question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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why do (more) women not take birth control pills continually to never have periods? | It's actually a subject of debate whether taking oral contraceptive continuously has no medical consequences. The fact is that this is a fairly new idea, and there's no enough data to say what the long term effects would be.
[This website](_URL_0_) gives a good rundown of the pros and cons. It seems like a majority of... | [
"Progestogen-only contraceptive pills (sometimes called the 'mini pill') are taken continuously without a 7-day span of using placebo pills, and therefore menstrual periods are less likely to occur than with the combined pill with placebo pills. However, disturbance of the menstrual cycle is common with the mini-pi... |
When light is emitted from a source; do the photons start moving at the speed of light or do they accelerate up to it? | Photons always move at the speed of light, from the instant they come into existence. | [
"If an observer runs away from a photon in the direction the photon travels from a source, and it catches up with the observer—when the photon catches up, the observer sees it as having less energy than it had at the source. The faster the observer is traveling with regard to the source when the photon catches up, ... |
Why aren't there pure ATP supplements available on the market as energy boosters? What would happen if you took these? | Funnily enough, not a thing. The moment ATP hits the acidic environment of your stomach, it begins to hydrolyze into phosphate and adenosine (and probably further into adenine and ribose). In order to harvest the energy from this hydrolysis reaction, you need an enzyme or protein that can accept it. In the absence o... | [
"Most supplements rely on β-hydroxybutyrate as the source of exogenous ketone bodies. It is the most common exogenous ketone body because of its efficient energy conversion and ease of synthesis. In the body, β-HB can be converted to acetoacetic acid. It is this acetoacetic acid that will enter the energy pathway u... |
how do people who live in eastern asian countrys eat so much yet stay so healthy? | This should be tagged as biology, not culture. Weight gain/loss is determined by how many calories you take in, compared to those you expend based on your baseline metabolism and activity level. Ingredients can have more or fewer calories, but healthy food and unhealthy food with the same amount of calories will cause ... | [
"Surveys have found that one out of every six older persons living in urban areas in India aren't obtaining proper nutrition, one out of every three older persons does not obtain sufficient health care or medicine, and one out of every two older persons don't receive due respect or good conduct from family members ... |
why aren't password special characters universally agreed on? | Because there is no standards group maintaining this. And because some special characters have special meaning in certain locations. It wouldn't matter if the person writing the password code knew what they were doing and used modern best practices, but there's still some older code that uses older patters where having... | [
"The full strength associated with using the entire ASCII character set (numerals, mixed case letters and special characters) is only achieved if each possible password is equally likely. This seems to suggest that all passwords must contain characters from each of several character classes, perhaps upper and lower... |
if the constitution protects against double jeopardy, how can trials go an appellate court? | In what way would it violate the rule? Keep in mind that the *defendant* is the one who asks for the appeal; without the appeal, he is guilty, and the appeal can't actually convict him (it's not a second trial). | [
"Among other things, \"[t]he Double Jeopardy Clause forbids a second trial for the purpose of affording the prosecution another opportunity to supply evidence which it failed to muster in the first proceeding.\" The Clause does so to \"protect an individual from being subjected to the hazards of trial and possible ... |
why is it so hard to get that old 'hand drawn' look in modern anime/cartoons using computer animation? | It's not done very often because animating something that high quality would take a really long time. It's possible, just insanely time consuming. | [
"Originally, animation was all hand-drawn by artists, though in the 1980s, beginning with \"Captain Power\", computers began to automate the task of creating repeated images; by the 1990s, hand-drawn animation became defunct.\n",
"In the cartoon, animated hand-drawn scenes appear on a chalkboard, such as a clown ... |
how american college applications work. | So, for a bit of clarification, mostly for the stuff below, a university is made up of colleges. a college of liberal arts a college of business, et cetera.
you only have to apply directly to college if you want to major in it. you can usually minor in a field without being certified by the college, while you do need... | [
"College application is the process by which individuals apply to gain entry into a college or university. Although specific details vary by country and institution, applications generally require basic background information of the applicant, such as family background, and academic or qualifying exam details such ... |
How has the historiography of the First World War changed over time? | In my experience, most of the revisions were made within the overall narrative of WWI that you've described, focusing instead on who exactly was to blame for the ultimate outbreak of the war. For most of the 20th century the scholars seem to have been preoccupied with the location of the "smoking gun", and it shifted f... | [
"British historian Heather Jones argues that the historiography of the First World War has been reinvigorated by the cultural turn in recent years. Scholars have raised entirely new questions regarding military occupation, radicalizion of politics, race, and the male body.\n",
"The History of the Great War Based ... |
16th century Church of England question? | It would depend entirely on why you were saying what *he* was saying was a lie. | [
"The Church of England is the established church in England. Its most senior bishops sit in the national parliament and the Queen is its supreme governor. It is also the \"mother church\" of the worldwide Anglican Communion. The Church of England separated from the Catholic Church in 1534 and became the established... |
i have a cpap machine for sleep apnea. how similar / different is it from a medical ventilator? | The CPAP machine is simply designed to keep a small positive airway pressure (hence the name) in order to keep the airway open. You still must breathe, it doesn't do it for you. A ventilator actually will breathe for the person, so it will put positive then negative pressure , usually through a breathing tube that's ... | [
"CPAP therapy utilizes machines specifically designed to deliver a constant flow of pressure. Some CPAP machines have other features as well, such as heated humidifiers. CPAP is the most effective treatment for obstructive sleep apnea, in which the mild pressure from the CPAP prevents the airway from collapsing or ... |
what makes popular music recordings you hear on the radio sound so "good"? | Professional mixing and mastering engineers.
Basically, for bands as large as Maroon 5, you have multiple professionals mixing the song to get it to sound as clean, clear and crisp as possible. The better the mix engineer, the better the song will sound.
