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w3ya5
|
the barclay's scandal and why it's garnering the amount of hype that it is.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/w3ya5/eli5_the_barclays_scandal_and_why_its_garnering/
|
{
"a_id": [
"c5a6la8"
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"score": [
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"text": [
"There's a group of 16 banks that get together to set LIBOR. LIBOR is the London Interbank Offered Rate. This is the rate used to determine interest of a lot of loans - from car loans, home loans, credit card loans, etc.\n\nIf you knew what the rate was ahead of time, that would give you a big advantage in betting on loans, making loans, etc. For this reason, the people setting the rate and the people making those bets are supposed to be separate from each other to avoid a conflict of interest.\n\nWhat happened is that someone leaked emails from Barclay's showing they were trying to change the rate so they could make money. They got other banks to help them (a big no-no) and had the people setting the rate and the people making the bets tell each other what's up (another no-no) and probably ended up costing other people lots of money by essentially cheating with the loan rate.\n\nThey are already being sued by several large retirement funds that think they have been cheated out of millions of dollars. Since that rate affect $300 trillion (with a T) dollars in financial products, this could have a huge effect on the global economy."
]
}
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[
[]
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13pp5r
|
How exactly does space weather impact the earth?
|
Hey everybody, I'm a dutch physics/astronomy major ( started in september ) and i've been looking up on how exactly space weather impacts the earth. We've dabbled a bit in solar weather during lectures but it wasn't really indepth. I'm especially interested in how it affects the magnetosphere and atmosphere as well as things on the surface.
I got to say though, most website really don't give any in depth answers to my question. Mostly the things I find are a lot like this :
> Solar flares impact Earth only when they occur on the side of the sun facing Earth. Because flares are made of photons, they travel out directly from the flare site, so if we can see the flare, we can be impacted by it.
And that's quote from the nasa site.
Honestly, telling me that it has an impact on the earth really doesn't mean anything to me unless you tell me how and show me some articles or something, thanks nasa.
You guys think you can help me satisfy my curiosity?
TL;DR: what exactly are impacts of space weather, like Coronal mass ejections, solar wind and solar flares on our atmosphere/magnetosphere or surface of the earth.
Quick edit here : here's an other thing i dont get. If charged particles from solar winds are deflected by the magnetosphere, how do they even get through the magnetosphere? Do they even? How does the plasma from CME's pass through the magnetosphere?
|
askscience
|
http://www.reddit.com/r/askscience/comments/13pp5r/how_exactly_does_space_weather_impact_the_earth/
|
{
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"text": [
"This is a rather multi-faceted question. Lets separate the components of space weather and try to address them in isolation, however unnatural that is.\n\nSolar flares, x-ray flares, can directly ionize the upper atmosphere and sometimes even lower levels. This ionization is measured as increased total electron content (TEC). Increased TEC changes radiowave propagation behavior and can lead to multi-path and interference issues as well as induced polarization rotation by the faraday effect. These combined sometimes lead to increased margins of error for sensitive applications like GPS. Or they might increase the distance that a ham radio operator can make contact around the curve of the Earth. It depends on many variables.\n\nAssociated with strong, impulsive flares sometimes are events called SEP: solar energetic particles. This is a description of a near relativistic burst of protons (and a few heavier ions) that are associated with the magnetic reconnection driving the flares. These particles then travel out from the active region into interplanetary space but in doing so their path is bent by the interplanetary magnetic field (called a parker spiral). So, in order to intersect with Earth the pointing on the surface of the sun must be precise. This usually means about ~60W longitude on the solar photosphere. In terms of Earth effect these SEP events the rigidity of the particle paths is high and they can penetrate the Earth's magnetic field without much net deflection. When a SEP is recorded at ground level is quite notable (called GLE, ground level events). The ionization of the lower atmosphere (troposphere even) from these rare events can lead to much different propagation of commercial FM radio and other line of sight communications.\n\nThen there's coronal mass ejections which are sometimes, but not always, associated with xray flares. They can and do happen without xray flares. There are a number of distinct sub-types of CME which can change their \"geoeffectiveness\" in inducing measurable changes at Earth but I'll not get into that here. As a CME expands out into the heliosphere it creates a shocked region of interplanetary magnetic field in front of it. This shocked region acts to ionize and accelerate ambient light ions (fermi acceleration) to high energies (but not as high as a well aimed SEP). These shocked ions will tend to go out in all directions and even if the CME is not going Earthward they'll be detected by the satellites at the L1 lagrange points. Their rigidity is relatively low, though, and they are significantly deflected by the Earth's magnetosphere. The coronal mass ejections themselves consist of charged particles bouncing back and forth almost perpendicular to the direction of travel on average. They are contained with a pseudo-magnetic bottle by gradients in the embedded magnetic field. How exactly that magnetic field is oriented and it's helicity will drastically effect it's impact on Earth. If there is a component of the magnetic field which is pointing down and out of the ecliptic plane of the solar system (direction called -Bz (z axis, B-field, negative direction)) then the magnetic field of the coronal mass ejection will be able to reconnect with the Earth's magnetic field. If this happens then the high energy particles without the CME will be able to enter the outer layers of the Earth's magnetosphere and in doing so their currents will greate a geomagnetic storm. But it is not the CME mass that you see precipitating down the field lines at the magnetic poles. Instead the magnetic reconnection on the day (star facing) side causes similar magnetic reconnection in the magnetotail of the Earth on the dark side. This process then allows particles trapped in the Earth's magnetosphere to snap down to the poles to induce aurora.\n\nThere are other spaceweather events during calm solar times too. The most notable of these is the co-rotating interaction region. On the sun there are distinct regions of slow and fast solar wind depending on weather the region of it's origin has closed or open magnetic field lines. In the regions with field lines open and extending into the heliosphere the solar wind is fast, some 700km/s sometimes, and consists primarily of electrons and a bit of protons. The slow solar wind from the \"helmet\" regions of close field lines averages more around ~300-400 km/s and has significantly more heavy ion (say, Helium) content. Anyway, as the solar photosphere surface rotates on the sun the solar wind shoots off into the heliosphere much like a water spinkler. That is, it seems to make a curved path due to the rotation of the source. When a region of slow solar wind is ahead (in terms of rotation) of a region with fast solar wind the fast will catch up with the slow once it gets an AU out or 3. The momentum transfer from the fast to the slow solar wind creates a shocked region. In this plane the embedded magnetic field can be tilted such that a significant -Bz magnetic component exists allowing the reconnection with Earth's geomagnetic field. This leads to geomagnetic storms much like described for coronal mass ejections.\n\n**If you really want to learn more I recommend the book, \"Exploring the Secrets of the Aurora\" 2nd Edition by Syun-Ichi Akasofu** (a legend in the field). While it is comprehensive and detailed the book is written to allow technically proficient people from outside the field to easily understand. Heck, even a complete layman would enjoy it. If you are unable to acquire a copy send me a PM. I'll *lend* you an electronic copy. \n\nIf you complete that and want to know the exact details of magnetic reconnection and convection allowing particles down to Earth then check out the denser, but still entertaining, \"Convection and Substorms: Paradigms of Magnetospheric Phenomenology\" written by Charles F Kennel. "
]
}
|
[] |
[] |
[
[]
] |
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35hesi
|
Who was eligible to attend the first universities, and what were the benefits of doing so?
|
Along those lines, how do ancient universities (let's say in the 1600s) compare to their modern counterparts? Some more specific questions:
- One big reason to attend uni today is the potential for a much higher salary. Was this the case in earlier times as well?
- Today every student has to pick their major or specialization. Has this always been a thing? If not, when did it first start?
- Most modern students have a side job or two, in addition to their studies. Was this the case in medieval times as well? More broadly speaking, was being a student considered a 'full time job?'
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/35hesi/who_was_eligible_to_attend_the_first_universities/
|
{
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"Part of this will get into a debate over what the \"first universities\" were. As an Arabist I'm more sympathetic to the idea that institutions like the Nizamiyyas were a form of university than many European medievalists might be. At the very least, without getting into the definition of a \"university\" these madrassas were clearly a form of higher education.\n\nIn the Islamic world in the middle ages, who was eligible for higher education and what their benefits were were closely intertwined. While for much of the Middle Ages the political classes of the Islamic world consisted of either steppe peoples or slave soldiers, education offered a path for non-military figures to join the ranks of the elite by becoming members of the Ulema, the religious class of scholars within Islam.\n\nDespite their clearest societal role being as religious leaders and scholars, because so much of late medieval history in the Islamic world the territories of Islamdom were dominated by external steppe peoples, the Ulema actually played a very powerful political role in mediating between the rulers and the ruled. Despite the constant flux of dynasties (Buyids, Ghaznavids, Seljuks, Ghurids, etc. etc.) because the Ulema were able to preserve the legal norms of Islam, they preserved a certain measure of societal continuity despite the total political chaos.\n\nAccess to this powerful political class was, at least theoretically, meritocratic, and even people from humble origins could rise to great heights as a religious scholar. Although of course the requisites of having access to education was inherently favorable to men from cities, and, of course, women had no role whatsoever.\n\nThis relationship between the foreign ruling class and the local intermediaries has been termed the Amir (Warrior Prince)/Ayan (Local Notable) system.\n\nIn terms of \"second jobs,\" I can't speak to knowledge of any of scholars who took up such a job, but I can say that even a junior scholar's preparation would have qualified them for other jobs. Entry to a madrasa would by definition and at a bare minimum have required the student to have memorized the Quran. Qualification as a religious judge would have further required memorization of a set number of hadiths and their respective Isnads (the chains of transmission from the Prophet to the recorder of the hadith) (depending on the time period, the number could reach the thousands.) Having memorized the Quran would allow such students to become Quran reciters, which was a paying position, as well as teachers of the Quran. Although being certified as a Qadi (religious judge) was a far more prestigious (and politically official) position than either of these.\n\nSo to give a bit of **TL:DR** for the Islamic world's answer to your questions, in order:\n\nWho was eligible? Everyone, but with a bias towards urban dwellers.\n\nWhat were the benefits? Access to a powerful political class that was otherwise unavailable to non-military figures.\n\nWould they have gained a higher salary than the alternative? Yes.\n\nMajor or specialization? The curriculum was by definition religious, but depending on the era in question there were different schools of law to choose from.\n\nSecond jobs? I don't know of any scholars who describe having taken such jobs, but even entry-level students would have been qualified to perform a number of roles that were paid.\n\nSources: Marshall Hodgson's *The Venture of Islam* goes into quite a lot of detail about how this political system worked in Islamdom in the Middle Ages with detail about social institutions including Madrasas."
]
}
|
[] |
[] |
[
[]
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4gstxq
|
Did the Roman Senate actually have ~300 and up to 900 senators?
|
The number of senators in the Roman Senate really confused me.
1. During Caesar the senate had up to 900 senators, but the dimension of the Curia Julia doesn't seem to be able to fit that much senators.
2. Most depictions of the Roman Senate, from paintings to TV shows, show a handful of senators - only ~100 at best.
3. Wikipedia mentions that all senators had to speak before a vote could be held, and senators could potentially filibuster until nightfall when a vote could no longer be held - wouldn't that happen anyway if the Senate had 300 memberes? What about the pedarii?
As an additional question - what defines a senator to be a pedarii? Were they not permitted to speak, or simply had no chance?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4gstxq/did_the_roman_senate_actually_have_300_and_up_to/
|
{
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"text": [
"I can help you out at least on the number of senators. After the reforms of Sulla in 81 B.C., holding the office of Quaestor was the requirement to get into senate. The Censores were the officials in charge of revising the senate rolls ~~and did so every year (in the earlier roman republic this happened less frequently, but let's just stay with the late republic)~~ Edit: actually not, during the 1st century B.C. it was more complicated than that, take a look down at u/XenophonTheAthenian , adding the new Quaestores to the senate. \n\nNow, after Sulla's reforms, there were 20 Quaestores elected each year, so we could assume that makes 20 new Senatores. Basically, membership was lifelong if you weren't kicked out (e.g. through a Nota Censoria as punishment for bad behaviour). The minimum age for Quaestorship was ~~30/32 years for Patricii/Plebeii~~ Edit: More likely it was 30 years irrespective of class. If we assume 35 as the average entry age and that an upper class roman could expect to live at least to the age of 50, that makes 20 times 15 Senatores in senate as an expected value of members. Just with this rough estimate you can see that there needed to be at least 300 senatores (more like an lower bound) in the late republic senate, in actuality it was more like 600 under Sulla! It was also possible to get into senate just by being deemed fit for the job by the responsible officials, so while in power Sulla and Caesar artificially inflated the senate with their supporters, raising the number even more.\n\nOn questions 1 and 2: This is because not all Senatores were always present at every debate. Many of them were serving officials that worked in the provinces, far away from the capital, or just didn't attend because of private reasons. This also explains why a relatively small building was enough on most occasions to house the assembled senate. \n\nQuestion 3: Well, as i already mentioned, it wasn't like every senator was present all the time. Also, while technically speaking all senators had the right to speak, this was not practical. There was a large group of Senatores, the Pedarii, who didn't speak. This group consisted of low-rank Senatores, most likely plebeian conscripts or junior officials like quaestores or tribunes.. According to Kunkel's and Wittman's \"Staatsordnung und Staatspraxis der römischen Republik\" it is unclear wheter there was an actual legal distinction between regular Senatores and Pedarii, or if it was only a matter of pragmatism, but we know for sure that they did not speak in senate and only participated in senate votes (which is where their name comes from). We don't know much about their rights, how the group was consisted. It could be either: They were legally/by custom prohibited from speaking or they just had no chance because of limited time and their limited influence.\n\nIf you're looking for reading material on the subject, you can find some great online sources at Google Books, i just stumbled upon \"Rank and Participation in the Republican Senate\" by Francis Ryan, which seems perfectly on point for your questions (i personally only use german sources, i don't think they'd help you?)"
]
}
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[
[]
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dfoe3o
|
When coffee was beginning to catch on in Europe in the seventeenth century, was it used as a “working drink” (as today) or just a recreational one? Would a Dutch merchant have done his paperwork with a cup of coffee on his desk?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/dfoe3o/when_coffee_was_beginning_to_catch_on_in_europe/
|
{
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30
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"text": [
"You might want to cross-post this to /r/askfoodhistorians.",
"I cant speak for all of Europe but Prussia in the 18th Century under Frederick II it was banned. [From All About Coffee\nBy William Harrison Ukers](_URL_0_). The ban wasn't ultimately effective but it lead to a great quote in the same vein as the \"kids these days\" type rants only from an 18th century King. \n\n > \"It is disgusting to notice the increase in the quantity of coffee used by my subjects, and the amount of money that goes out of the country in consequence. Everybody is using coffee. If possible, this must be prevented. My people must drink beer. His Majesty was brought up on beer, and so were his ancestors, and his officers. Many battles have been fought and won by soldiers nourished on beer; and the King does not believe that coffee-drinking soldiers can be depended upon to endure hardship or to beat his enemies in case of the occurrence of another war.\"\n\nSo with that information it certainly seems like it was not seen as a working drink. There's another article that mentions this in the context of alcohol in history, but I cant find it presently. Arguably it was popular, but its imported status helped drive some of the movement against it. I don't want to get so speculative this response gets deleted. So what I'd say is that from how that article outlines coffee in 18th century Prussia, it seems likely that a wealthy merchant might drink it, but since it was a status symbol and drank in coffee houses they probably wouldn't have drank it on the job, as it was expensive to brew with how the laws were structured to keep it \"upper class\".\n\nEdit: I realize that while trying to properly source my claims about 18th century Prussia... there’s another chapter about coffee in Holland that would help give you some insight from that book."
]
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|
[] |
[] |
[
[],
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"https://books.google.com/books?id=4O_RAAAAMAAJ&pg=PA46&dq=Frederick+the+Great+of+Prussia+coffee&hl=en&sa=X&ved=0ahUKEwi7r8qboNTeAhUn7IMKHTJdAjUQ6AEIKjAA#v=onepage&q=Frederick%20the%20Great%20of%20Prussia%20coffee&f=false"
]
] |
||
9g4f3j
|
BPA is widely accepted as being toxic. However, bottles and other storage containers aren't truly made of BPA; they're made of a polymer derived from BPA. It is my understanding that polymers lose most of the characteristics of their monomer, so what is the concern with BPA plastic?
|
askscience
|
https://www.reddit.com/r/askscience/comments/9g4f3j/bpa_is_widely_accepted_as_being_toxic_however/
|
{
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"e62m42v"
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15
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"text": [
"It’s the residuals people are worried about. Since no reaction proceeds to 100% conversion, there will always be a little bit of monomer leftover. Also, since no washing step is 100% efficient either, there will never be a way to completely remove all the monomer. All of thst being said, the residuals are insanely low, and so it turns into more of a judgement call, depending on the toxicity of the monomer. "
]
}
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[] |
[
[]
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||
2tx693
|
why the quality of anime blu-rays is so bad?
|
It's like they intentionally add very big amount of noise to every static scene (or encode in multiply threads).
I've never thought that I will see this in almost every BDMV.
What am I missing here?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2tx693/eli5_why_the_quality_of_anime_blurays_is_so_bad/
|
{
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"co34d9q"
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3
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"text": [
"It depends on a few factors. If it's an older show, they might only have shitty copies to work with. If it's a new show, it could just be low quality shovelware and they don't care about quality control. \n\nOr they could intentionally be putting out a bad copy so that people in Japan don't import it themselves. Prices for media in Japan are traditionally insanely high, to the point where it's often cheaper to actually buy a foreign copy of a product and pay to have it shipped back to Japan than it is to actually buy a Japanese copy. Sending out terrible versions for exports is one way that Japanese companies fight the recursive imports."
]
}
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[] |
[
[]
] |
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x7c22
|
will screen resolutions get higher and higher?
|
I look at pics from 5 years ago and they almost look like thumbnails.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/x7c22/will_screen_resolutions_get_higher_and_higher/
|
{
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"text": [
"The sizes are stagnating because they've outpaced content. I've got a 1080p television, and there are still no broadcasts in 1080p - I'm limited to bluray if I want full resolution content. 1440p screens are growing in popularity among pc enthusiasts, but there's no television or movies that are readily available in 1440p, so you're just interpolating 1080p content. As LCDs have taken over both the TV and PC monitor markets, more and more computer monitors are becoming 1080p to be able to use the same manufacturing process as TVs. Half a decade ago, resolution varied drastically with size. 15\" was 1024x768, 19\" was 1280x1024, 20+\" was 1600x1200, plus 1366x768 and 1680x1050 widescreen. Now, everything from a 20\" to a 28\" pc monitor is 1920x1080, with only expensive high end stuff offering a higher resolution. Televisions are the same - a 92\" has the same resolution as a 20\".",
"Resolutions will continue to increase, however there is somewhat of a hard limit for practicality as there is only so much resolution that our eyes can perceive.\n\nTo illustrate this, if you walk up to a brand new TV and hold your face a few inches from it, you can certainly see pixels, even if it's a blu-ray playing. However if you walk to the other side of best buy and look at it, you can't see pixels anymore, in fact you couldn't tell the difference between blu-ray and DVD if you're that far away.\n\nAccording to [this article](_URL_0_) the iPhone 4 can display at a resolution higher than the eye can detect at a distance of beyond 18 inches. Most people hold their phone closer to their eyes than that however, so it's not a true \"retina\" display in normal usage.\n\nTo put the iPhone resolution in perspective, it has a 960x640 resolution on a screen that's 3.5inches diagonal. If you expand that to a 21 inch diagonal display with the same 3:2 ration that would be a resolution of 5760x3840\n\nA current Blu-Ray playback on a 50\" TV is \"perfect\" once you're beyond a distance of 8+ feet. That means that if you sit more than 8 feet away from your TV, then resolutions will never look better than they do now.\n"
]
}
|
[] |
[] |
[
[],
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"http://www.pcworld.com/article/198402/does_the_iphone_4_really_have_a_retina_display_updated.html"
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|
mj3mw
|
Does the ability to learn reduce with age ? Is this a myth or is it an actual fact ?
|
Personally, I have always found that my ability to learn has always proportionate to how motivated I am. But I am not really old enough to make any statement. I would like to hear about this topic from reddit.
|
askscience
|
http://www.reddit.com/r/askscience/comments/mj3mw/does_the_ability_to_learn_reduce_with_age_is_this/
|
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5,
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5,
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"text": [
"To some degree this isn't a myth. During childhood, the capacity for our brains to do the reorganization required for learning (also called neural plasticity) is greater than during adulthood. This is partially due to the fact that when strong connections are formed, the weak connections are pruned away. After this, it becomes difficult for new neural connections to \"outcompete\" the established ones. This is a good thing though (you don't want to unlearn how to see.) Nevertheless, the neurotransmitters associated with motivation (fear of death or injury for example) can powerfully alter our ability to learn (sometimes detrimentally, as in post-traumatic stress disorder.) Believe it or not, taking a painfully cold shower after practicing a piano sequence will enhance your ability to remember it the following day.",
"[this was asked a little while ago](_URL_0_), check the comments for some links to additional info. hope this helps clarify your thoughts! ",
"I just went to TEDxRainier (in Seattle) and saw Dr. Dimitri Christakis' talk on infant brain development. It was eye-opening and totally fascinating.\n\nBasically, 85% of brain development happens between birth and the first year of school. So there is some room in there up until you are about 24. Then it is downhill from there, brain-development wise.\n\nHere is his info: [_URL_1_](_URL_1_)\n\nAnd his talk will be up on the [TEDxRainier](_URL_0_) web site the first week of December. It would be well worth your time to watch it. One of the finest presentations at this year's event.",
"To some degree this isn't a myth. During childhood, the capacity for our brains to do the reorganization required for learning (also called neural plasticity) is greater than during adulthood. This is partially due to the fact that when strong connections are formed, the weak connections are pruned away. After this, it becomes difficult for new neural connections to \"outcompete\" the established ones. This is a good thing though (you don't want to unlearn how to see.) Nevertheless, the neurotransmitters associated with motivation (fear of death or injury for example) can powerfully alter our ability to learn (sometimes detrimentally, as in post-traumatic stress disorder.) Believe it or not, taking a painfully cold shower after practicing a piano sequence will enhance your ability to remember it the following day.",
"[this was asked a little while ago](_URL_0_), check the comments for some links to additional info. hope this helps clarify your thoughts! ",
"I just went to TEDxRainier (in Seattle) and saw Dr. Dimitri Christakis' talk on infant brain development. It was eye-opening and totally fascinating.\n\nBasically, 85% of brain development happens between birth and the first year of school. So there is some room in there up until you are about 24. Then it is downhill from there, brain-development wise.\n\nHere is his info: [_URL_1_](_URL_1_)\n\nAnd his talk will be up on the [TEDxRainier](_URL_0_) web site the first week of December. It would be well worth your time to watch it. One of the finest presentations at this year's event."
]
}
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[],
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"http://www.reddit.com/r/askscience/comments/fk21t/does_our_ability_to_learn_and_retain_information/"
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"http://www.tedxrainier.com",
"http://www.seattlechildrens.org/medical-staff/dimitri-a-christakis/"
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"http://www.reddit.com/r/askscience/comments/fk21t/does_our_ability_to_learn_and_retain_information/"
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"http://www.tedxrainier.com",
"http://www.seattlechildrens.org/medical-staff/dimitri-a-christakis/"
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|
33s9k0
|
why is there such distaste for millennials in the business world, and why are many afraid of the future they will create?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/33s9k0/eli5why_is_there_such_distaste_for_millennials_in/
|
{
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"cqnx51l",
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5,
2
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"text": [
"Old people like to think their better its not a new idea its been happening since Aristotle ",
"Ugh. Hippies. I'll never humor a criticism from that generation. Whatever they say is invalid.\n\nI got hired to this job. The guy insisted there was too much for one person and he needed a second designer. Problem is, I put out twice as much work as he did. So this guy 3 years from retirement got laid off, replaced by a \"kid\" almost half his age. I'd hate me too. \n\nBuy seriously, I don't dislike the 18 year olds today, but I don't have much patience for them either. So I may lose my tolerance with the kids being born right now, 30 years from now."
]
}
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[] |
[] |
[
[],
[]
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||
157b4e
|
when the optician dilates your eyes and your pupils get enormous, why don't well-lit areas become unbearable blinding?
|
If pupils adjust their size to the light level, and dilation makes your pupils huge, wouldn't everything be too light to see?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/157b4e/when_the_optician_dilates_your_eyes_and_your/
|
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"text": [
"It does become pretty unbearable.\n\nWearing sunglasses is a must if you're driving during the day time."
]
}
|
[] |
[] |
[
[]
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5h87qv
|
how do multiple elevator systems work? why is one elevator always still while people are waiting?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5h87qv/eli5_how_do_multiple_elevator_systems_work_why_is/
|
{
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"text": [
"Elevators have become much more complex with new ideas and technology. At first they were single shafts, single boxes, with living elevator operators. Then automation came in. Elevator operators persisted for a while. \n\nNow there can be multiple cars in one elevator shaft. This works when one company rents several adjacent floors. A lot of traffic becomes local during the day. Using one shaft for several cars reduces the total footprint of the elevator shafts in the building. \n\nLoading and unloading always takes a certain amount of time. At peak times people always have to wait."
]
}
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[
[]
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1yxiet
|
Does placement on the periodic table have any influence how radioactive certain materials are?
|
Also it would be helpful if someone explained why some materials are radioactive+how radiation effects the body
|
askscience
|
http://www.reddit.com/r/askscience/comments/1yxiet/does_placement_on_the_periodic_table_have_any/
|
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"The placement of elements on the periodic table doesn't influence their radioactivity, in the sense that the periodic table is a human invention that is essentially arbitrary, though it was designed to follow certain rules that make predicting elemental properties easier.\n\nHowever, since the periodic table that is in universal use arranges atoms by their atomic number (proton count), the placement of elements on the periodic table is certainly *related* to radioactivity, in the sense that \"heavier\" elements are more likely to be radioactive. Heavier in this sense means both that elements with *more protons* are more likely to be radioactive and *also* that *atoms of any particular element with more neutrons* are also more likely to be radioactive.\n\nThe cause of radioactivity is essentially that there is *too much stuff* jammed into the nucleus of the atom -- so much so that it's energetically favorable for the nucleus to shoot *stuff* out. That stuff might be \"energy\" - in, for example, excited nuclear isomers - or it might be \"mass\". I put those terms in quotes because when we're talking about nuclear physics, mass-energy conversions happen pretty frequently, so the usefulness of distinguishing between them is not as high as it is in our everyday life. For non-radioactive substances, the nucleus is already in such a low-energy state that it will release no energy if its configuration changes, so such a change doesn't happen. For radioactive substances, the nucleus is in a higher-energy state - like a ball on top of a mountain - so perturbations (which may be caused *spontaneously* by quantum vacuum fluctuations) will cause the nucleus to change configuration. That might be by actually shooting out part of the nucleus (alpha and beta decay) or by emission of a photon (gamma decay). That's about as low-level an explanation you can get without really diving into the math.\n\nRadioactivity's effects on the body are pretty complicated. As I mentioned earlier, there are three major types of radioactive emissions that people usually talk about (although there are definitely others, like neutron emission, that are quite important for nuclear reactions, but not so much for radioactivity's effects on people) - alpha particles, beta particles, and gamma rays. Alpha particles and beta particles are both \"particles\" - i.e. they have rest mass. Alpha particles are helium nuclei (they have 2 protons and 2 electrons) and beta particles are electrons or positrons (electrons with a positive charge). Gamma rays are high-energy photons. Alpha and beta particles are both pretty easily absorbed because they're \"big\" and interact strongly with matter. Alpha particles are *really* big, so they get stopped by matter almost immediately - within a few centimeters of air, or by essentially any solid, like the skin. Beta particles don't interact as much, so it takes a little more to stop them, like a sheet of aluminum foil. Gamma rays interact even less, so they shoot through stuff very easily, and it takes meters upon meters of shielding to stop them. The fact that gamma rays shoot through stuff so easily is what makes them typically more dangerous than alpha and beta particles, because you can be bombarded by them even though you're far away from the source. If you swallow or inhale something that emits alpha or beta particles, though, it's worse than if you had swallowed something that emitted an equal amount of gamma radiation, because alpha and beta particles do more damage than gamma rays do.\n\nThe damage done by radioactivity is basically due to the fact that they slam into electrons with enough force to make them shoot off into space, turning neutral atoms into ions (and oftentimes the electrons that shoot off can do the *same thing*). This can cause all sorts of bad stuff to go down in biological systems. It can directly damage your DNA, or cause other reactions that cause cell damage or death. It's really too complicated to go into a whole lot of detail here, but the main effects of radiation damage are usually the death of fast-replicating cells, like the inside of your gut and your bone marrow. People with radiation sickness experience nausea, diarrhea and anemia because of these effects.\n\n"
]
}
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[
[]
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1o7ylm
|
Can electrons touch?
|
Electrons are point-particles that repel each other. They cannot occupy the same space, but can they touch surfaces? Do they even have surfaces?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1o7ylm/can_electrons_touch/
|
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"To answer this you first have to decide what you mean by \"touch\". What you normally think of as touch is in fact due to repulsive force between electrons, particularly [Pauli Repulsion](_URL_0_). In that sense, electrons are the *only* things that normally \"touch\" in our everyday experience, and what touch means in that case is something like \"getting close enough to another electron for the repulsive forces to rise to levels that cannot be overcome.\"\n\nBut none of this should be taken to mean that electrons are little balls that have surfaces that touch in the sense you normally think of as touching. They experience forces that cause them to appear to behave a bit like that, but that's only a part of the picture.\n",
"Our current theory is that they are point-particles, which means they don't have surfaces. So in that sense, no. \n\n\"Touching\" is difficult to define however. When I touch my keyboard to type this, my fingers are separated from the keys by a distance, it is the electrical repulsion of the keys and my fingers that I feel and what depresses the key. At the microscopic level nothing really touches. Things are separated by a tiny distance due to electrical forces.\n\nAt an even deeper level, subatomic particles don't even have well defined positions. It is difficult to define a concept of \"touching\" for constructs which don't have position in the way we think of it in the classical world."
