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5unnuc | What is No Mans Land and was it the best tactical decision? | It seems crazy to me that soldiers would just walk straight up to machine guns and the enemy. What did this achieve? I don't see how this would work unless the goal would to be to run the enemy's supply out but even then that seems mad to basically sacrifice your troops in exchange of the enemy's ammo. Don't know much about history so excuse my stupidity! | Other | explainlikeimfive | {
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"It wasn't a tactical decision so much as something that just happened. To understand the tactics of WWI trench warfare on the Western Front, you have to think about the situation and the objectives of the combatants. The initial phase of the war, right after the invasion of France by Germany, was very dynamic with battle lines and units moving all over. Once the French/British halted the initial German advance, however, the Germans decided to dig trenches to fortify their positions, as they were still deep inside France and did not want to be driven back by Allied counterattack. The Allies were then faced with the choice of either assaulting German trenches from the open (i.e. suicide), defending from unfortified positions (would get decimated by machine guns and artillery from German trenches), or building their own trenches facing the Germans to ride out German artillery and machine guns while blocking any further German advance. They chose the latter. So now you have two armies, each with lines of powerful trench fortifications facing each other. Each army wants to advance, but the enemy's trenches are lined up all along the front, so the only way forward is through enemy trenches. For each army, retreat means defeat. If you were the general charged with advancing your lines in this situation, what would you do? The only real solution is to charge the enemy trenches with a large number of men all at once, hoping to overwhelm their defenses before you lose too many soldiers. As it turns out, trench defenses were so strong that this rarely worked. But they still tried, because endlessly sitting in a fortified position that is not pressuring the enemy will not win you a war. In the end, innovations were made in tactics that allowed the attacks to succeed more often. Mainly, they became very good at laying curtains of artillery bombardment (called barrages) just in front of their advancing soldiers. Defenders could ride out artillery in underground shelters, but they couldn't do that and operate machine guns at the same time. So if infantry managed to arrive at an enemy position very shortly after their artillery stopped shelling it, they could advance without taking too much machine gun fire. Tanks also helped provide advancing soldiers with some cover. But ultimately there is no other way to take territory than walking straight up, and it's tough cookies if the enemy has a very fortified position!"
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5unoa1 | What's the difference between a militia and a gang? | Other | explainlikeimfive | {
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"A militia is a group of armed civilians organized to protect a city/region of a State from an external threat. A militia is under the control of the State government and can be nationalized by the Federal Government as an additional line of defense for invasion. A gang is group of armed civilians who actively participate in criminal activity and defend a region of territory (normally within a city) from other gangs and police so that they have an area to conduct their illegal activities."
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5unoxb | How does an Even Horizon work and how does it affect the space-time around it? | Pretend I'm a really dumb 5 year old | Physics | explainlikeimfive | {
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"It's (probably) a coordinate singularity on the way to the true, gravitational singularity within the horizon. It's a (changing as the hole gains or loses mass, spin, charge) region which defines the point of no return, where spacetime curvature is so extreme that all directions point inwards to the singularity, and even light won't be able to escape. Just beyond that is the photon sphere; the shell of stable photon orbits where light can orbit the hole. Outside of that, in a realistic black hole is something called the ergosphere, in which spacetime itself is being \"dragged\" along with the rotation of the black hole. From that region all the way out to the Static Limit, a stable orbit without constantly expending energy is impossible. Those are the \"special features\" of a rotating black hole. The result is really complex, but to an observer at infinity watching a particle fall into the hole, they'd see signals from the particle redshift all the way to black as it approached, then reached the event horizon. The distant observer would never see the particle pass the event horizon; the intervals between signals would just become arbitrarily large. If the observer instead decided to fall into the black hole, they'd eventually reach a point at which the gravity on their feet, and the gravity on their head would have a gradient of thousands of Earth gravity's... and they'd be strung out into a long, incandescent string of particles falling into a decaying orbit around the hole, eventually falling through the event horizon in its own proper time."
