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22vgew
|
How does Surface plasmon resonance (SPR) work?
|
I was reading [this _URL_1_ article](http://_URL_1_/news/2014-04-ersb-nanostructures-applications-infrared-terahertz.html) and it sent me on a long wikipedia walk reading about surface plasmons and related materials.
Then, after some googling, I found [this video](_URL_0_). In the video, it is mentioned that reactions that take place on the ligands result in a shift in the dark spot on the detector.
The narrator says that the resonance at the surface is very sensitive to environmental changes, but I don't fully follow. How and why does binding to the ligand cause this shift in angle? How is it connected to to the plasmonic resonance at the material's surface?
EDIT: I realize that my question is more about the application of SPR in biochemistry than actually what the phenomena is.
|
askscience
|
http://www.reddit.com/r/askscience/comments/22vgew/how_does_surface_plasmon_resonance_spr_work/
|
{
"a_id": [
"cgrvlgt"
],
"score": [
3
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"text": [
"In SPR you're hitting the underside of a thin piece of metal with light and measuring the light that is reflected back. Do this at a bunch of different angles and you get an SPR curve. When you modify the other side of the sensor, through say, binding an enzyme to it, you affect how the light resonants through the sensor which changes the curve. This is similar to how color indicators from acid-base titration a change color because their chemical formula has changed, just on a grander scale. "
]
}
|
[] |
[
"https://www.youtube.com/watch?v=sM-VI3alvAI",
"phys.org",
"http://phys.org/news/2014-04-ersb-nanostructures-applications-infrared-terahertz.html"
] |
[
[]
] |
|
2gov9b
|
no. 2 pencils
|
Whats so special about them? Why are No. 2 pencils only allowed on tests?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2gov9b/eli5_no_2_pencils/
|
{
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"ckl4via",
"ckl70gn",
"cklaekn"
],
"score": [
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3
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"text": [
"The various grades of pencil lead denote hardness. Harder pencils make a lighter mark; softer ones make a darker mark, but tend to smudge very easily. No.2 (aka HB) lead tends to make a nice dark mark and not smudge too badly. The scanner that are used to grade bubble tests are calibrated to read those marks.",
"You can take tests with other pencils, it's just more likely that the grading machine may not pick up the mark/the mark will smudge into other bubbles. ",
"No. 2, while the \"standard\" for writing pencils, is not actually standardized except on a per-manufacturer basis. So a No. 2 Palomino will be quite dark and soft compared to a No. 2 Staedtler Norica.\n\nI have heard of some test monitors refusing HB pencils, even though that's the equivalent of a No. 2, so you may want to be careful of that too. Just for further interest, the \"HB\" measure is \"Hard, Black\"; darker, softer grades are multiples of B, so 2B, 3B, etc., up to as high as 9B. For H it works the same. A few makers have an \"F\" rating between HB and H, for \"firm\"."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
2u8nzk
|
why is it okay to kill animals, but wrong to have sex with them?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2u8nzk/eli5_why_is_it_okay_to_kill_animals_but_wrong_to/
|
{
"a_id": [
"co65acb"
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"score": [
2
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"text": [
"Personally I'd rather die then get raped by animals. In some places if you are caught doing it the punishment is death. I think it's because its fucked up and inhumane. Killing animals is also bad and frowned upon but we do it anyway for resources. "
]
}
|
[] |
[] |
[
[]
] |
||
28qm87
|
how is german the closest language to english?
|
When looking or hearing German, it doesn't seem anything like English at all. I know a bit of Spanish, and there are many cognates and similarities to English across the entire language. I don't actually know any German, but German seems to be much further away than Spanish in this regard. How is it then that they are in the same family (both being Germanic languages), while Spanish is in an entirely different family?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/28qm87/eli5_how_is_german_the_closest_language_to_english/
|
{
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"cidgw8t",
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"cidl9kc"
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"score": [
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"text": [
"Try [Scots](_URL_1_) then [Fresian](_URL_0_) as the closest languages to English.",
"Like Antimutt said, there are languages that are closer to English than German.\n\nBut German and English have a common ancestor language, in the same way Spanish and French do. Prior to about 1500 years ago, the groups that went on to speak English and the groups that went on to speak German were speaking the same language.\n\nEnglish looks very different, though, mostly due to some really rapid change that happened while the Norman French were ruling England. The structure of the language changed, and we picked up a lot of words from them (which is why there are a lot of cognates with Spanish), and also separately from Latin over the centuries, since for a long time it was a language that most educated people knew.",
"**Answer:** English isn't \"the closest\" language to modern German in terms of how it sounds or reads. Rather, both are [\"Germanic\" languages](_URL_0_), meaning that, to make a biology analogy, they share a sort of \"common ancestor.\" \n \n**Analogy:** Think about the Romance Languages as fish, Modern German as a bear, and English as a leopard seal. Sure, leopard seals have \"fins\"---and a \"tail\" instead of legs---and they live in the sea. But leopard seals are still mammals, and more closely related to bears than to fish. \n \n**Explanation:** For historical reasons I don't understand well, English takes a lot of words from Greek and Latin as compared to actual German, which is partly why there are so many cognates with the Romance languages. Unlike with biological evolution, it is easier for languages to incorporate features of other less closely \"related\" languages---like words and sentence structure---which explains some of the other similarities. \n\n",
"Language 'families' are similar to real families in that you can have closer and more distant relatives. You say that Spanish and German are in different families. That is true in one sense, but in another they are part of the same family, that of Indo-European (along with almost every European language). So that's the first thing.\n\nIf you knew a bit more German, you'd find lots of similarities between German and English. There are too many to give an exhaustive list, but one example might be the word 'king', which has much more to do with the German word 'koenig' than the Latin root 'rex' (which is where you get the French 'roi' and Spanish 'rey'). The English word 'flesh' has more to do with the German word for meat (Fleisch) than the Latin 'caro', which is where you get the Spanish 'carne'.\n\nFinally, English derives heavily from German because it was a load of German tribes (Angles, Saxons and Jutes) that come to Britain after the Romans left, bringing their language with them (hence: Anglo-Saxon). That said, this was the first of many mass migrations to the island, each of which brings its own language. When the Normans invaded in 1066, English was injected with a load of French. With the British Empire in the early modern period (and beyond), English started picking up languages from the Indian subcontinent, the Caribbean, and the South Pacific (among other places). Call English a 'Germanic' language doesn't tell the whole story.\n\nTL;DR:\n1. All European languages are part of the same family.\n2. German and English have many, many similarities.\n3. English is more than just a 'Germanic' language.",
" > How is it then that they are in the same family (both being Germanic languages), while Spanish is in an entirely different family?\n\nAll three languages you mentioned (English, German and Spanish) are in the same family of languages. This family is called the \"Indo-European\" language family. \n\nOld English and Old German were much more similar to each other than Modern English and Modern German are. In the little more 1000 years, both languages have developed differently. \n\nEnglish developed on an island and after the Norman French conquest of 1066, English absorbed much vocabulary from the Norman French language. By the time Middle English appears (about 700 years ago), it is very different from Old English. \n\nIn Germany, the many hundreds of different German dialects continue to develop as there was no standard German language since Germany did not become one country until 1871. Likewise, German never had a strong Latin language influence, which English had. \n\nBy modern times, we have English (the most Romanised Germanic language) and a standard version of German. Of all the Germanic languages, German, Dutch and Afrikaans are somewhat similar, Swedish, Norwegian, Danish are quite similar, Icelandic and the Faroe Islands language are old versions of Norwegian and Frisian is somewhat close to the Scandinavian languages while being close to Dutch. \n\nWe could put English with the Scandinavian languages, since much English grammar is still similar to Scandinavian grammar.",
"Languages being related does not suggest any mutual intelligibility. Look at Finnish and Hungarian for another good example.\n\nBy the way, German is not English's closest relative. Languages said to be more similar are Scots, Frisian, and Dutch.",
"It actually is extremely similar. Some words are even exactly the same, or sound the same. \n\nFor example, hand is \"hand\" foot is \"fuss\" angel is \"engel\" morning is \"morgen\" also for family members, you have the mutter, the sohn, the vater and the schwester making up the familie, can you take a guess how those translate to English? ",
"german isnt. frisian is.",
"English and German have really similar words and they share the same ancestor.\n\nSpanish isn't closer to English than German."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Frisian_languages",
"https://en.wikipedia.org/wiki/Scots_language"
],
[],
[
"http://en.wikipedia.org/wiki/Germanic_languages"
],
[],
[],
[],
[],
[],
[]
] |
|
7nmz5o
|
Did the Pope ever go to war?
|
To my limited knowledge of Catholicism, the Pope has been apart of the Roman Empire, Western Roman Empire, (the Aryan Christian "Ostrogoths" maybe?), Justinian's brief newly united Roman Empire, the Papal States, France briefly, and a mixture of different Italians States leading up to Italian unification and then later Mussolini gives the Pope and Cardinals the Vatican and a little land to call theirs.
So in all of this time and exchanging of Rome between different countries, did the pope ever go to war? Be it in defending Rome (or Avignon) from invaders or going off with his own Papal army on crusades?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/7nmz5o/did_the_pope_ever_go_to_war/
|
{
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"ds45ynr"
],
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"text": [
"Some Popes certainly did lead armies.\n\nPope Leo IX led an army against Norman invaders, and was defeated at the Battle of Civitate in June 1053 and held hostage for about 9 months.\n\nPope John XXII openly supported Bologna and the Guelphs against Modena and the Ghibellines, offering indulgences to anyone who would war against Mantuan Passerino Bonacolsi (the leader of Bologna). I don't know if he actually led the army, but his actions did help precipitate the hilariously-named War of the Bucket.\n\nPope Julius II was given the epithet \"warrior pope\" due to his participation in--and starting of--multiple wars. He personally led his army on campaign in 1506 and 1510, at least.\n\nJulius II also sent his papal army under the command of his legate, Giovanni di Lorenzo de' Medici (of THE Medicis) against the French. They lost and Giovanni Medici was captured. Giovanni would later be elected Pope Leo X.\n"
]
}
|
[] |
[] |
[
[]
] |
|
53twzx
|
At the time of James I (VI) was Scottish already anglicized or was it still distinctly Scottish?
|
So was something akin to Scottish Gaelic still spoken in Scotland by commoners or nobles or did they speak Scottish in today's terms of English with a thick accent?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/53twzx/at_the_time_of_james_i_vi_was_scottish_already/
|
{
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"d7wpv4g"
],
"score": [
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"text": [
"First, some clarification about languages. At the time of James I and VI, i.e. late 16th and early 17th centuries, we are talking about three distinct languages:\n\n1) Gaelic - i.e. 'Scottish' Gaelic, a Celtic language. (Gàidhlig)\n\n2) Scots - a germanic language related to English. In this period we would refer to it as 'Middle Scots'. (It's still contentious whether to call Scots a language or a dialect; I'm on the language side of that debate).\n\n3) English - English 'as we know it', or at least as they knew it in the period, i.e. 'Modern English', not 'Middle English'. (English as it is spoken today in Scotland should be referred to as 'Scottish English', which distinguishes it regionally from other Englishes, but avoids confusion with the separate language 'Scots')\n\nBack to the question. It's a little contentious how far Gaelic spread in Scotland, with some people arguing that it never was widespread in the Lowlands at all. However, what's not really up for debate is that the Gaelic heartland was the Highlands and Western Isles, and the dominance of Gaelic was much lower in the Lowlands. \n\nIn terms of the period of your question, Gaelic had ceased to be used in the Lowlands in the second half of the 14th century, and was all but replaced by Scots as the language of common usage, and in government and law. James IV of Scotland was the last monarch to learn Gaelic. At this time, English language terms for Gaelic and Scots began to change. Gaelic, instead of being called 'Scottis' started to get called 'Erse' (= Irish), essentially *foreignising* it, and 'Inglis' (=Scots) began to be called 'Scots' (thus identifying it with Scottish identity, which would eventually form part of a English narrative of portraying Scots as rural and uneducated).\n\nThe personal union of crowns, and the growing ties to England among the Scottish nobility and elites, coupled with the influence of the reformation and the advent of printing, all increased Anglicisation of Scots, and the growth of Scottish English from the mid-to-late 16th century onwards."
]
}
|
[] |
[] |
[
[]
] |
|
339srr
|
Why was calculus developed? What was the motivation?
|
askscience
|
http://www.reddit.com/r/askscience/comments/339srr/why_was_calculus_developed_what_was_the_motivation/
|
{
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"text": [
"This is not a short question to answer. For a general history of Calculus take a look at Boyer's [A History of Calculus](_URL_3_).\n\nAnyways, as a brief overview, Calculus did not get created in a couple of years by Newton and Leibniz scribbling in their offices. The fundamental techniques and concepts can be traced back to the Greeks, at least. [Zeno's Paradox](_URL_2_) is an attempt at the ideas of Calculus. [Archimedes approximated Pi to very high degree](_URL_7_) using ideas from Calculus, and similarly [the area enclosed by a parabola](_URL_8_). Concepts like differentiation and continuity were popping up at the beginning of the Renaissance, in association to motion and velocity. [Fermat found the relationship between derivatives and maxima/minima](_URL_0_) years before Newton was born!\n\nAll of the tools, applications and methods were around by the time of Newton and Leibniz. But nothing was standardized, many of the theorems were only proved for a restricted class of functions, much too small for more general applications and, more importantly, they were missing the most important thing in Calculus: [The Fundamental Theorem of Calculus](_URL_10_). To discover the Fundamental Theorem of Calculus, you need to be able to see the Big Idea of all these concepts that were just floating around at the time and you needed a drive to push you to connect all the dots. For Newton, he needed powerful tools to work with his equations for Gravity and Motion. The ideas of (what we call today) integration and differentiation would be helpful to him, but he needed a little more to get everything he needed. Leibniz was much more sophisticated in his ideology, and was motivated by pure philosophy to study the ideas of infinitesimals. He was more driven by the need to connect the dots for their own sake. But they both had the right ideas floating around, the right conditions to think about them and the right drive to push them just a little further than everyone else. Pretty much simultaneously, they both discovered the connection between the Integral and the Derivative ideas that is the Fundamental Theorem of Calculus. This is a huge step, which is why we generally attribute the invention of Calculus to them. But they were, by far, not the first to think of these concepts.\n\nOf course, in the centuries after they died, the standard for a mathematical definition and proof rose. By the time the 1800s came along, the work of Newton and Leibniz was full of hand-waving where there should be proofs. This is where the likes of [Cauchy](_URL_9_) and [Riemann](_URL_4_) come into play. They were the ones who solidified the idea of Limits as the backbone of everything in Calculus. Up till then, the ideas of Leibniz and Newton were both separately supporting Calculus but they had fundamentally different philosophies, even if the consequences were the same. Leibniz worked with infinitesimal numbers, which made later mathematicians very uneasy. To fix this, the mathematicians of the 1800s abandoned Leibniz's philosophy and proved and used limits to expanded the concepts of Calculus into what we call [Real Analysis](_URL_5_) and [Complex Analysis](_URL_1_). At this point we pick up sophisticated integration techniques like Riemann Integrals and Lebesgue Integrals, as well as Fourier Analysis and other methods from Complex Analysis.\n\nLeibniz, however, was redeemed with the 20th Century invention of [Nonstandard Analysis](_URL_6_) in which Leibniz's infinitesimals ideas are taken seriously. Even though it is philosophically more pleasing, this has not really gained traction in the mathematical community because it doesn't prove anything extra, it's very different from what most everyone is used to and computation does not come easily."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Fermat%27s_theorem_%28stationary_points%29",
"http://en.wikipedia.org/wiki/Complex_analysis",
"http://en.wikipedia.org/wiki/Zeno%27s_paradoxes",
"http://www.amazon.com/History-Calculus-Conceptual-Development-Mathematics/dp/0486605094",
"http://en.wikipedia.org/wiki/Bernhard_Riemann",
"http://en.wikipedia.org/wiki/Real_analysis",
"http://en.wikipedia.org/wiki/Non-standard_analysis",
"http://en.wikipedia.org/wiki/Pi#Polygon_approximation_era",
"http://en.wikipedia.org/wiki/The_Quadrature_of_the_Parabola",
"http://en.wikipedia.org/wiki/Augustin-Louis_Cauchy",
"http://en.wikipedia.org/wiki/Fundamental_theorem_of_calculus"
]
] |
||
3wu4ce
|
Why does a dead star collapse under its own gravity?
|
How do the fusion reactions prevent this from happening before the star runs out of fuel? And please also explain how this implosion results in the release of gravitational potential energy. Sorry for asking a lot.
|
askscience
|
https://www.reddit.com/r/askscience/comments/3wu4ce/why_does_a_dead_star_collapse_under_its_own/
|
{
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"cxzzimj"
],
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"text": [
"So I think the better question is why don't objects collapse immediately. If pure gravity was all that was in play you'd expect them to collapse with no impediment.\n\nThe reason nuclear fusion stops the collapse for stars is that it produces a pressure gradient in the star and this counteracts the gravitational collapse. This situation is called [hydrostatic equilibrium](_URL_1_).\n\nOnce it can no longer fuse quickly enough it start to collapse, depending on how many times this has happened (and details of the star) this can lead to different fusion processes which then stop the star from collapsing. \n\nThe other option is that nuclear fusion can no longer support the star at all and then there are 3 basic options. \n\n1) For relatively light stars ~1 solar mass (and [not much more](_URL_3_)) an [electron degeneracy pressure](_URL_2_) can hold the star up.\n\n2) Above the [limit mentioned above](_URL_3_) protons will capture the electrons and you end up with a neutron star. These objects also have a [mass limit](_URL_4_).\n\n3) Nothing can halt collapse and we get a black hole (unless there is some exotic things like [quark stars](_URL_0_) in between)"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Quark_star",
"https://en.wikipedia.org/wiki/Hydrostatic_equilibrium",
"https://en.wikipedia.org/wiki/Electron_degeneracy_pressure",
"https://en.wikipedia.org/wiki/Chandrasekhar_limit",
"https://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit"
]
] |
|
c11jog
|
how and why does the time of the day affect our emotions?
|
Like we tend to feel negative emotions strongly at night while during the day we tend to have a more optimistic outlook.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/c11jog/eli5_how_and_why_does_the_time_of_the_day_affect/
|
{
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"text": [
"At night, you're tired and ready to call it a day. You let your guard down which opens you up to those kinds of thoughts and feelings. You aren't required to be alert in bed like you are during the day at work or school.",
"Because your your circadian clock effects hormones and other chemicals in your body. get these chemicals out of wack, and it can effect anything from mood to health.",
"A lot of it revolves around the sun. The sun releases hormones in your brain including serotonin, a hormone that regulates mood. It's why you feel crappy on overcast/winter days.",
"There's a hormone your body produces called cortisol. This does a LOT of things, but importantly, when there's plenty of it, it makes you feel like you're more energetic, which often corresponds with mood. Your cortisol levels change throughout the day, with their highest levels in the late morning & their lowest levels at midnight/in the early hours of the morning. This is also very noticeable in people with depression: they often feel significantly worse in the mornings. This won't be the only reason that the time of day affects one's emotions, but it probably is one."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
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|
1pwdu6
|
when i boot up my computer or console, it makes a "beep" sound. but it's not coming from the speakers. what does that sound?
|
There definetly isn't a speaker inside of my computer. I wondered this since forever.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1pwdu6/eli5_when_i_boot_up_my_computer_or_console_it/
|
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"text": [
"There usually IS a very small single speaker inside the computer. It is usually no wider than an American dime, with one plug that goes directly into the motherboard. It beeps probably to test itself and make sure it works. The mini speaker itself is used to beep error codes, in case your computer malfunctions.",
"That comes from the so called POST or \"power on self-test\".\n\nIf your machine passes the POST or POSTs as most people call it, it will give of one long beep. \n\nHowever if your computer fails that POST it will give of some other series of long and short beeps. If you write down the sequence of beeps you can then look up what that means in terms of your mother board.\n\nThis is designed to help debug problems where the computer will not boot up even enough to run any further tests.",
" > There definetly isn't a speaker inside of my computer.\n\nYes there is. It looks something like [this](_URL_0_).",
"Thank you for the answers! Also nice stories!",
"There is a little speaker in there. It used to be a real 2\" paper cone speaker, and used to be uses for basic game audio, since it is driven from a simple sound generator, that can be run at the BIOS level by simple code. A sound card usually cannot be accessed that early.\n\nSince the popularity of sound cards, it has become relegated to an error indicator with a disc diaphragm, to give that one beep to let you know BIOS is working. or a beep pattern if something is wrong.\n",
"There is a speaker inside your computer, it's called the PC Speaker. Computers have had this for 35 years at least. \n\nIn the days before computers typically had sound cards, the PC Speaker would produce all the sound and music for games. Obviously the sound quality left a lot to be desired.\n\nYou should be able to find it, by listening, it will be connected to your motherboard by a small 4-prong plug that has 2 wires going into it (usually red and black).\n",
"Finally a question I could answer fully and completely and I arrive to late. Oh well. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.newegg.com/Product/Product.aspx?Item=N82E16812201032"
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|
10eb9n
|
- baseball standings
|
How can you be half a game behind the leader? What is a wildcard spot, and why is it seemingly so coveted? Most other sports are pretty straightforward, but baseball standings are full of all sorts of weird little things that make it a mystery to me.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/10eb9n/eli5_baseball_standings/
|
{
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"text": [
"First off, there's 2 leagues (National and American) each with 3 divisions. To make it to the playoffs, a team must either win its division or win one of two (per league) wildcard spots. \n\nThe wildcard spots are reserved for teams that don't win their division, but are the best of the remaining teams in the league. The reason why you hear so much about them is because there are many more teams competing for only 2 spots. In a division there are usually 2 or 3 teams that are in contention to actually win the division. So out of 2-3 teams with good records only 1 team will get the automatic playoff berth by winning the division, and the rest of the teams from all 3 divisions are thrown together in the wildcard, making it quite an interesting race. It's not \"coveted\" per say, but it is often more interesting to keep track of because the division winners are often decided a while before the playoffs actually start.\n\nHalf-games in the standings come from teams that haven't played the same number of games. For example: Two teams both with a record of 0-0 play each other. Team 1 wins and Team 2 loses. Team 1 is of course 1 game ahead in the standings. \n\n Games Behind\n Team 1 - 1-0 -\n Team 2 - 0-1 1\n\nLet's look at Team 2's Games Behind. A good way to think about it is that 1 less win OR 1 more loss puts you .5 games further behind. In this case there's one of each category, so 2*.5=1\n\nTeam 1 then plays Team 3, with Team 3 winning. Team 2 doesn't play at the same time. Current standings:\n\n Games Behind\n Team 3 - 1-0 -\n Team 1 - 1-1 .5\n Team 2 - 0-1 1\n\nTeam 1 and Team 3 each have 1 win, but Team 1 has 1 more loss, putting them .5 games back. Team 2 has 1 less win and 1 more loss, putting them 1 full game back.\n\nHope that made a little sense "
]
}
|
[] |
[] |
[
[]
] |
|
c72jc1
|
why do cinema screens look so clear if pixels stretch with bigger screens?
|
If you stretched a 4K TV to the same size as your average IMAX meaning more than 10x it's current width, wouldn't it look extremely pixelated? Is it because of the distance being much further away for a cinema viewing experience?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/c72jc1/eli5_why_do_cinema_screens_look_so_clear_if/
|
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"How pixellated a screen looks is based on how big each pixel looks to you. If each pixel takes up one millionth of your full field of vision, then it doesn't matter how big that pixel actually is. If you took an old and really low pixel count screen, and set it a hundred feet away, it would look just as pixellated as a really nice 4k screen ten feet away. The size of a pixel scales with your distance. If you're twice as far away, the pixel is one half the size.",
"If the projector is digital, then it's using a resolution that is set based on the distance between the projector and the screen so that the image is clear.\n\nIf it's a film projector, film doesn't have a resolution, so it shouldn't look blurry anyway."
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2blamn
|
Any examples of predators overexploiting their prey population, leading to the extinction of both?