]
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|
[] |
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[
[
"http://www.eng.fsu.edu/~dommelen/quantum/style_a/pr.html"
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|
8jtylj
|
what makes some game consoles easier to emulate than others?
|
Zelda Breath of the wild can be played on the PC using CEMU, and has been for some time now. It was emulated far quicker than any Xbox or Playstation game. Why?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8jtylj/eli5_what_makes_some_game_consoles_easier_to/
|
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"text": [
"Usually the cause is the hardware used in the console. \n\nNewer consoles use the so called X86 Architecture for their CPUs, that's also the one used in your Computer, so those are often easier to emulate.\n\nThe PS3 for example used a Cell processor if I remember correctly, so giving PS3 CPU instructions to a X86 CPU will most likely not work, so you first have to create a program capable of helping the X86 understand what it has to do. \n\nOn top of that there is a big chance that hardware tricks are used on the PS3 to make it go faster, which might be even more taxing for a X86.",
"BOTW uses the Wii U’s version, right? I’m not sure how easy it would be to emulate the ARM instructions of the switch. It comes down to hardware mostly. Not too long ago, we just started getting enough power in most computers to accurately emulate SNES. Accuracy takes a massive amount of processing power. Emulators that don’t take that seriously have an easier time, because they can use hacks for performance. The issue with that comes when a programmer ties code to an aspect of the hardware that doesn’t get accurately emulated. This can cause a game to not work for those particular edge cases. \n\nIn an instance where the hardware is the same (XBone, PS4), it’s much easier to emulate or port games between platforms."
]
}
|
[] |
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[],
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1l8bhi
|
If you dropped an ignited match on a planet with an atmosphere of 100% hydrogen, would it burn the entire planet's atmosphere off?
|
I'm not sure how to explain my question more, but if you need more details for my hypothetical, please let me know.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1l8bhi/if_you_dropped_an_ignited_match_on_a_planet_with/
|
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"No: in order to burn, the hydrogen needs an oxidizer to react with (most commonly, oxygen gas, but there are other substances that can act as oxidizers). A pure 100% hydrogen atmosphere would have nothing to react with. You'd need oxygen or a chemically suitable oxidizer in the atmosphere to burn the hydrogen off (but if you did, then yes: it could burn the atmosphere).",
"Just so you know, the reason behind all of this is that when hydrogen \"burns\" it combines with oxygen to form water, or H20. So, for every oxygen atom you will consume 2 hydrogen atoms. This could theoretically propagate indefinitely and very quickly, but not instantaneously.\n\nEDIT: I apologize, I didn't see Baloroth's comment."
]
}
|
[] |
[] |
[
[],
[]
] |
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6ul708
|
If light is constantly speeding towards us from the edge of the observable universe, have any new galaxies or stars popped "into existence"?
|
askscience
|
https://www.reddit.com/r/askscience/comments/6ul708/if_light_is_constantly_speeding_towards_us_from/
|
{
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"text": [
"Any light we receive right now from the particle horizon would have been emitted shortly after the big bang (about 380,000 years or so). So galaxies were not yet formed. But, in principle, if we wait long enough, we would see galaxies slowly form and \"pop into existence\". (This is assuming the galaxy was close enough for the last receivable signal to be after the galaxy was actually formed.)",
"Generally no. Galaxies at the far end of the visible range are slowly vanishing due to the accelerating expansion of space. In the far future, that could turn around and we would see more and more things cross the horizon until literally everything is right on top of everything else and we merge back into a Big Crunch."
]
}
|
[] |
[] |
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[],
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||
6whulu
|
why are some mobile games not also available on pc (or any platform)?
|
And I'm not talking about those games that require touch screen specific mechanics or cams.
There are a lot of apps that are all just point and click. Which is what the mouse is built for. Yet the developers aren't inclined to sell those or make their free apps available on PC, which is practically a big market like mobile's.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6whulu/eli5why_are_some_mobile_games_not_also_available/
|
{
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"Mobile games are build for mobile hardware and operating systems. While to a user many of these will work similarly to PCs and consoles, to someone developing software for the platform, they are very different. If someone wants to alter a mobile game so it'll work on PC hardware with windows OS, that'll be a lot of extra time, effort, and consequently money spent to get done, and a lot of people come to the conclusion that it's not worth it, or that they won't make the money back by selling on other platforms."
]
}
|
[] |
[] |
[
[]
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1d7sqf
|
The French helped the Americans in their revolution, but did the Americans help the French in their revolution?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1d7sqf/the_french_helped_the_americans_in_their/
|
{
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"text": [
"The United States issued [The Proclamation of Neutrality 1793](_URL_4_) in response to the wars fought by Revolutionary France. The Genet affair, named after Citizen Genet, occurred in 1793 when Genet, an ambassador from France, attempted to drum up support for the French by touring America while hiring up American privateers to capture British ships (violating the Neutrality agreement).\n\nAfter several strongly worded letters that did very little to stop Genet, the Jacobins requested his arrest and extradition to France, where he would be killed. Despite his earlier actions, the United States granted him asylum and he lived another fifty or so years.\n\nIn addition, the [Jay Treaty](_URL_1_) (or whatever you want to call it) was quite a blow to France, as it essentially nullified the chance of the United States indirectly assisting their war against the British by striking one up themselves. \n\nFinally, the [XYZ Affair](_URL_0_) essentially killed US-French relations. The simplest version of events is that John Adams sent diplomats who were then told that they needed to, essentially, bribe their way into formal relations with France. While this wasn't particularly heinous by itself in Europe, the Americans were of a different culture and were incredibly offended, and left France.\n\nThis was followed by an undeclared naval war with France that left dozens of Americans dead or wounded and hundreds, if not a couple thousand, ships captured by the French. The [Alien and Sedition Acts](_URL_3_) were passed, and tensions rose, up until 1800.\n\n1800 saw a [treaty](_URL_2_) signed between France and the United States wherein both parties would drop all previous agreements and grievances, guarantee economic favoritism, and essentially keep the United States neutral as to keep their relations good with both Britain and France.\n\nI suppose to answer your question, no, the Americans did not assist the French in their revolution. However, the end result was a positive one, and the troubles during this time helped to cement future positive relations with France."
]
}
|
[] |
[] |
[
[
"http://history.state.gov/milestones/1784-1800/XYZ",
"http://www.loc.gov/rr/program/bib/ourdocs/jay.html",
"http://avalon.law.yale.edu/19th_century/fr1800.asp",
"http://www.loc.gov/rr/program/bib/ourdocs/Alien.html",
"http://avalon.law.yale.edu/18th_century/neutra93.asp"
]
] |
||
1ujru7
|
what would the world look like if we went with dc over ac current?
|
What would be the biggest differences, how would our technology look, and how would society be different if we use DC current as our primary current?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ujru7/eli5_what_would_the_world_look_like_if_we_went/
|
{
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"Dim, with lots of noisy machines everywhere. DC power is hard to transmit over distance, so you would need more power lines, more substations, more power plants, and the amount of energy reaching homes wouldn't be as great, so popular items would be a lot more energy efficient, but older items would be far less effective (lower wattage lightbulbs, 2 burner stoves, etc) You wouldn't need bricks for your electronics though. ",
"We haven't really chosen DC or AC, we chose to use the ones that make the most sense in the context it's begin deployed. Loads of things use DC. "
]
}
|
[] |
[] |
[
[],
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ep1hks
|
why is 2% inflation rate good, and what would happen if the rate falls below this?
|
Would people notice sudden changes in daily life?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/ep1hks/eli5_why_is_2_inflation_rate_good_and_what_would/
|
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"Inflation means that a dollar gets less valuable over time (by 2% a year). Too much inflation, and money becomes worthless, like in Weimar Germany. The too-little problem is a bit trickier. \n\nInflation encourages people and corporations (and especially banks) to do things with their money, specifically, invest it in businesses, education, or something else. If money loses 2% of its value each year, companies have to be doing something with it that earns at least a 2% profit - like lending it out.\n\nBasically, inflation forces banks and billionaires to stop just sitting on money and instead reinvest it, creating new businesses and jobs and driving the economy forwards.",
"You won't see any immediate changes in your daily life.\n\nThe biggest problem with very low inflation/deflation is that monetary policy becomes less effective/powerless, and the result may be a long economic slump.",
"*TL;DR*\n*Inflation is bad for people who cannot fight for better wages. If you are paid $500/week and the cost of everything increases by 5%, unless you can fight for more pay, you lose.*\n\n*Inflation is good for people who are in debt (as my debt is worth less than it was before) and small businesses (I can get away with charging more and not increase my staff's wages)*\n\n\nI think the best way to answer this is to explain the impacts of inflation.\n\nInflation is good for some and bad for others. \n\nGenerally, high inflation is good for those on strong wages and bad for those on weak wages.\n\nHigh inflation is good for those in debt, but bad for lenders (unless the interest rate climbs) or people with savings earning interest.\n\nAnd vice versa.\n\nExample 1.\nI lend you $500 for 1 year and get 5% interest.\nIf the inflation rate was high (5%), when you pay me back I have effectively made no profit.\n\nI made $50 in interest, but it is still only worth what $500 was a year ago.\n\nThis is great for the borrower who found it easy to pay me back though as their wage increased.\n\n\nExample 2:\nAn elderly couple retires with a fixed income of $500 per week.\nrent = $300\nFood = $150\nSave = $50\n\nBut costs inflate 10% over 2 years.\n\nNow,\nThey still make $500 per week\nRent = $330\nFood = $165\nSave = $5\n\nSo now, the couple does not have the money to cover incidentals.",
"Inflation promotes spending in turn generating more tax for the government, stimulating grown in the economy. \n\nIf there was deflation people would horde their money knowing they can buy more with it later on, leading to less spending, less taxes, and ultimately a recession etc...",
"Inflation isn't necessarily good, but deflation is extremely bad. As others have stated, inflation causes currency to lose value over time. The quicker the currency is losing the value, the quicker people want to get out and spend it. So inflation encourages participation in the economy and the churn of money that keeps everything moving. Deflation causes currency to gain in value, which sounds great, but it encourages people to save all their money instead of spending it. As people disengage from the economy, things start to slow down. Manufacturers start seeing that people aren't buying their goods as much, so they start making fewer goods. Now that they don't need as many goods produced, they start laying off workers. As people see their neighbors losing their jobs, they get nervous and start spending even less to hedge the risk of future unemployment. And the cycle keeps repeating in a self-reinforcing manner. \n\nHigh inflation can have terrible effects too, as seen in Weimar Germany, Zimbabwe, or Venezuela, but it's generally much easier to slow down people's rate of purchasing things than it is to convince people to start spending again once they've stopped. So overall it's much better to accept having a little inflation than to risk having any deflation. 2% inflation is the commonly accepted safe buffer to shoot for.",
"A low inflation rate or even deflation is not good long term. Short term it would be great for the everyday worker but the problem is the longer term effects will severely hurt everyone.\n\nFrom a personal finances level, consider this. Inflation means that $1 today will be worth $0.98 tomorrow. If the money you hold loses value, you are encouraged to do something with it. Be it investing or going out and buying that new phone. Now imagine this applied to companies. If their cash loses value, they want to use it rather than sit on it. This means they go out and buy something that someone else needs to make. This means more jobs for the economy as a whole.\n\nDeflation means that if you hold onto $1 today, it will be worth $1.02 tomorrow. What are you more likely to do then? Hold onto it because it gains value over time. Great! Now imagine a company seeing this. Rather than going out to buy that new hardware made by someone else, they decide to just sit on the money. Why turn down free money? What does this mean for the makers of that hardware? It means less customers for them which means they might need to fire people to keep afloat because they don't get as much business. Now apply this across the entire economy. Now you might be out of a job.\n\nNow this is all theory, but we see real world examples of this. The Japanese economy has faced deflation since the early 90's and has resulted in a very poorly performing economy. It's actually known as the lost decade, which is now known as the lost score because it went on well into the 2010's. During this time the GDP dropped and adjusted wages fell something like 5% and unemployment rates were way up. If I remember right, prior the unemployment rate was at around 2%. At the peak of the 20 years, unemployment was as high as 5.5% and the lowest was around 3.5%. At this point your economy is in a deflationary cycle which is really hard to pull out of. The Japanese government had to take some drastic measures to try and pull out of it.\n\nKeep in mind that all these effects take time to show, especially in daily life. Things will be great short term but when the hammer falls, everyone suffers.",
"There was a podcast that explained that 2% was a fairly arbitrary number somewhat based on what NewZealand used to get their inflation under control.",
"There was a great episode of the Planet Money podcast about the 2% inflation rate figure. It's been a while since I listened to it, but basically the 2% figure was arrived at in a pretty arbitrary way--you could even say it was basically a group of guys pulling the number out of their collective asses. But ever since then, the 2% rate number has been widely recognized as being ideal, even though the methodology that was used to come up with it was hardly scientific. \n\nHere's the episode: \n\n[_URL_0_](_URL_0_)",
"I would like to add to the question. What happens when we eventually have things costing ridiculous amounts of money? In third world countries where there was too much inflation, you could buy an egg for like a billion of their dollars. What about in X years when the USD reaches annoyingly high levels of inflation? Already, we have seen pennies become totally worthless, what's next? Quarters? Then $1 bills?",
"VeniVediVelcro hit the nail on the head but just imagine the opposite scenario. \n\nLet's say there is a 2% deflation rate. Money is getting more and more valuable every year! That's great! Except now banks and corporations and anyone with a good chunk of change has incentive to do absolutely nothing with the money. They can just sit on it and they will make money actually.\n\nEconomies are like water. You want lots of fluidity and swishy swashy moving around. Not a stagnate still pool",
"Inflation is a feature, not a bug. Folks who complain about (reasonable) inflation misunderstand money. They think it is a store of value. It is not. It is a transactional medium. Those who wish that it functioned as a store of value are missing an important point: there is no perfect store of value. literally no one, no institution of any kind, can guarantee the persistent value of ANYTHING.",
"Let's start with fractional reserve banking. Banks originally acted like warehouses for gold (or w/e currency) that would charge you a fee to store your money, much like renting a storage room for your furniture. But, eventually bankers realized that with all that money just sitting there doing nothing, that they could lend that money out (in the form of bank notes) and gain profits from the interest. This practice is called fractional reserve banking, and if you've ever seen _It's a Wonderful Life_, it's the type of bank Jimmy Stewart runs. The problem with this style of banking is that it results in 3 things: a) there is now far less money in the bank than the total that customers believe they have access to, b) because of this, if there is any uncertainty with the bank, a \"run\" on the bank can occur where its customers try to withdraw more money than is available, and c) loaning out money that someone else believes they have in their account effectively creates new money, essentially creating new money. \n\n\nSo, fractional reserve banking carries with it the potential for large profits AND a significant amount of risk should any of the loans default or if too many people want their money back. This style of banking, which many would call fraudulent, experienced problems in the 1800s with many banks going completely out of business (there were some states with laws against having too many branches which would exacerbate this issue, but that's a side issue). So, the large banks got together with government in 1914 and created the Federal Reserve. What this did was establish a government monopoly on currency and essentially socialized the risk of fractional reserve banking. So, while the banks could keep lending out more and more claims to the same money, if anything bad happened, the tax payers could bail the banks out. They essentially privatized the profit of loans while socializing the risk. But, this scheme needed to be explained to voters, and that's where this idea of \"stable inflation\" came from. \n\n\nEconomists like John Maynard Keynes, in an effort to legitimize this practice, started spreading the idea that it was the job of central banks to try to keep prices stable. Before the existence of the central bank, prices _fell_ over time. This was actually a great thing, as the cost of living would fall over time, and poor and middle class people could save their money and its value would just naturally increase over time without having to invest it in a 401(k) or anything. But, special interest groups for businesses would complain about falling prices, and they spread the idea that falling prices made business unstable. \n\n\nWell, over time, the US started getting into world wars and funding ever larger social programs, and in order to pay for all this, they would print new money with their newfound monopoly. But, this would increase the money supply, and people started noticing that prices were now rising over time instead of falling. So, in order to quell this fear without losing their ability to print money to pay for their vote-garnering programs, the Federal Reserve redefined price stability to mean keeping inflation under 2%. Then, once Nixon cut the last ties to the gold standard in 1971, it was again redefined to mean at least 2%. The Consumer Price Index is the government statistic that they use to show the public that they are staying true their word, but it's heavily manipulated to make sure that it only includes goods that result in the final number being what they want. \n\n\nSo, let's look at what has happened with this inflationary economy that the world has been running on for over 100 years now. Poor people are unable to save money because their money is constantly losing value. Consumption has become more rewarding than saving, which has led to our consumerist culture. Big banks and Wall St. have become a black hole of wealth that all money flows toward, artificially increasing wealth inequality. The government has been able to fund endless wars despite the fact that anti-war candidates (at least in rhetoric) have become the last 3 presidents. We have enormous booms where people over-invest into long term projects because loans are too easy to come by, followed by massive busts when those long term projects collapse due to a lack of the actual resources to sustain those businesses. The government has gone out of its way to push banks to give out bad loans like subprime mortgages and student loans, saddling normal people with debt they'll never be able to repay. The bad news is that this scheme cannot last forever. A major crash is coming soon (almost certainly by the end of this year), and it may be the last one that this government can sustain. \n\n\nIf you would like to learn more, here is a short article on [Austrian Business Cycle Theory](_URL_0_), and the Mises Institute also has Murray Rothbard's [What Has Government Done to Our Money?](_URL_1_) available for free as PDF.\n\n\nEdit: And before someone comes in and tells me deflation is bad, it's not. If it were true that falling prices kept people from buying products, then no one would ever buy a big screen tv.",
"Inflation is an important part of good economy, it incentives everyone who has a lot of money, people, companies and corporations to invest alll their extra money into the economy again hoping to make money.\n\nThis prevents people from just sitting on their money and hoarding it, which is very bad for the economy if it happens.\n\nThe main question is as ever found between the two extremes, no inflation and hyperinflation. What is the correct inflation rate?\n\nWe cant have any sort of hyperinflation because then the rich just takes their money and move the fuck away. You cant have no inflation because while risk your money on the market if there is nothing in it for you. Should we guess that somewhere between 1-3%, its all we can do really."
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[],
[],
[],
[],
[],
[
"https://www.npr.org/sections/money/2018/11/30/672366380/episode-879-the-secret-target"
],
[],
[],
[],
[
"https://mises.org/library/austrian-business-cycle-theory-brief-explanation",
"https://mises.org/library/what-has-government-done-our-money"
],
[]
] |
|
2zkt3x
|
If attraction of physical objects, gravity, can be modeled as curvature of spacetime, can electromagnetic attraction and repulsion also be modeled as curvature of spacetime?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2zkt3x/if_attraction_of_physical_objects_gravity_can_be/
|
{
"a_id": [
"cpjtg6g",
"cpjuz0c",
"cpjwvzu"
],
"score": [
37,
15,
7
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"text": [
"**Short answer:** In general relativity, the curvature of space is gravity. You can also use a mathematical structure that's very similar to the curvature, which is a tensor, for electromagnetic fields. This tensor has many names but I prefer the name [Field Strength Tensor](_URL_0_). It's basically a matrix to describe how the electromagnetic fields look, with no info about curvature, and can be used very straight forwardly in special relativity. Since electromagnetic fields have energy, they contribute to the curvature, so in general relativity you might also consider the [Electromagnetic Stress Energy Tensor.](_URL_1_) For a fun example, even though photons are massless, they have energy, so they must contribute to the curvature of space. Believe it or not, if you get enough photons in one place, you'll have a high enough energy density to make a black hole, without even using a smidgen of matter.\n\n**Long answer:** Uh... see above. \n\n",
"Generally not, because what makes Gravity so easy to model as spacetime curvature is the fact that gravitational charge and inertial mass are exactly the same thing, so that all bodies, regardless of their mass, fall at the same rate. That is not true with EM.",
"(Warning: this answer is based upon a 12 year-old memory, and so could be total nonsense.) \n\nIn classical dynamics, any (holonomic) force of constraint can be reformulated as force-free motion occurring on some curved manifold. In other words, you could be a pedantic snit and insist that your roller coaster ride is really just a force free path on some curved space. \n\nFurthermore, I believe the Lorentz force law, so electric and magnetic forces, can be formulated as such, if you choose the correct gauge and canonical coordinates. (not sure though.) \n\nIf memory serves, In Einstein's later years, he attempted to attempted to integrate electrodynamics into a curved space-time model. \n\nHowever, the big problem that no one has yet solved, is how to get quantum field theory to play nice with this kind of formulation of gravity. \n\nNinja: [Here's a 5-dimensional geometric model that is EM + gravity.](_URL_0_)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Electromagnetic_tensor",
"http://en.wikipedia.org/wiki/Electromagnetic_stress%E2%80%93energy_tensor"
],
[],
[
"http://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory"
]
] |
||
56g0de
|
What was the motive behind the assassination of Huey Long?
|
I read the wikipedia article on the senator's assassination, and that of his assassin, Dr. Carl Weiss. Interestingly, besides the description of the assassination itself and the two men's funerals, no mention is made of the doctor's motive. What prompted him?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/56g0de/what_was_the_motive_behind_the_assassination_of/
|
{
"a_id": [
"d8j7ufy"
],
"score": [
15
],
"text": [
"Weiss' contemporaries noted his objection's to Long's politics, which he apparently was so wrought over that they brought him to tears. He viewed Long as a tyrant, and once claimed that he would kill him (Long inspired extreme rhetoric from all sides, and such threats were not uncommon).\n\nThat said, there isn't proof that it was an overly premeditated act. Weiss didn't leave behind a note or manifesto, spent the day of the assassination in relatively high spirits, and in fact told his wife he was going out on a house call the night of the assassination. Weiss kept a pistol in his car as a gun collector, and might've acted impulsively, since Long was in Baton Rouge irregularly as senator. An in-law believed that Weiss' broodings had made him mentally unstable to the point where he made a spur of the moment decision to become a \"martyr to liberty\".\n\nSome dubiously sourced accounts tie Weiss to a larger conspiracy targeting Long due to his opposition to white supremacy, but lack definitive proof. \n\nSource: T. Harry William's *Huey Long*"
]
}
|
[] |
[] |
[
[]
] |
|
29vbhy
|
edward snowden
|
I dont know why but ever since the start of this i have been totally out of the loop and it seems harder and harder to catch up as time goes by. Could someone give me a brief synopsis on the whole situation with him?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/29vbhy/eli5edward_snowden/
|
{
"a_id": [
"ciotx8m",
"ciouime",
"ciovs9c"
],
"score": [
2,
2,
2
],
"text": [
"dude worked for a govt contractor.....decided on day to leak a bunch of sensitive govt files.....fled the country.....eneded up in Russia when the united states revoked his passport, leaving him stranded.\n\nRussia doesnt seem like it can be bothered to help send him back, so in russia he stays.",
"It the press were doing their job it wouldn't have been \"necessary\" for Snowden to leak documents. ",
"A tragic tale of a man trapped on a desert island. One day his hosts/captors will tire of him and will sell / trade him back to the usa"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
30xz21
|
if it is widely known as a failure, why do we still have standardized testing for all students, including special needs students?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/30xz21/eli5_if_it_is_widely_known_as_a_failure_why_do_we/
|
{
"a_id": [
"cpwveld"
],
"score": [
6
],
"text": [
"Because there is a notion that we need to measure success, and America chooses to do so through standardized tests. While there has always been some form of measuring success, No Child Left Behind really instilled testing as a school/county/national indicator of that success. No Child Left Behind is the re-authorization of an existing legislation (Elementary and Secondary Education Act) that provides funding to low-income schools. Standardized testing became the link between measuring success and national funding- if you wanted to be funded nationally, your school/county/state had to perform as such. School are penalized if they don't meet their annual progress metrics, which is ridiculous. \nThere has always been testing, but Bush Jr effectively ensured that student learning and school funding was tied to it. This is BS, because lower performing schools are usually in lower income neighborhoods where parents aren't raising thousands of dollars to subsidize necessary funding. \n\nWe STILL have it, because that notion of measuring success is engrained in our politicians minds. Where tests were once given to determine how much students were learning, or what they needed help learning, they are now just a string of words that don't capture anything relative to the real world. We saw Obama further buy into this notion with his Race to the Top program- those who perform best get most funding.\n\nStandardized tests not only fail to capture student education, they completely take away from what is left. Teacher performance is tied to these tests, and because so much weighs on them, nothing else in schools really matter. \n\nJonathon Kozol wrote an amazing book that captures this and more, perfectly titled: The Shame of the Nation.\n"
]
}
|
[] |
[] |
[
[]
] |
||
2pdece
|
why is breathing harder when you think about it?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2pdece/eli5_why_is_breathing_harder_when_you_think_about/
|
{
"a_id": [
"cmvmp5x"
],
"score": [
6
],
"text": [
"The way that the mind works about breathing is that it runs on 2 different processes: Automatic and manual.\n\nAutomatic processes include things like heartbeat, breathing, blinking, and generally body processes that are needed for survival. These are things that you can literally do in your sleep.\n\nThe manual processes are things that you can control, but have to learn. This includes things like walking, grabbing things, knitting, and generally other things that you can't do while sleeping.\n\nNow, objects can be moved from automatic memory to manual memory and vice versa. An example with this is walking. When we're babies, we had to move one foot in front of the other and learn how to move each muscle correctly. Essentially we were all QWOP players when we were young. Then, we eventually learned the process of taking a step to where we can walk without manually thinking \"lift right foot. Set it down. Lift left foot. Set it down.\"\n\nBut, when it comes to controlling something that's usually automatic, it generally takes more effort to do, including mental effort. Breathing happens without paying attention, but if you pay attention, then you have to manually start doing it. It's kind of like the difference of using a hand to cut meat when you're used to using a knife. "
]
}
|
[] |
[] |
[
[]
] |
||
5l0nst
|
how does electricity running through a filament produce light?
|
If electric current is just the movement of electrons how does a filament produce photons (light)? Are electrons and photons related in some way?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5l0nst/eli5_how_does_electricity_running_through_a/
|
{
"a_id": [
"dbs1m2z",
"dbs1zn4"
],
"score": [
3,
9
],
"text": [
"The electric current is heating the filament until it glows. It is glowing just as heated metal glows or a candle glows. This is different from a cfl or led lamp. \n\nElectrons are electrons. But electrons can absorb photons and move to a higher valence orbital, or emit a photon and move to a lower valence orbital.",
"The resistance of a piece of metal depends on its thickness. The filament is extremely thin, so it has a much higher resistance than the other wires in the bulb. As the resistance increases, the heat generated by passing current through it increases. Just like a piece of steel in a fire glows red from the heat, the filament (made of a metal with a very high melting point) gets so hot it glows white.\n\nAll objects above absolute zero emit thermal radiation, but it's usually only infrared. At sufficiently high temperatures it will emit visible light. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
1sbnrq
|
Do people with autoimmune diseases or dangerous allergies get colds/flus less often?
|
Colloquially I often hear things like celiac disease or peanut allergies described as an "over active immune system." Is that a useful characterization? Are conditions like this correlated with any additional protection against common pathogens?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1sbnrq/do_people_with_autoimmune_diseases_or_dangerous/
|
{
"a_id": [
"cdw23i9",
"cdw755c"
],
"score": [
2,
4
],
"text": [
"EDIT: I realized I made this answer ridiculously long so I made a TLDR at the end.\n\nOveractive immune system is kind of a misnomer. It is true that people with celiac disease have symptoms due to their immune system, however it not because it is \"overactive\" but more so it is an inappropriate response of the immune system to something benign. \n\nIn the case of celiac disease, you're immune cells have decided that gluten and its derivatives are bad. So anytime you eat something containing gluten, you're immune system activates just as it would if it came into contact with a virus. \n\nThat is pretty much the basis of autoimmune diseases. They result from a loss of tolerance to either self-proteins within our cells, or outside proteins as in gluten or peanuts.\n\nHowever, outside of that specific \"bad\" protein, the immune system is not any more active than the rest of societies, so there should be no increased protection from infections. \n\nThe cells that are the culprits behind autoimmune diseases are called the lymphocytes. You're body produces millions of lymphocytes each with a different ability to \"surveillance\" for certain proteins or components called antigens. This is helpful because each bacteria and virus have different antigens, and can actually mutate to form new antigens, so it is imperative for our immune system to have millions of combinations to catch different antigens.\n\nUnfortunately, this also means there is a chance lymphocytes are made that can find normal proteins and turn on the alarm to start attacking them. Our bodies have many defenses against this, but people with certain genetics can be more susceptible to slips in the defenses which allow for autoimmunity.\n\nThere is however one instance I can think of where an immune disorder might possibly make one less susceptible to infections. It is called mastocytosis. This can actually be considered an \"overactive immune system\" as it is caused by your immune system making too much mast cells. Mast cells are an important part of prevention for worms and parasites. So in mastocytosis you are probably much less susceptible to infections from parasites. However, the symptoms of mastocytosis can mimic and even include worse symptoms than simple infections so its not really a helpful disease.\n\nTLDR:\n1. Autoimmune diseases aren't \"overactive immune systems\" but rather \"inappropriate responses of the immune system to benign proteins.\n2. They won't help prevent other infections, because autoimmunity usually only affects a specific subset of proteins with no bearing on viruses or bacteria.\n3. Mastocytosis is an immune disorder which may help prevent infections from parasites due to an abnormal growth of mast cells which fight against these types of infections.\n",
"I wouldn't say it is an \"overactive immune system\" as much as it is just a malfunctioning immune system. In autoimmunity your body makes antibodies to your own tissues, so your immune system is attacking yourself.\nA popular way to treat people with autoimmunity is by knocking their immune system down a bit actually, so people with immune system problems are actually more likely to get colds/flus in some cases. Getting a flu shot is super important for these people."
