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9eky0e
|
how the government manages to double check every single person’s taxes
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9eky0e/eli5_how_the_government_manages_to_double_check/
|
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"They don't. The IRS does keep a record of whatever information is reported to it, so if a user falsifies a return by inputting incorrect data (or omitting data), a mismatch could trigger further investigation, but other than that, the IRS doesn't automatically know if someone is making money \"off the books\".\n\nLikewise, claming a credit you aren't eligible for may trigger further review.",
"Having to file your own taxes is not necessary. The IRS already already has all that information. H & R Block and TurboTax (and others like them) pay lobbyist to make it necessary so you use their services. It's a big scam."
]
}
|
[] |
[] |
[
[],
[]
] |
||
361w2j
|
why does any form of dental work in the usa cost so much money?
|
Is it just because there's no healthcare system and they know that you're in so much pain that you will pay literally anything to make it stop, or is there a less sinister reason?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/361w2j/eli5_why_does_any_form_of_dental_work_in_the_usa/
|
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"It is mainly because of insurance. There is a huge mark up for the procedures because they know insurance will pay the majority if not all of it. That screws over many people who's insurance only covers certain procedures or a certain maximum each year though. There are very few medical procedures where the costs of performing the procedure/materials/labor etc is fairly priced. "
]
}
|
[] |
[] |
[
[]
] |
|
3qri7r
|
why hasn't the windows source code leaked
|
Of all the thousands of employees Microsoft has, no one has leaked anything?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3qri7r/eli5_why_hasnt_the_windows_source_code_leaked/
|
{
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"Microsoft has thousands of employees but very few even work on Windows and very, very few have access to source code.",
"Well people have leaked the actual OS on piratebay and the like. But the source code of an OS as complicated as Windows is massive, and heavily copyrighted. This, paired with NDAs on pretty much every employee who would even come close to being in contact with it and people liking their jobs makes people disinclined to leak it.\n\nAnd then after all of this, what would someone do with all of the source code? Yes you could rip the OS and make your own, but why all the work when Linux is an option or just a free version is."
]
}
|
[] |
[] |
[
[],
[]
] |
|
22izrx
|
why has the price of computers stayed roughly the same over time, while the technology that goes into them has improved so much?
|
Is it really just that the costs to make them have gone down or something else?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/22izrx/eli5_why_has_the_price_of_computers_stayed/
|
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"My first computer was damn near $5,000 brand new. My first laptop was almost $2,000. The price of computers has dropped dramatically over time.",
"Because while the cost to produce X bytes of storage or X flops of computing power has dramatically decreased, that has resulted in us packing more and more of that technology into our computers. \n\nBuying a computer with the same specs as one that was top of the line 10 years ago would be astronomically cheap. The price stays the same because this year's high-end machine is WAY more powerful.",
"Prices have decreased dramatically over time for virtually any computer form-factor you can name. It is just that some, such as the desktop PC, have now reached a point where further declines are not dramatic. All of the \"low hanging fruit\" for cost reduction has been wrung out, and further reductions are difficult to find. They've also gotten to the point where the profit margins are so slim that it is almost impossible for a producer to reduce prices without becoming unprofitable. \n \nAt the same time, the progress described by [Moore's Law](_URL_0_) has allowed more and more speed and functionality to be packed into those computers. \n \nIf there was a market for computers with the same functionality as existed 10 or 20 years ago, we could make computers that are substantially cheaper than they are today. But virtually nobody wants to buy a machine like that. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://en.wikipedia.org/wiki/Moore%27s_Law"
]
] |
|
4wgdp5
|
why do wood and metal shavings curl up?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4wgdp5/eli5_why_do_wood_and_metal_shavings_curl_up/
|
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"This is my educated guess:\nWhen you produce a shaving, you don't produce a symetrical rectangular cuboid. If you looked at it from the side, you would actually have a flattened trapezoid shape. Where the angled bits are the places where your cutting impliment entered and exited the material. The material pushes against itself a certain amount (otherwise it would just collapse into nothing), On the angled bits this pushing force isn't inline with the length of the shaving. This force causes the shaving to curl. I'll see if I can draw a diagram.\n\nDiagram:_URL_0_",
"I'm new here and also not to 100 percent sure my explanation is correct but I imagine it is the same principle occurring when you make the curly ribbons when wrapping presents. By pulling the scissors past one side of the ribbon you pull the material and essentially lengthen the material creating tension between the two opposite sides. The same happens when cutting wood or metal. The swarf is cut and thereby the \"cut\" side is elongated. Therefore the swarf experiences tension and curls towards the uncut side... hope this helped. ",
"Because of the shape of your tool. [You cause deformation in that direction](_URL_0_) depending on the angle alpha. \n\nA sharp point (alpha < 30°) will produce long, straight shavings. A big alpha (you can go > 90°) will produce short and curly shavings. \n\nThe sharp tip will cut smoothly and with low cutting force, but it's fragile and the long shavings can actually be dangerous to the machine and the person operating it. A bigger alpha is more robust and less dangerous. The increase in cutting force is very significant though, so you want it somewhere in between (45-60° mostly). \n\nThe shavings are also defined by the speed and thickness you cut, and if needed you can add extra roughness on your cutting material to break the shavings. "
]
}
|
[] |
[] |
[
[
"http://imgur.com/a/R8m0M"
],
[],
[
"http://i.imgur.com/Ysjb2sV.png"
]
] |
||
1623mt
|
what other types of experiments are they performing at the large hadron collider, now when the higgs boson is confirmed?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1623mt/eli5_what_other_types_of_experiments_are_they/
|
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"**Disclaimer**: I work for the communication group of one of the LHC experiments ([CMS](_URL_1_)) but I am not a physicist myself. So, take everything I say with appropriate amounts of salt. Also, this will be a little long (and not quite as simple as ELI5 requires, but I'm trying my best). TL;DR at the bottom, as usual.\n\nSome vocabulary, before we get started:\n\n* **LHC**: The Large Hadron Collider is the main accelerator and there are smaller accelerators that feed the protons into the LHC. 27 km in circumference, the LHC accelerates protons to nearly the speed of light before colliding them at four locations along its own ring. There are gigantic detectors built around each of these collision points, designed to detect the debris of the collisions with very, very high precision. See a diagram [here](_URL_5_).\n* **Detectors**: There are two general-purpose detectors (CMS and [ATLAS](_URL_4_)), and two specialist ones ([LHCb](_URL_7_) and [ALICE](_URL_9_)). The best way to be introduced to the detectors is through the [LHC Rap](_URL_0_)! A full list of LHC detectors can be found [here](_URL_3_).\n* **Experiments**: Used interchangeably with \"detectors\".\n* **Collaboration**: Each detector is run by an international collaboration of thousands of physicists from hundreds of institutions in dozens of countries. The names of the detectors are used to refer to the collaborations themselves. For example, see [this map of CMS institutes and the projects they work on](_URL_1_content/cms-collaboration).\n* **The [Standard Model](_URL_10_) (SM)**: It is a theory of elementary particles that has been shown to be correct to very high accuracies.\n* **Higgs boson**: When you read the term \"Higgs boson\" in newspapers, they often refer to the particle as described within the framework of Standard Model. There are other theories (such as extensions of the Standard Model) that also predict the existence of a Higgs boson (or, in some cases, many!).\n\nNow, the LHC is going to operate for over 20 years. Its only goal is not to verify the existence of the SM Higgs boson –– this is only one of the preliminary objectives (more on this below). In July ~~this~~ last year, CMS and ATLAS announced that they had discovered a boson whose properties are consistent those of the SM Higgs. (If you are so inclined, here are the statements released at the time [by CMS](_URL_1_news/observation-new-particle-mass-125-gev) and [by ATLAS](_URL_11_).) What this means is that there are very precise predictions for how a SM Higgs would behave, and the particle that was observed appears to agree with these predictions. Of course, there can still be subtle deviations that need to be measured if they exist. More data are needed to confirm whether the new particle is indeed a SM Higgs boson; so far, we're saying it's a Higgs-like boson.\n\nHow deviations are measured is interesting. Particles produced in LHC collisions are usually unstable and they decay into other particles, until you are left with stable, elementary particles (photons, electrons, muons etc.). So, the SM Higgs could, for example, decay into two Z bosons, which further decays into (say) two electrons each. Or the SM Higgs could decay into two photons. Just as a change machine can give you change for 10 Swiss Francs (yes, let's keep it local) in different combinations (5, 2, 2, 1 or 2, 2, 2, 2, 2 or 2, 2, 2, 1, 1, 1, 1), a particle can decay in different ways, each such \"decay channel\" having its own probability. If, for example, these decay rates are different from those predicted by the Standard Model, we will have found \"new physics\".\n\nSo what are some of the other questions we hope the LHC will answer?\n\n* Why do we live in a matter-dominated Universe? What happened to all the anti-matter?\n* Why is gravity so weak compared to the other forces? (The entire earth is pulling on it and yet you can lift a paperclip with a fridge-magnet.) Is this because there are more than just three spatial dimensions in our Universe?\n* Have we discovered all the elementary particles that are out there? (Supersymmetry, or SUSY, predicts that for every elementary particle there exists a heavier superpartner.)\n\nMore explanations on the big questions the LHC hopes to answer can be found on [this page on the CMS website](_URL_1_news/big-questions). I hope this helps!\n\n**TL;DR**: 1) The LHC experiments have reported the discovery of a Higgs-like boson (not *the* Standard Model Higgs boson) and more data are needed to confirm its true nature. 2) The LHC has a long lifetime and there are many other searches being performed by the LHC experiments in addition to measurements designed to test the predictions of established theories such as the Standard Model.\n\nEdit: Missing \"the\" in the first line. Oops!"
]
}
|
[] |
[] |
[
[
"http://www.youtube.com/watch?v=j50ZssEojtM",
"http://cms.web.cern.ch/",
"http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev",
"http://public.web.cern.ch/public/en/lhc/LHCExperiments-en.html",
"http://atlas.ch/",
"http://upload.wikimedia.org/wikipedia/commons/7/74/LHC.svg",
"http://cms.web.cern.ch/news/big-questions",
"http://lhcb-public.web.cern.ch/lhcb-public/",
"http://cms.web.cern.ch/content/cms-collaboration",
"http://aliceinfo.cern.ch/Public/Welcome.html",
"http://simple.wikipedia.org/wiki/Standard_Model",
"http://www.atlas.ch/news/2012/latest-results-from-higgs-search.html"
]
] |
||
b6ncjm
|
what makes typos like "it's" in place of its so common?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b6ncjm/eli5_what_makes_typos_like_its_in_place_of_its_so/
|
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"People mistakenly go down the route of thinking to form a possessive by adding apostrophe + s which is correct in most cases. (Except plurals.) It seems a natural thing to do.\n\nHowever the impersonal \"its\", like \"his\", \"hers\" and \"theirs\" are possessive pronouns that don't have an apostrophe.",
"It's not truly a \"typo\". A typo is when you try to type one thing, and mistakenly type another. \n \nSometimes the two \"its\" can be a typo in that it is caused by autocorrect. \n \nBut the main reasons are (a) many people don't seem to remember that possessive its needs no apostrophe, and (b) a lot of people simply don't care about doing it right. Those aren't typos. ",
"Do you mean by phone keyboard autocorrect? It'll depend on the autocorrect algorithm, but they could get switched because \"it's\" is more commonly used than \"its\".\n\nIf this is what you mean, you might want to include autocorrect in the title instead of typo. Typos are committed by humans. Autocorrect errors are committed by computers."
]
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[] |
[
[],
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||
231cj6
|
why is a phone screen less expensive the a larger screen with the same resolution?
|
LG is bringing out a 2560x1440 screen on it's LG G3.
The phone will probably cost about the same as a PC monitor with a similar resolution.
I always assumed building a larger screen would be easier, and less expensive. I want High Res is my live... We've been stuck on 1080 for a long time.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/231cj6/eli5_why_is_a_phone_screen_less_expensive_the_a/
|
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"Well for one - size. \n \nBut you also don't have an apples to apples comparison - a phone has way more electronics and other parts than a desktop monitor.\n \nThe real reason for any price difference, is cause manufactures can charge whatever the fuck they want - based loosely on supply and demand, or what one is willing to pay.",
"When research is paid for, you can just sell it on same price. \n\nMore people buying - lesser price has to be individually paid for technologies and research. \n\nOr they are simply attempting to buy the market and estabilish their place on the market with lower price as an investment.",
"I was today shopping for a 27\" PC monitor. The cheapest 2560×1080 screen was 300 €, Asus 2560×1440 was 400 €. LG G2 was 399,90 €. In Finland the prices include 24 % VAT, LG G2 price is without any indenture service contract.\n\nIf and when LG G3 is out and in the shops, the prices of 2K monitors have gone down and the cheapest ones are well below 300 € and I'm probably shopping for a nice 4K monitor with G-sync.\n\nEdit: ninaj. Smtrhing."
]
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|
[] |
[] |
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[],
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|
80e53j
|
how do houseplants know what season it is?
|
How do houseplants know when it is time to grow and bloom and when to die back. I grow daffodils in my kitchen which is a pretty consistent temperature all year round however, without fail my daffodils will bloom in the spring and die back over winter. How do they know when to do this?
Edit: Thanks everyone for their responses. I understand how it works now.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/80e53j/eli5_how_do_houseplants_know_what_season_it_is/
|
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"They get varying amounts of sunlight every day. Short days = winter; and long days = summer. Temperature varies every day and swings over a large range. It's not as reliable as sunlight. Some plants, like cherry trees, do use ground temperature, but they bloom very early in the spring.",
"Usually by the amount of light/darkness they get. Many plants are either \"short-day\" plants or \"long-day\" plants. \n\n\"Short day\" plants are actually more accurately \"long night\" plants, in that they require more than a certain number of hours *without* light in order to get the signals to enter their reproductive life cycle. They've tested this by putting these plants in an isolated environment and turning on and off the lights at specific times. If you leave a \"short day\" plant in darkness for 13 hours but turn the light on for ten minutes in the middle of those 13 hours, it still won't bloom! This is because its internal clock resets when it gets hit with that light.\n\n\"Long day\" (short night) plants are exactly the opposite. They will start blooming only when they're exposed to less than 12 hours of darkness at a time.\n\nThe way this actually works is that plants have special enzymes called phytochromes that exist in two different molecular forms based on whether they're exposed to, essentially, brightness or dim light/darkness. Short day plants need a lot of the \"dark\" form of the enzyme to activate the genes necessary for flowering, so they can only bloom when longer nights allow the \"dark\" form to build up to high enough levels. Vice versa for the long day plants.\n\n[This is a good high-level summary](_URL_0_) ",
"I can't answer for most houseplants, but those of us over at /r/microgrowery know. Different light cycles and temperatures tell plants the seasons. With cannabis, the plant has two phases; Vegetative and Flowering. Vegetative is typically the early summer, and Flower is usually fall. Indoors, you can keep plants in Veg virtually indefinitely. This is because in the earlier part of the summer, the plant receives 14 hours of sunlight per day, and we can mimic that through artificial lights (Some like a 18/6 cycle, some like 24 hours of light per day). The plant has no reason to flower because it \"thinks\" it's early summer, so it just grows structurally and not at all for reproduction. Warmer temperatures also help for the same reason. \n\nOnce the plant begins getting less than 14 hours of light per day and slightly cooler temperatures, it \"knows\" that it's getting later in the year and begins to move to the Flower phase. Indoors, we just shorten the light cycle to 12/12 and drop the temperature a tiny bit to mimic the changing seasons. The plant begins creating pollen sacs or flowers to reproduce. Cannabis is a wind-pollinated plant, meaning that they do not rely on bees or other insects to spread their pollen, rather they \"pop\" pollen into the air and hope it spreads to a female plant. If a healthy female plant is pollinated, it will stop growing and focus on seeds, because it \"knows\" that the year has ended along with its own life cycle. When growing for product, the females are isolated and when they move into flower, the flowers get bigger and stickier and more proudly displayed because the plant \"knows\" that it needs to get pollinated before winter sets in.\n\nPlants never really \"know\" the seasons, but they react to them and rely on them to direct their own life cycles.",
"It's kind of the same the way our body knows when it's night or day: we use external cues called zeitgebers, like light.",
"They measure the amount of exposure they get to sunlight. Days are longer in the summer and shorter in the winter. It's called photoperiodism. I assume you have them next to a window where they get can get sunlight. If you had them away from all light with a sun lamp or something I'd guess they wouldn't know.",
"During the boom in oil in Pennsylvania in the mid 1800s, fires were burning which warmed trees enough that they reacted as if spring was happening even though it was the dead of winter -- they started to grow leaves, etc. So temperature seems to be a major factor. ",
"As the year goes on, the days get longer and shorter. A plant will bloom based on how much sunlight it gets per day. I have a christmas cactus that blooms when it detects shorter days (hence \"Christmas\")",
"Daylight length and daylight quality. In the full blown summer the days are long and the light is more in the blue spectrum, as summer is ending the daylight is shorter and more into the red spectrum.\n\nThat’s why you need blueish lights for growth (metal halide), and reddish light (high pressure sodium) for growing... ahem.... your tomatoes indoors. "
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] |
|
94b8r0
|
music and memory
|
I can only sing along to songs when the actual song is playing. Though ask me to sing it without the song playing, I can’t remember the lyrics. These can be songs that I haven’t listened to in years.
How does this work?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/94b8r0/eli5_music_and_memory/
|
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"Probably due to two things. 1) you’re need a cue to trigger the pattern that encodes the song in your brain, and 2) for whatever reason you’re unable to trigger the cue without the actual music playing, perhaps your brain isn’t wired to remember melodys to songs very well. But when you hear the melody of the song that triggers the information you have associated with that song. "
]
}
|
[] |
[] |
[
[]
] |
|
43jrxt
|
what happens to leftover campaign donation money after the election?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/43jrxt/eli5_what_happens_to_leftover_campaign_donation/
|
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"Here in North Dakota candidates are legally allowed to keep the leftovers for themselves. I wish I was kidding.",
"Here in Florida you have to either give it back to your donors or donate it to a recognized charity (501c3).\n",
"Legally you can either donate it to a charity, give it to another candidate to help them in their race, or you could save it for a future campaign. That is why some people hang in the presidential race so long because 3 million does go very far in a presidential race but it's probably enough to win a mayor or governors job.",
"Often candidates will keep their campaigns in existence throughout their tenure in office, partly because they fully intend to run again, but also because they will periodically wish/need to do something which is outside the realm of what they can pay for with public money. There is a whole host of ethics rules that limit how campaign staff and official staff can interact, etc. ",
"Entirely depends on the campaign (local, state or national). \n\nRight now in California, Governor Jerry Brown is sitting on $28 million he raised when last ran for re-election. Due to asinine term limits (LPT: if you want lobbyists to run your legislation, be in favor of term-limits), he can't run again and decided not to enter the race to replace Boxer as our senator.\n\nBrown wants to push for more early parole for non-violent (read: drug possession) prisoners and it's widely believed he is going to use that money to help push the public to vote for it. \n\nNationally, one of the reasons that many of the hopeless GOP candidates are still in the race is because they can take whatever donations they raise and use it to set up their own PACs and lobbying groups. It was my own theory as to why Cruz was running, because he has to be smart enough to realize that the general population will not elect someone that conservative. "
]
}
|
[] |
[] |
[
[],
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||
9novt1
|
what is the chomsky grammar heirarchy and how does it work?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9novt1/eli5_what_is_the_chomsky_grammar_heirarchy_and/
|
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"text": [
"As general background, this hierarchy is about classifying \"languages\". Languages here is a technical term that is not talking about actual human languages, but about collections of strings, where each string is a sequence of symbols. For example, all positive numbers in base-10 divisible by 10 form a language - the collection {'0', '10', '20', '30',...}.\n\nChomsky realized that one could classify these languages based on how powerful your computational model had to be to decide whether the sentences are valid - for the example above, this computer would say \"yes\" on '10', and \"no\" on '15'. Again, he was not talking about how fast literal physical computers had to be - he was talking about different hypothetical types of machines.\n\nThe four classes are Type 3, Type 2, Type 1, and Type 0.\n\nType 3 is the most basic form of language. To parse strings in this language all you need is a finite state automaton - a machine that has a *single* memory location, and looks at a *single* character at a time, and at each new character just checks whether that character is allowed based on a set of rules.\n\nType 2 is more complex - to parse these strings you need *infinite* memory, but you can have restrictions on how you look at the memory. In particular, you're only ever allowed to look at the *last* thing in your memory. You can imagine it as a stack of post-it notes - you can have as many as you want, but while looking at a single word in your sentence, you only have sight of the top post-it note,which you can remove, modify, or add another on top.\n\nType 1 is yet more complex, but the restrictions on computation are weird - you now have finite memory, but you can move through it arbitrarily. You can imagine basically a normal computer, into which you enter your string of character, and then all RAM outside of that string breaks, so the CPU is limited to that small amount of memory. The computer now has scratch space where it can write and remember stuff, but the scratch space destroys the information that was there before because you only have as much as the string.\n\nType 0 is the least restrictive - it includes all languages that any computer with *infinite* memory can eventually recognize.\n\nThese types are firmly nested in each other - all Type 3 languages are also Type 2, 1, and 0, all Type 2 languages are also Type 1 and 0, etc. This is more obvious in some cases than others.\n\nThere are also equivalent definitions for each to do with generating sentences in the language, rather than recognizing whether it's a valid sentence. This is what a \"grammar\" is - it is a rule set for generating sentences. There is a one-to-one correspondence between each of these types of computing machines and types of grammars that can make all those sentences, but the computing machine description tends to be easier to understand without a lot more background."
]
}
|
[] |
[] |
[
[]
] |
||
2sporp
|
why did the swiss national bank get rid of the swiss franc/euro exchange rate cap?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2sporp/eli5why_did_the_swiss_national_bank_get_rid_of/
|
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"cnrshq8"
],
"score": [
3
],
"text": [
"I just read an article about this: \nIt all revolves around the concept of supply and demand and what it takes to maintain a fixed exchange rate. In order for the Swiss to maintain a fixed exchange rate, they have to buy or sell euros. In 2011, they pegged their currency to the euro at 1.2 in order to impede disruptions in their economy as a result of the high demand for their currency as a safe asset during the financial crisis. When they did this, the SNB was buying euros to keep the currency stable. Now, there most likely isn't such a large demand for francs as we recover from the crisis so the SNB doesn't see the need to keep said peg. Also, the European Central Bank has announced their plan for stimulating the eurozone economy by pumping liquidity into the market, making the euro weaker. The weakening of the euro will also make it harder for the SNB to maintain the peg moving forward. Hope that helps a bit and here's the article I'm referencing: _URL_0_\n\n"
]
}
|
[] |
[] |
[
[
"http://www.businessweek.com/articles/2015-01-15/heres-what-the-swiss-central-bank-just-did-and-why-its-such-a-shocker"
]
] |
||
11qe5l
|
why does my buttcrack sweat much more than the rest of my body?
|
I just got done folding my laundry and my butt is swamped. I haven't perspired noticeably anywhere else on my body. Why?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/11qe5l/why_does_my_buttcrack_sweat_much_more_than_the/
|
{
"a_id": [
"c6or44r",
"c6orp9k",
"c6oskuj",
"c6oyzrp",
"c6p33yb"
],
"score": [
4,
9,
2,
2,
2
],
"text": [
"I would like to know this",
"Friction, no air flow, and it's one of the warmer parts of your body.\n\n\nCannot believe I answered that...",
"Friction (depending on your ass hair) and restricted air flow. ",
"Does it? I thought that sweat from the back kinda just gathered there.",
"Because you got a hot ass.\n\nButt seriously (last pun, I promise), your buttcrack sweats a lot because of a lack of air flow in that area, which combined with your body heat and butt hair causes sweat. It's like a greenhouse effect in your pants."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
1cwt1v
|
what do braces do other than just make your smile look better?
|
My brother just got braces and even though my family has spent a ton of money on my braces and will spend a ton more on my brother's, I still don't know what else they do other than just fix your smile. It seems like a pretty superficial thing to waste so much money on.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1cwt1v/eli5_what_do_braces_do_other_than_just_make_your/
|
{
"a_id": [
"c9kpn2h",
"c9kqkkw"
],
"score": [
3,
2
],
"text": [
"Most people get them exactly for superficial reasons. However braces have medical value in that they can fix serious issues with teeth not being aligned properly. When my SO was younger she had them put in to restore 70% of her chewing functionality for example.",
"When a child's jaw is too small for all his/her teeth, some teeth have to be pulled out so the remaining teeth have room to grow straight. The gaps left by the pulled teeth have to be closed, so braces are used. This also allows the dentist to align the upper and lower teeth. This is more than making your smile pretty: it makes chewing your food easier and it keeps your teeth and gums healthier."
]
}
|
[] |
[] |
[
[],
[]
] |
|
fy0j6z
|
how does putting an “x” of tape on glass protect it from breaking?
|
I just picked up a piece of glass I had cut at Lowe’s for a diploma frame. They put painter’s tape (that blue tape) all over the edges of the glass (so it won’t cut me I presume) and then the big “X” of tape on one side of the glass (diagonally from one top corner to the other bottom corner 2x to make the “x” shape), as I’ve seen before. What does this do? How does it protect it?
(I have no idea if this is physics, engineering, or what.. don’t judge).
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/fy0j6z/eli5_how_does_putting_an_x_of_tape_on_glass/
|
{
"a_id": [
"fmxjd1l",
"fmxjjl4",
"fmxjpy7"
],
"score": [
2,
8,
27
],
"text": [
"It’s so you can see that it’s glass, imagine two people stopped in front of an isle you wanted to go down, they are standing two metres apart and you’re looking at your phone checking prices or whatever online. Would you rather look up briefly and see a big tape X or walk into a huge pane of glass that you would almost certainly break?",
"It’s not for it to break it’s so if it does break it stays together back in the 90s race cars did it for their glass headlights.",
"It doesn't protect it. It's there in case you break the glass. In theory, the tape will hold the broken pieces together, making it easier to dispose of (and, again in theory, safer for you)"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
5pf7hv
|
japanese vs american automobiles
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5pf7hv/eli5_japanese_vs_american_automobiles/
|
{
"a_id": [
"dcqq85x"
],
"score": [
3
],
"text": [
"American cars used to be the hallmark of reliability. I think a variety of reasons contributed to the decline of quality in American cars. From an econ/financial perspective it just became too expensive to build quality cars. Labor costs for automotive companies kept going up because unions kept wanting more benefits and higher pay for less work. The companies can't redistribute the extra costs to the consumers because that will just drive them to their competition even faster so they did the only thing they could and cut down on quality."
