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Why do only one or two new immunogenic strains of the influenza virus appear yearly despite their highly variable nature ? | More strains almost certainly appear, but there are very, very few amino acid mutations that both 1) help either change an epitope to evade the immune system or change a binding protein so it recognizes humans, and 2) that allow their proteins (usually nueraminidase or hemagglutinin) to properly function. Its an incredibly hard optimization problem that nature, even though it has billions and billions of tries each year, only gets right a couple times (which is why its so hard to replicate in a laboratory, and why the one [created in a lab](_URL_0_) was such a big deal.) | [
"New influenza viruses are constantly evolving by mutation or by reassortment. Mutations can cause small changes in the hemagglutinin and neuraminidase antigens on the surface of the virus. This is called antigenic drift, which slowly creates an increasing variety of strains until one evolves that can infect people... |
What did pre-germ theory people think was going on when a cut got infected? | /u/Sir_David_S wrote an answer to a similar question regarding Miasma theory in this thread:
_URL_0_
The thread and answer specifically deal with reasons why people believed in Miasma theory, which was one of the predominant theories of disease transmission prior to germ theory.
Figured people might be interested in it, though as that is only one facet of the question in *this* thread, hopefully someone can provide a more general/holistic answer here. | [
"Chagas suspected that the parasite could cause human disease, due to the prevalence of the insect vector in human households and its habit of biting people, so he took blood samples and, on April 23, 1909, discovered for the first time the same \"Trypanosoma\" parasite in the blood of a 3-year-old girl. He also ob... |
How did you choose a graduate school? | I did two overlapping things while I was searching for PhD programs:
1. I remembered work that was in a similar vein to what I wanted to do, or that had impacted my scholarly development in a positive way. I then figured out where those scholars were. If they were in a top-level graduate program, I put them on the list. If they were on a lesser school or in a department without a PhD program (such as a liberal arts college), too bad, move on.
2. I looked at the top-20 or so programs and saw who was there and if I would be interested in working with them. The top tier will vary somewhat by field and subfield, but it will generally include most of the Ivies, several other great private schools (Stanford, Chicago, Duke), and the top public schools (both big UC schools, Michigan, UNC, UVA) (Note that this list is not intended to be comprehensive). In certain fields or subfields other schools will have high-quality programs. You can get a sense of their quality through rankings, kind of, but also by asking your professors, the placement rates and locations of recent PhD graduates, and their ability to fund PhD students fully.
This leads me to another source, one that I did not fully explore due to unique personal circumstances, but that you definitely should: Ask your current professors. They should know both you and their field well, and can steer you in a good direction. If you post more about your interests, some of the contributors here might be able to help, too.
Finally, you say you want a Master's rather than a PhD. Unless your family is wealthy and can pay for this degree out-of-pocket, I strongly urge you to minimize your debt any way you can. Paying for an MA in the humanities (as I did) is quite foolish, and can be financially crippling. Consider the flagship university in your state, or consider moving to a state for a year to establish residency before beginning your MA at THAT state's flagship. Another course is to get a job at the school you wish to attend, and then use your employee tuition remission to get your MA part-time over several years while earning a salary. In an MA specialization is somewhat less important than PhD, as is prestige, and you can go for higher levels of both specialization and prestige if you end up going on to a PhD. | [
"The Graduate School was created in 1971, initiating its academic activities with the programs of doctorate and masters in Education. The master's degree in Psychology and Philosophy were created in 1988, and the doctorate in Psychology in 1994. Subsequently, created the master's degree in Civil Law and Nutrition a... |
what purpose does the wingdings font serve? | Those fonts were made to provide computers a method of displaying basic graphics when graphics were limited. | [
"Wingdings is a series of dingbat fonts which render letters as a variety of symbols. They were originally developed in 1990 by Microsoft by combining glyphs from Lucida Icons, Arrows, and Stars licensed from Charles Bigelow and Kris Holmes. Certain versions of the font's copyright string include an attribution to ... |
Do planets expand when they're closer to the sun? And get smaller when they're distant from the heat? | As a previous poster said, for gas giants they absolutely do and we observe it. For gas giants in close to their host star we refer to them as Hot Jupiters (HJs) (these are gas giants less than 1AU from their host star). We have observed that some (but not all) HJs have inflated radii (sometimes known as [puffy hot Jupiters or puffy planets](_URL_2_)). That is some HJs the mass of Jupiter are actually twice the radius of Jupiter [(an example)](_URL_0_). Interestingly this is not fully explained by just heat flux from the star. One of the leading theories is that there is additional internal heating of the planet through interactions of the two bodies magnetic fields (a process known as [ohmic heating](_URL_1_)). This is still an area with many open questions and it is still not well understood why they swell to such sizes.
& nbsp;
It is possible that rocky planets might have the same magnetic field interactions but as far as I am aware this has not been observed. So while in general the answer to your question is, yes we would expect closer in planets to have larger volume than an equivalent planet further out. The extent of the inflation is not obvious and still a matter of some debate (and basically at the cutting edge of exoplanetary theory). | [
"As the Sun expands, it will swallow the planets Mercury and Venus. Earth's fate is less clear; although the Sun will envelop Earth's current orbit, the star's loss of mass (and thus weaker gravity) will cause the planets' orbits to move farther out. If it were only for this, Venus and Earth would probably escape i... |
What happens if a patient with an allergy to anesthetic needs surgery? | Anesthesiologist here.
"Allergic to anesthesia" is an almost never sort of thing. Yeah, we see it on charts, but what that usually means is an adverse reaction to one of the drugs we use, or normal side effects associated with anesthesia.
There are some conditions that make anesthesia potentially dangerous for some people. The two big ones are:
* Malignant hyperthermia - this is a genetic condition that causes a potentially fatal abnormal metabolic response when the patient is exposed to certain drugs. We can safely anesthetize these people by avoiding the triggering agents.
* Atypical pseudocholinesterase - this is another genetic condition that interferes with the breakdown of one paralyzing agent that we use. It turns a 5 minute drug into a several hours drug, which is a problem when we don't expect that to happen. If we know about it, we don't use the drug in question (succinylcholine).
There are many, many ways to give a general anesthetic, and there are also alternatives to general anesthesia for some cases. I haven't met anyone yet that I can't anesthetize in the 24 years that I've been giving anesthesia to people. Some patients just require some creativity. | [
"Anesthesia has the potential to cause malignant hyperthermia, an uncontrolled increase in body temperature, and permanent muscle damage in patients with MADD. Individuals with MADD are advised to notify their anesthesiologist about their condition prior to surgery.\n",
"Anesthesia is unique in that it is not a d... |
Why didn't the Ottoman Empire do anything during the 30 years war? | The relative lull in their conflicts in the west actually gave the Ottomans some breathing space to focus on their long standing rival in the east, the Safavids of Persia. The last war with the Habsburgs, the "long war" from 1593-1606 was a exhausting draw and stopped further Ottoman advance into Hungary and Croatia. The focus switched to the Safavids as they started gaining ground in the Caucasus and Iraq, thus most of Murat IV's reign was spent trying to retrieve these lands. | [
"Following the defeat of the Ottoman Empire in the First World War, the Ottoman army was disarmed according to the Armistice of Mudros. Although the Ottoman Empire had to agree to give up vast territories including most of Middle East, the Allies further retained the power of controlling what was left of the Ottoma... |
why does music, or even television seemingly get quieter the longer i listen? | Best ELI5 answer I can come up with: Compare it to how a dark room seems brighter the longer you're in it. That's your eyes adjusting to a low level of light.
The opposite happens when you listen to a t.v. loud for a while, your ears try to adjust to a high level of sound. | [
"After every two days at midnight, the music from the previous decade becomes quieter and quickly fades away, while the music from the next decade starts at normal volume. For example, when midnight of 1960 occurs, the music from the 1950s fades away and the music from the 1960s plays at normal volume.\n",
"A pot... |
why does anything that takes multiple batteries require them to be alternated? | The batteries are connected together in series with each positive end being connected to the negative end of the next battery in the sequence. It's much easier and cheaper to design a battery pack where you alternate the batteries (whereby the positive end of one battery is very close to negative end of the next battery). | [
"A battery swapping (or switching) station is a place at which a vehicle's discharged battery or battery pack can be immediately swapped for a fully charged one, eliminating the delay involved in waiting for the vehicle's battery to charge.\n",
"Battery swapping is a strategy to avoid range anxiety that allows el... |
why would someone want to/ need to use tor? | There are many reasons why people would want to hide their activity or be anonymous. A lot are legitimate, a lot are not, and a whole lot are in between.
Say you live in a country with a repressive regime that blocks access to, say, pro-democracy websites. You can get around that with Tor.
Say you're a privacy advocate and don't want your data logged on general principle. Tor is one of the tools you can use to mitigate that.
Tor is one of the simplest/easiest ways to achieve privacy/anonymity on the web. It's not perfect, but it helps. Anyone who wants that, Tor is probably their first stop. | [
"Tor (short for The Onion Router) is a system intended to enable online anonymity. Tor client software routes Internet traffic through a worldwide volunteer network of servers in order to conceal a user's location or usage from someone conducting network surveillance or traffic analysis. Using Tor makes it more dif... |
how cease and desist letters are not blackmail. | Cease and desist does not threaten anything illegal (such as violence), all it threatens is a lawsuit which is the accepted way to settle a dispute, and there's no guarantee that it will go either way, the plaintiff may lose.
Blackmail: "If you don't give me your lunch money I'm going to beat you up."
Cease and Desist: "If you don't give me your lunch money I'm going to tell the teacher that you should give it to me." | [
"Although cease and desist letters are not exclusively used in the area of intellectual property, such letters \"are frequently utilized in disputes concerning intellectual property and represent an important feature of the intellectual property law landscape\". The holder of an intellectual property right such as ... |
why does a lack of genetic diversity cause deformities? | Imagine a machine that makes bricks that you make a house with but machine needs a sample brick to make more bricks like it.
Imagine you only have a few types of bricks. One of em gets chipped and goes into the machine.
If there are many bricks the machine will see the difference between a chipped brick and OK brick and use the OK brick to make more bricks.
If all chipped bricks go in eventually you have all broken and chipped bricks coming out of the machine.
House is human. Brick is the chromosomes.
| [
"Deleterious alleles segregating in populations of diploid organisms have a remarkable trend to be, at least, partially recessive. This means that, when they occur in homozygosis (double copies), they reduce fitness by more than twice than when they occur in heterozygosis (single copy). In other words, part of thei... |
how do coin counting machines work? | They have various holes of increasing size, separating the individual coins. After being separated, each coin pushes a trigger bar as it falls, incrementing a counter which keeps tally of that kind of coin. From there, it's all multiplication and addition to come up with the value of all the coins.
Edit: my brain short-circuited | [
"A currency-counting machine is a machine that counts money—either stacks of banknotes or loose collections of coins. Counters may be purely mechanical or use electronic components. The machines typically provide a total count of all money, or count off specific batch sizes for wrapping and storage.\n",
"Electron... |
In Feudal Europe, how did doctors become doctors? | Define time period | [
"It is Medieval Europe, and the Church is fighting against 'black magic'. The medical knowledge of Greek physicians like Hippocrates and Galen had been lost to the medicine of medieval Europe. In 11th-century England, travelling barber surgeons attempted to supply medical care to the ordinary population, often at t... |
eil5: what was the conflict between edison and tesla about? | **While Tesla and Edison:** When Tesla moved to America, he began to work for Edison. He quickly started to climb Edison's corporate ladder, until Edison wanted him to redesign generators/motors using A/C. He offered Tesla lots of money for them. However, once Tesla went to give Edison the designs, he basically told him that he misunderstood him and he wasn't going to get a single cent. Tesla rage'd and made his own company.
**AC vs DC:** Imagine that AC and DC are like types of roads and that currents are types of cars. AC allows a lot more cars to be moved and in both directions over a huge distance, where as DC is a one lane road that only allows a small amount of volume and can't go very far.