]
}
|
[] |
[] |
[
[],
[]
] |
|
4w3q1m
|
my account is blocked for 15 min after i type my password 3 times incorrectly. so how come hackers can break my password in few seconds/minutes?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4w3q1m/eli5my_account_is_blocked_for_15_min_after_i_type/
|
{
"a_id": [
"d63pnxh",
"d63qfay"
],
"score": [
5,
4
],
"text": [
"There's two primary ways this occurs.\n\nNormally, attackers aren't just entering things into the website's log-in form. Through a security flaw in the site, they manage to obtain the password database. The site should have stored only a one-way *hash* of the password, a mathematical transformation into a string of characters of a standard length.\n\n If you enter a password then what you entered can be hashed and compared to the password hash in the database, but the site doesn't know your real password. Having the database available, though, an attacker can generate and hash passwords up to millions of times per second (if the site didn't use a very strong algorithm) until they get the right one. Passwords that are simple will be broken more quickly this way.\n\nThe second trick comes from the fact that many people re-use passwords on other sites, and tend to sign up with the same e-mail address. Let's say that an attacker gets the password for some random forum you signed up for with the e-mail [email protected]. Losing your forum account doesn't seem like a big deal. But the attacker will then try using that e-mail and password combination on popular banking sites, and if you reused your password, now they've got access to your money! It may seem like a long shot, but in a large breach, there's always a bunch of users who get caught this way and it can make the whole exercise profitable. Note that in this scenario the bank's security was not broken at all.",
"There are a number of ways to hack somebody's account:\n\n- Brute forcing.\n- Dictionary attack.\n- Password reuse.\n- Man in the middle attack.\n- SQL injection.\n- Phishing.\n- Keylogging.\n\n**Brute forcing** is when you repeatedly attempt to log into somebody's account using a randomly generated or incremental password. This kind of attack is pretty slow since it has to try every possible combination. If you use a longer password, it will exponentially increase the amount of time it takes to successfully break into an account. It's also pretty easily stopped by adding a small 15 minute block that prevents logins after too many attempts.\n\nA **dictionary** attack is when you try to log into somebody's account using a password from a predefined list. There's no guarantee that the attack will be successful, but if it is, it's much faster than a brute force attack. To prevent a dictionary attack, all you need is a strong password that isn't on the hacker's list.\n\nA **man in the middle** attack is when somebody sits in the middle of the connection between you and the server. Whatever you send to the server goes through the middle man, who is saving your username and password. Using an end-to-end encrypted connection such as HTTPS significantly lowers the ability for a MITM attack to be done successfully.\n\nAnother way people get into your account is through **password reuse**. Let's say you created an account on Amazon. You then create an account on _URL_0_ with the same email and password, and a hacker obtains the database for _URL_0_. The account information wasn't secured particularly well, and the hacker quickly cracked the MD5-hashed passwords. They now have your email and password, which can be use d on other websites like Amazon. You can prevent this by using different passwords for each website.\n\nA more technical kind of hack is one using **SQL injection**. SQL injection is a security flaw resulting from user input that wasn't properly escaped before passing it to an SQL server. With SQL injection, a hacker could change your password to whatever they want. By changing your password, they have successfully gained access to your account *and* locked you out of it at the same time. There's really not much you can do to reduce or prevent this from happening to your account.\n\nAnother way to gain access to your account is by **phishing** for your login information. The hacker creates a fake login page and tricks you into providing your account information. When you enter or submit the account details, the fake website stores your username and password so the hacker can use it at a later date. The best way to prevent this from happening to you is to check the domain name of the website. If it's not the real domain for the website, don't put your account information in.\n\n**Keylogging** is another way to steal your account info. A keylogger is a type of virus that logs all your keystrokes and sends them to the hacker. If you just so happened to log into PayPal with a keylogger running, the keylogger would've sent your login information to the hacker. A good way to prevent keyloggers is to use an antivirus and avoid opening suspicious files.\n\n**Edit:** rewrote some sections for clarification and fixed typos."
]
}
|
[] |
[] |
[
[],
[
"example.com"
]
] |
|
428f14
|
What was the reason behind the mass Soviet deportations of the Chechens, Crimean Tatars and others along the southwest frontier? Did anti-Muslim sentiment play into it?
|
The mass deportation Chechens, Ingush, Crimean Tartars and Kalmyks are examples I know of. I know one justification was for (supposed) Nazi collaboration, but as far as I know the Chechens, for example, didn't have nearly the level of collaboration as found in Estonia or Ukraine, and yet they suffered far more extensive deportation.
The second part comes from my understanding that the predominately Muslim central Asian Turkic peoples tended to see the politicized atheism of the Soviets as being the same sort of anti-Islam as found in the politicized Christianity of the Russian Empire.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/428f14/what_was_the_reason_behind_the_mass_soviet/
|
{
"a_id": [
"cz8g5k7",
"cz8n43q"
],
"score": [
3,
7
],
"text": [
"/u/blindingpain might be able to shed some light on this topic.",
"The official reason was because of alleged Nazi collaboration, but as thousands of Chechens (and the others; I'll use Chechen here to mean all North Caucasus groups deported, but don't mean to imply anything aside from ease of typing) had served, and were still serving, in the Red Army, it was nonsensical. Granted there was some efforts by the Germans and local Chechen groups to work together, but that was not very successful.\n\nI would also say that their religious views were not a factor. Keep in mind that nearly all of the Central Asian peoples (Kazakhs, Uzbeks, Tajiks, etc.) and many other groups in Russia itself (the Tatars being the largest group) were, and still are, Muslim. While many Chechens practised a hybrid Sufi Islam and traditional Caucasus beliefs, not really the same as the other Muslim peoples in the Russian Empire/USSR. Still, like I said, I don't think that played a factor, or at least a large one.\n\nI would argue that the main reason stems back from the Russian Revolution and formation of the Soviet state, and even then one can trace it back to the first Russian attempts to pacify the North Caucasus in the early 1800s. The Chechens had always resisted Russian (and any power before them) control, and had actively spent decades fighting anyone who tried to establish themselves. This probably reached its peak under [Iman Shamil](_URL_0_), who managed to fight the Russians for decades before the Russians effectively won control in 1864. \n\nBut even then the Chechens were not willing members of the Empire, and so when the Revolutions of 1917 they broke free, nominally creating the Mountainous Peoples Republic of the North Caucasus (the name has been translated into a variety of ways, but that's the basic idea), which lasted for a few years. Once again the Russians (in the form of the Red Army) tried to come in and reassert control, which was costly and time-consuming. The Chechens proved one of the most difficult to pacify, even though the basic idea of Marxist-Leninism was quite compatible with their traditional way of life (in terms of property and the like).\n\nSo I feel that Stalin and Beria found an excuse to deal with a troublesome people that were not interested in being part of the USSR and had caused more trouble than they were worth. Keep in mind it was not the first time a Caucasus people had been ethnically cleansed: the Circassians were forcibly expelled (they refer to it as genocide; I won't get into that here) in 1864, while the Abkhaz were also largely removed in 1878. So there was a pretext on how the Russian authorities dealt with the unruly people of the Caucasus. That they could cite Nazi collaboration just helped produce a legitimate claim to the whole operation."
]
}
|
[] |
[] |
[
[],
[
"https://en.wikipedia.org/wiki/Imam_Shamil"
]
] |
|
1l2w44
|
Is there any credible evidence that Hitler escaped?
|
I'm currently staying with a friend of mine who insists that there's no evidence that Hitler actually died, and as this is *very far* outside of my own personal historical interest and knowledge, I felt this was the best place to ask.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1l2w44/is_there_any_credible_evidence_that_hitler_escaped/
|
{
"a_id": [
"cbv9ww1",
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],
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97,
6
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"text": [
"Alright I'm going to try and take a crack at this, because at one point I looked into this, and I've read the book that your friend has probably read.\n\nThe book that people like to reference when making these claims is 'Grey Wolf: The Escape of Adolf' by Simon Dunstan. The claims made by the book are as follows:\n\n* Hitler and Eva Braun did not kill themselves in the bunker.\n* When the allies closed in on the bunker, Hitler and Eva Braun fled, leaving a body double and an actress in their places.\n* Hitler made it to Argentina, and lived there until he died in 1962.\n* Hitler had two daughters.\n\nThere's probably a few other things claimed in the book, but those are the big ones. To even call the book 'junk history' would be an insult to junk history. A reddit comment saying 'no' has more historical merit.\n\nI'd love to break down what's wrong with most of the claims, but the problem is that even within the book itself, most of the claims are barely even explained. For example, there's no citations on fairly huge claims. What sources are provided are all second hand, and seem to have huge gaps and inaccuracies. For example, they've interviewed people who 'knew hitler' after his arrival in Argentina, but fail to provide any sort of evidence that what people said was true. There's nothing but people's claims, and no actual hard evidence.\n\nPerhaps the most alarming is the claim that Hitler supposedly had *two daughters*, a fact that was mentioned several times but not elaborated on. If Hitler really did live, why not locate his daughters? They would be the ultimate piece of evidence that their claims are true.\n\nTo get into some evidence that Hitler died, we've got several primary sources. One of the prominent ones (who wrote a book about it), is Rochus Misch, who was Hitler's radio operator. He saw the bodies of Hitler and Eva Braun shortly after their suicide, and ended up being the last survivor of the bunker. His book about it is some pretty interesting stuff.\n\nThere is a jaw fragment and a skull fragment, but their validity is in question. I've heard conflicting sources on why there's so little physical evidence. Some claim that the Germans didn't want the bodies to be put on display. Regardless, it's believed they burned the bodies, which were later discovered by the Russians. The Russians are believed to have kept them secret for quite a while, and then later unburied them, cremated them completely, and scattered the ashes in order to prevent there from being any sort of gravesite.\n\nIn summary, there's not the tiniest shred of evidence for the claims made, but there is a huge hole where evidence should be (particularly the two daughters). By comparison, there's not a *ton* of evidence for Hitler's death, but there's a lot of good reasons and explanations for that--the cold war, the German's burning the bodies, etc.\n\n**Some sources:**\n\nI read 'The Grey Wolf: The Escape of Adolf' and it was horrible. I wouldn't recommend it to anyone--don't give them your money.\n\nHere's an excellent interview by Rochus Misch, who is actually still alive today: [interview](_URL_0_)",
"To add, the Soviet Union gave out misleading information about Hitler's fate after they had taken Berlin. It seems one of their reasons was to discredit the West, so at one point they claimed that one of the Western allies was secretly harbouring an alive Hitler. I think this is why conspiracy theories persist about him surviving beyond 1945. \n\nHowever, there is more evidence (ie from those who were inside the bunker at the time) to suggest that suicide by gunshot was the most likely event that occurred, and therefore Hitler died in 1945. "
]
}
|
[] |
[] |
[
[
"http://news.bbc.co.uk/2/hi/europe/8233856.stm"
],
[]
] |
|
2hb9ms
|
Why didn't the Persians take advantage of the Peloponnesian war in order to invade Greece?
|
Why didn't the Persians take advantage of the Peloponnesian war in order to invade Greece?
I know that they financially supported Sparta. They favored the land-oriented Sparta, instead of a navy power like Athens, which could be a constant threat for Asia Minor.
But why didn't they invade directly Greece , AFTER the Peloponnesian war had ended where the Greek States were in a weak state?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2hb9ms/why_didnt_the_persians_take_advantage_of_the/
|
{
"a_id": [
"ckr9320"
],
"score": [
5
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"text": [
"Well, they did sort of. The Spartan deal with the Persians greatly favored the Persians. While the Spartans got money for a fleet (and not much else--the Persians didn't even tell the Spartans what they were supposed to do with their ships, even though the leading Spartan generals had no idea what they were doing) the Persians were granted control of all the cities of Asia Minor, from which they had been pushed at the end of the Persian Wars. The Greeks fully expected the Persians to try a third time, at the very least to secure Ionia and the other Greek cities of Asia Minor. It is extremely fortunate for the Greeks that Xerxes' death began a period of extreme upheaval in Persia, with multiple satrapies in revolt and lots of disputes over the throne. Xerxes' successor, Artaxerxes, attempted a series of massive ritual and administrative reforms, while also trying to squash insurrections like the one in Egypt, which was Athenian-led and caused a major problem. During much of the Peloponnesian War the Persians were busy with their own civil squabbles, as Darius II marched on the throne after his brother was assassinated and trying to keep the eastern satrapies in the fold. Most Persian actions were carried out by the satrap Tissaphernes more or less independently. Across the reigns of several Great Kings, Tissaphernes proved to be a master of diplomatic action, playing the Greeks off against each other and giving each side support in turn, but only enough to ensure that the struggle be prolonged, not that anyone would actually win. \n\nBut why didn't the Persians invade at the end of the war? First, Greece wasn't quite so weak as it may seem. Although order had been thoroughly disrupted and Greece was in shambles (the Peloponnese in particular was devastated, a result of ruthless Athenian raids on coastal towns and farmland), the Lacedaemonians were the sole hegemon in the Peloponnese and had tied their allies to the north, namely the Boeotians, to them with ever-increasing bonds of military assistance and tribute. For about a decade the Lacedaemonians were incredibly powerful, although after the Corinthian War, when pretty much everyone in Greece banded together to overthrow the Spartans (who had not only lied about their promises of liberation--see what they did to the Ionians--but were exacting tribute several times higher than what had been paid to the Athenians--on their own allies, not just their subjects--and also dared to install garrisons in many allied cities) Greece devolved into a state of near-anarchy. Persia was having its own trouble. The insurrection of Cyrus the Younger coincided exactly with the end of the Peloponnesian War, obviously preventing the Great King from doing anything in Europe. And the Ten Thousand, while not immediately damaging, were still extremely jarring, since they were able to march around pretty much at will. The Persians were also subject themselves to invasion from the Greeks, not vice versa, when Agesilaus landed in Asia Minor to liberate the Ionian cities (which, yes, they had handed over to the Persians--the Spartans weren't the best at keeping friends, especially after their victory over the Athenians). This invasion, while of doubtful success, was enough to really ruffle Persian feathers, and even resulted in the death of Tissaphernes, who, despite his invaluable assistance previously, paid for his failures during this campaign and his failure to annihilate the Ten Thousand with his head. \n\nSo Persia was really not in a position to mount a large land invasion of the Greek mainland, especially considering how immensely costly it would be. And things in Persia weren't much more organized than in Greece in the 4th Century. Artaxerxes III defeated his rivals in a bloodbath of assassination and civil war, and although he did manage to finally squash most of the rebellions (including the one in Egypt), by his death in 338 things weren't particularly stable. His minister Bagoas (who probably murdered him and murdered all his children and a whole bunch of people) killed his successor, Artaxerxes IV, all *his* children, a whole bunch of satraps, and pretty much anyone he could get his hands on until finally in need of a Great King (because, being a eunuch outside the royal family he couldn't do it) he finally settled on Darius III, Artaxerxes IV's rather lacklustre nephew, who ended up killing Bagoas. So yeah, lots and lots of civil unrest for the Persians. This doesn't mean that Persia didn't do *anything*. During much of this period the Great Kings were occupied with civil, Egyptian, or eastern concerns, and most diplomacy and campaigning in the west was left to the satraps, mostly Tissaphernes and Pharnabazus. The latter was instrumental, because while Tissaphernes was a good diplomat he lacked military oomph, and Pharnabazus convinced Artaxerxes to put his faith not in Persian armies, but in the fleet. In the aftermath of Agesilaus' invasion of Asia Minor, Pharnabazus, enlisting the support of Conon, an Athenian admiral who spent the rest of his life after the Peloponnesian War on a personal vendetta of revenge against Sparta, wiped the Spartan fleet off the face of the globe, and was able to reclaim not only Asia Minor, but most of the Aegean cities in one stroke, undoing all Agesilaus' saber-waving. "
]
}
|
[] |
[] |
[
[]
] |
|
1ya0r9
|
what do maxwell's equations tell us and why are there so important in quantum physics?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ya0r9/eli5_what_do_maxwells_equations_tell_us_and_why/
|
{
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"cfiv9h8"
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"text": [
"(Sorry for my bad English) Maxwell's equations are the foundation of electric and magnetic dynamics. Maxwell's equations are 4 equations which underlie, together with the Lorentz law, the dynamics of a classical physical electro-magnetic system. They are very important equations as they form a complete paradigm for classical electro-magnetic physics. \nThe laws are as follows:\n\n\n**1**\n\nThe divergence of the electrical field equals 4*pi*(charge density).\n\nThis equation is Gauss's law. \nA divergence is a mathematical operator. A divergence is an indicator for finding out whether there is a source that causes a certain flux or flow through a surface. Like water coming out from a faucet.\n\nThe electric field is the force an \"imaginary\" particle (or more accurately a motionless positively charged test particle) would feel at certain points in space. \n\nSo basically, Gauss's equation means that the net flux/flow of an electric field that comes through a surface equals 4*pi*(the net charge inside that surface). \n\nIt means, that it doesn't matter how the surface looks like, all that determines the net flux is the charge inside a surface.\n\nAlso, it means that outer electric fields won't change the net flux from a closed surface.\n\nThese are some extra points, and I know I don't elaborate and prove their correctness, so forgive me for the incoherence.\n\nThe important thing is- Gauss's law basically means that what causes Electric fields are charged particles. There is a source for electric fields.\n\n\n**2 \nThe second equation is:**\n \nThe divergence of the magnetic field equals zero.\n\nSince the divergence of the magnetic field equals zero, it means that there are no sources for the magnetic field. Or more accurately- thus far, magnetic particles weren't found. \n\nJust so you know- A magnetic field is produced by electric moving charges. \n\n\n**3 \nThird equation:**\n\nThe curl of the electric field equals minus the partial derivative in respect to time of the magnetic field times (1/the speed of light in vacuum (donated as c)).\n\nThis is the generalization of Faraday's law of induction.\n\nCurl is a tad harder mathematical operator to explain, but basically you may look at it like the circulation density of a liquid, or a field.\n\nFaraday law basically means that if the magnetic field that goes through a certain conductive closed circuit changes in time, then it creates an electric field (or more accurately an electromotive force).\n\n\n**4\nThe fourth equation:**\n\nThe curl of the magnetic field equals the derivative of the electric field in respect to time, times (1/c), plus 4*pi/c*(the current density of the electric field).\n\nThe fourth equation is Ampere's law with Maxwell's correction. It basically means that a change in time of the electric field induces a magnetic field!!\n\n\nSo how do Maxwell's equations relate to Special Relativity?\nWell, as you can see, Ampere's law and Faraday's law contain a constant unit 'c', which represents the speed of light.\n \nWith these equations we can yield partial differential equations which represent equations of waves. \n\nWhich means that the magnetic and electric fields are waves. \n\nThrough the equation of waves we can derive the speed in which those waves move. In the magnetic and electric waves' case, they move in a speed that equals the constant 'c'.\n\nExperiments showed that the size of that constant equals the speed of light.\n\nIn conclusion, Maxwell's equations show that the speed of light in vacuum in any inertial frame of reference (i.e were there are no fictitious forces, and the laws of Newton hold) is constant.\n\n\nBut! \nThis caused a paradox in physics during the end of the 19th century and the beginning of the 20th century. \nThat is because, in different inertial frame of references the velocity of an object is relative to the spectator's point of view. (And in other words- each velocity is relative, and not constant in different frame of references).\n\nHowever, Maxwell's equations clearly showed that the speed of light is constant for every spectator that is in an inertial frame of reference. \n\nWhat Einstein suggested was that in inertial frame of references, the speed of light is constant. This causes the time and the length to not be constant when an objects moves relatively close to the speed of light. \n\nI won't go any further about the changes of time and length and explain what exactly does it mean, and I won't explain why Einstein's suggestion settled the paradox, since it's already 4am in here. \n\nBut just so you get the hang of it-\n\nLet's say that someone travels from point A to point B in a very high speed that is close to the speed of light. \n\nThat someone sees himself reaching point B in a certain time t.\n\nSomeone else, that watches said traveller, from the outside, will see the traveller reaching point B in a later time."
]
}
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[] |
[] |
[
[]
] |
||
1xmtsj
|
What is the best way for a fan of history to read popular history books?
|
I am a history fanatic. Long a fan of this sub, but my love of history goes way back to childhood. I realize now that many of the books I have read were distortions for the sake of entertainment, or contained outdated information, ethnocentric perspectives and outright jingoist lies.
I believe that many of the fans of this sub are similar to myself in that they fall somewhere between the expert and the casual interest. Now I am reading Tony Judt's wonderful "Postwar." I am aware that he had a certain political perspective (one that closely follows my own, actually) and I do not want to get a single perspective.
Many of the [popular questions] (_URL_0_) focus on whether an author (Gibbon, Pinker, Diamond, Chomsky...I wish Tuchman was among them) can be trusted. **My question is, how can a fan of history who is not capable or interested in primary sources, do due diligence while reading secondary sources or popular histories?**
E: My purpose is to keep from constantly asking "which is the best book on X?" or "is this author worth reading?" Currently, I use wiki sources for my reading list...which is much better than the old method of buying whatever was available in B Daltons before the invention of the internet. Thanks for the help in advance. Best sub on reddit!
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1xmtsj/what_is_the_best_way_for_a_fan_of_history_to_read/
|
{
"a_id": [
"cfcruq6"
],
"score": [
3
],
"text": [
"Read a couple reviews of the book. Not on amazon or goodreads, but on JSTOR or google scholar. Search the title of the book and see if any book reviews of it come up in academic journals. Proper journals will have titles like *American Historical Review* or *Journal of Modern History* (*PostWar* was reviewed in both). Most reviews won't be 100% positive (they tend to be very formulaic and part of that formula is including a couple of criticisms), but if the reviews generally say things like \"thoroughly-researched\" or \"good contribution to the field of x,\" then it's probably a decently scholarly book, although you should still read it critically. If the book has been published for a year or longer and you can't find any reviews of the book in a major academic journal, then it's probably safe to say that it's less scholarly or academic and more popular.\n\nAlso check to see who published the book. It's not always true but generally a book published by a University Press (Oxford UP, Chicago UP, etc) is going to be more academic than a book published by HarperCollins."
]
}
|
[] |
[
"http://www.reddit.com/r/AskHistorians/wiki/faq"
] |
[
[]
] |
|
95mw5j
|
How can worker ants be female if they don't have the means to reproduce?
|
How can we tell the sex of an entire subgroup of a species if none of them can reproduce? There are obvious reasons to why the drones are male and the queens are female, but where does the sex of the workers come from?
|
askscience
|
https://www.reddit.com/r/askscience/comments/95mw5j/how_can_worker_ants_be_female_if_they_dont_have/
|
{
"a_id": [
"e3tviqs"
],
"score": [
26
],
"text": [
"Ants like bees and other hymenoptera determine sex in a haploid/diplod manner. The reproductive sex, the female one has 2 sets of chromosomes (diploid) one from each parent. The other sex the male has only one set (haploid) provided by its mother alone. During mating the haploid member provides a gamete ie sperm to the diploid member who develops and deposits eggs.\n\nThe females that are non-reproductive have the same genes are the females that are reproductive. They have just been inhibited from developing to full reproductive status due to diet as a larva and pheromones from the reproductive members. Among bees at least these non-reproductive members can under unusual circumstances start laying eggs fully proving they are female. The eggs however are not fertilized and only produce haploid offspring: drones."
]
}
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[] |
[] |
[
[]
] |
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15wqgo
|
Since your sleeping pattern is linked to the dark-light pattern, could you 'fix' a messed up sleeping schedule by going outside in the morning, or regularly throughout the day?
|
I've never quite understood sleep patterns and the influence of light. Seems like I've read research on how our patterns change if, for example, we are locked into a room with artificial light in patterns different from nature. What is the status of our understanding of man's natural sleep pattern?
And if light helps us regulate our sleep, why do so many people prefer staying up late? Is that a matter of social structures that go against our natural patterns? Can the introduction of artificial light (or a walk outside) help enforce a more natural sleep pattern?
If you're someone who stays inside a lot, and your sleep schedule is messed up, for example:
- Being awake 16 hours, then sleeping ten hours, thus constantly moving your schedule up by two hours, or
- Going to sleep at 4am, waking up at noon, and having trouble shifting it back to normal
and
- You try going back to an 8am to midnight schedule, but just can't get to sleep at midnights, even though you're tired every morning at 8am.
