question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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how do headphones create sound by connecting a metal post into a metal housing and sending information through a wire into speakers? | They don't send "information", they send an analog electrical signal. That signal is run through a coil to produce a magnetic field. A small permanent magnet reacts to the field, moving a small speaker cone back and forth to produce sound waves that your ear can detect. | [
"Electrostatic and piezoelectric noise can also become an issue in exotic headphone systems, if the headphones have a relatively high input impedance compared to traditional speakers which have a nominal impedance of 8 Ohms. This is where a careful choice of insulating materials can make a difference. This type of ... |
why do so many people equate abortion with murder when an unwanted baby is often subject to a lifetime of pain and depression due to their parent's inability to care for the child? | Because apparently a life full of suffering and pain that likely ends tragically, is better than not being alive at all. | [
"Unsafe abortion is another major cause of maternal death. According to the World Health Organization in 2009, every eight minutes a woman died from complications arising from unsafe abortions. Complications include hemorrhage, infection, sepsis and genital trauma.\n",
"Unsafe abortions results in complications f... |
if dust in houses is mostly caused by dead human skin cells then why are old abandoned houses always so dusty? | You've been misinformed. Dust is not made up of mainly human skin. It's just that every sample of dust you take inside a home will always contain some human skin.
Dust isade of various small particles. Like fibers from clothing or plants, pollen aggregates, etc. And there's always some dust in the air as can be seen when a ray of light shining through a room is observed from the side.
Since dust particles are very light they can ride on air currents but since their density is greater than air they will always settle on surfaces given enough time. Since abandoned houses usually have large undisturbed volumes of air all that dust will slowly settle on surfaces. (As long as it's not wet or there are huge drafts inside, this will cause more general "dirt" to accumulate).
| [
"House dust mites are present indoors wherever humans live. Positive tests for dust mite allergies are extremely common among people with asthma. Dust mites are microscopic arachnids whose primary food is dead human skin cells, but they do not live on living people. They and their feces and other allergens which th... |
I wonder what historians think of Niall Ferguson. | I can only speak about his work on empire - which most historians dismiss as too one-sided and just bad. To put it bluntly, he gives a very distorted view of the British Empire, implying that, on the whole, it was an example of a "benevolent" imperial power who brought progress and modernity to the colonies in contrast to those big, bad, icky empires of France, Germany, and Japan. That, faced with the alternative, the British Empire was a positive historical phenomenon for the colonial world. Of course, specialists on the British empire (well, new generation) have the opposite view. They point to the harrowing violence the British colonial police inflicted in Kenya during the 1950s (concentration camps, systematic torture), suppression of Irish nationalism in the 1920s via the vicious Black and Tans, civil war and mass killings triggered by the sudden partition of British India, using air raids to terrorize villagers into submission in post-WWI Iraq, etc. etc. Empire was (is?) much more complicated than just constant victimization, of course. But at the root of all the real "progress" or change introduced into the colonies was exploitation and violence.
On the other hand, he's very charming and persuasive in person (I've heard him speak in public). I think his early work on finance is respected more but I haven't read it. He's published a lot, good at generating public interest in otherwise boring topics, which is probably why he's at Harvard. But, no, I don't expect him being elected president of the American Historical Association anytime soon. | [
"Ferguson was sympathetic to traditional societies, such as the Highlands, for producing courage and loyalty. He criticized commercial society as making men weak, dishonourable and unconcerned for their community. Ferguson has been called \"the father of modern sociology\" for his contributions to the early develop... |
why can't i become the president of the united states (i was born in canada)? | Its the rules
**US Constitution, Article II, Section 1**
No person except a natural born citizen, or a citizen of the United States, at the time of the adoption of this Constitution, shall be eligible to the office of President; neither shall any person be eligible to that office who shall not have attained to the age of thirty-five years, and been fourteen years a resident within the United States. | [
"Every president to date was either a citizen at the adoption of the Constitution in 1789 or born in the United States; of the former group, all except one had two parents with citizenship in what would become the U.S. (Andrew Jackson). Of those in the latter group, every president except two (Chester A. Arthur and... |
what does curiosity do besides taking pictures of mars? | It's got a chemical sniffer, a laser, and a drill. All for looking for chemistry of one form or another that might indicate prior life, or the possibility of future life. And when it meets Spirit and Opportunity they can join to become MegaRover™! | [
"Curiosity is a car-sized rover designed to explore the crater Gale on Mars as part of NASA's Mars Science Laboratory mission (MSL). \"Curiosity\" was launched from Cape Canaveral on November 26, 2011, at 15:02 UTC and landed on Aeolis Palus inside Gale on Mars on August 6, 2012, 05:17 UTC. The Bradbury Landing sit... |
When did a majority of Texans begin speaking English instead of Spanish? | Stephen Austin founded his colony in 1821. At that time, there were fewer than 8,000 Spanish-speaking *tejanos* and perhaps 15,000 Native Americans in Texas. These numbers should be taken with a grain of salt. Many of the Native Americans in Texas were nomadic and lived in Texas for only part of the year (or simply passed through from time to time while still considering it home). There were also a number of small isolated Spanish and American families and settlements who were in Texas specifically to avoid being counted or taxed (or arrested).
Within five years, Austin's colony numbered closed to 2,000 (including about 500 slaves), and was therefore already a very significant part of the population.
American colonists began flooding in during the 1820s - by 1831, Austin's colony had a recorded population of 20,000, so by this point the Americans (again, including their slaves) had overtaken Native Americans as the largest population in Texas. When Juan Almonte inspected the American colony on behalf of the Mexican government in 1834, he reported its population as nearly 25,000 - and this is the point where we can say a majority of Texans spoke English.
EDIT: Source, [the Texas State Historical Association](_URL_0_). More info on Texas' population history there. | [
"After Mexico gained independence in 1821, Mexican Texas legally permitted an influx of English-speaking Anglo settlers from the United States (mainly the Southern United States), who within a decade outnumbered Hispanics in Texas, making English as common as Spanish in central and north Texas. After Texas became a... |
What source(s) (primary if possie) could be used as evidence for a paper on the Nazi regieme's efforts to conceal the Holocaust from the public eye? | Nazi-Germany did not try to conceal the holocaust in the east at all. Public mass shootings were common practice. Please read Mark Mazower's Dark Continent for background.
They did try to conceal the holocaust in the west however. Primary evidence could be the administrations of the different Jewish Councils and e.g. the Mauthausen death books.
The first shows you the administration of Jewish populations of European countries and the treacherous methods and terminology the Nazis used to push the Jewish populations voluntarily towards transit, work and death camps. The second example (available online) shows you the disguised terminology of the causes of death in KZ Mauthausen. It is very curious that nobody in Mauthausen is beaten to death and death penalties are described as: "auf der Flücht erschossen". But to have a solid case there you must match the official Nazi statement to eyewitness accounts. That is possible, but it takes time to go to the right archives and do proper research.
Another example: In the beginning the KZ administrations still used to send certificates of deaths back towards the city the prisoner once lived. After receiving repeated requests for the remains and personal belongings, the Nazi authorities stopped sending those certificates. Of course those poor individuals ended up in the crematoria and mass graves, so there was nothing to claim left. This is also provable, but again it will take time to investigate and visit the archives. | [
"The pamphlet alleges that no documentary evidence exists of the Nazi plan to exterminate the Jews. The Crown adduced speeches by Heinrich Himmler, head of the SS, made on October 4, 1943, to his troops in Posen in which he refers to the program of extermination of the Jews. Himmler stated: \"I also want to talk to... |
What is the role of a neutral wire in an A/C? Does the return current in an A/C pass through the live or the neutral wire? | It's the same as the role of neutral wire in DC: in order for the current to move, it has to have a conductor to move through.
In a closed circuit, there is no difference between the live and the neutral wire; the only real difference is that if the circuit is open, touching one will electrocute you (because that's the one that's connected to the power source), and touching the other will do nothing. (Assuming your feet are grounded.) | [
"BULLET::::- Neutral wire is the return conductor of a circuit; in building wiring systems, the neutral wire is connected to earth ground at only one point. North American standards state that the neutral is neither switched nor fused except in very narrowly defined circumstances. The neutral is connected to the ce... |
how does glass work to help plants grow? | What do you mean?
Like greenhouses? They let in light and trap heat, allowing plants to grow in colder climates than they could otherwise. | [
"In cultivation this plant needs to be grown in a sharply-drained medium with a low nutrient content, at a minimum temperature of . In the United Kingdom, where it is best grown under glass due to high precipitation, it has gained the Royal Horticultural Society’s Award of Garden Merit.\n",
"Many commercial glass... |
why do red and blonde hair tend to run in the same families if there both recessive genes? | I'm not entirely sure of the allele frequencies of red/blonde hair but I'll continue regardless. By allele frequency I mean the number of people in the population who carry the particular gene variant/allele e.g. blonde/red hair
They must be at sufficiently high frequency that homozygotes (people with two copies of the blonde/red allele who therefore have blonde/red hair) and heterozygotes (Individuals who have the recessive allele for red/blonde hair and another dominant allele for e.g. brown hair) interbreed.
From this homozygote heterozygote pairing 50% of their children will be blonde/red head.
There is another factor which comes into play called Penetrance. This is kind of a difficult concept to grasp. We're used to thinking of a trait (e.g. hair colour) being coded for a single gene, of which there are multiple alleles (brown, red, blonde etc.). However, in reality most traits are encoded for by multiple genes which work together to produce the trait. Therefore genes which encode for specific traits (e.g. hair colour) can be highly penetrant i.e. if you have gene X you will get trait X, or have low penetrance i.e. if you have gene X, there is a lower chance you will exhibit train X due to the influence of multiple genes.
Sorry if this is a sucky, explanation, I'm tired. What i'm trying to say is that blonde/red hair alleles must be in the population in a sufficient frequency for people carrying these genes to mate often, and it must be highly penetrant.
| [
"One phenotype (brown/blonde) has a dominant brown allele and a recessive blond allele. A person with a brown allele will have brown hair; a person with no brown alleles will be blond. This explains why two brown-haired parents can produce a blond-haired child. However, this can only be possible if both parent are ... |
how does turning on a lightbulb use more electricity than keeping it running? | There must be an initial surge of energy to get the filament to the proper temperature to produce the light. | [
"Single-pole illuminated switches derive the power to energize their in-built illuminating source (usually, a \"neon\" lamp) from the current passing through the lamp(s) which they control. Such switches work satisfactorily with incandescent lamps, halogen lighting, and non-electronic fluorescent fixtures, because ... |
What led to the development of marine infantry units? | This is a bit of a throughout history question, so it would be best to narrow it down. In broad strokes though there are advantages in having troops who are specialized in certain aspects of warfare, ready to deploy abroad, and under control of your branch of service.
For a lot of history in many places naval warfare consisted of mainly trying to ram an enemy ship, or board it and take it over. When it was time for boarding it helped to have people on board whose main job was exactly that. Also the distinction between a combat ship and a transport or merchant ship wasn't always very well defined. You can look at the battle of Dover for a good example of this.
At first the fighters on the ships wouldn't have been marine specialists, but as time moves on and more professionalism and specialization entered the military specific marine units emerged. The tactics and equipment used in boarding an enemy ship would be different from fighting in the field.
Additionally, from an organizational stand point it's much easier if everyone is in the same organization and chain of command. Joint Operations have issues with inter service rivalry/misunderstanding even today, and a ship would always need a contingent of marines for security, so why should they belong to some wholly separate organization?
As time went on the concept of amphibious warfare became a natural fit for marine units, and the ability to have an expeditionary force trained and equipped for such means that your country has the ability to apply land force anywhere it's navy can get to. | [
"Marines became prominent during the Pacific War. These soldiers were capable of amphibious warfare on a scale not previously known. As Naval Infantry, both Japanese and American Marines enjoyed the support of naval craft such as battleships, cruisers, and the newly developed aircraft carriers. As with conventional... |
What tactics did viking raid victims come up with to counter the invasions? | First of all this is my first post in r/askhistorians. Apologies if the formatting is incorrect, if I'm honest I'm procrastinating from doing reading on my thesis. I hope it's useful. The answer below focuses primarily on Ireland.
Sources:
Primary:
Annals of Ulster
Life of Blathmacc
Secondary:
Clarke, Howard B. 'The Vikings in Ireland: A Historians Perspective'. Archaeology Ireland vol. 9, no. 3 (1995), pp. 7-9.
Cróinín, Daibhí Ó. Early Medieval Ireland 400-1200. Essex, 1995.
Doherty, Charles. 'The Vikings in Ireland: A Review' in Howard B. Clarke, Máire Ní Mhaonaigh and Raghnall Ó Floinn (eds.), 'Ireland and Scaninavia in the Early Viking Age'. Dublin, 1998, pp 292-311.
Doherty, Charles. 'The Viking Impact upon Ireland' in Anne-Christine Larsen (ed.), 'The Vikings in Ireland'. Roskilde, 2001, pp 29-37.