**A world with no A/C:** When Edison created D/C, he imagined that he would have power stations everywhere, due to how short distance D/C was. Moreover, there would be ~~huge~~ [oh-god-I-can't-see-outside huge power-lines](_URL_0_) (note: that image is drawn in 1890, imagine how congested it would be now)
If you have any other questions, I'll be happy to answer them.
| [
"The fifteen electric companies that existed 5 years before had merged down to two; General Electric and Westinghouse. The war of currents came to an end and this merger of the Edison company, along with its lighting patents, and the Thomson-Houston, with its AC patents, created a company that controlled three quar... |
how do tv/any screens actually work, like how do each pixels show different colours? | In LCD/LED TV's, each pixel has a red, green and blue element that can recreate a range of shades of that color. When combined you can create any color you need. Standard HDTV has 1920 pixels across and 1080 up and down.
The pixels work by passing light through a color filter (Red,Green and Blue) and then through a LCD which polarizes the light. Then the light is sent through a outer screen that only allows the polarized light to pass. So the more the LCD polarizes the light, the brighter the pixel becomes for the color needed.
The LED monitors use LED arrays to provide that initial light source. They are beneficial because of better color temperature and you can dim the individual LED segments to allow for deeper blacks in regions. Non-LED monitors use a fluorescent bulb to provide the backlight. | [
"Normally, the software in a computer treats the computer’s display screen as a rectangular array of square, indivisible pixels, each of which has an intensity and color that are determined by the blending of three primary colors: red, green, and blue. However, actual display hardware usually implements each pixel ... |
"OK" is the survivor of an 1839 slang in which speakers would abbreviate purposefully misspelled phrases (all correct=oll korrect=ok). Do we have any record of negative reactions to or criticisms of this fad and it's creators? | Yes. The etymologist who tracked down the origin of OK as "oll korrect" was named [Allen Walker Read](_URL_2_).
The groundbreaking article authored by him is called [The First Stage in the History of "O.K."](_URL_0_) He presents many examples that clearly support his assertion of the use of "OK" in the 1830s and 40s, and a couple of the quotes he pulled do show disapproval toward the abbreviation fad.
The earliest denunciation actually predates the first mention of "all correct" as the meaning behind OK. It comes from page 1 of the June 19, 1838, edition of the *Boston Post* in a letter to the editor:
> "The present age is one pregnant with experiments...There is yet one other sect...who in their fondness for a brevity of writing, would discard every letter of a word, but that with which it commences.
>
> "They extend this principle to speech, too—the glory in hyroglyphics—they rejoice in *steno*graphics—but it is to this very class that I would send forth my denunciation—let it be said that it is a dangerous sect—men whom Caesar would have regarded with a suspicious eye...I mistrust them—let them come out freely and openly and show us that their cabalistic signs are not omens of evil..."
The following year, an article appeared in the *Philadelphia Gazette* reporting on the fad, and the *New Orleans Sun* reprinted the article on page 2 of their December 3, 1839, issue. But the editor of the New Orleans paper added his own introduction:
> "HUMBUG.—It is laughable to observe what trash is served up for the edification of the Philadelphians..."
However, these are just two out of literally dozens of articles reporting on the fad around that time. In Allen Walker Read's other examples, the reporter either made no commentary one way or the other, or else found the fad "amusing."
In fact, Read points out that many newspaper writers joined in with the fad through their writing, offering up their own ridiculous initialisms that were never actually used in oral conversation. One example from the New York *Evening Tattler* being "W.O.O.O.F.C." ("with one of our first citizens").
Others actually were used colloquially, the most popular other ones seeming to be "N.G." and later "K.G." ("no go"/"know go"), "K.Y." ("know yuse"), and O.F.M. ("our first men", a derogatory way of referring to self-important young upper class males, something like "yuppy" today).
If the subject of the word "OK" interests you, I highly recommend picking up a copy of Allen Walker Read's [*Milestones in the History of English in America*](_URL_1_). It's a collection of his scholarly essays, so it can be pretty dry, but about 50 pages of the book are dedicated to the etymological history of "OK" with lots of quoted sources beginning from its earliest written use in 1839. Many of his articles are available individually on jstor as well. | [
"Read proposed an etymology of \"OK\" in \"Old Kinderhook\" in 1941. The evidence presented in that article was somewhat sparse, and the connection to \"Oll Korrect\" not fully elucidated. Various challenges to the etymology were presented; e.g., Heflin's 1962 article. However, Read's landmark 1963–1964 papers sile... |
if the sun is constantly adding heat/energy to earth, then why has the temperature always stayed the same? | heat leaves via radiation = the same way heat gets to Earth from the Sun, despite no air between them. | [
"Earth absorbs some of the radiant energy received from the sun, reflects some of it as light and reflects or radiates the rest back to space as heat. Earth's surface temperature depends on this balance between incoming and outgoing energy. If this energy balance is shifted, Earth's surface becomes warmer or cooler... |
If the Americans secretly invented the atomic bomb, how did Russia get their hands on the technology so soon after it's invention? | The biggest secret of the Manhattan Project was that there _was_ a Manhattan Project. That is, the secret of the atomic bomb was, largely, that an atomic bomb could be made.
That secret was revealed to the entire world on August 6, 1945.
The Soviet Union, on the other hand, had a number of well-placed spies who gave them information about the American work from 1941 onward. Stalin, in fact, knew more about the atomic bomb for much longer than did Harry Truman, who was not told about it until after Roosevelt's death.
Separate from this, what goes into making an atomic bomb? You need to acquire lots of uranium first, you need to know a lot about how nuclear chain reactions work, and you then need to produce fissile material, either by building reactors or by enriching the uranium.
The US started its project in earnest in late 1942/early 1943. (There was earlier work, but it was more or less table-top science until the decision was made to actually do the work necessary to build a bomb.) Construction of its reactors and enrichment plants started around the same time. The first plutonium production reactor went online in fall of 1944, and the first enrichment of uranium on a large scale started around the same period. This enabled them to have, by July 1945, enough high-enriched uranium for the bomb used on Hiroshima, and enough plutonium for the bomb tested at Trinity and the bomb dropped on Nagasaki. They also had another bomb's worth of plutonium in the pipeline.
So they managed to pull off all of that work in a little under 2 years of intense effort.
What about the Soviets? During the war they acquired a lot of information about what the US was doing on its bomb project, including information on the bomb design itself from the highly-placed, highly-capable mole Klaus Fuchs. During WWII, however, they did not have the manpower or resources to work on the bomb to any real degree, other than slowly working to build their first experimental nuclear reactor and collecting the intelligence information. Immediately after Hiroshima, however, Stalin accelerated the project and put Lavrentii Beria, the NKVD chief, in charge of building an atomic bomb as soon as possible.
The Soviets had a huge advantage over the US — they knew a bomb would work and they knew which methods had worked in the US case. Neither of those were secrets; the US publicized both of those facts immediately after using the bombs. They also had some technical data on how the bombs worked, but Beria did not trust spy data by itself, which meant he had his scientists check and re-check the American data. (Only a few of the Soviet scientists knew there was spy data; most of the data was "sanitized" and made to look like it came from other Soviet scientists.) In some cases this even meant having Soviet scientists "re-invent" things that the Americans had made, without realizing it.
But this kind of information did not set the timeline of the Soviet project. Unlike the Americans, the Soviets had almost no access to raw quantities of uranium. They had no major uranium sources known in their country at the end of WWII (they were able to get some from Czechslovakia at the end of the war). So the largest effort, and the real timeline of the project, was involved trying to locate uranium sources, including the exploitation (with slave labor) of very low-grade uranium ore sources (ores that would be considered too paltry for American use).
So yes, the spy information helped, but it can be overemphasized. The hardest part about the Soviets making the bomb was getting raw material. The Soviets had excellent scientists and were able to put together a strong industrial base. It took them about 4 years of continual effort to get their first bomb together — about twice as long as it took the Americans.
So personally I don't think of it as being "so soon" after the first bomb for that reason. Even at the time (in 1945), most scientists thought it would take the USSR about 5 years to get a bomb — they were slightly faster than that, but not by much, especially since they had been doing low-level scientific work on bomb questions since the war.
It only felt "very soon" to people in 1949 because they continued to say "5 years" well after 1945, without incrementing the clock downward (e.g. 4 years in 1946, 3 years in 1947, etc.). It is artifact of US estimations, and US politics, and poor US Soviet intelligence at the time, that people were "surprised" at the speed of the Soviet bomb. | [
"In 1945, the Soviet intelligence obtained rough blueprints of the first U.S. atomic device. Alexei Kojevnikov has estimated, based on newly released Soviet documents, that the primary way in which the espionage may have sped up the Soviet project was that it allowed Khariton to avoid dangerous tests to determine t... |
how is it safe to consume smoked meats? | Same way cooking does, by getting the meat hot enough to kill bacteria. Even a "low-temp" smoker is at about 200 F. | [
"Cold smoking meats is not something that should be attempted at home, according to the US National Center for Home Food Preservation:\"Most food scientists cannot recommend cold-smoking methods because of the inherent risks.\" Cold smoking meats should only be attempted by personnel certified in HACCP, or Hazard A... |
What is the curvature of empty space? | There are many non-trivial vacuum spacetimes, including all of the familiar black hole solutions (Schwarzschild, Kerr-Newman, etc.). Vacuum does not imply zero curvature.
> The curvature of the universe is 0, at least, as close as we've been able to measure it.
The *spatial* curvature is thought to be zero, and this is meaningful in our particular model of cosmology (FLRW universe). But the universe is not empty and this does not mean spacetime has zero curvature.
> On the other hand, near matter, space has slightly positive curvature (have I got that right?)
No. There's no such thing as "positive" curvature. Curvature is described by 20 independent numbers at each point. | [
"De Sitter special relativity postulates that the empty space has de Sitter symmetry as a fundamental law of nature. This means that spacetime is slightly curved even in the absence of matter or energy. This residual curvature implies a positive cosmological constant to be determined by observation. Due to the smal... |
why isn't water vapor considered worse than carbon in climate issues? | The reason why Carbon is the element to track is because of the lifecycle of the elements involved.
Water will evaporate from oceans, float over land masses, and condense into rain. It does this fairly cyclically. There is no net new water being added to the system.
With Carbon Dioxide, there's a cycle of plants breathing in CO2, turning that into sugars. Animals eat the plants, and when we breath in Oxygen, we combine the sugar and oxygen and make CO2 as a biproduct. That forms a natural cycle.
However, there's also a big cache of carbon under the ground from a hundreds of millions of years ago. Back then, there weren't any bacteria that ate up trees when they died. They just eventually toppled and kept all their carbon inside of them, and eventually got buried.
All that carbon is what we dig up as fossil fuels. We're introducing it back into this cycle, but there isn't any carbon sinks to hold it out of the atmosphere for any serious length of time. Thus, the CO2 builds up in the atmosphere, and increases the planets retained energy from the sun, causing the average temperature to go up. | [
"BULLET::::- water vapour is a greenhouse gas that has a greater overall effect on the ozone layer than carbon dioxide because of its higher concentrations but is not affected by human activities as it is caused mainly by evaporation and condensation rates.\n",
"Carbon dioxide, while vital for photosynthesis, is ... |
how do you properly use the paper toilet seat covers provided in public restrooms? | The fully-cut side goes to the back; the flap side should fall down from the front. It's supposedly for men when they sit, so their penis doesn't touch the porcelain. But it's also the only orientation where the paper cover doesn't just slide into the water before you ever manage to sit down.
Don't feel weird about not knowing. | [
"There has been much debate among those who use toilet covers, regarding the orientation of said toilet seat cover. The proper way to place a cover on a toilet seat is to place the side with the flap toward the front of the toilet, with the flap going in the toilet to prevent \"splashing\" forward. Most public toil... |
Why are all particles bosons or fermions? | Excellent questions - the answers are very subtle.
First of all, let's look at your first question, why exchange has to be symmetric or antisymmetric. You may be surprised to know that It's actually a peculiarity of having 3 (actually, just of having more than 2) spatial dimensions.