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5unvey | Why aren't banks held responsible for fraud or at least tracing the money? | So we typically hear about a fraud where the money is transferred outside the United States and it's suddenly untraceable and unrecoverable. Why is this possible? Doesn't the sending bank know what account it went to at another bank? That just may be a waypoint to yet another account, but eventually the money is in an account associated with a person and they try to spend or withdraw it. Doesn't that mean we should know exactly who had the cash at every step and also who had it last? They're all now subject to prosecution. If some schlub is laundering the money for a criminal, can't we arrest this person and force him to flip on the criminal? If accounts are being opened fraudulently (fake IDs, etc), can't we require insurance or minimum standards to avoid? Can't we blacklist banks that are repeat offenders and say they're no longer allowed to do business with banks on the whitelist? "Follow these rules in order to do business with the West?" Here are some "grandma scams" where "the money is gone": * URL_1 * URL_4 I found these ELI5, but they don't seem to address my question: * URL_2 * URL_0 * URL_3 | Economics | explainlikeimfive | {
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"With the grandma scam you link, she is sending a money order, which is pretty much cash. It isn't like a wire transfer between banks. So what law is being broken and who should be enforcing it? With a foreign bank it becomes a jurisdiction issue. Different countries have different rules and laws.",
"Money orders are over the counter and small amounts I believe. Usually these are kind of no questions asked. The Wells Fargo representative letting her wire the $10k is bizarre to me. When I was a teller, we were told to just pay extra attention to what old people do, especially if it was unusual, because they are a target for many scams. It's usually not that hard, because they are very routine (like every Tuesday at 10AM on the dot withdraw $100 and go get their hair cut or something) and anything unusual sticks out like a sore thumb. If one of our regulars came in asking for a $10k loan to wire it immediately would have been a huge red flag. To me, it seems like a pretty poor job on the Wells Bank in the first story, but doing a bad job isn't fraud. Now, wires are dangerous as well because they can be done anonymously through cash centers, where the recipient can take the money immediately with no ability to trace it back. Also, some countries have privacy laws that prevent US authorities from accessing information as to where the money went. It's not a question of the banks, they'll turn over any information the US tells them to, it's whether the countries allow US regulators into their country. And foreign policy isn't as simple as blacklisting a country because it isn't doing enough (scam is probably still illegal there) to prevent people in the US being scammed for a couple thousand dollars at a time."
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5unwcs | Why are most drywalls always closed off (preventing convenient access to pipes, insulation, wiring, etc.)? | As a young homeowner, it baffles me as to how inconvenient, challenging and difficult it is to access things behind a typical drywall. Why is that? Are our walls simply "closed off" for aesthetics? My downstairs bathroom is poorly insulated. Buying the insulation is the easy part, but it requires cutting the wall down, adding the insulation itself, patching the wall back up, sanding, re-painting, etc. Another example: my upstairs tub once had a leak where it was dripping onto my kitchen ceiling. Fixing the leak required taking down my cabinets, cutting a significant part of my ceiling, fixing the pipes, patching up the ceiling, reinstalling the cabinets, and painting the ceiling for aesthetic cohesion. | Other | explainlikeimfive | {
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"There are quite a few reasons for this, but what it comes down to is the balance between how often those things need to be accessed vs costs of construction and the routing of plumbing etc. I have a lot of experience building homes and believe me, there are lots of variables to consider when building a home. Here are some things that are required to be accessed: 1 - Electrical - anytime there are wire splices or connections, there must be an access box which is easily accessible by removing the cover plate (it could be located in an attic, but the box is still easily accessible from the attic) it is against code in CA to have wires connected behind drywall where you would have to remove drywall to access them - 2 - Plumbing cleanouts - almost all places where there is a drain, a cleanouts must be easily accessable in case the drain clogs - 3 - misc \"data\" boxes - these have similar rules to electrical - 4 - Jacuzzi tub pumps, water heaters, garbage disposals, water heaters, home AC and heaters - all of these must be accessible and properly vented. Water pipes, drain pipes and wire runs do not have to be accessible because they very rarely need to be accessed. Yes, it sucks when there is a leak, but that occurs very rarely compared to other problems. Having all the pipes and wires accessible would create huge problems with their functionality. If all plumbing pipes had to be accessible, you would not be able to run them to the points in the home they are needed, like the valves that feed your faucets, toilet or shower. It's possible, but would be very tough to do. It might also add distance from your water heater, increasing the time for hot water to get to your faucet. The same thing goes for electrical. If all these things had to be accessible, you would have cover plates all over the house and walls. You may also have water intrusion problems if these cover plates were on the exterior. As a contractor/ handyman I would love if all this stuff was accessible, especially shower valves (those suck to replace, they are often behind tiled surfaces and stucco walls, very inconvenient! Edit: I think someone also mentioned insulation. Having all these things accessible would compromise the insulation of you home. Almost anywhere there is an access box in an exterior wall very little insulation can be installed. Also, on a really cold or hot day, you may notice a slight draft coming into the house through access boxes on exterior walls. Home are intentionally designed to \"breathe\" so some fresh air can get in. Much of the design and construction of a home is balancing many factors. By making one thing better, something else usually suffers."