In regards to how the Irish responded you have to understand how the Irish kingship system was structured at the time. There were tiers of kingship, though a king of a townland could act independently of an "over" king. Before initial Viking appearances in Ireland these kings raided monasteries in each others territories as a display of dominance. However, one important thing to note is that they did not attack the sanctuary in the middle of monastery, as it was sacred. This is important as it acted a place for monks to hide when such raids occurred. The Irish kings were also well aware on the limits in terms of destruction which they could incur.
When the Vikings arrived, they were met with a non-unified resistance. If they defeated one local Irish king they gained very little in terms of land, and had to move onto the next local king, to fight again, for a small tract of land. In fact, the Vikings lost about as many battles as they won in Ireland. This style of warfare worked effectively against the Vikings versus the English system where a more unified form of kingship had grown. Once one king in England fell, the Vikings gained control of large tracts of land.
There is evidence that the Vikings were aware of the placement of Irish monasteries prior to their arrival, perhaps due to information gained in the Hebrides. They also became aware of what days to raid, as monasteries at this time served as proto-towns (Ireland had yet to develop what we would consider a town), but people gathered on feast days, and these were the days on which raids occurred.
The Viking response to the Irish system was to establish longforts on the boundaries between the Irish kingdoms, so they became a problem for both kings, but also neither as neither king wanted to deal with them. It was clear a raiding force was not going to be enough to gain a foothold in Ireland, as while in England there was infrastructure which could be taken and used, this did not exist in Ireland.
The Vikings then raided out from these longforts, attacking monasteries. This became an issue as initial raiders (pre-Christian Vikings) were unaware of the sacred nature of areas of these monasteries and burnt them in their entirety to the ground. This is demonstrated well in Walahfrid Strabo's 'Life of Blathmacc' in which the Abbott of Iona is murdered by the Vikings for refusing to show them to the burial site of Columba's remains. Round towers were not used as means of escape for monks, despite popular theory. Climbing into one is akin to climbing into a chimney with a fire lit in it.
It is clear that the Vikings became involved in the Irish political scene early on, as by AD 882 the Dublin Vikings had formed an alliance with the Southern Uí Néill and raided Armagh, but within seven years had made an alliance with the Northern Uí Néill to raid against the Southern Uí Néill.
As said above, the Irish response was disjointed, but violent and worked to the advantage of the Irish kings. Eventually the Vikings became naturalised (evidence at the Cherrywood site outside Dublin shows Viking farmers working land that had been used as farms from the Stone Age, meaning there was probably some form of intermingling).
The Dublin Vikings (as opposed to those in other longforts, who appear to have been separate groups) were expelled in 902 after Dublin was sacked. However, they returned in 917 and retook the city. The concept of expelling the Vikings is one which is subject to debate, as it appears the leadership was expelled as archaeological evidence shows the city continued to function. The assimilation of the Vikings can be seen further from this point on, as there are signs of intermarriage (through preserved records of names, which are hybrids), and intermarriage between kings, as can be seen with the three Gormlaiths, one of whom married high kings of Ireland.
Raids by this point were also not focused on taking monetary tolls, or slaves, as the Annals of Ulster tell us in 853 the Dublin Vikings exacting tributes of cattle and grain from the native population.
To be specific in military terms, there's little available in Ireland to my knowledge. Armour piercing arrowheads have been found in Dublin having been manufactured by the Dublin Vikings, though these are unlikely to have been used in Ireland, as the Irish wore no real armour at the time of their arrival and there's no evidence to suggest that this changed much until much later. These arrowheads were likely being exported to England, or further afield as part of the Viking economic hub.
On a tangential note, the Battle of Clontarf was not all that significant in real political terms. It was used as a piece of propaganda by Brian Boru's descendants as they were losing power in Munster and labelled as the battle in which he drove the Vikings from Ireland. Vikings in fact fought on both sides of the battle, and were mercenaries. The battle was not about removing Vikings from Ireland in any manner. They were an accepted part of Irish society at this point. Yes, the battle resulted in the death of Brian Boru, the then-high king of Ireland, but it simply saw Máel Sechnaill restored as high king of Ireland (having been high king before Brian).
In summary, the Irish initial resistance appears to have turned into acceptance with the Vikings. The Viking raids and initial attempted land grabs failed due to the disjointed nature of Irish kingship, and thus became involved on a political and economic level with the Irish. The Irish response to this was to accept it. | [
"Viking raids often lacked formation. They have been described as \"bees swarming.\" However, what they lacked in formation they made up with brutality. This naturalistic sense of unconventional warfare is rooted in their lack of organized leadership. These small fleets brutally but effectively scared locals and ma... |
If water conservation is so vital to mammals, why do we pee? Why not transfer toxins into stool and recycle the water? Are there any animals that have evolved to do this? | Safely excreting waste tends to be a balancing act between water and energy. Land animals in non-desert climates tend to urinate in the sense you are familiar with. However, animals in climates in which water is very precious or those which can't carry a lot of water due to weight (birds) use a different method of getting rid of waste.
A large part of what we're getting rid of in urine is nitrogen waste so that we don't build up ammonia. We get rid of nitrogen by making a compound called urea in a cycle called the urea cycle. It uses some energy to make, and takes a lot of water to get rid of. In contrast, birds, reptiles, and some desert mammals get rid of nitrogen by making a different compound called uric acid. This takes more energy, but can be excreted as a paste with only a little water in it (this is the white part of bird poop). It's a balancing act as to whether the water or the energy is generally more important, and so different species have gone different ways. | [
"Excretion is performed mainly by two small kidneys. In diapsids, uric acid is the main nitrogenous waste product; turtles, like mammals, excrete mainly urea. Unlike the kidneys of mammals and birds, reptile kidneys are unable to produce liquid urine more concentrated than their body fluid. This is because they lac... |
Why do dogs walk in a circle before they lay down? | There are a couple of theories ranging from circling behaviour intended to pad down grass to be more comfortable, to circling in order to judge wind direction and lay nose facing the breeze. There's little conclusive agreement on the true reason however. | [
"Going down with front legs in a bowing position can be an invitation to play if the dog is moving legs from side to side in a playful manner. Just as often, the dog is standing still while bowing and is using the signal to calm someone down. These signals often have double meanings and may be used in many differen... |
In US Presidential election history, has there been cases where the losing candidate completely refused to recognize the results of the election? | Hi there, I'm going to approve this question because it asks about the historical record, but for potential respondents: Please remember that our subreddit rules explicitly forbid both [discussion of current events](_URL_1_) as well as [political discussion/soapboxing](_URL_0_). | [
"The U.S. presidential election occurred on November 2, 2004. However, as in the 2000 U.S. election, the election was too close for a winner to be declared that night. By the next morning, the Republican campaign was declaring a victory while the results in several states remained too close for the media to declare... |
how did columbus communicated with the aztecs if they didn’t speak their language and vise versa? | Columbus didn't communicate with the Aztecs. He never met them.
Hernan Cortes was the man responsible for destroying the Aztec empire.
When Cortes first landed in the Yucatan he met Geronimo de Aguilar, a Spanish Franciscan priest who had survived a shipwreck followed by a period in captivity with the Maya. This priest had learned the Mayan language.
Later, Cortes fought and beat the Tabasco natives. They gave him 20 women. One of which was called La Malinche and would become Cortes' mistress. She knew the Aztec language and the Mayan language, so Cortes was then able to communicate to Montezuma of the Aztecs through these translators. | [
"The Aztec language, Nahuatl, was difficult for the Spanish troops stationed in Mexico to pronounce. The common ending \"tl\" sounded like \"te.\" Hernán Cortés' difficulties with the language was evident in the letters he sent, where he writes \"Temistitan\" instead of Tenochtitlan and the tribal god Huitzilopocht... |
Are new planets and stars currently being formed? | There are new planets and stars being formed all the time. And old ones being destroyed. We cannot directly or even indirectly observe most of this due to the distance between our solar system and these other systems and galaxies, but it is happening. In fact everything we are composed of, all of our atoms and those comprising our planet and sun, are from a now dead and Super-nova'd star.
Check out this video for some cool insight into the idea.
_URL_0_ | [
"An increasing number of extrasolar planet discoveries are being made with planets in planetary systems known as of . Rare Earth proponents argue life cannot arise outside Sun-like systems. However, some exobiologists have suggested that stars outside this range may give rise to life under the right circumstances; ... |
how integrals can calculate areas? | > how could it ever be accurate?
As you add more rectangles the closer you get to the true answer (because each rectangle will better approximate the curve). The more rectangles you add the closer the "error" is to zero.
Once you have an infinite number of them the error *is* zero. If you know what limits are it's quite literally the same thing. If every step has you get closer to reality, and you take an infinite number of steps, you'll get infinitely close to reality, which means you've arrived at the correct answer. | [
"In mathematics, a bilinear map is a function combining elements of two vector spaces to yield an element of a third vector space, and is linear in each of its arguments. Matrix multiplication is an example.\n",
"To define the Lebesgue integral requires the formal notion of a measure that, roughly, associates to ... |
Seeking for the translation of what Diogene said to Alexander the Great. | If I understand you right, you're asking for the Greek text? That's in Plutarch's Life of Alexander, 14.3. It looks like this:
> ‘μικρὸν’ εἶπεν, ‘ἀπὸ τοῦ ἡλίου μετάστηθι’
εἶπεν is "he said." So actual quote would be ‘μικρὸν ἀπὸ τοῦ ἡλίου μετάστηθι’
Writing Greek on an American keyboard is a pain in the ass. There are a couple of fonts available for it (TAPA uses GreekKeys, for instance). Honestly the easiest way I've found is to find the text online and copy and paste. I got this text from the [Perseus Project](_URL_0_). You may like to see that this site has the Greek text and the English translation, if you open the panel on the right. | [
"Aristippus was an envoy to Constantinople (1158-1160) when he received from the emperor Manuel I Comnenus a Greek copy of Ptolemy's \"Almagest\". A student of the Schola Medica Salernitana tracked down Aristippus and his copy on Mount Etna (observing an eruption) and proceeded to give a Latin translation. Though t... |
Is there number to acceleration of Universe expansion? | The expansion rate has units of inverse time (for practical reasons it is given as km/(s\*Megaparsec) but that is a length in numerator and denominator). How the expansion changes over time has units of inverse time squared: 1/s^(2).
It can be calculated with the second [Friedmann equation](_URL_0_). In the distant future the density (and pressure) of matter should become negligible and we are left with the cosmological constant only (assuming it is actually constant). Its value is about 1.1\*10^(-52)/m^(2), multiplied by c^(2)/3 we get 3.3\*10^(-36)/s^(2). That is still a weird number, but its inverse square root is about 17 billion years, and in the distant future (when distances increase as exponential function) that will be the time in which distances increase by a factor e. | [
"The definition of \"accelerating expansion\" is that the second time derivative of the cosmic scale factor, formula_2, is positive, which is equivalent to the deceleration parameter, formula_3, being negative. However, note this does not imply that the Hubble parameter is increasing with time. Since the Hubble par... |
how does the same model of device get software updates at different times during a rollout? | Every device had a unique serial number. The device sends its serial number to the update server which uses it to decide whether the device gets an update. | [
"A rolling release is typically implemented using small and frequent updates. However, simply having updates does not automatically mean that a piece of software is using a rolling release cycle; for this, the philosophy of developers must be to work with one code branch, versus discrete versions. When the rolling ... |
do "not for individual sale" warnings on products have any legal binding? | The point of the label is that required legal statements (like nutrition and ingredients) aren't on the individually wrapped servings but rather on the box they came in. These warnings protect the manufacturer from charges that they made items without the required labeling. | [
"To avoid inquiry and punitive action by the United States Federal Trade Commission, cosmeceuticals which do not intend to be regulated as drugs by the FDA are carefully labeled to avoid making statements which would indicate that the product has drug properties. Any such claims made regarding the product must be s... |
why couldn't martin shkreli call the committee of congressmen imbeciles right at the hearing ? can he invoke his 5th amendment and still them to go take a hike? | Just like contempt of court, you can be fined or jailed for contempt of congress.
You have to respect the proceedings even if you do not respect the people. | [
"BULLET::::- Bannon appears at the House Intelligence Committee under subpoena. According to committee members, he answers only 25 questions that were pre-approved by the White House, answering “no” to each, and invokes presidential executive privilege to decline answering further questions. Republican and Democrat... |
why does a knife need to be moved to be sharp? if you touch a knife it's ok, but if you drag your finger down the edge it hurts. | Knives are still sharp straight-on and can cut that way. However, at a microscopic level, even straight-edged knives have tiny teeth. So when you move the edge against the item to be cut, you are actually running a tiny ultra-sharp saw across it.
[Micro photo of a razor's edge can be seen here.](_URL_0_) | [
"BULLET::::- Blade: The blade is the piece of steel that runs down the center of the knife that is secured by both handles when closed. One edge of the blade is sharp and will cut the user if they are not careful, especially when flipping the knife. The other edge, called the swedge, is blunt and won't cut the user... |
If one of an entangled pair of particles is entangled again, what happens to the entangled values in the system? | Three electrons can be maximally entangled as
uuu + ddd
uuu + ddu + dud + udd
uuu + udd + duu + ddd
These are all [GHZ](_URL_0_) states. They're triply entangled, so there are no 'individual states'. Any single measurement of any electron has a 50/50 chance of being up or down. Some measurements of one of the three will pin down the values of the other two along the same axis, other measurements won't.
