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3e8nnt
|
Music Historians, how did the standard drum kit originate and what were previous incarnations of it?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/3e8nnt/music_historians_how_did_the_standard_drum_kit/
|
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"The modern drum kit began to emerge with early jazz and syncopated marching band music. Originally it was actually just a hodge-podge collection of various instruments. You'd probably find the evolution of the kit very interesting. Some of the instruments evolved into newer versions of themselves (the hi-hat used to be a sock drum for example), while others (such as the wood-block) fell in to disuse. "
]
}
|
[] |
[] |
[
[]
] |
||
30x7s0
|
is it possible to amputate your own leg/arm and use that as food?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/30x7s0/eli5_is_it_possible_to_amputate_your_own_legarm/
|
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"Vsauce explained this quite well in one of his videos, I'm on mobile so sorry for no source. But basically you shouldn't eat yourself.\n\nEdit: link: _URL_0_",
"There is at least one good written story about this. Also the movie about the self amputation of the arm for mobility. \n\nBut I assure you that your body will effectively cannibalize itself internally to keep you alive if you are starving. That is why it is not a good idea to try to lose weight by fasting. ",
"The vsauce video basically says that it takes more energy to consume and digest your own limbs than it gives you in. ",
"For the most part there is a 10:1 ratio of weight of prey consumed to predator flesh produced. A predator, that relies on prey not only for the building blocks of its flesh but for the energy to do the building, has consumed ten times its weight in prey to achieve any particular size.\n\nOf course you could eat your own arm, but it would amount to a net caloric loss under the best of conditions. If you add in the nutritional burden of healing it only gets worse.\n\nThis is why the Charlton Heston movie, Soylent Green is based on an impossible premise. No population of humans can sustain itself eating humans. "
]
}
|
[] |
[] |
[
[
"https://youtu.be/kdrTQlClb08"
],
[],
[],
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||
5yr3pb
|
! how can a country go bankrupt.?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5yr3pb/eli5_how_can_a_country_go_bankrupt/
|
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"In most cases, it *can't* in quite the same way that a person or corporation does. A person can be made bankrupt and then whatever they own is taken and sold off to pay off the debts, and this is enforced by the country they live in. But there's no power to force a country itself into bankruptcy. Rather, a country can simply refuse to pay back its debts, which is known as 'default', and there's no solid way to stop them. Although a country that didn't pay back its debts will have a hard time borrowing again and that damages the economy.\n\nTrying to pay off the debts by printing more money doesn't work, because it just causes inflation - the money becomes worth less. Quite often the debts are owed in a different currency, for example Argentina might owe debt to a French pension company in US dollars, which means printing more Argentine pesos can't even pay off the debt directly. In extreme cases the result is hyper-inflation where the value of money just plummets as the government foolishly continues printing more and more bigger and bigger banknotes."
]
}
|
[] |
[] |
[
[]
] |
||
m1u5r
|
What is the border between a program with an Artificial Intelligence, and one without?
|
As the title suggests, I'm finding it hard to define an AI. Are there some ground rules, or definitions that clearly states when something has an AI and when it doesn't?
|
askscience
|
http://www.reddit.com/r/askscience/comments/m1u5r/what_is_the_border_between_a_program_with_an/
|
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"All sorts of things are considered to be 'artificial intelligence'. The most obvious example is AI for non-human players in computer games, but there is a whole field of Computer Science called Artificial Intelligence, which is related to things like [machine learning](_URL_1_), creating systems that learn what to do rather than being specifically programmed to do it. Things like banking systems that learn what your normal credit card activity is like so they can spot if your details get stolen. AI systems are all around us, doing jobs like language translation, spam filtering, handwriting recognition, even things like plane autopilots and automobile computers.\n\nAll of those things use AI, but perhaps they are not what you would call \"An AI\". For that we have some more specific terms. What most people think of when they think 'An AI' is what is called a [Strong AI](_URL_0_), meaning a machine capable of doing any mental task at least as well as a human. Such systems do not now exist. Personally I think they will within 50 years.\n\nOne well known test for an AI is the [Turing Test](_URL_2_), named after Alan Turing, a truly brilliant man who was also very good at getting things named after himself. The idea is that a person converses through IM, sometimes with the AI sometimes with other people, and if they can't reliably tell whether the person they are IMing with is a human or a machine, the machine has passed the test. Passing the test doesn't mean the machine is 'intelligent' necessarily, but it shows that it's good enough at acting intelligent to fool a human, which is a major milestone.\n\nSo to answer your question, the chances are good that your smartphone 'counts as an AI', in that it makes use of AI systems, but there are as yet no *strong* AIs, and we're not sure how to test for it but the Turing Test is a well known start.",
"The short answer is, there is no generally accepted answer to exactly what intelligence is. We don't know exactly how neural activity can lead to the type of behaviors we call intelligence, or consciousness, and so we're right now limited to defining these sorts of things behaviorally (by looking at systems as black boxes with inputs and expected outputs). The Turing Test is of course, the most famous example. That being said, the Turing Test is somewhat binary: you either pass or fail (where we define passing this test as being able to fool the same number of people as an actual human would). Is a calculator conscious / intelligent? According to this, no.\n\nAn alternate way is by using intentionality. John Searle's Chinese Room Argument, for example, attacks the Turing test and argues that an underlying intentionality is necessary for *real* intelligence. Exactly what intentionality is, though, is much too complicated to explain here (it takes an entire semester of philosophy of mind to understand).\n\nFinally, there are those that accept that there are degrees of intelligence (so a calculator would be \"somewhat\" intelligent, and even somewhat conscious). But this is difficult to separate from claims of [panpsychism](_URL_0_), which is a deal breaker for most who care about this issue.",
"All sorts of things are considered to be 'artificial intelligence'. The most obvious example is AI for non-human players in computer games, but there is a whole field of Computer Science called Artificial Intelligence, which is related to things like [machine learning](_URL_1_), creating systems that learn what to do rather than being specifically programmed to do it. Things like banking systems that learn what your normal credit card activity is like so they can spot if your details get stolen. AI systems are all around us, doing jobs like language translation, spam filtering, handwriting recognition, even things like plane autopilots and automobile computers.\n\nAll of those things use AI, but perhaps they are not what you would call \"An AI\". For that we have some more specific terms. What most people think of when they think 'An AI' is what is called a [Strong AI](_URL_0_), meaning a machine capable of doing any mental task at least as well as a human. Such systems do not now exist. Personally I think they will within 50 years.\n\nOne well known test for an AI is the [Turing Test](_URL_2_), named after Alan Turing, a truly brilliant man who was also very good at getting things named after himself. The idea is that a person converses through IM, sometimes with the AI sometimes with other people, and if they can't reliably tell whether the person they are IMing with is a human or a machine, the machine has passed the test. Passing the test doesn't mean the machine is 'intelligent' necessarily, but it shows that it's good enough at acting intelligent to fool a human, which is a major milestone.\n\nSo to answer your question, the chances are good that your smartphone 'counts as an AI', in that it makes use of AI systems, but there are as yet no *strong* AIs, and we're not sure how to test for it but the Turing Test is a well known start.",
"The short answer is, there is no generally accepted answer to exactly what intelligence is. We don't know exactly how neural activity can lead to the type of behaviors we call intelligence, or consciousness, and so we're right now limited to defining these sorts of things behaviorally (by looking at systems as black boxes with inputs and expected outputs). The Turing Test is of course, the most famous example. That being said, the Turing Test is somewhat binary: you either pass or fail (where we define passing this test as being able to fool the same number of people as an actual human would). Is a calculator conscious / intelligent? According to this, no.\n\nAn alternate way is by using intentionality. John Searle's Chinese Room Argument, for example, attacks the Turing test and argues that an underlying intentionality is necessary for *real* intelligence. Exactly what intentionality is, though, is much too complicated to explain here (it takes an entire semester of philosophy of mind to understand).\n\nFinally, there are those that accept that there are degrees of intelligence (so a calculator would be \"somewhat\" intelligent, and even somewhat conscious). But this is difficult to separate from claims of [panpsychism](_URL_0_), which is a deal breaker for most who care about this issue."
]
}
|
[] |
[] |
[
[
"https://secure.wikimedia.org/wikipedia/en/wiki/Strong_AI",
"https://secure.wikimedia.org/wikipedia/en/wiki/Machine_learning",
"https://secure.wikimedia.org/wikipedia/en/wiki/Turing_test"
],
[
"http://en.wikipedia.org/wiki/Panpsychism"
],
[
"https://secure.wikimedia.org/wikipedia/en/wiki/Strong_AI",
"https://secure.wikimedia.org/wikipedia/en/wiki/Machine_learning",
"https://secure.wikimedia.org/wikipedia/en/wiki/Turing_test"
],
[
"http://en.wikipedia.org/wiki/Panpsychism"
]
] |
|
kka7s
|
Have any scientists here experienced "the decline effect" in their experiments? What do you theorize is going on?
|
I heard about this effect in [Radiolab](_URL_0_): that the effect you first observe in early experiments decrease the more and more experiments you do.
Links to 2 articles about it:
[Nature](_URL_1_)
[The New Yorker](_URL_2_)
What the heck is going on here? Is this just the media overblowing things? The decline effect seems really interesting, and seems like it would revolutionize the principles behind the scientific method.
|
askscience
|
http://www.reddit.com/r/askscience/comments/kka7s/have_any_scientists_here_experienced_the_decline/
|
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"I've seen this many times. Most of it (in my experience) is regression to the mean, and part of it is just psychology. I know that the articles say nobody knows if it's regression or not, but I think it is. The way science is done is prone to this kind of effect; let me explain.\n\nWhen you start something off, you often try many different ways to approach the problem. Some work, some don't. Of the ones that work, some kinda work, some just work, some work well, and some work *really* well.\n\nYou are at the start of the project. You have limited resources. You want big bang for the buck....so you pick the one out of 10 that worked *really* well. But odds are, that was a fluke. It just so happened to work that well on your first iteration.\n\nTo examine it more closely; take 3 techniques that make widgets go clank. You apply all three in a preliminary test and get:\n\nMethod A - 10 clanks\n\nMethod B - 15 clanks\n\nMethod C - 2 clanks\n\nAs an early researcher, it seems that method B worked the best. But let's say you have unlimited resources. You try all three techniques 6 more times.\n\nA gives you : 10, 14, 13, 12, 15, 15\n\nB gives you : 15, 14, 13, 15, 12, 12\n\nC gives you : 2, 1, 4, 3, 6, 1\n\nA and B actually wind up being just as good as each other (averages are the same). But it you plot the average over time:\n\nRunning average of all experiments to date\n\nA - 10, 12, 12.3, 12.3, 12.8, 13.2\n\nB - 15, 14.5, 14, 14.3, 13.4, 13.2\n\nC - 2, 1.5, 2.3, 2.5, 3.2, 2.8\n\nYou can see that B looks like it got worse and A looks like it got better. Really, both just got more accurate as you repeated the experiment.\n\nBut in the real world, you don't have that. You have limited resources, so you have to pick. And based on that preliminary data, B is the best. You go with it. And you running average looks like just the row for B:\n\nB - 15, 14.5, 14, 14.3, 13.4, 13.2\n\nOh no! we went from an average of 15 clanks to an average of 13.2??? What happened? Regression to the mean.\n\nBUT.....this isn't the whole story. There is also accumulation and elimination of error. Here, an anecdote may help.\n\nWhen I was a tech, we had a genetic model in which a specific cell type would invade the lung and the mice would die of inflammation at around 18 days of age. We worked on this for a year or two, one guy studying that specific cell type. But suddenly....that cell type stopped showing up. And the mice lived to 21d of age. Uh-oh....\n\nLong story short, the animal facility had switched to dust free bedding in our room. It was the dust exacerbating underlying disease causing this cell type to infiltrate and worsen the disease. This was elimination of error; a problem we didn't even know existed. We didn't know the first bedding wasn't dust free anyway; turns out someone had been ordering the wrong stuff they whole time. \n\n---EDIT---\nForgot to include....there's a rule of thumb in industry. If you have some super-cool technique that just popped up in a lab somewhere, you don't heavily pursue it until at least two other labs have repeated it. Odds are you won't be able to repeat it because it's that \"one guy\" that is able to do it. This can be due to somebody massaging the technique or the data, but it's more often because this \"one guy\" has been doing this so long he's the world's only expert on the technique. Nobody else can do it. You have to wait to see if this \"one guy\" also has the ability to teach his awesome new technique to other people. \"If in the end, nobody knows what you've been doing, all your doing has been for nothing.\"\n",
"The Nature article you link to offers the same explanations I would.\n\nIf scientists test something many times, eventually someone is going to get a statistical outlier that exaggerates the effect. A very strong effect is more likely to get noticed and reported by the scientist. And it's also more likely to get published by a journal. As scientists try to recreate the effect, they get results closer to the actual effect.\n\nFurthermore, once something is published, there's a strong tendency to believe it, so at first the scientists who get a significantly lower result might not report it, or delay publication thinking their experiments are flawed. But slightly lower results do get reported. The next round of reports are seen as a correction, and the process repeats, until the results reflect the actual effect.",
"I think it's nothing more than publication bias and regression to the mean.",
"I've seen this many times. Most of it (in my experience) is regression to the mean, and part of it is just psychology. I know that the articles say nobody knows if it's regression or not, but I think it is. The way science is done is prone to this kind of effect; let me explain.\n\nWhen you start something off, you often try many different ways to approach the problem. Some work, some don't. Of the ones that work, some kinda work, some just work, some work well, and some work *really* well.\n\nYou are at the start of the project. You have limited resources. You want big bang for the buck....so you pick the one out of 10 that worked *really* well. But odds are, that was a fluke. It just so happened to work that well on your first iteration.\n\nTo examine it more closely; take 3 techniques that make widgets go clank. You apply all three in a preliminary test and get:\n\nMethod A - 10 clanks\n\nMethod B - 15 clanks\n\nMethod C - 2 clanks\n\nAs an early researcher, it seems that method B worked the best. But let's say you have unlimited resources. You try all three techniques 6 more times.\n\nA gives you : 10, 14, 13, 12, 15, 15\n\nB gives you : 15, 14, 13, 15, 12, 12\n\nC gives you : 2, 1, 4, 3, 6, 1\n\nA and B actually wind up being just as good as each other (averages are the same). But it you plot the average over time:\n\nRunning average of all experiments to date\n\nA - 10, 12, 12.3, 12.3, 12.8, 13.2\n\nB - 15, 14.5, 14, 14.3, 13.4, 13.2\n\nC - 2, 1.5, 2.3, 2.5, 3.2, 2.8\n\nYou can see that B looks like it got worse and A looks like it got better. Really, both just got more accurate as you repeated the experiment.\n\nBut in the real world, you don't have that. You have limited resources, so you have to pick. And based on that preliminary data, B is the best. You go with it. And you running average looks like just the row for B:\n\nB - 15, 14.5, 14, 14.3, 13.4, 13.2\n\nOh no! we went from an average of 15 clanks to an average of 13.2??? What happened? Regression to the mean.\n\nBUT.....this isn't the whole story. There is also accumulation and elimination of error. Here, an anecdote may help.\n\nWhen I was a tech, we had a genetic model in which a specific cell type would invade the lung and the mice would die of inflammation at around 18 days of age. We worked on this for a year or two, one guy studying that specific cell type. But suddenly....that cell type stopped showing up. And the mice lived to 21d of age. Uh-oh....\n\nLong story short, the animal facility had switched to dust free bedding in our room. It was the dust exacerbating underlying disease causing this cell type to infiltrate and worsen the disease. This was elimination of error; a problem we didn't even know existed. We didn't know the first bedding wasn't dust free anyway; turns out someone had been ordering the wrong stuff they whole time. \n\n---EDIT---\nForgot to include....there's a rule of thumb in industry. If you have some super-cool technique that just popped up in a lab somewhere, you don't heavily pursue it until at least two other labs have repeated it. Odds are you won't be able to repeat it because it's that \"one guy\" that is able to do it. This can be due to somebody massaging the technique or the data, but it's more often because this \"one guy\" has been doing this so long he's the world's only expert on the technique. Nobody else can do it. You have to wait to see if this \"one guy\" also has the ability to teach his awesome new technique to other people. \"If in the end, nobody knows what you've been doing, all your doing has been for nothing.\"\n",
"The Nature article you link to offers the same explanations I would.\n\nIf scientists test something many times, eventually someone is going to get a statistical outlier that exaggerates the effect. A very strong effect is more likely to get noticed and reported by the scientist. And it's also more likely to get published by a journal. As scientists try to recreate the effect, they get results closer to the actual effect.\n\nFurthermore, once something is published, there's a strong tendency to believe it, so at first the scientists who get a significantly lower result might not report it, or delay publication thinking their experiments are flawed. But slightly lower results do get reported. The next round of reports are seen as a correction, and the process repeats, until the results reflect the actual effect.",
"I think it's nothing more than publication bias and regression to the mean."
]
}
|
[] |
[
"http://www.radiolab.org/blogs/radiolab-blog/2011/may/03/cosmic-habituation/",
"http://www.nature.com/news/2011/110223/full/470437a.html",
"http://www.newyorker.com/reporting/2010/12/13/101213fa_fact_lehrer"
] |
[
[],
[],
[],
[],
[],
[]
] |
|
f4nj7y
|
what is the difference between a "good" and a "bad" bottle of wine?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/f4nj7y/eli5what_is_the_difference_between_a_good_and_a/
|
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"Honestly, whether or not you like it. There are a lot of complex factors that can go into it, like specific techniques for making the wine, other ingredients, what kind of grapes were used, where the grapes are from, etc. while all of that does have an impact on the taste of the wine, what makes any bottle “good” or “bad” is completely subjective and up to your own personal tastes. Adam Ruins Everything did a really great [segment](_URL_0_) that breaks it down better than I can.",
"Well even a good bottle can be bad - it’s called corked. That’s when the cork fucks up and basically shits into the wine making it all corky.",
"It's no different than a relationship. Who you find attractive isn't who the next guy finds attractive. Don't fret over the bougie wine snobs out there. Figure out what styles you like, and you'd be shocked at how many amazing wines are out there for $20-$30 a bottle."
]
}
|
[] |
[] |
[
[
"https://www.trutv.com/shows/adam-ruins-everything/videos/why-wine-snobs-are-faking-it.html"
],
[],
[]
] |
||
2wrygw
|
why do companies such as nintendo region lock certain products? what exactly is region locking?
|
I read the Wikipedia page for it but am still having trouble understanding the reason.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2wrygw/eli5_why_do_companies_such_as_nintendo_region/
|
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"Based on the Wikipedia article, it seems that region locking is when you make a product that's only usable using products available in a certain part of the world. For video games, this would mean that a game is only playable if the console (Wii, XBox, Playstation, etc.) is from the same region. \n\nNintendo has said that it has used region locking for reasons including making sure the games were localized (adjusted for the region where the games are played) and to deal with licensing issues (copyright rules that vary by country). ",
"Nintendo region locks their consoles for a few reasons. One is cultural differences; for example in Bravely Default the Japanese versions' costumes are much skimpier and the characters are younger whereas when it was localised for the West they were aged up and were given more 'modest' clothing. Nintendo also doesn't bother localising every single Japanese game for the West because the game or franchise might be:\n\n* unpopular or not very well-known\n* confusing to Western audiences\n* considered 'inaproppriate' for the West or impossible to localise in a way that would make sense to non-Japanese audiences\n\nThus they are region locked so there is no confusion; these games aren't translated into English anyways so unless you are a fluent Japanese speaker and reader living in the US there would be no reason for you to really want to play these games.\n\nThere are also economic reasons; in places like Australia even popular games are pretty expensive and if there were no region locking there would be no reason for them not to import US games for cheaper than it would be to buy Australian games.\n\nLicensing and copyright issues are also an issue that region locking deals with.\n\nI don't think Nintendo plans to remove region locking any time soon, but I believe some popular 3DS hacker (I dunno the correct terminology so I'm definitely not trying to be disparaging here) has devised a way to bypass region locking on the 3DS."
]
}
|
[] |
[] |
[
[],
[]
] |
|
bb1469
|
How do astronomers calculate the orbits of planets?
|
Is there just one equation that shows where a planet should be or is it more complex than that?
|
askscience
|
https://www.reddit.com/r/askscience/comments/bb1469/how_do_astronomers_calculate_the_orbits_of_planets/
|
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"If you're asking how to describe the orbits, there are a couple ways.\n\nThe more generalized method is to write differential equations that describe all of the forces in the system given the current state, which can then be used to simulate the system numerically from the current state onwards. There is inherent error accumulation in numerical methods (where the error of each step causes the next step to be ever so slightly more off), but there are methods like 4th order Runge-Kutta that minimize that error to extremely small levels. Numerical simulations can be as detailed as you want them to be, with their accuracy limited only by your description of the situation. You can generate differential equations like these from the Lagrangian of the system, which is an equation which describes all of the sources of kinetic and potential energy in terms of the variables that describe where your planets (or other objects of interest) are.\n\nMost differential equations that describe orbits have no analytical solution, which means you can't just find where a planet would be at time *t* without simulating everything in between; you have to do what I described above. However, two body systems (like an isolated sun and single planet) *do* have analytical solutions that allow you to do this. This is called a \"central-force problem,\" where the only force involved is a single force that points inwards or outwards only, without perturbations introduced by the other planets in the system. The two-body orbits are described by conic sections, and are really pretty good approximations of reality in most cases; we got to the moon with the math of conics.\n\nAs for how astronomers actually determine the orbits by observing the planets from earth, I actually have no idea and would like to know as well.",
"Certainly more complex than one equation, but not terribly complex. The task is to determine [orbital elements](_URL_2_) from a set of (at least two) observations. This can be done with [Gauss's method](_URL_3_), however that's the \"traditional\" way, and while there's no problem with it in principle, I'm sure the actual orbits these days are determined more robustly with more [advanced methods](_URL_0_). Someone who's actually doing this might comment in more detail.\n\nOnce you know the orbital elements, finding out where the body will be (or has been) is, in principle, as simple as using one equation. In practice -- again, more complex than that, but not terribly. You'd be using [numerical integration](_URL_1_), accounting for errors/inaccuracies and so on, and so on. \n\nThis is often the story in physics: things are simple in principle, but easily get complex or at least troublesome in practice.",
"There's a whole field dedicated to understanding orbits called orbital mechanics and that's what engineers use to deduce where a planet will be at some point in the future. In terms of astronomy and the night sky, astronomers rely heavily on the surrounding stars for guidance and so do satellites. Most satellites are outfitted with star trackers so that they can use reference stars to orient themselves in space. Most astronomers therefore use the stars to track the [motion of the planets](_URL_0_) through the night sky."
]
}
|
[] |
[] |
[
[],
[
"https://www.lpi.usra.edu/books/AsteroidsIII/pdf/3039.pdf",
"https://en.wikipedia.org/wiki/Verlet_integration",
"https://en.wikipedia.org/wiki/Orbital_elements",
"https://en.wikipedia.org/wiki/Gauss%27s_method"
],
[
"https://physics.weber.edu/schroeder/ua/Planets.html"
]
] |
|
3h657q
|
how my cpap senses my breathing in and out.
|
I have a Phillips cpap and it has an SD card that collects data on its useage. Is it literally sensing my breaths in and out? Is some circuit being broken or created by the air pressure?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3h657q/eli5_how_my_cpap_senses_my_breathing_in_and_out/
|
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"text": [
"A diaphragm (fabric that is suspended along an opening or a valve) will either be pushed or pulled based on the air flowing through it due to negative pressure. These diaphragms can be wired along a calibrated sensor that measures your breath. A reference voltage is applied along the circuit, and as the diaphragm changes shape the resistance increases and decreases, changing the output voltage to the sensor which will interpret as your breathing.\n\nAircraft pitot static systems work in the same way, which is the only reason I know (im a mechanic not a doctor lel)\n"
]
}
|
[] |
[] |
[
[]
] |
|
bqtsqw
|
I saw on a horrible history channel that the Aztecs use chocolate as money. Wouldn't all the chocolate melt during the summer, thus crashing their economy?
|
Couldn't they have picked something more sensible like gold, silver or obsidian?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/bqtsqw/i_saw_on_a_horrible_history_channel_that_the/
|
{
"a_id": [
"eo8zm24",
"eoqlcfa"
],
"score": [
7,
2
],
"text": [
"Aztec economy was much more complicated than just cocoa beans (chocolate) as currency. They also used cotton sheets and copper axes, and a lot of bartering. Here is a good thread on Aztec economy featuring answers by /u/DownvotingCorvo and /u/400-Rabbits\n\n[_URL_0_](_URL_1_)",
"In addition to the link provided by /u/grandpohbah, you might also be interested in these past discussions:\n\n- [How exactly did the Aztecs distribute the cacao bean as currency? Did the state have a monopoly on bean production? Were bean farmers the richest people in the empire?](_URL_0_)\n\nWherein /u/historianla talks about the continued use of cacao into the the Colonial period, as well as exchange rates, and I chime in to note why cacao ended up as a mode of exchange (hint: it doesn't grow in the Central Highlands).\n\n- [How did Aztec society measure wealth?](_URL_1_)\n\nWhich is more about general socio-economics of Aztec society.\n\nAlso, I want to reiterate, it was the beans, not processed cacao, that was used a currency. The kind of chocolate we think about today is a post-Contact invention. Mesoamericans consumed cacao as a drink. Coe and Coe's *True History of Chocolate* is a very accessible book on the topic if you want to learn more."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/526plh/how\\_developed\\_were\\_commercial\\_networks\\_in\\_the/",
"https://www.reddit.com/r/AskHistorians/comments/526plh/how_developed_were_commercial_networks_in_the/"
],
[
"https://www.reddit.com/r/AskHistorians/comments/83qnz1/how_exactly_did_the_aztecs_distribute_the_cacao/",
"https://www.reddit.com/r/AskHistorians/comments/3as1tv/how_did_aztec_society_measure_wealth/csob2g3/?context=3"
]
] |
|
6kzbe1
|
can you guys help me understand this paragraph
|
This is one of the questions from south korean SAT equivalent test prep book (English reading section) and I've been struggling with this for 2hours lol I don't know if I'm too stupid to understand this paragraph , I need help.
