question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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why does it take so long to exonerate criminals through dna testing if the evidence is right there? | It's a real simple answer. Perhaps you've seen the Shawshank Redemption, everyone claims to be [innocent.](_URL_0_), so there's a plethora of people claiming to be innocent.
Judges, prosecutors and the cops aren't in a hurry to reinvestigate old cases, and find mistakes that they or their coworkers may have made. Plus plenty of new cases, and a backlog of current cases to focus on. So that only leaves lawyers willing to work for free or very little pay.
They comb through the cases to find the cases that seem most likely to win. That takes time, and money. | [
"Overturning a conviction after dozens of appeals and petitions have been denied is notoriously difficult, though prisoners have some options at their disposal. They can still attain freedom if legitimate innocence can be proven. The most common method is by using DNA evidence to disprove a crime that happened befo... |
why does thinking require so much energy? | To add to this question: what is physically happening when we think and where is the energy going? I know our brain has synapses and works with a lot of electrical signals. Does concentrating require more "electrical sparks" to activate more frequently? This is a great question, OP. | [
"Thinking is more than just conceiving ideas and drawing inferences; thinking is also reflection and contemplation. When we take embodied thinking rather than abstract reasoning as a goal for our mind, then we understand that thinking is a transformative act.br The mind will not only deduce, speculate, and com... |
Is it possible to infinitely half the distance between two objects? Is there a point at which objects become so close that if they are moved any closer, they touch? | So electrons don't have a physically defined volume - rather, they are expressed by something called a wavefunction, which encodes all of the quantum information about the electron. However, let's pretend for the moment that they are infinitely small point charges, which is a good approximation of them.
The force exerted by the electron is F=q*q_e/(4pi*e_0*r^2), where q is the charge on your finger (or whatever you're touching it with), q_e is electron charge, e_0 is vacuum permittivity, and r is the distance between your finger and the electron. (Though the charge on your finger is net 0, at localized points, electrons will repel each other and change their dispersion pattern accordingly. Let's pretend they don't, however, and that they act as immovable point charges as well.) Ignoring constants here, we can say that the force is proportional to the inverse square of the radius. So as you approach zero distance, the force required to decrease your distance even more tends towards infinity, so you'll never be able to touch the electron. You could have the entire planet moving at 300000 km/hr focused on the end of a pin and still never be able to touch the electron, though you'd get pretty close. | [
"The distance of closest approach of two objects is the distance between their centers when they are externally tangent. The objects may be geometric shapes or physical particles with well defined boundaries. The distance of closest approach is sometimes referred to as the contact distance.\n",
"For the simplest ... |
how do free games (like fortnite) make profit? especially for a 3d game which employs alot of artists, developers, etc. how do they pay all of these people and still earn enough money to keep the company moving forward? | Microtransactions. They offer a bunch of stuff in game that you can buy. A lot of mobile games get ad revenue as well, but it's mostly in game purchases. | [
"Since \"Unreal Tournament\" is being in part created by a community of volunteers, the game will be completely free when it is released. Epic Games stressed the point that it will be just free not free-to-play, meaning there will not be microtransactions or gameplay-affecting items. To pay for the game, it will ev... |
Why does the word "queue" contain 4 vowels, yet only utilizes the sound of the first letter? | ['Queue' comes from 'cauda'](_URL_0_), the Latin word meaning 'tail'. The French took it (originally spelled 'cue') and made the word we see today. In the 1500's, Middle English used it metaphorically to talk about a line of people dancing (like a tail, get it?). A couple hundred years later, we see it used the way we see it today.
Why all the letters? Because everyone hates the letter 'C'. It's confusing, it changes based on the letter ahead of it. **C**ertainly and **c**uriously **c**ryptic, these **c**hanges.
Moving on. There are five vowels in the Latin alphabet, and two of them aren't like the others: 'E' and 'I'. They're weak. Cerebral, cinch. 'A', 'O' and 'U' are strong. Cart, cold, culvert. See what happens to the confusing, changing 'C'?
Now let's talk about 'Q'. When Latin stopped using the 'K' (I don't know why), they had one letter for 'U', 'W', and 'V': 'V'. So to distinguish the traditional 'Qu' (Kw-) sound, they used 'Qv'. The French took 'Q' to combat the weak vowels following their C's because they didn't know anything about K's. *Quelle quiche Québécoise?*
Eventually a French fellow heard 'cue' and wrote it down. But what an English speaker would hear as "oo" isn't quite all that the French say. They have 'u' (*rue*), 'eu' (*jeune*), and 'ou' (*tout*). All pronounced slightly differently. The old French people who didn't write much down didn't care all that much about these differences, but eventually more French people started writing more stuff down and they had to distinguish the sounds. 'Cue' sounded more like an 'eu' sound. But now it starts with an 'E' and E's are weak! Time to pull out the 'Qu'.
And that brings us to 'Queu'. So why the final 'E'?
Because grammatical gender! It's a feminine word and feminine words (for the most part) end with an 'E' in French. (*Jeu*, for example, is an 'eu' sound in a masculine noun).
So, because 'u' changed to 'eu', the 'C' changed to 'Qu' because of the Romans. Then, because it's a lady noun, the final 'E' was added.
Q-U-E-U-E.
Boom. | [
"As a rule, 4 letters make up a noun. Nouns have an initial short-sound letter which indicates meaning, usually followed by a long-sound letter which is pronounced long and with a strong accent. The third letter is also usually short-sound, and it indicates the sort of noun divided by meaning, although it can be lo... |
if i have a source of light like a flashlight in a dark room, how can i see things that, when the light beam bounces off them, it doesn't reach my eyes? | imagine that you are in a room in witch the floor is all covered in rocks. random rocks of all sizes and shapes. if you vertically drop a tennis ball it will not bounce vertically because the floor wasn't smooth.
on the micro scale the wall, too, isn't smooth and the photons will scatter in every direction once they hit said wall. some of these "stray" photos will reach your eyes and that's why you can see the table. | [
"Rays of light travel in straight lines and change when they are reflected and partly absorbed by an object, retaining information about the color and brightness of the surface of that object. Lit objects reflect rays of light in all directions. A small enough opening in a screen only lets through rays that travel ... |
why does spraying on aftershave stop little cuts from bleeding? | Alcohol irritates open blood vessels and causes them to constrict. It also causes your skin to contract and pinch off the bleeders. | [
"If the bleeding is too copious, the chemical cautery may not be effective, as the flowing blood can wash away the chemical before it can react with the tissue. It can also be accidentally spread to undesirable locations where it can cause skin staining and tissue burns. This is especially important, as it is often... |
does a company forcing you to change your password every 6 months (for example) actually increase security? as far as i'm concerned it just causes me to forget my password. | Studies have shown that mandatory password changes actually reduce security because people tend to either use simpler passwords that are easier to remember, or they just write them down in easy to find places.
Edit: since so many people have asked.
_URL_0_
Edit: don't know how this turned into my highest karma post. I went from 1.3k this morning, to this!! Lol | [
"Inc. Magazine cybersecurity columnist, Joseph Steinberg, however, advised people not to change their passwords, stating that \"the current risk is much smaller than the price to be paid in increased 'cybersecurity fatigue' leading to much bigger problems in the future.\"\n",
"Some policies require users to chang... |
could a canadian billionaire just give 1 million to every person in canada, cure poverty, and still be filthy stinkin' rich or would it shatter the economy? | Since the population of Canada is just over 35 million people, you would need at least 35 trillion dollars to do this. This is more money than anyone has. It's more than double the GNP of the entire United States in 2011. So, yes this would probably wreak havoc on the world economy. | [
"The wealthiest Canadian of his day, Nova Scotia-born financial wizard Izaak Walton Killam and his wife Dorothy donated a large part of their fortune to supporting the arts, education and sciences in Canada. Established in 1968, the Canadian International Development Agency is responsible for administering the bulk... |
Why does being out in the sun (heat) make me thirsty even though I do not sweat? | You are still sweating. The sweat is just evaporating. | [
"Physical activity in extremely hot weather should be avoided. If a person starts to experience over heating, and symptoms of heat syncope, they should move or be moved to a shaded or cool area. It is also recommended to avoid alcoholic beverages in hot weather, because they cause dehydration which may worsen sympt... |
if police do the most vehicle chasing, why don't they have the fastest cars? | Car chases are way less than 1% of what we do. The Crown Victoria Police Package only has 240 horsepower. For comparison a new toyota minivan has 266 horsepower. Our cars are way more than just a pursuit vehicle, I hate when they are called "pursuit rated" because that seems to imply thats what its made for. Pursuits are so extremely dangerous, its probably a good thing we only have that 240 HP. I want to catch every bad guy out there, but most of the bad guys realize that the more dangerous their driving conduct, the faster we will end up calling off the chase. My last pursuit was against a stolen Audi S4, that thing was way faster than my CVPI. Funny thing is, I was able to keep on him being he had no idea how to take a corner, and believe me, the crown vic cant handle for s***.
The new Ford Taurus interceptors are alright, our dept has the front wheel drive(sigh) V6 version. They have 289 horses, and they get up and go just fine. Thing is, I will use that power for getting to medicals, domestics, and other hot calls god knows how many times more than just a handful of pursuits of vehicles.
| [
"Road policing units, or more informally known as traffic cars, are faster police vehicles used by specialist officers, tasked with conducting high speed pursuits and responding to major traffic accidents. Traffic cars are often estate cars or SUVs that can carry additional equipment, such as traffic cones, signs t... |
why didn't the usaf intervene during the battle of mogadishu? | Because conducting airstrikes in the middle of an extremely crowded urban area would have been an absolute PR nightmare and jeopardized the entire mission there. Bear in mind that at the time it wasn't at all clear that they'd soon be withdrawing altogether, so outraging the entire population of Somalia wouldn't have been done lightly. | [
"On the next day, US air support was withdrawn to take part in the Battle of Fallujah. ISIL recaptured the airbase, pushed the rebels back from the outskirts of Abu Kamal, and attacked the supply lines of the NSA through the empty desert. ISIL fighters encircled the rebels in a surprise ambush. They inflicted heavy... |
How did British troops get to France and have the time to dig trenches in WWI? | The British Expeditionary Force arrived in France by boat, arriving shortly after Britain's declaration of war on Germany. Britain declared war on Germany on 4 August 1914, General Sir John French crossed to France on 14 August with detachments of the BEF, disembarking at the Channel port of Boulogne. French then and indicated that the BEF would be ready to begin operations against German forces by 24 August.
The British, nor any other belligerent on the Western Front, were given time to dig in and construct their trench networks. Trenches were dug hurriedly and in an ad-hoc manner (at least initially) and occurred organically as a direct result of the weapons technology of the time. The destructive capabilities of artillery and the threat posed by machine guns meant that the safest place to be was below ground level. The first trenches started as individual foxholes, dug to protect an individual soldier. In order to move around safely, those holes were expanded, deepened and connected, eventually creating connected networks of sub-ground level earthworks. One side might do this first and, unable to reach these new positions, the other side would do the same rather then withdraw and yield ground to the enemy. Overtime, trench systems were improved upon, expanded and made more elaborate. | [
"On land, the German army attempted to capture Channel ports in the Race to the Sea but although the trenches are often said to have stretched \"from the frontier of Switzerland to the English Channel\", they reached the coast at the North Sea. Much of the British war effort in Flanders was a bloody but successful ... |
Is there any truth to the whole "Lose one sense and the others become better"? | I'll have to look up citation, but there is some developmental biology to support this. If you never you use a sense, that area of the brain is not fully utilized. It has also been found that these areas of the brain can change function. Studies on individuals with early onset blindness often show other senses active in the area of the brain usually reserved for sight.
Do they become super senses? Probably not, but it does show that brain functions can have flexible regions in the brain. | [
"It appears as though individuals with right hemisphere damage maintain their real world knowledge and their mental scripts of what the world is like and what to expect from common scenarios, they just can’t translate it when they see it. Despite this, right hemisphere damage can lead to deficits in discourse abili... |
duty free shops | You have a customer who wants to buy, say, some alcohol which they will drink in their destination country after their journey. If they buy it duty-free in the country they're leaving, it's now a shop in that country making profit on the sale and that country's government collects taxes on that profit instead of the destination's government.