|
Just trying to settle a bet. I'm aware that predator-prey dynamics normally involve oscillation in the sizes of each population. I've read in a couple of places that overpredation can lead to the extinction of the prey population, which can then cause the predator population to go extinct. I can't find any examples! Are there any relatively modern ones? Ones from the fossil record?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2blamn/any_examples_of_predators_overexploiting_their/
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"After briefly looking around I came across [the cascade effect](_URL_0_), which sounds like what you're looking for.\n\n > An ecological cascade effect is a series of secondary extinctions that is triggered by the primary extinction of a key species in an ecosystem.\n\nI don't know if we've specifically documented it happening for an entire species, but if all the members of a species were in an ecosystem that experienced one of these, that would qualify.",
"I am writing this from my phone, so I apologise for any mistakes that I have made, and perhaps a lack of detail or completion to my thoughts.\n\nBelieve it or not, there is absolutely no known example of a species causing its own extinction. \n\nSpecies (as far as we know) can only become extinct due to an environmental change causing their likelyhood of survival to decrease. In modern species, a predator will never deplete its food source completely. If a population of prey begins to deplete, the predator population will deplete at a much faster rate this is due to the exchange of energy within the system being fairly inefficient. As the predators population decreases, the prey's population will be able to increase resulting in a pattern where neither species ever dies out completely. \n\nHowever, it is incredibly difficult -at this time- for us to determine why some of the much older species became extinct, so it would not be correct to assume that they followed the patterns that we see today.",
"I remember reading about this during my university days:\n\nLocation: St. Matthews Island\n\n\nBack story: \n\nIn 1944, 29 reindeer were introduced to the island by the United States Coast Guard to provide an emergency food source. The coast guard abandoned the island a few years later, leaving the reindeer. Subsequently, the reindeer population rose to about 6,000 by 1963[5] and then died off in the next two years to 42 animals.[6] A scientific study attributed the population crash to the limited food supply in interaction with climatic factors (the winter of 1963–64 was exceptionally severe in the region).[1] By the 1980s, the reindeer population had completely died out.[2] Environmentalists see this as an issue of overpopulation. For example, Garrett Hardin cited the \"natural experiment\" of St. Matthew Island of the reindeer population explosion and collapse as a paradigmatic example of the consequences of overpopulation in his essay An Ecolate View of the Human Predicament.[7]\n\n\nSource: _URL_0_",
"The issue is, how would we know if it happened? Two coincidental extinctions could easily have been related, but without direct observation of the ecological interactions between both it's impossible to know for sure. That pretty much rules out any pre-historic or poorly studied systems, leaving us with the dearth of modern examples referenced by others. While it is theoretically possible (and geological history is a long time after all, so even unlikely events have likely occurred at least once), I'm unaware of any documented case. Best I've got is this article ( _URL_0_ ) which focuses on host-parasite interactions but does a decent job introducing the difficulties inherent to the scientific study of extinction in the ecological context. \n\nEdit: let's add a link that actually works...",
"If you are strictly talking about animals, I can't seem to find much of anything. I would imagine that the Maori, which hunted the Moa (_URL_0_) to extinction, led to the abandonment of some areas by the Maori, but that really isn't \"extinction\"\n\nIf you are talking about any type of species, I would then use the example of the inhabitants of Easter Island which once had a population of around 15k but is all but extinct from over-harvesting/hunting all species of plant and animal life on the island (_URL_1_).\n\n",
"i'm not 100% sure but I think there's a piece about this in A Short History of Nearly Everything by Bill Bryson. (Bit of a weird source I know).\n\nHe effectively says that over-predation causes the predator to die off massively but hasn't been observed to wipe out both species. I'll try and find the actual source but it basically works something like this:\n\n_URL_0_",
"this is one of the ethical reasons for hunting. It helps cull an animal population that would eventually eat itself into starvation and eventual extinction(from that region). \n\nas far as the question, I can't think of any. Trying to think of a predator who would biologically need to eat so much of its prey that both eventually became extinct. It is my understanding that animals in the wild only do things because their instincts tell them too. with that in mind I would assume an animal would stop eating once it was no longer hungry. And if a predator killed off its prey I would by overeating I would assume an animal would move on to another prey before it would die off. ",
" > I'm aware that predator-prey dynamics normally involve oscillation in the sizes of each population\n\nThis actually isn't quite true! \n\nThe Lotka-Volterra Predator-Prey models do indeed predict such oscillations, but in practice they're very rare. As far as I know just about the only undisputed examples involve microtine rodents living at high latitudes, and their predators. The models that predict these oscillations are useful but also highly simplified. ",
"Moa in New Zealand?\n\nI know it's also because of the slash and burn technique for getting land, but there is a lot of New Zealand that wasn't slashed and burnt. The Moa does seem to be a species that was killed off. Correct me if I'm wrong.\n\nInadvertently the Haast eagle.",
"The only exemple i know of is a man made. \n\nIn the 19th century, a ship left a few rabbits on a really tiny island in the pacific. When the ship returned the next year. The plants were gone and there was no sign of the rabbits. Most likely that without predators, they just ate all the plants and died of. ",
"The only way a predator-prey relationship becomes extant long enough for us to observe it is if they get the equilibrium stuff down-pat. So yeah, while it's more than possible to have them out of sync, the ones that do are gone in a geological heartbeat. ",
"I am going to give you the most amusing example of which I know, but it really doesn't fit the bounds of your question.\n\nBed bugs breed through [traumatic insemination](_URL_0_). Literally, the male pierced the abdomen of the female with its penis and injects the semen.\n\nOnce a bed bug colony become large enough, the male population will traumatically inseminate the entire female population to death, eventually wiping out the colony. ",
"While not entirely influenced by prey loss the longest running predator prey study I am aware of might be interesting to you. It's the moose/wolf study at Isle Royale National park. \n\n_URL_0_\n\nCurrently the wolf population is in decline and in danger in large part now due to lack of genetic diversity. \n\nThe current worry is actually that if the wolves die out then the moose population may get out if control however in a local scenario at least the reverse could theoretically be possible. \n\nHope this is of interest to you. \n\n",
"[In this situation on the Isle Royale](_URL_0_), it *could* happen. If there was an overabundance of the Balsam Fir, which is the moose main food source, then the moose population would go way up. Then with all the moose, the wolves would then have an overabundance of their food source, so the wolf population would rise as fast as it could. If they had enough individuals, they could eventually kill out the moose over time, also killing the wolves. So again, it *could* happen, but it would have to be some perfect situation (like on this island)",
"Happens with fish populations occasionally. If a predator invades an enclosed body of water (introduction via man or naturally) they can wipeout an entire prey base. Kinda what you were asking but this is more about on a microcosm level",
"The only chance of this happening that I could think of would be from an invasive species scenario. \n\nInvasive species introduced..on some small island..maybe they are dietary specialists that prey on say bird eggs...migratory birds visit island annually... then over the years... migratory birds change route...causing a local extinction event...then invasive species change their diet or witness an extinction event of their own.\n\nIF you're interested there is a neat island not far from guam I think that all the birds on the island are extinct. Resulting in massive spider population densities. \n\nCool question though! ",
"One example of this happening would be\n\n1) Sea Otters\n2) Clams\n3) Kelp\n\nSea otter population starts to decline due disease. Result: Clam populations start to rise. As clam populations rise, they start to consume more and more kelp. Sea otter population declines even more. Clams eat so much kelp that it cannot keep pace with them, and eventually starve. But not *all* would starve. So complete extinction would be tough, because even if the clam population shrunk from like 100,000 to 500, the those 500 would have access to any of the kelp that started to grow back and then with less clams, the kelp can grow back very quickly....",
"It's possible that if an entire area had a decreasing population from some external factor (e.g. an island with rising sea levels), that this phenomenon may have occurred. The end result however would be that a whole area would be extinct, making it hard to record the events.\n\nHowever it's extremely hard to find out, as predators have multiple preys, so it would need to make multiple species go extinct until they would disappear. \n\nOn the other hand, smaller prey tend to have lots of offspring. If the predator becomes extinct, then the likeliness that it would come to a 1v1 stand-off would be rare. It would be more likely the case of 1v10+, which would allow the predator to have enough food to last until more offspring is made.\n\nThis response is pretty over-simplified, but I hope it covers some points. I've done a good 30 minute google search, and I can't come with any valid examples. It's entirely plausible, but we have few to no examples of this.",
"The idea is that of a \"superpredator\" (one that causes its own extinction). The thing is once an animal evolves into such a state, it only would last for a short time as such, so the fossil record would be very scarce with evidence. I think almost certainly there have been a good deal of such species throughout earths past, but to find evidence of specific ones will prove difficult. Some think humans have the potential to be our own extinction, partly as a result of superpredation and other resource depletions",
"We live in a rural neighborhood and were just about over run with rabbits. Any time I would pull in at night their eyes would light up across the yards and my dogs would get a hold of one or two per week. A pair of hawks showed up and made it a happy hunting ground for about a year until I finally saw the haws less and less until about 6 months ago when I realized they weren't here at all. I recently saw a juvenile hawk perched on my fence a couple days in a row but he realized this wasn't the best place to hunt yet and moved on. I assumed the juvenile was from the pair that used to hunt my yard and that they are nearby exploiting a new hunting ground and in talking to a neighbor on the other side of the subdivision he mentioned having a pair of hawks that have been hunting that area for the past 6-8 months so I assume the pair rotated with the food source. I've seen a few rabbits recently so I assume their population is on the rise again and probably about the time we get rabbit-ful again, the hawks will rotate back to this side and give the other area a break for a while. I think predators reduce breeding during lean times which probably helps maintain a balance. Not that they make a conscious decision to have less offspring but that their bodies know they aren't living in a rich enough environment to support them well enough to support heavy breeding. Anyway, kind of cool to watch nature take it's course and make adjustments.",
"There is the case of the Stephens Island Wren (island is small, 1.5km^2). Cats were introduced to the island in the late 1894. They went feral and by winter of the next year had wiped the wrens out entirely.\n\nThe cats were then methodologically exterminated over the next 30 years to protect the remaining species of animal on the island.\n\nSo the cats caused direct extinction of the wrens via predation, which led to their own \"extinction\" by humans.\n\nI know this does not match your scenario entirely as cats in general are not extinct, nor did they die out because of lack of prey. But they did manage to get themselves exterminated from the island because of their actions.\n\nIf your scenario has happened anywhere in the world, I would expect it to have happened when two geographically isolated environments are forced to interact due to outside influences. \n\nLike a small population of predators fleeing a sinking island making it another island with appropriate prey animals, but not large enough to support the predators long-term. Or if an opening opens up between two deep cave pools that have been isolated for tens of thousands of years, intruding species to each other in a catastrophic manner.",
"In fact, yes!\n\nPerhaps the best example comes from the cilliate predator-prey pair *Colpidium striatum* and *Didinium nasutum*. The system is highly extinction-prone pairing due to the incredible feeding rate of *D. nasutum*. The excellent ecologist Marcel Holyoak (_URL_1_) has worked extensively with the system.\n\n[Here](_URL_0_) is one of many great papers on the subject.\n\nInterestingly, extinction-prone pairings such as these can persist indefinitely when local populations are connected by dispersal.",
"It hasn't caused total extintion, but cats brought along with explorers and settlers have been blamed for the extinction of several species native to small islands. These species wouldn't have had a very large population in the first place, and the cat's owners would have continued to care for them, but it's there.\n\nOf course, the idea of this happening is hotly contested, but one case where it's fairly certain our feline friends are to blame is the extinction of the [Stephens Island Wren](_URL_0_). Some claim a *single cat* caused this dieoff, though that is fairly unlikley; however, it's true that the island only had a handful of cats, most of whom weren't actually hunting for food.",
"every invasive species? they don't fit in. \n\nthere was this incident where cats were dropped into an island, yes air dropped in boxes, to kill some sick rats. they ended up hunting the local bird population to extinction since the birds couldn't fly.",
"There are abundant examples of this in artificial ecosystems. You can create a closed ecosystem with Hydra (the predator), Daphnia (the prey), and algae. This system will cycle through a chaotic series of variations and it will inevitably crash due to the extinction of either the Hydra or the Daphnia, resulting in the loss of the other species.\n\nYour question is meaningless, however, in a complex environment, because it attempts to reduce a chaotic system to a single set of axes. Reality is chaotic and not amenable to such reductionism.\n\nIf anyone were to propose, as a hypothesis, that what you suggest may have happened, the multifactorial nature of a complex environment would necessarily prohibit a definitive answer to the question. The hypothesis would be instantly falsifiable due to an infinity of potential interactions inside the system. That is how complexity works: you can only find out the truth by watching it unfold, and, even then, the uncertainty principle prohibits you from being completely informed about the nature of the system.\n\nYou may only ask the question for a non-complex ecosystem.",
"There's a chapter of Gordon Grice's **the red hourglass: lives of the predators** that covers the brown recluse, also known as the violin spider.\n\nHe includes an account of an isolated brown recluse population that eats its prey to extinction, and resorts to cannibalism before inevitably dying out. \n\nNow, I read this book as a child, so I'm uncertain of Grice's scientific stature. It was, however, very compelling. \n\nLink: _URL_0_",
"Its very hard to get down to 0. I can imagine that such a thing could have happened. Except instead of it being animal v animal more of a virus v animal (If you consider viruses as life)... If you introduce a very effective and contagious virus that stops reproduction of a species that may already be concentrated can pretty much knock it out of existence and at the same time eradicate it self. 4.6 billion years of life.. Im sure its happened at least once. ",
"Closest thing I can think of for this is the introduction of the Brown Tree Snake to Guam. Its introduction has devastated the local bird life as it is a natural climber and nocturnal hunter.\n\nThe bird life is pretty much gone but the snake is doing very well because it has alternate food sources; other introduced species such as rats.\n\nCould it have caused the extinction of the bird life and then itself if it had no alternate food source?",
"Although this may not be exactly what you were asking, you can win the bet with it.\n\nHumans. Humans have over-exploited many populations, there are dozens of examples of this, including the Dodo bird, passenger pigeon, Baiji White dolphin, and more.\n\nI hope this counts as part of your bet! ",
"No, most articles of extinction due to natural predation was proven to be false. The success rate of hunts are low. Due to the low success rate it would be impossible for predators to hunt prey to extinction.\n\nOf course there are some predators that just kill without any desire to eat it but even those kills are few in numbers, it just isn't enough to make a prey animal to go extinct. \n\nThere is no way to make a prey population go extinct through natural hunting. However, unnatural deaths such as ones caused from humans do make animals go extinct, indirectly and directly. ",
"Is there any indication that predators have understanding of the need not to do this?\n\nThat lions attack the weakest prey (I think) is practical for them but might tend to strengthen the prey species. It might simply be that by doing this and not killing unnecessarily predator species do not wipe out their prey.\n\nBut could observance of the \"truce\" of the waterhole (Kipling?) be based on an understanding that the prey need to drink in order to survive?"
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"http://en.wikipedia.org/wiki/Cascade_effect_%28ecology%29"
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[],
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"http://en.wikipedia.org/wiki/St._Matthew_Island"
],
[
"http://www.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-110411-160304"
],
[
"http://en.wikipedia.org/wiki/Moa",
"http://en.wikipedia.org/wiki/Easter_Island"
],
[
"http://www.bbc.co.uk/schools/gcsebitesize/science/images/10_lynx__hare.gif"
],
[],
[],
[],
[],
[],
[
"http://en.wikipedia.org/wiki/Traumatic_insemination"
],
[
"http://www.isleroyalewolf.org/overview/overview/at_a_glance.html"
],
[
"http://en.wikipedia.org/wiki/Wolves_and_moose_on_Isle_Royale"
],
[],
[],
[],
[],
[],
[],
[],
[
"http://www.des.ucdavis.edu/faculty/holyoak/MHpubs/Holyoak_Lawler_Ecology_1996.pdf",
"http://www.des.ucdavis.edu/faculty/holyoak/"
],
[
"http://en.wikipedia.org/wiki/Stephens_Island_Wren"
],
[],
[],
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"http://www.amazon.com/gp/aw/d/0385318901?pc_redir=1405230126&robot_redir=1"
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fzybsr
|
How did the Crusader states tend to view and interact with the Arab and Eastern Christians they lived around and ruled? Did they intermarry? Hire them freely? Did any Arab Christians rise to prestige in these realms?
|
Finally, what happened to them when the Crusader States we’re finally conquered? Did any move to Europe?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/fzybsr/how_did_the_crusader_states_tend_to_view_and/
|
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"I answered a similar question recently:\n\n[What was the social standing of oriental christians in the crusader states of the levant?](_URL_0_)\n\nTo summarize: Eastern Christians had a pretty high social standing, they intermarried with the crusaders frequently, and they often served in the military, as doctors, as merchants, and could become quite wealthy and prestigious. \n\nI don't know if any of them moved to Europe after 1291, but eastern Christians were also prominent on crusader Cyprus in the 13th and 14th centuries."
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|
7ficf3
|
What is the velocity of the edge of a bubble as it is "popping"?
|
Take a bubble - soap/water, milk or otherwise - and initiate a "pop" from a single point on the surface. What would be the velocity of the bursting edge, as it propagates away from the initiation point?
[Here is a video](_URL_0_) of some bursting bubbles in slow-motion. Notice that the bursting edge recedes from the initiation point; the intact surface remains unaffected until the bursting edge reaches it.
For simplicity, assume a *perfect bubble*:
- Perfectly spherical
- Evenly distributed surface
- No external forces (i.e. gravity, which would cause deformation and pooling of the medium)
- "Pop" or burst initiated from a single point on the surface
It seems intuitive that the *upper limit* would be the **speed of sound** for whatever medium the bubble was made from, because the speed of sound would be the physical limit that the information could be passed along that the bubble was popping. But I'm unsure what role the [pressure differential](_URL_1_) might play - if any at all.
|
askscience
|
https://www.reddit.com/r/askscience/comments/7ficf3/what_is_the_velocity_of_the_edge_of_a_bubble_as/
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"The link you provided for pressure differential includes an MS paint free body diagram. From this diagram we see that at any point on the bubbles surface, the forces due to surface tension are actually orthogonal to the forces due to the pressure differential. For this reason, forces due to pressure differential can be ignored in calculating how quickly the break will move along.\n\nUnless there is something else to be considered, I'd say that the upper bound of the material's speed of sound is a very reasonable approximation for the speed of propagation of the surface break.",
"\nThat BB was only outpaced by the poping by a slight amount. On one plane it was very slightly in the lead at the end, but take into account that it had to go around at the radius of the bubble it was quite a bit faster.",
"On mobile, so sorry for the spelling errors and typos. \n\n\nI imagine that the viscosity of the bubble material and the shear force of the liquid plane traveling through the gas are important factors.\n\nWe typically use liquids containing surfactants (such as soap) to achieve a liquid with low surface tension and viscosity. \n\n\nI also think the upper limit is significantly less than the speed of sound in the material for a couple different reasons. First, when a bubble bursts the matter travels *around* the surface of the bubble, in a circle. This requires a change of momentum not required if the material is traveling in a straight line. Second, when a bubble bursts, all of the material goes *with* the “shock wave.” When sound travels through a material, there is just a slight movement of each molecule; the energy from one molecule is passed along to the next (minus some frictional losses). In a popped bubble on the other hand, all of the material “clumps” together moving at the same speed. This means that enough energy is needed to accelerate all of the atoms to some top speed. \n\n\nThe best analogy I can think of is a train accelerating from a stop. In the ”speed of sound” case, the “speed” would be CLUNK CLUNK CLUNK of each train car’s hitch getting pulled taught. This happens really quickly and the CLUNk travels all the way to the last car in almost no time. In the bubble example, we have to accelerate all of the actual train cars to some top speed. \n\n\n\nTD;DR I have no idea how to calculate the top speed outside of experimentation, but I am guessing that it is significantly less than the speed of sound in the material. Like 1-3 orders of magnitude less. ",
"A rough approximation can be calculated:\n\n* Determine frame rate of the original video recording\n* Determine size of bubble in video\n* Measure time for bubble to pop\n* Calculate speed: distance divided by time\n\n & nbsp;\n\nLooking at the bubble at 1m43s: _URL_0_\n\n* video is recorded at 18,000 FPS.\n* bubble size is about 15 cm.\n* time to pop is about 13 seconds.\n* 13s of video at 18,000 FPS is 0.72ms of real time. 0.15m/0.72ms = 208 m/s\n* edit: MorRobots did the speed calculation for a spherical surface: 362.2 m/s\n\n & nbsp;\n\nThe bubble size and duration of the popping are just rough numbers and can be approximated better but it'll get you in the right ballpark.\n\nFor homework, you can do the math for traversing a sphereical surface instead of the simpler calculation I'm using.",
"This thread had me smiling. I love how innocent the prompt is. A bubble popping. Something we have all seen before and probably have all wondered about what’s happening when it pops. I’m very thankful for the informed guess of OP as well as the science behind most of the answers! I know this is r/science but sometimes it’s nice to smile and think of things other than wars and politics :) have a good day everyone!",
"From the video, it looks like the process goes as follows:\n\n- the edge of the bubble has an imbalance of forces because it has surface tension on one side and nothing on the other \n- this causes the edge to accelerate for a short distance d_step\n- after accelerating for a bit, turbulence occurs and the accelerating edge vaporizes\n\nLet's turn this picture into an order of magnitude estimate of the velocity. Let the surface tension be gamma. Consider an edge of length L (L will cancel out of the result). The force on the edge is F=2 gamma L (the factor of 2 is because there is both an inside and outside surface).\n\nWhat is the mass of the edge? Naively it's zero because the edge is a 2-dimensional surface of size L d_thick, where d_thick is the thickness of the bubble. But this leads to an infinite acceleration which is obviously wrong. Instead there's some distribution of accelerations near the edge that depends on the actual shape of the water near the edge. We can model this by saying that the edge has some effective \"depth\" d_depth (that we'll fix soon). Thus, the mass is m=rho L d_thick d_depth.\n\nThus the acceleration is a = 2 gamma L / (rho L d_thick d_depth). The acceleration occurs over a distance of d_step before turbulence sets in. The velocity accrued over this distance is \n\n- v = sqrt(2 a d_step) = 4 sqrt(gamma d_step / (rho d_thick d_depth)).\n\nNow what do we plug in for these values? I don't know what d_step and d_depth should be, but it's reasonable to expect that they should be similar to d_thick. From wikipedia,\n\n- gamma_water ~ 0.07 N/m\n- d_thick ~ 100 nm \n- rho = 1g/cm^3\n\nwhich gives\n\n- v ~ 50 m/s\n\nThis seems like roughly the order of magnitude of other estimates in this thread, though maybe a bit slow. That can perhaps be fixed by coming up with a better model for d_step and d_depth.",
"A typical retraction velocity is 10 m/s [Lee et al. 2011](_URL_0_)\n\nThe velocity is influenced by surface tension and viscosity as described by the Ohnesorg number ([_URL_1_](_URL_1_]))",
"This is how it can be derived in terms of kinetic energy:\n\n_URL_0_\n\n_URL_3_\n\nVia these sorts of papers:\n_URL_2_\n\nWhich say:\n\nThe Velocity = Square Root ( 2 * Equilibrium Surface Tension / (Density of Liquid * Film Thickness)\n\nEdit - Here's the original derivation:\n_URL_1_"
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[] |
[
"https://www.youtube.com/watch?v=blNe2Ae5a2c",
"https://physics.stackexchange.com/questions/127695/why-is-the-pressure-inside-a-soap-bubble-higher-than-outside"
] |
[
[],
[],
[],
[
"https://www.youtube.com/watch?v=ktvZ2Z_s4Bo&t=103s"
],
[],
[],
[
"https://www.nature.com/articles/ncomms1369",
"https://en.wikipedia.org/wiki/Ohnesorge_number"
],
[
"https://liquifun.wordpress.com/2013/03/08/how-fast-does-a-bubble-burst/",
"https://www.researchgate.net/publication/260567004_Comments_on_a_Ruptured_Soap_Film",
"https://arxiv.org/pdf/1503.06197.pdf",
"https://en.wikipedia.org/wiki/Soap_film#cite_ref-1"
]
] |
|
di284q
|
why does the door between my garage and my house slam harder when the garage door is open?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/di284q/eli5_why_does_the_door_between_my_garage_and_my/
|
{
"a_id": [
"f3sxhsp",
"f3sxmdp",
"f3sygnw"
],
"score": [
6,
3,
2
],
"text": [
"Imagine your entire garage was overflowing with cotton balls. When you try to slam the interior door the cotton balls slow the door down. It doesn’t slam. \n\nWhen the garage door is open slamming the interior door works. This is because the cotton balls easily slide out the big garage door while you are slamming the interior door. \n\nAir is exactly like very light cotton balls.",
"It's because when your outside garage door is open, your inside door can push the air outside with little resistance. \nBut, when your outside for is closed, there is no where for that air to go and so it increases the sure pressure in the garage which tries to equalise with the air in your house resulting in some force pushing back on the door.",
"They probably meant air pressure with the submarine explanation.\n\nWhen the garage door is open and you slam the \"interior door\" the air from the outside comes in to replace air you just pushed inside the house from the garage.\n\nIf the garage door is closed then it takes longer for the air to get inside and fill the space, so the interior door will be harder to move. It will be harder to move because as it's closing it moves air from the garage to the inside of the house. The pressure will be temporarily higher on the inner side, because there is suddenly more air on that side, and less in the garage. This extra air inside the house pushes the inner door back, while the lack of air in the garage pulls it.\n\nIt takes time until the pressure balances out. ( normal amount of air both sides ) \n\nIf the garage door is open it happens quickly. If it's closed then more time is needed."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
3zxwha
|
Why isn't over-eating/obesity treated as an addiction ?
|
I was comparing the DSM-IV and V, and especially with the shift towards evidence based medicine, it really seems like there should be a push to view conditions like this under the purview of addiction.
|
askscience
|
https://www.reddit.com/r/askscience/comments/3zxwha/why_isnt_overeatingobesity_treated_as_an_addiction/
|
{
"a_id": [
"cyqdy5i",
"cyqi37h"
],
"score": [
6,
2
],
"text": [
"Obesity may not be the source of over-eating, it could be due to a number of other factors (like food intolérances and allergies, hormonal imbalances, inflammation, etc...). Over-eating itself might have an argument of addiction, but that can be due to multiple factors. Not necessarily a straightforward correlation. ",
"I'd argue that over-eating is not treated as addiction because it is inherently physiologically programmed. We are designed to overeat and put on weight - obesity is a normal physiological response to an obesogenic environment, as many public health researchers have put it (see, for example, Boyd Swinburn in [this](_URL_0_) excellent Lancet review.\n\nThis is supported by biological evidence, that humans have very few systems to prevent weight gain, and very many to promote it. "
]
}
|
[] |
[] |
[
[],
[
"http://www.mineralmed.com.pt/documentos/pdf/e94490a7-1f16-4955-bdb0-0674adfd77b4.pdf"
]
] |
|
dlu1bt
|
zippers?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/dlu1bt/eli5_zippers/
|
{
"a_id": [
"f4ud0au"
],
"score": [
3
],
"text": [
"Strength comes in numbers. If you look at a zipper, the teeth are REALLY small and there are a lot of them. So any pressure against the zipper is divided and spread down to a much smaller force. \n\nHow do they work? Well if you look really closely at a few of the teeth, you’ll see that they have pits on one face of a tooth and a nub sticking out on the other side of the tooth. When the teeth come together at an angle within the slide pull, the nub nestles into the dimple. This also increases the surface area of contact which amplified the strength point above. The slide pull is designed to bring the two sides of teeth together at the right angle for the mesh to occur."
]
}
|
[] |
[] |
[
[]
] |
||
157sk3
|
why does mathematics always work? are there any other universal truths?
|
I've always been taught how to do math but I've never been taught why is works. I understand why it works with addition, subtraction, multiplication and division... it's simple observation and logical deduction. However, I don't understand why more complex mathematics such as algebra, trigonometry, and calculus works every time. I get very confused when you throw in fastballs such as imaginary numbers and undefined variables.
Are there any other universal truths that don't revolve around mathematics?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/157sk3/why_does_mathematics_always_work_are_there_any/
|
{
"a_id": [
"c7k0k03",
"c7k0y7i",
"c7k3iz5",
"c7keyyt"
],
"score": [
16,
2,
3,
2
],
"text": [
" > However, I don't understand why more complex mathematics such as algebra, trigonometry, and calculus works every time.\n\nComplex mathematics are just the logical extension of simple mathematics. They work for exactly the same reasons that simple math does. It's the same observation and logical deduction process applied to much more challenging problems.",
"When calculus was invented, I'm pretty sure it was derived from more simple mathematics in order to model how things like acceleration, velocity and position relate to each other. \n\nThere are, however, a couple parts of math that are completely human designed and could work in many other ways if we wanted them to. For example, the way matrix multiplication works is completely arbitrary.\n\nBut most mathematics is just derived from simpler mathematics. New concepts like imaginary numbers come into being because we already had square roots, and if you take the square root of a negative number it doesn't work, but using this other mathematics we already have, it can be useful.",
"Semantic truths, tautologies, and a few other things are universally true.\n\nSemantic truth examples: \n\n\"No bachelors have girlfriends\"\n\n\"There are no square circles\"",
"Math doesn't \"work\" to address all problems.\n\nFor example, let's say that you walk into a room with `n` suitcases. In each suitcase is a cashier's check for $100k. Every time you open a suitcase, you keep the check. That is, except for one suitcase. One of those suitcases, if you open it, deals immediate and certain death (say it fills the room with a poisonous gas that you immediately and painlessly succumb to). What is the smallest `n` for which you would open one suitcase?\n\nYou can use math to help you understand the nature of this problem, but at the end of the day you cannot use math to give you an exact answer.\n\nFor instance, you can say, well, every weekday I drive to work. Each time I make that decision, I'm taking a small risk of death just by getting in the car. Certainly $100k is worth more to me than going to wherever I'm using the car to go on a given day, so if I choose `n` so that the risk of dying is the same as my daily commute, I would certainly open at least one suitcase.\n\nYou can also certainly figure out certain values of `n` for which you definitely wouldn't open a suitcase. For instance, if `n=10`, you probably wouldn't want to risk a 10% chance of dying just for $100k. That's a bad deal unless you're suicidal.\n\nYou can keep reasoning using math until you place `n` in a box, but at the end of that process, you'll probably find it's a pretty big box and `n` is somewhere between the hundreds and the hundreds of thousands.\n\nOnce you figure out your values of `n` that are \"definitely no\", \"definitely yes\", and \"maybe\", you can compare those to other people's values and probably make some interesting mathematical models. (Really, a better way to do it is to abstract the problem into a straight risk-reward curve where you can say straight up I'll accept `x` chance of death for `y` reward. This is a much better model to work with because it allows you to identify asymptotes–your \"definitely no\" number–and compare a much richer set of information to other people's chosen curves.)\n\nSo math can answer a great many questions, but you have to pose the right question. As I initially stated it, it's not a mathematically interesting question until you break it down a bit more and start to figure out what math *can* do for you."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
39ukxk
|
How did speakers of Cockney Rhyming Slang propagate an agreed set of word substitutions?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/39ukxk/how_did_speakers_of_cockney_rhyming_slang/
|
{
"a_id": [
"cs6wuxc"
],
"score": [
10
],
"text": [
"I think you're thinking about this all wrong. it's not like the Cockney poor would meet in a semi-regular basis and agree on this stuff. \n\nit would advance like any other word. someone starts using it, and someone else likes that word, and starts using it too, and so on and so forth until it's fairly ubiquitous.\n\ntl/dr ask /r/etymology"
]
}
|
[] |
[] |
[
[]
] |
||
261v7h
|
How much energy is in the Internet?
|
Can we quantify how much energy is stored globally in the Internet once it leaves my device? Does that data, the bit transfers, all of it, amount to energy? Lastly, can we quantify that energy consumption as a percentage of all global energy production and would it be significant?
|
askscience
|
http://www.reddit.com/r/askscience/comments/261v7h/how_much_energy_is_in_the_internet/
|
{
"a_id": [
"chn6adq",
"chn6w7r"
],
"score": [
4,
2
],
"text": [
"The short answer: Yes.\n\nTake a sample bite of 8 bits. \nThe electrical current needed to pass the information from one device to another can be measured (or predicted.) \nThe energy requirement for storing the data can also be calculated (life of a harddrive with redundancy mechanisms vs total energy requirement to produce etc.) \n\nThe feasibility of such a task? Forget it. \n\nMore importantly though, the internet is not some easily quantifiable thing. The internet is a term for all our connected nodes around the world, it is an extension of humanity, which again is an extension of nature and the earth itself. \nWhile we *could* quantify the total energy requirement of \"the internet\" (disregarding the energy savings/return the internet indirectly provides, going full circle), that task is as said, unfeasible.\n\nAnother question is where one should draw the line. At the extraction of minerals? At the formation of mineral veins in the early days of the earth itself? ",
"The power involved in the Internet is absolutely significant. Some of it is involved in the losses from data transfers (particularly over long copper lines), but it's much more than that. Looking at the abstracts from a [summit google held](_URL_0_), I see thing such as:\n\n - the ubiquity of end user equipment\n - data centers\n - transmission (particularly wireless)\n - routing hardware\n\nLots of articles ad research are ongoing on the topic. In my quick searches, I'm seeing numbers as high as 10% (very rough) for electricity usage caused by the Internet.\n"
]
}
|
[] |
[] |
[
[],
[
"http://www.google.com/events/howgreenistheinternet2013/"
]
] |
|
1glaf5
|
Insurance in pre-Industrial era
|
Hi all. I am posting for the first time here. Mostly a lurker and just read stuff. I tried looking for but couldn't find about if there was a system equivalent to modern insurance (health/property etc) in any pre-industrial societies in the world and if so, what major differences does it have with current models. Also, how and when did it first start ? Thanks in advance.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1glaf5/insurance_in_preindustrial_era/
|
{
"a_id": [
"calr34u"
],
"score": [
2
],
"text": [
"In the early modern period social organizations provided something akin to modern insurance. By the seventeenth century there was actual insurance that we would recognize to day, but I'm not entirely sure how popular or widely available it was. Prior to that, most forms of insurance (help if you were unable to work due to illness, help with burial, help to deal with catastrophes like a burned down house) came from trade guilds. Neighbors and family members also frequently provided help to each other."
]
}
|
[] |
[] |
[
[]
] |
|
685fud
|
How is it possible that ocean life is facing mass extinction considering that the ocean covers more than 70% of the surface on our planet and the majority of it is unexplored?
|
askscience
|
https://www.reddit.com/r/askscience/comments/685fud/how_is_it_possible_that_ocean_life_is_facing_mass/
|
{
"a_id": [
"dgx5q0i"
],
"score": [
3
],
"text": [
"I just wrote a research paper on coral reefs and they are home to over 25% of marine life. They are also very delicate ecosystems that are very prone to clime change i.e temperature increases, sea level rise and terrestrial run off. With entire coral reefs being permanently wiped out the Eco systems fade out as well and that accounts for a lot of the diversity of marine life. I really didn't understand why some reefs were important until writing this paper. To further address your question I think a lot of it is error in statistics since the majority of the ocean is truly unexplored. We can make guesses but we really don't know. All of this information is off of Wikipedias page on coral reefs and I wrote the paper for an environmental physics elective, I am by no means a scientist and I'm sure Reddit will provide more insight "
]
}
|
[] |
[] |
[
[]
] |
||
ie60i
|
What is the most efficient form of heating?
|
Is it simply heating via electrical resistance? Is there a more efficient method of heating available?
|
askscience
|
http://www.reddit.com/r/askscience/comments/ie60i/what_is_the_most_efficient_form_of_heating/
|
{
"a_id": [
"c230ew7",
"c230fkt",
"c232itn"
],
"score": [
9,
3,
2
],
"text": [
"If you are talking about heating your home, reverse-cycle air conditioners are the most efficient option. They operate as a [heat pump](_URL_0_), which means for every unit of heat they produce by consuming energy, they also \"pump\" some heat from the cold source outdoors to inside your house. The ratio of how much heat they produce and move from the cold side to the hot side compared to how much energy they consume is known as the Coefficient of Performance (COP). Electric heaters work by directly converting electrical energy into heat (they don't move additional heat from a cold source), so their COP is 1.\n\nIn Australia reverse-cycle air conditioners are very efficient due to our mild climate. The COP of heat pumps reduces as the outside temperature drops though. So if you are in a very, very cold environment, their efficiency approaches that of electrical heaters. In this case, efficiency can be improved by using the relatively warm ground as your cold source rather than the outside air.",
"This depends on how you're defining \"efficient\". The energy for a coil heater has to come from _somewhere_, like a power plant, and there are energy losses in every step of the process of creating that electric power and getting it to your house. If we're only talking about various electric powered methods though, then yes, electrical resistance is a very efficient way of making heat, mostly because making heat is easy, and almost all the power dissipated in the heating coil is done so as heat. You can think of heat as the lowest common denominator of energy--easy to get to, but it's difficult/complicated to make anything else out of it.\n\nRemoving heat from your house is hard, which is why a fan room heater is a lot smaller and cheaper than a window unit AC.",
"tl;dr: how do you get the highest temperature differential with the least amount of energy.\n\nI think what the OP is trying to ask is for the method that generates the highest temperature differential with the least mount of energy input or wasted. For example, an electric resistance coil also generates visible light, that light could be considered 'wasted' energy. Are exothermic chemical reactions more efficient? For example, if you calculated the energy in pile of coal, and then burnt said coal and measured it's thermal output, then applied that same amount of energy as electric flow, would you get more or less thermal output, deeming one to be more efficient than the other?\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Heat_pump"
],
[],
[]
] |
|
12umv2
|
Was there oil during the dinosaur era?
|
As in car oil that comes from fossils? Was there sufficient oil in the ground millions if years ago?
|
askscience
|
http://www.reddit.com/r/askscience/comments/12umv2/was_there_oil_during_the_dinosaur_era/
|
{
"a_id": [
"c6y9dzg"
],
"score": [
42
],
"text": [
"Yes, there was. Much of our 'fossil fuel' comes from a time period known as the Carboniferous, which was about 300 - 360 million years ago, well before the time of the dinosaurs. This period is called the Carboniferous precisely because there's a high abundance of carbon in the rock record from that time. This is often preserved as coal or petroleum. Most of this carbon material derives from plants and algae, rather than the more familiar fossils of vertebrate animals.\n\nDinosaurs did not appear until the middle Triassic about 230 million years ago."