Here it is :
The tourism sector's reaction to climate change has involved two different but related responses : mitigation and adaptation strategies. Mitigation refers to attempts to reduce the impact of tourism on climate change, while adaptation refers to attempts to adapt tourism to climate changes and minimize climate change risks. The tourism sector will also need to make adaptations in response to national mitigation strategies related to greenhouse gas emissions, hence the concepts are related. For instance, as a sector totally reliant on transport, national and international mitigation polic related to greenhouse gas emissions are likely to increase costs of transport and impact tourism mobility. There are implications for slow travel which emphasizes traveling to destinations more slowly and staying longer in one place rather than cramming in as many places as possible in a short space of time. For example, it could be argued that slow travel should become a major mitigation response, as part of a cultural change, associated with [ blank ]
1. Travel and trip distance reduction
2. Removal of unnecessary regulations
3. Provision of fast and safe transport
4. Diverse tourism products to choose from
5. Reducing conflicts between locals and tourists
This answer is 1 btw :-)
But it's not the answer that really matters, I have NO idea what that paragraph is all about. If you had no problem getting this question right, I dare you to try these questions. Smh korean tests
_URL_0_
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6kzbe1/eli5_can_you_guys_help_me_understand_this/
|
{
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"text": [
"It's saying that the tourism sector is responding to climate change by trying to reduce their impact on the climate, and by trying to adapt to a changing climate. One way to reduce the impact is to promote more slow travelling, which is staying in one place for a while and enjoying it rather than travelling to a whole bunch of places in quick succession. Slow travel is associated with travel and trip distance reduction - therefore less carbon emissions.",
"It's basically giving you a background on what the tourism sector has done to reduce emissions, and then asking you what the \"best\" option is to reduce emissions, based on what they've just told you about the sector.\n\nSo:\n\nMitigation: Attempts to reduce the impact of tourism on the environment (specifically emissions from transportation)\n\nAdaptation: Adapting tourism to climate change that already exists\n\nThe question states that \"cramming in as many places as possible in a short time\" is a bad thing. So the correct answer is (1), because reducing the amount of travel and trip distances directly results in a reduction in overall emissions.\n\n(2) is not correct because it is not associated with the information in the question;\n\n(3) is not correct because the question states that slow transportation is \"good\" for reducing emissions;\n\n(4) is not correct because diverse tourism products do not affect trip distances or frequency of travel (or may adversely affect them);\n\n(5) is not correct because it has no bearing on emissions.",
" > The tourism sector's reaction to climate change has involved two different but related responses : mitigation and adaptation strategies. Mitigation refers to attempts to reduce the impact of tourism on climate change, while adaptation refers to attempts to adapt tourism to climate changes and minimize climate change risks.\n\nStarts off with the difference between the mitigation and adaptation strategies. Climate change is impacting tourism adversely, and there are two ways to go about handling this: one is to reduce the negative impact itself (in other words, mitigating it) and the other is to adapt the tourism sector itself (adapting strategy.)\n\n > The tourism sector will also need to make adaptations in response to national mitigation strategies related to greenhouse gas emissions, hence the concepts are related.\n\nThe two strategies mentioned earlier are interrelated because mitigation involves GHG reductions, and GHG reductions require a change in approaches, which is simply adaptation.\n\n > For instance, as a sector totally reliant on transport, national and international mitigation policy related to greenhouse gas emissions are likely to increase costs of transport and impact tourism mobility. \n\nTourism is meaningless without having tourists moving around. Tourists moving around = fuel consumption = GHG emission. If fuel standards are to be improved to reduce GHG emission, costs will go up and reduce mobility for tourists.\n\n > There are implications for slow travel which emphasizes traveling to destinations more slowly and staying longer in one place rather than cramming in as many places as possible in a short space of time.\n\nBasically, instead of trying to have breakfast in NYC, lunch in Panama and dinner at LA, spend more time in a single place and take in all the sights rather than rushing through everything as fast as possible.\n\n > For example, it could be argued that slow travel should become a major mitigation response, as part of a cultural change, associated with _____\n\nSince the last point focuses on slowing down travel, the next sentence is unlikely to change topic abruptly. That rules out options 2, 4 and 5. Option 3 is contradicting the previous point, which pretty much favours slowing down and smelling the roses. Hence we can rule it out too, and the right option is bound to be option 1.",
"Travel and tourism is bad because it causes greenhouse gases which are super duper bad because of we're all going to die climate change. So everyone should travel less to keep the earth from dying. You don't want to kill the earth do you?\n\nSee it's all about the subtext that we're all going to die if we don't immediately change how we live. Be a good world citizen, stay home and produce. Not reproduce because the world is over populated and that also causes climate change. \n\nIf you're taking this as a Korean learning English the best thing to do would be to watch more American news to see what you should be afraid of then choose the answer that would best remedy the situation. Extra credit: Google \"problem, reaction, solution\".",
"If u break it down each sentences it would be much simpler and it will still lead you to the answer of 1.\n\nFirst sentence simply refers to the 2 different responses to climate change. Simple enough.\n\nSecond sentence is just definition of each response.\n\nThird and fourth sentence is just emphasis on the situation.\n\nFifth and last sentence is the clue to the answer. Since it is talking about the travelling between destinations, the answer would be no.1 or no.3. \n\nBut using no.3 as an answer would mean \"cramming in as many places as possible in a short space of time\" thus by elimination the answer is no.1. \n\nCorrect me if my logic is wrong. cheers"
]
}
|
[] |
[
"https://youtu.be/pNTwRSKVJLc"
] |
[
[],
[],
[],
[],
[]
] |
|
36v1sl
|
if my pc freezes why are my sound keeps playing?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/36v1sl/eli5_if_my_pc_freezes_why_are_my_sound_keeps/
|
{
"a_id": [
"crhcd13"
],
"score": [
3
],
"text": [
"because sound data is still stored in the sound card buffer. The sound card runs seperately from the CPU so it will keep going over the same data over and over and over since it is not being updated by the CPU."
]
}
|
[] |
[] |
[
[]
] |
||
261ysa
|
Is there any possibility now or in the future that some form of solid light could exist?
|
When talking about solid light, I mean light that can be held or created into solid objects. Far fetched question, but just curious if this is even a possibility. Thanks!
|
askscience
|
http://www.reddit.com/r/askscience/comments/261ysa/is_there_any_possibility_now_or_in_the_future/
|
{
"a_id": [
"chmylhv"
],
"score": [
2
],
"text": [
"There has been some theoretical work done on suggesting of combining light particles together to form this kind of stuff. I believe recently, within the last year or so, they've started to make actual progress on getting light particles to interact and form a kind of \"molecule\" of light. I put that in quotations because it is obviously not really like a molecule at all. \n\nThis light that interacts is probably the closest thing that you are going to get to \"solid light\". "
]
}
|
[] |
[] |
[
[]
] |
|
s3oxz
|
Is the Heisenberg Uncertainty Principle connected to determinism?
|
I've always adhered to the idea of determinism; the idea that every event is a result of previous events, and humans ultimately have no free will since everything one does is determined by their previous experiences (environment) or their genetics.
However, I got to thinking about the uncertainty principle. Could the non-concrete positions of fundamental particles be a counter-statement? Since we can't truly observe anything accurately on that scale, does that not mean that what happens after is not pre-determined?
|
askscience
|
http://www.reddit.com/r/askscience/comments/s3oxz/is_the_heisenberg_uncertainty_principle_connected/
|
{
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"text": [
"Quantum mechanics says that the results of experiments are subject to strict random distributions, and this prediction has been rigorously tested (and debated). It is thus both deterministic and nondeterministic, in a sense.\n\nIt is deterministic in that the prediction for two identical experiments is always the same (there is a strict cause and effect relationship). However, the prediction is a probability distribution for the results of the experiment.\n\nIt is thus nondeterministic as the measured values for any individual experiment cannot be known ahead of time. However, for most experiments it is possible to run the experiment many, many times and test that the results have the expected distribution (not only the expected average, but the same shape, too!).\n\nIn the end, quantum mechanics does not allow for free will any more than classical mechanics. That's not to say that free will surely doesn't exist- but it's not a part of quantum mechanics, and quantum mechanics accurately describes nature as far as we know it.\n\nOf course, there's a whole other debate we could be having here, depending on the definitions of \"free will\" and \"determinism\" that you want to use- but I'm no expert in philosophy. There is an askphilosophy forum that is much more likely to know about that, if you are curious.\n\nEdit: The heisenberg uncertainty principle is really a footnote in this discussion- it's just an oft-touted fact about quantum measurement which relates the probabilistic nature of quantum mechanics- the important fact here is that quantum mechanics says (as an axiom, in fact) that the results of experiments have a fundamentally probabilistic nature.",
"Quantum Mechanics is based on probability...not certainty. Heisenberg's Uncertainty Principle is one aspect of this.\n\nBasically your notion that future events can be predicted with certainty is wrong. The nature of the universe prohibits this. Per Heisenberg's principle you *cannot* know both the position and the speed of a particle with perfect precision such that you could predict future events with perfect accuracy.\n\nThe better you know one aspect (momentum or position) the less well you know the other. This will lead you to the [Butterfly Effect](_URL_0_). As you try to predict the future the errors in the initial measurement, which cannot be know with perfect precision, will magnify. Eventually your predictions will be way off the mark.",
"The notion of determinism you describe actually traces back famously to Laplace who, beaming with the recent successes of Newtonian mechanics, wrote the following:\n\n > An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.\n\nWe now know there's (at least) one problem with this. As you suggest, the Uncertainty Principle makes it impossible to for anyone to know the position and momentum of *anything* with absolute certainty. So we can't satisfy Laplace's initial conditions, and never will. \n\nSome might claim a second problem with Laplace's demon is that the universe is inherently non-linear, and even without the Uncertainty Principle there's still an issue of sensitivity to initial conditions that reduces determinism to chaos (no pun intended)."
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Butterfly_effect"
],
[]
] |
|
10pw78
|
Are there any former SS members who worked at concentration camps that are still alive?
|
I'm aware that most of them were executed at the end of the war and many others served life in prison. I know some fled to Argentina and hid their identities. Are there some that are still alive today who are living in a normal society somewhere?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/10pw78/are_there_any_former_ss_members_who_worked_at/
|
{
"a_id": [
"c6fno5z"
],
"score": [
4
],
"text": [
"Here's a list of the most wanted nazi war criminals according to the Simon Wiesenthal Center:\n\n_URL_0_\n\nSome of them are SS. Looking through their pages I can't see any that were in camps apart from Alois Brunner who is probably dead. He'd be 100 years old now."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/List_of_Most_Wanted_Nazi_War_Criminals_according_to_the_Simon_Wiesenthal_Center"
]
] |
|
3o3e3f
|
Is the Voyager probe orbiting the Galactic center? Is it orbiting anything?
|
If the Voyager Probe (and others like it) are leaving the solar system, can they be said to be orbiting the center of the Milky Way?
Or is it possible for them to be orbiting something else or nothing at all?
Thanks for answers.
|
askscience
|
https://www.reddit.com/r/askscience/comments/3o3e3f/is_the_voyager_probe_orbiting_the_galactic_center/
|
{
"a_id": [
"cvuwm03"
],
"score": [
2
],
"text": [
"Although it's an unsupported claim, I'd say that Voyager is more attracted to the sun or even Proxima Centauri(our closest star) than it is to the center of the Galaxy. Considering the distance to and the mass of the black hole at \nthe center, you get a gravitational force of about 5.886e-12 Newtons acting on Voyager I, whereas the pull from Proxima Centauri is about 7.331e-12 Newtons which is(albeit marginally) larger that the gravitational pull from the center of the Galaxy. \n\nIf anyone cares, here are the values that I used: distance Voyager I to center of the Galaxy = 27,000 light years \n\nWeight of the super massive black hole there = 4.31e+6 solar masses \n\nWeight of Voyager 1 = 722 kg \n\nDistance Voyager I to Proxima Centauri = 4.24 light years - 1.9e+13m(distance sun - Voyager I)= 3.987e+16m\n\nWeight of Proxima Centauri = 2.446e+29kg\n\n\nEDIT: took the distance of Voyager I to the sun instead of radius of the solar system for the distance to Proxima Centauri "
]
}
|
[] |
[] |
[
[]
] |
|
t037d
|
How would you fix something like the Guatemala sinkhole?
|
Pic for reference: _URL_0_
Do they just pour in a lot of dirt? Wouldn't that just become unstable again?
If a sinkhole that size was there, wouldn't that mean that the whole city area would be in danger of falling into sinkholes? Is there anything they can do to prevent them from happening?
|
askscience
|
http://www.reddit.com/r/askscience/comments/t037d/how_would_you_fix_something_like_the_guatemala/
|
{
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"c4if5kz",
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],
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2,
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"text": [
"I was mostly convinced that was photoshopped, then googled it. Blimey. From the article I read on it: \n\nTypically, officials fill in sinkholes with large rocks and other debris. But the 2010 Guatemala sinkhole \"is so huge that it's going to take a lot of fill material to fill it,\" Currens said. \"I don't know what they're going to do.\"\n\n_URL_0_",
"In Florida, we build fences around them, put a staircase going down to the bottom, and call it a park.",
"Before the sinkhole can be filled other problems need to be addressed. The city sits on unconsolidated soil that can easily be washed away, which, in addition to the tropical storms and heavy rainfall, likely added to the formation of this hole. The underground water system needs to be thoroughly inspected to detect if there are other places where something disastrous like this could occur.\n\nAs for filling it in, if this is what they decide to do, it would be quite an endeavor. In order to preclude large amounts of settlement in the surrounding area, the fill material would need to be placed in controlled lifts and compacted. In a hole this deep with vertical sides this is nearly impossible to do safely. \n\nI am interested to see how they go about fixing this."
]
}
|
[] |
[
"http://thecotas.rarebirdinc.com/wordpress/wp-content/uploads/2010/12/guatemala-city-sinkhole-2010-aerial-close_21124_600x4501.jpg"
] |
[
[
"http://news.nationalgeographic.com/news/2010/06/100601-sinkhole-in-guatemala-2010-world-science/"
],
[],
[]
] |
|
y4do5
|
Are all the Pharaohs' tombs accounted for?
|
There are 62 tombs in the Valley of the Kings, are there more to be discovered? Is there a possibility of another Tutankhamen type of discovery?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/y4do5/are_all_the_pharaohs_tombs_accounted_for/
|
{
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"c5s9dxw",
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"text": [
"Without checking, no, they have not all been found yet. Egyptology has very much moved on as a field, and has shifted towards settlement archaeology away from royal tombs and palaces in a very real way, and there are many Egyptologists who claim they would rather find a workers' cemetery than a royal tomb--probably in part because Egyptology still carries the stain of treasure hunting which will never really be removed.",
"Not an exact answer to your question, but this is site is excellent for seeing exactly which tombs have been attributed to which New Kingdom pharoahs. It is interactive and allows you to see detailed descriptions, blueprints, and pictures from the valley.\n\n_URL_0_\n\nI'm not an Egyptologist, but just interested in the topic, and I looked into this a while ago. My sense was the vast majority of royal tombs have been accounted for, but there are likely plenty of non-royal burials to be found (Imhotep is a famous example).\n\nI'd love to hear an Egyptologist weigh in."
]
}
|
[] |
[] |
[
[],
[
"http://www.thebanmappingproject.com/"
]
] |
|
b6tot2
|
why are humans so drawn to the water? (srivers, seas, ocean,...)
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b6tot2/eli5_why_are_humans_so_drawn_to_the_water_srivers/
|
{
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"I don't think its so much the view that attracts people as it is the activities available there. Fishing, boating, jet skiing, sunbathing, parasailing, seafood, swimming, the wildlife, the list goes on and on. \n\nThe change of scenery is nice every once in a while. If you live in a big city with the constant traffic, noise, hustle and bustle, the allure of seeing something calming and different is something we all experience at some times.",
"I think its also not just a flat reflective surface as much as music is mere vibrations in the air. I think its oversimplifying it when thought of from that perspective. In the modern sense, I think its an escape from the busy modern life."
]
}
|
[] |
[] |
[
[],
[]
] |
|
hs9ii
|
Increasing mass of black holes and problem with relativity.
|
What I presume (correct me if wrong):
-mass falling in black holes will contribute in its mass
-gravitational effect wont "travel" faster than speed of light
-if someone observes object falling in black hole, it will seem to take forever (because of relativity)
Imagine object A falling into black hole and object B observing the event. For B it will seem to take forever for A to "vanish" in the black hole. If B had a device that would measure gravitational pull from black hole precisely, would he see the difference that the object A makes in its mass?
If not, then black holes cant grow according to observers. And if yes, how that can be if the object A hasnt falled yet according to observer?
Just a thought I came up with, im not pro in astrophysics so I guess there is a simple explanation. Hope this makes any sense, english isnt my first language. :-)
Edit: typo
|
askscience
|
http://www.reddit.com/r/askscience/comments/hs9ii/increasing_mass_of_black_holes_and_problem_with/
|
{
"a_id": [
"c1xxjlp"
],
"score": [
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"text": [
" > (because of relativism)\n\nRelativism says that Hitler wasn't a bad dude because all morals are relative. *Relativity* says that nothing travels faster than the speed of light.\n\nIf you're standing on the Earth's surface, and I ask you to tell from its gravitational field whether its mass is evenly distributed or whether it's hollow and all the mass is at the very center, can you? No: the gravitational field is the same either way.\n\nIt's the same for a black hole. According to a distant observer, all of the mass in the black hole is frozen, in a sense, on the event horizon. But due to a nice feature of general relativity, that gravitational field is the exact same as it would be if all the mass were concentrated in the center (which, according to the stuff making up the black hole, it is)."
]
}
|
[] |
[] |
[
[]
] |
|
3sdh8e
|
how hard is it to survive on minimum wage?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3sdh8e/eli5_how_hard_is_it_to_survive_on_minimum_wage/
|
{
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"text": [
"Depending on where you are, it can be practically impossible. \n\nI'm in WI, where the minimum wage was set in 2009 at $7.25 an hour and hasn't changed since.\n\nAssuming you worked a 40 hour week, this would net you about $1000 a month after taxes.\n\nFor comparison as to what that will get you here in WI, my previous dwelling was a crappy apartment in a fairly rough neighborhood on the outskirts of Milwaukee. It cost me $900 a month in rent.\n\nSo if I'd been on minimum wage, I would have had about $100 left per month to pay for food, transportation, clothing, medical expenses, insurances, gas, electric, water etc. In other words I'd have been in the red ALL the time, gradually getting further and further into debt until there was no way out.\n\nIn certain places, minimum wage is a nothing more than a joke. ",
"It... depends? It would not probably be a problem for me, but I'm extremely frugal. It could be a problem for me. There would not be much of any money left over, so if I got seriously sick or something, game over. There would be no savings there. Any one major bill would destroy me.",
"You can survive on it, but it's no walk in the park. You won't be renting a nice apartment. Maybe just a room with a shared kitchen and bathroom. No vacations, or fun money. It's just rent/food/utilities/transportation. And all of those keep going up, outpacing the income so you keep getting poorer.",
"I live in Ontario. Min wage is $11/hour.\n\nThat's $1760 before taxes and other deductibles. Let's say $1500 after taxes and deductibles.\n\nYou can rent a room in a house for about $500 in my area that provides power, water and internet.\n\nAnother $50/week for groceries means we are at about $700/month.\n\nMy insurance is $250, my gas is about $200/month just going to and from work and minor errands. And I keep $100 each month to put towards maintenance.\n\nWe are now at about $1250. Leaving about $250 a month for stuff like a phone ($30-$100/month), savings, insurance, etc.\n\nThis is assuming you have a fulltime job and already own a car. If you don't then you have to lease or else take out a loan to get a car."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
7gsnwe
|
Is the universe the same age everywhere?
|
askscience
|
https://www.reddit.com/r/askscience/comments/7gsnwe/is_the_universe_the_same_age_everywhere/
|
{
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"text": [
"Essentially no. The pace of time depends on the gravitational potential. In the Earths core time runs a bit slower: _URL_0_\nThe effect would be largest for neutron stars. For black holes \"age of the universe\" does not really apply inside the event horizon.",
"The passage of time is relative between everything in the universe, and every other thing moving relative to anything else. As well as variances in gravity.\n\nConsider a black hole that formed 10 billion years ago. There is matter, that from your perspective, is still falling into the black hole. From the perspective of the matter, only a few minutes may have passed as it falls inward. From your perspective the universe will suffer heat death before the matter passes the event horizon. The matter sees this happening in real time, in short order.\n\n\n",
"The answer is: more or less. It's not exactly the same, since time passes by for objects moving at different velocities and in different gravitational potentials, and the Universe isn't entirely uniform. Some regions are a little denser than average, and some are less dense. This is a pretty tiny effect, however: the differences in density from one region of the Universe to another are about one part in ten thousand, i.e., 10^(-5), and the age measured in these regions varies by a similarly tiny amount. Indeed, our best measurements of the age of the Universe have percent-level error, so that regional variation is still about a thousand times smaller than the *error* in our estimates of the Universe's age.\n\nTo put some numbers on all this, the age of the Universe is about 13.8 billion years, the error is in the ballpark of 100 million years, and the 10^(-5) variation between dense and underdense environments is in the realm of 100 thousand years. There are other reasons the age changes from place to place, such as other commenters have listed, but they generally lead to discrepancies far below even those relatively small numbers. One notable exception is near a black hole, where time slows down nearly to a halt as seen from outside, and time comes to an end entirely as seen from an object falling in when it hits the singularity. This is because black holes have extremely strong gravitational fields.",
"Well technically yes\nIf your measuring age by how long it has been in existence, then technically everything in the universe, all matter, has existed forever, since before the big bang. Because remember, the big bang didn't create anything, everything was already there. It just expanded and spread out the incredibly dense matter into less density",
"Isn't it theorised that the universe has been expanding continuously since the Big Bang? You could argue then that the expanding space is newborn, and therefore not the same age as the rest of existing space. Right? "
]
}
|
[] |
[] |
[
[
"https://www.sciencealert.com/earth-s-core-is-2-5-years-younger-than-its-crust-thanks-to-the-curvature-of-space-time"
],
[],
[],
[],
[]
] |
||
235e4w
|
what defines a song's genre?
|
Is there a technical defenition for each genre or is it just whatever genre the artist says it is?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/235e4w/eli5_what_defines_a_songs_genre/
|
{
"a_id": [
"cgtls76",
"cgtq5ov"
],
"score": [
6,
4
],
"text": [
"Instrumentation used, beats per minute, type of singing, key,...",
"Genres are a way to categorize music based on similar traits and attributes. Their definitions are defined by musicians, consumers, critics, and scholars as a whole. There is no objective body which defines the genres and sub-genres, which means that there is a level of subjectivity to classification, though this only becomes more of the case as you get closer to the borders between genres and sub-genres. For instance, a Metallica song is clearly different from a Wagnerian opera, which itself is very different from a rap by Tupac. \n\n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
4kjd0x
|
what causes your vision to become gradually worse? are video games and/or continual staring at phones a factor in today's society?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4kjd0x/eli5_what_causes_your_vision_to_become_gradually/
|
{
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"d3fcs5n",
"d3fdn7l"
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"score": [
5,
3
],
"text": [
"I read somewhere that there was a study done in Japan that the more time school children spend away from sunlight the worse their vision is. I have had terrible eyes since I was a child, it started about the time that I started reading books a lot and staying inside. Since I heard of that study I have been more cognisant of times I go out in the sun and look at stuff, while on a walk etc. It does seem to improve my vision for a while. \n\n Not a biologist, just an armchair scientist with bad eyes. ",
"ELI5: Changes to your eyes shape, coloration (cloudiness), the lens may begin to deteriorate, skeletal changes might cause your orbital bones to move and shift/squeeze the eye socket, changing the focus distance. You can also damage the retina with too much extreme bright light or staring at bright lights for too long. Also, if you jam a white-hot needle into your eye, that has an effect, too. Basically, anything that can affect the shape, clarity, and effectiveness of the eye can and most likely will change your eyesight, and rarely for the better.\n\nStaring at video games and phones will only make things worse if you do so when you need glasses to see closer things better. If you continue to try to view close things when you need corrective lenses, it will gradually make things worse.\n\nHope this helps! Peace!"
]
}
|
[] |
[] |
[
[],
[]
] |
||
1lgr3j
|
how can photon travel at light speed with so less/negligible energy.
|
Living organisms (humans/animals) have huge amount of energy as compared to photon. I know that our mass is also significantly higher.
But a photon can travel at light speed with so less energy! And other living things are barely moving on Earth as compared to photon.
I understand that gravity has a lot of impact on our movements. Does that mean we will be able to travel a lot faster in vacuum/space without much effort?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1lgr3j/eli5how_can_photon_travel_at_light_speed_with_so/
|
{
"a_id": [
"cbz2493",
"cbz2bpv"
],
"score": [
3,
2
],
"text": [
"Photons have literally 0 mass, as all massless particles they travel at light speed. No particle with mass can travel at light speed, no particle without mass can travel at any speed but light speed. The energy of a photon is irrelevant to it's speed, there is no mass to be moved.",
"You just barely missed the key point when you said \"I know that our mass is also significantly higher.\"\n\nOur mass is not only significantly higher, it's *infinitely* higher. A photon has no mass whatsoever, none at all. Things without mass can *only* travel at the speed of light, for the most part (it gets complicated and murky but that's not important here). Conversely, things with mass can never reach the speed of light.\n\nThere are lots of good explanations for why photons travel at the speed of light and why things without mass can't travel at the speed of light, so if you want to know more about why that is, just search \"speed of light\" on ELI5, you'll get lots of results.\n\nFor a reasonable qualitative (not completely precise) explanation of why we can have so much more energy than a photon but move so much slower, think of E = mc^(2), which I'm sure you've seen before. What it's essentially saying is that energy (E) gets tied up in mass (m).\n\nIn addition, the mass is multiplied by the speed of light twice (don't worry about why), so a lot of mass means a fuck-clobberingly huge amount of energy. The average person has as much energy \"tied up\" in their mass as a million atomic bombs.\n\nThe problem, of course, is that we can't really *use* that energy for anything, it's just stuck in the form of mass. A photon doesn't have that problem, though; it has no mass, so it can (and actually must) zip around at the speed of light with only a tiny amount of energy, because none of its energy is \"wasted\" in the form of mass.\n\nAgain, this is not a totally precise explanation of what's going on (I'm cutting a *lot* of corners), but I think it's reasonable enough as a starting point of sorts.\n\nBringing gravity into things doesn't really change much in this case, to be honest. It is certainly easier to fly around in a rocket when you're farther from the Earth or Sun or whatever, but it's not really part of the explanation of why we can't travel even remotely close to the speed of light. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
308fqj
|
Could an astronaut go back to earth without spacecraft ?
|
I mean, for example, could an astronaut leave the ISS with his space suit and a parachute ?
|
askscience
|
http://www.reddit.com/r/askscience/comments/308fqj/could_an_astronaut_go_back_to_earth_without/
|
{
"a_id": [
"cpq8atx",
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],
"score": [
22,
5,
9
],
"text": [
"From space to Earth in a straight drop: probably yes. The edge of space is [arbitrarily defined as 100 km](_URL_0_) and there has been a dive [from 41 km](_URL_1_), so that seems feasible.\n\nFrom orbit: no. Things in orbit are going sideways very fast and when they come back to Earth they get very hot from the air in front of them compressing. They also have to come in smoothly as a tumble at those speeds would be destructive. You need some heavy equipment to deal with those issues. You could of course get into what the definition of \"spacecraft\" is, but it's not going to be a spacesuit you could walk around in.\n",
"Trouble with re-entry is orbital speed. For example the ISS is moving at 4.76 miles per second relative to earth's surface. Under those velocities, the heat from drag is great but even that is overcome by the heat produced from compressing the air ([stagnation temperature](_URL_2_)) ahead of you. The space suit isn't meant to take such temperatures and you would just burn up. Re-entry vehicles tend to use ceramic plates and [ablative material](_URL_0_) to deal with the heat. You can check out this [XKCD What-if](_URL_1_) for a bit deeper explanation.",
"You are asking about what is called [Space Diving](_URL_0_). People have looked at the concept for over 80 years, however no one has actually performed one. Jumping from a commercial suborbital craft will probably be the first *true* space dive from above 100km. As for space diving from orbit, others have pointed out the issues. Current space suits used by astronauts for shuttle and ISS space walks would not survive reentry. However it is not *impossible* to design a suit that could. Insulating the space diver from reentry heat with something like [Aerogel](_URL_1_) might be one solution.\n\nOn a personal note, I would *love* to do this myself, and I would want a layer of copper foil on the outside of my dive suit so that when I reenter the atmosphere I'd burn green. 8)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line",
"http://en.wikipedia.org/wiki/Space_diving"
],
[
"http://en.wikipedia.org/wiki/Ablation",
"https://what-if.xkcd.com/58/",
"http://www.grc.nasa.gov/WWW/BGH/Images/stagtmp.gif"
],
[
"http://en.wikipedia.org/wiki/Space_diving",
"http://en.wikipedia.org/wiki/Aerogel"
]
] |
|
fhs3je
|
Graduate students and history professors, can you explain the common requirement to learn another language for grad school admissions?
|
I was just reading online that some of the graduate programs for history often require to know the written language in a specific area of interest. When did you start learning that language in order to get accepted to a graduate program? I’ll be starting mandarin sophomore year as an undergrad, and I’m worried that by the time I’m done with school I won’t be ready to enter the next level of education.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/fhs3je/graduate_students_and_history_professors_can_you/
|
{
"a_id": [
"fkd5m7r",
"fkdd5k0"
],
"score": [
4,
3
],
"text": [
"History programs at the grad level do, in the US at least, usually require at least one non-English language and there is usually the expectation that you will acquire another language during your time as a PhD candidate. The reason for this is that there is very little history where the primary source documents are in English. If you cannot understand the language of the society that you are studying then you cannot do original research, you would be dependent on secondary sources only.\n\nSince you are starting at the sophomore level you’re probably okay, two years of a language is usually what’s required. Look at the programs you might be interested in and their individual admissions requirements and build from there.",
"It is worth noting that full *expressive* fluency is not nearly as important as one might think — the important thing is to be conversant in the written language of your sources. If you are specializing in Bronze Age collapse, for example, you must be able to gloss Greek well and easily, but no one is expecting you to publish your papers in ancient Greek.\n\nIf your area of focus and interest is China, both a working knowledge of Classical Chinese *and* the ability to communicate with scholars in China will be prized, but if your interest was, say, mediæval Europe, an ability to read Latin and also communicate well at conferences in Romance languages would be useful, but no one would expect you to be communicating with foreign scholars in Latin.\n\nIf you develop a good working knowledge of one or more Chinese dialects (probably Mandarin would be the most popular choice, although someone interested in Chinese migration to the U.S. in the 19th century might prefer Cantonese, for example), it will certainly be beneficial, and one of the best ways to practice one's knowledge would be to work there for a year or two after undergrad in a non-English-speaking position. \n\nThere are immersion opportunities in a few places in the U.S. — Middlebury College in Vermont is probably the best known — but taking a Fulbright or simply a job overseas is probably one of your better opportunities to work on such a notoriously challenging language as Chinese."