More generally, it's an extension of the principle that you don't charge duty on goods which are exported. If you did, those exported goods would be subject to two lots of duty (the country of origin and the destination), so the exports wouldn't be competitive with local products. It's better to have a large successful exporting business generating lots of jobs and taxable profits than to collect duty on a much smaller volume of exports from a less successful business. | [
"This is a list of duty-free shops. A duty-free shop is a retail outlet that is exempt from the payment of certain local or national taxes and duties, on the requirement that the goods sold will be sold to travelers who will take them out of the country. Which products can be sold duty-free vary by jurisdiction, as... |
if there's anything bad with jehovah witnesses? | Parts of their doctrine cause them to refuse blood transfusions and other medical procedures, and they actively shun former members and people who refuse to convert often cutting people off from their families and friends after they convert if those people do not also convert, or after they have left the faith if their family and friends stay. These are seen a major, cult like behaviors by most people.
Some also take issue with their refusal to serve in the military, police, or salute the flag/do other patriotic activities. But these are much more minor objections that most do not care about, though it did give them a very bad reputation during the world wars.
| [
"Jehovah's Witnesses have received criticism from mainstream Christianity, members of the medical community, former members and commentators regarding their beliefs and practices. The movement has been accused of doctrinal inconsistency and reversals, failed predictions, mistranslation of the Bible, harsh treatment... |
why do things like stone, cloth, wood etc. change colour when it comes into contact with water? | When light hits an interface between two media, it has a chance of scattering. This chance is dependent on the angle of incidence (which we can ignore for simplicity's sake), and the difference in indices of refraction. The bigger the difference, the more scattering there is.
So when light hits the fibers in cloth, it scatters a lot, because fibre has a very different index of refraction than air. However, when the cloth is wet, light goes through 3 media instead of 2. First it hits the air/water interface - and the difference in indices of refraction is smaller here than between cloth and air - then the light hits the water/cloth interface - once again the difference is smaller. So the end result is that there is less total scattering, since each interface involves two media that is more similar in indices of refraction. So less light scatters off these surfaces and back to your eye, so the object appears darker.
This also means that more light is _transmitted through_ the material. This can be readily seen, and exploited, in wet t-shirt cont- uh... Go to bed, it's bed time. | [
"This effect is sometimes called \"wet look\", since wetting wood with water often displays the chatoyancy, albeit only until the wood dries. Certain finishes cause the wood grain to become more pronounced. Oil finishes, epoxy, and shellac can strongly bring out the \"wet look\" effect. When the refractive index of... |
Have there ever been "the good old days?" | The peoples of the America's had much better lives in the century or so before Columbus than those that lived in the century after. Disease brought by europeans (I've read speculation that malaria may have arrived with Columbus) killed as much as 90% (estimates vary) of the pre-contact population. Doesn't seem like a stretch to say suffering from wave after wave of illness would make life worse. | [
"Good old days is a cliché in popular culture. It is used to reference a time considered by the speaker to be better than the current era. It is a form of nostalgia which can reflect homesickness or yearning for long-gone moments.\n",
"\"Best Day of My Life\" is a song by American pop rock band American Authors. ... |
why do some roads sound different than others? | it's a combination of how hard it is and the texture of its surface. age can affect both, especially with different environmental factors in different areas | [
"Residents and motor vehicle users have always been complaining about the loudness of these trucks when using the roads. The loudness of these trucks have caused many hearing problems and disturbances to homes, businesses and the nearby Victoria Hospital located to the road where trucks mainly pass. The noise of th... |
How does a DNA sequence form its output? | Hmm. I took a gander at what other people were saying, I'm not sure they answered your question. I'll give it a walk, and hopefully simply.
DNA is converted to mRNA, in what is called transcription. This is done by matching each DNA base to each mRNA base(except for T/U). The mRNA is then used as a template to select which amino acids are used in a chain, by ribosomes, in a stage called translation. A sequence of amino acids can simply be called a protein, which can have a variety of effects on the body.
The problem that people have found when trying to use DNA as a coding language is that it's bloody *complicated*. Last I heard, were still trying to make a viable protein by hand, which needs appropriate DNA bases to code for it, and proper folding structure on top of that. | [
"Transcription occurs after entry into the cell and is regulated after both the L and P proteins are expressed in replication. This process occurs and accumulates in viroplasms, which are thread like structures that are located in the cytoplasm of infected cells. RNA dependent RNA polymerase or commonly known as Tr... |
Why does my phone camera intensify the brightness of reflections so much? | See the tag? Not an imaging scientist. But some experience with light and perception.
I think what you're noticing is the intrinsic dynamic range limitation of photographic gear. The human eye can take as input a single scene with a wide variation of brightnesses (maybe 10^5 to 10^6 ) and still generate an image for our brain that resolves the scene. Most CCDs, though, can only discern a range of 10^2 or 10^3 , so bright areas saturate the sensor, and the area appears washed out.
TL;DR: It's not actually intensifying the brightness at those spots, it's that your eye adapts to the real scene better than a CCD. | [
"Fresnel reflections from the glass as well as the adhesive can degrade LCD viewability. Reflection is caused by an impedance mismatch between air and the glass. The reflection makes the white brighter, but dilutes black and other colors, which decreases contrast. LOCA suppliers aim to match the refractive index of... |
How did the Islamic Revoloution become Islamic? | The primary reason why the Islamic Revolution became Islamic was that there was a lack of cohesion between the various groups you mentioned, from the paramilitary leftist organizations to ultra-conservative religious groups. Initially these groups only had one objective that tied them together, which was to overthrow Muhammad Reza Pahlavi. After the Shah fled to the U.S., this loosely tied revolution was thrown into disarray, and an inevitable power struggle would soon erupt.
First, the militant wing of the revolution—fundamentalists and leftists—purged the democratic forces. Then the Islamic revolutionaries went to war with the leftist revolutionaries. Finally, the conservative and pragmatist fundamentalist confronted the Radical and Left-leaning fundamentalists. What caused the Islamic revolutionaries to emerge victorious was that the other factions did not have either a coherent ideology or an ideology that had strong public support, or both.
For the democratic platform, its advocates lacked an ideology. Although they called for political reform, it was not the primary concern of the revolution. Inevitably in a social revolution, democracy falls victim to mass mobilization. For the ideologies of the Left, with various brands of communism and socialism, they had a solid plan to implement social and economic change. In the early part of the revolution, the Leftists successfully influenced policies, such as emphasizing the redistribution of wealth and confiscation of property from the rich. The problem was that the Leftist ideology ran against Ayatollah Ruhollah Khomeini and his followers, whom had their own concept of how a revolution should be ran. the general Marxist attitude toward religion as a reactionary force that has no place in a progressive society – and would be incapable of leading a revolution – blinded the Left to Khomeini’s power and potential. Thus, Khomeini was the only one capable of producing an Islamic ideology that could win the Revolution, while the Left fell victim to its blind spots of its own ideology.
For Khomeini to successfully convert his own religious and political agenda into the revolutionary movement, he would need to be a single Islamic ideology that could mobilize the masses and appeal to the revolutionary fervor. Indeed, Khomeini’s works prior to the revolution already established a basis for the masses to support. Khomeini defined Islamic ideology in terms of demanding an Islamic state that would bring about social justice, empowering the poor, and freeing Iran from Western political and cultural influence. This ideology was as much based on a fundamentalist view of Islam as it was on political and economic populism. In short, this had all the elements of Marxism, but Khomeini cleverly disguised it with religious symbol and language of Islam and led by the ulama. As a result, Khomeini was able to outmaneuver the Leftist by taking support away from those groups, crushing it and ending up controlling the revolution.
Sources:
Ali Gheissari and Seyyed Vali Reza Nasr, Democracy in Iran: History and the Quest for Liberty (Oxford: Oxford University Press, 2009).
Moaddel, Mansoor. Class, Politics, and Ideology in the Iranian Revolution. New York: Columbia University Press, 1994. | [
"Conversion to Islam was encouraged by the Umayyad caliphs and Emirs of Córdoba but it was not directly forced. Many Christians converted to Islam to avoid the Jizya tax which they were subjected to as Dhimmis. Conversion to Islam also opened up new horizons to the native Christians, alleviated their social positio... |
why some pills like nitroglycerine need to be desolved under tongue | They don't have to, but for the purposes they're used for, relieving chest pains, the quicker the release of the medication, the better. Sublingual administration (under the tongue) is one of the fastest ways to administer medications outside of establishing an IV or giving an injection. | [
"Caustic chemicals may cause ulceration of the oral mucosa if they are of strong-enough concentration and in contact for a sufficient length of time. The holding of medication in the mouth instead of swallowing it occurs mostly in children, those under psychiatric care, or simply because of a lack of understanding.... |
why isn't space always full of light? | It is very full of light. Problem is that you only see the light traveling towards your eye in front of you. There is a ton of light moving right in front of your nose that you can't see because it isn't going into your eye. | [
"Golas posits there is no such thing as empty space. What is called space is actually a vital \"substance\" generated by living beings who are highly intelligent, identical and equal. They are quite tangible yet they are invisible to our senses and our instruments except in their effect on energy/matter. Golas sugg... |
the patterns seen from lights with glasses off. | Behind your pupil and iris of your eye, there is a clear disk-like structure called the crystalline lens. This lens is connected to muscles that stretches the lens so that we can change our focus from far away to close.
On both sides of the crystalline lens at the center, there is a Y-shaped suture/line that forms as the lens develops. This can form an asterisk-like or other shapes: _URL_0_
Normally, if you have normal vision or are wearing glasses, you don't see these as the light perfectly focuses to a single point on the light sensing back of your eye (retina).
However, since you are nearsighted, without your glasses, most of the light doesn't focus to a point. Nonetheless, some of the light can go through these sutures (which act as a different focusing lens compared to the whole crystalline lens) and focus to a point, forming the patterns you see. Only a small amount of light manages to do this which is why you usually see them easier in darkness. | [
"The pattern is created by placing a very slightly convex curved glass on an optical flat glass. The two pieces of glass make contact only at the center, at other points there is a slight air gap between the two surfaces, increasing with radial distance from the center. The diagram at right shows a small section of... |
how does the wii u manage to stream to two screens without latency and lag? | 1) the processing for the Wii U is inside the console itself, not the remote/controller. The streaming to the TV is (from an electrical engineering standpoint) free.
2) the streaming of visual output from the console to the Wii U remote screen is done via a slightly proprietary H264 codec (similar to what Youtubes etc. use), highly compressed and at low latency (the Wii U being able to decompress it really fast)... aka the screen is updated/rendered on the console part and sent to the remote lickety-split. | [
"Like other emulation software, the Wii Virtual Console enables the user to suspend play of a game at any time. To do this, users simply return to the Wii main menu from the game. Two exceptions to this are the N64 and Neo Geo AES, titles which do not support this feature. The N64 will allow play to be halted by re... |
why does bread stop expanding while it bakes? | Bread expands because the yeast in it is burping out gasses as it eats sugars.
When you cook bread, the yeast dies.
Dead things can't eat.
So the yeast stops eating sugar, thus it stops burping.
The browning happens when it reaches a certain temperature. It's called a maillard reaction.
This Temperature is higher than it takes to kill the yeast.
So the bread will stop growing, and then browns. | [
"The rapid expansion of steam produced during baking leavens the bread, which is as simple as it is unpredictable. Steam-leavening is unpredictable since the steam is not produced until the bread is baked. Steam leavening happens regardless of the raising agents (baking soda, yeast, baking powder, sour dough, beate... |
What is literal potato quality? What is the maximum computing power available through use of a potato as a power source? | I can't believe I am actually going to spend the time to answer this, but it's a legitimate, and actually interesting question:
At first you might make the assumption that a potato, simply by its virtue of being a potato, and not a computer, cannot do calculations of any sort- and you would be right. But if we are talking about the theoretical *power* of a potato to do computational work- that can actually be calculated using [Landauer's Principle](_URL_0_) which asserts that the minimum amount of energy needed to erase a bit of information is 2.85e-21 Joules (2.85 zJ).