]
}
|
[] |
[] |
[
[]
] |
|
o741m
|
Why do certain noises make my teeth hurt?
|
Certain noises (particularly when someone makes a raspberry) hurt my front teeth, and give me the intense urge to bite down on something. It's a most irritating sensation that I find difficult to describe. Is there a reason certain noises irritate them more than others (for example, the sound of a rake on concrete does this to my sister, but doesn't bother me in the slightest)? The sound even makes me a little angry. Does anyone have an explanation for this?
**TL;DR** See title.
|
askscience
|
http://www.reddit.com/r/askscience/comments/o741m/why_do_certain_noises_make_my_teeth_hurt/
|
{
"a_id": [
"c3eyz9u"
],
"score": [
5
],
"text": [
"This question pops up on this subreddit periodically (just saw it less than a week ago).\n\nFrankly, no one knows. There are some [speculative theories](_URL_0_) having to do with primate warning calls but they seem to be poorly supported. "
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Sound_of_fingernails_scraping_chalkboard"
]
] |
|
3h7les
|
How does 4k upscaling work?
|
How does non 4k (usually 1080p) content somehow appear "better" on a 4k screen and not grainy like a low resolution video being displayed at a higher resolution normally is?
|
askscience
|
http://www.reddit.com/r/askscience/comments/3h7les/how_does_4k_upscaling_work/
|
{
"a_id": [
"cu56yj3",
"cu5wc2v"
],
"score": [
4,
3
],
"text": [
"I cannot speak to the specific technologies used for up-scaling in consumer devices, however [this video](_URL_0_) shows a demo of seam-carving/re-targeting which is one possible means of up-scaling video while preserving image and content quality.",
"The easiest way to perform upscaling is to have an algorithm process each frame and average pixel to pixel variations to \"fill in\" the extra content. This can be done with very low processing overhead.\n\nFor more advanced upscaling you're still doing frame by frame operations, but smarter algorithms can upscale by determining edges, outlines, textures, and content and fill in details, producing a perceptibly sharper image.\n\nI just upgraded my HTPC (thanks, Satya Nadella). My new video card works with my new version of PowerDvd to upconvert 480P DVDs to 1080P using smarter algorithms. The difference is remarkable. You still get a significantly better picture from native content, but newer upscaling algorithms are light years beyond the old pixel-averaging techniques."
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=AJtE8afwJEg"
],
[]
] |
|
u5xiy
|
How dangerous is a bubble in the bloodstream? What is the likelihood of a bubble being introduced into the bloodstream during an intravenous drip/ injection?
|
I was once laid up in intensive care as a kid for ~10 days and I remember the nurses being paranoid about the drip running out. The best answer I could get from them was that if the glucose ran out, it could induce a bubble in the bloodstream which could cause a heart attack.
Seems a bit far fetched to me - that would basically make any injection a potentially lethal procedure (if the doctor/ nurse were to be careless and pump in a little air along with the injected fluid).
So Askreddit, are we potentially playing with our lives each time we get an injection/ IV drip?
|
askscience
|
http://www.reddit.com/r/askscience/comments/u5xiy/how_dangerous_is_a_bubble_in_the_bloodstream_what/
|
{
"a_id": [
"c4sl25g",
"c4sl3zq",
"c4srxwe"
],
"score": [
2,
3,
2
],
"text": [
"Yes, within reason it's entirely possible. It's not really easy, and most current IV pumps are designed to detect bubbles and clamp the line to prevent this issue. Not everything goes through a pump at all times in all sites however, and machines fail too. It's also not critical until we're talking about large volumes of air.\n\nAn air embolism of 5ml/kg can cause cardiac failure, but smaller amounts can cause problems in circulation in other areas. The air may not mix appropriately in the blood, and thus travels as a bubble down the circulation, until it reaches a point it's too big for. It then creates a blockage, just like a blood clot or fat embolism.\n\n[Here's a case report.](_URL_0_)\n",
"Small enough bubbles are not particularly dangerous; they are often purposely injected into the bloodstream in order to improve contrast during diagnostic ultrasounds.",
"ICU nurses tend to seem paranoid about lots of things. Paying close attention to everything is a big part of the job. :)\n\nAs a nurse, I can say that we generally don't want any IV fluid to run out. But it's not because of air embolism. Instead it's just that we don't want to leave you wtihout the medication. If you're getting something by continuous IV, there's a reason we are giving it to you, and it should stay as close to continuous as possible.\n\nIf you were getting a significant amount of IV sugar, I'd also have been careful not to of letting it run out. When that sort of infusion is suddenly stopped and stays off for some time, your blood sugar can drop rather quickly in its absence. That would be very uncomfortable, and potentially dangerous if it went untreated, so we're careful to avoid the whole situation.\n"
]
}
|
[] |
[] |
[
[
"http://casereports.bmj.com/content/2012/bcr.01.2012.5488.long"
],
[],
[]
] |
|
10c7p9
|
Did Poland save Western Europe at the Battle of Vienna in 1683?
|
I'm aware of the general circumstances surrounding the conflict but there's a lot of "fluff" surrounding the battle and its repercussions. Were Jan Sobieski and his troops the deciding force in the battle and was the war really a life and death struggle for the West/Christianity?
Also, any good books on the subject or the Polish-Lithuanian Commonwealth?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/10c7p9/did_poland_save_western_europe_at_the_battle_of/
|
{
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"c6c7ve4",
"c6c8jdu",
"c6ccf56",
"c6cfd1f"
],
"score": [
5,
9,
3,
6
],
"text": [
"I'll leave the debate on the battle and its effects to those more expert than I, but I am happy to suggest some light reading on Poland-Lithuania!\n\nIf you have access to the **Cambridge Medieval History** (in a library, or through your school or University having an online subscription) I would start there for a basic narrative overview of the creation and early development of the Commonwealth (vols v. and vi would probably be best for this).\n\nAfter - or instead of this - I believe that Davies is still generally regarded as the textbook English language introduction to Polish history. God's Playground is excellent, and a joy to read **(N. Davies, God’s Playground. A History of Poland)**, and his Heart of Europe is a shorter alternative. **(N. Davies, Heart of Europe. A Short History of Poland (1984).**\n\nIf Davies is being elusive there are lots of other general texts available - here are a few that I can remember: \n\n**G. Łukowski & H. Zawadzki, A Concise History of Poland (2nd edn Cambridge, 2006**\n\n**W.F. Reddaway (ed.), The Cambridge History of Poland: From the Origins to Sobieski**\n\n**S. Rowell et al., A history of Lithuania (2002)**\n\n**S.C. Rowell, Lithuania Ascending.** \n\nThe interaction of the Poles and Lithuanians with the Teutonic Order is very exciting, **W. Urban, The Samogitian Crusade.** and **E. Christiansen, The Northern Crusades** - the bibliography of which will lead you in seeking further reading on the topic.\n\n**R. Butterwick (ed.) The Polish-Lithuanian Commonwealth in European Context, 1500-1795 (2001)** and **K. Friedrich (ed.), Citizenship and Identity in a Multinational Commonwealth: Poland-Lithuania in Context (2009)** are worth a look too - they are a bit more specialised than the general texts above, but still perfectly accessible.\n\nI would especially recommend **Natalia Nowakowska's, Church, State and Dynasty in Renaissance Poland (2007)** which is energetically brilliant. ",
"They saved Austria and the Empire, but Europe I don't see how, the Ottomans weren't on a *djihad* kind of war, and being a close partner of France they would just have conquered the Austrian and maybe some Germanic Provinces. ",
"To build on this question a bit, could they have conquered the rest of Europe even if they won at Vienna? They'd have to cross the Alps and, seeing as they were in a general decline at that point, it would probably stretch them too thin. They were already having enough trouble with all the different ethnic groups under their rule that were getting pretty antsy...",
"Fdurke and Premislaus make good points when they say that the Ottoman Empire already faced decline and probably would not have progressed into France (this could have changed once they consolidated power in the Germanic lands but there is a good chance that the Ottomans would not have been able to progress even if their alliances shifted). However, as an Austrian it seems to me that the Polish army saved a very important part of Europe. How would Europe have developed with all of the east and half of the west controlled by the Ottoman empire, even a weak one (especially a weak one), instead of European leaders working together in a more-connected, Western system during a period of massive growth and change? What would the next centuries have been like for the entire continent? The effect would have been significant even if the Ottomans didn't push all the way to the Atlantic. \n\nI only wish that the battle was on the border and not in Vienna - there was a lot in the middle, including my town, where the Alleluja (Hallelujah) caves are so called due to local confusion over the cries of \"Allah\" exclaimed by the Ottoman soldiers as they killed the people hiding there. Some of the bodies lay there until the time of my great grandfather, as people had fled into the caves in an effort to escape, and not all of their bodies were found until mountaineering came into vogue. \n\nTL;DR Sort of."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
d8yqgf
|
understanding type 1 diabetes
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/d8yqgf/eli5_understanding_type_1_diabetes/
|
{
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"text": [
"Oh boy, this is a loaded set of questions. I'll try to break it down a bit...\n\nWhy test yourself multiple times a day?\n- The level of sugar in your blood changes throughout the day. It can change through the things you eat or drink, or how active you are. How stressed you are. If it gets too high or too low, you can get very sick and potentially die. Monitoring sugar (glucose) levels is necessary. \n\nWhat is A1C and what's the ideal level?\n- When there's a lot of sugar in your blood, it binds to specific parts of your blood (the hemoglobin). That sugary hemoglobin is A1C. The American Diabetes Association recommends a level below 53 mmol/mol. \n\nWhy are there so many different kinds of pumps?\n- Mostly marketing. Why are there different kinds of deodorant? Each pump may have something unique to it, but at the end of the day, an insulin pump delivers insulin and the features/functionality comes down to preference or ease of use. \n\nWhy are there different kinds of insulin?\n- This one is a little bit more complicated. Some insulins act quickly. Some take longer to kick in. Some last a long time. Some don't last very long. Which one that a diabetic person needs depends on how frequently and quickly their sugars tend to change. If their sugars aren't prone to changing quickly or suddenly, a long lasting insulin can keep them stable all day. If their sugars swing wildly, they may need something that acts more quickly. Every person is different, and often has a specialist following them to help find a particular setup that works for them."
]
}
|
[] |
[] |
[
[]
] |
||
ji43o
|
why alcohol changes your emotions?
|
More specifically, why do different *types* of alcohol have different emotional effects on people? When someone says whiskey tends to make me angry, and rum makes me sad, why the difference? Is it psychological or chemical? Or both?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/ji43o/eli5_why_alcohol_changes_your_emotions/
|
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"Alcohol doesn't really change moods but it makes moods alreaady there stronger. It might also expose some hidden moods. Different alcohol makes people react differently because they've learned to have those expectations, not because of chemical differences. Someone might drink a particular drink when they're happy or sad and then start associating the drink with the emotional effects. ",
"I think it's probably psychological. A person has an experience with one alcohol and then associates the events with the liquor.\n\nI've seen some weird claims, such as Tequila acting as a stimulant, but I've never read any scientific evidence on that.\n\nI know Absinthe gets its reputation for the artist that used it. A lot of those artist had psychological problems to begin with, making it seem like the alcohol was \"hallucinatory.\" I've never actually tried it, but it seems like the effect of wormwood isn't what people expect it to be.\n\nIn general, from what I remember, alcohol has to do with the GABA brain receptor, which Benzo's also use. I'm trying to logically guess that it has something to do with motor functions, but it's been a while since I read up on it.\n\nI'll let this post serve as a placeholder since I'm not an expert. Just some basic background in psychology/biopsych.",
"Alcohol doesn't really change moods but it makes moods alreaady there stronger. It might also expose some hidden moods. Different alcohol makes people react differently because they've learned to have those expectations, not because of chemical differences. Someone might drink a particular drink when they're happy or sad and then start associating the drink with the emotional effects. ",
"I think it's probably psychological. A person has an experience with one alcohol and then associates the events with the liquor.\n\nI've seen some weird claims, such as Tequila acting as a stimulant, but I've never read any scientific evidence on that.\n\nI know Absinthe gets its reputation for the artist that used it. A lot of those artist had psychological problems to begin with, making it seem like the alcohol was \"hallucinatory.\" I've never actually tried it, but it seems like the effect of wormwood isn't what people expect it to be.\n\nIn general, from what I remember, alcohol has to do with the GABA brain receptor, which Benzo's also use. I'm trying to logically guess that it has something to do with motor functions, but it's been a while since I read up on it.\n\nI'll let this post serve as a placeholder since I'm not an expert. Just some basic background in psychology/biopsych."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
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|
3uf283
|
WW2 in the Pacific - How did the US not notice an entire Japanese battlegroup transiting the Pacific?
|
It is difficult to research this question due to conspiracy theories.
When I was in the Navy on submarines, we used to get daily reports on the order of battle for major ships of foreign militaries (mostly China) in the Pacific. That daily report would often show submarines, cruisers, etc... and where they were, including whether or not they were in port.
Looking back towards WW2, I know naval intelligence was nowhere near what it is today, but how in the world did that group of Japanese ships manage to transit the entire Pacific under the noses of the US Navy?
The reason I ask is that the popular conspiracy myth that they "knew" and "allowed" the attack to happen absurdly assumes that the supposed reports of Japanese ships the day before the attack on Pearl Harbor were ignored, or at best, taken as a nonissue.
Taking into account Japan's hostile actions in China prior to the attack on Pearl Harbor, it seems to me that the movements of their fleet would be something high on the list of naval intelligence collection requirements at the time.
If the Japanese group of ships were traveling at 20 knots and covering the ~3,850 miles from Japan to Hawaii, it would take 6.97 days to complete the transit. Assuming that after 2 days of transit, plotting the course of the Japanese group would point towards Hawaii fairly clearly. That would leave 4 days. I understand that in terms of war time frames, 4 days is very short, but it is still surprising to me that they were able to transit all the way to Hawaii undetected.
Am I missing something here? It just seems that the movement of a naval force by a country at war, Japan, would have been of great interest.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3uf283/ww2_in_the_pacific_how_did_the_us_not_notice_an/
|
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"The Kido Butai was Radio Silent with stations at major fleet bases in Japan using the call signs of the units involved, essentially were portrayed to either be in port or training in the Sea of Japan. The seamanship required for the transit is actually very impressive, as the fleet then had to meet with their oilers to refuel halfway there in the middle of the North Pacific and had to do so without radio usage.\n\nAnd at that point USN SIGINT was just starting to get a grip on the Japanese naval codes, and one of the first things fixed were the ship/squadron/admiral identifiers, so you can then triangulate where the source is.\n\nBut once the ships set sail the vast majority of traffic just STOPPED. The level of traffic was incredibly reduced, and Kimmel was told of it by his staff, but frankly the more likely targets to everyone were the Philippines, or points South, not 2/3 of the way across the Pacific. Though this Quote is very perceptive by Kimmel:\n\n > “Do you mean to say,” Kimmel asked Layton on December 2, “they could be rounding Diamond Head [an Oahu landmark] and you wouldn’t know it?”\n\n > “I hope they would have been spotted before now,” Layton said. \n\nThen as you can see on the map below the track took them WELL outside scouting range into the most barren open expanse of water on earth in the North Pacific.\n\n_URL_0_\n\n_URL_1_"
]
}
|
[] |
[] |
[
[
"https://upload.wikimedia.org/wikipedia/commons/0/05/PearlHarborCarrierChart.jpg",
"http://www.nationalgeographic.com/pearlharbor/ngbeyond/stories/story4.html"
]
] |
|
2nzzwy
|
Why is throwing pies depicted as such a fundamental part of early comedy?
|
I know this is sort of an odd question, but I'm curious as to why a pie to the face is so closely tied to comedy, specifically to clowns.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2nzzwy/why_is_throwing_pies_depicted_as_such_a/
|
{
"a_id": [
"cmjra1g"
],
"score": [
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"text": [
"The story is that the first pie was thrown as an impromptu action between actors in 1913. A top exec at Keystone Studio happened to see it, liked it, and pie throwing became a signature of their movies.\n\n[history](_URL_0_)\n\nOf course, once one studio has a great bit then other studios will copy and expand on it. Soon just throwing one pie wasn't enough. Each studio tried to top others with more involved pie mayhem."
]
}
|
[] |
[] |
[
[
"http://www.clowningbybuster.com/piespart4.html"
]
] |
|
116uko
|
is white a color? is black a color? is grey a color?
|
I don't really get why white should not be a color. People say it is to be explained with light. However, get a black piece of paper in a lighted room. Get a white pencil and draw a circle. Now you have a white circle. Do the same experiment with the lights out (In a dark room). The circle will still be white and identical in color as the circle drawn in the lighted room. So why is white still not a color?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/116uko/is_white_a_color_is_black_a_color_is_grey_a_color/
|
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"text": [
"There are three approaches to this. One is from artist point of view, where \"white\" is a background of a piece of paper. White = place where there is no paint, a clear area.\n\nOther is from physics point of view. Colour is light, white is mix of lights, but black is no light at all. From this point of view, there is no black light, so you could argue that black colour is nothingness instead of colour. \n\nThere is a normal folk approach, where anything that has a name is considered a colour. White is a colour, green is a colour and black is a colour. You don't go to a shop saying you want shirt in the colour of nothingness - that would be pretentious. ",
"Ok, we'll start with a brief introduction to light and then basic color theory:\n\nEDIT: I should add this: the way we see things is based on reflection. Light comes from a source, like the sun or a light bulb, and is reflected off an object and into our eye, which is interpreted by the brain. \n\nWhite light, which is based on sunlight, is considered to be made of all colors in the spectrum. [Using a prism,](_URL_0_) one can break white light down into the spectrum, which you would recognize as a rainbow. Now, when you have a white piece of paper, the paper reflects almost all of those colors and so appears \"white.\" \n\nIf you have a black piece of paper, it absorbs almost all of the light that hits it. It is not truly black because it still reflects some of the light, otherwise you would not be able to see it. If you drew a white circle on the black paper, that circle would be reflecting most of the visible light that hits it, while the rest of the paper absorbs the light. In a completely dark room, you would not be able to see either the paper or the circle, since there is no visible light available to reflect off the surface. \n\nSo, back to the prism and color theory. Remember how the prism broke the sunlight into a rainbow? That's because all of those colors are in the white light. So when you see something that is 'white', what you're actually seeing is all the colors of the rainbow reflected from a surface at the same angle. When you see something that is 'black' or 'grey', what you're seeing is the same thing, except that the amount of those colors that gets reflected is less. So, in essence, white, black, and grey are not different colors but different levels of light. To go back to your piece of paper, what you would notice if you took the intensity of the lights from 100% down to 0% is that the white circle would gradually appear greyer on the black paper until it finally looked 'black' because there was no light for it to reflect. \n",
"Is it in a box of crayola crayons? \n\nThose wacky people and their wacky color names, oh boy. ",
"Color happens in the brain. Everything you see is a color."
]
}
|
[] |
[] |
[
[],
[
"http://apollo.lsc.vsc.edu/classes/met130/notes/chapter19/graphics/prism.jpg"
],
[],
[]
] |
|
1sqvno
|
Are electromagnetic waves completely different from photons? I don't understand their connection.
|
Visible light is a portion of the electromagnetic spectrum. Why does sunlight not exhibit the properties of electricity and magnetism?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1sqvno/are_electromagnetic_waves_completely_different/
|
{
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"ce0ezim"
],
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"text": [
"The photon is the quantum of electromagnetic radiation.\n\nThat means that any electromagnetic wave you measure will have energy corresponding to a whole number of photons. Note that the energy per photon increases for higher frequency radiation, so that radio frequency waves (for example) are much more finely quantized than visible light waves.\n\n > Why does sunlight not exhibit the properties of electricity and magnetism?\n\nIt does. For example, both light and radio waves are refracted in the same way at a dielectric interface. \n\nWe can also see interference phenomena with both radio and light waves. We could set up a [double slit experiment](_URL_0_) with either radio or light and see similar interference patterns at the output (scaled according to the wavelengths of the two sources).\n\nBut because of the high frequency, the optical radiation effects can be qualitatively different than for lower-frequency em. For example, you can't use a metal wire as an antenna to collect visible light. "
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Double-slit_experiment"
]
] |
|
s1ff4
|
The average lifespan of an adult monarch butterfly is 2-6 weeks. However, during migration one generation has a lifespan of up to 8 months. What allows this?
|
askscience
|
http://www.reddit.com/r/askscience/comments/s1ff4/the_average_lifespan_of_an_adult_monarch/
|
{
"a_id": [
"c4ahc2a"
],
"score": [
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],
"text": [
"It appears to be due to [Diapause](_URL_1_)\n\nAnd you probably read about [monarch butterflies](_URL_0_).\n\nFrom what I've read on wikipedia it seems that the generation that begins the move enters diapause. Thus removing the daily need for procreation upon reaching a more habitable place in which they resume mating.\n\nHopefully someone with more knowledge about butterflies can answer this better. "
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Monarch_butterfly",
"http://en.wikipedia.org/wiki/Diapause"
]
] |
||
f7qw48
|
In what ways did the nazi's break rules?
|
This might sound like a f*cked up question, I'm not asking if what they did was morally good or bad, because we all know it's bad
But on a justice point of view, did they break a lot of rules? I'm thinking the law of Geneva and the hague , but any other international laws of that time aswell
I have no clue what kind of rules their were, and I wanted to see if they broke a lot of rules. If they did, also prewar? Because couldn't outside forces prevent all of it?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/f7qw48/in_what_ways_did_the_nazis_break_rules/
|
{
"a_id": [
"fidtznu"
],
"score": [
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],
"text": [
"While more can always be said, you can find a long discussion from multiple users of the question of how the regime was dealt with from the [perspective of international law here](_URL_2_), as well as discussion of the specific legalities of the Holocaust byu/kieslowskifan [here](_URL_1_) and u/commiespaceinvader [here](_URL_0_) (see also their answer [here](_URL_3_) on the rule of law under Nazism)."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/5vbw84/was_the_holocaust_technically_murder/?st=jios4hxi&sh=dbd86c50",
"https://www.reddit.com/r/AskHistorians/comments/8stosg/on_the_legality_of_the_holocaust/",
"https://www.reddit.com/r/AskHistorians/comments/95gfle/law_is_usually_not_retroactive_and_it_is_often/",
"https://www.reddit.com/r/AskHistorians/comments/4h2rnc/was_hitler_subject_to_rule_of_law/d2n45f1/"
]
] |
|
33lxuf
|
How can we see/measure things smaller than an electron microscope?
|
According to [this scale](_URL_0_), helium and hydrogen are smaller than the smallest thing an electron microscope can see, as are protons, neutrons, nuclei, and electrons. How do we know the sizes of those things, and other very small objects? Do we have something that can see smaller than an electron microscope can, or do we just have to estimate these things?
|
askscience
|
http://www.reddit.com/r/askscience/comments/33lxuf/how_can_we_seemeasure_things_smaller_than_an/
|
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"There are a few techniques that allow us to see things smaller than an SEM. One is a Scanning Tunneling Microscope:\n\n_URL_0_\n\nIt produces an image by measuring the tunneling current of electrons between a tip and a sample, which is dependent on a few things, one of which is distance to the sample. An STM can be used to image individual molecules, atomic orbitals and atoms. \n\nAn STM can also be used to move single atoms around by applying appropriate voltages between the STM tip and the surface. This is a super cool video IBM made using this technique which is composed of STM images of single atoms:\n\n_URL_1_",
"It's impossible to image things that small. The problem with imaging, at least in the strictest sense is that we need a probe wave that is adsorbed or reflected by the target and from these patterns we make an image. However, the maximum resolution that can be attained is determined by the wavelength of the probe wave and shorter wavelengths imply higher energies. But as the energy of light or electrons is increased their interaction with matter decreases and foccussing becomes more and more difficult. There are a few ways to get around this, particularely by using heavier particles (see for example the [Helium microscope](_URL_1_) which uses helium nuclei instead of electrons), but even then the maximum increase possible is only one or two orders of magnitude.\n\nIn order to get information about smaller structures one has to go to other methods. There are a few methods that are relatively similar to normal microscopy in the sense that they produce \"images\" usually by feeling the force that a molecule exerts on a tip (AFM), or the current that flows between a tip and the surface, which increases as you put a molecule in between (STM). These tip probe microscopes can give you image-like pictures with sub-molecular resolution but that's where it stops. They cannot actually probe inside a molecule or atom, let alone image a nucleus. For that, more radical deviations of the classical microscope are needed. \n\nThere are a variety of techniques availible to probe deeper into matter, but the one technique that's most relevant and generally applicable is the diffraction technique. It's the oldest of the two, much older than electron microscopy even and it's one of the workhorses of physics. In a diffraction experiment, a beam of radiation (light, electrons, neutrons, helium atoms or even buckyballs if you want to be fancy) interacts with a target. A part of the beam is diffracted, it's direction changes because of interaction with the electrons and nuclei in the target. The details of this process depend strongly on the radiation used and on the propperties of the target and as a result of that there are many, many things that can be studied by diffraction. However, all diffraction techniques take advantage of the fact that the scatterers can be much smaller than the probe beam (as long as the distance between them is larger than the wavelength) and from the fact that one doesn't need to focus the beam in any way. Using diffraction techniques we can get information about the inner structure of atoms, nuclei and even the [inner structure of protons and neutrons](_URL_2_). However, the information obtained from diffraction and scattering experiment is incomplete, a fact often called the [phase problem](_URL_0_). In principle, if we do the maths, there is a very easy relationship between the structure we're probing and the light that's diffracted; they're related via a Fourier transform. However, we can only measure the intensity of the light, not it's phase and therefor we lose part of the information. The only sollution is to try to correctly guess the phase and see if it gives results that are consistent with what one would expect from theory. So to answer your question, we know more than just guesses, but it still involves quite some input from intuition and theory.",
"One thing that has been mentioned on this sub in the past when questions like this come up is the following - with microscopy, the scattered light is *physically* refocused by the lenses, but with scattering techniques that involve highly energetic particles/photons that are used to probe matter at very small length scales, the 'refocusing' is computational in nature when one examines the scattering data. For example, at the [LHC](_URL_0_), most of the scattering are proton-proton collisions, with some proton-heavy ion collisions as well (at least according to Wikipedia - we'll see if this post gets any of the /r/askscience CERN cognoscenti to pop in with a comment). "
]
}
|
[] |
[
"http://htwins.net/scale2/"
] |
[
[
"http://en.wikipedia.org/wiki/Scanning_tunneling_microscope",
"http://www.research.ibm.com/articles/madewithatoms.shtml#fbid=YuCkdFezcuQ"
],
[
"http://en.wikipedia.org/wiki/Phase_problem",
"http://en.wikipedia.org/wiki/Scanning_Helium_Ion_Microscope",
"http://en.wikipedia.org/wiki/Deep_inelastic_scattering"
],
[
"http://en.wikipedia.org/wiki/Large_Hadron_Collider"
]
] |
|
89gugy
|
A lot of common English names (James, John, Michael) are English versions of biblical names. When did such names become common in English? Did the Anglo-Saxons use such names immediately after conversion, or were these names adopted more lately?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/89gugy/a_lot_of_common_english_names_james_john_michael/
|
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"Even for centuries after Christianization, Old English (Anglo-Saxon, pre-Conquest) still kept on pretty much using Germanic names. A common form was two-part names: choose your first part from Column Protheme and your second part from Column Deuterotheme. (Some name elements could appear in both places; some elements appeared in only one position.) Examples: Eadwulf (\"prosperity wolf\", by the way), Wigfrith (\"war peace\"), Leofstan (\"dear stone\"). There were uncompounded Germanic names too (Bubba, Ragge).\n\nFor a sampling, you can see Sara L. Uckelman, \"The Names of Testators in the *Cartularium Saxonicum Malmesburiensem*\", _URL_0_ . The only Christian name I see is Daniel, and the bithematic names are rampant.\n\nThe Old English name stock got thoroughly whacked at the Norman Conquest, especially in the aristocracy. Few such names survived, and they tended to be saints (like Hilda, Edward) or Wessex kings (like Alfred, Edward). The Normans came from the Norse some time back, so many Germanic-origin names came across with them (like Richard, Robert), and some Latin-based names or Breton-based names (like Alan).\n\nFor a small sample, there are 20 Normans known to have been at the side of William the Bastard / Conqueror in 1066: William Addams Reitwiesner, \"Normans at the Battle of Hastings\", _URL_1_ . I see nary a New Testament / saint's name in there, unless there was already a Saint William or Saint Richard, which seems likely.\n\nThe Church (or popular piety?) later began to gain influence in naming, though it wasn't until the Council of Trent much later (1500s) that the Church *required* saint's names as given names. For example, James and Michael aren't attested in England until the late 1100s, John appears once in Domesday Book in 1086 and is only at 2% in the late 1100s. In women's names, Mary, Anne, Elizabeth, and others of the common female saints don't come in until around 1200 either, though Germanic names for women quickly got stomped out.\n\nFor a larger sample, Brian M. Scott, \"Men's Given Names from Early 13th Century England\", _URL_3_ . (The introduction gives the source: \"custumals of 21 manors held by the Abbey of Bec\".) John is up to #3, Thomas is at #8, a cluster starts from Adam at #12 downwards, but that's 3.2% or less, and (for example) Osbert and Randolph are still beating Andrew and Benedict.\n\nCompare with Brian M. Scott, \"Yorkshire Masculine Names from 1379\", _URL_2_ (from tax rolls). John is in a comfortable lead, and Thomas is #3, and Adam is #6, though a lot of Norman-based names are up there too.\n\nNote, however, that the Christian-based names then were mostly New Testament (Michael does appear in Apocalypse / Revelations) or saints that might not be from scripture (Agnes, Martin, Christian). Not to say that the Old Testament was left alone: Adam and Abraham were in Domesday Book, for example. It was around the Reformation that Old Testament names jumped in popularity and non-scriptural saints tended to decline.\n\nThe common name stock got thoroughly squeezed from the 13th C on. \"The five names Henry, John, Richard, Robert, William together accounted for 30 per cent. of recorded men's names in the 12th century, for 57 per cent. in the 13th C, and for 64 per cent. in the 14th century.\" In baptismal records from 1600-49, 50.5% of all males are baptised either William, John, or Thomas; 52% of all females are baptised either Elizabeth, Mary, or Anne. (Source for this quotation and in general above: E. G. Withycombe, *The Oxford Dicitonary of English Christian Names*. It's getting dated, and not to be relied on for non-English names, but for a broad-brush look at basic facts I believe it's still usable.)\n"
]
}
|
[] |
[] |
[
[
"http://www.ellipsis.cx/~liana/names/english/malmesbury-oe.html",
"https://www.s-gabriel.org/names/arval/hastings.html",
"https://www.s-gabriel.org/names/talan/yorkshire/yorkm.html",
"https://www.s-gabriel.org/names/talan/eng13/eng13m.html"
]
] |
||
1iexey
|
Do all proteins have a function?
|
Hi, I have a question about protein evolution and the existence of functionally redundant proteins. This question is based on a couple of assumptions which I will explain before I get to the question itself:
Firstly, that proteins with new functions often evolve from an existing protein with a different function.