]
}
|
[] |
[] |
[
[],
[]
] |
|
4dcgd6
|
how many of martin Luther's 95 theses were nitpicks?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4dcgd6/how_many_of_martin_luthers_95_theses_were_nitpicks/
|
{
"a_id": [
"d1pt6f5",
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],
"score": [
16,
47,
25
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"text": [
"Could you be a little more specific as to what you mean by \"nitpick\"? I assume you mean \"criticism that, while valid, wouldn't require Luther to leave the Church\"?",
"None of them / all of them. You are asking for a subjective answer.\n\nLuther's theses were points of academic debate. Each one is an argument against or helps construct the debate against the sale of indulgences. Which ones were nitpicks? Well, none of them are in the sense that they all are valid ways of arguing against the system of indulgences. In another sense, they do seem very repetitive to our modern ears, perhaps giving the rise to the notion that Luther was nitpicking.\n\nSome context might help shed some light on what Luther might have intended. About a month before his famous 95 theses, Luther published for debate 97 theses which addressed issues he had with scholastic theology. In many ways, this is the underlying theology that gave rise to many of the institutions of the medieval church with which Luther took issue. These theses didn't gain much traction, the debate around this issue was limited to the university in Wittenberg.\n\nSo, when Luther sat down to write his 95 theses, one month after his 97, he likely thought of this as an academic exercise. He likely was under the impression that they would be debated by a handful of academics at the university and that would be it. Luther wrote the theses in Latin not German. In short, Luther used the language of academics and theology rather than the common tongue. This gives us some idea of his notion of what he intended the 95 theses to be.\n\nWhat made this situation different was the fact that Luther was attacking, on theological grounds, a revenue stream for the Roman church. With the threat of a lucrative source of money in the air, the Roman authorities sought to quash the theses and bring Luther to heel as was their MO. The problem was that controversy bread curiosity. The Latin theses were translated into German and distributed via printing presses. This made Luther's ideas accessible. At that point, it wasn't the church verses a rogue monk and professor but rather a more complicated political issue.\n\nSo, how many of Luther's theses are nitpicks? Well, depending on your perspective, it might be most. But, considering it was an academic exercise exploring all the possable arguments that could be used, even if it's nitpicking that's what he was doing in the first place.\n\nSource: Justo Gonzalez, *The Story of Christianity*.",
"This is kind of an impossible question to answer. The *Disputatio* or 95 Theses aren't really ninety-five separate criticisms of the Church, like you'd think from the common title. The Latin title is \"A Disputation on Declaration of the Power (Force, Efficacy) of Indulgences,\" which is what the ninety-five points wind their scholastic way around.\n\nThe genius move of building a point-by-point argument like this, is that *no individual thesis seems that controversial.* Like (I use Wikisource's translation):\n\n > Christians are to be taught that he who gives to the poor or lends to the needy does a better work than buying pardons;\n\nWho would disagree with that?\n\nAnd yet, the sum total impression of the theses is that the specific manner in which the Church has mobilized its indulgences campaign *cannot help but* violate cherished, fundamental dogma. Thus, when Luther writes his major contentions, like:\n\n > We say, on the contrary, that the papal pardons are not able to remove the very least of venial sins, so far as its guilt is concerned.\n\n > [...]\n\n > We say, on the contrary, that even the present pope, and any pope at all, has greater graces at his disposal; to wit, the Gospel, powers, gifts of healing, etc., as it is written in 1 Corinthians 12.\n\nthey don't jump off the page, but rather flow naturally out of the previous.\n\nFrom there, he can question Church doctrine from the point of view of the righteous protector of the Church from within:\n\n > This unbridled preaching of pardons makes it no easy matter, even for learned men, to rescue the reverence due to the pope from slander, or even from the shrewd questionings of the laity.\n\n > To wit: -- \"Why does not the pope empty purgatory, for the sake of holy love and of the dire need of the souls that are there, if he redeems an infinite number of souls for the sake of miserable money with which to build a Church? The former reasons would be most just; the latter is most trivial.\"\n\nThe theses are a fun text to wind your way through and see how Luther builds his criticism to a crescendo--as an insider and sacred protector, not as an outsider throwing rocks at the wall."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
acxzk2
|
why is john lennon's death generally referred to as an "assassination" and not just a murder?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/acxzk2/eli5_why_is_john_lennons_death_generally_referred/
|
{
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"text": [
"Assassination is the killing of a prominent person, either for political or religious reasons or for payment.",
"I think it has to do with the nature of the killing.\n\nLennon was murdered, and so was JFK, and so was Trotsky...but so were thousands of people.\n\nIf the murder is motivated by politics, or of an important figure, and is done for motivations other than personal greed, generally it is considered an assassination.\n\nLennon's death might be stretching this a bit, though.",
"Assassination generally refers to someone famous/culturally or politically influential, while murder is the blanket term. Legally, it's all \"homicide,\" however.",
"An assassination is the killing of a prominent person. He was a very prominent pop culture figure. \n\nThe rest of us normal people only get to be murdered. "
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
20rjxj
|
How do random mutations result in naturally selected evolutionary traits across an entire species?
|
On the last episode of Cosmos they talked a lot about mutation and natural selection. I have a pretty firm grasp of the basics and think I understand the principals behind evolution. The one thing I can't seem to get is how does a single random mutation result in a change that affects an entire species.
The example of the polar bear having a mutation that results in a white cub. Was that one white cub so evolutionary superior to it's peers that a single cub resulted in the entire brown bear population in the north becoming polar bears? If not how did it happen? If that white cub would have died before giving birth did the same mutation happen over and over again? I feel like I'm missing something here.
Am I?
|
askscience
|
http://www.reddit.com/r/askscience/comments/20rjxj/how_do_random_mutations_result_in_naturally/
|
{
"a_id": [
"cg6a66e",
"cg6hysq"
],
"score": [
3,
2
],
"text": [
"It's a statistical thing. You're right, some organisms with beneficial mutations end up dying anyway because they got really unlucky. But on average they tend to be slightly more successful and pass on the mutation more often than not, and over very long spans of time, it becomes widespread in the population.\n\nRemember, mutations (at least, small ones) aren't exactly rare. They're happening all the time. An organism that originated a new beneficial mutation might also pass on one that came from its parent, and one from its grandparent, and so on. Evolution does not stop and wait for a single new trait to develop fully before any new traits emerge. It works slowly, but it is working all the time, on everything.",
"Believe it or not, this effect can even occur with *no* selective pressure, through statistics alone. This is called [genetic drift]( _URL_0_). That only applies for neutral mutations which neither help nor hinder an organism. Mutations with selective pressure easily overpower statistical drift.\n\nThe interesting thing is that the mechanism is similar: in both cases, a variant will likely supplant competing versions in a population. Natural selection is simply weighting the probability of a certain variant reproducing, which makes it far more likely that *that* variation will be the one to take over the population.\n\nHowever, note that \"population\" and \"species\" are different. In the Cosmos example, you had one species (arctic brown bears) living in various environments with different selective pressures. Way up north, in the snow-covered areas, the white fur mutation helped. Down south, the original brown coloring was more effective. So we have two populations: one where white fur helps, and one where it hinders. This will cause the two populations to become increasingly different, because they have different selective pressures. Eventually, the differences were so significant that it cleaved the species in two."
]
}
|
[] |
[] |
[
[],
[
"https://en.m.wikipedia.org/wiki/Genetic_drift"
]
] |
|
29ln3y
|
how do texting apps generate a phone number that hasn't already been claimed?
|
Is this a legal method? To not be paying service to a phone company, but to have a phone number linked to an APP on your tablet?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/29ln3y/eli5how_do_texting_apps_generate_a_phone_number/
|
{
"a_id": [
"cim4v44"
],
"score": [
3
],
"text": [
"It doesn't exactly work like, phone companies arn't the only ones who can control phone numbers. Apps can use online services such as [Twilio](_URL_0_) that allow their systems to get phone assign phone numbers and access SMS. By chain the company who makes the SMS app is paying a service like Twilio for SMS.\n\nninjaedit: didn't link right"
]
}
|
[] |
[] |
[
[
"http://www.twilio.com/"
]
] |
|
16swpz
|
At the end of battles did medieval era knights kill the opposing sides archers ?
|
I've heard before that knights usually held a nasty grudge against the other sides archers and killed off any archer pows at the end of a battle. True or False?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/16swpz/at_the_end_of_battles_did_medieval_era_knights/
|
{
"a_id": [
"c7z3g5g"
],
"score": [
3
],
"text": [
"So, I found an unsourced bit of wikipedia after some discussion with another person trying to answer your question. It states that summary execution was standard practice for prisoners of war. \n _URL_0_ \n\n\n > The bowman etymology is unlikely, since no evidence exists of French forces (or any other continental European power) cutting off the fingers of captive bowmen; in fact, the standard procedure at the time was to summarily execute all enemy commoners captured on the battlefield (regardless of whether they were bowmen, foot soldiers or merely unarmed auxiliaries) since they had no ransom value, unlike the nobles whose lives could be worth thousands of florins apiece. \n\nI do not promise that it is reliable. It seems compatible with my studies of warfare during the middle ages, but most of that focuses on \"Crusades,\" wars between Roman Catholics and non-Roman Catholics (whether the opponents were Muslim, Eastern Orthodox, or \"Albigensian\"). \nIf the opposing force were also recognized Roman Catholic, members of a retreating force would probably best be served by going to a nearby monastery or other Church property and trying to gain sanctuary in one way or another. The laws for warfare were hypothetically very strict after the Peace of God and the Truce of God, and if a combatant actually gained sanctuary, any who wanted to harm them had an incredible amount to lose if they tried."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/V_sign#Origins"
]
] |
|
3cajlp
|
why does drinking water on an empty stomach hurt?
|
Sometimes when I'm hungry, I'll drink some water and it kills. It feels like someone is wrenching my stomach. The pain is fairly debilitating, so I want to know what's happening?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3cajlp/eli5_why_does_drinking_water_on_an_empty_stomach/
|
{
"a_id": [
"cstpuvl"
],
"score": [
2
],
"text": [
"I drink warm water do you drink it cold? I won't pretend I know what I'm talking about but my mentor told me it's easier on your stomach to drink room temp."
]
}
|
[] |
[] |
[
[]
] |
|
ew4p7w
|
In WW1 why didn’t the English sail behind the front and land men to charge the Germans from the other side?
|
I heard that the Germans built their lines to face in one direction. So why didn’t the English, using its powerful navy, sail round behind them and land men to take the front?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/ew4p7w/in_ww1_why_didnt_the_english_sail_behind_the/
|
{
"a_id": [
"ffzojnu"
],
"score": [
3
],
"text": [
"While more can be said, I've previously discussed British plans for amphibious assaults during WWI in the following threads:\n\n* [\nI was listening to the podcast on the Battle of Jutland, and \"..Land a million Russians north of Berlin, and boom..The War's over in a few weeks\" caught my ear.](_URL_3_)\n* [Why didn't the triple entente stage a naval invasion behind the western front in WW1?](_URL_1_)\n* [Had the North Sea theatre been secured by the British, could the Entente have landed in Northern Germany in WW1?](_URL_0_)\n* [Was landing soldiers behind enemy trench lines ever considered by either side on the Western Front during WWI?](_URL_2_)"
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/4i5a6a/had_the_north_sea_theatre_been_secured_by_the/d2v5wbd/",
"https://www.reddit.com/r/AskHistorians/comments/5i3eog/why_didnt_the_triple_entente_stage_a_naval/db52hdv/",
"https://www.reddit.com/r/AskHistorians/comments/45l3ap/was_landing_soldiers_behind_enemy_trench_lines/czywz8v/",
"https://www.reddit.com/r/AskHistorians/comments/7se8ot/i_was_listening_to_the_podcast_on_the_battle_of/"
]
] |
|
27cgp8
|
meta: why does it seem like the same questions get asked every hour?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/27cgp8/eli5_meta_why_does_it_seem_like_the_same/
|
{
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3,
4,
2,
2
],
"text": [
"Because people don't follow the rules and don't search.",
"It's a combination of two things: not searching and there's probably an article in the news or on a popular website that brings up the question.\n\nMultiple people see the same thing that inspires the same question.\n\nThey then either ignore or don't notice the instruction to search, or presume that their question is unique or that the rule doesn't matter.",
"If you see a bunch of similar questions over the span of a couple of days, a newsworthy event or highly upvoted post (such as in /r/todayilearned or something) could have made a lot of people wonder the same thing. ",
"This is a default sub. Defaults attract the masses, and the masses tend to be rather impulsive and daft. If there's a Bitcoin story on the front page, expect half a dozen questions about Bitcoin because\n\n- user sees Front, sees story about it\n\n- user comes here to see if there's an explanation\n\n- no thread, user assumes it's because no one has asked the question yet\n\n- user doesn't realize mods are deleting the topics off /new because they are so overdone\n\nBTW OP, this topic itself is a very frequent submission. I think there have been 2 other submissions like this just today. Ironic."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
44miox
|
How much was the Soviet's space program influenced by Nazi/Germany scientists and technology?
|
The American and the Soviet program were influenced by finding blueprints of the V-2 from captured factories, as well as capturing scientists. I know that the Soviet's heavily based their R1 ICBM on the V-2, but were they influenced after the production of the R1, or did the program rely more on modified Soviet designs and scientists?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/44miox/how_much_was_the_soviets_space_program_influenced/
|
{
"a_id": [
"czrd09c",
"czrdygp"
],
"score": [
44,
4
],
"text": [
"Both the US and Soviet programs were essentially based on German rocketry in their early days, very explicitly using the V-2 as the basis of their work. The American Redstone missile was just a scaled-up V-2, and the Soviet R-7 was a clustered set of V-2-like rocket engines.\n\nBoth countries of course significantly diverged from the V-2 over time, but you could argue that all liquid-fueled rockets essentially point back to the fundamental concepts that were piloted by the V-2. Both countries also developed solid-fuel rockets that were fundamentally different from the V-2. \n\nThe countries both used their Germans differently and had different sorts of Germans. The Americans got many designers and top-level engineers (like von Braun), and they let them run things in the USA. The Soviets got many lower-level engineers, and the Soviets did not trust the Germans to outright run things. So the direct German influence was arguably more strongly felt in the US program (and you can see it in their much later rockets like the Saturn V). \n\nIn neither case was the work just copying — both countries required complete knowledge of technology in question to innovate with it, and even when they \"copied\" the V-2 directly (as they did with the A-2 and R-1 rockets) they were doing so adapting to local production requirements that were not identical to the original V-2 (thank goodness). There are also multiple ways to \"riff\" on the V-2; the US preferred scaling the whole thing up (one giant fuel tank, one giant oxidizer tank, like the [Redstone](_URL_0_)), whereas the Soviets preferred a \"clustered\" model (e.g., four rockets strapped to a central rocket, like [R-7](_URL_1_)). ",
"Read \"Red Star in Orbit\" by James Oberg. It details the early days of the Soviet space program led by Sergei Korolev, a survivor of the Gulag arctic camps, sent there when Stalin purged the Tupelov aircraft design bureau. Rehabilitated under Khruschev, and for a while still technically a political prisoner, Korolev's iron will and genius forged the Soviet space progam. \n\nNOT captured German scientists."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/PGM-11_Redstone",
"https://en.wikipedia.org/wiki/R-7_Semyorka"
],
[]
] |
|
1daray
|
why and how laundry detergents are used in the drug community.
|
[This thread](_URL_0_) popped up on /r/wtf and from what everyone is saying, detergent is used in the drug community.
I get it's used for trading and stuff like that, but I don't understand why, or exactly how everything works the way it is said to.
Can somebody explain this?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1daray/eli5why_and_how_laundry_detergents_are_used_in/
|
{
"a_id": [
"c9ojiqx"
],
"score": [
7
],
"text": [
"Some small non-chain stores will buy it from you at a fraction of retail price so they can resell it. They're also easier to steal than booze or other items that are more closely watched. If you were to steal 10 of them, and sell them at 1/4 price you could use that money to purchase drugs. Similarly, some drug dealers will accept it as a means of currency. For example. If X drug costs $10, then they will accept $20 worth of laundry detergent instead of actual money (the extra $10 for the inconvenience of being paid in laundry detergent)."
]
}
|
[] |
[
"http://http://www.reddit.com/r/WTF/comments/1da91f/you_know_you_live_in_the_ghetto_when/"
] |
[
[]
] |
|
a58adl
|
how did scientists identify humanity's common ancestor?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/a58adl/eli5_how_did_scientists_identify_humanitys_common/
|
{
"a_id": [
"ebkn8sp",
"ebm9k64"
],
"score": [
19,
5
],
"text": [
"Imagine evolution to be like a book, something written long before the invention of printing. Like the bible. So it was copied over and over by monks, who even though they worked very thoroughly, occasionally made a mistake. Since there are so many more words than mistakes, the chance that two monks do the same mistake twice are incredibly low. But the monks who use that particular book to make their own copies will copy over the mistakes in it.\n\nSo now you've got 1000 copies of the book, and want to find the one that's closest to the original. What do you do? You assume that a book can only have a particular mistake if it's the one where a monk first made the mistake, or it was copied from that book, or it was copied from a book that was copied from it, and so on and so forth. So they all must have a common ancestor.\n\nBy sorting all the books by their mistakes, you can trace exactly which book was copied from which other book. And ultimately, that will lead you to the oldest common ancestor - or at least tell you which ones are the oldest.\n\nGenetics are similar. Mutations rarely occur twice in the same way, and it's basically impossible that multiple mutations occur at the same time in a species independently from one another. So if you have two different human fossils where, say, the hip bone looks oddly similar, it might be pure chance. But if in addition to that they have a similar skull, it's safe to assume that they do have a common ancestor. So if you have a whole bunch of different fossils, you can group them by these similarities, and reconstruct which ones are the ancestors of different fossils. Ultimately, that will lead you to the oldest of the bunch.",
"Scientifically, there is no such thing as a 'common ancestor' in the sense that 'every human alive is descended from one single person'. The closest we can get is the 'Most Recent Common Matrilineal Ancestor' (MRCMA), or the putative 'Mitochondrial Eve' (a term which many scientists dislike), which you can read about [here](_URL_0_) .\n\nMitochondria are genetic 'energy factories' inside our cell-structure, and they're only ever transmitted through the female line of descent. It's possible to trace mitochondrial DNA back over the millennia until the lines of descent converge on one woman.\n\nIt's important to note, though, that 'one woman' does not mean that it's one *specific* woman, or that she was the 'only' woman alive; by definition, Mitochondrial Eve had at least two daughters who both have unbroken female lineages that have survived to the present day. Thus, mt-Eve is effectively a 'title', passed down mother-to-daughter, that denotes the *most recent* female that qualifies as 'Mitochondrial Eve'."
]
}
|
[] |
[] |
[
[],
[
"https://en.wikipedia.org/wiki/Mitochondrial_Eve"
]
] |
||
25hbwl
|
are there any laws against independent space travel without government consent?
|
If Red Bull wanted to try and send a man to the moon and wanted to privately fund it, could they attempt to actually do their own moon landing? I bring this up because it blows my mind that we haven't been back to the moon. Supposedly the tech in our iPhones is equal to or better than the computers and hardware in the Apollo (Could be total bullshit but that's what we have all heard), so we should be able to go back with ease now right? Imagine a moon landing in HD! The advertising and ratings on something like that alone would be bananas! Even with upstarts like Virgin Galactic don't really seem to be able to do much other than fly out of our atmosphere. The space shuttle program seems to have taken back a step, we go visit another planet (The Moon) and then instead of trying to build a space station on the moon, we just orbit around our earth and get the same view. Now while I am not necessarily implying we haven't been to the moon, I do find it puzzling that we have not attempted to explore that planet more
TL;DR If Red Bull wanted to fund a moon landing would they be allowed to? If not why?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/25hbwl/eli5_are_there_any_laws_against_independent_space/
|
{
"a_id": [
"chh5x1w",
"chh6jov"
],
"score": [
8,
10
],
"text": [
"Sorry I don't know the answer to your question but please stop calling the moon a planet. Its not a planet its a planetary satellite. Planets are things that revolve around the sun, moons are things that revolve around planets.",
"Lawyer here! The answer to your core question is \"generally, no.\" Most spacefaring nations require compliance with statutes/regulations before they'll permit a private entity from launching.\n\nIn the U.S., for example, private launches are controlled by the [Commercial Space Launch Act of 1984](_URL_1_). This requires a substantial amount of regulatory compliance. For example, the company has to submit an environmental impact report to the EPA, and has to obtain quite a bit of liability insurance (among other things) before they can launch.\n\nMost countries have something similar. The [UN Outer Space Treaty](_URL_0_) (a real thing) seems to contemplate (without explicitly requiring) that we're only going to have state-sanctioned spaceflight. Specifically, it assigns liability for any losses in space to the nation that authorized the launch of the craft responsible.\n\nEdit: Now with links!"
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Outer_Space_Treaty",
"http://en.wikipedia.org/wiki/Commercial_Space_Launch_Act_of_1984"
]
] |
|
38bzih
|
do websites make absolutely no money off ad block users?
|
like not even a cent? or do they make some but not as much as a non adblock user?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/38bzih/eli5do_websites_make_absolutely_no_money_off_ad/
|
{
"a_id": [
"crtwi40"
],
"score": [
4
],
"text": [
"Free websites that rely on ads make no money off any users, whether or not they use ad block. Instead they make users off businesses who buy their ad spaces. These business make extra money by attracting new users/customers to their paid services/products.\n\nPeople who use ad blocks are not exposed to these ads, so if a website has a quarter of its users on ad blocks, their ad spaces would be exposed to a quarter less than what it otherwise would, and those business would see a less increase on buyers of their services/products, which means the ads are now less valuable.\n\nThis is how free websites suffer from ad blocks."
]
}
|
[] |
[] |
[
[]
] |
|
vgjze
|
Can swallowing gum act like fiber?
|
Can swallowing gum act like fiber, and aid the body with its regular doodee flow?
|
askscience
|
http://www.reddit.com/r/askscience/comments/vgjze/can_swallowing_gum_act_like_fiber/
|
{
"a_id": [
"c54chvp"
],
"score": [
11
],
"text": [
"Not really, it won't bind water or break down enough to add bulk to you faecal matter. Fiber also has many other dietary benefits such as cholesterol regulation and nutrient absorption of which gum would obviously not help, but I'm assuming you meant mostly with respect to bowel movements."
]
}
|
[] |
[] |
[
[]
] |
|
8jmlln
|
is the air around me packed full of atoms, like peas in a can, or is there space between? how can i see through it? are atoms transparent?
|
I know that an atom is mostly empty space, but every atom has a "solid" particle at the center, doesn't it? There must be gazillions of those things all around me.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8jmlln/eli5_is_the_air_around_me_packed_full_of_atoms/
|
{
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"dz0qy3x",
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"dz0u506",
"dz133fz"
],
"score": [
8,
5,
2,
3
],
"text": [
"It's like looking through a screen door, but much, much farther apart. They aren't transparent, but when spread out, you have no issue seeing through it.",
"When we say mostly empty space we mean that dense center is a baseball sitting in the center of a football field. Its a lot of empty space.\n\nBut yes many atoms let visible light through, they absorb/reflect in different ranges depending on their electrons (thats how colors work).\n\nThey are mostly pretty packed with 6.02*10^23 atoms per 22.4 liters.",
"You can only see through it for short distances. Look at something further away and you'll notice a blue/grey haze. That's air.",
"[Solids](_URL_1_) are packed like peas in a can.\n\nLiquids are actually loose enough that they move more like cars on a highway (at rush hour).\n\nAnd gases (like air) are more like [people on a sidewalk](_URL_0_).\n\nHowever, transparency is not quite related to \"relative size\" or photons being \"blocked\" by a wall of atoms. Because we clearly can have transparent solids, as well as various gases that don't let light through.\n\nAt the \"elementary particle\" scale, things tend to vibrate a lot, and also have not very precise locations. And the wavelength of photons can be bigger than the size of the atoms that make up the material. So absorption or reflection of light depends on whether the atoms in the material can absorb the energy of the photons, or not."
]
}
|
[] |
[] |
[
[],
[],
[],
[
"http://ak6.picdn.net/shutterstock/videos/4062466/thumb/4.jpg",
"https://i.pinimg.com/originals/0b/03/68/0b0368f4d6e909a6c0d31c4bfb07c7cc.gif"
]
] |
|
49qq7g
|
Questions about Longstreet's plan of disengaging at Gettysburg and matching to the right.
|
Longstreet famously claims he wanted to disengage at Gettysburg and march to the right to place the Army of Northern Virginia on good defensive ground between the Army of the Potomac and Washington DC.
What good defensive ground(s) lie between Gettysburg and Washington DC?
Given the road network available to both sides, and assuming the Army of the Potomac also try to keep themselves between the Army of Northern Virginia and Washington, could the Army of Northern Virginia actually arrive there before the Army of the Potomac?
EDIT: Title should say marching to the right orz
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/49qq7g/questions_about_longstreets_plan_of_disengaging/
|
{
"a_id": [
"d0uf7eo"
],
"score": [
2
],
"text": [
"its hard to say exactly which ground L. is talking about. Obviously the Pipe Creek area is what Meade had in mind but that presumably would already be taken. The area around Emittsburg has some high hills, you can see them from route 15; they must be some sort of extension of the Cactoctin Mountains, which I guess the Round Tops are as well. Emittsburg and those hills are far enuf away from Gettysburg, I cant imagine they would have any influence on a battle being fought there. Which makes it hard to understand if Meade will attack L. there. \n\n The Frederick MD area would probably be pretty good ground. As its a road hub and it seems to be higher ground than the surrounding area in all directions. The Cactoctin mountains are a bit to the west and would really not have any command of that city. \n\nIt seems that occuyping Frederick MD (which Lees army did the year before) would place them in a very exposed way as there's no easy covered route back west to the mountains, it is all rather open. But but I guess that would be the idea. Longstreets plan is very refective of Jomini and his theory of maneuver. I dont really ever recall seeing Longstreets exact writing and thinking on this idea, although Freeman is very critical of L. at Gettysbg. I dont recall Freeman ever commenting on this actual idea. \n\nYour second question about whether they would arrive there first is a pretty good question. I guess the idea is that the Army of the Potomac is so braced for defense that they will not be patrolling or have any idea what Lee is up to. Given the way the AoP operated that's not a bad assumption. Note that when Lee retreated the day after Gettysburg; Meade made no immediate attempt to interrupt im although there were many skirmishes in the weeks that followed. None of those battles feel as though Meade is really trying to come to grips with Lee. \n\nThere was some manuevering at Manassas Gap (?) where French's federal corps failed to bring on a battle in August; which seems typical for that summer and fall. Perhaps L. is banking on this lack of agressiveness on the part of the federals? Lee himself is often mentioned as studying his opposing number in order to figure out what they will do. He knew Meade would fight well on the defense, he figured Hooker would fall back etc. So maybe L. is taking a page out of Lee's book? \n\nThe other problem is that Ewells' entire corps is north of the town of Gettysburg, so it would be hard to march south with out leaving them out to dry. it seems very risky. Maybe the idea is that Ewell can retreat to the west via Cashtown or some other gap in those mountains? \n\nThat seems very risky. Lee almost met disaster the year before when he broke up his army into sections and MaClellan found his orders. \n\nI'd have to read exactly what L. was proposing. I''ve certainly heard it mentioned before but not sure exactly what the plan was. Perhaps L. means to have some sort of turning movement, while Ewell attacks in the northern sector in order to hold Meade and Longstreets turning movement doesnt exactly hit Meade's flank but rather find some ground to the south. \n\nIt's all very Jominian in concept. Lee was not a student of Jomini as I understand it. He was more of a Napoleonic school: concentration in time/space, and using geography to screen movements sort of thing. \n\n "
]
}
|
[] |
[] |
[
[]
] |
|
4nthjg
|
why does weather move from west to east, but wind can be blowing from any direction?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4nthjg/eli5_why_does_weather_move_from_west_to_east_but/
|
{
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"text": [
"Winds also flow differently between pressure systems. \n\nLow pressure system, wind tends to flow counter-clockwise\n\nHigh pressure system, wind tends to flow clockwise",
"Weather doesn't have to move west to east. Look at the Hurricanes! They move southeast to northwest on the east cost of North America. ",
"The wind that you feel is created because of a difference in temperatures, resulting in a difference in pressures. As an example: all day, the land and sea are warmed up a bit by the sun. As the sun sets, the sea cools faster than the land. Cold air sinks, and hot air rises. So the hotter air over the land rises, creating a lower pressure area. The cooler, low air from the sea (which also happens to be higher pressure), rushes into the area with lower pressure, causing wind. And the hot air that was above the land moves back over the ocean, cools, and the cycle repeats. Remember, this is happening on a massive scale. Also remember that this is only one common example. There are many other reasons for wind generation. ",
"The wind that you feel is created because of a difference in temperatures, resulting in a difference in pressures. As an example: all day, the land and sea are warmed up a bit by the sun. As the sun sets, the sea cools faster than the land. Cold air sinks, and hot air rises. So the hotter air over the land rises, creating a lower pressure area. The cooler, low air from the sea (which also happens to be higher pressure), rushes into the area with lower pressure, causing wind. And the hot air that was above the land moves back over the ocean, cools, and the cycle repeats. Remember, this is happening on a massive scale. Also remember that this is only one common example. There are many other reasons for wind generation. "
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
d53zhy
|
how does the electric company categorize my usage?
|
I have service with Duke / Progress energy. Every month I receive a breakdown of what categories I’ve spent my electricity on - lighting, cooking, cooling, etc - how can they know this information? Is it based on usage cycles, or some kind of per-breaker tracking?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/d53zhy/eli5_how_does_the_electric_company_categorize_my/
|
{
"a_id": [
"f0js32m"
],
"score": [
4
],
"text": [
"They use something called Power Signature Analysis. Basically, you have to imagine your homes power usage as a graph. When you turn something on, there will be a small increase in the graph, and decrease when it's turned off. Certain devices create patterns in usage. This data includes both voltage and amperage. Smart Meters transmit this data to the power company and they use special software to analyze the data.\n\nDevices that use large motors often times create huge spikes in amp draw, which also causes a drop in voltage. Devices such as air conditioners and refrigerators use large motors. Light bulbs will create very small loads with no initial spike. Devices such as space heaters, toaster ovens and electric ranges, that use electricity to create heat, also do not create large spikes, but will create a very high and steady draw of amps. Washing machines will often times create erratic loads, as they are constantly turning their motors on and off, and running them at different speeds.\n\nSmart Meters are also capable of measuring power factor, so they may also take that number into account. Most people are not billed for power factor, but it can give hints as to what type of devices are running inside the home."