Now how much energy is contained in a potato? Well, I can see three ways of looking at this question- in decreasing order of usefulness:
1. The energy contained in a hypothetical potato battery- which, believe it or not, has been [extensively studied](_URL_1_) has been found to be 150 Wh for an untreated standard Irish potato, or: 540,000 J. That's actually quite a bit of energy. An ordinary laptop consumes about 60W, which a potato could (theoretically) power for a little over 2 hours. That's not bad.
2. Now let's assume we have a perfect chip. An ideal chip that is right up against Landauer's Principle. So assuming we have a perfect, ideal computer powered by a potato it could theoretically perform **1.895e26 floating point operations** or roughly the computing power (3 Tflops/s) of a GeForce GTX 680 graphics card operating for 2 million years or the computing power of China's Tianhe-2 supercomputer for 186 years. But again, this is assuming a perfect ideal computer.
3. For option 3, we break out the big (see useless) guns. Special relativity. The mass energy equivalence of a standard Irish potato (about one pound) equates to 4.0767e+16 Joules, or 1.4304211e+37 floating point operations, or the computing power of the Tianhe-2 for 1.3744956e+13 years, or the ability to break 1.4304211e+17 RSA encryption keys (pretty much any password ever made in the history of the universe), or the entire computational power of the world in the year 2014 for 70872430515.9 years.
So truly, if we are talking about computing power, there is nothing humble about the humble potato. | [
"Potatoes have phosphoric acid and work well; they are the basis for commercial \"potato clock\" kits. Potato batteries with LED lighting have been proposed for use in poor countries or by off-grid populations. International research begun in 2010 showed that boiling potatoes for eight minutes improves their electr... |
What is the minimum population count for a species to have enough genetic diversity for them to continue existing? | There's something called the 50/500 rule, which is just a basic rule of thumb that is by no means an absolute, but it means that 50 is the minimum effective population size to avoid the effects of inbreeding and 500 is the minimum size to avoid genetic drift. But these numbers refer to the effective pop size, which is a bit of an abstraction that treats the population as homogenous with respect to certain properties, whereas real populations have complex age structures, non-breeding individuals, etc., so the actual population size will be a bit larger than any size specified in "effective population" terms. | [
"There is no unique definition of what is a sufficient population for the continuation of a species, because whether a species survives will depend to some extent on random events. Thus any calculation of a minimum viable population (MVP) will depend on the population projection model used.. A set of random (stocha... |
why do some countries require tourist visas if you're from specific countries? | If you are from a rich and/or friendly country, you a generally considered less likely to cause trouble, and have little trouble getting visas. People from poorer countries are more of a danger to stay illegally, and typically have to show that is not the case to get visas.
International relations play a role, too. After 9/11, the US upped their security measures for foreigners. Many countries took offense, and upped their entrance requirements for US citizens.
> And is the point of the visa to take care of the tourist load on the country's infrastructure?
Usually not. Tourist are a net economic plus, most countries want as many as possible.
What they don't want is criminals and people who enter as tourist but plan to stay indefinitely and work illegally.
| [
"Some countries—such as those in the Schengen Area—have agreements with other countries allowing each other's citizens to travel between them without visas. The World Tourism Organization announced that the number of tourists requiring a visa before travelling was at its lowest level ever in 2015.\n",
"Not only d... |
why are cherry blossom trees different in germany from the ones in japan although they come from the same source? | In Washington, Japan sent 12 different species of cherry trees [[ref](_URL_0_ )].
It's unclear what species was planted in the location you're looking at, but the notion that all Japanese cherry trees are the same is mistaken. | [
"Cherry trees have been used in Korea for a long time. It has been used in making bows and woodblocks(Palman Daejanggyeong). According to tradition, monks used wood from silver magnolias, white birches and cherry trees from the Southern coast of the peninsula. The origins of cherry blossoms in South Korea is conten... |
Is it possible to use sound waves to shape or mold physical material? | There's [ultrasonic plastic welding](_URL_0_) and [sonication](_URL_1_). And when pouring concrete, a heavy-duty vibrator (see _URL_3_ ) is used so that the concrete penetrates into crevices. Aaaaand, [ultrasonic humidifiers](_URL_2_). | [
"Sound waves have been successfully used in a device fabricated by two George Mason University senior engineering students, Viet Tran and Seth Robertson, but the procedure is still awaiting a patent (2015).\n",
"Sometimes sound waves at ultrasonic frequencies can be used to levitate objects, thus creating no soun... |
how come the electricity doesn't conduct through the person getting tased to the people supporting him during taster training? | Elektricity is lazy and always takes thé shortest route back. Meaning from pin 1 of the taser to pin 2 of the taser | [
"TFU officers also have the X26 Taser available for deployment as another less lethal option. The Taser operates by discharging two barbs, which attach to the clothing, or penetrate the skin of the person. This creates a circuit through which 50000 volts of electricity is passed causing temporary incapacitation.\n"... |
Questions about a solar array that would be big enough to power the US. | We must be careful to use precise terminology here. It is a 10,000 mile^2 array, or (100 mile)^2.
[Here's](_URL_0_) an article about it (from a political slant), with links to scientific articles and quotes from the folks who published the original article.
There are no plans to build an array that large that I know of. | [
"If the solar cells could be produced on a large scale and be cost effective then entire power stations could be built in order to provide power to the electrical grids. With a reduction in size, they could be implemented on both commercial and residential buildings with a much smaller footprint. They might not eve... |
how does a venus flytrap work? | It responds to stimulation of hairs inside its trap, which causes it to close (the signal is transmitted via an action potential, similar to nerves in animals). This step can be triggered by any direct contact. I used to have one in a pot that you could poke with a stick & cause it to snap shut. [Here's a gif of someone using a skewer to do so.](_URL_0_)
However, the digestion process only takes place if the hairs are stimulated once the trap has already closed, so this requires something alive & moving to continue to stimulate it, so the wind or a leaf probably wouldn't work in most cases.
These functions don't require a brain, as they're more like reflexes than conscious actions. The plant doesn't choose to close it's traps, it just responds to stimuli.
| [
"The Venus flytrap is a carnivorous plant that catches its prey with a trapping structure formed by the terminal portion of each of the plant's leaves, which is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap prepares to close, snapping s... |
why is it typical to see different punt formations in college versus the nfl? | There are different rules for the "ineligible player downfield" penalty. In the NFL, only the players at the side of the formation, known as gunners, are allowed to run toward the punt returner as soon as the ball is snapped. All the people crouching along the line of scrimmage can't go more than a yard forward until the ball is kicked.
Under NCAA rules, the linemen can run toward the punt returner right after the snap. As a result, some of the linemen take advantage of this and run forward after the snap. The players near the punter in the "shield punt" formation can block any defender who managed to get past the offensive line.
So, to answer your question, NFL rules make it so the punting team probably needs to use gunners on the sides of the field, while NCAA rules allow the linemen to do the running. | [
"The short punt formation is an older formation on both offense and defense in American football, popular when scoring was harder and a good punt was itself an offensive weapon. In times when punting on third down was fairly common, teams would line up in the short punt formation and offer the triple threat of punt... |
how does thermogenesis in the body work when eating? | Depends what kind of food. That’s why eating too many eggs won’t cause weight gain as easily as eating too many cookies. | [
"Thermogenesis is the process of heat production in organisms. It occurs in all warm-blooded animals, and also in a few species of thermogenic plants such as the Eastern skunk cabbage, the Voodoo lily, and the giant water lilies of the genus \"Victoria\". The lodgepole pine dwarf mistletoe, \"Arceuthobium americanu... |
What were the events that led to slavery becoming a thing of race in the U.S? | From the European perspective, or at least the English, the emergence of a racially defined slave system depended on three factors: new understandings of personhood and rights in industrializing England; a high land-to-labor ratio in the Americas; and, the fragility of labor relations between planters and laborers. (While Native Americans did make up a share of enslaved peoples in the British New World, their use was not widespread, so I'm confining my answer to Euro-indentures and African slaves.)
1. Per John Thornton, a consensus emerged in England and the New World that indenturing whites was antithetical to nascent beliefs about what we might call human rights. Others, including Eric Williams, have argued that the process of replacing white indentures with black slaves rested, too, on the need for laborers in the early English textile mills. Therefore, African laborers replaced British laborers due to a sudden need for white laborers in industrializing England.
2. The US has, and continues to have, a high land-to-labor ratio. What I mean by a "high land-to-labor ratio" is that British planters faced simultaneously an abundance of land and few available laborers to actually farm said land. As planters and indentures slowly eroded the indenture system, planters sought out new sources of labor. The growing slave trade on the West African coast was, in many ways, a logical solution to the problem of populating the workforce in the New World.
3. Another explanation, advanced by Edmund Morgan, is that planters popularized white privilege by extending political, legal, and economic rights to poor whites in what would become the U.S. According to Morgan, planters practiced a plan of divide-and-conquer following Bacon's Rebellion. By expanding protections for white indentures, for example (the logic goes), planters created both a sense of difference between African- and Euro-Americans, and set the context for eventually replacing the indenture system with that of chattel slavery. | [
"Slavery was a major point of contention in the United States for the first-half of the 19th century. During that period, the United States saw several slave revolts, including German Coast Uprising in 1811, Nat Turner's slave rebellion in 1831, the 1842 Slave Revolt in the Cherokee Nation, and John Brown raid in 1... |
Does pushing on an object propagate through the object at its speed of sound? | Yes, it does. Any disturbance at one end of a body will not be instantly noticeable at the other end, but travel through it at the speed of sound. It is important that the speed of sound can be pretty fast in solids, up to 12'000 m/s in diamonds. [Here is a useful list](_URL_0_) | [
"Shock is formed due to coalescence of various small pressure pulses. Sound waves are pressure waves and it is at the speed of the sound wave the disturbances are \"communicated\" in the medium. When an object is moving in a flow field the object sends out disturbances which propagate at the speed of sound and \"ad... |
why does water vapour come off of stuff that you pull out of the freezer? | The frozen item chills the air around it. This causes the water vapour already in the air to precipitate out as fog. So, the vapour isn't coming off the item, it's coming from the air around it. | [
"Freeze spray (cold spray or vapocoolant) is a type of aerosol spray product containing a liquified gas used for rapidly cooling surfaces, in medical and industrial applications. It is usually sold in hand-held spray cans. It may consist of various substances, which produce different temperatures, depending on the ... |
What was considered "junk food" in the early 1900's? | [Edit: Sorry, I've written a pretty disorganized post here, and I've played with it a bit; apologies for the messiness.]
I can answer this for Britain; other Anglophone and European countries followed some of the same patterns, but with important variations that are beyond my knowledge. This answer does require some consideration of just what "junk food" actually is, because the early twentieth century existed in a world that still saw the problem of food as one of scarcity, not abundance.
Our current definition of junk food is based on abundance. "Junk" food now is such because it will make you fat; say, burgers and fries or fish and chips. Modern medical knowledge tells us that fatty, salty, fried foods, or foods with a lot of sugar like soda or candy, are bad for our health, leading to obesity, diabetes, and heart disease. They're a "guilty pleasure" because they taste good but are unhealthy--but the real "problem" of those foods is that we eat too much.
In the early twentieth century, that kind of cultural-medical discourse just doesn't exist. People eating too much is just not seen as a problem (socially--individuals certainly could do it). The wealthy might eat extravagant, multi-course meals that we would see as ridiculously opulent and unhealthy because of the amount of fat, salt, red meat, and so on; however, you just don't see contemporary physicians looking at those things are problems socially, because that was basically fine *for the wealthy*, because they could afford it. If poor people were eating that kind of thing, then that would be a problem, but it would be a problem because it was wasteful. Instead, the problem then was people eating too little. And in Britain in the early 20th century, the people doing most of the looking and judging of this were not necessarily physicians, but middle-class "reformers" looking at the working class. For them, the "junk food" of the day was white bread and tea--sort of a "guilty pleasure," but not because they worried about poor people getting too fat, but because they claimed that such a diet was wasteful.