To see why this is, let's think first about how to implement particle exchange. A careful way to do this is to imagine that you start with two particles and slowly drag one of them around the other one until it's on the other side, then slide both particles over so that they are in the initial positions. You should try to draw this if my description is confusing. The statistics shouldn't depend on *how* you drag one particle around the other, just that you complete one half loop.
Now, suppose you exchange the particles twice. That's the same as dragging one particle halfway around the other, and then doing it again, that is, having one particle make a full loop around the other one. Now here's the key point: again, the result here shouldn't depend on the exact shape or size of the loop, only that the particles have been exchanged twice. In two dimensions, this loop must contain the other particle, and you cannot shrink the loop to zero size without crashing the first particle into the second at some point. However, in three dimensions, you can push the loop out of the original plane - in fact, you can shrink the loop to zero size while always keeping the first particle far away from the second particle. (Sorry I don't have pictures! Try drawing some.) This means that two exchanges *must* have the same effect as doing nothing at all, since the statistics shouldn't depend on what the loop looks like! That is, a single exchange can *only* either give you a minus sign or no change at all, so that you get no change upon doing it twice. In 2D, this is not true - in fact, you can get [anyons](_URL_1_) in 2D.
This exhausts my expertise for lay explanations to your questions - unfortunately I don't have a non-technical answer to the others. Hopefully someone else can fill in. But I'll give a couple of starting points.
Your second question, of why a particle can't have other spins. ~~It's a result of putting special relativity and quantum mechanics together, actually, in 3 spatial dimensions. For the mathematically inclined, it has to do with the fact that 1/2-integer and integer spins are the only allowed representations of the Lorentz group (which is the set of symmetries of spacetime in special relativity).~~ (EDIT: Important correction given as a response.)
And finally, the connection between the two - the [spin-statistics theorem](_URL_0_) tells you that bosons have integer spin and fermions have half-integer spin. This again relies on special relativity and having 3 spatial dimensions. | [
"Composite particles (such as hadrons, nuclei, and atoms) can be bosons or fermions depending on their constituents. More precisely, because of the relation between spin and statistics, a particle containing an odd number of fermions is itself a fermion. It will have half-integer spin.\n",
"Composite particles (s... |
When one person fails to open a pickle jar, the next person to try often succeeds. Has the first person's attempt at opening the jar 'loosened' it up? | This strikes me as highly unlikely, since we don't experience a sudden failing of musculature that would lead the first person to be unable to open the "loosened" jar. (Unless you have cataplexy.)
Instead, it seems much more likely that the second person is already anticipating a greater effort than the first person expected, and thus adopts a position that uses different muscle groups to full advantage. You can actually hurt a person, potentially, by acting as though a cap is on tight and needs to be wrenched, unless they manage to stop quickly.
Edited: grammar | [
"The trick is that the first person did something surreptitiously, usually at the end of the \"Johnny\" sequence, such as folding his or her arms, putting his or her hands together, or saying \"Now, you try.\" When the other people in the group try to repeat the \"Johnny, Johnny\" sequence, then, they are told they... |
Can anyone explain the three interactions happening in the Feynman triangle diagram? | The absolute most important thing to remember is that Feynman diagrams are mostly just visualization technique. To start with, the angles represent nothing; though a particle's angle from the horizontal *would* correspond to its speed, in practice the diagram is used to represent all possible speeds of all particles in it, and the actual speeds are specified (for the reagents and byproducts) or averaged over (for the "virtual" particles that start and end inside the diagram).
You're absolutely right that the third interaction is ultimately identical to the others, at least mathematically. Physically, you're right; it's a positron emitting or absorbing a photon and scattering. This kind of diagram is usually used to represent a "sub-diagram" of some other process: that is, at least one of the particles, most likely the top photon, has its other endpoint in some part of a larger Feynman diagram not shown here. But it's the same kind of photon that you'd see in the basic [Coulomb scattering Feynman diagram](_URL_1_).
We can draw the photon vertically, partly because as I said the direction doesn't have to represent reality exactly, but more because the photon there is a "virtual particle" that doesn't have to follow the rules. Virtual particles, well arguably they're not really particles at all, just excitations in the quantum field that behave enough like particles that we can sort of treat them as such in calculations. Critically, though, they don't have to have the relativistic relationship between speed and energy given by their mass, and they can even "travel" faster than the speed of light. I put "travel" in quotes there because it's not really in that case an excitation travelling; it's perhaps more of a path that happened to be completed on both ends.
But really maybe the *most important* reason that a photon might be drawn like that is just because the virtual photon it represents might be going forwards, and it might be going backwards; it doesn't really matter, you can draw the same line to represent both, and it'll make the math easier when you want to add those possibilities together.
Finally: as for matter and antimatter, it's maybe better to say, for this particular triangle diagram, that matter/antimatter being the same has interesting things to say about the diagram. Specifically,largely because it's fundamentally the same when you flip the arrows, this diagram and the antimatter diagram (with arrows flipped) cancel each other out. And so really I suspect you're only seeing this diagram because it's prettier than the triangle diagrams that are actually of interest to physicists. The one that comes up in QED, on the right vertex in the rightmost diagram [here](_URL_2_), is for an electron scattering off a photon (or an electron and positron annihilating to make a photon, etc.). Perhaps the most interesting one that's come up lately has been [this one](_URL_0_), for production of a Higgs boson out of gluons (contained in protons being collided at the LHC) through a "triangle" of top quarks. | [
"Einthoven's triangle is an imaginary formation of three limb leads in a triangle used in electrocardiography, formed by the two shoulders and the pubis. The shape forms an inverted equilateral triangle with the heart at the center that produces zero potential when the voltages are summed. It is named after Willem ... |
why doesn't everyone capitalize the word "internet?" there is only one internet and the chicago manual of style capitalizes it, so why would anyone spell it in lowercase? | Because it's inconvenient to hit the shift key any more than necessary. And by necessary, I mean that most people won't notice is it's casually omitted. | [
"When the term \"Internet\" is used to refer to the specific global system of interconnected Internet Protocol (IP) networks, the word is a proper noun that should be written with an initial capital letter. In common use and the media, it is often not capitalized, viz. \"the internet.\" Some guides specify that the... |
why do some coins tinkle with a metallic sound when you flick them but some coins don't sound much like anything? | The speed of sound and resonant frequency in a coin changes with size and composition.
Some coins are made of the right metals in the right shape that will reverberate with that characteristic ring, others aren't.
A US nickel is 5g of 75% copper and 25% nickel, and will ring when flicked. A dime (92% copper) will as well.
A penny (97.5% zinc) wont. | [
"Another method to determine whether a coin was plated was listening to the sound produced by dropping the coin onto a hard surface since if the coin was solid silver it would have a distinctive ring. Although this was done by contemporary merchants, it is not recommended that this method be used on ancient coin si... |
Is population control an absolute requirement for a post-scarcity economy? | You mean to *achieve* a post-scarcity economy.
Any answer to this would be speculative and normative in nature. One economist who would disagree with the need for population control is [Julian Simon](_URL_1_), who claimed that as resources diminish, an incentive is created to find new, more efficient ways to exploit those resources. In the end, this scientific innovation will increase the well-being of humans even if there are more of them. An example might be the Green Revolution in agriculture.
Another economist, Micheal Kremer has suggested that [more people means more collective brain power](_URL_0_), in turn leading to an increasing rate of technological progress.
Like I said, no one can answer this question, but since you specifically asked about population control being an *absolute* requirement, and since there are scientists whose ideas suggest otherwise, perhaps a suitable conclusions would be, "no, not necessarily an *absolute* requirement." | [
"Efforts to control population have been controversial, and Connelly argues that \"the road to controlling population growth in the 20th century was paved with good intentions and unpleasant policies that did not work\". For example, millions of intrauterine contraceptive devices were exported to poor countries alt... |
WWII - Found this is a box of my deceased grandfathers possessions. What is it? | Lagergeld (literally storage money or storage charges), during WWII, were employed within ghettos and concentration camps in replacement of actual money. This would ensure that prisoners would not have any valuable currency on their person if they should escape.
This money had been used by German authorities since as far back as the First World War, as records belonging to Western Michigan University show the production of 5 pfennig lagergeld notes dating back to at least 1919. (Source: _URL_1_)
The UK’s Imperial War Museum states that “Lagergeld was used to compensate prisoners in concentration camps for their work. This note was not negotiable outside of the camp for which it was issued and was specifically for use in their stores and canteens.” (Source: _URL_0_) | [
"It was also the site of the recent discovery of a bag which had been lost in the Second World War by a dispatch rider (Alec Ross) of the Long Range Desert Group, part of the British Army. This contained the rider's personal letters and photographs, and had been well preserved.\n",
"Numerous items were found with... |
the fcc is closed... does that mean pirate radio can not be stopped? | More or less. However, if something can fall in a local police jurisdiction, you're out of luck, because they're still on the job. However, since it usually takes a decent bit of equipment to start a serious pirate radio station, and historically these Government shutdowns are incredibly long, it isn't likely to be a big issue. The current pirates get a short reprieve, but the shutdown isn't long enough to really entice any new pirates.
If the FCC can prove later that you made pirate broadcasts during this period, you're still in trouble. | [
"Although this should mean that pirate radio has seen a decrease, most of the licensees are churches, colleges, and state or local government transportation departments, as the FCC requires the licensee to be a non-profit organization. Pirate radio also continues because legal open spots on the FM dial have been fi... |
why are acl injuries so difficult to repair properly? | Most injuries cause the entire thing to tear, with the ends not connected at all anymore. That will never heal without surgery, because the ligament has no mechanisms that allow it to fix itself when fully torn apart. | [
"Long term complications of ACL injury include early onset arthritis of the knee and/or re-tearing the ligament. Factors that increase risk of arthritis include severity of the initial injury, injury to other structures in the knee, and level of activity following treatment. Not repairing tears to the ACL can somet... |
"Participation" of Soldiers in the American Civil War | A few notes:
1) The original source of the unfired muskets statistic seems to be an [1867 army manual](_URL_0_).
> Of the 27,574 muskets picked up on the battle field of Gettysburgh and turned into the Washington Arsenal at least 24,000 were loaded. About one half of this number contained two charges each, one fourth contained from three to ten charges each, and the balance one charge. The largest number of cartridges found in any one piece was twenty three.
Since then, the figure has appeared in a few books, perhaps most notably *On Killing*, as evidence of Civil War soldiers' reluctance to kill.
Note, however, that the author of this manual doesn't seem surprised by the figure. He makes no attempt to explain it or understand in terms of soldiers' feelings.
2) PTSD can occur in many situations that don't involve killing. Returning Civil War soldiers absolutely suffered from it, but the disorder didn't have a name or body of study behind it. There are many accounts that clearly indicate PTSD, and it is probably not a coincidence that Civil War veterans became the most criminal and drug-addicted segment of society after the conflict.
3) It is untenable, historically, to draw such a broad conclusion from such a tiny shred of evidence. I would need a lot more data before I even began to believe such a claim.
4) Your points about artillery are good. Also note that the claim is not "unfired" but rather "found loaded," so you also have to consider men who were killed between shots.
Hope this clears a few things up. Once upon a time I was a flaired Civil War guy on this sub. Let me know if anything seems unclear. | [
"On April 2, 1863, roughly 600 soldiers from 20 states loyal to the Union, including members of Maryland's Patapsco Guards, participated in a rally in the hospital's mess room, during which the majority of those presented expressed their support for, and formally adopted, a resolution from hospital patients which s... |
why wouldn't this troll comic work? | Because water only gets sucked up a vacuum by about 10 meters/32 feet.