]
}
|
[] |
[] |
[
[]
] |
|
24qm2u
|
Why didn't artillery in WW1 render trench warfare useless?
|
This may be silly, but it always seems to go by without much information in non-fiction ww1 accounts, and history books growing up. I'm aware the Germans used some pretty serious artillery against belgian forts at the beginning of the war, and I'd imagine the real problem could have just been the logistics of getting big cannons to the fronts without railroads.
I'm a bit out of my depth, and I'm curious as to why artillery didn't nullify a lot of the protection that trench warfare offered combatants. Thanks for any info.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/24qm2u/why_didnt_artillery_in_ww1_render_trench_warfare/
|
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"text": [
"There are two main reasons that I can think of as to why artillery didn't render trench warfare useless. \n\nEarly in the war an issue that the British in particular faced was the reliability of shell fuses. Leading up to an assault like the beginning of the Battle of the Somme, artillery was easily capable of firing tens of thousands of shells over a few days. However, only a portion of those shells would actually explode when they hit the ground. Typically this was caused by the mud being too soft and the shell would just bury itself without triggering the fuse. The issue was sensitivity. There is anecdotal accounts that after the massive pre-Somme bombardment it was possible to walk across no-man's-land on a carpet of unexploded shells. \n\nThe second reason why artillery didn't render trench warfare useless ties into the sensitivity of fuses and reliability of shells. If you fire tens of thousands of shells at the enemy leading up to an assault, the shells will churn up the ground to an unusable level. This became an issue during the now infamous Battle of Passchendaele, when the already damaged drainage systems in the area were shelled and saturated the constantly agitated soil.\n\nThese two factors worked together to degrade artillery's status from a presumed war winner to just one part of the combined arms tactics necessary to succeed on the Western Front.",
"It’s a good question. One answer is the lack of High Explosive (HE) shells. In 1914, shrapnel shells were far easier to produce because the metallurgical and chemical components were more straightforward. Indeed, within the British army, the first HE shell for the 18-pounder field gun (the standard field artillery piece for the British and Dominion forces during the First World War) was only tested in October of 1914, two months after the beginning of the war. In all countries, the manufacture of artillery shells couldn’t keep pace with the rate of expenditure and even as late as the end of 1915, there was a backlog of thousands of HE shell casings within British munitions factories because the procedure for filling them was so complex. British production of HE shells only caught up with the production of Shrapnel shells in March of 1916. The lack of HE shells made destroying earthworks and trenches difficult.\n\nWhat happened after the manufacturing of HE shells caught up with expenditure? Not a lot. Obviously the destructive capabilities of artillery increased dramatically but by 1916 both sides were firmly entrenched. We can use the example of the Somme to demonstrate the failure of artillery as the sole means of destroying defences. The preceding artillery bombardment was intended to destroy German defences and cut the barbed wire. It did neither. The German’s garrisoning the front line survived the bombardment in their deep and well-constructed dugouts and emerged (though shaken), ready to defend their line which they did to great effect to the detriment of the attacking troops. Techniques such as the *Moving Barrage* or *Creeping Barrage* had been developed but not perfected and the barrage frequently moved faster than the infantry could to keep up with it, leaving them exposed. Greater cooperation between artillery units and the infantry was needed but due to poor communication, this wasn’t possible until later in the war.\n\nThe other thing that needs mentioning is that there were relatively few troops in the front lines except when an attack was looming. The majority of troops were held back as reserves to be moved up if the enemy attacked but until then were relatively safe from artillery fire. If the front line was hit, those troops would retreat to the safety of their dugouts as the Germans did on the Somme and emerge when the barrage had lifted. \n\nLater in the war, artillery would play a far more tactical role, shifting from a role purely bent on the destruction of enemy trenches and fortifications to a role of neutralisation. By 1917 the creeping barrage had largely been perfected and had become a regular tactic during attacks against trench lines. As the artillery barrage crossed trench lines, the infantry following close behind would enter and clear the trench while the artillery prevented enemy reinforcements from reaching their beleaguered comrades. While effective, the tactic didn’t always translate into success. The German defensive lines were deep and attacking units were inevitably worn down clearing trenches and were often unable to exploit and breakthrough they may have occurred. This changed in 1918 when the Hindenburg Line was breached. A combination of artillery, tanks and infantry attacked German lines. While one infantry unit cleared and held a trench line, another fresh unit would continue forward, continuing the pressure put on German defenders. This was known as leapfrogging.\n\nHopefully that answers your question. Like all things, practice makes perfect and the use of artillery in the type of warfare seen on the Western Front went through a huge learning curve. Unfortunately while we usually view failure as a learning opportunity, failure in this case meant the deaths of thousands of men.\n\nSource: *Battle Tactics of the Western Front: The British Army’s Art of Attack, 1916-1918* by Paddy Griffith.\n\n*The Great War* by Les Carlyon\n\nEdit: Corrected year\n",
"You seldom find a single weapon platform completely dominate warfare.\n\n\nYes, artillery was important, but you're still firing an artillery shell. Not only had chemistry not entirely caught up with the new weapon system (the Incendiary Round and similar high-explosive weapon ordinance weren't *quite* there- TNT had only been realized to be a *very* useful explosive ordinance about a decade prior) but you were using a very inaccurate weapon platform to hit a *very* narrow target- slit trenches made it very difficult to hit what you wanted. \n\n\n\nFurthermore between the dead zone artillery and machine guns induced, on the off chance saturated artillery strikes cleared an area, there'd be enough time for new troops to flood in, set up, and repel any charge.\n\n\n\nThe real issue was that the internal combustion engine hadn't yet come into it's own. Tanks (and lighter vehicles) were grossly ineffective at their job, and aircraft still couldn't manage a noteworthy load. ",
"Fusing had a lot to do with it. The VT fuse wasn't invented until WWII and even then it was considered so valuable that it wasn't allowed to be used if there was a possibility of it falling into enemy hands (until the battle of the bulge). The VT fuse uses a primitive form of radar to provide a consistent air burst at a constant height above ground. This is incredibly effective because the explosion of a shell is predominantly spherical so when it explodes in the air it can do damage to a lot of targets on the ground, including targets inside a trench or foxhole. Without VT fusing a shell either has a timer to explode in the air or explodes on contact. Timers are extremely difficult to get right and rely on a combination of many shells to eventually get a lucky hit that does the damage you want. Ground burst shells have the problem that a lot of their explosive power is uselessly directed upwards or downward. They dig a crater and provide a small radius of lethal damage. But heavily dug in targets that are just a few meters away might survive injury.\n\nTo take out a target in a trench you would need a direct hit, and then only the soldiers in that small section of the trench would be killed (since trenches were designed with zigzags to protect against artillery hits).\n\nArtillery is tremendous for taking out exposed targets. If you have, say, a building, an airfield, a warehouse, a train station, etc. then artillery can smash it in a matter of hours. But trenches are actually one of the best defenses against artillery, aside from completely underground tunnels.",
"Two additional things ( that are not mentioned by the other comments): \n\n1) With a trench you need to hit the trench in order to be effective. For illustration ( that is I am guessing the numbers) lets say that a artillery shell will kill ( or badly wound) anybody within 5m of the explosion. In open field this are roughly 80 m^2, in a 1m broad trench this are just 10 m^2. \n\n2) The trench systems were not simple trenches, but had bunkers incorporated into the trench, so during a artillery barrage the opposing soldiers would not actually be in the trench, but in the bunker. ( And only take position in the trench when the barrage stopped. "
]
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[],
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1h0xnk
|
how can you measure the speed of light if nothing goes faster than its speed?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1h0xnk/how_can_you_measure_the_speed_of_light_if_nothing/
|
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"Speed = Distance / Time\n\nYou don't need a on object with a similar or greater velocity to compare it to. \n\nNow here's a fun way you can confirm it at home:\n\nRemove the rotating plate from your microwave, and place an upturned plate over the rotor in the middle. Butter about 4 slices of bread with an even covering right to the edges, and lay out flat in the microwave.\n\nTurn on the microwave, and watch carefully: you should see the butter bubble up in spots on the bread.\n\nStop the microwave, and measure the distance between two of these splotches. \n\nThen flip the microwave around and look for an information sticker. It should have the frequency listed (either in MHz or GHz).\n\nThen, multiply the wavelength (distance you measured between splotches) by the frequency (number you read on the back of the microwave oven), and you get the speed of light. ",
"Light still takes time to travel. So you can work out the speed of light by having a light source, a light detector, a clock and a mirror.\n\nPlace the detector next to the light source, and the mirror a certain distance away. Rig the clock to turn on when the light starts and to stop when the detector sense the light from the reflection in the mirror. You can then work out the time the light took to travel between the source the mirror and back to the detector, hence the speed.\n\nOther methods have existed too using astrological information. There's a summary [here](_URL_0_) "
]
}
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[],
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"http://www.speed-light.info/measurement.htm"
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3v8u54
|
What is "real politik" and how was it applied in Europe?
|
Thanks for your support!
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3v8u54/what_is_real_politik_and_how_was_it_applied_in/
|
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"This is a very broad question and so I'll do my best to supply you with a general definition and then a specific example. You might get an answer closer to what you're looking for by narrowing down the question on time period and geography.\n\nRealpolitik is at its heart the setting aside of \"ideological\" motivations when crafting political or diplomatic decisions, and instead focusing on materialistic concerns. A diplomatic decision based on ideology would be: \"I'm a Catholic King, my neighbor which is a Catholic country is being attacked, I should help defend them.\" A decision based on realpolitik would be: \"I'm a Catholic King, my neighbor which is a Catholic country is being attacked, I should attack them too and take as much of their territory as I can while they are weak.\"\n\nOne excellent example of this comes to us from the Thirty Years War. In 1618 the Catholic emperor of the Holy Roman Empire, Ferdinand the Second, had recently sent two Catholic governors to Bohemia to oversee the administration of the territory. The Bohemians were heavily Protestant and worried that they would be losing their recently acquired religious freedoms, and so they threw the representatives from a window. This is often cited as the origin of the war, and while the war did start along religious lines, with the Bohemians calling upon the Protestant Union for aid and Ferdinand calling upon Catholic Spain to help put down the revolt, as the war progressed the tone and nature of the war fundamentally changed. \n\nWhen France entered the war, one would expect that the devoutly Catholic country and her chief minister Cardinal Richelieu would enter on the side of the the Holy Roman Empire and Catholic Spain; however, the Cardinal was one of the first masters of realpolitik and often described as a Machiavellian in his political scheming. Spain and the Holy Roman Empire were choking France which was pressed in on by Hapsburg territories. The Cardinal's chief objective was to secure as much power for France as he could, and so started supplying aid to the Protestants. Not only did France encourage, supply, and pay Protestant Sweden to engage in war against Spain and the HRE, but France itself would openly enter into hostilities as well. \n\nIf France had based its foreign policy on purely ideological grounds it would not have funded Sweden's war against Spain and the HRE nor would it have openly entered hostilities against Spain and the HRE; however, since the Cardinal based his foreign policy decisions on acquiring as much land, wealth, and power as possible, since he followed a realpolitik approach to foreign policy, he did just that.\n\nThe Thirty Years War: The Holy Roman Empire and Europe 1618-48 By Ronald G. Asch\n"
]
}
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[
[]
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1p4kw2
|
Why were poor whites in the Southern States usually pro-slavery, when in all likelihood, it made their lives more difficult?
|
This is something that's always puzzled me when looking at the Civil War and the years leading up to it. It seems to me that slavery would have almost exclusively benefited the planter aristocracy and left poor and middle-income whites unemployable (seeing how they had to compete against slave labor) or unable to purchase their own plots of land (since the planter aristocracy would be able to gobble up the most valuable land).
Why then did the vast majority of them join them fight so hard against its abolition? It seems to me to be an instance of people voting (or literally fighting) against their own interests.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1p4kw2/why_were_poor_whites_in_the_southern_states/
|
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"Think of the antebellum South as a hierarchy, with the planter elite at the top, and the black slave at the very bottom. Directly above the slaves were the poorest white people. Regardless of how they fit into the rest of white society, they still exerted power over the lowest group in the pyramid. The American slave system rested heavily on the nature of this balance of power. Even the poorest white farmer was better off than any slave in terms of their freedom. Many supported the system because it provided a power structure that prevented their low paying jobs, and status, being threatened by black equality. \n\nThis is critically important if we are to understand the reaction to the collapse of the slave system after the Civil War. ",
"Don't have the book in front of me, but this is from *Battle Cry of Freedom*, by James McPherson.\n\nTwo main reasons:\n\n* Aspirations of slave ownership. Just as poor whites in the North often worked towards owning property, poor whites in the South often dreamed of owning slaves.\n\n* As folsom_prison said, the social order put free (even poor) whites well above slaves.\n\nIt's also worthwhile to note that not all whites supported slavery. During the Civil War, many poor whites fought simply to defend their homeland and their social structure. This was helped by Southern propaganda that proclaimed that the North would elevate blacks equal to or even above the status of whites.\n(edited for formatting)",
"The best answer to your question can be found in Rachel Klein's \"Unification of a Slave state\". A complicated mix of social structures, politics, economics and religion all coalesced to bring the whites of South Carolina together, even though many non slave owning whites had no chance of owing slaves or joining the planter elite. This is only an answer for the state of South Carolina however. The fight against abolition varies from region to region and from state to state. Some states, such as Virginia, had an entire break off from them. Although West Virginia was able to succeed with lots of Union help. In other states, such as North Carolina, the mountain regions held allot of Unionist sentiment and became areas were deserters or draft dodgers could flee to. And yet other states, such as South Carolina had a large amount of men fight for and support the war and the main amount of political discord happened as a result of other matters, such as the Confederate congresses' secret council or South Carolina's Executive Council.",
"Not all poor whites in the South were pro-slavery. In Appalachia, for example, there were few planters and few slaves. They knew that their state governments were set up to favor planter interests, and that they themselves were economically and politically marginalized. Their geographic location meant they had no aspirations to become planters. Therefore, while they certainly weren't abolitionists, they weren't invested in slavery, and many opposed the Confederacy during the Civil War. Examples were West Virginia and eastern Tennessee.\n\nIn other words, as people in this thread have pointed out, those poor whites who supported slavery hoped to be slaveowners themselves, which means they lived in the plantation belts. They looked up to the wealthy planters who lived in their counties and voted for them. They had economic relations with them, as the planters might be the only ones in the neighborhood with the resources to transport cotton to market. Keep in mind that cotton was extremely profitable for most of the antebellum period, and yeoman farmers without any slaves could conceivably get by, meaning that there wasn't a sharp divide between haves and have-nots. Lots of small farmers owned just one or two slaves, and hoped to invest in more in the future.\n\nThe classic answer to your question is that poor whites supported slavery because it guaranteed that no matter how poor they might be, they would never be at the very bottom of the social hierarchy. Some historians call this concept \"Herrenvolk democracy,\" a government that serves the interests of a master race. You question why these poor whites would vote against their own interests; poor whites believed that supporting white unity and the planter class was a surer way of getting their interests addressed. Slavery which was reserved for Blacks only strengthened the white brand, and there were concrete advantages that went along with this.",
"The other thing that I don't think anyone has brought up yet is that many white people who didn't actually own slaves could still benefit economically from slavery. Overseers are an obvious example, but there are others: for example, *Soul by Soul* by Walter Johnson gives an example of a bartender who facilitated slave trades on the side. On paper, these were poor or middle-class people who didn't own any slaves, but they still made money from slavery.",
"They didn't join the fight against its abolition. They joined the fight to protect what they perceived to be their homeland and their culture. Take a look at the Confederate civil war songs. How many of them mention the institution of slavery? Why is that, if that was the rallying cry? Because it wasn't. \n\nSlavery was the main cause for secession. It was not the main cause for confederate soldiers to fight. Don't get me wrong: Most of them were racists, but they fought for different reasons.",
"In the 1670's, the colonists who were settled in Western Virginia were at constant threat to raids by the Native Americans. Now, who were these colonists? They were not the wealthy tobacco farmers who lived close the Chesapeake Bay. Instead, they were relatively poor, and mostly free indentured servants, who were given their promised piece of land, to find it to be not nearly as valuable as the land they worked on prior to being freed.\n\nThey petitioned the Governor to build outposts in the western portion of the colony. Governor Berkeley thought the idea was okay, allowed for the outposts to be built, but wanted the poor farmers of the region to pay for it. \n\nThis angered the settlers to the point where led by Nathaniel Bacon, they marched to the capital in revolt. On there way, Africans, both freed and enslaved joined them. Ultimately, it was realized by all those involved, the poor settlers, the Africans, and the colony elite, that the poor settlers and the Africans had a lot in common in terms of their position in colonial Virginia.\n\nNathaniel Bacon died and the rebellion fell apart. But the colonial elite realized they had to do something. While some societal concessions were made to the poorer farmers of the west, for example, they received the vote in the House of Burgesses, perhaps the more important result was that the colonial elites began to pin the poor whites against the Slaves.\n\nThis is perhaps best exemplified by poor Whites getting employed as run-away Slave catchers. While prior to the rebellion, a poor White farmer might see a run-away Slave, remember how much it sucked being an indenture servant, think about how hard he works to keep his farm now, and how unfair it is that some rich man to the east has slaves to do all his work for him, and decide to help the Slave, now the poor Whites are being given the sole task of hunting down these run-aways. The relationship between the poor Whites and Slaves was completely turned upside down.\n\nNow lets fast forward a couple hundred years. Douglass' narrative is perhaps the best first hand account we have about the relationship between Whites of all economic standings and Slaves in antebellum America. At one point, Douglass' owner believed he was being to rebellious, and needed to be broken in some. Because of this, Douglass was sent to Convoy's plantation. Convoy was a poor White, who was able to get Slaves for free because he promised the elites of the area that he would take rebellious Slaves and beat the rebellion out of them. So here's a poor White who's economic well-being relied on Slavery. \n\nSlave breaking and Slave catching were two of several jobs that poor Whites would hold that while not making them Slave owners, made them economically dependent on Slavery, and decisively pinned against Africans.\n\nForget all the comments in this thread that talk about how Slavery made even the poorest White superior to the Africans. While this is part of it, I think a more important point, the point that you should take away from the thread, is that *the poorest Whites, despite not owning Slaves themselves, were still often economically dependent on Slavery.* "
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1lchfc
|
what determines if you are burning fat, muscles or calories?
|
Does it depend on your hart rate or what you had to eat before or after working out? Does the type of workout matter?
Edit: Thanks everybody, a lot of useful anwers in here!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1lchfc/eli5_what_determines_if_you_are_burning_fat/
|
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"a calorie is a measure of energy. the food you eat provides a certain amount of energy, measured in calories. your body uses a certain amount of energy (calories) every day just to support regular functions. at the end of the day, any unused energy gets stored in your body as fat. when you work out, your body needs energy, so it starts to \"burn\" fat so it releases its energy. why arent fat people bursting with energy? well, fat doesnt do anything, muscles do. fat stored as fat is just dead weight and makes it that much harder for your muscles to do their job. you need to get active and have your body use that energy stored in the fat. the energy released from fat is measurable in calories, so thats why when you work out you can gauge how many calories you have burned. only in cases of extreme starvation will your body start to burn muscle, after it has gone through all of your fat",
"I assume you meant \n\n > What determines if you are burning fat, protein, or carbohydrates?\n\nIt is dependent on a number of factors, the type of exertion does not matter. Running or weight lifting alone do not determine which energy source your body uses. As I think you meant to say, there are three energy reservoirs our body can use: fat, protein and carbohydrates. Generally speaking you have three states, resting, moderate and heavy. Resting is sitting on the couch or sleeping. Moderate is walking up the stairs, hiking, lifting weights. Heavy is sprinting, marathon running and such. For a average person, your body burns carbohydrates the vast majority of the time, and almost never protein, regardless of your activity level. There is always some small level of fat being burned as well. At a moderate level, you burn a higher percentage of fat than at rest or at a high activity level, but because you burn more calories overall at a high activity level, you don't burn more fat at a moderate level. This is why those fat burning zones are actually BS. An average person will burn through their carbohydrate sources fairly quickly, so the body will switch over to fat burning. Fat has a higher energy density than carbohydrates, that's why we store a lot of fat and very little sugar. Athletes have been shown to almost instantly switch to fat burning during activity. Your body will burn protein only if you are starving.\n\nTL/DR; Your activity level and duration determine what your body is using for energy ",
"The body will burn through carbs (in the form of glycogen) first, then once the glycogen stores are depleted, it will switch to burning through fat. Once all the fat and glycogen are gone (as mentioned in another response - if you're starving), the body will start to burn protein for energy.\n\nAfter reading some of the responses here, I think it should be noted that while it is *possible* for the body to convert carbs into fat (Lipogenesis), it rarely or never happens in our bodies. We get fat from eating carbs because our body burns carbs first. If your body always has enough carbs (glycogen) to burn for energy, it never get around to burning fat for energy, so all the fat you eat gets stored.\n\nBasically, our body - like everything in nature - takes the path of least resistance. Carbs are the easiest to use for energy, then fat, then protein.",
"_URL_0_\n\nYou're welcome",
"Calories are measurement of energy - everything you eat has a calorie count.\n\nIn general the following conversions exist:\n\n* 1g Protein = 4 cal\n* 1g Carbs = 4 cal\n* 1g Fat = 9 cal\n\nWhat you eat, in what ratios, combined with when you eat and work out are all very important factors in what your body does with the food. The problem is, every single person is different, so there is no magic formula of what to eat.\n\nFirst let's talk about how each type of food is used by the body:\n\n* Protein is used primarily for muscle repair and growth. Additionally, what I haven't seen anyone comment on here, is that it can also be broken down and slowly converted to glycogen to be used as slow burn energy source.\n* Carbs are used primarily for energy. Depending on what the carb is determines how fast it is absorbed in your body.\n* Fat (you eat) can also be used as an energy source, but is mostly broken down to provide your body with nutrients used in natural body function. You also get most of the fatty acids your brain needs to function from fat sources.\n\nOk, now that we know what these things do in food - how do they affect your body.\n\nWhen you eat food, starting in the mouth it goes through the digestion process. Different parts begin to break down at different speeds - simple carbs (sugar) get broken down fast, complex carbs and proteins take much longer. Think of this like throwing wood on a fire. Twigs burn up right away, logs burn low and slow. The digestion process breaks down the sugars and converts them into glycogen to be stored for later use - note: food is not burned directly, first it's converted, then stored, then the stores are burned as a fuel source.\n\nWhen you eat, anything, your blood sugar will rise as your body starts processing the sugars in the food. This causes a release of insulin to regulate your blood sugar. Insulin is a double edged sword though. It lowers your blood sugar by forcing the sugar in to your glycogen stores (muscle fuel tanks) BUT insulin is unaware of how much sugar it's going up against, so generally too much insulin is released and all of that sugar is forced somewhere - when the muscles and liver are full, that somewhere is in to fat cells.\n\nThere's also a nasty byproduct of insulin - the double edged sword - you can't burn fat when your body is pumped up with insulin, as it it's in the process of storing fuel. You can't be starving and full at the same time.\n\nSo that covers the eating portion. Now for the burning.\n\nAs someone else said - there are 3 states of burn: resting, aerobic (enough oxygen), anaerobic (not enough oxygen). In all 3 cases your body is burning the stored fuel in your system, just in different ways.\n\nWhen you're resting, your body can generally burn through the glycogen in your muscles slow enough that your slow burn digestion (complex carbs and protein) refills the stores at the same rate so you don't notice a lack of energy or fatigue when sitting around.\n\nWhen you do low intensity exercise, 60-70% your max heart rate, where you can still breath properly, you burn more energy obviously then when sitting around. This is when those glycogen stores really get tapped - first the liver is emptied, then the muscles.\n\nIf you do high intensity exercise, 70%+ your max heart rate, where you run out of breath your body needs quick energy because it can't go through the normal process due to the lack of oxygen - so usually the muscles are tapped directly. Because muscles, per muscle, store a lot less glycogen this process can only be sustained short term. There's reasons you can't sprint for more than a few minutes.\n\nIn all 3 cases, fat is also being burned along side your glycogen stores - remember (above) how fat has way more calories then protein and cabs, well that makes it a good energy source. As you deplete the glycogen in your muscles, by moving your muscles, they need to get refilled - well that's where the fat burning comes in. Your body is going to look for sources of energy and it's going to take both from the fat stores (back up fuel) and the stuff you're still digesting.\n\nProtein, in the form of your muscles, is never really burned unless your body literally has nothing left to consume for energy - for men this happens below 4% body fat, for woman around 12%. You might have some small muscle loss from muscle decay, if your muscles are bigger than your body needs them to be it will break them down - muscles take a lot of fuel to support.\n\nAnd this is when you realize it's not a linear process (food goes in energy comes out), but a cyclical (energy is stored, energy is released).\n\nso that covers the burning portion. Now for the exercise and timing.\n\nGenerally you want to avoid eating high amounts of carbs, especially simple ones. Because as we saw, it turns off the fat burn and turns on the fat storage. But there is one exception - work out time. It is ok to eat carbs, especially simple ones, right before/during/after a work out. You're probably wondering why now.\n\nBecause, it generally takes about 30 mins for the insulin response to sugar to kick in. If you eat cabs before a work out, but before the insulin kicks in, you can rapidly deplete your glycogen stores (working out) and give that sugar a place to go, just to be used again during the work out. Similarly, after a work out your fuel tanks are empty, so those carbs go right to the glycogen stores. It doesn't matter that excess will go fat tissues, because there shouldn't be excess - your body has about 450g of glycogen stores between the muscles and liver. You would have to eat ALOT of sugar to over flow that.\n\nFor the rest of the day you want to eat complex carbs, healthy (**un**saturated) fats, and quality proteins to keep your body fueled with slow burn foods - which will keep your blood sugar consistent throughout the day. This avoids the spikes that cause fat storage.\n\nLastly - when insulin is done with it's job, it's usually so effective that your blood sugar is lower than before you ate. Making you hungry again. Every wonder why quick candy snacks leave you hungry an hour later, that's why.\n\nOnce you've gotten your head wrapped around the basics of how the body uses food, then you can get in to the details of what you should be eating for daily % of p/c/f. Personally I eat 25/20/55 following the Paleo guidelines, with 1hr of exercise 5 times a week, and I can eat all day and still lose weight because the carbs aren't being stored.\n\nHope that helps.\n\n**TL;DR Learn how insulin works, it's the key to understanding what you should eat and when**\n\n_URL_2_\n\n_URL_3_\n\n_URL_1_\n\n_URL_0_\n\nEdit: Feel free to ask follow ups and I'll do my best to clarify. Tried to keep it 'five year old' in detail, but unfortunately nutritional science is very complex\n\n\n\n"
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[
[],
[],
[],
[
"http://www.bodyrecomposition.com/muscle-gain/calorie-partitioning-part-1.html"
],
[
"http://www.eatnakednow.com/eatnaked/2013/05/08/the-fat-question-why-fat-doesnt-make-you-fat/",
"http://www.dummies.com/how-to/content/busting-the-great-myths-of-fat-burning.html",
"http://www.bodybuilding.com/fun/issa44.htm",
"http://www.bodybuilding.com/fun/matt55.htm"
]
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|
4swooy
|
Why would water push larger and heavier rocks/boulders farther up shore than smaller and lighter rocks?
|
I was just at a river/inlet from the ocean and it looked like very consistently, larger rocks were pushed father up the banks than smaller rocks. I would think it would be the other way around. The river was a large river in Rhode Island, not sure what type of rocks or whether there could have been a glacial aspect to the rock deposits, but the boulders were massive, but were sometimes pushed much further than smaller lighter rocks.
|
askscience
|
https://www.reddit.com/r/askscience/comments/4swooy/why_would_water_push_larger_and_heavier/
|
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"text": [
"If I'm reading the info you provided right, you might be looking at this backwards.\n\nYou say the mouth of this river is established in a layer of glacial sediments. Now, there are a lot of different kinds of glacial seds, but one of the most important ones is Till. \n\nTill is interesting in that one of its properties is the very wide variety of grain sizes represented in its constituent particles; [it contains pretty much a bit of everything from the finest mud to silt, sand, gravel and boulders](_URL_1_). When till is exposed to erosive forces such as periodic exposure to tides, there is a grain size threshold beyond which particles are too heavy to be moved. In other words, when the tide recedes, it will carry away some mud, silt and sand, as well as perhaps some gravel up to a certain size of boulder which exceeds its carrying force. After a while, you get a concentration of residual boulders along the upper reaches, with the sand and gravel circulating in the lower tide areas.\n\nI'm located about 600 km north of you, and here interaction of rivers and shorelines with poorly sorted glacial sediments is commonplace. It is very frequent for a river to be cluttered with boulder lag from winnowed glacial seds such as you've described ([Compare this scene with the previous picture of raw unworked till. Here, the river remobilised glacial sediments of sand size and less and flushed them down stream, leaving behind concentrations of large boulders on the shore and in its bed](_URL_0_)).\n\nTLDR: the boulders were brought in by the glacier with a load of finer stuff; the finer stuff was carried away by erosion but the boulders are more challenging to remove, so they stay behind."