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5uo4fp | How does the "ping" command on the terminal actually work? | Technology | explainlikeimfive | {
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"Simpler explanation: I write you a letter that says \"This letter was sent from < my address > on < date > and < time > . Please send me a letter back as soon as you get this, with the exact time and date you received this. You follow the instruction and send the second letter back to me. When I get your letter, I know exactly how long it took for the letter to get to you, and how long it took the letter to make the round trip. If I don't get a letter back in a reasonable amount of time, I know that something has gone with the postal service between my address and yours. Now imagine that we're two computers, and instead of a letters we're sending data packets. That's basically how 'ping' works."
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5uop2m | Why is it that Asian Countries tend to score much higher than the West in terms of Education, yet it seems the most innovation in almost any scientific/technological field comes from the West? | For a start I'm willing to be wrong about all my assumptions. I always hear that Asian Countries tend to have the best educated people. the highest literacy scores, maths scores, IQ etc. It may also be that in many niche scientific fields some massive breakthroughs have come from Asia - I really could be all wrong. As an example - I always heard that Japan had better technology than the US for mobiles in the early 2000. Media from the 80s/90s always seems to suggest Japan was way ahead of the West technologically, the same goes for South Korea, yet America now dominates the mobile market, as well as the software market. It really does seem that all the great breakthroughs in Science/Technology originate from the West. Am I right in these assumptions? If so what cultural differences may explain why this is the case? | Technology | explainlikeimfive | {
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"Many of the competitive industrial players are in the West so the best and brightest Asian students are drawn there. Likewise, a huge majority of scientific research and funding is in the West, so their scientists and STEM people are drawn there. However, the number of power global firms based in Asia is growing and the advances they have made in technology over the last 10-20 years is astounding. You say that much of the technological advance comes from there, but look at what Asian countries have done for consumer electronics (LG, Samsung, etc), Tech commerce (Alibaba), energy, banking, and transportation. All of the big advancements in high-speed rail are coming out of Asia right now and their infrastructure expertise is amazing (their contractors and engineering companies are gaining market share all over the world). 10 of the top 30 companies in the world (be revenue) are Asian."
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5uopka | how did we document time before Christ? | I know that B.C stands for before Christ, and A.D stands for Anno Domini ( or how others prefer " after death ") but before Christ was born did we use any epochs, how exactly did the human race document time? | Other | explainlikeimfive | {
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"The same way we do now. The invention of AD and BC was popularized by scholars to make the birth of Christ an important part of history however how we actually track time (24 hours in a day, 30(ish) days in a month, 12 months and a year) did not change. Different cultures used different starting points as their \"beginning\" but they just counted up years. This happens every so often in different cultures. Something they deem super important happens and they make it the new start of the calendar. Like in North Korea they start the calendar in 1912 because that is when Kim Il-sung was born. It is currently year 106 in North Korea."
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5uouz9 | Why do cell phones always get super buggy/get slower when a newer version of the comes out? | Technology | explainlikeimfive | {
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"The cell phone is built for the OS that was out when it was released. As a result, newer OS will not run as well as the one that the cell phone was built for. Also, the newer OS usually is more memory-intensive, so the phone naturally runs slower. Think of it like trying to run Windows 10 on a computer meant for Windows Vista. Even though Windows 10 is significantly superior, it probably would slow down the computer because it uses lots of memory.",
"To build on what u/sizzling-bacon said, a lot of smartphone users don't back up data and start fresh when they upgrade the OS. Easier to run smoothly from a fresh start, but even that only gets you so far.",
"It's known as [planned obsolescence]( URL_0 ) and is both a direct result of unchecked rampant capitalism, and an example of something completely unsustainable. We live in an awesome time right now. Our grandchildren are screwed, tho.",
"As an android user with a Moto X, the only effect I've seen from updating my OS is vastly improved battery life. Never have I run into planned obsolescence, is that a thing other manufacturers do? I heard apple does it.",
"I am more or less convinced that it's planned obsolescence - the updates they give out near/after a new product launch \"breaks\" older phones, so that their owners will get a new phone. In reality, there is absolutely no good reason a phone should get slower or become buggy just because of age (well, where age is \"small number of years\"). If it does, it's either planned, or the software is genuinely awful."
