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7gl4a0 | How do Fingerprint scanners on smartphones work? | Technology | explainlikeimfive | {
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"Its alot like a barcode scanner really. Your fingerprint has a unique series of lines to it. Your phone records that pattern of lines as a code and that's your password. (truthfully though its looking for the spaces in between the lines rather than the lines themselves) That said given how many things you touch in a day... obtaining your fingerprint isnt that super hard. Which is why they are super popular really."
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7gl4fv | Why do we tune out smells? | It works for both good and bad smells and varies person to person. But I'm talking about you walk into a room with a smell, and gradually over time you start to tune out that smell. For some it takes minutes for others it takes seconds. Which is why your room can smell but since your in it so often you don't smell that smell anymore. So I'm curious... Why do we tune out smells? both good and bad. | Biology | explainlikeimfive | {
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"I think it's a predatory thing, new smells means something new is arise and we should be alert. If nothing smells new, then we cool.",
"Your nose 'smells' things when particles from the object with the scent float into your nose and make contact with various receptors. The receptors they connect with determine if those smells are pleasant, foul, etc. The thing is, this only lasts for a short while until the particles are cleared away and the receptors can reset. If you are exposed to a constant stream of those particles, those receptors become saturated and don't reset. Essentially, it becomes really hard to detect those smells anymore. At least, not until you leave the source for a while."
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7gl8iz | Why are antibiotics so effective but at the same time bad for us? | Biology | explainlikeimfive | {
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"When you are sick the bad bacteria causes you problems. Solution. Bomb it with antibiotics. Problem. We have millions of good helpful bacteria co-existing with us that also get killed with those antibiotics. So you destroy the bad and good bacteria without prejudice. Lucky for us our good bacteria has lived with us for a while and can usually bounce back to a healthy population.",
"This is a very broad question with lots of different answers. Here are a few: -antibiotics target a mechanism that both the bug and yourself have, the only difference is the dose so too much of it will kill us eventually -antibiotics are broken down into toxic products by our liver and get eliminated from our body via the kidneys so if you have too much antibiotics and pre-existing liver or kidney disease these organs can get injured. -antibiotics kill both the good bacteria as well as the bad bacteria. You need a layer of good bacteria all over you to serve as a barrier against super bad bacteria, breakdown certain food products in your gut, and all sorts of other things we are only just learning -antibiotics may kill some of the bad bacteria in your system but others can survive and evolve to become mega badass bacteria that will kick your arse ten different ways -antibiotics have all sorts of weird and unusual side effects and allergies that random people might have -antibiotics are processed in your body in different ways which may interact with other medications, such as the contraceptive pill -antibiotics arent really tested on foetuses so we dont know if it will harm your baby if you are pregnant There are plenty more reasons but thats just a few. So be careful when you ask for antibiotics or any sort of pill from your doctor. The benefit may not always be worth the risk. Especially if its just a virus and you need to suck it up and have a cupful of cement instead of crying for antibiotics from your GP."
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7glhe8 | What is happening in our brains when we think? How does a series of nerve impulses become a complex thought? | And why we can we sort of "feel" our thoughts somewhere in our head instead of, let's say, our feet? | Biology | explainlikeimfive | {
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"Being a cognitive/neuroscience researcher myself, i have to say that this is a thing no one fully understands. The brain and how it deals with sensory input, how it ultimatively makes sense of the world is an insanely complex process. In fact, we don't even fully understand how you can look at an apple and say \"that is an apple\", so don't even ask about how we understand abstract and complex topics. Some basic tasks a human is capable of, such as identifying types of fruit really really fast (within milliseconds) and really really well (over 95% accuracy) are we now trying to teach computers, as some researchers hope that this will give us some insight on how we do such things with our brain, but only to figure that it is extremely difficult and needs like a shitload of data (like more data than any human needs or ever gets, we don't have to look at 10'000 apples until we are able to distinguish it from a banana), and only leads to limited results. Moreover, a software that can identify types of fruit can not learn to identify types of animals without having to re-train it completely... Sometimes researchers go and look what happens inside the brain using imaging technology. But even that only holds limited results. It's like clamping some sensors on your computer measuring the electricity that floats trough various parts, and then let the computer do various things to see whether one can identify which parts relate to which tasks - only to see that many parts are involved in many tasks yet we still don't see what they are doing because only knowing that they do something does not tell you what it is, or how the information that is passed between the parts is represented.",
"Unfortunately, despite the efforts of a vast number of research fields, we have no idea. Due to its importance research is ongoing, but nothing resembling a meaningful answer currently exists."
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7glkmw | How do owners of big corporations get money? | Just a noobie question.. Lets say Mark Zuckerberg wanted to buy a $100M mansion, where does he get that money? Facebook is not solely owned by Mark Zuckerberg, so does he have an authority to just get $100M from the business? If not, then where does he get the money? | Economics | explainlikeimfive | {
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"> so does he have an authority to just get $100M from the business? No. Zuckerberg has a duty to the shareholders, especially since Facebook is publicly traded. If he tried to have Facebook buy the house and put it on Facebook's books, the shareholders could file a lawsuit against him, or at a minimum have him fired Couple sources CEO's of big companies get paid 1. Most of them do get a salary. 2. Since they probably own stock, an increase in stock means an increase in his personal wealth. If they want to make a large purchase, they can sell off some of it. 3. They often get more stock each year with a clause saying they can't sell it for a period of time (because if they can just dump it they have no incentive to push the price up). Sometimes they get stock options as well. 4. Dividends on the stock if the company pays them. 5. If they're with the company during the IPO (like Zuckerburg), they probably got a huge chunk of money then, too.",
"People that rich have incomes from many different avenues. But if Zuckerberg wanted to take money specifically out of Facebook, he would just sell some of his shares in the business. Usually the founders/owners retain large amounts of the companies shares or stock."
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7glldq | Whenever slaves ‘bought’ back their freedom - what stopped them from being captured and enslaved once again? | Other | explainlikeimfive | {
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"Have you ever watched *12 Years a Slave*? If you were a black man in the wrong place at the wrong time (pre-1865 America), nothing at all was stopping you from being forced back into slavery. Even if the law supposedly protected you, there was no realistic way for you support your rights.",
"As for the early US history: Nothing stopped them from doing so. tl;dr: Every slave had to get a paper from their owner saying that they are free from now on. If this gets destroyed/stolen, the person is not free. In early US history, mostly black, slaves were denied any form of education such as reading and writing. The reason is that every slaveowner had to sign a paper saying that this exact person is, from now on, a free human being. If this person could read/write you could easily copy that paper (that actually happened). Though if you don't have this paper with you or someone steals it/destroys it, then you're back on square 1.",
"As crazy as it sounds there are different kinds of slavery. The US south, generally, had what was known as chattel slavery. A chattel is a physical object, like a cow, or tractor, and that's how slaves were viewed. You could kill, rape, mutilate a slave with essentially the same impunity you could do those things to a cow or tractor. In Chattel slavery there is no \"buying your freedom\" because you don't own anything to buy it with. You are not paid for your work, and just as it is absurd to imagine a tractor having its own money, a slave couldn't have their own money either. The romans practiced a different form of slavery. Slaves often were paid and had certain rights. They were not considered cows, rather they were considered very low status people. However, in either system there are going to be situations where you might want to liberate a slave by agreement with the slave. In the american south imagine a slave coming up to a plantation owner and saying \"Sir, I figured out a new way of harvesting cotton 10% faster than the current method. I will tell you what it is if you free me.\" Or perhaps I own a plantation of 1,000 slaves and say \"Now listen here boys! From now on, each month I am going to free the one of you who I think worked hardest over the past year. You want your freedom, then you just have to give me one great year of work!\" Regardless of the situation yes, there could be bad actors, but in stable systems where long term transactions are going to be more beneficial than any short term gain through dishonesty there is going to be a general incentive for fair dealing and if I promise to release a slave I am going to be assisted by keeping my word - even if there is no legal obligation for me to do so."
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7glra2 | What's the difference between a 10Mb/s connection and a 100Mb/s one when the "bits" travel at the speed of electricity in both cases? | Technology | explainlikeimfive | {
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"Imagine two dogs. A big ol' sheepdog ... Woof ... Woof ... Woof ... Woof and a little terrier ... Yip-Yip-Yip-Yip-Yip-Yip-Yip-Yip In both cases their barks are reaching your ears at the speed of sound, but the smaller dog is getting twice as may barks-per-minute. It is the same basic idea with 10Mb/s vs 100Mb/s connections speeds.",
"Nobody is really giving a good answer. The difference is this: at 100 Mb, the bits are packed tighter together. So suppose you have a piece of wire such that it takes a [nanosecond]( URL_0 ) for the signal to travel from one end to the other. This is the same regardless of how fast you're sending data. What changes is how long you wait between changing the voltage on the wire. If you're sending data at 10 Mbps, you're changing the voltage on the wire 10 million times per second. If you're sending at 100 Mbps, 100 million times. At both bandwidths a bit takes the same amount of time to cross the wire, but in the second case it's 1/10th as long. Physical characteristics of the wire smear the signal, so that if you change the voltage too fast information gets lost. So to transmit at a higher bandwidth you can need better cabling, besides faster hardware.",
"Bits do not travel with speed of electricity through the most of their journey, they travel with the speed of light. [[Demonstration of a signal traveling through optical fiber internet cable]]( URL_1 ). The bit that is travelling is either \"0\" (off) or \"1\" (on). Once it reaches junction box of your internet provider, then it is connected to a switch and sent via [[CAT5 cable]]( URL_0 ) If you think about Internet connection like a road, then the bits travelling to your house are the vehicles. \"Mb/s\" (Mega bits per second) is telling you how many cars can travel per second through the road, it is technically called \"bandwidth\". Speed at which the bits travel is called \"latency\", and it is never as good as speed of light, because the vehicles need to pass through junctions, bridges and corners, or even a gravel road which slows them down before they reach your house. Limit of 10Mb/s usually means, that the Internet Provider simply enables small amount of their road for your bits, so that bits of other customers can also travel along them.",
"The capacity has nothing to do with how fast a single pieve of information (a bit) arrives, it rather indicates how much can be sent in parallel. Think of it like water, if you have a small vertical tube and pour some water in it, it will fall by gravity. If you have a bigger tube, it will still fall by gravity and arrive just as fast. Now lets say you add a lot of water, more than the small tube can handle, it will accumulate on top until there is space for it, the first water will arrive just as fast as before, but you'll have to wait before you have the whole chunk. While with a bigger tube, it may all pass through and fall by gravity, just as fast as the small amount of water."
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7glsb3 | Why is Random Number Generation so important for IT security? | As far as I know the primary application of RNG algorythms in IT is security algorythms such as hashing and encryption. Play Station 3 was hacked basically because some number wasn't truly random. How exactly does the ability to predict "random" numer compromise security? | Technology | explainlikeimfive | {
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"I'm thinking of an ATM PIN. What number am I thinking of? If you can guess it, you can access my checking account. It's like guessing a password. If I use a system to generate my ATM PIN that seems random, but can actually be reproduced (like taking my birthday and scrambling the order of the digits), someone could figure out the system I use to generate PINs and guess only a few times before discovering it. Randomly generated passwords are related to randomly generated numbers. Computers generate pseudorandom numbers with a lazy function called Rand() or something like it that use the time that the function is called to generate a number. This is like creating an ATM PIN with your birthday. It can be guessed if you know enough of the other pseudorandom numbers the system generated. Even perfect security - like one time pads - rely on truly randomly generated passcodes. If the code isn't randomly generated, nothing is secure.",
"At the simplest level, IT software security is based on the idea that is really really hard to guess a large randomly chosen number. This is used to separate and secure different 'sessions' of interactions. An example... I log in to a website. The website confirms my password '2' and gives me a temporary secret keyword: 6 , for further communication. You login with your password '4' and it gives you a temporary secret keyword: '12'. A hacker has been watching this and figures out that the temporary secret keyword is always the password x 3. It is not random. Which means there is a very high chance that temporary keywords like 3, 6, 9, 12, 15...exist. He can try to communicate with the website using a secret keyword : 21, and boom...he has hijacked the poor souls account whose password was 7. To prevent this, it is extremely important that the secret keywords do not have any pattern. They must not be predictable. In other words, they should be random and very long so that they are harder to guess. Now it turns out that it is very hard to generate truly random numbers, because the process you use to generate them may have a hidden pattern. It is also the case that process used to generate them is itself a pattern. So computers use what are called pseudorandom numbers. These are numbers generated using steps such that the pattern is extremely difficult to figure out because any normal computer would either need ridiculous amounts of time (age of the universe) to calculate out or it would need near infinite amounts of memory to do so. They are for all practical purposes, as good as random numbers because you can't realistically detect the pattern.",
"Computers aren't really random at all. They do everything step-by-step in a logical way that's been programmed into them. They can't \"think of a number\" like a human can. They only follow instructions, and if you use the same starting conditions and instructions, you get the same answer every time. When it comes to security, this kind of repeatable consistency (called *deterministic* output) is bad. The computer needs to create a secret key that protects the information it's creating or transmitting - if you know, or can guess, the starting conditions of the program, you can easily find the secret key that it creates. There are ways of getting around this, by using data from sources that *shouldn't* be deterministic - like user input for instance. Unfortunately that can be quite difficult to get, especially if you need to do it at start up and the user hasn't touched anything yet. You can get it from \"worse\" sources like the current time, which should be different every time you run the program, but can be manipulated. When hackers can manipulate the data the random number generator receives or if the random number is used incorrectly by the code, that greatly increases their ability to get to the secret key that the computer generated, and thus break the encryption."
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7glzgd | Why are Apple’s iOS updates so large? | Technology | explainlikeimfive | {
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"In addition to the fact that there's more to the update than they list in the little blurb description they provide, it's also down to how the update is packaged. Some companies choose to provide updates in a \"delta\" format, where only the changes to files are sent to your device. In that format, the computer must calculate the new file using the old file and the provided delta data. This process is pretty reliable, but not perfect. When you're talking about OS files, this process can introduce errors that brick your device. Companies that use this for updates have to write additional code to check for errors and correct them, and sometimes updates may need to be downloaded multiple times as part of that. It saves time and bandwidth for most people, but it can unpredictably cost a lot of time and bandwidth for some people when it goes wrong. Apple often chooses to supply the entire updated file instead of just sending those bytes that changed, although they do now support delta updates. The advantage to full file updates is that there's no calculation needed on your device to install the update. You just change the code that pointed to the old files to point to the new files. If there are any problems, point them back to the old files. It's a more reliable method for the consumer, and is more predictable, but it does mean that updates include a lot of duplicate data you already have on your device."
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7gm1pe | Why do bees make honey but wasps don't? | Biology | explainlikeimfive | {
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"The reason for this is because since wasps eat meat and are parasitic creatures by nature they do not need to produce honey as bees do. The reason that bees produce honey is so that the young larvae have something to feed on while they grow where as wasp larvae feed on the body of the host they were implanted in. Bees also produce Royal Jelly which is a different more concentrated version of honey that they feed to the queen, it also has health benefits when consumed by humans. TLDR: Wasps don't make honey because they're cunts!",
"Because most wasp species are primarily carnivores, and some are even obligate carnivores. They don’t get a choice. They eat meat. Bees make honey for themselves, not consciously for us or for any other animal. It’s in big enough quantities that we can usually take some without really inconveniencing the hive, but it’s not *for* us. They gather nectar to eat, and honey in combs happens to be the best way they have of storing the food for later use. You need nectar from flowers to produce honey. What reason would a mostly or entirely carnivorous wasp have to gather all this nectar it won’t or can’t eat?",
"Wasps don't survive the winter in their nest. The wasp queen will find a hiding place to hibernate during the winter (like many other insects do), the rest of the colony will just die :(. When spring comes, she will start building a new hive and a new family. Bees on the other hand, they stick together in a big ball inside their hive to keep warm, and they'll move around and buzzzz to stay warm and take turns to be in center and the outside (except the queen, she'll stay in the warm center) so they need to store that sweet honey for for the winter when they can't find food outside. **TL;DR:** The wasp queen hibernates alone, without eating. The bees stick together working to keep the queen warm, so they need food during the winter."
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7gm7e2 | where does all of the Carbon dioxide we exhale come from? | We've been taught in schools that we breath in Oxygen and exhale Carbon Dioxide. We exhale just as much we inhale so where does all of this Carbon dioxide come from? | Biology | explainlikeimfive | {
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"> We exhale just as much we inhale This is only an approximation, there is a very little amount of O2 (oxygen) being absorbed by the blood and CO2 (Carbon dioxide) being released from the blood into the air, compared to the total volume you inhale/exhale, so you wouldn't notice the difference from the different molecule size, or temporary imbalance in number of molecules. > so where does all of this Carbon dioxide come from? When our cells need energy they oxidize glucose (sugar) from your food, extracted by your stomach, transported to the cells via the blood. The rest products are CO2 and water, both absorbed by the blood again. Some of the water is also absorbed by the air in the lungs, so in total you are probably breathing out more than you breathe in actually, at least in weight, although the volume may be the same.",
"You breath in Oxygen as a component of air. It gets diffused into your blood stream. That oxygen is used in a reaction with sugars which produces CO2 as a waste product. That CO2 is carried back out by your blood into your lungs, where it gets exhaled. Now think of this: When you are exercising to lose weight, it's because you are using those energy stores at an accelerated rate. You are actually breathing your weight away as your muscles require more sugar to be used up.",
"From all the things you eat. A lot of what we digest as food are carbohydrates. When we use energy, it comes from chemical reactions splitting those in much simpler compounds, including all the CO2 we exhale."