The globalization of Britain's food supply chain in the second half of the nineteenth century, combined with a revolution of flour milling technology in the 1870s and 1880s meant that by about 1900, white bread was available for everyone. Prior to about 1870 or 1880, people certainly ate white bread, but it was not as ubiquitous as it was by the end of the century, and it was frequently "white" only thanks to adulteration with alum, a bleaching agent (that's its own story, but alum went from nearly universal or practically gone between about 1850 and 1890). Tea underwent a similar pattern slightly earlier in the nineteenth century: the preserve of the wealthy in the seventeenth century, it became a common luxury in the eighteenth century, and a universal necessity across the nineteenth century. In part, this was possible through the expansion of cultivation in India and Ceylon, across the nineteenth century, which obviously increased the supply and drove down prices. By 1900, white bread and tea (and sugar) were universally available, and cheaper than ever across Britain.
Middle-class reformers in the late nineteenth and early twentieth centuries were concerned with working-class diets, and there were many who conducted surveys of what working people ate. They found that many subsisted on a diet of white bread and tea, working men eating as much as a pound of white bread per day, and tea the preferred drink. How common this actually was is difficult to determine; certainly after 1850, there was a rise in real wages across Britain, and a much wider variety of food products became available at lower and lower prices. These included imported tinned or frozen meats, processed food like tinned fruit, bottled sauces, and prepackaged biscuits and sweets, and even some fresh fruit. A variety of local fruits and vegetables had also been available in British cities, including cabbages, kale, and root vegetables like potatoes and carrots. With this variety available and with the increase in real wages, we know that by 1900 the British working class was eating considerably better than it had from, say, 1830 to 1860. Still, there was likely a subset of the very poor who continued to scrape by on the very cheapest foods available, white bread and tea. These were families that probably couldn't afford meat more than one a week or even once a month, couldn't afford the fuel to cook very much, and very likely had little time away from working to do so anyway. Bread, especially freshly-baked bread, and tea were warm, and provided enough energy and chemical stimulation to keep them going.
Middle class reformers were horrified by this revelation, but for complex reasons. White bread was not at the time seen as necessarily less healthy than brown bread; in fact, many physicians considered it a far more efficient food, and thereby preferable. The idea that there were micronutrients necessary for health that might not be provided by white bread and tea was certainly there, but it was not a culturally dominant idea until really after World War I. No, the problem with white bread and tea, I would argue, is that they represented poor people eating above their station. White bread and tea had both been traditionally the preserve of the wealthy, and though globalization had pretty much made that consumption pattern obsolete, those cultural ideas continued. Middle class reformers were offended by the poor eating white bread and drinking tea because, to them, the poor shouldn't be wasting their money on them. They should, in the eyes of reformers, eat brown bread or oatmeal, and drink milk--never mind that those products could actually be more expensive, so that white bread and tea was not necessarily an uneconomical choice. At the same time, the middle class thought it was fine for them to eat white bread, because their diets were more diverse.
So, in this way, "junk food" at the time was basically what poor people ate.
The main scholarly texts for this are Christian Petersen, *Bread and the British Economy*; Derek Oddy, *From Plain Fare to Fusion Food*; John Burnett, *Plenty and Want*. If you want more specific references, let me know.
| [
"According to an article in the \"New York Times\", \"Let Us Now Praise the Great Men of Junk Food\", \"The history of junk food is a largely American tale: It has been around for hundreds of years, in many parts of the world, but no one has done a better job inventing so many varieties of it, branding it, mass-pro... |
Does the infinite multiverse theory assume that in addition to every possible scenario existing, every impossible scenario also exists? | The short answer is no. If a particular scenario is by definition *impossible* then it *cannot* come about. However, given enough time, *improbable*, but still possible, events can take place.
But to understand why this is the case it would help to review the argument you are proposing more fully.
No doubt, the model you propose is some variant of a universe infinite in time and space, which can be subdivided into pockets which are independent of each other and limited in volume. The ensemble of particles within each 'pocket' is either in thermal equilibrium or near thermal equilibrium, characterised by a finite temperature.
Now, since we have a set of 'universe', i.e. collection of particles (let us assume that they are classical microscopic partiucles, for convenience) confined in a particular volume, there is a total number of arrangements that these particles can occupy within that given volume. This set of configurations is the phase space for each universe.
Now, consider the universe under time evolution. With time, the universe will either evolve into a periodic pattern (i.e. when it begins at some state, it will inevitably return to that state after a finite peroid of time, and as the rules of time evolution are deterministic, or at least preserve the distinctions between different states, it will continue to follow this pattern with some period) or it will not, i.e. it will continue jumping from one state to the next. However in the second case it is bound to occupy every region of the phase space; eventually it will return to a state arbitrarily close to one it has already occupied. In infinite time this will happen infinitely often.
This whole story is an outline of the concept of [Poincaré recurrence](_URL_2_).
However, it is important to stress that even the improbable states must be part of the phase space of the system and that the rules of time evolution must connect these states to the somewhat more probble ones. So truly *impossible* states, states that violate the laws of physics, will never occur.
I could go on to talk about how this concepts aaplies to our universe, [Boltzmann brains](_URL_0_) and associated paradoxes, and list the different [multiverse hypotheses](_URL_1_) but I think this is enough for now to kickstart some discussion on the topic. Essentially, givent a finite 'volume' of possible states and infinite time or space, and chaotic time evolution, every permutation is bound to arise infinitely often.
| [
"The Multiverse hypothesis proposes the existence of many universes with different physical constants, some of which are hospitable to intelligent life (see multiverse: anthropic principle). Because we are intelligent beings, it is unsurprising that we find ourselves in a hospitable universe if there is such a mult... |
why if i sleep with the fan on i wake up with a sore throat? | I think its because you keep air circulating that it will become dry, as a result when you breathe in it will dry out your throat, making it sore in the mornings, take a glass of water to bed with you for just before you fall asleep and as you wake up, it will make a difference, alternatively turn the fan off and sleep with fewer sheets. | [
"It is alleged that fans may cause asphyxiation by oxygen displacement and carbon dioxide intoxication. In the process of human respiration, inhaled fresh air is exhaled with a lower concentration of oxygen gas (O) and higher concentration of carbon dioxide gas (CO), causing a gradual reduction of O and buildup of ... |
How frequently were handgrenades used in both World Wars? | Hand Grenades were used *constantly* in combat, and unlike in the movies, are a necessity both for offensive and defensive combat.
There are various mentions in WWII of 'Hand Grenade Duels' and sharp exchanges would often occur between infantry in urban, room to room and hill-side engagements. In one famous incident at Verrieres Ridge in Normandy, German and Canadian infantry engaged in a hand grenade duel within whispering distance of one another; as the Canadians occupied one side of a ridge, and the Germans the other.
The phrase 'grenade duel' seems to come up most often in scenarios of close fighting; such as the pacific.
Two excerpts from the MoH citations of Joseph Barry and Bill Foster, respectively -admittedly extraordinary circumstances, but the best I could get on short notice:
> When infiltrating Japanese soldiers launched a surprise attack shortly after midnight in an attempt to overrun his position, he engaged in a pitched hand grenade duel, returning the dangerous weapons with prompt and deadly accuracy until an enemy grenade landed in the foxhole
The key thing to seize on here is that the Japanese both used them offensively, and that Barry used them defensively; often hurling the enemy's grenades back. He was awarded his medal posthumously.
> Dug in with another Marine on the point of the perimeter defense after waging a furious assault against a strongly fortified Japanese position, Private First Class Foster and comrade engaged in a fierce hand grenade duel with infiltrating enemy soldiers.
More of the same. Once at close range, and in low visibility terrain, a hand grenade is more valuable than a rifle - hence their frequent use by infiltrating Japanese soldiers. Foster would smother a grenade with his body and be posthumously awarded his medal. Fortifications, fieldworks of even a minor nature, and perimeter defenses are all things that often need to be eliminated through maneuver; not just firepower. This means attackers have to get close, hence the primacy of grenades in these two excerpts.
These are perhaps two extraordinary circumstances, but if one reads enough AARs from enough unit histories the patterns I briefly pointed out here will show themselves time and again for the employment of hand-grenades throughout both World Wars. To be pointed; would *you* storm a trenchline and not use the most potent weapon given you? As usual, Hollywood gets it (mostly) wrong. | [
"The Armed Occupation Act, passed in 1842, encouraged further settlement of Pinellas, like all of Florida, by offering 160 acres (0.65 km²) to anyone who would bear arms and cultivate the land. Pioneer families like the Booths, the Coachmans, the Marstons, and the McMullens established homesteads in the area in the... |
i've noticed that most cultures in the world have loose and flowing clothes, how come we've come to accept "western" clothing | Colonialism. Specifically British colonialism. | [
"Although these clothes are often donated by organizations in belief that people in rural and poor areas will be obtaining them first, the people who live in the cities get the clothing first. Since urban areas are full of fast and changing lifestyles, they are able to adapt to the change in cultures, such as chang... |
what is an electric boogaloo? | It's a reference to the 80's movie *Breakin' 2: Electric Boogaloo*, the sequel to the breakdancing film *Breakin'*. The was widely considered to be awful, and the subtitle "Electric Boogaloo" is now used by people to denote a needless or subpar sequel that probably shouldn't have been made. *The Passion of the Christ 2: Electric Boogaloo*, would be an example.
The actual term "Electric Boogaloo" was a type of funk/hip\-hop dance featured in the movie. | [
"The Electric Boogaloos are a street dance crew responsible for the spread of popping and electric boogaloo. The name \"Boogaloo\" came from a song called \"Do a Boogaloo\" by James Brown, which was also adapted as a street dance done from Oakland, CA. They were founded by Boogaloo Sam in Fresno, California in 1977... |
How did people in periods like Ancient Greece achieve such muscular and "sculpted" builds without as much knowledge of nutrition and fitness? (I assume they also didn't just "work out" but rather gained their builds by just working? | First you have to take into account that the bodies represented by antique sculptures ([1)](_URL_0_) are representations of an ideal and not the physique of your average ancient greek.
Then, the Greeks (at least the wealthy citizens of the city states) did exercise. Training at the gymnasium was an important part of the citizens life because
1- Aesthetics were considered the outside manifestation of an inside virtu and the sign of a strong will.
2- Physical exercise was a part of the military duty incumbent upon each citizen, as it was required to fight in an hoplitic formation.
3- The gymnasium was a place of physical training, but also socialization and learning. Working out was a part of the basic citizen social life. | [
"Athletes in ancient Greece were advised to consume large quantities of meat and wine. A number of herbal concoctions and tonics have been used by strong men and athletes since ancient times across cultures to try to increase their strength and stamina. In the 1910s, Eugen Sandow, widely considered to be the first ... |
Photons: do they "go on forever," and do they "experience" time? | Photons do not spontaneously decay; if they interact with something they can be absorbed. Time does not pass for photons, but really it doesn't make sense to consider the rest frame of something that is never at rest. | [
"\"Timewave zero\" is a numerological formula that purports to calculate the ebb and flow of \"novelty\", defined as increase over time in the universe's interconnectedness, or organized complexity. Terence McKenna claimed that the universe has a teleological attractor at the end of time that increases interconnect... |
inflation and the age of the universe | Because even though inflation did increase the size of the Universe significantly, it lasted only an extremely short period of time. Or put another way, even though inflation made the Universe many orders of magnitude bigger than when inflation started, it still left the Universe absurdly tiny in comparison to its size today. So when you're calculating the age of the Universe, it's essentially negligible.