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5upa9s | why, in the UK, student loans are seen as a bad thing? | Economics | explainlikeimfive | {
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"I think the reason is that we seem to have regressed. In other words we've gone from free tuition 20 or so years ago to £9000 a year. Couple this with the possibility that more than 50% of students may never pay back their loans, thereby leading to a loss to the taxpayer (when the measure was meant to save money), and the fact that many more students are being sent to uni to do degrees which will not boost their earning potential in any major way, and it doesn't seem to me that you have a decent system."
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5upi9u | Why have Canada & USA been more successful at integrating Muslims than Europe? | Other | explainlikeimfive | {
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"Muslim immigrants to Europe were primarily unskilled labor, while Muslim immigrants to the U.S. were primarily professionals. So what happened is that Europe developed large, lower class Muslim communities while the U.S. tended to have scattered families of Muslims with a few middle-to-upper class Muslim communities.",
"I think the biggest reason is that we have so few Muslims to begin with. Muslims make up approximately 1% of the US (*far* less, incidentally, than most Americans think). It varies by country, naturally, but Muslims make up around 6% of Europe. It's easier to not integrate as much when you have such a large community already there."
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5upjg3 | Why is it so hard to emulate (for example) PS2 games smoothly in a "basic" computer even tho they're way more powerful than the console? | Technology | explainlikeimfive | {
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"The emulator has to translate the CPU instructions of the console and game you're emulating into something your own computer's CPU can understand. Then, the emulator also has to take your input from the computer and turn it into something else that the emulated CPU can understand as well. This all requires a TON of processing power. A very good analogy is to imagine the console and computer are two different people who are talking to eachother, but speak two completely different languages. In this case, the emulator is the translator, which can be slow.",
"There are already a lot of good answers here, but I wanted to add something that a lot of them seem to be missing. Yes, it requires a *lot* of overhead to convert the instructions used on PS2 hardware to normal PC hardware, but there's something else that makes it difficult as well. The ELI5 of that being, imagine how hard it would be to translate someone very, very quickly speaking Mandarin at you, to someone who only speaks German, while you yourself are a native English speaker. And you have to be exactly correct, and really, really fast. However, what people are missing is the fact that the PS2 (or any console) has a very specific way of doing essentially everything. The memory is laid out in a certain way, disks are accessed in a certain way, instructions are executed in a certain way, etc. And, because console games are developed to only run on that *specific* console, they will often take advantage of those things. To borrow my metaphor from before, two people speaking in the same language to each other will very frequently use idioms and common sayings, that are total nonsense to a non-fluent speaker! Being able to translate those idioms (or, in the space of emulators, all of the strange quirks of memory and hardware) perfectly, into something that a non-speaker understands, is imperative in being a good translator. The same is true of the emulator. If a game takes advantage of a certain way of handling memory on a console, that same handling method *must* be present in the emulator, or the game will not function. And some of those special methods are inefficient to implement, so it further slows down an already arduous translation task. EDIT: Obligatory \"this blew up.\" I recommend checking out r/emulation if you want to learn more in depth about emulators! Also I recommend [this]( URL_1 ) article on how hard it was for the most prominent Game Cube emulator to boot a specific game. Further down I also link [this]( URL_0 ) talk on why the PS4 is an incredibly weird machine, and so would be extremely hard to emulate.",
"Your computer has to use software to emulate the hardware and OS of the device, then run the game software within that software. It's like Gameception. A good rule of thumb is that you need a device 10-20x faster to emulate an old device, which is why we can only emulate very old consoles currently.",
"The difference in hardware is the issue. The PS2 game was developed to run on PS2 hardware. This hardware natively supports a set of instructions; simple instructions like move, add, or subtract are widely supported, but instructions like division may not be. The difficulty is when the PC doesn't support all the same instructions as the PS2. When an instruction isn't natively supported, it can be emulated using a large number of other instructions. Even a subtle difference can require a large number of extra steps to accommodate. The downside of emulation is that the number of instructions to be completed necessarily increases, often dramatically. What it really boils down to is optimization.",
"The PS2 in particular takes more power to emulate smoothly due to the complexities of the Emotion Engine. It's much less like a normal computer than the Gamecube, and even now we still have to use hacks and workarounds to get some games working properly. Some games (most notably, the Ratchet and Clank series of games) are virtually unplayable. Edit: (According to u/JMC4789 this particular issue was not due to the EE! That being said, emulating such a system is still a chore when compared to the relatively more normal Gamecube or Wii, which had CPUs based on the Power architecture).",