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7gmb8w | What exactly is radiation and how does it affect our bodies? | Physics | explainlikeimfive | {
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"technically speaking radiation is anything emitted. So light is radiation, so is heat, you can radiate almost anything Assuming you mean nuclear radiation from what we consider radioactive compounds: Radiation are tiny bits of energy given off by nuclear reactions/decomposition. When an atom splits into smaller atoms (some atoms are inherently unstable, which is what radioactivity is) it gives off energy and sometimes small particles (on that scale the 2 are very similar). These particles fly through the air at really high energy and hit things, depositing their energy. Alpha particles are pretty big (2 protons and 2 neutrons) and they can make you sick by destroying parts of your cells. Beta particles are much smaller and often not as bad. Gamma radiation are tiny bits of energy and they can just cut straight through you, but are so small you only get cut at a cellular level (which is what radiation poisoning is). So radiation, with regards to radiation poisoning, are tiny tiny particles/bits of energy that shoot into your body and damage your cells. They are given off mostly in nuclear reactions and inherently unstable compounds."
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7gmf1d | Why is uracil only in RNA and not in DNA? | Biology | explainlikeimfive | {
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"The reason is because uracil is not stabile as thymidine. It's an evolutionary advantage to use thymidine in DNA to preserve stability. However, in RNA, you don't need the stability because RNA doesn't stick around that long."
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7gmqso | What is the difference between time signatures that have the same ratio? | For example, why would someone choose 2/2 time over 4/4 time? It will still give your 4 quarter notes per measure, just at half the time spent on each quarter note. | Other | explainlikeimfive | {
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"Played at the same speed, the difference is in the accent — that is, where you put more emphasis. Listen to Sousa's [Fairest of the Fair]( URL_2 ). As soon as the drums kick in, you should be able to get a really strong \"one, two. one, two.\" sort of feel. That's what 2/2 or 2/4 sounds like. Now pay attention to the bass line for Queen's [Crazy Little Thing Called Love]( URL_1 ). That's a \"one two three four\" feel. That's your 4/4. Let's try the ones that are multiples of three now. 3/4 vs 6/8 is the difference between \"One and Two and Three and One and Two and Three and (...)\" for 3/4, and \"One and a Two and a One and a Two and a (...)\" for 6/8: one has three beats that divide into two halves, the other has two beats that divide into thirds. You can hear this difference in Bernstein's [America]( URL_0 ) from West Side Story: The bit that goes \"*I* like to *live* in A-*me*-*ri*-*ca*\". Note how The first half has two accents (\"I\" and \"live\") and is in 6/8, and the second half is 3/4 with emphasis on \"me\", \"ri\", \"ca\".",
"Its not always about the ratio, its mostly about where you want the emphasis to be and how fast that beat goes. Also keep in mind that in many 20th century arrangements composers will stick in measures with different time signatures to produce a certain effect, and those measures don't always behave the same as if an entire piece were written in that meter. Some time signatures are close to interchangeable. 2/4 is often really similar to 2/2 or \"cut\" time even though those aren't the same ratio as 2/4. Having the beats on quarter notes is a little easier to read for some musicians that haven't played a lot of the old marches written in cut time. Others are not. 3/4 is 3 beats per measure, each beat being subdivided into 2, while 6/8 is 2 beats subdivided into 3. 6/4 can mean a few things. If an entire piece is written in 6/4, it probably is in a slow 3. But if a random measure is in a piece, it may just represent a 4/4 + a 2/4 measure to extend a phrase by a couple of beats. In addition to 2 vs 3 feel, the composer arranger will take other things into account, like how much work would the conductor be doing, and how much effort is to write everything out. Going back to 2/4 vs cut time, the advantage of 2/2 is that really fast notes can be written as 16th notes instead of 32nd notes. That makes it easier to read and easier to write.",
"The main difference is a combination of which notes get emphasized, how the notes are distributed in the measure, and what kind of music is traditionally played in that time signature. 2/2 with emphasizing every other beat, divide each measure into two parts, and have a march-like quality. 4/4 emphasized every fourth beat, and you might see a quarter note-half note-quarter note order you would be unlikely to see in 2/2. Similarly, 3/4 is usually a waltz 1-2-3, a measure's rhythm would rarely be divided between two dotted quarter notes. In 6/8, when it is divided, it is almost always going to be divided into two parts between the third and fourth beats. Edit: Fixed some confusion /u/samdajellybeenie helpfully pointed out.",
"2/2 time and 4/4 time are actually very different. 2/2 songs are usually a bit faster, vs 4/4 time which is very standard and can go all over the place. You usually only see 2/2 time in marches, to keep time with feet while marching.",
"It has more to do with the way the song is written rather than played. If you want something looser that you can experiment with, you have a time signature that you can fit more notes into. If you want something to have a more rigid structure, then the time signature that you can fit less notes per measure into will work.",
"Finally an ELI5 I can answer. One of the important things in music when composing is how the accents are placed. This is basically just musical emphasis. It can either be marked directly, where a little symbol is placed underneath the note, or indirectly, where a time signature is used. Take, for example, [this section]( URL_0 ) from Gustav Holst's *Jupiter*. As you can hear, the emphasis is a \"**dun** dun dun **dun** dun dun\" where each of the emphasis (I'm unimaginative) is on the third beat. If you try and imagine the emphasis on each other beat in a \"**dun** dun **dun** dun **dun** dun\", it would sound much different (if we stripped the piece of the chords and had just the horns playing at that point). Now, here's the kicker: **This should explain it.** Now, of course, you might not understand it, so here goes: The piece is currently in the time of 6/8. This is a series known as **compound time**. This is basically where you get groupings of 3 in one beat. The visualisation where the duns would be on the other beat is what's known as **simple time.** This is basically where you get groupings of 2 in one beat. (it would be in 3/4 btw) Next, to answer your question, listen to the [Colonel Bogey March.]( URL_1 ) You can feel a 2 feel - 1,2,1,2 - this is due to the accents, which are naturally placed. Listen to the bassline in particular - you can hear a repeating pattern in groups of 2s. Now listen to Queen's [Break Free.]( URL_2 ) Hopefully you can feel the 1,2,3,4,1,2,3,4. You'll notice a lot of pop songs are written this way. Both of those pieces can have a 4/4 time signature or a 2/2 - but it doesn't work for either. As for why composers just use 2/4 instead of 2/2 - the way music is written, it's a lot harder to read if the music is fast. I hope I explained myself well, this being the first ELI5 I've written."
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7gmqwn | why aren’t all plastics recyclable? | Chemistry | explainlikeimfive | {
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"They are! It's just that not all plastic *items* are *economical* to recycle. The best example is probably plastic grocery bags. Most of them are made of HDPE, the same plastic that's used to make milk jugs. Most of the rest are LDPE, the same plastic that's used to make food squeeze bottles. But why are plastic bags not accepted for recycling when they're made of the same plastic that milk jugs and squeeze bottles are, when those two *are* recyclable? The answer is that plastic bags are a nightmare to *process*. For plastic recycling to be economical, it needs to occur at industrial-scale volumes. The process isn't entirely automated, as human \"pickers\" are still used for certain parts of the sorting process, but a lot of what even the pickers do involves operating heavy machinery. Grinders are the important machines for this conversation. The problem with plastic bags is that because they're so thin, they don't really grind up very well. They tend to jam the machinery, particularly in any kind of quantity. So, why couldn't they just be sorted by hand and fed straight into some a smelter? They could! But the plastic used to make them is so cheap, and the amount of plastic in any single bag is so small, that it would cost more to sort and process the bags than you could possibly get from selling the recycled plastic. Say a picker can average one bag every second. They weigh, what, a tenth of a ounce? So 3,600 bags in an hour, that's 360 ounces, or. . . 22.5 pounds. Oh, and that's assuming that none of the bags are wet or dirty. Neither of those are okay, so the pickers would have to just throw those bags out, or at least separate them from the main stream. So realistically, we're probably looking at maybe 20 pounds an hour, if we're being really, really generous. The problem is HDPE sells for less than a dollar a pound, most of the time. So a picker processing plastic bags would generate less than $20 worth of plastic every hour. Possibly as little as $15. With those figures (which I did make up but are in the right ballpark), you'd probably be paying anywhere from 50-75% of your revenue in labor costs. That's not just unsustainable, it's completely non-viable. That figure would need to be more like 15% or so. Remember, recycling processors have to pay for the material they recycle, either in the form of collecting it themselves or paying other people to do it Plus pay for their machinery, a building in which to operate the machinery, and all the normal administrative overhead that goes into running what amounts to a manufacturing business. A picker needs to produce *hundreds of pounds* of sorted plastic every hour to justify their existence, and that just can't be done with plastic bags. This is also why other low-density and/or low-weight plastic items aren't generally accepted at most recycling centers. Packing peanuts. Plastic film/wrap. Styrofoam (and other polystyrene products). Can the plastics themselves be recycled? Yes. But not with the same machinery used to recycle denser/heavier plastic items, and the amount of plastic in these lighter items is so low that there's no economical way of processing them on their own."
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7gmw87 | What happens to the body when you donate one of your kidneys? Does it become less able to filter stuff out of your body? | Biology | explainlikeimfive | {
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"When you donate one kidney, or one kidney fails, the other will pick up the slack. When functional, both kidneys are not operating at the fullest capacity.",
"Yes and no. \"Yes\" in that your total renal capacity will obviously go down. But \"No\" in that most people don't make full use of their kidneys anyway. So maybe that one kidney has to work harder than it used to, but a single kidney is generally adequate. If that remaining kidney starts to get into trouble though, you're in quite a spot. You can't afford to lose all that much renal capacity if you've only got one kidney to begin with."
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7gn1km | How does a volcano erupt? | Why are all volcanoes different despite all of them being a vent to inner surface of the earth? | Physics | explainlikeimfive | {
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"Beneath every active volcano is it's magma pocket. When the pressure in the magma pocket from the gasses and the magma itself builds up enough, it overcomes the pressure that the layers of stone above the pocket are able to withstand, there's an eruption. The more pressure is built up, the more the eruption's violent. Savvy?"
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7gnkyu | Why does the bowl always get hotter than the food in the microwave? | Every damn time i microwave soup or other food i bowls the ceramics always come out steaming hot while the food still is cold. Any good reason for this? | Physics | explainlikeimfive | {
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"Because the bowl and the food have a different specific heat. Specific heat is a measure of how much energy it takes to raise the temperature of that material. Materials like metal or ceramics have a low specific heat, so it doesn't take much energy to change there temperature. Water, which your food is mostly made of, has a high specific heat, takes a lot of energy to heat it up. So in the case of the food and bowl in the microwave, the same amount of energy is put into both, but it results in a larger change in temperature in the bowl than the food."
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7gnoqb | How does charcoal clean your face? | Recently, I've been seeing a lot of advertisements touting "activated charcoal", and talking about how it will "attract the dirt from your pores". How does this work? Does it even work? and how is it any different than rubbing charcoal on your face? | Chemistry | explainlikeimfive | {
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"Charcoal generally has the property of having lots of pores that are approximately the correct size for medium-sized organic molecules to enter and become trapped. Activated carbon/charcoal has been produced in a way to maximize those pores, making it better at that process. If you're making charcoal for fuel, you don't care about the ability to adsorb oils or contaminants. If you're making it for a water filter, you don't care how it burns, you want to maximize pores and surface area.",
"I would imagine it has to do with the absorption properties. My son ate some medicine he shouldn’t have once and the doctors made him drink activated charcoal. Did the trick. So it would seem it pulls whatever it can into itself and away from whatever it was in. Makes sense to me anyway.",
"Charcoal and activated charcoal are two very different things. Could rubbing plain charcoal on the face just clog skin pores? I can't imagine it having any cleansing effect on skin. Not even sure about activated charcoal. First it has to get into the pores, but it also has to come out. Will simple rinsing with water do it? Activated charcoal (aka activated carbon) is traditionally used to filter water and to treat certain poisons. It does have a phenomenal ability to remove various contaminants and it's fairly safe even when ingested, so..."
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7gnq0e | Why in games/movies a gaint the size of a mountain is shown as moving really slowly?? | Biology | explainlikeimfive | {
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"They appear to be moving slowly because you are used to things that are normal sized moving at normal speeds. (sorry for the bastard units in advance) A person with a 3 foot arm throwing a punch in 1/2 second is moving at 4 miles/hour (6.5 km/hour). A Giant with a 100 foot arm throwing a punch in 1/2 second is moving at 136 miles per hour (219 km/hr). The sheer amount of force required to accelerate and decelerate to those speeds would be staggering. Not to mention the squared/cubed rule of muscle density. So basically large creatures appear to move slow because they have so much more space to cover to complete an action than a small creature would have to cover to do the same thing."
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7gnswu | what is the process of going into shock? | Biology | explainlikeimfive | {
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"Paramedic student here. When we speak of “shock” we are talking about inadequate tissue perfusion- basically, for whatever reason, oxygenated blood is not reaching the patients tissues. There are 5 major types of shock- hypovolemic (loss of blood volume, ie, the patient is bleeding out) cardiogenic (there is an issue with the mechanical activity of the heart pumping blood to the body), neurogenic (there is an issue with either the brain controlling the heart, or the electrical system in the heart itself) anaphylactic (life threatening allergic reactions, or other adrenal issues affecting perfusion) septic (massive systemic infections) In pre-hospital care (when you call for a paramedic), we can manage some of these. For hypovolemic, we can give you IV fluids to replace lost blood volume, but we have to balance that with making sure theres still enough actual blood there to carry oxygen to the tissues. For septic, we give fluids as well, but in the hopes of diluting the blood- theres very little we can do in the field to actually combat septic shock. For anaphylactic shock, we can give medications to mitigate and lessen to bodies reaction to what ever triggered the event. For neurogenic shock, we try to control heart rate and BP, without letting the system crash. For cardiogenic, we try to get you to the hospital as fast as we can, cause there’s not much we can do for you in the field. Another issue with shock is that there’s 3 levels of shock- compensated, decompensated, and irreversible. Compensated shock is the early stage, where the patient is sweaty, pale, and has a rapid heart rate. This is the stage that is easiest to manage. Signs/symptoms can include agitation or anxiety, fast heart rate (tachycardia), fast breathing (tachypnea), nausea and/or vomiting, and a weak or thready pulse. Decompensated shock is the mid stage, where the patient becomes mentally altered (seems intoxicated, or passes out entirely), has no pulses in the extremities (but still has a carotid pulse), labored or odd breathing, and a falling blood pressure. This is the shock stage that we throw everything we have at, in order to keep the patient alive so we can get them to a doc. The last stage, irreversible shock, is just that, irreversible. If you hit that point, you’re gonna die. Medics and doctors will do everything they can, but at that point, it’s a losing battle. Patients in this stage have lost the carotid pulse, they’ll have very shallow and irregular breathing, very low blood pressure (hypotension), and they’ll be unconscious. Our ultimate goal, regardless of the type or level of shock, is to get you to a hospital, or ‘definitive care’ as we call it. Medics, despite all the tools, techniques, and meds at our disposal, are bandaids. We can stabilize, but it takes a doctor to fix the problem. So if you call 911, and the medic says you need to see a doc, go see one. Ideally, the medic will take you, but not every fire service does their own patient transports.",
"There's a lot of good comments here describing what medical shock is, but OP is almost certainly asking about what most people think i called shock, i.e. an acute stress reaction, or ASR. Actual medical shock is a lack of oxygenated blood perfusing to tissue, but that isn't what people think shock is. That's because a bunch of movies/TV show someone who experiences a very intense event, like being shot, or seeing someone die, and they call that shock. That isn't medical shock (unless they bleed a lot from the bullet). That's a stress reaction, caused by the same soup of neurotransmitters that cause panic attacks and other such events.",
"The medical term refers to a sudden drop in blood pressure. This is often due to blood loss from a wound or cardiac malfunction. The loss of blood pressure results in insufficient oxygen reaching organs. If the organs are starved of oxygen too long, they will fail. If the organ is vital to living, its failure will result in death. Even with non-vital organs, their failure often leads to a chain of other organ failures, eventually causing the failure of a vital organ and thus death in short time."
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7go2ts | Why and how do starlings perform murmurations? | URL_0 | Biology | explainlikeimfive | {
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"To form a community bond, the benefits are safety in numbers from predators, peregrine falcons, and hawks, find it hard to grab in the in a massive flock, they tend to go for solitary birds, they roost together keeping warm, and safe, then birds who have had success in food search the previous day can form, lead the morning search, and they don't have to waste time looking for a mate, and when their chicks fledge it's not just down to the parents to teach. If you carefully watch a murmuration form, the numbers expand as dusk draws in, it's visible from miles around, so stragglers can locate the flock before nightfall."