Secondly, that a duplication of the DNA encoding the pre-existing 'original' protein often occurs, allowing the duplicated sequence to mutate and gain a new function without losing the function of the original protein.
Therefore my question is this:
If new proteins go through a 'redundant' phase before they gain a new, useful function, should we expect living organisms to express proteins which have not yet evolved a new function?
If so, what proportion of the genome might be dedicated to encoding proteins with redundant functions or with no real function at all?
I ask because we scientists always want to know what every single proteins does and I wonder if sometimes the answer is 'nothing useful'.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1iexey/do_all_proteins_have_a_function/
|
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"Being that over half of the human proteome is undefined, I believe the answer you will get to this question is that we don't know. \n\nConsider that *E. coli* has been the most well studied organism in microbiology, and yet a third of the ~4000 predicted proteins remain undefined and with unknown functions ([Hu et al. 2009](_URL_1_)).\n\nAlso consider that when research is done to describe the function of a protein, it is not always easily defined because the conditions that we do experiments may not reveal a protein's function. For example, the *lac* operon was discovered by changing the conditions of bacterial culture, allowing [Jacques Monod](_URL_0_) to visualize differences in growth and protein expression. While changing a sugar may be a relatively simple experiment, there are a near infinite number of conditions of metabolites that can be changed in a media. The possibilities are incredibly complex as bacteria can be in a liquid, on a surface, in any combination of sugars, salts, metals, compounds, peptides, and even other bacteria of the same or different species. And this is only with bacteria. \n\nEukaryotes have organelles that need to communicate within the cell to regulate functions within the cell. This is even more complex, with cross-talk between the nucleus and mitochondria, and chloroplasts in plant cells. Multicellular organisms must regulate and differentiate each cell. Intercellular and intracellular communication are absolutely essential to proper development and survival of the organism. And this communication is regulated primarily through peptides with difficult to define functions because we can only study one small part of an organism at a time. It is possible that some proteins are useless in a particular stage of an organism's lifetime, it is also likely that each protein has a purpose at some point in the organism's lifetime.\n\nTLDR, a lot of proteins have difficult to define functions.",
"That's a difficult question to answer without defining what we mean by \"function.\" Which is not so obvious. Or at least, is not easy to measure. I would say that the only biologically meaningful definition of function must be based on reproductive fitness, but even that is not enough to usefully define function, because fitness is always relative, and context dependent. I can delete hundreds of genes from *E. coli* without seeing a loss in fitness, as long as I grow them in rich broth at 37 C. It only gets more complicated as your organism and its interactions with its environment get more baroque. \n\nEvery protein does *something,* even if it's just sticking to things or affecting the osmolarity of its environment. Any peptide chain has dozens to thousands of chemically reactive side chains hanging off it, giving all sorts of opportunities for weak catalytic effects. \n\nSo how do we decide if a protein is truly 'functional'? For a given environment, the straightforward answer is look for mutants and see if they have a phenotype, but that's a very limited answer, because we don't know whether a tiny environmental change would change our answer. Looking for enzymatic or biological activity is madness, given the millions of potential interactions you'd have to rule out. \n\nOne useful evolutionary answer is to look for natural selection on the sequence. The way we normally do that is look for a skewed ratio between synonymous and non-synonymous mutations. Of course this assumes that the only important sequence differences for function are non-synonymous mutations, and a paper just came out casting doubt on that assumption: _URL_0_ \nIn the context of gene duplications, I'd say that, as long as the duplicated gene retains all the transcriptional and regulatory context, there's no reason not to consider it just as 'functional' as the original copy. The interesting thing is that, once you have multiple copies of a gene, the selection landscape changes significantly, since no single mutation can knock out the function of that gene. I would still call each copy 'functional,' but you should probably see significantly more sequence polymorphisms. Eventually, it seems to me, you'd end up with a large portion of the population with knockout mutations in one or the other copy of the gene, and you're back to square one, only now you have this extra sequence that may or may not produce some sort of peptide sequence, which it might be reasonable to call 'functionless.' But, if a protein is truly functionless, how long will it remain a protein? Without selective pressure, over time the open reading frame and/or the promoter will be lost, and it will be merely functionless DNA or at best RNA. \n\nThere is also the possibility of new ORFs arising de novo from previously non-coding DNA, but it should be quite rare for such ORFs to spread throughout a population if they don't provide a selective advantage.\n\nAll in all, I'd say that any sequence that is conserved between species is likely to be functional in some form or fashion, especially if it shows signs of purifying selection. This might be less true in very small populations, where genetic drift is more powerful. And never forget environmental context; a protein may have been super useful for protecting us against some enemy that no longer exists, and thus in our current environment is, in some senses, not functional. Environmental changes can happen too quick for meaningful sequence evolution to occur, so such a protein might still show signs of selection. If the enemy returns soon, suddenly it's functional again. But as long as it's gone, evolution doesn't see the protein as functional, and given time, random mutations will destroy whatever activity rendered it functional in that past environment.\n\nThat was a bit rambling. Oh well. Sometimes I like to think by writing.\n\n",
"Part of the problem we have with proteins is that for the vast majority of them we don't even know what they look like let alone what their function is. \n\nMuch of the data we have so far is on their sequencing, but it is difficult to predict from this what shape they will take when they fold and subsequently we don't know what their active sites look like. This data is usually collected by x-ray diffraction patterns or other similar techniques, but these can not be applied to all proteins. \n\nMore recently people are turning to computer simulations to help bridge the gap of what a protein is made of and what it does. \n\nSo at the moment to say something is useless is rather hard since to say something is useless would imply we know everything about it. "
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Jacques_Monod",
"http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000096"
],
[
"http://blogs.discovermagazine.com/gnxp/2013/07/an-illusion-of-neutrality-and-synonymous-sites/"
],
[]
] |
|
34zhmo
|
how and why did tony hawk get so famous?
|
Besides doing the first 900 what made his fame skyrocket, and why he is now worth so much?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/34zhmo/eli5_how_and_why_did_tony_hawk_get_so_famous/
|
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"One of the pioneers in skateboarding he founded birdhouse skateboards and even into his mid 40's still participates in the skateboarding community. ",
"He won a lot of skateboarding competitions, had his name on a successful series of skateboarding based video games, and has been a media personality in general for a while. ",
"There's a biopic on Netflix call Bones brigade about a group of skateboarders who made the sport what it is today. Highly recommended if you want to know how he made it big",
"I think a lot of it was timing -- he was the biggest skating star at the time when skate culture was just beginning to be considered trendy in the mainstream media, and he capitalized on that. ",
"[Police Academy 4](_URL_0_) That role alone set him on his path to glory.",
"To the average person who has no real interest in skateboarding vert is normally far more appealing because of the high flying tricks that are done versus some of the technical stuff that gets done in Street skating. \n\nHe's also a legend that's been around since the bones brigade. \n\nRight time right place. Skate culture became trendy.\n\nThe xgames started around the same time. \n\nHe's also a competition skater and those guys tend to be more marketable. \n\nTony hawk pro skater was a fantastic game that appeals to all kinds of people. Even people who have never skated. ",
"My first board was a Tony Hawk Powell-Peralta. That was like 25 years ago. The dude is a legend. Besides being sponsored and all the merchandising that comes with it, he has been in movies, and got a piece of every video game with his name from Activision.\n\n[Read his Wikipedia article. It answers your question in more detail.](_URL_0_)"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[
"https://www.youtube.com/watch?v=gFS_QLfTC8U"
],
[],
[
"http://en.wikipedia.org/wiki/Tony_Hawk"
]
] |
|
2p6fku
|
If a flashlight was on and free floating in space would it accelerate?
|
Would the emission of photos push the flashlight at all?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2p6fku/if_a_flashlight_was_on_and_free_floating_in_space/
|
{
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"text": [
" > Would the emission of photos push the flashlight at all?\n\n**Short answer:** Yes. [Photons carry momentum, which would cause the flashlight to experience a force against the direction it was shining.](_URL_5_)\n\n**Long answer:** let's go an adventure. For a normal pocket flashlight powered by a single 1.5 Volt AA lithium battery, we can do an easy calculation. That battery has a mass of 15 g, and contains a total charge of 2700–3400 mAh (that's milliAmp hours) which gives 5.10 Wh (watt hours) of energy. \n\nLet's assume that this thing operates at 100% efficiency. This actually isn't a bad estimate. Not much energy gets lost to heat in the circuit if we have a good LED, and the bit that does get lost to heat will probably find an easier to time radiating from the front, because the forward facing part dominates the angular part of the space that it could be radiating into and the material probably isn't as thick. Anyway, it puts out: \n\n E = 5.10 Watt-hours = 18360 Joules\n\n[This is comparable to the detonation of ~4 gram of TNT.](_URL_2_) I did some googling to try and find the explosive power of various fireworks to give you a sense of how much this is, but that information doesn't seem readily available. I only seem to have found myself on a government watchlist now for lots of google searches about the explosive power of fireworks. Fortunately, this is America, so information about [gunpowder](_URL_0_) is readily available, which has about 70% the energy density of TNT. Some useful conversation from *grains* to grams tells us that 4 grams of TNT contains about as much energy as [sixteen 9mm cartridges worth of gunpowder.](_URL_4_) It's a good thing our flashlight isn't releasing all this energy at once. Into a bullet. Actually, that's a shame, because that sounds really cool.\n\nAnyyywaaaay, if we calculate the momentum of the photons with this energy, we find \n\n\n p = E/c = 18360 J/(3.0x10^8 m/s) = 6.12x10^(-5) kg m/s\n\nwhich is the total momentum of an entire AA battery's worth of pocket flashlight light. So now, your pocket flashlight has that much momentum going backwards. If your flashlight weighs 30 g (so half the mass is in the casing and elecrotonics, and the other half is in the battery), then: \n\n v = p / m = 6.12x10^(-5) kg m/s / (0.030 kg) = 0.002 m/s\n\nThat's slow. [Coincidentally, it's also almost exactly equal to the World Record for the fastest snail in the Congham, UK.](_URL_3_) No, I don't know if the record for the fastest snail in the world was set in Congham, or if this is a local Congham record. Anyway...\n\nSo to find your acceleration, we need to know how long it took for the battery to run dead. I know my flashlight dies if I leave it on in my pocket over night, but it certainly can get me through a weekend of camping on one battery (provided I don't leave it on in my pocket the first night), so let's say it has 8 hours of juice. \n\nIn that case, the acceleration can be found by:\n\n a = dv/dt = (0.002 m/s) / (8x3600 s) = 6.94x10^(-8) m/s^2\n\nThat's also small. As fuck. It's so small that [the Wikipedia page doesn't even give us a sense of how small it is.](_URL_6_) If we multiply our 30 grams back in, we find the force, which is about 10^(-9) Newtons, [which is about the amount of force needed to break a covalent bond.](_URL_1_) If I haven't hit this point home hard enough yet, that's small. Really really fucking small. So maybe, if you hitch your flashlight like a tugboat to one of those lithium ions from that battery, you might just be able to pull it apart. ",
"If you're interested scaling the flashlight up a little, you can check out the idea of a [photon rocket](_URL_0_), which operates on the same principle.",
"I've seen no mention of it here, but the phenomenon known as [\"the Pioneer Anomoly\"](_URL_0_) has been proposed to be due to an actual case of radiation pressure sourced from a spacecraft producing unintended but measurable acceleration. Basically, the probe radiates heat unevenly throughout its structure and it shows up as a small net force that looks like something is nudging the craft in a particular direction. When the discrepancy in Pioneer's flight path was first noticed, people were very excited for a while wondering if there was some kind of new exotic thing on the verge of being discovered at the edge of the solar system. When first published, the radiation theory felt like a let down for some. But I thought it was riveting how those who came up with the idea went about trying to prove its plausibility.",
"Engineer here. Apologies if this has been brought up, but wouldn't the electrons moving across the battery in the flashlight present more of an opportunity to impart a force in deep space?\n\nHere are two situations:\n\nThe flashlight is switched on. Maybe some movement occurs from the radiation pressure. Electrons are moving across metal components, and a magnetic field is produced depending on the design of the flashlight, for example from a coiled filament within the bulb. Depending on the magnetic flux conditions in deep space, this could propel or spin the flashlight. However, is it possible for the electrons moving across metal components to exert a force?\n\nThe flashlight is switched off. So, opposing components inside the flashlight are at battery potential. This becomes a lens [like you'd see in an old vacuum tube](_URL_0_). Is there a flashlight design that deflects cosmic rays in such a way as to start spinning?\n\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Gunpowder",
"http://en.wikipedia.org/wiki/Orders_of_magnitude_%28force%29",
"http://en.wikipedia.org/wiki/Orders_of_magnitude_%28energy%29",
"http://en.wikipedia.org/wiki/Orders_of_magnitude_%28speed%29",
"http://en.allexperts.com/q/Guns-Firearms-Projectile-1501/2009/9/gunpowder-bullet.htm",
"http://en.wikipedia.org/wiki/Photon#Physical_properties",
"http://en.wikipedia.org/wiki/Orders_of_magnitude_%28acceleration%29"
],
[
"http://en.wikipedia.org/wiki/Photon_rocket"
],
[
"http://en.wikipedia.org/wiki/Pioneer_anomaly"
],
[
"http://www.vias.org/basicradio/basic_radio_22_02.html"
]
] |
|
hq84q
|
Could there be types of dimensions that are not space or time?
|
I'm not sure if this question even makes sense, but I was thinking about how we have four known dimensions in our universe, and three of those are classified as "space" and one is classified as "time". Could there be other "classifications" of dimensions?
|
askscience
|
http://www.reddit.com/r/askscience/comments/hq84q/could_there_be_types_of_dimensions_that_are_not/
|
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"text": [
"The concept of \"dimension\" actually isn't that restrictive at all. In mathematical terms, a dimension is simply a degree of freedom of a system; a value which can vary if all others are held constant. You could reasonably describe electric field, for instance, as being a dimension.\n\nSo why do we talk about the universe having three spatial dimensions and one temporal dimension? Because we already treat spatial dimensions as especially important, and it turns out you can't separate out time from space very easily. They're geometrically related, meaning you can't just put time \"on top\" of space like you can other things.",
"No. A timelike dimension has a negative coefficient in the metric, and a spacelike dimension has a positive coefficient (using a mostly positive signature). You could have a dimension with zero coefficient, but then it wouldn't really be a dimension in a meaningful way.",
"Physical, no.\n\nBut in math dimensions are abstract, and they can be anything you want. A good example is a computer screen, the image you see is stored in 5 dimension: two space dimensions, and three color dimensions.",
"Supersymmetry describes such a dimension."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
1k7te8
|
what is democratic socialism, how does it work, is it possible/feasible?
|
I'm not the smartest person in the world so please put as much detail in it as you can.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1k7te8/eli5_what_is_democratic_socialism_how_does_it/
|
{
"a_id": [
"cbm9jw4"
],
"score": [
3
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"text": [
"Socialism in general is a broad range of ideas, which can be applied in many different ways. At its core, socialism is just an economic philosophy based on the principals of need-based production for the purpose of meeting physical economic demands rather than gaining profits. In other words, a shoe company produces shoes based on how many people need new shoes, not based on how much money people are willing to spend on the shoe industry. \n\nAs for democratic socialism, this is just the application of democratic methods to achieve socialism. You could overthrow your government and put in a new, centralized government in charge of regulating production and distribution of goods, or you can gradually elect and vote socialist ideals into play. The latter is domocratic socialism. The end goal of democratic socialism is to put economic power in the hands of the stakeholders (the people, as they are most affected by the economy) rather than the shareholders (people who invest money or own businesses) as in capitalist societies, and not into the hands of a centralized authority such as a government. Proponents of democratic socialism believe that the use of democracy to shift away from capitalism is the best way to keep the power in the hands of the people supporting the change.\n\nI'll let someone else get into the details of if it is possible/feasible and how well it works or can work."
]
}
|
[] |
[] |
[
[]
] |
|
1cu5ic
|
Why are squid and octupus red?
|
Now, I know not all Cephalopods are red, but it seems that alot which are shown in TV are red or orange. Giant squid, Pacific octupus, humbolt squid, all are red (at least most of the time, I know they change colors). So what evolutionary advantage is there in being red? Or is it just one of those "that's just how they evolved" kinda thing? Or is I some media bias?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1cu5ic/why_are_squid_and_octupus_red/
|
{
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"c9kc6ne"
],
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"text": [
"Well, obviously there is the chance that they turn red as a threat because every time we see them they think we are a threat.\n\nBut another reason is to do with the way light travels through water. The deeper you go the the fewer colours you can see, the first one that goes is red. That is why many things at the bottom of them photosynthetic zone appear to be red. This gives them camouflage, if there is no red light you can't see something thats red, which leads me onto my next point.\n\nAlso colours do have an evolutionary role to play which is related to the way in which light travels through water. Many fish for example have different coloured tops to bottoms so that they are just as camouflaged if a predator sees them from above than if they are seen from below. As some Cephalopods frequent reefs and rock formations having this colour camo to protect them from predators looking down on them is a good thing as they blend into the reef or rock."
]
}
|
[] |
[] |
[
[]
] |
|
qhc1m
|
tv settings such as brightness vs contrast and sharpness.
|
Edit: A brief explanation on each setting such as tint, brightness, color, etc. Thanks!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/qhc1m/eli5_tv_settings_such_as_brightness_vs_contrast/
|
{
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"text": [
"Brightness is how much light the screen is putting out, contrast is the difference between the brightest parts of the screen and the darkest.",
" Many of the names of the settings come from the way old, CRT tv's worked. Sharpness dealt with the focus of the beam of electrons in the picture tube, but with new flat screens, the pixels are fixed in size and location. Tint would be related to the color (hue) of the image. Pictures on screen are made from blue, green, and red lights, so if the balance gets off, you get an image that is tinted blue or green or yellow or whatever. In old tv's the colors were tuned by separate parts, so they needed to be calibrated. ",
"In your typical LCD or plasma, it goes something like this:\n\n* Brightness - black level, this controls how dark the pixels go for \"black\" parts of the signal. You want to set this so full black becomes the darkest black your display can put out, and no lower. If its too low, things slightly above black (ex, RGB 15-15-15) will be displayed as black as well, and this will \"crush out\" shadow detail. \n\n* Confusingly, LCDs also have a backlight. This is sometimes labeled brightness as well, and its always a bit of a game to see if \"brightness\" controls the black level or backlight unless there is obviously another control called \"backlight\" or something. The backlight brightness can be adjusted to taste, although lower levels will be more impressive in a dark room, and it's generally set very high from the factory. You get darker blacks with lower backlight levels, since there is less light for the LCD to filter out.\n\n* Contrast/Picture - white level, basically the opposite, how bright full white is represented. You set this so full white is the brightest white your display can put out. If you set this too high, light colors will be crushed to white.\n\n* Color is usually just a saturation control, although nicer displays will have separate red, green, and blue controls. RGB is probably not exactly balanced internally, so usually cranking this up will overblow some color (it's usually red)\n\n* Color temperature deals with the RGB balance, it's what color \"grey\" is defined as. There are a couple of different possible settings, but you want to set it to 6500K/D65. This is because video is produced with the expectation that you used this setting. Your TV is probably set colder than this, since bright blue is eye catching in the store. If your TV doesn't mention what temp the settings really are (ex, cool2, cool1, normal, warm1, warm2) change it to the warmest setting, that is almost always 6500K. If your TV has warm1 and warm2, it's possible that 6500K is warm1, and warm2 is something overly warm. You can often find out the proper setting with a bit of googling for a reviewer or home theater fan who checked it with a meter. But seriously, it's probably \"warm\" or \"warm2\" if you have two \"warm\" settings.\n\n* Tint is a green/red balance, leave this at 0/centered, you'll need at the very least filter glasses and a test pattern to set this correctly.\n\n* Sharpness nowadays is just an edge enhancement/blur effect. Find the setting that disables it, usually either 0 or halfway point (check your manual, not all TVs have the blur/negative sharpness feature, but some do)\n\n\nHelpful links:\n_URL_1_\n_URL_2_\n_URL_0_"
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.pcworld.com/article/148462/how_to_calibrate_your_hdtv.html",
"http://www.lagom.nl/lcd-test/",
"http://www.audioholics.com/tweaks/calibrate-your-system/basic-television-setup-tips"
]
] |
|
2obgbt
|
how do the space ships designed to transport humans to the moon or mars relaunch from those places to return to earth?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2obgbt/eli5_how_do_the_space_ships_designed_to_transport/
|
{
"a_id": [
"cmliz7z"
],
"score": [
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"text": [
"As of right now there's only ever been craft to take humans to the moon.\n\nIt landed with the engine pointed down already. It simply activated them to take off again."
]
}
|
[] |
[] |
[
[]
] |
||
86x34n
|
what's the difference between the nyse and the nasdaq?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/86x34n/eli5_whats_the_difference_between_the_nyse_and/
|
{
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"text": [
"Both are stock exchanges (marketplaces for investing in companies) operated by two different competing companies. They do roughly the same things, but historically they were very different. NYSE traded mostly in person while NASDAQ traded mostly online; and NASDAQ specialized in tech companies (still does to some degree).",
"Both NASDAQ and the NYSE are [securities exchanges](_URL_2_). That means companies that meet the listing standards are able to list their stock on them to be traded.\n\n* [NASDAQ was started in 1971 to be an electronic stock exchange.](_URL_0_) As a result, it was marketed to be cutting edge and appealed mostly to tech companies. \n\n* The NYSE is older, [founded in 1792](_URL_1_), so a lot of older, established \"blue chip\" companies are listed on it. Tech companies are still able to list on it, but because many tech companies are already listed on the NASDAQ, they often choose to list there instead. \n\nIt should also be noted that many companies can find it more cost effective to list on one exchange over another, but it really depends on a number of factors.",
"The are the Coca-Cola and Pepsi of stock exchanges in the U.S. There are some other smaller exchanges like Chicago and Philadelphia, but the VAST majority of stocks are traded on the NYSE or NASDAQ.\n\nThe NYSE was the largest, most prestigious exchange, and the NASDAQ used to be more of a second-tier exchange with smaller, younger companies in areas like tech and pharmaceuticals... but as tech and healthcare have surged in importance and company scale, the NASDAQ has become an equal peer of the NYSE."
]
}
|
[] |
[] |
[
[],
[
"https://www.loc.gov/rr/business/amex/amex.html",
"https://www.loc.gov/rr/business/hottopic/stock_market.html",
"https://www.sec.gov/answers/about-lawsshtml.html#secexact1934"
],
[]
] |
||
b7diz3
|
how do open world games go without interstitial loading screens?
|
So if you’re playing a typical non-open world game, every time you lose a life or enter a new area, you have to sit through a couple minutes of loading screens. How do open world games circumvent this, to create a seamless experience as you transition from one area to the next? Is an open world game continually “streaming” data off the disc/hard drive/cartridge and dumping unneeded assets from RAM on the fly?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b7diz3/eli5_how_do_open_world_games_go_without/
|
{
"a_id": [
"ejqx8z8"
],
"score": [
4
],
"text": [
"Yes, that's exactly what it is doing. The open world is split in to sections, and only the section the player is close to is loaded. You notice if you die in open world games it will take a bit of time to load the area you respawn in. "
]
}
|
[] |
[] |
[
[]
] |
|
4bchpr
|
During the whaling period, how common was it for whales for strike back against fishermen?
|
I recently saw the film "In the Heart of the Sea" (i rather enjoyed it by the way despite the bad reviews) and currently reading the book it was based on. I really was surprised to learn that Moby Dick was inspired by an actual event. The thought of a whale being intelligent enough to attack/hunt a whaling mother ship seems implausible to me but perhaps I'm underestimating the intelligence of sperm whales. Was this an isolated event in history, or have their been other instances of whales being vengeful and striking back against their captors? Today it doesn't seem like whales strike back against humans and ships at all save for incidents in water parks by Orca whales.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4bchpr/during_the_whaling_period_how_common_was_it_for/
|
{
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],
"text": [
"The whaleship *Ann Alexander* is the only other notable \"deliberate sinking\" by a sperm whale, to my recollection, in 1851. \n\nYour use of the terms 'vengeful' and 'hunt' are sort of controversial. They give the whales an agency that we are totally not agreed on. Sperm whales are without a doubt an intelligent species, but to apply our human concepts of things like revenge might be a bit misleading. At the end of it, the only accounts we have are of the whalers who survived the incident, and it's not too far to suggest that sailor stories and human recollection can border on exaggerating details. Our scientific studies of sperm whales can offer a number of explanations for the sinkings of *Essex* and *Ann Alexander*. These sort of discussions exit the realm of the historical and more into the scientific, so I'm not sure how far we can get into it before it violates AskHistorians' parameters.\n\nHope this helps!"
]
}
|
[] |
[] |
[
[]
] |
|
8d2r30
|
Book about the Night of The Long Knives
|
Any recommendations of books that expand on Hitlers purge of Ernst Röhm and the SA?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8d2r30/book_about_the_night_of_the_long_knives/
|
{
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"dxkk2i8"
],
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3
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"text": [
"Unfortunately, there are not a lot of good English-language books on the Blood Purge itself; most accounts tend to be pop history-ish. There is a very good German-language book written by the journalist Heinz Höhne, *Mordsache Röhm: Hitlers Durchbruch zur Alleinherrschaft 1933–1934*. If you dig through some of the citations of Kershaw or Evans on the Purge, you'll usually find citations to Höhne's book. There is a very good recent book on the SA itself, *Stormtroopers: A New History of Hitler's Brownshirts* by Daniel Siemens, and its chapter on the Röhm affair is quite good. [Eleanor Hancock's](_URL_0_) corpus of work is also quite useful for contextualizing the Purge, especially her biography of Röhm and articles like \"'The Purge of the SA Reconsidered: 'An Old Putschist Trick\"?\". "
]
}
|
[] |
[] |
[
[
"https://www.unsw.adfa.edu.au/school-of-humanities-and-social-sciences/associate-professor-eleanor-hancock#quickset-people2"
]
] |
|
2qz1xe
|
During the first nuclear bomb test, how did they know how far away to observe the blast? Did they already know how many tons of TNT (or TJ) it was?
|
I tried some google-fu, but nothing showed up. How did the scientists that made the bomb know where to place their observation cameras and bunkers? From what I've seen they were fairly close enough to the blast to see it without using binoculars or other things. There were bunkers 10,000 yards away and observation things 20 miles away.
I also read that there was a betting pool as to how many tons of TNT or TJ the blast would be.
Is there a way to figure this out mathematically? (the TJ and distance of the blast wave)
|
askscience
|
http://www.reddit.com/r/askscience/comments/2qz1xe/during_the_first_nuclear_bomb_test_how_did_they/
|
{
"a_id": [
"cnavih0"
],
"score": [
154
],
"text": [
"The question of how large a nuclear blast can be is a function of the total energy release possible multiplied by the expected efficiency of the weapon. \n\nSo in the case of the first nuclear weapon, they knew that it contained 6.2 kg of plutonium. 1 kg of plutonium, completely fissioned, releases 18 kt or so of energy. So the absolute upper bound is around 112 kilotons. \n\nBut they also knew their method was not going to be very efficient. The \"safe\" estimate was that it would release about 5 kilotons worth of energy — an efficiency of only about 5% (that is, only about .28 kg of plutonium would fission, in a weapon that had 6.2 kg of plutonium in it). The most optimistic estimates (e.g. in the betting pool) was around 50 kilotons — an efficiency of 45%. But this was unusual — most thought it would be lower, maybe even less than a kiloton. \n\nIn reality, it was around 20 kilotons, which is an efficiency of about 18%, which is considerably higher than the \"safe\" guess (4X more). \n\nThey had a pretty OK idea of how the blast wave would react at different distances and kept anything really sensitive well outside of those distances. They were aided in the fact that damage does not scale linearly with increase of explosive yield: because the explosive energy is released as a sphere, it scales as a cubic root. To put this simply, in order to double the area of destruction, you have to increase the yield by a factor of eight (so a 8 kt bomb destroys twice the area of a 1 kt bomb). So just because it was 4X more energetic than they predicted, that did not mean they had to be 4X as far away to be safe. \n\nThere were many uncertainties, however. They tried to keep things as safe as they could under the circumstances, but there were many unknowns. They kept all personnel at comfortably safe distances, and tracked the spread of radioactive fallout. They even prepared for grim eventualities such as people accidentally dying during the test (which sounds fanciful, but it is worth noting that during several Soviet nuclear weapons tests there were inadvertent deaths due to unusual unanticipated phenomena, such as reflection of blast waves off of inversion layers in the atmosphere)."
]
}
|
[] |
[] |
[
[]
] |
|
3ed5jz
|
why do cereal and juice boxes all have "color swatches" under the tabs?
|
[This is an example of what I mean.](_URL_0_)
& nbsp;
They're also under the rims of coffee cups and not always the printer ink "CYMK" format. Sometimes it will be like 5 shades of the same purple color if the image on the box is just purple.