Could you fix it by exposing yourself to light in the mornings? Going for a walk outside, or even using those SAD type lights in combination with your alarm clock?
|
askscience
|
http://www.reddit.com/r/askscience/comments/15wqgo/since_your_sleeping_pattern_is_linked_to_the/
|
{
"a_id": [
"c7qjrwh"
],
"score": [
12
],
"text": [
"Yes, you are thinking along the right lines. The times at which you feel sleepy and alert each day are largely determined by your circadian rhythm. The timing of your circadian rhythm is primarily determined by your light/dark exposure pattern. So, whether you are trying to adjust your sleep/wake schedule, or trying to adapt to a new timezone, modifying your light exposure pattern is the best way to do it.\n\n**Phase Resetting**\n\nNow, to understand how to use light to change the timing of the circadian rhythm, you have to understand *phase resetting*. Basically, your body contains a clock that endogenously generates a rhythm with a period close to but not exactly 24 h. If you were put into complete isolation in darkness, you would continue to wake and sleep on an approximately 24 h schedule. But it's important to note that your clock's intrinsic period is not *exactly* 24 h, meaning you would gradually drift out of sync with the outside world under these conditions.\n\nThe reason most of us do remain entrained (i.e., synchronized) to the 24 h day is because our clock is reset a little each day by light to maintain a 24 h period. We each have a slightly different intrinsic period. The average for the human population is 24.15 h (_URL_0_), but everybody is a little different. Some people have intrinsic periods a little shorter than 24 h and some people have intrinsic periods a little longer than 24 h. Different people therefore require different amounts of daily resetting by light to remain entrained to a 24 h schedule.\n\n**Effects of Light**\n\nLight has different resetting effects on the circadian clock, depending on the time in the cycle. This is sometimes described in terms of a [phase response curve](_URL_2_). Light can either *advance* the clock (i.e., temporarily speed it up), or *delay* the clock (i.e., temporarily slow it down).\n\nLight in your *biological morning / late night* (i.e., the time around when you would normally wake up) tends to advance the clock. Light in the *biological evening / early night* (i.e., the time around when you would normally go to bed) tends to delay the clock. [Note that these times are relative to your rhythm. If you habitually wake up at 4pm, then that may be your biological morning!]\n\nIf you wanted to shift your schedule earlier, you would need to phase advance your circadian clock. This can be achieved by doing two things:\n\n* Increasing your light exposure in the biological morning, e.g., going for a walk outside shortly after awakening.\n\n* Decreasing your light exposure in the hour or so before bed, e.g., not using a computer, keeping the light dim.\n\nTogether, these will achieve a net phase advance of the rhythm, shifting it earlier each day. Decreasing light exposure in the hour before bed will also assist in getting to sleep more quickly, because: (i) light has an alerting effect, and (ii) light exposure tells the pineal gland to stop secreting melatonin, which is a hormone that helps you to get to sleep.\n\nKeep in mind that the circadian rhythm can only shift by so much each day, so it can take many days to move from one schedule to another. This is why jet-lag occurs, and it is also why people face problems on a Monday morning after staying up late on the weekend (a phenomenon sometimes called [social jet-lag](_URL_3_)).\n\nAs an aside, I mentioned above that everyone has a slightly different intrinsic circadian period. To achieve entrainment to the 24 h day, different people therefore require different amounts of net advance or delay each day, and therefore different patterns of light exposure. For this reason, your intrinsic circadian period partly determines how your sleep/wake cycle will typically be timed relative to the natural light/dark cycle (_URL_1_). People with longer intrinsic periods tend to be evening-types, whereas people with shorter intrinsic periods tend to be morning-types. In addition to circadian period (which you cannot control), there are many other factors that affect sleep/wake timing, including when you choose to get light each day (which you can control)."
]
}
|
[] |
[] |
[
[
"http://www.pnas.org/content/108/suppl.3/15602.short",
"http://www.ncbi.nlm.nih.gov/pubmed/11508728",
"http://en.wikipedia.org/wiki/Phase_response_curve",
"http://informahealthcare.com/doi/abs/10.1080/07420520500545979"
]
] |
|
5vnikg
|
why do scientists not care about certain places like pluto having water, yet care so much about places like mars
|
I'm guessing they only care to find other life. Well, why not look at Pluto instead of spending so much time looking through other planets?
Edit: Ah I see. Thanks for the answers!
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5vnikg/eli5_why_do_scientists_not_care_about_certain/
|
{
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"de3f23l",
"de3f2d9",
"de3f33p"
],
"score": [
6,
4,
6
],
"text": [
"Based on our understanding of life, water is one of the important elements of life.\n\nHaving warm enough temperatures is another. Pluto is just far too cold to care about because it will all be frozen.\n\nWe're looking for things close enough to earth that life as we know it might have a chance because we can't imagine anything else working.",
"Because water alone doesn't count for much. In Pluto's case, it's probably too far out from the Sun to support life, so it could literally be made of water and nothing else whatsoever, and scientists still wouldn't really be that interested.\n\nThey're looking for the right set of conditions in a given planet (i.e. like our own), and Pluto doesn't have many of those conditions.",
"Scientists care about life. Life (is widely agreed to) depends on liquid water. So we search for not only water, but places where water can exist as a liquid rather than ice or stream.\n\nIndeed, pluto may have water on it. But pluto is also -200 degrees or something, and so very unlikely to have life."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
9moh05
|
what are the alignment charts with “chaotic good” (etc.) actually mean, and what’s its backstory?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9moh05/eli5_what_are_the_alignment_charts_with_chaotic/
|
{
"a_id": [
"e7g2w5s",
"e7g337t",
"e7g36oa",
"e7g3uye"
],
"score": [
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7,
5,
5
],
"text": [
"A 'chaotic good' person is more than willing to assist his fellow man, and has no problems with breaking the law to do it. The guy that ignores ordinances against feeding the homeless to make sure no one starves is a good example of chaotic good. ",
"They’re charts of characters according to the alignment system in d & d. The good/evil axis represents moral good or evil. The lawful/chaotic axis represents how much they value the rule of law.",
"The origin (as far as I know) lies in the ttrpg Dungeons and Dragons. It is a model for describing the moral compass of a character. There are two axes: Lawfull vs Chaotic, and Good vs Evil. \n\nLawfull means using a law, system or code as the basis of your moral choices, chaotic is a more fluid, emotional and intuitive way of making moral choices. Good and evil are rather self explanatory, altough theologians, philosophers and other wise men have debated it of course. Mainly, the question is, will this help or hurt individuals. Neutral is just that, in between the extremes. Example, a neutral good player doesn't use a moral code, nor his emotions to decide what is the best course of action. \n\nSince the concept is filled with semantics, many people try to give examples of each alignment combination. ",
"Dungeons and Dragons characterizes the alignment of characters within the game based on two dimensions: Good (altruism, respect for life, etc.) vs. Evil (egoism, desire to harm and kill others, malice, etc.) and Law (obeying laws, honor, keeping some sort of code) vs. Chaos (freedom, anarchy, etc.), with both axes having a \"neutral\" point in the middle."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
et1o1h
|
why do cigarettes feel better than vaping?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/et1o1h/eli5_why_do_cigarettes_feel_better_than_vaping/
|
{
"a_id": [
"ffdmsjm",
"ffdlgz5"
],
"score": [
3,
3
],
"text": [
"I used to work for the company that made nicotine patches for smoking cessation and was in charge of the scientific substantiation for the advertising. \n\nThe nicotine from the smoke you draw into your lungs is absorbed into the blood steam almost instantaneously and gets to your brain in mere seconds, hence the instant \"hit\" to the nicotine receptors in your brain. \n\nVaping, on the other hand, has to cross the buccal mucosa membranes in your mouth, which means the nicotine in the vape takes much longer to arrive to your brain, hence the lack of that immediate \"ahhhh!\" you get when you smoke. Nicotine gum and lozeges you take to help you quit smoking work the same way. They are buccally absorbed at a much slower rate, which still gives those nicotine brain receptors some of what they crave, to take the edge off.",
"you smoke them farther apart from each other and tolerance starts to fall\n\nalso maybe because of carbon monoxide and other shit combustion products\n\nedit: a cigarette contains more nicotine than you can furiously vape in 5 minutes"
]
}
|
[] |
[] |
[
[],
[]
] |
|
2gy6gs
|
How considerable was the influence of the Epic of Gilgamesh on ancient Mesopotamian civilizations?
|
Basically what the title says. Would it be accurate to say the Epic of Gilgamesh was as influential (and popular) among the Akkadians, Assyrians, Babylonians etc. as the works of Homer were among the Greeks and Romans?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2gy6gs/how_considerable_was_the_influence_of_the_epic_of/
|
{
"a_id": [
"cknyecd"
],
"score": [
3
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"text": [
"I don't know if I can comfortably talk about literary influence in the same way we talk about, say Milton's influence on the Romantic poets but we can certainly say that the Gilgamesh poems(that is, the Standard Babylonian and Old Babylonian poems and the Sumerian Gilgamesh \"cycle\") were very popular texts that were widely copied from their first writing down to the end of Cuneiform literacy and across a wide range of places. The text we often speak of, the Standard Babylonian epic, has been found in fragments at Nineveh, at Nimrud, at Assur, at Sultantepe in modern-day Turkey and in Southern Babylonia at Uruk and other major Southern cities; closely related texts which are somewhat earlier in date have been found at Emar in Syria and in Anatolia at Hattuša. It also seems to have been found in a wide range of contexts; while Assurbanipal's library was a royal archive of sorts the Sultantepe tablets come for the most part from a private archive and a closely related text from Nippur is part of a school exercise tablet. Moreover, the Standard Babylonian epic is only one \"Gilgamesh\". It is itself a substantial revision with large additions and re-arrangements (most famously the prologue) dating from the 13th-11th century BCE of an older Babylonian poem that we think based on tablets of it that survive was a good deal more compact and heroic in tenor. And these poems both inspired further variations; perhaps the most dramatic example of this is a prose retelling from Hattuša-someplace where cuneiform was very much a creature of administrative life and which was in some ways on the fringes of Mesopotamia's cultural orbit-in Hittite that revised the poem to focus on the episodes that took place in the Cedar forest, an area closer to and more familiar to the Hittites. We can see therefore that the story of Gilgamesh was at once canonical-something that people could and did learn in school-and something that authors and scribes could revisit, return to, and revise or retell in light of their own concerns. If you wish to research the history of Gilgamesh further, probably the best starting point is A.R. George's _The Babylonian Gilgamesh Epic: Introduction, Critical Edition, and Cuneiform Texts_ or (more affordably) his paperback translation from Penguin Classics. Foster's _The Epic of Gilgamesh_ is probably not as good a translation but has some good supplemental essays as well as other texts relating to Gilgamesh and showcasing the essay's lasting influence. \n"
]
}
|
[] |
[] |
[
[]
] |
|
36wiok
|
how can a video uploaded 3 years ago at 24fps be converted to 60fps now?
|
The game I'm watching wasn't even recorded at 60fps, how does this work?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/36wiok/eli5_how_can_a_video_uploaded_3_years_ago_at/
|
{
"a_id": [
"crho4ca",
"crhoa3l"
],
"score": [
3,
2
],
"text": [
"Interpolation. Basically they use computers to fill in the gaps between frames, adding in frames that never existed, but are simply averages of the ones that did. ",
"It's called interpolation. It basically guesses what a new frame should look like based on the previous and following frames. You can reasonably assume that two adjacent frames will not be that different, so you can then reasonably guess a frame in between the two based on what those two frames look like. Interpolation equations have gotten really good these days. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
4gv8aw
|
Difference between ancient slavery and British/American slavery?
|
Slavery existed in ancient societies such as Rome and Greece and Arabian countries, but was it racially based? Is race-based slavery a fairly recent concept?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4gv8aw/difference_between_ancient_slavery_and/
|
{
"a_id": [
"d2ltqs9"
],
"score": [
3
],
"text": [
"In a manner of speaking, yes and no. Ancient cultures did sometimes dehumanize the cultures they subjugated it, but british/american slavery is something of an exceptional example, in that it was occuring within a culture that had effectively ended slavery (which had basically never happened before) so the racial aspects were used as justification for why it was suddenly ok to enslave people, because these people werent really \"people\""
]
}
|
[] |
[] |
[
[]
] |
|
fh9jpd
|
why is covid-19 being treated different than previous epidemics?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/fh9jpd/eli5_why_is_covid19_being_treated_different_than/
|
{
"a_id": [
"fk9ri9l",
"fk9rvu5",
"fk9ry4y"
],
"score": [
2,
2,
2
],
"text": [
"The interesting thing about it is that people can have it and just think they have the flu, but can infect people around them before, during, and after symptoms.\nThe main difference between this and the normal flu is that it can be passed from person to person easily.\n\nThe case fatality rate currently is a little more than 3%, meaning that if 100 people get it, then 3 or so of them will die. This is compared with the normal flu which is usually less than 1%.\n\nHowever, for perspective the MERS pandemic in the past (2014 I think) was much less infectious, but has a case fatality rate of 30% or so.\n\nThe H1N1 pandemic is the most recent I remember and the main difference between that and COVID 19 is how fast this new one is spreading across countries\n\nFor accurate data on this and other past pandemics go visit the CDC website",
"H1n1 was highly contagious but has a mortality rate of around 0.2%, only a little worse than regular influenza (not to suggest regular influenza isn't very serious).\n\nSars and Mers have much higher mortality rates but are much less contagious. I believe only something like 10K people have been infected between both of them. \n\nSars-Covid is different because it's in that bad middle ground - it's highly contagious *and* it has a significant mortality rate... in plain English: you're much more likely to catch it than you are to catch Sars, and if you do catch it, you're much more likely to die from it than you are from h1n1.",
"Ebola never spread out of its local region. SARS, while having a high death rate, only had a total of about 8,000 cases and was mostly limited to China, whereas COVID-19 is over 125,000 cases currently with cases in dozens of countries. There was initial concern with H1N1 because it is very similar to the Spanish Flu strain which killed millions, but while it did spread across the globe, it turned out to have a very low death rate (estimated 0.02% of cases in the U.S.). COVID-19 is currently estimated to have a death rate of 3.4%, and around 20% of cases require hospitalization which could result in widespread over-population of hospitals and cause shortages of many healthcare products."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
9da6pg
|
How prevalent was the practice of cannibalism in Pre-Colombian Mesoamerica?
|
I've recently sank my teeth into the rich, red, tender meat that is Mesoamerican history, and I find it delectable; like Ancient Greece but with bigger cities and much more blood. I also have a strange fascination with *having your friends for dinner*, so when I learned of a potential crossover between the two my appetite was piqued. I was hoping someone with a more experienced palate for Mesoamerican history than myself could satiate my hunger. I've had my fill of these food metaphors and they're starting to go a little stale, so i'll stop. Now, onto the main course of my question;
In accounts written by men in the entourage of conquistadors, there are several mentions of cannibalism being practiced by the savage pagan Indians (mostly Aztecs and other Mesoamerican cultures), no doubt to give just cause to their 'pacification' of them. Some people (such as Marvin Harris) suggest that, due to a protein deficiency in the diet, cannibalism actually made up a significant (and particularly grim) portion of the Mesoamerican diet.
What are the veracity of these claims? To what degree were reports of cannibalism exaggerated by the Spanish conquerors? And, most importantly, what role did cannibalism play in Mesoamerican culture, particularly in their unique and fascinating pantheon?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/9da6pg/how_prevalent_was_the_practice_of_cannibalism_in/
|
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"Don't get too hungry. Cannibalism is one of those tropes that the Spanish loved to bring out everytime they wanted to enslave someone. Along with sodomy, larceny, and rebellion, cannibalism is a fairly common accusation, mainly because it meant that conquistadors could legally enslave the population, and therefore profit. One of the nastiest and most harmful tales comes from Diego Duran's 'History of the Indies of New Spain,' where he claims that the Mexica official Tlacaelel orchestrates the Flower Wars against Tlaxcala so he could satisfy his taste for human flesh. This portrayal of the Flower Wars has been challenged by several historians such as David Hicks, Ross Hassig, and Barry Issac, and so the story is almost certainly an invention. \n\nThe real situation was much more complex. In the Mesoamerican case there is a little truth to the accusation. Mesoamerican people did occasionally eat small amounts of human flesh taken from sacrificial victims during rituals as communion. However, this bore little resemblance to a cannibalistic feast. Conceptually, the victims had been transformed into divinities, and so were no longer human. Eating human flesh was only permissible within this ritual context. Outside of this situation, it was considered abhorrent. \n\nRegardless of this, Spanish accounts of Indigenous cannibalism have obscured the realities of life in Mesoamerica, and the work of Marvin Harris and Michael Harner well demonstrate this point. Both Harner and Harris sought to explain Mexica cannibalism through materialism, arguing that it was a response to protein deficiency. However, a number of scholars such as Bernard Montellano and Barbara J. Price have aptly demonstrated the flaws in their arguments. First, they point out that the Aztecs actually had ample sources of protein, through vegetables (bean varieties), aquatic algae, insects, and fish. Second, they noted that the Mesoamerican sacrificial complex was hugely inefficient as a source of protein. It took a lot of energy to take captives, most of the flesh was wasted anyway, and the meat went only to a few elite warriors. Useless from a social perspective. Lastly, the Aztecs (the Mexica in particular) responded to agricultural pressures the same way everyone else did, by intensifying farming and expanding the amount of land under cultivation. The Mexica did this through the chinampas. Both Harris and Harner made the mistake of assuming that meat was food and all else was supplement.\n\nSo, although the Aztecs and their neighbours occasionally ate human flesh, they were not especially cannibalistic, and certainly nowhere near what the Spanish claimed. They did this for religious reasons, as it brought them into contact with their gods, not for nutrition. And they only did this in certain ritual situations. \n\nSources:\n\nHassig, Ross: Aztec Warfare: Imperial Expansion and Political Control, (Norman: University of Oklahoma Press, 1998)\n\nIssac, Barry L.: 'The Aztec 'Flower Wars'': A Geopolitical Explanation', Journal of Anthropological Research Vol. 39 No. 4 (1983)\n\nHicks, Frederick: “Flower Wars” in Aztec History', American Ethnologist Vol. 6 No. 1 (1979).\n\nPrice, Barbara J,: 'Demystification, Enriddlement, and Aztec Cannibalism: A Materialist Rejoinder to Harner’, American Ethnologist, 5/1, (1978)\n\nMontellano, Bernard R. Ortiz de: 'Cannibalism: An Ecological Necessity?', Science New Series 200/4342 (1978) and \nAztec Medicine, Health, and Nutrition, (New Brunswick and London: Rutgers University Press, 1990)\n\nHarris, Marvin: Cannibals and Kings: The Origins of Culture, (London: Collins, 1978)\n\nHarner, Michael: 'The Ecological Basis for Aztec Sacrifice', American Ethnologist 4/1 (1977)\n\n"
]
}
|
[] |
[] |
[
[]
] |
|
3xqg59
|
Is it possible to have pure water in liquid form at a temperature significantly lower than 0 degrees celsius?
|
askscience
|
https://www.reddit.com/r/askscience/comments/3xqg59/is_it_possible_to_have_pure_water_in_liquid_form/
|
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"Yes, this is called supercooling. It is unstable, and the water can rapidly solidify if it is perturbed.\n\nGO to 2:20: _URL_0_",
"In addition to supercooled water which is not really a stable phase you can have liquid water at temperature down to about -22^o C under very high pressure ~210 MPa, which you can see from the [phase diagram of water](_URL_1_). An example is the [Lake Vostok](_URL_0_) deep under the Antarctic ice sheet: it is a liquid lake even though the temperature is -3^o C due to the high pressure."
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=ph8xusY3GTM"
],
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"https://en.wikipedia.org/wiki/Lake_Vostok",
"https://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Phase_diagram_of_water.svg/700px-Phase_diagram_of_water.svg.png"
]
] |
||
2ucy1z
|
Can polar and nonpolar molecules ever mix?
|
What if polar and nonpolar fluids had the exact same specific densities? Is there anything keeping them from mixing?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2ucy1z/can_polar_and_nonpolar_molecules_ever_mix/
|
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"text": [
"When two liquid phases, A and B, are in equilibrium (even if they are immiscible) there will some A in the B phase and some B in the A phase. A common measure of this phenomenon is the partition coefficient _URL_0_",
"There is one product which you may have seen if you've ever looked at the ingredients in Mountain Dew. Brominated vegetable oil is used to tune the density of citrus flavors so they are the same density as the water. They form an emulsion and prevent an oily layer from forming.\n\n_URL_0_\n\nAlthough if you have a pretty large concentration that substances can't dissolve, then what will probably happen is you'll have a drop floating in the middle of the other liquid.\n\n_URL_1_",
"Yes. The are amphiphilic molecules that contain both polar and non-polar parts. ",
"So....Typicaldrugdealer, why is it you're interested In chemistry? Ha ha \n\nTo shed light on the actual chemistry involved: polar and nonpolar chemicals (liquids) interact with themselves differently. For instance polar compounds can align head to tail, pairing the partial positive of one compound with the partial negative of another. Hydrogen bonding is the example of this in water and There is an electrostatic force in This interaction.\n Nonpolar compounds have a much weaker interaction between themselves called London dispersion forces bc they don't have the positive and negative charges like polar compounds. \nSo, when you mix polar and nonpolar compounds the result can end up looking like a lava lamp. This is bc it takes force to break apart the interactions between polar molecules and the non polar molecules cant get in between them. Thus still producing a biphasic liquid mixture with droplets of each liquid type floating around each other. ",
"I feel like this is an ochem lab question and students often misunderstand separatory funnel. Density does not keep fluids from separating, it only allows you to predict by their mass which will be on top or the bottom. It's the difference in polarity that keeps the two layers separate. Only very small amounts of each solvent are present in the opposite solvent, and that allows extraction of the solutes into the other liquid. Because it's not a complete 100% of A is in B, you have to repeat the extraction multiple times."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Partition_coefficient"
],
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"http://en.wikipedia.org/wiki/Brominated_vegetable_oil",
"https://www.youtube.com/watch?v=MUKFaxy-z7s"
],
[],
[],
[]
] |
|
1jvfe6
|
If wikipedia is frowned upon by AskHistorians, are there any current efforts to create a historically accurate wiki or change the articles of wikipedia?
|
AskHistorians seems to call wikipedia a historically disinformative website. If such is the case, are there any current efforts by AskHistorians to:
* Change the wikipedia articles to improve historical accuracy? Why or why not?
* Create a simple, brief wiki which is easy to understand by the ordinary person? Why or why not?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1jvfe6/if_wikipedia_is_frowned_upon_by_askhistorians_are/
|
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"The closest thing we have is our FAQ. However, at least IMO, askhistorians isn't big or or organized enough to create an alternative \"factual\" wikipedia.\n\nAnd... well, it's not that Wikipedia isn't accurate, and scholars frowning upon it isn't because we're stuck up snobs. Wikipedia can be good, useful, unbiased and accurate, but it's a gate, not a goal.\n\nHistorical study and research is all about reading tons of papers by people with different approaches who bounce ideas off of eachother. Sometimes they contradict eachother and sometimes they compliment eachother. History is a conversation by people who look at the facts and try and figure out stuff beyond that - cause and effect, reasons, explainations, etc.\n\nThe problem with Wikipedia is that it's treated like some sort of universal truth, and even when it's citing sources you can't really tell what sort of bias these sources have. To paraphrase this, imagine history as a sports game: being a historian is looking at the gameplay, analyzing and figuring out who did what. You might think player A did good when another spectator thinks that player B was better, but you all looked at the same game and drew your own conclusions. In this sense, reading Wikipedia is like reading a news article the day after with just a scoreboard and the writer's opinion on the game. \n\n[Take a look at this article](_URL_0_). It says, for example, that Louis IX of France \" worked with the Parliament of Paris in order to improve the professionalism of his legal administration\", without any source. Now, assuming this is true, what was his relationship with the parliament? What was the situation before those reforms? What does \"professionalism\" mean in the 13th century? what does \"working with\" means in this context?\n\nOr in another paragraph, \"Because of the aura of holiness attached to his memory, many kings of France were called Louis, especially in the Bourbon dynasty, which directly descended from one of his younger sons.\" - if so, why is he Louis IX? The name was popular enough before him for eight other kings to be called Louis, with only seven kings after him. Even if Louis was a model Christian, who drew this conclusion? based on what? Why?\n\nYou see now? It's not that Wikipedia is bad per se, but being a historian isn't just about memorizing dates and facts, it's about critical thinking and analysis. ",
"Finally a chance to [post this article](_URL_0_) on exactly how hard it is get 'truth' across on Wikipedia!",
"I've thought for a long while now that it would be excellent if Wikipedia would support some system of *professional ratification* in which university professors, or established experts, would be allowed to tag *a version* of a Wikipedia page as being accurate, or rating it (out of 100, 10, 5, whatever). \n\nUnfortunately this system is unlikely to be implemented, so for the reasons /u/whitesock listed, we have to avoid Wikipedia.",
"I think you may have taken the wrong message away from my big Wikipedia comment! :( \n\nI actually quite love Wikipedia, I use it constantly for some things (its linguistic pages are all surprisingly good in my experience, and it's high-level math concepts pages saved my butt when I was studying informetrics) and know not to use it for other areas (it's opera pages are like 80% stubs and shitty so I use a professional encyclopedia product for music). I also donate to Wikipedia. Wikipedia is probably the most used reference inside libraries, and we don't even have to pay for it, which is amazing. We have other specialty resources (like Oxford Reference, and Credo Reference) but for ease of use for those general fact-based reference questions, Wikipedia usually trumps them every time. I remember I was once trying to fine more on the phrase \"sinosphere,\" and Wikipedia was the only place that even *had an entry.* Wikipedia is a very strong encyclopedia in a lot of ways. \n\nBUT it's still *an encyclopedia,* which is not what a historian would use to answer a question here. \"Just the facts ma'am\" is not what we're trying to give people, we want to connect people with historical interpretation and arguments, not just fact-spewing encyclopedians. And we can't just edit comments with historical interpretations into Wikipedia, because that's not what an encyclopedia is all about. ",
"Wikipedia is a great resource and is all in all a pretty accurate website. It has tons of great information and the quality is in many ways equal or better to /r/AskHistorians\n\nThat being said, when you did your first research paper in the third grade, the teacher should have told you: *an encyclopedia isn't a source*. The medium is innately unscholarly and indirect. Traditionally, it was devoid of citations, though that is not entirely the case for wikipedia.\n\nIn /r/AskHistorians it is appropriate to cite scholarly sources, often primary or ancient sources (though not always). It follows in the scholarly tradition.\n\n > Change the wikipedia articles to improve historical accuracy? Why or why not?\n\nYes, people who can do this should do this. It's not that wikipedia has terrible historical accuracy problems--there's a lot of misinformation and a lot of outdated approaches reflected, but not significantly more true than Encyclopedia Britannica or /r/AskHistorians (perhaps less). But just as citing another /r/AskHistorians post *as a source* is appropriate. People often recommend specific wikipedia articles (and specific /r/AskHistorians posts), and this is good.",
"I generally frown upon the use of any encyclopedia for papers.",
"I can't speak for Historians, but claims are made on wikipedia relevant to every field. Peer review and academic inertia is largely what determines the \"success\" of a hypothesis or claim; it's hard to map that model to a free-for-all model like Wikipedia.\n\nIn other fields, there are concerted efforts to provide what I would term \"open access academic encyclopedias\"—written by academics only but open to the general public. For example, the [Stanford Encyclopedia of Philosophy](_URL_1_) or [The Living Handbook of Narratology](_URL_0_). Warning, both of them have substantial quality content and addictive properties.\n\nMy impression with Wikipedia is that most academics love it as an abstract—you would never cite it, but it's still great to get a handle on a topic."