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7gool9 | How does throughput actually work on cabling? | I understand what throughput and bandwidth are now. I get the ANALOGY. But don't understand the literal use and how its implemented. I get that its not the speed of the signal, thats always the same really. its how many bits are sent at once. like a bus vs a 2 seat car. But how can you sent more than one bit at a time? on a wire you have one bit after another. its not at the same time. voltage represents bits. [Unless it is referring to UTPs]( URL_0 ) in UTPS, there are many other smaller wires. So is it saying that bits are sent on the different wires at the same time? like if you want to send the transmission 1010 on one wire, it will be 1...0...1...0... But using UTP with 4 wires, its all at the same time? (if so, how does the device know which bit comes first in that block of bits sent at once?) | Technology | explainlikeimfive | {
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"Your question is less about throughput/bandwidth, and more about how bits are modulated onto a cable. That's a fancy way saying how is a digital quantity (one or more bits) represented in the real physical world. Trivial case is two different voltage levels. We'll use +10/-10 volts as an example. When a device wants to send a bit, it can represent a 0 as -10 V and a 1 as +10 V. We'll call this concept of sending a bit with voltage, a symbol. The voltage for each symbol well be held steady for a specific time, intuitively called the symbol time. In my theoretical standard, 0 volts could perhaps mean no data is currently present (in practice far more complex framing schemes exists to determine when real data is present). I think you can already understand everything I just said, so let me know if I'm mistaken. A receiver built to my standard will start idle and wait there, continuously measuring the voltage. Once the voltage transitions away from 0V it is aware that data is now present. It can than determine the bit sent based on the voltage measured. This process can be referred to as demodulation. Then wait the symbol time and sample again. If the voltage ever goes back to 0, then no data is being sent and the receiver can return to an idle state. In reality there are several other details that are very important (and links with more bandwidth are much more complex than this example) but this is a good introduction (and is similar to how RS-232 works). Now to rephrase your question, what if I want to send more than one bit of information in a given symbol time. As you noted you could use multiple wires to send multiple symbols. However nothing says my symbol has to be able to only represent one bit. Indeed many standards have 2, 3 or 4 bits per symbol. Let's go to a 2 bit symbol. for 2 bits, there are 4 possible states (00, 01, 10, and 11). We can use four voltage levels to represent these bits. We'll use -10 to represent 00, -5 to represent 01, +5 to represent 10, and +10 to represent 11. The receiver would work very similar to my previous example, but now instead of demodulating 1 bit per symbol, we're demodulating 2 bits per symbol. There are a LOT of standards for how bits are modulated and sent across a medium. From your comments (if you're really interested) I would suggest you you first study a simple protocol like RS-232 which is really only sending one bit at a time. However it also discusses start/stop bits and you may be able to understand how a simple receiver can be built. Than you can start to look at the more complex protocols used in Ethernet like 1000Base-T (gigabit Ethernet over copper cabling) which play some very interesting games but require a much broader knowledge base to understand."
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7goonu | If the universe is expanding in all directions, does that mean that the universe is shaped like a sphere? | I realise the argument that the universe does not have a limit and therefore it is expanding but that it is also not technically expanding. Regardless of this, if there is universal expansion in some way and the direction that the universe is expanding is every direction, would that mean that the universe is expanding like a sphere? | Physics | explainlikeimfive | {
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"Here's a 2D example. Take a semi-inflated balloon. Glue a bunch of pennies on the surface of the balloon. The 2D surface of the balloon is an analog to our universe. If someone starts blowing up the balloon even more, each of the pennies is moving away from each other, and the surface area of the balloon is expanding. From our 3D perspective, we can see the shape of the balloon. But if your entire universe is the 2D surface of the balloon, it doesn't really have a shape. It just is. And somehow, it's expanding. You can take the same principles, and add another dimension to be our universe. The planets and stars and galaxies are all of the pennies glued to the surface of the balloon.",
"When people say that the universe is expanding in all directions, they don't merely mean *at its edges*. The universe is expanding everywhere all at once. Galaxies aren't really moving apart from one another, the space between them is expanding. If we removed that expansion from their velocities they would be practically standing still. All of the images that you see of the Big Bang show a spherical explosion, but that's greatly simplified for the masses. Remember that what is inside that \"sphere\" is *everything*. It's the whole universe. It's impossible to look at it from the outside because there is no concept of \"outside the universe\". The idea of what it looks like from the outside is meaningless. Why do all those animations show a sphere then? Well, in part because of the [Cosmological Principle]( URL_0 ), which says that the universe looks the same no matter the direction we look, and the natural way to depict that is with a sphere (and because [sphere shapes are very common in space]( URL_1 )), but that's not the way that real explosions work. Even the most perfectly packed explosions don't generate perfectly spherical shockwaves. Importantly, there would be no way for us to tell if the universe is shaped like, say, a giant chicken, because spacetime has no edges. We could be hip deep in chicken guts, but if we never see any feathers, we'd assume it's guts all the way down. TL;DR - The universe isn't expanding at its edges because it has no edges, and the concept of what it looks like is meaningless.",
"The universe is (theorized to be) infinite in extent, so it's not really 'spherical' in shape. it may be easier to think of expansion as a 'reduction in density over time.' The observable universe, however, is an expanding spherical volume. But this doesn't represent any sort of true physical boundary, so much as the volume of universe from which light has had time to reach us.",
"Not necessarily. But yes, and no. Content can expand in any direction regardless of the shape of the container, so the type of expansion should not be proportionate to the shape of it. We tend to think in spheres when it comes to the universe because when it comes to space exploration, Earth has always been the starting point, or rather our solar system, we can only explore what is going on up to a certain distance in any direction from a 360 degree starting point, this is why the famous image of ''the visible universe'' is actually in shape of a circle. There is another theory going on, in which the universe is shaped like a doughnut, instead, the cross section is still circular, but if you keep going and going and going, you will eventually end up in the place you started. Problem with that theory is... what IS in the middle of the doughnut?",
"Homer Simpson once said it was shaped like a donut and I think Stephen Hawking backed him up",
"Many uninformed answers here. The truth : we don't know the shape of the universe. The fact that it is expanding in all directions doesn't mean it's spherical. Just think about a balloon with an odd shape, you can still inflate it, and it can expand in all directions but still keeping an odd shape. Its surface is also unbounded, in the sense that an ant walking along it would never be stopped by any boundary. Now imagine this in one dimension higher (just imagine, but we can't really see a 3d surface because we can't see in 4d) : instead of the surface of a balloon, imagine our universe itself is a higher dimensional (3d) surface. We call this a 3-dimensional manifold. We know that this manifold is expanding but we don't know it's topology (it's shape : what happens to ants walking on it, what kind of path they can make etc).",
"The shape of the Universe could be anything, because it's bigger than the Visible Universe - the sphere we can see. Perhaps our VU is a small bubble in a giant loaf of universe-bread. Since it's expanding it's not going to make a difference to us. The Universe is pretty flat around here, so it could be infinite and flat, but that's not excellent evidence - only reasonable.",
"tl;dr nobody fucking knows. we just have varying skill levels when it comes to citing publications that support a difficult topic we barely understand",
"The shape of the universe is an area of active investigation. We're not sure what shape it is, but the main contenders are a sphere, a saddle-shape, or a flat plane. The shape depends on the amount of stuff in the universe. The critical mass of the universe is the amount of matter that has to be in it to stop the expansion of the universe through gravitational forces, and it's equal to the square of the [Hubble Constant]( URL_1 ), which is proportional to the rate of expansion of the universe. If the universe has more than the critical mass, it will be spherical, and will eventually stop expanding and begin to contract. If it's got less than the critical mass, it will keep expanding forever, and be saddle shaped. If it's got exactly the critical mass, it will keep slowing down expansion forever without coming to a complete stop, and will be a flat plane. If the universe were spherical, if we draw a big enough triangle, the angles will add up to more than 180 degrees. If it's saddle-shaped, a big enough triangle would have angles that add up to less than 180 degrees. If it's flat, no matter how big your triangle, the angles will always be 180 degrees. We don't know for sure what the shape is, but we do know that the biggest triangles we've been able to measure appear to have angles that add up to 180 degrees, so we're [pretty sure]( URL_0 ) it's flat, or if it's not flat, it's really, really, really big - so big that the part we can see looks flat, kind of like how looking at part of a baseball you can tell it's curved, but looking at the ground you can't tell the Earth is curved because it's so big that a small piece looks flat.",
"Nope! We don't actually know the shape of the universe, nor even its topology, nor its size. The universe is currently expanding, but not in the familiar sense of something getting bigger. And the rate of expansion is not constant; it is possible that the universe might start contracting again. To properly visualize the expansion, you need another dimension. Imagine the 2D surface of a balloon being inflated. Dots on the surface of the balloon would get farther away from each other. But there is no spot *on* the balloon where things are expanding from, nowhere on the surface that is the center of the expansion. And the same would work with a flat sheet of rubber, or the convex shape often called saddle-shaped -- that sort of expansion doesn't say anything about the shape. Unless you're more clever than I, you won't be able to visualize curved 3D space since you'd have to visualize it in 4 dimensions. However, it doesn't need an extra dimension to be curved, with math such things can be described from the curved surface itself. Fun fact about the topology (shape category) of the universe: you can measure it by measuring the angles of triangles. On a flat surface, triangles will add up to 180 degrees. On a surface like a sphere, a triangle will add up to *more* than 180 degrees. For example, on a globe you have a triangle with three 90 degree angles, the triangle formed by two lines of latitude and the equator. On a saddle-shaped surface, triangles will add up to *less* than 180 degrees. In our universe triangles measure as close as we can measure to 180 degrees, but of course we can never measure it to be *exactly* 180 degrees, and even the slightest variation would mean a drastically different universe topology.",
"How can it be shaped like anything if it's infinite?",
"Excuse my ignorance, but what does the universe expand into? Space is just infinitely vast?",
"The best explanation I've seen that makes sense would be that the universe is the 3d equivalent to the surface of a torus so that you can travel on the surface forever but it is not infinite. Although the size of the universe is bigger in light-years than the distance light has been able to travel since the beginning of the universe so you can yet see the repeat and probably never will be able to due to expansion",
"The universe was always infinite in size, but before the big bang it was also nearly infinitely dense. The big bang was the rapid expansion of all space everywhere, leaving the universe still infinite in size but much less dense. It's like you take the infinite set {0, 1, 2, 3, ...., +inf} and multiply by 10. The new set {0, 10, 20, 30, ..., +inf} has the exact same amount of \"stuff\" in it, just separated by more space. Today, the space between all things is still expanding, everywhere, all the time. e: And because this question comes up a lot: no, the big bang did not happen at a single point. e2: Why can space expand faster than the speed of light? Because this does not violate causality -no information is transmitted faster than C.",
"Not sure how accurate this is but I always imagine it as a comparison of dimensions. Since we can only see and properly comprehend 3d and below it is beneficial to choose a dimension as a demonstration 1 lower than what we use. Imagine something on a plane, up and down doesn't exist for it like it does for us. Now imagine that plane wrapped around or in the shape of a sphere. The sphere is blowing up like balloon and all the things on the balloon are getting pulled away from each other. However, to the 2d \"people\" that live on the surface, the actual expansion/shape of their universe isn't spherical at all. It's just infinite infinite in all directions (although I guess technically its looped). Now upscale the dimensions. Make the sphere 4 dimensional and the surface 3 dimensional (thats us!) So it's not really a sphere for us because we don't live in it or on it but rather IN the plane - which I guess upscaled now isnt a plane but a 3 dimensional space. So it's not really expanding in the general sense to us. The problem is we think of expansion as overall the borders getting further apart, but for the distance between the galaxies to increase (which is pretty much what the expansion is) there doesn't have to be borders. In fact, there aren't borders, just the distance between things is increasing. I'm not sure how accurate this is - because I think they actually use more complex multidimensional shapes to describe the expansion, but this analogy is a good way to understand the basics I think.",
"I don't know how technically correct this explanation is, but it at least helped me to wrap my mind around the expansion problem: Don't think of the universe as expanding or stretching, because that conjures up all kinds of imagery of something pulling it apart from the edges, or that there must be some space \"outside\" the universe for it to expand into. Instead, think of it simply as the metric we use to measure distances constantly shrinking. If I give you a ruler and tell you to measure the distance between two objects, you'd give me some number. If I then gave you another ruler that was identical in every way, except that it was shrunk down by 10%, markings and all, a second measurement would return a number 10% larger than the first. If you trusted that both rulers I gave you were legitimate, you might conclude that the two objects had moved away from each other. The universe is like that, except all the rulers everywhere are constantly shrinking, and doing so at some impossibly slow rate. At short distances it doesn't really make a difference, but the longer the distance you have to measure the more relevant it becomes because the shrinkage is proportional to that distance, i.e. two rulers end-to-end lose twice as much length overall as one ruler by itself over the same time frame. So assuming a meter is always a meter (why wouldn't we?) and taking a bunch of measurements of shit in space, the result is that everything appears to be moving away from everything else, no matter which direction you look, because length itself is getting shorter, while all the galaxies themselves stay put, so 10 light-years gradually becomes 11, then 12, etc. There is no need for an edge or an \"outside\" of the universe, or any weird forces pushing galaxies around, all that's required is some mechanism by which a spatial metric can change it's length. I was under the impression that relativity and all that jazz means that space-time expanding around a constant meter is equivalent to a meter shrinking within a constant space-time, but if anyone has a more thorough explanation, I'm all ears!",
"I honestly don't know how the torus/donut universe has become so popular in this thread, it really isn't a part of the standard cosmological picture as far as I'm aware. The answer is that General Relativity allows for a universe where parallel lines converge (like lines of longitude do on the surface of the earth) or where parallel lines diverge (not a simple example of this shape, but it's usually drawn like a pringles chip or a saddle). Or parallel lines stay the same distance apart forever, a 'flat' universe. Furthermore, we assume no where in space is any more special than anywhere else. An edge of space would certainly be a \"special\" location (why does the universe stop there? What does it mean to stop there?) So we assume, without proof of course, that the universe has no edges or borders (and consequently, no center either). If there's more mass than energy (of motion) in the universe, then \"gravity\" \"wins\" (to abuse the words both gravity and win) and parallel lines will eventually converge over very long distances. Thus, the universe doesn't need to have any edges because any direction you travel, you always wind up back where you start. If there's a balance of mass and energy, or more energy than mass, then the parallel lines don't converge, and may even get further apart, and the universe must be infinitely large if it doesn't have an edge. We measured parallel lines in our visible universe (as best we can, at least) and found that they seem to neither converge nor diverge, so... the universe seems flat. And thus infinitely large. There are still error bars associated with that measurement, but the overall result of our data is that the universe's curvature is *suspiciously* close to zero. Like if it's not exactly zero, we have a real question on our hands of \"why is it so close to, but not exactly, zero?\" Which is a question that has come up elsewhere in physics as well (like the mass of the neutrino). Maybe future answers to all these questions will tell us why it *must* be zero or explain why some other thing knocks it slightly off of zero. Anyway, to circle back around to the toroid/donut: Toroids have zero curvature, but are finite in size. If you really really hate the idea of an infinite universe, but want to fit your finite universe assumption to our zero curvature data, you might pick a toroid. But I think this breaks the principle of fewest assumptions since, to me at least, the shape of a toroid is a more complex assumption than the simpler shapes we've historically assumed (sphere-like, plane-like, saddle-shaped)"
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7gotk7 | How does any number to the power of 0 equal to 1? (5^0 = 1) | Mathematics | explainlikeimfive | {
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"Start with some givens: x^1 = x x^2 = x * x x^3 = x * x * x Every time you increase the exponent, you're adding an X to the list to multiply. So x^2+1 = x^2 * x If adding 1 to the exponent is the same as multiplying by the base (x), then subtracting 1 from the exponent is the same as dividing by the base. x^1 = x x^1-1 = x/x x^0 = 1 (because any number over itself is 1)",
"Let's use three as an example. 3^1 is 3, 3^2 is 9, and 3^3 is 27. To go up by one factor, you multiply by three. To go down by one factor, you multiply by 1/3. To go from 3^1 to 3^0, you multiply by 1/3: 3 * (1/3) is 1. This is also the principle behind negative exponents- to go to 3^-1, you again multiply by 1/3: 1 * (1/3) is 0.3 repeating. This works with all other numbers, too. Once you figure out the pattern, you can just follow it backwards.",
"Consider what happens when you divide powers. If the base is the same value, you simply have to subtract the exponent. For example, 5^3 ÷ 5^1 is basically just 5^3-1 or 5^2 . To put it in expanded form, 125 ÷ 5 = 25. & nbsp; Now, consider what happens if you divide the same number by itself, say for example 5 ÷ 5. This can easily be rewritten as 5^1 ÷ 5^1 since all numbers are the base of an exponent of 1 (all numbers are itself multiplied by 1). & nbsp; 5 ÷ 5 is obviously 1, and thus 5^1 ÷ 5^1 must also be 1. Now remember the rule about subtracting exponents. Due to that rule, 5^1 ÷ 5^1 becomes 5^1-1 which becomes 5^0 . But we've already deduced that 5^1 ÷ 5^1 is equal to 1. Therefore, 5^0 must also be 1."
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7gp015 | How do turf farmers reset their fields after harvesting? | Other | explainlikeimfive | {
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"Do you mean grass / rolled sod? Not really called turf where I live but I own a small landscape company and I deal with multiple suppliers here. They tend to be massive fields, and after the sod is cut (top 2 inches or so) they bring in truckloads of manure and organic fill, use huge tractors to rototill the soil and mix it all, then a special machine attachment to regrade everything smooth while applying their own brand of grass seed. It takes about 2 years for the field to grow sufficiently to harvest again.",
"To add to what skoguy said, some places engage in the practice of soil sterilization that involves either forcing steam into the ground or using heavy duty fumigants such as methyl bromide. Pretty neat stuff, farmers will wrap the entire field in plastic (imagine the biggest god damn roll of saran wrap you've ever seen being pulled by a tractor) and then pump it full of heavy duty fumigants. This and steaming are fairly common practices, especially on fields known to have soil-borne diseases. Steaming is a bit different and more energy intensive. There are several methods, one of which involves a large plate thing with [sharp nozzles attached to tractors that inject steam]( URL_0 ) as far down into the ground as possible. (I guess that's not really 'attached', more of a single purpose vehicle) Sidenote, methyl bromide is super fucking nasty stuff and there have been huge efforts to reduce its use. Steaming is becoming the more popular option these days. Edit: [Here is a good article on soil sterilization]( URL_1 )"
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7gplvj | How do snakes move? | Biology | explainlikeimfive | {
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"There are four snake movement schemes: serpentine (slithering), concertina, side-winder, and reticulation. The bottom of a snake has little grippers which hold the ground, and the snake lifts or moves parts of its body while pressing down onto the ground with other parts of its body. Not all snakes use all schemes."