But it also all comes down to the ear of the mixing engineer. ... | [
"The custom recordings were usually instrumental versions of current or recent rock and roll or pop hit songs, a move intended to give the stations more mass appeal without selling out, but also disgusted some longtime listeners of the format. Some stations would also occasionally play earlier big band-era recordin... |
how come no one has prosecuted the president yet? | If your gonna take a shot at the king, you better not miss. Any prosecutor worth their salt is gonna make sure all of their ducks are in a row before bringing anything forward, and with something as big as impeachment there are a lot of ducks. For reference watergate took roughly 2 1/2 years from start to finish and th... | [
"The president is enjoys full immunity from judicial or any type of official prosecution during his incumbency. The president may only be prosecuted with the explicit assent of the Federal Assembly. If an authority intends to prosecute the president, it must address a \"request for extradition\" before the National... |
why isn't drug testing mandatory for politicians? | Politicians are the ones that would put these new laws in place. Also, some govern places where certain drugs are now legal. They also don't operate heavy machinery or have a direct impact on public safety. | [
"The United States adopted the Personal Responsibility and Work Opportunity Act in 1996, which gave individual states the authority to drug test welfare recipients. Drug testing in order for potential recipients to receive welfare has become an increasingly controversial topic. Richard Hudson, a Republican from Nor... |
Marquis de Lafayette's uniform | There are very few surviving epaulettes from the Revolutionary War, otherwise I'd send you towards an image of an original. Instead [here is a link](_URL_1_) to trusted reproduction site, you'll want to look specifically at the cockade epaulette. I am assuming that you're working off of the [Charles Wilson Peale](_URL_... | [
"Marie-Joseph Paul Yves Roch Gilbert du Motier, Marquis de Lafayette (; 6 September 1757 – 20 May 1834), known in the United States simply as Lafayette, was a French aristocrat and military officer who fought in the American Revolutionary War, commanding American troops in several battles, including the Siege of Yo... |
Is hemp really a miraculous plant that could replace dozens of products at a cheaper cost? | Hemp isn't a 'miraculous' product, per se, but it is useful and could be a cheaper or more effective replacement for a few different materials if grown industrially. The reason people seem to sing its praises and make it sound like a miracle product is because right now in North America you pretty much can't grow it i... | [
"A 1914 USDA report described the Italian hemp as the highest-priced hemp fiber in both the American and European markets, noting that it was obtained from plants similar to those cultivated in Kentucky at the time. The cause of the higher price was attributed to water retting and to increased care and labor in the... |
Is color an intrinsic property, or is it just the way we process different wave lengths? And could other species "see" totally different colors? | Color is actually a complex combination of light wave lengths and perception. The human eye (typically) has three types of cones which are sensitive to different light wave lengths. Adding those wave lengths up gives us our perception of color. One of the big tricks, is that there are essentially an infinite number... | [
"Spectral absorption, the selective absorption of certain colors, determines the color of most objects with some modification by elastic scattering. The apparent blue color of veins in skin is a common example where both spectral absorption and scattering play important and complex roles in the coloration. Light sc... |
A question about old-fashioned TV antennas | Some people step really heavily. This could affect things.
Besides that, probably just observer bias. | [
"The slot antenna was invented in 1938 by Alan Blumlein, while working for EMI. He invented it in order to produce a practical type of antenna for VHF television broadcasting that would have horizontal polarization, an omnidirectional horizontal radiation pattern and a narrow vertical radiation pattern.\n",
"Soon... |
Why don't scientists use natural units more often? | > It seems foolish to have an electron's charge be -1.6 x 10-19 C when we could create a new unit and set it equal to 1.
Funnily enough, someone beat you to this observation. When you're doing certain things in physics, it's quite common to use the electron volt:
_URL_0_
Basically, people use the most convenient u... | [
"Natural units are physical units of measurement defined in terms of universal physical constants in such a manner that selected physical constants take on the numerical value of one when expressed in terms of those units. Natural units are so named because their definition relies on only properties of nature and n... |
if it takes so many processors to simulate one second of human neural activity, why are processors so much more accurate and faster than brains? | Processors are very good, extremely accurate and very fast - but only at certain types of problem.
A processor can very easily solve any problem that can be expressed using an algorithm - a series of steps that can be followed, one at a time, to tell it how to solve the problem.
The difficulty is that our brains don'... | [
"A computer program that faithfully emulates a human brain, or that otherwise runs algorithms that are equally powerful as the human brain's algorithms, could still become a \"speed superintelligence\" if it can think many orders of magnitude faster than a human, due to being made of silicon rather than flesh, or d... |
if alcohol has been proven to cause cancer and other diseases, why aren't bottles covered in warning labels like cigarettes? | Ahoy, matey! Yer not alone in askin', and kind strangers have explained:
1. [ELI5: Why are there health warning labels on cigarettes and not McDonalds, soft-drinks, processed meat, or on the side of Supercars and Bikes? ](_URL_1_)
1. [Why is Alcohol not illegal because of how much harm it brings people and society? Wh... | [
"Increasing calls for the introduction of warning labels on alcoholic beverages have occurred after tobacco packaging warning messages proved successful. The addition of warning labels on alcoholic beverages is historically supported by organizations of the temperance movement, such as the Woman's Christian Tempera... |
Is it possible to make a laser that releases X-rays or gamma rays? | It doesn't work by the same principles as other lasers, but [free electron lasers](_URL_0_) can produce virtually any wavelength of coherent photons.
Edit: it's also possible to use a regular laser and [backscatter the photons off a high energy electron beam](_URL_1_). It's like bouncing a tennis ball off the front o... | [
"The laser produces hard X-rays, 10 times the relative brightness of traditional synchrotron sources and is the most powerful x-ray source in the world. LCLS enables a variety of new experiments and provides enhancements for existing experimental methods. Often, x-rays are used to take \"snapshots\" of objects at t... |
How and why did the North-American states unite into the United States? | Originally that is how the United States was created. A loosely related country of sovereign states. Each state printed it's own money, had it's own laws, provided for the welfare of their citizens, had it's own army. Basically the Articles of Confederation made the Federal government weak as possible. That presented p... | [
"In 1787, the Congress of the Confederation enacted the Northwest Ordinance, which created the Northwest Territory in what is now the upper Midwestern United States. The Ordinance specified that the territory was eventually to be divided into \"not less than three nor more than five\" future states. It was determin... |
Does earth appear bigger on the horizon than over head when astronauts see it from the moon?
| Well, the Earth doesn't set if you're standing still on the moon because the moon is tidally locked with the Earth. But that aside, were you to walk so far that you make the Earth set, yes it would appear bigger because of [the way we perceive the sky](_URL_0_). | [
"BULLET::::- The full moon covers only about 0.2 deg of the sky when viewed from the surface of the Earth. The Moon is only a half degree across (i.e. a circular diameter of roughly 0.5 deg), so the moon's disk covers a circular area of: × (), or 0.2 square degrees.\n",
"Among the most prominent features of the ... |
Questions about nose picking and other socially unacceptable habits | Risks: Small but real risk of infection, which in turn [can spread to the brain.](_URL_0_)
> Nose picking (rhinotillexomania) can lead to infections in the nose, which is situated very close to the brain. They share the same blood supply. Getting an infection anywhere in the area doctors call the "danger triangle" pr... | [
"The Obsessive–Compulsive Disorder Association of South Africa collectively concluded that nose picking (and mucophagy) are passing behaviors. Andrade and Srihari studied persons who were more apt to suffer from \"habitual and obsessive–compulsive behaviors.\" They discovered that those with compulsive issues showe... |
how the nes zapper gun (like the one used in duck hunt) knew where you were pointing on the screen. | The Zapper doesn't actually "shoot" out light. Instead, it's the reverse: it's a light sensor. When you pull the trigger, the screen turns black and the targets (ducks, discs, enemies, etc.) would flash a white square. If the Zapper is pointed at a white square, it registers as a hit. This is also why it's possible to ... | [
"The Wii Zapper is a gun shell peripheral for the Wii Remote. The name is a reference to the NES Zapper light gun for the Nintendo Entertainment System. It is mainly used for shooter games, including light gun shooters, first-person shooters, and third-person shooters.\n",
"The Zapper allows players to aim at the... |
why does usa elect their president based on who gets the most electoral votes and not by popular vote? | These vids explain far better than I could:
* _URL_1_
* _URL_0_
Enjoy.
