question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
|---|---|---|
Why can't medical scientists collect data from a group of people and use the same human control group for every medical experiment in the future so that participants in a study don't have to risk taking a placebo? | The major issue with that is it wouldn't be a good control *because* of the lack of a group taking the placebo. When they do most trials they do them double blind. Neither the subject nor the doctor knows who is getting the real drug and who is getting a placebo (until afterwards, of course). | [
"In controlled experiments of medical treatment options on humans, researchers randomly assign individuals to a treatment group or control group. This is done to reduce the confounding effect of irrelevant variables that are not being studied, such as the placebo effect. \n",
"In medicine, anecdotal evidence is a... |
Why do lights dim briefly sometimes when lightning strikes nearby? | If lightning hits a power line or transformer, it could greatly increase the voltage of the lines relative to Earth ground, and a lot of equipment connected to those power lines would be damaged. Varisters or Transorbs are places across power line components to protect them form sudden increases in voltage. While these components are acting, they may prevent the normal flow of electricity. | [
"During the American Physical Society's 2014 March meeting, research was provided that gave a possible explanation for the reason why bright lights sometimes appear during an earthquake. The research stated that when two layers of the same material rub against each other, voltage is generated. The researcher, Profe... |
why are animals and fauna no longer as large as they once were? what has changed about our world that mega fauna and mega animals no longer exist? | We don’t *actually* know but some theories are that temperature of the earth was the major factor for mammals getting so big. If the ambient temperature is lower, the heat/energy of a larger mammal is much easier.
For insects (and maybe plants), there was a much higher concentrations of oxygen in the atmosphere that helped produce gigantic bugs (we think) and when birds were getting bigger and preying on them (we think) they started to die off (we think) | [
"A 2019 study published in \"Nature Communications\" found that rapid biodiversity loss is impacting larger mammals and birds to a much greater extent than smaller ones, with the body mass of such animals expected to shrink by 25% over the next century. Over the past 125,000 years, the average body size of wildlife... |
why don't 'unincorporated territories of the united states pay taxes? why aren't they considered a state? | Well in the US we have a thing about taxing people who don't have representation in the body that decides what those taxes are. They aren't states either because the don't want to be, or Congress won't admit them, or both. | [
"Territories of the United States are sub-national administrative divisions overseen by the federal government. They differ from U.S. states and Native American tribes, which have limited sovereignty. The territories are classified by incorporation and whether they have an \"organized\" government through an organi... |
Ku Klux Klan's reaction to Hilter | [From a previous answer](_URL_0_):
So the history of the KKK and the Nazi movement isn't a particularly big one, but given the similarities - being largely centered around ideologies of racial exclusion - it shouldn't be a surprise that they did, occasionally, intersect.
As far as Nazi Germany itself goes, it isn't entirely clear just how aware Hitler and the Nazi movement even was of the Ku Klux Klan. To start, the Klan itself had a very minimal presence in Germany. A Klan inspired group, the Order of the Knights of the Fiery Cross, was founded in Berlin in 1925 by three Americans, but doesn't seem to have been explicitly connected to the American KKK, and its membership seems to have capped at under 400. IT was quite short-lived, and had no real impact, being just one of many small groups that popped up during the Weimar period. Some members likely went on to join the Nazi Party, but there was no direct connection with the NSDAP.
Hitler's associate Ernst 'Putzi' Hanfstaengl claimed that Hitler broached the idea of cooperation with the Klan, but Putzi is not necessarily the most reliable source, as the German-American 'Old Fighter' had a hard fall from grace and later worked for the Americans during the war. Putzi, with his American heritage, would certainly be aware, and others in the Nazi hierarchy made comments on the Klan, such as Alfred Rosenberg, whose Party journal *Der Weltkampf* published several articles which made mention of the Klan in the mid-1920s, but Hitler seems to have left no explicit mentions which would demonstrate his personal familiarity. That said of course, Hitler did make broader public statements which expressed approval for the Jim Crow regime of the American south, and other Nazi publications likewise do disturbingly positively of Southern racism. Grill and Jenkins characterize an article by E. van Elden published in 1927 thus:
> Elden graphically described the burning of a black man who had been accused of raping a white woman in a small Georgia community. The author questioned whether lynching was ever justified and concluded that it was actually essential whenever blacks raped white women. Any other lynching, however, represented only mob rule. Elden easily saw German parallels with the American South because of "the lust of black beasts in the Rhineland." One could not blame southerners, concluded the article, for attempting to protect women from the "moral depravity of Negroes."
So in short, while explicit praise for the Klan was quite limited within the Nazi party, this likely reflects a lack of familiarity, as there was certainly "appreciation" for the kind of extremist racial views that the Klan held. Somewhat Ironically, Americans also saw the similarity, using it to lambast the Klan as the "nearest approach that any American organization has to the Nazi party in Germany", as the Birmingham News wrote in 1933. An important thing to keep in mind though is that by the time when the Nazis rose to power and Americans were paying attention to it... the Klan had significantly collapsed, losing its power through the 1920s and having fairly limited influence in the 1930s. The American South was still *rife* with racism and neck deep in Jim Crow, but many Southern newspapers followed the lead of the Birmingham News, vociferously condemning the Nazi movement in the 1930s as similar to the "extremists" of the KKK, while entirely missing the irony in condemning Nazi Germany's "[denial] to a whole class of its people their equal rights as citizens on account of their Jewish descent" while themselves instituting a regime of racial exclusion against African-Americans. Black publications followed suit in their condemnations of Nazi racial doctrine, but of course took a much more open-eyed stance as they compared it to the situation on their own doorstep, such as with a 1938 editorial in Crisis which stated "The South approaches more nearly than any other section of the United States the Nazi idea of government by a 'master race' without interference from any democratic process."
But, of course, what about the Klan itself? Simply put, the Klan was cautious, but not entirely opposed, at least prior to the outbreak of war, and there was some interaction between the KKK and the German-American Bund, i.e. the American Nazi Party. As noted, the Klan had been in marked decline by the beginning of the 1930s, and some Klan leaders believed that an alliance could help stem its loss of members, and maybe even bring about new growth. Outreach between the two groups was quite slow, but eventually the result of this was a rally held at the Bund's NJ compound 'Camp Nordland' where a joint meeting between members of the Bund and the KKK - bedecked in their "regalia" - occurred on August 18, 1940. The organizers claimed 3,500 attendees, while other estimates claim it was only about 1,000. The KKK participants were a distinct minority of the attendees either way, but certainly numbered at least 100 or so. Regardless of the numbers, the meeting also was emblematic, though, of the decline of the Bund, whose leader, Fritz Kuhn, had recently been sentenced to prison for embezzling Bund funds and tax evasion. So not only did the Klan-Bund combined rally draw protesters who gathered at the camp entrance to picket against both groups, but it also drew protests from within the Bund, as several dozen Kuhn loyalists showed up intent on starting a ruckus over disagreements in leadership, resulting in several arrests for assault.
Regardless though, as for the rally itself, it saw speakers from both groups, with 'Grand Giant of the New Jersey Realm of the Klan', the Rev. Edward E. Young' giving an impassioned speech about the shared values of white supremacy between the two groups, similarly echoed by Bund member, and the principal organizer of the rally, Edward James Smythe, who proclaimed it his "patriotic duty" to effect the meeting of the two groups. Grand Dragon of the New Jersey Klan, Arthur Bell, received particularly great applause when he railed about how the Jews were behind attempts to force the US into the war. Asked later about the rally during a Congressional investigation by Rep. Martin Dies Special Committee on Un-American Activities, August Klapprott, one of the Bund leaders, stated "[O]f course, I welcomed the idea [of] an Americanization rally" which essentially speaks to the general tenor of how the cooperation was viewed at the time by both groups of participants, namely a rally for their views of what America should be - a country for white men.
To be sure though, while that was how it was billed, it wasn't how it exactly went. Both before and after, there was much disagreement within the Klan about whether it was a good idea. As noted before, the 'pro-camp' believed that the alliance would be a good move for retaining membership, and they were willing to accept the veneer of Americanization that the Bund tried to project, but many Klansmen were opposed as they didn't accept it, and were much more favorable to the idea that the German-American Bund was nothing more than an ~~front~~ advocate for a foreign power. The Bund, having many first and second generation immigrants, additionally offended the sensibilities of some Klansmen. At its height in the 1920s the Klan had been quite vocal in opposition to German immigrants, but a decade, and necessity, was breaking down at least some members' opposition, although hardly all, especially in the South, where the largest outcry against the Bund came from, published in the Klan publication *The Fiery Cross*. | [
"The Ku Klux Klan was a secret organization of whites that resisted what they saw as the excesses of Reconstruction. They sometimes terrorized and even assassinated Union League leadership. Founder Nathan Bedford Forrest grew uneasy about the group’s tendency to lawlessness, and disbanded it in the late 1860’s.\n",... |
how are open-world video game maps designed? | They actually do "draw" the world piece by piece. It's usually done by groups of people, not just one dude. They first make a rough terrain curves (hills, rivers, canyons...) then they just polish it till it looks really nice. Then they have to add all the props, like trees, buildings, people...
So yeah, they are actually modeled inch by inch, there's nothing more complicated in it.
Exception could be randomly generated games like Minecraft, where the game continues to load new piecea of world. It's not really random, the blocks are dependent on their neighbours. | [
"Some open-world games, to guide the player towards major story events, do not provide the world's entire map at the start of the game, but require the player to complete a task to obtain part of that map, often identifying missions and points of interest when they view the map. This has been derogatorily referred ... |
Battle of Leuctra - the defeat the broke Sparta's power | **1/3: Historiography**
The Battle of Leuktra (371 BC) is notoriously difficult to reconstruct. As Pritchett once remarked with obvious exasperation, "there are more reconstructions of Leuktra than of any other ancient battle, and the end is not in sight." There are a number of philological and historiographical reasons for the controversy, but the main one is - ironically - that we have so many sources for the battle. Most Classical Greek engagements are known from just one source. For Leuktra, we have four full accounts:
* Xenophon, *Hellenika* 6.4.9-15. This is the only contemporary source, and written by an experienced commander with close ties to the rulers of Sparta.
* Diodoros of Sicily, *Library of History* 15.55-56. Written in the 1st century BC, possibly using the lost work of the 4th century BC historian Ephoros as a source.
* Plutarch, *Life of Pelopidas* 23. Written in the 2nd century AD. Plutarch was himself a Boiotian, and possibly used the lost 4th century BC historical accounts of Ephoros and Kallisthenes.
* Pausanias, *Tour of Greece* 9.13.3-12. Written in the 2nd century AD, presumably based on local traditions.
In addition, there are numerous anecdotes about Leuktra in both Polyainos' and Frontinus' collections of stratagems. Now, if all these sources were complementary, we would know more about Leuktra than about any other ancient battle. But, of course, they're not. They offer completely incompatible accounts of the battle that get more fanciful the greater the chronological distance form the actual event.
* **Xenophon** describes a simple battle in which a deep Theban phalanx preceded by a cavalry screen crashed directly into a shallower Spartan formation, making the allies of both sides irrelevant to the course of the battle. As attrition mounted and key officers fell, Spartan morale eventually broke.
* **Diodoros** has it that the Spartans advanced in a crescent formation, hoping to encircle the outnumbered Theban force. Seeing their advance, the Theban commander Epameinondas deployed his army in echelon to keep his weaker troops out of the fight, and concentrated all his strength on one of the pincers of the Spartan crescent.
* According to **Plutarch**, the Spartans advanced in line, but attempted to extend their line to the right and then wheel inwards to attack the Theban phalanx in the flank. To prevent this, Epameinondas first ordered his elite Sacred Band to charge into the Spartan wing mid-manoeuvre, and then led the main phalanx against their main force as they tried to regain their formation. Plutarch alone mentions the Sacred Band.
What are we to make of all this? For centuries, scholars have recognised that they must choose one account over the others, since they will not coexist. They have offered arguments in favour of all 3 accounts, and their reconstructions of the battle have varied accordingly. I won't bore you with the initial blows of this controversy, which involve a lot of Germans and Gothic script; the key modern interpretation is that of J.K. Anderson.^1
First, Anderson pointed out that Diodoros' account perfectly mirrors the solution offered by Diodoros' contemporary, the tactician Onasander, in the event of encountering an enemy in crescent formation. Since the crescent formation is otherwise unheard of in Classical Greece, it seems all too likely that we should dismiss Diodoros' account as a purely theoretical tactical exercise with no basis in historical reality.
Second, Anderson argued that Xenophon was biased in favour of the Spartans, that he hated the Thebans, and that he was merely writing an apology for the Spartan defeat. He was not the first to assume that Xenophon's account is basically worthless, but he started a trend in recent scholarship (including notable figures like Buckler^2 and Cartledge^3) that starts from the premise that this contemporary source is best ignored.
Third, he made a forceful argument in favour of Plutarch's account. He pointed out that the manoeuvre described in this account is the same as the one the Spartans used to win at the Nemea in 394 BC, and that it is also described in detail in Xenophon's fictional account of the battle of Thymbrara in the *Kyroupaideia*. Of course, Xenophon would not have described such Spartan sophistication at Leuktra, because he wasn't trying to give an honest account; but Plutarch, according to Anderson, preserved the truth. The Spartans were trying to outmanoeuvre the Thebans, but they were caught off guard by Epameinondas' rapid response; they were no match for the combined might of the Sacred Band and the 50-deep phalanx.
This interpretation has remained dominant until very recently. The revolt began quietly with Devine, who pointed out that Xenophon, as a contemporary source, probably should be taken seriously.^4 But his own reconstruction of the battle is completely mad. The case was made much more forcefully by V.D. Hanson a few years later.^5 Hanson showed how the accounts of Diodoros and Plutarch were themselves based on unreliable sources already discredited in antiquity, and stressed that we should trust Xenophon, the veteran mercenary general, to know what he was talking about. Indeed, for all its simplicity, Xenophon's version perfectly explains how the battle was won and lost. Hanson then makes the crucial point that modern authors are probably hesitant to rely on Xenophon precisely because he suggests *the Spartans were beaten by very crude tactics and Epameinondas did nothing new.* Modern scholars have been guided by their assumption that the Spartan defeat could only be accounted for by spectacular tactical innovations. This led them to favour the less reliable accounts of Plutarch and Diodoros over the actually quite blunt and honest picture sketched by Xenophon.
Now, I said "very recently" because it took a long time for Hanson's view to catch on. A lot of scholars probably still favour Anderson and therefore Plutarch; some might even be in the camp of Hammond and therefore Diodoros. But with Hutchinson,^6 Lendon,^7 Wheeler^8 and others now endorsing Hanson's "simple" view of Leuktra, it seems Xenophon and Theban brute force are now gaining ground. It fits much better within the tactical context of 4th century BC Greece than the later accounts. New interpretations of the Sacred Band also support the view that they had no decisive role to play at Leuktra. It would take a lot to persuade scholars to return to accounts that are inevitably later and more derivative.