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7gpq9r | How does a company get its product's code in the product? | I'm not terribly familiar with coding. I kind of understand it, but I'm still confused how, when you code something like Siri on a computer, how is the coded material put into the Iphonet? I hear people say they write code, but how is the code they wrote put into different products? | Technology | explainlikeimfive | {
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"by uploading it into the device's memory. physically same process as you uploading your music from your itunes on desktop to the iphone. except....apple's new iOS code gets loaded in at the factory thru a special loader.",
"Code is written in a \"programming language\". Think of it like a dictionary, it tells the device the meaning (function) of each term (code). Different devices use different languages. There's hundreds. It's easy to teach a computer a new programming language, you just have to upload the correct information. You can write code for almost any device, in almost any programming language, using a properly configured computer. You can also make a computer act like almost any device, through a process called \"emulation\". You can make your computer act like a cell phone, or a Nintendo, or even a car! So: A programmer uploaded the iPhone programming language onto a computer. They installed an emulator, that allows the computer to act like an iPhone. They wrote the program for Siri in the appropriate language, and tested it using the emulator. Once complete, the code was compiled into a single program that an iPhone can install. Any product running the correct programming language can run that program. The programmer will have to re-write the program in a different language to work on devices that can't use that programming language."
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7gpy4t | Airflow with a Verticaly Mounted GPU | In my [computer's case]( URL_0 ) I have the option to mount my graphics card vertically as shown in the picture with about 7mm of room between the side panel window and the fans of the card. I did this with my old GPU and it ran about 20 degrees warmer than the normal horizontal mount directly into the motherboard until it died. My question is about how fans spinning at the same speed can cool less efficiently in different configurations? "How can a fan pull less air at the same speed" is what is going through my head. | Physics | explainlikeimfive | {
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"If the card is against the side window, it's not receiving as much cold air from the front case fans as it is just recirculating the hot air it puts out. It's not pulling less air, it's just pulling air from a different source and in the case of coolers like the one in the picture, which most manufacturers have moved to rather than the old shrouds, the hot air gets blown out the sides of the card rather than the back, so the fans will draw it right back in."
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7gq3qy | Why is it cheaper to buy the digital copy of a movie than a physical copy but it is about the same price between digital and physical copies of the same game? | Economics | explainlikeimfive | {
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"Short story: because their publishers have decided that that's how they can make the most money out of their product. Long story: because of a combination of the nature of the market, history, inertia, competition, greed, and brazen exploitation. Movies make the most money at the box office. Take Toy Story, for example: URL_0 It made 191 million at the box office, and a paltry combined 97 million DVD + Blu-Ray. That's not even adjusting for inflation, which would widen the gap considerably. So the timing of when a movie is released to DVD is carefully timed such that it won't affect box office sales, but while people still want to watch it. After all, what people really shell out for is to go to the theatres. Selling discs and digital copies is just a way to squeeze more money out of the product. It costs less money to produce a digital product, you have to stay online to stream it, you can't bring a digital copy to a friend's place, & c.- people know these limitations, and so they're willing to pay less for a digital copy. Publishers want to maximize sales, so they sell the digital copy for less, which results in more sales, and overall more profit, since it costs you nothing to put out a digital copy. On the other hand, a video game is different. Companies have noticed that gamers can **and will** pay money to pre-order their games. They want them on day one. They will wait in line and pay 5 times the list price for a game in high demand. And publishers are in full control of the demand. Nintendo knows this, but bless their souls, doesn't sell games for a higher price- they just control the supply to build up hype. What's a good publisher going to do? Milk it for all it's worth. Preorder bonuses, preorder DLC, deluxe editions, all the bells and whistles. They know gamers will pay for these things, so they sell them. Basically, when demand is so great and they are the only supplier, they can get away with exploiting their consumers for a good long time. And that means that while people are willing to pay as much for a digital copy as a physical one (we'll soon see them costing more for the \"convenience\"), they will be that expensive. That's why after a while, games do get cheaper. When demand has lessened, they start to compete with other games on their merits alone. True classics stay expensive (and may even stage a comeback- look how expensive old Final Fantasy games are on Android!) while games that are really bad get really cheap (your $2 Steam bargain bin). All these strategies are aimed at maximizing profit. When there's no demand, you have to lower your price to increase sales."
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7gq6dg | When people take prescription drugs like Adderall and Ritalin why do they have no appetite? | Biology | explainlikeimfive | {
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"Individuals with ADHD have low dopamine levels flowing in their brain, and dopamine helps us with motivation, planning, satisfaction w/ doing work, etc. The goal of these medications is to cause more dopamine to be released from its storage places in the brain. Unfortunately, dopamine is stored in the same little \"pouches\" in your brain cells as epinephrine, which is adrenaline. When stimulants like Adderall or Ritalin reach your brain, they release dopamine *and* adrenaline. This means we accidentally set off the \"fight or flight\" response. That response shuts down functions you wouldn't need in these adrenaline-fueled situations, including digestion. As a result, you're not hungry at all."
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7gq8m3 | Why do we need to file taxes? | Economics | explainlikeimfive | {
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"The deduction from your paycheck is based on a guesswork estimate of how much you will owe at the end of the year. However, there are a lot of things that can happen throughout the year that can change how much you end up owning. Buying a house, for example, kicks in a lot of tax credits that wouldn't have been predicted by the estimate. So at the end of the year you fill out a tax return, to find out if you have paid the government too much or too little through your paycheck deductions. If you've paid too much, they send you a *tax refund*. If you've paid too little, you have to pay.",
"Some people get money from things that don't produce paychecks. Investors might buy an old house, fix it up, and then sell it. There is nobody taking deductions or withholding taxes there. The tax system has to be very general to handle all these complicated cases.",
"What you describe is how taxes work in many countries. Taxes are taken automatically and you're done. In the US you can file a return and, if you were overcharged, *get that part back*. It is pretty much your responsibility to make sure you don't *under*pay. *Could* it be automatic? Probably, and a lot of it is. At this point (you my have heard) our tax system is immensely complicated and needs a huge overhaul.",
"> AFAIK income tax is automatically deducted from your paycheque This is usually correct. However, the amount of taxes you are required to pay can vary based on many things, e.g. having kids, owning a home, owning a business, donating to charity, etc. Your employer isn't going to do your finances for you so it just deducts a standardized amount for taxes. You are legally required to file your taxes in case the standard amount is lower or higher than what you actually paid from your paychecks. Some employers also do not deduct from paychecks for a number of reasons.",
"When you earn money from a regular paycheck, an **estimate** of the tax you owe is withheld. Your tax return is where you go through the accounting of how much tax you actually owe, you compare it to the estimate that was withheld, and you settle up the difference (or have the difference paid to you). Why might the estimate of taxes you owe be inaccurate? Well, the first is, you can change the estimate. You can tell your company how much to withhold on your behalf. The second reason is, not all your income comes from your regular paycheck. Some people don't draw paychecks. Other people get paid cash. Other people have lots of investment income, or other types of income. Some people get big bonuses at the end of the year that they didn't predict. And the third reason is that the tax you owe isn't just based on your income, it's also based on other life circumstances like: * education costs * medical costs * how many kids you have * whether or not you have a mortgage and how much you pay * whether you had investment losses in previous years ...and hundreds of other things."
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7gq9fl | How does a 50 lb child make so much more noise walking around the house than a 200 lb adult? | Physics | explainlikeimfive | {
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"Maybe it's the way the walk. Usually adults walk more deliberately, with a rolling step. They don't put 100% of the weight on the ground, where kids tend to stomp more. I don't know anything, this is just a guess",
"By not caring how much noise they make. Adults are more conscious of their effects on their environment, and more polite.",
"Adults have had years to perfect their stride, making it as energy efficient as possible. Children, however, are pretty new to this whole bipedal thing. Their technique is quite a bit more energy consuming because they haven’t perfected the efficient stride. Sound is a good general indicator of how efficient or how much energy an action uses. See: knife skills, tires, jet engines, speaking, etc To expand on the whole “technique” thing: Walking is meant for you to expend the least amount of energy possible to keep you up so that the rest can go into moving you forward. This requires balance, skill, technique, and experience. A child is just trying to stay up because they’re, well, a child. So it’s more stompy, and therefore more loud. It’s like when we travel on stairs: it’s more loud because more of our action is going into moving us vertically than horizontally."
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7gq9ps | If the universe is always expanding, are new planets/stars/moons coming in to existence to fill the space? How does this happen? | Other | explainlikeimfive | {
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"No. The idea that new matter is created to fill space is called the [Steady State Theory]( URL_0 ), which has been rejected by the majority of astronomers. Instead, things just get further apart as the universe expands.",
"New stars, planets, and moons are forming all the time. However, they are not forming in order to fill the space of the ever expanding universe. Things are just getting farther and farther apart."
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7gqdm7 | How do scientists split atoms? | I still don't get it. How does one actually get something that can cut an atom? | Chemistry | explainlikeimfive | {
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"you dont \"cut\" them you more or less smash into them until they fall apart. Less knife more sledgehammer. Large Atoms like Uranium 235 are already inheritable unstable. Almost like a jenga tower that is way too tall. We launch a Neutron into the the nucleus which is almost like adding another layer on that massive jenga tower. Once we do that the entire thing comes crashing down. The really nice thing is that once a large atom like uranium 235 splits it shoots off neutrons out and those will hit other 235 atoms and you get a nice little chain reaction of nuclear fission.",
"They are not cut with a knife-like action. They are smashed by having a small particle run into them at high speed.",
"The pieces of an atom are held together with large but finite forces. A supercollider accelerates atoms in opposite directions to almost the speed of light and then makes them smash into each other with some very powerful magnets. As it turns out, even single atoms break if you hit them hard enough, like if it hits another atom traveling at almost lightspeed in the other direction.",
"Smack that bitch with a neutron. If it's unstable, you can split it. Nuclear fission a la \"The Bomb\" works on this principle. U-235 gets slapped with a neutron and it breaks. I forget the products, but you get a 3 neutrons as well. So if you get enough 235 in one place (critical mass), the neutrons keep breaking more uranium and you get more neutrons, until you get a big boom. Edit: Fusion--\\ > Fission."
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7gqmdn | After signing the Declaration of Independence, how did such a small group, the first government officials, go about convincing inhabitants that they were now living in the United States of America? | Other | explainlikeimfive | {
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"The Revolutionary War had already been going on in earnest for a year. People were literally shooting the British authorities and soldiers. So it didn't take a document to convince people something was up. That said, many were *loyalists* who sided with the British and did not agree with the Declaration or the revolution. They were convinced only when the British lost the war -- and even then, some felt it was wrong, and some even left the country.",
"The founding fathers weren't just a small group of individuals. They were delegates sent by the governments of the states. Thomas Jefferson was acting on behalf of the government of Virginia, Franklin was acting on behalf of Pennsylvania, etc. It wasn't just a case of a few influential individuals who declared independence, it was the already established and legitimate government of 13 colonies that declared independence."
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7gqv21 | how do organ transplants work, specifically a kidney | I know someone who had a kidney transplant today and apparently the doctors said it started producing urine immediately after being translated and it just blew my mind for some reason, like how does the body know to do that with someone else’s kidney how does it send that signal after being cut apart and replaced I’m so confused | Biology | explainlikeimfive | {
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"> the doctors said it started producing urine immediately after being translated Producing urine on the operating table just means you've successfully hooked all the tubes up. I think part of your confusion comes from your understanding of how the kidneys work. Kidneys are basically glorified filters. Blood flows into them, some stuff gets filtered out as urine, and then the rest of that blood flows out the other side. As long as you get all your blood supplies hooked up and then link the new kidney to the bladder, it's gonna start making urine. The kidneys **do** respond to chemical signals in the blood for adjustments, which they'll do regardless of whose body they're in -- but the recipient's body doesn't have to instruct the kidney to do anything."
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7gr5kk | How can professional kickboxers and MMA fighters be able to hit things with their shins with so much force? | So i just saw this on twitter URL_0 this lady his using the middle of her shin like its not attached to her body, if i bang my shin i am in agony yet these people can use their shins as a weapon without as much as a crack to the bone or a whimper How is this possible? | Biology | explainlikeimfive | {
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"Its all about conditioning the shins, essentially numbing the nerves and bone, so that the nerves die and you become used to the inevitable pain at the same time There's a great post [here]( URL_0 ) that explains: > There's basically 3 factors from my point of view. Your own pain tolerance to start. You can pretty much do anything to me short of the obvious ones (jam shit in my eyes, kick me in the beanbag) and I'll be okay. My pain threshold is pretty crazy as is so that certainly helps. As time goes on your body gets used to what you're doing and you get more durable, things get more tolerable. Like exercise right? First time you do it it's hard, your body strains, you really suck at it and everything aches. Then a month later your routine isn't as hard. Six months later hey I'm halfway decent at this and I can walk fine the next day, that kind of thing. Three is your body itself is helped by factors and I'm not a doctor so bear with me but you do deaden the nerves in your shin one way or another really. We had drills to kick wooden posts, we got whacked in the shins with stuff (to varying degrees not like some guy full force drove a cricket bat or something into us and we had to take it) and your friend adrenaline also helps out as it does with any contact sport. If you've ever played a physical sport like hockey, indoor lacrosse, American football, rugby etc you tend to get hit in those sports and you don't really notice unless it's a huge impact. After the game you check yourself out and you have bruises and stuff you never felt when they happened. So your body toughens, your shin bones get stronger, your nerves kinda fuck off and you get more used to hitting and getting hit."
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7grbgp | How do eagles & owls have better vision than humans? Do they see everything in incredible detail all at once, or do they have super great focusing powers that act like a zoom in camera lens? What specifically is better? How is this measured? | Biology | explainlikeimfive | {
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"They have better acuity, sorta related to resolution in a camera, but they also have higher magnification. They have to swing their eye over a larger range to see the whole world, but they see it at slightly higher magnification. Not exactly like binoculars, but a similar effect."
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7grfn9 | A river running over millions of years eventually create a valley or in extreme cases the Grand Canyon. Why are there not more examples of extreme canyons? | Other | explainlikeimfive | {
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"Making a canyon like the Grand Canyon requires a fast-moving, narrow river running over the right kind of rock. Rivers running over softer soils carve out huge valleys instead. The Mississippi River Valley is dozens of miles wide for most of the river's length."
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7gs0ws | What is "blue light" and why does filtering it on my phone help protect my eyes? | Technology | explainlikeimfive | {
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"The most important thing about filtering blue light from your electronic devices is that blue light keeps you awake at night. Light signals your body to stop the production of melatonin and destroy the melatonin in your body, and blue light is the most effective at causing this. Melatonin signals the rest of your body to sleep and gives you that sleepy feeling. Filtering out the blue from your phone screen and computer monitor helps prevent sleep disorders because it helps prevent those devices from falsely signaling your body to stop producing melatonin."
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7gsb6z | Why does “turning it off and turning t back on” fix so many problems in IT? | Technology | explainlikeimfive | {
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"Every complex system has something called 'state' - the current status of all the various elements in a system. Consider a chess match. When you begin a chess match, it's in a fixed state - all the pieces nicely lined up in a specific order on their side of the border. As the chess match proceeds, the state becomes more and more muddled - until you finally reach a state where one side is no longer able to make a legal move. Computer systems can also work the same way. They can potentially work themselves into a state where there are no valid moves to make. Just like with the chess match, starting over changes the state into a known good state from which operation can continue."
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7gsc3u | Why does sugar make things less spicy? | From what I know, spicy isn't a flavor so much as an irritation that we enjoy for some reason, so why would sweetness (a taste) effect how spicy something is? | Chemistry | explainlikeimfive | {
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"Sugars, breads, and a protein found in milks, actually kick capsaicin off of your taste buds and take its place. Since capsaicin is the tricky little bastard that makes your tongue feel like its on fire, they effectively put the fire out.",
"Sugar and capsaicin ~~are both *nonpolar* molecules, and they~~ like to bind together. After capsaicin is bound to sugar it can't bind to the receptors that let you taste spice, so it cools the burn. Milk does the same thing, but with the addition of fats (which are also nonpolar)."
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7gsrj9 | In the English language, why do we say, “Give her her stuff back,” but not “Give him him stuff back?” | Other | explainlikeimfive | {
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"Because \"his\" is the male possessive for \"him,\" while \"her\" is the female possessive for \"her.\" It's irregular."
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7gt7iy | How sometimes people don't feel that they've been cut? | Biology | explainlikeimfive | {
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"There's nothing at the injury site itself that hurts. It's all in your brain. Nerves at the site of the injury send signals up about what's going on, and then the brain sorts it out. The brain actually integrates a ton of information very quickly, including memories of past \"pain\" signals in particular locations and the consequences (severe injury, major illness, nothing particularly bad). It also integrates what you're doing at the time, and in the instant, it seems to dampen pain perception so you can make sure you're not in further danger. It also changes over time and can hurt later, when you're reliably out of danger, so that you take care of the area and don't use it so it can heal and avoid further injury. Pain is essentially your brain's opinion about what's going on with your body. It can be seriously out of step with the actual state of damage of a particular area."