| [
"Even though the aggregate national popular vote is calculated by state officials, media organizations, and the Federal Election Commission, the people only indirectly elect the president, as the national popular vote is not the basis for electing the president or vice president. The president and vice president of... |
why is it that some people absorb information easily while others can't? | It is training. Also - we absorb different kinds of information differently. For example I usually have no problem picking up new math/logic concepts, but I can't keep up with history, and can only understand music from a math/order standpoint. | [
"Psychologists have recognized for many years that humans have a limited capacity to store current information in the memory. Psychologist George Armitage Miller was very influential in this regard, proposing that people can process about seven chunks of information at a time. Miller says that under overload condit... |
With the sea levels rising, what's happening with mountain heights? | In a simple sense, yes, elevations are referenced to sea level, but in reality, things are much more complicated. Obviously sea level change (i.e. rising sea level) presents a problem for defining "sea level", but it was a problem well before that with tides, changes in heights of tides in relation to the shape of coas... | [
"At a May 2018 meeting of the United States House Committee on Science, Space, and Technology, Alabama's Representative Mo Brooks claimed that sea level rise is caused not by melting glaciers but rather by coastal erosion and silt that flows from rivers into the ocean.\n",
"BULLET::::- Sea level rise is projected... |
georgia's "religious freedom" bill | When it passed through the House the main 3 points were as follows
-- It cleared ministers from having to perform marriages that violated their religious beliefs; (meaning a minister that refuses to perform a LBGT marriage cannot be sued for discrimination)
-- Business owners could remain closed on Saturday or Sunday... | [
"In March 2016, the Georgia State Senate and the Georgia House of Representatives passed a religious freedom bill. On March 28, Georgia's governor, Nathan Deal, vetoed the bill after multiple Hollywood figures, as well as the Walt Disney Company threatened to pull future productions from the state if the bill becam... |
Tuesday Trivia | Adventures in the Archives | I've got a good one, a few years back I interned at a local archive in order to beef up my CV and get some general experience, because at this point I had none. After introducing myself and doing some light filing and genealogy work, I asked the head archivist if she had anything she wanted done but couldn't do herself... | [
"BULLET::::- The first season of the American television show \"The Librarians\" is centered on the efforts of an elderly Lancelot (using his last name, Dulaque, as an alias) to restore Camelot, which he considers to be a golden age of humanity. He manages to release magic back into the world using Excalibur in the... |
why is it preferable for an airplane to have the propeller pulling at the front, instead of pushing from the back? | Generally propeller placement actually comes down to engine placement.
You need the center of mass of a plane to be in front of the center of lift otherwise the nose of the plane will constantly be lifting up and trying to stall you out. This generally calls for the big heavy engines to be in front of the wing.
Ther... | [
"The thrust to propel the aircraft forward comes from its propellers or jet engines. Reverse thrust for backing up can be generated by thrust reversers such as on the Boeing C-17 Globemaster III, or reversible pitch propellers such as on the Lockheed C-130 Hercules. Most aircraft, however, are not designed to back ... |
Why did Japan join the Axis during World War II | Hi, I discuss the details of Japan's joining of the Axis alliance [here](_URL_0_). | [
"At the end of September 1940, the Tripartite Pact formally united Japan, Italy and Germany as the Axis Powers. The Tripartite Pact stipulated that any country, with the exception of the Soviet Union, which attacked any Axis Power would be forced to go to war against all three. The Axis expanded in November 1940 wh... |
nitrogen fixation | Basically, nitrogen is really, **really** important for living organisms. Unfortunately, most of the nitrogen on Earth is in the atmosphere in the form of N2 and most creatures lack the tools to break it apart and make use of it.
Fortunately, there are bacteria that *do* have the tools to do so. They are able to conv... | [
"The technical nitrogen fixation was made possible by the Haber-Bosch process, in which nitrogen is converted into ammonia by reductive protonation in the presence of iron catalysts under high pressures ( 150 bar) and temperatures ( 400 °C). In chemical nitrogen fixation (i.e., the transformation of atmospheric nit... |
What does it mean when we say there may be more dimensions but they are too 'small' or 'curled up' for us to see? | Imagine an infinitely long cylinder. If we contract the radius to a very small distance, then it would appear, to a macroscopic observer, that this was a one dimensional line. But on a very small scale, one would note that the surface of this cylinder had two dimensions - one which is very large and stretches along t... | [
"The many-angled ones exist in a space with more dimensions than our own; hence, they appear to be \"many angled\". As a result, when they manifest in our universe they appear as disconnected floating body parts of some larger beast that is complete in the higher dimension (similar to how a three dimensional being ... |
why do some plants have red leaves instead of green? do they get less energy from sunlight? | The colour green comes from a molecule called chlorophyll in plant cells. I believe chlorophyll can come in different types, that capture different wavelengths of sunlight. In most plants, all wavelengths except for green are absorbed, so green is reflected back. That's why they appear as green.
During the fall, the ... | [
"Green is common in nature, as many plants are green because of a complex chemical known as chlorophyll, which is involved in photosynthesis. Chlorophyll absorbs the long wavelengths of light (red) and short wavelengths of light (blue) much more efficiently than the wavelengths that appear green to the human eye, s... |
what *is* the space that gets taken up when i add "data" to my hard drive, phone, memory card, ect., and how exactly does it work? | Think of the storage as being lots and lots of switches.
When your phone is empty, the position of these switches - whether they are on or off - really doesn't matter.
When your phone is full, the switches are all being used to represent the photos, apps and and music in your phone. You can't install more apps, becau... | [
"When data is deleted from storage devices, the references to the data are removed from the directory structure. The space can then be used, or overwritten, with data from other files or computer functions. The deleted data itself is not immediately removed from the physical drive and often exists as a number of di... |
what causes rivers to suddenly be rapid in certain areas? | The speed of a river is determined by a lot of factors - the steepness of the ground it's flowing down, how deep the water is, and how wide, mostly. If those change suddenly, the speed of the river can change suddenly too. | [
"Slow-rising floods most commonly occur in large rivers with large catchment areas. The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but smal... |
What's the point of SATA 6 GB/sec? | First, just in case you didn't know, those are bits per second, and SATA uses a 10/8 encoding which means that the 1.5 Gbit/s SATA-1 rate equals 150 MByte/s, the 3 GBit/s SATA-2 rate equals 300 MByte/s, and 6 GBit/s SATA-3 rate equals 600 MByte/s.