]
}
|
[] |
[] |
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"http://en.wikipedia.org/wiki/Louis_IX_of_France"
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"http://chronicle.com/article/The-Undue-Weight-of-Truth-on/130704/"
],
[],
[],
[],
[],
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"http://wikis.sub.uni-hamburg.de/lhn/index.php/Narratology",
"http://plato.stanford.edu/contents.html"
]
] |
|
bwo9f8
|
how exactly does our brain "direct" blood to a specific body part, e.g. for an erection?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bwo9f8/eli5_how_exactly_does_our_brain_direct_blood_to_a/
|
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"It, for the most part, does not direct blood. It controls muscle contractions, which can clamp down vessels to slow blood flow to regions, such as reducing blood flow to one's hands or feet when it's cold.",
"Your circulatory system is just an interconnected series of pipes that goes around your body starting and ending at your heart. Like water pipes, you can increase or decrease the flow of these pipes. Your body directs flow by releasing certain signalling chemicals into the blood which makes the vessels (pipes) either expand/dilate/widen (vasodilation) or contract/constrict (vasoconstriction) to allow more or less blood through. Some of these act locally in a certain area, while others will act in a broad region of the body. \n\nA penis is like a bouncing castle. Blood, or air is pumped in and blood, or air will passively leak out. During an erection, your body will increase the amount of blood going in by making the vessels expand in diameter. This means more blood goes in, while the same amount is going out. The net effect is a bouncier castle, or an erection.",
"For the most part, it comes from the release of chemicals that tell blood vessels to either dilate and increase blood flow, or constrict and reduce blood flow. There are various chemicals that do this, such as adrenaline, and different areas of the body are susceptible to them in different ways to give some targeted control. For an erection specifically, the arteries dilate and the veins constrict, increasing blood flow in and decreasing blood flow out."
]
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[],
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||
7y6gj0
|
Since Western Europe only saw the Holy Roman Empire as the only Empire, what polity did they refer to Byzantium as?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/7y6gj0/since_western_europe_only_saw_the_holy_roman/
|
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"The best source I have on me right now is that of the crusaders from France as they visited Constantinople on their way to Jerusalem during the First Crusade, where they heavily refer to the Byzantine state as \"Romania\", or more literally Land of the Romans.\n\nCount Stephen of Blois, a minor leader of the First Crusade from his letters back home, refers to the Byzantines as Romania:\n\n > You have certainly heard that after the capture of the city of Nicaea where we fought a great battle with the Turks, and by God's aid conquered them. Next we conquered for the Emperor of all Romania\n\nThere are also many instances of the Byzantines being referred to as \"Empire of the Greeks\" to delegitimize their claim to the Roman Empire, as far as I know this was almost always intended as an insult to the empire and used mainly by Italians and the Papacy to reassert their claim of the Holy Roman Emperor being the legitimate continuation to the Roman Empire.\n\nBy and large, Western Europe did refer to the Empire in Constantinople as the Roman Empire, or Romania for short, despite insistence that the Holy Roman Emperor was the legitimate claim by the Papacy.",
"Its a misconception that Western Europe saw the Holy Roman Empire as the only empire. It was not a situation like China and Taiwan, today were both claim to be the legitimate rulers over the same territory. There were areas of disputed sovereignty but fundamentally they did not claim to be the same state. The setting up off the Latin Empire, after the fourth Crusade, which was called the Empire of Romania with no political problems. \n\nIn commutations between Frankish states and the Eastern empire what they called each other varied with there current relationship. When the Italian maritime republics were allied they address the Emperor with his correct title. When they were hostile the Emperor of the Greeks. Even communications between the two Empires varied dependent on the state of relations. \n \n\n"
]
}
|
[] |
[] |
[
[],
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||
psem9
|
What would you see in the middle of a ring of mirrors?
|
If you were to have a giant ring of mirrors set up, so that there were no corners between them (so effectively a giant ring shaped mirror), and then stand in the middle of it, what would you see? I can't my head around this and I can't figure out if you would see one reflection of yourself, or a reflection of yourself everywhere. If it's the second option, what would that even look like?
|
askscience
|
http://www.reddit.com/r/askscience/comments/psem9/what_would_you_see_in_the_middle_of_a_ring_of/
|
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"Lighting design engineer here. We work with parabolic reflectors all the time. They try to focus light (information) from a source and put it into a specific direction. All parabolic surfaces, however, have a focus at which point rays of information will converge. With a perfectly circular surface concentric with its focal point, essentially every \"plane\" on the reflector is normal to the direction of the beam going to or coming from the focus. \n\nSo imagine it this way: If you have an octagonal ring of mirrors, you can look in 8 different directions from the center and see specifically one reflection in each direction. If you bump that up to a dodecagon, you'll see ~~20~~ 12 distinct reflections. As the planes get thinner and thinner, you begin to lose surface area that can reflect the whole image back to the focus. Eventually, in the case of the ring, the surfaces get infinitesimally thin and you're left with a sliver of a reflection in every direction you look in. The result is an amorphous, but continuous, smear of color, almost as if someone covered you with some sort of transfer material and rolled and dragged you around the interior surface of the ringed mirror.\n\nA lightbulb at the center of such a reflector would see nothing but a band of continuous light all the way around, but it would be very different for any person observing from a point not at the center.",
"What about inside a mirrored sphere with a lightbulb in the center?",
"It's interesting to note that in this situation, you are at the center of curvature (twice the focal length). Rays emitted from the center of curvature will be reflected back to the center of curvature. Secondly, this ring is exactly a circle, and because you are using all of the mirror, it can't be approximated as a parabola, meaning the mirror will severely suffer from third order spherical aberration. This would ordinarily not be a problem for a point source at the center of curvature, but you are an extended source (assuming the ring mirror isn't so large). This will blur the reflections, and other aberrations such as coma willl further blur the reflections. \n\nSo, final answer: it depends on how large the mirror is, if it is so large that you are a point source, all rays will be reflected back to that point (image is formed with1:1 magnfication). If it is a smaller mirror, all rays will be reflected to a much larger spot (meaninglots of blur). \nI think that's right...",
"There's a Japanese (since Heian-period) urban legend / ghost story that involves this. Did you get the idea from it?",
"I've had a similar question for a while now. Lets say you have a perfect glass sphere (hollow) that is mirrored to be reflective on the inside. There are no seams or flaws, it is perfect. Now lets say somehow you got a flashlight in there (I don't know how, this is theoretical) and left it on until the batteries died. \nWhat happens when if you break the sphere in a dark room? \nI assume nothing happens. It breaks. That's what the real world is like. I just don't understand where the light goes. ",
"What would I see standing in the middle of mirrored sphere ?",
"A friend of mine built one. [Here's a video he made about it.](_URL_0_)",
"I am from Sweden so you have to apologize for my bad English.\n When I saw this thread on Reddit, and saw all enormously smart answers to this question, I just had to contribute with my \"mirrorproblem\".\n\n Imagine a perfecty plane mirror that is parallel to a so-called spy mirror (also perfetcly plane). You are behind the spy mirror and looking toward the perfect mirror. What do you see?"
]
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[],
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|
f4012p
|
How did they find out light and radioactivity and radio were all the same electromagnetic phenomenon?
|
askscience
|
https://www.reddit.com/r/askscience/comments/f4012p/how_did_they_find_out_light_and_radioactivity_and/
|
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"There are different types of radioactivity, only one of them (gamma radiation) is electromagnetic radiation.\n\nRadio waves were discovered when working with electric currents, so that one was easy. For visible light, people measured that it has the same speed as an electromagnetic wave. It also shows diffraction similar to radio waves, and it interacts with electrons in the way we expect from electromagnetic radiation.\n\nGamma rays are roughly the nuclear physics equivalent to visible light for atoms - it also moves at the same speed, it can be reflected by crystals (which leads to a wavelength measurement), and it interacts with charged particles in the way we expect from electromagnetic radiation.",
"What I was told in Fields and Waves class is that a sequence of things happened,\n\n1. [Maxwell fixed Ampere's law](_URL_0_)\n2. This fix allowed deriving a wave equation from Maxwell's equations\n3. Standard methods for finding the velocity of the electromagnetic wave yielded c\n\nAnd the key thing was that the speed of light was already known; it was c, determined experimentally. Finding that Maxwell's equations can calculate that light and electromagnetic waves are the same speed is a good indication that light is an electromagnetic wave. \n\nThat's how I remember the explanation from nearly a decade ago, so please feel free to correct me.",
"It is of note that it took over a decade for physicists to understand that X-rays were the same phenomena as other electromagnetic waves. They behaved similar to visible light in some respects, but not others. The chain of experiments that it took to figure this out is a long and technical one. X-rays were discovered by Röntgen in 1896, but not until experiments in crystal diffraction in 1912 that it was proven that they were a form of very short-wavelength electromagnetic waves. Prior to that there were many theories about what they were, all with some evidence behind them: longitudinal vibrations in the ether, some kind of particular radiation, some kind of extreme ultraviolet radiation. One of the difficulties in figuring this out is the fact that they do exhibit both wave and particle properties, and the wave-particle nature of the quantum world was not at all understood at the time.\n\nWhich is only to say: like many things in the history of science, there are the \"simple\" answers that textbooks give, but the reality is usually pretty messy and unclear for a long time."
]
}
|
[] |
[] |
[
[],
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"https://www.youtube.com/watch?v=os_Qt89VokE"
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||
17evl2
|
How distinct were the classes of Ancient Rome?
|
Could a pleb have risen up or a patrician fallen out of wealth? How did the importance of class fluctuate over time? I'd always thought they were stagnant but when I started thinking about and looking into the similarities of Rome and America, I wasn't as sure. So any help would be appreciated. Another question: what was tax farming and how was that done? The Wikipedia page on it is really poorly written.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/17evl2/how_distinct_were_the_classes_of_ancient_rome/
|
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"The patrician/plebeian division was more or less irrelevant by the Late Republic. \"Patrician\" specifically refers to a select group of families that were supposedly descended from the men chosen by Romulus for the first Senate. The status did not automatically confer status, political position or wealth any more than, say, British nobility today does, and there were many poor and irrelevant patricians and many wealthy and powerful plebeians. For example, Sulla, despite being of the *gens* Cornelia (the most consistently important family in the Republic) began life in rather sordid conditions--although I must stress that those patricians who were *truly* impoverished did not make it to the history books. Likewise, many of the wealthiest and most important families were plebeian--the Caecilii Metelli being a good example.\n\nAs for general social mobility, there seems to have been a fair amount of it. Epigraphy on tombs show us that there were wealthy men coming from every imaginable profession, the most endearing example being the [Tomb of Eurysaces the Baker](_URL_0_), a freedman. There is also a great graffito from Pompeii which details the many jobs that the target has tried a failed at, including innkeeper, farmer, baker, and cobbler, and concludes with the immortal line \"if you now choose to lick cunt you will have truly attempted every profession\". Liquidity within a labor market is a fairly important aspect of a fluid economic system, and Rome's was unusually liquid for a premodern society.\n\nNow, if you change the question somewhat and say \"I am an average inhabitant of Rome, what are my odds of fighting out of poverty?\" we are probably still dealing with only a very small chance. The majority of people would have still been rural laborers, and even if the material condition of rural laborers was quite good for an ancient society, it would have still been a very much hand-to-mouth existence with little hope of advancement. Although the city offered higher hope for advancement, it too would have been a very difficult life. It is surely significant that a disproportionate number of recovered middling tombs are from freedmen, who would have entered the labor market with skills and connections. The modern Western world is quite unique in that the majority of the population is not poor. \n\nBut to answer simply, there was a great deal of economic mobility, as wealthy and influential families slid into poverty and poor families pulled themselves up. The effect that this would have on the \"average\" Roman is difficult to tell--this was still a premodern society.",
"Tax farming was the practice of the roman state of selling the right to tax a given province.\n\nThe state did receive a given sum, and then the man who did win the contract had the right to collect the taxes in the province, pocketing the difference between what he did give to the state and what he was able to get.\n\nAs you can imagine, that was a situation that could lead to many abuses. It could also become potentially a very political problem (for example, Caesar did legislate on this matter as a favor to his ally Crassus when he was consul).\n\nThe \"publicani\" in the christian gospels were the agents of the men who did win the tax contracts. As they did act as tax collectors, this explain why they were not exactly loved."
]
}
|
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[
[
"http://en.wikipedia.org/wiki/Tomb_of_Eurysaces_the_Baker"
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|
7xrjh8
|
why do white supremisists adopt the nazi swastika and hitler himself as symbolic of their beliefs when none of them would pass nazi "racial purity" standards?
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explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7xrjh8/eli5_why_do_white_supremisists_adopt_the_nazi/
|
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"You're absolutely correct. However the rise of white supremacy doesn't start off targeting EVERYONE who isn't \"pure\" rather it starts with obvious targets. Then slowly moves in to a narrower and narrower definition. First they target those who are obviously non-white, then the religions that are \"not white\" then the religions who stood against them, then the groups that didn't actively support them, then it becomes those who supported them but think differently because they \"might\" betray them, it just gets narrower and narrower until the staunch supporters realize that they are next."
]
}
|
[] |
[] |
[
[]
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||
f0md1
|
Cosmological redshift vs the Doppler effect
|
Seems like a basic enough question, but I couldn't find a way to word it for google.
If the distance between two galaxies is increasing solely due to the expansion of space, then galaxy 1 will see that the light emitted from galaxy 2 appears to be redshifted. This has nothing to do with the Doppler effect, since the two objects are still stationary relative to each other within expanding space (right?). So it is just the light wave that is physically being stretched out along with space that causes the redshift.
Now what I'm wondering is, does this work out to be the exact same amount of redshift you would observe via the Doppler effect if space were not expanding, but instead the galaxies really were moving away from each other (at the same rate as before), within a static space? that is, if you had the same rate of increase in distance over time between the two as you had when it was solely due to expanding space, would you observe less redshift, more redshift, or the same amount of redshift (since this is now caused by a completely different phenomenon)?
If the aren't the same, how far off are they?
And if they are, does it matter what the value of the Hubble constant is? Or will this work with any rate of expansion?
|
askscience
|
http://www.reddit.com/r/askscience/comments/f0md1/cosmological_redshift_vs_the_doppler_effect/
|
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"No, they actually appear to be moving relative to each other. That's the source of the redshift.",
"It's possible to construct a model of the universe that foregoes metric expansion in favor of special relativity alone. One fairly well-known one was called the Milne model, after the guy who constructed it.\n\nThere are some problems that arise in these models, though. And they're not small ones. But let's work through it anyway.\n\nThe first problem is that the observed redshifts equate to recessional velocities that are far, far too low. Take UDFy-38135539, for example. That's a galaxy in the Hubble Deep Field. It's about 30 billion light-years away, give or take. It has a redshift of 8.6, making it one of the highest redshifts yet observed.\n\nIf you plug in a redshift of 8.6 into the relativistic Doppler equation, that comes out to a recessional velocity of 0.98*c.* Which is quite fast, to be sure. But if that galaxy had been moving away from us at that speed for *the entire history of the universe,* it would be less than half as far away from us as it is today. Which means the universe must necessarily be much older than the 13.7 billion years (ish) we know it to be, so the model runs smack-dab against reality at that point.\n\nBut okay, let's ignore that. Let's say instead that the universe really is older than we think; *much* older, at least twice as old. We move on to step two of the model, and find that the mathematics of special relativity makes very solid predictions of how distant galaxies should be moving through time relative to us. Say you have a galaxy with a redshift of 0.574 — a far cry from the highest observed redshifts, but still indicating (via the relativistic Doppler equation) a recessional velocity of 0.42*c.* Special relativity would tell you that that galaxy should progress toward the future about 1.1 times slower than we do. In other words, an event that takes *T* time here will be observed to take 1.1*T* time when we see it happen there.\n\nWe can measure just that kind of thing, by observing type Ia supernovae. These have very predictable light curves, so we can treat them like clocks. What we find is that time in that distant galaxy — the .574 redshift one — actually runs about 1.5 times more slowly than time here.\n\nIf you want the maths, the relativistic Doppler equation says that the time dilation is … um. I still don't know how to type equations here, even if they can be typed. But if you go to _URL_0_ and type in\n\nγ == (1/2) (1 + z + 1/(1 + z))\n\nyou can see the equation written out.\n\nAnyway, the general relativity model says that time dilation goes by 1+z, which is clearly different from the above equation. And the observations closely conform to the general relativity model.",
"The two are fundamentally different. With Doppler shift the change in frequency happens the instant the photon is released. With cosmological redshift the photon leaves at it's \"true\" wavelength and is gradually redshifted as the space it's travelling through slowly expands. \n\nThey give different answers. Using the doppler redshift often yields galaxies that are travelling faster than the speed of light. Cosmological redshift explains why galaxies further away from us are more red shifted.\n"
]
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|
1tu8su
|
how is audio created with only 1s and 0s?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1tu8su/how_is_audio_created_with_only_1s_and_0s/
|
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"At a very low level, any audio can be described as (more or less) how loud it is at any given point in time. When you hear a note played on a piano, what's happening (roughly) is that the volume is getting louder and softer and louder and softer over and over and over, very very fast. When you hear a different sound, it's still just louder and softer over and over very very fast, but it's doing it in a different pattern than before.\n\nSo you can describe a sound as something like \"this loud, then a millisecond later that loud, then a millisecond after that so-and-so loud\", and so forth.\n\n\"This loud\", \"that loud\", and \"so-and-so loud\" are just numbers.\n\nAny number can be described with just 1's and 0's - for example, \"When I say 0, I mean 0; when I say 1, I mean 1; when I say 10, I mean 2; when I say 11, I mean 3; when I say 100, I mean 4; when I say 101, I mean 5.\"",
"The ones and zeroes are used to encode numbers that represent a certain voltage in your playback device. By having many of these numbers per second controlling the electrical output, a varying signal is created. This signal is amplified and fed to your ear buds or loudspeaker, rendering a manifestation that you can perceive with your senses."
]
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[],
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1x79uf
|
why is it that when it's a really cold night outside, the sky is so much clearer & crisper to see the stars more clearly? [serious]
|
I've noticed this my whole life living in southwest N. America, & amp; I've always wanted an explanation. Can anyone help explain this to me in detail please? Is it an air pollution/pressure/moisture thing, or something else entirely? Why does this happen? Would really appreciate it :)
Edit: Thank you for your helpful answers everyone! I will certainly keep this in mind next time when it's cold out :)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1x79uf/why_is_it_that_when_its_a_really_cold_night/
|
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"The sky isn't clear because it's cold, it's cold because the sky is clear. Clouds act like a blanket that keep the warmth radiating from the earth's surface escaping into the upper atmosphere so easily. Without the clouds, the heat escapes. This is why deserts are usually freezing cold at night - no moisture for clouds.",
"Because clouds help trap warmth in the atmosphere. They're like a blanket over the sky."
]
}
|
[] |
[] |
[
[],
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|
regmd
|
how murder trials and sentencing work.
|
(Obviously not an appropriate topic for a 5 year old, but can someone dumb this down for me?)
More specifically, why do some people that knowingly commit murder (knowingly as in they aren't deemed legally insane) get sentenced to a life sentence or 10 years in prison, but others get the death penalty? How do they decide who gets a death penalty and who just gets a life term? Is it totally up to the judge?
I watch a lot of cover stories about murder trials on TV and I can't think of any specific cases right now, but why is it that a person who kills one other person can get the death penalty, but someone who mass murders a bunch of people will get life in prison or something?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/regmd/eli5_how_murder_trials_and_sentencing_work/
|
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"ELI5: Murder.\n\nWell, I'll give this a shot. Sit down, 5 year-old, and I'll tell you a tale. \n\nFirst, we need to understand what **murder** actually means. **Murder** is the *unlawful* killing of another person with **malice aforethought**. Unlawful means killed when they weren't supposed to, unlike when police officers or soldiers have to kill someone. **Malice aforethought** means that they killed the person on purpose, and they thought about it or planned it beforehand. To **murder** someone, you have to mean it. Malice means that you either want to kill someone, or you're being so reckless that you're risking peoples lives, or you're committing another crime where someone gets killed in the process (felony-murder). \n\n*First degree* murder has intent and and planning. *Second degree* murder has intent but not planning. If someone killed someone else \"in the heat of passion\", it's probably second degree. \nIf these things didn't happen, then it's probably not murder. \n\nSometimes when people kill people, it can be something like an accident. Killing someone, but not murdering them, is called *manslaughter*. \n\nIf someone kills someone \"in the heat of passion\" but they have a reason they were angry, then it might be what is called **voluntary manslaughter**. It comes from a situation where a reasonable person might do what they did. This can happen when someone is provoked to kill. \n\n**Involuntary manslaughter** means that you didn't mean to kill someone, but you did, so you have to be punished for it. Not as much as if you did it on purpose, but you still did something bad. This can happen if you make a mistake while driving, or you don't do your job right and someone dies. \n\n\nBecause there are different types of murder and killing, there are different sentences. There are a lot of pieces that have to come together, and those pieces will tell you how much jail time someone has. Did a bad man think about murdering a girl, plan it, find her, and murder her? Can the lawyers prove all of those things? Then he will go to jail for life, or get the death penalty. Did a good man make a mistake with his car and someone died? Can the lawyer prove that it was an accident? Then he will go to jail for a little while, but not forever. \n\nThis all depends on what the prosecution can prove, and what state the killing happens in. Different states have different laws about the death pentalty and sentencing."
]
}
|
[] |
[] |
[
[]
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|
5wo9ao
|
how can videos that were recorded in 30 fps can be reencoded in 60 fps ?
|
I was talking about this with a friend, he said that it was still looking smoother
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5wo9ao/eli5_how_can_videos_that_were_recorded_in_30_fps/
|
{
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"Interpolation. Encoding software basically \"makes up\" a frame in between every frame. If you look at it closely enough you can see that it is not true 60 FPS. ",
"The easiest way is you can just double the frames.\n\nFrames at 30 FPS: 123456789\n\nFrames at 60 FPS: 112233445566778899\n\nA more complex method is interpolating the frames by estimating what's between them. If the RGB at pixel X=50 and Y=171 is value 30 in the first frame and 70 in the second frame, you make it 50 in the interpolated frame. An even more complicated method might be to interpolate shapes and motion."
]
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[] |
[] |
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[],
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6jjlxz
|
if survival is the primary goal of life forms, then why do we age to death?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6jjlxz/eli5_if_survival_is_the_primary_goal_of_life/
|
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"text": [
"It's survival to reproduction, not survival forever. If something only needs a year to be able to reproduce, then it won't need to continue living after it has reproduced. ",
"It's not survival but procreation. Any organism's \"purpose\" is to ensure the continued existence of its genetic material. Unless you're part of a social species that relies on the group, there's little reason for you to live on after your offspring has reached maturity.",
"You may want to read the book *The Selfish Gene*, by Richard Dawkins. It's pretty short and it's an important book. In it, he lays down the argument that it's genes themselves, not organisms or the species that are trying to survive and reproduce. So the individual creature is just a means to the end of propagating genes. Once those genes have been propagated in a successful fashion, the organism becomes unimportant in replicating and can die off while a younger, stronger, better organism takes over spreading genes.",
"Just wanted to add onto the other explanations and say that a living human past their prime requires resources and acts in direct competition for them with the younger generation, including their offspring. As a result, evolution creating a method to kill off the old is actually beneficial for the survival and the continuation of the species. As shitty as it sounds, that is life."
]
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1mx97m
|
How was the electricity created that powered the first electrical telegraphs in the 1840s?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1mx97m/how_was_the_electricity_created_that_powered_the/
|
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"[Batteries.](_URL_0_)\n\nInteresting for me is that amplifiers were not in use yet so the distance from telegraph station to telegraph station was decided by the distance that a clear signal could be sent. To the present day the towns that were built up around these telegraph stations are ten miles apart."
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"http://members.kos.net/sdgagnon/te4.html"
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v2vkl
|
Would it be possible to have a soda bottle that chills itself from decompression?
|
Would it be possible to have a bottle of soda that when opened, the act of decompression could lower the temperature of liquid from say 21*C(70*F roughly room temp) down to a cool 7*C(45*F). Assume 750ml of liquid (soda being mostly water so 4.18J/g*C to keep it simple).
|
askscience
|
http://www.reddit.com/r/askscience/comments/v2vkl/would_it_be_possible_to_have_a_soda_bottle_that/
|
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"It would be possible but the size of the container would be unwieldy. For instance a can like you describe exists but a significant amount of the volume of the container is dedicated to the heat-sink, vacuum, and evaporative material. The can holds 300 ml of beverage in what would normally be a 500 ml can. \n\n_URL_1_\n_URL_0_",
"They actually looked at this in the late 1980s; there was a plan to put a small Freon cannister inside the soda can. You'd pull one tab, and the Freon would be released in a specific fashion, resulting in a cold cannister inside the soda can. Once they equilibrated, the temperature would drop so many degrees and you'd have a cold can of soda. That plan went bye-bye shortly after we found out how bad CFCs were on the ozone layer; there may be another halocarbon that we could use today.\n\nIt should be noted the opposite is true in that there are self-heating meals available. The MRE heater is the most common sort, relying upon oxidation of magnesium powder, but the older version relies upon water + calcium oxide (lime). As recently as 3-4 years ago, some company marketed a line of self-heating coffees using this mechanism. Pretty slick, but not without its hazards. The older products (meant to be for soldiers, or for single guys that were too lazy/inept to operate an oven, but still wanted hot TV dinners) would occasionally explode; there were manufacturing problems. And then you'd get hot lime spattered everywhere, and people would get thermal and/or chemical burns. Not the greatest of inventions, which is one reason why the magnesium oxidation packets in MREs predominate today."