Do companies have to print swatches on the each box for some legal reason? I can't imagine it would be efficient/useful for the company itself, but I also can't imagine why the FDA would want color swatches on all the boxes and stuff.
edit: format
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3ed5jz/eli5_why_do_cereal_and_juice_boxes_all_have_color/
|
{
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5,
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2
],
"text": [
"They're to verify the printing. If the blue on that swatch is faded then you know the rest of the blue on the box is faded. If the crosshairs are misaligned then you know the box art is misaligned.",
"They are used by the packaging company to control their printing process. It doesn't consume much ink, but offers a constant data point of how correct the color reproduction and printing alignment is.",
"The swatches are there so the pressman can adjust the plates on the printer. There is no legal requirements for them. ",
"As others have said it's there as a tool for the printers. Every item commercially printed would have them but things like books and magazines would have these marks on the areas that are guillotined off after binding so you wouldn't see them.",
"When these packages are printed through an Offset Printer, each color is printed independently. So, these **swatches** are basically a **tool** to check the colours when printed. With them, you can see if the cyan is darker than it should, or if the magenta is more reddish than it should.\n\nA **cool fact** is that you can know *how many* colours the printer used when printing the package. (In this case, 6 colours: the basic CMYK (**cyan**, **magenta**, **yellow** and **black**), and two *special colours*: **red** and **blue**)"
]
}
|
[] |
[
"http://i.imgur.com/j497Wyj.jpg"
] |
[
[],
[],
[],
[],
[]
] |
|
5l8foa
|
why do pro gamers retire in their early 20's? do your reflexes really drop so significantly that early in life?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5l8foa/eli5why_do_pro_gamers_retire_in_their_early_20s/
|
{
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"text": [
"It's more social pressures, really. There are some relatively old eSports players still at the top of their games. Polt is 28, Taz is 30. But most retire before then.\n\nSouth Korean players get a special mention here, as they always have the looming threat of mandatory military service. They can postpone it, but eventually they'll have to take it, and many would rather do it early than late.\n\neSports has gotten much bigger recently, but it's still new and much less stable than sports. And being a competitive player is an exhausting and stressful job. In many cases, prize pools still make up a good chunk of player's incomes. So you always have the stress to be the best.\n\nIn a normal day job, you're not at constant competition with your peers. If you don't \"perform\" well for a while, you don't get kicked from your team. You still get payed the same. \n\nEventually, people want to settle down.",
"For one thing, the games change.\n\nYou aren't a professional gamer...you are a professional DOTA 2 gamer or Starcraft 2 or League of Legends or whatever.\n\nAs new games emerge, prize money for the the older games shrinks, and there is no guarantee being a top player in one game will ensure success in another. If I were a 25 year old top Counterstrike pro with a bunch of prize money in the bank, I might be thinking about what I want to do for the next phase of my life. That's still young enough to go to college and go back to being a normal person with a nice nest egg in the bank.",
"One thing the other commenters haven't mentioned is health and burnout. Pro gamers work a grueling schedule: 12+ hour days, day after day, honing their skills. It's not a game to them; it's their job, so they can't just log off and do something else if they get bored. Many retiring players say that they do it because they want games to be *fun* again. \n\nAlso, carpal tunnel syndrome.",
"Several reasons:\n\n1) you don't really make that much money. Only top players make the big money. For every guy making over $100k a year, there are hundreds who don't. It's kind of like the acting industry. The top 1% of actors make huge money, the other 99% are broke. At some point these guys realize they will never be a top player and they can make more money doing something else.\n\n2) it not all fun and games, it is a job. These guys play the same game every day for 12+ hours a day to be as good as they are. Just imagine that. It would get real boring, really quickly. Also, they are not playing to have fun, they are playing to win. They only get paid when they win, so there is a lot of stress to win. Even if these guys are on contract with guaranteed pay, they are always at risk of losing that contract if their performance slips or if the team finds a better player to replace them.\n\n3) medical reasons. Yes, you read that correctly. Carpal tunnel syndrome is real and extremely painful. Using all those fine motor skills in the hand can actually damage the muscles and tendons in the hand. Our hands were not designed to use the fine motor muscle constantly for hours on end. Also, the pressure and constant stress to win takes a physical toll on the body.\n\n4) games change. Most professional gamers specialize in 1 or maybe 2 games. After a few years, and as new games come out, older games stop getting media coverage and the prize money for their tournaments drop. In some cases, tournaments cease to exist for that game and there is no more demand. If you are lucky, your chosen game will have several iterations (like Halo or COD) that only have minor changes as each new version comes out. If not, there is no guarantee that you will be as good at a different game.\n\n5) At some point, you want a normal life. You want to be able to date, get married, have kids, etc. You need a stable career and free time to do this.",
"As a pro gamer between 1999 and 2001, I can tell you my reasons (I was not even 20 at the time).\n\nThe pro gamer scene back then was nothing like the current. I just had fun with friends and even won the national tournaments hosted on my country for UT99, I was one of the best player back then. Prices were not even money, I didn't care for that.\n\nEventually, the videogame was relegated a lot (by CS, Q3 and SC) and most people lost interest. In 2002, under (understandable) pressure from my parents I started university, so that was it. I still play a lot, even more than 15 years ago, but for personal enjoyment.",
"I can confirm I had to give up gaming console entirely at 40...kids reflexes are just too fast"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[]
] |
||
9srb96
|
do we know how greek and latin were originally pronounced?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9srb96/eli5_do_we_know_how_greek_and_latin_were/
|
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"text": [
"While he isn’t referring specifically to Greek or Latin, Dr Jackson Crawford has several YouTube video about Old Norse and other Old or dead languages, and he explains in detail how we know what old languages sounded like based on certain modern characteristics and modern languages that may echo the old pronunciation, along with how we know that languages have changed over time. \n\nI would recommend that you check out his videos, and you’ll get a clear answer to this. I had asked the same question about Old Norse and how we know what I sounded like. ",
"We don't really. Ancient Greek and Latin are reconstructed based on modern Greek and Italian and ancient Greek and Latin writings.\n\nWe know, for example, that Latin used V as a \"sometimes vowel\", both where we would use U and V in modern romance languages. Because of that and the fact that Italian uses both U and V sounds, we assume that words like VENI are pronounced \"veh-ni\", and ANIMVS is pronounced \"ah-ni-muss\". But it is easily possible that it was mostly the same sound, even as a consonant, making VENI \"oo-eh-ni\" or \"weh-ni\"\n\nUnless we go back in time, we will never know 100% for sure.",
"We do have what was essentially text books for both ancient Greek and Latin. This was intended for both foreigners who wanted to learn the language and for poets who wanted to sound better. So we have a quite detailed description of how you should pronounce each sylibal. And unlike modern written languages, especially English, they did not have advanced rules for how to pronounce text. Each letter were usually pronounced and were pronounced the same way in every case.",
"_URL_0_\n\n\nthis person explains it so much better than i can, but the too long, didn’t read answer is this. basically it comes from looking at the writing we have from that period. but also looking at how people described how they spoke, people describing how those weirdos over there said things wrong, what rhymes in songs, and even puns. put that together with some linguistics skills and you can get a halfway decent idea."
]
}
|
[] |
[] |
[
[],
[],
[],
[
"https://www.youtube.com/watch?v=_enn7NIo-S0"
]
] |
||
743m95
|
how did we become to trust banks with all our money?
|
I know if I were in the early years of banking I sure as hell wouldn't trust them with my life savings.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/743m95/eli5_how_did_we_become_to_trust_banks_with_all/
|
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"text": [
"Well you could watch some videos about that on YT. I reccomend extra-history: Money. \n\nSo early in italy there was a lot of trade, and a lot of different currency. So the banks helped exchange money. You got some paper wich you could exchange at your lockal bank for gold. Eventually people never bothered to turn the papers instead just traded with the papermoney...",
" > I know if I were in the early years of banking I sure as hell wouldn't trust them with my life savings.\n\nYou mean when most likely you would be a dirt poor peasant who didn't have *any* life savings?\n\nEarly banking grew in a haphazard way but it was mostly used by wealthy merchants. The first real banks were in Italy and mostly acted as a neutral third party through which merchants could buy and sell goods without having to carry 100lb of gold across a country that was rife with bandits and armies. Instead the banks would issue promissory notes (the ancestor of our paper money) and would exchange these notes between each other so that trade could go on.\n\nFrom there is evolved into the modern system we have today.",
"The original conception of a bank was simply a storehouse for wealth, initially represented by money. Rather than keep all your wealth on you (robbery) or at your home (theft, home invasion robbery), you pay for your wealth to be securely guarded by people who's jobs it is to protect that money. \n\nTrue banking came about when bankers started loaning that money out as loans with interest rates. This was seen as a good idea by depositors, as they would no longer have to pay a fee for their wealth to be guarded. Additionally, banks could now accept more deposits and accounts from more people since every deposit represents float they can use to issue loans (rather than a cost).\n\nBank runs and closures were always an issue of course but far less prevalent than simple robbery.",
"Well it's a choice between trusting them with your life savings, or trust your life savings to all the people around you.\n\nOr more specifically when traveling, it was a good idea to have a personal note from a bank that you could then redeem rather than carrying all your wealth with you making you a target to be robbed and murdered."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
88uhiu
|
How does the size of a proton change under different conditions?
|
Within different sizes of atomic nuclei what governs changes in the size of the proton? What conjecture is there? What do we know? And how does this affect the density of atomic nuclei?
If any astrophysics people know anything about say matter in extreme conditions and it's affect on size that would be interesting to hear as well.
|
askscience
|
https://www.reddit.com/r/askscience/comments/88uhiu/how_does_the_size_of_a_proton_change_under/
|
{
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"dwndbwp"
],
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"text": [
" > Within different sizes of atomic nuclei what governs changes in the size of the proton? What conjecture is there? What do we know? And how does this affect the density of atomic nuclei?\n\nThe different sizes of nuclei are not really caused by individual nucleons having larger sizes. It's determined by how the nucleons are distributed within the nucleus. Some nucleon orbitals are very tight near the core, and some are spatially extended. For example, see [here](_URL_0_)."
]
}
|
[] |
[] |
[
[
"http://slideplayer.com/slide/7353729/24/images/3/Bound+lithium+isotopes.jpg"
]
] |
|
yu8by
|
How long will Neil Armstrong's footprints remain on the Moon?
|
I should ask: how long *could* his footprints remain on the Moon?
|
askscience
|
http://www.reddit.com/r/askscience/comments/yu8by/how_long_will_neil_armstrongs_footprints_remain/
|
{
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"text": [
"Unless disturbed by an outside force.... Forever ",
"Until some meteor strikes spread some powder over them to bury them. Infrequent, sure, but probably some 100,000 years or so, maybe a million.\n\nThis is the \"outside force\" that jamotron mentioned.",
"It will likely take hundreds of millions of years, but eventually micrometeorite impacts will make the bootprints unrecognizable. Or some large meteorite could destroy them tomorrow.",
"Several people hav already said that they will likely be covered up by a meteorite strike at some point in the future, but assuming that doesn't happen for a while I would imagine that humans will eventually colonise the moon in some way and preserve them because of their historical significance.",
"Don't forget that his first footprints have already been wiped out by the exhaust from the LM ascent stage. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
1v77ur
|
when your pen stops writing mid-word, you make it write again somewhere else, then try to write the same word in the same place as before, why it will stop writing again so often?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1v77ur/eli5_when_your_pen_stops_writing_midword_you_make/
|
{
"a_id": [
"cepdgrr",
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2,
3
],
"text": [
"It's probably the surface you are writing on that is causing the pen to stop",
"Usually, it's because you were writing too hard and made the ball stop turning because it's too slippery. You turn the ball somewhere else and the ball turns easier"
]
}
|
[] |
[] |
[
[],
[]
] |
||
8wq6fr
|
why can they make phone chargers that fit both ways but cant make a usb plug that fits in both ways?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8wq6fr/eli5_why_can_they_make_phone_chargers_that_fit/
|
{
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"e1xke01"
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"text": [
"They do, USB C. The more common USB types (A, B, Mini, Micro etc) will take a while to phase out as there is still so much tech out there that still uses them, especially USB A."
]
}
|
[] |
[] |
[
[]
] |
||
16yd7h
|
Can anyone tell me about historical Iberian cultures?
|
I'm trying to make a EUIII mod, and want to add some more nations in Iberia. Can anyone tell me about some cool tribes/factions/nations/etc that existed in the Iberian Peninsula? I'm not looking for anything specific, so christians, muslims, whatever is all fair game. Also I'm not shooting for perfect historical accuracy either, so although the game takes place in the 15th century, I'm interested in *any* cultures, even ancient ones.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/16yd7h/can_anyone_tell_me_about_historical_iberian/
|
{
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"text": [
"During the late medieval period (i.e. the 15th century), the Christian portion of the Iberian Peninsula (most of the peninsula at that point) consisted of four kingdoms: [Portugal](_URL_5_), [Navarre](_URL_17_), [the Crown of Aragon](_URL_1_) (which encompassed the Kingdom of Aragon, the County of Barcelona, the Kingdoms of Sicily, Valencia, and Majorca, and like a dozen other entities), and [Castile](_URL_10_) (which included the former kingdoms of Asturias, Galicia, and Leon). \n\nThe Muslim portion of fifteenth-century Iberia was simpler: the [Kingdom of Granada](_URL_7_) under the Nasrid dynasty. However, the Muslims had previously ruled most of the peninsula, so former political units included the [Emirate of Cordoba](_URL_2_), which, when Abderraman III promoted himself to Caliph in 929, became the [Caliphate of Cordoba](_URL_13_). Once that fell apart, the remains were petty kingdoms known as [taifas](_URL_18_), based in a major city like [Toledo](_URL_4_) or [Seville](_URL_8_). The Muslim realms of Al-Andalus were later united under first the [Almoravids](_URL_14_) (in the eleventh century) and then the [Almohads](_URL_0_) (in the twelfth century), both ruling from North Africa.\n\nAs for ancient tribes, pre-Roman Iberia was a mess of different cultures and political affiliations. The main divisions of cultures in pre-Roman Iberia were the [Iberian tribes](_URL_15_), the [Celtic tribes](_URL_9_), and the [Celtiberians](_URL_12_). There were dozens of tribes within these major divisions, and I'm not qualified to differentiate among them. In fairness, there's not a whole lot we know about them apart from what Roman sources had to say (and of course, material remains). In addition, the Romans themselves and the Carthaginians were vastly influential in the peninsula, the latter invading and recruiting Iberian mercenaries on their way to conquering Rome (spoiler: it [failed](_URL_3_)), and the former invading Iberia in response and making it a crucial region of their eventual empire.\n\nIn between the Roman and the medieval periods, several Germanic societies invaded Iberia. The [Vandals](_URL_6_) briefly invaded before being driven to North Africa by the [Visigoths](_URL_16_), who created a kingdom there that lasted several centuries. The [Suevi](_URL_11_) also entered the peninsula as the Roman Empire was fragmenting and carved out a kingdom in Galicia, in the northwest corner of the peninsula.\n\nI think that's all the major societies of premodern Spain. I'm not sure what you're looking for (social structures, military, etc), so I can't really give you much detail. I'll tell you what I'm able to if you give me more specific questions, and I can certainly point you to scholarly books and articles that know more than I do. One basic and informative one for the medieval period (my specialization) is [The Medieval Spains](_URL_19_) by Bernard Reilly (a very knowledgeable historian).",
"One of the most interesting things about Iberia is that, at the time its historical record starts (around the middle of the first millennium BCE) the peninsula was one of the only regions in Europe where Indo-European groups had not yet completely absorbed the previous inhabitants. Even today, the Iberian peninsula is the only part of Europe in which a pre-Indo-European ethnic group survives (the Basques).\n\n[Here's](_URL_0_) a detailed map of Iberia around this time: Although all this information is pretty sketchy given the scarcity of records, this is a pretty good overview of the dominant cultures in Iberia before the Carthaginian and subsequent Roman takeovers.\n\nThe dominant group in central Iberia before the Roman conquest were the Celtiberians, so-called by the Romans because they represented a cultural fusion between the native Iberians (non-Indo-Europeans) and incoming Celtic migrants from Gaul. In the far north, east and south, pre-Celtic groups remained dominant. In the south, there were heavy trade contacts with the Greeks and Phoenicians. One of the most notable native Iberian states that sprang up around this time was Tartessos, which seems to have been a muscular trading power based in what is now southern Spain and Portugal although it had disappeared by the time the Romans arrived.\n\nThe Romans had an extremely difficult time subjugating Hispania, as they called the whole peninsula. It took them around 200 years to break all resistance but eventually they succeeded and it would remain a Roman province until the breakdown of the Western Roman Empire in the 5th century CE. At this point an assortment of Germanic/Iranic groups entered the peninsula: the Vandals, Alans, Suebes, and Visigoths, but only the Visigoths managed to create a strong, lasting kingdom.\n\nAmong the Germanic successor kingdoms to the Western Roman Empire, the Visigothic kingdom is recognized as being among the most \"Romanized\" and refined. The Visigoths quickly fused themselves into the existing Hispano-Roman society. These Visigoths were far from drooling barbarians: like all the Germanic invaders they idolized Roman civilization and as much as possible in the decaying Roman world maintained the structures of Roman government and administration. \n\nHowever, despite its successes the Visigothic kingdom suffered from chronic political instability. The Visigothic kings were never able to overcome the power of the aristocracy and the principle of hereditary kingship did not take root. Frequent depositions and civil wars wracked the kingdom and contributed to its swift and easy takeover by the Muslims in 711.\n\nUnfortunately I don't have time to finish this narrative right now... but I'm sure other responses will give an idea of events after the Islamic takeover."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Almohad_Caliphate",
"http://en.wikipedia.org/wiki/Crown_of_Aragon",
"http://en.wikipedia.org/wiki/Emirate_of_C%C3%B3rdoba",
"http://en.wikipedia.org/wiki/Second_Punic_War",
"http://en.wikipedia.org/wiki/Taifa_of_Toledo",
"http://en.wikipedia.org/wiki/Kingdom_of_Portugal",
"http://en.wikipedia.org/wiki/Vandals#In_Hispania",
"http://en.wikipedia.org/wiki/Kingdom_of_Granada",
"http://en.wikipedia.org/wiki/Taifa_of_Seville",
"http://en.wikipedia.org/wiki/Celts#Iberia",
"http://en.wikipedia.org/wiki/Kingdom_of_Castile_and_Le%C3%B3n",
"http://en.wikipedia.org/wiki/Suebic_Kingdom_of_Galicia",
"http://en.wikipedia.org/wiki/Celtiberians",
"http://en.wikipedia.org/wiki/Caliphate_of_C%C3%B3rdoba",
"http://en.wikipedia.org/wiki/Almoravid_dynasty",
"http://en.wikipedia.org/wiki/Iberians",
"http://en.wikipedia.org/wiki/Visigothic_Kingdom",
"http://en.wikipedia.org/wiki/Kingdom_of_Navarre",
"http://en.wikipedia.org/wiki/Taifa",
"http://www.amazon.com/Medieval-Spains-Cambridge-Textbooks/dp/0521397413/ref=sr_1_1?s=books&ie=UTF8&qid=1358742327&sr=1-1&keywords=the+medieval+spains"
],
[
"http://en.wikipedia.org/wiki/File:Iberia_300BC.svg"
]
] |
|
b17t5r
|
what is modern macroeconomic theory and why do none of the top economists support it?
|
Today is the first time I've ever heard of it and all I have been able to find is conflicting information. Some seem to present it as a new school of thought (ex. Monetarism, Keynesian, New-Keynesian, Neo-Classical, etc.), but I haven't found anything to support this type of claim. Basically, does anyone actually know what this refers to, and what its underlying assumptions are?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b17t5r/eli5_what_is_modern_macroeconomic_theory_and_why/
|
{
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"text": [
"At a simple level, it posits a disconnect between spending and taxes. That is, the amount government spends is unrelated to the amount it collects as tax revenue.\n\nInstead, this discrepancy is merely an exercise in monetary policy.\n\nImagine for a moment that the U.S. government decided to just stop collecting taxes. Would it also have to stop spending? The answer is no. It could simply produce currency to pay its bills. Because the government has a monopoly over currency, everyone else is forced to accept it.\n\nThe reason you don't find economists supporting it is that it tends to fall into the category of overly simplistic models. While virtually any modern economist will agree with the basic notion that revenue and taxation are de-coupled in a way that my salary and my spending aren't, exploiting this fact in the way the MMT proponents describe normally leads to disaster.",
"So here's the first statement that economists disagreed with:\n\n\\- “Countries that borrow in their own currency should not worry about government deficits because they can always create money to finance their debt.” \n\nThis basically takes a truism in monetary economics, that a country that borrows in its own currency should never default on its debts, and stretches it. Leaving aside the fact that [the truism isn't even true](_URL_0_), it's kind of like going from \"A human can live with only one kidney\" to \"Go ahead, stab me in the kidney\". That is, a government borrowing in its own currency (probably) won't default from excess debt. Default would be a huge disaster, so that's good I guess? However, it will avoid the huge disaster only by bringing about a slightly-less-huge disaster and creating a hyperinflation crisis as it inflates the debt away. That's related to the second statement...\n\n\\- “Countries that borrow in their own currency can finance as much real government spending as they want by creating money.” \n\nThe key word here is \"real\". Printing money is an accounting trick. It doesn't produce any more of the goods and services that the government actually wants to buy. It's a classic pitfall of \"planned\" economies to think that doubling the \"budget\" for wheat by printing more money will actually double the amount of wheat available. Instead it just causes the price of some fixed amount of wheat to double. This is why the worst kind of inflation almost always stems from government stupidity or desperation. \n\nTo sum up: the basic reason why any economist worth their salt should be very suspicious of MMT is that it tries to wave away tradeoffs. Economics is all about the distribution of scarce resources, and you can't magic those up on a money printing press. If the government wants to give something of value to a citizen (e.g. a public servant, a military contractor, or a food stamp recipient), it *must* take something of value away from someone else. Government spending that pretends otherwise will eventually get pulled back to reality. \n\n & #x200B;"
]
}
|
[] |
[] |
[
[],
[
"https://en.wikipedia.org/wiki/1998_Russian_financial_crisis"
]
] |
|
1yxkky
|
why do some people worship satan?
|
I'm actually a pagan myself (/r/Asatru if yer interested), but I sometimes wonder why some people consider themselves to be satanists. If the Christians believe that he is a personification of evil and you'll be sent to a horrible place if you follow him, then why do some people still want to devote their lives to him?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1yxkky/eli5_why_do_some_people_worship_satan/
|
{
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"text": [
"If you're referring to Satanism, they don't actually worship Satan. It's simply the antithesis of Christian ethics. Most satanists are atheist. They just don't hold to 'love your neighbor' and such.",
"There aren't really any significant number of actual Satan worshipers.\n\nFirst off, you've got your disturbed teenagers that listen to heavy metal & want to piss off their parents. There's no real \"worship\" here, just doing \"naughty\" things to get attention.\n\nSecondly you have the [Anton Levey Satanists](_URL_1_) that don't really believe in the Christian mythology - at most, they view it as bad propaganda trying to make Satan look bad. To them, Satan is a symbol of free will & independence.\n\nThirdly, you've got some batshit Christians that need to have something to 'fight' against. They *make up* Satanic cults, just like they did [witches in the Salem Witch Trials](_URL_2_). The early 80s were full of supposed [satanic ritual abuse](_URL_0_) and the like but none of it ever actually turned out to be real. People that believe that angels & demons are real can believe all kinds of far out shit...",
"Satanist here. I'll try to keep this simple as possible.\n\nWhat most people in this thread are describing is the atheistic branch that tries to call itself \"Satanism\"... which is not Satanism.\n\nFirst off, I don't believe in \"worshiping\" him. I consider him more of a friend and a mentor, not some being that is to be slavishly worshiped.\n\nSecond... Unlike what all the abrahamic/xtian versions say, he's actually a kind and caring person. In the early years of humanity, he was known as the Sumerian deity Enki; this deity (and his allies) genetically transformed the then-current humans into what we are now. He's basically the \"creator of humanity\" if you will.\n\nHe and his allies then lost a heavy battle against those who opposed our creation, and were imprisoned for thousands of years. During these thousands of years, their own genetic creations started religions against Enki, to slander him and his allies as \"Satan\" and \"demons.\"\n\nIn short, the christian \"evil red guy with horns\" version of him does not exist; that version of him is basically a pattern of telling a lie so often, and for so long, it becomes \"truth\". The actual truth has become so distorted that it's hard to tell fact from fiction unless one is educated. \n\nIn closing... if you see a non-abrahamic religion with a \"creator of humanity\" god or \"king of the gods\" type role, it's usually him under a different nickname. Not \"torture and deceive all humans\" or some rubbish like his enemies promote.\n\n[I did an AMA here a while back, if you're interested.](_URL_0_)"
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Satanic_ritual_abuse",
"http://en.wikipedia.org/wiki/LaVeyan_Satanism",
"http://en.wikipedia.org/wiki/Salem_witch_trials"
],
[
"http://www.reddit.com/r/casualiama/comments/1ldzt0/i_am_a_22_yo_spiritual_satanist_ask_me_anything/"
]
] |
|
few3zs
|
During the Warlord and Republic period in China, the Muslim dominated Ma Clique seems to be the only force in the country with a strong religious affiliation. Is this assessment correct or did other Warlords, Cliques and factions have such support?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/few3zs/during_the_warlord_and_republic_period_in_china/
|
{
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"text": [
"It is true that the Ma Clique had a strong affiliation with Islam, being that many were ethnic Hui, most of whom practice Islam, which is still present in modern China. Because of that, I think the Ma Clique gets a lot of attention from Western observers, many of whom are usually surprised Islam is present at all in China. Anyone who has studied China, however, knows that while East Asian religion can be nebulous and extremely different from Western religion, \"China\" as a whole is quite ethnically and religiously diverse. \n\nDuring the 1920s, it became somewhat of a fad among various Warlords to convert to Christianity. Its really hard to pinpoint something like a persons attachment to cultural and material things, so I cant really just go around saying \"Well, warlord X converted to Christianity due to Y,\" but there's a good indicator that the powerful presence of the YMCA in China during this time was a driving factor. At a time when China was a failed state, various Western (and/or Christian) institutions that had existed within China for decades still held tremendous financial and political influence. In addition, Western-styles of life, politics, and culture seemed to be usurping traditional Chinese culture and power since the Opium Wars. Thus, for many wealthy elites, it made sense for them to send their children to Christian-run private schools in China, or to Japan, where they could receive a good, but more importantly stable, education. As a result, many of these future Chinese leaders grew up to be Christian. Again, this begs the question just how spiritually affiliated with their religion they were, who knows, but there were certain political implications to publicly announcing your new found Christian faith. \n\nThus, the Zhili Clique ended up having quite a few warlords who identified as Christian, most notably Feng Yuxiang, who later became a close affiliate of Chiang Kai-shek, who was also Christian. Many elites within the Kuomintang were well known Christians, including the Soong family, who consisted of future Minister of Finance TV Soong, Chiang's wife Soong Mayling, and Soong Ching-ling who married Sun Yat-sen and later became a communist revolutionary to her family's dismay. So while Christianity didn't peak among most warlords during the pre-Nanjing period, it as present and became more powerful with the rise of Sun Yat-sen and Chiang. It proved to be a powerful tool, along with Soong Mayling's American education, in securing trust and support from Western powers against Japan, which realistically didn't amount to much.\n\nThis religious attachment, and additionally attachment to a *foreign ideology*, became quite the bullet in the butt once communism became popular among Chinese elites. One can point out the irony of a party following a Western-born political ideology (communism) pointing the finger at KMT officials for adhering to a foreign religion, but I digress. Still, while I'm not expert on Chinese elite's religion, I imagine that most of these men were not exactly attached to Christianity the same way that Western leaders were. I do know that we have access to most of Chiang Kai-shek's personal diaries, and he was quite devout to Christianity. Additionally, he often blended many elements of Christianity with Confucianism, so we can possibly assume other devout Christian elites did too, as is natural with religious expansion. \n\nSo in conclusion, I can't give a straight answer, but we do know that Christianity became powerful during the 1920-30s among elites, especially Republican politicians. Christianity quickly fell out of favor once the CCP took over, but to this day roughly 2-3% of Chinese identify as Christians, which is about anywhere from 30-50,000,000 people."
]
}
|
[] |
[] |
[
[]
] |
||
mkrrz
|
What would it take to make Venus habitable?
|
So, Venus has approximately the same diameter as Earth, has a full atmosphere, is a rocky planet... What would it take to convert it into a livable planet?
For instance, [this](_URL_0_) comment in another thread makes it seem like a faster rotation would give a magnetic field, which then could allow water buildup.
Considering things like atmosphere, water content, distance to the sun, radiation protection from the Sun, what would it take to make a planet like Venus habitable?
|
askscience
|
http://www.reddit.com/r/askscience/comments/mkrrz/what_would_it_take_to_make_venus_habitable/
|
{
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"Venus has a very thick atmosphere that traps in heat from the sun, making it unbearably hot there wether the sun is showing or not. And because the atmosphere is so thick, the air pressure there would be unbearable as well. In the 70's i believe the Soviet Union sent probes to land on the surface of venus (Venera Missions). They usually didn't last more than half an hour as the systems failed due to temperature and pressure. So seeing as how reinforced probes wouldn't last very long on venus, I doubt we would fair much better. So I would say a complete overhaul of the venus atmosphere would be a start. Not so much in adding anything to it, but getting rid of a lot of it. That is if you want a habitable planet similar to earth. I have heard theories of having floating cities on venus way up in the atmosphere. Kindof similar to how the Jetsons lived i guess.\n\nAs for the magnetic field problem, I haven't researched much about it. But my guess would be that it does have one, otherwise i would think the atmosphere would have been carried away by the solar winds like mars' atmosphere was.\n\nEDIT:edited for spelling and grammar",
"Venus has a very thick atmosphere that traps in heat from the sun, making it unbearably hot there wether the sun is showing or not. And because the atmosphere is so thick, the air pressure there would be unbearable as well. In the 70's i believe the Soviet Union sent probes to land on the surface of venus (Venera Missions). They usually didn't last more than half an hour as the systems failed due to temperature and pressure. So seeing as how reinforced probes wouldn't last very long on venus, I doubt we would fair much better. So I would say a complete overhaul of the venus atmosphere would be a start. Not so much in adding anything to it, but getting rid of a lot of it. That is if you want a habitable planet similar to earth. I have heard theories of having floating cities on venus way up in the atmosphere. Kindof similar to how the Jetsons lived i guess.\n\nAs for the magnetic field problem, I haven't researched much about it. But my guess would be that it does have one, otherwise i would think the atmosphere would have been carried away by the solar winds like mars' atmosphere was.\n\nEDIT:edited for spelling and grammar"
]
}
|
[] |
[
"http://www.reddit.com/r/askscience/comments/mjw89/what_would_earth_be_like_if_it_was_tidally_locked/c31isf4"
] |
[
[],
[]
] |
|
a9fzwf
|
Are deep-sea creatures fragile?
|
Recently I've been reading a sci-fi book about a crew manning a deep sea geothermal plant and it is mentioned multiple times (and shown) that the organism down there are fragile and squishy due to their crappy diet. Is this true?
|
askscience
|
https://www.reddit.com/r/askscience/comments/a9fzwf/are_deepsea_creatures_fragile/
|
{
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"eclh5nt"
],
"score": [
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],
"text": [
"Due to the extreme amounts of outside pressure deep sea creatures experience they don't have any bones or teeth. \nThis causes them to be extremely squishy.\n\nIf we try to study them by bringing them to sea level they usually swell up and pop. Like a balloon would when you send them high into the atmosphere.\n(This is because the outside pressure isn't pushing as hard as the inside pressure when going higher and higher. So the inside pressure pushes harder against the walls of the balloon which causes it to expand or swell up and eventually pop)."