**References**
1. J.K. Anderson, *Military Theory and Practice in the Age of Xenophon* (1970)
2. J. Buckler, 'Plutarch on Leuktra', *Symbolae Osloenses* 55 (1980), 75-93
3. P. Cartledge, *Agesilaos and the Crisis of Sparta* (1987)
4. A.M. Devine, 'EMBOɅON: a Study in Tactical Terminology', *Phoenix* 37 (1983), 201-217
5. V.D. Hanson, 'Epameinondas, the Battle of Leuktra (371 B.C.) and the "Revolution" in Greek Battle Tactics', *Classical Antiquity* 7 (1988), 190-207
6. G. Hutchinson, *Xenophon and the Art of Command* (2000)
7. J.E. Lendon, *Soldiers and Ghosts: A History of Battle in Classical Antiquity* (2005)
8. E.L. Wheeler (ed.), *The Armies of Classical Greece* (2007)
| [
"During the Corinthian War, Sparta faced a coalition of the leading Greek states: Thebes, Athens, Corinth, and Argos. The alliance was initially backed by Persia, which feared further Spartan expansion into Asia. Sparta achieved a series of land victories, but many of her ships were destroyed at the battle of Cnidu... |
why is drinking sea water lethal, but soups with massive sodium content are acceptable? | Because soups with massive sodium content are still much, much, ***MUCH*** less salty than sea water. That's not to say they're healthy, though, Americans eat way too much sodium as it is.
Edit: in fact, salt water is so salty, that getting a mouthful of it is known to cause immediate vomiting. It's happened to me before. We in the SCUBA diving community call it "feeding the fishes". (and yes, when it happens, fishes often crowd around your face to eat your vomit. It's disgusting and cool at the same time) | [
"Many canned soups, including Campbell's condensed and chunky varieties, contain relatively high quantities of sodium and thus are not desirable for those on low-sodium diets. However, Campbell's Chunky, Healthy Request and other soups, as well as their V-8 and Tomato juices, are claimed by Campbell's to contain re... |
How genetically dissimilar are different dog breeds? Could a Sheppard donate a kidney to a Lab? Could a Great Dane donate blood to a Chihuahua? | Great question! Both cats of different breeds and dogs of different breeds are of the same species (*Felis catus* and *Canis lupis familiaris* respectively). As such, they can act as donors within their own species of both blood and organs.
That being said, there are things that you have to watch out for.
1. When it comes to dogs, with organs that can vary drastically in size between breeds, you have to select animals that are of similar dimensions.
2. As in other donors/recipients it would be nice to try to match [MHC I](_URL_0_) between the donor and the recipient. This is the molecule on cells that tells the immune system that a cell is either self or non-self. Matching makes the organ less likely to be rejected. This is likely not going to happen since it would be very expensive and time consuming, and most veterinary medicine neither has the time nor the money. As a result, the recipient animal will have to be put on [immuno-suppressive drugs](_URL_1_) for life. This procedure takes place in the case of [feline renal transplantation](_URL_3_) at the University of Pennsylvania.
3. Dogs can, and often do in emergency trauma cases, receive blood transfusions! They have a set of their own [blood types](_URL_2_), although if the animal has never gotten an transfusion before and it is an emergency, any type will do. After that initial transfusion, antibodies toward the new blood type are formed, and subsequent transfusions must be made with matching blood type.
I hope that answers everything! Source: the above references, and I'm a 2nd year student of veterinary medicine. | [
"Ullmann was a pioneer of renal transplantation research. In 1902, he performed the first successful renal autotransplantation in a dog. Reportedly, the kidney remained functional for five days. Soon afterwards, he was unsuccessful in trying the first renal xenotransplantation (cross-species transplant) between a g... |
why is it that whats politically correct sometimes isn't the same as the opinion of the majority? | Let's start off with a statement, society evolves towards increased compassion for all members of society. On the forefront of that evolution is radical thought that tends to be less judgemental of others. For example, native Americans are equal humans (1920s), women are equal humans (1940s), Blacks are equal humans (1950), Gays are equal humans (1990). The population in general is conservative, they find radical though scary. Thus social regulation has to be created to help move on society (equal opportunities acts, etc.) This is called "political correctness" in that the politics of the time have moved on past the status quo of the population.
Of course, there are always people looking to mock evolution of society because it scares them a lot. This is usually because they are in some way inadequate and need oppression of sectors of society in order to keep their inadequacy "punching above their weight". These people use "political correctness" as a mocking term. They are trying to undermine a fairer society so that they don't need to address their own failings.
So, to answer your question, leaders need to create political correctness in order to evolve our society forward to a better place. By that definition PC will always be pushing the majority | [
"By solely acknowledging voting patterns, one cannot make an accurate conclusion as to the presence or absence of political polarization, because in the United States, there is a limited number of presidential candidates in the two-party system. To assume that the majority of voters are mostly or completely in agre... |
How can paper be sharp enough to cut through human skin? | Microscopically the edge of paper is like a saw blade rather than a razor, it has to slide along the skin in order to make the cut.
| [
"BULLET::::- Plastic blades are usually not very sharp and are mainly used to cut through vegetables without causing discolouration. They are not sharp enough to cut deeply into flesh, but can cut or scratch skin.\n",
"A clean cut through a thick stack of paper cannot be made with a traditional inexpensive sickle... |
is gordan ramsay actually a good chef? | There's not really an objective way to answer your question, tastes can certainly vary. His restaurants have earned 16 Michelin stars, which are pretty sought after, so you may take that as an endorsement. At least some of these stars have been earned while he has been head chef at a location. He's undoubtedly technically skilled. | [
"Ramsay's reputation is built upon his goal of culinary perfection, which is associated with winning three Michelin stars. His mentor, Marco Pierre White noted that he is highly competitive. Since the airing of \"Boiling Point\", which followed Ramsay's quest of earning three Michelin stars, the chef has also becom... |
was Nero (the emperor) crazy from the beginning ? | I wrote [an answer](_URL_0_) to a similar question a few months back. The tl;dr of it is that Nero likely never was crazy, he was just really unfit to be an emperor of Rome. | [
"BULLET::::- \"The Adventures of Nero\": The title character Nero is named after Nero. In his first debut appearance the character believes himself to be the Roman emperor after drinking poisoned beer. Later he regains his sanity, but all characters kept referring to him as \"Nero\" from that moment onwards. In the... |
Are there any studies that show other species to be capable of lying/dishonesty? | This was a guestion in AMA with Sir David Attenborough:
In all your time of shooting nature programs, what is the most human thing you have ever witnessed an animal do?
A chimpanzee does in fact tell lies. If you can believe that. Also, when some Colobus monkeys find a very precious piece of food, it calls the alarm call that it would make if a snake were to arrive, and all the other monkeys run away and it gets the food. | [
"Researchers from the University of the Free State (UFS) in South Africa, while observing gelada during field studies, discovered that the monkeys were capable of 'cheating' on their partners and covering up their 'infidelity'. A non-dominant male would mate surreptitiously with a female, suppressing their normal m... |
I was spinning in my chair today (question about centripetal and -fugal forces.) | The construction of the inner ear (see [semicircular canals](_URL_0_)) allows you to detect the direction of acceleration. Once the turbulence in your inner ear settles, you will perceive yourself to be at rest as long as you don't feel acceleration, ignoring the sorts of small details mentioned in other comments. | [
"In Newtonian mechanics, the centrifugal force is an inertial force (also called a \"fictitious\" or \"pseudo\" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis passing through the coordinate system's origin and parallel to the axis of rotation... |
In the 1970s UK sitcom Fawlty Towers, a few guests are shown to live permanently at the hotel. Was this common during this time? What factors led people to choose life in a hotel, and did this have a long history? | Hotel living has a *long* history--the *Eloise* books by Kay Thompson are probably the most famous example. I can talk a little bit about some of the earlier history, specifically, hotel living in Paris!
*(This is adapted from several of my earlier answers with some new stuff thrown in).*
Paris is the City of Lights...but it sure wasn't very lit in the late 19th and early 20th centuries, when it had one of the lowest electrification rates of any major city. It also had one of the worst housing situations in the Euro-American world, especially given the *doubling* of the population between 1871-1920. As you can imagine, this burden fell mostly on immigrants and the lower classes.
Attempts at mitigating the horrific conditions, like establishing factories in the suburbs instead of the city (with extensive slum settlements building up around them), or even some government-sponsored housing projects, could never come even close to meeting demand.
As a result, Paris even more so than other cities developed a system of "hotels."
But these are not what we often talk about in the U.S. at the time--the de facto boarding houses for single men where housekeepers would take care of "women's work" for them, or for single working women where they could be watched and "stay respectable."
No, these were tenements with really lousy--metaphorically and often literally--living conditions.
The *hotels garnis* resembled very lousy--metaphorically and often literally--versions of our hotels today: single-room "apartments" with no kitchen. (Although, sometimes also no bathroom). They even often had a restaurant on the ground floor. So when you hear about Simone de Beauvoir and Jean-Paul Sartre spending all their time in cafes...well, guess what.
Parisian hotels were filled with transient workers, new immigrants, basically the young and poor--single women and men, single women with children, young couples.
To give you an idea of the conditions of the worse of these: Helmut Gruber describes housing for the working women of Paris (in the slum tenements known as "insalubrious islands" and in the hotels garnis) as:
> The majority lived in domiciles lacking indoor water, heat, electricity, daylight, and ventilation, and they shared slovenly sanitary facilities...It is difficult to imagine where and how they actually washed their clothes, and how often...The absence of hygiene is evident from reports by teachers of the lack of cleanliness of children and from the high death rate from tuberculosis and pulmonary disease.
But despite these conditions, hotel residents weren't all just sitting around cafes philosophizing. Gruber also notes that tenement and hotel residents were *very* active organizing in order to keep rents down to something they could afford on their salaries, protesting to the government to enforce protections for them against landlords/slumlords.
~~
*We used to have a really great answer on the U.S. end of things I mentioned, but that user seems to have deleted it.* | [
"The hotel's heyday was in the early 20th century, when it played host to royalty, politicians and film stars as well as staging many dinners, concerts and dances in the Grosvenor Suites. King George VI, Winston Churchill, Neville Chamberlain, Charlie Chaplin, James Cagney and Joe Louis attended functions or stayed... |
Why did 20th amendment required 3/4 of the states to be ratified? | I think a couple of things are getting mixed up here.
For the process of amending the Constitution, as laid out in the 1787 document (Article V), here is the original language:
> The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Constitution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as Part of this Constitution, when ratified by the Legislatures of three fourths of the several States, or by Conventions in three fourths thereof, as the one or the other Mode of Ratification may be proposed by the Congress; Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.
So what that means: first a Constitutional amendment needs to be passed by two thirds of each house of Congress, or two thirds of the states need to call for a Convention to propose amendments.
However, once an Amendment passes this stage, it needs approval by three fourths of the states. This can either come in the form of the state legislatures voting for the amendment, or through special state conventions elected to vote for or against the amendment.
Every single constitutional amendment to date has been passed through Congress. All of those amendments bar one (the 21st Amendment, repealing the 18th Amendment) were approved by state legislatures, rather than state conventions.
The method of proposing amendments through a Convention requested by at least two thirds of the states has to date never actually been attempted, and it's not very clear just how this process would even work in practice.
The notable feature of Section 6 is less the ratification requirement of three fourths of the states, which is constitutionally-required, but the deadline for ratification of seven years. This is a feature for constitutional amendments that was introduced in the 20th century - the 18th, 20th, 21st and 22nd Amendments have deadlines in the text of the amendment, and the 23rd, 24th, 25th and 26th amendments have deadlines in the introductory text of the amendment as passed by Congress. The 27th Amendment notably had no deadline as it was originally approved by Congress as part of the package of Amendments known as the Bill of Rights, was ratified by a few states, and then largely left "dormant" until being rediscovered by an undergraduate student at University of Texas Austin, Gregory Watson. His paper on the amendment got a C from his TA, but ultimately his research led to a campaign to get the amendment ratified by three fourths of the states, which happened in 1992.
So why time limits? Richard F. Hamm's *Shaping the Eighteenth Amendment* gives some clues as to why this particular amendment was the first one to have such a rider successfully attached. Opponents of Prohibition had originally wanted a two year grace period for implementation after ratification, and/or compensation to brewers and distilleries - Congress eventually came up with a one year period. Opponents also saw a seven year window for ratification as "fair" - the original proposal from then Ohio Senator Warren Harding was for four years. It was basically a means of weakening attempts to block the passage in Congress by providing a window of time to prevent passage in the states.
Of course, it's not super clear just how constitutional or binding time limits are. In 1921 the Supreme Court heard *Dillon v. Gloss*, in which, to make a long story short, an arrest under the Volstead Act (enforcing alcohol prohibition) was contested under the pretext that adding a time limit to the 18th Amendment invalidated the whole amendment process. The Supreme Court basically said: "Time limits are fine, we guess." But notably the 18th Amendment had been ratified by the necessary states before the time limit was up, so it wasn't necessarily a very tough call to make.
Of course there is a potentially interesting case to be made about the legality of time limits because of the Equal Rights Amendment, passed in Congress in 1972 with a seven year limit, that in 1978 was extended to a ten year limit (ie, to 1982). This ten year limit was set by a resolution voted on by a simple majority, and in any case due to increasing political resistance, it was not passed by the necessary states by 1982 (although four states rescinded their ratifications in the 1970s, and this isn't something provided for or forbidden in the Constitution). Of course several states have since ratified the amendment, with Illinois being the 37th in 2017. If a 38th state ratified the amendment - well, it's not 100% clear just what would happen.
To go back to Article V, note the two exceptions to the amendment process: no amendment could ban the slave trade before 1808 (when Congress was constitutionally allowed to ban it), and no amendment can change the number of Senators each states has (it's theoretically an un-amendable part of the Constitution, unless each State agrees to it). | [
"To become valid as part of the Constitution, the Twenty-third Amendment needed to be ratified by the legislatures of three-quarters of the states (38, following admission of Alaska and Hawaii to the union in 1959) within seven years from its submission to the states by Congress (June 16, 1967). President Eisenhowe... |
What do we know about the fowl of the roman empire? | Fortunately there is a cook book from the late 4th or early 5th century CE. That book is Apicius. Keep in mind these recipes would have been for the upper class of society. There is a section on fowl which includes chicken, pheasant, goose, duck and doves. It also includes ostrich and peacock along with a few others. If you'd like you can check out the book at the following link from project Gutenberg.
_URL_0_
You are also correct in turkey being a recent addition to European cuisine. The turkey is among one of the New World foods. | [
"Caltrops were known to the Romans as \"tribulus\" or sometimes as \"murex ferreus\", the latter meaning 'jagged iron' (literally 'iron jagged thing'). They were also used in the Battle of Carrhae in 53 BC.\n",
"Pliny reported in \"Natural History\" that a grub which he gives the name \"cossus\" was considered a ... |
the plot of the legend of zelda series | It's hard to attribute a chronology to Zelda, though some aspects can be assumed ( like Wind Waker seems to be a post-apocalyptic Hyrule, the Great Sea having flooded the world ), and each of the games has similar themes for the most part. Seeing as Link is the "hero of time", I always saw the series as two omnipresent "forces" that are epitomized by Link and Ganondorf, good and evil, a conflict that reoccurs every century or so. We can be sure all this is happening within the same world, seeing as certain constants exist (the goddesses, zelda, hyrule, termina, deku tree, faeries, etc) but I dont think anyone knows for sure | [
"The story of \"The Legend of Zelda\" is described in the instruction booklet and during the short prologue which plays after the title screen: A small kingdom in the land of Hyrule is engulfed by chaos when an army led by Ganon, the Prince of Darkness, invaded and stole the Triforce of Power, one part of a magical... |
What causes the double sonic boom of Falcon rockets landing? | Practically all objects that breaks the sound barrier cause a double sonic boom. First at the front of the object, where it is pushing away the air, and second at the end of the object, where it stops pushing away the air. At both these points there is a big and rapid change in pressure.