]
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"http://www.gizmag.com/go/3136/",
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38scle
|
why do humans like pillows to support their heads when they sleep?
|
Other animals don't need any sort of head support, and if museums are correct, humans have sought out sleep-time head-supporting objects for millennia.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/38scle/eli5_why_do_humans_like_pillows_to_support_their/
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"I think it is because we can't lay down comfortably if we do not have a support for our head, especially if we lay on our side.",
"I would wager it's for comfort and spinal alignment. It's not as noticeable on your back but when you sleep on your sides and let your head hang lower putting your neck at an angle which in turn puts pressure on your spine.\n\nJust an educated guess from someone not with any sleep study, just someone who has had minor problems in the past with sleeping and waking up with back/neck pain",
"I think OP's point, is that other animals *can* lay down comfortably without aids, while humans cannot. Why did we evolve in such a way as to require outside help for something as essential as sleep?",
"Not a scientific answer but I think it's because we have the option. My dog sleeps with a pillow. And animals in the wild often use each other as pillows and warmth. ",
"I feel like no one has really answered your question. All of these responses seem to be \"because our heads need support\" instead of WHY our heads need support when other animals do not.",
"Our heads evolved to be bigger relative to body size, requiring more support.... But instead of evolving coping mechanisms for dealing with our heads biologically, our big heads figured out head support first.... So then there was no evolutionary pressure to select for a biological accommodation (people survived just as well without evolution selecting for a trait that accommodated this failure), we intellectually solved that problem.",
"Ultimately, I don't think we need them but are instead just used to them. For example, you can support your head with your arm when you sleep sideways. However, now that we have pillows it makes it easier and more comfortable for us to sleep, beyond what we could do before. \n\nAdditionally, many animals do find support for their sleep; don't nests and burrows generally have leaves or other things that the animal rests on?",
"The spine of primates is curved to support standing upright, so it does not do as well lying flat on our back or stomach. We can do so, but it is not as comfortable as lying on our sides. \n\nPrimate shoulders stick out past our head, so when we lay on our sides our heads are not lying flat on the ground (unlike dogs or cats for instance). The larger the primate the bigger the gap (monkeys have tiny shoulders and are very flexible so they can usually just shift their shoulder out of the way). Therefore to support our heads we need something to fill the gap between our shoulder and head.\n\nGoogle \"ape sleeping\" and look at the pictures. You will see that apes also sleep on their sides with their arm under their head. ",
"Hmm i believe we're assuming animals are 100% comfortable when they lay down and that we cannot without a pillow. I believe that if a person never adapts to sleeping with a pillow he/she will find a sufficiently comfortable position to sleep. Our pillows keep our spines aligned for our convenience but not necessarily a necessity. How do large primates sleep? they're fairly similar in body structure to us. (off to look up \"sleeping ape\")",
"Our spines work a bit differently than most other mammals. The changes that we evolved to our spine that allow us to comfortably stay upright balancing something roughly the size and shape of a bowling ball on top of it all day had some other side effects. \n\nOne of those is that our spine is a lot more rigid than other animals. A good illustration of that point is to look at your dog curled up into a circle to sleep, or your cat sleeping draped across your legs. \n\nSo the extra strength that we needed to stay upright made it harder for us to sleep in unusual positions. But all this means is that standing tall was more important than sleeping draped across branches to our ancestors. And losing the ability to sleep anywhere probably wasn't much of a cost to pay for our genes, since our ancestors were crazy smart nest building mammals. If they needed a little lumbar support they knew where to find a nice soft mossy log to cushion the nest. \n\nFor fun, here's a photo of a chimp in a nest. _URL_0_\n\nAlso, on an anecdotal level, it's completely possible for humans to sleep comfortably without a pillow on a flat bed. I did so for a couple of years as a personal experiment. A softer bed really helps it, but I got used to sleeping on my back in about two weeks. Sleeping on my side took a bit longer, but I basically learned to use my shoulder/arm as a pillow to keep my neck in a comfortable position after a monthish. ",
"it is just habit.\n\nI've slept without a pillow on a rather hard bed for well till I was 15 or so; you get used to it. \nLot of Asia used to sleep on bamboo mats on hard floor. Similar for Africa. In other places they have head rests, but they're solid wood.\n\nIt is more comfortable to most people, but hardly a necessity.",
"We did this to ourselves. Silly humans. We are actually designed to lie flat on our backs, like our stone age brothers and sisters. Certain European (mostly) civilizations began using elevated beds, to keep away from rats and the like, who had decided that these new big cities the humans were building were a great place to chill and eat our food. These were made of stone or wood and were soon dressed with cushions, because wooden beds suck ass.\n\nHowever, sleeping on a cushion/mattress is not as comfortable lying flat on you back, as more of your spine gets called in to take the load, whereas on a solid surface your lower back is told to chill and leave it to your butt and them monster muscles you have either side of your upper back.\n\nThis meant that it was now more comfy to lie on your side, leaving the load of your awesome self to your shoulders and your gluteus medius (side butt hehehe). This was good for the spine but your neck got peed off that it now had to support your big bobble head... So pillows...\n\nThis is how we were told it in school, but my friend Larry has since informed me that the illuminati own the pillow making factory and put stuff in our food to make our heads weigh more.",
"My dog likes to sleep on his side with a pillow. Is he doing it wrong? Should I hit him?",
"Also: what do sleeping chimps look like?",
"We are smart enough to create and use pillows. What more reason do you need?",
"One of the main reasons we use pillows has to do with the complicated relationship between our heads, necks, and spines. When a person is walking upright during the day, the head and neck are held in vertical alignment over the spine by a complex arrangement of muscles and tendons. During sleep, however, many of these muscles relax, causing the head to fall backward or forwards. This places additional stress on the neck muscles and vertebrae, which in turn triggers stiffness in the back muscles and spine.\n\nThe solution to this painful situation is to elevate the head and neck until they are back in alignment with the spine, regardless of sleep position. The easiest way to achieve this supported alignment is to use a pillow to achieve the proper angle. When the head, neck, and spine are back in alignment, a person should be able to breathe easier and have improved circulation.",
"Because our Alien overlords who spliced their DNA with Earth's primates existed in close to zero gravity, there fore our heads need to \"float\", so we compensate with soft elevated bags.",
"I remember a question on eli5 a while back about \"why do dogs and cats and other animals like being petted?\" The top answer was something along the lines of \"has anyone ever pet you? It's feels fucking amazing.\"\n\nI don't think there is a much deeper explanation other than it felt good, so we kept doing it...forever. ",
"I think it'smostly the softness, personally I usually sleep without pillow. started after a period whereI often had a sore back/neck, threw my pillow away from the bed one night when I had trouble getting to sleep, and the next morning I woke up without any soreness inmy neck. after thatwhenever I tried sleeping with pillow I woke up with a sore neck, but if I sleep without I wake up feeling fine. but if I sleep on a harder surface, like on a thin airmatress in atent, I do like to put a sweater or so under my head because of the softness, eventhough it will stillgive me somewhat of a sore neck.",
"Not sure if this is true, but this is what I've heard.\n\nAs babies we have large heads that lift are heads enough of the surface to give us a comfortable feel. As we get older our proportions change and without having something to lift our head off the surface, we get uncomfortable. I think the comfort has something to do with the straightness of the spine or something,",
"Lots of animals use a support of some kind. A [giraffe](_URL_4_) for instance uses it's body as a pillow.\n[Big cats](_URL_2_) often use body parts as pillows (thiers).\n\n[Apes](_URL_1_) [More apes](_URL_3_) [Even more apes](_URL_0_)\n\nI think it comes down to comfort and keeping your head away from critters while you sleep.",
"I think the only reason is that humans are used to it. I don't think they do anything great for your spine either. \n\nWhen I have a sprained or stiff neck I find it far easier on the neck to sleep without a pillow. I believe the ideal and recommended position to sleep in is on your back on a flat firm surface without any pillows. \n\nMy grandmother lived a spartan live without many luxuries and often slept on the floor without a pillow. Come to think of it, my grandma-in - law has her afternoon naps on a mat on the floor without a pillow. Both women are the strongest and hardiest women I've come across so far. (must add here even though it's OT: grandma - in - law has a full set of teeth with no dental work. She's over ninety. I'm in complete awe of her for that alone). ",
"I always feel guilty because I like a lot of pillows, but everything I see about proper sleep posture says to use only one or two small ones. I use like four. If I use only one or two, I sleep terribly. What's up with that?",
"I feel like I'm the only one who sleeps on their stomach semi routinely without a pillow. It is almost painful feeling to use a pillow on my stomach sometimes.",
"Why are you writing this as you are not human?",
"Our heads are bigger relative to the rest of our bodies, because our brains are more developed than most mammals. So our heads weigh more when we're lying down, especially on our sides. Hence the idea of a pillow for support.",
"I had this friend with enormous boobs who never used a pillow. I, on the other hand, have next to no boobs and always need a pillow.",
"One of my dogs enjoys a life of luxury and waits for me to put a pillow under her chin, then I do this and she plops down. :| Although she sort of thinks she's people.",
"animals also don't have toilets but they still poo. out species gets the benefit of being able to make tools for comfort. pillows are obviously one of those tools. ",
"My dog loves pillows, and head support. She has one of those beds from Costco with the wrap around fluff-bumper, and she loves to lay her head on it, tucked in with her blankie. If she isn't tucked in? She'll grunt and kick dramatically, so we know she can't get comfortable. \n\nShe know's what she likes.",
"Perhaps this is going to get buried, but I just wanted to point out that all the cats I've had whenever they can use a pillow, an actual pillow (MY pillow, to be specific)...\n\nI say this because everybody is saying \"cats and dogs don't use pillows because of their anatomy\", but from my own experience, they seem to enjoy the extra support, just like us humans... \n\nI have no answer for you, unfortunately, I clicked on this 'cause it piqued my curiosity...",
"What's the deal with needing to put hands in-between the head and pillow?",
"Wtf are all these answers? I felt I had bad posture so I decided to sleep flat one night and felt great the next day. I don't use a pillow and feel way better about it.\n\nThe key is your head is soft so you need a soft mattress (memory foam) so you arnt point loading. Lots of people lean forward but that is bad posture - straight back seems and feels better for me.",
"FWIW, I didn't have a usable pillow for a summer and slept fine, then when I returned home to my pillow, it took getting used to again.",
"Human here I don't like my pillow when I sleep. I would rather sleep with a very thin pillow or no pillow",
"Maybe because our necks are slant and not straight?\n\nwelll... sometimes i use my pillow just behind my neck, and i still fell comfortable :D",
"If other animals had the ability to manipulate their environments the way that people do they would probably make pillows too. My dog uses pillows that i give to her. In the wild they flatten grass in a circle. Birds make nests. It is a matter of ability to make cushions that are comfortable for your body design. Every animal does the best that it can.",
"Our family owns/operates a mattress store so I have access to great pillows at cost. I've owned nearly 20 different high quality pillows. Some good ones and some not so good ones for my sleep style. \n\nI think my current pillow is just about perfect for my sleep style and it definitely improved my sleep quality.\n\nMy wife says we like pillows because we start out sleeping on boobs :-/\n\n/u/Vegesus44 has the best answer.",
"We have larger brains relative to our body proportions. If we lie on our back without some sort of support, our big heads force our spine out of alignment"
]
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"http://static.neatorama.com/images/2013-05/baby-giraffe-sleeping-2.jpg"
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|
4c0c7r
|
what percentage of ticket sales in movie theaters go to studios and when do they start profitting from a certain film?
|
Mainly, my question is concerning when and how studios move into profit on a certain film. For example, Batman v Superman is expected to take in $350 million worldwide (around $150 million domestically) this weekend, but I cannot imagine all of it goes to Warner Bros. Or does it?
I know that it probably is different in every country, so my question is primarily concerning the US, though I would appreciate it if you shared any knowledge about other countries.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4c0c7r/eli5_what_percentage_of_ticket_sales_in_movie/
|
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"Quite a lot. First the cinema will take a cut to pay expenses, which depends on all different things. The money left after in-house expenses will then be divided between the cinema and the studio. The split will depend on what has been negotiated, but from memory the studio usually takes 80-90%.",
"Someone please correct this if it's completely wrong, but as far as I know rule of thumb is that a movie should gross twice its budget to break even.",
"Theatres make their money primarily off concessions. Movie ticket money barely goes to them!",
"A movie theater and studio will work out agreements on a per movie basis for revenue sharing. Many factors can go into these negotiations, such as how well the movie is expected to do or how long it may play. Typically the theater will get a flat fee plus a percentage of every ticket sold. The percentage is usually a sliding scale, less in the beginning, and more the longer the movie plays, the goal is that over the engagement of the film the studio and theater will each get about 50% of ticket revenue.\n\nSo for a film like BvS, Warner Bros. will probably be getting all or most of the ticket revenue this week. If the bad reviews and word of mouth cause it to drop more than expected, the theaters may renegotiate for a bigger portion of the ticket sale.\n\nThis is why theaters have such huge markups on concessions.",
"I worked as a sales/booker for a major film distributor from 1990 to 1992 before moving on to work in development. I left the film biz completely in 2003, but it's likely that film rental agreements haven't changed much, if at all.\n\nFilm rental (what theaters pay to the distributor) is high. In the first several weeks with a new release, it is at least 70% of ticket sales and can reach 90% if a threshold amount of ticket sales is reached. This is called a \"90/10 deal\" and at the time I was doing this, it was standard. Big hit movies would often hit those 90/10 thresholds for a couple weeks before grosses dropped and the rental would be 70% for another several weeks.\n\nAfter the first several weeks of release, film rental begins to drop (also, grosses drop - films nearly always do best when they are first released, especially films released to many theaters, known as a \"wide\" release). \n\nBy the time a film is \"coming off\" a lot of theaters, the film rental is typically down to 35% of ticket sales.\n\nWhile the 90/10 deal sounds crazy to laypeople, it makes economic sense for the theaters, because they only hit those thresholds when *edit: at least some* showings are either sold out or close to it. That means lots and lots of concession sales, where their margins are high. It also means that if they do sell out Star Wars, some people are going to buy a ticket to see something else, because they've come to the theater anyway. \n\nIt was an interesting job for about the first year!",
"Studio gets 50%, Distributor take the other 50% to split with the Exhibitor. The Distributor is typically also the studio nowadays, so the Studio/Distr gets about 90% of it. \n\nThe theatre is in all likelihood losing money on the film itself."
]
}
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[] |
[] |
[
[],
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|
a7ny7j
|
why do some cities have enough allotted phone numbers (based on area codes) for 10x their population?
|
Houston has ~4 million residents, and now has 4 area codes. Each area code has 10,000,000 number possibilities, so Houston theoretically has 4 million people and 40 million available phone numbers. Why the massive jump?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/a7ny7j/eli5_why_do_some_cities_have_enough_allotted/
|
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"Well, there's a couple reasons for this. One is that not all phone numbers are valid.\n\nFor example, any number of the form XXX-555-01XX is reserved for directory assistance and information numbers. Certain businesses or universities might also buy as a block entire sets of numbers, so that all the numbers that with the same XXX-XXX numbers call the business.\n\nSo if I only have 30 phones in my business, but I buy all 304-218 numbers, I've blocked out a thousand numbers by myself.\n\nAlso, some people have multiple phones. So even though it only has 4 million people, it probably has ten or fifteen million phones.",
"Those area codes server the Houston \\*area\\*, not just within the city borders. You also have to consider cell phones, home phones, office phones, call centers, business lines, etc. Overall, there are more phone numbers used than there are people. You also have to have numbers available for pre-paid phones and other temporary numbers. You don't typically make a phone number available immediately when someone cancels an existing number, so you are always going to need extras. Many phone numbers are reserved by the phone company and not available for use."
]
}
|
[] |
[] |
[
[],
[]
] |
|
jekak
|
Would it be possible for a large/dense enough planet to have a Sun orbiting it?
|
And if so, would said sun be warm/large enough to effectively warm the planet to the stage where life could exist?
|
askscience
|
http://www.reddit.com/r/askscience/comments/jekak/would_it_be_possible_for_a_largedense_enough/
|
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"Not an astronomer, but AFAIK: A planetary object, by definition, is something not massive enough to sustain fusion and thus being a star. So a planet should *never* be more massive than a star. ",
"Theoretically it should be possible, but I can't imagine a scenario in which the initial conditions would be such that it could take place. \n\nAs other people have mentioned, a planet that is more massive than a star should, in fact, sustain fusion. However, if the planet was composed of material \"further along\" the periodic table than iron, fusion would not take place in the planet's core. Then, a star could form out of fusionable material, and orbit the massive planet. \n\nHowever, solar systems are formed out of big disks of rotating mass, and like a centrifuge, the more massive atoms are more likely to be located closer to the edge of the disk, with the lighter material closer to the center. This causes a problem with the above scenario, because we want the dense material to be collected in the center of the disk. \n\nA different option is as follows. Normally the idea of a planet orbiting a star is a pretty clear cut picture, because the star is so much more massive than the planet, that the planet's orbit does not cause the star to move very much. However, any time something is in orbit, it isn't actually orbiting the center object, both objects are orbiting the center of mass of the system. However, in the case of the Earth/Sun system, the sun is so massive that is is a very good approximation that the center of mass of the system is at the center of mass of the sun. However, Jupiter is massive enough (and far enough away) that it does, in fact, cause a very minor wobble to the Sun, and Jupiter could be ~~100,000~~ 1000 times more massive before it would become massive enough to sustain fusion. So imagining a really, really massive planet (maybe ~~90,000~~ 900 times more massive than Jupiter) that is on the verge of fusion but not quite there, it could appear as if the sun and planet are binary and the general notion of the planet \"orbiting\" the star might not make sense. \n\nAll of that being said, I can see no reason the star wouldn't produce enough heat to warm the planet, should one of these situations arise. \n\n**Edit:** I realized I was off by 10^3 in my statements about the mass of Jupiter. Corrected above. Sorry about that. ",
"Yes. But probably not in the way you are thinking.\n\nTake a binary star system, with regular planets orbiting star A, and then in a very large orbit, star B orbiting all of them. B does in fact go around the planets. You might argue that B is actually going around A, but that's not quite true - B goes around the barycenter of A + B + planets. If the barycenter is displaced far enough from A it might be closer to the orbit of one of the planets than anything else.\n\nFrom the day-to-day perpective of one of these planets, A is the dominant star in the sky, however, not B.\n\nOf course none of this has to do with the density of the planet, so it's not really the case you were thinking of.",
"Not an astronomer, but AFAIK: A planetary object, by definition, is something not massive enough to sustain fusion and thus being a star. So a planet should *never* be more massive than a star. ",
"Theoretically it should be possible, but I can't imagine a scenario in which the initial conditions would be such that it could take place. \n\nAs other people have mentioned, a planet that is more massive than a star should, in fact, sustain fusion. However, if the planet was composed of material \"further along\" the periodic table than iron, fusion would not take place in the planet's core. Then, a star could form out of fusionable material, and orbit the massive planet. \n\nHowever, solar systems are formed out of big disks of rotating mass, and like a centrifuge, the more massive atoms are more likely to be located closer to the edge of the disk, with the lighter material closer to the center. This causes a problem with the above scenario, because we want the dense material to be collected in the center of the disk. \n\nA different option is as follows. Normally the idea of a planet orbiting a star is a pretty clear cut picture, because the star is so much more massive than the planet, that the planet's orbit does not cause the star to move very much. However, any time something is in orbit, it isn't actually orbiting the center object, both objects are orbiting the center of mass of the system. However, in the case of the Earth/Sun system, the sun is so massive that is is a very good approximation that the center of mass of the system is at the center of mass of the sun. However, Jupiter is massive enough (and far enough away) that it does, in fact, cause a very minor wobble to the Sun, and Jupiter could be ~~100,000~~ 1000 times more massive before it would become massive enough to sustain fusion. So imagining a really, really massive planet (maybe ~~90,000~~ 900 times more massive than Jupiter) that is on the verge of fusion but not quite there, it could appear as if the sun and planet are binary and the general notion of the planet \"orbiting\" the star might not make sense. \n\nAll of that being said, I can see no reason the star wouldn't produce enough heat to warm the planet, should one of these situations arise. \n\n**Edit:** I realized I was off by 10^3 in my statements about the mass of Jupiter. Corrected above. Sorry about that. ",
"Yes. But probably not in the way you are thinking.\n\nTake a binary star system, with regular planets orbiting star A, and then in a very large orbit, star B orbiting all of them. B does in fact go around the planets. You might argue that B is actually going around A, but that's not quite true - B goes around the barycenter of A + B + planets. If the barycenter is displaced far enough from A it might be closer to the orbit of one of the planets than anything else.\n\nFrom the day-to-day perpective of one of these planets, A is the dominant star in the sky, however, not B.\n\nOf course none of this has to do with the density of the planet, so it's not really the case you were thinking of."
]
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|
[] |
[] |
[
[],
[],
[],
[],
[],
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] |
|
4kzlyh
|
When looking for life, why does it HAVE to be in the Goldilocks zone? Are we that closeminded to think ET organisms couldn't thrive in what we'd call completely unsurvivable conditions?
|
[deleted]
|
askscience
|
https://www.reddit.com/r/askscience/comments/4kzlyh/when_looking_for_life_why_does_it_have_to_be_in/
|
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"The universe is a big place, we have to narrow down the search somehow. Since we have one and only one example of life so we narrow the search down to areas that match the conditions where we already know life can exist. Could we be wrong? Perhaps. But we are not closed minded we are taking the best available evidence and applying it to the search so the limited resources we have are hopefully more productive. Until we find life a second time that's the best we can do. It doesn't mean we aren't looking outside Goldilocks zones and if we find life outside them we will ignore it, we just are not concentrating our search outside those areas because there it too much outside that area to make any search productive.\n\nThis is just like finding a lost hiker. You know he went into the woods. Its best to search those woods first and most thoroughly before moving on to other areas. The likelihood of him being found on a beach in Mexico is possible, but much less than him being in the woods where he was last seen. Doesn't mean he didn't flee to Mexico but rescuers have limited resources and have to start with the most likely scenario. Right now the most likely scenario is that life requires the conditions found in Goldilocks zones.",
"The Goldilocks zone is really only a guide to help focus the search for extraterrestrial life. It isn't necessarily a comprehensive predictive tool and it operates with a fixed set of assumptions. Of course there is a lot of potential territory which is deliberately left out, it is by definition restrictive rather than inclusive and that is sort of the point, the search for extra terrestrial life is a winnowing exercice - the less worlds we have to look at the better our chances.\n\nTake the case of our own solar system: the goldilocks zone stretches from somewhere around the veneran orbit to about Mars. Yet some of the most promising areas where life might exist in the solar system are tidally-driven hydrothermal vents in the oceans of ice moons in the saturnian and jovian systems. These are well out of the goldilocks zone, and somewhat independant of it, because the ecosystems which might exist there are completely disconnected from photosynthesis. However, the thick ice crust and absence of atmosphere of such environments make them unamenable to long distance investigation and we must thus ignore them in our search for life outside of our solar system. \n\nBut it doesn't mean that they should be forgotten.",
"It's where life *as we know it* will most likely be. Yes, sure there could be crystal monsters out on an icy Neptune-style planet... but at that point we don't even know what we'd be looking for. So we take the easiest path (for now).",
"Close minded may be a stretch. Life requires certain molecule mechanics. The ability to build long molecular chains etc...\n\nWater/carbon and ammonia/silicon fit these requirements at certain temperatures.\n\nCould there be more exotics forms of life? Sure, anything is possible. But with no evidence that is firmly the realm of faith, science has nothing to do with it.",
"Life is a chemical process. And as a chemical process it's bound by certain conditions. \n\nOne is reaction rate. Simply put, chemical reactions happen extremely slowly at low temperatures. Life depends on hundreds of thousands of reactions all taking place simultaneously, and if you're at a temperature such that a ligand x will only bind to enzyme y on average once per thousand years, you've got a problem. Your star is going to burn out before you can get very far. \n\nSo there's some lower bound on temperature, but there's also an upper bound. One of the fundamental properties of life is storage and replication of information. For this you need large molecules - small ones will be overwhelmed by entropy. And most large molecules simply get battered to pieces once the temperature gets high enough. \n\nSo there's a goldilocks zone. It's not based on liquid water, or DNA, or carbon-based proteins, just simple realities of chemistry. \n"
]
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|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
4jrio0
|
What happened to Manichaeism?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4jrio0/what_happened_to_manichaeism/
|
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"It was persecuted in Persia. Mani was either executed or died in jail; in Persia it was seen as a competitor of the Zoroastrian religion, and the Zoroastrian priesthood persecuted it into oblivion. See Will Durant's book, THE AGE OF FAITH.\n\nIn Central Asia, it had better luck. EMPIRE OF THE STEPPES says that the Uighur Turks adopted it as a state religion. The Uighurs, developing a high degree of civilization, propped up Tang Emperors after the An-Shi Rebellion. The Chinese Emperors let Manicheans preach in China. But after the Uighurs got smashed by the Kirghiz, who were uncivilized Turks from the Siberian forest, the Chinese turned on them persecuted the Manicheans into oblivion. \n\nThe Chinese, it would seem, had come to resent their dependence on Uighur support, and saw the religion of Mani as an unwelcome intrusion. \n\nIt is said that Mani's ideas were behind the Bogomil heretics in Bosnia, the Paulician heretics in Anatolia, and the Albigensians of Southern France. All these groups were persecuted by Christians or absorbed by Islam. \n\n I do not know if they really were Manicheans, and would like to see people here discuss these movements. I think that in the long run, Mani's religion had nothing that could compete against Islam and Christianity; and Buddhism was more attractive in the East Asian region. "
]
}
|
[] |
[] |
[
[]
] |
||
1v5aow
|
Probably not the correct subreddit for this, but I need help finding primary sources or paintings involving Native Americans.
|
For a history project, we had to create a question having to do with communication between Europeans. Africans, and the Americas, and my question was about Native Americans (Can't actually say my question because they are later being checked of plagiarism. I need sources that show how Native Americans thought of Africans and Europeans. The source can be a table, a primary document, and painting, etc. If this is not the correct subreddit, please just comment which one I can ask this question to. Thank you.
P.S I am not just asking this out of laziness, I have been searching all around the web and so far could only find two decent sources. Thanks.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1v5aow/probably_not_the_correct_subreddit_for_this_but_i/
|
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"I suggest looking up the diaries of James Cook's around-the-world voyage. They are public domain and should be scattered around the Internet. ",
"I recommend getting a copy of Colin Calloway's [The World Turned Upside Down](_URL_0_), which is an anthology of colonial era Native writer. Many of the authors describe their community's initial reactions to the arrival of Europeans or their assessment of European religion and society. The book is mainly focused on the eastern half of North America. For the Plains, he also has [Our Hearts Fell On the Ground](_URL_1_).",
"Thanks for all the help guys."
]
}
|
[] |
[] |
[
[],
[
"http://books.google.com/books?id=9LanQgAACAAJ",
"http://books.google.com/books?id=DSRhE9bB1M4C"
],
[]
] |
|
cy0zie
|
During the American Civil War in the United States Military was there a particular group of people who were tasked with treating, protecting, and or removing their fellow injured soldiers, in the way a combat medic is typically depicted in more recent history?
|
Two of my all time favorite things are combat medics and civil war history. I know both sides had medical staff, surgery professionals and makeshift hospitals to treat the injured, but was there anyone who was expected to protect and remove the injured during a battle? If so did they have any special tile or markings? Or was this procedure handled simply by any soldiers who found themselves in a position where this was necessary, combined with a general respect for injured men on both sides?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/cy0zie/during_the_american_civil_war_in_the_united/
|
{
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"text": [
"My main source will be McPherson's Battle Cry of Freedom. Unfortunately, I don't have access to specialized sources that deal only with the medical aspects of the Civil War, but McPherson's book should provide enough information to answer your question. \n\nAccording to him, \"Traditional practice in both armies assigned regimental musicians and soldiers \"least effective under arms\" as stretcher-bearers to carry the wounded from the field and assist the surgeons in field hospitals.\" However, he goes on to say that those men were not really useful, usually running away in terror and not having the resources necessary to carry away all the wounded to safety. The fact that the Army was awfully small previous to the war did not help matters. It had grown tremendously during the war, and with it the number of casualties as well. As a result, simply impressing drummer boys and ineffective soldiers into being \"combat medics\" would not be enough. They lacked the training and morale to carry out their work effectively. \n\nCivilians helped as well in many ways, volunteering to go to the front to carry away the wounded to Army hospitals. But some of them were \"worse than useless\". For example, after the Battle of Second Manassas, a contingent of volunteers arrived to the scene already drunk, and they bribed the ambulance drivers to take *them* back to Washington, instead of taking the wounded men. Under such circumstances, the soldiers had little faith in the Army medical services, and they often broke ranks to carry comrades to the hospitals, knowing that no one else would. After battles, a common practice was to organize a temporary truce where the soldiers would go for their wounded companions, and then bury the fallen.\n\nIt was clear that change was necessary. Fortunately, when men failed to step up to the challenge, the women stepped forward. Many women created different associations to provide relief and supplies to the fighting men. In April 29, 1861, a reunion in the Copper Institute of New York created the Women's Central Association for Relief, in order to coordinate and expand the scope of these associations. The association would eventually become the U.S. Sanitary Commission, inspired by the work of Florence Nightingale and the British Sanitary Commission during the Crimean War. The Army Medical Bureau at first opposed such efforts, and Lincoln was skeptical, but he did sign the order that created the Sanitary as an official body. \n\nWe can say a lot about the brave efforts of the nurses recruited by the Sanitary and their herculean labors in favor of the soldiers, but when it comes to your question the important fact is that the Sanitary pushed for reform in the ambulance system. Jonathan K. Letterman became the medical director of the Army of the Potomac after the Seven Days, and he created a dedicated Ambulance Corps that had the duty of evacuating the wounded men in the middle of battle. Unlike the previous volunteers and soldiers, these men were trained and had high morale, which they needed, because going into the battlefield to evacuate the wounded was a dangerous task. The system quickly spread from the Army of the Potomac to other Union armies, until it was mandated by an 1864 law. \n\nThe Confederates, for their part, also created a similar system, the Infirmary Corps. But they did not have the resources in either quality or quantity. Nonetheless, they matched their Union counterparts in valor, and maybe surpassed them in improvisation and creativity. \n\nAside from these specialized corps, both sides still needed to recruit volunteer nurses to help the wounded or organize truces so that soldiers could rescue their comrades. Clara Barton, an exceptional woman who took part in this war and in the Franco-Prussian War and would later help create the American Red Cross, related the horrific scenes that took place after the battle: \"By midnight there must have been three thousand helpless men lying in that hay. . . . All night we made compresses and slings—and bound up and wet wounds, when we could get water, fed what we could, travelled miles in that dark over these poor helpless wretches, in terror lest some one's candle fall into the hay and consume them all.\" Similarly, during the Overland Campaign, more specifically the initial battles of the campaign in the Wilderness, the fighting died down because soldiers sought to rescue their wounded from the forest fires started by the artillery. \n\nSo, to summarize, there were special units tasked with protecting the wounded and taking them to Army hospital as fast as possible, the Ambulance Corps in the Union and the Infirmary Corps in the Confederacy. At least in the Union side, they wore special uniforms and had their own [badges and banners](_URL_0_). Nurses of the Sanitary Commission or volunteer civilians helped to evacuate the men as well, and organizing truces to rescue the wounded was a common practice, especially after particularly hard-fought battles. \n\n**Sources:** As I said, I took this mostly from McPherson's *Battle Cry of Freedom*. In his biographical note, McPhersons recommends William Q. Maxwell's *Lincoln's Fifth Wheel: The Political History of the United States Sanitary\nCommission*, as a source for the Sanitary Commission and their labor for the Union. I haven't read it personally, but I suppose it can give you a greater insight if you want to go deep into the topic."