]
}
|
[] |
[] |
[
[]
] |
||
1xrbl8
|
why do minor chords sound sad?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1xrbl8/eli5_why_do_minor_chords_sound_sad/
|
{
"a_id": [
"cfdyn7d",
"cfdzj2o",
"cfdzk2q",
"cfe1cx6",
"cfehmfg"
],
"score": [
3,
17,
2,
10,
2
],
"text": [
"Because the closeness of the first and second notes of the chord (technically called the \"root\" and \"third\" notes of the scale). \n\nIn a major chord, there are three notes between the root and third, which causes a pleasant-sounding resolve. In a minor chord, there are only two notes separating the root and third, which causes a sort of dissonance that we perceive as sad. ",
"Keyboardist / novice producer here. They don't always sound sad. It's in the way they are played. If you play them slowly, with pauses and expression, they can sound sad (cough cough Adele). If you play them rhythmically, they can sound (and excuse me for bringing it back to 2005 here) \"epic\" (_URL_0_) or even celebratory. (_URL_1_). It's all in how the music is played. I suppose that is related to speech patterns, people often talk more slowly and with greater expression when they're conveying something sad. In addition different series of chords, (chord progressions) can seem mellowing, uplifting, inspirational, happy, or sad. I can't explain why that is, only that many musicians simply have an ear for the type of mood they want to convey.",
"So musical notes produce wavelengths ([Here's an example with a C and G, or a perfect 5th, which usually sounds good or consonant](_URL_0_)), and some combinations can be more **dissonant** or **consonant**, meaning sounding bad and good respectively. When these produced wavelengths match up just right, it sounds good (consonant), but when they don't it sounds less than desirable (dissonant). So you're asking about major vs. minor chords, and the distinguishing factor is the major third and the minor third. So to break it down, the answer to your question is that the wavelengths produced by a major third line up better than that of a minor third. Source: I took an AP Music Theory Course and [this website](_URL_1_)\n**Edit - If you look closely at the C and G wavelengths, you can see that they line up; every fourth green wave lines up the same way with every third red wavelength**",
"**Most importantly, this is a common misconception. There is plenty of music written in a minor key that actually does not sound sad, although they are in a minor key.**\n\nIt's complicated to explain to someone who doesn't actually read music, so if I get a little too technical/not ELI5 here, sorry..:\n\nWith one note on a stringed instrument, it is made of several different notes.\n\n**For instance: guitar strings are E-A-D-G-B-E**\n\nThe A-string is made up of A-C#-E, which is your fundamental/root A, C# (which is a major third above the root), and an E (which is a fifth, for the non-music folk). When you build a minor chord, it's going to be built differently. An A minor chord, in comparison to A major, is A-C-E. There will be some kind of dissonance here which essentially clouds the sound of the chord. (I would suggest looking up the overtone series if you're interested in learning more about this!) This is some technical reasoning behind it that I could definitely add more to. It also has to do with the fact that, even subconsciously, we are looking for a resolution in music. As a musician, having something not resolve is the most annoying thing in the world. Nothing actually grinds my gears more. \n\nIt mostly has to do with history and the associations we make with minor chords and ranges culturally. For example, we can look at *The Theory of Musical Equilibration*. It is the idea that certain chords will evoke certain emotions from the listener. But chords aren't the only things that are to be taken into account here. A sad chord that is repeated and increases in volume might not sound as sad, but more angry or angsty.\n\ntl;dr it's a social thing and kind of a misconception because not all minor chords are sad.\n\nsource: 5th year music performance student. ",
"[This song in F minor.](_URL_0_)"
]
}
|
[] |
[] |
[
[],
[
"http://www.youtube.com/watch?v=LRLdhFVzqt4",
"http://www.youtube.com/watch?v=yYe6tmrFxbw"
],
[
"http://imgur.com/ZPjHkWN",
"http://www.musicmasterworks.com/WhereMathMeetsMusic.html"
],
[],
[
"http://www.youtube.com/watch?v=y6Sxv-sUYtM"
]
] |
||
cqi19b
|
what causes the helicopter sound when you roll down the window in a car going 40mph+? if another window is cracked or down it does not make this noise
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/cqi19b/eli5_what_causes_the_helicopter_sound_when_you/
|
{
"a_id": [
"ewwejtl",
"ewwek4b",
"ewweuxv"
],
"score": [
8,
2,
21
],
"text": [
"Helmholtz resonance. It is similar to blowing over an open bottle, but since the car is so big, the sound is low enough pitched that it is more of a violent fluttering than a sound. When you open another window, air does not compress/decompress in the car since the other window allows the pressure to equalize.",
"It’s a Venturi effect pressure equalization cycle. When you crack the window, the slipstream outside pulls air out of the vehicle creating a vacuum. When the vacuum exceeds slipstream pressure the pressure pops back, pulling outside air in, in order to equalize the pressure. Repeat 180 times per minute and the pressure oscillation creates the sound you hear.",
"Turbulence due to a pressure differential. Air is trying to get in and out of the same window so it does it in bursts.\n\nCrack another window and it's like poking a hole in the can of pineapple juice so it pours easier. Air gets in one window while pressure is released out the other."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
czea33
|
- how does the water level get so high during a hurricane? is it just the downpour of rain?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/czea33/eli5_how_does_the_water_level_get_so_high_during/
|
{
"a_id": [
"eyxt42f",
"eyxvarw"
],
"score": [
2,
4
],
"text": [
"If you're talking about the storm surge, hurricanes rotate counterclockwise (in northern hemisphere), all that wind pushes the water ahead of it. When that water reaches the coast, and especially if it happens at high tide, the water level will be higher.",
"The extreme low pressure of the storm causes water to dome upwards under the center of the hurricane where the pressure is lowest. This is why storm surge is highest around center of the hurricane\n\nThe rotating winds also help push water inwards towards the center of the storm\n\nThe water that makes up storm surge comes from the surrounding ocean. Sometimes before a severe hurricane arrives, the coastal waters recede to extremely shallow levels because the rest of the water is sucked under the storm\n\n_URL_0_"
]
}
|
[] |
[] |
[
[],
[
"https://en.m.wikipedia.org/wiki/Storm_surge"
]
] |
|
awkjd8
|
i don't get the "nobody:" meme format
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/awkjd8/eli5_i_dont_get_the_nobody_meme_format/
|
{
"a_id": [
"ehn5l1z",
"ehn6ihx"
],
"score": [
6,
7
],
"text": [
"I think it's like, the second person is responding as if the first person had prompted them, but nothing happened. Nobody said anything, and yet they still reacted",
"It's a variety of another meme format:\n\n > (somebody): (something relevant)\n\n > (somebody else): (reaction)\n\nHere, the `nobody: (blank)`refers to nobody saying anything, meaning that the second person is just doing something out of nowhere with no provocation or anything like that."
]
}
|
[] |
[] |
[
[],
[]
] |
||
2nps8x
|
why do babies babble from such an early age?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2nps8x/eli5_why_do_babies_babble_from_such_an_early_age/
|
{
"a_id": [
"cmfq9f2"
],
"score": [
2
],
"text": [
"Because they are attempting to replicate the sounds they are hearing in their environment. Over time the babble becomes closer and closer to the language apoken by the parents. Which is the first step of learning the language."
]
}
|
[] |
[] |
[
[]
] |
||
2zt53j
|
how do people get their accounts hacked?
|
I'm talking about the complex hacking, where it isn't just someone downloading porn and getting a virus or something along those lines. I'm talking about how do the really good hackers actually hack into an account and take it, when there's no key loggers, viruses, brute forcing, etc involved.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2zt53j/eli5_how_do_people_get_their_accounts_hacked/
|
{
"a_id": [
"cpm154h",
"cpm17t2",
"cpm40an"
],
"score": [
13,
3,
2
],
"text": [
"Forgot password > forgot username > forgot email\n\nAt that point, you just need a name and a bit of personal information for most sites. I've tested this on Facebook before (with the friend's permission of course), and I was able to get in with a few fake accounts and a birthday. ",
"Using specific softwares or operating system with vulnerabilities (old versions of Windows, MySQL, Internet Explorer and so on). Then hackers can scan and find systems that can be exploited with tools like nmap to fingerprint the operating system and open ports to a system. If any ports run an exploitable software. They will then try to exploit the vulnerabilty to gain superior access to the system or access the database or upload malicious content/applications to run as backdoors for easy access later. \n\nThen they can access your accounts as they please.\n\nEDIT: Other way is to scan for data flow through the network like ethernet or wifi with tools like wireshark. If users tries to access sites without encryption, they might just show up in the scanner in clear text like passwords, chats etc. ",
"Social Engineering is one way to get access to an account without any malicious software involved. In ELI5 terms it's basically tricking people into giving you sensitive data. Like calling you pretending to be a manager in your bank and asking you to verify your social security number.\n\nAnother way is exploiting vulnerabilities in web applications to trick servers into giving you the info. Basically what you're doing is \"injecting\" your own code into a vulnerable application in order to trick whatever service it uses to store the data into giving you data you're not supposed to be receiving. This is kinda hard to explain without getting more technical. If you want more info [Cross-site Scripting](_URL_0_) & [SQL injection](_URL_1_) are probably the most exploited vulnerabilities of this type right now."
]
}
|
[] |
[] |
[
[],
[],
[
"http://en.wikipedia.org/wiki/Cross-site_scripting",
"http://en.wikipedia.org/wiki/SQL_injection"
]
] |
|
5m7911
|
how do strain gauges work?
|
I was reading about railway systems and found out that strain gauges are used to measure the weight of train cars. However I didn't really understand how the strain gauge work. ELI5?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5m7911/eli5how_do_strain_gauges_work/
|
{
"a_id": [
"dc1e5b2"
],
"score": [
3
],
"text": [
"Make a cylinder of play-doh. Squish it down evenly from the top. The center will expand out in a predictable way. Steel acts much like play-doh, but squishes almost imperceptibly. \n\nStrain gauges feature a wire on a conductive bit of foil and an adhesive. If we pass a current through the wire, we can measure the resistance between the two ends of the wire. At rest, we know this is 100. \n\nWhen we stick the gauge to the side of something, calibrate the resistance to 100, then load the something, we'll see the resistance in the strain gauge go from 100 to 105. Using math and known material properties, we can estimate how many micromillimeters of play-doh style expansion has occurred. \n\nFrom there we can calculate the stress and strain in the object at that point. "
]
}
|
[] |
[] |
[
[]
] |
|
2kblqo
|
why a smooth metal ball rolling on smooth wood makes noise
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2kblqo/eli5_why_a_smooth_metal_ball_rolling_on_smooth/
|
{
"a_id": [
"cljpeko"
],
"score": [
7
],
"text": [
"The short and simple answer is that nothing is as \"smooth\" as it seems.\n\nOn the microscopic level, everything around you has pits, valleys, bumps, edges, etc. When you roll that ball on that table, all of those features create sound as they interact with each other and vibrate the air around them.\n\nTl;Dr: Anything you see as smooth on the human scale, is really not smooth at all.\n\nEdit: spellingz, and clarifications"
]
}
|
[] |
[] |
[
[]
] |
||
a59gik
|
what do they mean when they say “you’re gonna flood it” when the car won’t start?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/a59gik/eli5_what_do_they_mean_when_they_say_youre_gonna/
|
{
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"ebktc13",
"ebktenp",
"ebktmka",
"ebkttu4"
],
"score": [
3,
4,
2,
20
],
"text": [
"For the air-fuel mixture in an internal combustion engine to ignite it must be at a specific ratio (the stoichiometric ratio) of 14.7:1 parts air:fuel\n\nWhen they say you're going to flood it, they mean if you open the gas you'll put more than that ratio in. When you put so much fuel into the combustion chamber that there isn't enough air in there to combust, then you have flooded your engine\n\nEdit : corrected ratio to 14.7:1 thanks to u/clydetorrez",
"Basically, every time you turn the key to start your car in, some fuel is injected into the cylinders. For combustion to happen, it has to be the correct ratio of fuel to air.\n\nIf you turn the key, and the car doesn’t start, fuel gets injected, but not burned. Thus, when you turn it again, there will be even more fuel. Do this enough times, there will be too much fuel inside of the cylinders for combustion to happen. \n\nThat’s what they mean by “flooding the engine”.\n\nWhen this happens, you have to wait a while for some of the fuel to evaporate so that the proper ratio of fuel to air can be achieved.",
"everytime you try to start a vehicle the fuel pump in the vehicle does what we call \"Prime\" now priming is where the fuel pump will shoot in a little bit of fuel into the cylinder so that the car has something to burn to start the car\n\nOn a vehicle thaf is having an issue starting the car will continuously put gas into the cylinders even though it's not burning so if your vehicle is having an ignition issue where it will not fire to burn the gas continuously trying to start the vehicle will cause the cylinders in the engine to fill with gas and thus flood.\n\n",
"In older cars with carbureted engines (as opposed to fuel injected), the carburetor is the place where fuel and air are mixed prior to combustion. When starting up the engine, if the engine turns over (driven by the electric starter motor) but the fuel in the cylinders (where the fuel/air mixture burns) does not ignite, then the unburned fuel will build up and be to rich (too much fuel, not enough air) to burn. At this point the engine is \"flooded\" with fuel and may need to sit for a short while while it drains/dissipates before the engine can be started up."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
7p804q
|
what are quaternions and octonions? what are they used for and how?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7p804q/eli5_what_are_quaternions_and_octonions_what_are/
|
{
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"dsfhbkp",
"dsfisnd",
"dsfjhwz",
"dsfmbv6",
"dsfx4vv",
"dsg7cwp",
"dsg9g84",
"dsghudm",
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118,
80,
45,
9,
18,
2562,
38,
5,
472,
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3,
2,
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"text": [
"A practical application of **quaternions** are that they are used to stabilise cube satellites in Low Earth Orbit. \n\nCube satellites can take advantage of the Earth's magnetic field and using orthogonal electromagnets, stabilise themselves with respect the field. Of course this is a simple explanation of what happens, but quaternions are a way of mathematically modeling, then controlling, the satellites relationship to the field. \n\n*Source: me, using quaternions for Attitude Determination and Control System for a cubesat.*",
"I love quaternions.\n\nQuaternions can be thought of in a variety of ways, but perhaps the most intuitive is as an extension of the complex numbers (or better yet, as an algebra on R^4, if you know what that means).\n\nWhere a complex number is of the form a + bi, where a and b are real numbers, a quaternion is of the form a + bi + cj + dk.\n\nWe define addition as follows:\n\n(a + bi + cj + dk) + (e + fi + gj + hk) = (a+e) + (b+f)i + (c + g)j + (d + h)k\n\nMultiplication is a bit more complicated, but stems from Hamilton (the cool one, not the shitty one with the musical) where he defined i^2 = j^2 = k^2 = ijk = -1. Extrapolating this out, we get a few identities:\n\n1. ij = k\n2. ji = -k\n3. jk = i\n4. kj = -i\n5. ki = j\n6. ik = -j\n\nYou see what this is, yeah? We have, built into quaternions, an anti-symmetry which is \"compatible\" (not sure of a more technical word) with an oriented R^3. We use this to define multiplication of two quaternions, which I'll leave to use as an exercise (aka, its long so I don't want to type it out).\n\nThe real power of quaternions is that you can use unit quaternions (q = a + bi + cj + dk implies |q|^2 = a^2 + b^2 + c^2 + d^2) to represent orientation preserving rotations of R^3.\n\nThe collection of orientation preserving rotations on R^3 is denoted SO(3) and is a three dimensional Lie group, which is a group and a manifold at the same time. Since it is three dimensional, we can parameterize it with 3 variables. This is commonly done using Euler angles, which is generally a shitty way of doing it because you wind up with very serious issues known as singularities. It turns out that SO(3) cannot be globally parameterized (parameterized everywhere without singularities) by a single parameterization of three variables. To use a minimal parameterization, you either have to ignore the singularities (very dicey prospect), or use mutliple parameterizations that are related to one another smoothly. The former is what shitty engineers do, the latter is what mathematicians do. A third approach is to use a non-minimal parameterization. A common one is the collection of 3x3 real matrices which have determinent 1 and whose transpose is also their inverse. This works, but it is waaay more parameters (9), than are needed (3). You can instead use unit quaternions, which have 4 parameters, to represent an element in SO(3). Because of this, quaternions are used in robotics, computer graphics, control theory, etc.\n\nQuaternions were also developed for use in physics, but I think they have fallen well out of flavor in that field.\n\nBTW, quaternions have the structure of a non-commutative division algebra --- they *almost* form a field.\n\nOctonions are a further generalization which have 8 real parameters. They also form a division algebra. I'm not sure of any applications of octonions, but apparently John Baez, famed physics professor (really beautiful writer) and cousin of way more famous Joan Baez, knows a lot about applications of [octonions](_URL_0_)",
"Edit:\nWhat I said below is not literally an explain like I'm 5. Consider it an \"explain like I've learned enough math to have heard of quaternions, but I don't really understand what they are\". To help make things more accessible, for anyone still reading, I have prefaced it with an explanation of the complex numbers as well, so that it hopefully becomes a bit more accessible. There are plenty of other comments that explain via analogy- I am trying to explain what's really going on, in a way that most people can understand. This is easier said than done. \n\nComplex number preamble (high school level): \nStep one, we are all familiar with the real numbers - 1, 2, ⅓, 1.924323, pi, e, etc, and one way that we can view the complex numbers is as an extension of the real numbers. In the real numbers, we can't take the square root of a negative number, since all numbers square to positive numbers, so we should never have a situation in which a negative number is a square. Therefore, a long time ago, mathematicians asked themselves \"what would happen if we could take square roots of negative numbers?\". To allow for this, we can *define* i = sqrt(-1) (Technically not \"correct\" but it's \"good enough\" for most purposes). Then, it turns out that we can use the property sqrt(ab) = sqrt(a)sqrt(b) to get sqrt(-a) = sqrt((-1)a) = sqrt(-1)sqrt(a) = isqrt(a). From here, we can define the real part of a number, and the imaginary part, so that complex numbers look like a + ib, where a and b are real numbers, with a the real part and b the imaginary part. Now, this is all fine and good, but so far its very unintuitive and quite abstract. I don't blame you if you're feeling lost right now. It gets better.\n\nPicture the plane (so, xy axis type thing). Usually, we think of this as a copy of the real numbers on the x axis, and a copy of the real numbers on the y axis - this is how we get graphs and lines and stuff. Hopefully you're pretty comfortable with that. From here, you may notice the similarity between how we have defined complex numbers, and the x and y axis- plot the \"a\" value of the complex number on the x axis, and the \"b\" value on the y axis - this gives us a pictorial representation of complex numbers. Instead of a number line, we have a number plane, and any point you can plunk on the plane corresponds to exactly one complex number. Perfect. \n\nIm running low on time now, but after a bit more work, it turns out that there is a nice way to represent rotation using these complex numbers - you can think about it like this: if you have a number a on the x axis, to get it to the y axis, you multiply by i. Pictorially, this corresponds to a 90 degree rotation in the plane. \n\nWith that all said, onto the real explanation of quaternions:\n\nI’ll try a more eli5 explanation, although if you want something more technically correct, look at the other comment. \n\nSo, I will be assuming you know about complex numbers for this, otherwise, let me know and I’ll do a quick explanation of those. \n\nAs we know, complex numbers can be used to represent rotation in R^2 (the 2 dimensional plane). The question then is “how do we represent rotations in 3- space?” \n\nNaively, you might think, “well, if we define another “unit”, call it j instead of i, and then work out the same rules, that might work”. Unfortunately, you run into some insurmountable issues if you do it that way - from a purely geometric perspective, you get something called gimbal lock, where 2 of your axis of rotation sort of degenerate into 1. \n\nTo solve that, we can bring in a 4th dimension- using the k unit to denote it. This solves the gimbal lock problem (again, geometrically). \n\nFrom a mathematical perspective, this manifests as an inability to give well defined operations using 3 dimensions, which is mostly fixed by adding 4. I say mostly, because quaternions loose commutativity, which means that, for x, y quaternions, in general, xy!= yx, whereas that is true in the complex numbers. \n\nOctonians are just another generalization, and this time you loose associativity as well as commutativity. \n",
"Let me try instead, I did a whole thesis on quaternion transformations with the purpose of developing a monitoring system with sensors to help the revalidation of people with back issues.\n\nQuaternions are indeed a 4-dimensional representation of 3d rotations and an extention of the complex numbers, but have a much easier way of interpreting than explained here already.\n\nLet's start out with Euclidian-rotations. These correspond with the rotations shown on a gimbal. There are 3 axis and you can rotate an object around these. If we ignore the gimbal-lock for one second you can represent any position with three numbers (x,y,z).\n\nQuaternions use a different system. Imaging an object and stabbing it with a long needle. You can now rotate the object around the needle with an angle (theta). The needle can be respresented by a vecor (a, b, c) and the angle gives d.\n\nWe can already see that there are 4 variables here that determine the rotation, but they are not quaternions yet. There values need to be transformed to form the eventual (x, y, z, w) values that make a quaternion. I'm on my phone and don't know them by heart, so i'll fill them in later\n\nX = ...\nY= ...\nZ=...\nW=...\n\nFrom this point you have a quaternion with wich all sort of special transformations can happen. Combining rotations is now linear wich has great applications.\n\nIn short, they are a different and difficult way of representing 3d positions, to afterwards make calculations easy.",
"Coming at this from the wrong direction for this subreddit, Quarternions are black magic that make the math for rotating stuff easier. Like, if you only have XYZ, sometimes a simple movement, such as rotating over the north pole, is either impossible or needlessly complex, but quaternions let you, like, temporarily shunt the axis of rotation off to the fourth dimension or something, so that it's never actually in the way. I don't understand it, but it's sure as hell useful.",
"I'm going to try my best at this.\n\nSo think about these numbers: 1, 2, -3, 5.5, 2/3, and π (pi). These are all used in what we call the Real Number System. You know lots of these numbers, and you also know how to add them and multiply them very well. With each system there are some rules we cannot break, like any number multiplied by 0 is always 0. Using these numbers and rules we can solve lots of equations; however, there are some equations which we cannot solve by using Real Numbers.\n\nFor example, what is the solution to x * x + 1 = 0? We have x * x = -1, so x is the square root of -1. Well, what exactly is the square root of a negative number? Well, it's definitely not Real. In fact, we call the square root of a negative number an Imaginary Number. Using Imaginary and Real numbers we create what is known as the Complex Number System. A Complex Number is a combination of a Real Number plus an Imaginary Number. For example, 3 + 2i, is a Complex Number where the letter i indicates an Imaginary Number.\n\nWhat's so interesting about this Complex Number System? Well just like the Real Number System there are specific rules on addition and multiplication. Most notably is that i * i = -1. We can solve different types of problems using this Complex Number System that we couldn't in the Real Number System---but remember, with this power comes more rules to follow. \n\nNow here come Quatternions. You can think of Quatternions as like Complex Numbers with four components. An example of a Quatternion is 1 + 2i + 3j + 4k. Like above, the letters i, j, and k stand for different imaginary numbers. Quatternions must follow the rule i * i = j * j = k * k = i * j * k = -1. Here's a huge key point about Quatternions---order of multiplication DOES matter. i * j = k BUT j * i = -k. Using these rules we can solve lots of problems we could not do easily using just Real Numbers.\n\nWell, what about an example? Quaternions are used in computers graphics a lot where we want to visualize 3-dimensional space. Think about a 3-D graph with 3-axes. We have the x-axis, y-axis, and z-axis. Now replace them with the i-axis, j-axis, and k-axis. Some cool things we can do with math on Quaternions is rotation. So if you have some computer image encoded as a Quaternion vector and want to tilt it a few degrees, you can just 'multiply' the vector for that image by a specific Quaternion to get the same image but rotated just as wanted. We could do this in other systems but the math works out very quickly and smoothly in this system.\n\nNow what about Octonions? We apply similar ideas and add on four more terms to Quaternions. You can see the specific rules they must follow [here](_URL_0_).\n\nAs we continue to move down this chain we can do some cool things we couldn't very well in the simple system most people use on a day to day basis. But in doing so we are restricted by more and more rules. Knowing the strengths and weaknesses of each system is one of the many fun things students and masters in math explore.",
"to a 5 year old.\nquaternions are a way to make sense of rolling a ball. if you took a normal ball and placed it on the ground, then drew a dot on the top, one side and the front, you'd have some useful marks to look at while it rolled along the ground.\n\nif you then tried to record the position of those dots while it rolled, you might think you need to write down 3 numbers. unfortunately, you need to record where 'up' is. so you need to write that down as well. so you write down 4 numbers.\n\nquaternions are a neat little package for writing down 4 numbers for when rolling a ball and making it sensible later on\n\n(edited because phone typos)\n\n(edit again: its pretty funny how many responses this got. my assumption is that lots of people took maths classes high enough to tackle these, but the teachers never had useful enough analogies, and instead persisted in trying to explain maths with more maths....)",
"Imagine a Nerf dart stuck to the screen of a smartphone. Now, pick up the phone and turn it around so that the dart points in some direction. The *direction* the dart is pointing can be considered to be the direction the phone itself is pointing. \n\nNow lay the phone on a table and spin it; the dart will be facing up the whole time, but it will also be *rotating*. The somewhat involved mathematical combination of direction and rotation is an *orientation*.\n\nA quaternion allows you to use 4 numbers to describe an orientation in 3D (real life) space. This is really neat and quaternions have a lot of useful mathematical properties which makes them great at this task. They are common in 3D animation, for example, because animations use a \"skeleton\" made up of \"bones\", and all of these bones have an orientation. Animation often involves rotating these bones between different orientations that represent \"poses\", and this is much easier to do with quaternions than with other mathematical objects like matrices.\n\nOctonions are similar but for 7D space which makes them not very useful for most people.",
"Quaternions are very simple. Let's start with vectors first because a quarternion is simply an extension of a vector. So a vector can be used to represent a direction in 3D space. The vector (1,1,1) is one unit up, left and forward from your current position. \n\nA quaternion is meant to describe a rotation, so imagine your head looking in the direction of the (1,1,1) vector with straight line coming out from your nose. Now return the vector to looking straight ahead (0,0,1)how far clockwise or anti-clockwise around this line is your head rotated ? Is it inclined slightly to the left ? Or maybe the right ? Clearly to describe all exes of the rotation we need an additional piece of data to add to the vector. Thus a quaternion is represented by (x, y, z, w) where w is the rotation around the direction. \n\nNow this is only true for certain simple cases but it serves to explain what's quaternion is. Remember that because the rotation I just described is relative to the frame of reference that the vector is pointing in, it's only possible to use the z component of the vector to describe that clockwise rotation when the other two components (x and y) are at 0,0.\n\nAs you rotate one axis, the dimensions of the quaternion cross into each other (as demonstrated by gimbal lock) so the w component no longer represent simply rotation around the direction but also part of the direction also. The entire quaternion thus is used to express a 3D rotation. \n\nIncidentally, (and being Irish I like this story), the inventor or quaternions William Hamilton was struggling with how to describe a rotation, and unable to solve the problem went for a walk with his wife in the part of Dublin where they lived. As he crossed broom bridge he was inspired an there's a plaque on the bridge now to mark the occasion. I know broom bridge well & have seen the plaque many times. Look up the Wikipedia entry for quaternions. ",
" > What are they used for and how?\n\n**Video games!** \nVideo games are hard but cool math. If you ever asked your teacher \"What do I need this for?\", the teacher should have said \"Video games!\".\n\nNow, Quaternions can be used in video games as a mathematical means of describing the orientation of an object in three dimensional space, for example the current world of the level. Most of objects are controlled by using matrices (Matrix, but not the movie), but a considerable part of generating these matrices is done using Quaternions.\n\n & nbsp;\n\nTo understand why Quaternions are helpful in video games, I need to introduce you into two common problems that will help you understand how rotations depend on each other.\n & nbsp; \n & nbsp; \n \n**Issue number 1: Rotation order.** \n\nImagine a plane on a runway. The plane has three axises: X-axis the one the plane rotates around when it takes off (From wingtip to wingtip). Y-axis is towards the direction of travel (When the plane does a barrel roll, it rolls around the Y axis). And Z-Axis is the one it rotates around when it is on the ground driving around the airport.\n\nNow I give you the following instructions for a plane on a runway facing north:\n\n1. Rotate the plane around its X-Axis by 45 degrees. (This looks like the plane has just taken off) \n2. Then rotate the plane around its Z axis by 90 degrees. (This looks like the plane is taking off, but looking towards the right of the runway) \n \nIf I reverse these instructions, you get a different outcome:\nThe plane is now going off the runway towards the East. And it is still facing up correctly at 45°. No weird sideways flying here.\n\nThe more axes you add, the more erratic the result will become if you do not follow the rotation order.\n & nbsp; \n & nbsp; \n \n**Issue number 2: Gimbal Lock** \n \nYou are inside this plane and it keeps going up at 45 degrees. But you sit in a cool pilot chair that will always keep you upright so your drink never spills. This chair will counteract all the rotations the plane currently does to move you back to a level position where your drink does not spill.\nNow the plane has kept pulling up and is now going exactly straight upwards. (X = 90°)\n\nThe chair compensates for this well, as it only applies the opposite rotation of the plane to your seat. But remember the chair is still fixed to the plane, so the chair itself is now at 90° like the plane.\nThen, suddenly, the plane is grabbed by a wind gust and shaken around, and it is now flying straight up AND 45° around its Z axis towards the left.\n\nThe Pilot chair cannot help you counteract this, as it is not able to do the opposite rotation here. The rotation order would need to be first 45° around Z, and then 90° around X. It cant do this and your drink will spill.\n & nbsp; \n & nbsp; \n \n**Fix: Quaternion** \n \n\nTo fix the chair, the engineers will need to cheat and allow the chair to turn around an extra axis to fix any rotation-order mess that may have occurred. This fourth axis is a joker, and it will need to be perpendicular to one of the three axes of the chair to help out when needed. \n\nAnd when taking this extra joker axis into account, we no longer have a three rotations, but four. The construct of dealing with this is called Quaternion and it is some pretty tough math(s) which others have tried to explain here.\n\nNow, in video games with characters, each arm and leg is made up from virtual bones that let the character bend the knee or hold weapons. These virtual bones are exactly like the special pilot chair in the plane. That is where quaternions are used.\n\n & nbsp;\nedit: man fuck reddit formatting...",
"Let's say you have a compass. It tells you what direction you're pointing, but it isn't very precise. Take enough measurements and it'll all average out in the end, but any one measurement isn't very good. \n\nNow suppose you are facing due east, which is a heading of 90 degrees. You check the compass once and it tells you that you're facing 70 degrees. You check again and it tells you you're facing 110 degrees. You average those two values and get 90. Hooray! \n\nNow suppose you were actually facing north, which is both 0 degrees and 360 degrees. You check your compass once and it tells you 20 degrees. You check it again and it tells you 340 degrees. You average these two together and you get 180 degrees! This averaging method couldn't have given an answer that was any more wrong!\n\nThe problem is that 0 and 360 are on opposite ends of a linear scale, but they represent the same direction in our circle. We can come up with a solution to this, though: instead of using one number we use two. Our two numbers will be the X and Y coordinates you'd get if you went a distance of \"1 unit\" along a given angle. \n\nThis means that a reading of 0.1 degrees will give a point very very close to a reading of 359.9 degrees. It also means that you can take several of these points and average them together by just averaging their X values and averaging their Y values. By using two numbers and a constraint (i.e. x^2 + y^2 = 1) to represent one number (an angle) we remove the issues around 0 vs 360. \n\nWe could do the same thing with a two dimensional angle. Imagine a telescope where you select altitude (angle above the horizon) and azimuth (angle relative to North). If you want to tell how far apart two stars are in the sky then this alt-az setup is fairly useless. Near an altitude of 90 degrees (straight up) you can change azimuth by a huge amount while still pointing at basically the same point.\n\nAgain, we solve this problem by introducing an extra number and an extra constraint. We use x, y, z as a point on a sphere that you would arrive at if you went \"one unit\" in a given direction. Here, again, we can average several points together and not have to worry about wraparound. We can measure distances between angles and not have to worry about the distances being wildly different in some parts of the sky. \n\nA quaternion is what you get as the next term in this series. We could describe the orientation of an aircraft in terms of roll (one wing rising and the other going down), pitch (nose up or down), and yaw (turning left or right), but this has all the problems listed above. Instead, we describe orientation by introducing another value and a constraint. Conceptually, this is the point on a 4-D hypersphere that you'd arrive at if you went \"one unit\" in a direction described by your orientation, but this is hard to conceptualize. The important thing is that they solve all of the same problems that we solved with 1- and 2- dimensional orientations. ",