Similarly, the Universe increased greatly in size during the next cosmic era, when radiation dominated the expansion. This lasted for about 80,000 years, but because that was such a tiny period of time in comparison to 13.7 billion years, you can ignore it and still get a very good estimate for the age of the Universe. The important eras to consider are the next two, matter domination and dark energy domination, as those each lasted a few billion years. | [
"In physical cosmology the inflationary epoch was the period in the evolution of the early universe when, according to inflation theory, the universe underwent an extremely rapid exponential expansion. This rapid expansion increased the linear dimensions of the early universe by a factor of at least 10 (and possibl... |
Could you use the vacuum of space to create a vacuum on earth that sucks up dust and smaller objects up into space? | Picture the atmosphere around Earth. It is already exposed to the vacuum of space. There is no significant suction that draws out all the air in the atmosphere - that's because gravity is keeping the air down (with the exception of a few of the lighter elements, which unfortunately do escape).
So the answer is no, there will be no continuous suction. If you have a vacuum sealed tube extended in your scenario, once the seal is broken, yes, there will be initial suction as air rushes in to fill the vacuum. However, the air inside the tube will quickly reach the same density gradient as the atmosphere, at which point there will be no longer any suction. In this case, the "suction" that is created comes from _displacing atmospheric air_ as you lower this vacuum-sealed tube onto the surface - not unlike covering one end of the straw and dipping the other end into your drink. When you release your finger the liquid just rushes up, until it is level with the rest of the drink. | [
"Outer space is the closest known approximation to a perfect vacuum. It has effectively no friction, allowing stars, planets, and moons to move freely along their ideal orbits, following the initial formation stage. However, even the deep vacuum of intergalactic space is not devoid of matter, as it contains a few h... |
Is it possible to observe human history if we send telescopes far away enough? | If you're looking at something 10,000 light years away, then yeah, you're seeing it as it was 10,000 years ago. But you would need a *huge* telescope to see details on a planet. | [
"The Mammalluca Observatory located 9 km north of Vicuña, has tourist and education programs. At the Cerro Tololo Inter-American Observatory, only daily tourist visits are possible, the telescopic observation is not possible except for specialists and astronomers. However, at Mamalluca, it is possible to observe us... |
After how many weeks can you easily tell a human embryo from other mammals? | Mammals are a class, the third degree of specification down the taxonomic tree. Past that, humans fall into the primate order. Since embryo development very generally follows taxonomic history, so this is where you could see the first difference. What distinguishes primates from mammals isn’t a razor-thin line, but there’s a few possibilities.
One is the presence of the calcarine sulcus. This separates the primary and secondary visual centers in the brain. It starts out as the calcarine fissure, which can be seen as early as 15 weeks in development. | [
"With obstetric ultrasonography the gestational sac sometimes can be visualized as early as four and a half weeks of gestation (approximately two and a half weeks after ovulation) and the yolk sac at about five weeks' gestation. The embryo can be observed and measured by about five and a half weeks. The heartbeat m... |
why do some sodas (like coke) produce a lot of foam when it's poured into a cup, from say, a can, while other sodas (like sprite) don't produce nearly as much? | the most important factor in how "foamy" a soda acts is which of its ingredients raise or lower surface tension. Aspartame promotes the formation and persistence of bubbles, as do certain preservatives.
The combination of multiple foam-promoting ingredients and circumstance is why Diet Coke reacts so energetically with Mentos candy. | [
"One of the ways foam is created is through dispersion, where a large amount of gas is mixed with a liquid. A more specific method of dispersion involves injecting a gas through a hole in a solid into a liquid. If this process is completed very slowly, then one bubble can be emitted from the orifice at a time as sh... |
Are there currently any leading contenders to explain neutrino oscillation? | > Are there currently any leading contenders to explain neutrino oscillation?
Neutrino oscillation is a natural consequence of neutrino mixing and non-zero neutrino mass.
The weak force interacts with flavour eigenstates. However, particles propagate as their mass eigenstates. Neutrino mixing means that the mass and flavour eigenstates are not aligned: flavour eigenstates are superpositions of mass eigenstates and vice-versa. This mixing is parametrised by the [PMNS matrix](_URL_2_)
A neutrino on creation is a superposition of mass eigenstates, which have different masses so propagate at different velocities.
This means that their interference is time-dependent. ([Maybe this image shows it better.](_URL_3_)) Therefore there is a time-dependent oscillating probability of observing a neutrino in each of the 3 flavour eigenstates. ([See this image for the example of an initial electron neutrino](_URL_1_))
> Also, do they fit into the standard model?
The problem with this is how neutrinos gain mass. The Higgs mechanism requires both left-handed and right-handed versions of fermions in order to give them mass ("handedness" here is chirality). The weak force only couples to left-handed fermions and right-handed antifermions. Since neutrinos only interact with the weak force right-handed antineutrinos and left-handed neutrinos have never been observed.
They might exist as "sterile" neutrinos, or neutrinos and antineutrinos might be the same particle with different chirality (Majorana fermions). There are ongoing experimental efforts testing these two hypotheses.
> If so, how, and why do other fermions not oscillate? (Or do they?)
Quarks also mix and have mass. (The relevant mixing matrix is the [CKM matrix](_URL_0_)) They should in principle oscillate via the same mechanism as neutrinos. However, the strong interaction effectively stops that from happening by constantly collapsing quarks into their mass eigenstates. | [
"Strong evidence for neutrino oscillation came in 1998 from the Super-Kamiokande collaboration in Japan. It produced observations consistent with muon neutrinos (produced in the upper atmosphere by cosmic rays) changing into tau neutrinos within the Earth: Fewer atmospheric neutrinos were detected coming through th... |
how come each language seems to have 10 digits? | The man reason that so-called "Arabic numerals" have risen to prominence in almost every language uses a base-ten counting system, which was originally used with those numerals. Some languages still have their own distinct numeral systems, especially (and perhaps ironically) Arabic, and I believe many of the languages of India, but Arabic numerals are increasingly being used in place of or alongside them.
Why the base ten counting system became so popular is that the Indian mathematicians who invented positional notation and the digit for zero used base ten, and that's how everyone else learned it. Positional notation is vastly superior for doing calculations compared to non-positional notation (Roman Numerals being a prominent surviving example) so uptake was pretty well universal.
Funny enough, even though our numerals are base ten, our languages still reflect the time before base ten became the world standard. Most of Europe once used a base-twelve counting system, which is reflected in languages like English who have special words for "eleven" and "twelve" instead of calling them things like "oneteen" and "twoteen." | [
"In the United States and Canada, ten-digit dialing is the practice of including the area code of a telephone number when dialing to initiate a telephone call. When necessary, a ten-digit number may be prefixed with the trunk code \"1\", which is often referred to as \"11-digit dialing\" or \"national format\".\n",... |
How do (some) natural gas deposits come to contain helium? | Radioactive decay.
An alpha particle is a helium nucleus, and primordial radionuclides inside our planet like uranium and thorium are alpha emitters. Over the years the helium so emitted accumulates, bubbling up and/or getting stuck among natural gas. | [
"All commercial production of helium comes from natural gas. There are two basic types of commercial helium deposits: natural gas produced primarily for the hydrocarbon content, typically containing less than 3 percent helium; and gas with little or no hydrocarbons, produced solely for the helium, which typically m... |
how are pregnancy test never 100% accurate? | So first there is the obvious "I took it too soon." This comes from the fact that the placenta makes human chorionic gonadotropin, which is the hormone detected by the test. If you take it before it is high enough to be detected, the test will fail.
All tests have to pick a line at which above a value is considered positive. The trick is to have it high enough so that you don't get false positives, but not so high that you get false negatives. Now you might think, "but shouldn't it just be positive if the hormone is there and negative if it is not?" But it is not that simple. All tests have background sensitivity that can cause them to be picking up a reading. The trick is to make that threshold high enough so only true positives are picked up.
Since not every person, placenta, and urine sample is 100% the same, we cannot be 100% sure.
Also tests can be defective.
EDIT grammar | [
"The accuracy of a pregnancy test is most closely related to the day of ovulation, not of the act of intercourse or insemination that caused the pregnancy. It is normal for sperm to live up to five days in the fallopian tubes, waiting for ovulation to occur. It could take up to 12 further days for implantation to o... |
high pressure systems and low pressure systems | Hi, I will answer this properly since it hasn't been done so far...
The H and L on a weather map do stand for areas of High and Low pressure. By low pressure they mean the air has a natural tendency to rise due to several possible effects. These effects are normally either intense heating by the sun in tropical or inland regions, causing the air to rise thus reducing air pressure. Or a phenomenon called ''The polar front theory''. It is very complicated to try to explain and has never been fully done, but basically it happens when air mixes around the mid to high latitudes, this forms what you know as warm and cold fronts.
Air that rises releases energy by losing temperature and condensing water vapor (cloud), this fuels bad weather such as storms or in the more normal lesser circumstances cloudy and rainy weather due to the water vapor condensing out of the air.
High pressure systems are the opposite. In these the air has a tendency to descend. This creates more settled weather with air re-absorbing condensed water vapor (cloud) creating clear sky's and light winds. High pressure systems are secondary to low pressure systems, they normally are formed because of a low pressure system.
The air rising out a low pressure system has to go somewhere, it will travel hundreds of kilometers across the earth in the upper atmosphere to then descend far away, creating a High pressure system.
As low pressure systems are generated in predictable areas (the equator due to the suns heating, and around 45 degrees of latitude due to the polar front theory) so are High pressure systems. Here is a link [_URL_0_] that shows how low and high pressure systems control the entire planets weather and climate.
Source: Me (A university meteorology student) | [
"The net force on each ion is generally calculated explicitly at each numerical step. From this, the stress tensor of the system can be calculated and usually is calculated by the numerical package. By varying the convergence criteria, one can either seek a lowest energy structure or a structure that produces a des... |
preferred stock | There's more than 2 attributes to a stock. There's common vs preferred sure, but there's also voting vs non voting, an ones that guarantee a dividend vs those that don't, along with other attributes.
Preferred shares are commonly paired with a clause that guarantees a dividend. The fact that the shares are preferred is what forces the company to pay the garunteed dividend FIRST, before it pays any common shareholder dividends.
Say the company can pay $10,000 in dividends and it has 2 shareholders. One would assume that it would be fair to pay each person $5,000 and that would normally be the case.
But one of the shareholders holds preferred shares that guarantee him a $6,000 dividend that year. So he gets $6,000 and the other guy only gets $4,000.
In a second example, the guarantee states the preferred shareholder should receive $11,000 a year. But only $10,000 in dividends can be paid, so the preferred shareholder gets all of it and the common shareholder gets none. (the remaining amount owing to the preferred shareholder can sometimes roll into the next year).
So basically when it comes time to divide up the total dividend payment a preferred share allows you to take your portion first. If your portion is just an equal share then this preference is meaningless, but if your portion is more than an "equal share" then you are allowed to take your full portion, because you are preferred.
| [
"In America, Series A preferred stock is the first round of stock offered during the seed or early stage round by a portfolio company to the venture capital investor. Series A preferred stock is often convertible into common stock in certain cases such as an Initial public offering (IPO) or the sale of the company.... |
with deepfake voices now sounding almost indistinguishable from human voices, why do computer voices (tts, google maps, etc) still sound like garbage? | Because they're not deep-fake voices.
They're deliberately kept out of the uncanny valley by remaining obviously computerized. That way, nobody gets weirded out by an almost human voice. | [
"Voiceless resonants are rare; they occur as phonemes in only about 5% of the world's languages. Voiceless sonorants tend to be extremely quiet and difficult to recognise, even for those people whose language has them.\n",
"Voice computing has become increasingly significant in modern times, especially with the a... |
how exactly do the pens that claim to have special ink help prevent check fraud? | Without specific details on the pens in question, some guesses will be made.
I will assume the pen is using an ink with a dye that chemically reacts/binds with the paper, leaving a mark that can not be erased. This prevents the value of the check from being altered, as a properly written check would show a different word and numerical value, and could easily be identified as altered, along with preventing the addressee from being changed. | [
"These tests were developed to be used in clinical, organizational, and human resource departments. Some psychologists might still use these tests today for personality assessments or assessments of unconscious motives or feelings. However, the American Psychological Association discourages use of official ink blot... |
problems with cryopreservating humans | > but what are the major problems that keep this technology from being used?