]
}
|
[] |
[] |
[
[
"https://c8.alamy.com/comp/KH56X7/ambulance-corps-banner-belonging-to-the-army-of-the-potomac-national-KH56X7.jpg"
]
] |
|
29a55b
|
if russia is so lawless and corrupt what are scammers actually gaining by jumping in front of cars pretending that they were hit?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/29a55b/eli5_if_russia_is_so_lawless_and_corrupt_what_are/
|
{
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"text": [
"Russia really isnt as corrupt and lawless as you seem to think it is",
"Wow, anti-russian propaganda does its work pretty well"
]
}
|
[] |
[] |
[
[],
[]
] |
||
4flmpt
|
How can polar regions of Venus measure -157°C when the average temperature of the planet is 462°C?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4flmpt/how_can_polar_regions_of_venus_measure_157c_when/
|
{
"a_id": [
"d2a7s16"
],
"score": [
9
],
"text": [
"I think you got something wrong. I never hear bout the poles being cold.\n\n > Temperatures are cooler in the upper atmosphere, ranging from (minus 43 C) to (minus 173 C).\n\n--\n\n > The lack of significant tilt causes only slight temperature variations from the equator to the poles, as well.\n\n\n_URL_0_"
]
}
|
[] |
[] |
[
[
"http://www.space.com/18526-venus-temperature.html"
]
] |
||
2yswtg
|
What was the international reaction to the famine deaths in the Ukraine during the Holodomor and China during the Cultural Revolution?
|
Was there one? Were there food drives in the US and Western Europe to send food/money? I would guess no, the world seems to be a lot less global then, but I'd love to find out.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2yswtg/what_was_the_international_reaction_to_the_famine/
|
{
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"cpehjmm"
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"text": [
"(speaking about the Holodomor exclusively here)\n\nThere were some attempts to provide international aid, though nothing led by Western governments themselves. A letter written by Laurence Collier of the British Foreign Office specifically states that the government had “a certain amount of information about famine conditions,” but “[did] not want to make it public, however, because the Soviet government would resent it and our relations with them would be prejudiced.” The American government at the beginning of the famine did not yet have formal diplomatic relations with the Soviet Union, and were likewise being very careful. \n\nThe reactions of everyday people were influenced by the fact that the stories coming out of Russia were often contradictory. Some reporters, like Walter Duranty, denied that a famine was even taking place. The news was alarming enough, however, that many people in the U.S. (especially Ukrainian immigrants) tried to appeal to the government to supply aid. In Austria, Theodor Cardinal Innitzer set up an International Relief Committee, working with Dr. Ewald Ammende. J. H. Rushbrooke of the British Free Church Council is described in contemporary accounts as taking a “leading role in international relief activities after the 1933 famine,” as well. A note from the British Foreign Office shows that Rushbrooke was involved in a “Torgsin parcels scheme,\" a type of relief effort supported by the United British Appeal organization. \n\nTorgsins were “trade with foreigners” stores that existed from 1931-1936. They accepted foreign currency or valuables in exchange for bread and other goods, and provided a way in which the Ukrainian diaspora could assist their family members back home. This method was utilized by Ukrainians of Mennonite and Jewish descent in particular. While the Soviet government rejected other forms of international aid, they welcomed hard currency as a resource to drive industrialization. \n\nIf you’re interested, there was a commission formed to investigate the Ukrainian famine in 1985… the full text is available online and contains some testimony from people who lived through it: _URL_0_\n"
]
}
|
[] |
[] |
[
[
"http://babel.hathitrust.org/cgi/pt?id=mdp.39015014630530;view=1up;seq=7"
]
] |
|
3uk1vc
|
what good would a gun owner registry do in preventing crime?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3uk1vc/eli5_what_good_would_a_gun_owner_registry_do_in/
|
{
"a_id": [
"cxfi70i"
],
"score": [
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"text": [
"It really wouldn't prevent crime. In some cases it might help solve crimes. If you look at Australia they had a mandatory gun registry and told everyone if they registered their guns they'd be grandfathered into compliance. When it didn't help crime they used the registry to confiscate guns from those who registered them."
]
}
|
[] |
[] |
[
[]
] |
||
q4u8b
|
what is "irreducible complexity" in regards to the theory of evolution?
|
I've read a few things but still don't think I get it.
1. What does the term originate and what does it mean?
2. Why do creationists use this as "proof" against evolution?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/q4u8b/eli5_what_is_irreducible_complexity_in_regards_to/
|
{
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"text": [
"One of the main ideas of evolution is that small changes add up, resulting in big adaptive changes over time. For instance, fish using fins to crawl across land to new mud puddles, fins get bigger, blablabla legs. \n\nIrreducible complexity is saying, \"Well how would a creature incrementally evolve a wing? Half a wing won't help you fly, so it never would have been selected for in the first place. And what about an eye? 'Half' an eye is completely useless, so obviously a creature born with half an eye would not be selected for by evolution.\"\n\nSo, its saying that things like eyes and wings are \"irreducible complexity.\" That is, they cannot be any 'less' and still have function. The conclusion being that incremental changes, as theorized by evolution, would never result in their existence.",
"I love the idea of a five year old asking this. I can't even say it out loud.",
"Irreducible complexity can be explained with a simple mechanical clock. Remove one cog from its interior and it will stop working. This means that the clock will only work as a clock if all the parts are there. Its design is so precise that if you remove something it will stop working.\n\nCreationists use this as proof against evolution on the premise that life is irreducibly complex, that life is like a clock with a special purpose and if you mess the slightest thing up, it will stop working. What they don't do is prove that life is irreducibly complex, they just assume it as a fact.\n\nI see life more like a cake. In the beginning it was made up of water and flour. Then by chance some salt and baking powder was added and made it into a fluffy dough. Later on sugar, whipped cream, jam/jelly, and toppings were added, by chance. And as time went on, what began as a simple dough slowly becomes what we know as a cake.\n\nWhat creationists do is that they look at the cake in it's current state and say: \"That cannot have been made by chance, it must have been designed from the beginning, see when you remove the bread/cream/water/flour/sugar/half the cake it is not a cake anymore.\" Evolutionists say: \"That is true, but it still is food.\"",
"It isn't related at all to evolution. Irreducible complexity is an idea one intelligent design proponent came up with to say that evolution can't explain certain organs, like the eye. It's a flawed argument for a number of reasons and doesn't belong in any serrious scientific discussion.\n\nHowever.\n\nA guy named Michael Beoh (can't remember how to spell it) explained it by saying that certain things don't work if one piece is missing. A mouse trap, for example, needs all of its parts to work. He used this show that evolution cannot _URL_0_ gradual changes how the blood clot cascade, bacterial flagella, and eyeballs could not be explained by evolution. They were irreducably complex.\n\nThis is flawed logic. It's also a negative argument for evolution, and not a positive argument for intelligent design. No scientific journal would publish it. No one gave it any peer review. Finally, the whole idea was publicly humiliated by actual scientists and biologists in the very public Kitzmiller v. Dover Area school board case about teaching evolution in public school. There is a great Nova documentary about it and I strongly recommend it.",
"Evolution explains how things evolved gradually...starting with simple forms and becoming more complex. It is an unguided process without a plan...little changes help an organism survive, then added up to big changes later. \n\nSo if you have a complex biological structure, you should be able to \"play it backwards\" to its simple form, with it serving a purpose for every step in between.\n\nIrreducible complexity is the claim some complex forms are irreducible...that is it impossible to for them to have arisen from simple forms while serving a purpose during the intermediate steps. A mousetrap is a common analogy. Take away any one part, and it no longer works. Clearly, a mousetrap was designed by some intelligence, rather tan arising by chance.\n\nThe IR advocate would claim that there are biological structures that are similarly irreducible, which proves they were also designed.\n\nThere are a number of problems with this argument:\n\n* Just because it isn't clear how a complex system can be reduced don't make it irreducibly complex. Many features, such as eyes and blood clotting factors, have been proposed to be irreducible, but turned out not to be.\n* Even an irreducibly complex system can arise from other systems with different functions. A mousetrap without a trigger could be used as a clip, a nutcracker, or a tiny catapult. Just because a system has a function now doesn't mean it always served that same function.\n\nIR is regarded as an unscientific, ad hoc criticism of evolution holding little merit. "
]
}
|
[] |
[] |
[
[],
[],
[],
[
"explain.by"
],
[]
] |
|
1y5mhv
|
reddit's "we took too long to make this page for you" error message.
|
You know, [this one](_URL_0_).
At first glance, it seems like a bad user experience to say the equivalent of "we failed, try again" when you could easily automate the trying again or increase the timeout.
Does anyone understand why they do it this way?
Edit: amusingly enough, I got that error when I first loaded this question after posting it.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1y5mhv/eli5_reddits_we_took_too_long_to_make_this_page/
|
{
"a_id": [
"cfhjqqu"
],
"score": [
2
],
"text": [
"The general idea is \"Okay, this should have taken THIS long. It's gone far past that, and it's tying up the system, get rid of it.\" \n\n1. Stop doing what you're doing. This frees up resources.\n2. Tell the user you gave up, and tell THEM to do it again.\n\nIf the system just tried again, the requests would just keep on coming. Even buying the servers a half second could make the difference, so putting the need to re-request on the user is a safety mechanism.\n\nExtending the timeout just means the servers can get stuck dealing with the traffic longer, and maybe still not succeed. Gridlock.\n\nAnalogy Like You're Five: It's a traffic jam. You're supposed to look out the window and say, \"I'll wait a few minutes before trying to drive in that mess.\""
]
}
|
[] |
[
"http://i.imgur.com/d2kDLcR.png"
] |
[
[]
] |
|
49c58k
|
why can't we just make the face value of a penny 2.5 cents?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/49c58k/eli5_why_cant_we_just_make_the_face_value_of_a/
|
{
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"d0qmoox",
"d0qnyzm"
],
"score": [
3,
29
],
"text": [
"We already have a five cent coin. There's no need for a 2.5 cent coin as well. ",
"You hear a lot about this as though the cost of the penny is huge issue - but it's not. A penny is not single use. Coins stay in circulation on average 25 years which which is more than enough time to cover that manufacturing cost. \n\nWhen we talk about saving money by getting rid of the penny it has more to do with all the handling costs associated with it. If a coin is only used for making change (you can't buy anything with a single penny anymore) then it's more trouble than it's worth."
]
}
|
[] |
[] |
[
[],
[]
] |
||
tryh0
|
Could the effects of a Taser on a person be neutralized by conductive clothing?
|
I have to admit, I was tempted to just try this one out and shout "for science" before getting zapped, but I feel that askscience is a better way to start. Just as the title asks, could the current running between two taser prongs be transferred through clothing made of a conductive substance? It may come down to if the electrodes are coated after a certain "depth" so that the current moves from tip-to-tip of the barbs.
Thoughts?
|
askscience
|
http://www.reddit.com/r/askscience/comments/tryh0/could_the_effects_of_a_taser_on_a_person_be/
|
{
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2
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"text": [
"The concept has been [patented.](_URL_0_)\n\nI saw a video of a demo a couple of years ago; supposedly it works.",
"Better still: could something be worn that would cause a taser-wielder to be the one to get shocked?"
]
}
|
[] |
[] |
[
[
"http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=7,284,280&OS=7,284,280&RS=7,284,280"
],
[]
] |
|
2xw5b4
|
What do we know regarding Hermes Trismegistus, Hermeticism and the Emerald Tablet?
|
I tried Wikipedia and it just says that Hermes is "purported" to be the author Hermetic Corpus.
Did this mysterious figure actually exist and he/she start/founded Hermeticism?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2xw5b4/what_do_we_know_regarding_hermes_trismegistus/
|
{
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"text": [
"There is no evidence whatsoever that there was ever a person named Hermes Trismestigus, and definitely not in the form in which Hermetic writings present him.\n\nAs for the Corpus Hermeticum itself, it dates from Alexandria around 200 AD, and represents a kind of cultic strain of Neoplatonic mysticism.\n\nIt first enters Europe - as the 'Emerald Tablet' - with the translation of the Secretum Secretorum by the \"Aristotle by the Doctor\" in the thirteenth century as part of the wave of translations from Arabic. \n\nThis amazing book, constructed as an epistolary exchange between Alexander the Great and Aristotle, was thought - by, for example, Roger Bacon - to contain the 'secret teachings' of Aristotle which enabled Alexander to conquer the world through various magical means. Alexander, in a motif that would subsequently repeat itself in the history of occultism, is described 'finding' the tablet in an ancient tomb. Through the Secretum Sectorum, it circulated Europe, inspiring magicians and alchemists, but without any evidence that I am aware of, of instigating \"Hermeticism'' as such.\n\nThe underlying idea that Hermes was extremely ancient, possibly the teacher of Plato, or perhaps even Moses, or Zoroaster, was in line with the notion that the world was 6,000 years old, as the Bible clearly shows. Furthermore, because of course the most important thing that ever happened in the world was Christianity, there was a thought that there was something like a \"prisca theologia\" containing in outline the shape of the Revelation to come, which inspired ancient sages, being inspired by God, had foreseen. \n\nTypically, this kind of proto-historical thinking only really begins in the Renaissance - that is, the beginning of the end as far as medieval Christianity was concerned.\n\nThe first place that you see it is Gemistos, aka Plethon, this very unusual neo-pagan philosopher whose life spans the last century of Byzantium, and who has the great historical honor of reintroducing Plato to Europe. But Plethon doesn't mention Hermes. The first time you find him is in Ficino, who translated 'the' Corpus Hermiticum after 'it' was found in a Macedonian monastery, and indeed broke-off translating Plato for it, because, the idea was, Hermes being older, Plato represented a continuation, and to some extent distortion of the original Hermetic message, when of course the truth was exactly the opposite. That truth became clear in 1600 when Isaac Causabon conclusively dated the Corpus Hermiticum to around 200 AD.\n\n"
]
}
|
[] |
[] |
[
[]
] |
|
2zr7j4
|
Chinese, Hindu, and Muslim civilizations produced great scientists but the Scientific Revolution owes to Europe. Why?
|
My question stems from this video I came across:
_URL_0_
Has historical analysis been conducted regarding this topic? It's very intriguing.
EDIT:
Thank you for the responses so far. How much historical truth is there to what Carl Sagan said in ep.7 of Cosmos when he compared the ancient Greek civilization and the modern European renaissance:
"“Ordinary people were to be kept ignorant,” Sagan says of the Pythagoreans’ work. “Instead of wanting everyone to share and know of their discoveries, they suppressed the square root of two and the dodecahedron.” And Plato loved the elitism and secrecy, equally, as he argues. Plato was hostile to the real world, experiments, practicality, etc."
_URL_1_
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2zr7j4/chinese_hindu_and_muslim_civilizations_produced/
|
{
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"cplrx2d",
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9
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"text": [
"Definitely. Perhaps the most famous discussion of this has been the [Needham Question] (_URL_0_), which essentially asked why did modern science develop in Europe and not in China, when any observer circa 1400 CE would not likely have pegged Europe as the future center of science, or technological advancement.\n\nI would say, that among professional historians, the question has largely fallen off the radar, but in the past it was the source of a great deal of historical debate and with most hotly contested issues, questions, or thesis, gradually historians turn away from them as the discussion devolves into attacks and debates over minutiae (kind of like many reddit threads- or debates in general). Ultimately there was never going to be a single, good answer, so eventually the debate was not really worth having.\n\nNeedham ended up concluding basically that China never stopped advancing- it did not stagnate, but was over taken when European science experienced an incredible flowering. According to Needham, it boiled down to culture. The culture of Europe promoted the sort of values that drove the Scientific Revolution.\n\nPerhaps nowadays the focus is more on the idea of a great \"divergence\" between Europe and China. This has been a topic written on extensively; perhaps the biggest western scholars to enter the field have been Kenneth Pommeranz \"The Great Divergence\", Parthasarathi \"Why Europe Grew Rich\" and Gunder-Frank \"ReOrient\" (and perhaps R. Bin Wong \"China Transformed). The focus in these studies is less on the development of science, than it is on commercial development, or the rise of European capitalism, as a unique transformation- and one very much linked to the types of patronage networks that develop during the Early Modern Period in Western Europe - the time and place of the Scientific Revolution.\n\nThough the video linked above does not mention it- I personally find it pretty hard to ignore the rise of colonial empires in conjunction with the scientific revolution and certainly the enlightenment in my own work.\n\nThe video itself isn't bad- it's very general- so maybe the sort of thing directed towards High Schoolers, or an Introduction to World History. Perhaps some of the biggest blindspots in it are a lack of context for why many of the non-European scientists came earlier than Europe, what connection some of them had to the scientific revolution in Europe, a clear definition of what he means by Europe (though notice nearly all of the scientists he mentions are French- a hint that this is predominantly a particular western European phenomena), and the assumption that the Scientific Revolution was really a \"Revolution\" or that common people really took part in it, or felt it in a dramatic way. Many of these are issues we might bring up in a little bit higher level class- or by means of some discussion of the video.",
"Indeed this question has been asked before. Essentially the conclusion that historians have come to is that this is the wrong question to ask. As another poster has mentioned, Joseph Needham was very important in stimulating this discussion.\n\nThe question suggests that \"the scientific revolution\", i.e. the changes in European natural philosophy approximately between the years 1400 and 1800, is the inevitable result of investigations into nature. The problem is that there's no evidence to support this assumption. The scientific revolution happened once, in one place and in one time. So we shouldn't ask \"why didn't the scientific revolution happen elsewhere?\", we should ask \"why did the scientific revolution happen when and where it did?\". [Here](_URL_0_) is a very good article by Nathan Sivin which may help to answer some of your questions regarding this point. He argues that China *did* have a scientific revolution around the same time as Europe; it's just that the social changes associated with the revolution in Europe did not take place in China. This leads him to examine the underlying assumptions hiding behind your question.\n\nThe kind of question we need to be asking about European science is: \"why did changes in the way professional scholars studied motion, medicine, and astronomy, grow to encompass all investigations into nature?\" The revolutionary part of the Scientific Revolution is its spread, the precedents established in physics and medicine were applied to the study of chemicals, of the Earth, of life, and now there are dozens of 'pure' fields and a myriad of interdisciplinary fields. What we need to understand is why this happened, and that's the thing that modern historians of science focus on.\n\nModern history of science has become more and more focused on individuals and events rather than century spanning ideals, which makes for good scholarship but poor popular literature. Contemporary historians of science shy away from macrohistories because the simplifications involved in making such a project manageable obscure the details that make the history accurate. We can tell a story about the pedigree of Western science running from Socrates to Antoine Lavoisier; the story of Chinese science is simply different. The scientific revolution is part of Europe's story, not China's.\n\nSivin, N 1985, 'Why the Scientific Revolution Did Not Take Place in China--Or Did It?', Environmentalist, vol. 5, no. 1, pp. 39-50."
]
}
|
[] |
[
"https://vimeo.com/91404092",
"http://www.tor.com/blogs/2012/12/exploring-carl-sagans-cosmos-episode-7-qthe-backbone-of-nightq"
] |
[
[
"http://www.oxfordbibliographies.com/view/document/obo-9780199920082/obo-9780199920082-0006.xml"
],
[
"http://web.nchu.edu.tw/pweb/users/hbhsu/lesson/8252.pdf"
]
] |
|
68edgg
|
why is all life on earth based on rna/dna ?
|
I often wondered why there aren't other life forms based on a different chemistery.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/68edgg/eli5why_is_all_life_on_earth_based_on_rnadna/
|
{
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"dgxv1bn",
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],
"score": [
4,
2
],
"text": [
"The simple answer is that it works so well. A system which works well has advantages of anything else. So there are more descendents using it than any other.\n\nOne interesting variant is mad cow disease and its relatives. This is not life as we know it but the proteins are copied. So the disease is propagated without using nucleic acid. ",
"Every macro level life form is related, since their common ancestor had dna/rna, so have they.\n\nWe don't know all microscopic life forms, so maybe some developed independently and aren't based on dna."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2zelid
|
(X-posted from r/Sailing) Why would a Spanish Galleon need such a large crew?
|
My research says crew sizes were at least a hundred men, often two, for a large ship such as a Spanish galleon. Why was this? What is the absolute minimum size a crew could be to get a galleon running? What did the crew do when they weren't at their stations, with a hundred and something men aboard?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2zelid/xposted_from_rsailing_why_would_a_spanish_galleon/
|
{
"a_id": [
"cpi74hr",
"cpimxjk"
],
"score": [
4,
2
],
"text": [
"For context, what time period are you referring to? It might make a difference. \n \nBut, my initial thoughts are: \n* Men brought on for defense against attackers (security in modern terms) \n* Depending on the size of the Galleon, the vessel could be large and require more than your typical smaller merchantmen vessels \n* Possibly trying to factor in a margin for men killed by disease if they expect to be at sea long enough or in circumstances where disease was common wherever they were going \n \nHard to give a more decisive answer without more information.",
"For sailing the ship, the number of crew needed is largely determined by the number of masts and the type of rig. (Also, the details of the rig had some bearing as, generally, later in history, advances in rig efficiency such as divided tops’ls and to’gallants, brace winches, etc., allowed crew efficiency to increase).\n\nSquare rig required more crew per mast than fore and aft rig.\n\nChapman reckons that a 4 masted full rigged merchant ship (late in the age of sail) required a crew of 48. (p. xvi) He reports that the 7 masted schooner “Thomas W. Lawson” (5,200 tons gross) operated with a crew of 16 men.\n\n“Chapman, Great Sailing Ships of the World”, _URL_0_\n\n\nI have sailed a 100 foot brigantine (square rigged on the foremast, fore and aft rigged on the main mast) perfectly well with a captain and 4 sailors. (Of course some evolutions, like setting and taking sail would have been faster with a larger crew, and others such as weighing anchor (man-powered windlass on this ship), would have been easier.)\n\nThis was day sailing. On a longer voyage, where 24 hour coverage was required, the same ship, on a 2 watch system, would have worked well with an 11 man crew (Captain, mate, 8 seamen, 1 cook).\n\nWarships, of course, needed far larger crews than merchant ships. This was primarily due to the number of men needed to operate the cannon. A training manual for the French revolutionary navy specifies that a 36pdr cannon should have a crew of 15 men, an 18pdr cannon should have a crew of 11 men, and an 8pdr cannon should have a crew of 7 men.\n\nChris Henry, “Napoleonic Naval Armaments 1792-1815”, _URL_1_\n\n\nWarships only rarely carried enough men to man all their cannon at once (usually only one broadside).\n\nBesides the number of men needed to operate cannon, warships also carried marines, specialist petty officers, larger numbers of able seamen, so that sail handling could be carried out more rapidly, which would be an advantage in combat.\n\nSo, the main reason why ‘Spanish Galleons’ needed such large crews was because they were either warships, or armed to protect their cargoes from attack by pirates or national enemies, and they needed to carry enough crew to man their cannon.\n\nThe absolute minimum size of crew to get a galleon (assumed to be 3 masted, full rigged) running I estimate at 5-6, (but that would be very slow and inefficient – Setting or taking sails would be one at a time for example – This might not even be enough manpower to haul the anchor (depending on windlass efficiency and strength of wind and wave) but the cable could always be cut in a real emergency.). For fairly efficient operation (one watch only – not very good for long voyages) perhaps 12. For fairly efficient sailing on a long voyage (but very inefficient fighting with the cannon) about 25.\n\n\n(Note: \"Fairly efficient\" means \"a reasonable balance between the cost of the crew and the efficiency, performance, and safety of the ship\", as it might be perceived by a merchant ship owner (perhaps a somewhat stingy one). Clipper ships, (also three masted, square rigged ships, like galleons (though 200 years or so later in history)) on the California run, generally carried a crew of 50-60. These ships carried proportionally much more sail area than Galleons. They valued speed much more highly. They knew they would need to sail through the extreme and dangerous conditions round Cape Horn (where a larger crew which could take sails rapidly might contribute greatly to the safety of the ship). So they were willing to invest in a larger crew in order to gain \"high efficiency\" rather than \"fair efficiency\". Different ship owners in all eras might value sailing efficiency differently. The more they valued this, the more they would be inclined to ship a larger crew.)\n\n(Rough estimate for number of crew required to provide various \"efficiency levels\" for a three masted, full rigged, ship on a two watch system: \"Fair efficiency\" - 25-30 men; \"Good efficiency\" - 30-40 men; \"High efficiency\" - 40-60 men.)\n\n\n\nFor what did the crew do when they weren’t at their stations, see this earlier post which asked a similar question but about 1st and 2nd rate ships rather than galleons. The tasks I mentioned in my reply would have been very similar for galleons.\n\n_URL_2_\n"
]
}
|
[] |
[] |
[
[],
[
"https://books.google.no/books?id=QgMRudqoLGQC&pg=PR15&lpg=PR15&dq=size+of+crew+on+sailing+ships&source=bl&ots=9TyCVTDP9f&sig=E-s9V33IaacETh-vr8BoM_9cJno&hl=en&sa=X&ei=5DwJVcrrDsf4OraggeAG&redir_esc=y#v=onepage&q=size%20of%20crew%20on%20sailing%20ships&f=false",
"https://books.google.no/books?id=Bs2MVggWyvQC&pg=PT18&dq=number+of+crew+to+man+a+naval+cannon&hl=en&sa=X&ei=UkQJVZObOoWuPKfUgNAC&ved=0CDIQ6AEwAg#v=onepage&q=number%20of%20crew%20to%20man%20a%20naval%20cannon&f=false",
"http://www.reddit.com/r/AskHistorians/comments/23ibxt/what_were_the_maintenance_requirements_for_a_1st/"
]
] |
|
52b278
|
Is "ancient" denoted by a specific length of time?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/52b278/is_ancient_denoted_by_a_specific_length_of_time/
|
{
"a_id": [
"d7j8pln"
],
"score": [
4
],
"text": [
"Ancient History dates from the beginning of recorded history under the Sumerians and their Cuneiform script sometime around the 3rd millennium BC until sometime around the 5th century AD depending on what part of the world you're looking at. The end of the ancient period and the beginning of the Medieval period is in Europe clearly associated with the fall of Rome, whichever 5th century date you attribute this phenomenon to.* In China or the Middle East the dates are different, but I'm not sure what events they are generally associated with.\n\nAs a side note, Classical history, which is my area, is a relatively short but dominant field of Ancient history focusing on the Greco-Roman world, defined by the beginning of the Homeric era in Greece around the 8th century or so BC until the fall of Rome. Due to the predominance of the Classical period in Ancient history and the cultural and intellectual traditions descended to the West from the Greco-Roman world, when most people say \"ancient\" or refer to the \"ancients\" they are referring to the Classical period and its Mediterranean inhabitants. \n\nEssentially, Ancient history refers to a period of time roughly 3500 years long from the beginning of recorded history to the mid/late 5th century AD. \n\n* The traditional date is of course AD 476, when Romulus Augustulus was deposed by Odoacer, but this date is notoriously arbitrary due to the fact that Roman imperial authority in the West had fragmented well before this date. Other dates might include the sacks of Rome in 410 and 455, the appointment of the insidious Ricimer to the post of *magister militum* in 461, the death of Julius Nepos in 480 or the brutal overthrow of Odoacer by Theodoric in 493. "
]
}
|
[] |
[] |
[
[]
] |
||
1fqf4w
|
how do components of electricity work?(i.e. power/wattage, potential difference/voltage, current/amperage)
|
I've usually tried to understand most things using analogies to everyday life. Before being introduced to the concept of these in an Academic setting, i've always thought of electricity being like Water through a pipe, Voltage is the water pressure, Amperage is the Amount of water, but then what would Wattage be?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1fqf4w/eli5_how_do_components_of_electricity_workie/
|
{
"a_id": [
"cacsir4",
"cacts0u"
],
"score": [
2,
2
],
"text": [
"Power is a change in energy per unit time (measured in Watts). A circuit uses up a certain amount of energy. The power is how much energy is used every second.\n\nYour ideas of voltage and current are pretty much spot on. The voltage \"pushes\" the current through the circuit. Current is just a flow of charge.",
"Power and energy are related in the same way speed and distance are related. m/s is how many meters you travel in a second. A Watt is J/s so how many joules of energy are being used per second."