Secondly, there are SSD drives on the market today that can read and wr... | [
"The eSATA version of SATA 6G operates at 6.0 Gbit/s (the term \"SATA III\" is avoided by the SATA-IO organization to prevent confusion with SATA II 3.0 Gbit/s, which was colloquially referred to as \"SATA 3G\" [bit/s] or \"SATA 300\" [MB/s] since the 1.5 Gbit/s SATA I and 1.5 Gbit/s SATA II were referred to as bot... |
how is it profitable for wineries to sell their wine cheaply enough to an import/export company that i can get it on another continent for $5.70/bottle? | There is a world wide surplus of basic grade grape wine juice. Australia, Chile, Argentina, US all produce commodity grade grape wine juice.. Perhaps you've heard of [Charles Shaw](_URL_0_), aka Two Buck Chuck. A few years ago it was about $2 at the retail level, wholesale perhaps a dollar or less. Obviously those wine... | [
"While there may be tens of thousands of wine producers across the globe, it is estimated that perhaps only 250 produce the sort of premier wines that are worth considering as a financial investment. It is also estimated that about 90 percent of the world's investment grade wine is produced in the Bordeaux region o... |
what spurred the usage of 'xmas' in place of 'christmas'? | "X" is the Greek Letter Chi, which is the first letter of "Christ" when written in Greek. The X is just an abbreviation, and was used for many years by Christians as a secret code that only others would know to show they are Christian in times when it wasn't best to be open about it. | [
"There is a common misconception that the word \"Xmas\" stems from a secular attempt to remove the religious tradition from Christmas by taking the \"Christ\" out of \"Christmas\", but its use dates back to the 16th century.\n",
"The common abbreviation \"Xmas,\" for Christmas, is a remnant of an old scribal abbr... |
how do vegetables get vitamins and minerals if they only "eat" water and sunlight? | They also take in nutrients from the dirt. That's how you can get things like iron etc. | [
"Vitamins and minerals are required for normal metabolism but which the body cannot manufacture itself and which must therefore come from external sources. Vitamins come from several sources including fresh fruit and vegetables (Vitamin C), carrots, liver (Vitamin A), cereal bran, bread, liver (B vitamins), fish li... |
what gives fire its shape? | When air is heated, it tends to expand.
To explain why it expands - Heat is basically the measure of vibration and movement of the actual molecules within a substance. When something is solid, these vibrations don't have enough energy to stop the attractive forces between the molecules thus they stay mostly in place.
... | [
"According to Descartes, the motion, or agitation, of these particles is what gives substances their properties (i.e. their fluidity and hardness). Fire is the most fluid and has enough energy to render most other bodies fluid whereas the particles of air lack the force necessary to do the same. Hard bodies have pa... |
What could be the drawbacks of immortality? | Your memory would run out after not very long. Unless you had some kind of memory upgrade you would no doubt, before too long, not be able to remember most of your life.
Not something often considered by people who make up long lived or immortal characters. | [
"Certain scientists, futurists, and philosophers have theorized about the immortality of the human body, with some suggesting that human immortality may be achievable in the first few decades of the 21st century. Other advocates believe that life extension is a more achievable goal in the short term, with immortali... |
how do free softwares like vlc player make any money? | Broadly speaking, they don't, but that's okay because they aren't trying to. VLC is "community-developed" software; it's just a bunch of people who got together to write a video player because they wanted to. | [
"Certain items are provided for free. Providing free DLC can also provide revenue for game companies at the expense of users' convenience. For example, \"\" for the PlayStation 3 was shipped with certain features disabled. However, users can freely download packs to re enable the missing content from the PlayStatio... |
how do air brakes work? | They are not that much different than regular brakes.
Reguar brakes use hydraulic fluid. You push the brake pedel, and your master cylinder forces fluid down the brake line, and that squeezes the brake pads against the rotor.
Air brakes are the same thing. You have a compressed air tank, and when you press the brak... | [
"An air brake is a panel conforming the shape of an aircraft that can be opened with hydraulic pressure in order to create drag, similar to spoilers which are on the edges of the aircraft wings and open in an upward position forcing the plane towards the ground. Air brakes are used when the aircraft needs to reduce... |
how does 'immigration reform" aka legalizing 11 million people and allowing for more foreign workers help create more jobs? | As far as I know, it doesn't. The only thing it will do is further depress wages. Simple supply and demand.
| [
"Undocumented immigrants have been considered a source of low-wage labor, both in the formal and informal sectors of the economy. However, in the late 1980s with an increasing influx of un-regulated immigration, many worried about how this would impact the economy and, at the same time, citizens. Consequently, in 1... |
How do Galaxies Accelerate? | You don't need to worry about time dilation too much - the gravity fields and velocities are almost always weak enough and slow enough that it doesn't make much difference.
You do need to worry about the expansion of spacetime if you're working on large distances. Space is expanding everywhere at a rate of about 65 km... | [
"However the observed velocity dispersion of galaxies within a galaxy cluster does not depend on the mass of the galaxies. The explanation is that a galaxy cluster relaxes by violent relaxation, which sets the velocity dispersion to a value independent of the galaxy's mass.\n",
"Dynamical friction is believed to ... |
what causes the static screen when you go to a nonexistent channel on your tv. | It's just noise in the electronics.
In old televisions, where you were capturing things with an antenna and adjusting with a dial, a small portion of the static at night was caused by the cosmic microwave background radiation.
Numerous other more local sources contribute most of the noise. | [
"Many televisions and monitors automatically degauss their picture tube when switched on, before an image is displayed. The high current surge that takes place during this automatic degauss is the cause of an audible \"thunk\" or loud hum, which can be heard (and felt) when televisions and CRT computer monitors are... |
how do returns work at retail stores? what does the store do with broken returns? | I used to work at Best Buy. When we get a return, it goes into something called functionality check where someone checks the device for accessories or any damage/defects. If it's good, they mark it "open box" at a discount. If it's broken, they send it out to their service center to be repaired and then resold in the s... | [
"In retail, a product return is the process of a customer taking previously purchased merchandise back to the retailer, and in turn receiving a refund in the original form of payment, exchange for another item (identical or different), or a store credit. \n",
"Items deemed resellable are displayed for purchase in... |
How do computers calculate limits, derivatives, and integrals? | tl;dr: not really. CAS's sometimes use them, but that's not really what you're asking I think.
There are two types of systems you could be dealing with here.