"Extend your right arm with your palm facing down. Now, rotate elbow 90 degrees towards your chest (anticlockwise). Your fingers should be pointing to the left, with your palm down. Now rotate elbow 90 degrees up clockwise. Your fingers should be pointing up, with your palm facing left. Finally rotate your elbow forward 90 degrees. Your arm is extended in front of you like when you started. *However*...\n\nThere is one difference. Your palm is now facing left, not down. This is the problem with just using rotations about three axes - you cannot conserve your entire orientation. That is where quaternions come in. They have four numbers which take care of three axis rotations and the orientation. So if you were to describe the arm movements using quaternions instead of angles, your arm (and palm) would end up in the exact same position they started.",
"They are number systems.\n\nSay you in a narrow ravine with a bear. The bear is 5m away from you and just sitting there, but you want to get away from the bear. You walk away from it but after walking 5m, you see another bear 10m away. On either side of you is a bear 10m away. You say one bear is -10m, and the other bear is +10m away. Your current position is 0. How do you get further away from the bears? \n\nYou see that where you are there is a tree. You climb the tree 10m. These bears can't climb trees, so you are fine and 10m away from them. If your position was 0 before, what's your position now? It's not 10, because that's where the bear was. It's not -10 because that's where the other bear was. It's not 0, because thats where you were on the ground, but now you're farther. It's like you're at 0, but then you're 10m in the tree. So you could say you are 0 + 10i. \n\nNow the tree breaks and falls over in a nice arc with you at the top. When the tree is at a 45 degree angle, you notice that you're falling towards one of the bears. You're going to collide with him. But you notice that you're not halfway down, you're higher than that, and you're not halfway to the bear, you're closer than that. Quickly you realize that you are half the square root of 200 meters up, and towards the bear. \n\nOn your way down you realize that the math would have been a bit easier if you had just considered that everything was one unit away, then you'd just be half the square root of 2 units up and towards the bear. \n\nYou knock the bear down, and find a motorcycle and ride away from the bear. \n\nNow you find yourself on an open plain, again with a conspicuous tree. You crash your motorcycle into the tree. You get off the tree and start to walk and run into another bear, again 10m away from the tree. You walk back to the tree, and the opposite direction and again see another bear 10m away from the tree. You go back to the tree and this time you don't want to climb the post, so you turn 90 degrees and walk away from the tree. Again, bear at 10m. You go back the opposite direction and see a bear at 10m. You go back to the tree and spin in a random direction, and ... bear at 10m. You recognize that there is a bear circle with radius 10m surrounding you. The bears converge, the circle is 5m, 3m. You need to go somewhere, but what is further away from the edge of a circle than the middle if you can't get out of the circle? You climb this tree 10m. The bears go back to 10m away from the tree.\n\nUp in the tree you remember falling down in the ravine. You think that you can fall on any bear. You imagine falling on every bear, and you trace that out in your mind and realize that makes a sort of dome shape. \n\nYou think about where you traveled and how it got you to where you are. You went +5, then you went -5 back to the tree, then you went -5, and then you went +5 back to the tree. Then what did you do? You went in another direction, and we said that up the tree was i, so you say you went +5j, and then you went -5j back to the post. You notice you can add these together in series and they show you where you were at any point in time, especially when you were running around randomly. Finally you go up the tree, +10i. \n\nYou realize that you can tell pretty much any point in space with these numbers, but things get funny when you try to multiply some of them when they're in a direction. \n\nYou think back to when you were in the ravine. You went 5 one way, you went -10, you went 5 again, and then you went 10*i. Or 10m up the tree. But what would it mean if you added i*10? Is that just going up the tree 10m too? But is i a number? It kind of means you changed directions. What if you change directions twice? You think about if you walked towards the bear, this would be +10. Changing directions once would be +10i, that put you at 90 degrees up, at 10i. Another rotation, at +10ii would put you 180 degrees. So that would end up leading you back to the other bear at -10. So i*i = -1. \n\nYou think about the plains. If you were going towards one bear at +10, but you decide to turn left once, you end up at +10j. If you turn left twice it puts you at 10jj, but that is the same as -10. \n\nYou fall down the tree and hit your head. You start to hallucinate and the circle of bears turns into a sphere of bears. The bears are hovering in the air, exactly 10m away from you in every direction. You need to go somewhere to get away with them, but all of the spatial dimensions are taken. You start to recognize that you're hallucinating so you decide to do something impossible to get away from them. You rotate upwards 90 degrees, and at the same time turn left 90 degrees without interrupting the other rotation and find yourself at 10 units k in a dimension you didn't know could exist. Here you're safe. You think about these things. You realize that i*i is -1, that j*j is -1, that k*k must be -1 too. But to get to k, you made the impossible rotation i*j, so i*j = k. This means that i*j*k = -1 as well. This is interesting. You find a rock and chisel this into it so you don't forget. \n\nYou think about the sphere of bears. You think about the collapsing circle of bears. You realize that you can define any point in space by imagining a place where that sphere of bears could contract or expand to, and recording the steps to get there. 3 + 5i + 4j would mean traveling 3 meters, heading in an opposite direction for 5 meters, then traveling up for 4 meters. You can combine these together a bit too, 3 + 2i + 6j and then 3i - 2j brings you to the same bear. \n\nBut something starts to bother you. You can add these paths up to get to any bear, but you remember multiplying them together. For instance, you found k by combining i*j. You could change directions by combining i*i. There's a meaning to multiplying these together. But you start to think about this as well, if you turned i then j, you ended up with k. But if you turned j then i, what would happen, you puzzle to think about turning yourself inside out the other way around, and realize you would be still in k, but pointing the other direction. But these multiplications are kind of special, and you could plot out some interesting courses if you could combine these entire sequences, or divide them. \n\nThe problem is that k was just a silly imaginary place you went when you hit your head. You figure you don't need it, and you try and work out how you would divide or multiply these places in the real world. Nothing really seems to work, but then you remember that message you chiseled into the rock at 10k, and you remember that ijk = -1, and that ij = k. You can't multiply these together without k, because k is part of the whole process, and if you're dividing or multiplying you're likely folding these on to eachother and k will pop up. \n\nYou realize that this construction a + bi + cj + dk represents any position in 4 dimensional space, and is necessary for doing many operations on 3 dimensional space. \n\nThen you get into computer graphics and want to combine rotations. Your friends do this weird thing by rotating along the x axis, then along the y axis, then along the z axis, but those don't combine well, and they end up putting you into situations where you're restricted in which kind of rotation is possible without unwinding previous rotations.\n\nYou think back to your incident with the bears and about how your quaternion system works. You can represent any direction as a vector (a line towards any specific bear), and you can choose a magnitude of rotation along that vector. You remember the 2 bears in the chasm, and the circle of bears, and the sphere of bears, and you escaped into k space, but what if in k space there was also a bear 10m away in every direction? Well, you recognize you could get to any bear anywhere by using a value of a + bi + cj + dk and that the distance from the origin is always going to be 10m. If you went to any area that isn't a bear, the bear sphere could contract or expand to reach it. That it's the direction in this 4d sphere that is important, not exactly how far you're going. \n\nSo still on the computer rotation thing, you think, \"Hey, I'll just use a 4 dimensional sphere with 3 dimensions giving the vector for the axis of rotation and the 4th dimension to give the amount that it's going to rotate. We'll normalize it because these rotations are weighted the same way so to do that we'll stretch or shrink it to fit within a hypersphere of bears with a 1m radius (or something) and now we already have a bunch of the math to multiply, divide and add these things together. Now we don't get tied up like we're playing twister with a gopro and can smoothly interpolate between any rotation. \n\nYou try to explain this to your friends and they look at you like you're crazy for some reason.",
"I just want to add that they are basically the same as a rotation matrix. As in there is a one to one function that transforms between the two.\n\nSo why use one over the other? The quaternion uses less parameters (4 vs 9) so it is easier to store, and chaining them uses less floating point operations (which is good for speed + reduce numerical error). You can also interpolate them for splines and such. The disadvantage is that it's less intuitive than a rotation matrix, and it sometimes flips sign depending on how you are computing them (flipping the sign makes the same quaternion) which can be an issue when taking the derivative.",
"We assume a very smart 5 year old that knows a complex number z = a + bi, where i is the imaginary unit satisfying i^2 = -1. The nice thing about complex numbers is that multiplication acts as a rotation on the complex plane. Think of 1 as the unit facing east and i as the unit facing north, and the transformation i * 1 = i as rotating the point 1 to the point i.\n\n\nQuaternions are an extention of complex numbers to a higher dimension. Throughout much of the 19th century, mathemeticians tried to find a way to generalize this rotational transformation to 3 dimensions. Unfortunately, 3 dimensional rotations can not be expressed using only 3 dimensional numbers, in fact you need 4 dimensions. A quaternion is of the form z= a1 + bi + ck + dj, where i^2 = j^2 = k^2 = ijk = -1. Quaternions allow for 4 dimensional rotation [edit: also 3 dimensional rotation] via quaternion multiplication, and they are used extensively in computer graphics for this reason.\nDo note that quaternions do not have commutative multiplication, so if A and B are quaternions, AB =/= BA, necessarily. Edit 2: Quaternions were also the basis of physics until Jordan and his damn vectors came along and ruined all the hypercomplex fun.\n\n\nOctonions take this a step further with 8 dimensions, although I'm not sure if there is a use case for 8 dimensional rotation. Octonions also take a step further by not being associative, i.e. for octonions A, B, and C, (AB)C =/= A(BC), necessarily.\n\n\nBig up to William Rowan Hamilton for the discovery. For even more fun, check out Clifford algebras.",
"Take out your protractor and put your finger on \"10 degrees\" and \"20 degrees\". Those are \"10\" apart. If you move the second finger to \"90 degrees\" now they are \"80\" apart which is more, and that's satisfying, because they are also farther around on the protractor. Let's keep going! Let's put one finger on \"0 degrees\" and one on \"180 degrees\". They're as far apart as possible and \"180\" apart. Now move your finger to \"181 degrees\". How far is that from \"0 degrees\"? Is it \"181\"? No, you've started getting closer again, it's only \"179\". Keep going to \"350 degrees\". If I just subtract I get \"350\" from your first finger, but we can see it's really much closer. Now move that first finger over to \"359 degrees\". Hey! The math works again, your fingers are \"9\" apart.\n\nSo it's convenient to label that protractor in \"degrees\" but it has this property where it wraps around and makes the math annoying. If I want the angle halfway between two points it works to just average sometimes (0 and 90 average to 45, check!) but not other times (0 and 350 average to 175, but halfway between is 355). What other method could we choose to label angles? What if we used the XY coordinates of the point on the circle that corresponds to the angle? We'll use the unit circle, so ||X, Y|| := 1. We can use complex numbers to represent the points as X+Yi. This has the nice property that nearby angles are nearby in number space without any discontinuities. It has the nice property that you can multiply them to combine their rotations. And unlike adding angles, there is no wrapping to \"428 degrees\", it just naturally wraps right back around the complex unit circle. It has the unfortunate property that there are lots of invalid numbers like \"2+3i\" which aren't on the unit circle (this happens because there is only really one degree of freedom, but a pair of numbers has two degrees of freedom).\n\nNow if you extend the same kinds of problems and the same solution to a 3 dimensional angle (and they're actually even more annoying) then you get quaternions, which lie on the surface of a 4-dimensional sphere just like our one dimensional example used a 2-dimensional circle.",
"complex numbers have an imaginary unit i with ii=-1.\n\nquaternions have 3 imaginary units (+1 real part is the 4 in the name) i,j,k with ij=k,jk=i, ki=j as well as ii=jj=kk=-1. they form a noncommutative division ring."
]
}
|
[] |
[] |
[
[],
[
"http://math.ucr.edu/home/baez/octonions/octonions.html"
],
[],
[],
[],
[
"https://en.wikipedia.org/wiki/Octonion"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[]
] |
||
1bcisr
|
superfluid helium and perpetual motion
|
I heard that superfluid helium can climb up the walls of a container and push itself through a perpetual fountain. The only explanation given was that the liquid lacks viscosity. It seems like energy would still have to be spent to counteract gravity. How does this work?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1bcisr/eli5_superfluid_helium_and_perpetual_motion/
|
{
"a_id": [
"c95nlxh"
],
"score": [
2
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"text": [
"You can create a superfluid helium fountain by sticking an empty tube into it. However, the fountain only exists as long as there is a heat gradient. It's not perpetual motion."
]
}
|
[] |
[] |
[
[]
] |
|
7chxcb
|
how does matter transform into energy, visually speaking?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7chxcb/eli5_how_does_matter_transform_into_energy/
|
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"text": [
"Well if you split an atom intramolecular bonds change from matter to energy. \n\nSo what would it look like visually is a nuclear explosion. The sun would be a good example of energy turning into matter actually, also a huge explosion. \n\nDue to its nature I don't think anyone has an actual visual representation of the transformation, there isn't a stable intermediate so its matter, then its just energy, like electrons switching between energy levels.",
"Is this something you could study in college? Of course!\n\nIf you're talking about full matter-to-energy conversion, like matter/anti-matter annihilation, there's not much to \"visualize\"... the two particles literally disappear and become the gamma rays or whatever is being emitted. I don't know if it can be described any further than that.\n\nIf we're talking something like fission, think of the particles making up the nucleus of an atom as being all stuck in a tug of war contest. They want to fly apart but the rope (the rope is representing the strong nuclear force) is keeping them together. Breaking that up causes the particles to fly away from each other, just like breaking a tug-of-war rope causes the contestants to all fly away from each other. The energy that's kept pent up by being stuck together in the nucleus is suddenly released.",
"Everything is energy. Mass is simply the energy that's contained within a system regardless of what you do. It doesn't matter who is viewing the system, there's a minimum amount of energy that simply will always be there. \n\n\nA baseball has a certain amount of energy. It's got the nuclear energy in all it's atoms, the chemical energy in all the binding between atoms, thermal energy in the random motion if the atoms, and kinetic energy in how fast the ball as a whole is moving. It's \"mass\" is nuclear, chemical, thermal energy combined, the internal energies. However, the thermal energy and chemical energy are insignificant next to the nuclear energy.\n\n\nIf a professional baseball player through the ball, relative to you standing there it's gained a lot of energy. Does this energy mean it gained mass? Well, it depends if everyone sees it with that energy, and the answer is no. If you were in a car traveling along side the ball, it's not moving. It has no kinetic energy. There is always a viewpoint you can take where an object has zero motion, zero kinetic energy. Therefore, kinetic energy isn't mass. And whatever energy is left then is the mass. The energy internal to it. \n\n\nNow, I said thermal energy contributes (a trivial amount) to mass of a ball. But if thermal energy is just random kinetic motion of the atoms, how does that work? Because the mass of a baseball is the mass of the entire system staying together, that is the ball. It's not the mass of the individual atoms summed up. Energy confined to a system becomes mass to that system. An atom moving left and another moving right within a ball in still there even if the ball is stationary, therefore that kinetic energy is part of the ball's mass. \n\n\nThat means if I took a mirrored box and weighed it, and then filled it with a lot of light to continually bounce around inside and wieght it again, the box would weigh more. Add light, completely massless pure energy, to a box will make the box have more mass. Just as adding pure kinetic energy in the forming of moving atoms (heat) made the baseball slightly heavier. \n\n\nSo what about converting matter into energy? Well, what is matter? It has mass and it's made of atoms. Atoms are made of electrons, protons, and neutrons. Protons and neutrons contribute the vast majority of the mass to an atom. What are protons and neutrons? They are three even smaller particles called quarks held together. What is the mass of a quark? Only a tiny insignificant fraction of the mass of a proton or neutron. 3x the mass of a quark isn't even close to the mass of a proton or neutron. \n\n\nWhat does that mean, where is the rest of the mass of an atom, of all matter, coming from? The vast majority of the mass of matter isn't actually the mass of what's it's made of, it's energy. Nuclear binding energy is the vast majority of the mass of matter. It's as much pure energy as light it. And just like light is made of a massless entity called a photon, the nuclear energy is made of a massless entity called a gluon (literally because it glues things together). It manifests itself as mass only because it's confined within an atom, and confirmed energy is mass. \n\n\nSo what happens in a nuclear reaction and mass is converted to energy that we always hear about? Well, the subatomic particles rearrange themselves. This rearrangement has slight less nuclear binding energy so it has slightly less mass. Where did the mass go? It was converted to energy that was no longer confined to the atoms, such as light or kinetic energy. And hence, the atom lost mass. All the same particles are still there though. It's the same for chemical reactions too. In this case it's just electrons rearranging themselves, changing the energy in the chemical bonds, and therefore changing the mass too. Just not as much of a change in energy as a nuclear reaction, so less of a change in mass. \n\n\nThat said, there are some things with fundamental mass. An electron has mass. It's not made of anything smaller, it simply has mass. That is, it has energy even if you stop it from moving. Where this mass comes from is a little complicated. Nonetheless, it isn't fixed. You can annihilate an electron (using its positively charged cousin the positron), and they both vanish into light. \n\n\nSo why doesn't light have mass? There's no way to view light in a way that it has a fixed minimum energy. If you have an electron whizzing by, you can always move the same speed as it and see it with zero kinetic energy. With light, you can't do this. If you move closer and closer to the speed of light to chase a particle of light, it simply gets more and more red. Less energy, until it essentially vanishes with zero energy. Very crudely, light is just kinetic energy. You can't stop it and still have energy left sitting there. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
6c7zff
|
where did the phrase "it ain't over until the fat lady sings" come from?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6c7zff/eli5_where_did_the_phrase_it_aint_over_until_the/
|
{
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"text": [
"Richard Wagner's opera cycle Der Ring des Nibelungen and its last part, Götterdämmerung, is what's being referenced in the saying. The \"fat lady\" is the Valkyrie Brünnhilde, who is traditionally presented as a very buxom lady with horned helmet, spear and round shield. After her scene, the opera and the Ring cycle ends. "
]
}
|
[] |
[] |
[
[]
] |
||
5g6s9x
|
how is the tongue the strongest muscle in the body when it is never worked out and is small compared to others?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5g6s9x/eli5_how_is_the_tongue_the_strongest_muscle_in/
|
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"It's constantly in use, for talking as well as eating food and swallowing etc, for a small muscle it gets used an awful lot. Also I believe it's the strongest muscle gram for gram I'm not sure about over all. Hope this helped :)",
"[Some would disagree](_URL_0_) but there's so many ways of defining strongest in different contexts.",
"Endurance and strength are very different from each other. With that contrast we can see that the tongue isn't very strong in sense of strength but it has a lot of endurance as in, it won't feel tired even if you've been talking and eating for hours and hours where as a muscle capable of lifting much much more weight will get tired from 10 min of a similar exercise. We could compare sprints to your legs, and quickly eating to your tongue and chances are your legs will give out before your tongue "
]
}
|
[] |
[] |
[
[],
[
"https://www.pumpone.com/blog/57"
],
[]
] |
|
1euec2
|
how do tv networks decide what episodes of a show to play?
|
Why is it that the same episode of a show that is being rerun will play 2 or 3 times in a day, when a network owns all the episodes of a show, and could play any one they want? Why not give as wide a variety of programming as possible on any given day? Also, why do they so often only play one half of a 2 part episode? It's particularly annoying when there are 2 time slots for the show back to back, and they play Episode X part 1 from season 3, and then, instead of playing Episode X part 2, they play Episode Y from season 5, and you just want to punch the schedule makers in the face?!?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1euec2/how_do_tv_networks_decide_what_episodes_of_a_show/
|
{
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"text": [
"The networks/stations own the rights to air the shows, but the episode orders come from the syndication companies. So The Big Bang Theory is on Peachtree TV in Atlanta, but Warner Brothers is the Syndicator, and they provide the episodes and the order. The reason 2 parters are run out of sequence on back to back shows is because the first half hour is usually the \"first run\" order and the next half hour is the \"second run.\" I believe it was a holdover from days when local stations and cable networks would buy the same shows, but have different runs, so they wouldn't compete with the same episodes as another station."
]
}
|
[] |
[] |
[
[]
] |
|
5w38t0
|
how does the "pineapple juice makes semen taste better" thing work? and how frequently do i have to drink it to make it work?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5w38t0/eli5_how_does_the_pineapple_juice_makes_semen/
|
{
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"If the person on the receiving end believes it, who are any of us to question it?",
"Tried it for a while, my completion rate for blow jobs is less than one a decade. . .so. . .couldnt get any verifiable feedback. ",
"You could always run a controlled study. By keeping track of what you eat and drink and tasting your semen regularly you should be able to make a determination as to the truth of the statement."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
3ygrsf
|
do some humans "need" meat while others do not?
|
Anecdotally I know many people who will feel unwell and still feel hungry when they have gone a day without meat while there are others that lead a healthy and satisfied vegitarian or vegan lifestyle.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3ygrsf/eli5_do_some_humans_need_meat_while_others_do_not/
|
{
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"text": [
"No one \"needs\" meat.\n\nPeople who use meat as their primary source of protein, when they go a day without meat, often do not make up for it with plant-based proteins. As a result, they may not feel well because of their protein-deficient diet.\n\nMeanwhile, vegetarians are skilled at supplementing their diet with plant-based proteins. As a result, despite going without meat, they are still consuming enough protein and feel fine as a result. If meat-eaters were just as proficient at supplementing their diets on days that, for whatever reason, they abstained from meat, they'd probably feel fine.\n\nEdit: a word\n\nEdit 2: I'm not a vegetarian. Just a former science teacher that knows what he's talking about.",
"Humans are biologically omnivores. That means that we are suppose to eat a mixture of meat, plants, fruit, fungi, and nuts. Humans need meat because we are not herbivores. We are not capable of getting all the nutrients we need from plants without eating a wide variety of them. It is also important to note that most of the plant combinations do not grow naturally together in most of the world, and many only grow in tropical regions. (India being one of the few places with all the right plants). \n\nIn modernity we are able to be vegetarian or vegan without problems because we have access to dietary supplements and the ability to import the proper foods from around the world. But there is no reason to give up our natural diet and the pleasure of eating meat unless it violates your personal ethics. ",
"Humans don't need meat (or any other animal products). If people feel unwell without it, it's because they don't plan their diet well. All the major dietetics and health organizations in the world agree that vegan and vegetarian diets are just as healthy as omnivorous diets. Here are links to what some of them have to say on the subject:\n\n**[American Dietetic Association](_URL_3_)**\n\n > It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.\n\n**[Dietitians of Canada](_URL_1_)**\n\n > A well planned vegan diet can meet all of these needs. It is safe and healthy for pregnant and breastfeeding women, babies, children, teens and seniors.\n\n**[The British National Health Service](_URL_8_)**\n\n > With good planning and an understanding of what makes up a healthy, balanced vegan diet, you can get all the nutrients your body needs.\n\n**[The British Nutrition Foundation](_URL_6_)**\n\n > A well-planned, balanced vegetarian or vegan diet can be nutritionally adequate ... Studies of UK vegetarian and vegan children have revealed that their growth and development are within the normal range. \n\n**[The Dietitians Association of Australia](_URL_2_)**\n\n > Vegan diets are a type of vegetarian diet, where only plant-based foods are eaten. They differ to other vegetarian diets in that no animal products are usually consumed or used. Despite these restrictions, with good planning it is still possible to obtain all the nutrients required for good health on a vegan diet.\n\n**[The United States Department of Agriculture](_URL_9_)**\n\n > Vegetarian diets (*see context*) can meet all the recommendations for nutrients. The key is to consume a variety of foods and the right amount of foods to meet your calorie needs. Follow the food group recommendations for your age, sex, and activity level to get the right amount of food and the variety of foods needed for nutrient adequacy. Nutrients that vegetarians may need to focus on include protein, iron, calcium, zinc, and vitamin B12. \n\n**[The National Health and Medical Research Council](_URL_7_)**\n\n > Alternatives to animal foods include nuts, seeds, legumes, beans and tofu. For all Australians,\nthese foods increase dietary variety and can provide a valuable, affordable source of protein\nand other nutrients found in meats. These foods are also particularly important for those who\nfollow vegetarian or vegan dietary patterns. Australians following a vegetarian diet can still meet nutrient requirements if energy needs are met and the appropriate number and variety of serves from the Five Food Groups are eaten throughout the day. For those eating a vegan diet, supplementation of B12 is recommended.\n\n**[The Mayo Clinic](_URL_4_)**\n\n > A well-planned vegetarian diet (*see context*) can meet the needs of people of all ages, including children, teenagers, and pregnant or breast-feeding women. The key is to be aware of your nutritional needs so that you plan a diet that meets them. \n\n**[The Heart and Stroke Foundation of Canada](_URL_0_)**\n\n > Vegetarian diets (*see context*) can provide all the nutrients you need at any age, as well as some additional health benefits.\n\n**[Harvard Medical School](_URL_5_)**\n\n > Traditionally, research into vegetarianism focused mainly on potential nutritional deficiencies, but in recent years, the pendulum has swung the other way, and studies are confirming the health benefits of meat-free eating. Nowadays, plant-based eating is recognized as not only nutritionally sufficient but also as a way to reduce the risk for many chronic illnesses.\n"
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.heartandstroke.com/site/c.ikIQLcMWJtE/b.3484249/k.2F6C/Healthy_living__Vegetarian_diets.htm",
"http://www.dietitians.ca/Nutrition-Resources-A-Z/Factsheets/Vegetarian/Eating-Guidelines-for-Vegans.aspx",
"http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/vegan-diets/",
"http://www.ncbi.nlm.nih.gov/pubmed/19562864",
"http://www.mayoclinic.org/healthy-living/nutrition-and-healthy-eating/in-depth/vegetarian-diet/art-20046446",
"http://www.health.harvard.edu/staying-healthy/becoming-a-vegetarian",
"http://www.nutrition.org.uk/publications/briefingpapers/vegetarian-nutrition",
"http://www.nhmrc.gov.au/guidelines-publications/n55",
"http://www.nhs.uk/Livewell/Vegetarianhealth/Pages/Vegandiets.aspx",
"http://www.choosemyplate.gov/tips-vegetarians"
]
] |
|
3h7tmp
|
why is it that our eyes cannot repair their vision? so we don't have to wear glasses or contacts etc...
|
edit: thanks for the explaination guys! first time posting something here
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3h7tmp/eli5_why_is_it_that_our_eyes_cannot_repair_their/
|
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"This isn't a complete answer but they can, some people when they get glasses say their natural vision improves after a while. That may only apply to minor eyesight issues though. ",
"Sort of relevant; because what if \"repaired\" to a particular person is still abnormal?\n\nAs in, imagine having astigmatism (a more oval shaped eye, basically) that you were born with. Any repair your body would do would only restore the problem, not actually fix it.\n\nAnother thing, mostly relevant to adult age, is that the cells (particularly the lens) of the eye aren't all that great with aging. It's my recollection that the lens itself becomes less flexible and more hardened/brittle by aging, which makes it harder for the muscles involved in the eye to focus on different depths. This being a possible reason why middle aged and elderly adults might have a set of reading glasses - because their eyes are incapable of adjusting for depth adequately.",
"Well, think about it; light comes into your eye through the lens, which is a large protein structure. This light travels through the open cavity in your eye, until it hits the back of your eye, where it excites photoreceptor cells, which then send information pulses to your brain through your optical nerve. Your brain, at the occipital lobe then takes those information packages, and builds together a coherent image of what your eye is seeing, which you perceive as vision. \n\nThe problem with fixing vision issues comes with, where is the problem, and how could it get fixed biologically? Generally speaking, tissue specific stem cells are responsible for fixing damaged tissue, but unfortunately the first part of fixing a problem, is recognizing that you have a problem, and having a feedback mechanism to tell the stem cell if it's fixing the problem, or making it worse. As cliche as it's going to sound, vision is all in your head, and as far as your body is concerned, it did it's job by giving you an pair of eyes, and it doesn't care/know that your vision isn't perfect. \n\nYour eyes don't have stem cells, and we don't have a feedback mechanism for vision issues. ",
"If the vision problems you're talking about are just the kind that can be fixed by glasses, I think there's a misconception; needing glasses does not mean you have any \"damage\" to your eyes; rather it just means the size of your eye is not at the ideal for the power of your lens and cornea. The size of your eye isn't really a disease state except in the extremes, so there's nothing to really \"fix\".\n\nOther causes of vision loss (ie medical causes) are a different story",
"The lens in your eye is a crystal of collagen. There are no cells inside of it. As you age the crystallization continues via chemical processes which makes the lens stiffer. Since the muscles that stretch it don't get stronger this makes it less able to focus than before making it more difficult to see then before. It doesn't get \"repaired\" because a) there's nothing \"wrong\" with it, b) there aren't any cells in the lens to make repairs and c) they wouldn't \"know\" how to do the repair if there were.\n\nGlasses are a relatively recent thing and throughout most of human history humanity (and probably many billions of animals) has/have done just fine without them. ",
"Evolution doesn't really care about quality of life. If you can pass down your genes there isn't an evolutionary need to repair your vision. "
]
}
|
[] |
[] |
[
[],
[],
[],
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|
69v5og
|
where am i "allowed" to buy a tesla?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/69v5og/eli5_where_am_i_allowed_to_buy_a_tesla/
|
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"You can and the showrooms will help you place an order. \n\nI think a few states are still preventing this direct model still. "
]
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|
[] |
[] |
[
[]
] |
||
3171gr
|
how does the united states run on a deficit, and what does that actually mean for the future?