]
}
|
[] |
[] |
[
[]
] |
|
21ot8v
|
If you were to lose a Liter of blood, how long would it take your body to make that amount of blood back?
|
askscience
|
http://www.reddit.com/r/askscience/comments/21ot8v/if_you_were_to_lose_a_liter_of_blood_how_long/
|
{
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"cgf7lgz"
],
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49
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"text": [
"The plasma would be replaced very quickly; as soon as you ate a meal. The volume would be replaced within 6 hours. The red blood cells can take up to a month to regenerate. This is why you can't give blood more than once a month. "
]
}
|
[] |
[] |
[
[]
] |
||
3fndbl
|
Archeologist, and those who study Native Americans: Do we know of any large areas of North America that were never explored by native Americans?
|
askscience
|
http://www.reddit.com/r/askscience/comments/3fndbl/archeologist_and_those_who_study_native_americans/
|
{
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"text": [
"While there are certainly areas where no archaeological remains have been found, it's nearly impossible to know if no native ever explored an area. If all they left behind is footprints and all they took with them were stories that have been lost in time...\n\nOne might think the best bet for unexplored terrain would be the extreme far north, such as Ellesmere island. However, there is evidence that this area was inhabited both by the Dorset (who were probably related to other native american populations but are now extinct) and the Thule (present day inhabitants who came from Asia in the middle ages). There were also likely some viking explorers in the area during the period when Greenland was settled and vikings traded with the Dorset and Thule. \n\nThere are areas in Northern B.C. that remain remote and difficult to travel to today, even with modern technology. For example, it is estimated that more people have walked on the moon than have been through some parts of the stikine river valley, which has some of the most difficult rapids in the world inside of a deep canyon. It is unlikely that natives could have successfully explored such areas as they wouldn't have had durable modern kayaks or, likely, the deathwish necessary to paddle into that canyon. However, it's not impossible. \n\nPerhaps the only sure bet for unexplored terrain is any area recently uncovered by retreating glaciers. If a place was under a kilometer or two of ice until the last few decades, it was not accessible to native americans during prehistory.\n\nAs remote as some places are today, it is important to remember that 99% of Archaeology is done no more than a couple hours drive from the nearest pub. It's not that archaeologists are lazy, it's just that it's incredibly difficult and expensive to survey remote areas and more difficult still to dig there. There have been significant finds in the last few years thanks to the availability of satellite imagery of remote areas. However, such imagery, no matter how well massaged by algorithms, can only reveal relatively large features, such as buildings. With only a few exceptions (e.g. the mound builders of Cahokia), large structures were not built by natives in North America. There are, no doubt, many archaeological sites we have yet to discover, especially in remote areas where humans seldom tread even today. "
]
}
|
[] |
[] |
[
[]
] |
||
8mib7i
|
What were plebeian sports in the past? And what are the reasons?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8mib7i/what_were_plebeian_sports_in_the_past_and_what/
|
{
"a_id": [
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],
"score": [
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"text": [
"Sorry, we don't allow [\"example seeking\" questions](_URL_0_). It's not that your question was bad; it's that these kinds of questions tend to produce threads that are collections of disjointed, partial, inadequate responses. If you have a question about a specific historical event, period, or person, feel free to rewrite your question and submit it again. If you don't want to rewrite it, you might try submitting it to /r/history, /r/askhistory, or /r/tellmeafact. \n\nFor further explanation of the rule, feel free to consult [this META thread](_URL_1_)."
]
}
|
[] |
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"https://www.reddit.com/r/AskHistorians/comments/3nub87/rules_change_throughout_history_rule_is_replaced/"
]
] |
||
75b9iy
|
why do some cops in big cities like new york use horses?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/75b9iy/eli5_why_do_some_cops_in_big_cities_like_new_york/
|
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"They're usually used for crowd control purposes. Being on a horse allows the officer more visibility while also being easier to spot for those who may need them. They're also used where a car just wouldn't be practical, like a wilderness areas or a very large grassy park, ex: Central Park in New York",
"In nEw Orleans we use them for crowd contol. You get the fuck out of the way when one of those huge horses start moving. I've also seen them form a wall. Pretty cool.",
"I used to wonder about this too. Then I was caught in a football riot, and saw a mass of hundreds controlled by just a few cops on horses. The sight of those beasts coming towards you in a row, slowly and inexorably, is awe-inspiring. I can't even imagine what having them galloping at you would do to you.",
"They've been a tried and tested way to control crowds for thousands of years. Ever tried fucking with someone on a horse who knows what he's doing?",
"They are used for crowd control purposes for the most part. They are very common in Britain as well. Especially during big football games and protests.\n\nI live in a town outside Edinburgh, and one time the crime got so bad they had police on horses patrolling certain estates all day. Was quite weird but I guess it does deter people from committing crimes",
"What about when the horse poops? Is it the officers job to clean it up or is it someone's job?",
"[This is why](_URL_0_)\nNotice the guy at the beginning and the guy at the end that are too slow to move. \nTurns out horses are pretty heavy and strong ",
"The real reason, and most effective reason, is public relations. \n\nWatch to see, a troubled area, or an area that just had a shooting, a lot of times mounted units are sent to the area, because people love animals, kids especially, and will often times go out and talk to the officers, meet the animals, have a positive social interaction with police, fostering better community relations. People will even sometimes give information on crime or problems in the community through this interaction, like where the crack houses are, or where some troubled people might be living. \n\nThey are good for riot/crowd control, and a good visible patrol, but PR and community relations is what they are best at. ",
"Horses offer a number of benefits in city environments that make them an ideal partner in many situations. They allow a rider to sit up high for a better view of what's going on. They can turn around or maneuver in tighter spaces than a car could. Horses are great for dealing with crowds as well, because they're big animals and if they push you, you're going to move. There's also a bit of natural fear that humans have of a big animal that may trample them, so people tend to respect a horse much more than they respect a police car. Adding to that, some people won't think twice about smashing a cop car window, but it's a whole different story if you're attacking an animal. Especially if that animal can fight back.\n\nIt's also only my personal opinion, but I think a cop on a horse is seen as a bit more friendly and personable than a cop in a car.",
"I know diddly about horses. The couple of times I've been around them their owners warned me to back off or I'd risk getting kicked. They particularly seem nervous of people getting behind them. I always kind of wondered how well trained police horses are to be in the middle of crowds and not be nervy about the people around them.",
"Went to Times Square in NYC one night. It was very crowded. There were police on horses. Police cars or motorcycles just wouldn't work in those dense crowds. Bikes could maybe work. Horses definitely work well.",
"Community policing is a big part of why they're used too. All part of a greater effort for better police-civilian relations. They might not be in the best tactical situation while riding a horse through the park but they'll get a lot of attention from people and kids admiring the horse.",
"Don't forget mobility! Horses can manuever up, through, or around obstacles. Since, having the ability to jump and what not",
"Because horses can shit on the street giving a nice slippery trap to stop pesky criminals.\n\nIn all seriousness it's the same reason motorcycle cops exist. More maneuverable. Except horses can more easily go off road.",
"My initial thought was that the horses have been around long before modern metropolitan police or even cars. After a quick look into it there is a pretty rich history. \n\nHistory of NYPD’s Mounted Unit\nA Stately Presence: The NYPDs Mounted Unit\nNew York City police have used horse-mounted officers since at least 1858, with the opening of Central Park. Since its formal organization in 1871, the Mounted Unit has evolved into one of the NYPD's most visible andelite police units. This exciting exhibit will explore their fascinating history and continuing day-to-day operations. Through artifacts that include saddles, harnesses and uniforms, paintings, video, and historic photographs, the exhibit will delve into the lives and work of the officers known by their nickname,\"10-foot cops.\"\nOne area of the exhibit will even provide a lifelike recreation of a stable for the Unit's horses. Overall, the exhibit explores the history of their patrol in parks, city streets, parades, and city-wide demonstrations, and examines the training and dedication required of both police officer and horse alike. \n\n_URL_0_\n",
"Side note: in San Francisco and San Jose, they have trading cards for both the horse & officer. You just have to ask for it. They are super cool.\n\n(I used to collect them and always got excited when I saw a mounted officer. Don't know if the still make cards.)",
"Two reasons, for crowd control in large public events and for public relations - people love to approach police on horses and get to meet the horse. [I know the second reason sounds odd, but it's true.](_URL_0_)",
"Horses are great for crowd control because they're intimidating (most people will instinctively get out of the way) but not threatening (very few people perceive a horse as a weapon). ",
"Horses are a force multiplier. The typical factor given is that in an inforcement action, a horse accounts for 10 human officers.\n\nHorces also tend to calm people down. Or make them think about moving on.",
"One of the best advantages of it is that the police officer does not have to watch where he's going. The horse can navigate, leaving the officer free to pay attention to the crowd. ",
"one additional point, horses also have the same quality that bike cops get, they don't isolate you like being in a car does. it lets you hear what's going on around you.",
"A few different reasons, but when patrolling it helps spread goodwill and interaction with the community. They can also go places faster than bicycle cops, they control crowds by their size and force (and will fight back if provoked), unlike a bike they also have self preservation and will (usually) try not to die when carrying you (bikes don’t do that). I could go on... ",
"Also, besides all the other mentions, horse cops are way more chill and way less douche than bike cops. Motorbike cops are the worst followed by bicycle cops.",
"Multiple reasons, some have already been mentioned in to comments, others haven't. Keep in mind that this is based on my experience working with this in Sweden. Mileage in other countries may vary. \n\n1. Horses are less noisy and more approachable. People can come up and talk to the officer in a different way. \n\n2. The horse still offers mobility and speed. \n\n3. Tradition and culture. In a lot of places, like Sweden (where I live) horses are fairly integrated in culture. People enjoy seeing horses out and about. Not everyone want to approach one, but that's fine. \n\n4. Crowd control. You absolutely do not fuck with one of those horses. They're huge, and on their back you have a trained police officer. It's a force multiplier. I've seen sports events riot like situations where three mounted officers replaced 20-25 officers in riot gear. The fights stopped immediately and people scattered. \n\n5. Accessibility. A mounted officer can move in areas where a car can technically move, but is advised not to because it could cause blockage or congestion. Such as walking streets or shop streets. \n\n6. Visibility. A police forces primary task is to maintain law and order. This is preferably done by preemptive measure, with things as simple as visible presence being at the top of efficiency. A mounted officer can both see and be seen easier. This has a calming effect on the public as well as encourages approaching the officer. We were often approached about very minor things, which didn't warrant any kind of report or anything, but that keeps the public happy and calm to be able to let the authorities know about. ",
"One thing I noticed being around my cousins horses in Carlise and Langholm is that they are really fucking big and powerful. I can see why through out history and in some places today there use remain relevant. ",
"* Taller than a bike (better visibility)\n* Can go where cars cant/move in traffic\n* Faster than walking",
"New York has Central Park. Horses are able to go where a police car can't. Crowds move aside for horses. Mounted Police can see above traffic and crowds.",
"They are fantastic for crowd control. I was outside Madison Square Garden one night. The crowd was on the verge of mayhem. 4 cops on horses came right up the stone stairs outside. In short order they split these assholes up and dispersed them. Horses move people like you wouldn't believe. They get to places scooters/cars can't and they give a great view from the saddle.",
"I wondered this too when I was growing up. Then I watched an episode of Cops that showed it for me. Like this, in a crowd in New Orleans.\n\n_URL_0_\n\nA few things stand out. \n\nThe officers can see everyone and everything. \n\nAn officer would have to push to get through the crowd, a horse just walks and people have to part.\n\nA half-ton animal is so big it gives even a belligerent drunk pause. It takes a special person to think they can fight a horse."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[
"https://www.youtube.com/watch?v=VyPpo7Ng-48"
],
[],
[],
[],
[],
[],
[],
[],
[
"http://historydetectives.nyhistory.org/2013/05/blast-from-the-past-ten-foot-cops/"
],
[],
[
"http://www.scpr.org/news/2014/03/02/42534/role-of-police-on-horseback-has-changed-over-time/"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://youtu.be/YoO1m4G4wvA"
]
] |
||
7wvfvo
|
why is the end of the nail different than the bottom of the nail if the nail grows upward and they are the same thing?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7wvfvo/eli5_why_is_the_end_of_the_nail_different_than/
|
{
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"du3i36d",
"du3i8a5",
"du3io67"
],
"score": [
4,
10,
2
],
"text": [
"Well it's so one end is pointy and it'll go into the wood easily, and the other end has more surface area so it's easier to hit with a hammer and transfers more energy.",
"Oh you mean finger nails, right? My first thought was wood nails haha. As for the colour Change, the keratin which your nail is made of needs to be hydrated and is so whilst in contact with the skin constantly but once it reaches past that then it dies and turns white.",
"Note: I am talking about finger nails, not regular nails. Sorry for the confusion haha."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
43f8dh
|
Why didn't late medieval armies resurrect the Roman way of fighting?
|
By this time I would have thought a lot of the more advanced European powers would have the money and technology to create a Roman-style infantry army. I'm aware of things like the rodeleros, but why did armies choose to fight with massed pikes instead? Hadn't the Roman legions proved to be more flexible than the Macedonian phalanx?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/43f8dh/why_didnt_late_medieval_armies_resurrect_the/
|
{
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"czi39mo",
"czi6fgo"
],
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22
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"text": [
"In the most significant sense, late medieval/early modern armies did resurrect the Roman way of fighting: larger, more centralized states developed administrative and financial apparatuses that were able to raise and maintain large bodies of soldiers in the field for sustained campaigns. The capability to put large numbers of troops in the field matters more to military success than copying the exact tactics of a bygone era. Replicating the sword-and-javelin armament of Roman infantry wouldn't be nearly as effective for late medieval armies, when plate armor (that wouldn't be affected at all by javelins) was becoming more and more affordable for the average soldier. Even the cheap munitions plate available to the average Hapsburg pikemen in 1530 would be much more protective than the linothorax of his Macedonian counterpart. Pike formations were supplemented by other, shorter weapons: the proportion of halberd to pikes was often a fixed ratio that varied from country to country. The inflexibility of pikemen was a known weakness that was often exploited, but ultimately massed piked proved themselves capable enough they were only eventually supplanted by increasingly sophisticated handheld firearms. ",
"In addition to what MI13 mentioned in their excellent answer, you have to keep in mind the tactical employment of Early Modern pike formations bore only superficial resemblance to Macedonian phalanxes. They both carried pikes, and that was it. The Spanish, on the cutting edge of military development in the 16th century, fought in the tercio; in a bastioned square, with muskets in every direction, they usually stood their ground even when completely surrounded, whereas Macedonian phalanxes often collapsed when outflanked. \n\nIn another sense, Early Modern armies like Maurice of Nassau did emulate the Roman way of war; they compensated for the limitations of muskets by countermarching, rotating men in a file to keep the men ready to fight in the front rank. They built sophisticated logistical networks. Their greatest strength was the scientific application of engineering to construct and overcome fortifications. Is there anything more Roman than that?"
]
}
|
[] |
[] |
[
[],
[]
] |
|
16968u
|
How often was upward mobility available to serfs and villeins around Norman times?
|
Were there avenues for advancement out of serfdom and into, say, into becoming a villein or even upwards into barony? Were the agricultural classes generally happy or unhappy with their lot in life? Did they strive to become something else, or was it something they resigned themselves to or even proud of? Did they feel pride when one of their number gained higher status, or was it more jealousy or feeling they were acting "above their station" and that being a churl was too good for them?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/16968u/how_often_was_upward_mobility_available_to_serfs/
|
{
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"text": [
"Norman times were about 900 to 1200, so portable wealth (coinage) was rare and most store of value was actually land. It was more after 1300 did trade begin to grow and commoners (merchants) became upwardly mobile due to commerce. So peasants were locked into their social class for the most part. \n\nThe avenues for upward mobility were basically through warfare and martial aspects. That was pretty much it, they really hammered it in that they were two distinct social classes, the nobility and commons. A serf was pretty much a serf for life otherwise, and a villein would have a much greater chance at losing their status than increasing it. Peasants generally did not volunteer to be taken on campaign either, their lords usually forced them to accompany them. A free man (small minority until cities grew) might volunteer for terrible pay or promise of likely spoils, such as a tenant farmer or even a hunter. The ways to advance in warfare was generally capturing and ransoming a noble and pillage. Of course nobles themselves enriched themselves with the lands conquered but that wasn't available for peasants. There's tales here and there of a peasant rescuing a knight or doing something heroic on the battle and receiving a small honor; but for the most part peasants were largely overlooked as combatants, even though they fought. \n\nAs far as receiving a barony, it really wouldn't happen but I wouldn't say absolutely impossible. A commoner that became a titled/landed in one generation would be seen as an incredible upstart and create discontent amongst the landed nobility. They didn't want to associate with commoners at all. If land went a commoner's family it would be because a commoner became a squire then knight, then their son would be more eligible to be granted land/title through martial exploits. \n\nThese last few questions are rather personal, so nothing is really exact since they were people and would of course have varying opinions and outlooks to a degree. Villeins and serfs didn't know too much better than what they had. They lived on and worked their lords land and that was about it for the most part. They were the real workers of the agrarian economy and manorial system, the just didn't know it. Being a peasant was an extremely hard life, but in many cultures they did get to count their blessings such as festivals and carnival. \n\nIf they hoped for anything beyond a good harvest and marriage, it was usually more rights or to abolish their obligations to their lord. This is evident by recurring peasant revolts, where they usually stormed the manor and destroyed the feudal documents...then went home with nothing really changed. I don't think I would say they were resigned to their lot in life, but they were likely simply unaware that they could be more than what they were. They lived very sheltered lives for the most part. They often weren't too proud because no matter what, they'd be working the fields. It didn't matter if their lord lost a war and was ousted from his land for a new lord, as long as the new lord wasn't cruel. They had no hand in medieval politics, just another result of them being tied to the land. There is evidence that some aspired to increase their position because of accompanying their lord on campaign and a few succeeding in doing so. \n\nI can't really answer your last question though. I suppose like with most of the personal questions they were just human too, and the responses varied from person to person, culture to culture. \n\nEdit:\n\nOne thing about the Normans, I remember reading they had one of the most established feudal systems at the time, but at the same time they had the most opportunities to rise in status in warfare. \n\nSome sources:\n\n_URL_2_\n\n_URL_0_\n\n_URL_1_",
"Happiness in 11th century England was a relative concept to happiness today. People generally would've been happy if there was enough food on the table to feed themselves. They also would've been happy if they were alive and healthy. The concept of social advancement or many of the things that we today deem essential wouldn't have even crossed their minds. If someone didn't like the system, they would either be killed by their master or, if they were able to escape, they'd have to combat the cold, highwaymen, robbers, and the ability to feed themselves. Finally, banish any thought of killing animals for your survival: this is 11th century England, and poaching is a crime punishable by death. Regardless, they couldn't negotiate at any rate: Normans spoke an archaic form of French, while serfs and various classes of peasant spoke middle English. If peasants stayed on the estate and pleased the local powers to be, they could *possibly* be shown extra favor in terms of food and resources.\n\nSome serfs were \"lucky,\" and were able to join the clergy. However, monks also had an equally hard life and you'd probably go from farming one piece of land to now farming another piece of land elsewhere. Instead of belonging to your lord, you'd now belong to the Church. Whether or not this is an improvement or not is highly dependent upon your monastery. If you lived on a large demesne or were from an isolated part of the country, you may not even know that monasteries exist.\n\nOpportunities for social advancement came only in war time. Until the 16th century, all nobility was created by the sword. Exceptional bravery in times of war could, in theory, lead to upward mobility but I can't think of any cases off the top of my head. From what I've written, it appears as if the end-game for any peasant appears to be trading bondage in one form for bondage in another. This is exactly the point. Even barons owned their land in right of the King, and private property would have been a relative concept because everything was owned by the King.\n\nThere are some exceptions. Assuming that you could survive all of the above and make it to, say, London you could theoretically be some sort of craftsman. However, London at that time was hardly anything more than a hamlet. Some peasants were free men and able to move, but generally speaking this was an inordinately complicated transaction for a man with absolutely no education or skills to begin with.\n\nIn short, there was very little social mobility unless you were inordinately fortunate."
]
}
|
[] |
[] |
[
[
"http://www.medieval-life-and-times.info/medieval-life/index.htm",
"http://faculty.history.wisc.edu/sommerville/123/123%2013%20Society.htm",
"http://www.yale.edu/ynhti/curriculum/units/1986/3/86.03.03.x.html"
],
[]
] |
|
5ska0d
|
What are the biggest limitations of SETI?
|
askscience
|
https://www.reddit.com/r/askscience/comments/5ska0d/what_are_the_biggest_limitations_of_seti/
|
{
"a_id": [
"ddg7y05"
],
"score": [
2
],
"text": [
"The strength of our observational equipment, the type of equipment used and signal processing for intelligence are the big limitations. Current SETI instruments look at the radio and visual spectrum for signals. The problem is that in order to detect radio waves and lasers from a potentially advanced civilization requires a huge optical receiver/antenna which is very expensive to create and operate. Conversely, to broadcast a message into space detectable by a civilization also requires an enormous apparatus. To maintain clarity of transmission/reception, the size of both the receiver and transmitter increases as the distance between communication sources increases. Nobody knows how far away broadcasters maybe (assuming they exist at all).\n\nThen we have the issue of deciphering an intelligent message from random background noise. This has become better over the years, but we're only familiar with earth-based communication and there's a whole lot of ways of encoding information. We rely on the assumption that such an intelligent species would realize this issue and code in some universal manner...but we can only guess at what that might actually look like.\n\nEdit: we also assume all intelligent aliens use radio and lasers to talk. There are other potential methods that we might not have the technology to intercept."
]
}
|
[] |
[] |
[
[]
] |
||
18lcge
|
If one consumes an excess of sodium during a meal, could he offset it by drinking an excess of water?
|
Just something that I always wondered and tried to rationalize to myself after eating some really salty foods.
|
askscience
|
http://www.reddit.com/r/askscience/comments/18lcge/if_one_consumes_an_excess_of_sodium_during_a_meal/
|
{
"a_id": [
"c8ftajx"
],
"score": [
8
],
"text": [
"Sodium controls how much water is in your body. If you eat more sodium, you hold onto more water. This can increase your blood pressure but your kidneys try to compensate. Many anti-hypertensive medications act on the kidneys, causing them to lose more sodium and water. \n\nThe concentration of sodium in your blood is kept the same, this is why water is so closely linked. In short, the quantity of water is irrelevant over a certain point, your kidneys decide how much water you need. If you have more sodium, your kidneys will hang on to some water, if you drink extra water the kidneys will do the same and you will excrete the excess. "
]
}
|
[] |
[] |
[
[]
] |
|
2fb2y0
|
Is there any material that reflects all wavelengths of the electromagnetic spectrum?
|
also, what causes a certain frequency to reflect at all?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2fb2y0/is_there_any_material_that_reflects_all/
|
{
"a_id": [
"ck7mqcw"
],
"score": [
4
],
"text": [
"Materials reflect a wavelength when there is a quantum transition available at the corresponding energy. For instance, metals reflect in the visible because they have electrons with a broad spectrum of energy levels to move into. \n\nThere isn't any material that I'm aware of that is reflective throughout the spectrum. Taken to the extreme, eventually high energy photons will eject electrons rather than being absorbed and reemitted. Infrared photons, towards the opposite end of the spectrum, excite bond vibrations and thus increase the temperature of the material rather than reflecting. "
]
}
|
[] |
[] |
[
[]
] |
|
jm9i0
|
how does bill proration work?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/jm9i0/eli5_how_does_bill_proration_work/
|
{
"a_id": [
"c2dc710",
"c2dc710"
],
"score": [
2,
2
],
"text": [
"Bill proration is adjusting how much you pay for a good/service depending on how much of it you used. Think of the bill like a candy bar that costs $1 but you only want half of the candy bar. The person selling you would \"prorate\" the price of the candy bar to $.50 \n\nAn adult version of this would be rent. Let's say your parents pay $500 a month for ya'lls place but ya'll moved half way into the month. Since ya'll weren't using your place for the full month the person renting out the place (known as a landlord) would only charge your parents half of that month's rent, $250.",
"Bill proration is adjusting how much you pay for a good/service depending on how much of it you used. Think of the bill like a candy bar that costs $1 but you only want half of the candy bar. The person selling you would \"prorate\" the price of the candy bar to $.50 \n\nAn adult version of this would be rent. Let's say your parents pay $500 a month for ya'lls place but ya'll moved half way into the month. Since ya'll weren't using your place for the full month the person renting out the place (known as a landlord) would only charge your parents half of that month's rent, $250."
]
}
|
[] |
[] |
[
[],
[]
] |
||
7654oc
|
how does gravitropism work?
|
Additional: How would affect plants in places with other gravity, e.g. Moon?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7654oc/eli5how_does_gravitropism_work/
|
{
"a_id": [
"dobdbxo"
],
"score": [
3
],
"text": [
"Some plant cells are sensitive to gravity, and the plant uses this information to send the root down and the stalk up when the seed germinates. It would not work as well on the Moon or Mars, where there is less gravity, but some effect is still likely. Of course, both these places have a larger obstacle to plant life - no atmosphere."
]
}
|
[] |
[] |
[
[]
] |
|
y98pd
|
Is the energy required to get to space diminished by any significant amount by launching in the opposite direction of Earth's revolution?
|
It's 6 AM. I'm hopped up on coffee and reading Wikipedia articles about space travel. Bear with me.
The question is whether or not space-bound vehicles gain any kind of "boost" by lifting off in the opposite direction of Earth's path around the sun. In the same way that I can throw a baseball farther with less effort if I'm standing atop a bus and I throw it toward the rear of a bus, can the space-bound vehicles gain any kind of boost by going in the opposite direction of our planet?
If so, is it at all measurable or even significant enough to be worth factoring into the planning that goes into the launch? If not, why isn't there any measurable difference?
|
askscience
|
http://www.reddit.com/r/askscience/comments/y98pd/is_the_energy_required_to_get_to_space_diminished/
|
{
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"c5tgq0y",
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"text": [
"It is very much measurable and an extremely important part in interplanetary travel. Most spacecraft launch to Earth orbit going eastwards because the surface of Earth is rotating that way about 460 m/s. The orbital speed at low Earth orbit is around 8km/s so you get 5% of that for free there.\n\nWhen you leave Earth for some other planet, you need to be going somewhere around the escape velocity from Earth, or 11 km/s, this is relative to Earth. Earth itself is orbiting the Sun at about 30 km/s relative to the Sun. So depending on which direction you leave Earth, your velocity relative to the Sun can be anywhere from around 20 km/s to 40 km/s, that is Earth's velocity relative to the Sun plus or minus your velocity relative to Earth. That is a very significant difference and pretty much dictates your entire trajectory in the solar system. If you leave Earth opposite the way Earth is travelling around the Sun, and thus end up with around 20 km/s relative to the Sun, then you'll end up going inwards in the Solar System. If you leave Earth the other way and get 40 km/s velocity relative to the Sun then you'll go outwards in the Solar System.\n",
"Imagine that the earth is a big space ship orbiting the sun, and your ship is just a little shuttle craft docked on the spaceship. If you burn't against the direction of earth's trajectory, you would kill speed, relative to the sun. If you speed up in the direction that earth was going, you would gain speed relative toggle sun. If your asking which way is most efficient to escape the solar system, then it's to burn in the direction earth is heading. ",
"Related trivia. An Israeli engineer told me the political requirement to launch in the wrong direction was problematic for his country's rocket programs."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
547jjj
|
What are the best books on the life of Charlemagne?
|
I've read quite a bit about Charlemagne legacy, but I've had a hard time finding more detailed information about his rise. Are there any sources (besides Einhard) that would help me learn more about Charlemagne, his family, his military campaigns (against the Lombards and the Saxons, among others), and the political struggles in the region before he largely stabilized it?
Thanks!