First, using numerical methods on a computer to take a definite integral, derivative at a point, etc, generally use an array of numerical techniques. For exam... | [
"In mathematics, a limit is the value that a function (or sequence) \"approaches\" as the input (or index) \"approaches\" some value. Limits are essential to calculus (and mathematical analysis in general) and are used to define continuity, derivatives, and integrals.\n",
"The derivative of a function can, in pri... |
Did the Soviets create any movies about the horrifying prospect of nuclear war between themselves and the USA? | ["Dead Man's Letters,"](_URL_0_), from 1986, seems to fit the bill. | [
"The film postulates a fictional war between NATO forces and the Warsaw Pact countries that rapidly escalates into a full-scale nuclear exchange between the United States and the Soviet Union. The action itself focuses on the residents of Lawrence, Kansas and Kansas City, Missouri, as well as several family farms s... |
Can honey be used as an antibiotic? I've read a few articles claiming that it has the ability to help psoriasis, various skin conditions, cuts, insect bites, etc. I'm looking for some hard evidence, as the articles I'm finding on the net seem to be biased. | While honey has some compounds in it with antibiotic properties, they aren't at a high enough concentration to really do anything for you at the level you would need if you were trying to treat an infection. Part of why we look for novel antimicrobials in unusual places isn't so we can then use that source as our sour... | [
"Antibacterial properties of honey are the result of the low water activity causing osmosis, hydrogen peroxide effect, and high acidity. The combination of high acidity, hygroscopic, and antibacterial effects have led to honey's reputation as a plausible way to mummify a human cadaver, despite lack of concrete evid... |
how do podcasts make any money on advertising when their ads are just commercials for other podcasts? | They also advertise other things that cost money, like Audible books, mattresses, website hosting/design, etc. | [
"Initially, production and distribution costs of the podcast were funded entirely by Carolla himself. Carolla stated that bandwidth costs were over $9,000 per month as of May 2009. In September 2009 Carolla began generating revenue for the show with spoken advertisements for his first sponsors. Shows on the network... |
with the release of last christmas in 4k, how are old music videos that are so low in resolution remastered in 4k? | The original was shot in very high quality to physical film (35mm probably) and then was compressed for the media standards and capabilities of the day.
They just get the original footage and compress to 4k instead of whatever the first release was. They may haved digitally altered the colours to make it more saturate... | [
"The core game and story for all games remains unchanged with the remastered versions. For the remastering, all three games have had a graphics overhaul to allow them to support modern 720p resolution. When in 3D mode the games run at 30fps, while in normal mode, the games run 60fps. All three of the games also hav... |
the difference between architects and engineers in the design of a project, and how they work together | In as simple terms as possible, the architect comes up with the design of the building/area/whatever itself, and engineers figure out how to make the design work as closely to what the architect wants. They go back and forth about what is and isn't possible, costs, etc to come up with the final plan.
In short:
Archi... | [
"The architect is usually the lead designer on buildings, with a structural engineer employed as a sub-consultant. The degree to which each discipline actually leads the design depends heavily on the type of structure. Many structures are structurally simple and led by architecture, such as multi-storey office buil... |
Was Child Rape/Pedophilia Legal During the time of American slavery? | I don't focus on sexual abuse of children in [this older answer](_URL_0_) but do touch on the issue in the follow-ups. *Obvious* content warning if you click through, or read further, as this is all about sexual assault and violence.
To reiterate, it was one of the few places where there were any appreciable legal pro... | [
"Rape laws in the south embodied a race-based double standard. Black men accused of rape during the colonial period were often punished with castration, and the penalty was increased to death during the antebellum period; however, white men could rape female slaves without fear of punishment. Men and boys were also... |
How do nerves interpret the movement of molecules as heat? | Your cells have ion channels whose permeability to certain ions is influenced by temperature. By changing the permeability of the channels you change the electrochemical gradient of the cell which can easily be translated into an action potential. Really they aren't directly measuring the speed of molecules, they're me... | [
"On a microscopic scale, conduction occurs within a body considered as being stationary; this means that the kinetic and potential energies of the bulk motion of the body are separately accounted for. Internal energy diffuses as rapidly moving or vibrating atoms and molecules interact with neighbouring particles, t... |
why did competing video stores not have any issues getting all new films, yet competing online services seem to have to fight over content? | [First sale doctrine](_URL_0_), which was court ruling that stated that once you purchased something you could do with it as you pleased. If a video was available for sale, any video store was free to purchase it and rent it out. Studios could (and often did) release VHS tapes for like $100 at first ("priced for rental... | [
"Analysts believed that while this was a major victory for the video game industry, the challenge is not yet over. Dan Offner, a partner for the video game industry analysis firm Loeb & Loeb believed that similar laws and regulations will be sought by State and Federal governments, as \"the regulation of mature con... |
if food contains so much energy in the kilocalorie scale, why can't we use that energy to power our homes? | We do, its called diesel fuel. They have similar energy densities, and this is why petroleum is the most common form of transportation fuel. For stationary power plans coal is more common, but it is pretty much the same thing, a complex hydrocarbon.
Edit: also Ethanol, we straight up turn corn into car fuel sometimes,... | [
"Energy in food comes from three sources: fat, protein, and carbohydrates. A typical energy bar weighs between 45 and 80 g and is likely to supply about 200–300 Cal (840–1,300 kJ), 3–9 g of fat, 7–15 g of protein, and 20–40 g of carbohydrates.\n",
"Many governments require food manufacturers to label the energy c... |
Before the modern era where did people go to report crimes? Who were their 'police' basically? | It is very difficult to tell for most premodern societies. Luckily, Iceland left an extensive body of literature that focuses almost exclusively on the issue.
The Icelandic Althing is generally said to be the oldest Parliament in the world, but that doesn't really capture the nuances of the government. Iceland had a l... | [
"Before the 19th century, there were few municipal police departments, though the first had been created in Paris in 1667. As police activities moved from appointees helped by volunteers to professionals, the idea of dedicated detectives did not immediately arise. The first private detective agency was founded by E... |
the bank crisis 1837 | Cause:
Local banks receive federal bank money and loan too much paper money (not gold or silver) out.
Details:
Jackson hated the national bank and decided not to recharter its bill in 1832. This was the start of the BANK WAR. Jackson believed that a national bank had high interest rates and exploited smaller, wester... | [
"During the Panic of 1837, the United States suffered a financial crisis brought on by speculative fever. This crisis caused a run on the Bank of the State of Alabama. Clay ordered the bank to provide a detailed report of its finances, but it was unable to do so.\n",
"The Panic of 1792 was a financial credit cris... |
how does turning down the temperature while away from home actually save energy? | > It seems to me that maintaining an internal temperature would require less energy than letting the house cool and then having to crank the furnace on high for an hour or more to raise the temperature back up to a comfortable level, assuming the external temperature is much colder than the internal temperature.