|
We've only NOT run a deficit for four years of the past forty. As a member of the younger generation I'm trying to learn what it actually means for a country and it's posterity to run a deficit year after year.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3171gr/eli5_how_does_the_united_states_run_on_a_deficit/
|
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"Running a deficit basically means that you end the year owing more than you did at the start of the year.\n\nIs that a bad thing? Well, maybe... but not necessarily.\n\nYou see, unlike in personal finance, when you're talking about national finances (or business finances, which are very similar), having some debt is usually a *good* thing, because it means you can spend money in order to make more money.\n\nSo if the country borrows money, spends it on things like infrastructure and job creation, and ends up with more of the population in work, earning more money, and paying more tax, then this extra tax ought to be enough to pay the extra interest on the bigger amount of debt. That's a good thing - it means the country's finances are growing. As the country's finances grow, so its ability to repay debt grows, and it would be wrong not to take advantage of that.\n\nOn the other hand, if the reason you're running at a deficit is because no one is in work so you're not collecting much tax, but you're having to borrow money to pay the salaries of civil servants, then that's bad.",
"A countries finances are different than personal finance. For one the country controls the money. We could simply print off all the money and instantly pay back all the debt we wanted at any time. Should we? No because that could cause a lot of inflation.\n\nRunning a deficit isnt necessarily bad and being in debt as a country is more the norm than anything. As long as we keep paying back the money (which we always have) then there is no real reason to worry.",
"Something that really put it in perspective for me was [Democracy 3](_URL_0_) \n\nIt gives a glimpse of what makes up the national budget, and how a ton of outside influences constantly throw it into chaos. Then you have to decide how to manage it. \n\n",
"What it means is that the Government spends more in a year than it takes in. As you've noted, the US government almost always runs a deficit. This is only sustainable if the US economy is growing faster than the the debt is growing. The measure of the size of the US economy is GDP, which you can think of as the ability of the economy to pay taxes that go to repaying the debt that the government accumulates.\n\nObviously debt bears interest. If the economy doesn't grow as fast as the debt, the debt to gdp ratio goes up. The higher this ratio, roughly speaking, the bigger the proportion of the government's income it must spend on interest payments. The last two presidencies have both contributed to a huge increase in the debt to gdp ratio, through running deficits that are larger than the rate of growth of the economy. This is not sustainable in the medium or long term.\n\nRight now 14% of the American government's income is being used to pay interest. If the American economy doesn't start ovtertaking the deficits soon, this number will keep rising. History has shown us that empires tend to collapse when close to half government income is spent on interest payments.\n\nThe trick that the US government has been using for decades to reduce this problem is to lower interest rates on government bonds, which have been falling steadily for decades. Now that interest rates are near zero, they can't be lowered further. There are some who don't think the Fed will be able to raise rates much in the coming years, as this would put more pressure on the federal government, which already has one of the highest debt to gdp ratios in the world (over 100%).\n\nDeficit spending and national debt is essentially buying something now and paying for it later. That means that your generation will pay for the spending of your parents - which is all good and well, unless your parents were irresponsible and left you with a bill that you have no hope of paying off. That is what is happening right now in Greece and Japan.\n\nEdit: Source. _URL_0_ shows the debt. Each US citizen is in debt $56,800.\n\nEdit2: Corrected 20% to 14%",
"They don't owe money in the normal sense of debt. The Fed is the largest buyer of 30-year Treasuries by far, which (without getting too pedantic about whether the Fed is a public entity) simply means the government is buying it's own debt. They do this to control the money supply, as when you owe interest to yourself you are effectively reducing the total amount of money in circulation in the future. This theoretically would result in deflation as each unit of money now represents a bigger piece of the pie. Basically, at this level the concept of money takes on a philosophical context where it acts more like a checkbook which you balance over time rather than an absolute unit of value. \n\nThe issue today is that there is way too much money in circulation for GDP to catch up with organically, and there seems to be no sign of balancing the checkbook. So now things are entering a \"new normal\", where the world is expecting the amount of money currently in circulation to be the new benchmark, which would seriously devalue the dollar as GDP hasn't grown at the same rate and you are never returning back to where things started.",
"Let me see if I can bring this closer to LI5:\n\nThere are a lot of people -- and I mean a *whole lot* of people -- who need some place 100% safe to park money that they're not going to spend right away. Just to give a few examples:\n\n* You have any money in the bank? They've got it invested in *something,* that's for sure. Some of it has to be parked somewhere 100% safe so that they can cover at least that much, no matter how bad a day they have on their other investments.\n\n* State governments bring in a lot of money in the first four months of the year, and need some place to park it so that they still have some in December. It's also not unusual for them to borrow a lot of money up front to pay for something really big, but then need to park that money somewhere safe so that they can make monthly or quarterly payments. (If they're paying monthly, why borrow it all up front at once? It's cheaper and more reliable, that way they don't have to vote every month to raise enough money to make the payment.)\n\n* Most retail firms do a lot of business in December. They park some of their December receipts in places where they are 100% certain they'll still be able to get it back out when they order next December's merchandise. Some businesses are even more cyclical than that, like architecture firms that get paid millions to design a building, but only land a really profitable building every couple of years.\n\n* People who are within 5 years of retirement, maybe even farther out than that, need to be able to stop worrying about \"what if my investments tank?\" They need something predictable to park their retirement savings in.\n\nAnd there turns out to be, really, only one place in the whole world that meets both of the following criteria for a safe investment, for the investment of last resort:\n\n* Has never missed a payment, and seldom even run much inflation, and also ...\n\n* Borrows enough money to satisfy most of the world's need for safe investments.\n\nSo as long as the US never misses a payment, they can offer near-zero (or even slightly negative!) interest rates, adjusted for inflation, and still have enough people desperate to loan them money that it doesn't matter.\n\nIf the US were to balance its budget tomorrow, it would mean two things:\n\n1. Federal tax collections would have to go up by about 50%. That might well be enough to crash the economy. (Or it might not. But all at once, it would be a heck of a shock, to say the least.) And also ...\n\n2. Everybody in the world would lose the ability to safely park money in US Treasury Bills, so saving money would instantly become a lot riskier for every individual, company, and government in the world.",
"There's really no good way to ELI5 this, but let me give probably my favorite \"fact\" about international debt as a way to illustrate just how weird and complex a system it actually is.\n\nWho is the largest foreign holder of US debt, what dollar amount do they hold, what is that as a total percentage of our debt? \n\nChina, ~1.3T , 7.2% (why so low? we hold the vast majority of our debt internally). What's the interest rate on that debt? < 0.3%\n\nBut wait... that's only half the fact (group of facts, whatever)!\n\n* What is china's total debt? ~25T (We think. China does its best to obfuscate all of these numbers)\n* Who holds the largest share of that? The US \n* What interest rate do they pay us? > 5.25% \n\nThat's right, we're literally willing to (and do) borrow money from china at 0.25% interest rate (or lower) to buy chinese debt which pays 5.35% or higher (often much so)\n\nI digress: the value of a nation's currency is only loosely tied to the \"value of a nation\" and frankly there are a lot of things a nation can do to \"unpeg\" those two things... you can argue about what the short term or long term effects of our monetary policy will be, but in the end, the value of our nation (relative to other nations) is simply our \"real GDP\" which is comparable to that of the entire EU combined, and comprises ~22.5% of the entire world's GDP. For us to \"feel\" significantly less wealthy than we currently \"feel\" we'd basically have to go into steep recession for a \"very long time\". \n\nThere's a separate argument that other countries could significantly increase their GDPs much faster than us to lower the percentage of world GDP the US holds (which they are definitely doing) but unless I'm sorely mistaken current economic theory holds that this is actually a good thing for everyone, **including** the US. (It's basically a restating of the principal why free trade is \"good\".)",
"The United States can do something nobody else can, which is print money. That means, if the United States borrows money from you, they can pay you back to matter what.\n\nThe problem comes in that when the money has to be printed to be paid out, there is more money in the system and because there is more money in the system, each dollar is worth relatively less than it used to be worth. Everybody's cash saving's are worth less than it used to be which is bad for people, this is called inflation.\n\nRunning a deficit can be a good thing. At times when people have no money, giving them money (welfare: increasing spending), and decreasing taxes(decreasing revenue) can help them through a struggling economy, and inflation doesn't matter as much because many people's savings are drained and the new money is their only money. Even if A dollar is losing value, for people that started with nothing, a less valuable dollar is better than nothing.\n\nWhen running a deficit over a long period of time more and more of the government's money is going to paying interest on these debts every year. Money spent on interest can not be used to help people when the economy is struggling. The government becomes less and less able to help people out when they are spending so much on interest.\n\nThe longer the government waits to pay off the debts the more money it will have to pay back, and the harder it will be to pay off the debt without causing crippling inflation.\n\nThere are times when the economy is doing well, and at this point the United States should not be running a deficit and instead be running a surplus. When the economy is booming, the government should be paying off all the people that borrowed money from them.\n\nThe problem is that even though paying the debts is the responsible thing to do for the future, increasing taxes and decreasing spending pisses people off. Politicians will lose themselves and their parties a lot of votes by doing the right thing... which means they're not going to do it.\n\nWhat all this actually means for the future is that every economic boom we go through without paying off the debts causes the next recession to be harder to handle. \n\nAt some point hopefully we can make the decision to make our good times (economic booms) a little worse (by running a surplus) in order to make our children's bad times (recessions) a little better by efficiently running a deficit (spending extra money on things that are not interest).",
"The US petro dollar is currently the major world reserve currency. So basically, \"we are good for it.\"\n\nWe are good for it as long as we continue to hold major oil reserves in foreign countries, which we tend to do by finding a reason to justify a military invasion of those countries.\n\nIf the US cannot expand into Syria, Somalia, Libya, Iran, etc... the petro dollar will eventually decline in value, and will cease to be the major world reserve currency.\n\nThere is a new development bank now called BRICS, which is led by China and Russia. If these countries were to try and undermine US foreign policy, and restrict our ability to control international oil reserves, then our deficit would become a problem.\n\nNobody can predict the future, but basically our currency is overvalued because we fight wars, and we have collateral so long as we continue to do so. \n\n[Source](_URL_1_)\n\n[Source 2](_URL_0_)",
"CBO projections on our federal interest: _URL_0_\n\nIt will become bad when a large portion of our budget is to pay the interest on all of our debt. Right now it's about 6% of our federal budget, but it's about to get a lot higher. The more we borrow, the more debt we have, the higher our interest payments, the more we need to borrow, etc. Debt is a runaway train when you can't pay it back.",
"Hi, I'm an economist. \n \nThe reality is that debt is one of the few things that people who aren't economists feel like they intuitively understand, so it's frequently used as a talking point when referencing \"the economy\" \n \nUnfortunately, the debt of a nation state and the debt of family are about as similar as ducks and used condoms. The debt of a nation state is one of many, many, (thousands, let's say) variables that contribute to the economic health of a nation state. It is in no way the most important or even a particularly significant one. \n \nTo directly answer your question:\n \n > I'm trying to learn what it actually means for a country and it's posterity to run a deficit year after year.\n \nIt means nothing, in isolation. How much is the country paying for the debt? Where does the money get spent? Who owns the debt? Borrowing at 500% for a 3 month note to spend the money on building gold statues of the nation state's leader is probably a bad idea. Borrowing at .5% for a 30 year note to pay for infrastructure probably isn't.\n \nIf your question is meant as a hand waive towards current US debt buying, it's almost all being bought at tiny premiums, being close to \"free money.\" and is being spent quickly enough that it's almost certainly having a net positive effect on GDP (outside of the actual spending itself). There are arguments that this isn't the case, but I and the vast majority of economists don't find them very compelling. ",
"The most important thing is to look at **where** that financing comes from, and this is why debt in the US is not a problem.\n\nYou've heard about Greece's debt crisis. Their debt load when the crisis started was about 100% of their annual GDP (i.e., if it was somehow possible to divert every penny of economic activity to paying off accumulated debt, they'd be free in about a year).\n\nBut have you heard about the Japanese debt crisis? No? Because there isn't one, even tough Japan's national debt is 230% of their GDP. Yep, after adjusting for the size of their economies, Japan is in a hole that's 2.3 times deeper than Greece's, yet that doesn't make the international headlines.\n\nThe US national debt is also around 100%, and that's not all that bad, actually. For historical perspective, at the end of WW2, it was around 130% of GDP.\n\nSo what makes Japan and the US different from Greece? Greece borrowed money from foreign entities. Over 90% of Japan's debt is owned by the Japanese. Essentially, Japan owes itself money. Similarly, the vast bulk of US debt is held by Americans. This is why there's no debt crisis--when the money a government owes is mostly to their own citizens, there's no problem. It's not a \"mortgaging of our future\".\n\nWell, not quite true: There is a problem. It means that government is spending more than it's collecting in taxes. This is not surprising, given how much the top *marginal* rate had been cut over the years. Back when Eisenhower was President, the top marginal rate (paid by the richest) was **over 90%**. George W. Bush cut that from 39.6% to 35%. Although most of us directly or indirectly (through retirement funds or bank accounts that, in turn, invest in government debt) own some of that debt, much of it is owned by the wealthy (in fact, one reason why interest rates are so low is because during economic downturns when stocks and other assets are decreasing in value, buying up US Treasury Bonds was basically the safest investment anyone could make--yes, the Fed sets target rates, but that's only half the picture--there's still lots of demand in the market for Treasuries even though their yields are at historical lows). Essentially, this high debt represents a long-term wealth transfer from the poor to the wealthy, as it's money government owes mostly to the rich, at a time when the rich are paying a decreasing share of taxes.\n\nFinally, you'll notice that I've left out China. They hold about a trillion in US national debt. That's a big headline-grabbing number. But it's largely irrelevant for a few reasons. First, a trillion is only about 10% of US debt. Second, they hold this money because US Treasury Bonds are sold on the open market--i.e., anyone who wants to buy them can buy them. It's not \"Oh, we can't find someone, so let's turn to the Chinese\", but rather, \"They happened to want to buy them, and we don't discriminate\". If they were to somehow stop buying them, there's still plenty of demand. Finally, the reason China snaps up so many Treasury Bonds and other dollar-denominated assets is because they need to in order to maintain their currency manipulation. China is deliberately making sure their currency is undervalued, and one way to achieve this is to buy up tons of foreign-denominated assets to drive up the demand (and value) of the dollar and other currencies relative to the Chinese RMB. Why does China want a strong dollar? Because a strong dollar means that Chinese exports are more competitive in the US and US exports are less competitive in China. Judging from the disparity between China's nominal GDP and PPP GDP, the Chinese RMB is about half of what it's really worth. In other words, if China stopped buying US debt and doing other things to manipulate their currency, imported Chinese goods will cost twice as much--that would fix our trade imbalance pretty quickly.\n\n**Edit:** Also, when our debt-to-GDP ratio has gone down in the past, it's mostly by the GDP growing faster than the debt. If the debt represents the government investing in the economy (education, infrastructure, etc.), then this investment spurs growth in the GDP. Also, people have mentioned that because our debt is denominated in dollars, we can print our way out of it if we wanted, and I'd like to add a couple of comments to that. Yes, this is true (though in today's economy, it's more about bits in the Federal Reserve's computer than actual ink-on-fiber). There are downsides to this, and it's more of an escape hatch than something that would actually be used. That said, \"printing money\" isn't always necessarily bad: inflation/deflation is complicated, as it's the result of the supply *and demand* of money as well as things that are entirely out of the purview of monetary policy, like global oil prices. The Fed controls the supply of money and nothing else, which means even if the Fed does not change the supply of money at all, there would still be inflation or deflation from those other factors outside of the Fed's control (this is also the ELI5 for why the gold standard is idiotic and anyone advocating its return is dangerously ignorant). The Fed's goal is to use its control of the supply of money to counteract those other forces in order to maintain a stable price level, with a healthy, modest amount of inflation (too much inflation is bad, but deflation is even more dangerous, so the Fed tries to steer things towards a optimal middle ground). So the Fed has been \"printing\" a lot of money of sorts during the financial crisis, because the economy was about to nosedive off a deflationary cliff--not to pay off US debt (because, again, that's more of an emergency escape hatch), but to stabilize price levels. (In contrast, the European Central Bank, which hasn't been well-governed and lacks the level of political independence of the Fed--they were beholden to Germany's dogmatic worship of austerity--refused to use quantitative easing until it was far too late, which is why parts of Europe sank into the deflationary quicksand and imploded.) And in times of runaway inflation, the Fed tightens the money supply (e.g., Volker in the early 1980's).",
"It's kind of like if you are fresh out of high school and decide to go to college. You can take out a loan and pursue your degree, but at the end of the year (or 4) you will have a degree that will let you pay off every debt you have to date. \n\nExcept this process continues forever, and you consider yourself to be immortal. So you are constantly improving yourself through an expense you can't quite pay for now, on the promise that it will make you better able to pay it off in the future. As long as you are improving yourself faster than that debt is rising, then it's ok that the amount is increasing.",
"\"This note is legally tender for all debts public and private\".\n\nIn the US, money *is* debt. The US backs it's currency. So think about it. Think about the first dollar bill that the US ever issued (theoretical thought process). Prior to that, the US had no debt. But once they issue that first dollar bill, they have made a promise to back that dollar - providing its value. If you create an obligation for yourself, you have a liability. You have debt.\n\nEvery time the US issues money, they are creating more \"debt\". Your money is their debt.",
"It's only been sustainable due to dollar hegemony. There is currently a big move to end the dollar as the reserve currency and when that finally happens you can bet life is going to get uglier for a whole lot of folks. ",
"TL;DR\nThe general justification is that you assume in advance that the money you borrow will be used to generate a higher GDP for the country next year (and thus an increase in tax revenues), and would end up paying for itself plus more. So it's sort of a gamble.\n\nCongress are idiots however, and overall they end up contributing to a higher national debt every single year.",
"It means nothing. Money is imaginary. Let's go to Disneyland",
"Heres my understanding\nDeficits and the resulting debt is menacing however the reasons countries really dont worry much about them is:\n\n1) most debt is paid in the counties dollars to bond holders, realistically no one coutry can hold a worlds worth of debt a lot comes from people in the country buying bonds and dollars\n\n2) most debt in held in currency of the countries in debt so if worse comes to worse they can simply print more money and inflate themselves out of a lot of debt, ie lots of paper floating about but not worth much. \n\nThis of course is super bad for there future and for thier citizens but does tend to do the job. \n\nThis was why the debt and deficit crisis was so bad in the euro zone, coutries like greece were tied to the euro and could not just print up more to deflate thier currecy and lower the real value of thier debt and make it easier to pay so they would have had to default but remember most of thier debt holders are also in euros so they might have brought stink on the whole euro zone by defaulting. It pays to have your own currency. Incidentally I believe this is what the US did they called it Quanitative easing= print more money",
"Everybody in this thread should read Debt: The First 5000 Years. Extremely enlightening on all manner of debt/credit related topics, including deficits.",
"The USA's shit don't stink. People buy our debt and are like \"yeaaah this be some choice stuff\". You see because we're like the Lannisters and always walk our pets. ",
"Something that should be kept in mind with economics is that it has a variety of schools of thought like in politics. While there are a lot of things that economists agree on, the consequences of running high deficits and what qualifies as high deficits is heavily debated. \n\nI mention this because the comments I am seeing seem to suggest that the U.S. does not have a current deficit or even debt problem. The vast majority of economists from schools across the spectrum would very much disagree.",
"The US can run a deficit because it borrows money in dollars, pays the debt in dollars, and prints dollars. The debt is slowly eroded by inflation. Countries lend the US money because we pay our debts. ",
"Triffin Paradox or Dilemna: The Triffin dilemma or paradox is the conflict of economic interests that arises between short-term domestic and long-term international objectives for countries whose currencies serve as global reserve currencies. This dilemma was first identified in the 1960s by Belgian-American economist Robert Triffin, who pointed out that the country whose currency, being the global reserve currency, foreign nations wish to hold, must be willing to supply the world with an extra supply of its currency to fulfill world demand for these foreign exchange reserves, thus leading to a trade deficit.\n\nThe use of a national currency, such as the U.S. dollar, as global reserve currency leads to tension between its national and global monetary policy. This is reflected in fundamental imbalances in the balance of payments, specifically the current account, as some goals require an outflow of dollars from the United States, while others require an overall inflow.\n\nSpecifically, the Triffin dilemma is usually cited to articulate the problems with the role of the U.S. dollar as the reserve currency under the Bretton Woods system.\n_URL_0_",
"Doesn't mean shit. Money = debt. Debt = money.\n\nIf every person, company and country paid all their debt tomorrow, it wouldn't add up. There is more debt than there is money. It's impossible to repay the debt.",
"Growth is what keeps the debt monsters away. Imagine you have a small business. as long as you keep expanding and growing, you can keep borrowing money to pay for more growth. Once you stop growing, you can't pay the piper anymore and are in trouble. Is this \"bad\" for us? yes and no. It's great for the short term or even long term. borrowing is what finances growth for many businesses that make it big. It can also increase your losses when it slows down. It depends on the nature of our GDP (value of stuff we make) for the next several decades, the value of our currency, and the ability of other economies to interact with us.",
"It depends on how it's handled, either we becomes serfs to debt interest or we are robbed by inflation. \n\nI can assure you the same people who think it's good are the same people 100k in debt with a worthless degree.\n\nThe ROI on government spending is abysmal. ",
"A fiscal deficit literally just means that government spends more money than it makes. It thus runs into a debt (if this pattern is continued). What do *you* do when you are in debt? You borrow money. \n\nThis is the same on a national level. But is it a problem? Well, if you make $2 a year, a debt of $2.50 is pretty significant, right? However, if you make $1000000000 a year, that $2.50 of debt doesn't matter. So it's not just the level of debt which matters, but it's also your income (and how the two relate). Again, this is the same on the national level. Right now, the public debt in the states represents 72.5% of their GDP (a measurement of a country's income). This is pretty high, but they are at no immediate risk of defaulting on their debt (this is the national equivalent of filing for bankruptcy). However, if it keeps moving upwards, then alarm bells definitely will start to ring and not many people will give them loans (as they know they won't see the money again). At this point, a country is screwed and historically this is where countries start to print money and run into hyperinflation.\n\nThe immediate problem is that countries have a credit rating (just like you do). This credit rating determines at what levels of interest you can borrow money from. If people feel that you are an unreliable economy, you will be rated as such and thus any loans made to you will be seen as riskier than before. That risk has to be compensated by a higher price (so that even though the loan is riskier, it's more profitable) and this comes in the form of a higher interest rate. The U.S, and many other countries, are currently at risk of having their credit ratings downgraded because the powers that be feel that big strides need to be made to lower the levels of debt. If the credit rating is downgraded, then borrowing money becomes more expensive, which will mean more debt (because a country, just like any decently sized company, needs to borrow money to finance whatever it is they do) and we will go into a vicious cycle.\n\nI would also like to say that people are very happy to lend to the U.S because they're so important that a poor U.S economy would negatively affect them (plus the U.S trades with a lot of countries, so chances are, whatever your country is, they trade with the U.S and thus they need the U.S economy to be healthy).",
"As every year it seems to take more \"tax days\" to pay off the interest (is this true?) will we reach a point we cannot sustain our interest payments on the debt and what will happen then?",
"Not that difficult.\n\nIt takes X amount of money to pay for the programs and things each and every year. Taxes are essentially the government's \"salary\" - thus its called \"tax revenue\". Each year, that tax revenue is less than the amount it costs to run the aforementioned programs. That difference is the yearly deficit, and it gets added to the total money we owe (from previous years), which is the total debt.\n\nThis is a graphical representation of where the money goes (as of a few years ago):\n\n_URL_0_\n\nThere are 2 ways to reduce or eliminate the deficit. Take in more money, or use less of it. The reality of the situation is that you need to do both. The easiest and best way to do that in my opinion is slash the Department of Defense's budget which is one of the top 3 single largest expenditures of money. The other involves taking in more money. Currently large corporations are essentially hiding TRILLIONS of dollars offshore in other countries so they don't have to pay US taxes on that money. If even 1/2 of that money was taxed by the US, it would eliminate our yearly deficit. And to be clear, I'm not talking about TAKING that money outright... I'm talking about simply taxing that money at the current corporate tax rate just like all other companies have to pay. ",
"It's not all that bad think, nations and companies have invested trillions in us. Imagine what would occur if we went to war or dell apart, the debt would be at risk of being erased. It keeps others invested in is, because the loss is too great.",
"Hey little Nicky! Posterity is quite a big word for a 5 year old! The United States runs a deficit when it spends more money than it makes from asking people and businesses here to pay chunks of money called 'taxes' every year. It can spend more money than it makes by selling contracts called bonds that say the government has to pay back a big amount of money called principal plus small amounts every year called interest. Luckily, other countries of the world rely on American money for their own bank accounts and the US is the best about making sure it fulfills those contracts so the government can sell as many of those bonds as it needs to and only pays back an extremely small amount of interest. It's almost like free money that we can spend on helping people by building bridges and schools and having a military! It's okay for us to have a deficit that isn't too big since it lets the US spend more on things that will allow people and businesses to make more money, which will give the government more in taxes! Today, we also sell bonds to pay for other bonds. The problem is those interest payments, as small as they are, and those principal payments are going add up every year to a number called debt that will get so big eventually that the world might decide to use another country's money for its bank accounts, which is not good for the US bank. Other countries then might think the United States' money isn't that great anymore so the country won't be be able to sell bonds anymore cheaply.\n\n\n\nWhen the world decides it doesn't want to buy US bonds anymore, the country will have a bad day at the bank where something called a 'default' happens when there isn't enough money to pay back bonds and the US comes to some agreement to pay back what it can. This will make interest payments rise a lot on future bonds so our money won't be 'free' anymore and we won't be able to spend enough on our people. If the US doesn't want to default it can just print more money to pay back bonds, but this is also bad because it makes American money worth less and a lot of our people won't be able to afford things and live such good lives anymore.\n\n\n\nDefault doesn't have to happen, though, since the world might always depend on American money so our money is always 'free,' or we could just not have deficits anymore by bringing in more taxes than we spend. To do this, we can raise taxes, or spend a LOT less. Right now we need to find a good balance of doing both of those.",
"US debt is not the same as personal debt. US debt is sold as a point of investment in the form of government bonds. It is also one of the safest forms of investment as the US has never defaulted on any of its bonds when they have come due, and they do not all come due at once.\nWe also have a better debt to GDP ratio than most developed countries and half that of Japan.\nAlso 60% of our debts owned by the US. Divided up among various parts of the government, corporate investments into bonds, and private citizens investments into bonds. The rest is distributed among dozens of countries with China owning about 8% of our total debt.\nThat and external debt to other countries tends to be with countries who owe us a lot back too, so the ledger after being balanced is a lot lower. Not to say it isnt a big issue, US still has the largest external debt of any country.\nHowever... other countries have much larger debt relative to GDP, we have like 80% more external debt than the UK, but its about equal to 1 year of our GDP... the UKs external debt is like 400% higher relative to GDP.\nIn terms of 1st world countries, the US is slightly lower than in the middle in terms of $ amount of external debt per capita, course we have a lot more people...\n",
" < aiming for 10 year old, 5 is too simplistic > \nDebt is a claim on future production. So debt is saying I'm owed a barrel of oil or the services of a nurse (a dollar is used placeholder, but the amount that a dollar buys you changes over time). If the United States creates a lot of debt, there will be a lot of claims on production in the future. Since there is a fixed amount of wealth and production in the future, this will just make the claims worth less.\n\nNow debt can be good, if its used today to build wealth and production for tomorrow. For example, using debt to create a nuclear power plant will create more production in the future. However, the United States is not spending most of its debt on productive purposes. Most of the money goes to the military, paying people to work and create little value, or essentials for poor or unfortunate people. While these things may be good things, they don't create production or wealth. So that means our collective wealth and savings will be worth less in the future. There will be more claims on future production.",
"US Dollar is a reserve (world) currency. Only United States can print it though. This means US can theoretically borrow a lot more than any other country could, and pay with printed dollars. Huge advantage.",
"Edit: formatting\n\n1. It runs it with an inflation policy\n\n2. What this means is that your purchasing power decreases with every new generation and you are poorer even though the numerical value of the paycheck increases. \n\nIt is a generational transfer of purchasing power (aka theft).\n\n",
"All these rosy outlooks on the national debt are so laughably naive its ridiculous. With the way things are heading the good ol' USA is fucked big time. Entitlement spending is soaring as more and more people retire and revenues are not increasing to match the burden, which is a large reason why we keep getting in to more debt.\n\nPersonally, I believe we are in what I like to call the \"credit run up phase\" which is one of the last steps before bankruptcy. Basically charge as much as you can while you can because sooner rather than later nobody will be giving you credit anymore. I predict in the next 20 - 30 years we will be so far down the hole, our interest payments so sky high that the only reasonable action will be to declare bankruptcy and default on all loans. It will happen when we hit 75-100 trillion in debt. Its not that far off the way we are headed and the interest payments alone will dwarf the entire budget.",
"Money hasn't been real since we left the gold standard.",
"there are complicated metrics, but it really boils down any loan comes down to do they think you can pay them back? what's the chance that you don't. the us hasn't defaulted on loans and the system is basically set up to make sure we pay off our bills. \n\nno one figures the us will default and has no problem lending them money despite an enormous debt. they're going to get paid. ",
"for the future?? lol...we're effed. numbers dont lie. look up the numbers. unemployment. debt. inflation. immigration. automation. they do not lie.",
"A deficit is just a bet that you'll make more money in the future. As long as the economy keeps growing, you can afford to pay off your debt -- and get even more debt! If the economy shrinks, of course, then you lose your bet. The US has a very good credit rating, which means that it's generally considered to be able to pay back money that it borrows.\n\nIt's good to borrow money every year, so long as you can pay it back, because that means that you have more money available. As an example, let's say you have $10, and you borrow $1. Now you have $11, but you need to pay back the $1. Let's say that your money grows by 10%. You had $11, and 10% of that is $1.10 so now you have $12.10. You pay back the $1 you owe, and now you have $11.10. If you *hadn't* borrowed any money, you would have had $10, your money would have grown by 10%, and then you'd have had $11. So you have 10 cents more because you borrowed a dollar than if you hadn't, and you paid everything back! So what do you do? Borrow $1 again and repeat the process!\n\nIn real life it's a *lot* more complicated than that, but that's the basic idea.",
"The biggest problem is that even in times of economic boom, no elected official will condone increasing taxes. In recessions, every elected official will support decreasing taxes and increasing spending.\n\nSo democracy shall forever be stricken with public debts.",
"Money is not well understood, even by supposed experts, as they often leave out essential facts. First off, when the Fed loans the U.S. Treasury \"money\", by buying \"bonds\" (Treasury instruments), the money is fake right from the beginning. That is it is made out of thin air. There is no pile of money anywhere, it is effectively printed on the spot (not literally, but effectively since it all happens in computers).\n\nThese \"bonds\", which are debt instruments of the U.S. Treasury (aka the \"taxpayer\") get sold on open markets and are bought in many places, such as China (which as we know holds many many billions of this kind of Ameican debt).\n\nOur Congress and the rest of the federal government, run on a budget. The budget is based on anticipated tax revenues. The Congress then spends (the Executive Branch only spends what it is given to spend in the \"budget\") money on all kinds of stuff, and periodically runs out of money in the budget that comes in from tax revenues.\n\nSo, the shortfall (the money borrowed from the Fed to pay for what we don't have money to pay for) is called the \"deficit\". \n\nSo, a private bank (the Fed is a private bank), that was given unconstituional power to \"coin money and regulate the value thereof\" around 1913 etc., prints money out of nothing, loans it to allow the government to pay the bills it doesn't have tax money to pay for, and these treasury \"bills\" (debt) are bought and sold to other banks and nations.\n\nFor a long time the dollar was so highly valued, this wasn't a problem. Congress could spend what it wanted, borrow what there wasn't taxes to pay for, and kick down the street the debt to the future generations. For example, the wars in Iraq and in Afghanistan were financed by unbudgeted money - i.e. debt, which each citizen now owes (supposedly), to the tune of about $30,000 each or something like that.\n\nJust keep in mind that this situation is far worse than this. For example, Congress robbed the Social Security Savings Funds in the 1970's and '80's to pay for stuff there wasn't otherwise money for, which is why young peoples FICA taxes are needed to pay for all those \"entitlements\" out of current tax money. Congress also is ruining the Post Office by demanding (only of the Post Office, no one else has to do this), that it fund (save) for 75 years in advance, all its retirement obligations. This saves Congress from having to do that too.\n\nMeanwhile, the international money situation grows worse daily, because nothing that led to the 2008 debacle was ever fixed, and banks get to take all the risks they want, in part because our Fed in 2008-2009, created out of nothing 17 trillion dollars which it loaned (gave away) to multinational corporations and other central banks so that the international \"financial\" system would not collapse, which it was threatening to do at that time.\n\nModern predatory student loans come from the same source. It is fake money, which banks create at the time of the loan, and for which they are charging students horrible rates and fees.\n\nThe supposed \"reason\" for this kind of lending is that this is how a consumer culture has a fluid currency in circulation - via commercial loans (including credit cards). The fake money (regular banks have to have 10% of the value of the outstanding loans on reserve, but in practice get around doing this) goes through the pockets of students, and into the pockets of universities and colleges, and then circulates through the whole economy. Sadly, this way of circulation of money leaves behind legal debt obligations among those who originally receive the money from the banks.\n\nSee Economic and Social Rebellion for other details and possible solutions: _URL_0_",
"a bond is basically an IOU that says that you will pay money back to the person that bought it from you with an interest on the money loaned to you.\n\nAmerica does this on a much larger scale and sells their bonds to other countries. When the bond is due, America just sells more bonds so that it can pay back the bond that it originally sold. In theory, America could do this forever assuming that other countries trust America will pay them back. But, if a country like China (who owns more than 20% of Americas bonds) thinks that America will not pay back the loan, then they can just not buy bonds from America anymore which will cause the entire America economy and the rest of the worlds economy to crash.",
"Running a deficit means the value of your hour of labor will dwindle, you wont be able to work enough hours in the day to pay your taxes, which pays for the interest on the deficit, the entire system is going to crash and there will be a catastrophic failure of government and financial institutions. Banks will be overwhelmed with trying to collect from accounts that cannot pay. So, use every means at your disposal to maximize your personal debt and enjoy life now, because it is going to get pretty difficult when everything collapses. ",
"A deficit means we're spending more money than we take in as revenues. A lot of this comes from taxes but there are other side deals we have that earn us a bit of money.\n\nIs it bad? Not really.\n\nPeople get all up in arms about our national debt but in reality it's meaningless. Nobody is going to call in our debts, nobody is going to twist our arm, because if it does come to that we can flip them the bird and say no. What are they going to do? Most countries need us for foreign aid or as a trading partner. Our military is the best equipped in the world. \n\nWe essentially have a credit card that, as long as we throw a few bucks at it every month we can run it up as high as we want."