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/547jjj/what_are_the_best_books_on_the_life_of_charlemagne/
|
{
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"text": [
"I hesitate to recommend this to you, but I DO recommend it as a good candidate for someone with good general history interest and knowledge, but relatively little on the man himself. *Charlemagne: From The Hammer to The Cross* by Richard Winston is a good read. I just finished it a few weeks ago.\n\nIt was written in 1954, and the author is clearly of the WW2 generation. It was a bit jarring, but effective, to come upon Charlemagne's \"final solution to the Saxon question.\" You don't live through WW2 and then walk on eggshells with your choice of words. The subject himself has a pretty impressive credit and debit balance, and it all gets a good airing. Many points should have gotten more time, but in his defense, this is one book, not 7 books, and the historical written record is pretty thin.\n\nSpoilers - There's lots of killing people and breaking stuff, Irene of Athens is a piece of work, and Abul-Abbas the elephant gets a good long mention.",
"Rosamond McKitterick's [*Charlemagne*](_URL_1_) is the most up-to-date scholarly work. For a broader perspective, you might want to check out [*The Carolingian World*](_URL_4_) (2011), which could be used as a textbook for an advanced history class but which I still find to be a straightforward and enjoyable read.\n\nAnd if you're willing to make the adjustment, there's nothing like going back to the sources. First and foremost is Einhard's *Life of Charlemagne*, which can be found in many different editions in print and online. I'd recommend the cheap Penguin edition in [*Two Lives of Charlemagne*](_URL_3_), which is a solid translation and includes what is still a quality introduction to this text. (McKitterick also opens up her book on Charlemagne with a good discussion of Einhard, who remains our most informative source on the man himself.) Going a bit deeper, you could also check out [*Carolingian Chronicles*](_URL_0_), which brings together some of our other most important sources alongside Einhard. Alternatively, you might look into Dutton's great anthology, [*Carolingian Civilization*](_URL_2_), which includes both Einhard and selections from the chronicles.\n\nI glanced through as much of Winston's *Charlemagne* as I could see on Amazon preview. It looks like a quick and fun read, which might be a good place to start, although I would hesitate to take his word as final on many key issues. We now understand the vitality of Merovingian kings, the relationship between church and state, and even the very notion of political power in the early middle ages completely differently from when Winston was writing in the mid-1950s. If you're looking for a quick sketch of Charlemagne's life, Winston's work seems to have weathered well, but I wouldn't trust it as a map to navigate the contours of Charlemagne's career as we understand it today.",
"followup question - is there a consensus on whether Charlemagne could read and write?\n\nA brilliant world history teacher in high school, some decades ago, mentioned that he was pretty much illiterate though he also kept a quill and ink and paper near his bed. He was quite good at his job. In a Texas high school, during the Reagan era, he showed us *Battleship Potemkin*. He has since gotten an PhD, and I'm inclined to take his opinion seriously.\n\nWinston's *Hammer to The Cross* votes YES he could. Winston also comments at some length that he disagrees with conventional wisdom on this point. Clearly, there were also scribes/secretaries to take a letter as he dictated, but he could at least manage himself. Winston even mentioned his tutor's name.\n"
]
}
|
[] |
[] |
[
[],
[
"https://catalog.hathitrust.org/Record/000133210",
"https://books.google.com/books?id=kxb8kR4hvbQC",
"https://books.google.com/books/about/Carolingian_Civilization.html?id=2zAjAQAAIAAJ",
"https://books.google.com/books?id=L7Rf2PsyvowC",
"https://books.google.com/books?id=OkSG3X-M80oC"
],
[]
] |
|
8osfzb
|
Why have wars in Asia and Africa become so bloody and difficult for the Europeans after ww2?
|
In the 19th and the early 20th century, wars in Asia and Africa were a relative cakewalk for the Europeans (even when fighting modernized enemies like the Boers). After WW2, the french wars in Indochina, the Algerian war, and later the US campaigns in the Middle East have become constant, bloody, expensive guerilla wars with no end in sight. What exactly has changed?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8osfzb/why_have_wars_in_asia_and_africa_become_so_bloody/
|
{
"a_id": [
"e063im9"
],
"score": [
6
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"text": [
"The problem with your question is that the initial premise is wrong. 19th and early 20th century conflicts in Asia and Africa were not the cakewalks we imagine them to be. Although 20th century popular culture has often portrayed conflicts between European powers and the inhabitants of colonies and regions intended for colonization as short and relatively inevitable in a white, European victory. The most representative example of this would be the Anglo-Zulu War of 1879, arguably the most well-known colonial conflict in the popular imagination of the west. Even in the crushing defeat of Isandlawana, the layman knows that there will be a European victory shortly afterwards in Rorke's Drift. \n\nBut let's take a step back. First and foremost, we have to establish the fact that we are dealing with not only different centuries, but also different types of conflicts. The Anglo-Zulu War was what we would call a conventional war. What this effectively means is that the war was fought by primarily conventional, \"normal\", tactics and strategic thinking. Two conventional armies fighting against each other with the intent to defeat the other in a set-piece battle. The kind of war we think of when we, for example, imagine the Second World War or more suitably for the period, the American Civil War. Throughout the 19th century in both Africa and Asia, several conventional wars did occur between colonizers and the would-be colonized. One such war for example, the First Italo-Ethiopian War in 1896, effectively prevented the colonization of Ethiopia by Italy. \n\nBut more frequently, colonial wars and wars of conquest were not strictly conventional. Many were unconventional, in which the European powers had to subdue forces who were using guerrilla warfare, or a mixture between the conventional and unconventional. This also characterizes the conflicts you refer to in your question. The Indochina War, the Algerian War, the Vietnam War, The Malayan Emergency, the Portuguese Colonial Wars, etc. were all unconventional conflicts or a mixture between the two. The reason for *why* unconventional conflicts can drag on for so long is based in the fact that it is unconventional. Unlike the conventional war, the unconventional or asymmetric war will have one side who *doesn't* want to face the other side in open battle. Instead, the side that utilizes guerrilla warfare will try to survive and outlast its opponent to the point where the opponent has to give in, give up and/or leave. This is a simplification, but it needs to be understood that we are talking about different approaches to winning a war. \n\nThis brings us back to your question. Why \"have wars in Asia and Africa become so bloody and difficult for the Europeans after WW2\"? Because they were equally as bloody and difficult for Europeans before WW2. The initial French conquest of Algeria took more than 15 years to accomplish. The French conquest and subsequent pacification of Indochina began in the late 1850s but lasted well into the early 20th century. The five Xhosa wars that the British experienced in modern-day South Africa between 1811 and 1879 pale in comparison to the fact that colonists in the Americas fought long wars to subdue their native populations, some beginning in the 16th century and not \"winning\" until the 19th and into the 20th century. These are only some conflicts in Africa, Asia, and the Americas that can be mentioned in this context. Additional conflicts ranging from Bosnia to New Zealand can be added onto a very extensive list of unconventional conflicts that were far from a \"relative cakewalk\". Furthermore, these conflicts were equally as physically and psychologically straining for the soldiers fighting in them as they are today. Let's consider the following quote from a soldier fighting in Indochina:\n\n\"The ambushes and the constant shots fired from the side of the road unsettled us to the point where all thoughts of mercy disappeared. An open battle does not create the same feelings of hate and vengeance. For months you've been in constant strain to be killed in an ambush like an animal, each minute you have to think that there are enemies all around who are just waiting for you to pass by. Constantly these sounds of shots being fired on a very short distance and that makes your ear ache! All human emotions disappear and you are taken by rage. You lose the ability to see the conditions clearly, to see them as they really are.\" \n\nThis quote could equally have been uttered by a French soldier in Indochina in 1952 or an American soldier in 1969. Instead, it was written by Swedish French Foreign Legionnaire Martin Sandell in 1901 while fighting in Laos.\n\n**Sources:**\n\nA good introduction source to the scholarly study of guerilla warfare in history is *Modern Insurgencies and Counter-Insurgencies: Guerrillas and Their Opponents since 1750* by Ian F. W. Beckett. The quote above is from Bertil Nelsson's *Breven från Tonkin: En svensk främlingslegionär i Indokina*."
]
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[] |
[
[]
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|
6or2zf
|
why is the molecular weight standard (the amu) measured as 1/12 of a carbon-12 atom? why not base it off of hydrogen or helium?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6or2zf/eli5_why_is_the_molecular_weight_standard_the_amu/
|
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"In 1903, before they had discovered elemental isotopes, it was suggested to use 1/16th the mass of oxygen and quite a bit of literature built up around it. But in 1929 isotopic oxygen was discovered and different standards were established for chemistry and physics respectively. This lead to a divergence of calculations which in 1961 was corrected by changing the definition to carbon-12. One of the reasons carbon-12 was chosen was to minimize divergence from prior literature."
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1dgnxp
|
How does obesity affect the procedure of surgery? If the patient carries excessive body fat, how much does it hinder the surgeon?
|
This is mainly referring to surgeries done in places with typically more body fat, such as stomach or chest area.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1dgnxp/how_does_obesity_affect_the_procedure_of_surgery/
|
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"[This comparative MRI image](_URL_0_) helps you understand fat distribution in people a bit. All that tan stuff is fat.\n\nFat is mostly subcutaneous (under the skin), so if a surgeon needs to access your abdominal cavity, then the belly area will have a large pad of fat that needs to be gone through/around. My experience is in vet med not human, but I can imagine that you would make your access incisions along the areas of thinnest fat covering that would still be readily closed. Laparoscopic surgery (via small access incisions and using scopes and very small instruments) is common in people but the scopes used have size limitations.\n\nIn surgery, anything that isn't *what you are trying to deal with directly* is in your way. Say you're trying to find the uterus in a dog to remove it (ok so my experience is biased but same principle), everything else in the abdominal cavity is in your way. intestines, spleen, urinary bladder, etc. So if everything is *also* covered with a layer of fat (the omental covering that drapes across your intestines really likes to deposit fat) then even more \"stuff\" is in the way of you finding that uterus and tying off/cutting the blood vessels, etc. Fat also has an excellent blood supply and when you mess with it, it will ooze a lot, so keeping blood loss under control could be an issue.\n\nI can imagine that with the immense size that people can get, it increases difficulty not only technically but physically. moving them around, getting appropriate surgical exposure, etc takes more people and more effort.\n\nAnd don't forget the increased anesthetic risks. Obesity affects drug metabolism and respiratory volume, as well as cardiovascular status.",
"Obesity affects surgery in many ways:\n\n* Persons who are obese tend to have a variety of comorbidities, including diabetes, heart disease, hypertension, obstructive apnea, etc.\n\n* Morbidly obese persons are 90% likely to have abnormalities in the liver (i.e. fatty liver) (\nPalmer M, Schaffner F. Effect of weight reduction on hepatic abnormalities in overweight patients. Gastroenterology 1990; 99: 1408–13., Albert S, Borovicka J, Thurnheer M, et al. Pre- and post-operative transaminase changes within the scope of gastric banding in morbid obesity. Schweiz Rundsch Med Prax 2001; 90: 1459–64., Gholam PM, Kotler DP, Flancbaum LJ. Liver pathology in morbidly obese patients undergoing Roux-en-Y gastric bypass surgery. Obes Surg 2002; 12: 49–51., Ramsey-Stewart G. Hepatic steatosis and morbid obesity. Obes Surg 1993; 3: 157–9. Clain DJ, Lefkowitch JH. Fatty liver disease in morbid obesity. Gastroenterol Clin North Am 1987; 16: 239–52.)\n\n* Due to hypertension, kidneys can filter drugs out of the system quicker (Marik P, Varon J. The obese patient in the ICU. Chest 1998; 113: 492–8. Ribstein J, duCailar G, Mimran A. Combined renal effects of overweight and hypertension. Hypertension 1995; 26: 610–5.)\n\n* Diabetic patients have a much greater chance in surgical site infections. Although glucose is controlled during surgery, post-op 30-day care is usually done at home and glucose may not be as closely monitored (Latham R, Lancaster AD, Covington JF, Pirolo JS, Thomsas CS Jr. The association of diabetes and glucose control with surgical-site infections among cardiothoracic surgery patients. Infect Control Hosp Epidemiol 2001; 22(10):607-12.).\n\n* Obese patients are at a higher risk to develop deep vein thrombosis (blood clots) and is a major, independent risk factor for a pulmonary embolism (Braekkan SK, Siegerink B, Lijfering WM, Hansen JB, Cannegieter SC, Rosendaal FR. Role of obesity in the etiology of deep vein thrombosis and pulmonary embolism: current epidemiological insights. Semin Thromb Hemost 2013 (April 27) (Epub ahead of print). Allman-Farinelli MA. Obesity and venous thrombosis: a review. Semin Thromb Hemost 2011; 37:903-7.).\n\n* They are harder to intubate (provide an airway tube) and the use of surgical airways is much greater for bariatric patients during surgery (McCarroll SM, Saunders PR, Brass PJ. Anesthetic considerations in obese patients. Prog Anesthesiol 1989; 3: 1–12.).\n\n* Weight-based dosing of drugs are difficult, as some are dosed for their actual body weight and others on their ideal body weight (some are effected by fatty tissue, some are not).\n\n* As stated by someone else, finding veins are difficult.\n\n* Obese patients are harder to position for surgery. They are harder to monitor as standard cuffs may not be adequate for blood pressure monitoring (too much fatty tissue between cuff and blood vessel, cuff does not fit, etc).\n\n* Open surgery is very difficult when having to retract large amounts of tissue. There are many practical aspects that make this difficult, as a patient who is lying down may be in too high of a position for the surgical team.\n\n* It's rare, but it does happen, but hypersaturation of oxygen, lots of fat, and electrocautery can cause fires. Obesity is not a factor in the likelihood of occurrence, but a factor in severity.\n\nThis list isn't exhaustive, but can provide you some idea of the challenges of providing surgery to the obese. Also note, morbidly obese persons may not get surgery as complication rates are too high and weight management is attempted before surgery. This includes weight reduction surgery, such as the roux-en-y.\n\n**EDIT: Sources--I'll have to come back to this when I have time.**",
"Not to mention that a bone marrow tap is much more difficult to perform on an obese thigh.",
"I don't work on the living, but an issue you run into also is the natural heat from your hands can warm up the adipose tissue in the area you're working and melt it. Everything becomes really slippery! ",
"Not a surgeon but I did get to sit in on a total double hip replacement surgery of an obese person. A total double hip replacement is when you take the ball and socket out of the hip joint and replacement it with a plastic and metal joint. This is designed to reduce the amount of pain it takes to move, normally because excess bone growth makes things all crunchy after sustained abuse to the joint. As one might expect, joints take more abuse if you have more weight on them, which is why obese patients are common in orthopedic surgery.\n\nRegardless, the double total hip replacement turned into a single total hip replacement because it took a very long time just to get one hip replaced. The surgeon and his team had to constantly readjust the fat that protruded from the patient's stomach. It would seek to rest over the hip joint that the surgeon was trying to replace. \n\nI also sat in with the same surgeon during his clinic days - the vast majority of his patients were obese or old (in fact, I think all of them were on that day). When a seriously obese person came into the clinic, she had to be lifted onto the table with the help of the doctor, a physician assistant and 2 or 3 nurses. Then he had to readjust the fat to see if the joint was operable. During that process, there was mold or something that was under the fold of fat that stunk up the examination room for a few hours.\n\nJust do yourself a favor and go for a run. ",
"Maybe I'm not asking the right question for this but how do surgeons determine the obesity of a patient? Do they find out the body fat percentage? Or is it more of an eyeball \"I think I'll need to cut further down if I want to do X..\"?",
"Obesity affects us in anesthesia, too. Some of this might be repeats of what everycredit said, but here is a list of why I like my patients on the lean side:\n\n* Airway issues - obese patients have a lot of \"redundant pharyngeal tissue\" making intubation more difficult. They also have heavy heads and many have tiny mouths, and that also makes it tougher to get the tube in.\n\n* Ventilation is more difficult - the ventilator has to lift a heavy chest, using higher pressures. I often have to play with the settings on the vent and use more frequent, smaller breaths to get both oxygen and CO2 to the right levels. Put the patient in a head-down (Trendelenberg) position, and ventilation can be nearly impossible.\n\n* Oxygenation - morbidly obese patients have no lung reserve for oxygen. I can put a non-obese patient to sleep and have a good two minutes to get the tube in before the oxygen levels drop. Obese patients, maybe 15 seconds. Now, we usually get the tube in right away, but if you refer to my first point, that might not be the case with an extra large patient.\n\n* Monitors - the BP cuffs, even the large ones, don't fit well. Many obese arms are cone-shaped, and the darn cuffs are cylindrical. I have put arterial lines in patients because of size for big cases.\n\n* Positioning - when the patient is wider than the table, we have to worry about pressure points and keeping all the body parts on the OR table. If we have to go lateral or prone, it's difficult.\n\n* IV access - it's harder to hit what you can't see or palpate. I have luck with the inside of the wrist on a lot of obese patients.\n\n* Regional blocks - much more difficult when you can't find landmarks. Spinals and epidurals are more difficult when you're starting a few inches out from where you would in a non-obese patient. There's a lot of \"stab in the dark\" and hope for finding landmarks with the needle in these folks. I have used 3 1/2 inch long epidural needles as introducers for 5 inch spinal needles in very obese women for C-sections.\n\n* Comorbidities - hypertension, diabetes, arthritis are extremely common, and they complicate anesthesia somewhat. \n\n* Drug dosages - many of the anesthetic drugs are based on \"ideal body weight\", but in reality, they tend to need more than that... sometimes. It's hard to predict. Fortunately, we titrate most of what we use.\n\n* Upper airway obstruction post-op - if I treat their pain with opioids, they get comfortable enough to obstruct and stop breathing. If I go easy on the pain meds, they hurt, and that's not acceptable either.\n\n* Delayed awakening after inhalation anesthesia - if the case is long enough, more than an hour or two, inhalation anesthetics start getting into the fat. They come out slowly after the surgery is done. Combine that with a little airway obstruction, and they can re-anesthetize themselves in recovery.\n\n* Surgery is going to be more difficult - I have to worry about more blood loss, longer anesthetic times, frustrated surgeons and have to be ready for changes in the surgical procedure (laparoscopic to open, mostly).\n\nThat's just off the top of my head. Obesity makes my job a lot harder. A little overweight is no problem. Morbid obesity is a big problem, and puts the patient at higher risk for anesthetic complications.\n\n\n\n\n\n",
"One thing that can be affected by obesity is radiology. If there is too much fat in the way, certain things like an inflamed appendix won't be seen in the imagery. "
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a0ifa9
|
why does our brain sometimes wake us up during the night, despite there being no external stimulus, and when we clearly have not had enough sleep?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/a0ifa9/eli5_why_does_our_brain_sometimes_wake_us_up/
|
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"Depends. What kind of waking up are you talking about?\nThe one where you have no chance to go to sleep again (insomnia style) or more like waking up, realizing it’s still bed time, rolling to the side and going back to sleep? ",
"Just wanted to add to what others have written - there's a chance that there was some external stimulus (noise, temperature, light, movement, feeling), that you weren't aware of at the time of waking up.\n\nFor example, you may hear your phone buzzing in the next room just enough to wake up, but you may not understand that's what you've heard, or that you've indeed heard it. (happens to me with my alarm sometimes)\n\nMy SO occasionally wakes up like that while I'm still awake, and it's usually due to some random \"interference\" (noise or light mostly), but when she wakes up she's not aware of any reason for waking up.\n\nHope this helps :)",
"I've heard that back in the olden days we never used to sleep through the night but would wake and get up for a few hours during the night before going back to sleep again. ",
"Happens to me when I have caffeine after 4pm or so. I assumed caffeine didn't really affect me since I drink it so much. But I started paying attention and it really does affect my sleep even when my tolerance is at its highest."
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3opcsp
|
why don't modern tv's have more than 3 light colours?
|
Screens are made up of RGB, but why don't modern HD TV's have more to get even better colour quality?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3opcsp/eli5_why_dont_modern_tvs_have_more_than_3_light/
|
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"You wouldn't necessarily get better color quality. Our eyes have only three different types of color receptor. This is known as trichromatic vision. If you added another color, that would mean you would have more than one way to represent a given color, but there's no real advantage to that - it would look the same to our eyes, and it would reduce the resolution, because each individual pixel would be larger.\n\nPrinters usually use four colors - cyan, magenta, yellow, and black added. This is partly because it's difficult to reproduce black accurately by mixing cyan, magenta, and yellow (even though you could in theory), but also because black is a very common text color and it saves on the color ink.",
"Because you can make almost any color by playing with the intensity of each of the 3 sub-pixels included in a pixel.\n\nAlso less sub-pixels means a pixel will take less space which implies more pixels for a certain surface \n",
"That's not true at all. Sharp makes RGBY TV's (RGB + yellow) since 2010. They call this technology [Quattron](_URL_0_). Whether it works better, it's debatable.",
"You only need RGB to make every color the human eye is able to detect. The combination of colors in discreet amounts with give rise to millions of colors. Light has additive properties which means you get a range of different colors when added and will eventually add up to white when combined enough. \n\n_URL_0_\n\nSource: I work with digital cinema projectors and have to calibrate the color systems.",
"Because it *wouldn't* improve things. But it *would* make the equipment more complicated and more expensive (at least using current technologies), and would also quite probably take up more transmission bandwidth (more information to encode).\n\nUnderstand - your eye *doesn't* see thousands of colours. It sees only **three** - red, green and blue. The three types of cone cells in a normal eye are tuned to those wavelengths; if a different colour comes in, they may react - but not as strongly. So each and every colour of light that reaches your retina gets registered as varying amounts of just those three colours. The \"thousands\" bit happens in your brain, when it compares just how much of each of the three it got.\n\nBut crucially, neither your eye nor your brain can tell the difference between light that is a mix of those three colours, and whatever monochrome light stimulates the receptors to the same degree. Send the right mix of the three colours, and you can show the brain any colour you want. (Lots of Red, lots of Green, no Blue? \"Yellow\". Doesn't matter whether the eye actually got pure yellow light, or an equal mixture of pure red and pure green - the eye can't tell, and the signal the brain gets is the same.) More colours wouldn't add anything; they'd just get broken straight back down into RGB by the eye, leading to a different mix that you could have sent with three colours anyway. So that's what TV sets send - RGB. It's an optical illusion - frankly, an out-and-out con trick - but it's one that works, and it's the simplest solution to date.\n\n(The brain is effectively pulling the same trick that has been used in the past to allow cameras on spacecraft to take full colour images using monochrome photography - take a picture through a red filter, then take the same picture through green and blue filters. When the three are combined - full, perfect colour. As far as the average human eye is concerned, at least; some animals register more, or less, colours than us, and probably wouldn't agree. Nor would they necessarily agree that the colour on a colour TV is correct.)"
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1kzfsl
|
Why does alcohol store dead tissue so capably, but is so harmful towards living tissue?
|
Need to save a liver for display in a jar? Use alcohol!
Wanna ruin a live liver? Use alcohol!
What gives?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1kzfsl/why_does_alcohol_store_dead_tissue_so_capably_but/
|
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"I'm not so sure about alcohol, but lets think for a bit about preserving tissue. I'm familiar with formaldehyde: it gets into your sample, permeates it, and then \"cross-links\" (AKA \"fixes) many proteins together. Basically, it chemically freezes everything in place exactly how it was when you applied the formaldehyde. This preserves the sample, and lets you come back later and look at the sample in the exact same state it was in when you fixed it.\n\nThink about if you exposed a living liver to formaldehyde. It fixes the liver, freezing everything in place. The liver could not possibly function like this, and it thus dies. The thing that makes the formaldehyde so great at preserving is what makes it so dangerous: everything biological it's exposed to grinds to a perfectly preserved halt.\n\n(Please note that when I say \"freezes in place\" I don't mean actual cold freezing, I just mean cessation of motion.)\n\nAlcohol works somewhat differently, but the principle message is the same. Alcohols like ethanol basically surround and unravel proteins without completely dissolving everything. This is me hazarding a guess here, but I'd say that helps incapacitate proteins that are designed to break down dying tissue. In this way, the tissue is preserved. \n\nKeep in mind the concentrations required to ruin a liver and MUCH MUCH lower than the concentrations needed to preserve stuff. Alcohol has a myriad of other health effects that may or may not be related to its preservation properties. "
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|
136omi
|
Wednesday AMA: I am heyheymse, specialist in Roman sexuality and mod of this fine community! AMA.
|
Hello historians! As most of you know, I'm not only a mod but a historian with a speciality in Roman sexuality. My dissertation was subtitled, "Sex, Deviance, and Satire in Martial's Epigrams" - have any questions about how Romans had sex? Or anything else, for that matter? Ask away!
(Previous AMA is up [here](_URL_0_) on /r/IAmA, if you wanna take a look at that. Or not.)
EDIT: I'm back and I'll try to do as much as I can tonight! If I don't get to your question tonight, I swear I will get to it!
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/136omi/wednesday_ama_i_am_heyheymse_specialist_in_roman/
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"Thanks for the AMA! I recently rewatched Gladiator, and it got my curious as to how accurate the depiction is of upper class women having sex with gladiators. Is there any record of specific couplings of this nature?",
"Hello there! I eagerly waited for this AMA! I realize 'Ancient Rome' covers a huge period of time so you could be as general or specific as needed with time and setting!\n\nSo, was monogamy considered to be the standard loving relationship? Were adulterous affairs common? And if found out, would they be tolerated by their significant other? If it wasn't, what would the fallout be like?\n\nI'm assuming homosexuality was fairly common, though I could be wrong. Were homosexuals seen as sexually deviant and would they have been open about their relationship? \n\nI've also heard stories about crazy Roman orgies that would last for entire days at a time. I imagine this was restricted to the upper class? My reasoning being the common people ain't go not time for that. \n\nI'd just like a general overview on these apparently infamously hedonistic orgies. If they were really as ubiquitous as I've heard, why? Also would it be an 'open call' sort of thing or would they have been a 'close circle of friends and family' sort of thing?\n\nAnd on that matter, what was incest like in Ancient Rome? Taboo or just another relationship?\n\nThanks for the AMA!",
"Hey cool! I have a few questions about Roman sexuality vis-a-vis Greek sexuality:\n\nDid Roman society have its own version of hetaera? \n\nWhat did Roman scholars think about the Athenian pederasty system? \n\nIs there much evidence in the way of Roman sexual identity (their ideals, I guess?) altering as they encountered/absorbed Greek city states? ",
"I'm doing a fair bit on the Eastern Roman empire at uni at the moment. To what extent was Roman sexuality consistent with Romanoi sexuality, and how did the latter change over time? I understand if this is outside of your period/expertise, no worries that's the case. Thanks for doing the AMA!",
"How did/or did Roman sexuality evolve over the course of it's history? Do we see certain acts fall in and out of favour?\n\nHow did Roman's sexuality influence politics or the way leaders governed?",
"Hey, I really enjoyed your previous IAMA. Unfortunately, by the time I noticed it had already exploded, so I missed the opportunity to ask this question:\n\nIn the series \"Rome\", an upper class woman sent a well-endowed slave as a gift to another woman. Did this actually happen? Was it a regular occurrence?",
"Hello! Thank you so much for doing this AMA.\n\nI was wondering if you could shed some light on how Romans (of any age - I know that 'Ancient Rome' covers a huge area!) saw women's sexuality, including both heterosexual and queer sexuality. (I.e., did they share the attitudes of the Classical Greeks towards women, requiring them to stay in the home and culturally robbing them of sexual agency? Is there any evidence of queer female activity in Rome, a subculture or even just a scandal?)",
"One of the great problems with history is that it all too often recorded from the perspective of educated, often wealthy, males. Are there any alternate sources on Roman sexuality which could give us further insight into what sex was like for women or slaves? \n\nI've just read Ovid's Amores, which features a poem in which he attempts to persuade a man to let Ovid sleep with his wife. Was a Roman wife's sexual freedom controlled by her husband completely? Or is Ovid's work not to be trusted as a representation of Roman sexuality at all (because Augustus deemed it \"immoral\")?",
"I have a question regarding the office of censor. What kinds of \"sexual deviancy\" would get you in trouble with the censor? How was it prosecuted? ",
"What was the Roman attitude to sex with 'minors'? Was it normal? Frowned upon? Was there an age limit? Morally? Legally?",
"Did the advent of Christianity in Rome create a steep decline in what would be viewed today as promiscuous sexuality?",
"Were there any punishments in Rome dealing directly with sexuality? For instance, forcible castration or forced sexual relations.",
"Are there any stories from Ancient Rome in Romeo and Juliet style, where for example a patrician teen falls in love with someone from a rival family, or falls in love with a plebian, and when that happened, was it damaging to that family's reputation?",
"I challenge thee...to name your favorite catullus poem!\n\n[Relevant.](_URL_0_)",
"How prevalent were sexually transmitted infections in ancient Rome? I recall one of my Latin teachers mentioning that Herpes was huge at one point, but I never read anything from the time that would back anything up. ",
"In the last year of High School, 1/3 of my Classics grade was based on one essay on whether Julio-Claudian Morality was more in line with Epicureanism (as depicted by Lucretius), or Seneca's Stoicism. I spend most of my time rather embarrassingly blethering on about militarism and family values with little secondary evidence to back this up. Being an 18year old boy, I probably also propagated some misconceptions that would have you screaming. \n\nWhat would your take on the matter of philosophy and morality be within your field?",
"What are some historical 'pick up lines' the Romans used? Or in history in general?",
"What significant sexual more is the *least* changed between ancient Rome and modern America?",
"what's your favorite sex scandal of the time?",
"How much evidence is there for Heliogabalus'/Elagabalus' purported sexual excesses, and how much of it is just \"something someone said once\"? Are there are records of people who were famous at the time but less famous today than Heliogabalus, and equally (or more) sexually deviant? How aware would the public have been of his sex life and/or of the rumors about his sex life?",
"Thanks for doing this AMA & c :D\n\nWas there a (negative) stigma attached to being a prostitute? Did it depend on class or gender? (Ie, was working as a prostitute not that big of a deal for lower-class women?) Were most prostitutes slaves?\n\nWas there a stigma attached to men who were celibate/'confirmed bachelors'?",
"I looked and didn't see this posted, but what was the romantic and sexual life of an average Roman citizen like? Not talking about patricians, but what did an average person do to find someone to fall in love with and how would they have expressed their love sexually? Also, I understand it varies widely person to person, but I'm just curious. Thanks!",
"I remember reading a book about Pompeii years ago. I have no idea what it was called or who wrote it but I recall it being a fairly legit source, as in an actual work of academia. It dealt with Pompeii in general and (among other things) the brothels, and even had a map with all of them marked, and suggested that the large amount of prostitutes fulfilled a societal need of men getting their rocks off with women other than their wives to not get them pregnant which risked their lives and the stability of the family unit. Basically it claimed that 'infidelity' was a necessary institution.\n\nI'm sorry I have no further details on the work, but thoughts, comments?",
"This is a dumb question, but you're the best person to answer it I think. I've leafed through Tacitus and Jerome Carcopinos book with out much luck. Also tried Wiki and google.\nI was musing about the current Japanese attitude to nudity (bathing naked in onsens) and was wondering if there were any other societies that had a similar outlook. I thought of Ancient Rome because well, there were public baths for both men and women. A lady in my tour group insisted that in Ancient Rome, slaves were forced to breed and there were special places, with erotic pictures, where they were brought to put them in the mood.\nIs there any truth to this? I have searched through my references and came up with nothing, and was pretty surprised when she said it. Wanted to give her the benefit of the doubt however, as I have big gaps in my knowledge on Ancient Rome.",
"What is your opinion of the film Caligula? I understand there is a great amount of controversy regarding the film's unsimulated sex scenes, but what do you think about the film's historical accuracy?",
"I have to confess, after following the AMAs you've done, my main fascination have become your thoughts/opinions re: Rome and Spartacus. (Both of which I've seen you mention, and both of which are fascinating whilst simultaneously being rife with inaccuracies.)\n\nMore a statement than a question, so no pressure to respond.",
"I've read in studies of the British Empire that men who went overseas often went with the idea that they would be freer in terms of sexuality and sexual practices in the colonies. (Source: Ronald Hyam's *Empire and Sexuality*). Is there a similar attitude towards going to the colonies among Roman men? \n\nAlso, would there be significant differences in Egyptian marital and sexual practices from the Romans after Egypt's incorporation into the Empire? Or would it be more a case of amalgamation by the time the Flavian dynasty takes power? ",
"How did the Romans have anal sex before the invention of lube?",
"Ancient writers, such as Herodotus, Heraclidus Ponticus and Strabon say that Thraco-Dacians were polygamous. It has been some debate whether this happened only for the *tarabostes* (Dacian aristocracy) or it was a general rule.\nPolygamy wasn't restricted to the Dacians, my understanding is that it was a common habit for \"barbarians\".\nMy question is therefore - what did happen when, after being conquered, such polygamous societies were subject to the monogamous Roman society.",
"How did the myth of Roman orgies come about? Was it spread after the fall of Rome as evidence of their immorality or did they actually occur?\n\nNo smoke without fire?",
"Do you have insight into how slaves were treated when it came to being allowed to marry? Were they able to or was it forbidden? And, did the practice of \"breeding\" exist (matching slaves for offspring) or would the families just purchase new ones?\n\n\nSorry if this is worded odd, I can't think of a better way to ask.",
"So I'm very late to this party, however, if you do get a chance to answer this; I'd very much like to know what types of sources you find for this stuff. Are there books written purely about sex or is it referenced in all manner of unrelated biographies and similar writings?",
"Have you ever read Neil Gaiman's [24 hour comic on the Emperor Heliogabolus](_URL_0_)? I'm wondering how accurate this comic is, and was this the most perverse guy on the block. Also, where can I read up on more along these lines?",
"Hey, thanks for the AMA, fascinating stuff!\n\nWas there any evidence of sexually transmitted diseases in ancient Rome? If so what were they? How were they treated? And what were they thought to be? \nAlso, we hear about homosexuality mostly concerning men, were there any documented or well known instances of women engaing in sex with each other?",
"Hey, having dated and lived with (different) classicists ancient rome has always been a prurient interest of mine. \n\nOne thing I find interesting/strange is the idea of slaves and woment not really having any agency or there being any notion of consent or lack of it. How much of this reflects people's real attitudes? The idea that rape just wasn't considered a moral issue just perplexes me. Even if there weren't legal punishments you would think there would be some moral/social condemnation. ",
"I'm actually curious what your day to day professional life is like, with such a specific specialty. I would imagine you've nearly, if not already, exhausted reading through source material on the subject.",
"Alright. So, in Cicero's *Pro Caelio*, Cicero's defense of Caelius includes the following sentiment, roughly paraphrased: \"he was a little wild, and might have slept around too much, but who hasn't at that age? As long as he becomes a respectable adult after his passions cool, he'll be fine.\" (I apologize for omitting an exact quote)\n\nIn other words, Cicero seems to suggest that there was a period in a young man's life, after he became a man legally, that he could engage in a bit more sexual deviance than was normally allowed...as long as he eventually straightened up. (In this case, it was sexual deviance with Clodia). Was this actually a norm, or merely a rhetorical invention on Cicero's part?\n\n(This is, of course, a very specific question, but I'm a Classics major who nearly did a paper about this topic). Thank you!",
"What are some texts you'd recommend on ancient (Roman or otherwise) sexuality? ",
"Hi there! Hope I'm not too late, I'm in an exotic time zone.\n\nDid the Romans have what is known as \"intercrural sex\" -- sex between the thighs (the passive partner holds their legs together as tightly as possible)? Or was solely a Greek practice?",
"I'm probably too late for this question, but here goes anyway. I remember reading that Romans would sex during gladiatorial events because the proximity to death was a huge turn on. \n\nIs this true? If it is was it common across all classes or just among those who had the means to afford a box seat to the games?",
"Hi there! Let me be late to the party (as per usual) and ask if your dissertation was available to the public and where could I find it? I did a quick Google search (I even tried DeeperWeb!) but it yielded no results. Judging by reading your comments, it sounds like \"Sex, Deviance, and Satire in Martial's Epigrams\" would be a hilariously informative read. I enjoy history and have taken a few classes towards a minor in it when time in my schedule permits. (But as a double major in Math and Engineering, these moments are hard to come by.) But I refuse to let the interest die! So please reply, even if it is to politely decline."