"URL_0 Read this. It tells you exactly why.",
"It's like running a Virtual machine on your computer. Sure you can run multiple OS at the same time but you need to split the ressources (processor, RAM,...) your computer have between the running OS. Emulating a game is running an emulator that translate from your computer language to the target console OS laguage, then run the game OS to finally run the game. You need to split your ressources through your computer, the emulator program, the game OS and finally to the game. So if you try to run a PS3 game, you need to emulate the PS3 CPU (at 3.2 Ghz), you need to emulate the memory (256 Mb RAM and 256 MB VRAM) just to run the OS. After that you need to run the actual game and as others have said, your CPU use a set of instruction that he understand which is not the same set of instruction the PS3 understand. Finally, once everybody understand everyone, The emulator need to translate the video output of the PS3 for your GPU driver can understand and display it on your screen. It's easier for a Xbox one to emulate Xbox 360 game since the system architech are most likely the same people and they have acces to the actual build of the 360 and they have a better understanding of the machine.",
"^(I don't think metaphors made using \"languages\" really convey the difficulty of emulating one piece of hardware on another, because we already use the metaphors for \"languages\" in computing, and they equate to programming languages. Converting from one coding language to another can be a challenging task, akin to translating from archaic Latin to modern Mandarin, but at least you're still communicating from the same species to the same species - human to human. We generally think the same way, our brains function the same way, and we have lots of experience doing language translation. Using language translation as a metaphor for computer only really gets us as far as trying to convert Cobol to C++ while still using an x86 system.) ---- **ELI5**: Imagine you put your brain into a centipede. Your brain is way more powerful than a centipede's brain. But you have no idea how a centipede's body works. You've never had to move dozens of legs simultaneously (or in a rythmic pattern) before. The way a centipede moves is as foreign to you as the way it thinks and communicates. This is so far beyond simply translating a language. This is translating an entire way of thinking and perceiving and organizing the world around you before you can even begin to hope to understand centipede communication. To do anything as a centipede, you'd basically have to learn to emulate a centipede's brain. Imagine how difficult that would be for you, even though your brain is probably several dozens of orders of magnitude more powerful. A computer basically has to emulate the brain *and the body*, *and the language* of the centipede, *without fully understanding every detail*\\* about how the brain and body works, and the computer is only, maybe, an order of magnitude (or two or three) more powerful than the system it is trying to emulate. ---- \\*^(Emulators often have to do a lot of *guessing* achieved via reverse-engineering, but we don't usually have complete engineering plans of the hardware that is being emulated. That lack of complete understanding is often why emulators don't get everything \"just right\" - because they're doing a poor job of pretending to be a centipede. Sometimes, even when we do have complete understanding, hardware limitations prevent perfect emulation. Just like you might completely understand a dance move in theory, but not have the actual skills to pull it off in practice. Even if someone gave you a complete schematic of a centipede's brain, you probably still wouldn't be able to emulate it in real time because even as simple as it is, it would still be mindboggling complex, and your brain couldn't handle it even though your brain is significantly more complex.)",
"Part of it can depend on which game you are talking about. Final Fantasy X, for example, is something I can run on my rather barebones laptop, and I can play Kingdom Hearts with some graphical glitches. But Wild Arms 3, which by all appearances should be easier to emulate, essentially doesn't function.",
"Imagine this, you manage to get a time machine and travel back in time to the the 1500s and try to give science knowledge to a Portuguese navigator. You have more knowledge than him in various aspects, science and so on, but the language is a big barrier. It's the same with the console, it \"talks\" in a language not understood by the current processors"
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5upl74 | Why can humans digest a whole variety of plants, but not grass? | Biology | explainlikeimfive | {
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"Humans actually can't digest a wide variety of plants. Our stomachs cannot break down cellulose, which means that there is no plant we can truly digest. The edible ones are just plants that we happen to be able to get nutrients from without needing to break down cellulose. Grass would require cellulose digesting to get much out of.",
"i'd answer your question in two parts, as you also seem to have a mistaken understanding behind your question. humans can only digest a very small proportion of a plant. your everyday cow/grass eating animal can't digest much of grass either, it relies on its gut bacteria to digest it for them, and then digest the sugars that the bacteria produce. we lack these gut bacteria. your poop is solid from all the undigested plant material. secondly, humans cannot digest a wide variety of plants. there are what over 30000 species of plants, and in your average supermarket no more than like 20-30 different plants, bred over many generations to become more palatable."