]
}
|
[] |
[] |
[
[],
[],
[
"http://store.steampowered.com/app/245470/"
],
[
"http://www.nationaldebtclocks.org/debtclock/unitedstates"
],
[],
[],
[],
[],
[
"http://www.peakprosperity.com/podcast/91503/gail-tverberg-beginning-end-oil-production",
"http://www.globalresearch.ca/russia-and-china-the-dawning-of-a-new-monetary-system/5423637"
],
[
"https://www.cbo.gov/publication/45684"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://en.wikipedia.org/wiki/Triffin_dilemma"
],
[],
[],
[],
[],
[],
[
"http://static.flickr.com/75/189476575_2bb83d5fb5_b.jpg"
],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"http://ipwebdev.com/hermit/Rebellion.html"
],
[],
[],
[]
] |
|
bsvjrp
|
why do people lease cars? it seems like such a waste of money to me.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bsvjrp/eli5_why_do_people_lease_cars_it_seems_like_such/
|
{
"a_id": [
"eoqvo5x"
],
"score": [
3
],
"text": [
"For some people, like sales people who travel a lot, need a new car every 2 or 3 years and can take a business deduction, it can make sense. \n\nFor anyone else, it's the appeal of the nice car for a lower monthly payment. It's not the frugal choice, but people can be taken in by the hype, or they just really place a lot of value on driving a nicer car than they can afford to buy outright."
]
}
|
[] |
[] |
[
[]
] |
||
4n1rdw
|
why can't dogs and cats be tickled?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4n1rdw/eli5why_cant_dogs_and_cats_be_tickled/
|
{
"a_id": [
"d402vnl"
],
"score": [
2
],
"text": [
"They can. Many animals can be tickled. They just can't *laugh*, so perhaps you're not aware of it, but they can be tickled. "
]
}
|
[] |
[] |
[
[]
] |
|
2gaa6b
|
why there are emulators for pc about almost all known consoles, but the 3ds?
|
I wonder why this has happened since it's release, but time is no longer a reason. If the screen is, why not an emulator in 2D? Is there some problem that I'm overlooking? Finally, if there's any **legit** emulator, please let me know.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2gaa6b/eli5_why_there_are_emulators_for_pc_about_almost/
|
{
"a_id": [
"ckh5e95"
],
"score": [
5
],
"text": [
"u wot m8? Emulators usually get done many years after the release of the console. There isn't an emulator for any of the current-gen consoles, and the previous gen ones are still in early stages of development."
]
}
|
[] |
[] |
[
[]
] |
|
3zb0pz
|
why/how university became just as well known for partying, sex and drugs as for educational purposes?
|
And is this a global thing? I'm from the UK and I know the US is similar to, but other than, question explains itself. Thanks in advance!
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3zb0pz/eli5_whyhow_university_became_just_as_well_known/
|
{
"a_id": [
"cykm006",
"cykm4c4",
"cykmg4u",
"cykpnvw",
"cykpss3"
],
"score": [
5,
11,
37,
5,
2
],
"text": [
"Because they are the places where children go and are not under their parents' watch for the first time in their lives. Wherever this place is, whenever it happens, it will also be known for partying, or whatever the cultural equivalent of that is.",
"what do you think will happen when you put 18-22+ year olds in an environment without parental supervision? people are curious, they like to experiment, find out what their identity is away from home. university is the best place to do this",
"i honestly have no idea why it is that when you put 50,000 teenagers on their own for the first time in their lives..they tend to have sex and party. not a clue. ",
"It's all about marketing. When I applied to university, every pamphlet for the one I chose touted the university as \"Canada's best research -intensive university\" and bragged about their accomplished alumni and professors. This type of marketing attracts a certain type of student. \n\nRecently, they changed their name to something less esteemed (The University of Western Ontario to simply Western University. All of their marketing materials toute \"Canada's best student experience.\" They promote the 500 clubs, the facilities, the residences, the activities. The education aspect is secondary to the social experience. This attracts a different type of student. \n\n",
"I don't think OP's question is \"why is there sex, parties and drugs at colleges\", but is rather \" what factors cause each of these colleges to gain a reputation specifically for either their sex, drug, or party scenes\".\n\nTo put the question in terms of academics, OP isn't asking \"why do colleges have degrees\" but is instead asking \"what causes specific colleges to become law colleges, or medicine colleges, etc.\""
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
zncig
|
in films and on television, how do they make the same person appear on screen twice (i.e. the parent trap, etc)?
|
I have always wondered this. Some examples I can think of off the top of my head include The Parent Trap, Friends (when they have Pheobe and Ursula together), and basically any other production with twins who are really the same person in real life.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/zncig/eli5_in_films_and_on_television_how_do_they_make/
|
{
"a_id": [
"c6630no",
"c6630sf",
"c664txl",
"c66eio3"
],
"score": [
9,
4,
2,
3
],
"text": [
"Back in the olden days (B & W and silent films) they would literally glue two pieces of film together to make it appear as if two people were in a scene. Nowadays the technology is so advanced that they just layer to pieces of footage over each other. It's incredibly easy. The only tricky part (and even this isn't that hard) is to get a body-double that looks just like the other person, for those over-the-shoulder shots (where you see the back of one persons head and their shoulder, and the other person staring at them). This helps further the illusion.",
"They shoot the first take live against a real set. They do the second take against a green screen, and then use a computer to splice them together.",
"What about the way the camera spins around the two Leonardo DiCaprio characters in \"The Man with the Iron Mask\"?",
"This annoyed me beyond belief in The Parent Trap. BUT HOW DID SHE PIERCE HER OWN EARS?"
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
911cyc
|
what makes materials hydrophobic?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/911cyc/eli5_what_makes_materials_hydrophobic/
|
{
"a_id": [
"e2uruq4"
],
"score": [
2
],
"text": [
"Generally, hydrophobic (literally \"water hating\") materials are called \"non-polar\" whereas hydrophilic (\"water loving\") ones are considered \"polar\". Since water is polar, it only likes polar things, and so the non-polar material doesnt like water and so they stay separate.\n\nYou can imagine it as such. Chemicals are made up of protons, neutrons and electrons (without getting too into all the sub particles). Every chemical has a different tendency to \"want\" electrons. Think of it like someone who only has $10 to his name will go out of his way to pick up a $5 bill, but someone who has $10,000 wont really go around and chase it all that much. Chemicals are the same way with electrons: some of them go out of their way to pick up more electrons, others are just like \"meh you can have it, i dont care\". So when a chemical that really wants electrons meets one that wants to give it away, the reaction can be intense (this is why pure lithium must be stored in an oil and not air, because the oxygen in the air really wants to take the electrons lithium desperately wants to give away, sorta like shoppers during black friday)\n\nIn a covalent compound, there isnt a direct transfer of electrons, but a sharing. Depending on the degree each chemical \"wants\" the electrons, it will pull it more to its side. Think of it as one parent getting custody M-F and the other gets only weekends, with the child being the electrons. When this imbalance occurs, molecules are said to be polar (polar like the pole of a magnet, i.e. there is a more negative end, that which hogs the electrons, and a more positive end, that which usually doesnt have the electrons) If the two chemicals pretty equally share the electrons, then the molecule becomes non-polar since there is not one side that sees a more negative charge from having more electrons. \n\nSo a hydrophobic material is non-polar because its chemicals equally share the electrons between everyone. Most commonly, these are carbon-hydrogen compounds. Thats why things like tar have been used for 1000s of years to keep the hulls of boats more water resistant. Tar is extremely long chains of nearly only carbon and hydrogen, so it acts as a barrier between the sea and the boat (which regardless if its made of metal or wood would still like the water to some degree). "
]
}
|
[] |
[] |
[
[]
] |
||
3jaak1
|
how come people who are crossing europe illegally are considered migrants and not illegal immigrants?
|
More and more we see "migrants" leaving Syria and other countries to come to Europe. Some pay traffickers and go by boat. Why are these people considered migrants and not illegal immigrants?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3jaak1/eli5_how_come_people_who_are_crossing_europe/
|
{
"a_id": [
"cunln4n",
"cunti54"
],
"score": [
10,
2
],
"text": [
"Well a migrant is just somebody who travels, could be an immigrant or an emigrant. As for the North African and Middle Eastern immigrants, they're refugees of a war zone so referring to them as \"illegal immigrants\" creates a certain stereotype which they don't deserve. ",
"Immigrant means a person who goes to a country with the intention to live there permanently. \n\nEmigrant means a person who leaves their own country to live permanently in another country.\n\nMigrant means people who leave one country but not necessarily permanently. Perhaps just temporarily. And that's a general assumption about these people--they're fleeing a war, but it doesn't mean they want to leave their country or that they intend to remain permanently in the place where they've fled to."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2b5ee9
|
how does color printer ink create the separate colors?
|
Is it one cartridge filled with a single fluid that can create the individual colors? If so, how?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2b5ee9/eli5_how_does_color_printer_ink_create_the/
|
{
"a_id": [
"cj1yds6",
"cj1yht1"
],
"score": [
2,
2
],
"text": [
"In fact only 4 colours are used in most printers: _URL_1_ \n_URL_0_\n\nAll the colours you see in printed photos are combinations of these inks. The printer doesn’t mix them to get other colours though, they sort of get mixed by your eye. This [picture](_URL_2_) is purple if you zoom out, even though not a single purple pixel is present. Tiny dots of 4 colors are separate in printed pictures if you look with a microscope.",
"Printers have four separate inks CMYK. Cyan is light blue, Magenta is bright red/pink, Yellow is yellow and K is Black (for some reason). These are the basic colours you surely had to deal with in elementary school. Mixing them together creates the rest."
]
}
|
[] |
[] |
[
[
"http://www.olympusmicro.com/primer/java/primarycolors/colorseparation/colorseparationfigure1.jpg",
"http://i.imgur.com/MOeiP8d.jpg",
"http://i.imgur.com/jZUSTGu.png"
],
[]
] |
|
2oaj3v
|
why doesn't disney make 'cartoon-like' animated movies anymore? (i.e. the lion king, aladdin, etc.)
|
I think Pixar has done phenomenal work since Toy Story up to Frozen, but why did they do away with the beautiful art of drawing the characters?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2oaj3v/eli5_why_doesnt_disney_make_cartoonlike_animated/
|
{
"a_id": [
"cml9mb1",
"cml9r1z",
"cmla1g2",
"cmlh3la"
],
"score": [
6,
2,
6,
5
],
"text": [
"Their last two hand drawn movies didn't do great in the box office (The Princess and the Frog, Winnie the pooh) but two CGI movies that came out around the same time did fantastic (Bolt, Tangled.) The industry was already leaning away from hand drawn 2D, and that was pretty much the final nail in the coffin for Disney. \n\nSome disney 2D animators have got together to produce their own film, [Hullabaloo](_URL_0_)",
"Disney saw falling returns on their animated films, considered to be in part from increased competition and declining fashionability, versus increasing gains in their computer animation, through the late 90s and early 2000s. This lead to downsizing and eventual closing of much of their animation capacity, and acquisitions aimed more at CGI production.",
"Hand animation is insanely expensive. They have to hand-draw every character and paint backgrounds. It takes 32 still images per second to create moving picture.\n\nAs weird as it seems, CGI is much, much cheaper.",
"Look at this YouTube video for historical background. _URL_1_\n\nNote: I count The Great Mouse Detective as the start of the Disney Renaissance. Even if someone disagrees with that judgement, they'd have to agree that The Great Mouse Detective at least represents the studio gearing up for the Renaissance. This is because I tend to group the eras more by who is working there and what they're doing than by how much money their features make at the box office, and also because I just really love The Great Mouse Detective.\n\nNow, with that background out of the way, I have to point out some things:\n\n1. Pixar is a separate studio from Disney Animation Studios. It is owned by the Disney company, but it is not part of Disney Animation Studios. This means that there is very little overlap in terms of how the films are produced between the groups working on Disney films where you see the Pixar logo, and Disney films where you do not. Disney didn't exactly develop Pixar -- Pixar developed from the folks who made The Brave Little Toaster movies when they decided to switch to CG -- and then Disney bought Pixar. So movies like Bolt, Tangled and Frozen have nothing to do with Pixar -- they are from the same studios as the classic Disney films, while Toy Story, Cars, Bug's Life, Incredibles, Up etc. have nothing to do with Disney Animation Studios. Is it weird for Disney to own two completely separate animation studios that make very similar films which risk competing with one another? Yes, that is very weird, but that's just how big Disney is. They also own studios that are working on Marvel comics, Star Wars and Muppets stuff. Disney has repeatedly shown that they will buy anything from your childhood if it is for sale and slap a Disney logo on it. _URL_0_\n\n2. Hand drawn animation is much more expensive to produce than computer animation. One way to understand this is to think about how every single frame has to be drawn manually in an animated film. Not just the major poses like in a comic book, but **every single frame.** That's **24 frames per second** unless I'm mistaken, and audiences may be coming to expect an even higher framerate due to CG and live action films starting to adopt higher framerates in order to keep up with console video games, which are trying to adopt higher frame rates in order to keep up with the Glorious PC Gaming Master Race, who have been gaming at 60 fps for more than a decade. /r/pcmasterrace In computer animation, all the animator has to do is to set up the main poses, and then tell the computer to calculate the in-between frames. This, and many other uses of automation, means that the man-hours required to create computer generated animation footage is much less, and man-hours is one of the most expensive things for an animation studio. As a result, there is a strong financial incentive to prefer CG animated films over traditional animation.\n\n3. However, there is more to it than just costs. There is also the issue of audience expectations. When compared to Pixar's computer generated films, traditional animation was looking very dated and relatively unappealing to audiences at the time \"Home on the Range\" was produced, and Home on the Range was a total box office bomb that cost them lots of money. So the thinking, coming out of that, was that audiences were just done with that type of film. It was a somewhat reasonable analysis based on what was known at the time. I wouldn't attack Disney for that decision -- because the Pixar films really were very good. Shrek's satire of worn-out Disney cliche's also had something to do with it on an emotional level, I think.\n\n4. Reasonable as it seemed, that analysis turned out to be wrong when it was tested by Disney's grand experiment we call \"Princess and the Frog\" in which Disney decided to give traditional hand drawn animation one more chance. And man, it really did shine when given that chance. \"Princess and the Frog\" showed that the reason \"Home on the Range\" tanked was not because it was upstaged by CG. The reason was that \"Home on the Range\" **just wasn't a very good movie.** There are enough people who really love to see the hand-drawn stuff that it will be back (probably with much help from more subtle advances in computer graphics) for a long time to come."
]
}
|
[] |
[] |
[
[
"https://www.indiegogo.com/projects/hullabaloo-steampunk-animated-film"
],
[],
[],
[
"https://www.youtube.com/watch?v=uyYb_r4cZHE",
"https://www.youtube.com/watch?v=n2a4EBbbISo"
]
] |
|
551dvc
|
the reason why nsaids are ineffective at reducing symptoms of diseases like psoriasis?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/551dvc/eli5_the_reason_why_nsaids_are_ineffective_at/
|
{
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"text": [
"Not 100% sure, but I would say that's because Psoriasis is caused when your immune system ins't working properly and the chemicals involved in psoriasis are not affected by NSAIDS (they generally affect the COX enzymes that promote inflammation)"
]
}
|
[] |
[] |
[
[]
] |
||
scbaz
|
why gas stations promote that their gas is ethanol free.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/scbaz/eli5_why_gas_stations_promote_that_their_gas_is/
|
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"text": [
"We as humans figured out a way to turn corn into a fuel-additive. It's cheaper but our current internal-combustion engines aren't really built to effectively utilize it.\n\nLike you're five...\n\nYou freakin' love some mac 'n' cheese and can eat it all day, every day, for every meal, and be fine.\n\nMac 'n' cheese is a bit expensive so Mom finds a way to mix in some 2% milk and not use as much cheese so she can save a few pennies.\n\nOnly, your stomach isn't used to 2% milk, so you occasionally have cramps. And the milk doesn't provide as much nutrition so you require just a little bit more of it.\n\nEDIT: To angle this towards your original question: They're saying that their gas is better for your engine and not \"corned down\" with ethanol (which may damage your engine and not produce as much energy).",
"Also gas with ethanol is not good to leave in engines over a long period of time as it can gunk up or even corrode. (ie. don't leave in your lawn mower over the winter without some fuel stabilizer added to it)",
"I think this belongs in Askreddit.",
"Because the energy content of ethanol (that is, how much heat gets released when you burn it) is lower than gasoline. Heat causes things to expand, including the gases burning inside your engine that make it run.\n\nLower energy content means less expansion, which means less energy makes it to your wheels. A 10% ethanol blend has only about 3-4% less energy than regular gasoline, but for some people this is a sticking point.\n\nI can go into a lot more detail if you want the non-ELI5 version. :)"
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
8qd3xi
|
why did the cambrian explosion occur and why do new species of animalia no longer appear as rapidly?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8qd3xi/eli5_why_did_the_cambrian_explosion_occur_and_why/
|
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"text": [
"Answering your second question -\n\nThis is something related to a concept called [Adaptive Radiation] (_URL_0_). This is when a single ancestor species rapidly evolves into a wide variety of species. We've seen this sort of thing happen a few times during earth's history and generally it is related to extinction events.\n\nAn extinction event is whenever a large percentage of the animals and plants living on earth or in the ocean suddenly die off. The most famous is probably the Cretaceus-Paleogene extinction which wiped out, among others, the non-avian dinosaurs. \n\nThe thing is though that after an extinction event? The world is practically empty. A lot of the previously established species are gone which leaves a looooot of open niches. And that sort of environment encourages the process through which species rapidly evolve into wider variety of new species. In time, as the niches become filled up, this process slows down however. It is harder to find a new niche and thereby possibly become a new species, if there is already competitors in that niche. That is also what we have got going on right now. It's been a while since the last big extinction (not counting the one we are kinda causing right now). That means the niches in our ecosystems are pretty filled up, so we don't see this wild explosion of species right now.\n\nWell, that, and seeing as the evolution of new species takes a pretty long time, it's pretty hard to look around right now and see it happen.\n\nI can't really answer your first question, but you might find some answers in [this] (_URL_1_) documentary on PBS Eons (which I recommend checking out in general if you are into this kind of stuff) which talks about the period of time from the Cambrian explosion to the Great Dying. (Permian–Triassic extinction event) ",
"As to why its still being debated but the evolution of hard body parts is the most likely answer. What many scientists envision is that hard parts led to an arms race between predators (killing power) and prey (armour). This arms race created a lot of opportunities for new creatures to emerge if they had decent performance in this arms race.\n\nThe second point I'd like to make is that we don't know for sure that the Cambrian explosion actually was an explosion. There is a very strong preservation bias in the fossil record towards hard body parts so the Cambrian explosion marks the first time in the fossil record we can see a lot of creatures",
"The Cambrian \"Explosion\" took place over at least 20 million years. In terms of Earth's history this may be \"rapid\", but from the perspective of many life-forms that existed at the time and still exist today...even a year can be a couple generations: a parent insect can be born in January have grandchildren or even great-grandchildren by the time December rolls around.\n\nOf course, this also relates to the second question...since humanity has not been around even a million years, so we could be in the middle of another \"Explosion\" and no one would even know for millennia.\n\n----\n\nFor your first question, note that the main difference between \"pre-Explosion\" and \"post-Explosion\" creatures are the prominence of hard mineral-based anatomical and physiological features: bones, shells, exoskeletons, etc. Creatures encased in amber or miraculously fossilized from pre-Explosion times notably tend to lack such mineral-rich things as bones or exoskeletons...but otherwise are remarkably identical to prominent organisms (such as arthropods, fish, etc) during and even after the \"Explosion\".\n\nSo we see very few fossilized organisms as they lack bones which can be fossilized \"reliably\", and then see the same organisms only this time with bones that can easily be fossilized. Not too hard to say that the \"Cambrian Explosion\" occurred in part due to mutations that promoted the development of bones/shells/exoskeletons/whatever else as well as whatever other events people might want to blame.\n",
"I'm no expert on the topic, but from what I've read, there is currently no commonly accepted explanation for the Cambrian Explosion. The fossil record prior to the Cambrian does not account for any body plans that would explain the sudden appearance of the 20+ new phyla that appeared during that time. The PreCambrian strata has proven to be more than capable of preserving soft bodied animals (such as sponges and even embryos), and the animals as developed as the ones found in the Cambrian strata certainly should have had at least some traces of ancestors in the PreCambrian strata. But again, none have been found. That is, none that have been accepted universally. As the fossil record grows, the evidence seems to be consistent-many novel body plans appearing in the Cambrian strata, with no legitimate ancestors being found in the PreCambrian strata."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Adaptive_radiation",
"https://youtu.be/RDQa0okkpf0"
],
[],
[],
[]
] |
||
6gs5nu
|
when did straight white teeth become a status symbol?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6gs5nu/eli5when_did_straight_white_teeth_become_a_status/
|
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"I'm guessing this is a thing in the States?\n\nAs with so many things, it probably started to become a status symbol as soon as famous people started doing it.\n\nThis being said, the super white teeth American TV stars and politicians tend to have is not really a thing here in Europe (is this changing?). So it's not a status symbol everywhere. Even teeth you take very good care of should have a slightly yellow tint to them. It's the natural color of the teeth. By making them completely white you're making them look like something that isn't the color of teeth.",
"Generally, things become a status symbol if rich people can afford them easily and others can't. ",
"I understand the concept of having straighter teeth, for the ease of cleaning and making them last longer. Teeth are also one of the first things that I and, I'm sure, many others notice when conversing. It's probably just a cultural thing though. When it comes to pearl white teeth, they almost look fake in my opinion. It's normal for teeth to have a yellowish tint. \n\nEdit: More than not white teeth are probably a symbol like others have said. ",
"Less a status symbol and more a part of being attractive - like silky hair and smooth jawline... it's about our genetic attraction to symmetrical people. Symmetry = healthy genes, at least as far as we can see at a glance.\n\nIt isn't sudden either, we've always been more attracted to the straight-toothed than the gnarly people. What's sudden (in genetic timelines) is the medical technology to straighten teeth, and also various cosmetic surgeries to make you \"more attractive\" - however you think that's measured.\n\nPersonally, I would never want my wife to look like Melania Trump at that age, uncanniness is not sexy.",
"It's only within the past 20 years or so that it's gotten really popular in the US. You can see popular actors with crooked teeth early in their careers that now have perfect teeth.\n\nIt's a sign that the person has the time and money to take care of their teeth.\n\nKinda like how being pale was considered super attractive (meant you didn't have to work outside) but now being tan is considered more attractive (means you have time to go outside or tan). Same with being overweight back in the day (had the money to actually eat).\n\n ",
"TL;DR: basically forever. \n\n1. Before the modern era, a full set of straight, white teeth was a lot less common than they are today. Being a lot more attractive than rotten/missing teeth, it's not hard to see why this might have been prized.\n\n2. Poor dental health can be indicative of lack of access to adequate nutrition. There are several chronic nutritional disorders, such as scurvy, that can lead to the loosening or outright loss of teeth. Poor sanitary conditions are also bad for dental health. Someone with good teeth presumably didn't lack for food or clean living conditions, suggesting at least moderate affluence in addition to decent genes/luck.\n\n3. Related to both of the above, though today's media culture inundates us with images of \"perfect\" models, no such system existed before the modern era. Standards were a lot lower. Anything that tended to indicate that someone was *basically healthy* was perceived as very attractive. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[]
] |
||
ae48zq
|
what are the advantages and disadvantages of fixed and floating point calculations on computers?
|
Hello
I know what fixed point and floating point values are. But I can simply not understand *at all* what advantages the one has to offer over the other.