E... | [
"Instead of letting your central heating system cool down completely, so that you often have to keep switching it on for a short time to give your home a big blast of heat, it is best to keep your central heating running continuously with the central wall-mounted thermostat set at the lowest temperature at which yo... |
why don't we treat addictions by putting the addicted people into medically induced coma for a long time? | This wouldn't address the behavioral factors that brought people to their addictions. | [
"Helping an individual stop using drugs is not enough. Addiction treatment must also help the individual maintain a drug-free lifestyle, and achieve productive functioning in the family, at work, and in society. Addiction is a disease which alters the structure and function of the brain. The brain circuitry may tak... |
shouldn't many more of us have bed bugs? | Oh they are a real problem.
But they don't get around too well by riding on people.
They aren't like fleas, who are highly mobile. Bed bugs are slow and don't jump. So if you sit on a couch with bed bugs, you might pick some up, but they won't be leaping leaping onto passing strangers.
However, when you put your... | [
"Bed bugs occur around the world. Rates of infestations in developed countries while decreasing from the 1930s to the 1980s have increased dramatically since the 1980s. Previous to this they were common in the developing world but rare in the developed world. The increase in the developed world may have been caused... |
Why are Norway and Sweden not united today? | The economic (and hence geopolitical) interests of the two countries were, and are, quite different; they are separated by a mountain range that makes it difficult to get much overland trade going. Sweden looks east across the Baltic (and south to Germany); Norway looks west, to the North Sea and the Atlantic (and to t... | [
"The Union between Sweden and Norway is an overriding theme of the history of Sweden in the 19th century. On 4 November 1814, the kingdoms of Sweden and Norway formed a personal union under one king. The two countries had completely separate institutions, except for the foreign service led by the king through the S... |
How are metal welds so strong? | Because the weld isn't an adhesive. You can think of it like taking two pieces of paper and then instead of making them stick together, you melt the atoms in each paper down and then press them together, then when it cools down its one piece of paper. Overall the welding is weaker than the rest of the metal, but its st... | [
"In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that, based on weld configuration (butt, full penetration, fillet, etc.), can be stronger than the base material (parent metal). Pressure may also be... |
what is the difference between decibel and sone? | The decibel (dB) is a unit used to express the ratio of two values of a physical quantity, often power or intensity. One of these values is often a standard reference value, in which case the decibel is used to express the level of the other value relative to this.
The sone is a unit of how loud a sound is perceived.... | [
"In the International System of Quantities, the decibel is defined as a unit of measurement for quantities of type level or level difference, which are defined as the logarithm of the ratio of power- or field-type quantities.\n",
"The definition of the decibel is based on the measurement of power in telephony of ... |
what is the big deal about "unlocked" smartphones? | Smart phones are quite expensive and so present an entry barrier to cell phone companies who are trying to provide a service. To solve this they sell phones which might cost $800 at only $200 if you agree to a 2-year contract, planning to recoup the cost over the course of the agreement.
However, if you can unlock you... | [
"A hardlocked phone is one in which a telecom provider has modified the firmware on the phone to make it impossible to manually enter the unlock codes in any way. The only solution to SIM-unlock such a phone is to change the firmware to a firmware which has not been modified by any telecom provider, a so-called \"u... |
mechanical advantage | Pulleys provide a mechanical advantage depending on how many wheels they have.
This can be explained using a few simple concepts.
If you were to tie a rope to an object (let’s say it’s a brick) and you threw the other end over a tree branch, when you pull that end, you pull the brick up even though your pulling the... | [
"Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force. The model for this is the \"law of the lever.\" Machi... |
English common law and U.S. common law... what, if anything, was kept in the new republic? | (I'm going to take this on, since it has come up in my research. How it relates to my flair is a long story. The short version is "church property disputes." So while I am a historian, I am not a lawyer, and some of what I think I have figured out may need to be corrected.)
The American common law tradition did not st... | [
"The common lawso named because it was \"common\" to all the king's courts across Englandoriginated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. The British Empire spread the English legal system to its historical colonies, many of which retain the comm... |
Can people with a cochlear implant hear the direction a sound is coming from? | Directional hearing is largely a result of having two ears. Since sound must strike each one at different times depending on the distance and the brain can calculate a heading from that. There's no reason implants can't do the same. | [
"The sound information from the cochlea travels via the auditory nerve to the cochlear nucleus in the brainstem. From there, the signals are projected to the inferior colliculus in the midbrain tectum. The inferior colliculus integrates auditory input with limited input from other parts of the brain and is involved... |
why do some cuts heal quicker than others | Some parts of your body, like the inside of your mouth, are "primed" to heal and will heal much faster than other parts. Cuts on your hands, or anywhere where the skin is constantly being stretched and bent will take longer than places where the skin is basically left alone to get on with repairing itself. | [
"In recent years, advances have been made in accelerating healing of chronic wounds and ulcers. Chronic wounds produce fewer growth hormones than necessary for healing tissue, and healing may be accelerated by replacing or stimulating growth factors while controlling the formation of other substances that work agai... |
advertising with use of a competitor's name | A Mac is a real thing that exists. You don't need permission to call something by its name. It's honestly that simple. | [
"Comparative advertising or advertising war is an advertisement in which a particular product, or service, specifically mentions a competitor by name for the express purpose of showing why the competitor is inferior to the product naming it. Also referred to as \"knocking copy\", it is loosely defined as advertisin... |
How did the Vietnamese react upon discovering the Killing Fields, extermination camps, etc during the Cambodian War? | Follow up question: how well known was extent of the Cambodian genocide by Vietnamese leadership, and what role did it play in the breakdown of relations and decision to invade? | [
"In September 1977, Cambodia launched division-scale raids over the border, which once again left a trail of murder and destruction in villages. The Vietnamese claimed that around 1,000 people had been killed or injured. Three days after the raid, Pol Pot officially announced the existence of the formerly secret Co... |
how come bottled water is such a hot commodity while other animals can still drink water from unfiltered lakes and rivers? | Wild animals have lots of parasites and DO face serious repercussions. There's a reason the animals in zoos live longer and grow bigger than in the wild, and it's not just that they have no predators. Try adopting a stray dog right when it arrives in the shelter; they're full of parasites and need a LOT of medicine to ... | [
"In addition to the supply of tap water, many local water resources are also being acquired by private companies, most notably Nestlé Waters with its numerous brands, in order to provide commodity for the bottled water industry. This industry, which often bottles common ground water and sells it as spring water, co... |
How did the leaders of the time, both American and English, react to the Boston Tea Party? | I can't speak to the English aspect of things, but the Boston Tea Party made American leaders really uncomfortable. There's a really good book specifically answering your question called *The Shoemaker and The Tea Party* by Alfred Young. In a nutshell, American leaders were not happy with the idea that the lower clas... | [
"The Boston Tea Party arose from two issues confronting the British Empire in 1765: the financial problems of the British East India Company; and an ongoing dispute about the extent of Parliament's authority, if any, over the British American colonies without seating any elected representation. The North Ministry's... |
Why were so many early presidents fluent in greek and latin? Did they speak/write in it often? | Knowledge of Greek and Latin was a fundamental of a classical education. It's not to "show off" their educated status, per se, but just a part of being educated. It allowed them to read classical works of literature in their original language, which would also be part of their education. In fact, admission to universit... | [
"John Adams, the second president of the United States, learned to read Latin at a young age. In preparation for attending Harvard University, Adams attended a school for improving his Latin skills. While posted in France, Adams became fluent in French.\n",
"Of the 44 men who have served as presidents of the Unit... |
Are agricultural societies more violent than hunter gatherer ones? | That is conventional thinking, that agricultural societies are violent while hunter-gatherers are peaceful, but it's wrong and misleading and draws heavily from the idea of the [Noble Savage](_URL_0_). It's more a matter of the type of violence. Hunter-gatherers, at least mobile ones (there were some sedentary hunter-g... | [
"It has been argued that hunting and gathering represents an adaptive strategy, which may still be exploited, if necessary, when environmental change causes extreme food stress for agriculturalists. In fact, it is sometimes difficult to draw a clear line between agricultural and hunter-gatherer societies, especiall... |
why does it always feel like there's somebody behind you in the dark? | It doesn't feel like that to me. I love the bliss of the night.