The reason things move in a vacuum is because there is a pressure differential. The water is being pushed "upwards", opposing the force of the atmosphere pushing down on it, enough to rise about 32 feet, and so removing the pressure of the atmosphere on the water causes it to rise to that level and then stop. | [
"One of the most widely-used rage comic faces is the trollface, drawn by Oakland artist Carlos Ramirez in 2008. Originally posted in a comic to his DeviantArt account Whynne about Internet trolling on 4chan, the trollface is a recognizable image of Internet memes and culture. Ramirez has used his creation, register... |
why do people discover partial fossils, not complete ones? | Well, it takes a very specific set of circumstances for fossils to form. The specimen needs to be covered up completely, rapidly, and permanently. Those conditions are often met in violent and turbulent environments such as mudslides, floods, volcanic eruptions, etc... So, very often you end up with the specimen in a moving and changing mass of mud, silt, or ash, and it can relocate different parts of the specimen to different areas altogether.
Add on to this situations where scavengers may tear apart the carcass before it's covered up, carry pieces away, etc...
It's a rare treasure to find nicely preserved fossils in one piece, with all the violence and chaos they are often associated with. | [
"Because fossils from the formation are usually retrieved by local people who are untrained as geologists, it is difficult to know the exact provenance of many of them. For this reason, the provenance of a fossil from the Ifezouane and the Aoufous Formations is not generally specified; in any case the two formation... |
How close did the UK really come to capitulation to Nazi Germany in May 1940? | Some historians would argue that Hitler had no interest in taking Britain. He long admired the British, at one point he even offered them control of the seas while he expanded into Eastern Europe and Russia.
On top of this, the Germans did not have the capability to invade Britain even if they wanted to. One of the major preconditions to them invading the mainland would be both naval and air-force superiority, which simply was not possible. Couple this with the logistical issues involved with this sort of invasion, and the previous points, it was never going to happen. Hitler expected the British to "sue for peace", which they didn't.
So, I do not believe the British ever truly were in a position where they would have needed to surrender. I do not think it is as close as it has been dramatized for decades after. | [
"Britain and France were anxious to prevent a Nazi takeover of Scandinavia that would greatly reduce the effectiveness of the blockade and secure indefinite supplies of the iron ore. Such a move would also provide the Germans with many more sea ports and bases from which they could fly bombing and reconnaissance mi... |
if it takes years of study to become a lawyer and practice law, and many more to potentially ever become a judge, how can regular people be expected to know what any of the laws are so as not to break them? | It's for this very reason that you should not under any circumstances speak to the police, assuming you live in a country where you are free to do so. Exercising your right to avoid self-incrimination is extremely important, since in the process of attempting to exculpate yourself from one crime you my implicate yourself in another.
It's also probably a good idea not to be very vocal or obvious about behaviors which may be legally sketchy, which is why I am always floored at people openly flouting their drug use on /r/trees. Whether or not you believe the law is wrong, you are still providing concrete evidence of your illegal activity.
> Also, if it takes years to practice law, why does it take relatively very little to enforce the law at gunpoint as a police officer?
I assume you are asking: "Given the breadth of legal code, how is a shallow understanding of it sufficient to become a police officer?"
Although police are required to have a fairly good understanding of the law (particularly laws which govern the behavior of the police!) the average cop stopping you in traffic is highly unlikely to, for example, arrest you for violating the [Lacey Act](_URL_0_) and transporting certain species of fish or wildlife across state lines. So cops are likely to prosecute you for illegal behaviors they are aware of. However, a DA or other prosecutor may determine that they can prosecute someone using a more obscure law, and they will direct the police officer to arrest that person. | [
"Judges follow a distinct career path. At the end of their legal education at university, all law students must pass a state examination before they can continue on to an apprenticeship that provides them with broad training in the legal profession over two years. They then must pass a second state examination that... |
hypothetically, if the trillion dollar deficit were paid off, who would be getting paid off? | Your mommy bought you a U.S. Savings Bond when you were born.
That means she gave the U.S. government $1,000 back then. In exchange they will give her $1,104 later.
That $1,000+interest is the *debt* that the government owes. They owe that money to your mommy, and anyone else who bought U.S. Savings Bonds.
Some other people who bought U.S. Savings Bonds:
- my mommy
- daddy's work
- China
**Edit** i a word | [
"If it so chose, the government could say it was taxing you $1,000 this year and also, this year, borrowing $1 trillion from you for, say, five years, making a transfer payment to you this year of $1 trillion, and taxing you in five years an amount equal to principal plus interest on the $1 trillion and using it to... |
What is the minimum amount of organs required to sustain a human life? | Can you clarify what you mean by that?
Some organs you can do without entirely and live (ie spleen, tonsils) though there may be health issues to a greater or lesser extent
Other organs you need close to 100% of (ie the heart)
Other organs you can lose a large portion of, depending on WHICH part it is (ie you can lose most of your cerebral cortex of the brain and live (as a vegetable, but still alive) but you would die pretty quickly without a medulla oblongata)
Other organs still you can lose a portion of and survive. For example, you need ~25% of your total kidney volume working, ~15-20% of your liver, ~30-40% of you small intestine, one adrenal gland, etc
| [
"In Niven's universe, the technology to indefinitely sustain any human organ outside of the body was developed in the early 21st century, greatly simplifying organ transplants. This led to the creation of \"organ banks\" which, in theory, one could use to extend life indefinitely so long as a compatible organ had b... |
Was 'The Pale' ever located in southeast Ireland? | You can't both ignore the legend and notes and still interpret the map. The map is of viking settlements in Ireland around 850 AD. The area ringed with yellow dots shows the area that was under viking control during that time. It would be completely irrelevant to "the pale" as designated in 1541. Except for the general shape of Ireland and the location of Dublin, Wexford and Waterford.
The professor is indeed pointing at an area that would be part of "the pale" in 1541. Though he chose a very poor map to use to represent it. [Here is a much better map](_URL_0_).
If you are actually discussing Vikings and Ireland in 850 the term "The Pale" would be relevant, if slightly confusing, to describe areas solidly under viking control. In modern usage "the Pale" can be used to describe any controlled or "civilized" area surrounded by a less civilized or anarchic area which would be "beyond The Pale." | [
"The Pale was a strip of land, centred on Dublin, that stretched from Dundalk in Louth to Bray in Wicklow and became the base of English rule in Ireland. The Norman invasion of Ireland, beginning in 1169, brought much of Ireland briefly under the theoretical control of the Plantagenet Kings of England. From the 13t... |
How come Ireland got christanized so early? | First, while, yes, the majority of Ireland was converted by the end of the fifth century, early Irish Christianity was **super weird**. Very little earlier mythology seems to have been completely abandoned, although the Irish did try to claim some *romanitas* by insisting that the founder of the "Irish race" was a Roman by the name of Mil, that is, *Militus*, that is, "Soldier". Irish saints are particularly fantastic, and behave much more like demigods than the models of sanctity you find on the continent. Continental hagiography (stories of saints) was very concerned with holiness and piety. Irish hagiography consists of a whole lot of cursing and anathematizing with a couple miracles thrown in for good measure. It is extremely unwise to piss off an Irish saint. As one of my compatriots said when we were discussing this post, "Most of St. Patrick's *vita* (life story) is him killing wizards with magic Jesus power."
Second, Irish missionaries didn't *Christianize* Europe, they *monasticized* it. Europe, at least within the former boundaries of the Roman Empire, was certainly Christian, and even England and Scotland were reconverted after an Anglo-Saxon interlude starting with the mission of St. Augustine of Canterbury sent by Pope Gregory I in the first decade of the 600s. Wales is a slightly different case due to its proximity to Ireland and the frequent travel between the two areas. In fact, when the Irish monks began expanding outward, first in Wales in the sixth century and then into England in the seventh, they were found to have particular doctrinal deviations from Roman practice, specifically with the proper way to calculate the date for Easter.
The real expansion of Irish monasticism came with the foundations of the abbeys of Luxeuil (ca. 590s) and Corbie (ca. 660) in modern-day France. These served as the foundation for the revitalization of western learning after the collapse of the western Roman Empire. Almost every known script in Europe during the seventh and eighth centuries was derived from those used in the *scriptoria* of Luxeuil, Corbie, and Benevento, all of which were Irish foundations, and whose scripts were themselves of Insular extraction. | [
"Following the English Reformation, the reformed church in Ireland was established by decree of the Irish Parliament to become the state church in the Kingdom of Ireland as the Church of Ireland, taking possession of most church property (and so retaining a great repository of religious architecture and other items... |
Is there a reason why radio towers aren't used for wifi? | Radio towers (specifically, cell towers) are certainly used for *wireless Internet*. It's just called GPRS or HSDPA or 3G or 4G or what have you. "Wi-fi" (that is, IEEE 802.11 wireless LAN) is optimized for local area usage and would not be a good choice for long-distance data transfer. Of course, as the number of users per tower, and the distance to the tower, are both much higher than with Wi-fi, you can't except the same sort of speeds. | [
"Also some radio towers were so built that they can be used apart from their function as transmitting tower also as observation tower. A condition for this is a sufficiently stable construction, which permits a permanent safe visitor entrance without interruption of the transmission services. This is the case for t... |
what happens if an individual can’t pay a large fine? | They probably cant.. theyll set u up w a payment plan or they can garnish wages, put a lien on your house, even put u in jail.. theyll get their money | [
"The person who is punished with a fine is responsible for giving accurate information concerning their income. Lying about one's income (, ) is a crime punishable with a fine or up to three months in prison. The police can, however, access the taxation data of Finnish citizens and permanent residents via a real-ti... |
When did the practice of attaching genders to words begin? | You might try /r/linguistics! | [
"A system of grammatical gender, whereby every noun was treated as either masculine, feminine or neuter, existed in Old English, but fell out of use during the Middle English period. Modern English retains features relating to natural gender, namely the use of certain nouns and pronouns (such as \"he\" and \"she\")... |
Was there any equivalent to a homicide detective in ancient Greek and Roman times? Are there any surviving "detective stories" from those times? | What we *do* have is a fair amount of forensic oratory, most famously Cicero in Rome and the [canon of ten](_URL_1_) in the Greek world.
Some of these are like detective stories working backwards; evidence is presented rather than found. Unlike detective stories, these are real, and these speeches were composed and delivered by real people in real courts about about real crimes...probably. In a lot of cases we don't know the outcomes of the trial or truth of the matters at hand, which I personally find both fascinating and frustrating.
[Lysias 1](_URL_0_) is short and famous. It's got adultery and murder and everything you could want. | [
"Ancient epic poems such as the \"Epic of Gilgamesh\", Homer's \"Odyssey\" and the \"Mahābhārata\" may have used similar narrative techniques to modern thrillers. \"The Three Apples\", a tale in the \"One Thousand and One Nights\" (\"Arabian Nights\"), is the earliest known murder mystery with multiple plot twists ... |
why do current tv's still play static sound if there is no channel? | It's fake static. On many TV models if you look closely enough you can see that the "static" is a looped animation with just a few frames showing a simple white and black geometric pattern.