If you're starting with (ud - du), which I assume is the state you're talking about, and intent on keeping it, then all you'll get is a product state of the entangled pair and the third electron. | [
"It is also possible to create entanglement between quantum systems that never directly interacted, through the use of entanglement swapping. Two independently-prepared, identical particles may also be entangled if their wave functions merely spatially overlap, at least partially.\n",
"The scheme relies on two pr... |
as alcohol sterilizes stuff, when we drink booze it kills the good bacteria inside us? | Alcohol is absorbed in your small intestines and subsequently processed and broken down enzymatically by your liver long before it reaches your colon. The colon aka large intestines is where your gut bacteria live predominantly | [
"Several species of the benign bacteria in the intestine use fermentation as a form of anaerobic metabolism. This metabolic reaction produces ethanol as a waste product. Thus, human bodies contain some quantity of alcohol endogenously produced by these bacteria. In rare cases, this can be sufficient to cause \"auto... |
Does capillary action take salt water with it? Why or why not? | Yes, the water drawn up by capillary action would take the soluble salt with it, but you are right that the slightly larger mass of the sodium and chloride ions, compared to water, will make them "climb" slower, and therefore less high.
This is the basis of some types of molecular separation mechanisms/experiments, such as [paper chromatography](_URL_0_) or [thin-layer chromotography](_URL_1_). You take a solvent solution with some dissolved molecules you want to separate (called the "mobile phase"), and allow the liquid to climb through a thin layer of some absorbent material (called the "stationary phase") by capillary action. The larger a molecule is, the less it will move up through the stationary phase in a given amount of time. | [
"Normal saline is least irritating to the colon, at the opposite end of the spectrum. Like plain water, it simply functions mechanically to expand the colon, but having a neutral concentration gradient, it neither draws electrolytes from the body, as happens with plain water, nor draws water into the colon, as occu... |
how is it possible for something moving the speed of light to experience no time. | The concept at play here is called Special Relativity; it's one of Einstein's greatest achievements.
The ELI5 is that time slows down for *all* moving objects. You don't notice this on a day to day basis because you're moving *really* slowly; you need to be moving at a nontrivial fraction of the speed of light for the effects to become noticeable.
But, for example, if you were to get in a spaceship and go at .99 times the speed of light and take a 1 lightyear trip that ended up back at Earth, we on Earth would have to wait a year for you to return, but it would only seem like about two months to you on the ship. | [
"According to Albert Einstein's theory of special relativity, \"instantaneous action at a distance\" violates the relativistic upper limit on speed of propagation of information. If one of the interacting objects were to suddenly be displaced from its position, the other object would feel its influence instantaneou... |
Do new scientific discoveries have the same relative significance over time? | It's important that we not mix up science and engineering. There's a lot of cross-pollination, obviously, but they're different things with different goals and means.
Broadly speaking, things can happen in one of two ways. Either we learn something new, then seek (and maybe find, maybe not) ways to apply that knowledge for something other than more knowledge, or we discover that we can do something and then seek ways to explain that something abstractly.
The wheel wasn't a *discovery.* Nobody sat down five thousand years ago and worked out the differential geometry of the circle. It was a pure invention: hey, round things roll. Neat.
Likewise, the Higgs isn't an invention. It has *zero* practical applications. It's pure discovery. Oh look, here's why weak bosons have mass while the electromagnetic boson doesn't. Neat.
Sometimes inventions lead to knowledge, but not always, and not right away. The Minoans had flush toilets three thousand years before anyone wrote down the Hagen-Whasisname equation for laminar fluid flow through a pipe. You don't always need to be able to understand something completely to make use of it in ways that change the world.
Similarly, not all knowledge is applicable. For instance, how would the world be different if we had never discovered that other galaxies exist? It wouldn't. Not in the slightest. Well, okay, maybe in the slightest. Some of our fiction would be different, and theoretical cosmologists would have to find proper jobs, and awkward teenagers the world over would have different posters tacked up in their rooms. But in terms of actual day-to-day life? Zero change. But at the same time, discovering that the universe is filled with galaxies opened up the door to *tremendous* understanding of the universe and how it all works, trickling down to all sorts of things like current work on extending the Standard Model of particle physics.
So how do you quantify "significance?" Will the Higgs change lives? Almost certainly not, at least not in any direct way. Is it important anyway? Absolutely. It's a piece of the puzzle that we're slotting into place, advancing the goal of someday being able to say we have a complete understanding of the laws of physics. That's something. | [
"Commonly cited examples of multiple independent discovery are the 17th-century independent formulation of calculus by Isaac Newton, Gottfried Wilhelm Leibniz and others, described by A. Rupert Hall; the 18th-century discovery of oxygen by Carl Wilhelm Scheele, Joseph Priestley, Antoine Lavoisier and others; and th... |
the metal thing they press on fighters faces between rounds. | Hits to bony areas usually cause large swelling very quickly. There is no fat/muscle to blunt the force.
The piece you see is actually an "eye iron." It is simply a cold piece of metal. That piece is applied and pressed into the swelling to minimize/reduce it.
It literally "pushes" the swelling down.
The cold helps, but the force is what really does the trick.
Yes, it hurts like hell.
Side note: the method of pushing in swelling isn't just for fighters. A doctor once did it for my niece, in the ER, after she fell and hit her head on the corner of a table. We rushed her to the ER because it swelled up to the size of a softball in under 5 minutes. It was intense to watch.
| [
"Fighters are covered in full modern produced protective armor, made from steel (or other metal alloy if permitted) made to aesthetically be as close to their historical counterparts as possible. Hits and blows may be aimed at any parts of the body (with the limitations set in the regulations); both wrestling and p... |
what's the deal with all those scammy looking "we buy houses" signs i see at so many intersections? | They buy houses. Why do you think them scammy? | [
"In the early 1980s, the Freelandville Improvement Club decided to put street signs up in town, as they had not had them before then. Oddly enough, there is no current street sign for Happy Street, as anytime one was put up, it was stolen.\n",
"Apart from the front gate structure, all buildings on International S... |
why do skilled nfl athletes still commit penalties? | For a penalty on the body like a facemask it can just be trying to grab their shoulder and missing. So in that instance it is just a case of things happening too fast. Remember, you may be one of the top linebackers in the sport but you're also playing against the best running backs and receivers in the sport.
For something like holding you can see players trying to get away with it sometimes and it can depend on what the ref is letting them get away with.
For timing penalties (i.e. false start) there are a lot of mind games that happen when both sides line up. Quarter backs will use fake counts to try to get defenders to move early and defenders will fidget to try and get the offensive line to move early. | [
"In addition to suspensions, Goodell has also fined players for on-field misconduct. For example, on October 19, 2010, the NFL handed out fines to Pittsburgh Steelers linebacker James Harrison, Falcons cornerback Dunta Robinson, and New England Patriots safety Brandon Meriweather after they were involved in controv... |
how bulletproof are dinosaurs? | Well, how does a bullet kill a person? It either damages an organ so badly that it can't work anymore, or it hits a big enough blood vessel that the person bleeds out.
So when you look at the I-Rex, it's basically a huge, scaly mass of muscle. Most bullets probably can't get through all of that dense muscle to actually hit a major organ. Its blood vessels are probably large and there are probably lots of them; a bullet hitting some of the smaller, outer ones isn't going to get him to bleed to death. And it's not like a bullet can hit his aorta or anything, because that's in the center of a heavily muscled, bony, scaled body.
So it's sort of like shooting toothpicks at a human. Sure, they'll hurt, and if you get hit with enough of them in the leg, it might be tougher to move your leg. But they aren't going through and causing major damage that could really hurt the I-Rex. | [
"In 2005, the BBC program \"The Truth About Killer Dinosaurs\" used Stan's skull as a model for their hydraulic test of the \"T.rex\"'s bite force and estimated that it exceeded 6.8 tonnes. Additional tests, like those published by Karl T. Bates 2009, used Stan's remains to study the weight distribution of \"T.rex,... |
Is there any evidence that over the counter vitamin D supplements enhance mood? | In the unlikely chance that reduced sun exposure causes a severe Vitamin D deficiency, [you can experience depression](_URL_0_). However, taking supplements to prevent depression isn't quite established. | [
"Vitamin D supplements have been widely marketed for their claimed anticancer properties. Associations have been shown in observational studies between low vitamin D levels and the risk of development of certain cancers. It is unclear, however, if taking additional vitamin D in the diet or as supplements affects th... |
rules about reasonable suspicion vs. probable cause/just cause | Cop here:
Reasonable Suspicion:
An officer reasonably belives a crime *may have* occurred.
For example: An officer is patrolling an area where car break-ins have been a problem. He sees a man in a hoodie (even though it's warm outside) looking into a car window.
He has reasonable suspicion a crime may be occurring. He can legally stop that man and hold him long enough to determine if a crime occurred or not.
Probable Cause:
A higher standard; an officer has reason to belive a crime probably occurred.
Same example as before, but the officer finds several cars with broken windows, the man has broken glass on his jacket, and a wallet from one of the cars.
Reasonable Suspicion is the standard required for a stop or detainment.
Probable cause is the standard for am arrest.
There is no "just cause" in the US legal system. "Beyond a Reasonable Doubt" is the standard needed to *convict* a person of a crime.
As for vehicle searches:
An officer needs probable cause to search a vehicle without your consent. The exception to this is what's called a "Terry Frisk" in which an officer may *frisk* (or pat down- not search) a person or the lungeable (easily-reachable) areas of a car for a weapon if the officer has reason to belive a person may be armed.
The smell of marijuana is probable cause. It seems to be a common belief that cops will fake smelling marijuana in order search a car. I've personally never seen this happen and I would doubt that it happens often at all.
You have the right to refuse a search if the search is consensual only.
*Edit: fixed autocorrect error. | [
"Reasonable suspicion is a legal standard of proof in United States law that is less than probable cause, the legal standard for arrests and warrants, but more than an \"inchoate and unparticularized suspicion or 'hunch; it must be based on \"specific and articulable facts\", \"taken together with rational inferenc... |
what role does a director actually play in creating a movie and what are the signs of a poorly directed movie? | The Director of a film (or a play, or a television show episode) is the person responsible for the creative vision of the piece. They create a concept from the script (which may or may not be something concretely found in the script, it may be metaphorical or tangential) and from the concept lead the design and production team towards a collaborative vision. Once rehearsals/filming have begin, the director blocks the piece (i.e. tells actors where to move), provides objective and subtextual support to the actors (i.e. tells them why they are saying the things the writer wrote) and ensures that the visual style and setting are within the original vision or concept parameters.
In film, they also work closely with the DP, first story-boarding the script, and then, once on set, making sure that each shoot is framed, blocked and shot per their vision. Including ALL design aspects, from the color of the walls to the type of purse a character might wear.
In essence they are the Captain of the ship. A lot of my notes below can also be laid at the feet of bad writing, but in film (less so TV and theatre) directors have a great deal of oversight on the writing, so they are typically held accountable if the writing is terrible.
A film which has been directed badly will usually (but not always, the problem with a collaborative art form, which is what film is, is that there are many, many chefs in the kitchen. However, since the director tends to get the credit when everything works, they also tend to get the blame when it doesn't)--usually show the following flaws:
1. Incoherent story telling. You don't know what is happening. Or why it is happening. Or who it is happening to. Sometimes things are just blatantly implausible.
2. Cliche or trope ridden dialogue/shots/events. You feel like you've seen all of these things before. All the characters are stereotypes, all the plot points unfailingly predictable. Note: cliches, tropes and stereotypes can all be used well. But bad directors tend not to.
3. Bad dialogue. Dialogue that is forced and unnatural. Dialogue that is too on-the-nose. People telling other people things instead of doing things. People explaining how they feel ad nauseam. Dialogue spoken only to allow for the plot to push forward, leading us to:
4. Coincidental plotting, or plots hole you could drive a freight train through (not the small inconsistencies that almost every movie has, but HUGE giant massive oh-my-god-this-movie-is-broken plot holes). Coincidental plotting is when everything that has to happen for the plot to move forward does, without any effort on the part of the hero (or the bad guy).
5. Bad acting. Directors are responsible for getting a performance out of their actors, so even if the actor can't act (one reason why casting is important) the director is still the one people are going to hold responsible for any painful moments on screen (this is less true in TV and theatre).
6. Over or under designed. Over designed is when the concept/vision of the piece becomes more important then any other element. Think 300: Rise of an Empire or Sin City: A Dame to Kill For (not-at-all-oddly, both Frank Miller graphic novel adaptations, where the look was where the design team started with). Tim Burton is also a well-known director who can go to far with his vision/design to the point of over balancing the movie. Under designing is when there is a lack of design and the production feels (usually) cheap or not-thought-through. Good design elevates the narrative, supports the characters and provides visual clues to the audience about what is happening--excellent design can comment on and complement the action, enhancing the entire experience.