]
}
|
[] |
[] |
[
[
"http://img.radio-canada.ca/2013/07/17/635x357/130717_xo7xl_riviere_chaudiere_sn635.jpg",
"https://manitobamuseum.ca/main/wp-content/uploads/geology_paleontology/till.jpg"
]
] |
|
d8kigz
|
Why Descendants of those who survived the plague in europe are immune to HIV?
|
I just read this somewere and i am a medical student so i just wanted to know the reason
|
askscience
|
https://www.reddit.com/r/askscience/comments/d8kigz/why_descendants_of_those_who_survived_the_plague/
|
{
"a_id": [
"f1b2g08",
"f1bj705"
],
"score": [
7,
34
],
"text": [
"Here's a nice little [article](_URL_0_) that summarizes it and also cites the two studies done on the subject. \n\nTL;DR: Protection from HIV is transfered through mutation in gene for CCR5 receptor which is necessary for HIV uptake into cells. Studies suggest epidemic in the past has selected for this mutation in European population. Main contenders are Black Death or smallpox.",
"Short answer: They aren’t. \n\nLonger answer: It was proposed that the relatively high frequency of the CCR5-Δ32 mutation in Europeans was selected by surviving bubonic plague, but that was just a hypothesis that wasn’t tested in the original paper, that hasn’t been supported by testing, and that doesn’t match what we know about plague in the first place. \n\nLonger answer still: There’s a mutation in the CCR5 protein called CCR5-Δ32 that was identified as giving carriers a lot of protection against HIV infection. That mutation is *relatively* (but only relatively) common in Europeans, with around 10% of Europeans carrying the mutation. When this was discovered, scientists wondered why it was so (again, relatively) common in Europe, and suggested that perhaps exposure to some other pathogen had selected for CCR5-Δ32. Since one pathogen that was once common in Europe was Yersinia pestis (the Black Plague agent), that seemed like a reasonable candidate. ([Dating the origin of the CCR5-Delta32 AIDS-resistance allele by the coalescence of haplotypes.](_URL_0_))\n\nNote that this was purely a guess, and was completely peripheral to the actual work of identifying the mutation in the context of HIV. The guess was, however, widely reported as fact, since nuances don’t carry over into reporting. However, there’s really no other evidence supporting this notion, and in fact there are at least three lines of evidence arguing against it:\n\n* People with CCR5-Δ32 were just about as likely to die of the plague as non-carriers. [Frequency analysis of the delta32ccr5 HIV resistance allele in a medieval plague mass grave.](_URL_3_)\n* Regions in Europe with a historically higher frequency of plague, today have a lower frequency of CCR5-Δ32. [The Black Death and AIDS: CCR5-Δ32 in genetics and history](_URL_4_)\n* The CCR5-Δ32 mutation seems to have been selected in Europeans before the plague arrived. [Evaluating plague and smallpox as historical selective pressures for the CCR5-Δ32 HIV-resistance allele](_URL_2_)\n\nA new guess is that CCR5-Δ32 may give some protection against smallpox, but again this seems to be a guess with no experimental or epidemiological support. \n\nFinally, even if CCR5-Δ32 did give protection against the plague (which it probably doesn’t), 90% of Europeans don’t have this mutation, so by no stretch of the imagination could you say that “Europeans are immune to the Black Plague”. \n\n[Other mutations](_URL_1_) have, similarly, been proposed to be associated with plague resistance, but are similarly untested and should be considered as less than a hypothesis until there’s some form of evidence.\n\nAlso, technically, these sort of resistance-associated variations aren't strictly \"immune\", since they don't necessarily impact the immune system, but in a non-technical way it's fine to call it \"immunity\"."
]
}
|
[] |
[] |
[
[
"https://www.nature.com/news/2005/050307/full/050307-15.html"
],
[
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1377146/",
"https://academic.oup.com/ecco-jcc/advance-article-abstract/doi/10.1093/ecco-jcc/jjz062/5409350?redirectedFrom=fulltext",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC299980/",
"https://www.ncbi.nlm.nih.gov/pubmed/15830584",
"https://academic.oup.com/qjmed/article/99/8/497/2258951"
]
] |
|
426386
|
Are there any recordings of Hitler where he's *not* screaming and yelling?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/426386/are_there_any_recordings_of_hitler_where_hes_not/
|
{
"a_id": [
"cz7zyaj"
],
"score": [
35
],
"text": [
"Hitler was amazingly guarded about his public image, and because of this, there is very little out there in terms of candid recordings. The one extant recording we have was made June 4, 1942, during a visit to Finland. Ostensibly, he was there to greet Mannerheim, the Finnish supreme commander, for the occasion of his 75th Birthday. In reality though, the purpose of the visit was to shore up Finnish support and assure them of continued Axis success against the Soviets. Barbarossa had been launched a year prior and of course had not delivered a knock-out blow as had been hoped for. The Finns were an important partner of Germany, putting pressure on the Northern front, especially near Leningrad, and there were fears (which of course would come true two years later), that flagging enthusiasm might result in Finland putting out signals for a separate peace.\n\nThe meeting was on Mannerheim's private train, with a presentation of the Great Golden Cross of the German Order of the Eagle and a private lunch. Following that, the two leaders - along with Field Marshal Keitel and Finnish State President Ryti - had a conference which lasted for an hour and a half, mostly taken up by Hitler's monologues. He impressed upon the Finns the danger of the Soviet Union and the necessity of the conflict, but gave them no real indication of upcoming military plans. While we don't have the entire meeting, a recording of the first segment survives. It made by the Finns without Hitler's knowledge, and as such lacks the same tone and style that he exhibited in his public statements. [Thanks to the wonders of modern technology, here it is on YouTube with subtitles.](_URL_0_)\n\nKershaw, \"Hitler 1936-1945\""
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=E8raDPASvq0"
]
] |
||
2hwkdf
|
If in-breeding produces weak/deficient/deformed offspring, why doesn't asexual reproduction do the same?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2hwkdf/if_inbreeding_produces_weakdeficientdeformed/
|
{
"a_id": [
"ckwq43e"
],
"score": [
3
],
"text": [
"In breeding results in homozygosity (the same allele in both positions). This means that conditions which are autosomal recessive are brought to the fore where before there was enough genetic diversity for this not to happen. \n\nAsexual reproduction is just cloning - there's no genetic crossover - so the offspring are identical to the parent."
]
}
|
[] |
[] |
[
[]
] |
||
2vhig6
|
what is a computer script?
|
Are there different types of scripts, and if so what are the best uses for each type?
How does one go about learning to write scripts?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2vhig6/eli5_what_is_a_computer_script/
|
{
"a_id": [
"cohr3gs",
"cohtgds"
],
"score": [
2,
2
],
"text": [
"One way of categorizing programming languages is according to whether they are interpreted or compiled. In an interpreted language, a program is simply a plain-text file containing the commands that you want to run. This file is called a *script*. You feed this file to a program called an *interpreter* which then executes each command in the order they're written (like an actor reading a script).\n\nIn compiled languages, the plain-text file that contains the commands for the program is called a *source file*. This source is fed to a *compiler*. Instead of executing the commands in the source immediately (as the interpreter does), the compiler translates the program into a binary file called the *executable* (actually, it's a bit more complicated than this, but we're going for simplicity here). The executable is the actual program that you run on your computer.\n\nEach method has its pros and cons, and choosing between them depends on the program being made. Some compiled programs will even incorporate an interpreter to handle aspects that are better accomplished by scripting.",
"Scripts are small programs generally written in a \"high level\" languages (languages where much of the computer's underlying workings are abstracted from the user). Scripts are also often associated with the automation of small repetitive tasks and interpretive run-time environments (special computer code that interpolates the script as it executes). \n\n The delineation between calling something a program vs script is very unclear, but usually a script would be denoted by brevity and lack of complexity. That said, there isn't a hard and fast rule, as evidenced by the lengthy write up on wikipedia: _URL_0_\n"
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Scripting_language"
]
] |
|
flhogm
|
how do 'dry' wines taste dry when they're a liquid?
|
I never knew what people meant when they said dry wines until I drank one recently and it definitely tastes dry. It's a liquid though and I'm curious how this works.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/flhogm/eli5_how_do_dry_wines_taste_dry_when_theyre_a/
|
{
"a_id": [
"fkymmvk",
"fkyng6u"
],
"score": [
2,
17
],
"text": [
"Dry is simply the opposite of sweet. Dry wine means it has a low sugar content. They tend to be quite sharp, the same way lemon juice is, and I suppose that could taste \"dry\".",
"\"Dry\" is just the wine lingo word for \"not sweet.\" Sugar tends to make us salivate a little bit, which might explain why \"dry\" is used to mean a wine with little sugar - because the sour, bitter, and tannic flavors in wine can make the mouth feel drier without much sugar to compensate.\n\nHowever, it is mainly the tannins in wine that cause that puckery, drying out feeling on the tongue. The same compounds in a strong cup of tea. But we describe wines with a high amount of those tannins as \"tannic,\" rather than dry. Confusingly, a wine can have plenty of sweetness and high tannins, meaning that your mouth might have that dry feeling, but the wine shouldn't be considered \"dry.\" It's just a term that's been used historically for drinks without much sugar content."
]
}
|
[] |
[] |
[
[],
[]
] |
|
1huxi9
|
why singapore is doing better (economically) than its neighboring countries
|
Singapore's at the top: _URL_0_
I get that Singapore's smaller, but what else?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1huxi9/eli5_why_singapore_is_doing_better_economically/
|
{
"a_id": [
"cay5zsh",
"cay8ier",
"cayb3ut",
"caybfgh"
],
"score": [
16,
8,
7,
7
],
"text": [
"It is a former British trading port which achieved independence but retained its importance as a trading hub.",
"Initially, right after independence, the geographical location of Singapore as a free port was the main thing that boosted its economy. As the country got richer, more investments could be made in R & D, resulting in technological advancements which would further boost economic growth. It's a cycle, and since then the country has thrived on international trade, quality of human capital (which is also ranked one of the top few in the world, if I'm not wrong), and technology. Hope this has helped!",
"The link you give is \"urbanization.\" That's how much of the country is city. In the case of Singapore, 100% of the country is a city. That's because the country is the *size* of a city.",
"Not sure why this hasn't been brought up yet... plain and simple, Singapore has one the freest economies in the world.\n\n_URL_0_\n\nThere are lots of former British colonial ports and lots of small trade dependent nations in the world, but Singapore's economy excels for the same reason Hong Kong's does; a very deregulated market-based economy that attracts investment and business ventures. \n\nThe country has problems (low birthrate, some draconian laws imposed on its citizens) but it's economy is not one of them. "
]
}
|
[] |
[
"http://en.wikipedia.org/wiki/Urbanization_by_country"
] |
[
[],
[],
[],
[
"http://en.wikipedia.org/wiki/Singapore#Economy"
]
] |
|
1pt6qp
|
how are weather percentages determined?
|
Yesterday had been marked as 100% chance of precipitation all day for the last week, and then we received a little rain at night, otherwise a pretty dry day. How are these percentages determined? They are something that has always confused me.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1pt6qp/eli5_how_are_weather_percentages_determined/
|
{
"a_id": [
"cd5rpcd",
"cd5rxeq"
],
"score": [
2,
3
],
"text": [
"Its a combination of likelihood and area of prediction (and they use things like Hygrometers to measure Humidity).\n\nIf they predict 60% chance of rain, but over 100% of the area they show, then it is a 60% chance. Conversely, if they predict 100% chance of rain, but in scattered showers over only 60% of the same area, then it is still 60% chance of rain (since 40% of the area wont receive rain). ",
"In order to forecast the weather, a lot of model simulations are run. This is called an ensemble, and each ensemble member has a slightly different set of initial conditions (to account for uncertainty in measurements). \n\nPercentages are calculated based on the results of the ensemble. For example, if it rained in a particular area in 20% of their simulations, they would say there is a 20% chance of precipitation."
]
}
|
[] |
[] |
[
[],
[]
] |
|
bx1c7g
|
Is it accurate to say that in wwII Mexico was approached by the nazis to attack the US but instead joined the fight in opposition.
|
[deleted]
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/bx1c7g/is_it_accurate_to_say_that_in_wwii_mexico_was/
|
{
"a_id": [
"eq2fj93"
],
"score": [
7
],
"text": [
"Are you sure you are thinking about World War II? Most of this sounds like it is a description of World War I and the Zimmerman Telegram. Give a look at [this older thread](_URL_1_) or [this one](_URL_0_), or [this one](_URL_2_). (Although to be sure, Mexico never joined in for either side there)"
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/8eyn2m/was_the_zimmerman_telegram_really_a_scam_plotted/dxzuxq2/",
"https://www.reddit.com/r/AskHistorians/comments/480jmy/what_made_germany_think_mexico_would_go_along/",
"https://www.reddit.com/r/AskHistorians/comments/8eyn2m/was_the_zimmerman_telegram_really_a_scam_plotted/dy004pn/"
]
] |
|
24glzo
|
what are "zoning laws" and "neighbourhood commities". they're either a tiny thing or not a thing at all in the uk
|
It seems crazy? That some people can come a long and just say what you can and can't do. Is there a way out of it or do you somewhat agree to follow the rules when you move there or something?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/24glzo/eli5_what_are_zoning_laws_and_neighbourhood/
|
{
"a_id": [
"ch6wwk3",
"ch6x0zk",
"ch6x23f",
"ch6x54d",
"ch72esq"
],
"score": [
3,
2,
2,
2,
2
],
"text": [
"Zoning laws designate what type of structure and/or business can be located in a certain area. For instance, a city may not want a car repair shop plopped right down in the middle of a neighborhood.\n\nIf by *neighborhood communities* you mean Home Owner Associations, these are collective organizations in which homeowners pay into the association and, in return, the association pays for common area maintenance and improvements, such as a pool and recreation area and common area landscaping and lighting. \n\nAssociations are becoming prevalent in certain areas in the US because cities tend to be lax about making repairs or keeping up city-owned land, and homeowners like to feel they have some control over the area in which they live.\n\nCities love homeowner association because they can completely wash their hands of any maintenance to the areas, even including the streets.\n\nThe downside, as you may have guessed, it that these associations are made up of people who often have a strict agenda of controlling everybody else in the association, and the contracts that homeowners have to sign when entering these communities tend to be strict and unforgiving.",
"A Neighbourhood committee, or Home Owner's Association is essentially a group of people that run the neighbourhood's appearance. They schedule any block parties, stuff like that. But they also dictate certain things about the outward appearance of the house, they have a list of approved colours, you can't have a window AC unit in the front of the house, all the mailboxes have to look like this. And yes they do have some authority, but they do have a purpose, neighbourhoods do look nice when all the houses have a bit of uniformity and such.\n\nAs for zoning laws, I'm sure they are there in the UK, you just don't hear about them. Essentially, when land gets divided up and the city is given authority over it, they have to classify what it is. Whether it be residential (people live there) or commercial (people work there) or industrial (factories, shipping yards, warehouses, etc) obviously there are people who work from home, and people who live in hotels, but you get the idea. You can't buy a store in a city and then try and make it into a house, just like you can't buy a warehouse and make it into a house. There are certain restrictions, and if you want to do so, you have to go to the city and get it changed.",
"Zoning laws are laws that determine what a particular area of land could be used for. For example, a particular lot may be designated as residential and you'd be able to build a house there but not a convenience store (unless you get the city to rezone it.) \n\nBy \"neighborhood committees\" I'm guessing you mean something like homeowner's associations. Those are voluntary groups formed to ensure that the appearance and activities don't negatively affect the value of neighboring homes. If you never agree to join they don't affect you (although some owners and brokers won't sell to you unless you agree to join). There have been some small communities that have been able to incorporate as a legal neighborhood and try and pass ordinances to force people to join but they haven't really stood up well in court.",
"Zoning laws are the cities way of controlling development in the city. Ensuring that you have enough space for housing (both high and low density), Commercial, Light and heavy industrial. In some cities by zoning for low density residential you ensure that only larger upscale houses can be built and therefore prevent low income apartment building from going up.\n\nNeighborhood Communities or HOA's are a list of rules that you must abide by in order to live in the community. It is there to protect property values and to keep the area looking nice. They are put in place by the developer and usually ran by a private management company. While it may be a bit of a pain getting a warning for leaving your trash can out for two days...it does prevent my neighbor from allowing all his plants to die in his front yard, park his car on his lawn and paint his house purple.\n\nIf you have a problem with zoning then you talk to the town council. If you have a problem with the HOA then join the board and help take control.",
"You can't just build where you want in the UK either. You have to apply to the council for planning permission."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
3p0fzp
|
What causes the aftertaste one gets when administered certain anesthetics and illicit IV drugs?
|
I had an EGD last week and remembered a medical taste come into my mouth.
Some IV users have reported experienced this "taste". What causes it, and why does it have the flavor it does?
|
askscience
|
https://www.reddit.com/r/askscience/comments/3p0fzp/what_causes_the_aftertaste_one_gets_when/
|
{
"a_id": [
"cw2hj2e"
],
"score": [
5
],
"text": [
"This happens frequently with IV medications. It seems to be especially common with prefilled saline syringes. \n\nThe mechanism is that when certain volatile compounds enter a vein and get circulated, within a few seconds they pass through the lungs. The compounds evaporate into the lung airspace and are exhaled. The smell or aftertaste occurs as they pass through the nose and mouth on the way out. "
]
}
|
[] |
[] |
[
[]
] |
|
1jorh5
|
lbw in cricket
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1jorh5/eli5_lbw_in_cricket/
|
{
"a_id": [
"cbgsc4n"
],
"score": [
2
],
"text": [
"Leg Before Wicket: it's the simplest way for a batter to get put out in cricket. If he stands in front of the wicket and gets hit by a pitched ball that would have hit the wicket but for his body block, he's out. If you know baseball, it's like leaning into the strike zone. In baseball, such a pitch would just be ruled a strike, but in cricket it's an out -- because if the wicket does get hit, it's one strike and you're out."
]
}
|
[] |
[] |
[
[]
] |
||
5352eo
|
how can idle clicker games that offer little to no gameplay become popular?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5352eo/eli5_how_can_idle_clicker_games_that_offer_little/
|
{
"a_id": [
"d7q10ae"
],
"score": [
4
],
"text": [
"People like to micromanage and people like easy on-the-go games to play while they're taking breaks at work or are on the shitter."
]
}
|
[] |
[] |
[
[]
] |
||
68077h
|
Why did the Harlem Globetrotters never join the NBA?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/68077h/why_did_the_harlem_globetrotters_never_join_the/
|
{
"a_id": [
"dgv4sw4",
"dgvgl8b"
],
"score": [
5,
22
],
"text": [
"You honestly might have better luck asking in /r/NBA",
"1927-1950 the globetrotters did play real competitive basketball and were one of the best teams in the world. However, they were based out of Chicago and only used the Harlem moniker to reference their connection to black culture. At first, they would play regional as well as one national tournament called the world professional basketball tournament. Which they won in 1940 and several future NBA teams would go on to win in later years such as the Lakers. Then the NBA became dominate in competitive basketball through the mid 40’s and beyond but did not largely integrate until the late 50’s leaving talented players like Goose Tatum (arguably the best player in the world during his period with the globetrotters) out of the league and barnstorming with the Globetrotters.\nAs the globetrotters lost their true stars to the NBA they shifted to less competitive basketball and more of a show as the WWE would be to Olympic wrestling. They formed the Washington Generals in 1952 to play their opponents on tour and have largely stayed out of real basketball since, outside of a few exhibition games. \n\nIn summary, the globetrotters originally were a basketball club on par with the New York Knicks or Minnesota Lakers, however because of their predominance of black players they were not asked to join the NBA or the early leagues that would go on to form it. They created a separate concept from the NBA originally as a showcase of African American Basketball talent through the mid 40’s-50’s, and then as the NBA began integration African American players they transitioned to the fun basketball themed showcase we have today. \n\nSources \nUnfortunately, I could not find a serious academic source for the globetrotters and hope a popular history book and website will suffice. \n\nSpinning the globe the rise fall and return to greatness of the Harlem Globetrotters, Ben Green *Amistad* Jan 3, 2006, reprint\n\nHere’s a nice PBS article, \n_URL_0_\n\nWould like to see a social historian follow up with more about the slow integration of the NBA as compared to baseball.\n"
]
}
|
[] |
[] |
[
[],
[
"http://www.pbs.org/pov/hardwood/background/"
]
] |
||
2k32an
|
Why were women considered bad luck to be on a ship? When and how did the superstition start?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2k32an/why_were_women_considered_bad_luck_to_be_on_a/
|
{
"a_id": [
"clhoe3c"
],
"score": [
131
],
"text": [
"It's been years since I've actively studied anything related to the Age of Sail but once a fangirl, always a fangirl, I suppose. So, to answer your question, women were considered bad luck on ships because they were believed to be too physically inferior to be of any use in actually sailing the vessel while also distracting the men on board and leading them into acts of vice. If the men were distracted from their duty to the ship in this way and therefore failed to sail the vessel properly, it would anger the stormy sea gods who would then punish the entire ship with rough seas and bad weather, possibly even causing the ship to sink with all hands on board.\n\nSuch beliefs often had dire consequences for women aboard ships at sea. In 1379, Sir John Arundel set out for sea in support of the duke of Brittany but stopped on the way to violate a convent of nuns, even allowing some of his men to take some of these women with them out to sea. The fleet ran into heavy storms off the coast of Cornwall, though, and thinking that it was the fault of the women on board, the crew threw them overboard. (See, *The Chronica Maiora of Thomas Walsingham (1376-1422)*, ed. and trans. by James G. Clark and David Preest (Woodbridge, 2009), pp. 96-99)\n\nYet, paradoxically, women were believed to be the best navigators and the presence of a naked woman was thought to be good luck at sea, hence why a number of ships' figureheads were bare-breasted female figures. It was thought that her open eyes would lead the ship to her destination while her bare breasts would shame the sea gods into calm. This effect of female nudity over nature was recorded by Pliny in his encyclopedic *Natural History* (Book 28, Ch 2) where he wrote that a menstruating woman who uncovers her body has the ability to scare away hailstorms, whirlwinds and lightning. If she walks naked around the field, caterpillars, worms, and beetles will fall off the ears of corn. And, even when not menstruating, a woman can still lull a storm out at sea by stripping down to nothing."
]
}
|
[] |
[] |
[
[]
] |
||
wgith
|
Why are some people able to bend their pinky finger without moving the rest of their fingers, while other people cannot?
|
If I open my hand as if to wave to someone, I'm able to bend most of my digits down toward my palm without moving the other fingers. The one exception is my pinky finger. As soon as I start to bend it, my ring finger bends as well. I am completely unable to bend my pinky finger without my ring finger bending as well.
Some people experience this, and others don't. What is going on in my hand that is not allowing this?
|
askscience
|
http://www.reddit.com/r/askscience/comments/wgith/why_are_some_people_able_to_bend_their_pinky/
|
{
"a_id": [
"c5d4bjs",
"c5dtlxr"
],
"score": [
2,
2
],
"text": [
"I'm not sure but sitting here bending my pinkie reminded me of the time some redditor had me trying to taste the salt at work",
"It has to do with the innervation and muscles that extend and flex your fingers. Your pinky and ring finger share common tendons. \n\nA simple way to illustrate this. Open your hand and try to flex each finger at the first finger joint (not the knuckle). These are your proximal interphalangeal joints. You will notice that you can flex each finger individually but when you get to your pinky YOU CANNOT flex your pinky individually. This is because normally you do not have an individual ring finger extensor muscle, and when your pinky flexes it overpowers the rink finger. \n\n\nIn a nutshell\n\n1) A few lucky people are born with independent ring and pinky finger extensor muscles\n\n2) Most however do not, but you can train your fingers (think guitarists) to overcome this somewhat\n\nIf you are really interested I found this **amazing** post online that explains everything in detail \n\n_URL_0_"
]
}
|
[] |
[] |
[
[],
[
"http://www.madsci.org/posts/archives/2005-05/1117326759.An.r.html"
]
] |
|
1pjp8z
|
In the Middle Ages, how common was literacy in one's own language as opposed to literacy in Latin or Greek?
|
This got me thinking after I read about the high Russian-only literacy rate of the city of Novgorod during the time of the republic.
During a time when literacy in Latin usually meant someone in the church, how common was it to be literate in your own language (English, German, etc.)?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1pjp8z/in_the_middle_ages_how_common_was_literacy_in/
|
{
"a_id": [
"cd3ezah"
],
"score": [
4
],
"text": [
"Vernacular literacy in 13th to 14th century England was on the way up, so that some estimates say that as many as half of the adult male population was literate enough to transact business in writing. This link has [more information,](_URL_0_) with interesting insights into just what we mean by \"literate\"."
]
}
|
[] |
[] |
[
[
"http://books.google.com/books?id=Rv_QzOML3U0C&pg=PA47&lpg=PA47&dq=literacy+in+england+1300&source=bl&ots=ftu_pOzSs5&sig=C6w76tyGkbDQzE_q1rtqK0TeDaM&hl=en&sa=X&ei=Hb1xUpXxGvDyyAGFuYD4Bg&ved=0CEwQ6AEwBA#v=snippet&q=%22the%20question%20of%20the%20literacy%20of%20the%20laity%22&f=false"
]
] |
|
20hr0n
|
Peerage Titles and Military Ranks
|
Perhaps not the best place to ask this question, but I couldn't think of any other place to ask and my normal resources on peerage address have failed me.
How did ranks/titles given by military service interact with peerage titles, specifically in Great Britain? The person I have primarily used to try and help myself figure this out is Horatio Nelson, but I cannot determine whether addressing him as "Admiral Lord Nelson" is a standard form of address or simply a loose, common way of referring to him and his accomplishments and something that would make the peers cringe. I also am aware that Nelson was given his peerage because of his Naval successes - would there be a difference for someone who had titles not through military accomplishments? Or would there be a difference dependent on branch of service- Navy versus Army? Or did it all come down to what their peer title was - a baron versus a viscount, for example?
Also, looking beyond just Great Britain, did it vary in different countries. or over time, for example during wartime or not? That might be making it too broad, but I've been struggling with this question for a while. Thank you in advance.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/20hr0n/peerage_titles_and_military_ranks/
|
{
"a_id": [
"cg3dbpi"
],
"score": [
9
],
"text": [
"Formally it's military rank followed by the honorific or title, for example Admiral the Viscount Nelson, Field Marshal the Duke of Wellington or Marshal of the Royal Air Force the Viscount Trenchard. Informally these may be shortened to Lord Nelson, The Duke of Wellington or Lord Trenchard respectively. Indeed any ennobled person below the rank of Duke is known informally as Lord.\n\nThe three former Chiefs of the Defence Staff are life peers and so formally are known by the honorific \"sir\" which comes with each of them being a baronet, viz: Admiral Sir Michael Boyce, Air Chief Marshal Sir Jock Stirrup and General Sir David Richards. As members of the House of Lords, however, they may be known informally as Lord Boyce, Lord Stirrup and Lord Richards.\n\nThe final title of note is \"the Honourable\" which is used by the younger sons of a viscount and all sons of an earl or baron. Although rarely used outside of the most formal circumstances one might find something in the style of Captain the Honourable Rupert Badminton-Racket serving in the Household Cavalry.\n\nEdit: source is Debrett's Correct Form."