Thanks
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/ae48zq/eli5what_are_the_advantages_and_disadvantages_of/
|
{
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"text": [
"Because some decimal numbers can be extremely long, i.e. pi. It's hard to represent that with fixed point arithmetic, and even tho it's impossible with floating-point, it's still better suited for it"
]
}
|
[] |
[] |
[
[]
] |
|
6ne63r
|
when does a hill become a mountain?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6ne63r/eli5_when_does_a_hill_become_a_mountain/
|
{
"a_id": [
"dk8t32a"
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"text": [
"Many geographers state that a mountain is greater than 300 metres (1,000 feet) above sea level. Other definitions, such as the one in the Oxford English Dictionary, put the hill limit at twice that. Still others make distinctions about the degree of slope (including two degrees or five degrees). In Scotland, meanwhile, landforms with distinct summits are called ‘hills’ no matter what their height. But in America, there are several ‘mounts’ that are less than 300 metres (1,000 feet) tall. So, essentially, a hill becomes a mountain when someone names it as such.\n\n\nSource: _URL_0_\n\nEdit: Source"
]
}
|
[] |
[] |
[
[
"https://www.google.com/amp/s/www.howitworksdaily.com/when-does-a-hill-become-a-mountain/amp/"
]
] |
||
3dzdt2
|
crude oil prices are almost half of what they were a year ago. what exactly has changed over this period of time?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3dzdt2/eli5_crude_oil_prices_are_almost_half_of_what/
|
{
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"text": [
"The price of oil can vary wildly based on small differences. If there's 1% more capacity than everyone needs, the price can drop off a cliff. If demand is 1% higher than capacity, the opposite.\n",
"Four things are now affecting the picture. Demand is low because of weak economic activity, increased efficiency, and a growing switch away from oil to other fuels. Second, turmoil in Iraq and Libya—two big oil producers with nearly 4m barrels a day combined—has not affected their output. The market is more sanguine about geopolitical risk. Thirdly, America has become the world’s largest oil producer. Though it does not export crude oil, it now imports much less, creating a lot of spare supply. Finally, the Saudis and their Gulf allies have decided not to sacrifice their own market share to restore the price. They could curb production sharply, but the main benefits would go to countries they detest such as Iran and Russia. Saudi Arabia can tolerate lower oil prices quite easily. It has $900 billion in reserves. Its own oil costs very little (around $5-6 per barrel) to get out of the ground."
]
}
|
[] |
[] |
[
[],
[]
] |
||
1t2qkh
|
why the navier-stokes existence and smoothness problem has not been solved yet.
|
What makes it so difficult to find a solution or a counter-example to the Navier-Stokes equations?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1t2qkh/eli5_why_the_navierstokes_existence_and/
|
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"text": [
"The Navier-Stokes equations are what are known as differential equations. We don't know how to exactly solve the vast majority of differential equations; in fact, we know for a fact that most of them *can't* be solved exactly. What we normally do is approximate.",
"The conservation of momentum equation contains a non-linear term. In this convective term, the power of the fluid velocity is greater than one.\nI'm guessing we know how to solve almost every linear differential equations but only a few of non-linear ones. \nWhat we do for numerical simulations are approximations such as finite elements, finite differences. It basically divides the space in a discrete grid and compute the equations by iteration. \nSome people are trying to simulate directly Navier-Stokes but it seems quite hard, time and power consuming. \n\nHope this helps.",
"The OP should realize that he asked two completely different questions:\n\n* Why is the **existence and smoothness** problem so hard? (asked in the title)\n* Why is it hard to **find a solution**? (asked in the post)\n\nAll answers here so far have focused on the second question and have correctly said that the non-linearity is what makes it hard.\n\nI would like to explain the difference between these two questions with a very simple example. The problem I would like you to solve is: find two people in your state/country who have the exact same number of hairs on their head. I will now explain why the **existence** (no uniqueness) of a solution is very easy to show, but that it's very hard to **find the solution**:\n\n* We know that there must exist a solution because all humans have between 0 and 200'000 hairs on their head (the actual number isn't that important, 200'000 is just my guesstimate) and we suppose that in the state/country we talk about there are a lot more than 200'000 people living. A solution exists because we can imagine all the people being put into one of the 200'001 categories of 'has X hairs on his head' one by one until we have filled up all the categories with at least one person. Person number 200'002 will then have no category of his own and will join another person in his category and there will be now two people with the same number of hairs on their heads. We have shown the **existence** of a solution, which was **easy**. (The principle we have used is also called the pigeonhole principle)\n* Actually **finding two people** with the same number of hairs on their head will be very **difficult** as you can imagine. It would take years to precisely count the number of hairs on thousands of people and this is just not feasible.\n\nSo showing existence is often easy but actually finding the solution is harder.\n\nReturning now to the existence of a solution of the Navier-Stokes equation I can't answer why it's so hard. In a simpler case of an ordinary differential equation it's easy to show existence for non-linear equations (all \"lipschitz-continuous\" functions will do, actually) so non-linearity isn't necessarily part of the answer. I'm not a mathematician so I can't give any further details.\n\nAs a last comment I want to make it clear that you get the 1 million dollars prize money for showing the existence of a solution, not giving a representation of it. You have to do the easier one of the two equations, the existence.",
"UCLA Prof. Terence Tao (Fields medalist) explains the Navier-Stokes (NS) problem of smoothness in his blog (along with possible ways of attacking the problem):\n\n\n_URL_0_\n\n\nWhile nonlinearity is the issue, determining smoothness for many nonlinear partial differential equations (PDEs) is at least achievable. What's so unique about NS?\n\n\nLooking at three-dimensional NS PDE, I see three major characteristics: (1) elliptic PDE, (2) viscous dissipation and (3) nonlinearity.\n\n\nWith the first characteristic, when an equation is elliptic, it basically means that a change in one part of the flow will immediately affect a change in another part of the flow. For example, in subsonic flows on a wing, if you have some flow activity like a flap deflecting at the trailing edge, it will have an immediate effect on the upstream flow, e.g., wing leading edge. This doesn't occur with parabolic / hyperbolic PDEs, which is why we're able to some simplifications for supersonic / hypersonic flows.\n\n\nWith the second characteristic of viscous dissipation, flow structures will dissipate into smaller scale flow structures, e.g., going from coarse to finer scales. Combining this with the nonlinearity in the PDE, the flow can move from coarse scale to fine scale and back for various parts of the flow at various times, e.g., turbulence. There is energy at each of these scales (coarse / fine), and mathematicians are having a hard time confining the energy of these scales or even the evolution of the energy of these scales as the flow evolves in time.\n\n\nCombining the above issue of nonlinearity / viscous dissipation with the elliptic property means that the complexity in part of the flow is connected to the complexity in another completely different part of the flow. You can see how the complexity easily cascades.\n\n\nSo, right now, even if you program a computational model of Navier Stokes equations, we won't even know if the simulation is numerically correct for the general problem.\n\n\nTL;DR. Turbulence + elliptic PDE = difficult to solve problem."
]
}
|
[] |
[] |
[
[],
[],
[],
[
"http://terrytao.wordpress.com/2007/03/18/why-global-regularity-for-navier-stokes-is-hard/"
]
] |
|
a0tvtn
|
how is it that tiny countries like monaco, luxembourg, and singapore have managed to remain independent and also maintain such high levels of wealth and standards of living?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/a0tvtn/eli5_how_is_it_that_tiny_countries_like_monaco/
|
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"It can sometimes be for differnet reasons. Luxembourg and Monaco are both tax havens. They have very low taxes, so corporations often move there. Also, in Luxembourg, about 60% of people who work there, don't actually live there. So they are adding to the GDP, by their productivity, and spending money at surrounding businesses, but the government is not spending much money on those people. Their home country is. And when a corporation sets up shop someplace for a tax haven, those jobs are often higher paying job.\n\nMonaco is also just a beautiful place, so it has nice resorts, etc. Its a great vacation spot, which brings in money. Its also a tax haven as well, which attracts millionaires. (In 2016) 8 formula one drivers live in Monaco. They all make a lot of money, and have to spend it somewhere, which is good for the economy. Obviously 8 individuals won't affect a countries GDP, but there are thousands of (non famous) millionaires who also go to Monaco for its tax haven status. ",
"A lot of times countries prefer having \"buffer states\" along their boarder between major empires. These states are easier to handle and will give some preparation time in case of an invasion. For example in the last 200 years whenever Belgium have been invaded it have given France, Germany or Great Britain a reason to get involved in the war. Most tiny countries are on the boarder. In the case of Monaco they were on the boarder between France, Savoy and Aragon. And this is also part of the reason why smaller nations tend to be richer. They do not have as much of a need to defend themselves. Both due to having neighbors who wants them to exist and because any army they could come up with would not be able to stand their own for long against their neighbors. And I do not mean to disrespect the efforts of the Belgian army in WWI or the Polish army in WWII but they did not have the manpower to win the war on their own. So a lot of the smaller countries have a much smaller army then their population would suggest. This reduces the tax expenses making it easier to grow their wealth. Another factor here is that there is naturally a higher variance in the wealth of smaller nations then larger ones. So you would expect to see more wealthy small nations but also more poor small nations.",
"TLDR: For different reasons having to do with geographic location and what kind of wars happened around them.\n\nUnexpectedly long-winded answer follows:\n---\nWell, they only stand out as tiny countries among huge neighbors today, but in historical terms, those huge neighbors were not always there.\n\nFor example, Singapore has only been independent for a little over half a century. After WWII, the areas around it was kind of assembled together into the federal state of Malaysia, as a counterweight to Indonesia, which was thought to be too strong a regional power, and a potential threat. Singapore originally wanted to be part of Malaysia, but because it was mainly populated by the Chinese (who were already very heavily represented in other important trade hubs like Penang and Malacca), the Malaysian nationalists thought its wealth would give the local Chinese far too much power in the Malaysian parliament and federal government. So they basically kicked Singapore out. Note, however, that Singapore is really paranoid about its independence and doesn't take it for granted; they make a disproportionate effort to have a functional Armed Forces on such a tiny and crowded piece of land.\n\nWith Luxembourg, it's a different kind of location advantage. Remember that Germany as a single country is also a 19th century thing! Before united Germany, and even before Prussia, it was a bunch of tiny independent countries. While Singapore got a huge boost from being a very convenient harbor on a very busy shipping route, Luxembourg is placed right in the area where a bunch of European powers - mostly France and bits of Germany, but also Spain (which used to own Belgium) and Holland - have been fighting each other for centuries, pushing the borders back and forth. There are actually loads of territories in that part of the world that were independent or quasi-independent in recent memory. The were Neutral Moresnet, sort of independent but ruled by a representative each from Belgium and Prussia, which was briefly the world capital of Esperanto enthusiasts. There is Saarland, which was forced into independence from Germany after each World War and rejoined by referendum each time - when I was there, my local friend showed me the football stadium where, quote, \"our team played against the Germans for the European Cup qualifiers\". :) So Luxembourg is kind of just the last little independent principality out of many that were there.\n\nWith Monaco, again I think it's a consequence of the relatively recent unification of Italy. Before that, various European royal families owned little bits of land, and would give individual principalities to their children to rule, etc. It didn't matter that Monaco wasn't part of France because it was owned by a minor relative of the king of France anyway. Same with San Marino, etc.\n\nToday, Monaco survives because of its low taxes (very wealthy people officially live there and spend money there). \n\nSingapore survives because it's a really, really convenient shipping and trade hub - and because it had a leader called Lee Kwan Yew who was very authoritarian, but very development-focused. He made it possible for Singaporeans to make a lot of money in trade, and supported education and development for citizens (they have some of the best universities, tech companies, etc.). And the rule of law is very strong, so businessmen and corrupt officials from surrounding countries like that they can park their money in Singapore safely. ;)\n\nLuxembourg survives partially also because of tax dodginess - a lot of online service companies like Skype or Amazon used to have their European subsidiaries registered there, because the value-added tax in Luxembourg was so much lower than in the rest of the EU. (That got closed down a few years ago with an EU law that says you pay VAT according to the buyer's location, not the seller's.) But very importantly, Luxembourg has a very strong mining and steelworks industry, some of the best steel in the world comes from there, so it always had real industry to fall back on when the financial markets were in a crisis.",
"Singaporean here, I can share abit on how we got wealthy.\n\nAfter WW2, Singapore was a third world nation. We had no resources, no allies and no population. It was very likely that we would be a failed state. We were kicked out of the Malaysian federation and forced into independence, which basically spelled doom for a country so weak. Unemployment was 12% and the GDP per capita was 500USD (in today’s terms).\n\nBut our early leaders were exceptional. They threw everything we had into education, attracted companies with low taxes, and heavily expanded our ports to service all ships in the region. We also went all-in with the petrochemical industry, becoming the third largest refiner of petroleum in the world.\n\nAfter we started to gain wealth, the government built lots of infrastructure. They formed the HDB to build public housing (which now accommodates 80% of our population). Public transport was improved significantly, and we set up the cpf scheme to enforce savings.\n\nFrom the point of our independence, we have had only one ruling party. To the rest of the world, it looks like a dictatorship, but we do have opposition parties, they are just not popular. There is no rigged ballots or stuff like that, people really vote that way.\n\nThis gives us the ability to plan long-term, instead of focusing on how to win the next election (although nowadays they seem to be doing that more). Laws are consistent, and companies like the stable political, economic and social climate.\n\nThe government has also built up a massive Budget surplus year after year, which is invested worldwide to bring in more profits. During the 2009 financial crisis, a portion of this fund was used to offset the economic depression and we zoomed back up with a 15% gdp growth.\n\nNowadays, the majority of our economy is based on the financial sector, construction, trade, petrochemicals & medical research. The tax rates are still low, and the people well educated, which attracts businesses to set up shop here."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
7w7u9d
|
what is happening when your hands feel wet in water despite being dry inside of watertight gloves and even after the gloves are removed?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7w7u9d/eli5_what_is_happening_when_your_hands_feel_wet/
|
{
"a_id": [
"dty6z3a"
],
"score": [
8
],
"text": [
"It's the combination of the smoothness of the gloves, and the temperature drop of going into the water (or rise) triggering the appropriate flags in your brain that make it go \"wet\". Simple as that really. \n\n'Wet' as a feeling is just the right comination of texture pressure and temperature, and enough of that sensation can pass through the gloves to fool your brain. "
]
}
|
[] |
[] |
[
[]
] |
||
fr753l
|
why our bodies get more creaky and poppy with age
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/fr753l/eli5_why_our_bodies_get_more_creaky_and_poppy/
|
{
"a_id": [
"flu3opf"
],
"score": [
7
],
"text": [
"The older we get the less good our bodies become at generating new tissue and repair. This leads to tighter muscles and thinner skin. It also can lead to muscle atrophy if you weren’t active in your middle age."
]
}
|
[] |
[] |
[
[]
] |
||
18h3e1
|
/r/fifthworldpics
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/18h3e1/eli5_rfifthworldpics/
|
{
"a_id": [
"c8era22"
],
"score": [
2
],
"text": [
"It's all satire"
]
}
|
[] |
[] |
[
[]
] |
||
1zztfu
|
how do gift cards get activated at a register?
|
Gift cards that you buy at a convenience store get activated at a register, but its just a code at the back to type into a computer, how does the computer know it is activated?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1zztfu/eli5_how_do_gift_cards_get_activated_at_a_register/
|
{
"a_id": [
"cfyglld"
],
"score": [
3
],
"text": [
"Whenever you swipe a card with a magnetic stripe on a computer system that is designed to deal with such cards, the card is identifying itself to that system. In a way, it's like typing in a unique User Name on a computer that hopefully is so complex that it cannot be duplicated.\n\nWhen the cashier swipes the gift card (or types in the number) when you purchase it, the gift card tells the system, \"Hi, I am gift card number 388309809827348760827634\" and I would like to be activated.\n\nThe system then says, \"OK, that's a valid number for a $100 gift card. Your wish is granted. the card is activated and can now be used for $100 credit at this store (or chain of stores).\""
]
}
|
[] |
[] |
[
[]
] |
|
32v14m
|
is there an intrinsic need for physical money?
|
Is there any reason to have physical money. Are we destined to have a completely virtual monetary society?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/32v14m/eli5is_there_an_intrinsic_need_for_physical_money/
|
{
"a_id": [
"cqevs4m"
],
"score": [
3
],
"text": [
"There isn't a need. But since transaction fee is zero for physical currency, its cheaper than intangible currency."
]
}
|
[] |
[] |
[
[]
] |
|
3ejdx7
|
the turks are bombing the kurds. the kurds are fighting against is. is is attacking turkey. wtf is going on?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3ejdx7/eli5_the_turks_are_bombing_the_kurds_the_kurds/
|
{
"a_id": [
"ctfi6po"
],
"score": [
10
],
"text": [
"In Geopolitics, there is a concept called a 'natural country', an area bounded by geography that is defensible and relatively isolated.\n\nTurkey is 'naturally' bounded by mountainous hills in the south of their nation. These hills are also the natural barrier of a flat riverland inhabited by the Kurds that runs through northern Syria and into Iraq. These Kurdish lowlands are naturally bounded by dry highlands, mountains, and deserts in southern and coastal Syria. The desert and coast people are the Syrian government, and they are powerful politically because oceans are amazing and bring a lot of trade and opportunity. \n\nTurkey doesn't want to lose it's super-important defensive mountains to the Kurds because it would weaken them as a state - they require those mountains to maintain their natural territory. The people who live in those mountains are Kurds, however, and identify with the valley people. ISIS is not occupying a natural country, but is spread out between those two natural countries. They hope to take Coastal Syria and use it to occupy Kurdish Syria. If they do, their next step would be to reclaim the territory that Turkey controls in the mountains.\n\nSo, from the Kurds' perspective they need to liberate their country from Syria and Turkey, from the Syrian Government's perspective it's losing control of territories inland while fighting a rebellion, from ISIS perspective they need to keep spreading until they occupy a natural country and from Turkey's perspective all of these groups are a threat and need to be contained, since they all want Turkey's strategic mountain."
]
}
|
[] |
[] |
[
[]
] |
||
2okqcb
|
why do companies think they can increase human lifespan to like 150 or 300 years?
|
Groups like Google's calicolabs _URL_1_ Craig Ventor's new co human logvevity _URL_2_ genopharmix _URL_3_ and GE healthcare/software _URL_0_ etc.
Edit: There's also the Buck instutute and the SENS foundation.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2okqcb/eli5why_do_companies_think_they_can_increase/
|
{
"a_id": [
"cmo1b05",
"cmo1k5s"
],
"score": [
3,
2
],
"text": [
"People don't just die, they die because of something. If nothing causes you to die, you would just keep living.",
"We have examples of life on earth that can live to 100's of years, or can live forever. Think about sea turtles or trees. Fundamentally, there isn't anything about Humans that would make extremely long lives impossible, so it must be possible."
]
}
|
[] |
[
"http://www.gesoftware.com",
"http://www.calicolabs.com",
"http://www.humanlongevity.com",
"http://www.genopharmix.com"
] |
[
[],
[]
] |
|
3qy4xg
|
is it possible to live in a world without money ? why/why not ?
|
I'm asking this question in context with the modern world. Would it be possible to implement a cashless society across the world ? If so, how would it look like, and what would be done to put it in place (or) if not, why ?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3qy4xg/eli5_is_it_possible_to_live_in_a_world_without/
|
{
"a_id": [
"cwjbba2"
],
"score": [
3
],
"text": [
"One wonderful thing that money does for us is that it lets us tell other people what we want and what we can do. Imagine a society with no money but everyone was exceptionally nice to each other and would make things for each other if they wanted them. How would anyone know what to make? How would anyone know whether the raw materials they need to make things are available or whether they are scarce and better left for other uses.\n\nMoney (and importantly prices) transmit information about how scarce things are, about how hard it is to make things and about how much people want them. And a system with money has the added bonus that it doesn't rely on people all being nice to each other: money allows us to have much of what we all want without relying on the kindess of strangers.\n\nIt's far from a perfect system and there are lots of ways we can make it better. But without money, it would be very difficult for us to co-ordinate to make the wonderfully complex things we all love.\n\nMilton Friedman isn't always right, but this is a wonderful, 2 minute video that's on point.\n_URL_0_"
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=R5Gppi-O3a8"
]
] |
|
43xt9y
|
how do banks and other large entities send out mass mail? who stuffs and ships?
|
I work in the back offices of my families business. This entails payroll, W2s, etc. since I'm 19 I get stuck with stuffing it all, and it sucks. How do banks like Chase, Barclays, or other huge firms send out literally millions of parcels a year?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/43xt9y/eli5_how_do_banks_and_other_large_entities_send/
|
{
"a_id": [
"czltovp",
"czltrad"
],
"score": [
5,
2
],
"text": [
"There are companies that have machines that do it. When I was in college I worked in a factory that did a lot of the mailings for many large companies. ",
"It's all automated in centralised print centres.\n\nThe documents are printed, then pass into machinery that automatically folds it and stuffs it into envelopes (appropriately printed with addresses and postage).\n\nI develop insurance software and part of it has to integrate into document services which directs electronic format documents to these centres.\n\nI believe you can get smaller versions of these machines for home office and small businesses though?"
]
}
|
[] |
[] |
[
[],
[]
] |
|
abou36
|
why do people like scary movies or thrill rides?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/abou36/eli5_why_do_people_like_scary_movies_or_thrill/
|
{
"a_id": [
"ed1xsxl"
],
"score": [
6
],
"text": [
"The most likely answer is that being frightened releases adrenaline, and that sh!t is addictive AF. "
]
}
|
[] |
[] |
[
[]
] |
||
1rtkn3
|
who/what is jd power and associates, and why do they give out awards to so many different products?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1rtkn3/eli5_whowhat_is_jd_power_and_associates_and_why/
|
{
"a_id": [
"cdqqlzf",
"cdqrkta",
"cdqt1b7",
"cdqtxwp"
],
"score": [
9,
5,
2,
2
],
"text": [
"I asked my brother who works there the same question, he says they manage other people/ businesses money. He once answered it legitly, I understood none of it. ",
"They are perhaps most famous for giving cars a reliability rating. They do surveys on owners of the car about mechanical problems. They also do this for consumer goods. They make money selling their data and licensing their name for advertisement. If you give an award to a car then the company is going to want to use that promotionally. ",
"If you have to ask, that means the marketing hasn't gotten to you yet. There's still hope.",
"If I could add another question. How to you make a business out of giving awards?"
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
1pvu03
|
macro nutrients
|
Hey everyone I'm trying to be a healthier individual and so far im on the right track. As Im exploring health forums and plans I keep seeing references to macro nutrients. Can someone please explain what they are and how to figure out how many I need each day?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1pvu03/macro_nutrients/
|
{
"a_id": [
"cd6m626",
"cd6t2k7"
],
"score": [
2,
2
],
"text": [
"_URL_0_\n\nHere are a bunch of tables with recommended daily intake for various nutrients. Macro nutrient is a term for nutrients that are required in large quantities as opposed to micro-nutrients. \n\nAs long as you eat a balanced and varied diet you should get most of your required nutrients. Almost any food in the US will be labelled with what percentage of your daily needs it will fill. And fruits and veggies are easily googleable. Hope this helps. ",
"Basically,\n\nMacronutrients - Protein/Carbohydrates/Fat (Basically the nutrients that provide calories)\n\nMicronutrients - Vitamins & Minerals \n\nHow many calories your body requires depends on your body composition. You will have to the math yourself by sex/weight/etc. \n\nGenerally, I think it was recommended that most people get around 50%Carbs/30%Fat/20%Protein unless you are on a specialized diet. This means if you were to have a 2000 Calorie diet, you would try to get 1000 calories in carbohydrates, 600 Calories from Fat and 400 Calories from Protein. In general, Protein & Carbs are 4 Calories per gram while Fat is ~9 Calories per gram.\n"
]
}
|
[] |
[] |
[
[
"http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-tables"
],
[]
] |
|
4ivn7x
|
why is not okay to talk to someone on your phone whilst driving but it is okay to talk using hands free systems? surely the distracting part is talking to someone, not holding the phone.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4ivn7x/eli5_why_is_not_okay_to_talk_to_someone_on_your/
|
{
"a_id": [
"d31hlrs"
],
"score": [
2
],
"text": [
"1. if you don't want people to text, you need to be able to differentiate between breaking the law and not breaking the law. Some of this overflow from anti-texting laws which are clearly in everyone's best interest. (he says despite texting and driving on occasion like the fucktard dickhead he is)\n\n2. We are good at mentally focusing on things that are hands are doing. If your hands are driving, so is your brain (broadly speaking). If your hands are doing something else, so is your brain. This is _not as true_ of our mouths/vocalizing. We are constantly doing things while talking! "
]
}
|
[] |
[] |
[
[]
] |
||
7byqw5
|
what determines if 2 chemicals will or won't bond
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7byqw5/eli5_what_determines_if_2_chemicals_will_or_wont/
|
{
"a_id": [
"dplvyti"
],
"score": [
3
],
"text": [
"Square blocks go in square holes. If the orbitals of one molecule are the same 'shape' and 'size' as another molecule they can fit together. \n\nAside from looking at bond overlap you can also understand a lot of chemical reactions from simple E+M. Opposite charges attract. If a molecule has a part of its body that is a little bit positively charged (maybe there is a carbon next to an oxygen that is slorping up its electrons) than any negatively charged part on another molecule is going to want to stick to it. In the case of something super negative like say the carbon next to a lithium in alkyl lithiums, it will stick and won't come off.\n\nAt a high level though it's all about going downhill. Whatever increases the entropy of the universe will happen. Period. "
]
}
|
[] |
[] |
[
[]
] |
||
3tox9e
|
dimension theories
|
How many are there, and what are they?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3tox9e/eli5_dimension_theories/
|
{
"a_id": [
"cx7ys5v",
"cx80kpw"
],
"score": [
2,
3
],
"text": [
"According to M-theory, there are 11 dimensions. Dimensions are mathematical properties of the universe, they basically allow for subatomic particles to have the qualities they do (charge, spin, etc). String theory stated that each subatomic particle consisted of strings vibrating in different planes or dimensions, and string theorists believed there to be 10 dimensions, this was mostly disregarded by physicists as there were multiple versions of the theory and were not very coherent. \nThere was another theory called supergravity that says that gravity is just as strong as magnetism; if you imagine the entire earth pulling on a fridge magnet can easily be overcome by another tiny magnet. The theory suggested that the gravity seeps into other universes through another, 11th dimension.\nString theorists and other physicists didn't like like this, but when you combine the maths of both of them together, giving 11 dimensions to all the different string theories, they all combine to the same thing, suddenly a huge theory of the universe was mathematically described by one theory, now called [M-theory](_URL_1_) (M for membrane).\n\nEdit: [In the absence of an understanding of the true meaning and structure of M-theory, Witten has suggested that the M should stand for \"magic\", \"mystery\", or \"membrane\" according to taste, and the true meaning of the title should be decided when a more fundamental formulation of the theory is known.](_URL_0_)",
"So this all springs out of attempts to make a quantum theory of gravity, and in turn unifying such a theory with the theories of the other forces. In turns out that the usual process of quantification just doesn't work, and one solution is to do some fancy mathematical trickery that just happens to require some extra spatial dimensions. The specific reasons for this are too technical to really go into here. Now, as far as we can tell there are only three spatial dimensions, so the extra dimensions have to be \"hidden away\" somehow, usually by compactifying them into tiny regions in space-time.\n\nThe number of extra dimensions and the way they are implemented are numerous, a notable example being string theory in all its forms. They all share the common goal of unifying the fources. Although such theories have been the main focus of theoretical physics for the last 30 years or so, it seems like the hope is lost for most such theories. The problems involved in \"hiding\" away the extra dimensions along with the apparent lack of a unique theory that comes along with it just seem to be too large at the moment, but who knows? "
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/M-theory#cite_ref-Duff_1996.2C_sec._1_1-0",
"https://en.wikipedia.org/wiki/M-theory"
],
[]
] |
|
4i69sz
|
electrochemical gradient
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4i69sz/eli5_electrochemical_gradient/
|
{
"a_id": [
"d2vvy5f"
],
"score": [
2
],
"text": [
"One of the best examples of an electrochemical gradient is in our neurons \n\nWe have a lot of sodium outside our cells and little inside cells\n\nHowever, we have potassium inside the cell which is + charged just like sodium.\n\nIf a gate opens, sodium is going to rush into the cell and equilibrate because there is less of it inside. However as sodium goes down its CHEMICAL gradient the inside of the cell becomes more and more positive as more sodium enters and adds to the already + potassium.\n\nPositive charges repel one another so there is going to be a point at which sodium is not going to enter the cell anymore even though there is more sodium outside than inside. This is due to the ELECTRICAL gradient equalizing and opposing the chemical gradient. \n\nThis is the basics of it, in reality our cell has many different ions and ions have different pathways in and out of cells. However I hope this shows what electrochemical gradient can mean in biology.\n\n"
]
}
|
[] |
[] |
[
[]
] |
||
15a4yx
|
can anyone explain crystalline resonance?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/15a4yx/can_anyone_explain_crystalline_resonance/
|
{
"a_id": [
"c7l1bup"
],
"score": [
3
],
"text": [
"Atoms in a solid are \"connected\" to each other by the electromagnetic force. This acts like a little spring. Because of these, the atoms can jiggle back and forth more easily at certain frequencies than others, similar to how a pendulum with a certain weight and length wants to swing at a particular rate. \n \nIn a lot of solids, there's a huge variety of those connections, so there's a huge variety of those jiggle frequencies. But in crystals, there are only a few different ways that atoms are connected, so there are only a few frequencies at which they can easily jiggle. So whole bunches of them can jiggle at the same frequency. Once a few do, they will tend to make the others near them jiggle along with them at the same frequency and in the same \"phase\" (because they make the whole crystal shake). This means that they aren't just jiggling at the same rate, but their motions are also in the same directions at the same time. "
]
}
|
[] |
[] |
[
[]
] |
||
63avtd
|
why do the letters in english have an 'eee' sound when saying their names? b,c,d,g etc..