The F9 actually creates three sonic booms though. At the engine, at the landing legs and at the grid fins. | [
"According to witnesses no sonic boom was heard. It is claimed that this was because of the short distance between the observers and the deafening sonic waves from the combined liquid and solid-fuel rockets used to propel the vehicle. Standing shock waves in the rocket exhaust produce continuous supersonic shock wa... |
In the UK, how did political power shift away from the nobility? | It was taken from the hands of the nobility in 1999 when Labour removed the rights of peers to sit in the House of Lords, which is the UK's second chamber.
92 hereditary peers are left there today, along with 26 Princes of the Church. The rest are members of political parties that were ushered while their party was in power. Sixteen years later it's still a controversial issue and reeks of corruption to many.
FYI, this subreddit has a rule that excludes everything that happened under twenty years ago. | [
"The influence of the Crown was increased by the civil wars of the late fifteenth century, which destroyed the power of the great noblemen. Both houses of Parliament held little power during the ensuing years, and the absolute supremacy of the Sovereign was restored. The domination of the monarch grew further under... |
What's the science behind the Hiroshima and Nagasaki bombs? Why were they still airborne when they detonated? | Both the Hiroshima and Nagasaki bombs were devices meant to create a supercritical state in a mass of enriched uranium (Hiroshima) or plutonium (Nagasaki), which allowed for an explosive nuclear fission chain reaction. In more layman's speak, this means that they quickly created the conditions so that [splitting one atom of uranium-235 or plutonium-239 would lead to the splitting of more than one additional atoms](_URL_0_), which over the course of a millisecond of such exponential splitting would release a lot of energy. They used different fuels and were of different designs because of those fuel choices. In the Hiroshima bomb (Little Boy), one piece of enriched uranium was shot into another through a gun barrel using high explosives. This created a brief supercritical mass of uranium. In the Nagasaki bomb (Fat Man), a solid sphere of plutonium-239 was compressed symmetrically from all sides through the use of explosive lenses, which increased its density by a factor of 2 or so, squeezing its atoms closer together. This meant that its existing mass was now supercritical.
There are many more details involved with making this work in practice, but the basic concept is as described. Atomic bombs are just complex machines made to produce the conditions for the chain reaction.
The above is totally separate from why they were detonated in the air. The choice of an air bust was made to maximize blast damage to the targets on the ground. When the blast wave proceeds downward from above, it reflects off of the ground. It can then catch up with the rest of the blast wave, increasing its strength. This expands the area of medium/light damage considerably, at the expense of heavier blast damage. For a "light" target like a city, this is (clearly) entirely adequate. [You can see a diagram of this reflection here](_URL_1_), and a [photograph of the reflection here](_URL_2_) (the latter is for a weapon with the same yield as the Hiroshima bomb, from the 1950s; those little dark things on the ground are tanks). This technique is sometimes used with conventional explosives as well. | [
"In Europe and America the effects of the atomic bombs over Hiroshima and Nagasaki were not fully understood. The photos produced by Masao Horino contributed to the world wide cry for the bombs to never be used again.\n",
"Details of nuclear weapon design also affect neutron emission: the gun-type assembly Hirosh... |
what makes facebook so valuable? why would it be a 100 bn $ company? | They do have a product they sell, a very valuable one... You.
All those statuses, all those 'likes', all those location check-ins... That data isn't just there for your friends to see. It is organized and categorized and analyzed and creates an unbelievable source of data for directed advertising. You dump every detail of yourself onto Facebook which tells them exactly what to try and sell you. The ads may be small and seem insignificant, but they are the digital equivalent of real estate on Manhattan Island. Add to that the ads beyond the actual _URL_0_ site itself. The 'like' button you see on virtually every website now, ever wonder why you don't log in every time you use it? A cookie based system is essentially tracking your every online movement while at the same time allowing advertisers to customize ads anywhere based on your FB info. Not just Facebook either: Google, Yahoo, Foursquare, Twitter... All these 'free' products we take for granted as "Innovative communications tools for the 21st century!" are vast information fishing nets for well-paying corporate clients.
I always chuckle when the semi-annual "Facebook is going to start charging a fee!" outrage kicks up. No they aren't. They have zero need to ever extract a penny from us, more likely they will keep tacking on new free feature after another. When you sell something you charge the fee to the buyer, and we aren't the customer... we're the product. | [
"Facebook ranked No. 76 in the 2018 Fortune 500 list of the largest United States corporations by revenue. Most comes from advertising. One analysis of 2017 data determined that the company earned per user from advertising.\n",
"Facebook did accept investments from companies, and these investments suggested fluct... |
is there an evolutionary benefit to the type of hair you have? | I can tell you that having really curly afro hair in the summer heat means that I can sick my fingers in my hair and it feels like there is a little private AC unit in there. It keeps my head cool, I imagine it does, and has for other afro haired humans who are almost entirely of recent African descent, where it would have been beneficial in the hot environment. | [
"It has been hypothesised that, in an alternate type of mutation, positive selection for increased expression of the FGF5 protein was one of the contributing factors in the evolutionary loss of hair in cetaceans as they transitioned from the terrestrial to the aquatic environment.\n",
"Markus J. Rantala of the De... |
when nasa created the golden record that they sent with the voyager probe, how did they know that another intelligent species who found the probe would be able to read/play it? | They printed instructions on how to play the disk in pictograms onto the disk cover.
see this picture on the explaination of the pictograms
_URL_0_ | [
"Launched in 1977, the Voyager probes carried two golden records that were inscribed with diagrams depicting the human form, our solar system, and its location. Also included were recordings of images and sounds from Earth.\n",
"The Voyager Golden Records are two phonograph records that were included aboard both ... |
what's a tarif? | A tariff is a tax on imports or exports.
For example, if you have a 100% tariff on iron, that means someone wanting to import (or export) iron into your country must pay 100% of the value of the iron in taxes. | [
"In computing, tar is a computer software utility for collecting many files into one archive file, often referred to as a tarball, for distribution or backup purposes. The name is derived from \"(t)ape (ar)chive\", as it was originally developed to write data to sequential I/O devices with no file system of their o... |
How does hydrogen peroxide work to remove stains? | It either oxidizes the material responsible for the coloration to the point that it becomes water soluble and rinses away or until it no longer absorbs light in the visible spectrum (organic dyes absorb light in certain color bands based on the energy level of their electrons - adjust the electronics and you adjust the absorbtion band. The process is called bleaching because this is also what bleach does). | [
"Oxidation using hydrogen peroxide is often used as a low cost pyrogen destroying solution. The mechanism for this destruction is unknown, but hydrogen peroxide can easily be removed further downstream in the purification process, and is therefore a useful method of pyrogen removal. However, like acid-base hydrolys... |
How did the first century Greeks and Romans view women? Further, how was this different from how Christians treated women? | This is mainly about the upper classes, as a necessity mandated by our sources. But an extremely brief summary: Greek and Roman medical theory believed that women had not received enough heat in the womb, and thus had failed to mature into full humans, i.e. men. So women are considered inherently biologically inferior. Women were expected to get married, get married early (~14), produce children, and re-marry if their husband died in order to produce more children. Remaining unmarried was highly anomalous, even religious virgins (such as the vestals) generally only remained virgins for a set period (for example until 30). The production of children was considered absolutely vital to the future of the state, community, and family. It was also hugely dangerous. Marriage was understood as one of the core institutions of the Empire, vital to maintaining it. Men were the unquestioned head of the household, all the property, etc. Women essentially passed from the control of their fathers/older brothers to husband.
Christianity, on the other hand, brings with it a strong focus on bodily asceticism, of which sexual renunciation (and given above, extremely visible) was an important part. Christians both encourage consecrated virginity among young women, but they also support widows who wish to remain unmarried. Both of these allowed women to escape the societal strictures of the time, and to at least a limited degree the control of men, and to avoid the terrifying (we can see this in their literature) dangers of childbirth. Also vitally, it enables widows to retain control of their deceased husband's property, which for the upper class could be quite substantial (some of the widows who corresponded with Jerome in the 4th century were among the richest people in the world at the time). This is all pretty problematic from the point of view of prevailing society. Thus, in Late Antiquity it is Christianity which is accused of being anti-family.
It's also important to note that many, if not most, Roman religious practices excluded women, whereas Christianity did not. Perhaps not unsurprisingly, Christianity was very popular with women.
A lot of this comes from Peter Brown's *Body and Society* which is a really excellent study of this sort of thing.
| [
"Whereas neither the Jewish, nor the Roman family would warm the hearts of a modern feminist, the early Christians were sympathetic to women. Paul himself insisted in his early writings that men and women were equal. His letter to the Galatians was emphatic in defying the prevailing culture, and his words must have... |
what went down in the ows subreddit? | I only have a tenuous grasp of the situation, but what I gathered was that some dick (username: [TheGhostOfNoLibs](_URL_0_)) finagled his way into a moderator spot on [/r/occupywallstreet](/r/occupywallstreet). Several people were complaining that he directly opposes just about everything the OWS movement stands for, has a war hawkish disposition, and regularly makes inflammatory and offensive comments. A lot of people were banned from the OWS subreddit for pointing out that this guy is an asshole and has no business being anywhere near an OWS community. Evidently he was stripped of his position recently. [source](_URL_1_) | [
"OWS Media Group, Inc. is a group of the Occupy Wall Street movement, which achieved media attention after filing a lawsuit to re-obtain control over the Twitter account, @OccupyWallStNYC, which was hijacked by one of tweetboat's former members and password holders, Justin Wedes.\n",
"On June 10, 2015, a post on ... |
Why is it human nature to enjoy the pain of others? | It is not human nature to enjoy the suffering of others, quite the opposite in fact. Empathy is the one of the very important reasons our society functions well.
Sometimes however, the relief that we are not the ones suffering can be mistaken for enjoyment.
In modern day it can be seen as weak or soft to be empathetic, leading to a growing tendency for people to stifle or repress their feelings of empathy. However if this keeps happening, society as we know will start to deconstruct, as everyone will become overwhelmingly selfish at the expense of others. | [
"A benefit of tracing good to pleasure and pain is that both are easily understandable, both in oneself and to an extent in others. For the hedonist, the explanation for helping behaviour may come in the form of \"empathy\"—the ability of a being to \"feel\" another's pain. People tend to value the lives of gorilla... |
Is there an auditory processing disorder that is similar to dyslexia? | There is a disorder literally called Auditory Processing Disorder (APD) that is similar to Dyslexia. It is an abnormality in the processing of sound in the central auditory nervous system and it affects the brain’s ability to filter and process sounds and words. Most people that have Dyslexia also tend to have this disorder as well. | [
"Dyslexia is thought to have two types of cause, one related to language processing and another to visual processing. It is considered a cognitive disorder, not a problem with intelligence. However, emotional problems often arise because of it. Some published definitions are purely descriptive, whereas others propo... |
How did James Maxwell determine that electromagnetic waves create their own medium? | To get the speed of light, you can take Maxwell's equations, assume there are no charges anywhere, and 'pluck' the electric or magnetic field and watch what happens. The solution to these assumptions is a wave propagating through the EM field at the speed *c*. Maxwell proposed that light might be an EM wave because this behavior matched what was known about light at the time.
Originally, it was thought that this wave was propagating in a 'luminiferous aether', as these charge-free EM fields were assumed to be mathematical constructs, not physical things (because the only known way to measure the field was with charges or magnets.) The [Michelson-Morley experiment](_URL_2_), along with the analysis provided by Einstein, convincingly demonstrated that no such thing exists. Further measurement of the properties of light and results like the derivation of [Snell's law](_URL_1_) and the equations of [diffraction](_URL_0_) from Maxwell's equations cemented the idea that light was an electromagnetic phenomena.
EM Fields were then taken to be fundamental, essentially taking the electromagnetic field itself as the medium for the propagation of light. The electromagnetic field could be measured without the use of charges by measuring light. | [
"With the addition of the displacement current, Maxwell was able to hypothesize (correctly) that light was a form of electromagnetic wave. See electromagnetic wave equation for a discussion of this important discovery.\n",
"In 1864 Scottish mathematical physicist James Clerk Maxwell proposed a comprehensive theor... |
Does the electromagnetic spectrum abruptly stop at gamma rays.. or are there higher energy/shorter wavelengths out there? | No, there is no sharp cut off, though we don't have a standard term for super-high energy photons. Typical gamma rays from nuclear have energies of 10^(5) to 10^(7) eV. Astronomical sources can yield energies around 10^(13) eV, indicating that they coming from processes other than radioactive decay. If you can find a way to create a high energy photon, it will have more energy.
In fact, the notion of a photon's energy is dependent on the frame of reference of the observer. The fastest particle every observed was a cosmic ray (likely a proton) with an energy of 3x10^(20) eV. Imagine that that cosmic ray was observing a gamma ray that we observed as traveling towards the cosmic ray and, in our frame, with an energy E. To the cosmic ray, that gamma ray would have an energy that was between 10^(11) and 10^(12) times bigger. That means, if things were lined up right, nuclear gamma rays we observed at 10^(7) eV or astrophysical gamma rays that we observed at 10^(13) eV would, to this cosmic ray, have energies of over 10^(18) or 10^(24) eV, respectively. | [
"In the few radio-loud Seyfert galaxies that have been observed, the radio emission is believed to represent synchrotron emission from the jet. The infrared emission is due to radiation in other bands being reprocessed by dust near the nucleus. The highest energy photons are believed to be created by inverse Compto... |
Monday Methods | An Indigenous Pedagogy | Another very fascinating write-up, thank you. I actually have a few questions.
In most threads on indigenous or marginalized/subaltern peoples of any kind, there is a common caveat that accompanies any historical answer on this subreddit. For example, from a recently excellent answer about Native American perceptions of dinosaur bones:
> This is my general notice that "Native American" encompasses two vast continents filled with innumerable people in the various landscapes of those continents, whose thoughts, traditions, and cultures were not static, but evolved and flourished over a period of thousands of years.
Yet, in our current thread, your post is written about "Indigenous peoples" and "Indigenous pedagogy". Essentially, I'm curious, are these methods specific to certain indigenous groups? Is this a kind of generalization (i.e. for a United Statesian context)? A better question might be: What is the historiography of indigenous historical methodology? Is this a post-colonial construction, or did the pre-colonial Aztecs and the Algonquin peoples share fundamental educational values which could be summed up as "Indigenous pedagogy"?
Addendum to this: is "Western" a kind of misnomer, in this case? Do pedagogical systems in China or the Middle-East fall under this purview? I just fear that there may be a less Eurocentric way to frame the divide.
Secondly;
> These benefits also extend beyond Indigenous students and can be applied to non-Indigenous students alike, those who, in my opinion, do not benefit from many Western methods of teaching as previously thoughts
This was interesting to me, because I usually encounter criticisms of educational paradigms through a self-fulfilling lens; education systems help student navigate educational systems and a workforce based on those educational systems. That is, the system serves itself, and society at all levels is shaped by and for people which went through the system. In this sense, a radical departure from Western educational paradigms could potentially undermine Indigenous attempts at prosperity, equality, and agency, despite the equal (if not greater) value of the pedagogical system itself.