]
}
|
[] |
[] |
[
[]
] |
|
142kef
|
Would a thimbleful of a neutron star which weighs approximately 100 million tons on earth, remain the size of a thimble if it were removed from its neutron star?
|
It is said a thimbleful of a neutron star would weigh 100 million tons on earth because of the matter density within a neutron star. Is it the entire mass of the star which keeps the matter so compressed or once the matter is so compressed does it remain stable at its density?
|
askscience
|
http://www.reddit.com/r/askscience/comments/142kef/would_a_thimbleful_of_a_neutron_star_which_weighs/
|
{
"a_id": [
"c79e5jf"
],
"score": [
4
],
"text": [
"The star's gravity is the reason that we conclude it has such high density. It is unknown if a smaller amount of this dense neutron material would be stable in that form, as a neutron star is only about 10 km in diameter, and it's obviously stable.\n\nSome theories hold that this amount of neutron star on Earth would explode violently, and if you analyze the stored energy from it's extreme temperature, you can see that amount is sufficient to destroy the Earth.\n\nAlso, see this: _URL_0_\n\nEdit: grammar."
]
}
|
[] |
[] |
[
[
"http://www.reddit.com/r/askscience/comments/gq1fu/the_explosive_yield_of_neutron_star_matter/"
]
] |
|
1pnc0d
|
the reddit policy against self promotion
|
So I run a YouTube channel. Recently I created a video that received a very positive response. Realizing that I had found a new market for my videos I began working on new content. Not spamming mind you, I made sure to allow a gap of at least 3-4 days between videos or posts.
However, I am now running up against the "self promotion" clause. I read the information I could find but don't feel like I have a good understanding of what I did wrong. I'm frustrated because I'm getting great responses from my content but I can't share it.
Thank you for your help!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1pnc0d/eli5_the_reddit_policy_against_self_promotion/
|
{
"a_id": [
"cd41j6r"
],
"score": [
3
],
"text": [
"Reddit has very few hard rules (i.e. rules which may cause your account to be shadow-banned if broken), however there are a number of soft rules (primarily outlined on the [reddiquette](_URL_0_) page) that guide 'proper' behavior on the site.\n\nIn terms of hard rules, the only one which is relevant to your situation is the \"Don't Spam\" rule which basically only applies if the only content you post on reddit is from your own website/blog. In other words, this rule generally does not apply to people who actively engage in the reddit community and participate in discussions (e.g. by making relevant and thoughtful comments in other user's threads and by posting a variety of content/links from various different sources, not just your own websites).\n\nIn terms of proper etiquette... if you do plug your own site, you should generally disclose this information up front (such as by posting a comment in the thread that makes it clear that you are the creator of the video/content and perhaps explains why the content is relevant or why you thought the reddit community would enjoy it).\n\nPlease note that reddit is comprised of many (almost endless) different subreddits. Each subreddit has its own moderators which enforce their own rules. So just because you may have received warning from one particular moderator of one subreddit about self-promotion, does not necessarily mean what you did was against reddit's site-wide rules or that it was against the rules of other subreddits.\n\n"
]
}
|
[] |
[] |
[
[
"http://www.reddit.com/wiki/reddiquette"
]
] |
|
6pnjxi
|
Looking for resources on Mesopotamia during the Early Dynastic period
|
Books or reliable online resources are both good. Particularly interested in trade, taxation, economics, internal politics and social structure. I know definite information on this period is scarce -- informed speculation is perfectly acceptable. Thanks!
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/6pnjxi/looking_for_resources_on_mesopotamia_during_the/
|
{
"a_id": [
"dks03hr"
],
"score": [
2
],
"text": [
"I recommend beginning with Harriet Crawford's *Sumer and the Sumerians* and Postgate's *Early Mesopotamia: Society and Economy at the Dawn of History*. Susan Pollock's *Ancient Mesopotamia* is excellent but very dry, as is Crawford's edited volume *The Sumerian World*.\n\nI also highly recommend *Archaic Bookkeeping: Early Writing and Techniques of Economic Administration in the Ancient Near East*, *Treasures from the Royal Tombs of Ur*, and the Early Dynastic sections of *[Art of the First Cities](_URL_0_)*. Finally, the recent publication of Zainab Bahrani's *Art of Mesopotamia* has provided a very nice overview of the art of the Uruk period and Early Dynastic Mesopotamia (pp. 41-109). "
]
}
|
[] |
[] |
[
[
"http://www.metmuseum.org/art/metpublications/art_of_the_first_cities_the_third_millennium_bc_from_the_mediterranean_to_the_indus"
]
] |
|
34kske
|
I'm an able bodied man from East Germany during the cold war, if I really wanted to, how hard would it be for me to get to west Germany and how likely would I be to succeed?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/34kske/im_an_able_bodied_man_from_east_germany_during/
|
{
"a_id": [
"cqvunxd",
"cqwipgk"
],
"score": [
222,
6
],
"text": [
"Acording to [this table](_URL_0_) your chances of succes would have been like 20-25%. The 2nd collumn is all succesful attempts of that year and the 5th collum are all unsuccesful attempts. How hard it would have been is dependent on a lot of factors, it could be easy for instance: you are allowed to travel to the west and you just don't come back. Or if you are really determined you build yourself a hot air baloon.",
"There's one thing I don't quite understand. Yugoslavia had practically open borders and both East and West tourists were coming there for vacation. What stopped a family that had a car to simply go to a third country (for vacation) and from there go to the west?"
]
}
|
[] |
[] |
[
[
"http://de.wikipedia.org/wiki/Flucht_aus_der_Sowjetischen_Besatzungszone_und_der_DDR#Umfang"
],
[]
] |
||
3vq5dl
|
Why did Ashkenazi Jews who lived outside of German-speaking areas speak Yiddish?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3vq5dl/why_did_ashkenazi_jews_who_lived_outside_of/
|
{
"a_id": [
"cxpuk6h"
],
"score": [
4
],
"text": [
"Short answer:\n\nBecause they lived in Yiddish-speaking areas, doh. \n\n\nLong answer: \n\nThe Yiddish language is indeed related to some German dialects currently spoken in what used to be Roman Germany but doesn't share the innovations that appeared in German after the 15th century. What might be the reason?\n\n[The Jews arrived in Germany together with the Romans](_URL_1_) but with the sudden appearance of Christians they started getting problems with antisemitism.\n\n- in 1096 the First Crusade starts with a genocide on the Jews in Speyer, Worms and Mainz.\n\n- in 1298 Rintfleisch burger movement is killing Jews and taking their property during a short war between the house of Naussau and the house of Habsburg for the German crown. \n\n- in 1336-38 the Armleder movement is murdering Jews to take hold of their property again in Franconia, in Hessen and in Alsace; it's triggered by a noble who has seen an angel in his dreams. \n\n- in 1349-51 the Jews are massacred in Speyer, Worms, Mainz, Koblenz, Köln and Trier in a Christian attempt to atone for the sins that have brought them the plague.\n\nInbetween you had smaller killing sessions, too. The Jews of Bacherach, for instance, have been murdered over the libel of having ritually cannibalized a Christian child for Passover. The child in question was made into a \"Saint Werner\". Until 1962 he was a patron saint of wine.\n\nHowever: In Eastern Europe they were more than welcome for their urbanite know-how. The very first Polish coins have, for instance, been [minted with Hebrew inscriptions](_URL_0_)."
]
}
|
[] |
[] |
[
[
"https://upload.wikimedia.org/wikipedia/commons/e/e9/PolishHebrewCoins1.jpg",
"http://www.antikmakler.de/catalog/images/thumbnail/produkte/xlarge/bilder/bucher/06/v6789.jpg"
]
] |
||
28yjek
|
can blind people even understand the concept of color?
|
I've always been curious (in the case of people who have been blind their whole lives and never enjoyed a single second of sight) as to whether or not they can grasp or understand explanations about visually derived phenomena like color, visually descriptive terms like gloomy, brilliant, etc?
There are so many things I wonder about their ability to comprehend (given their handicap), as well as what they undoubtedly understand in greater detail or in ways that I could never understand (by having other heightened senses).
I wish I could speak to a blind person about this but would love to learn from others who might know the answer to this free-flowing, endless sorry excuse of a question :)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/28yjek/eli5can_blind_people_even_understand_the_concept/
|
{
"a_id": [
"cifp9uk"
],
"score": [
2
],
"text": [
"Check out Tommy Edison on youtube. He's a blind comedian, and he's got a whole series of videos on being blind...and he's hilarious. One specifically where he's trying to guess the color of a Magic Marker by smelling them..."
]
}
|
[] |
[] |
[
[]
] |
|
33cyz0
|
Why are male ligers "sterile", but not the females?
|
askscience
|
http://www.reddit.com/r/askscience/comments/33cyz0/why_are_male_ligers_sterile_but_not_the_females/
|
{
"a_id": [
"cqkutv1"
],
"score": [
2
],
"text": [
"This is called \"Haldane's rule\": if there is sterility in a hybrid population, it is more likely that the heterogametic sex (that is, the one carrying XY) will be the sterile one. In mammals, the male is XY, while in birds, it's the female that's XY (called ZW, but that's just terminology), and so hybrid male mammals are more likely to be sterile, while hybrid bird females are more likely to be.\n\nThe reason for this isn't well understood, but there are some hypotheses listed in the Wikipedia article: _URL_0_"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Haldane%27s_rule"
]
] |
||
5nbd6g
|
why is taking an aspirin before the surgery harmful?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5nbd6g/eli5why_is_taking_an_aspirin_before_the_surgery/
|
{
"a_id": [
"dca4ol0",
"dca4pqk",
"dca4tr9"
],
"score": [
8,
5,
3
],
"text": [
"It prevents your blood from clotting properly! Hence, if you want to walk out of the surgery without blood gushing from your wounds you shouldn't take an aspirin right before it :)\n\nEDIT: words",
"Because aspirin is the only NSAID with blood thinning properties: that's why it's used in prevention of CV events at low dosage ( < 100mg). ",
"They also usually don't want you to take ibuprofen (Motrin/Advil) before surgery, either. And make sure of the number of days before surgery that you can't take them."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
1fue3b
|
Does exercise burn more calories at different parts of the day? What time of day is the body most efficient at fat burning?
|
To specify cardio would be jogging/running for about 30 mins
_URL_1_
_URL_0_
These articles are contradicting each other and both source valid papers. One says that the morning is best, the other says that the late afternoon is best. Please help me my poor brain is quite confused.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1fue3b/does_exercise_burn_more_calories_at_different/
|
{
"a_id": [
"cae0o71"
],
"score": [
3
],
"text": [
"You'll burn more fat at times when less carbohydrates are available for energy, it's that simple, and the first article says exactly that. Second article is not about cardio, it's about resistance training, so I don't know why you are trying to apply its facts to cardio."
]
}
|
[] |
[
"http://www.livestrong.com/article/118349-benefits-lifting-weights-night/",
"http://www.virtualmedstudent.com/links/healthy_living/understanding_how_the_body_burns_carbs_proteins_fats_simple.html"
] |
[
[]
] |
|
6j1smj
|
How was the Electoral College in the US related to slavery?
|
I've heard here and there that the Electoral College should be scrapped because it's purpose was to favor the slave states somehow. How was this so? What advantage/disadvantage did the slave states have in the Electoral College system?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/6j1smj/how_was_the_electoral_college_in_the_us_related/
|
{
"a_id": [
"djb1w8w"
],
"score": [
3
],
"text": [
"- The voting population of slave states was small compared to it's total population, free and slave.\n- Due to the 3/5 compromise slaves counted for the purposes of apportionment.\n- Congressional representation determines the number of electoral votes a state has.\n- The North had a larger population and was growing. [By the Civil War](_URL_0_) the North had a population of 18.5 million plus the border states. The South had a population of 5.5 million free and 3.5 million slaves.\n\nBecause of these factors slave states had more relative voting power in the EC than they would if a national popular vote was used.\n\n[President Lincoln won](_URL_1_) only 40% of the popular vote. He recieved 180 electoral votes, 69 more than the combined total of the two southern candidates who received a total of 111.\n\n69 EV is about 40% of the total EV in 1860. By comparison in 2016 President Trump won by 77 EV or about 14% of the total EV in 2016. "
]
}
|
[] |
[] |
[
[
"https://nps.gov/civilwar/facts.htm",
"http://www.270towin.com/1860_Election/"
]
] |
|
58j9ts
|
what exactly makes ramen noodles so unhealthy, and if you eat ramen often, will you have a shorter life expectancy?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/58j9ts/eli5_what_exactly_makes_ramen_noodles_so/
|
{
"a_id": [
"d90uwso",
"d90vhzt",
"d90wghz",
"d913yhs"
],
"score": [
13,
10,
6,
2
],
"text": [
"Ramen in and of itself is just noodles in soup. But instant Ramen, the kind you buy in a store, has a lot of salt. Too much salt is bad for you.",
"It's not that it's bad for you, it's that it's not \"good enough for you to live on\". Noodles are to starch what soda-pop is to sugar. A sneaky and tasty way to overindulge in an empty indulgence.\n\nSo ramen makes you \"feel like you ate\" (slaking your hunger) but it didn't give you any really essential nutrients. It doesn't even have enough _fat_ to keep you healthy, let alone the vitamins and minerals you need to keep all your systems functioning.\n\nThe problem isn't that eating ramen is poisoning you, it's that it's being treated like a staple.\n\nNow go look at that packaging on your instant ramen. Notice how they have a picture of the noodles with like vegetables and meat or eggs floating in the broth. ... If you do that. If you make it part of a balanced meal then it's fine.\n\nBut just like Captain Crunch is never encountered in the wild as \"part of this balanced breakfast\" the average people in the world you know eat the noodles in the salty broth and are secretly starving to death even as they get fat.",
"I am going to ASSUME you are talking about instant Ramen noodles. The typical quick cooking noodles in a cup or in a block.\n\nYou might ask consider how do they pre-cook the noodle, yet still put it dry into a package? The noodles are first deep fried in oil, then dried.\n\nSo first they are deep fried in oil, then you put them in a high sodium broth. Citation: _URL_0_\n\nReal, fresh Ramen is another thing.",
"One serving of instant ramen noodles will typically have close to 100% DV worth of sodium and I dunno bout you but I'd regularly have 2 packs at once when I was broke, so that's more sodium than you should have ALL DAY in one meal.\nThey also contain very little vitamins/minerals that a balanced diet needs, I find that all instant meals share this in some way, and in this case you're basically just getting salty carbs. \nSome would argue that if you eat any one particular dish that you'd become unhealthy, so don't think this is just the instant noodles we're warning you off of but actually lack of a proper diet in general."
]
}
|
[] |
[] |
[
[],
[],
[
"https://en.wikipedia.org/wiki/Instant_noodle#Production"
],
[]
] |
||
2a1c1w
|
Are the planets really in a ring around the sun?
|
If so, why a ring and not a more spherical shape?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2a1c1w/are_the_planets_really_in_a_ring_around_the_sun/
|
{
"a_id": [
"ciqmnua"
],
"score": [
4
],
"text": [
"Yes, the planets orbit the Sun on the same plane, more or less. \n\nThis question has been answered before. Be sure to check out the [FAQ's](_URL_0_) next time. Quoting my answer from the FAQ's on this subject:\n\n > The reason is the physical principle known as conservation of angular momentum.\n > \n > Before the planets formed, the solar system was just a giant cloud of dust and gas. Initially, the cloud had some net spin. As it collapsed, it began spinning faster and faster (just like an ice skater who brings in his/her arms). Also, the cloud began to flatten, due to gravity and some centrifugal forces.\n > \n > That is why everything orbits in the same plane, and it is also why most planets and moons spin in the same direction!"
]
}
|
[] |
[] |
[
[
"http://www.reddit.com/r/askscience/wiki/astronomy"
]
] |
|
95241n
|
During WWII were elderly or vulnerable adults evacuated out of London in the Blitz?
|
When doing some family research I came across an elderly relative who was born, reared and lived her entire life in London being listed in Kelly's directory as being in Birmingham in 1940. It's not the most common name, so while it's possibly just a coincidence, I am trying to think of reasons why she would have been out of London and I know children were evacuated but I was wondering if adults were as well.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/95241n/during_wwii_were_elderly_or_vulnerable_adults/
|
{
"a_id": [
"e3pigf1"
],
"score": [
4
],
"text": [
"Evacuees were mostly children, either unaccompanied or with their mothers, but others were also included in the government scheme including \"homeless persons, expectant mothers, children in nurseries, camps and hostels, invalids, old people, the crippled, and the blind\" (Richard M. Titmuss, *Problems of Social Policy*). About 4,000 old and infirm people were transferred by the government from London to hospitals in country areas by December 1940, others left unofficially or through assisted schemes - between October 1940 and June 1941 about 21,500 left London with the assistance of churches and voluntary organisations such as the Friends' War Relief Service. Titmuss illustrates the challenges the voluntary organisations could face in a footnote mentioning \"Miss Q, aged seventy, deaf, quite toothless, not very clean, living in the basement of an empty house in a much bombed area. Determined to take with her a cat, a feather bed, and two large trunks beside the usual complement of parcels, cases and carriers. The arrangements for transport for her and her luggage at both ends of the journey were not altogether easy, and the storage of her London furniture was another problem with which he had to deal. She stayed one month, borrowed money from all the neighbours, and returned to London because she couldn't 'seem to take to a place where there wasn't no Picture House nor no evening paper neither'\"\n\nBirmingham would be an odd destination for an evacuee, though; with all the industry in the area (e.g. the Spitfire factory at Castle Bromwich) it was a prime target for the Luftwaffe and heavily bombed, people were evacuated *from* Birmingham, Coventry, West Bromwich, Smethwick and Walsall."
]
}
|
[] |
[] |
[
[]
] |
|
3uphh2
|
why is the media so selective about the things they report?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3uphh2/eli5why_is_the_media_so_selective_about_the/
|
{
"a_id": [
"cxgpm8e",
"cxgqi17"
],
"score": [
2,
2
],
"text": [
"They have to be.\n\nThey only have so many reporters, so many photographers, so many pages or minutes of airtime... They can't report on everything.\n\nAs a result, they must pick & choose.",
"1. Firstly most news sources' main source of revenue is from people buying their product (newspapers, watching adverts on tv etc.), so they need views or clicks to do this, generally more people care about gossip relating to celebrities than a constant stream of \"all these people died and you should feel terrible about it\". So media outlets choose to publish things that get a lot of buyers as opposed to real news stories, this is called sensationalism or churnalism. \n\n2. Most media outlets are run by private individuals with a strict agenda, examples include Rupert Murdoch who owns everything from Fox News to The Sun in England, the Murdoch family is very wealthy and obviously doesn't like to pay tax that goes to social welfare programs because they don't need it, so these outlets only show how evil left wing/liberalism is and how great conservatism is, that's why Fox news is so biased. There are also left wing media outlets that do the same, it's all about propaganda, you're reading someone else's agenda because even though they should be, most journalists aren't neutral.\n\n3. The media has to be careful what they publish as it may effect world events. As many redditors have now begun to understand, whenever a mass shooting happens there will always be many copycats that follow if the media reports on these stories because people realise that they can gain national attention even if it is from doing something deplorable. \n\n4. There is also governmental censorship of certain things and government's will work with newspapers that share their agenda about a topic, examples include the Margaret Thatcher government of the UK in the 80s, Margaret Thatcher covered up the police's part in a disaster that took place in a football stadium in Hillsborough in 1989, she worked with newspapers to convince people it was the fans that caused to disaster and not the police who let overcrowding of the stadium take place.\n\n"
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[
[],
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a042fu
|
How did the Fleur de Lis and the color blue become integral to the symbology of Royal France?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/a042fu/how_did_the_fleur_de_lis_and_the_color_blue/
|
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"Fleur-de-lis was at first a religious symbol. It is believed that the flower of lily was used to baptize King Clovis I. It is likely that the kings of France therefore kept this flower to commemorate their ancestor's (all kings of France were his descendants) conversion to Christianity. During the 12^(th) century King Louis VI and King Louis VII put this symbol on their scepters, and the latter order that fleur-de-lis be put on his son's coronation garment (his son being Philip II). \n\n & #x200B;\n\nIt is not known when Bleu de France was first used, but it is generally believed that its use originates in the 12^(th) as well."
]
}
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[
[]
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5057wz
|
why is ac better than dc ?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5057wz/eli5_why_is_ac_better_than_dc/
|
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"Well, it depends on the application. For some things AC is better, for some DC is better.\n\nThe main advantage of AC is the ability to move it over large distances, which means you don't have to live within a mile of a power plant to have electricity in your house.",
"It's not really, with practically everything, DC is a better choice (lower losses, higher transmission efficiency, and easier to interface with modern systems). There are two main exceptions, with AC a transformer can be used to change the voltage (DC requires a relativity complex circuit) and with AC a generator and motor do not require a ~~commentator~~ commutator or any circuit other than three windings. This is not true for DC.\n\nThe major downside of DC is that the electronics to change the voltage (required to long distance transmission) have only existed at a commercially acceptable price for maybe 10 years. When they built the grids they were simply not an option (doing it with DC back then would require a motor-generator set at every house, which are expensive and fail often).",
"it's much easier to transform to a different voltage, which in turn simplifies transportation a lot.\n\nby transforming AC to a higher voltage, the same amount of power can be transported over much thinner wires. the only drawback of high voltage is that you need a good insulator between the wires and that high voltage switches are very expensive. but air is a very good insulator and you actually don't need that many switches for overhead powerlines.\n\non the other hand, quite a lot household electronics work actually at a much lower voltage than 110/230 V. these things usually have a small transformator built in their power supply unit, for example in most laptops that's the black box in the middle of the power cord.",
"The main benefit is that you can easily change voltages/amps with AC using a transformer.\n\nVoltage and Current have inverse relationship, but power used/lost depends mostly on current, so being able to transport it as a very high voltage, and very low current means you can use much smaller wires, which cost a LOT less when your talking about miles and miles. Then substations you transform it to medium voltage, then low voltage at all your houses, and businesses etc. \n\nWith DC switching between voltages takes much more complex equipment thats more likely to fail, AC only takes some wires rapped around a bar of iron, so its relatively cheap, and unlikely to fail.\n\n\nSource EE working in power distribution.",
"The biggest reason AC is better is constant power output/input. When you run a DC motor you get surges when the coils are in different positions. With 3 phase AC power output/input is constant at every step, so when on phase goes up/down the others compensate. The transformer thing is also a plus. \n\nTl:Dr Sine waves are nice. \n\nSource: I am an electrical engineer in power generation and transmission. ",
"It's not, they're different and used for different things, but both are extremely useful. It's kind of like saying \"Which is better, hands or feet?\" ",
"I wouldn't say ac is better than dc. It's just cheaper and easier to transport ac long distances. In addition to what others have said, DC current have historically had less efficiency with transporting, but we've gotten a little better at that. It should be heavily noted that we use both ac and DC current.",
"AC\n\n- Power grid easier to make. \n\n- Easier to transform to a different Voltage.\n\n- It's safer: You can stil let go of a power line when you touch it. \n\n- Easier to control the voltage under variable load.\n\n\nDC:\n\n- Difficult power grid.\n\n- Hard to transform to a different voltage.\n\n- More dangerous. If you grab a power line your muscles contract and you can't let go.\n\n- Its hard to maintain DC under a variable load.",
"AC is better for long distance energy transmission - like from the power plant to your home. Covering the same distances using DC would require full blown power stations every other mile. AC can be transmitted long distances using relatively small transformers and magnetic induction to transfer power.\n\nDC is better for short distance transmission, like from your wall to your device/appliance.\n",
"Ac current is easier to transmit over long distances.\n\nThere are certain applications one excels at more than the other... (ac is better in motors, DC is better in electronics) but for the most part transmission is the number one concern.\n\nAt the local level ac current can be stepped down or rectified as needed;each individual device has its own way of doing that.",
"I had an electrical question on an exam once. \nWhich is safer... AC or DC?\n\nThe answer:\nAC, because AC oscillates the direction of the current back and forth, thus if you were to touch an AC coupled wire, your muscles would contract and release rapidly giving you the ability to jerk your arm away. Whereas DC is a continuous current (on an oscilloscope, DC is a straight line) thus your muscles would contract and you would not be able to let go. Of course in practice, both would fry you given enough amps.\n\nDC power grids are now very efficient and soon we will not need AC grids at all. However, since the infrastructure is there and most power stations use turbines which produce oscillating AC current it's going to be around for a very long time. There is talk of DC power grids supplying renewable power (e.g. solar) to parts of Europe from the Sahara .. i'd love to see this come to life.",
"If the real question is why do we use AC, the answer is transformers. It's relatively easy for the power company to send power at tens of thousands of volts over high power lines to travel far distances with little loss, then have it go through a transformer to drop it to step it down to a more useful voltage (that won't blow up every device in your house or cause it to jump through the walls and kill you, but has the downside of not traveling as efficiently) closer to your house. You can transform DC voltages but the circuitry is more complex and difficult to do with very large amounts of power like the electric company delivers to all the houses in a city.",
"We can look at it a bit from how power distribution works.\n\nWhen we transfer electricity from a producer to a consumer, we usually transfer it a very long distance. No-one wants to live next door to a nuclear power plant and the waterfalls that are easily used for hydropower tend to be a inland somewhere a long distance from cities that are historically founded near an ocean. (generalizing things here a bit.)\n\nElectricity s easy to transfer, because all you have to do is attach a wire to a porcelain insulator that sits on top of a pole, and run the electricity through it. The wire will, however, inevitably consume part of the energy that goes into the wire and become something we call transmission loss. Transmission loss can be lowered to levels where it proves cost-efficient if you raise the voltage some 1000 times at the production site and then lower it again near the consumer in a transformer substation. The loss of the transformers are somewhere around 5% or so depending on size and cost, and some two or three different voltage levels along the way gives that you still have not even near half the loss you would have with a DC powered grid running the same distance with the same voltage. DC voltage can't be as easily altered in a cost-efficient manner, so you are stuck with what you have and that would inevitably give you costly losses.\n\nAnother thing that speaks for AC is that it's cheap to construct motors that are AC powered. It's so cheap that it's what made the first electrified industries finally putting the foot down and have their wishes heard. Lights bulbs and all that are really fancy, but them power grids were originally built to provide power to one industry that required some sort of motion, and the selling point had to be that the new fancy electricity everyone was talking about had to be cost-efficient compared to steam- and waterwheel-powered machines. Cheap motors was how it all got interesting. Without them industries, no-one would have coughed up the funds to build any long-distance wires.\n\nThe thing about AC though is that it is fantastic when you use it on wires mounted on poles, like power grids have historically always been built, but once you want it in a cable instead some really scary things happen that need to be taken into account. The three phases affect each other. because each of them create a magnetic field. Those fields can be seen as TV interference and there is some debating going around about if they cause cancer (which, if I recall correctly has not been proven nor dismissed yet, but it's a scary thought that I completely understand why people wonder about) or not, but from the power grids point of view the magnetic field needs to be handled because it creates transmission loss. If you look at a very high voltage line (say, from 100kV and up) you will notice that every kilometer or so the phases shift position on the pole. That's a transmission loss prevention measure that alters the magnetic field.\n\nNow, imagine that you want to have that very same transmission capability in a cable instead. You are basically taking those phases that don't go very well together even when they hang on a pole some ten-fifteen meters apart, and try to entwine them into a cable. This is somewhat of a pandoras box for power cables at the moment. There is no good way to do this when you reach a certain voltage. In fact, when you dig down a power cable intended to transfer anything beyond 100kV you are in fact digging down at the very least three separate cables that have to be placed five-ten meters apart - which basically makes it impossible to do that in a normal suburban road - and the cables are so bloody dangerous that the power company can't get away with just borrowing the land from the land owner, they will have to become the land owner themselves for mile after mile of roads they have no wish whatsoever to own nor maintain.\n\nThe magnetic field can also affect the cable terminations - it goes without saying that there has to be a conductive element in it, and those are also affected by magnetic fields - and those are harder to do properly if you have higher voltage, because the tolerances are lower.\n\nAC was the obvious choice when power grid started to pop up in the world, but cables where not a thing until half a decade later when cable manufacturing started to produce (somewhat) reliable grid equipment that you could actually dig down. By then AC was well stuck in the industry and chanting something that everyone has agreed on already is very hard. Especially when the needy customers dislike the higher costs of the alternative.\n\nA DC cable is a sensible alternative, because it will not create the same type of magnetic field, and in theory you only need one or two wires that won't affect each other. Still dangerous as fuck, but not affecting each other and not self damaging in the same way as a AC cable. Very high voltage that needs to run through urban areas in cable are for that reason subject to AC/DC-conversion in substations with very expensive (and power consuming, which is another aspect of expensive) equipment.\n\nSame goes for subsea transmission. If you can't use a pole and wires, you will have to go DC.\n\nSo, basically, DC would have been the sensible alternative for power distribution, but for historical reasons it's AC and will remain so.",