It's a great example of [skeumorphism](_URL_0_). | [
"Many modern digital television receivers, such as standalone TV sets and set-top boxes use sophisticated audio processing, which can create a delay between the time when the audio signal is received and the time when it is heard on the speakers. Since many of these TVs also cause delays in processing the video sig... |
Has there ever been black Roman Senators in Roman Republic? | Just to clarify, do you mean specifically someone with Sub-Saharan origins or anyone with skin much darker than the average Roman? | [
"During his dictatorship, Caesar extended full rights of Roman citizenship to ethnically Celtic Cisalpine Gaul (northern Italy), and filled the roll of the Roman senate with controversial appointments that included Cisalpine and possibly a few Narbonese Gauls. Although accusations of degrading the senate with unciv... |
why do you experience withdrawal from opiates but not from orgasms? | Opiates hack the brain's normal chemistry, forcing the brain to do things it's not designed to do. Chemical addictions trick the brain into thinking the drug is necessary to continue to live, whereas orgasms are a normal bodily process. Opiates and amphetamines and cocaine are also much more intense than an 8 second orgasm, flooding the brain with more chemicals than usual. Upsetting this balance has consequences. | [
"This learning process has two parts. First, opiate users must connect their drug withdrawal to their use of the drug, which is something that individuals exposed to opiates in hospital settings are more likely to do. When withdrawal is interpreted as a form of addiction, the perceived (and felt) need for more drug... |
It seems like multiple large Christian sects in colonial America considered dancing to be evil. Where did this view of dance come from? What happened to it? | Follow up question: did any of these people feel the same about instruments? I was raised Church of Christ and dancing wasn't allowed, and instruments weren't allowed in the church (on your own time was fine, but I think we were pretty liberal there) | [
"Dance has had a chequered history within Christianity. Many records exist of prohibitions by leaders within most branches of the Christian Church, for such reasons as the association of dance with paganism, fears relating to sexuality, and a Greek-influenced belief in the separation of soul and body.\n",
"Variou... |
When did contractions like "won't" and "can't" start being used in the English language? | You may also want to try the linguists in /r/linguistics or /r/AskSocialScience or in /r/Etymology. | [
"A reasonable surmise for why \"faw\" and \"law\" were substituted for \"fa\" and \"la\" can be offered, based on the history of the English language. Until the twentieth century, English had no words ending in . Words ending in , however, have always been abundant (\"paw\", \"caw\", \"thaw\", \"saw\", \"Shaw\", \"... |
Is it possible to breakdown CO and/or CO2 into carbon and oxygen? | You can turn 2CO into 2C + O2 but it takes energy. | [
"At present, only schemes isolating fossil CO from natural gas actually use carbon storage, (e.g., Sleipner gas field), but there are many plans for future CCS schemes involving pre- or post- combustion CO. There is also the possibility to reduce the amount of CO in the atmosphere by using biomass to generate power... |
What were the chances of surviving the entire Great War? | For a related question, see [What were your odds of surviving "going over the top" in a WWI trench?](_URL_0_) with a guess at the odds by /u/DuxBelisarius. | [
"The losses of the century of war were enormous, particularly owing to the plague (the Black Death, usually considered an outbreak of bubonic plague), which arrived from Italy in 1348, spreading rapidly up the Rhone valley and thence across most of the country: it is estimated that a population of some 18–20 millio... |
what is the purpose of a dentist teeth cleaning appointment? what do they do that i can't do at home brushing my own teeth. | Clean a lot more thoroughly, get rid of plaque, tartar and the sort. Generally flossing once a day and brushing once a day PROPERLY will prevent these build-ups and prevent gingivitis and other forms of gum disease, but for most people they aren't perfectly thorough. Also, it's good for the to check the health of your teeth and gums, since a lot of people are probably unaware of what most abnormalities may look like. | [
"The purpose of cleaning teeth is to remove plaque, which consists mostly of bacteria. Healthcare professionals recommend regular brushing twice a day (in the morning and in the evening, or after meals) in order to prevent formation of plaque and tartar. A toothbrush is able to remove most plaque, except in areas b... |
What are this things present on this milky way image ? | 1. Very likely the black spot in the middle of the star is an error of the imaging sensor. Basically the light at those pixel is so strong that it completely overpowered the sensor and it returned an erroneous value.
2. A dense molecular cloud, which blocks most of the light from stars behind it and so happens to not have many stars in front of it. | [
"A photograph of False Kiva by Wally Pacholka, entitled \"A True Image of False Kiva,\" was featured on NASA's Astronomy Picture of the Day (APOD) on September 29, 2008, giving an almost otherworldly view into the Milky Way.\n",
"The Milky Way appears as a hazy band of faint stars. It is the disc of our own galax... |
why do gummy candies become stale? | The same reason anything else becomes stale.
It starts to break down chemically.
All the little bonds holding something together will start to break down.
Typically, there is something breaking down those bonds. It's sometimes bacteria, and sometimes sunlight.
In the case of gummies, what happens is bacteria start to eat the sugar in the gummies, and produce their own waste. As they eat the sugar, they are also breaking down the bonds around them, either through eating them, or putting out waste that chemically breaks those bonds.
What you get, in effect, is a gummy that tastes stale because the sugar has been eaten, and the waste products which are present taste different.
PS: waste products aren't always bad. Alcohol is technically a waste product, but one that everyone enjoys. | [
"Candies spoil more quickly if they have different amounts of water in different parts of the candy (for example, a candy that combines marshmallow and nougat), or if they are stored in high-moisture environments. This process is due to the effects of water activity, which results in the transfer of unwanted water ... |
How far would you have to fall on Mars to reach terminal velocity, and how fast would you be falling? | See [this](_URL_0_). At the top of the page is the derivation of the formula for terminal velocity. And a bit further down there's a handy calculator to give you the terminal velocity. The initial values give 58 m/s for Earth which is pretty much the terminal velocity for the belly-down skydiving position, so the drag coefficient should be good for that. Same values for Mars give 285 m/s.
As can be noted from the derivation of the formula at the top of the page, terminal velocity is proportional to sqrt(surface gravity / atmospheric density). Surface gravity is 0.37 times Earth and atmospheric density is about 0.01 times Earth (note that density is not the same as pressure). That would give 326 m/s. So it may be that the calculator used a bit different value for the density as it can vary quite a bit.
Even at constant acceleration (which it won't be), it would take you more than 10 kilometres of falling to reach the terminal velocity. That big of an altitude difference is going to have a fairly significant effect on the atmospheric density so the drag and thus your local terminal velocity would be changing all the time. That makes the math quite tricky. Furthermore, the terminal velocity starts to be close to speed of sound which will complicate things even more. In any case, it'll take a very long fall before you reach terminal velocity. | [
"Using the figure of 56 m/s for the terminal velocity of a human, one finds that after 10 seconds he will have fallen 348 metres and attained 94% of terminal velocity, and after 12 seconds he will have fallen 455 metres and will have attained 97% of terminal velocity. However, when the air density cannot be assumed... |
does mars (and any other planets for that matter) have plate tectonics like earth? | > I always thought it was something unique to earth due to the water.
No, it is due to having an active molten core. Some moons of the gas giants have molten cores, and basically any planet with volcanoes has tectonic activity. | [
"It is believed that plate tectonic processes could have been active on Mars early in the planet's history . Large-scale redistribution of lithospheric crustal material is known to be caused by plate tectonic processes on Earth. Even though it is still not entirely clear how mantle processes affect plate tectonics ... |
What was the general attitude towards electricity when it was first introduced? | Benjamin Harrison was psi dent when the White House was electrified. Though he was too afraid to turn the lights on and off himself for fear of electrocution. Not the best answer but an anecdote to give you an idea that , like all new technologies, people were suspicious of it. | [
"The convenience and economy of electricity resulted in its rapid adoption once the technical problems of production and transmission of electricity were solved. Electric trams largely replaced animal power and other forms of motive power including cable and steam, in the late 19th and early 20th centuries.\n",
"... |
why does vision in one eye get worse than the other? | If I punch you in the right eye, does the left eye get swollen and puffy? No. Both eyes are under different circumstances, and these affect them individually. | [
"Vision disorder is not the same as an eye disease. Although many vision disorders do have their immediate cause in the eye, there are many other causes that may occur at other locations in the optic pathway.\n",
"Eye injuries, most often occurring in people under 30, are the leading cause of monocular blindness ... |
Why do older commercial buildings (roughly 1880-1920) have such high ceilings? What purpose did they serve? | The first air-conditioning system was made in 1902. Having a high ceiling in a public building would make cooling cheaper if the building only has one floor.
You know if have a 2 story home you turn on the air-conditioning on on the second floor and your whole house cools down? Same concept but with one a one story building. The air in the room would be able to circulate faster and more efficiently.
That's why old Victorian buildings have lots of windows in their rooms.
Plus Virginia and the mid west are warmer than the upper states so heating costs wouldnt be a drawback in the winter if you where a business owner.
(Hopefully this makes sense, my engish isn't 10/10) | [
"Some commercial buildings reflect Italianate or even Victorian styles in their architecture, but many were renovated after High Street was widened in 1920. Buildings tend to be two to four stories high with a storefront at the base, an upper façade, and a building cornice or parapet at the top. Masonry constructio... |
what causes the white substance to form in your mouth when you wake up? | It is dried saliva and mucus. | [
"When there is discharge of thick, cloudy white fluid (wady) (that exits before or after urinating) or unlustful discharge of thin, sticky, white fluid (madhy) caused by play or kissing, it requires ghusl. And wudu. \n",
"When there is discharge of thick, cloudy white fluid (wady) (that exits before or after urin... |
Does THC get Stored in your Body and Released? | No. Since some of the components of marijuana are fat soluble, they do get stored in the body for a relatively long time, but they do not have any noticeable psychoactive effects during that period. It’s not even true for acid either. Acid is water soluble and can leave the body in one day.
I’ve heard this myth so many times (especially that LSD is stored in the spinal cord) but it’s false. I think it started simply because of how powerful the experiences can be. They can leave an imprint on your mind that shows up in the form of flashbacks long after the drugs have left your body. Powerful experiences alone can leave people with PTSD and flashbacks even when no drugs are involved. | [
"Due to substantial metabolism of THC and CBD, their metabolites are excreted mostly via feces, rather than by urine. After delta-9-THC is hydroxylated into 11-OH-THC via CYP2C9, CYP2C19, and CYP3A4, it undergoes phase II metabolism into more than 30 metabolites, a majority of which are products of glucuronidation.... |
Are there documented cases of schizophrenics who hear only positive, encouraging voices? | Studies show two things - that people who cope well with voices tend to hear more positive things (and apparently by focusing on the positive voices, they get more of that and less negative over time), and that there is a cultural component. People in certain cultures tend to hear overwhelmingly positive voices, whereas other cultures experience them as overwhelmingly negative. *Differences in voice-hearing experiences
of people with psychosis in the USA, India
and Ghana: interview-based study* by T. M. Luhrmann et al is just one example study.
Also, I was surprised to find in grad school that there is a subset of the population that hears voices but never develops psychosis or schizophrenia, so that might be a group that would fall into your theory. *Positive and useful auditory vocal hallucinations: prevalence, characteristics, attributions, and implications for treatment*
J. A. Jenner et al talks a little about this. | [
"Another typical disorder where auditory hallucinations are very common is dissociative identity disorder. In schizophrenia voices are normally perceived coming from outside the person but in dissociative disorders they are perceived as originating from within the person, commenting in their head instead of behind ... |
when birds tear into the dirt looking for worms, are they just blindly excavating, or do they have some reason to believe a worm is right there? | Aviary expert here. Birds can tell the sensation of creatures moving beneath their feet. Earth is one of the best conduits of movement, so the vibrations of animals such as worms can be felt through their claws and talons, travelling through their legs and into their bones, eventually vibrating into their skulls. This sensation allows them to pinpoint the movement of any animal, so they can then aim their beaks to strike at the exact moment any creature comes closest to the surface.
TLDR: Yes birds know what they're doing, it's not down to chance. | [
"The worm comes out from his hole and tells the viewers that the bird is trying to catch him every day, and that it's making him a nervous wreck. The worm wants to get rid of the bird, and then he sees a chance: a cat that chased a mouse but failed.\n",
"There are three types of foraging behaviour observed in the... |
Why did Thailand become such a huge centre for tourism? | It's the only country in the region that has favourable conditions for tourism.