7. Movies/TV only: bad editing. Either because there were technical difficulties during filming and the needed shots weren't gotten (or a director wasn't prepared and didn't get the shots they needed), and therefore the editor is attempting to make up for missing and/or bad shots; or because the editing itself is just bad. Odd cuts, odd shots going back to back, odd audio issues. Various other things. While most early directors at a studio on a movie won't have any say over the final cut, most editing issues are from a lack of footage (which is the director's issue), not bad editing. OR a director who does have final cut approval and shouldn't, which is where you got a three-hour movie that should have been 2 hours and 10 minutes max.
8. Poor production value. An overall feel that the movie wasn't cared for (this isn't about money, this is about time and support). Usually shows in bad lighting, bad audio, bad set dressing, bad costumes--just an overall sense that these things weren't considered important or there wasn't time to pay attention to them.
A film, tv show or theatrical play is an immense, multi-part beast, and the Director is the one that tries to tame it. To varying degrees of success. Every director probably has one (or many) bad movies to their name, as its how we all learn. The more telling test is not if they directed a bad movie, but if people wanted to work with them again. And, sometimes, the love of the thing they are creating can shine through the worst movie and make it, somehow, good (think Sam Raimi's original Evil Dead).
Hope that helped! | [
"The out-of-work director has a shady past. A witness to his shady past is an aspiring actor, who was subsequently thrown out of the acting circuit. This actor started a catering service for the film unit.\n",
"Since the film director depends on the successful cooperation of many different creative individuals wi... |
What sources are there to suggest that Nero blamed the fire in Rome in 64 CE on Christians? Do we know how he became aware of the movement? Would these suggestions be the earliest independent recognition of Christians as a distinct group in the historical record? | The only source that mentions Nero's blaming of the Christians is Tacitus ([Annals 15.44](_URL_2_)):
> Therefore, to scotch the rumour, Nero substituted as culprits, and punished with the utmost refinements of cruelty, a class of men, loathed for their vices, whom the crowd styled Christians. Christus, the founder of the name, had undergone the death penalty in the reign of Tiberius, by sentence of the procurator Pontius Pilatus, and the pernicious superstition was checked for a moment, only to break out once more, not merely in Judaea, the home of the disease, but in the capital itself, where all things horrible or shameful in the world collect and find a vogue. First, then, the confessed members of the sect were arrested; next, on their disclosures, vast numbers were convicted, not so much on the count of arson as for hatred of the human race. And derision accompanied their end: they were covered with wild beasts' skins and torn to death by dogs; or they were fastened on crosses, and, when daylight failed were burned to serve as lamps by night. Nero had offered his Gardens for the spectacle, and gave an exhibition in his Circus, mixing with the crowd in the habit of a charioteer, or mounted on his car. Hence, in spite of a guilt which had earned the most exemplary punishment, there arose a sentiment of pity, due to the impression that they were being sacrificed not for the welfare of the state but to the ferocity of a single man.
The passage has caused a great deal of scholarly discussion over the years, including some doubts over its authenticity. However, the general consensus is that this is a genuine bit of Tacitus, and yes, that makes this pretty much the earliest mention of Christians as a distinct group by a non-Christian author. Suetonius and Pliny the Younger also mention the Christians, and both were writing in the early 2nd century, so the same time as Tacitus. In both of these writers, the Christians are also coming in for rough treatment by the Roman authorities - in [Suetonius](_URL_3_) it's Nero again (and maybe [Claudius](_URL_1_) a decade earlier), and in Pliny it's actually [himself](_URL_0_). He was the governor of the province of Bithynia, and oversaw the trials of some Christians. His letter describing his actions to the Emperor Trajan is a fascinating window into the interactions between the Roman state and the new religious group, which is less than a century old at this point, and probably only numbers a few thousand adherents across the whole empire. The crucial difference between the writers here is that Tacitus and Suetonius are describing events around 50 years before their time, whereas Pliny is talking about his own experience. How much does the contemporary situation colour the accounts of Tacitus and Suetonius, in terms of their awareness of Christianity as a distinct group? There's also genre and authorial intent to consider here, especially with Tacitus. It's always important to remember that throughout his *Annals,* Tacitus is intentionally presenting a gloomy, degenerate picture of Rome, fallen from its glorious past. His portrayal of Neronian Rome is a centrepiece to this, and we can't take the tiny passage about the Christians out of this context. Tacitus lumps Christianity in with the other horrible and shameful things that have collected in Rome under the emperors, but makes it pale in comparison with the cruel debauchery of Nero, who allegedly burned the Eternal City to satisfy his own desires and then tortured innocent people to cover his tracks.
As to how Nero became aware of Christianity, we can only speculate. Tacitus implies they were notorious in the city, and the evidence from the New Testament suggests a fairly strong community. Paul wrote his letter to the Christians in the city before he visited, and preached there for two years while awaiting trial. Perhaps someone in the imperial household (or even Nero himself) picked up gossip or rumour of these new beliefs, or maybe heard someone preaching on the streets. Pliny's letter suggests that perhaps the emperors might have also been getting news about the religion from other provinces, especially when Christians were caught up in (or the cause of) civil unrest. | [
"The exact cause of the fire remains uncertain, but much of the population of Rome suspected that Emperor Nero had started the fire himself. To divert attention from himself, Nero accused the Christians of starting the fire and persecuted them, making this the first documented confrontation between Christians and t... |
why do so many great mma fighters have multiple losses on their record compared to boxers? | A couple of reasons:
1) MMA is more physically tolling on the body. Even in training, you get hit, get slammed and get submissions put on you. More parts of the body are involved so there are more places to get injured. You are pretty much safe below the belt in boxing and don't have to worry about falling unless you get knocked out. You have to worry about both of these things in MMA.
2) It depends on who you consider "a great" and when you consider them one. Anderson Silva didn't lose between 2007-2012. Fedor didn't truly lose from 2000-2009. GSP only lost twice from 2002-2013. Fedor's now lost multiple times, but it doesn't make his original run any less.
3) With UFC being the only real show in town right now and MMA matchups being booked by a company, and not individual promoters, it's hard to duck and dodge the best competition like boxers do. Boxers don't really have to face anyone they don't want as it's more on individual drawing power, while UFC is a full company. UFC will be around if say Rhonda Rousey leaves. Random boxing promoter may not be if his man leaves.
4) UFC and MMA have a lot less weight classes than boxing. There are 17 boxing weight classes right now. UFC has 8. That means the better talent is less spread out and you have a lesser chance of getting by on favorable matchups than skill. | [
"During career mode, all of the attributes are increased by allotted training bonuses. As the boxer progresses from match to match, his statistics start to fade. After 35 fights, his hair turns from normal to grey. Finally after 40 fights, the player is forced to retire even if he or she has never beaten the champi... |
How come soldiers in Mesoamerica and Japan didn't make widespread use of larger shields like in Eurasia? | Define large.
In Mesoamerica, different shield designs were used at various points in time. Ross Hassig talks about changes in Mesoamerican shield design in his book *War and Society in Ancient Mesoamerica*.
The Central Mexican city of Teotihuacan, which fell some 500 years before the Aztec empire arose, appears to have used rectangular shields. The most famous depiction of these can be found on the Teotihuacano soldiers depicted in [Tikal Stela 31](_URL_1_). Given the way this shield is carried, it appears to have been made out of a flexible material and was likely more useful for deflecting glancing blows from projectiles rather than for melee combat. Because the material was likely flexible, it wouldn't have been practical to make them very large. Maya warriors during the Classic period were rarely depicted with shields. Those depictions that do exist typically show small rounded bucklers that are even smaller than these. A comparison of these two types of shields can be seen [in this image](_URL_0_). (With a caveat, the labels in that image are inaccurate, the different shield types correspond to regional differences not class distinctions). In contrast to the rectangular shields, the rounded shields appear to be rigid (likely made of wood), and were likely designed to deflect blows from clubs.
The rounded shield that you see in [most depictions of Aztec soldiers](_URL_2_) was largely prominent during the Postclassic period (c. 900 AD to conquest). This shield design appears to gain prominence in Mesoamerican armies about the same time as the macuahuitl, a sword-like weapon made of wood and obsidian. The rigid portion of this shield was as large, if not larger, than the metal shields carried by the conquistadors. However, as you can see in the image, it also had a feather fringe on the outside that, like the flexible shields used by Classic Period Central Mexican soldiers, was likely designed to deflect glancing blows from projectiles. If the fringe is considered part of the shield, they were actually quite large.
What you're probably asking though is why they didn't develop the large tower shields like the kinds you frequently see in movies depicting Roman legions. I can only speculate, but it's likely that those kinds of shields were designed for a different kind of combat. As Hassig explains (and as I've tried to explain above), Mesoamerican shields were typically designed to either deflect indirect hits from projectiles and/or for hand-to-hand combat between individual combatants. Tight formations of spearmen (like a *phalanx*) were not frequently employed in most Mesoamerican armies (with the possible exception of some Central Mexican armies during the Classic Period). If the old adage that "form follows function" holds true, it could be that such a design simply wasn't necessary given the tactics used by Mesoamerican armies. It's also possible that such a shield design would not be as effective with materials other than iron, which the Mesoamericans did not have. | [
"During the 19th century, non-industrial cultures with little access to guns were still using war shields. Zulu warriors carried large lightweight shields called Ishlangu made from a single ox hide supported by a wooden spine. This was used in combination with a short spear (assegai) and/or club.\n",
"In Italy, t... |
why, as an adult, i take the same amount of cough syrup or other medicines as a 12 year old when i am heavier and more physically mature? | The dosage is just what they know is safe but still effective generally. If you feel like the recommended dosage is insufficient you can go above. Of course if something goes wrong you can't sue the company because you went against recommendations, and you didn't hear it from me that it should be safe, but for the very reason of lawsuits the recommended dosage is already a bit conservative. | [
"No good evidence exists for or against the effectiveness of over-the-counter cough medications for reducing coughing in adults or children. Children under 2 years old should not be given any type of cough or cold medicine due to the potential for life-threatening side effects. In addition, according to the America... |
Did WW2 had any cultural impact on arts or music in Europe? | Huge, post modernism was in part a reaction to the world wars and the changes they brought.
In Europe the grief was palpable, imagine if 20% of your population died. It made many artists think that any attempt at meaning or beauty was hopeless and futile in the face of such horror.
It was really shattering to many Europeans that their great and respectable culture, where people where supposed to be civilized and intellectual had produced such immense hatred, death and destruction.
I think Theodor Adorno summed up the feeling best,
> To write poetry after Auschwitz is barbaric. | [
"These works are a few of the examples of some of the musical thought taking place at the turn of the century. However, many European thinkers found fewer resources and more censorship with the incoming Second World War. In response, Charles Seeger helped found the American Society for Comparative Musicology to hou... |
When and why did golf become the default "upper-class hangout/dealmaking" activity? What filled that role before? | In ancient Persia, there was quite an exciting sport that we've been able to reconstruct from artistic depictions, and also the preserved fragments from the ancient Persian *On the art of entertaining officials*, an important handbook for satraps and other royal officials. Whenever a group of royal officials were seriously bored, they would first locate a cliff, or a mountain. They would also bring with them a large herd of camels, and then send down observers to the bottom of the mountain (this being pretty important for what followed). Each noble would then choose a camel. The camel would be strapped into a harness, and then attached to a large brightly coloured canvas. And when I say large, I mean several metres wingspan. Then the camels would, one by one, be forced to run off the edge of the mountain or cliff. They would quite literally hang-glide from there to the bottom, and the competition was won by noble whose camel travelled the greatest distance. Camel harnesses breaking was a big problem, which is why there were so many brought up the hill. It seems to have been a pretty obscure sport in the rest of Persia, all told, but nobles seem to have loved sending camels hang-gliding off cliffs.
A reconstruction of the hang-gliders for camels can be found in Samuel P Langley's papers, currently stored in the Smithsonian Institution Archives; the man simply insisted on attempting to recreate one. A more recent and direct look at the subject can be found in Louis Nockton-Draffer's *The Persian Funeral Glider: Reconstruction and experiential perspectives*, presented at the 7th Experimental Archeology Conference in Cardiff
[WARNING THIS IS TOTALLY A JOKE NONE OF THIS IS REAL. READ MOD NOTE HERE](_URL_0_) | [
"Golf became widely popular during the economic bubble, when golf club passes became useful tools for currying favor with corporate executives. Many mid-level salarymen were pressured into taking up golf to participate in golfing events with their superiors. The collapse of the economic bubble led to the closing of... |
When Canada changed its flag, what did they do with all the old ones? | There's never been any legislation covering flag disposal in Canada. The rules of Flag Etiquette are laid out in a [publication by the Department of Canadian Heritage](_URL_0_) and the rule for disposal is pretty vague. It just says that old flags "should be destroyed in a dignified way." But of course that's just the rule as it stands today. The [Flags of the World website](_URL_1_) suggests that this regulation didn't exist until the 1970s or 1980s, well after the 1965 switchover. In the Navy, for example, old ensigns were often turned into polishing rags. Not quite the respectful disposal one might expect.