"*Edit* - This was supposed to be a supplemental post to others, not make it as a high top-level comment. So here's an ELI5 explanation people would expect from it. More mathematical explanation has been pushed below that.\n\n\nWhen you want to transfer electrical power, you have to push electricity through a wire to reach its destination. As electricity flows through a wire, it heats it up slightly. This is how a light bulb works - electricity flowing through a very thin wire heats up the wire until it glows.\n\nWe're going to think about it like water. If we want to transfer energy with water, we need to put it under pressure (blowing through a straw) and we need to move it through a pipe. The more water we move under a given pressure, the more energy we'll transfer.\n\nWater flows through pipes. Bigger pipes let water flow easier. The reason is that water rubs up against the sides and friction causes it to slow down. Larger pipes have a lot more area that isn't rubbing up against the sides. Think a soda straw versus a coffee straw - a coffee straw is a lot harder to drink with, or to blow air through.\n\nBut the friction between the water and the side of the pipe also depends on how *fast* the water is going. If the water is moving slowly, not much heat is generated. As the water moves faster, a lot more heat is generated and energy is wasted.\n\nSo ideally we'd like to transfer our water slowly through large pipes to deliver it over long distances. But since it's a long distance, we can't afford to make the pipe that large. So the pipe has to be fairly small and thus we need to make sure the water moves *very* slowly.\n\nGoing back to electricity, water pressure is like Voltage, and the speed of the water is like Current. Current times voltage equals how much power we're transferring. So if we increase the pressure by a factor of 10 - increase the voltage, we can drop the speed of the water - the current by a factor of 10. If we multiply the voltage by *one million* we can drop the current to *one millionth* of the original speed and still transfer the same energy. At those super-slow speeds, the water rubbing against the pipe isn't going to waste any energy at all.\n\nAC power lets us use a cool device called a transformer that lets us take in voltage and current on one line, and output a different voltage and current with the same total power on another line. We can't do this efficiently with DC power. So we use AC power because we can step up the voltage to super-high levels, and drop the current to a trickle.\n\n \n\n\n---------------------\n\nLarge number of correct answers - but none are describing the mathematics of why, so I thought I'd add it. The Short version is that resistive loss of power transmission is a function of resistance in the wire, multiplied by the square of the current. So high current leads to *very* high resistive losses heating up the power line and wasting energy. Some examples:\n\nPower (energy in a set amount of time) is a function of the voltage on the power line multiplied by the current. So if I wanted to run a winch that lifted up a 1kg weight at 1 meter per second, I'd need a motor than ran on 10 volts of DC power with a current of 1 amp.\n\n > Electric Power Draw: \n > 10Volt x 1Ampere = 10 Watts = 10 joules/second. \n\n > Potential Energy of Weight: \n > 1m/s x 1kg x ~10m/s^2 = 10 Nm/s = 10 joules/second\n\nSo they're balanced. However, if I had a motor than ran off of a 20 Volt power, it would need only draw 0.5 Ampere. At 100 Volts, it'd need draw only 0.1 Ampere.\n\nThen the question goes to power distribution. Why is there a limit to how far we can deliver electricity from a power plant? We have to run electricity through wires. And when we run electricity through a wire, it heats up slightly and loses some energy.\n\nThat power is equal to the resistance in the wire multiplied by the *square* of the current. RI^2 = resistive loss.\n\nSo lets change our example above a little bit. Now we're lifting huge wrecking ball that weighs 10,000kg.\n\nTo lift it at 1meter/sec would require 100,000 joules/sec or 100Kilowatts. Using our 10 Volt motor, we would need to draw 10,000 Amps.\n\nNow lets say that the we have a very thick wire that is 10 meters long, and has 0.0001 Ohms of resistance per meter. So almost no resistance. \n\n > Overall resistance R = 10m x 0.0001Ohm/m = .001Ohms \n > Overall Current = 10000 Amps \n > Resistive Power Loss = 0.001O x 10000A x 10000A = 10^5 W or *100 Kilowatts of power as waste energy!*\n\nWe're burning as much energy just *transferring* the power to the motor as we're actually using for the motor.\n\nSo lets switch our 10 Volt motor out for a 100 Volt Motor. The power demand remains at 100 Kilowatts. \n > 100,000KW = 100Volts x ?Ampere \n > current I = 1000Amps\n\n > Resistive Heat Loss = 0.001 Ohms x 1000Amps x 1000Amps = 1000 Watts = 1 Kilowatt of waste heat.\n\nStill a lot of waste, but it's actually manageable now. we're only spending 1% of our power draw heating up the wire during transmission.\n\nIf we used a 1000 Volt motor, we'd only pull 100 Amps and our restive heat loss would be 10 Watts across the whole thing. A tenth of the energy spent on an incandescent bulb, spread over 10 meters. The wire wouldn't even be warm in your hand.\n\n\nSo clearly, when transferring power with electricity, we need to keep the current as low as possible because the energy lost is a function of current-squared. We also can't make the resistance too low because thick wire becomes prohibitively expensive over millions upon millions of meters of power lines.\n\nSo if we want to transmit, say, 1 Gigawatt 10 kilometers from a power plant to a city, with 6 gauge wire (1 Ohm per kilometer), we need to figure out how bad that will be.\n\n > P = 1 Billion Watts \n > R = 10 Ohms\n\nIf we step the voltage up to 1 Million Volts, we'd still have 1000 Amps of current, and would lose 100 Megawatts of power - 10% to heating up the power line.\n\nIf we get up to 10 Million Volts, we'd need 100 Amperes, and now our losses are 10 x 100 x 100 = 100 Kilowatts of loss. Which is still a ton of energy, but its spread out over 10 kilometers and represents only one ten-thousandth of the energy transferred as a loss. \n\nAs others have repeatedly said, AC power lets us use transformers, which very easily and efficiently let us maintain the *power* of electricity flowing, but trade voltage for current. So I can transfer the energy of a circuit running at 10 volts with 100 amps into a circuit running with 1000Volts at 1 Amp. Or 1 Million Volts at 1 miliAmp.\n\nSo for power distribution in our country, we generate power at a station, we step it up to hundreds of thousands of volts and transfer it across the country on those *massive* high-voltage power lines. Those lines go to a few dozen sub-stations located around your town, that step the voltage down to ~10,000Volts. That energy is carried along power lines to neighborhoods, where every 1 to 5 houses share a small green box somewhere that transforms the voltage down to 120 Volts, which is then delivered to your wall outlet.\n\n\n\n\n\n",
"It's not but it is easier to transport over long distances. Basically it has to do with the fact that when you transfer voltage it has to be high because the higher the voltage the lower the resistance. Now this can be done with AC or DC, but the advantage of AC is that in order to use in homes you have to transform it into a low voltage once it gets there, and AC is just easier and cheaper to transform. ",
"AC is just different. Both have pros and cons and should be used where it makes sense.\n\nIt's like using single mode vs. multi mode fiber or PVC vs. lead vs. copper vs. whatever else pipes.\n\n",
"As someone who lives in New Jersey that recently visited Washington, DC this was very confusing.",
"It's not. They are different for different purposes.\n\nYou might as well as, what is better odd numbers or even numbers?\n\nBetter for what?\n",
"There is an implication in asking \"Why is AC better than DC\" and that is \"for commercial power production and transmission to consumers and businesses\" because you would otherwise have to define what 'better' means. It is akin to asking why is hot better than cold. \n\n\nThe short version is that to get power from a far off generator, into your cable modem at home is best accomplished with a minimum loss of power, and with the greatest efficiency and safety using alternating current for power transmission. \n\nThink about a circuit. You form a circuit and electrons flow in one direction from one side of the circuit to the other. If this circuit is 100 miles each direction, that is an awfully long way for an electron to travel and this creates a lot of heat and loss of power along the way. After all it's not the distance the electron travels that lets it do work, but merely it's movement. It does just as much work going back and forth as it does moving only forward, but since the direction changes 60 times a second, it never travels very far. So alternating current is great for transmitting power at long distances without needing prohibitively thick cabling. \n\nAs an added bonus, most heavy machinery used in factories runs on alternating current directly without needing any complex circuits. This was likely the reason that AC won out over DC back in the early days. It could deliver lots of power, a long distance, and be more easily turned into mechanical work for factories. \n\nDC at the time needed much thicker cables, and it still could not be sent over more than a few miles at a time so instead of one big station sending power to a region, it needed hundreds of smaller neighborhood power stations sending power close by. And when that power arrived at a factory it had to be converted into alternating current to run the big motors that drove the factory which caused a loss of power and a lot of heat. \n\n\nSo to summarize\n\nAC: \n\nBenefits: long transmission distances with minimal loss of power. \nCan easily be stepped up and down with transformers to raise or lower voltage without complicated electronics or loss of power. \nThinner wires. \n\nCan run industrial motors directly. \n\nProblems: \nMany electronics run on DC so we need bridge rectifiers and mosfet switching power supplies to provide stable power for electronics. This wastes a little energy as heat and adds to the cost of consumer goods. \n\n\n\nDC: \n\nBenefit: Can directly power your clock radio\n\nProblems: Size of cables. Distance of travel. Can't drive industrial motors directly without expensive stepping controls and complex control circuitry which limits the size and power of the motors. Lots of energy loss as heat. No easy way to change voltage without lots of electronic circuitry which are not as robust as the simple transformers used in AC. \n\n",
"Imagine you have a pulley system in front of you, with one pulley on each end, and a rope looped around both. You're standing near one pulley, with a wooden stick pressed against the rope near the other pulley. Your goal is to try to start a fire by rubbing the rope as fast as you can against the stick that's on the other end.\n\n**DC** means you could only pull the rope in one direction, so you have to pull it as fast as you can in order to start a fire.\n\n**AC** means you can grab a hold of the rope, and tug it back and forth in short jerks.\n\nIn this example, it's easy to see how AC would beat DC in terms of transmitting your energy from your arm, to the stick that is far away from you. This is one of the advantages of Alternating Current. The electricity flows both ways, enabling the energy to perform work to be transmitted a longer distance more efficiently.",
"AC isn't \"better\" than DC. In fact most modern electronics use DC for good reason! So why do our homes have AC not DC going to them? Because it's easier to transport than DC power!\n\nThe reason it's easier to transport is due to two components of electricity called voltage and amperage. Voltage is like the potential energy of electricity, and amperage is the current or ability to do work. The total amount of power in a wire is a product of voltage and amperage. However, only amperage determines the thickness of the wire used to transfer electricity.\n\nSome people use a water-pipe analogy to explain electricity, but instead, I want you to think about raised aqueducts like what you might find in ancient Rome. Voltage would be how high the aqueducts are from the ground, and amps are like the speed the water flowing through it.\n\nThe benefit to AC is that it's easy to step up and step down the voltage. So it's like raising or lowering the aqueducts. When we lower an aqueduct, the water flows downhill and speeds up. In other words, stepping down AC voltage increases its current or amperage!\n\nA city is a big place, and it requires a lot of power! Power can be thought of as a product of amps and voltage. However, the more amps you send through a wire, the bigger wire you need to handle all that current. A city's worth of amperage over a 120 volt line would require cables thicker than cars!!! Going back to the aqueduct example, the more water that flows through an aqueduct, the bigger you have to make it.\n\nLuckily, an inventor named Tesla had an idea! Why not send electricity at a really high voltage and relatively low amperage, then use transformers to step down the voltage and raise the amperage at the destination?! That way, a big power plant can send power to an entire city using relatively thin wires. \n\nSince AC is easier to step up and step down the voltage compared to DC, all our homes receive AC power. If we used DC power instead, we would have needed power plants on every block. \n\nIf you pay attention to your surroundings, I'm sure you'll find lots of transformer boxes around your town converting higher voltages to lower voltages so each home can get the power it needs. These transformer boxes are easiest to work with AC power, and thus, all our homes run on AC. :)",
"All those posting that DC can't be transmitted long distances might be interested to know that most of the power for Los Angeles arrives via high voltage DC transmission lines. 3.1 gigawatts via the Pacific DC intertie (Path 65), 850 mi long, starting from the Oregon Washington border, and 2.4 gigawatts via Path 27, 500 mi long, starting in central Utah",
"It is probably better to say that they are better for different purposes than to say that one is better than the other. ",
"It is not \"better\". In fact we use DC in most things rather than AC. But right now it is impractical to transmit DC over long distances so we use AC for getting from point A to point B then then transform to DC because that is what the devices need internally.",
"I am not going cover much but I would just like to correct a misconception in many of these replies. High voltage DC power actually transmits along long range power lines more efficiently than AC especially in underwater cables. But transformers for stepping down the voltages for home use have historically been much cheaper, more reliable, long lasting and efficient when designed for AC current, historically the only way to transform DC current would be a motor and generator with different windings on the same rotor. DC electric motors and generators also require brush contacts on the motor which can wear out or create inefficiencies. As the AC DC converters have gotten better [HVDC powerlines](_URL_0_) have become a more effiecient option for long range and underwater power transmission.",
"AC is like a rolling wheel of electricity while DC is like a sled that slides along. The wheel is easier to push faster for longer distances than the sled on any surface. The AC's \"rolling\" means that it propagates longer over wire and is more convenient to generate: since we can easily make a power source that turns (like a water wheel, wind mill, horse pulling a cart, or gas turbine engine) we can very efficiently turn a spinning shaft into \"rolling\" electricity that will be consistently proportional to the input speed. Similarly it's very easy to control, split, and transform \"rolling\" electricity to multiple lower speed wheel outputs, and also very easy to convert it back into a high power spinning motion like in a kitchen blender.",
"This is a particularly hard one. I wouldn't necessarily say that AC is better than DC. They seem to work best hand-in-hand. While I quite enjoy a cold room, I also do love my batman comics. Best scenario, batman comics in a cold room. ",
"\"One of the reasons that AC might be considered more dangerous is that it arguably has more ways of getting into your body. Since the voltage alternates, it can cause current to enter and exit your body even without a closed loop, since your body (and what ground it's attached to) has capacitance. DC cannot do that\" ~ [Source](_URL_0_)",
"AC(armor class) more commonly at low levels and against martial enemies comes into play than saving throw DC (difficulty class). Additionally, there are 6 ability scores with separate saving throws. It is much easier to optimize AC to mitigate damage than all six abilities when you cannot max them all. \n\nI had to go to the comments to realize this was not one of my d & d subs. ",
"Maybe you meant to ask *when* is AC better than DC?",
"AC is not better than DC or wise-versa. They both have their magnificent applications. AC is better for power transmission while DC is better for powering circuits, and then the circuit will convert it into a mixture of AC and DC at a grand spectrum from 0 to giga Hertz of frequency! It is an unimaginable world of beautiful and yet killer power! I almost like to break into a song!",
"Both do certain things well. AC has better transmission efficiency. Edison was pushing hard for DC but having a grid based off of DC would have required massive cables and power plants every few blocks. DC is really easy to build circuits around. AC is also very easy to turn into DC. On macro scales AC wins because of the efficiency and ability to centralize production. On small scales DC is dominant because its easy to use.",
"It has a lot to do with motors:\n\n**AC's advantages**\n\n* Cheaply generated by the AC alternator motors at the hydropower dam, wind turbine, coal and nuclear power plant. DC dynamos (alternative to AC alternator) are inefficient and require expensive maintenance more often. \n* Cheaply transportable through the wires by means of voltage conversion via transformers.\n* Voltage conversion through cheap basic transformers and still achieve the same high-quality, low-loss sine wave. Efficient DC voltage conversion is expensive with all the MOSFET transistors and big capacitors needed, and it always generates high-frequency electrical noises.\n* Appliances (aircon, fan, washing machine, etc) can use cheap AC motors to run off AC power. \n* Cheaper to convert AC to DC using a single rectifier, than DC to AC using multiple power transistors.\n\n**DC's advantages**\n\n* Modern electronics always run on DC power due to the fact that CMOS chips do DC digital operations, as DC offers stability and predictability to the chips.\n* These CMOS chips are not just CPU. They are everything from RAM, flash memory, to LED emitter, OLED display, camera sensor, CPU, GPU, transistors, microprocessors and more.\n* DC is easy to deal with. Much simpler formulas. Easier to electronically control the voltage and current at low power.\n* DC is generally safe to human touch at 48V or less (although higher DC voltage is actually more dangerous than AC). AC can interfere with the electrical signal that our heart, brain and muscles use; it can confuse our heart and make it stop. \n\n\nYou can see that both AC and DC have their own unique uses that the other can't replace. It's the two sides of one coin.",
"EE here. I would say that AC used to be better, as everyone says, because you can step it up and down with a simple transformer. However, these days, DC can also be stepped up and down using a DC-to-DC converter, and these have become very good and cheap. They basically consist of a DC-to-AC converter, a transformer and an AC-to-DC converter. There are important advantages to this which more than compensate for the extra complexity. For one thing, the size of the transformer depends on the AC frequency. Higher frequency = smaller transformer at the same power rating. Using a DC-to-DC converter, you can choose the frequency, and the most economical choice is usually WAY higher than 50-60 Hz. Every computer power supply sold today actually does this, and operate at frequencies between 40 kHz and 2 MHz. Otherwise, they'd be big, bulky and expensive. Similar savings could be made in power distribution transformers if we used DC for transmission and only used AC right around each transformer. Also, DC has less power loss in HV transmission lines than AC. In fact, some of the very beefiest power transmission systems in the world use DC despite the extra complication involved in converting to and from 50/60 Hz on either end (see [HVDC](_URL_0_)) So I would say we are stuck with AC as a legacy standard because it used to be better, not because it is.",
"Several reasons:\n\n* More efficient to transport long distances.\n\n* More suited for elecrical motors (remember, in the beginning, electricity was mainly for motors, lamps (which don't care about AC or DC) and heating (which also don't care)).\n\n* Transformers need AC to work, so to transform between different voltages, it's much easier.\n\n* It's easy to go from AC to DC, and harder to go from DC to AC.\n\n* Polarity is not an issue, so outlets does not have to have a fixed polarity.",
"Okay, so imagine you've got a bunch of metal balls in a long pipe about the same diameter of the balls. Pretend you're feeding some more balls into one end so some come out the other end. You'll intuitively notice that it takes a bit of effort to push all the balls at once as there's friction between the balls and the pipe. This is DC.\n\nNow imagine a [Newton's cradle](_URL_0_). With a Newton's cradle you can slap one ball into the others and watch the ball at the other end swing out. The balls in the middle hardly move at all, but the energy still goes through. So now imagine you can slap the first ball again and again at a steady rate - the ball at the other end will swing out at the same rate. Given a way to capture the energy of the final ball, we've created a way to transport kinetic energy without transporting the balls across the whole distance - they just move back and forth a tiny distance. This is AC.\n\n____\n\n*However*, things like computer electronics and stuff can't use AC because they need to manipulate the individual balls and trap them in transistors and stuff. So we need to use DC for them. AC is great over long distances though.",
"DC isn't better than AC. Simply put, AC is better suited to travel long distance, like from the place it's generated, to your house. ",
"None of each is \"better\".\nThere are applications where DC is better and there are applications where AC is better. But it would be more than wrong to say this or that is better. Source; electrical engineer "
]
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[],
[
"https://www.google.com/search?q=does+ac+blow+you+back&oq=does+ac+blow+you+back&aqs=chrome..69i57.15966j0j7&sourceid=chrome&ie=UTF-8#q=ac+vs+dc+danger"
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"http://s.hswstatic.com/gif/newtons-cradle-1.jpg"
],
[],
[]
] |
||
1vms04
|
Where cannon balls explosive as seen in movies or where they just balls of metal?
|
In many pirate movies cannons fire balls that explode when they hit enemy ships aswell as in movies like "the patriot". Is this accurate or were they just balls of metal that ripped through ships?
edit: it's late and I have just seen the typos in the title.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1vms04/where_cannon_balls_explosive_as_seen_in_movies_or/
|
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"The other post is wrong, as far as I understand - the word cannonball refers to things that weren't rockets, grapeshot, or exotics like carcasses. However, there are 'shot' cannonballs and 'shell' cannonballs. The Huolongjing, a famous 14th century Chinese treatise, references both, specifically talking about round, hollow metal shells that would be filled with gunpowder, and (IIRC) the context was about use in cannons, not just trebuchets or the like.\n\nI don't think they were used in Europe for some time, but Chingis Khan was using shells on open fields and during siege.\n\nIt's a ball, and it goes in a cannon, and I believe that qualifies to be a cannonball.\n\nSo, were there explosive cannonballs? Yes. In naval warfare? Yes! [Here, after just a cursory search, is an account of the adoption of shell-firing guns.](_URL_0_) For a tl;dr:, the book represents naval minds strongly cautioning against the use of shell guns, because they were relatively low-range - they couldn't pack too much of a punch because that would detonate the shell - and the shells themselves were unreliable. Shot, on the other hand, is quick, safe, and accurate - the explosive power didn't mean so much when you could just tear through wooden decks with sheer momentum.\n\nEDIT: And there is a serious difference between a carcass and a shell. A carcass is a lit incendiary, meant to spill open when it lands. A shell is an explosive, a gunpowder weapon.",
"The word \"shrapnel\" comes from an English officer named Shrapnel. He invented a shell with a fuse that would explode some time after it was fired, spewing small metal balls at the enemy. Wikipedia has the first use as 1804. \n\n_URL_0_\n\nThe US national anthem mentions \"the bombs bursting in air\" during the British attack on Ft. McHenry in 1814. This was a naval bombardment where exploding shells were used. However this type of shell was fired from a short barrel mortar or howitzer, at a high trajectory to the target. \n\nOne needed the high trajectory to allow time to light the fuse, load the gun, then shoot it before the fuse blew. The naval canon which shot a flat trajectory had too short a flight of its shell, making an exploding shell dangerous to the gun crew.\n\nIn the mid 1800s a system was developed to arm the shells as they were fired, allowing their use in cannon.\n",
"Can someone reference civil war cannonballs? I was under the impression that round, solid iron balls (i.e. \"cannonballs\") were a very viable and common weapon in civil war battles because when fired at massed infantry, you would essentially be taking out several soldiers as the cannonball passed through a group of them.\n\nAnd I believe these balls are still around, stacked in pyramid shapes at various museums, monuments, etc (and presumably not packed with explosives).\n\nThanks to the OP for this very interesting question!",
"Okay, I'll try to give you a succinct answer, because some of the answers in this thread are all over the place. \n\nIn the era in question, all firearms fired round projectiles. The reason for this is because rifling was, due to the powder and materials used, unfeasible for practical use. A cylindrical projectile without spin will wobble out of control, while a round projectile will at least simply turn on its own axis. \n\nSo, the problem with round projectiles is that you can never know with which end it will hit, which makes the idea of percussion fuse untenable. Instead you're left with two choices: either solid shot or a timed fuse attached to a shell. In the general sense, cannon would fire solid shot at high speed in a straight trajectory while mortars would fire shells, which due to their fragility would be fired at lower speed in a ballistic trajectory. During the 18th century a compromise between the two, the howitzer, began seeing use: a indirect fire weapon firing at a slight angle, firing shells. Now, indirect fire is great if your target isn't moving about, like a fort, but kind of useless otherwise, because the art of ballistic calculation is still in its infancy, and sighting has to be played by ear. \n\nSo, to return to your question: infantry and ships were both moving targets at relatively short range, so direct fire was by all means preferable to indirect fire: hence both ships and land armies both used solid shot (ignoring grape and canister for the moment). A cannon ball striking a ship wouldn't explode, but would strike through the hull causing damage and splinters as it went, while round shot fired at infantry would bounce along the ground knocking off limbs as they went. \n\nLastly, not that I would ever defend an atrocious movie like The Patriot, but in Mel's defense I don't think it ever showed a cannon ball exploding. ",
"As an incidental answer to the second part of your question, \"were they just balls of metal?\" I can tell you that during the English Civil War, iron balls were not universally used on land. Stone cannonballs were often employed, despite being less penetrative or powerful, as they were cheaper and easier to provide."
]
}
|
[] |
[] |
[
[
"http://books.google.com/books?id=Qz5KAAAAYAAJ&pg=PA6&lpg=PA6&dq=naval+warfare+shells&source=bl&ots=c4YYQ4vGey&sig=J4bDAkyWR2pYwokClkb2LdRKrTQ&hl=en&sa=X&ei=-oPcUrW6L4T4yQG87ICoCg&ved=0CFYQ6AEwCg#v=onepage&q=naval%20warfare%20shells&f=false"
],
[
"http://en.wikipedia.org/wiki/Shrapnel_shell"
],
[],
[],
[]
] |
|
3sssxi
|
how come light doesn't go through objects like walls of their atoms are made of mostly empty space as proved by the gold foil experiment?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3sssxi/eli5_how_come_light_doesnt_go_through_objects/
|
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"I would think it has to do with the photons being blocked by the cloud of electrons surrounding the atom, so even though by volume it is mostly space, it's more like an opaque hollow sphere. ",
"The difference is that the gold foil experiment fired *alpha particles* (which are Helium atoms but without electrons) at high velocities at the gold foil, not *light*. The two interact completely differently with atoms.\n\nYour question is kind of like asking \"How come cannonballs can go through walls while light can't?\"\n\nWhile the alpha particles can (largely) ignore the electron 'shell' about an atom, light interacts heavily with this layer.",
"The wavelength of visible light is much bigger than the size of atoms. Visible light doesn't really interact with individual atoms (unless it's absorbed, but that's based on frequency, not size).",
"A forest is mostly empty space too, but if you run a car into one at 100 miles and hour you're likely going to have a tough time making it very far.\n\n",
"easy answer...the gold foil experiment only had a \"single\" layer of atoms (in reality, it was more than that, but not much) and that like shooting a pea through a goal posts but when you get more layers, it is like playing Plinko and the distance between pegs gets SO SMALL that light cant make it all the way through (usually it gets stopped and bounces off the first row) ",
"Very thin (nanometer sized) gold sheets actually are transparent. Also blue, interestingly enough.",
"For the wavelengths of interest for visible light (~300-700nm), the primary interactions of photons with atoms are the photoelectric effect and Compton scattering. Both of these interactions are with the atomic electrons due to the wavelength of the light being on the order of the DeBroglie wavelength of the electron. For higher energy photons, there are photonuclear reactions where the photon interacts with the nucleons in the atomic nucleus.\n\nThe issue with comparing this to the gold foil experiment is that the gold foil was irradiate with alpha particles which have an electric charge and interact directly with the coulomb field of the atom. Alpha particles are electrically charged and tend to have a much higher energy than visible light photons. This being said, they are deflected by the electric field surrounding the atom but can also scatter of the nucleus because their large momentum can strip atomic electrons from their orbitals and allow the alpha particles to get closer to the nucleus. It's really two different sets of interactions for photons and alpha particles so you can't directly compare the two."
]
}
|
[] |
[] |
[
[],
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[],
[],
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] |
||
20cvo8
|
Why do males have two testicals as opposed to one?
|
Is there any benefit to having two? Why have we evolved to have two, and not just one?
|
askscience
|
http://www.reddit.com/r/askscience/comments/20cvo8/why_do_males_have_two_testicals_as_opposed_to_one/
|
{
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"text": [
"Bilateral symmetry. Humans, at least, begin life as female in the womb. After a certain point of development, If you are meant to be male, you differentiate into a male. Labia fuse to form the scrotum, ovaries differentiate into testes, and the clitoris becomes a penis.",
" > This is because bilateral symmetry evolved a very long time ago, at least 500 or 600 million years ago. Our body plan has been locked into bilateral symmetry since that point. \n\n > The early embryo has an outer layer, a single midline tube passing from mouth to anus to become the gut. From the single and simple midline tube, is developed the intestines. However many other organs develop from it by a system of budding from the tube. Such organs include the lungs, the liver, the pancreas... and whether these become a single organ or two organs depends on whether the bud that grows from tube stays as a single bud or divides to grow more than one. The liver for instance is a single organ whereas the lung comes from two buds to give the organs that we see in the developed child. So what about the kidneys I hear you ask? Well, they develop not as a single tube, as with the gut, but on either side of the body quite separately. \n\n_URL_0_ Not the most reliable sources.\n\nBut this explanation works pretty well for me at least. Some parts of our body develop from a single system (the midline tube) as an embryo while others develop later in the form of budding. And all of this is carried from our ancestors for unexplained reasons. The environment of all the species that branched out since had never been challenged in reproducibility to change into some other form of symmetry or asymmetry."
]
}
|
[] |
[] |
[
[],
[
"http://www.thenakedscientists.com/HTML/questions/question/3091/"
]
] |
|
4llejw
|
Why are we able to feel any part of our body when we think about that certain part?
|
Think about your butt and suddenly you feel the pressure and tension it makes with the object it's seated upon.
Think about you toe and you suddenly feel the surface it's exposed to.
Why does this happen? Are we always aware of feeling but only able to feel when we focus on a body part? Are action potentials being generated (constantly)?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4llejw/why_are_we_able_to_feel_any_part_of_our_body_when/
|
{
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"d3oeicf"
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"text": [
"Well technically your brain ignores certain feelings until they surpass a signal threshold and or you stop blocking the signals. Imagine you live near a busy street. After a while of constant noise you will begin to block it out until you think about it, then it's obvious. So the brain is constantly blocking signals you have deemed un necessary through training. I imagine as a baby before we begin to block signals you would feel every bit of your body all the time."