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7gtgqq | When doing heavy excersise\lifting, why do we stop breathing? | Biology | explainlikeimfive | {
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"> When doing heavy excersise\\lifting, why do we stop breathing? Tensing the muscles of the core will provide extra rigidity in the torso and can aid in whatever physical exertion you are attempting, but of course this makes it impossible to breath properly. It is a trade of breath for core strength.",
"This technique is called \"bracing\" in weightlifting. When lifting heavy weights, you want your core to remain stable, so that your back doesn't get twisted and thrown out. To do that, you engage your abs and back muscles to create a very solid core, and that greatly helps with protecting your back. Holding your breath creates air pressure in your abdomen, and this allows your muscles to press in against something, creating more tension and support than simply tensing those muscles would provide. If you look at professional powerlifters, they lift their heaviest weights with a belt on. That belt is tightened (not too tight! You still need some air) around the abdomen so that they can brace against the belt. With air pressure inside their body and the belt holding the outside, the resulting support is very strong."
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7guqi3 | Why does milk help relief spice? | Ate a chilly today and drank milk and next second my mouth isn't burning. | Chemistry | explainlikeimfive | {
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"Because capsacin, the thing in chilies that you experience as heat, is an oil. The fats in milk combine with capsacin to neutralize it. Drinking water doesn't help because the capsacin resists it. But you could just as well drink butter or anything else fatty."
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7guzb6 | How Do credit Cards work and whats the best way to use a credit card? | Economics | explainlikeimfive | {
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"In very simple terms: When you apply for a credit card the bank will assess your income, assets, etc and decide on a maximum amount they are prepared to lend to you based on what they think you will be able to pay back. This is the credit limit on your card. Then rather than give you all this money in one hit, they give you a credit card which allows you to take out a series of small loans (each time you buy something with your credit card) until you reach that limit. You are then going to be expected to make a minimum payment of your card each month and will be charged interest on whatever remains outstanding (plus a fee - but the fee is usually charged annually rather than monthly) The best way to use a credit card is to not use it The second best way is to only use it for purchases you can afford and pay back the total balance each month before your interest in applied. The worst way is to max it out and pay a crap load of interest each month on what you still owe."
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7gv0dt | What is that weird smell that comes off old guitar strings? | Chemistry | explainlikeimfive | {
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"Rotting skin and sweat stuck in the itty bitty cracks of the strings. Most strings are a material that doesn't rust or oxidize, like silver or stainless steel. That'll have a bit of a metallic smell, but everything else is leftovers from the player.",
"[Iron, copper, and brass are odorless, but they react with skin oil to produce a unique smell that we identify as \"metallic\"]( URL_0 ) Guitar strings get skin oil smushed into them for hours at a time, they will produce a lot of these smells."
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7gvagn | Tax write-offs for donating to charity. | Economics | explainlikeimfive | {
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"Not quite. If you donate $100 to charity, you subtract $100 from the income you declare to the IRS, so you owe fewer taxes. So instead of paying income tax on $50,000, you’d only be taxed on $49,900.",
"Another thing to keep in mind when donating is to see what you get out of it. For example, I buy a one year membership to the Academy of Science. This membership is tax deductible. I get to visit as often as I want and get a tax write off, they get money.",
"If you spent $100 on Pokémon cards, you’d have paid 25% tax on the money (or whatever your tax bracket is) to buy them. So you actually need to earn $133 to have $100 left to buy the $100 good. If you made a $100 donation to a charity, you can deduct $100 from your taxable income, meaning you don’t pay tax on that $100... so it effectively costs you $75 to make the $100 donation, because of the tax savings. Or a $133 donation would effectively cost you $100. You don’t save overall money, but save on your tax obligation.",
"Usually you are correct. It's mostly a meme that charity donations are tax write-offs. You might lower your taxable income by $100, but you're still out $100 (though it's probably gone to a good cause), and you might be saving only $5-10 in taxes. Most of the concern/criticism comes from the mega-wealthy that donate vast amounts of money to charities that they own and control, that may or may not be doing actual charity work. In those cases it looks like they're simply moving money around to get out of paying their taxes. In the case of people like Bill Gates this isn't true, and his charity does a lot of good work. In the case of other, less notable billionaires, it might be a dysfunctional or shell charity that exists just to redistribute money back to their friends."
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7gvuv4 | password keepers | Technology | explainlikeimfive | {
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"I'm assuming you're talking about apps like LastPass and 1Password? The idea isn't that they're more secure than *typing in your password*, it's that they're more secure than *other* methods of keeping your passwords (like writing them all down on an index card and keeping it in your purse or wallet, like my mom does). If your master password is secure but memorable to you, it is a relatively safe way of storing a multitude of other passwords that you might not otherwise remember on a day to day basis. It's more secure because you can use a different password for every account without having to remember them all individually (rather than using the same one or two passwords for everything, which is a security disaster)."
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7gvxoq | How does sleep restore the body's energy? | If energy can't be created, then why does sleep boost us back to 100% every morning? If I don't plug in a laptop and I put it in sleep mode, it just drains battery less quickly. If it's from food, why does our body wait until sleep to convert it to energy? | Biology | explainlikeimfive | {
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"It's from food, and the body doesn't wait until sleep to restore energy. This is why a workout or athletic activity feels so much easier a few hours after a meal rather than on a starving stomach. What sleep restores is not your energy, but your brain function. Your brain is floating in a nutrient soup called *cerebrospinal fluid* or CSF. Throughout the day, your brain cells drink in nutrients from the CSF, and spit out waste. This builds up, and by the end of the day there's so much waste floating around in the CSF that it starts negatively affecting brain function. When you sleep, channels open up and flush the day's supply of CSF away. New, clean CSF is pumped in for tomorrow, and so you wake up with a clean brain.",
"Your brain continuously creates something called adenosine while you are awake. This keeps you energized and ready to do anything. The more adenosine your brain makes, the more it has to carry, and sleeping is the only way to get rid of it. The more it carries, the more it gets tired. Your brain also has an alarm clock called a 'circadian rhythm' of when to do certain things at certain points in the day. Let's say it's night time, your brain is carrying way too much adenosine, luckily the 'circadian rhythm' tells the brain it's time to sleep. Because it's sleepy time, your brain creates something called melatonin. This makes you comfy, mix that with being tired from all of the adenosine and you get sleep. During sleep, your brain starts putting away your memories it was holding throughout the day away into a library known as your long term memory (REM Sleep). This is when you dream, usually it's associated with whatever your brain is putting away. Your brain is also firing old bad cellular workers and hiring new good ones that are ready to work. Meanwhile, your body's cellular workers destroy the adenosine while making important fixes and adjustments to the body. When the circadian rhythm says it's time to wake up, your brain stops making melatonin. You have no adenosine so you feel tired, but this is also an incentive to wake up since your brain is satisfied that the adenosine and melatonin is gone. Your cellular workers fixed any problems they saw so your body also feels good. You do gain your energy from foods mostly as types of sugars that are fed to the little cellular workers in your body. Because your body is always working, you will always be converting food or fat into sugars to feed your cells.",
"No one knows, we only have theories at this point in time. Theoretically theres no evidence we need sleep. But we know thats not true."
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7gw83s | What Ant Decides When A Colony Is To Be Moved? | Biology | explainlikeimfive | {
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"No one ant decides to move. Instead, when an ant thinks the colony needs to move, it goes out scouting for a new home. If it finds one it likes, it comes back to the nest, lays down a phermone trail, and brings another ant to check out the new nest. If _that_ ant likes it too, it will go back and also lay down a phermone trail and bring a new ant to check out the place. If it doesn't like it, the ant will just go back home. Eventually, if the number of ants desiring to move to the new place gets big enough, the whole colony will migrate over. Ants may move if their old home has been damaged, or if they've just outgrown the space available, or various other reasons. Here's a write up about an experiment that this info comes from URL_0"
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7gwail | Why does human skin often have a luminous/poreless/non-greasy quality in childhood, but then lose this quality right when physical attractiveness starts to become a lot more important in the teenage years? | Biology | explainlikeimfive | {
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"Children phyioslogy is hugely different from adults. Children skin cells are plentiful, regenerate rapidly, and have no accumulated mutations. These traits fade with age at different rates for different people. Essentially the traits you find attractive are side effects of a human rapidly growing. When the growth slows down so do these 'perks'. The attractiveness likely evolved as a behavorial trait to help choose a fit mate. Edit: in regards to oiliness/greasiness, sebaceous and suderiferus (oil and sweat) glands are less active until the kid hits puberty, when they crank into overdrive.",
"Always think of these types of things in terms of primitive man (who we’ll call “Todd”)as a way to get yourself thinking about why over thousands of years our bodies have evolved to what they are. It was more important for bear skin wearing Todd to hit puberty and be strong to hunt and gather and be horny AF to spread his genes and create a retirement plan. Unfortunately, the same hormones that increase during puberty to allow for these valuable traits also increase glandular production (ie, pimple time). But Todd didn’t have instagram or other societal ideals so his pimples weren’t holding him back as a mate.",
"Hormones. Adults have 'em, kids not so much. Teens have MORE, which explains some of the issues they have that other people don't. Actually, babies also tend to have little hormone spurts as their systems come online, so it's not unusual to see some baby acne or whatever, though it tends to be short lived.",
"Note: for the exposed skin (face, hands and feet) keep moisture levels up, as these areas dry out and crack, peel, shed more than others. If your face out, gets wind/sun burned you are going to prematurely age... if you like the old weathered cowboy look, do nothing. If not, you need to moisturize daily. Children’s skin has a high water content - adults tend to lose this as they age. But some seem to stay young looking (ever heard about some people whose face’ don’t crack’ - that’s likely Shea Butter at work) Shea butter (pure) is excellent for daily use - Vaseline and Aquaphor can be helpful for dry-chafed skin."
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7gwia9 | Why is finding "patient zero" in an epidemic so important? | Biology | explainlikeimfive | {
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"How did patient zero get the sickness? Who has patient zero been in contact with? The first question helps to guide efforts to prevent. The second question helps guide efforts to contain.",
"It depends on the epidemic. For rare diseases that pop up now and then, like ebola, this was important because people wanted to know where ebola was coming from. Years could pass without a single known human having it, so it was coming from the environment, likely some kind of animal. After finding out \"patient zero\" for ebola outbreaks, you can look at where they lived, what they did, etc. to identify likely candidates for animal hosts, and then go into the wild and collect those animals to see if they actually have the virus. If they do, then you can now warn everyone that this is how you get ebola, so they know to be cautious. Studying diseases that can jump species barriers can also potentially teach us about which diseases might do this in the future, so we can be prepared just in case it happens. If *very* little is known about the disease in question, tracing the path of transmission can tell you how the disease is spreading. Is it airborne? Does it live in the environment, or only within hosts? How long can it survive outside the host? Does it even spread from person to person, or were all those infected exposed to the same source, rather than one passing it to the other? Legionnaire's disease is like this, it DOES NOT spread from person to person, it spreads through inhaling contaminated water vapor. So if a group of people get it, we can look to see what water sources they've been near, so that we can stop any more people from being infected by that source. Edit: **For more information,** I recommend [this book]( URL_0 ) on a cholera epidemic in London, where epidemiological techniques were first pioneered. . . by a guy named John Snow. No, really! Here's a [Youtube series]( URL_1 ) on the same topic.",
"If you want to stop an epidemic it's important to know how it started. For instance, there was a cholera epidemic in London in the 1800's that was eventually traced to a single contaminated public water pump. Shutting down that pump stopped the epidemic. If you have an epidemic that is spread person-to-person, finding the source can help pinpoint the root cause, so that you can stop it at the source.",
"Biocontainment team member here. Helps to find out who has it, who the disease may have spread to and came from. Say you had a person from Sierrea Leone that was Ebola positive, we'd have to know if they took a boat or plane, did they take a direct flight or did they drive after landing? If they drove did they use a taxi or drive alone? Is the patient wet or dry? (Are try actively vomiting/sneezing/bleeding/diarrheaing or are they just experiencing initial signs and symptoms) gives us an idea how sick others may be. PROTIP: don't go to a hospital and pretend to have Ebola, we lock your ass down. I think it's our safety measure to have you masked up within 5min, isolated within 7, and have EVS follow your walking path with a bleach mop.if you are just at a random hospital you will be sent to an assessment site to be evaluated if your hospital isn't.",
"One more important thing to note is that the disease samples of P-Zero are likely to be the original mutagen. Considering how diseases adapt themselves according to the host or environs they find themselves in, it is important to know what the original structure of of microbe looked like. That way it is possible to simulate the possible mutations and find a base counter to all of them. If that isn't possible, then one needs to try out different vaccine strains which cost a lot of time and money.",
"Trying to find a cure for an illness is very difficult, trying to cure or treat it is like feeling around in the dark. For that reason, two things are very important in developing a cure/treatment: patient zero and resistant/carrier patients. Patient zero helps give you a better idea of where it came from and how it is communicated. Knowing these things also helps you understand who's most at risk and how best to limit infection. Resistant carriers are the most critical because they help you determine how the body can fight off the infection, and they tell you what kind of reaction you need to artificially create in the body to help fight it off.",
"It means that the carrier is transmitting the infection, but still alive. Patient zero has active antibodies that are combating the infection/keeping him alive. Finding patient zero is valuable because you can harvest the antibodies to find how it is combating the infection and produce a vaccine/cure from the antibodies.",
"Understanding how the first person came to have a disease helps contain further spread for comunicable ailments. But it also helps track a path that the person with the disease has taken since they acquired it which demonstrates the possible exposure to others so bodies like the cdc know where to expend man power. Quarntine procedures and the like are very costly.",
"Relatedly... Why are they called patient 0, and patient 1?",
"It's understandable that humans get diseases from other humans because the infectious agent can adapt to the new host easily, but it's important to find patient zero because that person most likely contracted the disease from a natural reservoir (animals or plants). This natural reservoir and the corresponding pathological agent needs to be identified and contained as soon as possible. Natural reservoirs are important to identify because even if humans have developed complete immunity to a particular pathogen, the disease lives on in animals that may be unaffected by its effects. Who knows when it might make a comeback. Armadillos for example, carry leprosy.",
"Microbiologist, here. My background is in Bioterrorism Response. Patient Zero is mostly used in movies, frequently, because they are often talking about crazy fast mutating viruses. One core concept is genetic drift, which is essentially looking at how different the infectious agent is from how it started. In simplest terms, it’s like a game of “Whisper Down the Alley,” the more people are involved, the greater chance there is for it to have changed from the original. The concept of Patient Zero ties in with what it looks like now compared to what it started as. On a genetic level, if they *are* trying to create a vaccine, they will need to look at the areas that are the same in both the original (Patient Zero) and whatever is the newest thing. An effective vaccine targets the areas that are shared by all mutations of the infection. For example, you have a snake, a lizard, and a wolf. Cutting off the legs will harm the lizard and wolf, but does nothing to the snake. Putting them in a relatively colder environment will harm the snake and the lizard, but the wolf will survive. But finding Patient Zero and knowing what the original strain compared to the newest mutation is like cutting off the head of the snake, lizard, and wolf. They all share that common feature, so attacking that works on all 3.",
"Take something like Ebola Virus Disease. It is a hemorrhagic viral fever with a mortality rate of between 40%-90% depending on the strain. It's a mean, scary disease. It is transmissible to another human through all body fluids...Sweat, tears, saliva, blood, semen, snot...If you can leak it, Ebola will catch a ride on it. So lets say for example, a person in sub-Saharan Africa was exposed to the disease and got on an airplane to the US before they knew they had it. They would sit on the plane full of people and travel from someplace like Liberia, to maybe Amsterdam, then hop on another flight to someplace in the US like Dallas. They are around people sealed up with them on two planes and three airports. Fortunately, with Ebola, people are not contagious until they become symptomatic. So this guy is not showing symptoms until a few days after he arrives, so he decides to seek treatment. No, most hospitals in the US aren't going to think much of it, nor be equipped for it when a guy appears showing flu-like symptoms, then starts bleeding out of his orifices a day or so later. Health care workers that aren't prepared for this exposure might do something like hop on a flight to Ohio while another healthcare worker is reporting a fever. This would mean that the CDC would have to step in and find out everyone that had come into contact with that first patient on his trip from Liberia as well as anyone he had had contact with and that the healthcare workers that were exposed had been in contact with and have them all tested for Antibodies against the virus. This is exactly what happened with Thomas Eric Duncan in 2014. He was Patient zero (in the US). He wound up dying, but the healthcare workers lived.",
"Pt 0 is important for making vaccinations and containment efforts, if pt 0 was a French tourist visiting the us, the us may have the outbreak but France is at risk to. Plus it helps researchers find out what happened and how to stop it from happening again",
"I believe the disease can be tracked by following the location of patient zero. It helps to single out elements and various factors that may have influenced the spread.",
"I was under the impression that Patient Zero would have the most time with the \"disease\" or whatever, so the most possible mutations would be available for study and prevention."