Essentially, if an indigenous student goes through an undergraduate degree with a more indigenous pedagogy, would they be at a disadvantage in moving on to medical school and being forced to navigate a less-familiar Western pedagogical system?
And finally:
> Thus, the words of elders to relate what happened in the past has as much authority as the written word (if we are putting Indigenous peoples and Western societies on level playing fields, that is).
This may be outside the scope of the thread, so feel free to link to a previous answer on the subject. My understanding of both the academic consensus on psychology and criminology is such that human memory is far, far more fallible than generally believed. Not that written sources are infallible or anything of the sort, I'm just curious, is that an uncontroversial statement to make (written word having as much authority as the spoken)? I understand the social and political reasons to avoid civilizational arguments for the superiority of literate texts, but from a historiographical perspective, is this opinion shared by scholars working outside indigenous contexts (givenn that all human cultures still maintain some oral elements, i.e. folklore and whatnot)?
Sorry for all the questions, I'm really diving into unknown territory for myself here. | [
"Critical Indigenous Pedagogy focuses on resisting colonization and oppression through education practices that privilege indigenous knowledge and promote indigenous sovereignty. Beyond schooling and instruction, CIP is rooted in thinking critically about social injustices and challenging those through education sy... |
why are some seasonal fruits, like apples, available all year round, but others aren't? | Seasonal fuits are grown in both the northern and southern hemispheres and shipped all over the world. A lot of summer fruits that are available in grocery stores in the winter in northern countries are grown in Chile, Argentina, New Zealand etc. The same is true of winter fruits that are available in grocery stores in the summer in northern countries.
Fruits that cannot be shipped and stored easily are not available out of season. Apples, for example, are very easy to ship because they are hard and so do not bruise easily, and they can be stored in refrigerators for months. Strawberries, on the other hand, are too delicate to ship long distances or to store for months because they will bruise and rot quickly.
Some of these more delicate seasonal fruits can be grown out of season in greenhouses, but they tend to be very expensive. They can also be grown in more temperate regions like California and Mexico, which have much longer growing seasons, but they still still have to be shipped on trains and trucks. Avoiding bruising and spoilage is a difficult process.
Tropical fruits like bananas, pineapples, and papayas are grown year-round in tropical climates. | [
"While the season usually lasts only 9 or 10 months, they are able to last all year round. However, due to some apples continuing to be grown in some orchards, and the fact that they can be refrigerated for some months, leads to the availability of the Gala apple year-round in some Australian markets. These usually... |
how do they fake apps/operating systems in movies/tv | Usually you would want to do it in post-production because screens don't film well due to different refresh rates. They may have prompts on the screen if the scene calls for it though. | [
"Virtual influencers are sometimes considered fake influencers too, given their profiles do not correspond to real individuals. It can be argued, however, their presence and role on the platform are different, in the sense they are not automated (bots) nor implemented with the purpose of generating fake likes, fake... |
why do game consoles not need a 3 prong plug with a ground wire but things like amplifiers and pcs do? | The 3rd prong is just an added safety precaution. To be approved by the UL anything with an exposed metal case needs to have the 3rd prong so if a wire inside the device comes loose and into contact with the case the current will go down the ground prong and not to you if you touch it. game consoles have plastic cases, computers have metal cases around their power supplies which is exposed on most systems. | [
"Historically, pinball machines have employed a central fixed I/O board connected to the primary CPU controlled by a custom microcontroller platform running an in-house operating system. For a variety of reasons that include thermal flow, reliability, vibration reduction and serviceability, I/O electronics have bee... |
How does the rate at which a star burns up scale with temperature? | Just taking some of the relationships from [here.](_URL_0_) We have:
- Lifespan is proportional to M^-2.5
- L is proportional to M^3.5
- L is also proportional to T^4
(where L is luminosity, T is temperature and M is mass). So combining all of these, we get lifespan is proportional to T^-10/3.5 or T^-20/7 . | [
"The surface temperature of a main sequence star is determined by the rate of energy production of its core and by its radius, and is often estimated from the star's color index. The temperature is normally given in terms of an effective temperature, which is the temperature of an idealized black body that radiates... |
how is downloading movies/books online any different than going to your local library to check out movies/books for free? | First sale doctrine applies to libraries, video rental outfits, etc.
From [Wikipedia](_URL_0_)
> The doctrine allows the purchaser to transfer (i.e., sell, lend or give away) a particular lawfully made copy of the copyrighted work without permission once it has been legally obtained. This means that the copyright holder's rights to control the change of ownership of a particular copy ends once ownership of that copy has passed to someone else, as long as the copy itself is not an infringing copy.
They purchased the copy legally, so they can lend, sell, or rent it out as they see fit so long as they're not duplicating it. | [
"Used bookstores can range in size offering from several hundred to several hundred thousands of titles. They may be brick-and-mortar stores, internet-only stores, or a combination of both. A book town is a locale where numerous bookstores are located and serve as the town's main attraction to tourists.\n",
"The ... |
what would happen if somebody broke the nato treaty? | Sending military support is only one way NATO countries can show support. They can also provide financial aide, legal aide, or advisory aide.
Unless one NATO country attacked another, I can't imagine a situation where the other NATO countries wouldn't provide some sort of support, no matter how indirect. | [
"At the time the treaty was being negotiated, NATO had in place secret nuclear weapons sharing agreements whereby the United States provided nuclear weapons to be deployed by, and stored in, other NATO states. Some argue this is an act of proliferation violating Articles I and II of the treaty. A counter-argument i... |
Why are Hydrogen(1) and Helium(2) highly abundant in the universe, while Lithium(3) and Beryllium(4) not that much? | Production of lithium from helium is highly *Endothermic*, meaning that it consumes massive amounts of energy instead of creating it. Secondly the fact that it's endothermic results in a significant *Energy Barrier* that needs to be overcome, on top of the powerful electrical repulsion between nuclei.
The most likely way one would assume lithium would be produced is from a hydrogen nucleus colliding with a helium-4 nucleus. (2 protons and two neutrons), producing Li-5. *However Li-5 is extremely unstable (half life = 3.7 × 10^−24 s) and almost instantly decays back into helium-4, spitting the proton right back out.*
Li-6, the first stable isotope, would need to be produced by fusion of deuterium (Hydrogen-2) with helium-4. Deuterium in the sun is only about 23 parts per million, because it tends to fuse more easily into highly stable helium, than bare hydrogen-1. So it's consumed almost as fast as it's produced.
Additionally producing Li-6 runs up against the *energy barrier* mentioned earlier, making this process astronomically rare.
In fact the majority of the lithium in the sun has probably been there since the sun's formation. Lithium, Berylium, and Boron are among the rarest elements in the sun.
Li,Be,and B are probably produced in outer space by [Cosmic Ray Spallation](_URL_0_) from much more common, heavier elements. Not produced by fusion in stars.
Berylium is likely produced from lithium-7 by neutron capture via the [S-Process.](_URL_1_) (PDF)
In fact, lithium-7 is much more common than lithium-6, because the latter is much better at absorbing neutrons.
Certain reaction in the sun involving hydrogen isotopes, end up producing high-energy neutrons. These neutrons may be absorbed by heavy elements in the sun. In some situations this converts them into higher elements through successive beta decays. In other cases this may produce lighter elements plus helium by triggering alpha decay.
| [
"According to modern cosmological theory, lithium—in both stable isotopes (lithium-6 and lithium-7)—was one of the three elements synthesized in the Big Bang. Though the amount of lithium generated in Big Bang nucleosynthesis is dependent upon the number of photons per baryon, for accepted values the lithium abunda... |
why does putting the air conditioner on 25°c in a cooling mode feel different from the same 25°c in heating mode? | The unit isn't putting out air at 25 C.
If it's in cooling mode, it's putting out very cold air until the ambient temperature reaches 25 C.
If it's in heating mode, it's putting out very warm air until the ambient temperature hits 25 C. | [
"Switching the direction of heat flow, the same system can be used to circulate the cooled water through the house for cooling in the summer months. The heat is exhausted to the relatively cooler ground (or groundwater) rather than delivering it to the hot outside air as an air conditioner does. As a result, the he... |
land bridges | Here's a NOAA map of the last ice age sea levels at their peak (trough) _URL_0_
| [
"A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise new lands. A land bridge can be created by marine regression, in which sea levels fall, exposing shallow, previously submerged sections of continenta... |
what's the deal with tuxes, blazers, etc, when is each appropriate, what kind of occasions? | In descending order of fanciness:
- **[White Tie](_URL_2_)**, otherwise known as Evening Dress or Top Hat And Tails.
This is as formal as it gets in Western fashion, and is generally restricted to very high occasions like state dinners, royal functions or very formal balls and evening weddings. White Tie is strictly to be worn after 6 PM, though many agree that anytime after dark is fine. For events of similar importance during the day, [Morning Dress](_URL_0_) is the thing.
- **[Black Tie](_URL_1_)** is for any highly formal occasion for which White Tie is not required; charity galas, formal weddings, awards ceremonies. It is generally considered good etiquette for the host of an event to indicate on the invitations whether or not Black Tie is appropriate, or whether Formal Wear will suffice.
- **Formal Wear** is sometimes called "informal attire" to set it apart from Black Tie, but as often as not that ends up with Bob from Accounting showing up in khakis and a Hawaiian shirt. Formal wear is pretty basic, just a suit and tie. Lots of leeway here in terms of colour, fashionable cut, accessories etc., if you want to know more about this in detail I think it's done in detail on GQ's website.
The only big things to keep in mind with Formal Wear are that one should always wear black or very dark grey to a funeral, and one should never wear black to a wedding unless the event itself is listed as Black Tie. While we're talking funerals, even if the only black suit you own is a tuxedo, never wear it to a funeral as Black Tie is considered to be for celebrating.
- Below Formal you might see "Smart Casual" or "Business Casual"; the former usually refers to some variation on a blazer and dress pants, while the latter is a nightmarishly vague reference to "any pants nicer than jeans, paired with virtually any shirt with a collar and no logos". When to wear either of these gives many men great difficulty; if in doubt, ask your host or employer in advance.
| [
"Blazers are worn with a wide variety of other clothes, ranging from a dress shirt and necktie to an open-necked polo shirt, or even just a plain T-shirt. They are seen with trousers of all colours and fabrics, from the classic white cotton or linen, to grey flannel, to brown or beige chinos, and also jeans.\n",
... |
How do weather satellites measure barometric pressure in the atmosphere from space? | Satellite radar systems can correlate a specific band of the electromagnetic spectrum with surface pressure, but according to my relatively limited knowledge of remote sensing, this technique is not commonly in use. Surface pressure is generally recorded in the ocean by anchored buoys, or potentially by [dropsondes](_URL_0_) in the case of a special mission to record pressure fields in tropical storms. | [
"A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to help find surface troughs, pressure systems and frontal boundaries.\n... |
Volume of Earths atmosphere? | The volume of Earth's atmosphere, using the [accepted definition of the edge of the atmosphere](_URL_0_) is approximately 5.18*10^19 m^3 . Not very useful without something to compare it to, but it's a place to start. | [
"The composition of Earth's atmosphere is largely governed by the by-products of the life that it sustains. Dry air from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other \"noble\" gases (by volume), but generally a variable amou... |
why do stores offer cash-out, if it seems like they don't make any profit off it. (they charge your card, and give you that amount in cash) | The store benefits by getting rid of physical money and using electronic funds transfer - less money to transport in an armoured truck, less loss if they are robbed | [
"The combination of these two factors means that the retailer can save money by offering the cashback service. It does not cost the retailer more in commission to add cashback to a debit card purchase, but in the process of giving cashback, the retailer can \"offload\" cash which they would otherwise have to pay to... |
Why does a single gas molecule which is hot rise above another one which is cool? | Metrics such as temperature describe the behavior of a system that is made up of components. These types of properties are termed emergent properties because they are derived from the behavior of the system as a whole and are not observable if you were to look only at the components.
So, for your specific question, individual molecules do not have temperature. They are not "hot" or "cool" exactly, although they do have energy that is zipping them around their surroundings. Molecules with more energy will move faster and collide with other matter more frequently and with more force. It is only when you begin to look at a system of molecules that ideas such as temperature start to be meaningful. In that sense, a group of molecules with a certain amount of energy will correspond to a certain temperature. If these molecules are "hotter" than other molecules, then they will be moving about much more rapidly and they will be less dense than the latter group of molecules. Properties such as temperature and density are emergent from the system of molecules interacting with each other and interacting with their surroundings. | [
"Molecules, such as oxygen (O), have more degrees of freedom than single spherical atoms: they undergo rotational and vibrational motions as well as translations. Heating results in an increase in temperature due to an increase in the average translational kinetic energy of the molecules. Heating will also cause, t... |
how was space x able to build better rockets than nasa having less budget and experience? | I think the other people have missed the critical element here.
The critical element was the shift from disposable to reusable rockets. Now, to their great credit, NASA did make that move in the 70s with the space shuttle, but it was a bit too early, and the whole shuttle project was a bit of a logistical and political shitshow.
By the time SpaceX came along, technology had advanced considerably. Here's a great talk by Raffaello D’Andrea explaining it [_URL_0_](_URL_0_)
In short, between the Space Shuttle and the Falcon 9, feedback control got good enough, and cheap enough, that the idea of landing an otherwise traditional rocket vertically was very feasible. By this point, the Shuttle was seen as a failure - technologically impressive, but economically unviable, and increasingly outdated. So NASAs focus was off of reusability and onto cheap disposability. In that environment, dumping money into R & D is a bit pointless if you have designs from the 60s that are reliable and well understood. They'll only fly once, and the cost of space flight is really in the minimization of failures. So, advances in engines and control systems largely stopped.
SpaceX saw things differently. Believing they could take what looked like a conventional rocket and land and refly it, meant they could change the economic model. Launches were rare because the cost of disposing a rocket each time was high, and because the cadence was low - there was no incentive to build out production lines that could spit out a rocket every two weeks. But if you could reuse the rocket, even just one more time, you'd need half as many of them. Refly it 4 times, and you need to build only 20% as many. So, SpaceX went for a commodity strategy - build one really really good motor to serve first and second stage, rely on modern control electronics to regulate 9 motors operating together in the first stage, and engineer for reusability, and get your reliability that way, and dramatically cut costs to fly the rocket and use that money to pay for the new R & D. Digital feedback control wasn't the only thing that had dramatically advanced since the 70s, so had manufacturing techniques and materials engineering. So SpaceX could build simpler rockets that performed better than was possible in the 70s.
NASA didn't want these rockets, believing in their tried and true approach, but private companies did want them and with time SpaceX won them over. Bezos saw the same opportunities, as did others. Existing companies didn't see the opportunity because their value was in their tried and true methods, their decades of engineering experience at this, their detailed knowledge of how these old system worked, which made them reliable.