Mainly because we don't have any good way of bringing someone who has been pumped full of antifreeze back to life. Even if we can prevent cells from forming ice crystals and breaking as they expand, turning the person to mush upon thawing, we still have some recently thawed dead person.
Why bother so much when in the best case all you can get is a relatively undamaged corpse? | [
"Cryonics requires unknown future technology to repair or regenerate tissue that is diseased, damaged, or missing. Brain repairs in particular will require analysis at the molecular level. This far-future technology is usually assumed to be nanomedicine based on molecular nanotechnology. Biological repair methods o... |
After the Aztec Empire | Hi, there was a recent post on this subject - you may want to join the conversation here
* [I recently heard that from 1603 onwards Samurai arrived to Mexico to work as guardsmen and mercenaries. How true is this?](_URL_0_) | [
"Prior to the Spanish conquest (1519–1522) most of present-day Mexico formed the Aztec Empire, a Native American empire ruled from Tenochtitlán (present day Mexico City) by a \"tlatoani\" or \"emperor\". The ceremonial feathered headdress or \"quetzalāpanecayōtl\" that was worn by Montezuma II (the last reigning em... |
Will it ever be possible to artificially create petroleum? | It already is possible to make oil, you can either get bacteria to create oils
_URL_1_
or directly make them with heat and carbon dixoide and water.
_URL_0_ | [
"Several firms have successfully created petroleum products in the lab using either solid catalysts or genetically modified microorganisms. As of July, 2008, such firms are producing petroleum products in very small quantities, but hope to increase production over the next few years.\n",
"It may be possible to ma... |
how come i cannot control my brain enough for me to tell it to stop doing things that i dislike (e.g. diabetes, where it tells the beta cells do something that is harmful to my body, pimples, etc.)? | Is this a real question from a 5 year old because I'm having a tough time deciphering the question. If you are asking "why can't i control everything that happens in your body?" then...
Your body is like a car. It's a machine built with parts made to do specific jobs. You have a bit of control over the machine, like the steering wheel, gas pedal, brakes, etc but you don't actually have specific control over the entire engine. It "just works" with the minimal input you give it.
Some things like headlights can turn on themselves when it's dark automatically in case you forget but you could override them and turn off or on if you want.
Sometimes a part breaks, like the speedometer. Even though the car still runs and works, it's really difficult to tell how fast you're driving now. You might get in trouble and get a ticket or even worse, crash if you're not careful. You can try to replace or fix a broken part but sometimes you can't.
Things like acid rain, rocks or salt from the road, or the sun can damage the pretty paint and make it not so shiny. You can't control those things since they are foreign bodies. | [
"The opponents claim they are giving medication to the patient, but there are no brain chemical imbalances to correct in \"mental illness\". Our ability to control ourselves and reason comes from the mind, and the brain is being reduced in size from the psychiatric medications.\n",
"We use medications to adjust a... |
why do orchestras have multiple players with the same instrument? | It amplifies the sound and effect. If you had one person clapping to a beat compared to fifty it would give it alot more umpf ya dig. | [
"Orchestras also play with instrumental soloists in concertos. During concertos, the orchestra plays an accompaniment role to the soloist (e.g., a solo violinist or pianist) and, at times, introduces musical themes or interludes while the soloist is not playing. Orchestras also play during operas, ballets, some mus... |
What will happen when the James Webb Telescope gets hit by a micrometeoroid? | Do you mean micrometeoroid or man-made space junk? The James Webb Telescope will be orbiting at [L2](_URL_0_), which is further than the moon and well away from the cloud of debris orbiting earth. | [
"On November 24, 2011 and October 4, 2012, the space probe's thrusters were fired briefly for two trajectory correction maneuvers that targeted Deep Impact for an encounter with 2002 GT in 2020, possibly within a distance of no more than 400 kilometers. However, funding for the flyby mission was not guaranteed. In ... |
why does taking the derivative of a function give you the slope? | The most useful thing I was ever taught by a math teacher was that if you don’t know if/how something works, try it with simpler numbers. Take the equation y = 6x. Obviously your slope is 6, but how did we get there? You’ll notice that in every main function equation the slope (often referred to as “m” is attached to your x value) take for instance slope-intercept form: y = mx + b and point-slope form: y - y1 = m(x - x1). The expression is always x time slope, so how do you isolate slope? you take out an x from the value by division (dividing by an x will lower your exponent by 1) the part about multiplying by the original exponent is a bit more complicated though. | [
"Much as the derivative of a function of a single variable represents the slope of the tangent to the graph of the function, if at a point formula_2, the gradient of a function of several variables is not the zero vector, it has the direction of greatest increase of the function at formula_2, and its magnitude is t... |
Was there a single point in time where the Indian Removal Act could have been prevented or was it unavoidable? | This is not my field of expertise, but I think I've read enough on the topic to attempt an answer. Somebody more knowledgeable can feel free to correct me if I overlook anything.
There were many single points in time where the Indian Removal Act could have been prevented. The act was very controversial, with many Christian missionaries, lead by Jeremiah Evarts, protesting the act. According to historian John Andrew,
> Evarts' tactics were clear. He planned to organize a phalanx of friendly congressmen to present the case against removal on the floor of the House and Senate, hoping to convince enough Jacksonians that the immorality of removal required them to vote against the Indian Removal Bill. At the same time, he would continue to barrage the public with letters, pamphlets, and articles on the Indian question, along with whatever other information might create a groundswell of public opinion against removal.^1
In Congress, New Jersey Senator Theodore Frelinghuysen made a six hour speech stretched over three days.^2 The Senate passed the Indian Removal Act by a vote of 28 to 19 on 24 April 1830. Tennessee Representative Davy Crockett also argued against the bill (even though it later cost him his seat), and the bill barely passed the House by a vote of 101 to 97 on 26 May.
It's been a few years since I've read the book and I unfortunately don't have a copy, but from what I remember H.W. Brand's *Andrew Jackson: His Life and Times* Jackson truly believed that the Indian Removal Act was inevitable^3 and probably would not have had any reservations when he signed it into law on 28 May.
The problem with trying to pinpoint a single point in time that something could have been changed is that you have entire systems at play, and just one small change could have prevented the Act, but then again, it could have not. You can never really know because it was counterfactual.
Sources:
1. John A. Andrew III, From Revivals to Removal: Jeremiah Evarts, the Cherokee Nation, and the Search for the Soul of America (Athens: University of Georgia Press, 1992), 220.
2. Daniel Walker Howe, What Hath God Wrought: The Transformation of America, 1815–1848 (Oxford: Oxford University Press, 2007), 348-352.
3. [H.W. Brands, Andrew Jackson: His Life and Times.](_URL_0_) | [
"The Indian Removal Act of 1830 established policy that resulted in the complete extinguishment of aboriginal title in Alabama and Mississippi (1832); Florida and Illinois (1833); Georgia, North Carolina, and Tennessee (1835) [the Treaty of New Echota]; Indiana (1840); and Ohio (1842).\n",
"The Indian Removal Act... |
can the brain really change the function of the body's organs? | As far as I'm aware? No.
Your organs are all super specialized, and so are the cells that make them up. You can't turn a liver into a kidney for the same reason you can't turn a banana into an apple, they're different things. Similarly you can't make something that's designed for breathing do something that isn't breathing.
Now, if a kidney fails, the liver might have to work a little harder to filter out toxins, but it's not going to be another kidney, and really the liver isn't going to change, it's just going to work harder.
Your brain can do a whole lot of stuff, but it can't make one thing out of a different thing. | [
"The brain serves as the organic basis of cognition and exerts centralized control over the other organs of the body. The brain is protected by the skull; however, if the brain is damaged, significant impairments in cognition and physiological function or death may occur.\n",
"The currently accepted theory states... |
Soviet pilots in the Korean War | The Soviet pilots were not to overfly any enemy territory, so none were captured, -- look up the location of "Mig Alley".
Also, I read this from certain Chinese source: some of the Soviet pilots were given Chinese or Korean IDs, and they all had to leave any items that can link them to Soviet Union back at home. The plan was that if one Soviet pilot was captured, he would be claimed as a Russian Chinese since there were a few thousand Russian decedents living as Chinese citizen at the time, of course this would be very far-fetched, but as long as UN does not have solid proof...
| [
"The USSR never acknowledged that its pilots ever flew over Korea during the Cold War. Americans who intercepted radio traffic during combat confirmed hearing Russian-speaking voices, but only the Communist Chinese and North Korean combatants took responsibility for the flying. Until the publishing of recent books ... |
what happens as we grow up that makes us stop liking people of this age and instead like people closer to a different age, and why does this not happen for pedophiles? | Morality and social norms keep most people from messing around with people more than a few years younger (for men. Only we really take the hits for being with someone much younger in most situations). Also, since people naturally as they grow up tend to stick by people their own age group (they're more likely to like/think the same as you), you tend to stay away from those who don't fit this.
Now most of the above has generally nothing to do with pedophilia, because it's not like pedophiles go their whole life hanging around with kids. (To quickly make this clear, I mean ACTUAL pedophilia. That means pre-pubescent. If you're talking about a 20 something hooking up with a 15 or 16 year old that actually has its own name separate from pedophilia, because their body and mind are maturing. I really hate when people clump every person below 18 together) Pedophiles have a distorted chemical profile in their brain; they don't see things the way most do, and typically their sexual orientation to certain body types/ages stay that way their whole life, and it's not something they can change without serious help from professionals and mental fortitude. | [
"The social aspect is a significant factor that can cause questioning youth to feel they have an unsafe environment in establishing their sexuality or gender. The need for social acceptance by their peers and other members of society during adolescence gives the individual the feeling of belonging; therefore, the f... |
Was the reading aloud of books/written texts (as opposed to reading silent) a universality in all ancient cultures? (also noneuropean) and if yes; how come ? | Until 15 years ago it was, indeed, widely assumed that all reading in Greco-Roman antiquity was done aloud. This assumption was almost entirely based on the Augustine passage that is cited in your link.
However, a couple of studies published in 1997 refuted this idea, very thoroughly and decisively. [Here's part of a thread](_URL_3_) that goes into details. As far back as we can look, there are many more references to reading that imply silent reading than those that imply reading aloud.
Some of them are as explicit as the Augustine passage. The problem that has kept Augustine at the top of the citation list for so long is that the Greeks in particular routinely used metaphors of "speaking" and "hearing" for what texts say.
Here are the earliest relevant references, all from the fifth century BCE:
* [Euripides, *Hippolytos* 856ff.](_URL_0_) - Theseus opens a letter to "see" what it "speaks" to him; a few lines later (and there's no evidence that he leaves the stage) he cries out at its horrible contents, stating -- using the aural metaphor -- "it shouts, it shouts". At 882 he cries, "I will no longer keep this unspeakable story within my mouth's gate".
* [Euripides, *Iphigeneia at Aulis* 34ff. and 107-108](_URL_1_) - Agamemnon reads and edits a letter repeatedly, but a slave standing next to him still doesn't know its contents.
* [Herodotos 1.123-125](_URL_4_) - Cyrus is alone, so the references to the letter "saying" things and Cyrus "hearing" them are the aural metaphor again; cf. an inscription "speaking" in Hdt. 8.22.
* [Aristophanes, *Knights* 115ff.](_URL_2_) - Nikias gives Demosthenes a bundle of oracles to read, and Demosthenes is so absorbed in reading them that when Nikias asks him what they say, he says "pour me another cup of wine". A few lines later he paraphrases what's in the text without quoting it directly.
So, the short answer to your question is: no, absolutely not. Manguel's discussion (which dates to 1996) is simply out-of-date! | [
"This is a celebrated passage in modern scholarly discussion. The practice of reading to oneself without vocalizing the text was less common in antiquity than it has since become. In a culture that set a high value on oratory and public performances of all kinds, in which the production of books was very labor-inte... |
What's the point in creating new elements? Would anything further in the periodic table be stable? | The point is to learn more about how atomic nuclei work. Some people are not interested in this, some are. Generally there can be practical applications of synthetic isotopes, like in radiation therapy for cancer, or as catalysts in the nuclear industry, but generally not the superheavy ones.