On top of there being no general rule for flag disposal at the time, there were no specific instructions for the flags that got lowered in 15 Feb 1965 (at least none that were made public that I'm aware of). Given all that, I don't think we can really say what happened to all the old Red Ensigns. I do know that the last Red Ensign flown over Parliament is currently in the collection of the Canadain Musuem of History though. You can see a picture of it if you [scroll down this page here](_URL_2_).
| [
"Shortly after Canadian Confederation in 1867, the need for distinctive Canadian flags emerged. The first Canadian flag was that then used as the flag of the Governor General of Canada, a Union Flag with a shield in the centre bearing the quartered arms of Ontario, Quebec, Nova Scotia, and New Brunswick surrounded ... |
if gravity is actually the earth accelerating upwards and the earth is spherical, how can it accelerate upwards in all its surface? | Did you get the bit where it mentioned frames of reference? Because that's what this is all about.
Now, ignore the planet. Ignore all the big stuff around here. Ignore me, ignore you. We're going to talk about two tennis balls in deep space. They're just there, in space - they're not sitting on a table, they're not sitting on the ground. They're just there.
Now, they're getting closer to each other. So, is it correct to say that:
1. Ball A is moving towards B?
1. Ball B is moving towards A?
1. Both balls are moving towards each other?
Well, it could be any of them. It depends on what you define as your frame of reference.
If you **decide** that B is stationary, then case 1 applies. If you decide that A is stationary, case 2 applies. If you decide that an invisible point in the middle of the two is stationary, 3 applies.
The thing is, we tend to think of the Earth as the be-all and end-all. It's big, it's kinda constant for most of us - it just sits there under our feet, not seeming to move.
But... what about the tennis ball example? We can decide which thing moves. If I hold a tennis ball above the Earth and let go, the same thing applies. I can **decide** whether the ball moves, the Earth moves, or both. | [
"Gravity acceleration is a vector quantity. In a spherically symmetric Earth, gravity would point directly towards the sphere's centre. As the Earth is slightly flatter, there are consequently slight deviations in the direction of gravity.\n",
"The Earth is massive enough that the pull of gravity created and main... |
what the hell did people think sports concussions were before? | Well the expression for a concussion was usually something like "he got his bell rung" to explain the immediate symptoms of concussion. CTE is different that a concussion though. It is caused by many concussions over time, slowly building, as we understand it now, but is often seen later in life.
So a normal guy racks up a few concussions and recovers. Then 20 years later he has real mental health problems. There was no way for them to link it to the bell ringings he got in high school football.
Basically they didnt realize these impacts and symptoms which would subside fairly quickly were having permenant impact on the brain. | [
"In the 2010s, there has been much controversy about football and brain health, with a number of studies focusing not just on the occasional concussion, but also on the large number of sub-concussive hits. One game in particular in 2012 resulted in five concussions. In 2015, a family sued Pop Warner over the suicid... |
the brain is very important, and very complex and exists in a confined space; given that why is it that tumors in the brain are able to get so large before being noticed? | The common symptoms of brain tumors are just that, common. Headaches, nausea, dizziness, and so on can be caused by a lot of other things and the symptoms themselves can come and go. It's usually once more serious symptoms appear or a pattern of symptoms is recognized that a patient undergo MRI. | [
"The signs and symptoms of brain tumors are broad. People may experience symptoms regardless of whether the tumor is benign (not cancerous) or cancerous. Primary and secondary brain tumors present with similar symptoms, depending on the location, size, and rate of growth of the tumor. For example, larger tumors in ... |
Can anyone tell me about a specific American flag? | hi! it might be worth x-posting this question to the flag aficionados in /r/Vexillology | [
"The flag of the United States of America, often referred to as the American flag or U.S. flag, is the national flag of the United States. It consists of thirteen equal horizontal stripes of red (top and bottom) alternating with white, with a blue rectangle in the canton (referred to specifically as the \"union\") ... |
openoffice vs. libreoffice (vs. microsoft office) | I haven't used OpenOffice since the split, nor MS Office since before then, so I can't comment on the differences between them today. But I can give a little background on the split itself.
OpenOffice used to be run by Sun. [In 2009 Oracle bought Sun](_URL_0_) and maintenance of OpenOffice became less of a priority - basically Oracle put it on the back burner. LibreOffice was created by the community in response to that, and a number of old OpenOffice contributors now work on LibreOffice instead, and many of the financial backers of the project also followed.
Oracle later donated OpenOffice to Apache, so now both software suites exist, and the short version is that LibreOffice is the spiritual successor to OpenOffice, and the new OpenOffice is essentially a completely new entity. | [
"LibreOffice is available for a variety of computing platforms, including Microsoft Windows, macOS, and Linux (including a LibreOffice Viewer for Android), as well as in the form of an online office suite LibreOffice Online. It is the default office suite of most popular Linux distributions. It is the most actively... |
- when you dent your car and the auto body shop uses filler to fill the dent, what are they using? | Polyester resin/putty, sometimes mixed with fiberglass for extra strength. Bondo is a fairly common brand, and other brands are often referred to as "bondo" as a result. | [
"BULLET::::- Body filler: Body filler (or Bondo) is a two-part putty often used to fix dents in automobiles. Case modders use it to fill and sculpt their own creations. When mixed with a paste catalyst the filler hardens in a short period of time and can be sanded, ground or cut to a desired shape. An alternative s... |
is it pitch black in space or is there enough ambient light to see something held in front of you? | Light would be very dim.You would probably be able to make out objects at close range, but not read or see fine details.
[Here's a good r/askscience post on the subject](_URL_0_) | [
"Olafur has been developing various experiments with atmospheric density in exhibition spaces. In \"Room For One Colour\" (1998), a corridor lit by yellow monofrequency tubes, the participants find themselves in a room filled with light that affects the perception of all other colours. Another installation, \"360 d... |
how do cinema projectors have such high quality compared to personal home projectors? | They got a light source (think: a bulb) that is consuming so much energy it's crazy compared to the tiny box you got in your own living room.
And bulbs always create excess heat that needs to be cooled away with active cooling. i.e, fans. Fans are noisy.
But no-one in the cinema cares, because that projector is in it's own room, with a glass window. No-one in the audience hears the fan. | [
"Although usually more expensive than film projectors, high-resolution digital projectors offer many advantages over traditional film units. For example, digital projectors contain no moving parts except fans, can be operated remotely, are relatively compact and have no film to break, scratch or change reels of. Th... |
why do chiggers and/or mosquitos seem to bite around a person's joints (e.g. ankle) | In short, evolution or The Fall, depending on your religious flavor or lack thereof.
The most prominent reason is the fact that the blood vessels are very close to the surface of the skin over these areas. Mosquitos have the capacity to sense heat as well as (some speculate) the capacity to sense the blood pumping through blood vessels. | [
"Chiggers seem to affect warm covered areas of the body more than drier areas. Thus, the bites are often clustered behind the knees, or beneath tight undergarments such as socks, underwear, or brassieres. Areas higher in the body (chest, back, waist-band, and under-arms) are affected more easily in small children t... |
How exactly was Jefferson Davis elected President of the Confederacy? | While a perfectly fine question, more of our Civil War experts are sticking around in [this AMA thread today, so I would suggest you repost it here!](_URL_0_) | [
"Jefferson Davis was named provisional president on February 9, 1861, and assumed similar commander-in-chief responsibilities as would Lincoln; on November 6, 1861 Davis was elected President of the Confederate States of America under the Confederate Constitution. Alexander H. Stephens was appointed as Vice Preside... |
What factors contribute to resting metabolic rate? | First question; not my area
Second question, relating to the first:
[Not much](_URL_0_)
> One study noted that one standard deviation of variance for resting metabolic rate (how many calories are burnt by living) was 5-8%; meaning 1 standard deviation of the population (68%) was within 6-8% of the average metabolic rate. Extending this, 2 standard deviations of the population (96%) was within 10-16% of the population average.
sources within top link
It's perhaps better to use Metabolic equivalent, using it to compare the instant valuation with the type of physical activity being done given that RMR within a given population doesn't vary greatly. | [
"T increases the basal metabolic rate and, thus, increases the body's oxygen and energy consumption. The basal metabolic rate is the minimal caloric requirement needed to sustain life in a resting individual. T acts on the majority of tissues within the body, with a few exceptions including the spleen. It increases... |
how is facebook exploiting me? | Basically anything you submit to Facebook becomes their property; Pictures, personal information, everything.
People complain about privacy and then go and spill every single detail of their life to Facebook, thus Facebook is "exploiting" idiots. | [
"Recently, Facebook, knowingly agreed and facilitated a controversial experiment; the experiment blatantly bypassed user privacy and demonstrates the dangers and complex ethical nature of the current networking management system. The \"one week study in January of 2012\" where over 600,000 users were randomly selec... |
where does the sound from the car's blinker actually come from? | It's a relay with a reed switch. Makes noise when activated. They're usually under the dash on the driver's side.
| [
"The result was an engine which idled at 150 rpm and ran with uncanny silence \"the only audible sound made by a Double-Six (if you opened the bonnet and went right up to it) was the almost imperceptible tick as the ignition points opened and the faint breathing of the carburettor\".\n",
"While the car is idling,... |
Why are there distinct lines between the states of matter, instead of just a gradual scale of change? | So, addressing a few misconceptions:
It really isn't a terribly meaningful statement to describe a single molecule as having a temperature. That said, I assume your idea here is that the entire material is in the same "condition" (pressure, temperature, etc).
Next, while it is still "just water", it is incorrect to suggest that water at 1C is identical in behavior and structure to water at 50C or 99C. If we consider only "gelatinous-ness", which might be more rigorously quantified by density and viscosity, you can see [here](_URL_1_), that there is appreciable variation throughout the temperature range where liquid water is stable.
That said, you are correct that many materials appear to exhibit a transition temperature across which there is an almost black-and-white difference in behavior and structure: the melting temperature. However, there are many materials that do not exhibit this, or at least not in a terribly accessible or meaningful way.
Many amorphous materials are characterized by what is called a glass transition temperature (which despite its name, is quite different from a melting temperature). Specifically, the glass transition temperature is not a well-defined temperature in many cases, but rather a range over which the transition from a more rigid material (like window glass) to a more viscous material (like melted plastic) occurs. Also, as you may know, the melting temperature of a material is characteristic of that material and for the most part will not change depending on the sample or cooling rate. The glass transition however is very sensitive to many factors including thermal history and cooling rate.
The glass transition is seen in many everyday materials, including most plastics and glasses (although the temperature range is so high for most glass that you wouldn't ever notice it unless you happened to have access to a high temperature furnace). In fact, the whole glass transition issue makes even categorizing glass as a solid or a liquid a very complex matter. The topic also [came up](_URL_0_) in the last "misconception" thread, courtesy of the resident expert on glass physics, EagleFalconn.
Edit: even this is a simplification but the general idea is that it turns out that whole idea of "solid, liquid, or gas" is far from comprehensive and often becomes less and less meaningful the more, and deeper, questions you ask. | [
"Classically, states of matter are distinguished by changes in the properties of matter related to external factors such as pressure and temperature. States are usually distinguished by a discontinuity in one of those properties: for example, raising the temperature of ice produces a clear discontinuity at 0 °C as ... |
How and when were all the clocks (time) around the world synced? | As the UK became a maritime nation, boats kept one [chronometer](_URL_0_) on-board so they knew how far away they were from the Greenwich meridian (which is considered to have longitude zero degrees). The chronometer wasn't treated as the actual time, because that was calculated by solar time, depending on where they were. But this, boats travelling back and forth around the world from Britain, meant that people used GMT worldwide as a reference time no matter where they were (there were other reasons, including [this](_URL_3_), but I'm trying to keep it simple). Most time zones were either an hour or a half-hour ahead or behind of GMT.
Basically, trains were responsible for the adoption of GMT as full British time. Railway companies had to adopt a singular time in order to work in unison, otherwise making things very difficult. It didn't happen quickly and there were court battles regarding the case, but eventually they did decide that it was best for the local mean time to be considered as full British time.
As for other countries, it was never truly set out. There are a bunch of countries (Ireland, Canada, Australia) that have time set out in legislation, but most know it simply by convention. The time simply exists, not set out.
There were a lot of changes from the deciding of GMT - it was redefined later as [Coordinated Universal Time](_URL_1_), which was maintained by atomic clocks because they were pretty reliable. It was changed again as UT0 and UT1 and UT2 later to make up for small discrepancies such as seasonal variations, earth's rotation, leap seconds and the like.
It's unfortunately not a particularly interesting topic. The adoption of time was very, very slow, but came about largely as a result of boats and trains needing ways to keep things going smoothly, or "like clockwork". In fact, it's taken so long to do that it wasn't until the advent of the internet and GPS and things that clocks all around the world could be properly synchronised (and even then, some people still take issue).
Wikipedia has a really good summation of the subject, to be honest. You can read it [here](_URL_2_), but I think what I explained is pretty much the same, and maybe easier to understand.