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/63avtd/eli5_why_do_the_letters_in_english_have_an_eee/
|
{
"a_id": [
"dfsmy6h"
],
"score": [
3
],
"text": [
"The names of English letters are mostly derivative of their French, Latin, and Etruscan ancestors - see _URL_0_ for a quick reference to that. (Not terribly fond of Wikipedia as a source, but this ain't university, it's just Reddit, so it'll do.)"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/English_alphabet#Etymology"
]
] |
||
29b60g
|
how does the 'westboro baptist church' keep convincing their followers? what do they say every sunday?
|
I'm Christian. I can't begin to think what these people say every Sunday and / or Wednesday, or whatever day they "worship".
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/29b60g/eli5_how_does_the_westboro_baptist_church_keep/
|
{
"a_id": [
"cij7aex",
"cij7rhq",
"cije78o"
],
"score": [
9,
6,
2
],
"text": [
"They don't really get new followers. It's a family, not really a church.",
"Most are all one family, who have been taught the ideals of the WBC since they were born. When ideas are implanted in your head from that young an age, it's the only thing you'll believe without much persuasion.\n\nBasically, they've believed in the WBC since they were children so they don't know much better.",
"Mark 11:12-14.\n\n_URL_0_\n\nI stole that from a post by one of Fred Phelps grandchildren, or something"
]
}
|
[] |
[] |
[
[],
[],
[
"http://2.bp.blogspot.com/-scO6xUFdJ8A/T3YjDh4W5II/AAAAAAAAAOE/sUU5EmexUdk/s1600/god-hates-figs.jpg"
]
] |
|
36feb2
|
do atoms have a lifespan or exchange subatomic particles within their lifespan to become a different atom?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/36feb2/eli5do_atoms_have_a_lifespan_or_exchange/
|
{
"a_id": [
"crdhrsa"
],
"score": [
2
],
"text": [
"Yes, but it varies. Theoretically, all atoms undergo radioactive decay on some sort of timescale, but that could be in the billions of years or even longer for the more stable isotopes. There's even the possibility that protons decay into smaller subatomic particles, but we have even less evidence for that.\n\nAnd there's always nuclear fusion if we're considering making a heavier atom from lighter ones."
]
}
|
[] |
[] |
[
[]
] |
||
2qu7sy
|
when i'm sick, why does masturbating temporally decongest my sinuses?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2qu7sy/eli5_when_im_sick_why_does_masturbating/
|
{
"a_id": [
"cn9m2d2",
"cn9mi42",
"cn9o4jp",
"cn9oj37",
"cn9oun9",
"cn9pr4k",
"cn9rp20"
],
"score": [
4,
2,
210,
3,
2,
19,
3
],
"text": [
"One of the hormones that's involved in congestion - histamine - is also involved in the sex response.",
"Same goes for stomach ache and many more ailments. Why?",
"**It's actually not a blood flow thing as the other guy said.** It has to do with Norepinephrine being released when you orgasm. Obviously just having a boner doesn't decongest your sinuses, but orgasming does. When you orgasm lots of neurotransmitters are released into your brain, one of them is norepinephrine. Norepinephrine constricts the blood vessels, which prevents fluid from blood vessels going into your mucous membranes, which leads to less mucous production and decongestion.\n\nEdit: **Norepinephrine is exactly the same thing that is released in the most powerful decongestants like Sudafed (pseudoephedrine), that is why they have the same effect**",
"When I am sick I don't feel much like masturbating. Maybe I am doing 'sick' wrong?",
"does anyone else find themselves just like cupping their junk more when their sick? ive been sick with headache/fever/coughs for the past week and noticed i was doing it more, :l",
"Does this work for girls? Because I'm severely congested at work and can't wait to go home and try",
"Because we are made to reproduce, and sexual redproduction takes priority. So the body makes you feel better so you can accomplish it, then when you stop it lets you feel shitty again.\n\nI know its not technical, but idk what chemicals are actually involved."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[]
] |
||
5ez23d
|
why do we have bad dreams? why are our dreams not just purely happy ones?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5ez23d/eli5_why_do_we_have_bad_dreams_why_are_our_dreams/
|
{
"a_id": [
"dag7vql",
"dagc4z6"
],
"score": [
3,
2
],
"text": [
"Why would you only have good dreams? You have good and bad experiences, good and bad thoughts, and good and bad feelings, so it makes sense that you would have good and bad dreams too.",
"Ok, I'm not an expert, by far, but I did do a fair bit of reading across my little life about things like these and grew up with psychology books in the house. Basically our brains and memory as well function in 3 parts. Conscious, subconscious and unconscious. \n\nConsciousness is what we are always aware of, what you're doing most of the time, decisions, etc. Memories are stored in the subconscious and unconscious. Subconscious memories are things you know but don't need. For example you're having a conversation with an old friend and he remembers some funny story with you 2. Your brain then searches for that memory and finds it in the subconscious.\n\nPart of our dreams are from that region, subconscious thoughts that become more active during sleep as the consciousness disappears in that period of time. \n\nThe other part comes from the unconscious. There we can find all sorts of things our ID and Superego is mostly stored there. People with ticks (biting nails, twitching, things we do without being aware of until told about it at least). The unconscious also becomes more active during sleep and there you may have fears, worries, long time trauma and stress that could manifest during sleep and dreams.\n\nSo as far as my uneducated mind can explain, it goes like that. Also dreams can be also influenced a lot by where/how we sleep, for how long, did you eat less than certain hours before bed? There are a multitude of factors that influence our good/bad dreams as well as what we consider to be good or bad. For example I once had a dream about flying on a dragon, I personally loved it whereas people afraid of heights might see it as a bad experience.\n\nP.S: for anyone with more knowledge than me in these things, I would appreciate to correct me in any of the things I mentioned but at the same time let me know what I got right. I never did extensive research and authors, books and other information is stored in my unconscious mind as I never gave them that much of importance to keep them handy.\n\nP.P.S: Our brains actually record EVERYTHING that we experience, from sounds, sensations, images, tastes. Nothing is lost ever really lost, just the connections to those memories but we do not need all of them and the brains sorts them into \"keep handy\", \"might be important, let's leave it somewhere i can easily find\" and \"yeah, put it with the others in that place hard to reach and sort\". So during deep sleep some of these things could come up randomly and you may experience them as such."
]
}
|
[] |
[] |
[
[],
[]
] |
||
lbfvd
|
kosher meats
|
Can someone explain the difference between kosher meat and regular meat? Someone told me that it's just softer, but I don't understand.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/lbfvd/eli5_kosher_meats/
|
{
"a_id": [
"c2rbnaq",
"c2rcf38",
"c2rbnaq",
"c2rcf38"
],
"score": [
2,
3,
2,
3
],
"text": [
"With regards to what makes meat \"kosher\" or not largely depends on how it was processed. Of course, certain meats (such as pork) are not kosher, while some (beef) can be. Animals must be killed in a certain way that is meant to minimize the pain the animal experiences. Kosher meat cannot come from animals that were diseased, nor can it come from animals that die of natural causes.\n\nWhether the meat is softer, richer, saltier, is more a factor of the specific steps made to make that.",
"Kosher meat is meat from specific animals (split hooves and chew their cud - which basically means grazing animals). The process is soaking the meat with water, salting the meat and then rinsing the salt off. All of this must be witnessed by a Rabbi. The problem is that the salt draws out all the moisture from the meat make it much less tender. However, thousands of years ago when these rules were invented, it would probably have led to less disease.",
"With regards to what makes meat \"kosher\" or not largely depends on how it was processed. Of course, certain meats (such as pork) are not kosher, while some (beef) can be. Animals must be killed in a certain way that is meant to minimize the pain the animal experiences. Kosher meat cannot come from animals that were diseased, nor can it come from animals that die of natural causes.\n\nWhether the meat is softer, richer, saltier, is more a factor of the specific steps made to make that.",
"Kosher meat is meat from specific animals (split hooves and chew their cud - which basically means grazing animals). The process is soaking the meat with water, salting the meat and then rinsing the salt off. All of this must be witnessed by a Rabbi. The problem is that the salt draws out all the moisture from the meat make it much less tender. However, thousands of years ago when these rules were invented, it would probably have led to less disease."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
278wlp
|
- why do airport runway numbers change?
|
I've noticed at my local airport, the runway numbers had changed a couple years ago - for example, what is considered to be a North/South runway had been numbered as runway 14/32 was changed to 15/33. I know the numbers correspond to the runways' general orientation to compass degrees(?). So, what changes?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/278wlp/eli5_why_do_airport_runway_numbers_change/
|
{
"a_id": [
"chyhm39"
],
"score": [
7
],
"text": [
"The numbering is according to magnetic north, and earth's magnetic field is changing ever so slowly. After many years, it has moved enough that it's now closer to 15 (150 degrees magnetic) than 14 (140 degrees magnetic)."
]
}
|
[] |
[] |
[
[]
] |
|
34tp58
|
why do we have to use raw eggs when we bake?
|
What would happen if I crushed up a boiled egg into the bake mix instead of cracking a raw egg?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/34tp58/eli5_why_do_we_have_to_use_raw_eggs_when_we_bake/
|
{
"a_id": [
"cqxy4vq",
"cqxy9a0"
],
"score": [
5,
2
],
"text": [
"You would get a cake full of bits of boiled egg. By mixing the liquid raw egg into the batter itself, it causes it to cook differently than if it's on its own. So it doesn't just bake into scrambled eggs within the cake.",
"One function of eggs in the dough is to keep the thing together as it's pretty sticky and that would certainly not work with a boiled egg. Sometimes you can also use oil instead of eggs but it doesn't work quite as well. It's easier to get that mushy and yet firm texture and full moist taste with eggs than oil or other substitutes. \n\nThen again I'm a rookie cook and don't know anything."
]
}
|
[] |
[] |
[
[],
[]
] |
|
11cd0n
|
how police are allowed to arrest individuals in sting operations on "to catch a predator" though they haven't actually committed the act of pedophilia.
|
It seems like a lot of the time on this show a man will chat up a young girl or boy online (who is actually an adult posing as a young teen) and agree to meet for sex, which admittedly is very bad behavior. But how is it possible, legally, to arrest these men? In some sense, all they're really guilty of is the possibility (or promise) of pedophilia - without having ever committed the act. How is this legal?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/11cd0n/eli5_how_police_are_allowed_to_arrest_individuals/
|
{
"a_id": [
"c6l7hhl",
"c6l7l0h",
"c6l8wf6"
],
"score": [
11,
9,
3
],
"text": [
"It's intent. You can be arrested for possession of cocaine with \"intent\" to distribute, for example. The same goes for pedophilia.\n\nEdit: Take one of those \"cases\" on To Catch A Predator. All of the chat room logs can be used as evidence. They are normally very explicit and detailed about what the suspect is planning to do. Showing up can also be used against him/her, and the suspect can also be charged for whatever illegal substances, etc. that he/she brings to the sting. The poster underneath me, Jefffffff, is right that \"Pedophilia\" is not actually a crime. I was just using that as a blanket term.",
"There is no crime of \"paedophilia\". Paedophilia is not legally defined. The *crimes* involved are, for example, possession of child pornography, sexual intererence, & c.\n\nOne such crime is making plans to have sex with a minor. Yeah, just making plans to have sex with a minor is a criminal offence, in many places.",
"Quick check to see what forum I am in. \n\nGood, the law doesn't want to have to wait until you have harmed somebody in order to prosecute you. Take child rape. Just because you haven't actually raped a child doesn't free you from criminal charges. In fact, you probably won't get to have sex with a child unless you commit lesser offenses. You have to contact the child (which is legal) and then have an interaction with the child in which you suggest sex in some way. That is called solicitation. Solicitation is when you encourage someone else to commit a crime or you offer to commit a crime. \n\nWhen you approach a child and offer to conduct sexual acts, you are using lewd language according to most state laws. You cannot tell a child you want to ____ her in the ___. Children are not supposed to hear that type of language. \n\n Many of the men will send pornographic pictures of themselves. This is also a crime. Children should not have to see a man masturbating. This could also be considered lewd contact with a child. \n\nFinally, when you tell a child you are going to go over his or her house and have sex, even if you don't have sex, the law looks at it as attempted sexual battery of a child. Battery is no more than an unlawful touch. If you plan to do it, and you bring items showing you had that intention, you can be convicted of sexual battery. \n\nClaiming that you thought the victim was of age is not a defense because the law does not allow the sexual solicitation of children because children cannot give consent. So even if a 10 year old girl says she would do anything to you and is home alone, you are still breaking the law by arriving at her house. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
b5qi6w
|
since the earth has a magnetic field, would it be possible to create a flying machine by repelling against it?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b5qi6w/eli5_since_the_earth_has_a_magnetic_field_would/
|
{
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"ejf5jv3",
"ejf5oh2",
"ejf8clc",
"ejfmdcq"
],
"score": [
21,
5,
18,
2
],
"text": [
"No.\n\nThe field is not strong enough to lift an object with air inside. Of course, you could make a balloon with a magnetic motor to steer it. This would only work inside a special building, the wind would always overpower it.\n\nThe Earth's magnetic field is barely enough to turn a compass needle in a special, super-low-friction configuration.",
"Unfortunately, no. The Earth's magnetic field is not very dense, so it would take a very high powered magnet to repel against it meaning you couldn't have any electronics and so a helicopter is a better idea. Magnetic flux and the flowing nature of the field make it even more complicated in that your device would need to read the field and react immediately.\n\nIt'd be much easier to build roads out of permanent magnets.",
"As others have stated, it's not nearly strong enough for such a vehicle.\n\n*However*, many satellites use something called a \"magnetorquer,\" which is a device that uses the Earth's magnetic field to control and/or stabilize orientation. It's not very strong at all, but there's no air friction to overpower it in space.",
"No.\n\nSetting aside that it's not nearly strong enough, as others have explained, the Earth's magnetic field isn't oriented properly to provide for magnetic levitation anywhere except near the poles.\n\nThe earth's magnetic field is oriented to the poles, so any magnet that tried to work with it would be able to repel or attract north to south, not up and down. \n\nIf you've seen a magnetic force diagram, with what looks like wings around a bar marked north and south, that's basically what you have- you can push along those lines, but you can't really use them to push sideways. For the earth's magnetic field to be usable for levitation, you would have to have what's called a monopole- basically, earth would have to only have north or south magnetism, with the force lines radiating outward towards space."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
54j6jg
|
the difference between the 3 most common calendars ?
|
How can i have 3 different ages when i'm born on the same day ?
Edit: I meant The Western , Hebrew and Islamic calendar.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/54j6jg/eli5_the_difference_between_the_3_most_common/
|
{
"a_id": [
"d82dek9"
],
"score": [
3
],
"text": [
"First of all, the Hebrew calendar really isn't one of the most common calendars - there are only about 14 million Jews in the world. The Chinese calendar for example is much more common.\n\nSecondly, the three calendars count the years from a different starting point. The Hebrew calendar counts the years from the supposed creation of the world, the Gregorian calendar counts the years since the supposed birth of Jesus, and the Islamic calendar counts the year since Muhammad's emigration from Mecca to Medina (known as the Hijra). Also, since the three calendar have different months, they also have different starting point - the Gregorian new year is in January, while the Hebrew new year is in the month of Tishrei, which is around September-October.\n\nThe Hebrew calendar is basically lunar - the new month starts at the new moon. The year is divided into 12 months based on the lunar cycle, which means that each month is 29.5 days on average (i.e. some months are 29 and some are 30 days). The problem with this is that is doesn't align perfectly with the solar year - 12 lunar months are about 354 days. So, every few years, an extra months is added, and we get a 13 month year. This works on a cycle of 19 years - out of every 19 years, a month is added to 7 of them, resulting in the Gregorian and Hebrew calendar synchronizing. That's why the Hebrew holidays tend to move around the calendar, but not too much (Passover is always celebrated in the spring, for example).\n\nAs far as I know, the Islamic calendar is also lunar, but it doesn't have the corrections that the Hebrew calendar has, so every years is 354 days and the years don't sync up with the Gregorian calendar. That's why the current Islamic year is 1437 even though the Hijra was 1394 years ago."
]
}
|
[] |
[] |
[
[]
] |
|
dvxudc
|
why does the body produce ldl cholesterol if it promotes heart disease?
|
I know that the body uses bits and pieces of other kinds of lipoproteins to make LDL in the liver, but why do that if it causes problems later? Is there any benefit to having LDL cholesterol in the blood/tissues?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/dvxudc/eli5_why_does_the_body_produce_ldl_cholesterol_if/
|
{
"a_id": [
"f7fen7u"
],
"score": [
3
],
"text": [
"LDL inherrently does not lead to heart disease, but elevated LDL levels are what's bad. You need SOME amount of LDL to keep things in balance, which is why your liver produces it. But if you also eat foods high in saturated fats that will elevate your LDL levels (the LDL you liver makes, PLUS the extra you're ingesting) and cause buildup in your arteries which causes a lot of the issues which stem from high \"bad\" cholesterol.\n\nYour cells all contain some LDL cholesterol and it's required for them to function. But just like drinking water, too much of anything can kill you. _URL_0_"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Water_intoxication"
]
] |
|
brhi5g
|
why did uber’s ipo fail so badly?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/brhi5g/eli5_why_did_ubers_ipo_fail_so_badly/
|
{
"a_id": [
"eodv93h",
"eody37g"
],
"score": [
4,
2
],
"text": [
"In short, Uber has never shown a profit, and people (including money people) are well aware of that.\n\nAd to that limp revenue growth, and Uber stock is less than appealing.",
"If it's in the news it's a current event, and that's not allowed on ELI5. Better to r/askeconomics."
]
}
|
[] |
[] |
[
[],
[]
] |
||
2dsmd2
|
how does a mosfet switch work?
|
Specifically, in a personal vaporizer. I recently bought a device that uses two 26650 batteries, wired in series. And was told it's using a mosfet switch, with 15k resistors, to take the stress off of the button. I generally am able to pick this stuff up pretty quick, but this is absolutely out of my reach for some reason. Thanks!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2dsmd2/eli5_how_does_a_mosfet_switch_work/
|
{
"a_id": [
"cjsmsh9",
"cjsmsjh"
],
"score": [
3,
3
],
"text": [
"It is just a type of transistor. All of which can be used for amplification or solid state switching.\n\nTL dr : give gate/base voltage, opens/closes connection at source drain / collector emitter.",
"A mosfet is a type of transistor, which is just a switch without moving parts. It stands for metal–oxide–semiconductor field-effect transistor. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
7sftk6
|
if our voices sound lower to us than they actually are, how do we ever hit the right notes when singing?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7sftk6/eli5_if_our_voices_sound_lower_to_us_than_they/
|
{
"a_id": [
"dt4dsoe",
"dt4gber",
"dt4gd53"
],
"score": [
2,
6,
3
],
"text": [
"For those who don't use earpieces when singing - training. They learn what their voice at a certain note sounds like to them, and they use it. The fact that it may sound different than the real note makes no difference, because it will always sound the same to them while they are singing.",
"Our voices aren't lower in tone or pitch than we perceive, but rather are lower in timbre, the quality or character of the sound we hear. So our voices sound \"different\", but the pitch is essentially the same, so we can match the tone to the right notes when we sing.",
"TL;DR at the bottom, I figured a broad explanation would help here.\n\nIt doesn't only have to do with the sound, but also the feeling. All sound is basically a vibration; a wave moving through a medium. On a large scale, such as a mining explosions, they use different types of explosives for different frequencies that certain kinds of rocks are more vulnerable to. The shock waves produced aren't just heard by your ear, but also felt by your body. In the case of singing, this is doubly true, because you can feel the specific vibration of your throat and chest as you sing. Couple this with the pitch you hear, and you can generally train yourself to match these two.\n\nOur ears also do an exceedingly fast type of \"aural math\", where the interpretations from the inner ear hair and eardrums will actually measure frequencies in a relative way. If your ears are picking up multiple frequencies, then your ear will automatically determine the ratio between them. For example, you can tell when something if out of key, because the note simply has a dissonant resonance with the rest of the notes in that key. This makes sense because an octave works by matching the peaks and valleys of one frequency with a few peaks and valleys of another. Of course, this also has to be trained or learned over time, but the idea is that you can fine-tune yourself to not only hear, but \"feel\" these things as you sing.\n\nWhen you compare wavelengths of octaves with eachother, you'll notice that they are in sync with eachother, except the lower wavelength will have a longer periodicity (repetition time between peaks and valleys, forming full cycles) than the higher wavelength. You ears (generally) know if two notes aren't octaves, because their corresponding wavelengths will be out of phase with the other, as opposed to having frequently matching peaks and valleys.\n\n(I know this is a bit of a ramble, but I think it should accurately explain how you can learn and experience these phenomena when you sing. As an extra note, hearing these minute differences in frequencies is much more obvious at lower frequencies, because there's much less for your ears to \"calculate\".)\n\nTL;DR: In practice, it takes time to train your BRAIN to understand the interpretations of your ears. It helps when you take into account the physical vibrations of your body when you sing, and trying to match it with the pitch of what you're hearing. Humming is a great way to match the rumbling feel of a bass guitar, for example."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
31jbr5
|
why does it cost upwards of $50 to ship from usa to australia, yet i can get the same thing from amazon with $10 shipping.
|
Looking to buy a few things that I can't get from Amazon and the shipping is upwards for $50 for something that is $20, yet I bought something on Amazon last week that was significantly bigger and heavier and it only cost $10 shipping.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/31jbr5/eli5_why_does_it_cost_upwards_of_50_to_ship_from/
|
{
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"cq22zu0",
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"cq2prmv",
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"score": [
123,
28,
17,
5,
3,
3
],
"text": [
"Amazon ships in bulk, literally by the truckload/shipping container, which saves both you and them money. The other shipper probably doesn't have the kind of volume to negotiate the same level of shipping discount.",
"You: \"Hello, a pen please.\"\n\nPen seller: \"Here you go, $5 please.\"\n\n***\n\nAmazon: \"Hello, a million pens please.\"\n\n***\n\nEdit: format",
"Working in the book trade, this is something I see all the time. In general, shipping out of the US is more expensive and slower than shipping in from just about every other country in the world, and there's no good explanation for it. It's as if the US is deliberately trying to suppress its own small business international sales. You only start seeing parity when using marine shipping at pallet-load volumes and up. Indeed, shipping by EMS from China is so cheap they can routinely sell items to the US in the range of a few dollars, shipping one item at a time. \n\nMany Chinese manufacturers of things like gadgets and electronics accessories are now doing direct sales in the US through Amazon, TaoBao, AliExpress, and various hobby-related sales sites. Delivery time is rarely worse than twice the time to delivery for things shipped within the US, and given the discounts it's often worth that wait. If the Chinese were a little better at marketing and TaoBao cleaned up their act, they could crush Amazon like a bug. (as a company, it's already vastly larger, having bought-up Alibaba) \n",
"Almost none of the information below is correct. I've worked in logistics for almost 5 years.\n\nIt's really simple. If something is shipped domestically then you don't pay duties and taxes on it other than sales tax depending on the state.\n\nIf it's shipped internationally then you're paying duties and taxes, sometimes for both the origin nation and for the nation to which the package is being delivered.\n\nSome nations have free trade agreements which essentially allow shipments between the participating nations to ignore duties and taxes. That's why it's cheaper to have something shipped from the UK, Canada, or Mexico than it is to have something shipped from Brazil, all other variables being the same. It's up to the shipper to file with customs to take advantage of free trade agreements, but since they pass the buck to you anyway not everyone will take the extra effort. Especially if you're purchasing from a private seller or small company and not a large corporation.\n\nBig companies do negotiate rates with courier services and freight forwarders, so that does factor in but duties and taxes is very often the bigger factor.\n\nLastly, method of shipping matters a lot internationally. Ordering something right now from China that's being sent on a boat could take over 3 months to receive thanks to the situation with the dock workers in Long Beach, but the same package by air could arrive at your door in as little as 3-5 days depending on class of service and customs. Not that you'd ever receive it that quickly, but it can happen.",
"Once when I was mailing something TO the US from Australia, AusPost worker explained that the US heavily taxes incoming parcels from overseas which resulted in something like an extra $10 added to the cost. It's the same for sending things internationally FROM the US. \n\nOn this note, why do some people (I'm thinking Etsy sellers, etc) refuse to ship to Australia at all? If I'm willing to pay the shipping costs, there shouldn't be an issue. ",
"I make and ship things to Australia regularly. The cost hike for smaller guys like me is due to the fact that we are covering the cost of the discounts that bigger shippers like Amazon are enjoying. (* note Amazon also has distribution centers with inventory all over the world so it's not always shipping from the US) It's also a lack of consumer oversight and protection. Even the price of shipping supplies in the US is ridiculous. There are a few manufacturers left for things like bubble wrap and the like and they gouge you for it and there doesn't seem to be a way to get around it for a small operation like mine without a hefty investment in alternative packaging machines. I'm constantly running into supply issues due to the fact of past mergers of larger companies have erased the competition and now operate like a monopoly. At this phase it really is a monopoly. On top of all that you have UPS and Fedex trying to end USPS and lawmakers are backing them up with straddling USPS with nearly impossible financial demands for its retirees. The same thing is going on in Canada. I do expect to pay more to ship but not 5x more than a larger corporation. And it's not due to bulk shipping because shipping is a regular occurrence with metrics that can be tracked. Currently I take a few dollar hit for every international order I fulfill to try and save them some money. Transit times are also becoming less reliable. It's a mess. I can order something from China via airmail for less than I could ship it to a US destination form within the US. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[]
] |
|
5aavks
|
why are fairytales so dark?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5aavks/eli5_why_are_fairytales_so_dark/
|
{
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"Basically times were far more brutal than today, life expectancy was short and an early death from war, disease or hunger was not shocking, so to grab the attention fairy tales had to be darker.",
"A lot of the fairy tales that are popular come from the Grimm brothers stories. These were originally very dark, some to the point they were seen more as for adults than children. This is mostly a stylistic thing for the brothers but there may be some attempt to frighten or scare the moral of the story into the reader as these were meant as cautionary tales of children or adults not acting as they should.",
"What we think of as fairy tales are specifically medieval German fairy tales, because that's what the Brothers Grimm were trying to catalog. Medieval Europe [was going through a pretty morbid phase](_URL_2_).\n\nThe Arabian Nights, [beast fables](_URL_3_), [porquoi stories](_URL_1_), and mythological tales in general all fall into the same category of stories.\n\nMy personal favorite fairy tale is [Bearskin](_URL_0_), incidentally.",
"Quoting /u/Rawrbear89:\n\n > This is mostly a stylistic thing for the brothers [Grimm]\n\nNot at all. The Grimms didn't invent the stories themselves; rather, they set out to record as many of these old traditional stories as they could, as they worried that the old folkways were dying out.\\* These stories were originally transmitted from generation to generation by word of mouth, and were, for the most part, cautionary tales for children: don't wander into the forest, don't talk to strangers, be virtuous, that sort of thing. The Grimms travelled German-speaking lands collecting as many versions of these stories as they could find, and then distilling from them a version that went into their books.\n\nIn doing this, they often toned down the stories. For example, in practically all the tales that became the story of *Little Red Riding-Hood*, the girl does not survive, but the Grimms nevertheless went for the (extremely rare) happy ending. Even so, the first version of their work was considered by some in 19th century society to be unsuitable for children, so the second edition was \"censored\" even more heavily.\n\nThe crucial thing to remember is that there was a huge difference between rural and urban societies in those days. In rural societies, children were confronted at a very early age with death, violence and sex; it couldn't really be avoided, since you only had to step out of the house to see all of these things.\n\nBut in urban society -- and at the time the Grimms were collecting their tales, society was already starting to become urbanized -- people were much more shielded from those things, and so tended to be offended by them.\n\nFor example, in the Grimms' original version of *Rapunzel*, her guardian realizes that Rapunzel has been seeing a man when Rapunzel complains that her clothes are becoming too tight. A rural child, used to seeing animals mating, would have no problem with that; the intellectual book-reading middle-class urban dwellers -- the very people who would be reading the books -- were scandalized by it and believed that children should be shielded from such things.\n\n------------\n\n\\* They also worried that the German language was becoming dumbed-down, but rather than simply complain about it, Jacob Grimm decided to do some study and research. He discovered that some consonants changed according to a very regular and predictable set of rules when the language that evolved into all the Germanic languages first came into being: this is called the First Germanic Sound Shift, but most linguists know it as \"Grimm's Law\". Basically, Jacob Grimm invented a new branch of linguistics, and his ideas contributed greatly to our understanding of how languages are related to each other.",
"Actually took a class in college about fairytales and my professor essentially made the point that it was more for the parents than the kids. Parents basically had this guide of what *not* to let happen to your child. Parents would read them to their kids but it was initially for the parents. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.pitt.edu/~dash/type0361.html",
"https://en.wikipedia.org/wiki/Pourquoi_story",
"https://en.wikipedia.org/wiki/Memento_mori#Europe_.E2.80.94_Medieval_through_Victorian",
"https://en.wikipedia.org/wiki/Beast_fable"
],
[],
[]
] |
||
73wikc
|
why do birds leave a white residue whenever they hit a window?
|
Birds frequently fly into my backyard windows. I've noticed that when this happens, they leave an oily white residue along with the expected clumps of feathers.