It is thought that there may be an "island of stability" possibly around element 126, but these would likely still be unstable, just more stable than other 100+ elements. | [
"The quest for new elements is usually described using atomic numbers. As of 2010, all elements with atomic numbers 1 to 118 have been observed. Synthesis of new elements is accomplished by bombarding target atoms of heavy elements with ions, such that the sum of the atomic numbers of the target and ion elements eq... |
half life (not the game). 'what' has been covered, can anyone tell me how / why? | Forget about atoms for now.
Fill a shoe box with quarters - let's play a game. You know coins have 50/50 chance of being heads and tails. You put these coins into the box, close the lid, and shake it up. You open the lid, and remove any coins showing heads.
Each time you do that, you'd expect to remove on average half the coins - because there is 50% chance they'll be heads. But wait - if you started with 100 coins, you removed about 50 the first time, then 25, then 13, etc.
But this doesn't result from any coins actually _interacting_ with each other to affect whether they're heads or tails. This is _purely probabilities_. How many coins you actually remove is based on the size of the starting sample - the only thing that's constant is that 50%.
It is the exact same thing with radioactive decay. After one half-life, each and every atom has 50% chance of undergoing decay. They don't need to communicate with each other, or affect each other, to result in this type of behaviour - it arises due to _chance_. | [
"Half-Life 2 (stylized as HλLF-LIFE) is a first-person shooter video game developed and published by Valve Corporation. It is the sequel to 1998's \"Half-Life\" and was released in November 2004 following a five-year $40 million development. During development, a substantial part of the project was leaked and distr... |
how do so many actors/actresses from successful television shows manage to never have to work again? | Maybe theyve moved on from acting. Not all people do one career for their entire life. Especially females, some go and choose to become moms instead of actresses | [
"Almost unheard of from the beginning of television until the 1980s, more and more actors have been placed on \"recurring\" so the production company in charge of making the show doesn't go over-budget. Dwindling viewership and economic downturn have led to all U.S. soaps to placing actors (usually veterans who hav... |
why is finding liquid water on mars such a bigger deal than it being in different forms? | Life as we know it needs liquid water. Finding liquid water outside Earth makes it more likely life or proto-life might have evolved in Mars, and more generally if liquid water is common in our solar system, it might be common around the universe and increases the chances there is life somewhere else. | [
"The Mars Reconnaissance Orbiter's HiRISE instrument has taken many images that strongly suggest that Mars has had a rich history of water-related processes. Many features of Mars appear to be created by large amounts of water. That Mars once possessed large amounts of water was confirmed by isotope studies in a st... |
why do birds such as geese or penguins have teeth on their tongues? what lead to this? | Geese don't have teeth on their tongues. They don't have teeth at all.
Geese have a series of serrated "teeth-like" things on their beaks, which are primarily used to grab and rip meat/fish.
[Here is a young goose chomping on my finger](_URL_0_) it's painless, until they start to tug, at which point they can easily rip the skin and draw blood. Though not at this age as his serrations haven't come in fully. | [
"Birds do not have teeth, relying instead on other means of gripping and macerating their food. Their beaks have a range of sizes and shapes according to their diet and are composed of elongated mandibles. The upper mandible may have a nasofrontal hinge allowing the beak to open wider than would otherwise be possib... |
if the second amendment guarantees the right to keep and bear arms, how are some parts of the usa able to require gun licenses? | The 2nd amendment isn't specific. For the same reason that not all speech is free (like perjury, speech that endangers people, etc).
All it says is that in order to maintain a well regulated militia (the well-regulated part can't be ignored), the right to bear arms will not be denied. There is a lot of interpretation that goes on there. SCOTUS leaves it up to the states, for the most part. | [
"In the United States, gun laws are found in a number of federal statutes, enforced by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). The right to keep and bear arms is protected by the Second Amendment to the Constitution, and most state constitutions also guarantee this right. There is some varian... |
how were we able to film the explosions of atomic bombs? i would assume the sheer amount of force would blow any type of camera to dust. | Because your assumption is wrong. Notice how all the footage of atomic detonations is from far away? Thats because they don’t have unlimited blast radius. You can look at one, and film it, from far enough away that the shockwave will dissipate before it hits you.
There is very limited footage from camera’s within the lethal radius, and those cameras were placed in reinforced structures, not directly facing the explosion, rather they are trained on a ‘subject’ to observe as it is destroyed, usually at an angle away from the blast. | [
"Following the use of the atomic bomb in World War II, studies on flash radiography found that field emission flash x-rays, which were previously used to analyze explosions, could simulate radiation from a nuclear bomb. Given this realization, the U.S. military began to prioritize the development of flash x-ray mac... |
why is it when you hear the same sound constantly for hours of the day, when you remove yourself from that environment you can still hear that sound? | Brains adapt in weird ways. Their entire goal is to find changes in the senses.
The brain deal with auditory change by filtering it out when it can predict it. After a while a sound that repeats becomes one big piece of background instead of a second of silence and then a beep. Your eye does this too when you look at something bright and then can see its imprint when you look away. Your muscles do it if you spend a day in the ocean and can feel the waves at night. What your hearing is the brain expecting the sound and filling it in. It's still adjusting for it, so you can still hear it. | [
"Auditory adaptation, as perceptual adaptation with other senses, is the process by which individuals adapt to sounds and noises. As research has shown, as time progresses, individuals tend to adapt to sounds and tend to distinguish them less frequently after a while. Sensory adaptation tends to blend sounds into o... |
Do the limitations of oral sources prevent them from being useful to historians? | Oral sources can be used but they require their own types of source criticism. The same can and must be said of written sources, by the way. All sources are suspect and should never be taken on face value. Each type of source requires its own spectrum of source criticism. An oral history conducted by a reputable oral historian carries a great deal of weight. A community's collective account of its history may be more suspect, especially the further back in time it extends, but it can be taken as bearing its own unique sort of information. At the very least, that community oral history reflects on how members of the community regard themselves.
John Rule, an excellent British historian, looked at the Cornish collections of folklore for evidence embedded within the stories for traditional festival practices in pre- or early-industrial times. See his essay on the topic in his "Essays in Eighteenth and Nineteenth Century Social History" (Clio Publishing: Southampton, 2006). That's not how I use the same texts - I look at these oral sources as evidence of the stories that were told in the nineteenth century, but the example presented by Rule illustrates that the same oral source can be consulted to tease out insights in more than one way. | [
"The Middle East often requires oral history methods of research, mainly because of the relative lack in written and archival history and its emphasis on oral records and traditions. Furthermore, because of its population transfers, refugees and émigrés become suitable objects for oral history research.\n",
"Oral... |
Would a combustion engine like the one in my car work in zero gravity? | On a four stroke or a diesel the only real problem you would have is lubrication. Oil is typically sprayed/splashed onto the bottom of the cylinders and allowed to drip down via gravity or by using the piston as a scraper. It is then collected in the oil pan and recirculated through the engine. After a long enough period most of the oil would probably* be floating around in the cavity that houses the rotating assembly and not in the bottom of the oil pan where it can be collected. I say probably because I don't believe the piston would necessarily send the oil back to the bottom of the pan, and even if it did, gravity wouldn't be there to force it to the low point where the pickup is. This would cause the engine to be oil starved and seize up. Similar problems exist with other oil routines within the motor. This all assumes a there is a pressurized fuel delivery system is in place to move fuel from the tank to the engine.
Some two stroke engines would probably be fine because they are lubricated via the fuel delivery system.
| [
"To further update the car, they changed its polarity from positive to negative earth and fitted an alternator in place of the dynamo. They also devised a new twin pipe exhaust system so that the new engine could breathe more easily.\n",
"Pulse and glide ratio of combustion engine in hybrid vehicles points on it ... |
Why is it that I can safely eat a rare steak but eating undercooked chicken, fish, or pork could land me in the hospital? | Actually fish can be eaten raw, ever heard of sushi?
Pork can also can now be eaten undercooked but it doesn't taste that much better. The main problem used to be a parasite (_URL_0_) which has been pretty much eradicated.
The only bad one is chicken, which can contain salmonella. The reason it does is because salmonella is a pretty resistant bacteria which can make us pretty sick but doesn't affect the chicken (or most birds/reptiles for that matter).
| [
"Beef steak can be cooked to a level of very rare (bleu, a cold raw center), rare, medium rare, medium, medium well, or well done. Pittsburgh rare is charred on the outside. Beef, unlike some other meats, does not need to be cooked through. Food-borne human illnesses are not normally found within a beef steak, thou... |
Do storms move across an area naturally on its own or is it due to the Earth's rotation? What decides its path? | It really depends on the nature of the beast. Hurricanes move by seeking out the lowest pressure, so they naturally move into areas of the highest pressure falls. Storms associated with a cold front (squall lines, etc.) move with the cold front which is created by the circulation around a low pressure system. The rate at which low pressure systems move (which may be a decent explanation of your question as it may relate to winter storms) is related somewhat to Rossby waves propagating against the mean flow.
Rossby waves (_URL_1_) travel from East to West in the N hemisphere (opposite of the mean flow which is W to E in N America), and larger waves move faster than smaller waves. If you think of a massive winter storm it tends to move rather slowly (big synoptic wave) as opposed to a little clipper system (_URL_0_) which zips along.
Rotation does impact the movement of a storm, but it is buried in the other dynamics that impact storm movement and not the overall main cause. | [
"In the tropical latitudes, tropical storms and hurricanes generally move westward with a slight tendency toward the north, under the influence of the \"subtropical ridge\", a high pressure system that usually extends east-west across the subtropics. South of the subtropical ridge, surface easterly winds (blowing f... |
how does my gps request a signal from the gps constellation? is there a limit on how many devices can do so? | your GPS receiver doesn't interface with the GPS satellite. all it does is listen to the GPS satellite broadcast.
basically each GPS satellite is a radio station. there's no limit to how many people can listen to the same station. | [
"For the ranging codes and navigation message to travel from the satellite to the receiver, they must be modulated onto a carrier wave. In the case of the original GPS design, two frequencies are utilized; one at 1575.42 MHz (10.23 MHz × 154) called L1; and a second at 1227.60 MHz (10.23 MHz × 120), called L2.\n",
... |
why does snow in southern state cause complete mayhem? | Snow and dirt are two different terrain.
Snow leads to slippery roads that the usual southern driver is not used to handling that`s why we usually have snow tires specifically to handle driving in the snow better.
Driving in the snow has its own nuances, and it`s a bit hard to explain to someone who has never driven in the snow. | [
"Ground blizzards are common in the American great plains in the wake of snowstorms producing light, dry snowfall that is more easily picked up by strong winds. They are also common in the Canadian Prairies, Siberia, Northern China, and also Arctic and Antarctic regions during seasonal transition periods, such as t... |
I'm now confused after reading some reddit comments: is being gay a choice? | Check out [this thread first](_URL_0_). There are apparent correlations between genetics and prenatal hormonal environment and sexuality.
On the general topic of whether any personal characteristic is strictly a choice or an inheritance, its generally impossible to quantify the degree to which something is genetic or social, largely because its impossible to separate genes from socialization.
In response to your other comment regarding highschool biology, keep in mind that's a simplification. Its hard to separate genes from environment because your genes *affect* your environment (through your appearance, your behaviour) and your environment affects how you develop on a biological level, so the two are constantly affecting each other - they are not fully separable.
| [
"I think to be gay is to be blessed. We have so much freedom, so many choices. This isn't our moment to party or to think we're going to stay young forever … maybe it's our time to find someone to be safe with … to be happy with …\n",
"\"I don't know if I want to answer that or not because it doesn't make any dif... |
Is polio still present in the environment in a place where vaccination has reduced new cases to zero? | The poliovirus is transmitted by poop shedding (you poop it out other people come in contact with or you scratch your buttflaps and go touching all the stuffs spreading it) it is hard to determine what a zero incidence place is given how mobile people are today.