Edit: adding some extra resources in as links | [
"The 24-hour time system has its origins in the Egyptian astronomical system of decans, and has been used for centuries by scientists, astronomers, navigators, and horologists. In East Asia, time notation was 24-hour before westernization in modern times. Western-made clocks were changed into 12 dual-hours style wh... |
Can anyone name an example of a country that fared poorly as a result of having a really open immigration policy? | Our [subreddit rules](_URL_0_) don't allow "throughout history" questions, so I'm afraid I've had to remove your post. We've found that questions like this end up attracting low effort trivia rather than the in-depth responses people like to see here. If you're interested, I'd encourage you to post a question about immigration policy in a specific time and place. | [
"Immigration may be the outcome of problems in the migrants' countries of origin. Open immigration policies and efforts do not address these problems. However, just keeping borders closed does not address them either.\n",
"BULLET::::- \"Migration policy: from control to governance : In the United States and Europ... |
paralysis, specifically if you are paralyzed below the waist, is your genitalia also paralyzed? can a man never have an erection for the rest of his life? | It depends.
Some people are (effectively) paralyzed because of a muscle issue. So, the nerve connection between brain and muscle is still there, but the muscles can't contract when the signal reaches them, or they're too weak to truly move. So, if it's just an issue of "the muscles in the leg no longer function properly," the genitalia will still mostly function. This would be the case for someone who's effectively paralyzed because of muscular dystrophy, for example.
Someone with muscle issues may have problems with ferility, though, especially childbirth. A mother whose muscles are too weak to force a child out would have to have surgery to give birth, for example. Men also may have issues ejaculating, because the muscles that actually force the semen out can be too weak. Incontinence can also be an issue.
With nerve issues, it's more complicated. There are injuries or diseases which affect the brain's ability to actually send signals to the muscles. If the nerves that go down your leg through the hip are cut off or damaged, the genitalia aren't affected. If there's a spinal problem where the cutoff is towards the base of the spine or whatever, that can affect genital functioning. No nerve impulse, no genital functioning. Not only can you not feel anything when the nerves are cut off, but the "automatic" reflexes that occur without you doing anything conscious (like your leg kicking when the doctor taps your knee) also fail, since they're also routed through the central nervous system. | [
"The onset of paralysis (spastic paraparesis) is sudden and symmetrical and affects the legs more than the arms. The resulting disability is permanent but does not progress. Typically, a patient is standing and walking on the balls of the feet with rigid legs and often with ankle clonus.\n",
"Paralysis can occur ... |
theresa may's announcement of the snap election | May's Blue party think they're currently doing a lot better than Jeremy's Red party. Because the Blue party are in charge of the tree house just now, they've decided to hold the next election earlier than they need to, which is called a 'snap' election.
All the members of the tree house get to vote in whether or not the snap election will take place, but if Jeremy and his friends say no then everyone will think they're scared to stand up to May. Everyone who's not a Red or a Blue thinks that they can maybe steal a few of the better chairs in the tree house from the Reds during the confusion. | [
"On 18 April 2017, Prime Minister Theresa May announced she would seek an unexpected snap election on Thursday 8 June 2017. Corbyn said he welcomed May's proposal and said his party would support the government's move in the parliamentary vote announced for 19 April. The necessary super-majority of two-thirds was a... |
How serious was the Madagascar plan? | Transcript from the Eichmann trial.
The plan took its final shape during the War. Eichmann admitted that it had been devised and passed on by his Section after consultations and discussions with other authorities. Under this plan all the local inhabitants of Madagascar, about four million persons were to be uprooted, to be removed and deported from there, and in their stead the Jews were to be settled on that island, the main advantage of which was, according to what was specifically stated, that its occupants would be prohibited from coming into any contact - even business contacts - with other nations. There they would be living under the control of the Gestapo and would never achieve any independence. They planned to dump a million Jews there each year. Whoever studies this atrocious plan which originated with him, will come to the conclusion that its principal objective was to take control of the Jews, to throw them out of Europe, and to transport them to a country of exile, a country in which they would be isolated from the world. Whether the Jews succeeded in surviving there, or not - that did not matter, that Eichmann did not take into consideration.
He was questioned about the plan. The Court will find his replies on the subject. From the point of view of its cruelty and lack of consideration for human life, its being pervaded with hatred of Jews, its being drawn up in total disregard for the inhabitants of the island of Madagascar themselves and for the Jews destined to be deported there - it was not much better than a plan for actual extermination. Whoever was capable of preparing such a plan, recommending it and striving for its implementation - would not find it too difficult to move to the next stage of the criminal plot. But it was impertinent and insolent to mention this plot in the same breath as Herzl and the Zionist movement.
Possibly Eichmann was incensed that his schemes were not adopted. Possibly he expected that his name would be linked, as it had been linked at the ministerial meeting of 12 November 1938, with the practical solution of getting rid of the Jews - the aim which a veteran National Socialist should obviously have aspired to achieve. Possibly he toyed with the idea that if his programme were to be implemented, he - and not Heydrich - would be the Supreme Commissioner for Jewish Affairs.
At any rate,instead of Madagascar, there came the extermination plan. Eichmann admits that he knew about it already from its early stages, in the summer of 1941, and that he had an active role in its realization. As I have said, he tried to persuade the Court with all his might, that it was only through lack of an alternative and because he could not free himself, that he had to become engaged in this activity. Although, as I have said, it makes no difference, as regards his being found guilty, whether a murderer acts out of an eager lust for blood or out of "pessimism," as Eichmann portrayed his mental condition regarding the Final Solution. But for the purpose of assessing the man, of considering his testimony and evaluating the personality which he tried to present for himself, for understanding the group of his collaborators and their assistants who carried out the numerous works, there is some importance also in this enquiry. The truth came out as it emerged from a particular passage from his conversation with Sassen, about which he was questioned twice. | [
"BULLET::::- Madagascar Plan – a scheme devised by the Nazis in 1940 to globally alleviate the perceived Jewish problem by shipping them en-masse to the French colony known as the island of Madagascar. Instead of sending the Jews to Palestine, which the Nazis believed belonged to the Christians and Muslims, the ide... |
how military units get their numbers? like where does 25th id come from? wheres 24th id? | It's largely random. In WWII we had the first, second, and third armies, but then you get reasons like:
-SEAL Team 6: Actually the second SEAL Team, but we wanted the Russians to think we had more.
-112th Airborne: Made up of 2 different units, something like the 50th and 62nd, couldn't decide whose number to take when they got combined, so they just added them.
Other units were just split up and given "the next number" that wasn't being used and then became autonomous by circumstance, so they were reinforced and became their own unit. Really there's no single rhyme or reason to it.
Charlie 3-07 sounds more like a callsign. Like the 7th crewman in the 3rd vehicle of Charlie platoon. | [
"Wartime service numbers of the Regular Army and the Army of the United States began at 10 000 000 and extended to 19 999 999. A subset of this series was reserved solely for those who had enlisted from recruiting stations outside of the 48 contiguous states of the United States. The first number after the \"ten\" ... |
why should one's beliefs impede another's rights, especially if the other doesn't subscribe to their belief system? | Christians believe being around gay people or being forced to serve them food in their restaurant is the same as "being forced to accept homosexuality". In Christianity, homosexuality is a sin punishable by death, no different from murder.
Also, they believe gay marriage or gay rights are special rights. They believe it is equal because no one should have the right to marry someone of their same sex. | [
"While direct discrimination on grounds of religion or belief is automatically unlawful, the nature of religions or beliefs leads to the conclusion that objective justification for disparate impact is easier. Beliefs often lead adherents to the need to manifest their closely held views, in a way which may conflict ... |
plato's theory of forms and aristotle's criticism to it | Little Kid: "Dad, what's a dog?"
Dad: "Well, we have Buster at home. Buster is a dog."
Little Kid: "Yeah, but what *makes* Buster a dog?"
Dad: "Well, he walks on four legs and is covered in fur."
Little Kid: "Yeah, but so does our cat Oscar."
Dad: "Yeah... well, Buster barks."
Little Kid: "But bears walk on four legs, are covered in fur, and kind of bark. Are bears a type of dog?"
Dad: "No dingbat, bears aren't a type of dog. When I tell you to think of a dog you don't think of a bear do you?"
Little Kid: "No . . . but what if you shave Buster? Is he still a dog with no fur? Cause that's not what I think of when I think of a dog."
Dad: "No, he's still a dog. He's just . . . different. Dogs just sort of have that dog-like quality to them. I guess dogs are just something where you know it when you see it."
This sort of illustrates Plato's Theory of Forms and Aristotle's critique. Plato was basically saying that when you're trying to define something, you ultimately will need to invoke a kind of knowing that isn't a matter of grasping a definition of one term by means of another terms, but of grasping the thing itself. In other words, the concept of a "dog" is an abstract universal entity that exists independent of dogs themselves.
Aristotle said yeah, but there must be some knowledge of the substance which is *in* the thing. There must be something *in* Buster, some type of dog-like quality, which makes Buster a dog. | [
"Aristotle argued at length against many aspects of Plato's forms, creating his own doctrine of hylomorphism wherein form and matter coexist. Ultimately however, Aristotle's aim was to perfect a theory of forms, rather than to reject it. Although Aristotle strongly rejected the independent existence Plato attribute... |
why are videogame consoles and other electronics arranged in rectangular prisms rather than cubes? | They're based around circuit boards which tend to be flat and not square. Making a cube would either result in a *giant* cube, forcing you to make your circuit board really tiny or splitting the electronics into multiple square boards & adding some sort of interconnect between them, none of which are ideal solutions.
For one example, [here's the inside of an XBox 360](_URL_0_). | [
"In three-dimensional variants, the playing field is a cube (containing smaller cubes) instead of a rectangle, and the player has the ability to rotate the cube. \"Cubes\" for iPhone OS uses this approach.\n",
"In the fields of computer and video games and pixel art, the technique has become popular because of th... |
Serious: Is the increase in detection and diagnosis of all Cancers in any way related to the increased levels of radioactive materials in circulation globally? | In short: no. Only a [small fraction of cancers](_URL_0_) is attributable to radiation.
There are several reasons that cancer is more prevalent (or appears more prevalent) in recent years.
1) Age is the #1 risk factor for cancer. In other words, the older you are, the more likely you are to develop it. This means that as the rest of medicine gets better, and lifespans are extended, cancer is more likely.
2) We are much better at detecting and diagnosing cancer than 200 years ago. The better we are at seeing it, the more people we realize have it.
3) Lifestyle factors (smoking, diet, obesity, exercise) together account for roughly 2/3rds of the cancer we see in the US. In the past 100 years, smoking rates have exploded (although they are on the decline now), and there is an epidemic of obesity. This greatly increases the number of cancer cases each year. Additionally, HPV leads to large numbers of cancers in the cervix, head & neck, and several other sites.
4) Cancer treatment has extended the lifespan of people with cancer by many years. This means that there are more people alive who either have cancer or have had cancer. This is the "awareness" factor that can make it appear more prevalent.
Radiation causes cancer, but isn't nearly as strong of a carcinogen as many people think. Here's a question for you: we've done lots of studies on the people exposed to the atomic bombs in Japan during WW2. For those who survived the bombings, what do you think the excess risk of cancer death is? | [
"There has been considerable research done on the effect of low-level radiation on humans. Debate on the applicability of Linear no-threshold model versus Radiation hormesis and other competing models continues, however, the predicted low rate of cancer with low dose means that large sample sizes are required in or... |
why do veins swell when you constrict your blood flow? | Blood flows out from your heart along arteries, and back to the heart along veins. Blood pressure is very high in the arteries, and low in the veins - it's the drop in pressure that carries it through your circulatory system.
So, grab your arm above the elbow, and what's happening? You're constricting the whole area, raising the internal pressure. Think of the arteries, running deep down in the tissue, as high pressure hoses. You're squeezing them, but that has little effect. Meanwhile, the veins are made of floppy tissue that carried blood under low pressure, so your grip is enough to collapse them.
That means that blood is flowing out to the arm, but having trouble coming back.
As the veins are only used to holding low pressure their walls are weak and flexible. When all that extra blood has to go somewhere, they balloon out and fill with it. | [
"Veins may become temporarily blocked if the internal lining of the vein swells in response to repeated injury or irritation. This may be caused by the needle, the substance injected, or donating plasma. Once the swelling subsides, the circulation will often become re-established.\n",
"When blood vessels dilate, ... |
what is border adjustment and how will it let trump force mexico to pay for the wall? | I'm not an expert. But as I understood it, the border adjustment simply means import/export toll (I don't know the English word; I mean the fee you or a company has to pay to be allowed to transport goods to another country) is changed. Less import taxes for US Companies, and more export taxes for Foreign (Mexican) companies. This way, rather than paying the price of the wall directly, Mexico will "pay" through their companies paying import tolls to the US. Of course, that could mean Mexican Companies shift their export to other countries than the US, should that be possible. I can't give a guarantee that this is correct. | [
"Trump repeatedly said that Mexico will pay for the construction of the border wall, but did not explain how the U.S. government would compel Mexico to do so. Trump stated that \"there will be a payment; it will be in a form, perhaps a complicated form\". The Mexican government has rejected Trump's statements and h... |
Why isn't matter evenly distributed across the universe? | It is, just not on small scales. The basic structure of the universe on large scales is galactic superclusters, to clusters, to galaxies, to stars. At supercluster level, the universe is very evenly distributed.
[this](_URL_0_) link gave a good description of how the local distributions came about.