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7gwjso | How does gentrification push poor people out of neighborhoods? | If you own a house or apartment in a poor neigborhood and the area gets gentrified, how can this be a bad thing for you? Doesn't your property just rise in value? Why can the poor not continue living there if they want? | Economics | explainlikeimfive | {
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"Your property rising in value isn't necessarily a good thing. It's good if you own it and want to sell it, sure. But if you want to keep owning it, it means you have to pay more in property taxes every year. If you *don't* own it, then it's even worse. It means your rent will go up, oftentimes so dramatically that you can no longer afford to live there.",
"poor neighborhood = low rent. But since not only poor people need or want low rent, also students, artists and all sorts of people move in. Because of the students and the artists there are small alternative businesses and clubs. This then attracts rich kids who enjoy this kinda lifestyle. The value of your landlord's property rises, he can afford to raise the rents because even if people move out, he will find new ones fast because everyone wants to live there.",
"When your property grows in value, the property taxes you pay also grow. If you're living on a fixed income, or your budget doesn't allow for a new expense of thousands of dollars per year, you're probably forced to sell your property.",
"> Doesn't your property just rise in value? Property tax is assessed based on the value of the property being taxed. If the area becomes much more valuable then people's tax burden rises. Also nearby stores may raise their prices because they expect that most people can afford it. Finally if you are actually poor then chances are you don't own anything to start with.",
"Your mortgage doesn't change, but your rent might. Or your property tax, ground tax, council tax, or other such things. Also, the cost of getting some groceries from the corner store will go up, as will the cost of getting a coffee and a sandwich from the café next door. The places you used to go to will either die off due to disinterest from the newer, wealthier locals, and will adapt and cater to them, rather than you.",
"While you can benefit from owning property in a gentrifying area, that is only the case if you want to sell and move elsewhere. But if you want to stay, you may be forced to sell because of rising property taxes and the impact on your budget. As an example, the area of Chicago where i live in rapidly gentrifying. Older homes that sold for like $100k 10 or 15 years ago are now selling for $500k. Between increases in home values and Chicago's increase in property taxes in general, some people may have seen their property taxes double from one 3-year assessment cycle to the next -- mine went up 77%, but we would be considered gentrifiers and we bought more recently, at near current value. So my property tax bill went up from about $4100 to $6900 literally from one year to the next. My wife and I combined make 6-figures and could absorb that... but some working class neighbor who is making $40k while supporting a family of 5? An extra $3k is hard to come up with... But the thing to remember is that in poor areas, most of the residents are renters. They have been living paycheck to paycheck, and have never had the ability to save for a home down payment. So they have no control over their housing and the landlord's decision to jack up rents. And as I described above, property tax hikes alone could cause a landlord to need to raise taxes $200-300 a month without even seeing any more money in his pocket. So it's not just that \"greedy\" landlords are trying to make more money because of gentrification, but instead them just trying to not lose money."
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7gwo2f | Why Is Companies giving Senators a big stack of money to get there way not considered bribery? | Other | explainlikeimfive | {
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"Companies do not give Senators big stacks of money to get their way. Just like I could set up a group that advocates for issues important to me, and either fund it with my own money or through donations, and then in turn decide to donate money to campaigns of candidates supportive of issues important to me - companies can do the same.",
"Because they are donating to the campaign, not directly to the Senator and the Senator cannot spend that money on personal things. It also has no binding agreements with the Senator. They are donating in the hope that the Senator will favor their donors when crafting law, not donating giving instructions on how they want the Senators to vote and what they want made law."
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7gwoax | How does mining of cryptocurrencies work? | Economics | explainlikeimfive | {
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"It's basically math. Let's say the first person that mined a bitcoin had to answer a simple math problem, 1+2 for example. Second person had to solve the first persons problem, plus one of his own. 1+2+6. Then he gets a bitcoin also. Third person has to solve everything that came before him plus one of his own: 1+2+6+37 Now imagine that you want to mine a bitcoin now, and a trillion other people have mined a bitcoin before you, you need to do a math problem with a trillion things added together. So that would take even the strongest computer a very very long time. Bitcoin made it so people can work on a small fraction of the big problem and earn a small fraction of that bitcoin. So if you did a million additions you might earn a hundreth or a thousandth of a bitcoin. But that's only a small part of the total answer to get the next bitcoin. Every bitcoin gets harder and harder to mine than the last ones. Eventually the math problem will get so complex that no computer in the world can solve it and that's when all bitcoin mining will end. Then people can just trade the fixed amount on the open market for goods and services, but no more will ever be made, unless they come up with something new and better. Note: I realize the actual math problem is more complex than this, but I'm trying to make it into something that anyone can understand.",
"Using Bitcoin as an example; When someone wants to *”make a transaction”* on Bitcoin. A mathematical number is submitted. The transaction is submitted to a pool of *miners* who attempted to solve the mathematical problem, which could be decrypting a SHA256 string. Once a solution is found, it is [I think] broadcast to the other miners, who then verify the solution. The transaction is then added to the list of previous transaction in a Merkel tree. And form a block, hence blockhain. The record of all transactions is stored on a single ledger to which a copy is stored by multiple nodes. in Bitcoins case can be downloaded by anyone (peemissionless). The distributed ledger is the same for everyone. Hence the term distribute ledger. Pwemissioned ledgers are restricted in who has the ledger or can mine or a private ledger. Added (Edit): A block is a string of multiple encrypted numbers together. So 1627377374 and 3737373737 become 3827262939 You can use math to unwind the numbers to get to your original number but the more numbers you have the harder it becomes."
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7gwq7j | Why having a diet high in salt is bad for your heart | Biology | explainlikeimfive | {
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"Simple explanation given to me I'm on a heart medication and diuretic (increased peeing = water and sodium levels decreased in blood) Sodium is a known to cause fluid retention aka the more sodium you take in the more water stays in the body and not filtered out. so high salt = high amount of water in blood. lets say that water changes to 1 gallon of blood will be 1 gallon + water content so lets say 1 gallon of water. Well now your 1 Gallon volume circulatory system now has 2 gallons in it causing increased pressure on veins and making your heart work twice if not three times as hard to pump double the fluid content through your body.",
"People with hypertension benefit from a low salt diet, although it's not clear that salt causes hypertension."
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7gwxpm | Why do microwaves cook the stuff on the outside of the plate more completely while the stuff in the middle remains cold? | Physics | explainlikeimfive | {
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"The microwaves penetrate the outside more than the denser core. Life pro tip. It will hear more evenly if you make a ring of food instead of a pile",
"Microwaves don't heat things evenly in their boxes, thats why they rotate. The outside edge will pass through zones that cook better while the middle might stay in an area with less radiation hitting it and since the middle portion doesn't move throughout the microwave",
"The type of the radiation used is only capable of penetrating \"skin deep.\" The rest of the object is cooked by that heat (absorbing outside inward). This causes the outside to be \"extremely hot\" and the inside to be \"less hot.\" The thicker the item, the less heat that can be absorbed (inward)."
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7gx0sd | A few genuine questions about depression. | Hi, first time posting here, sorry if this is a dumb question. I read a post earlier saying how it was near impossible to function with depression. It said it was hard to talk walk and concentrate. Is depression a thing we're born with or does it develop overtime? If it develops over time, for what reason will it develop? Also, can depression be avoided? As in, does it develop in your brain or what? Sorry if these questions are stupid, but I legit have no idea. Thanks if anyone helps. | Biology | explainlikeimfive | {
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"No such thing as a dumb question. So, depression can be confusing because we use the word \"depression\" and its' alternate forms to both describe a psychological disorder, and to describe an emotion that we all go through. The key difference is in the outside stimuli... You will naturally feel depressed about a loved one dying, but if you're neurotypical, you will eventually pull out of that. Chronic depression, conversely, show these same types of helpless emotions in people who aren't going through a devastating loss. To go through some questions: > Is depression a thing we're born with or does it develop overtime? It's a little bit of both, as far as scientists could tell the last time I did any research on the subject; Depression tends to run in families, and correlations are stronger the closer the family tie, which tells us that some of it is hereditary, but another predictive factor is how many \"minor depressive episodes\" (or: times you felt down about a big devastating loss but pulled through on the other side) people go through before hitting a certain age, which indicates an environmental factor at play. This also goes into the next question, I think, and I don't have much more of an answer for it, so: > Also, can depression be avoided? As in, does it develop in your brain or what? We don't have an effective prevention or cure for depression that I'm aware of, other than \"try not to suffer too many minor depressive episodes before you're in your mid-20s\" but that's a toss of the dice. It can be treated, but not fully cured. [This video]( URL_0 ) I found to be really helpful as an overview on depression and what we know about it, and from there you can read more contemporary papers."
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7gx1og | How do babies brought up in bilingual families differentiate between languages? | Biology | explainlikeimfive | {
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"I don’t remember this but I was a bilingual child who spent the first 3 years in a country with a third language, didn’t start saying anything more than da-da-da until my family moved to an English speaking country. Speech doctors were not concerned as apparently time and socialisation spent only speaking one language were the solution Note my dad did get in trouble by said doctor because he would speak to me in very bad Norwegian (or Norwegian sounding sounds) thinking it was cute and had been doing this for the first year and a half of my life",
"I see this was already answered, but I think I can expand a little more on the information the article is putting forth. I'm actually a linguistics student, and my primary area of study is developmental linguistics! So I'm a little excited I saw this question because its not often I get to gush about my science. So, first, to answer this question you should understand something about language development. Infants learn language in stages, and a large part of putting together a lexicon and grammatical rules is purely exposure. We \"teach\" language in school, but the fact of the matter is, children learn to speak their home language simply by being exposed to it. From being in the womb, to being fully competent speakers, our minds are constantly building a list of \"rules\" to follow. Some of these rules are obvious to us as native speakers. If someone asks you \"What's in a sentence?\" you would be able to answer \"A noun, a verb, a subject\" etc etc, or whatever is required for your native language(s). However, if someone asked you what order adjectives go in, would you be able to tell them? If someone asked you the rules in regards to the type of nouns that are acceptable to use with transitive verbs, would you know off the top of your head? No, probably not, this simply isn't something we teach people. However, in a normal conversation you will apply these rules without any hesitation, because its simply knowledge you have. The other thing you should know about language is that, while the general consensus among linguists is that grammar is universal (This is a result of Noam Chomsky's research, who is now a faculty member at my school and I cry every time I think about it.), every language has it's own rules it follows. Sentence structure, sound order, inflections, pitch, etc. Our speech is not just a bunch of sounds that we've agreed upon meanings to. Its an extremely complex combination of a multitude of factors that we've spent literally our entire lives piecing together. All that information comes together to tell us the content of a sentence, the intent of it, the case, subject, focus, etc. With those two things in mind, infants differentiate pretty easily. Bilingual children develop language at the same rate as monolingual children, with some debate on if they are actually ahead or behind monolingual children. Plenty of studies have been done and there is varying results, with some researchers finding that bilingual children develop at the same rate, but split their \"results\" between two languages, making them appear behind. Other have found that bilingual child basically \"double\" the rate of monolingual children, with having equal competency in both languages, and so forth. Like as said, even within the womb, fetuses are building this mental library of information on language. The body is a low pass filter meaning children gather information on inflection, tone, non-specific information that allows them to determine, in general, who is talking to them. I.e; voice recognition to a small degree. This is important for establishing a \"native\" language. This is also why bilingual children tend to favor their mother's primary language. Anyways, my point of mentioning this is that, the rules we mentally put together, from the day we're born, to being 5, or 6, or 17 or 90, allows us to very naturally, and typically, very easily, differentiate between languages. Even languages that are incredibly close, that share similar alphabets, phonology rules, etc, are complex enough at their base that word recognition is relatively easy. Simpliest way I can put it... All children's brains have a basket, and every word, every sentence they've ever heard is thrown into that basket so their brains can analyze it. Once enough sentences are in that basket to build baseline rules for a language, anything outside of those rules goes into a new basket. If they are unsure, repeated exposure and context allows them to establish it. Before an infant even says their first words, their mental basket has sorted through the most important rules of their language(s). As an aside, and something I absolutely love about bilingualism, is something we call Code Switching. Code Switching is essentially the opposite side of the spectrum. The capacity to differentiate between two languages, and not doing so. Its basically, talking in one language, and switching to another language mid-sentence. You hear it all the time, especially with sister languages (for example, when native Spanish speakers will inject Spanish turn-of-phrases into English conversation). While it seems simple, this is honestly an incredible phenomenon. Language is COMPLICATED. We have literally thousands of rules in our head, as I said, and bilingual speakers have the ability to not only keep track of these two(or three, or four, of five) sets of rules and manage them separately, but are able to recognize overlap in these rules and seamlessly move through the languages to form a cohesive thought in multiple languages. Code Switching is beautiful, because it can happen purely out of necessity (the idea can't be conveyed in one language, so they switch to another), limitation (they don't know **how** to convey the idea in one language, so they switch to another), stress (the mind is too frantic to sort through the rules, so the baskets get \"knocked over\" and everything gets mixed up) or emphasis. Anyways, I rambled a lot, but I hope that answered your question.",
"I babysat for a bilingual family, mum speaking French and dad English to kids (5 and 2 at the time). They were dealing pretty well, but kept it really separated. Kids had their minds blown when they discovered I could read books in both languages to them :)"
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7gx2q1 | When you eat something hot and burn your tongue, why does your tongue feel weird afterward and why does your sense of taste get messed up for a short period of time? | Biology | explainlikeimfive | {
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"Your tongue feels weird because you've just burned a part off and done some minor sensory nerve damage. Which is also why your sense of taste gets messed up."
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7gx6za | How come things get harder and harder to destroy as they get smaller? | Example: You have a chip and you keep breaking it but it is hard to break a very visible crumb. | Physics | explainlikeimfive | {
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"Leverage. You can take a stick and break it in half over your knee. Now take those halves and do the same. Eventually the size of the object will limit the amount of leverage you can put on it's body until not enough force can be applied to break it. Large object = more leverage can be applied."
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7gx7x7 | How people in the past made charcoal? | Chemistry | explainlikeimfive | {
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"The same way they’ve always made it. It’s mostly low carbon, and it’s made by cooking wood in a low oxygen environment.",
"Here is a video of traditional charcoal making in UK... URL_0"
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7gxa9q | Why dont humans have mating seasons? | Biology | explainlikeimfive | {
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"Mating seasons allow offspring to be born at a time when conditions are favourable. Generally this means they will be born at a time when food is most plentiful and conditions are less harsh. Often it is safer to be for large populations to be born at the same time and place as it increases the chance of avoiding predators. Humans don't have a season now, it seems, as conditions are largely fine for giving birth all year round. This may not have always been the case, it was found that female feromones are higher at certain times, suggesting we have evolved away from mating seasons.",
"It's not just humans, other primates don't have breeding seasons either. One theory is this is because primates are very social creatures who raise children collectively, so it's more important to be able to produce a child when social factors are right than what time of year it is. Animals like fish, reptiles, and insects don't care about things like families or mates, so they just get it on as much as they can when the spring comes and food is plentiful. However, for primates it's better to have a baby when we find an ideal long term mate and when our family is prepared to help us raise it than to just have one because it's spring."
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7gxal7 | What is the science behind how a boomerang works? | Physics | explainlikeimfive | {
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"There are four main points to understand about a boomerang: 1) You throw it vertically, not horizontally. This will be important later. 2) Airfoils. Each arm of the boomerang is a little airplane wing, which creates lift as the boomerang spins and flies. There are left-handed and right-handed boomerangs because of this; if you throw with the wrong hand it will spin \"backwards\" and won't produce lift. 3) Unbalanced lift. Since the boomerang is moving forward at the same time as it's spinning, the arms aren't moving through the air at the same speed. For one arm the spin and the forward motion are working together, creating more lift. For the other arm the spin and the forward motion are fighting each other, meaning less lift. This means there's more lift on one side of the boomerang than the other, so it will try to tilt to the side. 4) Gyroscopic precession. Things that are spinning resist being tilted - think of a child's top or someone spinning a basketball on their finger. It's one of the more \"wtf\" behaviors in basic physics: a spin around one axis and a tilting torque around a second axis combine into a turn about the third axis instead. So when the boomerang, which is spinning, tries to tilt because of the unbalanced lift, it ends up turning instead. This is why you have to throw it vertically, not horizontally: it's spinning about the left-right axis, and the unbalanced lift is trying to tilt it about the front-back axis. So it ends up turning around the up-down axis, which means it turns around and flies back to you. If you were to throw it horizontally, the axes would be different and it would turn upwards instead, flying up into the air uselessly."
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7gxdr8 | Why does the sky turn dark when it's about to rain? | Other | explainlikeimfive | {
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"Cumulonimbus clouds are the ones that rain, and they are very thick and dense. Their density is *why* they rain in fact, it's too much water too close together so it clumps up and falls out of the sky. They will block more of the Sun's light than any other type of cloud, so that's why it gets dark when it rains. However, a cumulonimbus cloud doesn't have to be between you and the Sun. The Sun could be setting in the west and the clouds are right above you, and it will be bright and rainy."
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7gxifq | Why are you expected to drive faster than the posted speed limit in the United States? | Other | explainlikeimfive | {
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"Many drivers know that absolute enforcement of speed limits is very difficult and sometimes dangerous, especially if every driver is slightly above the limit, and minor offenses are punishable by a small fine, if not just a verbal warning. Instrumental tolerance and error is a very easy argument against a small traffic ticket. Because of this, they drive slightly faster than the speed limit, as the chances of being stopped just for a minor offense or verbal warning is close to zero. The police are primarily looking for those who they suspect may have a secondary offense that can be cited (such as reckless driving of some sort) and major speeders.",
"Speedometers are not perfect, and neither are drivers. A cops 80/kph and your cars 80/kph might be a few klicks off, and that can be used in court to get out of tickets. So cops tend to give you ~10k wiggle room, so when they nail you at 11k over, you're dead to rights. Because people know they have the 10k margin of error, it's more or less expected to be within it. *Sorry, Canadian, not American, but close enough?",
"Because we have places to go, the consequences for speeding slightly are slim to none, and because [speed limits are quite outdated and restrictive]( URL_0 ). Also, driving with the flow of traffic is far safer than going slower than everyone around you, so it's one of the few times where \"because everyone else was doing it\" is a valid reason in terms of safety, if not in terms of the law."