* Myanmar - oppressive dictatorship
* Malaysia - Muslim country, which means no sex tourism, and it's more expensive and developed
* Cambodia - the Khmer Rouge fucked it up, it's too poor, it doesn't have the required infrastructure and has a short coast
* Laos - no coast, communist government
* Vietnam - also a communist regime | [
"The tourism industry first truly flourished during the late 19th to early 20th century due to the influx of immigrants from Europe and the United States. It was listed as one of the best countries to visit in Asia aside from Hong Kong and Japan, earning the nickname \"Pearl of the Orient Seas\". The tourism declin... |
Practical filtration method to remove lead from water? | I believe activated carbon filters it well, as long as you remember to change the carbon as needed. The zero water filter system seems to be good and it comes with a conductivity test meter that is easy to use and will tell you when its time to change the cartridge. I don't think the meter is actually capable of measuring trace amounts of lead, it only goes down to 0 PPM, not PPB. | [
"Lead piping is still found in old domestic and other water distribution systems, but is no longer permitted for new potable water piping installations due to its toxicity. Many building codes now require that lead piping in residential or institutional installations be replaced with non-toxic piping or that the tu... |
Was there ever a time when gunpowder and knights took the battlefield together? | You may be interested in some of the threads in the '[Early firearms](_URL_0_)' section of the Popular Questions pages.
| [
"BULLET::::- In 919, the first use of gunpowder in battle occurs with the Chinese Battle of Langshan Jiang (Wolf Mountain River), where the Wuyue naval fleet under Qian Yuanguan defeats the Wu fleet. Qian had used flamethrowers ignited by gunpowder fuses to burn the Wu fleet.\n",
"This battle is of additional not... |
How do we determine that a vaccine for a potentially fatal disease is fit for human usage? Wouldn't there be ethics violations at preliminary stages of testing? | After animal testing shows a promising result, they move on to human testing. The first step is to try it on already infected (and then healthy) **volunteers** to make sure there are no bad reactions to just the vaccine. If that works then they give half of a large *at risk* population the vaccine and the other half placebo. Then they interprete the results over a fairly lengthy time period and determine if it is actually effective (a significant percentage of vaccinated people don't get ill compared to the placebo group).
They never actually give a human the virus to test if the vaccine works, just people who are at risk of catching it.
For example there is a vaccine against HIV that was just cleared for human trials in Canada back in December. [link](_URL_0_).
> The Phase I clinical trial will begin in January using 40 volunteers who already have HIV. That phase will test the safety of the vaccine.
> If all goes well, the next phases of study would test whether the vaccine is actually effective.
> Phase II would measure immune responses to the vaccine in people who are HIV negative. Phase III would test the effectiveness of the vaccine in a larger group of about 6,000 volunteers who are at risk of becoming infected. Half would be given the vaccine and half given a placebo. Participants would then be tracked for three years to see how many in each group become infected. | [
"Concerns about immunization safety often follow a pattern: some investigators suggest that a medical condition is an adverse effect of vaccination; a premature announcement is made of the alleged adverse effect; the initial study is not reproduced by other groups; and finally, it takes several years to regain publ... |
why can phone battery-bars act so erratic? | Can't speak for Android, but for iPhone, you should take it to the Apple Store so that they can replace the battery, usually for free. | [
"A battery indicator is a feature of many electronic devices. In mobile phones, the battery indicator usually takes the form of a bar graph - the more bars that are showing, the better the battery's state of charge.\n",
"BULLET::::- Sometimes, the display lights up for a few seconds and then goes out again. This ... |
what would happen if you brought a really strong telescope to space and pointed it at earth? | Yes to both your questions. See: Spy satellites. | [
"This problem can also be solved without using thermal infrared, by positioning a space telescope away from Earth, closer to the Sun. The telescope can then look back towards Earth from the same direction as the Sun, and any asteroids closer to Earth than the telescope will then be in opposition, and much better il... |
when did the idea of gym begin? | “No man has the right to be an amateur in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable.” -Socrates
The idea goes back a while... | [
"The first recorded gymnasiums date back to over 3000 years ago in ancient Persia, where they were known as \"zurkhaneh\", areas that encouraged physical fitness. The larger Roman Baths often had attached fitness facilities, the baths themselves sometimes being decorated with mosaics of local champions of sport. Gy... |
Do fundamental particles exist in 16 dimensions, but we "experience" them in only 3? How can dimensions be folded up inside other ones? | I can't really comment on the 16 dimensional stuff since I'm not a string theorist, but I have a good analogy to understand the 'curled up dimensions'.
Consider a long string or cable. When you hold it in front of your eyes you can see it has multiple dimensions. There is the length of the string, and there is the roundness to it; as in if you were small enough to be sitting on the string you could move around it in a circular fashion and not just along its length. Hence at that scale you can see there are 2 dimensions to the surface of the string. You could walk in a straight line down its length, or you could turn 90 degrees and walk around the body of the string.
However consider this same string held several feet away from you. If you had never seen this mysterious object before and could only view it from this relatively large distance you would conclude it one has 1 dimension, it only has its length, there is no thickness to the string! That second dimension to the string is 'curled up' at a smaller scale and only by magnifying the string does this new dimension become apparent.
Obviously we cannot possibly understand how these 13 other curled up dimensions would look because we live in a 3 dimensional world, the concept of another spatial dimension is beyond comprehension. However I hope my analogy has helped to understand the idea of curled up dimensions.
edit - wording | [
"The authors discussed the possibility that the Universe has formula_1 dimensions, but ordinary particles are confined in a potential well which is narrow along formula_2 spatial directions and flat along three others, and proposed a particular five-dimensional model.\n",
"In string theory, a model used in theore... |
why is it so hard for smokers to stop smoking? | There is a lot of ritual involved in smoking and a lot of nostolgia for most people that goes beyond the physical addiction.
Many people have their work tied in mentally to cigarette breaks. The stress is the stress of that ritual being disrupted. For a smoker the smoke break is like waiting for Christmas and Christmas comes every two hours. Take that away and it becomes hard to tolerate previously tolerable things.
There is also a sort of fraternity among smokers that you loose. Many people met lots of friend over bumming, giving away cigarettes to others. Smoke breakers usually move in crowds, whether in work or in bars and it is a social network that can get you laid or advance your career (if your boss smokes, if a hot friend of a friend smokes, you get new ways too talk to them.)
Smoking is like a little present you get every day with all sorts of great memories and people attached to it. It's not just raw addiction to the drug that makes people miserable, it is loosing the habit itself.
At least for me anyway. For chain smokers it is probably different or people who can still light up when ever it is probably different. | [
"At Allen Carr Clinics during stop-smoking sessions, smokers are allowed to continue smoking while their doubts and fears are removed, with the aim of encouraging and developing the mindset of a non-smoker before the final cigarette is extinguished. A further reason for allowing smokers to smoke while undergoing co... |
why can american porn websites sell porn by simply asking if people are over 18, when store owners have to ask for id. | Websites "sell porn" by asking for a Credit Card, that is their age verification measure.
If you are asking why you only have to click "I am over 18" to view a porn site, it comes down to business vs burden.
First of all, by requiring you to click to verify you are over 18, the responsibility shifts from the website to the individual, if you are not 18 and you click it, then YOU are the one breaking the law, not the website.
Secondly, it next becomes a question of "how much burden does this place on the producer/seller vs how much it affects their business." For a store owner, simply asking for an ID before purchase does not place much of a burden on that store owner, nor on the individual. Whereas checking an ID online usually involves a Credit Card, which means the site needs to have a secure method to do so, and ultimately having a CC check just to VIEW their products has a negative effect on their overall business (some people would simply look elsewhere to purchase something if they were required to enter a CC just to view the products for sale).
| [
"Almost all licensed adult stores in the UK are forbidden from having their wares in open shop windows under the Indecent Displays Act 1981, which means often the shop fronts are boarded up or covered in posters. A warning sign must be clearly shown at the entrance to the store, and no sex articles (for example, po... |
The dawn of the year 2000 was celebrated and feared in many parts of the world. How was the dawn of the year 1000 viewed, in those parts of the world that observed years in this way? | This question pops upon this sub occasionally, and even though more can always be said, you may be interested in checking out these old answers:
* [Was the millennium from 999-1000 ad marked in any special way?](_URL_1_) by u/savvysioux
* [Did people in 999 AD celebrate the new millennium? Were there any doomsday predictions similar to Y2K?](_URL_0_) by u/haimoofauxerre | [
"At sunset on Friday, September 15, 2000, approximately 100,000 spectators and over 12,000 performers celebrated the opening of the 27th Olympiad in Sydney, Australia. Four billion viewers joined them worldwide.\n",
"Rio de Janeiro held a special party led by Gal Costa at minutes to midnight. South Georgia and th... |
Is it possible to only be half down syndrome? | The short answer to your question is that yes, this is possible. It’s called [Mosaic Down Syndrome](_URL_0_), and it occurs in something like 2-4% of Down Syndrome cases. However, I don’t think it has to do with chimerism as you’re describing it. Developing embryos are full of rapidly dividing cells. Full Down Syndrome results when the 21st chromosome (note: not the 13th) is duplicated in either the egg or sperm. Mosaic Down Syndrome occurs when the duplication occurs later in the process, so not every cell contains an extra chromosome. It can result in different expression of the symptoms associated with Down Syndrome. Basically, depending on how that duplication occurred, different parts of the body will contain a higher percentage of cells with three copies of chromosome 21 than other parts. This means the expression of symptoms can be variable and less severe than in full Down syndrome.
That means that while this can occur, it’s not really the result of chimerism. As far as I know, that hasn’t been documented. | [
"Down syndrome (DS or DNS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with... |
losing your voice. | Your throat has a "voice box" made up of bands of muscle called vocal cords. When you talk, the air that passes through your vocal cords sets off vibrations that make the sound of your voice. So if your vocal cords are swollen, they block a lot of the air that would normally vibrate and produce your voice, turning it raspy, or not producing anything at all.
Different causes are
Infection - if you get sick, your vocal cords can swell. Also, if you have asthma, always remember to rinse your mouth out after using your inhaler
Voice strain - too much yelling and screaming can irritate the vocal cords. Use your indoor voice.
Smoking - smoking is bad for more than just your lungs
Acid reflux - stomach acid can wreak havoc on your voice box.
When you get older, it's likely that your vocal cords will start to loosen a get thinner. So, you have that to look forward to, too. | [
"I never lost my voice, but I lost strength in my diaphragm. ... Because of those organic complaints, I lost my courage and boldness. My vocal cords were and still are in excellent condition, but my 'sound boxes' have not been working well even though I have been to all the doctors. The result was that I overstrain... |
how do missile defense systems like thaad and aegis work, and are they adequate against missile attacks? | No one really knows they're effectiveness because they've never truly been tested in a real world attack, and any secret tests aren't going to be released because releasing that information publicly would reveal any weaknesses the systems have, and open up them for exploitation. | [
"The Aegis Ballistic Missile Defense System (Aegis BMD or ABMD) is a United States Department of Defense Missile Defense Agency program developed to provide missile defense against short to intermediate-range ballistic missiles. It is part of the United States national missile defense strategy. Aegis BMD (also know... |
Why does Japan continue to hold animosity towards China and Korea over events that transpired in WWII but doesn't still hate the US for bombing them? | What makes you think Japan holds animosity towards China and Korea? I mean it's obviously true in reverse, but this is the first time I've heard of this.
Also the idea that Japan is a "victim" of WWII due to the atomic bombings is part of the Japanese narrative of the war. | [
"While there was initial hesitance by some in the US government to get involved in the war, considerations about Japan played a part in the ultimate decision to engage on behalf of South Korea. Especially after the fall of China to the Communists, US experts on East Asia saw Japan as the critical counterweight to t... |
How are we able to differentiate religious texts from ancient fiction? | Maybe this is worth it's own thread, but can I extend this and ask how we can distinguish *any* ancient texts? For example, when were the transition points where ancient epics went from preserving history to being entertainment, morality tales, etc.? | [
"On the other hand, the one original text that a scholar theorizes to exist is referred to as the urtext (Biblical studies), archetype or autograph; however, there is not necessarily a single original text for every group of texts. For example, if a story was spread by oral tradition, and then later written down by... |
Quantum mechanics act at a scale of 100 nm or less. Is the transition to the realm of Classical mechanics smooth or abrupt? | > Is the transition to the realm of classical mechanics smooth or abrupt?