To paraphrase, matter was completely even after the inflation, but even natural variations break the evenness on small scales (in this case, atoms being slightly to the left, or similar). These small variations eventually led to grouping of matter naturally. | [
"As a matter of fact, the great majority of ordinary matter in the universe is unseen, since visible stars and gas inside galaxies and clusters account for less than 10 per cent of the ordinary matter contribution to the mass–energy density of the universe.\n",
"The remaining 4.9% of the mass–energy of the Univer... |
When And Why Did Children's Books Emerge? | I did an overview of pretty much the entire history of children's literature in [this answer about the rise of YA lit](_URL_0_), though I skirt around spending a lot of time doing in-depth discussion surrounding the beginnings of children's literature. If you're not satisfied with that answer and would like me to go more in-depth on that front, I'd be happy to do so. | [
"Children's literature has been a part of American culture since Europeans first settled in America. The earliest books were used as tools to instill self-control in children and preach a life of morality in Puritan society. Eighteenth-century American youth began to shift away from the social upbringing of its Eur... |
the rick perry indictment | Lehmberg is an elected district attorney. As such, she cannot be fired directly by Governor Perry. Lehmberg was charged with a DWI back in 2013, did some jail time, and successfully defended her position in a civil suit. Governor Perry does not want Lehmberg to remain in office, so he threatened to veto $7.5 M in funding specifically set aside for a public corruption unit that operates out of Lehmberg's office, unless she stepped down. She did not, so Perry vetoed the funding.
A complaint was filed against Governor Perry for this and presented to a grand jury, who indicted him on charges of abuse of an official capacity, and coercion of a public servant. | [
"On August 15, 2014, Perry was indicted by a Travis County grand jury. The first charge of the indictment was abuse of official capacity, which has since been ruled unconstitutional, for threatening to veto $7.5 million in funding for the Public Integrity Unit, a state public corruption prosecutors department. The ... |
how do shows like last week tonight identify clips for a clip montage? | Studios have library / archive services that will sell you clips to use. For example, [NBCUniversal Archives] (_URL_0_) has clips from their news shows.
| [
"Footage from the show is usually edited from an entertainment perspective that relies on \"suspense building mechanisms\" such as brief segments involving team members becoming agitated or startled, asserting they have seen or heard something of interest and then followed by a sudden cut to a commercial break. Con... |
How did early films get copied and mass-produced? | While I can't give a good answer, I can say what I would do if I had their technology.
I would take an unexposed reel and match it up with the film's reel. Laying the two strips over one another, shine a light through the original and then through the new film. The original film will filter the light that will then expose the new filmstrip.
I know very little about the mechanics of old film, but I imagine this might have worked. Can't tell you if it's what they actually did, though. I'll ask some of my friends in film, they might know better. | [
"The potential of movies as long term sources of revenue was unknown to early movie industry executives. Films were made quickly, sent into distribution channels and mostly forgotten soon after their first runs. Surviving prints were wontedly stored haphazardly, if at all. Early film stock was chemically volatile a... |
how does a thermal explosion cause a human to get knocked back, as often seen in action movies? | Movies aren't always representative of real life. Action movies even less so.
Of course, it's possible for an explosion to knock people back. Because of the rapidity with which explosion take place, they almost always create a shock wave. The problem with being knocked back with the shockwave from a thermal explosion, however, is that the shockwave is likely many thousands of degrees. Of course, only being in contact with it for a short time, you wouldn't necessarily be burnt to death (unless it was a *really* hot bomb), but it certainly wouldn't be as clean as movies lead us to believe. | [
"The shock wave from an explosion can be reflected by an inversion layer in much the same way as it bounces off the ground in an air-burst and can cause additional damage as a result. This phenomenon killed three people in the Soviet RDS-37 nuclear test when a building collapsed.\n",
"A thermal wave is created by... |
how broadcasters get such good sound of professional athletes while they are on the field. | The use [parabolic microphones](_URL_0_). They put a directional microphone at the focal point of a big bowl, and it makes it ultrasensitive towards sounds from a particular spot. | [
"In sports broadcasting, a sports commentator (also known as sports announcer, sportscaster or play-by-play announcer) gives a running commentary of a game or event in real time, usually during a live broadcast, traditionally delivered in the historical present tense. Radio was the first medium for sports broadcast... |
How does density affect the speed of seismic waves through the Earth? | Waves travel more slowly through denser material. A lot of people have this misconception because, for example, sound travels faster in water than air, and faster in steel than water. But actually the increasing density is impeding the speed of sound. It's the increased stiffness (elastic modulus) of these materials that drives their faster speed of sound. | [
"The density profile through Earth is determined by the velocity of seismic waves. Density increases progressively in each layer largely due to compression of the rock at increased depths. Abrupt changes in density occur where the material composition changes. \n",
"The propagation velocity of seismic waves depen... |
Historians, what was Christmas like during the American Revolution? | Christmas night 1776 General Washington crossed the Delaware river to mount a surprise attack on Hessian mercenaries in Trenton New Jersey. Not the heart warming story you were looking for but a Christmas story none the less.
Edit:
The following year Washington's Army was at winter quarters in Valley Forge where roughly half of his forces were sick/injured/or dying. | [
"In the aftermath of the American Civil War, Christmas became the festival highpoint of the American calendar. The day became a Federal holiday in 1870 under President Ulysses S. Grant in an attempt to unite north and south. During the 19th century, the Puritan hostility to Christmas gradually relaxed. In the late ... |
What was the result of the location of pangea, and the resulting difference in earth's centermass? | Firstly, Pangea was only the [most recent](_URL_0_) of at least 6 supercontinents that have existed in Earth's history. It formed about 300 million years ago, and started breaking up about 175 million years ago.
Secondly, as far as mass of the planet is concerned, the vast, vast majority is contained in the mantle and core, which are 2-6 times more dense. The crust makes up about 0.9% of the earth's volume, and just 0.5% of the earth's mass. Remember, the tectonic plates are up to *maybe* 100 km thick at their absolute maximum (35 km average for continental), whereas the earth is 12,742 kilometers across
Thirdly, the crust is lying buoyantly on the mantle, which deforms below it. What that means is that while continental crust is less dense and thicker than oceanic crust, the load on the underlying mantle is around about [the same](_URL_1_).
All this acts to make the effect on centre of mass negligible. | [
"Pangea broke apart after 70 million years. The supercontinent was torn apart through fragmentation, which is where parts of the main landmass would break off in stages. There were two main events that led to the dispersal of Pangea. The first was a passive rifting event that occurred in the Triassic period. This r... |
Does fungus build up a resistance to treatment like bacteria does? | What kind of anti-fungal treatment do you mean? Fungi can certainly evolve resistance to [agricultural fungicides](_URL_3_) but it sounds like you're more interested in [antifungal medication](_URL_4_) to which fungi have also evolved resistance: [1](_URL_2_) [2](_URL_0_) [3](_URL_1_). It seems as if whoever said that this doesn't occur was mis-informed. | [
"Development of fungal resistance can be prevented by not using cyproconazole \"repeatedly alone in the same season\" or by not using it late in the infection, that is, curatively. Fungi can develop resistance if the same fungicide is used repeatedly or when fungicides with the same mode of action are repeatedly.(p... |
What is more expensive - mail or plate armour? | At least in the Burgundian accounts, the mail armour is cheaper (in general) as the plate armour, but some very high grade mail armour could be a lot more expansive than low quality plates armour. For exemple, a full plate armour could cost between 37£ 3 s and 76£ 10s, a mail shirt, between 5£ 13s and 50£, a higher price than the lowest prince found for a full plate harness. (Those accounts spoke about livres tournoi, tournoi pounds, and not Sterling).
This variation in price is also found in the inventories of the armory of the tower of london (second part of the 14th), as Thom Richardson prouved in its thesis, where you could find mail shirts (iron) between 16s 1d and 46s 8d, and mail shirt made of steel, at the price of 4£. (Iron and steel are not always related to the use of proper steel or iron, but could aslo be use to note the quality of the armour)
Sources: Burgundian account, in AGR (Bruxelles) and ADN (Lille).
ROBCIS Dominiques, armes armures et armuriers sous le principat de Jean sans Peur (1404-1419) d'après les documents comptables, Paris, 1998.
RICHARDSON Roland Thomas, The medieval inventories of the Tower armouries 1320-1410, PHD Thesis, Unversity of York, 2012. | [
"By the 14th century, plate armour was commonly used to supplement mail. Eventually mail was supplanted by plate for the most part, as it provided greater protection against windlass crossbows, bludgeoning weapons, and lance charges. However, mail was still widely used by many soldiers as well as brigandines and pa... |
How long does it take for a cell to travel through your body? | [This page](_URL_2_) says that in a 120-day span, it will travel the body about 75,000 times. That gives you a bit over [2 minutes](_URL_0_). However, it will flow at different rates depending on the type of blood vessel it is in (see [here](_URL_3_)) and probably spends some time moving through your heart and also I think a much longer time being stored in the spleen (see [here](_URL_1_)). So, it's probably a bit less than that but of that order. Maybe someone else can provide a better estimate! | [
"Interphase is the phase of the cell cycle in which a typical cell spends most of its life. If, we consider that the total event (interphase and mitotic cell division) take place about 24 hrs. then the interphase is of 23 hrs. Interphase can also be thought of as lasting for 90% of the cell's life, while Mitosis us... |
How are multiple sounds transmitted through gases simultaneously? | One way of thinking of it is that you only hear *one* sound, which is the sum of all the individual sounds. If you look at a sound waveform, it's a single line travelling up and down as air pressure changes. A steady tone has a very simple wave (a sine wave). In fact any sound can be considered to be made up of sine waves of varying frequency and amplitude.
Sometimes sounds do cancel each other. If you play two very close notes, for example, you'll be able to hear a "beat" which is the result of the two soundwaves shifting in and out of phase, alternately reinforcing and (partially) cancelling each other. Sometimes, if you're in a quiet room with, say, a whiny computer fan, you might find there are places in the room where it sounds a lot quieter than you'd expect (this will probably only happen for one ear at a time). This is where reflections of the original sound meet out-of-phase and cancel each other out.
Noise-cancelling headphones work by playing the inverse of an incoming sound wave in order to (attempt to) cancel it completely.
As for how multiple sounds travel through the air, try filling a tray with water and letting drips of water fall on to it in different places. You'll see the circular ripple move out from each point. Where the ripples meet, they effectively move right through each other.
Here's a very brief video showing the effect with a slinky. There are two waves, one from either end, which pass right through each other:
_URL_0_
As to whether there's really a limit, I'm not sure. I suspect if you try to play too high a frequency/amplitude, other effects may take over and cause the usual addition/subtraction of sound waves in air to start breaking down. | [
"In low molecular weight gases such as helium, sound propagates faster as compared to heavier gases such as xenon. For monatomic gases, the speed of sound is about 75% of the mean speed that the atoms move in that gas.\n",
"In a non-dispersive medium, the speed of sound is independent of sound frequency, so the s... |
What is happening on the cellular level when you rub lotion into your skin, and why is it good for you? | When you say lotion you can mean one of a few different things. Products known as [emollients](_URL_0_) are lipid (fat) heavy solutions that restore barrier function to disrupted skin. Another sub-class of "lotions" are humectants, which hydrate the skin by trapping water. Generally speaking, the lotion (vehicle) has little/no activity at the cellular level, however you do see changes in the thickness of some epidermal layers and changes in the relative proportions of components of the extra-cellular matrix.
Other functions of lotions are to deliver various medications into the skin, and they're generally formulated to best serve as vehicles for the medication in a addition to being emollients/humectants. Other than that we can change qualities in the vehicle based on where on the body it will be used. Different vehicles are required for the scalp/hair, as opposed to the face, ect. | [
"Absorption through the skin is increased when lotions are applied and then covered with an occlusive layer, when they are applied to large areas of the body, or when they are applied to damaged or broken skin.\n",
"All topical products, including lotions, can result in the percutaneous (through the skin) absorpt... |
why is it so hard to find alcohol that doesn't taste...like alcohol? you'd think someone would make a killing off of 40% koolaid-flavoured alcohol. | Haven't you ever heard of flavored vodka? Tastes like candy. Especially caramel vodka, thats some good stuff. | [
"Excessive concentrations of some alcohols other than ethanol may cause off-flavors, sometimes described as \"spicy\", \"hot\", or \"solvent-like\". Some beverages, such as rum, whisky (especially Bourbon), incompletely rectified vodka (e.g. Siwucha), and traditional ales and ciders, are expected to have relatively... |
does true randomness exist in the universe? if i replayed the universe exactly the same from the start, would it be exactly the same? | Does true randomness exist in the universe?-Yes. At a quantum level randomness happens all the time. Would the universe be exactly the same if we re-ran it? Probably not, if our quantum theories are correct, although not everyone agrees. Whether we could notice the difference is anyone's guess. | [
"Randomness can be seen as conflicting with the deterministic ideas of some religions, such as those where the universe is created by an omniscient deity who is aware of all past and future events. If the universe is regarded to have a purpose, then randomness can be seen as impossible. This is one of the rationale... |
How did tribes like the Seminole in the Everglades deal with alligators? | To start out with, by the time the Seminoles started settling Florida, they already had guns. So lets turn the clock back a bit more. For thousands of years, alligators were on the menu for people living in Florida. They weren't really a common meal, of course, but their bones do show in trash middens alongside other game animals and fish. At the time of contact with the Old World, northeastern Florida and southeastern Georgia were Timucua territory. The Timucua sought out European alliances during war between the three Timucuan alliances that dominated the area. The French allied with the Saturiwa, which allowed Jacques le Moyne the opportunity to capture various aspect of Timucuan life in his art. This included an image of the Timucua preparing for a feast. [As you can see](_URL_1_), a young alligator is already cooking over the fire and another is about to be put on the rack. But those are small alligators, what about the adults? Luckily, le Moyne has an answer for that too.