This is also a story of why established companies rarely pivot their business model to adapt to changes, and why startups and other new entrants are key to advancing industries. They can take these risks, they can invest in the new technology and not invest in the legacy technology. Had SpaceX failed, we wouldn't even be talking about them - so there's some survivors bias baked in here too. | [
"Congressional testimony by SpaceX in 2017 suggested that the unusual NASA process of \"setting only a high-level requirement for cargo transport to the space station [while] leaving the details to industry\" had allowed SpaceX to design and develop the Falcon 9 rocket on its own at substantially lower cost. \"Acco... |
Is it true that there have been 29 years free of war in all of human history? | It rather depends how you define things. If you count tribal disputes as wars, then it is unlikely there was ever a year without war. If you don't count tribal disputes, only formal armies, then the majority of human existence was without war. Mind you, most of human existence was before history. | [
"BULLET::::4. \"The Long Peace\" – The powers of 20th Century believed that period of time to be the bloodiest in history. This led to a largely peaceful 65-year period post World War I and World War II. Developed countries have stopped warring (against each other and colonially), adopted democracy, and this has le... |
Why didn't Hitler tell Mussolini about his plans to invade the USSR? | This one is kind of complex.
[Operation Barbarossa](_URL_2_) was the operation the Axis had planned to invade the Soviet Union. Nazi Germany had started to amass troops and equipment and had a pretty substantial force at the border in February of 1941. The original plan for the operation was to take place in May of 1941. There really was no shock, Stalin knew of the amassing of German troops and was warned by Soviet military leaders of an impending attack.
Mussolini and the Italian Military were fighting the [Greco-Italian War](_URL_3_) in Greece and making no headway. This is considered the start of the [Balkan Campaign](_URL_6_). The stalling of Italy in Greece lead to Hitler start [Operation Marita](_URL_4_) which was the German invasion of Greece, which coincided with the Italian invasion of Greece, which had stalled. Hitler had no intentions of invading Greece at this point, but was forced into action by Mussolini.
To sum it up quickly at this point. Italy tried to invade Greece from Albania, without Hitler and a lot of other important Italian leaders knowing, and failed. Greece actually pushed back and started taking ground in Albania. Hitler pushed forward with Italy to invade and defeat Greece.
The failure of Italy to defeat Greece on their own meant that some of the troops and materials for Operation Barbarossa were used in The Balkan Campaign. Which, with some other weather related issues lead to Operation Barbarossa being delayed. The delays are questionable at this point, there is some speculation that the Operation could have continued, even with the Germany military being deployed in Greece.
Prior to the entire Greek campaign, Italian forces under Mussolini had dealt with setbacks in the North African Campaign. Which lead to Rommel being deployed to Africa to aid the Italians in that campaign.
The relationship between Hitler and Mussolini was complex and stressed. Mussolini never felt like an equal and the invasion of Greece was not advised by Hitler, rather performed by Mussolini to impress Hitler. Which basically lead to Hitler having to bail him out. Hitler commonly didn't communicate with Mussolini, so not knowing about the invasion of the USSR isn't odd.
So to answer your first question. Mussolini already had his hands full with the Greco-Italian war. Aiding Hitler at the border of the USSR would have been near impossible. Hitler delayed Operation Barbarossa to aid Mussolini in Greece.
Anecdotally, I would assume that there was some irritation on Hitler's part with Mussolini. From everything I have read about the relationship between Hitler and Mussolini, Hitler never viewed Mussolini as an equal and Mussolini never felt like an equal. Even prior to any invasions.
So while both Italy and Germany had signed the [Pact of Steel](_URL_0_), both countries had trouble with meeting the obligations of the pact.
As to when did the Italians get into the USSR? The [Italian Expeditionary Corps](_URL_1_) were deployed to the USSR in July of 1941. Later the expeditionary corps were upscaled to a full sized army unit in [July of 1942](_URL_5_)
Operation Barbarossa had started in June of 1941, so the assistance of the Italian military had come less than a month after the campaign started.
Then you get into the whole invasion of Northern Italy. Hitler had basically set up a puppet government and put Mussolini in charge of Northern Italy after Southern Italy was retaken by the Allied forces. Mussolini and his mistress trying to escape to the Swiss border, being captured by allied Italian fighters, both of them being shot and then their bodies were hung in a park in Milan and defaced by many, many Italian citizens.
| [
"Mussolini first learned of Operation Barbarossa after the invasion of Soviet Union had begun on 22 June 1941, and was not asked by Hitler to involve himself. Mussolini took the initiative in ordering an Italian Army Corps to head to the Eastern Front, where he hoped that Italy might score an easy victory to restor... |
what is cancer? (specifically leukemia) | You, my ELI5 friend, are made of cells. Billions and billions of them, and they all have special jobs, shapes, and grow a different rates.
Sometimes we want cells to grow and divide a lot, like skin cells. And sometimes we don't want cells to grow and divide a lot, like brain cells. Each cell knows, because it is in the DNA, when to stop dividing.
But the biochemical machines that run cells don't always work properly, and sometimes a cell doesn't stop growing. The reasons why are complex and varied (i'll go into them if you want but it's not very ELI5ish).
This broken cell keeps growing and dividing, consuming resources from surrounding cells, and getting bigger, which will cause harm to surrounding organs. This is called a tumor.
Cancer is named from what kind of cell it arises from. Leukemia is a special kind of cancer, where the broken cell is a white blood cell or leukocyte. Leukemia doesn't usually have a tumor, but can be found in the bone marrow (where all blood cells are 'born') and will destroy the bone there. | [
"Cancer is a group of fatal diseases that involves abnormal cell growth that can invade or spread to other parts of the body. They are usually caused by the accumulation of mutations in genes that regulate cell growth and differentiation. Majority of cancer, about 90-95%, are due to genetic mutations from environme... |
why are neanderthals always depicted with caucasian features? | Most, if not all, skeletons found of Homo neanderthalensis were found in Europe, especially places like France. As you may know, the people native to most places in Europe are Caucasian, including people like the Gauls (the tribe whose descendents make up a quite large percentage of native French people). | [
"Neanderthals are depicted as white-skinned, while Cro-Magnons are dark. Kurtén's skin color identification for both populations appears to agree with recent DNA studies, including those proposing the African origin of modern humans. His racial presentation of the Cro-Magnon is in contrast to Jean M. Auel's view in... |
Urban abandonment during late antiquity and the middle ages. | In the case of the Roman empire, there are several possibilities:
- The loss of North Africa to the Vandals. North Africa was the breadbasket of the Western Roman Empire, and without it, huge cities could no longer be supported. There was a similar but less dramatic depopulation of Constantinople after Egypt was lost to the Arabs in the 7th century. This is probably the most important reason.
- In the waning days of the western empire, invading Germanic tribes cut the supply of water into Rome and only the Aqua Virgo, which ran completely underground, continued to deliver water. In other words, large Roman cities were dependent on proper maintenance of aqueducts, and if they were destroyed for any reason, it would be difficult to continue to support a large population.
- There were several severe and protracted plagues, combined with a long period of invasions and conflicts.
- It has been speculated that the deforestation of the Western Mediterranean might have been an important cause. I really can't say how well accepted this argument is at the moment. | [
"However, there are traces of a resettling in the Middle Ages (12th century), when the ancient Roman walls were incorporated into those of a building forming part of the new inhabited hamlet also called \"Saint Eleuterio\", then in turn abandoned.\n",
"This development took place in the Late Middle Ages (13th to ... |
why doesn't the us military replace the m9. i'm sure there are better pistols out there. | Military firearms tend to have a long life. They like to standardize. When you've got a million of *anything* it's a big deal.
That said, they're [currently looking into a replacement](_URL_0_). These things can take time. Since handguns haven't fundamentally changed in decades, there's no major rush. | [
"The U.S. Army and Air Force are seeking to replace their M9s through the Modular Handgun System program. The House Armed Services Committee wants to terminate the program in favor of upgrading the M9. Program officials say buying a new pistol is the better option due to advances in handgun designs, the difficulty ... |
Hello AskHistorians, what are the most interesting or important books within your specialty, and what are they about? I am a teacher, creating a recommended/optional reading list for highly motivated students. Thank you! | Updating a list I wrote earlier for a request for resources on North Korea and the Kim regime:
- **Refugee account:** *The Aquariums of Pyongyang* by Chol-Hwan Kang and Pierre Rigoulout. A terrifying account of the Yodok concentration camp where the families of political prisoners are/were sent for punishment. Yodok was actually fairly high on the pecking order of North Korean camps, and the reason the book exists in the first place is that Kang is among the few who not only survived but was released. The book gained widespread recognition in the West after it ended up on George Bush's reading list and its authors were invited to the White House. Victor Cha (see below) comments on this and the effect it had on Bush's view of Kim Jong-Il.
- **Overview of propaganda:** *The Cleanest Race: How North Koreans See Themselves and Why It Matters* by B.R. Myers. Not everyone is on board with the author's conclusions -- he's extremely harsh to the generation of South Korean politicians behind the Sunshine Policy, which he considered both an ethical problem and a strategic blunder -- but it's a thorough look at the toxic ideology that is approved for mass entertainment and journalism in North Korea. This is what they say to themselves when no one is looking, although perhaps it might be more accurate to describe it as what you can say in North Korea without getting arrested or shot.
- **Statistical accounts:** *Famine in North Korea: Markets, Aid, and Reform* by Stephen Haggard and Marcus Noland, and *Witness to Transformation: Refugee Insights into North Korea* by the same guys. By necessity, these are somewhat drier accounts of what's going on in North Korea, but it's a mindfuck to read what statisticians *think* is going on in the country and what later refugee accounts corroborate. For example, Haggard and Noland arrive at the conclusion that the true roots of the North Korean famine probably started in the late 1980s when the Soviet Union started to fall, and stopped giving a shit about paying to support the ridiculously inefficient NK economy. Then you read Demick's book (see below) and see accounts from housewives in North Korea who say that they started getting shortchanged by the public distribution system at the exact same time. *Witness to Transformation* will give you some background on who is most likely to escape North Korea in the first place and what happens to them afterwards, with accompanying commentary (none of it terribly optimistic) about what this implies should the NK government eventually fall.
As an aside, reading the *Markets, Aid, and Reform* study was what convinced me that B.R. Myers was probably right about the damage that South Korea did to nuclear negotiations during the Six-Party talks.
- **Mixed bag o' topics:** *North of the DMZ: Essays on Daily Life in North Korea* by Andrei Lankov. This one's unique, as it's a series of essays written by a Russian writer who went to school in North Korea back during the 1980s, and that's a perspective that the Western world rarely sees. Lankov's articles are not only a valuable window into how the North Koreans were seen by their allies -- or more appropriately, "allies" -- but he also comments on a very wide variety of topics not usually addressed by scholars. Interestingly, his time in North Korea predates Andrew Holloway's (see below) by only a few years, and the NK that he writes about from that era is both recognizably the same NK that Holloway describes and an interesting contrast to the changes you'll see in the society as the Kims tried to prove that they could have co-hosted the 1988 Seoul Olympics.
- **If you read nothing else, read this:** *Nothing to Envy: Ordinary Lives in North Korea* by Barbara Demick. Demick was a Los Angeles Times reporter who was assigned to the Seoul bureau for several years and spent a lot of time interviewing North Koreans who'd escaped the country before it became somewhat common. This one really brings home to you the number of personal and family tragedies that the regime has caused, and why everyone who helped Kim il-Sung on his rise to power should have been shot. A finalist for the National Book Award in 2010.
- **And after you read Demick -- or maybe before you do:** *Under the Loving Care of the Fatherly Leader: North Korea and the Kim Dynasty* by Bradley K. Martin. This one gives a lot of background into the stuff you'll see in Demick's book, and interestingly also gives some insight into academic arrogance in the Western world concerning the Korean peninsula. The popular narrative on Korean history as written by vanguards like Bruce Cumings was far kinder to the Kim regime than it deserved, and Martin was given a lot of crap for writing about the concentration camps and the famine.
- **An American diplomat's perspective on the Six-Party talks and international relations in Asia:** *The Impossible State* by Victor Cha. This was published within the past year and, like Lankov's perspective, it's unique. Cha was the Director for Asian Affairs for the NSC under Bush and saw a lot of Japanese, Russian, Chinese, South Korean, and North Korean diplomats for his job. This isn't the book to read if you want an in-depth history of North Korea, but it's an incredibly cogent commentary on why NK is popularly known as "The Land of Lousy Options" in diplomatic circles, and what the American perspective was during the talks. There's also several behind-the-scenes stories from both the White House and the diplomatic world, including Bush's drop-in on a visiting group of Chinese generals and an interesting insight into the North Koreans' (correct) interpretation of Japanese politicking concerning aid.
- **The true believer turned hopeless cynic:** *[A Year in Pyongyang](_URL_0_)* by Andrew Holloway. Holloway was a Brit who lived in Pyongyang editing NK's English-language propaganda for a year, and he wrote the book as a way to keep from going insane while trapped in a fairly boring and extremely controlled city. If nothing else, I find it an absolutely fascinating meta-commentary on what one person can see of a society even when that society is determined not to let him see anything. As he says, he was a Marxist who was sympathetic to what appeared to be the underlying goals of North Korean society, but he managed to figure out that the wool was being pulled over his eyes despite a fairly regimented year.
There's still some heartbreaking assumptions, though -- mainly his firm belief that, whatever the Kim regime's mistakes, they would never commit the atrocities he had seen in more capitalist countries elsewhere, that NK just wasn't that kind of society. Turns out NK was *exactly* the kind of society that would ship people off to death camps. Holloway's account has many mistakes, but they were honestly made, they reflect what the Western world knew of North Korea at the time, and he obviously struggled with his portrayal of a society that he genuinely wanted to like due to his personal beliefs, but knew was deeply flawed. | [
"Expert authors dissect, simplify and explain each topic to help readers achieve greater success in their business and home lives. Each book is short, snappy and easy-to-read, yet bursting with instantly actionable takeaways.\n",
"The books cover a wide range of topics, many to do with crafts, tools, music and ot... |
apparently there are tens of thousands of illegal immigrants from ireland in places like new york. isn't life very difficult for them? how do they earn money? can they get things like houses, driving licenses, healthcare, etc? | Housing: rent and pay cash. Find landlord that doesn't care if you're illegal.
Driver license, just don't get one. Take bus or subway. Or drive illegally and not get pulled over.
Healthcare, go to emergency room, pay in cash or don't pay at all | [
"There are however numerous incentives which draw foreigners to the US. Most illegal immigrants who come to America come for better opportunities for employment, a greater degree of freedom, avoidance of political oppression, freedom from violence, famine, and family reunification.\n",
"Some people go to traffick... |
If our moon causes our tides, and considering the size, wouldn't moons around a planet the size of Jupiter have tides that would flood entire continents? | (not my field of expertise) The moons of Jupiter have huge tidal forces. For instance take Io, it's the closest large satelite of Jupiter and it's tidal forces are so extreme that they heat the core of the moon, causing volcanos with plumes hundreds of kilometers high!