Smooth. You can recover classical mechanics from quantum mechanics if you carefully take the limit as hbar goes to zero. | [
"The quantum realm (or quantum parameter ) in physics is the scale where quantum mechanical effects become important when studied as an isolated system. Typically, this means distances of 100 nanometers (10 meters) or less or at very low temperature. More precisely, it is where the action or angular momentum is qua... |
how do organisms without brains (starfish, trees, jellyfish, etc) know how to "do" things like mate, flip over, swim, etc? | Stimuli lead to certain responses which cause changes in the organism's behavior, kind of like how a complicated machine can react in different ways to different switches and levers because they cause a different cascade of actions in the internal mechanism. For example, plants can grow towards a light source because the light stimulates growth on the side of the plant away from the light source, which causes it to bend from that increased growth towards the source. It's very complicated series of events at the biomolecular level that trigger multiple actions and reactions that culminate in some final result. | [
"Several fish species are capable of learning complex spatial relationships and forming cognitive maps. They can orient themselves using multiple landmarks or symbols and they are able to integrate experiences which enable them to generate appropriate avoidance responses.\n",
"Neurons are the cells that transmit ... |
In medieval times balcksmiths' apprentices had to get up well before dawn to get the furnace hot. How was this done before alarm clocks were invented? | First, it's often noted here that the medieval period lasted around a thousand years, so it's hard to generalize about the whole of it.
But, a very short answer would be that the blacksmith's wife woke him up, because as an apprentice he was a part of the blacksmith's household, and the blacksmith's wife would manage that household. The blacksmith and his wife acted in place of parents: they fed him, clothed him, made sure he went to church, and gave him a place to sleep. So, the apprentice likely wouldn't have to wake himself- someone in the household would do that.
Next, how early would the forge have to be lit? If it was burning charcoal, carrying a few embers from the kitchen fire over with some woodshavings would be enough to get blaze going within several minutes. For a coal fire, it could take longer, as coal is harder to start. Still, all in all, lighting the forge wouldn't take that long.
How to tell the time? If a rooster was crowing in the very dim light of dawn, the fire could be lit before there was enough light to get to work. But there were some people who very much wanted to know the time who didn't need to light forges: monks and nuns. Their days and nights were divided up with periodic sessions of prayer, and saying mass. They would be the first to develop mechanical clocks, in the 13th c. , and those clocks would have bells- small ones, at first, but then larger ones. Towns would also gain clocks, and bells.Those clocks were very inaccurate, having to be corrected with a sundial almost every day. But they were quickly set to the task of setting the work day. In 14th c. Brussels there was one bell at dawn, for kitchen maids, one for workers a little later. There would be a bell in the evening for the weavers and spinners to return home, then another a little later for tapestry makers, cobblers and fine metal workers. Eventually, workers would mistrust the accuracy of the clocks that only rang to set their working hours and were controlled by their masters. Fairer was to have the clocks ring at set intervals, first chiming for each hour, later every half-hour and finally every quarter hour. If the blacksmith was in hearing of a monastery or near a town, those bells could set the schedule for his shop.
David S Landes: *Revolution in Time* | [
"The conventional solid metal clothes iron of the 19th century weighed around to and had to be heated on a stove. It was so hot, that often a rag or thick cloth mitt was utilized to touch the metal handle to prevent burning the fingers. Once this all-metal iron cooled down, the ironing job at hand had to stop until... |
how come ads on my computer are based on what kinds of websites i go on, but in cell phone apps all i get are clash of clans ads? | Clash of Clans dumps a metric fuckton of money into advertising for mobile devices, because that's their main platform, and the primary demographic on phones and their target demographic are pretty similar. | [
"Web sites often include the banner or pop-up ads. Social networking sites don't always have ads. In exchange, products have entire pages and are able to interact with users. Television commercials often end with a spokesperson asking viewers to check out the product website for more information. While briefly popu... |
Who are some of history's lesser known/under appreciated martyrs? | Udham Singh. British colonial rule in India was very oppressive to the Indians. Resources were plundered, racial and religious tensions were sparked, and the common folk were getting taxed out of homes, fields, and food. Forcing entire generations of young men to enlist. Revolutionary activity started to sprout up everywhere. Especially in the Punjab.
On April 13. 1919 was the Sikh holiday of Visakhi, celebrating the Birth of the religion. Near the holy Shrine of the golden temple many people had gathered at a popular site called the Jalliawallah Bagh. It was a well that had a courtyard around it, the courtyard was surrounded by walls and gates. Here a couple of folks were set to do speeches and one of the speakers included a revolutionary. The British found out and sent General Dyer and his troops to make sure it wasn't too much of a rukus, Dyer had other plans.
General Dyer had the gates blocked off and his soldiers readied. Without warning he ordered his soldiers to start firing into the crowd. There was mass panic and stampedes yet Dyer didn't order the stop until bullets ran out. Conservative estimates put the death toll around 500, but many speculate the numbers could reach 1,000. Young Udham Singh was in this crowd.
He survived and saw the devastation around him and made it his life goal to get revenge. He figured out that the Punjabs Lt. Governer Michael O'Dwyer had ordered the action. He wouldn't do anything for another 21 years. In these years he would travel abroad to the UK, Nairobi, The US, Canada, France and other countries to build support from the Indians living abroad for the revolution. He was able to help establish funds from abroad and party members creating a whole revolutionary network.
Then on March 13, 1940 he was in the UK. He walked into caxton hall where an East India company meeting was going on. Took out his pistol he hid in a hallowed out bible, and shot O'dwyer. He was arrested and set to trial. When he found out only one was dead he said "Only one dead, eh? I thought I could get more. I must have been too slow. There were a lot of women about, you know". He would be hung a couple months after .Udham Singhs actions would inspire many to strive for freedom including soldiers of the Azad Hind fauj who couples together with ww2, the Indian socialists, and Gandhis actions would lead to India's Independence. | [
"On 26 December 1705, Fateh and his elder brother Zorawar were martyred at Sirhind. Fateh Singh is probably the youngest recorded martyr in history: He knowingly laid down his life at the age of six years. Brothers Sahibzada Fateh Singh and Sahibzada Zorawar Singh are among the most hallowed martyrs in Sikhism.\n",... |
So what's the story behind the European micro-states (Andorra, Lichtenstein, etc)? | This was asked a few months ago and got some pretty good explanations.
_URL_0_ | [
"The European microstates or European ministates are a set of very small sovereign states in Europe. The term is typically used to refer to the six smallest states in Europe by area: Andorra, Liechtenstein, Malta, Monaco, San Marino, and Vatican City. Four of these states are monarchies (three principalities—Andorr... |
How certain is it that Catherine De Medici organized the Saint Bartholomew's Day Massacre? | It will be great to know which books you have read.
The Bartholomew's Day Massacre comprises of several distinct stages, namely the assassination attempt on Coligny the leader of the Huguenots, then the order to murder the Huguenot leaders in Paris, then the communal murder frenzy, and finally the spread of violence to the provinces.
While traditionally there is tendency to blame Catherine de Medici for all three, more recent critical examinations analyze her within the context of the four stages.
1. Did she order the assassination attempt on Coligny? Traditionally, de Medici was blamed as the mastermind, with the support of the Guises. The thinking goes that if it had succeeded, it will have significantly weakened the position of the Huguenots both in France (removing the influence of the Huguenots on Charles IX) and elsewhere (Coligny was said to have designs on French involvement in religious wars in nearby Low Countries). The fact is that the shot was fired from a building owned by the Guise family, who had openly opposed the Huguenots, so it can be argued it made more sense that the Guise faction, *or somebody from their faction,* would be the one to arrange it.
2. Was there a pre-existing plan to murder Huguenot leaders in Paris? It's quite easy to argue that it there was indeed such a plot, then why attempt to kill Coligny ahead of the plan? The argument is then reduced to, who instigated this murder, was it de Medici or was it her son Charles IX? Up to this point Charles IX had ruled under the shadow of his mother Catherine de Medici, so the distinction becomes very, very murky. Most agree that this is an over-reaction due to fears and tensions in Paris and that whichever way this was proposed, de Medici endorsed it. If this was an over-reaction, keep in mind the 4000 Huguenot military contingent stationed outside the city, led by Coligny's brother.
3. Communal violence in Paris. There is less argument here that the pro-Catholic city militia mobilized to secure the streets while the Royal Guards carried out murder of the Huguenot leaders ended up fomenting fear and violence by the Catholics against the Huguenots. Most historians say that the Catholic citizenry was led to believe that the 4000 Huguenot military contingent stationed outside the city was about to strike, when they saw the city militia deploy on the streets. At the same time, there was already much resentment and hatred. Coligny's dead body was mutilated and put on mock trial, as were those of other leaders.
4. What about the provinces? The timing of outbreak of violence tells us a lot. Most did not start until mid-September, weeks after the Paris massacre, some even later. So it was spread of news that fomented them. Further, by this point Charles IX had issued orders that local governments keep the peace, and evidence points to populist uprisings leading to violence. Exceptions, of course, are towns where Protestants were in the majority, such as La Rochelle.
All of the above are mostly based off of Mack P. Holt's *French Wars of Religion*. | [
"The St. Bartholomew's Day massacre () in 1572 was a targeted group of assassinations and a wave of Catholic mob violence, directed against the Huguenots (French Calvinist Protestants) during the French Wars of Religion. Traditionally believed to have been instigated by Queen Catherine de' Medici, the mother of Kin... |
why is that many people (incluiding myself) feel extra motivated to make a big change during night time? | You know you don't have to do it. You know you're about to go to bed and you can put it off for several hours. In the morning you will actually have to face doing the task you set for yourself, and the physical or mental exertion required to do it will outweigh the benefit your late night brain found. A lot of people do it, and the only way I have found of getting over it is to figure out what I really want to treat myself with, go to sleep with these thoughts, and hopefully wake up pumped to get that thing | [
"Baumeister and Vohs have suggested that the disastrous failure of men in high office to control impulses in their private lives may at times be attributed to decision fatigue stemming from the burden of day-to-day decision making. Similarly, Tierney notes that \"C.F.O.s [are] prone to disastrous dalliances late in... |
how knockoff or off brand toys/items are manufactured and actually end up in stores in the west | Most items are made in China. Usually the factory that makes them have all the tools to make more and sometimes after the brands order has been filled they're left with raw resources so they'll make their own batch and sell it to make more money then the brand paid.
Stores are all about making money so if a similar product that consumers want is cheaper cause China was able to spend less making them then the brand did then the store might decide to pick up that product so they can sell it at similar price to the brand name product or even cheaper and make more profit off it than they do for the branded item.
Most products come from the east. China doesn't honor trademarks or copyrights. They can produce similar items cheaper and sell them to stores cheaper who end up making more money. | [
"Australian toy manufacturer Moose Toys have experienced problems with counterfeiting of their popular Shopkins toys in 2015. In 2013, five New York-based companies were accused of importing hazardous and counterfeit toys from China. Merchandise seized included knockoff toys featuring popular children's characters ... |
What would it take to simulate a neural network as complex as the human brain in real time? | Neural Networks don't work the same way as the human brain. We won't be able to simulate the brain until we know how it works, that is the primary barrier to this right now.
A [survey of experts](_URL_1_) puts an estimate of a 50% chance of having Human Level Machine Intelligence by 2040. There is a cool post about AI on [waitbutwhy](_URL_0_)
Quantum computers are fundamentally different than classical computers, they may be good at certain kinds of computations, but if quantum becomes mainstream, it'll be in a hybrid setup to still allow all of the functionality people are used to. | [
"An artificial neural network described as being \"as big and as complex as half of a mouse brain\" was run on an IBM Blue Gene supercomputer by the University of Nevada's research team in 2007. Each second of simulated time took ten seconds of computer time. The researchers claimed to observe \"biologically consis... |
What were hospitality rituals and why were they important in their respective societies? | Hospitality rituals could range from taking one's shoes of before entering a house to something more specific. For instance, the Lakota tribe had an interesting policy where the less words that were spoken, the more polite the guest seemed. It's often hard to actually distinguish between hospitality rituals and general manners, and whether or not these are based off of culture or religion.