[In this illustration](_URL_0_), a Timucua hunting party gets an exaggeratedly large alligator to bite down on a pole (foreground), then uses the pole for leverage to flip the alligator on its back. Once it's turned over, they're able shot its softer underbelly with their bows (background). | [
"Alligator boats were a type of amphibious vehicle used in the forestry industry throughout Ontario, Quebec, the Maritime provinces of Canada and the northern United States from the mid-19th century to the beginning of the 20th century. These boats were so named because of their ability to travel between lakes by p... |
how are wild plants domesticated? | It's a very very long process, where farmers basically just breed plants with traits they like, in an effort to make those traits more prevalent over time. | [
"The process of domestication of wild plants cannot be described with any precision. However, Bruce D. Smith and other scholars have pointed out that three of the domesticates (chenopods, \"I. annua\", and \"C. pepo\") were plants that thrived in disturbed soils in river valleys. In the aftermath of a flood, in whi... |
why does my heart rate drop when i exhale? | It's called sinus arrhythmia, and it's perfectly normal and benign, especially in young people. I have it too.
I'm a little fuzzy on the details, but I believe it's because the expansion of your lungs as you inhale puts pressure on a nerve that controls heart rate. | [
"During exhalation, the diaphragm relaxes, moving upward, and decreases the size of the chest cavity, causing an increase in intrathoracic pressure. This increase in pressure inhibits venous return to the heart resulting in both reduced atrial expansion and reduced activation of baroreceptors. This relieves the sup... |
the difference between unlawful and illegal. | They're pretty much interchangeable. You might define "illegal" as "forbidden by the law" and "unlawful" as "not permitted by the law", but they boil down to the same thing. "Illegal" also tends to be used more for criminal law, while a civil wrong is more likely to be described as unlawful, but that's not a clear cut rule. | [
"In US law, the term illegal \"per se\" means that the act is inherently illegal. Thus, an act is illegal without extrinsic proof of any surrounding circumstances such as lack of \"scienter\" (knowledge) or other defenses. Acts are made illegal \"per se\" by statute, constitution or case law.\n",
"Natural-law the... |
lasers and mirrors | If a mirror reflects 90% if light that means it absorbs 10% of the light. If 10% of a laser is enough to burn a thing then the mirror burns. There is no 100% reflective mirrors. | [
"BULLET::::- Active mirrors are mirrors that amplify the light they reflect. They are used to make disk lasers. The amplification is typically over a narrow range of wavelengths, and requires an external source of power.\n",
"Light from the medium, produced by spontaneous emission, is reflected by the mirrors bac... |
why do home thermostats have a "heat/ cool" switch? why can't you simply set a range and have it automatically determine whether to use the ac or the heater? | There are actually thermostats that have an 'auto' mode that does switch from heat to cool and vice versa. Typically, only higher end thermostats have this, though. This is because it takes more advanced temperature sensors to allow an 'auto' function to work.
Say it's summer and you have the thermostat set to 'cool', and 78 degrees. The AC blows cool air into the house, but it might reduce the temperature to 77 degrees. This is typically intentional, to increase the time between the system turning off, then on again as the temperature rises from outside heat. In this case, if you were in an 'auto' mode, the furnace would kick in, which would not be desirable in the summer!
Premium thermostats that do have an 'auto' switch for heat and cool have extra setpoints or criteria before allowing the system to shift modes. For example, some use the date to determine what month it is, to prevent the furnace from being used in the summer. Otherwise, it would be 'turn AC on if temperature hits 80F, and furnace if it hits 70F' or something like that. | [
"A home thermostat is an example of a closed control loop: It constantly measures the current room temperature and compares this to a desired user-defined set point and controls a heater and/or air conditioner to increase or decrease the temperature to meet the desired set point. A simple (low-cost, cheap) thermost... |
why are data caps for mobile phones still so small? | Phone companies are greedy so they set data limits low to either a) make you use less of their product than you normally would or b) pay more for using your natural level of usage. | [
"Because of its nature data at rest is of increasing concern to businesses, government agencies and other institutions. Mobile devices are often subject to specific security protocols to protect data at rest from unauthorised access when lost or stolen and there is an increasing recognition that database management... |
Does the wobble of our sun caused by Jupiter's gravity effect the weather on Earth? | Jupiter's gravity does affect the climate on Earth but it's over many thousands of years. The variations in Earth's axial tilt, orbital obliquity, etc caused by Jupiter are called the Milankovich cycles and are associated with ice ages. As for the 12 year orbit of the Sun/Jupiter system...the 11 year sunspot cycle likely has a larger effect, especially because the sun doesn't move that much compared to Earth's ellipiticity. | [
"The Jupiter Effect is a 1974 book by John Gribbin and Stephen Plagemann, in which the authors predicted that an alignment of the planets of the Solar System would create a number of catastrophes, including a great earthquake on the San Andreas Fault, on March 10, 1982. The book became a best-seller. The predicted ... |
How different is breast milk to formula in terms of the baby's health? | Please remember that this is /r/askscience. While it may be tempting to share your own experiences as a parent, this forum is for a discussion of science. **Please refrain from sharing your own experiences or speculation/guesses.**
There is a lot of research on this topic, so please make sure to use scientific sources (not popular media articles or parenting websites).
Thanks, have a wonderfully scientific day! | [
"Though it now is almost universally prescribed, in some countries in the 1950s the practice of breastfeeding went through a period where it was out of vogue and the use of infant formula was considered superior to breast milk. However, it is now universally recognized that there is no commercial formula that can e... |
Rhodesia & NIBMAR | The policy of 'No Independence Before Majority Rule' came out of the September 1966 meeting of the Commonwealth of Nations. At that meeting, Commonwealth members from the Caribbean, Asia and Africa (minus Southern Rhodesia) caucused together and proposed that the Commonwealth position should be No Independence Before Majority Rule. East African leaders like Milton Obote, Jomo Kenyatta and Kenneth Kaunda were particularly prominent in pushing this position, as they had already met in Dar es Salaam in Tanzania to articulate a unified strategy prior to the opening of the Commonwealth meeting.
On the other hand the UK, Australia and New Zealand formed a bloc resistant to NIBMAR. British PM Harold Wilson had previously been engaged in negotiations with Ian Smith that established a formula for independence, and was resentful at being forced to backtrack from those negotiations. Wilson proposed to the commonwealth a phased plan where UK would engage in another round of negotiations with Smith, and if Smith remained intransigent on points of contention, UK would end negotiations and _then_ support NIBMAR.
In between these two blocks was the government of Canada which sought to build a consensus between the two factions, and Harold Wilson gave Canadian PM Lester Pearson the task of writing a compromise draft communique that would present a consensus Commonwealth position on the Rhodesia issue. Pearson's compromise draft included NIBMAR as "the demand of a majority of the Commonwealth". Pearson's draft was ultimately adopted by the meeting.
So, NIBMAR was *not* a British attempt to maintain control over Rhodesia, it was a position articulated by African heads of state and forced on UK by diplomatic pressure.
----
Source
[UDI: The international relations of the Rhodesian Rebellion](_URL_0_) by Robert Goode, pp 170-177 | [
"Rhodesians made up an integral component of the Long Range Desert Group (LRDG), a mechanised reconnaissance and raiding unit formed in North Africa in 1940 to operate behind enemy lines. Initially made up of New Zealanders, the unit's first British and Rhodesian members joined in November 1940. It was reorganised ... |
Is analytic continuation of the Riemann-Zeta function more than just a reflection over a vertical line? | It's almost a reflection about the line Re(s)=1/2 (the critical line), but not exactly. If it were a reflection, then if s were a point to the left of this line, its value there would be equal to the value of the point exactly opposite on the right side of the line, and this point is 1-s. That is, we would have Z(s) = Z(1-s). But this isn't exactly what happens. In reality we have
* Z(s) = Z(1-s)\*2^(s)pi^(s-1)sin(pi\*s/2)Gamma(1-s)
So there is an extra scaling factor in there, and this scaling factor can make it totally look not like a reflection (see [this](_URL_0_)) However, this extra scaling factor is in there because the Riemann Zeta Function is actually "incomplete". We can construct the Riemann Zeta Function for Re(s) > 1 either by the sum of 1/n^(s) for n=1 to infinity, or we an do it as the product of (1-p^(-s))^(-1) over all primes p. This is the [Euler Factorization](_URL_2_) of the Riemann Zeta Function. When viewed this way, the product in the Euler Factorization is actually missing a contribution from a prime. The "Prime at Infinity".
In their natural state, the Rational Numbers do not live on a line, they're just a pile of fractions that we can add/multiply together. But, if we put them on a line ordered by their absolute value, then we find that there are holes in this line, tons of holes. By filling in these holes, we are able to construct the Real Numbers. So we get the real number system by 1.) Applying a geometry to the rational numbers and then 2.) Filling in the holes left by this geometry. It might then be natural to ask "Are there *other* geometries we could apply to the rational numbers that result in a *different* number system in a similar way?"
It turns out that the answer is "Yes!" If p is a prime number, then I can say that N is *p-adically* smaller than M if p divides M more than it divides N, and write this as |M|*_p_* < |N|*_p_*. For example, |50|*_5_* < |49|*_5_* and |16|*_2_* < |8|*_2_*. This can also be extended to fractions, where if the denominator has a p in it, then that takes away from the count. So |5/16|*_2_* > |5/8|*_2_* since 2 divides the bottom more in 5/16. This gives us an alternate geometry to arrange the rational numbers, and this geometry will be nicely behaved and have holes in it, just like when we put it on the line. If we fill in these holes, then we'll get a new number system that was constructed in the same way as the real numbers were constructed, just with a different geometry. These are the [p-adic Numbers](_URL_1_), and there's a different one for every prime p.
So using the same method, we can make the real numbers and the p-adic numbers (for each prime p). These should be thought of as siblings in a big family, where the reals are the odd one of the bunch. It then turns out that the reals+p-adics are the *only* number systems that can be made in this way. It then seems like the "Reals" should be included as a "prime" since it kinda behaves similarly to the primes in this way. We then say that the reals are the "Prime at Infinity" (which is a term we borrow from geometry). This "Prime at Infinity" doesn't have a number associated to it, but it behaves like primes in pretty much all other ways.
So, back to the Riemann Zeta Function. With this in mind, the Euler Product for the Riemann Zeta Function takes into account all the primes, except the reals. It seems like the reals are then a missing from the Riemann Zeta Function. In fact, we can view the term (1-p^(-s))^(-1) that appears for the prime p in the Euler Factorization as a specific kind of integral over the p-adic numbers and we can actually construct an analogous integral over the reals. The value of this integral will be 2^(-1)pi^(-s/2)s(s-1)Gamma(s/2) and if we append this to the Euler Factorization we get what is called the "Completed Zeta Function", Xi(s). The analytic continuation of *this* function is just a simple reflection:
* Xi(s) = Xi(1-s)
This follows from the above expression + properties of the Gamma function.
Note: This isn't how the Completed Zeta Function was originally made. Originally, we just used a trick involving a change of variables in an integral to recover the Zeta Function from the integral expression for the Gamma Function, and it is this that allowed us to get the analytic continuation in the first place. This transformation hinted at what Xi(s) should be, so we used that. The whole "prime at infinity" concept is a relatively modern idea. | [
"BULLET::::- The calculations in show that the zeros of the zeta function behave very much like the eigenvalues of a random Hermitian matrix, suggesting that they are the eigenvalues of some self-adjoint operator, which would imply the Riemann hypothesis. However all attempts to find such an operator have failed.\n... |
what do underwriters for insurance companies do? | Underwriters are the people actually taking on responsibility for the insurance claim; the people who will actually pay.
In a lot of cases this is the same company, but if for instance you use an insurance **broker**, that's where things would be different, because they would search around for the best company for whatever it is you need, and choose them on your behalf.
Say for example you use the insurance broker, "No Crash Insurance". They might shop around and find the best deal for you is with "Union Direct". In case it wasn't obvious, these names are made up for the purposes of this example.
If you accpted that, then your insurance would then be through "No Crash Insurance", underwritten by "Union Direct".
| [
"BULLET::::- Insurance underwriting - Personal lines insurance underwriters actually underwrite insurance for individuals, a service still offered primarily through agents, insurance brokers, and stock brokers. Underwriters may also offer similar commercial lines of coverage for businesses. Activities include insur... |
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