Generally, evolution gave us a better safe than sorry mentality. Checking if someone isn't sneaking up on you is easily done at little cost to you. Facing the consequences if someone does happen to be sneaking up on you is very costly. Any impetus to make... | [
"Things turn dark after an obscure presence arrives with them and start chasing them. Odd accidents and curious wounds happen. Gary tries to warn them, but because of his dementia nobody believes him, and don't trust them. \n",
"\"Where His Light Was\" comes from the perspective of when you're walking through a h... |
why doesnt earthing a connection discharge all the electricity in the circuit? | In normal circuit operation, you need a closed loop to keep the current flowing. But that is only true in "steady state"; you can have short term current flow without a closed loop.
All you really need to get current to flow is a voltage differential and sufficient mobile charge carriers. If you don't have a c... | [
"In a building with electricity it is normal for safety reasons to connect all metal objects such as pipes together to the mains earth to form an equipotential zone. This is done in the UK because many buildings are supplied with a single phase supply cable where the neutral and earth conductors are combined. Close... |
How much memory do different animals posses? | Different animals might have different kinds of memory that are useful in their environment. For example, Clark's nutcrackers have really good spatial memory. Studies have shown that they can remember where they stored food for the winter better than graduate students, but they may not necessarily "remember" a partic... | [
"Chaser had the largest tested memory of any non-human animal. She was bred by Wayne West at his Fleet Hill Farms in Pauline, South Carolina. She was taught by her owner, Wofford College Professor Emeritus of Psychology John W. Pilley, with the formal research published in Elsevier's journals \"Behavioural Processe... |
When did streets stopped being narrow and crooked and started being wider with wide sidewalks and straight? | The Romans actually made some of the straightest roads in the world since it was the empires life blood.
But in modern times its probably when we started to pave all the roads that it became easier to do in a straight line than a curved one. | [
"In the western neighborhoods of the city, near the Champs Élysées, the streets, mostly built in the 17th and 18th centuries, were reasonably wide and straight. A very few, including the Chausée d'Antin and the rue de l'Odéon, had sidewalks, which had first been introduced into Paris in 1781. The Paris streets in t... |
why are some people able to survive huge falls while some die instantly from much smaller ones? | A mixture of extreme luck and what you land on. If its concrete your dead, if its grass or dirt you have a very small chance of bouncing a few times breaking lots of bones but still potentially surviving. Human terminal velocity is 120 mph (your top speed in a free fall) so just think about the different types of mat... | [
"Falling is the second leading cause of accidental death worldwide and is a major cause of personal injury, especially for the elderly. Falls in older adults are an important class of preventable injuries. Builders, electricians, miners, and painters are occupations with high rates of fall injuries.\n",
"The most... |
why does perception of color change after taking off ski goggles? | Your eyes have special cells called Cone Cells that give you the ability to see color. You have three types of cone cells - S (short wave), M (medium wave), and L (long wave), but for the sake of simplicity, we'll respectively call them blue, green, and red. (Fun fact: The absence of any or all of these cone types ar... | [
"Dark adaptor goggles, also called red adaptation goggles, are used in the field of meteorology and astronomy for adapting the eyes to the dark prior to an observation at night. They also aid with the identification of clouds during bright sunshine or glare from snow. The goggles are made with red-tinted plastic le... |
Does electrolysis work to separate hydrogen and oxygen from salt water? or does it have to be purified first? | [This page](_URL_0_) has a good explanation of the processes involved in the electrolysis of brine (a saturated NaCl solution). You do create hydrogen gas via this reaction, but instead of O2 you will form Cl2 (chlorine gas) at the other electrode. | [
"The electrolysis of water is a simple method of producing hydrogen. A low voltage current is run through the water, and gaseous oxygen forms at the anode while gaseous hydrogen forms at the cathode. Typically the cathode is made from platinum or another inert metal when producing hydrogen for storage. If, however,... |
African-American Islam and the civil rights movement? | One thing I think you should make note of, and be careful not to mix, is the definition of African American members of Islam and African American members of the Nation of Islam (NOI). While superficially the two look similar, the differences are vast and important. The NOI is more responsible for the Black Power and Bl... | [
"Some African Americans follow Islam. Historically, between 15 and 30% of enslaved Africans brought to the Americas were Muslims, but most of these Africans were converted to Christianity during the era of American slavery. During the twentieth century, some African Americans converted to Islam, mainly through the ... |
why can't you pay for gift cards with a credit card? | At some stores, the 2-3% bank charge on a credit card transaction isn't worth it. Let's say you buy a $100 gift card with your credit card, the store only gets $97.50. That's losing $2.50 up front, and usually the reason you can't get cash for unused gift card balances.