For instance, taking of your shoes in some asian countries used to be very important, but with countries like Japan and Taiwan becoming more and more modernized every day, this becomes less common. In Roman times, there was a term called "hospi'tium" which explains that someone who is not directly related to you had greater claims upon the host (you), than those who were blood or affinity related. This was a common practice in Greece as well, although the Roman version was better defined.
There is also an ethinic group located in the Tibet Autonomous Region in China called the Menba. The Menba have a dinner tradition where the host will eat first, and the guest will then be invited to enjoy the food. This because there is an ancient Menba tale that Menba hosts would dip their fingernails in poison, and then put it into the drinks of the guests. The event of the host eating first shows that the food isn't poisoned. It isn't always meant to be taken literally, but it shows that the Menba host was "gracious" enough not to poison his food.
There are also several Russian hospitality rituals, more so than most other countries. This bit comes from _URL_0_...
It was a common attitude to feel happy when having guests. If you were not happy you would receive disapproval from people around you. It was a tradition, when guests were expected to feed their host’s dog before entering the hosts’ house, and hosts usually would scrubb the floor and leave it wet before gusts arrive. Sometimes hosts kept the gates to the house locked very tightly, but when guests arrive they would open the gates widely. This symbolized that guests were so dear to hosts that they would do anything to make guests feel welcome.
One more Russian custom was to meet guests on the threshold of a house with bread and salt in hope that guests take it and walk away, without entering the house. If they took the bread and salt and entered the house anyway (which happened most of the time) then the hosts should have served them very carefully. | [
"Celtic societies also valued the concept of hospitality, especially in terms of protection. A host who granted a person's request for refuge was expected not only to provide food and shelter for his/her guest, but to make sure they did not come to harm while under their care.\n",
"In Ancient Greece, hospitality ... |
how a wave breaks | So if we're talking specifically about beach waves, it's not very complicated. The wave is pushed by the wind toward the beach. But as the water goes up the beach, it eventually reaches a high point, after which it wants to run down into the sea again. Now imagine those two things happening at the same time, except the "running back into the sea" is happening faster than the "getting pushed toward the beach." This means that Mr. Wave is trying to get near the beach, but the water below him disappears, and so he tips over. Of course there are more things happening, but that's more advanced.
The best way to observe this is with animation, and this is the best I found: _URL_0_ | [
"A surf break (also break, shore break, or big wave break) is a permanent (or semi permanent) obstruction such as a coral reef, rock, shoal, or headland that causes a wave to break, forming a barreling wave or other wave that can be surfed, before it eventually collapses. The topography of the seabed determines the... |
how do alarm systems know when a door or window has been opened? | The installers put a pair of tiny magnets somewhere on the door (one on the door, one on the frame.) If you open the door, the system can tell that you’ve separated the magnets because it breaks a circuit. | [
"In one common alarm sequence, the light in a window will flash and a bell or horn will sound to attract the operator's attention when the alarm condition is detected. The operator can silence the alarm with a button, and the window will remain lit as long as the process is in the alarm state. When the alarm clears... |
Why did the Nazis end up annexing the Czech Republic, but only installed a puppet government in Slovakia? | The Czech region of Czechoslovakia (Bohemia and Moravia) developed much differently than the Slovak region prior to their integration in 1918. The Czech lands had been the center of industrialization for the Hapsburg empire, while Slovakia had been cut off from the Czech lands through a process known as "Magyarization" in which the Hungarians (the Magyars) attempted to erase Slovak culture (as well as other cultures within the Hungarian region of the Austro-Hungarian Empire). When Czechoslovakia formed in 1918, the Czech lands inherited 4/5 of the industrial capabilities of Austria-Hungary. One might have expected rapid growth in the Slovak region once the Slovaks were reunited with their Czech cousins in Czechoslovakia, but in fact Prague (the Czechoslovak capital) implemented policy that kept the Slovakia a junior partner in the Czecho-Slovak relationship. For example, of the 100+ generals of the Czechoslovak army on the eve of Hitler's occupation of Prague, only one was Slovak. Many Slovaks resented Czech domination of Czechoslovakia, which became important to Hitler's overall Czechoslovak strategy describe below, but the main point here is that Bohemia and Moravia were valuable prizes for Hitler because of their industrial might while Slovakia lagged far behind.
Of course, Hitler could not occupy Bohemia and Moravia while ignoring Slovakia. Instead, he worked with Jozef Tiso of the Slovak People's Party, a right-wing party demanding more autonomy for Slovakia, to create a new nation to act as an ally of Germany and to provide Germany with a pretext for the invasion of Czechoslovakia. Hitler called Tiso to Berlin and told him that if he did not assist in the plan, then Germany would allow Hungary and Poland, which had already seized areas of Slovakia in the previous months, to completely annex the small nation. Tiso eventually yielded, and although it was not easy to convince his party to make such a declaration, the Slovak parliament finally did issue an official request on March 14 (crafted by Berlin) that Germany move into the Czech lands in order to protect the sovereignty of a newly-declared Slovak state. The following day, Hitler ordered his military to occupy Prague and the Czech lands.
Given that Slovakia was an afterthought in his conquest of Bohemia and Moravia, the creation of a puppet state in Slovakia proved a deft move by Hitler. He created a military ally (and Slovakia did commit divisions to Hitler's upcoming war), invented a pretext for the invasion of Czechoslovakia (however obvious it was), and avoided committing resources to a pointless occupation of Slovakia (until after the Slovak Uprising of 1944).
-----
Chad Bryant, *Prague in Black: Nazi Rule and Czech Nationalism,* Harvard University Press, 2009.
Stanislav Kirschbaum, *A History of Slovakia: The Struggle for Survival,* second edition, Palgrave Macmillan, 2005 (original edition 1995). | [
"Besides violating his promises at Munich, the annexation of the rest of Czechoslovakia was—unlike Hitler's previous actions—not described in \"Mein Kampf\". After having repeatedly stated that he was only interested in pan-Germanism, Germany had now conquered seven million Czechs. Hitler's proclamation creating th... |
why do you think europe as a whole is less obese compared to the states? | America has a culture of sitting. We drive almost everywhere, but in Europe its common to walk.
High fructose corn syrup is lobbied and put in nearly everything you eat and its unhealthy. Seriously, go look at the ingredients at nearly everything in the middle aisles of a grocery store.
Portion control. American portions are enormous. A tiny little Happy Meal from McDonalds is actually a pretty solid meal for a full grown adult.
Our country subsidizes grains and makes food cheap. Cheapest in the world when factored into a percentage of income. But most of the cheap food is the unhealthy stuff.
All that and motorized scooters at Wal Mart. Seriously, how did that become such an acceptable thing?! | [
"Today’s European countries are moving away from this Mediterranean lifestyle and towards a more Western way of life. Indulging on the fast foods and limited daily activity are to blame on for this increase in obesity in Greece . An article from the Associated Press states that obesity rates in some European countr... |
Negative pressure/space? | There would still be a vacuum. A true vacuum means that there is zero matter in the box. Even if you made the box bigger, there would still be zero matter, and thus still a vacuum. | [
"Negative room pressure is an isolation technique used in hospitals and medical centers to prevent cross-contaminations from room to room. It includes a ventilation that generates negative pressure to allow air to flow into the isolation room but not escape from the room, as air will naturally flow from areas with ... |
the difference between rubbing alcohol (isopropyl) and hydrogen proxide | > Are they really that different?
Yes, yes they are. Hydrogen peroxide is H2O2 while isopropanol is C3H7OH. Alcohols generally behave very differently from peroxides.
> Will one help your wound heal faster, or do they both work in a similar manner?
For wound treatment, both work as disinfectants. Hydrogen peroxide might actually slow the healing of wounds by killing new cells and causing scar tissues. In high quantities it can even cause an embolism. Isopropanol is safer, but will sting more as it is an alcohol. Soap and water should be sufficient in most cases anyway. | [
"Isopropyl alcohol is miscible in water, ethanol, ether, and chloroform. It dissolves ethyl cellulose, polyvinyl butyral, many oils, alkaloids, gums and natural resins. Unlike ethanol or methanol, isopropyl alcohol is not miscible with salt solutions and can be separated from aqueous solutions by adding a salt such... |
why haven't new alphabets been introduced in our languages? | Its more like alphabets slowly evolve and change over time, no one does it on purpose and it never happens quickly. But you can see the effects of it over time. Here's a good example: _URL_0_
You probably can't read that. But that's actually English. | [
"Various reforms of the alphabet by scholars of Church Slavonic, Ruthenian, and Russian languages caused the written and spoken word to diverge by varying amounts. Etymological rules from Greek and South Slavic languages made the orthography imprecise and difficult to master.\n",
"BULLET::::1. The reason why Gree... |
Can you catch STDs from a corpse? | Yes. And it would vary with STD. A blood borne STD like AIDS wouldn't last too long, but crabs would hang out for quite a while.
And eww. | [
"Genital ulcers are not strictly a sign of an STD. They can occur in patients with Behcet's syndrome, lupus, and some forms of rheumatoid arthritis (all non-communicable diseases). Genital tuberculosis, often caused by direct genital contact with infected sputum, can also present as genital ulcer.\n",
"Many STIs ... |
how do calculators do math? | They have both hardware and software methods to do various things.
At the hardware level, you are able to implement a lot of basic arithmetic functions in the same way that any computer can. With about 5 minutes of working some stuff out, you can easily design a very basic circuit that will add two numbers. I'm not going to go into any detail about how to do this, but this is trivial for anyone in the field of designing logic hardware. You can do the same thing to create circuits that will subtract, multiply, divide, and some other things, although some of them will be a bit more complex than a basic add circuit.
Once you have the framework for basic arithmetic at the hardware level, you can implement more complicated arithmetic using software. Keep in mind that a calculator is basically a mini computer. It runs an operating system, simple as it is, and executes code in the same way that your Windows desktop does. Thus, an engineer is able to write code to implement other arithmetic.
Your question now may be how can the engineer write code to do things like find square roots or find the values of sin and cos or take derivatives. Well, most of those things have special methods that mathematicians have discovered to approximate them. There is a reason why engineers take calculus!
~~Let me give you an example of this. Let's take approximating sine, for example. There are some nifty things called Taylor series in the world of calculus. A Taylor series, in short, is the representation of a complex function through a polynomial. A special type of Taylor series is called a Maclaurin series, which is what your calculator uses to do a lot of various things. We figured out that the Maclaurin series that represents sin(x) is simply:~~
~~sin(x) = x - x^(3)/3! + x^(5)/5! - x^(7)/7! + ...~~
~~forever and ever, following that pattern. Relatively speaking, we can figure out the value of this polynomial through basic arithmetic. As long as we are able to add, subtract, multiply, and divide, we can calculate this for any input x. And our calculator has hardware that can do that! So whenever we need to get a value of sin(x), our calculator executes some code that performs that math to get an extremely accurate approximation.~~
~~If you are interested in seeing other functions that can be approximated through Maclaurin series (like logarithms and exponentials), check out this link:~~
EDIT: Turns out I was a little wrong with my example of approximating sine. While it possible to use the Taylor series approximation, it is inefficient on a lot of calculators because they can't multiply at the hardware level (instead they only perform repeated addition to achieve the same ends). While this for does work, it isn't the fastest process. Instead, for approximating sine, a lot of calculators use the CORDIC algorithm, which is a relatively complex algorithm to calculate trig functions and some other things more efficiently. It does this by using a combination of logic and arithmetic (adding, bit shifting, etc), lookup tables, and some other stuff.
While this is different than what I originally said, the effort is in the same vain. You come up with a software method that takes advantage of hardware methods (addition, bit shifting, storing predetermined values in memory) to approximate a more complex function.
However, most newer calculators are able to multiply at the hardware level, and so the Maclaurin series approach would be used for those. That would include calculators like the TI-89. | [
"The use of calculators became common in United States math instruction in the 1980s and 1990s. Critics have argued that calculator work, when not accompanied by a strong emphasis on the importance of showing work, allows students to get the answers to many problems without understanding the math involved. However,... |
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