]
}
|
[] |
[] |
[
[],
[]
] |
|
1iudhy
|
How are virus like rabies able to proliferate when they kill their hosts outright?
|
I would think that virus such as these have a very poor evolutionary model. To survive indefinitely inside a host, it would make better sense to not kill the host right away right? I don't understand how this type of virus continue to survive.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1iudhy/how_are_virus_like_rabies_able_to_proliferate/
|
{
"a_id": [
"cb8nr5v"
],
"score": [
2
],
"text": [
"You are correct that rabies kills humans very well, making them a poor host for rabies virus. However, the natural host for rabies virus is typically wild carnivores such as raccoons and canines, or bats ([WHO source](_URL_0_)).\n\nCorrect, a parasite is usually best off when it does not kill its host quickly. Rabies may not be well adapted to humans, but it is very well adapted to other hosts such as bats, where it stays in the environment. This zoonosis is also the main reason that it is nearly impossible to eradicate rabies.\n\nAnother excellent example of this is Ebola, which has an incredibly high mortality rate in humans, but may persist in the environment through infecting bats, where it does not kill the host and replicates well."
]
}
|
[] |
[] |
[
[
"http://www.who.int/zoonoses/diseases/rabies/en/"
]
] |
|
1dgk78
|
How often did a Knight train? What was their age of retirement? & c
|
Do we have any information on the practical side of knighthood? Training regimens, estimate of average hours trained daily/weekly, etc?
Would a higher ranked knight train less and take his military role less seriously due to other demands on his time or a higher personal 'value'?
Around what age would a knight 'retire' if he didn't acquire a crippling injury?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1dgk78/how_often_did_a_knight_train_what_was_their_age/
|
{
"a_id": [
"c9q7h6c"
],
"score": [
2
],
"text": [
" > Training regimens, estimate of average hours trained daily/weekly, etc?\n\nI don't know the direct answer to your question, but I can start you off on your journey of discovery. \n\nTowards the end of the Knightly period we start to see some details of the Knightly martial arts. They suggest that serious fighters trained for a few hours a day. The manuals that describe masters work would require years of dedication to master: \n\nHere's a link to the Master [Fiore De'i Liberi](_URL_1_) he describes a fighting system that starts with wrestling (which has a closer visual style of JuJitsu), and then goes on to how to fight with dagger, sword in one hand, sword in two hands, spear, poleaxe, and mounted combat. \n\nAnother crowd favourate is [Johanne Liechtenauer](_URL_0_) who describes a martial arts with a focus on technical sword work \n\nThe sword and buckler was the foundation of honour duels in the medieval period. _URL_2_\n\n\n"
]
}
|
[] |
[] |
[
[
"http://wiktenauer.com/wiki/Johannes_Liechtenauer",
"http://wiktenauer.com/wiki/Fiore_de%27i_Liberi",
"http://wiktenauer.com/wiki/Liber_de_Arte_Dimicatoria_(MS_I.33)"
]
] |
|
30izkc
|
Why didn't the USA apply the Monroe Doctrine during the Falkland War?
|
As the question above states, I realize that there are diplomatic reasons behind why the USA would have chosen not to apply this doctrine with regards to intervention within South America, but did the USA have a justifiable reason to ignore the conflict over the Falkland Islands or was it more conveniently ignoring the Monroe Doctrine?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/30izkc/why_didnt_the_usa_apply_the_monroe_doctrine/
|
{
"a_id": [
"cpsvq8l",
"cpsx9pc"
],
"score": [
40,
51
],
"text": [
"The Monroe Doctrine is often taught as a policy that precluded European involvement in the western hemisphere. In fact, however, it precluded *further* colonization or interference with states in the western hemisphere. The Falklands were initially colonized before America was even founded so it was not further colonization or interference with an American state. The war in the Falkland Islands began because Argentina tried to take an existing British possession. The British were simply defending that existing possession, not acquiring a new one or interfering with an American state. \n\n**tl;dr:** The war in the Falkland Islands doesn't fall within the purview of the Monroe Doctrine. ",
"Well, the Falkland War was also a diplomatic issue for the United States. It didn't want to apply the Monroe Doctrine because of that, but it certainly didn't agree with Margaret Thatcher of the UK in this instance. The conflict actually led to some friction between Reagan and Thatcher, which was fairly rare apparently.\n\nThe U.S did everything it could to find a solution to the conflict, with Secretary of State Alexander Haig shuttling back and forth doing his best to try to solve it before the British entered the warzone. The U.S had no real good options in this scenario, however. It could not force Britain out of the Western Hemisphere, and it was concerned over the prospect of escalation. It could not find a solution to either side's wounded pride, and it was scared that ties with both Latin America and Britain would be hurt by the conflict between them. This was a lose-lose for the United States.\n\nThe United States took an initial policy of \"even-handedness\", arguing that both Britain and Argentina were allies and that they should work this out peacefully. However, neither party was very willing to listen. They believed that the U.S stake in the conflict made it someone they couldn't trust, and its hesitation to pick one side over the other made both more suspicious of it. Argentina figured that if the U.S believed it was an ally to both and wanted peace so badly, it wouldn't intervene on the side of the British...just as it hadn't when the Argentinians first invaded the Falklands. And sending Haig didn't seem to work very well, after all...he wasn't a great diplomat on this issue, didn't seem to know it well or come up with solutions quickly at all, and his \"shuttle diplomacy\" was a far cry from Kissinger's. And to add to this whole mess, Haig was disliked by Thatcher and by Argentina's leaders, on a personal level. He just wasn't the man for the job, and he didn't do much to help mediate in the end.\n\nWhen peace overtures ended up rejected, the U.S decided to side with Britain. It viewed the British alliance as more important than the Argentinian one (meant to be against Communism), and decided to [sanction Argentina while providing material support to the British](_URL_1_). Argentina's calculation that it had leverage over the U.S, because of its role in the war against communism and in the protection of shipping lanes in the South Atlantic, was a miscalculation.\n\nThe British were upset when the U.S Ambassador to the United Nations, Jeane Kirkpatrick, made an even-handed statement justifying the use of force to pursue territorial claims based on historical grounds, which could be perceived as applying to the UK's right to respond or the Argentinian invasion alike. When questioned on it, Kirkpatrick explained her reasoning. She pointed out that the U.S had a longstanding commitment to the United Kingdom, but that it shared a common heritage with Latin America, which supported (besides Chile) Argentina in the dispute. So the U.S was caught between, as I said earlier, the fight against communism in the Western Hemisphere and the attempt to lead NATO against communism in Europe, which taking a side would not help. After all, Argentina had trade ties with the Soviet Union and refused to enact the embargo the U.S placed after the Soviet invasion of Afghanistan, which worried the U.S into thinking that the Soviets could cause mischief through Latin America. But it couldn't allow Britain to fail, either. That would be a huge blow to its pride, it would blame the United States for not exerting leadership and helping it, and it would demoralize the NATO alliance through Britain's anger.\n\nBy the time Haig negotiated, both sides were fairly deeply committed. Argentina could not withdraw or General Galtieri would lose all popular support and likely be deposed, and Thatcher had already sent a sizable Task Force that couldn't simply withdraw now that its pride was wounded. Argentina believed, with some good reason, that the UK was not serious about negotiations brokered by Haig. They seemed happy to allow negotiations to chug on while their ships chugged on, to paraphrase the words of one British War Cabinet member. Still, Britain had moved some on its proposals for a peaceful solution.\n\nBy April 26th, the stage was all but set. The British stopped all aircraft and ships going through the Falkland zone by April 28, and Haig gave his proposal to Argentina the day before. The Argentinians saw the proposal (which they had no fore-knowledge of) as coming on the tail of the incoming British threat, since it was handed to them on April 27. They wanted time to consider, not unreasonably, seeing the situation as prejudged and unfair. But they rejected the proposals, and so on April 30 Haig declared that the U.S would see the use of force to resolve disputes as unlawful, effectively siding with the British on this one. At that point, the U.S was committed to ensuring the British won: a loss would be devastating. The fact that mediation failed didn't get helped by the fact that Reagan was virtually in disbelief. Who would fight over such a ridiculous patch of island, he figured? Well, he underestimated the pride factor, it seems.\n\nSo why not invoke Monroe?\n\nWell, the answer becomes clear above. The U.S didn't know who to value more, between the feeling that one had to keep united against the \"communist threat\" of the Soviet Union, and the feeling that Britain was a longstanding ally who needed this help more. Eventually the U.S judged British support to be more valuable, seeing it as necessary to maintain the European bloc's morale and help the allies.\n\nBut it did lead to a lot of friction between Thatcher and Reagan, as I mentioned. Reagan was floating peace initiatives to Thatcher, and it didn't get anywhere easily. On May 31 Reagan proposed one to Thatcher, as he was concerned over Latin American opinion of the United States. He made another attempt on his visit to Europe June 2-4. Reagan figured that now that Thatcher had the upper hand and British pride, she could negotiate. Thatcher replied:\n\n > that we could not contemplate a cease-fire without Argentine withdrawal. Having lost ships and lives because for seven weeks the Argentines had refused to negotiate, we would not consider handing the Islands over to a third party\n\nThat didn't make Reagan happy, but his warm relationship with Thatcher helped soothe it. Even so, the fact that over the May 31 phone call she rejected his pleas *three times*, and more strongly each time, was not helpful to the relations. [This NY Times article on released documents from the National Archives](_URL_0_) talks about the friction that resulted from the dispute. But like I said, a warm relationship helped smooth it over. Which, coincidentally, may be another reason why the U.S didn't invoke the Monroe Doctrine. It got along so well with Thatcher, what use would invoking the Doctrine really be?\n\nAs was already brought up by /u/jgrey12, the idea that the Monroe Doctrine only applies to *new* colonization, and the Falkland conflict was over already held land, could also have influenced the way it played out. But it's also important to note that the Argentinians were disputing the Falklands being held by the British in the first place, so it could still apply. More importantly, however, the Monroe Doctrine was used to justify attempts to keep Soviet influence out of the Western Hemisphere, and this definitely played into the conflict: as I said, the U.S was reluctant to go against Argentina because it feared Soviet influence, after all. But it chose not to invoke the Monroe Doctrine in siding with Britain, because it believed that the British were more important than *possible* Argentinian turns to communism, which could really have led to an invocation of the Monroe Doctrine since that would be expansion of influence unlike the British case which appeared to be more preserving-based.\n\nActually an interesting corollary can be found in the case of Grover Cleveland's handling of the Venezuelan Crisis of 1895. Venezuela and Britain had a dispute over who had the rightful claim to Guayana Esequiba, and the U.S sided with Venezuela in this case. It also had the Monroe Doctrine invoked, and the British effectively submitted to it in this case. So in cases where control is disputed, as with the Falkland War, it can be down to more than just whether or not colonization is being expanded, since that is more ambiguous. Instead, it can often rely on the way that diplomacy plays out, and the *realpolitik* of the situation."
]
}
|
[] |
[] |
[
[],
[
"http://www.nytimes.com/2012/12/29/world/europe/falklands-war-caused-rare-friction-for-thatcher-and-reagan.html",
"http://fpc.state.gov/6172.htm#President_as_Initiator"
]
] |
|
6cpxor
|
does communism and capitalism have an end goal? if so what are they?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6cpxor/eli5_does_communism_and_capitalism_have_an_end/
|
{
"a_id": [
"dhwhcsg"
],
"score": [
2
],
"text": [
"I would say that he end goal of both is maximum human prosperity, but that communists have a more optimistic view on how properous humanity can get. Total equality is also an important end goal of communism that is not shared by capitalism (not that there is poverty or need in an ideal capitalist world, but some people will still be richer than others even if everyone is comfortable).\n\nI think perhaps the biggest point, though, is that most capitalists would say there is no end goal, this is just the best way to do things. Communists think of history as progress towards utopia while capitalists generally do not, so the idea of an \"end goal\" is a bit out of place in capitalism."
]
}
|
[] |
[] |
[
[]
] |
||
2ag0yq
|
how does one sports team pay another?
|
With Luis Suarez going to Barcelona for (reportedly) $130 million, how does one team pay another? Writing a check for $130 million seems too simplistic and cash doesn't seem logical either.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2ag0yq/eli5how_does_one_sports_team_pay_another/
|
{
"a_id": [
"ciup00z",
"ciup037"
],
"score": [
2,
2
],
"text": [
"Electronic Funds Transfer (EFT) or bank wire transfer. ",
"they play 5 games of rock, paper, scissors and if the paying team wins, the debt is forgiven. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
802ygh
|
why can't you martingale bet 1st and 2nd 12 on roulette and walk away with better odds than the house
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/802ygh/eli5_why_cant_you_martingale_bet_1st_and_2nd_12/
|
{
"a_id": [
"duslyft",
"dusmhmp"
],
"score": [
3,
5
],
"text": [
"The general problem with martingale bets is that the exponential increase of the betting amounts will quickly bankrupt most gamblers. Simply put, you don’t have an infinite amount of wealth to put up on the table. ",
"You have about a 63% chance of hitting either 1st or 2nd 12. Anything less than 66.6% chance is still in the house’s favor. \nAlso, a big problem with Martingale betting is running up against the max bet. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
1prsdh
|
why are skateboarding and bicycle helmets designed so differently?
|
Seems like there would be one design for protecting your head best? Are different types of injuries more common on each? do aerodynamics play a part? is it just so skateboarders can look cooler?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1prsdh/eli5_why_are_skateboarding_and_bicycle_helmets/
|
{
"a_id": [
"cd5bx87",
"cd5ci95"
],
"score": [
2,
2
],
"text": [
"Beyond style (and the hottest trend right now is bicycle helmets that look more like skateboard helmets- think Nutcase and Bern- Bicycle helmets are designed to protect against a single hard collision- say you hit a rock while riding at high speed, and then be disposed of. Skateboard helmets are designed for repeated \"oops, I fell off my board\" type falls. A lot of helmets are dual certified for both, and they're the hard-shell, round \"skateboard style\" designs. Skate style (whether dual certified or bicycle only) used for bicycle riding are going to be a lot hotter than a typical bicycle helmet, hence why you see most bicyclists using a stereotypical bicycle helmet. ",
"One major factor is the speed of the collisions involved. Bicycles can go much faster than skateboards with small wheels, so the amount of padding needed to properly cushion the blow from a crash is much higher for bicycles. This is why bicycle helmets are tall; the teardrop shape, however, is purely for aerodynamics. Most helmets, including motorcycle helmets, are automatically deemed unsafe to wear after being subject to one accident."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2pjc3c
|
What's the difference between organic carbon and non-organic carbon?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2pjc3c/whats_the_difference_between_organic_carbon_and/
|
{
"a_id": [
"cmxjde1",
"cmxjj6u"
],
"score": [
3,
7
],
"text": [
"[Hydrogen](_URL_0_):\n\n > Compounds that are considered organic must contain carbon bound to hydrogen and possibly other elements. By this definition, iron cyanide complexes, carbon dioxide, carbon tetrachloride, and sodium bicarbonate are all inorganic.",
"There is no difference between organic and nonorganic carbon. Carbon is carbon, defined by the number of protons. There is a difference, however, between organic COMPOUNDS (or molecules, species, whatever you want to call a bunch of covalently-bonded atoms, including carbon and hydrogen), and nonorganic compounds, as /u/mutatron stated."
]
}
|
[] |
[] |
[
[
"http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/what-is-inorganic-carbon.shtml"
],
[]
] |
||
4iuulh
|
if the multiverse theory is true, and if there are an infinite number of universes, does it logically follow that every possible universe exists? couldn't there be an infinite number of universes which exclude one particular kind of universe (i.e a fictional universe like s. wars)
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4iuulh/eli5_if_the_multiverse_theory_is_true_and_if/
|
{
"a_id": [
"d318ws5",
"d3195fu",
"d319cb9",
"d319eah",
"d31cd83",
"d31d6zf",
"d31gkgb"
],
"score": [
2,
38,
18,
2,
3,
4,
3
],
"text": [
"You'd have to temper it a bit to \"every universe that could exist would exist\". So if the laws of physics were shared, you still wouldn't get Godzilla sized crabs living on a planet like earth since the environment of such a planet wouldn't allow them to survive.\n\nOf course since the laws of physics could be different in these different universes, that might mean that every possible situation does exist.\n\nAlso the multiverse is just a hypothesis. The multiverse itself might not exist and there might just be this one.\n\nOr there could be a multiverse with a finite number of universes.",
"I disagree with the other posters that an infinite multiverse would even necessarily include every category or type of universe that **could** exist. Infinity does not mean that all possibilities are checked. The set of positive integers is infinite, but there are many more things that it doesn't include than it does, like pi, and -14, and Eva Peron. ",
" > does it logically follow that every possible universe exists?\n\nNo\n\n > Couldn't there be an infinite number of universes which exclude one particular kind of universe (i.e a fictional universe like s. wars)\n\nYes.\n\nIt only implies, in and of itself, that there are infinite universes. Not that all universes are represented. There can be any number of universes not included in that particular infinity, odd as it sounds. Similarly, there are infinite numbers in the group \"positive integers\" but none of them are -1, -10, .353, -1000, or .9999999...... and so on. There are infinite numbers *not* in the group as well.\n\nEdit: Oh, I basically replicated the answer of /u/Cliffy73. What he said.",
"There is a difference between \"every universe that could exist\" and \"every universe that could be imagined\". If universes are split by decisions or actions, then you could have a universe where Hitler was a famous musician; but not one where he could fly by flapping his arms.",
"As far as i see it, not every possible universe exists.\n\nThat would mean that there are an infinite amount of universes that contain machines that can teleport other items to this universe.\n\nAnd i don't see gold raining from the sky, or anything else (except snow and rain).",
"The way someone explained it to me is that there are an infinite number of numbers between 0 and 1. However, on none of those numbers will ever be 2. \n\nSo to answer your question yes there are infinite universes, and no not all possible universes exist.",
"I like to think about that one universe where magic exists (*seems to exist), where every time someone casts a spell, coincidentally something happens to make it appear the spell worked. Of course the inhabitants would never realize it was all just a lot of coincidences."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[]
] |
||
3bc7ww
|
if i were to stand at the geographic north/south pole, would someone looking at me from space see me as spinning around?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3bc7ww/eli5if_i_were_to_stand_at_the_geographic/
|
{
"a_id": [
"cskt8b8",
"cskt90u"
],
"score": [
5,
5
],
"text": [
"Yes, but not nearly as fast as you are imagining it. The earth rotates at 1000 mph at the equator, but it still only completes one rotation every ~24 hours. Likewise, you standing on the pole would only rotate once every ~24 hours. So you would be spinning, but just very very slowly.",
"Miles per hour is not a unit of rotational speed. The rotational speed of earth is 7.29 * 10^-5 radians per second. An observer in space would see you spin around once every 24 hours."
]
}
|
[] |
[] |
[
[],
[]
] |
||
11frue
|
How does the Trammel of Archimedes work?
|
[Video](_URL_0_) for those of you who don't know what it is. Basically, it traces an ellipse.
Can anyone explain the mathematics behind how this works?
|
askscience
|
http://www.reddit.com/r/askscience/comments/11frue/how_does_the_trammel_of_archimedes_work/
|
{
"a_id": [
"c6m29op"
],
"score": [
2
],
"text": [
" > Can anyone explain the mathematics behind how this works?\n\nThe Wikipedia article [Trammel of Archimedes](_URL_0_) does this."
]
}
|
[] |
[
"http://www.youtube.com/watch?v=Hfw0yYur5S4"
] |
[
[
"https://en.wikipedia.org/wiki/Trammel_of_Archimedes"
]
] |
|
t2ybo
|
spherical harmonics
|
What do they represent?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/t2ybo/spherical_harmonics/
|
{
"a_id": [
"c4j4kdd"
],
"score": [
2
],
"text": [
"Before we look at spherical harmonics, let's first look at another harmonic oscillation: Standing waves on a rope.\n\nTake a rope and attach one end to a solid wall. Now move the other end. If you hit the right \"beat\" you will get the whole of the rope swinging in a single standing wave. Double the beat and you get two bulges. Triple the base beat and you get 3 bulges. For every higher number of bulges you must put additional energy into the rope (=oscillator).\n\nIn this rope you can also overlay (=superposition) multiple modes of swing, i.e. a large single bulge and the smaller ones.\n\nNow imagine that the rope was some flexible spring and you form it into a closed loop. You can again excite it to oscillate. Instead of one single bulge you got deformation into some sort of ellipse. Add more energy and it becomes shaped like a 3 leafed clover, then a 4 leaved clover and so on. And of course you can superposition them.\n\nWhat you got now are circular harmonics.\n\nNow imagine you do this on a spherical closed surface (like a soap bubble). This surface can now oscillate in modes reaching over the whole surface.\n\nThis is in essence the whole idea of spherical harmonics."
]
}
|
[] |
[] |
[
[]
] |
|
2c4wv6
|
Can element 119 be possible?
|
We know it could go till element 118(Uuo) but can electrons go theoretically in the next orbit to form element 119?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2c4wv6/can_element_119_be_possible/
|
{
"a_id": [
"cjc0oi5"
],
"score": [
5
],
"text": [
"The only proposed \"limit\" to the elements is so-called \"Feynmanium.\" A simplistic analysis of electrons shows that for more than 137 protons (a non-relativistic theoretical prediction), electron speeds would exceed c. A slightly more rigorous calculation using relativity and the finite size of a nucleus moves up to 173 protons. And the result here is just that if the lowest energy electron orbital was empty, there would be enough energy in the electromagnetic field to create an electron-positron pair. \n\nSo no, there's not really any limit to the periodic table that we're aware of. I mean aside from the obvious \"it's really difficult to hold gigantic nuclei together\" problem\n\n[for more](_URL_0_)"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Extended_periodic_table#Feynmanium_and_elements_above_the_atomic_number_137"
]
] |
|
26dpa4
|
When a bone in the body chips/lesions where does the chipped part go and what does it do?
|
askscience
|
http://www.reddit.com/r/askscience/comments/26dpa4/when_a_bone_in_the_body_chipslesions_where_does/
|
{
"a_id": [
"chq3v1g",
"chq48k8",
"chq4d9x"
],
"score": [
2,
3,
2
],
"text": [
"Depends on the size of the chip, often if a bone has a non-union where the two or more pieces don't come together by a few months, then likely they never will. There's no phagocytosis of bone unless it's essentially dust.",
"Answer to your question: Depends on what \"chips.\" If the piece of bone remains in close contact to its donor site, has a blood supply, and remains relatively stable it can heal back to the intact bone. If the piece of bone is avulsed by a tendon or ligament and held apart from its donor site or is too mobile too heal (or has no blood supply) it will go on to \"non-union\" and never heal back. Somtimes you can feel it if it is just under the skin. Sometimes it will be broken down and absorbed by the body. Typically it does not say \"loose\" as most boney avulsions have some attachments to fascia or some other tissue keeping it in place.\nRegarding the stem of your question: A Hills-Sachs lesion is not a \"chip.\" When a person dislocates their shoulder the head of the humerus comes out of the cup of the glenoid. This is not a natural motion and the head of humerus and edge of the glenoid come into contact with each other very violently during the dislocation. In some people (particularly those who disolcate a lot) the glenoid will damage the head of the humerus by putting a \"dent\" in it. This is a Hills-Sachs lesion. It is not a chip; it is more like a depression or dent in the bone. \nSource: I am an orthopaedic surgeon",
"Am orthopaedic trauma surgeon.\n\nA Hill-sacks lesion is actually a dent in the humeral head (ball). The bone is impacted and will heal but the shape will not change. The dent is there to stay. A Bankart lesion is a chip off of the genpid (part of scapula/the socket of shoulder joint). These are common in younger people with shoulder dislocations and can lead to further dislocations. \n\nIn general small chips off of bone do not heal back to the bone but rather scar in with fiberous tissue. They may smooth out a little with time but are often there for years or decades. The \"chip\" is never really free floating but attached to the connective tissue around bones. \n\nHope this answers your question. If you want something more dreary I can drone on and on about osteoclasts and the phases of bone healing. Cheers. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
6o1o15
|
what is happening when you zero a rifle?
|
???
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6o1o15/eli5_what_is_happening_when_you_zero_a_rifle/
|
{
"a_id": [
"dkdvlif"
],
"score": [
3
],
"text": [
"you are setting the bullet impact at range to match the line of sight you view through the optic. Example: you have a rifle that has an optic that is 2\" about the centerline of the bore, being that there is a difference between the 2 lines (bore, sight), in order for them to coorespond at the desired distance (normally 100 yard or 100 meters) an angular adjustment must be made, these are known as \nMOA (1\"click\" = 1/8\", 1/4\" @ 100yrd) \nMILS (1\"click\" = .1 MIL (~.36in) @ 100 yards) \nThese adjustments will allow for the user to tune the optic to the ballistics of the round, height over bore of the optic, dispersion (vertical and horizontal) inherent to the barrel, harmonics of the system, etc. in order to set a baseline that further calculations and/or adjustments can be made from the systems \"zero\"."
]
}
|
[] |
[] |
[
[]
] |
|
3f4ti2
|
if the earth is heated by the sun, why are places that are higher up and closer to the sun significantly colder than the surface?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3f4ti2/eli5_if_the_earth_is_heated_by_the_sun_why_are/
|
{
"a_id": [
"ctlaswz",
"ctlau3i"
],
"score": [
2,
4
],
"text": [
"Can't explain like your 5 because alcohol but it's because our atmosphere traps heat so basically the higher you go the less atmosphere their is, could be wrong like I said alcohol ",
"Moving up/down on Earth's altitude is essentially meaningless in terms of \"closeness\" to the sun in terms of heat. However as you move further from the surface of the planet the air pressure drops, which does have a significant measurement in your heat."
]
}
|
[] |
[] |
[
[],
[]
] |
||
3yksax
|
What was the ethnicity of Beethoven?
|
Today a friend of mine came and said that he read somewhere that Beethoven was black. I asked where he read that, he said he would send me the link, but sent me nothing to the time of this post. He just showed me Beethoven's death mask and said the noise was like a black person's. Is there any truth to it?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3yksax/what_was_the_ethnicity_of_beethoven/
|
{
"a_id": [
"cyeazv8"
],
"score": [
14
],
"text": [
"From the San José State University's Beethoven Center [FAQ] (_URL_0_):\n > Was Beethoven black?\nMany people in the African-American community claim that there has been a conspiracy on the part of European-Americans to conceal Beethoven’s alleged black heritage. The theory that he was black is based on the fact that Beethoven’s ancestors came from the Flemish region of northern Europe that was invaded and ruled by the Spanish. Since the Moors were part of Spanish culture, it is possible that Moors were part of the invasion. This theory, however, is not based on genealogical studies of Beethoven’s past, which are available to the public. Rather, it is based on the assumption that one of Beethoven’s ancestors had a child out of wedlock. Another part of this theory is that Beethoven was given the nickname “Spaniard” as a child because he had a dark complexion by European standards. However, it is important to note that no one called Beethoven black or a moor during his lifetime, and the Viennese were keenly aware both of Moors and of mulattos, such as George Bridgetower, the famous violinist who collaborated with Beethoven.\n\n\nA recent article tackles the issue in depth: Nicholas Rinehart, \"Black Beethoven and the Racial Politics of Music History,\" *Transition* 112 (2013): 117-130"
]
}
|
[] |
[] |
[
[
"http://www.sjsu.edu/beethoven/research/faq_beethoven/"
]
] |
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