]
}
|
[] |
[
"http://www.reddit.com/r/IAmA/comments/u7zpn/iama_heyheymse_from_askhistorians_i_have_a_degree/"
] |
[
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://www.youtube.com/watch?v=Yzs2Fq1ICZU&list=FLcMZoy-tJUOPDCr3cfmy2Uw&index=64&feature=plpp_video"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://www.holycow.com/dreaming/stories/being-an-account-of-the-life-and-death-of-the-emperor-heliogabolous/"
],
[],
[],
[],
[],
[],
[],
[],
[]
] |
|
d1nceg
|
Was the 1972 World Chess Championship really as big of a deal as "Bobby Fischer Against the World" portrayed it?
|
It implied it was a pretty big event with tonnes of people watching, a complete national event like a mini-superbowl. Was it really that popular in the USA? Was Russia similar? None of my friends or anyone I work with could even name the current WCC.
Also the doc portrayed the Russians as being this entity supporting Spassky and Fischer being more of a lone wolf. Was this accurate or did Fischer have a big support network too and the doc tried to romanticise it?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/d1nceg/was_the_1972_world_chess_championship_really_as/
|
{
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"ezr5fxm"
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"text": [
"There is a lot to unpack here. First, you should know that Bobby Fischer suffered from mental illness from a very early age. I did a 2.5 hour [presentation](_URL_2_) on Fischer's biography, including discussion of mental illness, if you're interested. This bears on the \"lone wolf\" characterization which I will address later. Second, you should know that Fischer was undoubtedly the strongest chess player in the world in the years before the world championship, but he wasn't playing. He didn't feel like he was getting paid enough, felt like others were colluding against him (and he was partly right), etc. \n\nHe was convinced to play in the qualification to become the official challenger in 1970, and began a streak of play which has seen no equal before or after. He won the interzonal tournament by a large margin, ending with 7 straight victories (no losses or draws). He then played Marc Taimanov, a strong Russian GM, in the quarterfinals, and crushed him 6-0 *with no draws*. The beatdown was so bad the Soviets would yank Taimanov's chess stipend and bar him from international competition, essentially ending his career. In the semifinals,Fischer played Bent Larson, widely considered the second-best Westerner to Fischer. Fischer beat him 6-0 *with no draws*, too. The finals were a bit harder, but after settling his nerves, Fischer beat Tigran Petrosian, the former World Champion, *four straight games* to close out their series.\n\nOnce he earned a spot in the World Championship, Fischer tried to negotiate and renegotiate everything about the series, from the location (switched several times before ending up in Reykjavik) to the prize purse (increased to the unheard of $125,000). And after all that, he still refused to go until a wealthy financier *doubled* the prize purse out of his own wallet. So there was lots of mystery and drama about whether (and how) Fischer would participate in the match, and this continued through the match.\n\nSpassky had a team. For 30+ years, since Mikhail Botvinnik had put Soviet chess on the map, the Soviets took it very seriously, with players putting their own interests aside in the name of advancing Soviet chess. Among other things, this meant some of the collusion I discussed earlier, where Soviet GMs would make quick draws against one another in tournaments to save their strength against Westerners like Fischer. Spassky had three top Soviet GMs with him to help prepare openings, analyze matches, etc. Fischer had Bill Lombardy, who was a GM (a weak one) and a Catholic Priest. Lombardy was there mostly to keep Fischer calm and focused, as his ability in chess paled in comparison to Fischer. Fischer had a lawyer accompany him (Paul Marshall) and a representative from the U.S. Chess Federation (Fred Kramer), but Fischer spent most of his time alone.\n\nFischer was paranoid. Part of this was likely mental illness, but part of it was probably warranted. The FBI had spied on Fischer's mom (a Communist sympathizer) and Fischer for years. He believed that the Soviets would try to kill him or otherwise seek to incapacitate him. I'm not aware of any effort on their part to do so, but it would not surprise me. After losing this match and signaling a willingness to defect to the West, Boris Spassky suffered under the hands of the KGB, who, among other things, tried to get him to contract a sexually-transmitted disease by infecting his girlfriend's undergarments. Fischer would also, due to his religious beliefs, isolate himself (notably on weekends). So Fischer trusted almost no one, and his illness would negatively impact his participation in this match (consider the negotiation around lights and cameras) and effectively ensure this was his last serious match ever (because he refused to ever compete again until the 1990s when a lucrative proposal pulled him briefly out of retirement).\n\nNow you ask if the match was widely regarded. For a chess match, the coverage in the U.S. was unprecedented. Public Broadcasting Services (PBS) aired the matches live on television. Of course, without cameras in Reykjavik, the moves were related to chess master Shelby Lyman, who displayed them on big boards and spent up to 5 hours providing commentary on each game ([source](_URL_0_)).\n\nThere are many, many books on Fischer and this match, but here are a few I would recommend:\n\n*Endgame: Bobby Fischer's Remarkable Rise and Fall – from America's Brightest Prodigy to the Edge of Madness* by Frank Brady. Start with this one--it's by far the best biography of Fischer, from someone who knew him personally.\n\n*Bobby Fischer Goes to War: How the Soviets Lost the Most Extraordinary Chess Match of All Time* by David Edmonds. This places chess into the broader context of the cultural Cold War.\n\n*A Psychobiography of Bobby Fischer* by Dr. Joseph G. Ponterotto. This is who I defer to for psychiatric diagnosis. Ponterotto also examines Fischer's early history with psychiatrists, including a racy accusation that the chess club of New York avoided recommending therapy for a young Fischer in order not to blunt his potential.\n\n*The KGB Plays Chess: The Soviet Secret Police and the Fight for the World Chess Crown* by Boris Gulko and other GMs who defected from the Soviet Union. If you want a story about the KGB sprinkling Chlamydia bacteria on Spassky's girlfriend's undergarments, this is your book.\n\nBonus--The current world champion is the Norwegian Magnus Carlsen. Carlsen rose to prominence at an early age, and has dominated chess for several years now. But unlike Fischer, he seems well adjusted and even in tune with new media, including [some live streaming](_URL_1_)."
]
}
|
[] |
[] |
[
[
"https://www.nytimes.com/2019/08/20/obituaries/shelby-lyman-dead.html",
"https://www.youtube.com/watch?v=gA7AfpLY2YE",
"https://www.youtube.com/watch?v=xXiVpFE3Zs0"
]
] |
|
1h3j34
|
How exactly were Roman leaders "hailed as Emperor?"
|
I just got through "The History of Rome" podcast, and I noticed how often Duncan describes various eminent Roman leaders being "hailed as Emperor" (or Caesar, or Augustus) by their troops (with varying degrees of feigned or genuine spontaneity). Was this just as simple as a general leaving his tent in the morning and being greeted by cries of "Imperator?" I feel like there must have been a more elaborate procedure to something as weighty as declaring someone absolute ruler of a massive empire. How did the process vary over the centuries of the Empire's existence?
Thanks.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1h3j34/how_exactly_were_roman_leaders_hailed_as_emperor/
|
{
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"caqtug2"
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"text": [
"No, it was more or less just being hailed as \"Imperator.\" The title, until the Principate, was an incredibly great honor and the troops wouldn't just confer it on anybody. Most likely, after some great victory, no doubt in camp after the general had taken the lists of casualties and recieved the enemy prisoners, the troops would resond with the ritual phrase \"Ave Imperator!\" which was only used with someone who had been awarded the title. Therefore to greet him with that phrase was the same as awarding him the title. Throughout our texts we find that soldiers \"hailed the general as imperator\" and boom, he's now imperator and he gets to put it on letters and on his tomb and so on. He also gets additional influence.\n\nWhile in the early days it might have been just that easy (although the title was *very* rare early on), some time before Caesar's time the Senate had to ratify the nomination for the title, as with every title. Troops following Marius and Sulla often just hailed their general as imperator after even the easiest victories, presumably for added status, and the Senate wanted to cut down on this and to make sure that only people they liked got the coveted titles. This plan fell through when Pompey and Caesar took control of the Senate with the (illegal) Triumvirate, but it also allowed someone like Cicero to attain the title of Imperator, awarded to him by his troops and confirmed by the Senate following a fairly small victory when he was governor of Cilicia."
]
}
|
[] |
[] |
[
[]
] |
|
5k6200
|
helium is non-renewable, but in most cases (as far as i know), it is used as is and not converted into anything else. why can't we just keep helium in something that contains it better, and doesn't allow it to escape to the atmosphere?
|
And I do understand that we have another ~250 years of helium in reserve, and that the U.S is selling of its stockpile, but why are we using it so brashly, versus making more airtight applications?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5k6200/eli5_helium_is_nonrenewable_but_in_most_cases_as/
|
{
"a_id": [
"dblkuay",
"dblokqm"
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2,
4
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"text": [
"Why are using a finite resource so carelessly? Balloons and funny noises.",
"We do. Labs always recycle their helium. When you use helium, you're incentivised to pump it back into a storage tank. But it's still a fairly cheap thing, so normal consumers work based on that."
]
}
|
[] |
[] |
[
[],
[]
] |
|
37p6ac
|
Where does the money come from to make rich people ever richer (without the poor becoming much poorer)?
|
I don't know the least thing about economics. That may be the reason why I fail to see how rich people can become increasingly rich without necessarily taking ALL their newly gained wealth from the middle classes and the poor (who, as far as I know, don't get increasingly poorer). If it's a matter of just printing new money, wouldn't that make a single bank note represent less value than before so that the rich aren't *actually* richer? So, my question is: where does that new wealth come from? Are there alien donors? I would appreciate a very simple answer. I'm not more informed than the average twelve-year-old.
|
askscience
|
http://www.reddit.com/r/askscience/comments/37p6ac/where_does_the_money_come_from_to_make_rich/
|
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"text": [
" > where does that new wealth come from?\n\nWealth doesn't come from the amount of money in circulation. It comes from our capacity to produce real goods and services.\n\nIf we found a way to double our production of iron ore, for example, every production process using iron would become cheaper, consumer goods would be cheaper, and therefore the rich and poor will both be richer at the same time.",
"It is a bit hard to answer this question if you have no prior knowledge on economics. But since you stated you have no prior knowledge ill try to explain it from the bottom up.\n\nCurrency gets its value from people believing it has value, And also from governmental enforcement. Governments do not just print money as they please, there are consequences that will drive the worth of each bill down, this is usually what we want to avoid.\n\nCurrency is just a medium to value and exchange goods/services ETC..\n\nThe Rich don't have to make their money from the poor, new \"wealthy people\" can get build their wealth from taking small chunks from other \"wealthy people\". Such as a real estate broker.\n\nLike someone else stated, if we suddenly engineered a method to produce surpluses of electrical energy everyone would get richer in the sense that everyone can afford more of it, or have to give up less to get the same amount.\n\nBasically if you have something that others want, you can amass wealth(as in, people are willing to give you some of their wealth in exchange for your goods/services). Of course this isn't the only way to obtain wealth, you can amass wealth from a slew of other ways such as taking advantage of others mistakes in valuing goods and services.\n\nWhen you amass wealth, usually you contribute to society/economy, you offer something that many people want and are willing to pay for. Whether that is for everyday needs such as Gas/food, or whether it is for leisure like buying the book 50 shades of grey.\n\nWealthy people aren't a negative impact to an economy if they contributed to it. Example Bill gates, Microsoft has changed the world, computers have made its way into every part of our lives, Bill gates has consistently been the single the richest person on earth because he has created something that everyone wants and is willing to give some of their wealth to obtain it.\n\n----\n\nYou should think of wealth as the ability to afford goods/services etc instead of a Dollar amount. For example $1000 could get me a thousand apples, or 300 Gallons of Gasoline, or two months of rent, or five months of electricity, or that new Apple Iphone product.\n\nA simpler way to understand this is if 10 people were stranded on an island. Bob starts spending hours each day picking apples from trees, Steven spends hours a day cutting trees for fire wood, Sally spends hours a day fishing... ETC.. Sooner or later they can amass a surplus, then they start trading their goods with each other via barter trading( Sally wants 10 apples for 1 fish). \n\nBring a new person to the island, now the question is how does he/she obtain wealth? Lets say this person has something to offer that everyone else wants such as a cigarette lighter to make fires in an instant rather than spending hours via friction. He/she would amass wealth pretty quickly.\n\n\n",
"Wealth comes from production not money, all the money in the world is only worth as much as it can buy. That said, there are three possible ways individual wealth can increase. Either production rises and everyone gets a share so everyone gains wealth. Or production rises but only some people get the gains and only their wealth increases. Or production does not rise, then for some to gain wealth others must lose wealth."
]
}
|
[] |
[] |
[
[],
[],
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] |
|
1x30w3
|
how does evolution and the big bang disprove existence of any god?
|
I believe in evolution and the big bang and am not a religious man at all but I don't see how these events are proof that there couldn't be any greater force behind them.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1x30w3/how_does_evolution_and_the_big_bang_disprove/
|
{
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"cf7mz1l"
],
"score": [
2
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"text": [
"If you are referring to the Nye/ Kent debate, they were discussing only between evolution and creationism, not the existence of a god.\n\nBesides that its really a matter of personal belief on the subject. If you think there is something behind it then sure, there is. But if you think there isn't anything behind it, fine, there isn't. Its really just a personal opinion at that point."
]
}
|
[] |
[] |
[
[]
] |
|
6qdb9x
|
Why is Earth's Moon so nice and round while other moons like Phobos and Deimos are weird ugly rocks?
|
Also, are there different classes/types of moons or every moon is a moon and that's about it?
|
askscience
|
https://www.reddit.com/r/askscience/comments/6qdb9x/why_is_earths_moon_so_nice_and_round_while_other/
|
{
"a_id": [
"dkwp2rp"
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"text": [
"If an object is above a certain size, its own gravity will smoosh it into a sphere. Below that size, the structural rigidity of the rock or ice making up the object will resist the smooshing of gravity, leaving it jagged or potato-like. The [\"potato radius\"](_URL_0_) is around 200-300 km, much bigger than Mars' moons but much smaller than ours. The asteroid Vesta is sort of on the cusp."
]
}
|
[] |
[] |
[
[
"https://arxiv.org/abs/1511.04297"
]
] |
|
e6tgul
|
what's the difference between having a type and fetishizing?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/e6tgul/eli5_whats_the_difference_between_having_a_type/
|
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"text": [
"It’s not a good black and white distinction, but generally, having a type is just kind of a subconscious preference for certain traits. Fetishization goes far beyond that. Realizing that you have a preference for redheads is one thing. Being attracted to people purely on the basis of their red hair and nothing else is more fetishization.",
"There's a clinical definition of fetish, and that is to not be able to derive sexual pleasure or gratification without that fetish element. Like if you have a foot fetish, you need feet to become sexually stimulated, it's not just going to be an element you happen to enjoy. Lots of people might have opinions about feet, and find, for example, a woman in high heels to be attractive. But a foot fetishist is not going to be attracted to a woman without the element of feet. Also, a fetish involves a non-sexual aspect as causing sexual gratification. Like getting a hard on from seeing an amputated limb or from seeing a dead person. The aspect of them being dead is the fetish, the appearance of them while dead (clothing, hair color) is the type.",
"\"Fetish\" has a scientific definition. Technically a fetish something you HAVE to have in order to get aroused that is not part of normal biological reproduction. If you are a dude with a shoe fetish, you HAVE to have shoes involved or you cant get aroused."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
3scgc4
|
why are we in $19 trillion dollars debt? and how do we pay it back? is it possible to have millions of americans paying something every month until the debt is paid off?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3scgc4/eli5_why_are_we_in_19_trillion_dollars_debt_and/
|
{
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],
"text": [
" > Why are we in $19 trillion dollars debt?\n\nBecause the federal government has been borrowing (more specifically, selling bonds) for a long, long time.\n\n > And how do we pay it back?\n\nBy collecting tax revenues and/or borrowing more to pay what we owe. The governments makes payments *very* regularly, and has never missed a payment.\n\n > Is it possible to have millions of Americans aying something every month until the debt is paid off?\n\nSure, but why bother? U.S. citizens have no obligation to repay that money; the government does. Granted, the government may ultimately choose to increase tax revenues and/or print money to pay for its debts, and both of those things would hurt the average U.S. citizen. But the government can always do that anyway, whether we give it extra money or not.\n\n > I meant a couple of millions that would be willing to pay something every month to catch up the debt we are in.\n\nThat's $9.5 million for each of those two million people. That's a staggering sum. If you stretch that out over four years (for example) that's still about $198,000 per month per person. (And that's assuming you could stop the clock on interest/additional borrowing, which is itself an absurd concept.) There simply aren't 2 million people with that kind of cash."
]
}
|
[] |
[] |
[
[]
] |
||
5ka3v2
|
How does a ribosome understand which exact protein goes with a corresponding codon?
|
How do our cells understand the language of codons? What exactly makes a ribosome synthesize Methionine when it "reads" AUG or to stop when it reaches UAA, UAG or UGA?
|
askscience
|
https://www.reddit.com/r/askscience/comments/5ka3v2/how_does_a_ribosome_understand_which_exact/
|
{
"a_id": [
"dbmw0sv"
],
"score": [
11
],
"text": [
"There are transfer RNA molecules which have 3 base pairs which complement the codons in the DNA. Each transfer RNA of a particular codon is only able to carry one specific amino acid because of the arrangement of bonds and polarity, etc. The ribosome doesn't \"know\" anything, it's just that the chemistry of transfer RNA is highly specific."
]
}
|
[] |
[] |
[
[]
] |
|
9usw4a
|
i have to teach 6th graders about investment and i want to talk to them about bonds, so i looked up the definition, and i have no clue what it's talking about. any help?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9usw4a/eli5_i_have_to_teach_6th_graders_about_investment/
|
{
"a_id": [
"e96qzg7",
"e96rnup",
"e96ryrx",
"e9771sz",
"e97c7en"
],
"score": [
5,
3,
63,
5,
2
],
"text": [
"Bonds are an agreement that if you give money to someone today they will then give you more money later.\n\nBonds are mostly issued by governments and corporations.\n\nThey are one of many ways the financial system achieves its purpose: moving money from those that have it but don't need it right now to those who need it right now but don't have it.\n\n",
"When you buy a bond you lend money to the government or a company. They eventually pay it back and give you extra money called \"interest\" to say \"thank you!\"",
"Say I borrow $100 from you. I write down that I owe you $100 on a piece of paper. That piece of paper is the bond. At some point in the future, I owe you the $100 I borrowed from you back. I am called the issuer of the bond because I wrote down the IOU on the piece of paper. You are the creditor aka the lender.\n\nNow say that you don't want to lend me the $100. You need it for something else. So I make you a deal. I'll borrow $100 from you today, but in 7 days, I'll pay you back $110. We write that on the bond. The extra $10 is called interest, and the 7 days is the maturity date of the bond aka the day I promise to pay you back.\n\nNow say you need your money back right away. But I don't have it. Instead, you find a third person and, they give you 100 or so dollars in cash in exchange for the IOU. Then I owe them the $110. They might charge you a little extra because they got you out of a bind. This is called selling a bond.\n\nFinally, say you trust me to give you back the money. You are confident that I will pay back the $110. Then things are great. But let's say you start to get nervous that I won't be able to pay you back. You can sell the bond for less than the face value. So if the IOU says that it's for $110, you can sell it for $70. Then you are guaranteed to get $70 instead of taking the chance you get nothing. For the other person, they are taking on the risk, but there is a chance they'll make $40.",
"I’m a Finance Major: \n\nELI5: A company or government needs to raise money. One way is to sell a bond. What’s a bond? A bond is an IOU they will sell to you. You pay them $1,000 today (all bonds have a face value of $1,000). \n\nLet’s say the bond is for 10 years (the time until you get paid back is the maturity). In 10 years you get your $1,000 back. But they will also pay you what’s called a “coupon”. The coupon is the interest they pay you until maturity. This coupon could be paid semi-annually or once a year. If the bond has a 7% annual coupon, that means they will pay 7% of the face value (so $70) a year. \nSo you give $1,000, receive $70 every year for 10\nyears, then in year 10 at maturity you receive your $1,000 back. \n\nOther thoughts: U.S. Government bonds (T-Bonds, T-Notes, T-Bills) are considered the safest, least riskiest investment there is. Why? Because the only way you aren’t getting your money back is if the U.S. government goes bankrupt. And frankly if that were to happen we would have a lot more to worry (as the world would be in total economic despair). You can trade your bonds before maturity to others, but the value depends on a few different things (interest rates, time to maturity) that I doubt a 6th grader would fully grasp. ",
"If you don’t feel you have a good grasp on the concept maybe look for some good short videos to show? Like [this](_URL_0_) maybe?"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[
"https://youtu.be/IuyejHOGCro"
]
] |
||
5dwg4v
|
Could Black Holes be Entropy Recyclers?
|
This is probably a stupid idea, but I'm in Chem II right now and just learned about entropy.
On the molecular level, entropy increases with the number of microstates possible where a microstate is defined by the number of possible variations of speed, position, rotation, and vibration a set of molecules can have. So, for example, if you have ten molecules in a small container and release them into a big container, the number of possible states has increased for those molecules, as they can be in a much greater number of physical positions in the larger container than they could in the smaller. Thus entropy has increased.
My text book concludes that as the number of molecules increases, as temp increases, and as volume increases, entropy increases because each of these attributes lead to more possibilities of position, direction of movement, spin, etc for the system to have (and thus more disorder).
This made me think about black holes. Molecules are so dense in a black hole, that I'd imagine entropy decreases. They have practically zero ability to move anywhere, they're essentially in a smaller container with fewer possible physical locations for them to be in, and in general they're more highly organized.
So how stupid of an idea is this?
|
askscience
|
https://www.reddit.com/r/askscience/comments/5dwg4v/could_black_holes_be_entropy_recyclers/
|
{
"a_id": [
"da802yf"
],
"score": [
19
],
"text": [
"It's not stupid to think black holes have low entropy, on the basis of general relativity alone everyone should agree. What should be worrying you however is this would violate the second law. If you throw high entropy states into the black hole, their information is destroyed and entropy is lowered. That's bad. This is actually the black hole information loss paradox, thinly disguised.\n\nTurns out in a quantum theory of gravity black holes have a large, in fact huge entropy. That of a black hole is the largest possible entropy you can fit in that volume. And this is a result in semiclassical gravity, meaning it is true no matter what, indipendently of which theory of quantum gravity is the true one. However identifying the microstates in which this entropy is stored is a responsibility of the specific theory of quantum gravity.\n\nWhere could this entropy be stored? Probably, it's in the horizon (there are relatively simple arguments you can make to convince yourself this is probably the case). I'm going to give an example of one scenario in string theory, which in itself is one theory of quantum gravity. According to string-inspired black hole complementarity, as seen from a far away observer the black hole actually ends at the horizon, which is in truth a Planck-thick, Planck-hot boiling membrane. The membrane holds the microstate that give the large entropy, and strings evaporating off from it form Hawking radiation. There is a complementary, simultaneous picture in which the black hole is instead a (warm) D-brane in flat spacetime, on which open strings can attach. Then the microstates are those of open strings on the brane. These two pictures are both correct, but for different observers."
]
}
|
[] |
[] |
[
[]
] |
|
1ieplk
|
How much have firearms changed over the last seventy years?
|
There have obviously been a lot of different fire arms designed and produced since the end of World War 2 but to my knowledge nothing has really 'broken the mold' since the invention of the assault rifle and the serious development of bullpup weapons.
So what has actually happened in the last seventy years of firearms development?
(I'm not too interested in ammunition, just the weapons themselves)
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1ieplk/how_much_have_firearms_changed_over_the_last/
|
{
"a_id": [
"cb3qy7y",
"cb3r1q6"
],
"score": [
3,
5
],
"text": [
"Modern weapons are more ergonomic, reliable, and accurate due to improved manufacturing techniques. They are lighter and produce less recoil. \n\nA lot of this improvement has come in the last 20 years. You would probably have more luck posting this in a firearm-oriented sub like /r/guns.",
"Not all that much has changed in the underlying mechanics of firearms since WW2, its been more about refining the technology we currently have. Sure, there have been experiments in case less ammunition, such as with the G11 back in the 70s, but if you took someone from 1944 and gave them some examples of modern firearms, they wouldn't be at all confused in how to get them working. Even 1900 I would say. For the internals, roller-delayed blowback was developed in the 1940s for the MG-42, and is, I would venture, the most recent self-loading mechanism developed to see widespread use. HK makes use of it in the G3 and MP5 for instance.\n\nIf I had to peg the major developments in firearms over the past century (I know you asked post-1943, but a lot of these kind of span across that mark due to WW2), there are four.\n\nWidespread acceptance of semi-automatics. They were developed in the late 1800s, but semi-auto pistols didn't start to gain traction until the early 1900s, and semi-auto rifles didn't start to become common for military use until the 1930s/40s (The French MAS Mle. 1936 was the last new design bolt action rifle developed for regular military issue).\n\nThe development of man portable automatic weapons. This started in earnest during WW1. The BAR saw limited action, and submachine guns started to be developed, the first being the MP18 put into use by the Germans. Again, it was World War II that really brought in widespread usage.\n\nThe success of the submachine gun and the overkill of the traditional battle rifle however led to the development of the Assault Rifle, initially with the StG-44 (MP-43 or MP-44). It introduced the use of an intermediate cartridge into a man portable, magazine fed automatic weapon. This basic concept still is the basic military arm for pretty much all nations armies in the world today.\n\nSince then, as you said, nothing has broken the mold, at least as far as widespread usage is concerned. Bullpups are one, but I would venture that the biggest development in firearms since the assault rifle was the Glock. It didn't rewrite the book on firearms, but Glock did bring about acceptance for the use of polymers in firearm design."
]
}
|
[] |
[] |
[
[],
[]
] |
|
spbmv
|
Is the idea of the subconscious mind an actual scientific concept or is it just a model used in philosophy and psychology to help describe mental processes?
|
If its more than just a model, what, in terms of evolution, would be the advantage to having a hidden and generally inaccessable (for lack of a better term) part of our brain?
|
askscience
|
http://www.reddit.com/r/askscience/comments/spbmv/is_the_idea_of_the_subconscious_mind_an_actual/
|
{
"a_id": [
"c4fu0cy",
"c4fzxs1"
],
"score": [
2,
3
],
"text": [
"The brain does lots and lots of processing which we're not consciously aware. Calling this 'subconscious' is a reasonable terminology, and one which is standard within some literatures.",
"Don't lump psychology in with philosophy. One is science, one is not. Much like consciousness, [subconscious](_URL_2_) is not used in research or academic settings. \n\n\nI think you're asking about automatic or (at times) \"unconscious\" processes. Maybe try to read up more on the divisions of the [autonomic nervous system](_URL_1_) and even some behavioral phenomenon like [priming](_URL_0_)."
]
}
|
[] |
[] |
[
[],
[
"http://en.wikipedia.org/wiki/Priming_(psychology\\)",
"http://en.wikipedia.org/wiki/Autonomic_nervous_system",
"http://en.wikipedia.org/wiki/Subconscious"
]
] |
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