_URL_0_
(I remembered all of this from Arthur C Clarke's 2010)
| [
"If the Earth had no Moon, the ocean tides resulting solely from the Sun's gravity would be only half that of the lunar tides. A large satellite gives rise to tidal pools, which may be essential for the formation of complex life, though this is far from certain.\n",
"Atmospheric tides are also produced through th... |
why do most aeroplane hangars have curved roofs regardless of their size? | Actually it is for strength. An arch is incredibly strong and puts far less strain on the materials than a flat surface. | [
"The rectangular hangar accommodates 10 planes, and is still in use today. The building is made of brick and has a concrete foundation. The roof is gabled, and the walls are parapeted. The end walls are capped by pent roofs and decorative brick panels framed by stucco. The north and south ends contain eight large s... |
What is the mythological precedent for Jesus's single resurrection? | To quote Mettinger's [The Riddle of Resurrection](_URL_0_), which is probably the best survey of ANE gods and resurrection (Baal, Dumuzi-Tammuz, Adonis, Melqart-Heracles, Osiris, Eshmun-Ascelpius):
> The dying and rising gods were closely related to the seasonal
cycle. Their death and return were seen as reflected in the changes of
plant life. The death and resurrection of Jesus is a one-time event, not
repeated, and unrelated to seasonal changes.
and
> There is, as far as I am aware, no prima facie evidence that the death
and resurrection of Jesus is a mythological construct, drawing on the
myths and rites of the dying and rising gods of the surrounding world. While studied with profit against the background of Jewish resurrection belief, the faith in the death and resurrection of Jesus retains its unique 1 character in the history of religions. The riddle remains. | [
"Rahner states that the death and the resurrection of Jesus are two aspects of a single event not to be separated, even though the resurrection is not a historical event in time and place like the death of Jesus. What the Scripture offers are powerful encounters in which the disciples come to experience the \"spiri... |
Since pi is irrational, is there a point in pi's decimals where there are 1 billion subsequent threes? | Probably, but not just because it's irrational. For example, the [Liouville constant](_URL_1_) is irrational but has only 0's and 1's in its decimal expansion.
However, pi is strongly conjectured to be a [normal number](_URL_0_). If this is the case, you certainly can find a billion 3's in a row in its decimal expansion—in fact, you'd find this infinitely many times. Of course, the first occurrence would be *very* deep, but it would be there. | [
"as it sometimes is, the ellipsis does not mean that the decimals repeat (they do not), but rather that there is no end to them. It has been proved that is irrational. Another well-known number, proven to be an irrational real number, is\n",
"In the 1760s, Johann Heinrich Lambert proved that the number (pi) is i... |
how are the nsa intercepting my data? | > Assuming I am US, by what method did the NSA just get hold of either/both the credit card details and travel information?
So the NSA is a spying agency, that also is involved in technical standards. They have court oversight through FISA, who can issue warrants that compel companies to turn over data.
Lets walk through what you just did.
> I submitted my credit card details online
You sent communications over a telecoms channel. The NSA has (literally) secret black closets in telecom company centres. If it's running over telecoms is most of the world they can intercept it, either via submarine cables, collaborating agencies or their own equipment in big telecom company centres.
> encrypted
Since the early days of encryption standards the NSA has been involved in, and deliberately weakening crytographic standards. Kinda. This is a bit complex, but the NSA, since the DES days, has wanted encryption that is strong enough that you need to be a big organized outfit to break. That sounds contradictory but isn't. Imagine you came up with a trivially bad encryption system - well then anyone could break it. That's not any good. But imagine you came up with an encryption system that required 100 million dollars in hardware to break efficiently. Ah, that's secure enough for most things, but vulnerable enough for an intelligence agency. With DES they shortened the key to make it vulnerable to brute force attacks, but eliminated an exploit that would have made it much easier to break. More recently they put an (obviously ridiculous) random number generator into standards that was bizarre in how sloppy it was at trying to be a back door.
> gmail
The NSA has had people working for them from inside Google for some time, particularly communication between data centres, some officially and some not. So they could easily be looked at your data inside the google data centres network. Your data is only useful if it can be read after all, so there has to be a recoverable form and key.
> Assuming I am US
If you are a US citizen they can spy on you to be sure you aren't also an agent of a foreign power, or they could get a FISA warrant to see what you are up to.
Back in June Yahoo's efforts to fight a FISA warrant were revealed. In short. Yahoo lost.
> credit card.... US
The NSA is a US government agency, with courts who virtually never say no. You should presume that if the government ever wants access to anything about you stored with a company then there is nothing you can do to prevent that.
Most likely the NSA is not spying on your random credit card transactions. They don't need to. For that they can get metadata about your transaction history from the banks. But if someone there is specifically trying to track what you're up to, then there's an issue. The NSA doesn't really need (or want) to decrypt or credit card details - that they have access to anyway.
| [
"All intercepted data go to the NSA headquarters in Fort Meade, Maryland, where a program called XKeyscore processes them and sending them to different so-called \"production lines\" that deal with targets, like counterterrorism or specific countries. These processed data are stored in different NSA databases like ... |
why does increased air flow extinguish flames? wouldn't you be adding the necessary ingredients? | Yer not alone in askin', and kind strangers have explained:
1. [ELI5: Why can air both extinguish and stoke up a fire? ](_URL_2_)
1. [ELI5: Why does blowing air on a small flame put it out, but doing the same on a big fire only fuels it? ](_URL_1_)
1. [ELI5: Why does blowing on a flame put it out, but glowing on coals makes them brighter? ](_URL_4_)
1. [ELI5: If fire thrives on oxygen, then why does wind blow a fire out? ](_URL_5_)
1. [ELI5 Why does a flame (like on a match, lighter, etc.) go out when you blow on it but when I blow on an ember it intensifies? ](_URL_3_)
1. [ELI5: How does wind blow out fire, like on a match? ](_URL_0_)
| [
"Oxygen is not flammable, but when it is present in increased concentrations it will enable fires to start much more easily. Once a fire has started, if supplemental oxygen is present it will burn more fiercely, based on the principle of the fire triangle. Materials that do not burn in ambient air may burn when the... |
why do people feel comfortable with themselves in the mirror, but hate themselves in flipped pictures? | Short answer: Because mirrors show a mirrored version of your face that you are used to/comfortable seeing. Photographs show a "correct" version of your face where it is not mirrored and it looks off to the person who perceives sees their face in a mirror on a regular basis
_URL_0_ | [
"This psychological effect is often used in the cinema, where an actor will be shown apparently looking at himself or herself in the mirror. What viewers see is different from what the actor sees, because the camera is not right behind the actor, but the position of the actor is often chosen so that his or her imag... |
If I could fly and I flew upwards really slowly, could I escape the earths atmosphere? | The term escape velocity refers to the speed you need to never fall back down to the Earth, assuming you stop pushing on your craft. If you can somehow continue to travel with a constant force away from the Earth, there is nothing stopping you from coming back down. Real craft will eventually run out of fuel, and thus must reach escape velocity before that happens, otherwise they will either orbit or fall back down to Earth. | [
"As a tool for learning to control the body flight, there is a vertical wind tunnel, which makes it possible to fly in the air, simulating free fall due to the created air flow (on average, about 190 km/h).\n",
"In most situations it is impractical to achieve escape velocity almost instantly, because of the accel... |
American WW1 vet grave markings. | That's his unit. Company A, 13th Machine Gun Battalion.
See page 76 of this PDF
_URL_0_ | [
"When their remains were recovered after the war, Farrow, Hallmark and Meder were buried with full military honors at Arlington National Cemetery. Spatz was buried with military honors at National Memorial Cemetery of the Pacific.\n",
"The cemetery is an official Commonwealth War Grave Cemetery containing 48 memo... |
-if lance armstrong and his generation were doped to the gills how is it that this generation of cyclists is breaking their records absent significant technology advances and without drugs. | what records are you referring to exactly? if we're talking about the time it takes to climb Ventoux or Alpe d'Huez, [those times have actually gotten markedly worse since the doping crackdown](_URL_2_). in both cases, the best certifiably clean result isn't in the top 10 times up those climbs. or the top 20 (i'm looking at Sanchez's 2011 and Froome's 2013 attempts, Sastre is still a bit questionable in my opinion). this doesn't seem surprising at all in context--not doping should cause the time it takes to ride these climbs to increase. they certainly aren't record breaking. i'm mentioning this because this is the only sort of record Armstrong would really have been able to take, as this was kind of his forte.
how about a one-day race then? paris-roubaix is (arguably) the most important of these. [the fastest average speed was set in 1964](_URL_3_). though i give credit to cancellara for an excellent ride in 2013, there are plenty of fast editions of this race that have been ridden over the years--they don't seem to be concentrated on a particular time period.
ok, so maybe you mean the [hour record](_URL_1_)? the hour record rules have been officially changed in the last year. several people have attempted or are planning on attempting to beat it. it's a brand new metric, and it isn't comparable to either of the old hour record definitions, which top level cyclists largely ignored.
records in track racing? sure. those get beaten at an incremental rate. but then again, doping doesn't really seem to have hit the track discipline quite as hard as it did with road, [as evidenced by the amount of doping cases in either](_URL_0_).
**tl;dr** this generation of cyclists really *aren't* beating records, at least not on the road. | [
"In 2009 director Alex Gibney set out to film \"The Road Back\", a documentary on cyclist Lance Armstrong's comeback year after a four-year retirement from the sport. Three years later, on October 2012, a doping investigation led to his lifetime ban from competition and the stripping of his seven Tour de France tit... |
why do people think that jeffrey epstein’s death seems like a coincidence? | At this point he was ready to bring down the people around him with him. He was a liability for all of the guilty elites that took advantage of his services. He already almost died once due to a cop beating him senseless, so this isn’t that big of a surprise. | [
"Epstein died of an overdose of Carbitral, a form of barbiturate or sleeping pill, in his locked bedroom on 27 August 1967. He was discovered after his butler had knocked on the door and then, hearing no response, asked the housekeeper to call the police. Epstein was found on a single bed, dressed in pyjamas, with ... |
why do bad smells seem to be so much more resilient than good ones? | I would assume that it is because bad smells are most often things that can negatively affect our health, like feces and rotting food and we should avoid as long as it is around.
The running shoes example doesn't exactly fit, although that may be due to cultural/evolutionary distance from apes in the same way that sweaty stinky men don't attract women like pheromones do in other animals.
On the other hand, good smells like flowers and fresh fruit are often not directed at humans specifically but other mammals and birds that the plants "want" their seeds/pollen spread by which likely have stronger senses of smell.
(I can expand on it more if it isn't ELI5 enough) | [
"Smell disorders can result in the inability to detect environmental dangers such as gas leaks, toxins, or smoke. In addition to safety, nutritional and eating habits can also be affected. There is a loss of appetite because of unpleasant flavor and fear of failing to recognize and consuming spoiled food. A decreas... |
when i bend my little finger, why do my other fingers also move? | What happens between the pinky and ring finger is nerve signals sent to the pinky get picked up by the ring finger because your brain can't actually control the pinky very accurately so to do more it sends signals intended for the ring finger. All of your fingers do this to a degree. Try extending all your fingers, and then closing the last 3 while keeping the index finger pointed. You can't do it. It will try to close and after your fingers close then you will be able to straighten it back out.
Now with other fingers, like your index finger closing all the way forces the middle one to go down, involve tendon lengths and muscle connection.
Generally, if it's the top knuckle moving any restrictions are muscular but the second knuckle movement restrictions are nervous. | [
"Thumb twiddling is an activity that is done with the hands of an individual whereby the fingers are interlocked and the thumbs circle around a common focal point, usually in the middle of the distance between the two thumbs.\n",
"You should hold the other two fingers slightly bent, not completely straight. This ... |
If the gene that causes dwarfism is dominant why is it that the percentage of the general population that have this dominant gene is not higher? | Inheriting two copies of the gene usually leads to death in infancy [1], and a lot of achrondroplasic dwarfs have chronic pain, which would cause a general decrease in "fitness" (in the Darwinian sense). It seems fair to say it probably puts people at a pretty serious sexual disadvantage as well.
1. _URL_0_ | [
"As the genetic mutations that cause dwarfing occur in many species, dwarf animals can be the offspring of normal-appearing animals. Even in breeds which have not been selected for dwarfing, some genetic lines may show a tendency to produce dwarfs, which may be encouraged by deliberate breeding. This often takes th... |
Can a strong enough electric field penetrate Faraday cage? | A Faraday cage works because the electrons in the cage respond to an external electric field and re-arrange themselves naturally to create an equal and opposite field.
Hypothetically, if you had a large enough externally applied field that all the free electrons moving from one side to the other does not produce a large enough counter-field then your Faraday cage would fail to block it. However, my feeling is such a strength of field would be very unrealistic. | [
"Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth's magnetic field (a compass will still work inside). To a large degree, though, they shield the interior from external electromagnetic radiation if the conductor is thick enough and any holes are significantly smaller than the w... |
Why is steel stronger than pure iron? | It all comes down to grain structure. Neither steel nor iron is a completely homogenous solid. A single crystal of metal can deform easily along the crystal axes; but if your metal is made up of a large number of small crystalline regions that are oriented randomly, they can't all deform in the same way and the bulk material is stronger.
Adding or removing various impurities (like carbon) changes the crystal grain structure because it changes how the metal freezes from the melt. As the molten metal cools, it separates into multiple distinct phases (like if you freeze salt water, it'll separate into pure-ish ice and brine, and if you get it cold enough it'll end up as chunks of ice separated by frozen brine). If you have the right ratios of impurities, you can control how the metal solidifies and get a grain structure that's especially strong.
This is also what happens when you're tempering, annealing, or work-hardening a piece of metal, fundamentally— you're changing the grain structure, making the grains smaller or larger or differently organized.
[Here's a link to the iron-carbon phase diagram](_URL_0_). It's fairly complicated, and it gets even more complicated when you add other alloying elements (there are tons: chromium, molybdenum, manganese, nickel, vanadium, and on and on). Plus you can get different results by cooling the metal differently (tempering, quenching, etc), since it actually takes time for various individual phases to separate, for crystal grains to grow, etc. This is what makes metallurgy interesting.
| [
"Steel has much higher strength than wrought iron and allowed long span bridges, high rise buildings, automobiles and other items. Steel also made superior threaded fasteners (screws, nuts, bolts), nails, wire and other hardware items. Steel rails lasted over 10 times longer than wrought iron rails.\n",
"Iron is ... |
in court how do they compensate swearing the oath on bibles for people who arent religious or are not christian? | In the US, very few jurisdictions have people swear on bibles anymore. Those that do offer alternates to non-Christians. Some religions, like the Jehovah's Witnesses, who do not allow swearing, are allowed to affirm instead.
Note there is no legal significance to swearing on the bible or any religious book, it is purely symbolic. All the swearing process means is that you are promising to tell the truth and acknowledging that you can be charged with perjury if you do not. Any religious trappings are legally irrelevant to that purpose. | [
"On May 24, 2007, Superior Court Judge Paul Ridgeway ruled that people of non-Christian faiths must be allowed to use religious texts other than the Christian Bible when being sworn in as jurors or witnesses in state court proceedings. Though the state had 30 days to decide to appeal the ruling, it took no action.\... |
What is it about Jamaican culture - opposed to other Caribbean nations - that produced so much extraordinary music? | Not to stifle discussion, but /u/hillsonghoods wrote [some fantastic replies to a similar question](_URL_0_) of mine which I'd recommend checking out. | [
"Jamaica's most popular musical forms are reggae and dancehall. There are also others such as \"dub poetry\" or chanted verses, Ska, and Rocksteady, with its emotionally charged, celebrative beat. Jamaican Americans also listen to a great variety of other music such as: jazz, calypso, soca, ska, rap, classical musi... |
What do we know about the Helots before they were enslaved by the Dorians/Spartiates? Did they ever manage to liberate themselves? | The ancient sources for helots are of such paucity and quality that scholars keep getting to diametrically opposite conclusions about who they were, what was their servial status, and the timing of their servitude. If you're interested in Helotry, I'd recommend this [collection of essays](_URL_0_), edited by Susan E. Alcock and Nino Luraghi. It's a fascinating book and great because many of the authors hold completely contradicting views, reflecting how 'thorny' the whole topic is. Following is a brief outline of the basic facts that most academics (well, me at least!) agree with.