That said, I bought several as gifts this week... | [
"VISA, MasterCard and American Express gift cards are initially funded by a credit card or bank account, after which the funding account and gift card are not connected to one another. Once the predetermined funds are consumed, the card number expires. A gift of a gift card, maybe in an attractive wrapper, may be s... |
To what extent was Congress's declaration of war on Germany in 1917 a reflection of American public opinion at the time? | This is a huge question; American public opinion changed quite often over the period 1914-1917 in reaction to such things as the Atlantic U-Boat campaign, the Zimmerman Telegraph, the Dublin Uprisings, and other events. The American public at this time - like at any time - was hardly a single mass, either, and that def... | [
"Kendrick Clements claims bureaucratic decision-making was one of the main sources pushing the United States to declaring war on Germany and aligning itself with the Allies. He cites the State Department's demand that Germany's submarines obey outdated 18th century sailing laws as one of the first missteps by the U... |
Alvin C. York | The Tennessee State Museum in Nashville used to have a display on York- including the old Sharps and Hankins rifle he hunted with as a boy. There's also some York stuff at the [TN State Archives](_URL_0_)
Myself, I'd prefer a trip to Jamestown over Nashville, but that looks like a better place to start. | [
"He also contributed to many other societies and charitable institutions both while he lived and through his estate. He gave his native town of Simsbury, Connecticut US$1000 to aid the poor. Among his other philanthropic activities was the creation of the Anson G. Phelps lecture series on early American history at ... |
what is a motif in music? | Your motif is part of music that's repeated to invoke a specific emotion or feeling in a musical piece.
I'm some styles of music a motif will come back always the same to create familiarity, In other pieces a motif can change a little bit every time it comes back so the motif develops like a character in a story. | [
"A motif thematically associated with a person, place, or idea is called a leitmotif. Occasionally such a motif is a musical cryptogram of the name involved. A head-motif (German: Kopfmotiv) is a musical idea at the opening of a set of movements which serves to unite those movements.\n",
"The motif was used as a ... |
why do astronauts wear white? | To reflect heat.
Although we hear about space being very cold, in fact it is difficult to lose heat in space due to the lack of any substance to transmit the heat to. The only way to get rid of heat is through infra-red radiation, which takes a long time.
The problem is that astronauts generate body heat faster than ... | [
"Pilots and flight crews use several colors of flight suit. NASA crews, for example, wear blue flight suits as a sort of functional dress uniform during training. The orange suits that they wear during launch and re-entry/landing are designed for high visibility, should there be an emergency recovery. White suits a... |
whatever happend to kony2012 and why isnt there something similar for boko haram who's actions have been much worse? | If I recall correctly, there were two main reasons why the Kony 2012 hype quickly died down:
1) People who were actually familiar with the situation spoke up and basically said the Kony issue was no longer relevant / significant anymore and they had no idea why this guy was trying to start the campaign
2) The directo... | [
"By mid-April, Boko Haram had been blamed for nearly 4,000 deaths in 2014. Militants then attacked a school and kidnapped 276 girls, of which 57 escaped, in Chibok. The incident brought international attention on the situation in Nigeria, and Western nations promised to help fight Boko Haram. Negotiations to trade ... |
How did the Vatican respond to the Fascist Italian Government? | The two were in direct conflict almost immediately until they agreed to the Lateran Treaty. They were basically fighting over the power to indoctrinate Italy's youth. The Church also believed that Fascism contradicted their stance on free will, and believed Capitalism (Liberty) was preferable to Fascist Corporatism.
I... | [
"After Mussolini was rescued by the Nazis and installed as leader in Northern Italy, the Vatican feared a Communist takeover, but refused to recognise Mussolini's new state. As Italy lurched towards civil war, the Vatican urged moderation. At Easter 1944, Italian bishops were directed to \"stigmatise every form of ... |
Why does the passage of time change when space is curve? Or, why/how is time so inextricably linked to space? | So let's start with space-like dimensions, since they're more intuitive. What are they? Well they're measurements one can make with a ruler, right? I can point in a direction and say the tv is 3 meters over there, and point in another direction and say the light is 2 meters up there, and so forth. It turns out that all... | [
"In physics, time is the fourth dimension. Physicists argue that spacetime can be understood as a sort of stretchy fabric that bends due to forces such as gravity. In classical physics the future is just a half of the timeline, which is the same for all observers. In special relativity the flow of time is relative ... |
If the Universe were shrunk to something akin to the size of Earth, what would the scale for stars, planets, etc. be? | The radius of the Observable Universe is about [4.3e26 m](_URL_4_). The radius of the Earth is [6.37e6 m](_URL_7_). So, your scale factor is about [1.5e-20](_URL_10_). Everything in the Universe shrinks by that amount and now fits into the size of the Earth.
Some fun numbers:
* Earth itself is now [0.1 picometers](_U... | [
"Finding no star bigger than 200 solar masses, Oey and her colleagues at the University of Michigan at Ann Arbor have found evidence for a size limit in a survey of other clusters within our galaxy and in the nearby satellite galaxy, Magellanic clouds. \"It is not clear whether the size is limited by the physics of... |
why does vasoconstriction lead to better blood flow? | Vasoconstriction does not increase blood *flow*. It increases blood *pressure*. If all things were equal, that would normally increase blood flow. But as you note, making the blood vessels smaller increases the resistance to flow.
If you grab a hose or piece of tubing with liquid flowing through it and squeeze... | [
"Vasodilation is, in essence, the opposite of vasoconstriction. In vasodilation the blood vessels dilate to allow more blood flow. The smooth muscle cells are relaxed to increase the diameter of flow, decreasing the vascular resistance. This is possible due to the direct relationship between the cardiac output, mea... |
why are "girl" pushups so much easier than regular ones? | Think about a spanner. It is much easier to turn a nut if you pull on the spanner at the far end, rather than near the nut. Forces which cause rotational motion are called moments (also called torques), and the distance from the point of rotation matters.
Now when you do a push up the man way (from the feet), your cen... | [
"Push Girls was an American reality television series on the SundanceTV. A sneak peek episode, and original premiere date, aired on April 17, 2012, with the official debut on June 4, 2012. \"Push Girls\" chronicles the lives of four women—Angela Rockwood, Tiphany Adams, Mia Schaikewitz, and Auti Angel—who have been... |
If the gravitational force is transmited at the speed of light, does the earth orbit a 8-minutes-before sun? | There's a subtlety: the gravitational field of the sun is retarded by 8 minutes, but it also encodes information about the sun's velocity, so the Earth is actually orbiting where the sun is "now."
_URL_0_ | [
"In December 2012, a research team in China announced that it had produced measurements of the phase lag of Earth tides during full and new moons which seem to prove that the speed of gravity is equal to the speed of light. This means that if the Sun suddenly disappeared, the Earth would keep orbiting it normally f... |
In Gibbon's The Decline and Fall of the Romans Empire he calculates the population of the Romans world at the time of Claudius to be 120 million people. How accurate is this estimate? | I do not know if he is correct but we must remember that a census of Roman citizens would only include a fraction of the population since a large portion of population were not actually considered citizens. | [
"The population of the city of Rome peaked at possibly more than one million people from the late 1st century to the 3rd century CE and thereafter declined by 400 CE to 700,000-800,000, between 400,000 and 500,000 in 452, and thereafter to a population estimated at only 100,000 in 500 CE, declining still further th... |
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