight up to your brain than it takes to pump when your whole body is horizontal
* Your muscles aren't moving during sleep so they requires less blood
* Your brain uses just as much blood/oxygen when sleeping as when awake | [
"Zaregarizi and his team have concluded that the acute time of falling asleep was where beneficial cardiovascular changes take place. This study has indicated that a large decline in blood pressure occurs during the daytime sleep-onset period only when sleep is expected; however, when subjects rest in a supine posi... |
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