As the holy *Oxford Classical Dictionary* reminds me, other Greek states than Sparta had servile populations which were not privately owned *douloi*, but, because their status seemed superior in important respects, came to be categorized as ‘between free men and *douloi*' (Pollux 3. 83). When discussing non-Doric states, we might call them serfs etc.; 'helots' is specific to Laconia and Messenia. 'Helots' were thus not an oppressed ethnic group, but rather a term referring to a certain social class. Helots could be manumitted (although at least in Sparta, in only exceptional circumstances) and thus 'stop' being helots. Our best sources to helots are about Spartan helots - I cannot say to what extent the Spartan example can be generalized into other Doric city-states. In Sparta, helots had some property rights, unlike slaves (which weren't very common in classical Sparta, mind), and whereas slaves were always considered as a personal property of one individual, helots were sort of considered to be the property of the citizen community as a whole. Spartan helots had some military obligations, too, whereas slaves did not; their main responsibility, however, was to provide their Spartan masters and mistresses with a fixed quota of natural produce.
To answer your question, what do we know about helots before they were helots; not much, really. It is believed that the classical helots are descendants of those Greek peoples that the Dorians enslaved during the [Dorian invasion](_URL_2_), somewhere between the 7th and 10th centuries. The word 'helots' (*heilōtai*) is most likely derived from a root that means *to capture*, and the helots certainly 'enjoyed' the position of being ritually demeaned and considered as a sort of the 'enemy within' in the Spartan state (J. Ducat in his *Spartan education* stresses this 'ritual demeaning' of helots), on top of the very real fear of a helot revolt (e.g. [Thucydides 4.80](_URL_1_)). Every year, the Spartan [ephors](_URL_3_) ritually declared a war against the helots, and Spartans could guilt-free kill helots. The ancient sources suggest that this was to keep the massive helot population in check, which the ancient authors believed to by far outnumber the citizen population. Not that it made any sense for the Spartans to kill helots on everyday basis; the helots were basically the bedrock of the Spartan states as their main source of agricultural labour. The most famous example of the helot oppression is of course the infamous *krypteia* institution, which was an initiation rite for young Spartan men where they went to the countryside in groups to randomly kill helots with daggers (well, this is the picture Aristotle paints; e.g. Plato described it a bit differently).
Helotry survived as an institution well into Hellenistic era, and it wasn't the helots who freed themselves in the end. Helots survived as a self-perpuating body until Theban general Epaminondas freed the Messenians from the Spartan league in 369, and the remaining Laconian helots weren't freed until early 2nd century B.C. A revolutionary chap called Nabis seized the Spartan crown around 207 B.C., and he put under way some badly needed modernizations, including effectively ending the status of helots, and also the *periokoi* class of citizens was practically abolished later during his reign.
EDIT: spelling | [
"In the \"Bibliotheke\", \"Dorus received the country over against Peloponnese and called the settlers Dorians after himself.\" According to Karl Kerenyi, the Dorians recalled that three times Heracles had aided their \"oldest king\", Aigimios, \"under whom they had not yet emigrated to the Peleponnesos.\" Kerenyi'... |
how do we get propane and other gases from the ground? | We refine crude oil which contains gases in the oil(similar to carbonated beverages but less fizzy) and can undergo chemical reactions which will take bigger molecules and break them down into smaller molecules, like propane, which we then seperate out. | [
"Propane and butane are gases at atmospheric pressure that can be liquefied at fairly low pressures and are commonly known as liquified petroleum gas (LPG). Propane is used in propane gas burners and as a fuel for road vehicles, butane in space heaters and disposable cigarette lighters. Both are used as propellants... |
Does picking up a radio signal with a antenna reduce the power of the signal, even minimally? | Substitute "radio signal" with "sunlight" and "antenna" with "solar cell".
You assume that there's such thing as _the_ power of the signal, as a property of the emitter that everyone has direct access to. No, radio waves are not fundamentally different from light, so what you have instead is independent power of the signal in various places; receiving the signal with an antenna removes it from that particular region of space and creates a radio shadow behind it.
So for example to black out a radio emitter you have to build a [Faraday cage](_URL_0_) around it. | [
"So much wasted power is not acceptable in a transmitting antenna, however in a receiving antenna the inefficiency is not important at frequencies below about 15 MHz. At these lower frequencies, atmospheric noise (static) and man-made noise (radio frequency interference) even in the weak signal from an inefficient ... |
Does running through the rain make you more or less dry than walking? | If you look at this problem by trying to figure out your wetness as you walk through the falling rain, then it can be pretty tough. But it actually becomes easier if you look at it from the frame of reference of the falling rain. In this reference frame, the rain is just sitting there, still, and the ground is moving up through it with you moving along. Then, as you move through it, you will carve out a tunnel through the rain and how wet you get will be proportional to the volume of this tunnel.
To get the volume of this tunnel you can simplify it further by noting that it's basically just a thickened line, and so the volume will be roughly proportional to the length of this line. The slope of this line will depend on how fast you go. If you go really, really, slow, then the line will be very steep, as you are going more up through the rain than forward. It will be very, very shallow if you go really fast, as the ground hardly has time to move up before you're done. In general, then, this line traced out by your path is the hypotenuse of a right triangle. The bottom leg of this triangle is just the distance that you have to go across the ground, L, and the height of this triangle is basically the amount of time you spend in the rain, T (well, proportional to it depending on how fast the rain is falling). The length of this line, and the subsequent volume of rain you carve out, is then given by the Pythagorean theorem as the square root of L^(2)+T^(2).
So how wet you get is then basically proportional to sqrt(L^(2)+T^(2)). Since L doesn't change the only way you can make this less is to make T smaller, which means running faster.
[MinutePhysics](_URL_0_) has a more well put together presentation of this. | [
"Running is an effective way to reduce stress, anxiety, depression, and tension. It helps people who struggle with seasonal affective disorder by being more outside running when it's sunny and warm. Running can improve mental alertness and also improve sleep which is needed for good mental health. Both research and... |
why do stenographers use those tiny typewriters? | They're [stenotypes](_URL_0_) which are much faster than typing, but don't transcribe speech directly into readable English but into a form of shorthand.
Why? It's quicker - the words are formed with "chords" rather than letter at a time. | [
"A number of typographical conventions originate from the widespread use of the typewriter, based on the characteristics and limitations of the typewriter itself. For example, the QWERTY keyboard typewriter did not include keys for the en dash and the em dash. To overcome this limitation, users typically typed more... |
how did the wwii enigma code machines work? | It's pretty cool, actually. I'll start with the basics. Each letter on the keyboard is connected, or paired, to another letter. So, if you press the A key, for example, you might see K light up. Similarly, if you press K, you'll see A light up. So, if you were to press H-E-L-L-O, you might get something like T-W-I-I-M. You send the new message "twiim" to the recipient. The recipient's machine is wired the same as yours, so pressing T-W-I-I-M will result in the letters H-E-L-L-O. Make sense so far?
Here's where it gets interesting. On each Enigma Machine is three rotors that can each be set by the user. Each rotor has a setting from A to Z. So, when I'm using my Enigma, I can set the three rotors to anything I like, such as: G-E-K. The rotors basically take all the letter pairs and scramble them; all the wires that go from and to each letter are shuffled depending on each rotor setting. Imagine a railroad junction where the track can switch between two paths; it's like that, but with 26 different options, 3 different times in a row.
However, if I were to type a message scrambled in this way, it would be very easy to crack because each letter just corresponds with a different letter. If somebody were to intercept the message, he/she could just guess which letters are which and eventually come up with the original message. In fact, this is so simple that newspapers publish puzzles with this encryption format, sometimes known as a CryptoQuip. [Try it yourself!](_URL_0_)
This is where the brilliance of the Enigma machine comes in. Every time you press a letter on the keyboard, the rotors turn. (kachunk!) So, the letter pairings are completely rescrambled with every letter you choose. Suppose my rotors were set to: G-E-K. After I press a single key, the rotors will shift to: G-E-L, and so on, until G-E-Z, and then G-F-A. Anybody who intercepts the message won't be able to pair up letters because every single character uses a different pairing schematic as defined by the rotor setting. Even if the interceptor has an Enigma Machine, he/she can't decode the message unless the rotors are set the same way. The rotor settings can't efficiently be guessed by hand because there are 26 * 26 * 26 = 17,576 different settings to try. This, combined with the plugboard settings for each letter, and the option of shuffling the rotor order, means there are about 10^21 possible combinations to go through. (Modern computers can do this with some work.)
So, as long as the sender and receiver use the same rotor settings, the letter pairs are matched. Plus, each time a key is pressed, the rotors rotate, including for the receiver. So, the receiver's rotors stay in sync with the sender's, allowing for total encryption and decryption for both parties.
Fun Fact: The Enigma was cracked not because its encryption method was flawed, but because radios were very poor quality. The protocol was to repeat certain key letters to make sure that the receiver didn't miss any info, but the extra information made the messages mathematically feasible to crack. | [
"In the lead up to World War II, the Germans made successive improvements to their military Enigma machines. By January 1939, additional rotors had been introduced so that there was a choice of three from five (i.e. 60 wheel orders) for the army and airforce Enigmas, and three out of eight (336 wheel orders) for th... |
the lean six sigma methodology | LEAN and 6sigma address two different aspects of factory production.
LEAN applies analysis to find the minimal cost steps needed to produce the item. It could mean the difference between giving a power tool to a worker instead of a manual tool. or having a conveyer delivery belt move the component to the worker instead of the worker walking around the factory to get the components from their bins. all of it centers on the methods to measure and reduce the cost of the production in both time and money (which boils down to same thing).
6sigma is concerned about whether items that come out of production all meet quality control standards. bad items are categorized as errors vs defects. errors are caught inside the production area. defects make it out of production area. the total cost of an error is the time and cost to remanufacture the item within the production area. the total cost of a defect is error cost PLUS defect management overhead cost PLUS potential customer impacts. 6sigma goals is to measure the existing rates and find ways to reduce the rates.
1sigma is 69% mistakes.
2sigma is 30% mistake.
3sigma is 6.68%.
4sigma is 0.6%
5sigma is 0.0233%
6sigma is 0.00034% | [
"Lean Six Sigma is a synergized managerial concept of Lean and Six Sigma. Lean traditionally focuses on the elimination of the eight kinds of waste/\"Muda\" classified as defects, over-production, waiting, non-utilized talent, transportation, inventory, motion, and extra-processing. Six Sigma seeks to improve the q... |
how do the "check to ensure you're not a robot" things actually work? what prevents computers from "clicking all pictures with a car"? i'm especially confused with the ones that dont require you to do anything except check the box. does somebody have an explaination? | It checks the way that the person clicks the button (path, speed, etc) to determine if the clicker is indeed a human | [
"Machine checks are a hardware problem, not a software problem. They're often the result of the overclocking or overheating, causing errors, or hitting a thermal limit where the CPU must shut itself down to avoid permanent damage. But they can also be caused by bus errors introduced by other failing components, inc... |
how did mayweather win that fight? | Pacquiao was the aggressor for most of the fight, and he swung a lot more. The crowd was clearly on his side, and Mayweather rarely drove forward.
But these things don't matter to the judges, or at least they shouldn't. Who was better at landing punches, who dictated the pace, who did the most damage, these things matter. And Mayweather did all those things. He threw less, but landed more. His hits were doing more damage. It was very rare that Mayweather ever seemed trapped, even buried in the corner.
Pacquiao need a lot more of those flurry pieces, and he didn't get through Mayweather's defense most of those times.
EDIT: it's been brought to my attention that MW actually threw MORE punches as well. Paq threw more power punches but MW threw more total punches. Thank you fellow redditor for pointing that out. | [
"Having recovered from Pacquiao's big hit in the previous round, Mayweather won the early exchanges of the fifth round. Pacquiao remained on the offensive, but was unable to land any big punches. Mayweather upped his activity and won the round in the eyes of the three judges. Pacquiao came out aggressive in the six... |
at the large hadron collider, how do the scientists get the 'right' protons into the machine? | You're overthinking the way it actually works.
What happens is they use a source that generates literally billions and billions of protons, these are all then accelerated around the machine and then finally allowed to crash into each other. Most of them don't even hit each other and are just absorbed. If the scientists are really, really lucky some of the protons WILL hit each other, if they're luckier still then when they hit each other they'll decay into simpler particles, and if it's the scientists' best day ever they'll decay into the exact simpler particles they've been looking for. | [
"The Proton Synchrotron Booster (PSB) is the first and smallest circular proton accelerator (a synchrotron) in the accelerator chain at the CERN injection complex, which also provides beams to the Large Hadron Collider. It contains four superimposed rings with a radius of 25 meters, which receive protons with an en... |
What was the origin and meaning behind the haircuts of Medieval Japan? | Frankly I only know of the common topknot ("Chonmage") which was mostly done as a way to ensure that the kabuto helmet would fit snugly on one's head. The idea was that the topknot would be able to fit through a small hole in the helmet. Over time, while this tradition was forgotten, as the bushi and local daimyo began to take power, they continued using topknots as it was a sign of their military prowess. | [
"In the early 1870s, in a shift that historians attribute to the influence of the West, Japanese men began cutting their hair into styles known as jangiri or zangiri (which roughly means \"random cropping\"). During this period, Asian women were still wearing traditional hairstyles held up with combs, pins and stic... |
(if your country has them) why do drinks in king-size cans cost less than the normal cans? | There are a lot of fixed costs in packaging drinks and the price of a bigger or smaller can may not make much difference. Most of an items price has nothing to do with the size.
I designed labels for a big box store once and learned that the difference in cost to make a 16oz can of soda and a 32oz can is often less than 1 cent per can.
Naturally, even if it is priced less than the smaller cans, there's still room for profit.
Here's an example of all of the math involved. Hope this helps!
_URL_0_ | [
"In both Malaysia and Singapore, the most commonly found cans are 300 ml for non-carbonated drinks and 325 ml for carbonated drinks. Larger 330 ml/350 ml cans are limited to imported drinks where it would usually cost a lot more than local ones.\n",
"250 ml cans are the most common for soft drinks, but when accom... |
4 continuous hours in the sun results in a sunburn, but 4 hours broken up into 15 minutes chunks does not. | The explanations so far are not correct. 4 continuous hours of sunlight will give your damaged cells less time to repair DNA and less time to apoptose (safely die without causing inflammation).
4 hours spread out over increments gives your cells time to repair DNA and, if need be, apoptose irreparable cells in-between exposures.
If you do not have this break time in-between exposures, cells will become damaged so badly that they cannot die in a safe, organized manner (apoptosis). Instead, they die quicker and release their proteins into the space between cells. Nearby cells sense this, freak out and release chemicals that cause inflammation and pain.
Additionally, immune cells in skin undergoing DNA damage from UV may directly contribute to inflammation.
Fun fact: When you feel heat, when you are out in the sun, it’s from infrared light. A lot of people have the misconception that they aren’t feeling the heat from the sun, so they aren’t getting burned. The “heat” (really just pain) from a sunburn will come on much later, and is produced by inflammation and hypersensitive nerve endings.