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7gxiuc | what is crypto currency? How is it used and where does the money actually go?? | Economics | explainlikeimfive | {
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"Basically, instead of having a server that says, Person X has $52, person Z has $3000, they work by giving everyone a copy of the data. The data from the past in included in future transaction logs (called Blocks generally) in such a way that confirms that the new transactions are valid. I'm not gonna get into mining, since it differs between crypto variants, in terms both of what needs to be solved and how new coins are distributed. I assume you are asking because the price of Bitcoin is skyrocketing. The way that they are valued is based on trading. Someone says I want to buy 0.25 bitcoins for $X, and if someone else has said they want to sell for $X, than a transaction occurs. So anyone getting money *out* of the system comes from someone else putting money *into* the system. There are many websites that exist to do this process, and they work off of the main transaction archive (not on the Blockchain). This is because it is both much, much quicker and cheaper to do so. You send X bitcoins and $Y to an exchange, and now they track that on your account. So we're back to where we were with normal currency systems, as opposed to distributed. There are a lot of things that go into why the price is rising, why prices tend to be pretty equal across multiple exchanges, but this already getting a bit long."
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7gxkcr | How do companies make sure representatives don't vote against them after getting money? | ISPs can't just write "we will only give you this much if you vote yes", since that's proof of bribery, right? So how do they make sure that the politicians they bribed actually vote for them instead of just taking the money and voting what they were originally going to vote? | Other | explainlikeimfive | {
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"They of course can't guarantee it, but that is a very easy way to lose their campaign donations and have them go to your opponent when you come up for re-election. And most politicians aren't just in it for a single term, they'd like to win again next time.",
"There are clear cases of donations influencing votes, but it's also worth bearing in mind that many times, corporate donations go to someone _who already supports the policies the company wants_. During the election season, if Candidate A says, \"I will do X,\" and Candidate B says, \"I will do Y,\" then a company/organization/individual in favor of X over Y will probably give money to A instead of B.",
"Elections happen every couple of years. Wealthy people and corporations won't exercise their massive amounts of free speech at them next time if they don't toe (or is it tow?) the line.",
"Career politicians always need money for their campaigns. US Representatives have to be reelected every 2 years and US Senators every 6 years. If they don't vote like they were \"paid\" to do, they will never get another dime from those companies. The GOP admitted the current tax cut bill is a payback to donors and if they don't pass it they will never get their campaigns funded again. It's a bribe but unfortunately in this country, a legal bribe."
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7gxn37 | Why do drinks in different containers taste different, in example, soda in can vs fountain vs bottle? | Chemistry | explainlikeimfive | {
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"So the obvious reasoning is that the metal or the glass don't react the same as the other with the soda. But both products are the same just in different containers. Coca-Cola INSISTS that they don't taste any different with this quote \"The great taste of Coca-Cola is the same regardless of the package it comes in,\" Also take a look at this \"the polymer that lines aluminum cans might absorb small amounts of soluble flavor from the soda. Conversely, acetaldehyde in plastic bottles might migrate into the soda.\" Hope I was able to be of some help. Source : URL_0",
"I'm glad to see this question, am looking for some good science answers. I despise Snapple in plastic bottles. It tastes different. Imagine my horror only a few days ago where all the bottles are the same shape, but are plastic now. With big logos advertising they are plastic. I may never have another Snapple the same way again."
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7gxnzk | what are DJ's doing when they are pushing buttons and turn knobs while playing live if the song/mix they are playing can just play on its own? | Other | explainlikeimfive | {
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"The two turntables on either side of the knobs can be used to speed up or slow down the song that is playing in order to match the speed of another song. The, their melodies and percussion can match up and the transition between the tunes will be smooth. The knobs are typically used to control the volume of the different frequencies of the songs. Most of the time, there are three knobs per channel to help with this: One knob for high frequencies such as high hats and cymbals, a 2nd knob for mid range frequencies like vocals and instruments, and a final knob for low frequencies like kick drums and basslines. By adjusting each knob, you can further enhance the quality of the transition between two songs by not allowing vocals to clash or having double the amount of bass. Edit: check out URL_0 for a fun example on how to quickly use these tools to put together a performance."
],
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7gxpy0 | What was Argentina a believed hotspot for Nazis during and after WWII? | I've noticed this throughout my adult life, but I just don't get it. Why Argentina? What made it stand out to Nazi High Command? | Other | explainlikeimfive | {
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"text": [
"German speaking people from all over Europe started emigrating to Brazil and Argentina in the 1870s, and continued to do so in fairly significant numbers right up until 1939, and of course after the war. What makes Argentina kind of different is that a lot of those people lived in enclaves all over the country and continued to speak German and follow German customs, and continue to do so right up to the present day.",
"Argentina had a lot of Nazi sympathizers, so Nazis went there to escape being sentenced to death or life imprisonment. Argentina was more than happy to have them, and they were more than happy not to be hanged.",
"Argentina has few extradition treaties with other countries. If someone is discovered as wanted they will not be arrested by the Argentines and given to the authorities of the home country, and the home country does not have authority to arrest them while they are within Argentina."
],
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11,
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7gxpy6 | Why does a city like Seattle have forecasted temperatures of 47/41 (hi/lo), a difference of only 6 degrees, while Los Angeles' forecasted temperatures are 73/49 (hi/lo), a difference of 24 degrees? | I live in Los Angeles, and find it odd that the temperature at noon is only 6 degrees hotter than the middle of the night | Other | explainlikeimfive | {
"a_id": [
"dqmj46i"
],
"text": [
"Humidity. Drier air causes higher temperature swings between daytime and night. The moisture in the air holds the temperature from the sun and cools off gradually. Dry air cools off immediately once there is no direct sunlight."
],
"score": [
4
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7gxtlu | How does dry cleaning work? | Chemistry | explainlikeimfive | {
"a_id": [
"dqmlh74"
],
"text": [
"It uses a series of solvents. It isn't literally dry, they are liquids, but they're not *water*. Basically soaking it in not-water-solvent, dissolve any stains, rinse, then evaporate away what's left of the solvent. Uses chemicals like URL_0 or just paint thinner."
],
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6
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Tetrachloroethylene"
]
]
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|
7gxtu6 | Why does your saliva taste different when you have the feeling of having to vomit? | Chemistry | explainlikeimfive | {
"a_id": [
"dqmk0vv",
"dqmk7w8"
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"text": [
"It protects your teeth and esophagus from the harmful acid in your stomach that comes up with barf. The human body is a wonderland of gross. Edit: I kinda didn't answer why it tastes different but this is why it happens. Lol sorry",
"Before vomiting your mouth will secrete a lot more saliva to protect itself from the acid that's coming up. This is a more basic solution to offset the acid so it doesn't burn any tissues. The basic property plus the amount of saliva that you aren't accustomed to will cause a taste difference"
],
"score": [
10,
5
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7gxv04 | Why do some people get car sick, even if they are looking at the road while they are moving? And why is it more likely while you are on a hill or mountain? | Biology | explainlikeimfive | {
"a_id": [
"dqmm0be",
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"text": [
"Car sickness generally comes as a result of your vestibular system sensing motion that does not agree with what your brain expects. The vestibular system is essentially the system your body uses to sense normal movement. Your inner ear and other nervous system functions work together to let your brain figure out if your body is moving. Normally, your brain takes input from the vestibular system and combines it with other senses to understand what's going on. What you see is one of the most powerful tools your brain uses to check and validate what the vestibular system senses. When you turn your head left, your vestibular system says \"hey, we think the head is turning left\". Your eyes say \"hey, it looks like we're looking left now\". Your brain recognizes that both systems are in agreement and accepts the turn as normal. When you're in a car, your vestibular system is sensing motion outside the control of the body. It feels acceleration, turning, and all sorts of input. Meanwhile, your eye's don't necessarily see the same things the body feels. Oftentimes looking out the window helps, but without a constant frame of reference, not all brains are able to reconcile what is seen and what the vestibular system feels. Any time the vestibular system isn't in agreement with other senses, the brain can potentially trigger a nauseous response. Very literally, your brain thinks it may be poisoned (that's how it explains why things aren't in agreement), and it wants you to puke up the potential poison. The reason it may be more common on a hill or mountain can come from many different reasons: - If you can't see the horizon clearly, you may not be able to accurately judge what \"level\" is, and it may confuse the brain. - Road conditions on mountains are often poor, and the small bumps may exacerbate the problem. - Driving on a flat surface generally means that motion happens on two axis. Driving on hills or a mountain introduces a third axis. That's another variable that might be off with your vestibular system, and it can lead you to getting sick easier. Essentially, the more chances you give your brain to have mismatched inputs, the more likely you are to get sick.",
"A vehicle driving down the road constantly bumps around, making slight corrections to keep on the road. This creates a disconnect between the structures in your inner ear that determine balance and what you physically see. This also happens to be a symptom of poisoning, so your body's response is to become nauseated to vomit the assumed poison."
],
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|
7gxx8a | What are those chills you get when you listen to good music? | Biology | explainlikeimfive | {
"a_id": [
"dqml8e1"
],
"text": [
"It's called ASMR - short for Autonomous Sensory Meridian Response. You can explore a vast library of videos on YouTube of people making sounds deliberately to trigger this response. It helps a lot of people with anxiety and is really good way to relax! When you experience the right stimuli, your brain involuntarily responds with those tingles. Enjoy!"
],
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4
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|
7gy6j3 | What causes humans to think a smell stinks? | How does a human decide if something stinks? For instance why do flowers smell good and flatuance smells bad? | Biology | explainlikeimfive | {
"a_id": [
"dqmtr8e"
],
"text": [
"The human body, like most animals, is designed to avoid things that are harmful to it or might get it sick, by using it's senses. An example to it is stench. The body translates smells of things that might get it sick, such as feces for example, as 'stinky' (unsettling feeling) so the brain will keep the body away from them. Another example is pain. Much like stench, the body will translate the physical harm as uncomfortable, and will avoid getting close to harmful dangers or actions again. Savvy?"
],
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4
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7gyle0 | Why does garlic smell good in food but bad in breath? | Chemistry | explainlikeimfive | {
"a_id": [
"dqn2wdr",
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"dqmrxpy"
],
"text": [
"As you are eating it, your body begins breaking down garlic immediately into sulfuric compounds. These sulfuric compounds remain in the mouth and smell very similar to the compounds that the bad breath causing bacteria in your mouth also create. Secondary to that, as the garlic passes into your digestive tract, your body decomposes garlic into allyl methyl sulfide. This is distributed through the bloodstream to the lungs, then exhaled through your mouth or you just burp it up. This is what causes garlic breath to linger even after brushing your teeth, mouthwash, etc. It smells pungent and aromatic as a food while also being slightly sweet if cooked. The chemical reaction that occurs during digestion is what makes it no longer appealing after we eat it.",
"I don't recall the name of the compounds, but garlic breaks down into several sulfur-like compounds. They aren't present in the garlic before you eat it.",
"Probably for the same reason that your farts smell good to you but no one else's farts do. Its probably a psychological thing where your brain says \"is the breath from another person? If so, it smells bad\""
],
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39,
4,
3
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|
7gyngw | Why is hearing loss impossible to cure? | Biology | explainlikeimfive | {
"a_id": [
"dqmrugu"
],
"text": [
"Its not. It depends on what you mean by hearing loss and cure. A cochlear implant can cure hearing loss, in the sense that the person can hear again, but the underlying cause is not cured"
],
"score": [
3
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"text_urls": [
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|
7gynzu | Since we now know that atoms are made of even smaller particles, and the basis for their existence is that at some point there is a limit to how small something can get, does that mean either that there is no limit to size, or that atoms aren't real or practical terms anymore? | Chemistry | explainlikeimfive | {
"a_id": [
"dqmr1gp",
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],
"text": [
"Is there a limit as to how small something can get?",
"An atom is still a very practical term, especially since you've tagged the thread 'Chemistry'. It is the smallest object that maintains the same chemical properties."
],
"score": [
3,
3
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|
7gypzw | How long would it take to heat a bathtub of water with a lighter? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"171 hours, 11min Assumptions: No loss of energy 80 gallon tub Start/finish temp: 68F/103F Heating power: 40 watts (consensus found online for a candle)",
"In practice, you'd lose significantly more heat than you'd be adding. A bit like blowing air into a blimp that has a huge hole in it. The minimal heat from the lighter would be lost to the cooling of the tubs surface water.",
"With a single lighters? I don't think it'll ever happen."
],
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3
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|
7gyuau | When a ball hits the ground, is its momentum transferred to the Earth? | Physics | explainlikeimfive | {
"a_id": [
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],
"text": [
"Yes, and given the immense size of the Earth compared to the ball, the effect is negligible in just about any application."
],
"score": [
6
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|
7gyyij | Why does most garbage have the same smell? | My garbage and someone else's can have almost the exact same smell, even if we have completely different items in our trash. What causes this? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"This isn't 100% true as different garbage can smell different (green waste vs solid waste, etc.) But in normal trash, like you will have in a trash can on the street, the primary thing you're smelling is decomposition of you're food, mostly the protein like old bits of meat. The reason it all has a similar smell is they all produce pretty much the same gases, hydrogen sulfide, carbon dioxide, methane, and nitrogen. This is an extremely simplified way of putting it. But it's one of the key factors.",
"Because what you're smelling is bacteria poop, essentially. Garbage is stinky because microorganisms find it, move in, and start to eat it and breed and of course, excrete waste. Much like us bigger organisms, even if their diet is varied the un-digestable waste products are pretty consistent. Consistently gross, that is.",
"there is a wide array but your right most likely you will encounters similar or close smells most of the time due to the fact what your smelling is a blend of mold and rot. usually rot smells the same cause its the same decomp molecules being released nitrates nitrogen carbon etc. mold on the otherhand some mold are extremely common in garbagio so most likely your encountering the same mold colonies. so all those smells mixed together your gonna get a blast of stink which you can't differenciate sometimes. It's like mixing 50 perfumes and then mixing another 50, they usually smell the same I tried it for college doing a study of scent differenciation about no one in my class could pickout which of the 50 was in one batch, or the other, or the one my friend did to counter mine is 50 colognes still confused our noses then we tryed to see if mine and his are compatible scents could not differenciate mixed together from seperate men and women sprays."
],
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7gz5dm | I read that members of the U.S. congress need, on average, "$14,000 every single day just to stay in office". Why? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Power. Why else spend $3 million to get a job that pays $80,000?"
],
"score": [
3
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|
7gz7ee | How and why do our brains make up the color magenta? | Magenta isn't on the visible spectrum, which means it doesn't have a wavelength, which means it doesn't exist as a color of light. So...like it says on the tin. | Physics | explainlikeimfive | {
"a_id": [
"dqmvq42",
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"text": [
"It's a mixture of colors and can't be defined by one wavelength. So is any kind of brown. No big deal.",
"Because 'colour' doesn't exist in the real world. In the real world it's just photons of a certain wavelength right? What you truly see as colour is an interpretation by your brain of the signals that come from your eye. You're might be familiar with these optical illusions: URL_1 URL_0 A very similar thing is going on here. You are not seeing the world as it truly is. You are seeing the world as your brain interprets the world. Magenta is what your brain \"sees\" when your red and blue, but not green, cones are activated in your eye. Humans also don't have a colour receptor for yellow (well.. most don't), yellow instead works like an \"anti-blue\". If your eye sees green and red, but not blue, then your brain turns it into yellow."
],
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"http://brainden.com/images/rotating-dots.gif",
"https://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Optical_grey_squares_orange_brown.svg/1280px-Optical_grey_squares_orange_brown.svg.png"
]
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7gzl9z | How can the Senate vote on something no one has read? | Other | explainlikeimfive | {
"a_id": [
"dqmyp31"
],
"text": [
"Not sure about the time frame, but basically lobbyists read bills and tell Senators and Congress how to vote in order to 1: Get Money and/or 2: Stay elected."