What is this residue and why does it seem to make a perfect outline of the bird's body?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/73wikc/eli5_why_do_birds_leave_a_white_residue_whenever/
|
{
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"dntncuv",
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3,
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"text": [
"The residue is made up of the oils, dirt, and dust that coats the bird's feathers. When they hit a window, the coating gets smeared onto the glass where the bird makes contact.",
"They excrete an oil into their feathers that prevent water sticking to them and weighing them down. When they crash into a window they will leave an imprint just like your hand does if you pressed it against the window."
]
}
|
[] |
[] |
[
[],
[]
] |
|
1plsov
|
why do we feel dewy and a bit "sticky" when we wake up in the morning?
|
You know what I mean. That feeling of being slightly greasy and sticky. I mean I shower twice a day and am a very hygienic person, and In the 8 or 9 hours I'm asleep it's not like I've been exercising, so why do I feel like this.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1plsov/eli5why_do_we_feel_dewy_and_a_bit_sticky_when_we/
|
{
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"text": [
"Sleep sweat, is the only reason I can think of for this. Lying under covers where you basically slowly increase the temperature under your covers until it gets warm enough for you to perspire but not warm enough to be uncomfortable and for you to notice.",
"Might have a leak sonewhere in your room causing a build up of moisture. Think of sleeping in a tent, do you make up feeling like that?"
]
}
|
[] |
[] |
[
[],
[]
] |
|
2tnt67
|
how are games with huge amounts of content like skyrim or fallout made?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2tnt67/eli5_how_are_games_with_huge_amounts_of_content/
|
{
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"text": [
"With a whole lot of skilled people, a lot of time, and a lot of money. When you have those resources you can accomplish most projects.\n\nIs there something specific you are asking about?",
"For one thing, they are a big more repetitive. You see the same dungeon maps, over and over, and the same \"get the thing from the thing\" and \"put the thing in the thing\" quests over and over."
]
}
|
[] |
[] |
[
[],
[]
] |
||
4rgpik
|
why are exoskeletons only found on insects and arachnids. why aren't they found on something the size of a cow?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4rgpik/eli5_why_are_exoskeletons_only_found_on_insects/
|
{
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"text": [
"As a creature gets bigger in size, so would the exoskeleton. At a certain point, the exoskeleton would be so heavy it would actually crush the creature inside.",
"Insects and arachnids don't breathe in and out with lungs like mammals, birds, or lizards. Instead they breathe by opening tiny holes in their exoskeletons called tracheae on their stomachs to exchange air.\n\nIf an insect is larger, there is more distance between the tracheae and the inside of their body. This makes it harder for those parts of the body farthest from the exoskeleton to get oxygen and get rid of carbon dioxide. If not enough air exchange happens, those areas would starve and would not survive.\n\nInsects were much larger in the past because the oxygen concentration in the air was much higher than it was today. This allowed more oxygen to go through the tracheae so the insects could grow to larger sizes.\n\n",
"Giant insects (with suitably giant exoskeletons) existed during the late carboniferous and early Permian periods about 300 million years ago. However, as atmospheric oxygen decreased, so did insect size. ",
"A bit less like you're five, but maybe more interesting.\n\nIf you somehow had a creature that was a cube 1 cm on a side, its volume would be 1 x 1 x 1 = 1 cc (cubic centimeter). Its surface area would be six sides of 1 cm squared, so 6 cm squared.\n\nNow double the dimensions. The volume is now 2 x 2 x 2 = 8cc. Its surface area is now six sides of 2 x 2 cm, which totals 24 sq cm.\n\nSee what happened? Doubling the dimensions made an EIGHTfold increase in volume... which also means eight times the weight of the original, with only four times the surface area to hold it in. That surface would have to be twice as strong to support all the internal guts of our little beasty!\n\nI've never heard of a term for this, but I call the general idea \"scaling.\" You cannot just scale up something and have it still work, or hold together, or support itself.",
"Because no one would go near a cow for milk if it would look as frightening and savage with an exoskeleton"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
||
4y6fha
|
dialysis treatment
|
I have a friend who's kidneys are failing right now and the doctors don't know why right now. But they said they are going to start Dialysis , I've heard of it before but I'm not really sure what it is and want to understand if he's going to be okay or not.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4y6fha/eli5_dialysis_treatment/
|
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"Basically blood is pumped into a machine that does the work that kidneys normally do i.e. filtering the blood and removing waste products. This procedure is generally performed on a regular basis but the frequency depends on the state of the kidneys.",
"/u/grande1899's comment explains hemodialysis, but there is also peritoneal dialysis. I have a fair bit of experience with this, since my kidneys have failed and I've been through it.\n\nIn peritoneal dialysis, a catheter (flexible tube) is inserted into the abdomen, and a solution is passed into the peritoneal cavity, where it dwells (sits) for a period of time. The solution causes waste products in the blood to diffuse through the peritoneal membrane, into the solution, and the solution is drained back out of the catheter after it dwells. A session of peritoneal dialysis typically consists of several of these cycles, often overnight using the help of an automated machine.\n\nThese cycles help rid the blood of waste products - a job that healthy kidneys do very efficiently. This isn't the only responsibility of the kidneys however - they also produce the hormone erythropoietin, which stimulates red blood cell production. Additionally, they regulate blood pressure and control fluids via urine production.\n\nAs I said above, I'm going through renal failure. I'm also only 28, so I'd be happy to answer any further questions you have about your friend who is also very young.\n\nEDIT: I'd like to add that your friend is almost certainly going through hemodialysis, since it doesn't sound like the doctors want to wait to see what's going on. Peritoneal dialysis requires a surgery to insert the catheter, 3-4 weeks of healing time, and 1-2 weeks of training if you're going to be performing the dialysis yourself at home (what I've done).\n",
"A machine gets your blood, cleans all the crap out of it and pumps it back in again. This is what your kidneys do but without the hassle.",
"Finally, my time to shine!\n\ntl;dr - get your friend onto home dialysis treatment, either home peritoneal dialysis or home hemodialysis...and do it now!\n\nFull disclosure - I'm not a doctor, and some of the things I am saying are regularly debated and disagreed upon by the medical community\n\nI spent six years doing R & D for dialysis equipment, please, please, please share this information with your friend. Not to be scary or morose, but the average life expectancy for someone on chronic dialysis is somewhere around 2 years, even though your friend is young. If he's doing dialysis in a clinic, he's probably doing it ~3x per week and about 4 hours x treatment. This is totally inadequate treatment. Your kidneys work 24/7/365. What do you think would happen to your body if you couldn't pee for three days!?\n\nHome peritoneal dialysis, as others have described, allows you to do a form of dialysis overnight (and sometimes during the day). Although an hour of PD is not as good as an hour of hemodialysis, because you can do so much more of it, it's generally considered better because you can do so much more of it. The issue is that your peritoneal membrane, in your abdomen, will \"wear out\" after a few years...meaning it's not a permanent solution.\n\nHemodialysis, on the other hand, is far more efficient. The problem is that when you do it in a clinic, you can't do it very often or very long (just logistically speaking, are you really going to LIVE at a dialysis clinic? No, of course not!). The answer to this is to perform HD in the home. This is not very commonly done, but is more common now that a device from a company called NxStage came on market a few years ago. Basically, you teach yourself how to run this piece of medical equipment so that you can treat yourself at home in your free time, and you can do it nearly every day (or, for really good outcomes, do it overnight while you sleep). The trick is to get AS MUCH TIME on the device as possible. Not to oversimplify, but the longer you spend connected to a dialysis machine, the longer you will live. The only way, logistically, to do this is to do it at home.\n\nYou can do lots of research about this online, but people who do home dialysis have lived for 20-30 years or even longer! It's really a miracle, and it's a travesty that so many people still do dialysis in clinics 3x per week.\n\nBest of luck to your friend!",
"I was 24 when I found out I had renal failure. By the time it was caught I had 10% function remaining and the only reason I found out was because I was in Mexico and lost majority of my sight in my right eye. I was freaked out and don't know what to do so I waited to return to the states. Upon returning I went to my doctor who sent me to the hospital. They were unsure what was happening as well but my blood pressure was 220/180. So they did a kidney biopsy which hurts like hell if you don't listen to the rule about don't move for 4-6 hours after the procedure. Reason being you can bleed and that blood can get trapped between your kidney and the the lining of the kidney. Shame on my for ignoring their recommendations. Found out it was renal failure and had to go on dialysis. There are 2 options regular dialysis where your blood is circulated through a machine and the toxins are removed, or there is peritoneal dialysis where you have a tube in your stomach that connects to a machine pumps you up with 2-3 liters of fluid which absorbs the toxins and then the machine pumps out the fluid and you get rid of it by dumping it in the toilet. The first option you have to go 3 plus times a week depending and the peritoneal option you have to do daily 10 hours a day. I chose the 2nd option because I did not want to be surrounded by sickly people, I already was depressed and felt terrible. I was fortunate to get a donor quickly and only had to do it for 6-8 months, but it was a nightmare. I still worked 40 hours a week so I would have to plan may days 10 hours in advance to ensure I was able to cleanse my system out. The other issue is they now say peritoneal dialysis is not as effective as once believed so I was rather fortunate. Long story short depending on their condition he may need to go on dialysis right away and not get a choice because it is already so bad that if they don't act now he could die. On a positive it is possible it is not renal failure and his body my be able to recover from the condition. And only need dialysis for the mean time. It all depends on the condition, I wish your friend luck I know from first hand experience and it's freaky but it is 100% manageable if you listen to your doctors and not think you are invincible. I'm lucky and hopefully your friend is even more lucky. Best of luck",
"The kidneys are an amazing organ that are sorely under-rated. Primarily they filter our blood. Other functions include blood pressure managment and electrolyte management. \n\nWhen functioning correctly the glomerulus filters fluid, sodium,urea and other unwanted solutes from the blood and this becomes urine. A similar mechanism allows for the regulation of blood pressure (i.e retention or excretion of sodium and fluid) and electrolytes. \n\nThere are a few particular results we look at in relation to kidenys. The eGFR (thats the estimated glomerular filtration rate), the creatnine level and the urea.\n\n- The eGFR measures how quickly the glomerulus can filter blood.\n\n- The creatnine measures the level of the byproduct creatnine in the blood. Creatnine is a normal byproduct of muscle use and movement that is cleared by the kidenys. \n\n- Urea is a waste product from then breakdown of various protiens. It's a key indicator on the extent of renal failure. \n\nYour friend will have two large tubes in their neck or abdomen called a permacath. This will be used for the dialysis.\n\nSo, your friend wil be loaded onto the machine, two tubes attached to their two tubes. The machine will swiftly pump the blood out. Now. Depending on the situation there could be two ways this is happening.\n\n- Haemodialysis: in this situation the blood is passed through a porous membrane that fits only certain sized solutes through. It's also introduced to a fluid that can assist in drawing out more fluid, creatnine and urea. However this can cause issues with blood pressures and electrolyte levels.\n\n- Hameofiltration is commonly done in Intensive Care Units and is a far slower process. It's generally continuous and uses force to push solutes through an artificial, porous membrane.\n\nThere's mentions of peritoneal dialysis in other comments which is a thing but also vety different. This is likely not what your friend is on. PD takes about 2 months to establish and requires some viable kideny function. It's also only indicated in chronic renal failure, rather than the acute renal failure it sounds like your friend has.\n\nUltimately your friend is very sick. However in modern medicine we have the ability to replace nearly all vital bodily functions. Dialysis is one of these. \n\nSome people live on dialysis for years, others only require it for a few days. \n\nYounger people are often better candidates for kidney transplants **if it is required**\n\nI can't say if they're going to be okay, I'm not there. I can say the team will do thier best. \n\n*Source: Renal Nurse*"
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[]
] |
|
1zgday
|
why is it we are so good at recognizing and identifying faces, but not hands, or even full bodies?
|
Unless you have face blindness, humans are insane at facial recognition, but why on earth can't we recognize someone from their body, or their hands?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1zgday/eli5_why_is_it_we_are_so_good_at_recognizing_and/
|
{
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"cfteg74",
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],
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2,
2
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"text": [
"There is a specific region of the brain that recognizes faces, and another portion for identifying any other object. I don't understand neurology enough to explain how it works more deeply, but faces do get a dedicated system in the brain, and everything else gets funneled into the \"other\" category, that just isn't as detail oriented.\n\n(This is how face blindness happens. That dedicated portion of the brain is impaired and you make up for it using your other object portion for faces, and that piece just isn't equip to tell one set of eyes, nose, mouth from another)",
"This acute sensitivity to faces probably evolved along with the great expressiveness of our facial features—the fine muscular control of our mouths, eyes, brows, etc. In other words, because we evolved as highly social animals, it was very valuable to do well in groups, and thus to communicate (send and receive) not only factual information, but also emotional states. Thus as others' faces became expressive it became useful to be more sensitive to them, and as others grew more sensitive to faces it became ever more useful to have facial features that were more expressive."
]
}
|
[] |
[] |
[
[],
[]
] |
|
zzk3f
|
sql injection attacks and ddos attacks.
|
My university was 'hacked' today by NullSec. Is this an SQL injection attack? How sophisticated is this? _URL_0_
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/zzk3f/eli5_sql_injection_attacks_and_ddos_attacks/
|
{
"a_id": [
"c694ntm"
],
"score": [
2
],
"text": [
"What likely happened with your university is someone gained access to an administrator's password. Most of these \"hacks\" aren't as sophisticated as the hackers would like you to believe, and generally involve social engineering to gain access to the password as opposed to some hollywood-esque technical maneuvering.\n"
]
}
|
[] |
[
"http://pastebin.com/Cz893VCP"
] |
[
[]
] |
|
9zly6a
|
why do the effects of some drugs decrease with an increased dosage?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9zly6a/eli5_why_do_the_effects_of_some_drugs_decrease/
|
{
"a_id": [
"eaaa2b8"
],
"score": [
18
],
"text": [
"Say you snort some cocaine. Your brain is flooded with the neurotransmitter dopamine and you get high. But the surplus causes your brain to create more dopamine receptors, so when the high fades and you do more coke it takes more dopamine, and thus more coke, to create the same surplus and get the same effect. Consequently, when the drugs stop flowing and the dopamine levels return to normal, all those extra receptors make the normal levels seem super low and you feel like shit - \"the comedown\". Eventually the extra receptors fade away. Your mood is basically dictated by the ratio of neurotransmitters to receptors. "
]
}
|
[] |
[] |
[
[]
] |
||
3u08wx
|
why did america lose all it's factory jobs and industry?
|
What happened? Was it something the presidents allowed, or changed....or was it corporate greed and had nothing to do with our leaders...should we have taxed other countries imports so we stayed competitive?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3u08wx/eli5_why_did_america_lose_all_its_factory_jobs/
|
{
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"text": [
"People agitated and fought for better workplace conditions, higher wages, etc. \n\nThis made it more expensive to do business in America than other places. And so those businesses followed the laws of Economy and went for the cheaper route. ",
"We didn't? The US has 18% of the worlds manufacturing capability (with less than 5% of the worlds population), and manufacturing supports ~18 million jobs in the US (about 1 in 6). I'm not sure what standard you're using to measure \"all it's factory jobs and industry\" but I don't think it's a very good one.",
"Labor unions demanded stricter rules, safety requirements, pensions, better pay, paid vacations, etc etc etc. \n\nThird world countries offered MUCH cheaper labor. When it got to the point that it was cheaper to have stuff made overseas and shipped over, that's what companies started doing. ",
"There's no one reason, it was a combination of a lot of things, the effect of which was that labor costs in the US were no longer competitive with poorer countries. Why pay an American $20 hr to assemble widgets when you can pay a worker in another country $1.50 hr.\n\nAnd yes, we could tax imports (known as a Tariff), but that works both ways; the countries we're exporting to can raise the tariffs on our products. If you're not careful, pretty soon you've got another Smoot-Hawley.",
"Globalization. American workers can't compete with somebody in a developing country who's willing to work for a small fraction of the pay and no benefits or safety protections.\n\nAnd in a few years those people in developing countries won't be able to compete with machines who work for no pay.",
"Nixon's diplomacy with China in the 70s, rising cost of living in the states, and NAFTA are all things that can be considered. Plus the low cost of living in places at the time such as China, India, Vietnam and Bangladesh combined with the cost of exporting those goods were cheaper then their actual production in the states. It just makes good business to lower production costs wherever possible and America had already been moving to a more service economy then a production one. It isn't just one president though it's the nature of globalism that the world economy has been heading towards for some time itself that encourages companies to find way to increase revenues. While some might consider it standard greedy corporations being greedy corporations, globalism has actually lifted millions all over the world, specifically in Asia out of poverty. Raising prices on imports just makes other countries raise prices on your exports which makes it harder for consumers to access goods. Of course there's stories such as where you see deplorable conditions some workers are forced to labor in, such as the factories that produce Nike goods or Apple electronics, but global awareness especially with the internet brings these out to the fore front (also it's worth nothing these factories aren't usually owned by the corporations but make deals with corporations to produce these goods). So yeah free trade has been something the world has been heading towards for a long time, all though some agreements such as nafta or tpp can be argued as not promoting true free trade, and that many modern American presidents have promoted this in their administrations since countries you trade with are less likely to wage war with you and vice versa.",
"First off, our manufacturing base is actually in decent shape. It's certainly shrunk by percentage, but that's for a multitude of reasons that don't necessarily equate with job losses. \n \nA few factors:\n\n1. Globalization. A combination of free trade agreements and economic recovery. Europe in particular was in bad shape after WWII, as was pretty much everything under Soviet domination. It took decades for Europe to get back on track, and in the meantime it allowed other third world nations to catch up. It's not so much that the US lost manufacturing, it's that they were pretty much literally the only nation capable of high-end manufacturing from probably 1945-1965. No matter what it was bound to shrink as the rest of the world caught up.\n\n2. Change in economics. Just think of all of the new jobs created due to the personal computer alone. As Americans took these high-skill jobs, the now (relatively) low-skill manufacturing jobs shifted to other nations. It's division of labor and comparative advantage. \n\n3. Part of it was pay. Despite what people will tell you, big corporations didn't really want to fire high-paid union workers to go straight to low-wage third world nations; those high wages also came with high skills and high levels of experience, so it was still worth it. What happened, though, was that many unions (the UAW in particlar) got *waaaay* too greedy. If the choice is a $50/hr American and a $25/hr third world worker, they'll probably still stick with America; they're probably at least twice as efficient. When it's $80/hr to $15/hr, they almost have no choice but to do that. "
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[] |
[] |
[
[],
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|
10a98s
|
the susan g. komen scandal
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/10a98s/eli5_the_susan_g_komen_scandal/
|
{
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"text": [
"One of the senior people at the Komen foundation decided that they wanted to stop supporting Planned Parenthood because of Planned Parenthood's links to abortions. The problem is, Planned Parenthood also happens to be one of the biggest providers of mammograms which are an important cancer screening tool, and therefore should be something that the Komen foundation would support.\n\nTo accomplish this, the Komen foundation had to change their policies such that they could have a reason to stop paying for things like mammograms at Planned Parenthood without people thinking that they were cutting funding only because of the fact that Planned Parenthood also provides abortion services. In effect, the Komen foundation was choosing to ignore their mission to prevent cancer in order to support one director's political agenda.\n\nAfter the issue was publicized and people started to rethink supporting Komen the director who supported the policy stepped down and the foundation reversed course. "
]
}
|
[] |
[] |
[
[]
] |
||
e9ndyx
|
how can facial skin be dry and oily at the same time?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/e9ndyx/eli5_how_can_facial_skin_be_dry_and_oily_at_the/
|
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"falsfak",
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"text": [
"If you over wash your face or use a cleaner that is a stringent, your skin becomes overly dry and your body over produces oils to compensate. \n\nI used to have a pretty wicked case of the issue you are describing.\n\nI found that a sensitive face wash without any type of salicylic acid to be best (burt’s bees foaming cleanser works great for me)",
"Oil is not water. Oils allow the skin to retain moisture better. If you wash your skin too often with detergents, you are washing away the oil and water can evaporate easier. This tells your body to produce more oil and too much oil is not good for the skin either. If you leave soap on your skin for too long, you will get chemical burns. This tells a bit what the soap does. Water alone does no damage. The liquid soaps we have are concentrated and the amount used is much less than any advertisement or TV show or a movie shows us. The actual amount needed is often ten times less. This applies to washing up almost anything, hair, body, dishes... More elbow grease and less detergent, plenty of water.\n\nIf one washes too much, don't quit cold turkey. Take time to give your body and skin to get used to the new regime. Your skin has loads of bacteria, no matter how much you wash. Healthy skin also has good bacteria covering it and it takes time to get that biome working for you and not against you. Washing too often with soap leaves behind bacteria strains that can take soap for longer time and can live from the excess oil being produces in between. In fact, if you have very, very steady routine they can evolve to form spores before you wash up, the next generation will survive the \"purge\". You are training them to be as effective as possible while the more benevolent and useful bacteria strains are constantly killed. If you stop right away, the \"bad\" bacteria colonies will explode in size.",
"Your skin creates oils called sebum. If you create too much - often caused by excessive or unbalanced hormones - the oil can make its way to the surface of your skin. Here, it can act as a wick to pull dirt and debris from the air which gets pulled into your pores. \n\nNormally, this may be a non issue - your skin dries out due to your pores being blocked by debris reducing the available space for sebum production, also causing more to escape. Sometimes however, that dirt and debris can be allergenic or contain irritants which cause inflammation, which can in turn lead to acne.\n\nIn general, if you wish to avoid this problem you should avoid acne medicines and washes, and avoid lotion. Many acne medicines can only contain a small amount of acids to break down debris, meaning they may shave a day or two off at best, but it will also irritate your pores causing more acne to appear later. Some are so harsh they can dry out your pores allowing bacteria to crawl in much easier. \n\nLotion can help by creating a protective coating, but excessive use can cause your pores to be clogged up with the lotion. Your body doesn’t want to hydrate with lotion, it wants to hydrate with sebum - so you’re just making your skin FEEL moisturized when in fact all you’re feeling is the layer of lotion resting on top of your now drying skin. Your body will respond by producing less sebum which will eventually cause damage in the form of aging.\n\nIronically you’ll find articles talking about how you should use lotion daily. Lotion isn’t a natural thing, there’s no lotion tree or lotion fruit our ancestors picked, opened and smeared on their faces. These articles are often written by people who say how terrible their skin gets when they don’t moisturize- the reality is their skin is already in horrible shape and the lotion is what’s keeping their skin from being VISIBLY dry.\n\nEdit: with the votes moving rapidly in both directions I’d like to post some links with tl;drs.\n\n_URL_0_ - you rarely need lotion for skin health, it’s mostly for skin comfort. There’s multiple ways to moisturize, not all work for everyone.\n\n_URL_1_ - diet may likely play a part but research is inconclusive.\n\nIn general, you can start with better soaps then move to astringents alone, and only then should you consider lotions and moisturizers but ultimately it’s all a personal choice. I’m not saying you can’t use them, I’m saying you PROBABLY shouldn’t. We shouldn’t eat triple bacon cheeseburgers too but most of us still will.",
"You can be dehydrated and have naturally oily skin.\n\nYou can be dehydrated and have naturally dry skin.\n\nIt's an important distinction to figure out when caring for your skin.",
"The simple answer is that oil is not water. \n\n\nOil can help hold water in your skin but if you use too strong of a cleanser on your face you can strip away the protective oils, allowing water deeper in your skin to evaporate away.",
"So your skin is dry because you’re missing water. You could definitely miss water without missing oil. Your skin is probably over producing oil because you lack water, therefore it tries to protect itself.",
"Oil and water are two different things. \n\nYour skin produces oil, and makes more when it perceives that your skin is dry. \n\nSo using a strong stripping cleanser can actually make your skin produce more oil to compensate. \n\nHydration is water based, and is affected by how much water you drink and how much you trap in your skin with a moisturizer. Applying moisturizer to your skin when it's dry may look good, but you're not actually hydrating your skin. You should apply moisturizer right after you wash your face, as it creates a barrier and traps in the moisture. \n\nSo the general rule is gentle cleansing, apply the barrier, trap in the moisture, your skin calms down.",
"There is no 'dry and oily skin' at the same time. There is however, dehydrated and oily, which gets mistaken for dry and oily, because the symptoms for dry and dehydrated can be pretty similar. Dry skin lacks oil. Dehydrated skin lacks water. Dry skin is a skin type, while dehydrated skin is a condition that anyone can experience, including oily skin types.",
"There's a skin condition called seborrheic dermatitis, which is a form of eczema. It produces very dry, scaly, flaking skin. But in some extreme cases it can become infested/infected with a fungus, which apparently causes the skin to produce excessive amounts of oil. I've heard other explanations of why people with seborrheic dermatitis have dry, flaking, and yet super oily skin, but this is the most recent explanation I've heard. You may not have this particular condition, just saying that this may be one reason that combo exists.",
"Water. The oil is there to prevent the evaporation of water (drying) of skin. If you wash away all the oil and water in/on your skin, it will be dry. Your body will re-cover the area with oils, but oil doesn’t replenish the water (just protects from evap).\n\nUse moisturizer immediately after washing and stay hydrated to combat dry skin. \n\nPersonal opinion: you don’t have to use intense soaps/scrubs every day unless you have a specific medical condition you’re dealing with. Washing face with your usual body wash (usually much less harsh than soaps or deep cleansing face washes) is enough for daily routine.",
"The issue that people mix descriptive terms (looks flaky/rough = dry) and official terms (dry, normal, combination, oily skin types). If we would use the official term, it would be \"dehydrated\". So no, your skin is not dry and oily. It is oily and dehydrated.\n\nDry is a skin type - it is skin with tiny pores and low on oils. Dry skin can still be hydrated if taking good care of it.\n\nDehydrated is condition and can be on any type of skin. Dehydrated skin mostly shows up as flaky and/or rough patches, and comes because of lack of hydration. Oily dehydrated skin will not be fixed with oily products for dry skin.\n\nSource: extensive research (I can find you explanation articles), because apparently lots of people in shops also do not know difference between \"dry\" and \"dehydrated\", and will sell dry skin products for your oily dehydrated skin."
]
}
|
[] |
[] |
[
[],
[],
[
"https://www.health.harvard.edu/staying-healthy/moisturizers-do-they-work",
"https://www.medicalnewstoday.com/articles/322639.php"
],
[],
[],
[],
[],
[],
[],
[],
[]
] |
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