Edit: I should add. Even if your 4 hours is broken up into increments, if you’re fair-skinned, you’ll probably still get burned. | [
"Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious.\n",
"Recurring yearly, the eruption can sometimes last longer than a few days if persistent and rep... |
what are these new-age solid-state batteries? how are they different from conventional batteries? | They're batteries that use solid electrodes or electrolytes instead of liquid.
They have potentially higher energy density, and are safer since they're not flammable. They also have longer lifespans and don't produce as much heat.
I think the problem at the moment is that they're not ready to be mass produced and so they're expensive. | [
"A solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries. Materials proposed for use as solid electrolytes in solid-state batteries include ceramics (e.g. oxides, sulfides, p... |
When I think of the legacy of dueling, I picture it as an exclusively male enterprise. Is this really the case? Or are there records of women dueling as well? | Not discouraging any new answers coming in, but you better believe that /u/Georgy_K_Zhukov wrote about [this topic already](_URL_0_). Hope it helps! | [
"In tennis, \"Battle of the Sexes\" is a term that has been used to describe various exhibition matches played between a man and a woman (or, in one case, a doubles match between two men and two women). Most famously, the term is used for a nationally televised match in 1973, held at the Houston Astrodome, between ... |
how does a bike roll down a hill (balance) with no assistance? | Conservation of angular momentum. The wheels of the bike are spinning on a particular plane, and they naturally "want" to continue spinning on that plane, so they resist any change in that motion. In this case they resist the bike tipping over due to gravity. The faster they are spinning (meaning the more momentum they have) the more they will resist a change in that momentum. Once they slow down and lose momentum the bike will tip over. | [
"A cyclist executing a basic track stand holds the bicycle's cranks in a horizontal position, with his or her dominant foot forward. Track stands executed on bicycles with a freewheel usually employ a small uphill section of ground. The uphill needs to be sufficient to allow the rider to create backward motion by r... |
why (in the u.s) we are taxed twice, and in many cases a third time, on the same income? | There's nothing illegal for different taxation at different levels of government for different purposed. Different taxes are for different governing bodies, some are more regressive, some more progressive, some go to specific uses while others go to general revenue streams. The amount needed to be collected is the same, so whether it was a 50% state income tax that also got distributed to cities and the Federal gov't or paying 3 different levels of taxes don't change the totals... in fact they might be higher, because different levels have different types of credits, etc. Like you might lose mortgage interest deduction if you didn't pay the Feds directly. | [
"Taxes are most often levied as a percentage, called the \"tax rate\". An important distinction when talking about tax rates is to distinguish between the marginal rate and the effective tax rate. The effective rate is the total tax paid divided by the total amount the tax is paid on, while the marginal rate is the... |
the "internet" to someone from the 1950s | Basically just go over the history of computers so that each step is easy enough to imagine from the last:
You know adding machines? Well we've made them better. Much better. Instead of being mechanically constructed to do sums or other things with numbers we enter with some buttons we've extended them to be able to do all that calculating from instructions written on 'punch cards'. The punch cards specify what numbers to work on and how. This way we can, without needing a human to press all the buttons or work it all out, get this computer to perform complex calculations. It can count up all the numbers fed into it by the punch cards or get the ratio of how many of the values are above or below 5 or something, etc. Basically we replaced the buttons on the adding machine for pre-made punch cards that let you do the same thing without needing a human to push all the buttons. By putting census data or something on the punch cards we can feed it data and cards quickly without a human punching it all in manually.
Next we started advancing it further - instead of punch cards we made electricity the 'card'. Just like in a radio a current is used to make the speakers vibrate differently - and thus make noise - we can use a current to signify data or instructions to the computer. Varying voltage is used rather than holes in cards. This lets us feed things into the computer much faster.
Additionally we found ways to store the data without the cards. It's possible to make extremely small 'marks' on special-made disks. It's almost like grammophone records. We mark these disks and can read them back with a very small head.
This lets us store data and instruction sets on these disks which are far smaller than punch-cards and can be fed in more quickly.
We then took these so-called 'drives' and integrated them into the computer directly so we didn't have to load every instruction set or data set in disk by disk. Now you could save commonly-used instruction sets to the computer and the computer had a mechanism added so you could just ask it to load these programs from the drive. This meant we no longer needed to load the new instruction set every time we wanted to do different things; an operator could switch what it was doing quickly.
Next we made typewriter like 'keyboards' for the computers that let us start interacting with the computer. Special instruction sets were made to react to things we typed into it. If I typed in 'echo 5 + 5' the special instruction set would get the computer to add 5 and 5, then put the result on the monitor. (The monitor being like a TV that the computer can control to produce images for us.)
In time these computers were connected to the phone networks. Now computers could place calls to one another and exchange data using the phone network. This let us share things between computers. People started making centralized centres of knowledge for all sorts of things and we could ask our computer to call them to see this data on our own computer.
Eventually the phone-line system was replaced with a dedicated cable network just for computer to talk to one another. | [
"The history of the Internet begins with the development of electronic computers in the 1950s. Initial concepts of wide area networking originated in several computer science laboratories in the United States, United Kingdom, and France. The U.S. Department of Defense awarded contracts as early as the 1960s, includ... |
I was told that there is so much historical proof of jesus' ressurection that you can't claim it didn't happen, how true is this? | **Commenters:** Please keep our commenting rules in mind as you respond to this. We've already had to remove a lot of comments that weren't up to the standards of the subreddit.
**OP:** We actually have this question asked from time to time, or questions like it. You might be interested in these previous posts:
* [So, what do we actually know about the life, existence, etcetera of the man called Jesus Christ?](_URL_0_)
* [What do we really know about Jesus Christ?](_URL_5_)
* [How is it that we can have so much concrete information on Ancient philosophers like Parmenides and Plato, yet so little on Jesus?](_URL_6_)
* [What are your views on the mentioning of Jesus in Josephus' histories? Added later by people copying it down or authentic?](_URL_3_)
* [I'd like a real historians critique of American Biblical scholar Joseph Atwill's "new discovery": ancient confessions recently uncovered now prove that the New Testament was written by first-century Roman aristocrats and that they fabricated the entire story of Jesus Christ.](_URL_4_)
* [What do we actually know about Jesus?](_URL_2_)
* [How much evidence is there for a historical jesus christ besides the bible?](_URL_1_)
| [
"Many testified falsely against Jesus, but their statements did not agree. At last two witnesses said they had heard Him saying He would destroy that temple and in three days built another, not made with hands, (He really had meant the resurrection of His body, as a temple of the Holy Spirit, destroyed by others bu... |
Can we create artificial atmospheres? | It's hard, because planets are big.
Think about what an atmosphere is. It's an razor thin envelope of gas that wraps around the surface of a rocky planet. There's no way to *fake* that. You don't want an *artificial* atmosphere, so much as you are actually asking for a real *bona fide* atmosphere.
To give the moon an atmosphere, you would literally need to come up with all of those gas molecules, the whole billion megatons of them. For perspective, [the mass of the earth's atmosphere is about 5x10^18 kg.](_URL_0_) I don't even know the SI prefix for that amount of mass- is that an exagram? Like a million billion kilograms? Good luck.
For the moon, there's just no way to come up with that amount of matter. But there's a bigger problem: the low gravity and the lack of a magnetic field. The moon's magnetic field is basically nonexistant compared to the earth, and it's smaller mass makes it less able to hold onto any gas at it's surface. This means it has no way to hold onto what it has or really shield itself from the solar wind, which is the wall of charged particles and radiation the sun is throwing out in every direction. This will strip the planet of any atmosphere in no time.
[Edit: Astromike saves the day again, please see his comment below for a more accurate account of this.](_URL_1_)
Mars, similarly, has this problem. Mars is no longer tectonically active, and it's magnetic field has largely died. If Mars once had water, there isn't much of it left in the atmosphere. The water molecules, without the shielding of an ozone layer and magnetic field, would get broken up by the high energy rays from the sun into separate hydrogen and oxygen, and that hydrogen would float up to the top of the atmosphere (because less dense things like to be on top of more dense things, like oil on water), and would get stripped by the sun. Any Martian water that survived this dessication is either locked up in the polar ice caps, or underground.
So in an *xkcd-eqsue* what-if scenario, what if we wanted to make Mars habitable? Well there's a large science fiction literature about that, called terraforming. Terraforming involves processing the natural atmosphere of a planet or moon into one that is more earth like. In the case of Mars, you would want to add green house gasses to warm the planet.
Possible mechanisms include:
1. Bringing in large amounts of ammonia from comets to serve as green house gases to melt the polar ice caps. But how do you get them there? It's hard enough getting people to the ISS, let alone doing astronomical construction projects.
2. Set up solar panels that will use the energy they generate to break the Martian CO2 atmosphere into carbon and oxygen. But CO2 is really stable and carbon needs something to bond with, so where are you going to come up with that material to serve as your carbon sink? And if this was so easy, why not do it on earth and solve global warming?
3. Put a satellite with a mirror in orbit to focus light onto the polar ice caps, melting them. But you'll need a really fucking big mirror to even make a dent. Annual difference due to solar weather will make more of a difference than your mirror.
Remember, the sum of humanity has been pumping carbon dioxide into the earth's atmosphere for the better part of 200 years, and the effects have been slow to appear, so slow that's it's still hard to convince Americans it matters. So now how do you get a small team of scientists to do it on a planet we haven't even set foot on yet? | [
"There are two basic choices for an artificial atmosphere: either an Earth-like mixture of oxygen in an inert gas such as nitrogen or helium, or pure oxygen, which can be used at lower than standard atmospheric pressure. A nitrogen-oxygen mixture is used in the International Space Station and Soyuz spacecraft, whil... |
why do space craft enter the atmosphere at full velocity, requiring heat shields and risking burning up? | "at the expense of additional fuel"
That's a really big expense, both in cost and weight. Its just literally not economically viable right now to do it that way. Though things like space x are starting to work on it.
Right now it makes most economic sense to just let it burn and crash and rebuild it, because thats how much more expensive that extra fuel is. | [
"Spacecraft that land on a planet with an atmosphere, such as Earth, Mars, and Venus, currently do so by entering the atmosphere at high speeds, depending on air resistance rather than rocket power to slow them down. A side effect of this method of atmospheric re-entry is aerodynamic heating, which can be highly de... |
the earth is about 4.5 billion years old, but at what physical point do scientists classify a planet's age as 0? | When it started to be a planet.
To be a planet, it needs to fit three criteria:
A planet is an object in orbit around the Sun with a diameter greater than 2000 km.
A planet is an object in orbit around the Sun whose shape is stable due to its own gravity.
A planet is an object in orbit around the Sun that is dominant in its immediate neighbourhood.
So, basically, it needed to coalesce into a stable shape and clear out the immediate neighbourhood.
There's no hard-and-fast answer of when it "became" a planet. There's no point where you can say "Before this instant, it was not a planet, but now it is."
Just like how if you have a pile of seeds, and then take one seed away at a time, you can't say there's a specific time when taking away a single seed made it from a pile into something that isn't a pile anymore. Obviously if you have only one seed, it isn't a pile. Is two seeds a pile of seeds? Probably not. | [
"The age of the Earth is estimated to be 4.54 ± 0.05 billion years This age may represent the age of the Earth's accretion, of core formation, or of the material from which the Earth formed. This dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric age... |
How much body heat do you lose in your legs compared to your arms? And in your hands and feet? | heat loss is fairly uniform throughout the body. | [
"The burn percentage in adults can be estimated by applying the Wallace rule of nines (see total body surface area): 9% for each arm, 18% for each leg, 18% for the front of the torso, 18% for the back of the torso, and 9% for the head and 1% for the perineum.\n",
"Normally, extremities such as the hands are lower... |
Theoretically could you implant cones into your eyes that would allow you to see colors you could previously not see? | Perhaps. Experiments have been done where new visual pigment proteins have been introduced into red-green colorblind monkeys, and afterwards the monkeys could distinguish colors that they were not able to previously. However, these experiments did not implant new cones into the monkey retinas. Instead new proteins were expressed in previously existing cones, and the circuitry already in place adapted to the new spectral properties of the photopigments.
See the [Neitz Lab website](_URL_0_) or their [published paper](_URL_1_) for more info. | [
"Neitz further states that since apparently \"the neural circuits can handle even higher dimensions of color vision that could come from artificially adding a fourth cone type, it is possible that gene therapy could also be used to extend normal human color vision\", making human trichromats into tetrachromats.\n",... |
Was Russia/Stalin truly hoping to share the Europe with Germany/Hitler or was Stalin playing a waiting game? | First of all let me say that Stalin didn't leave a diary so we can't exactly say what his emotions or personal thoughts were with confidence. That said, he was probably neither of those things.
The idea that he locked himself in a room for 3 days is certainly not true. We do have a record of his itinerary of the first day after the German invasion. Stalin spent the entire day meeting senior officials and generals, from before 6am to after midnight. He continued to have a fairly busy schedule that entire week. Nor could we say that he was really "shocked". Under a cover of military exercises, the Red Army began to mobilize before the Germans had invaded and certain units were ordered to move toward the border. A special directive was issued to the troops that an imminent attack was likely. All of these steps were significantly belated - mobilization should have began nearly a month prior. To say that Stalin was completely shocked would be misleading. Also to say that Stalin and Hitler were "friends" is a bit preposterous - the two have never met or even interacted directly.
That said you COULD make a case that Stalin fell into a state of despair or panic slightly later, about a week after the war began, when it became clear that things were developing catastrophically, the city of Minsk had fallen, and that war might be lost. He retreated to his dacha outside of Moscow, and didn't see people for a period of 3 days. Stalin is described as depressed. When several senior officials came to visit Stalin, upon seeing him he supposedly thought they came to arrest him. However this hypothesis, too, is tenuous. Stalin frequently worked in his dacha, so him being there isn't really evidence of him trying to hide. Almost all evidence comes down to memoirs of a single person, Anastas Mikoyan. Unlike several people who later wrote about Stalin's possible depression, such as Khrushchev, Mikoyan was the only one actually on the scene. It is certainly possible that Stalin was feeling down after receiving terrible news from the front. Anthony Beevor writes that Stalin even floated the idea to offer huge swaths of western USSR (including Ukraine and Belarus) to Hitler in exchange for peace but was then dissuaded of this. In short, it seems that Stalin was more affected by how poorly the war was going rather than the start of the war itself. Beyond that, there isn't a whole lot of evidence to go on, beyond a couple memoirs and speculations of Stalin's associates.
Lastly, there is the idea that Stalin himself was about to invade Germany and that Hitler just preempted him. This hypothesis was popularized by a former Soviet spy who wrote under a pseudonym Viktor Suvorov. However, almost no reputable Russian or western historian supports this idea. While it is definitely possible that Stalin planned to eventually attack Germany, it is extremely unlikely that would have happened that year. The Soviet military was undergoing wide-sweeping reforms and reorganization and was in no shape for a major war at the time.
EDIT: My first gold ever - thank you kind sir/lady! | [
"The Soviet Union was not invited to the critical Munich conference in late September 1938, where Britain, France and Italy appeased Hitler by giving in to his demands to take over the Sudetenland, a largely German-speaking area of Western Czechoslovakia. Distrust was high in all directions. Leaders in London and P... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.