]
}
|
[] |
[] |
[
[]
] |
|
50hzlv
|
what is data mining?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/50hzlv/eli5_what_is_data_mining/
|
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"text": [
"Gold mining is digging though rock and dirt looking for clumps of gold that is worth anything. Data mining is digging though tons of random looking data looking for the pieces of information that is worth anything.",
"Suppose that every school day your teacher writes down in a notebook what color the playdough each student plays with and she does it for years. \n\nWhen you data mine you look through that entire notebook and try to find patterns. \n\nYou might, for example, count the number the of students using Blue on a given day (Statistics) or ask your friend \"da computer genie\" for help (Artificial Intelligence, Machine Learning) etc You use various techniques in order to find certain obscure patterns in data . In this case you might find out that all boys named Jessie like to play with Green playdough. ",
"Looking for patterns in large amounts of data.\n\nA well known case from a while back was this: retailers have a huge database of what customers bought. An analyst had this idea: You can tell when a woman has just had a baby because for instance she has started buying diapers. But is there anything in a woman's buying patterns that changes before she gives birth? Then you could for instance send her ads or free samples, and make her more likely to use your product.\n\nTurns out that yes, you can do that. Look at the women you know that just gave birth, then check if the history of their past 9 months has anything that distinguishes them from the average woman. And you will find things like a pattern of stopping to buy alcohol, buying vitamins, etc. With enough data you can fine tune this by a lot, to the point of figuring out pregnant women before they even told anybody yet.\n\n[It was in the news](_URL_0_)",
"Essentially, going through raw data and finding trends within. \n\nI took an intro class to data mining in college, and for our main project we were given a set of raw data concerning computer programs in the 1980s. Using a tool called [Weka](_URL_0_), we could focus on one dependent variable (number of bugs, in this case) and several dependent variables (length of the code, number of comments, action statements, etc), creating either linear regression equations or decision trees, either of which could be used to predict future cases.",
"Aww yiss something I can explain!\n\n**Data** is just bits and pieces of numbers and text. For example results of a running competition at a local school. It is composed of observations and variables. Let's say we have runners Mike, Jane, Thomas and Hannah and they start doing laps. When Mike completes a lap, we have a new piece of data called an **observation** which is set of individual data pieces called **variables**! And then Jane, and then Thomas and Mike again and so on until we have a **data set**. We write down the name of the runner, the result, the age, weather and date and time of the run. These are our variables!\n\n| name | result | age | weather | datetime |\n|---|---|---|---|---|\n| Jane | 16 | 13 | dry | 2010-09-12 11:00 |\n| Mike | 55 | 13 | ice | 2010-01-12 11:00 |\n| Hannah | 36 | 17 | snow | 2010-02-12 11:00 |\n| Thomas | 6 | 17 | dry | 2010-06-12 11:00 |\n| Mike | 11 | 13 | rain | 2010-06-12 11:00 |\n| Jane | 15 | 13 | rain | 2010-10-12 11:00 |\n| Jane | 306 | 13 | dry | 2010-03-12 11:00 |\n\n\nWe have multiple variables for each observation. Using data mining algorithms the software can determine rules that during the summer it can be rainy or dry, during the winter it can snowy or icy, autumn or spring rainy or dry. It can also make a rule that older runners are faster, while bad conditions (ice,snow) make worse results than during better (dry,rainy) conditions and so on. This is how advertising products to you works in online stores. A large data set of what people bought, and the software determines that people that bought iPhones also bought an iPhone case of some kind and perhaps a screen protector. (Some software is smarter, some is dumber).\n\nNotice that one result is different? It is called an **outlier** or an **anomaly**. Perhaps Jane tripped or did cartwheels all the way. Software can detect those too! Perhaps your credit card information was stolen, and the bank is able to determine that buying stuff at a strip joint for 1000 dollars at a Tuesday night is an anomaly, because you normally don't go spending 1000$ at a strip joint on Tuesdays even though you sometimes go to a strip joint, sometimes spend money on Tuesdays and sometimes spend 1000$ but the combination of these is abnormal.\n\nThe process of extracting **information** and **knowledge** from data is what data mining is.\n\nRelated keywords are machine learning, anomaly detection, data science, data analysis, business analytics, prediction, statistics"
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.businessinsider.com/the-incredible-story-of-how-target-exposed-a-teen-girls-pregnancy-2012-2"
],
[
"http://www.cs.waikato.ac.nz/ml/weka/"
],
[]
] |
||
3g515p
|
Why did American revolutionaries keep place names like "New England" and "New London" after the expulsion of the British?
|
I live in China. After the revolution, anything in public places named after the old guard was quickly changed to match the new powers that be. Why didn't New England turn into New Washington (or something similarly revolutionary)?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/3g515p/why_did_american_revolutionaries_keep_place_names/
|
{
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"I'm not sure if anyone has examined this subject in a conclusive or comprehensive way, but the few examples of names either changing or staying the same during and after the Revolution tend to depend on local politics more than a centrally-planned national campaign to change names. Most of my examples will come from New York, which is the state I am most familiar with and can furnish some interesting examples.\n\nThe names that did not change were those around New York City. Loyalism had run strong in some quarters of the City and Long Island before the British invasion, and the British held Manhattan, Staten, and Long Islands throughout the war. Loyalists from across the Northeast fled to British lines throughout the war. While many evacuated with the British at the end of the war, some must have stayed. As such, there was not much of a push to rename Kings and Queens Counties, though Kings County is more commonly called Brooklyn today.\n\nFurther north, some names were changed. In 1782, the town of Hanover, settled largely by Palatine Germans but politically led by the loyalist-leaning Colden family, changed its name to Montgomery in honor of fallen Continental Army General Richard Montgomery. Interestingly, the militia and town committee (the revolutionary body that ran the town in the place of the deposed official government) were thought to be under \"undue influence\" of the Colden family, and thus were not trusted to arrest suspected loyalists in their own borders. Replacing the name Hanover, the German province where King George III's family was from, with the name of a martyr of the Revolution may have been a way to bone up on their Revolutionary credentials.\n\nFurther north, the lands around the Mohawk River were divided between Tryon and Charlotte counties, named after one of the royal governors of New York and George III's wife, respectively. This region saw some of the fiercest fighting of the war. Many of the inhabitants were Scots that had settled along the Mohawk after the Seven Years' War. When fighting broke out, the majority of these Scots, led by the powerful and influential Johnson clan that dominated the region, remained loyal to the King that had granted them their lands. These loyalists fought hard alongside their Iroquois (Native American) allies during the war, but the British surrender cost both the loyalists and the Iroquois their lands. After the war, the New York State legislature [changed the names to Montgomery and Washington counties](_URL_0_) as Continental Army veterans moved into the region. Montgomery County later went through several subdivisions, one of which is named after Baron von Steuben, a Prussian officer who trained American soldiers during the war. \n\n"
]
}
|
[] |
[] |
[
[
"http://history.rays-place.com/ny/tryon-cyt.htm"
]
] |
|
2v904m
|
why can't spacex let the used rockets land in the ocean, then retrieve them rather than trying to land on a barge?
|
Seems like there should be a cheaper, more cost effective alternative, but I'm sure someone can explain.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2v904m/eli5_why_cant_spacex_let_the_used_rockets_land_in/
|
{
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"text": [
"Cleaning the salt and other ocean contaminants off of the rockets is expensive.\n\nWhat you propose is what the [Space Shuttle rockets did](_URL_0_). While a reliable system at the time, the same benefits could be achieved for less cost by landing the rockets on a barge or other area such that the refurbishing costs are significantly reduced.",
"They want to land them safely and reliably on land, eventually. Saltwater exposure makes reusing their rockets more problematic and more expensive. So, once they get through the costs of developing a reliable on-land recovery, the rest -- *as they say* -- is gravy."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Descent_and_recovery"
],
[]
] |
|
zw8mj
|
why can places like newegg ship ups for free when it costs regular people so much money?
|
I bought a Storm Trooper computer case a while back, and for those who don't know, this is a huge 45-pound steel case. Newegg offered free 3-day shipping via UPS. Now I'm trying to sell it, and UPS wants a minimum of like $50 to ship it. Are they just losing money on places like Newegg or am I getting ripped off?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/zw8mj/eli5_why_can_places_like_newegg_ship_ups_for_free/
|
{
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"text": [
"Volume.\n\nCarriers like UPS commonly offer discounted rates to companies that do a lot of business with them. It's not hard to see why; a company that does a *lot* of shipping can choose among several worldwide shipping companies, and not getting that business means losing a lot of revenue. So carries are highly incentivized to compete on price.\n\nOnce the price gets low enough, the company doing the shipping can absorb the marginal cost — say, eating $3 on a $100 purchase. This reduces their profit margins, but if it wins them enough extra business from their competitors, they end up with the better end of the deal."
]
}
|
[] |
[] |
[
[]
] |
|
84n0oz
|
what would be the environmental issues with sinking large quantities of trash into the mariana trench?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/84n0oz/eli5_what_would_be_the_environmental_issues_with/
|
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2
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"text": [
"You didn’t deal with the problem you just dumped it out of sight. It’s like sweeping dirt under the rug. Eventually you’re going to have to pull up the rug and clean that up too. So you just delayed the problem and potentially made it worse from pollutants leaking out of the garbage. "
]
}
|
[] |
[] |
[
[]
] |
||
1rl7wk
|
Were the Republican forces in the Spanish Civil War thankful for the help of the International Brigades, or were they viewed as a nuisance?
|
I'm sure some of the volunteers who had extensive military training were appreciated, but I'm thinking more of the many artists and intellectuals and political activists who made their way to Spain to fight. Were they a real help, or were they a liability?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1rl7wk/were_the_republican_forces_in_the_spanish_civil/
|
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"According to George Orwell in \"Homage to Catalonia\", who himself was a volunteer for the Republicans, the International Brigades were viewed quite positively by them. They would fight side by side with each other and were usually treated as equals.\n\nI would highly recommend reading it, it is perhaps Orwell's best book and gives a lot of insight into the Civil War.",
"One thing to keep in mind is that the Spanish Civil War was *incredibly* chaotic. The fate of a particular town or city could be decided in mere minutes. Whomever could muster the most firearms in the least amount of time would end up in control. This was often an army unit, but was also commonly a militia or even a mob. The Nationalists ended up with a bit more than half of the army under their command, but these men did not make up the bulk of the fighters on either side. Most were completely inexperienced themselves.\n\nBasically anyone that could carry a rifle was shoved into the front lines. Inexperience was the rule, not the exception. In fact, at first many men were unwilling to take cover or dig trenches as it was seen as unmanly. Once the obvious folly of such practices was exposed to modern rifles such reluctance melted away. The fact that this was commonplace should tell you just how green such fighters were. \n\nAlso, the practice of getting rifles into the hands of combatants was often haphazard. It wasn't often the orderly distribution of identical rifles from a magazine. Instead, rifles of all makes and models were handed out, along with shotguns and pistols of all kinds. Just sorting the ammunition into usable groups was a novel and trying experience. Especially early in the conflict, arming your own side was extremely problematic. This isn't even to mention the new headaches of supplying the other logistics required of these newly created \"army units.\" (Water, food, medical services, transport, etc)\n\nSo, while it did take some time for foreign volunteers to arrive, and there was some of the standard harassment of the new arrivals, these artists and intellectuals (and thugs, and criminals) were only marginally less experienced than most of the other troops around them. And they, like the local fighters, learned at the front. Especially for the Republicans, they provided needed manpower in a bitterly contested war.",
"The International Brigades were incredibly helpful to the Republican forces. A lot of the Brigadiers were veterans of the First World War, and showed their determination and skill in the Siege of Madrid, where approximately 3,000 of them fought. Orwell describes that the presence of foreign volunteers made a positive impact on the morale of the Spanish militiamen, and they were admired in their relative skill. \n > They\nwere talking excitedly about their experiences and were full of\nenthusiasm for some French troops who had been next to them at Huesca.\nThe French were very brave, they said; adding enthusiastically: '_Más\nvalientes que nosotros_'--'Braver than we are!' Of course I demurred,\nwhereupon they explained that the French knew more of the art of\nwar--were more expert with bombs, machine-guns, and so forth. \n\nThe quite strong presence of journalists and intellectuals on the Republican side, such as Capa, Orwell and Hemingway, was also appreciated as many Republican Spanish believed that they could help their image overseas and rally more support for their cause. \n\nIn October 1938, the International Brigades were sent back to their home countries as a bid to ease the blockade maintained by the League of Nations Non-Intervention Committee so that they could receive some much needed aid. The bid failed, though, and the war was lost in early 1939, with the last few months offering little proper resistance since the bulk of the Army and air force was defeated at the Ebro. (Beevor, Antony. *The Battle for Spain*)\n\nAt the farewell parade we can also see what the Spanish thought of the International Brigadiers, with Dolores Ibarruri, La Pasionaria, making her famous *Farewell to the International Brigades* speech. \n\n > Today many are departing. Thousands remain, shrouded in Spanish earth, profoundly remembered by all Spaniards. Comrades of the International Brigades: Political reasons, reasons of state, the welfare of that very cause for which you offered your blood with boundless generosity, are sending you back, some to your own countries and others to forced exile. You can go proudly. You are history. You are legend. You are the heroic example of democracy's solidarity and universality in the face of the vile and accommodating spirit of those who interpret democratic principles with their eyes on hoards of wealth or corporate shares which they want to safeguard from all risk.\n\n(Full transcript available [here](_URL_0_))\n\nA bit of a tangent, but the International Brigades were also used by the Nationalists in their propaganda to portray the Republican forces as foreign invaders and strengthen the image that they were in defence of Spain and traditional Catholicism against the evil Bolshevik hordes trying to take their country."
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.english.illinois.edu/maps/scw/farewell.htm"
]
] |
|
1n17fc
|
Are there any millionaires alive today who's only source of wealth is inheritance from slave owners.
|
And I mean where the wealth was earned using slaves (plantations, slave trade, etc).
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1n17fc/are_there_any_millionaires_alive_today_whos_only/
|
{
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"ccekux4"
],
"score": [
5
],
"text": [
"You may be interested in the [Legacies of British Slavery](_URL_0_) project. When Britain emancipated its slaves, it paid compensation to the slaveowners. This project traces the families and institutions that benefited from that payout."
]
}
|
[] |
[] |
[
[
"http://lbsatucl.wordpress.com/"
]
] |
|
xvihd
|
Could you clone a woman by transplanting the nucleus from one of her normal cells into one of her own egg cells?
|
EDIT: Actually, I was curious because of mitochondrial DNA. There is genetic information contained in the cell mitochondria that isn't accounted for in the nucleus, isn't there? If that's true, wouldn't you need a cell with identical mitochondrial DNA in order to make a perfect clone? You could get that by using an egg cell from the target animal's mother, but if it were female you wouldn't need the mother at all.
If you cloned me incorrectly, for example, my clone might wind up free of male-pattern baldness.
|
askscience
|
http://www.reddit.com/r/askscience/comments/xvihd/could_you_clone_a_woman_by_transplanting_the/
|
{
"a_id": [
"c5pyrpd"
],
"score": [
3
],
"text": [
"Yes, it is definitely possible. This, in fact, is how most animal cloning is done. Except that the egg donor is usually a different animal from the nucleus donor. See [this description](_URL_0_) of the first successful cloning of a mammal."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Dolly_the_Sheep"
]
] |
|
3o261t
|
if drunk people are unable to consent, what happens when both parties are equally drunk and have sex?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3o261t/eli5if_drunk_people_are_unable_to_consent_what/
|
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"Usually yes. However, it is possible for people to give consent beforehand. For instance, an established couple might consume drugs and then have sex while under the effects. Because they have an established relationship, and previously consented, I think it would avoid the definition of rape.",
"It depends on the law in your area. Historically, rape was often defined as a forced action taken by a man against a women; it was legally impossible for a man to be raped. In modern law, rape is often defined by penetration; so it would depend on the acts involved. Even if you are 'blackout drunk', legally speaking you can still commit rape (in the same way that drunk driving doesn't absolve you from guilt of manslaughter); even rape each other, and both could go to jail for it.",
"Please note, not a laywer:\n\nDrunk people are capable of consenting. You can be sufficiently drunk that you're incapable of course (At the extreme end someone barely conscious is not able to consent for obvious reasons). Exactly how this breaks down will depend on jurisdiction and other \ncircumstance. The age difference of both parties, are both of them of legal age to be drinking, weather anyone of pressured into drinking or otherwise manipulated into getting drunker than intended (If you keep refilling someone's glass before it's emptied it can be easy for them to lose track of how much), whether at any point one of the parties objected to sex and so on will all be taken into account. \n\nAbsent any of those or other relevant details, then the likely opinion of the courts is that no crime occurred at all. Neither party carried any malicious intent. \n\nThat said if someone ends up in that situation, they should still get themselves a good defense attorney. Also while that might be the opinion the courts are likely to take, private disciplinary bodies may have different guidelines: Universities, workplaces, etc. \n\nETA: also some places (again universities etc) use incapacitation as their test which is often defined as: “an inability to make a rational, reasonable judgment or appreciate the consequences of your decisions”. In that situation the other person could be stark naked begging for sex, but it would still be considered rape if their status was known or knowable by the other person. Unfortunately most of these regulations are quite new and are very much works in progress and may have all sorts of potential for bad decisions when it comes to enforcement. \n\nETA2: Also true cases of mutual incapacitation are hilariously rare. They're basically unicorns. ",
"Are there any cases of this actually happening or is it just a hypothetical?",
"In the US Army, both parties get Article 15s (get in legal trouble). \n\nLegally speaking (most logically), by law, even two drunk people having sex consentually would mean that they raped eachother, and are both rapists."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
32wxcx
|
why were people like the nazi ss able to such horrible things without remorse?
|
I've been looking at the various massacres committed by the SS during WWII, and I really can't wrap my head around the idea of a group of people committing mass murder. In one of the massacres, they ate lunch outside the burning church with hundreds of bodies inside. (Sant'Anna di Stazzema massacre)
I just don't understand how a group of people could collectively agree with doing such a thing.
If I have any misconceptions about anything please let me know, I'm 17 and I plan on studying history in college.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/32wxcx/eli5_why_were_people_like_the_nazi_ss_able_to/
|
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"1. Some people are really fucked up\n2. They were following orders and only did it out of fear for their own lives ",
"Desperation leading to ingrained de-humanization of their enemies.\n\nPeople have, for the entirety of humanity, done things similar to what the SS had done. There have been massacres and slaughter and war since the dawn of man.",
"You have to understand a few things in the context of History. Even in the late 1930s most of Europe was still trying to recover from WWI which devastated millions of people and human life was not perceived as an especially precious commodity. In fact, casual murder runs all throughout human history, even in America (the 1800s was ripe with it).\n\nSo once human life is sufficiently devalued and you mix in a healthy dose of nationalistic and racist ideology, it was quite easy for German soldiers to dehumanize Jews, Gypsies, the elderly, children, homosexuals, the handicapped, etc.\n\nThere were certainly good Germans who found what they were doing repellent, but what was their option? Disobeying orders would lead them to the same trenches. What would *you* do?\n\nBTW - Don't let anyone crap on you for studying History. I feel it's the most valuable degree possible for understanding exactly how the world works and how everything happens in cycles. A proper understanding of History helps you put the present into its proper historical context.",
"They believed they were doing good. The Nazi propaganda depicted the Jews as evil and threat to society.",
"Through out history people have dehumanised their enemies. One of the best examples is the [Hartlepool Monkey] (_URL_0_). If people can be manipulated enough they will do almost anything. \nIn the example you cite there is also the macho factor. Remember most of the SS grew up in the Hitler Youth which ridiculed any sign of weakness. It's true there were many good Germans but by the time they realised what was happening, it was too dangerous to speak out.",
"If you plan to study history prepare to be horrified.\n\nThat stuff that the Nazis did was not really an exception but pretty much the rule for most of human history. What makes it stand out is that it happened on the end of a paradigm shift in human ethics that said such things were no longer okay and that it happened at a point where technology was advanced enough to allow people to commit atrocities on an industrial scale.\n\nYou will find similar and even worse stuff throughout human history. It may feel comforting telling oneself that it is not normal but mostly it was the sort of thing people did all the time and by pretending that it was more exceptional than it was you are setting yourself up to the danger of it being repeated.\n\nAfter WWII [Stanley Milgram](_URL_0_) did an experiment to figure out how people could have been brought to this and if there was something special about Germans. Like a good scientist he started out by doing the experiment first in the US so he would have a control with 'normal' people.\n\nHe then very quickly stopped because the results, as obvious as they are in hindsight were quite horrific for anyone who had previously believed that average normal humans did not just go and start torturing other people with little to no provocation.\n\nIt turns out humans are bastards and all that is keeping most of the people around you and most likely yourself from being like the people who ate lunch next to a burning church is a certain set of circumstances.\n\nOur only hope of preventing something like this from ever happening again is to always question ourselves and our motives and never fall into the trap of blindly believing that we are in the right.\n\nThere are many ways that one can end up in a situation that on would normally consider to be completely wrong. Most of the people who committed those massacres did not start out as psychopaths and sadistic serial killers (though there were some) most of them were normal people like you and me.\n\nOne important part of it was obedience to authority and peer pressure. It is easy to get caught up in those kind of things especially since they offer a convenient mechanism to let go of your own responsibility.\n\nYou just follow orders and don't question authority very much and do as everyone else around you does. the trick here is to start with something small and work yourself up. If you give people and order and they follow it once you have greater chance of being obeyed again. If they do a slightly sketchy thing just because they were told to, they will have a harder time saying no to the next order because saying no once would be admitting that they should have said no earlier. Once you killed a person because you were told to you either buy into the whole ideology fully or you have to admit to yourself that you were a murder. If it is gradual enough it is almost impossible to escape without some tremendous amount of self reflection, that few people are capable of.\n\nAnother aspect is the whole dehumanization of the victims thing, you deny them that they are human beings like yourself and it becomes much easier to justify to yourself what needs to be done.\n\nThe nazis started out by going after people that the vast majority of the population could agree had it coming and than gradually moved things up. Again admitting to yourself that things had gone to far would have meant admitting to yourself that you should have stood up for the first people they had come for and which you had despised.\n\nThe SS-comandos were the extreme and point to this development, they were so involved with death and murder and atrocities that in the end they could do things that even normal nazis who carried their own share of guilt would have reacted with horror to.\n\nIt is easy to put these people down as monsters and not really human, but that is about the worst thing you could do for two reasons.\n\n1. Dehumanizing people is the thing that got us into that sort of trouble in the first place.\n2. Many of them started out as not-monsters, but as mostly normal people. If you don't admit to yourself that they are human like yourself you have far less chances of avoiding the traps they fell into when they might ever come for yourself.\n\nIt is easy to divide the world in good and evil and tell yourself that they are obviously evil and you are obviously good, but it helps to keep in mind that they probably thought similarly of themselves too.\n\nIt is hard to wrap you head around it but humans have a great capacity for 'evil' and by the time it becomes as obvious as your example it is usually to late to stop. You have to constantly check yourself to avoid becoming like them. \n",
"A lot of people are trying to say \"They had no choice\". That's not entirely true. Well it might be for some people... with Nazis it's kind of like the empty rifle in the firing squad, an easy out, but it's not the whole story.\n\nWatch the movie *Compliance*. When you're done look up the case it's based on. Look up the Stanford prison experiment. Look up the Milford experiments.\n\nYou don't have to be desperate to be horrible to another human being. You just have to be told by someone, in a position of authority, that you have to do it.",
" > group of people committing mass murder. In one of the massacres, they ate lunch outside the burning church with hundreds of bodies inside.\n\nYeah you get that from every army, including the good ol' USA. \n\nEnd of the day is if you don't see your victims as being humans, then it's easy to kill them off like cattle. ",
"There is a recent book titled Ostland by David Thomas that you might like to read. It's a fictional novel, but based on actual events, about a respected German police detective who later took part in horrific war crimes on the Russian front. It does a pretty interesting job of following his thought process as he sinks deeper into the quagmire. He knew what he was doing was terrible, but also knew that disobeying would get him killed or sent to the front, where he would die. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[
"https://www.youtube.com/watch?v=K1b8AhIsSYQ&list=PLK9Sc5q_4K6aNajVLKtkaAB1JGmKyccf2&index=197"
],
[
"http://en.wikipedia.org/wiki/Milgram_experiment"
],
[],
[],
[]
] |
|
tj7ik
|
Can Anyone Point to a Time in History When Trickle Down Economics Worked?
|
I'm curious. Republicans are pushing the idea that if you give tax breaks and subsidies to business rather than focusing on social welfare, the money will trickle down from the rich and help the poor. There are time periods in which this has been done, but I can't seem to find how it worked out for us.
I'm unbiased really, I just need to know where I stand on it, and I think historical information is the best way to find out.
This is one of Romney's favorite things to push and he wants to impose it. Obama is opposed to it and would rather do it with welfare.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/tj7ik/can_anyone_point_to_a_time_in_history_when/
|
{
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"text": [
"Define worked. In terms of raw economic growth? Do you consider that mitigated by other factors, and if so, by what? Are you pursuing numerical aggregate as the indicator of good function? Or a more Sen-esque approach?",
"The gilded age was define by hands off, laissez faire economic policy and in terms of raw economic growth, it seemed to have worked pretty damn well. Obviously the workers were struggling but the economy as a whole grew tremendously.",
"Despite the protestations its pretty clear you're not looking for an answer just pushing a political view point. /politics or /economics are more appropriate subreddits. ",
"Can anyone point to a time in history when Keynesian economics worked? Or any kind of economics? \n\nWhat does it mean for something to work? Work, relative to what? Does freedom and liberalism create economic growth? It seems quite clear that over the last three hundred years that it has. \n\nBut there are a lot of epistemological problems with your loaded question. First of, it is difficult if not impossible to ever verify empirically whether an economic policy was effective. I remember that there was a lot of talk in 2008 that we would have a stimulus, and the results would prove once and for all whether Keynes was right. Well, the stimulus happened, but nobody could really tell empirically whether we would have been better off with or without it. \n\nWhen you ask whether something \"works\" you are presenting an implicit assumption that we can somehow test economic policies against each other. But economics is not a hard science; it has a different kind of methodology and different kinds of laws. It is a priori, logical, and deductive. There are many more variables in economic performance than only the set of policy recommendations from a government's economic advisor. \n\nIn short, your question cannot be answered by historical investigation, since historical research is empirical. You say that it is an unbiased question, but I question whether you fail to recognize your own bias.\n\nData never speaks for itself. Data must be interpreted through theory. \n\ntl;dr History cannot prove economic theory, it can only provide illustrations for the logic of theories. \n\nEdit: Downvotes, really? Someone doesn't like epistemology?",
"Your question doesn't really make sense...or the entire premise. \n\nTricke-down economics has an *effect*, but does it work as a surrogate for social insurance/services/welfare?\n\nNo.\n\nIt's like saying \"does driving safely work instead of buying car insurance?\"\n\nNo, because you can't control if someone plows into you at a red light. I know, because someone did that to me at 50 mph. All the car insurance in the world didn't matter because it didn't stop me from having an accident.\n\nLook, these aren't mutually exclusive ideas. You can have trickle-down economics with or without a social safety net. What you should ask is if Romney's premise makes sense, which it does not. It only provides an answer for prosperity, not insurance and emergencies.\n\nI segregate capitalism and trickle-down economics from social services. Purely as a means to run an economy, these things do produce results. You cannot control things like graft, greed and cheating without regulation. So that is the question you need to be asking: what level of regulation is enough keep capitalism working optimally without becoming onerous? Or another question \"Why are we talking about pure, philosophical capitalism and trickle-down economics when they are just a theory that is only applicable in /r/libertarian and not real life?\"\n\nThe other is the merit of Obama's social services plan. Do you want the federal government to run it? How about they mandate it, but the state runs it? Or they mandate it, but we do it privately? Or perhaps there's no federal mandate, but a state mandate and we have non-profit collectives?\n\nThere are so many choices, and what's sad is their solutions are not even answers to the question."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
5ij57u
|
if the energy is consumed at the time it is produced how come there is always electricity at the electrical outlets ?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5ij57u/eli5if_the_energy_is_consumed_at_the_time_it_is/
|
{
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"Because it is produced in anticipation of you using it. And with a million people using it at the same time, you turning on your blender is balanced out by someone else turning off their blow dryer.\n\nAlso, there is enough \"slack\" in the system that what one or two households so isn't going change how much total power needed to be used.",
"The outlet is not using power until something is plugged in. When you plug something in, it does actually pull the voltage of the entire grid down. It's just that most consumer products are such a minor quantity of power that the change is pretty unnoticeable to the grid. You will see this though with a large air compressor (the lights in your house will dim). \n\nEventually it will propogate all the way through the grid to the turbine generating the power. Since the turbine is simply converting mechanical energy to electrical energy, the grid will take more mechanical energy from the turbine. This is a fancy way of saying it slows the turbine down. Those managing the power grid can assure proper power generation by maintaining the proper speed on those turbines. ",
"Think of electricity like water flowing through pipes. Everything you plug in is like a drain valve. Open a valve (turn something on) and that allows water to flow, close a valve (shut it off) and the flow stops.\n\n\n\nPower plants are like pumps, they never stop and when water isn't flowing they just sit there churning. No water is pushed into the pipes until you open a drain valve."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
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