Pakistan and Afghanistan in Asia, and Nigeria, Niger and Chad in Africa, and parts of India still have pretty active forms of one of the 3 types of virus. Unless you are sure there is nobody from that region around that is carrying it herd effect of the vaccines should protect even the few that are not immunized.
Regarding the strategy on making vaccines: there is a huge component of luck. It is a matter of stars aligning (enough people having the disease, actually having a vaccine that works, good cost benefit).
Edit: so sorry guys thought I was in ELI5.
Going to get some refs a polish this turd I wrote.
Here is a brief brush up on polio reservoirs
_URL_1_
Here is how we went from thinking it was eradicated to not really:
_URL_0_
To elaborate on the vaccines and what diseases are eligible for targeting:
For dead vaccines: the microorganism to be targeted have to be passive to chemical/ heat inactivation. Rabies and cholera are examples of this.
Attenuated: the microorganism must have a mechanism to shut down virulence or there must be a member within the curl family that is similar enough but not as bad. Measles and yellow fever are examples.
Toxoid: this one is easy, you are vaccinated with a version of a toxic particle instead of what actually produces it. (Rattle snake anti venom shots are an example of this).
Subunit: well, you could not kill it, you could not shut down virulence, it does produce toxins so throw a carrot at the immune system. Just show a portion of the microorganism to your immune system, enough to produce a reaction, I think hep B falls in this category.
Conjugate: a lot of microorganism are coated with polysaccharides, and your organism isn't great at producing an immune response, so just stick a protein to it and it is made more immunogenic. There is an influenza vaccine made like this if I remember correctly. | [
"Scientific evidence for the effectiveness of large-scale vaccination campaigns is well established. Vaccination campaigns helped eradicate smallpox, which once killed as many as one in seven children in Europe, and have nearly eradicated polio. As a more modest example, infections caused by \"Haemophilus influenza... |
Do humans have any plants as direct ancestors? | Our most common ancestor is probably an organism similar to green algae.
[Here is an interesting article that discusses information on what that organism may have been like.](_URL_0_)
One thing about evolution to keep in mind: Just as we did not evolve from apes, but only shared a common ancestor; the same relationship can be identified between us and all other life on the planet. | [
"Wild ancestors in plants are direct origin of certain plants. Thousands of years ago, humans started to settle and grow crops. This change in human behaviour from nomadic to sedentary marked the start of the domestication process of plants. Creating high-yielding and adaptable plant varieties. A lot of crop plants... |
eli9: why can't a person/organisation/whatever display a picture of the prophet mohammed, but so many people in the world are named mohammed and there not be any backlash from the islamic community? | It's not the word, it's the picture that they object to. | [
"The Quran identifies a number of men as \"Prophets of Islam\" ( \"nabī\"; pl. \"anbiyāʾ\"). Muslims believe such individuals were assigned a special mission by God to guide humanity. Besides Muhammad, this includes prophets such as Abraham (\"Ibrāhīm\"), Moses (\"Mūsā\") and Jesus (\"ʿĪsā\").\n",
"Muslims identi... |
How do microscopic black holes behave? | In a sense, microscopical black-holes are just like very weird scattering-matrices. They form and immediately decay into many soft quanta, so they just act as scattering amplitudes for quantum processes.
The only way we can ever observe micro black holes in experiments is if we have additional dimensions. In this case, the Planck mass is actually lower than what we expect and thus colliding experiments might have enough energy to produce black-holes. But these black-holes will come in something that we can Kaluza-Klein towers, which is a phenomena that happens in higher dimensional scenarios where different levels of excitation in the other dimensions are seen here as "particles with different masses", loosely speaking.
Unfortunately, even if we have black-hole formation, it's quite unlikely that we'll actually be know, as we need to see more than one excitation to tell the difference between a black-hole or a resonance caused by any other particle.
If you're curious, you might want to read this paper: _URL_0_ It's quite accessible and it talks extensively about the phenomenology of black-hole production. | [
"Matter propagating in a curved spacetime is similar to the electromagnetic wave propagation in a curved space and in an in homogeneous metamaterial, as stated in the previous section. Hence a black hole can possibly be simulated using electromagnetic fields and metamaterials. In July 2009 a metamaterial structure ... |
How does soap/shampoo expire? | Is it a medicated shampoo? If so I can tell you how they determined their expiration date. Companies will run stability testing and measure the concentration of the active ingredient (Pyrithione Zinc in something like Head and Shoulders for dandruff control) over periods of time. As long as the active ingredient is within 10% of the labeled quantity the product is good from a pharmaceutical standpoint. Other measures of stability include changes in color, pH, viscosity, smell, consistency, and turbidity. | [
"The soap is then cut in cubes. The cubes of soap are stacked in staggered cylinders to allow maximum air exposure. Once they have dried sufficiently, they are put into a special subterranean chamber to be aged for six months to a year. While it is aging, the soap goes through several chemical changes. The free alk... |
what the proposed extradition bill means for hong kong and mainland chinese citizens (please and thank you) | China and Hong Kong is under a one country, two systems type of structure where Hong Kong could do it's own thing and China wouldnt interfere, which also included criminal prosecutions. Under this proposed bill criminals in Hong Kong can be extradited to China and prosecuted under Chinas laws, which effectively shatters the one country, two systems format. It means nothing for Chinese residents but have huge implications for Hong Kong residents as HKers are now potentially subject to the more restrictive Chinese laws and criminal proceedings. | [
"If enacted, the bill would allow local authorities to detain and extradite people who are wanted in countries or territories that Hong Kong does not have extradition agreements with, including mainland China and Taiwan. Opponents of the legislation fear that it would place Hong Kong residents and visitors under th... |
why does soda "plop" out of the bottle when you pour it? | When the soda is pouring out the volume of space that plop used to be in needs to be replaced by an equally sized plop of air. When the soda is filling the entire opening of the bottle there is no place for the air to get in. Eventually the air gets tired of waiting for its turn and it forces its way in. The soda briefly stop, the air goes in, and then another plop of soda can come out. This process repeats until you lower the angle of your soda bottle so that soda can come out of the bottom half of the opening and air can go into the top half of the opening at the same time. | [
"The conversion of dissolved carbon dioxide to gaseous carbon dioxide forms rapidly expanding gas bubbles in the soda, which pushes the beverage contents out of the container. Gases, in general, are more soluble in liquids at elevated pressures. Carbonated sodas contain elevated levels of carbon dioxide under press... |
why is an action potential called an action potenial? | This isn't really a biology question, more of a physics one. Although I'm not a physicist I can take a shot at answering this, but anyone studying electrostatics (although why would you willingly study this ;)) will be able to define an electric potential better than I can.
A membrane potential is simply the existence of a difference in the electric potential on two sides of a membrane.
What is an electric potential?
An electric potential is just a measurement of work. Specifically, the amount of work it takes to move a unit charge particle from an arbitrary location to a location within the electric field while keeping the unit charge at a constant velocity.
So, for example, the inside of a cell is negatively charged. Thus, any positive charge will be drawn into the negatively charged electric field, so a negative amount of force is required to keep the velocity constant. In this case, the electric potential is negative.
The outside of a cell is positively charged. Thus, any positive charge will be pushed away from the electric field, so a positive amount of force is required to keep the velocity constant. In this case, the electric potential is positive.
Thus, since there is a difference in the potentials on both sides of the cell membrane, we have a membrane potential.
The resting potential is the simply the membrane potential of the cell at rest. The action potential occurs whenever there is a quick change in the membrane potential. | [
"An action potential is a spike of both positive and negative ionic discharge that travels along the membrane of a cell. The creation and conduction of action potentials represents a fundamental means of communication in the nervous system. Action potentials represent rapid reversals in voltage across the plasma me... |
Why was medieval Spain so prosperous compared to the rest of western Europe? | What period are you interested in? | [
"Late medieval Spain was divided into the three Christian kingdoms of Navarre, Castile and Aragon, alongside the small, last remaining Islamic state of Granada. The civil wars and conflicts of the late 14th and early 15th century would result in the unification of the Christian kingdoms; combined with advances in n... |
How did Sailors prevent ships from sinking in the 18th century after receiving heavy cannon fire? | Hi there, I just answered a different question regarding ship damage in this sub -- I will link there for resources from Google books:
_URL_0_
Regarding cannon fire, the main concern would be actual holes in the ship's hull that were leaking water. A secondary concern would be structural damage to the ship's hull, related to actual cannon fire but not as the result of direct damage/holes, that would loosen space between planks and allow water to enter that way.
Depending on the size of the hole, ships' carpenters and carpenters' mates could use shot plugs to try to stem the flow of water. Shot plugs were tapered cylinders that could fit several sizes of hole (fatter side to the outside). Working over the side of the ship, they could hammer shot plugs into holes, which would theoretically be held in place by water pressure while they worked on a more permanent patch.
For larger holes or those more difficult to be plugged, they could do something called "fothering" a sail. To do that, they would sew pieces of rope fibers, yarn, twine or shakings through a spare sail, giving it the look of an old-time quilt and increasing the density of the sail. They would lower the fothered sail over the side and maneuver it to cover the hole; although it was not wateright, it might slow the leak and allow repairs to be made.
For major structural damage, cables (ropes) could be wrapped around the ship and tightened to tighten the seams between the hull planks.
Pumping ship was a daily occupation anyhow, because all wooden ships leaked, and they were fitted with pumps. So pumping would be ongoing during the other damage control operations.
Edit: You can read about fothering a sail to help refloat HMS Endeavour here: _URL_1_ | [
"Warships of the age of sail were highly vulnerable to fire. Made of wood, with seams caulked with tar, ropes greased with fat, and stores of gunpowder, there was little that would not burn. Accidental fires destroyed many ships, so fire ships presented a terrifying threat. With the wind in exactly the right direct... |
fcc comments. how many are needed and how do they make a difference in policy? | The SOPA debate led to over 500k comments on the FCC.
Less than a year later, the initial mainstream net neutrality debate that followed led to over 1M comments on the FCC.
So, to answer your question - historically it seems that you need roughly 500k comments to delay policy change for another year.
The question is, how many do you have to hit in order to actually cement net neutrality as policy. As that number is purely hypothetical, let's just say that as long as there's a monopoly on ISPs being privately opposed to publicly run, the answer is: infinite comments. | [
"Federal agencies often solicit and release public comments on proposed legislation. Regulations.gov, which is designated for public comments, includes a detailed set of guidelines explaining how to submit comments, what type of personal information is collected and how that information may be used, stating, \"Some... |
I've heard several times that the M4 Sherman tank was vastly outdated and inferior to nearly all other tanks in WW2 in every regard except quantity; how much truth is there to this? Why would the US use an obsolete tank? | vastly outdated and inferior to nearly all other tanks? not at all, it was better than the models it first encountered in africa (pz3, early pz4), and even later in the war it could hold its ground (and the later sherman models with a 76,2mm gun such as the easy eight were even better) against the 4s and stugs - of which the germans had the largest numbers, unlike the panther or tiger, both of which however were vastly superior to the sherman
compared to german tanks it was also much more reliable, easier to maintain and repair, and not a logistics nightmare (which the german heavy tanks were), it also had the advantage of having a stabilizer right from the start, something the german engineers took a longer time to implement and never so extensively
i think it is also important to note the early american tank engagement doctrine which called for tank destroyers to be the primary means of engaging enemy armor... with this, the fact that the shermans fared very well in their first fights, mostly adequately later and only were truly outmatched by the german heavy armor, and the logistics involved both on the ground in day to day battlefield conditions as well as overseas industry in mind, it is just nonsense to talk about the sherman being vastly inferior | [
"The M4 Sherman became the standard American military tank in World War II. Due to lack of development before the war leading to inexperience in tank design, the first large scale production of a medium tank was the M3 Lee, built for the US and the British, a compromise design with the main weapon mounted in the hu... |
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