],
"score": [
4
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|
7gzlat | Why and how exactly do computer files become corrupt? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Let's say you work in sandwich shop, and all you do is make sandwiches all day. Bread, meat, bread, bread, meat, bread, all day long. It is super boring, and sometimes your mind wanders. One day, you mess up and do an extra bread...Bread, bread, meat, bread, bread, meat. And since you weren't paying attention, you might make a hundred bread, bread, meat non-sandwiches before anyone notices, and all that work is wasted. File corruption works the same. Files are a series of ones and zeros, that have to be in just the right order. One number gets changed, or even worse, one is skipped or added, and the file gets corrupted. Sometimes the impact is local, and you just see or hear a little blip. Other times the first is messed up so badly the computer doesn't know what to do with it.",
"There are a number of different ways that this can happen, and it can happen at various different levels of the hardware-software stack in a modern device. First, let's define \"corrupt\". That basically means that for one reason or another, when your device tries to read a file that looks like a duck, it finds out that it doesn't quack, or doesn't have feathers, or it has a beak and then the rest of it is a frog. At that point, the operating system will refuse to load the file and something will tell you that it's corrupt. Files are stored on your device's storage drive. In the past, this was most likely a hard disk, so let's start there. Hard disks use rotating magnetic platters to physically represent the 1s and 0s that make up your data. They're almost like tiny, *tiny* switches that can be flipped on or off. To store more and more data, the switches (and the arm that reads and writes them) have to get smaller and more precise. So, a hard disk depends on lots of precision pieces moving very close together, and it depends on them being highly durable and accurate for a long time. If the bearings that let the disk spin freely start to wear, the disk can wobble, and the arm can either contact the wrong part of the disk, or contact the disk way too hard, damaging a big fat line of those tiny, delicate switches. That's one easy way to lose data, or make a hard disk permanently unusable. The way that most disk manufacturers mitigate this risk is by implementing a \"sudden motion sensor\", which you might have actually heard on an old iPod or laptop - if you shook it or moved it around while it was changing tracks, you'd hear a sound like \"Click! Sssssyyeeeewwwww\". The \"click\" is that read/write head getting parked *away* from the disk ASAP. The little laser noise is the drive spinning down. The goal is to make sure the disk doesn't wobble while it's at full speed, and the head is nowhere near the disk while it might be wobbling. But, that's far from everything that could damage data on a hard disk. Dust on the drive platters, liquid - really anything at all inside the case - could damage the delicate parts. That's one of the main reason the cases are sealed. That's one of the reasons that almost all modern devices use non-volatile flash storage. Flash storage is conceptually similar to computer memory - internally, it looks like a 'chip' instead of like a metal disk, and the way information is recorded onto it is with electricity rather than with a physical arm. Briefly, instead of little physical \"lightswitches\" like a hard disk would have, a flash drive has little gates that can be \"opened\" or \"closed\" with electricity, using that \"open\" or \"closed\" state to represent a \"1\" or a \"0\" when they're read later. But, anything that undergoes a physical change will wear down. That's the same reason that usable space on a flash storage drive will wear out over time and your \"usable space\" on a drive will decrease. Eventually, the gates get stuck or break, so they can't be opened or closed anymore. When that happens, the flash drive will make a note to itself, like \"when I try to open and close gates in this area now, they don't work well\", and decommission a small chunk of the drive. Before that happens, it will try to shift your files around so that they're still accessible, and use error correcting code to make sure they still \"look\" right. Speaking of memory, that's another opportunity for a file to become corrupt. Files are read off your storage device into memory while you work on them, and when you save them, the version in memory is written back onto the disk. If you've got bad or broken memory, such that your disk hands it \"my name is bob\" and the memory creates \"y nane is bbb\" when it comes back out, that's an opportunity for corruption (especially if the garbled bits aren't in your thesis statement, but in the part of the file that tells Windows \"hey, I'm a Word file\"). The next level up is the filesystem. You might have heard a big fuss about this recently with Apple's release of APFS, their replacement for the older HFS. One of the big dangers in a filesystem is \"hey, if I lose power while I'm saving my file, what happens to it?\". This is another potential case for data loss. If your computer was halfway through saving your homework and then the power went out, you might very well have had half of the old file combined with half of the new file, and even though the hard disks still say \"yep, those are the 1s and 0s you told me to write down\", the filesystem is going to get confused and probably refuse to open the file. To get around this obvious nightmare scenario, most filesystems used in the past 20-30 years have used something called \"journaling\". Rather than risk your one and only copy of a file, the filesystem will first write the changes you want to make to a log. It then reads the log, copies the original file, applies the changes, verifies that the new file looks like the old file (plus your changes), and then deletes the old file. At any point in that chain, the drive could lose power and you'd still have *at least one* good copy of *a version* of the file. Much better than nothing. One of the big features in APFS (and a lot of other modern filesystems) is that it gets rid of journaling in favor of something called \"copy-on-write\". Copy-on-write is a lot like journaling without creating the second file. When you save a file on a CoW system, you're saving what's different, very similar to the log. But now, when you ask for that file, the filesystem will pull up the original, apply the changes on the fly, and transparently give you an identical file to the one you would have created on an older filesystem. CoW is a big deal, because you get a lot for free. For instance, when you copy a file, if there are no changes, the filesystem just creates a sign that points to the old file and says \"done!\". If you change the copy, it creates a list of changes that apply to the sign (that points at the original file, which hasn't changed). That's how Apple's Craig \"Hair Force One\" Federighi was able to do his demo of \"instantly\" copying files in the new macOS - they're not being copied in a literal sense anymore. Ultimately, the point is that you don't risk the original file nearly as much if you're never moving, copying, changing, or deleting it - all of which are opportunities for corruption. And that's just about it. There are definitely other cases that can cause corruption, but those are the main ones, and the gist of it is: anything that physically or electrically causes a file to not be what it says it is will mean the file is now \"corrupt\". Sometimes it's faulty hardware, sometimes it's faulty software, sometimes it's a power loss or a malfunction. Final parting thought: As a software developer, I also can't promise that devlopers don't sometimes change things like configuration files between versions, and instead of translating the old one into the new one, just avoid the work by saying the old one is \"corrupt\".",
"If a computer is using a file, it's probably going to read it and write onto it constantly. If something disturbs the computer enough, it might mess up and write the wrong thing. If I'm writing my banking account number to you, but I accidentally write a 3 instead of an 8, suddenly the entire number is useless to you. A single mistake can irreversibly ruin a file, thus making it corrupted."
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7gzou0 | How are these politicians receiving kick-backs from Telecom publicly and not being punished for it? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Donations to a politician's election campaign are not kickbacks, bribes, or any other sort of illegal transaction.",
"They're receiving political campaign donations from telcos... or lobby groups that represent telcos. And by law they have to disclose this.... but unless there's a particular industry-we-hate of the week like telcos in this case, noone particularly cares. Well, maybe some voters care. Campaign donation records are available, you just have to bother to look them up. [For example, here's Paul Ryan's.]( URL_0 )"
],
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7gzpgg | Why do certain bacterial infections (skin infections, strep throat, etc) resolve on their own while others (curable STDs for example) tend to persist for life unless treated with a course of antibiotics? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"It's most viruses that stay latent forever. There are some instances of bacteria that live inside you, don't make you sick, but can make other sicks. It's like a landlord that owns a bunch of houses. He doesn't really care who owns the houses, but wants to make sure the tenants are paying rent and not making any mischief. Some viruses (all herpes, others) are like good squatters. They're not supposed to be there, but they keep up appearances from the outside, even though they may be cooking meth on the inside. Viruses have some pretty crazy techniques to evade our immune system. They live inside the cell, and are armed with a host of enzymes and proteins that basically don't alert the immune system to something going on. They disable the alarm system and keep to themselves, so when the police drive by, they see a regular house with the lights on inside and nothing obviously amiss. Some bacteria can do this to an extent, but I'm not really aware of nasty bacteria that don't produce clinical signs, are contagious to other people, and can hangout for any *long* periods of time. You can be infected with a bacteria, not be sick, but still be contagious to other for a long time. These bacteria have characteristics that just makes it so they take a long time before they make you sick. It's not really the same as the way a virus can lay dormant and 'recrudesce' during times of stress and either make you sick all over again, or make you contagious. There's a disease in cows where, if the mother is infected while pregnant at the right time, the fetus develops enough of an immune response to not get aborted, but results in an unthrifty calf that is a major sources of infection for other cows. These animals rarely live beyond a year though. I like immunology and stuff like that, hope this helps.",
"It’s pretty much all down to the methods that they use to evade the immune system and their relative effectiveness. Some bacteria hide inside your own cells. Some bacteria find a little pocket where they can develop their own environment (ulcers), some kill off your cells to get a nice oxygen-less space, and some activate your immune system so strongly that your own immune cells start attacking you. Bacteria want to maintain a balance where you’re sick enough to allow them to spread but not so sick that you die without spreading the disease to another place where it can grow. Basically, some bacteria (generally the ones that don’t spread super easily) are just better at evading the immune system, so we have to give antibiotics. Some don’t need to survive too long because they spread quickly to other people. The overwhelming majority of bacteria are either blocked by our skin/mucus, or they get the shit beat out of them by our incredibly powerful immune system"
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7gzu7h | Why do debits and credits always equal in accounting? | I understand that they have to equal and will always equal on balance sheets and etc. but I don't understand why? How is it possible for a company to lose money and liquidate if their accounts are always supposed to equal? Really just need a diffinitive answer for an accounting dummy like me. Ty in adv. | Economics | explainlikeimfive | {
"a_id": [
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"text": [
"A debit to my account could be a credit to yours. No money is lost in the transaction. The movement of money out of various accounts (as a whole) must equal the movement of money into various accounts (as a whole).",
"Maybe you are thinking of an account in a general ledger as representing things like cash in the bank. And while there are some accounts like that, others represent things like \"how much we spent on electricity\". So let's say a company gets an electric bill for $100 this month. When it pays that bill, in its ledger it records a decrease of $100 in the \"cash\" account and an increase of $100 in the \"electricity expense\" account. So overall the debits and credits are equal for this transaction even though we have less money in the bank. This could continue until we have no money in the bank and have spent it all on electricity. But then what happens? Well, we could borrow some money to keep paying the electric bill. So next month we take out a $100 loan and pay the bill with that. Our ledger would show another $100 increase in electricity expenses, but now also a $100 increase in loans we own. Hmm, both things increased (loans owed and electricity expenses paid), so how does that work? Well, the rules for what counts as a debit or a credit vary depending on the type of account. For expenses, an increase in the expense = a debit, whereas for our cash account, a decrease in cash = a credit. So we get balanced debits and credits when we pay a bill with cash (credit to cash, debit to expense). For a loan (a liability) an increase in that = a credit. So when we borrow $100 to pay the electric bill, we credit the loan account and debit the expense account. So we still have balanced debits and credits even though both accounts increased. The rules for when you do a credit vs. a debit are designed so that they'll always balance for any conceivable transaction that happens."
],
"score": [
6,
4
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"text_urls": [
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7h0bf6 | What's the point in having arched feet? | Why isn't it better to NOT have an arch and why does it cause pain for people when they have fallen arches? | Physics | explainlikeimfive | {
"a_id": [
"dqn5k6p",
"dqnc15p"
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"text": [
"Too much of an arch will cause you to put a lot of weight on your heel. Which causes pain. Too little will cause issues with posture and issues with walking, since they can't support your body properly. It makes your legs rotate in when you take steps.",
"Humans are very good walkers and pretty good distance runners. We are so good at endurance that we can actually stalk deer to death. Endurance hunting was the primary mode of hunting before (and for sometime after) the invention of the spear. We would just follow deer for hours or days until the deer died of exhaustion. Deer can sprint. They essentially walk on their toes (the balls of their feet). They are way faster than a human - but only for a few minutes. Think PePe LePew. Humans can transition between their toes for running and a heel to toe walk for more efficient walking by simply transferring weight between their legs. Doing this for hours exhausted prey to the point of death. This more efficient walking is why we can stalk deer to death. But it also requires a more complex foot that can “pronate” between flat and arched. A human without the arch will have ankle and shin pain because the leg is designed for this complex foot shape."
],
"score": [
5,
4
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"text_urls": [
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7h0moe | How does a “power nap” give you more energy than waking up slightly later? | After a power nap you feel reenergized but if I wake up during REM I am exhausted waking up but I technically rested for longer. How or why does it work this way? | Biology | explainlikeimfive | {
"a_id": [
"dqnk4k2",
"dqnakec",
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],
"text": [
"I think a lot of people forgot the ELI5 here. I'll try my best to make this understandable: When you go to sleep you go through different stages of sleep. The first ones clean out your brain a tad bit, making you have less of the hormones (emotion regulants) which makes you sleepy. The next stage makes you fall In a deeper sleep, where you get more of these sleep hormones. If you're awoken in this part, you'll likely fall asleep a couple of seconds after waking up, like if you fall down from your bed in the middle of the night and you go back up into your bed and forgets about it. If you sleep for an entire cycle, your brain will have gotten in and out of these cycles a couple of times, and It will have cleaned up all the trash which isn't cleaned away during day time. If you just take 30 minute naps, you will not be in the second state, and you will feel less tired. It's important to sleep through the entire sleep cycle, as your brain needs cleaning. You usually wake up naturally after a cycle, but you can wake up earlier and still feel good as new if you use sun light to make the sleep go faster (try sleeping in a totally dark room and then right next to a window, and not put an alarm) So in short: power naps removes what makes you tired, but doesn't make you well rested!",
"It's like money. If your have 1000 bucks having 1010 isn't much, but if you have nothing 10 bucks can be a lot",
"REM is also known as deep sleep. And you want to stay there. It's like being really focused on something, then having someone disturb/interrupt you. You're groggy and don't know what's going on. You go through stages of sleep. It takes different amounts of time to get into each stage, and some stages allow for easier waking up than others. These 'power naps' really only go into the first 2 stages of sleeping, which are rather light. So you don't have time to go into the deep, REM sleep."
],
"score": [
9,
4,
4
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"text_urls": [
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} | [
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7h0tl6 | how is there enough cows to make enough beef in the world to supply restaurants/fast food chains? | Other | explainlikeimfive | {
"a_id": [
"dqn9m8v",
"dqn9o4g",
"dqn9mgq"
],
"text": [
"Farming, intensive breeding, and the fact that one cow can product hundreds of cuts of meat (at minimum). Cows are like a ton, a normal steak is about 600 grams ish. There are plenty of cows",
"There is demand for beef. People will pay money for it. This leads profit-driven people to raising cows for the purpose of selling them. Cows are large, about 1500 lbs. That's a large meatsicle. Where I live there are approximately one million people and two million cows. The average cow is about five to ten times the size of the average human. We export a lot of meat. If we didn't it wouldn't be humanly possible to eat all this damn beef.",
"well... there are 30million + beef cows in the US alone at any given time... thats a lot of beef."
],
"score": [
14,
6,
4
],
"text_urls": [
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} | [
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|
7h191n | What does the tax bill that was passed today mean? How will it affect Americans in each tax bracket? | Economics | explainlikeimfive | {
"a_id": [
"dqnds8l",
"dqnd1jl",
"dqng3i1",
"dqnku5x"
],
"text": [
"The tax bill is 500 pages long and there were a lot of changes still going on right to the end. It's not just an adjustment to the income tax brackets, it's a whole bunch of changes. As such there is no good answer to your question. The big take aways are: - Big reduction in corporate income tax rate will make large companies very happy. - Pass through rate change will make certain styles of business (law firms, hedge funds) extremely happy - Income tax changes are moderate, and are set to expire (though it's the kind of thing that might just always get re-applied without being made permanent) - People in high tax states (California, New York) lose out, and many of them will end up with their taxes raised.",
"None yet. It has to be reconciled with a vastly different house bill and then passed again.",
"Also: does this apply to 2017 taxes? Or does it start with 2018 taxes?",
"This article explains both the House and senate bills, including the proposed changes to your income taxes based on your income level. URL_0"
],
"score": [
21,
19,
5,
3
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"text_urls": [
[],
[],
[],
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"https://www.investopedia.com/news/trumps-tax-reform-what-can-be-done/"
]
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"url"
] | [
"url"
] |
|
7h1duo | This video about fluid motion | [Video is here.]( URL_0 ) The guy injects dye into glycerin and swirls it around, making it smear, then *reverses*, making it revert to its little pocket. HOW? | Physics | explainlikeimfive | {
"a_id": [
"dqnhmvg"
],
"text": [
"Imagine the dye not swirling and tumbling around like a normal liquid but moving in smooth simple strips, so you can imagine that after swirling it around one way then exactly copying it back the other way (this is important or it doesn't work) the first motion is undone. It works through laminar flow which is provided by the viscus liquid, (turbulent flow which you're used to is chaotic and effectively unpredictable, you could never reverse the movement). The color change is the same as mixing dye in normal liquid, the molecules of the color are brought close enough to each other so the colors blend together into the new color. They however aren't chaotically mixed with each other like in normal liquid (they will start diffusing together if left though so you have to be quick). In simplest terms they simply pushed the dyes and then pushed them back like they were separate. Look up laminar flow if you want to learn more."
],
"score": [
3
],
"text_urls": [
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} | [
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"url"
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7h1fdt | Why we feel cold at first when we touch something really hot? | Biology | explainlikeimfive | {
"a_id": [
"dqne29r"
],
"text": [
"So we have receptors for hot, cold, and pain in our skin. Usually they only trigger when their normal conditions are met. However, if a very strong stimulus triggers both hot and pain, for some reason, cold is triggered. If you wanna know more than that, good luck."
],
"score": [
3
],
"text_urls": [
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} | [
"url"
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"url"
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|
7h1idy | Why do both fission and fusion produce energy? | Fission breaks atoms apart, and fusion combines them (as does the Sun). How can they both produce so much energy when they are "opposite" processes? And where is that energy actually coming from? | Physics | explainlikeimfive | {
"a_id": [
"dqnezim",
"dqneyba",
"dqngmlu"
],
"text": [
"It depends on what is fused and what is fissioned; for example if you fissioned helium into hydrogen, you would lose energy. I believe Iron is the tipping point, and is the most stable element. So if you fuse two elements into something below Iron, energy is released, and if you fission an element into products above iron, energy is also released.",
"They both produce energy, but only under different conditions. Fusion produces energy when small atoms are involved, and *requires* energy with large atoms. Similarly, fission produced energy with large atoms, and requires it with small atoms. Eventually, they meet in the middle at iron and nickel. [This graph]( URL_0 ) essentially shows the how tightly protons and neutron are bound together in various nuclei. Reactions that go up the hill release energy, until they get to iron and nickle at the top.",
"Fusion only releases energy until you get to iron, the 26th element (though isotopes up to Fe^56 are produced in a normal star). Fissile atoms start around radium, element 90, as an isotope Ra^228, but for maximum sustained fission you need something more like U^235. It's partly about how numerous and glommed together the neutrons and protons are, and odd-numbered isotopes are usually more fissile... U^238 releases neutrons that have less energy than the one that caused the break, so it can't sustain a chain reaction the way U^235 can. The energy in both cases is the binding energy of the atom, but the atoms being fused are way off on the low end of the Periodic Table, while the atoms being split are way off on the high end. (Since fusion starts to *cost* energy instead of *releasing* energy around iron, atoms above iron aren't made in normal stellar fusion. The extra kick from a supernova is needed to convince the lower elements to fuse into the elements above iron.)"
],
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10,
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"https://upload.wikimedia.org/wikipedia/commons/5/53/Binding_energy_curve_-_common_isotopes.svg"
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