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5upmht | What is the mathematical constant, "i?" And, what is the importance of it? | Before you start typing away, I am well aware that the constant "i" is in fact √(-1). What I am really asking is, what IS it? Unlike a constant like 1, I can't really think of what √(-1) IS. I can imagine 1 apple, but √(-1) apples doesn't really come to mind. I mainly came to ask that question when I began to research more into the Mandelbrot set. Of course, I only understood bits and pieces as am I still only a AP Calculus BC student (for those of you who are non-American, Calculus BC is Calc I, and Calc II. You cover derivatives, limits, integrals, some (basic) differential equation stuff, and sequences & series). To my knowledge the set has to do with complex numbers, which is why I went to ask this question. As for my other question, what are some of the applications of "i?" While your at it, if there are any proofs that prove something we already knew using "i," I wouldn't mind seeing/hearing about it. Although, that might still be over my head... Lastly, if you have any suggestions for books on this topic that wouldn't be way over me then I'd love to read it. Whether it's about the Mandelbrot set, "i" or anything else related to math. Thanks! | Mathematics | explainlikeimfive | {
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"Complex numbers can be written using two notations. Polar which is a magnitude and an angle, and rectangular. Rectangular gives the magnitude along the real axis and separately the magnitude along the imaginary (i) axis. If you took both notations together, you'd see that the magnitude and angle in polar form exactly matches the hypotenuse formed by the magnitudes from the real and imaginary axes in rectangular form. If you are still confused, I'd suggest researching more on complex numbers. They are a very useful mathematical construct especially if you plan on studying any form of engineering.",
"There's a reasonably simple way to get intuition about what exactly 'i' is. Let's say you have 2d space, so you have the origin, 0, and you have an x-axis and a y-axis. You can label points by calling them (*a*, *b*), which means go *a* units along the x-axis, and *b* units along the y-axis. But let's call the x-axis the real axis, and the y-axis the imaginary axis. And instead of calling a point (*a*, *b*), let's call it *a* + *b*i. There's no reason why we can't do this, all we're doing is changing names. We call these numbers the complex numbers, and they have the property that when you multiply *a* + *b*i by i, you rotate that point by pi/2 radians(90 degrees) anticlockwise. That's essentially all we want, and really, that is exactly what i does, and that's exactly what makes it useful. That's what the number i is, it rotates the plane 90 degrees anticlockwise, just like how multiplying by -1 rotates the plane by pi radians (180 degrees) anticlockwise, and multiplication by 1 rotates the plane by 0 radians (0 degrees) (or 2pi radians, or 4pi radians, etc). Complex numbers allow us to look at this 2d plane, and give us the freedom to rotate it and scale it however we want in a way that's much simpler to write down than matrices. If you've met matrices before, then it is fairly easy to get an idea of what i is (and complex numbers in general) by looking at certain 2x2 matrices. The equivalent of the complex numbers in matrices work exactly the same way as normal complex numbers. When you multiply them, they rotate the plane by some angle, and scale a vector by some amount. As for the uses, there are many, and since I'm not familiar with the US education system, I'm not sure which examples are best to give, but I'll try to give one or two. Maybe you are familiar with the trigonometric functions, sin and cos. Maybe you've also been asked tedious questions like \"show that cos(10x) = blah blah blah\". If you just go at this problem directly, I'd imagine that you'd go about using double angle formulae and the like, and slowly working your way towards the answer. Complex numbers make this all so much easier, because you have the result that e^(ix) = cos(x) + i sin(x), where x is a real number. So if you're asked to find, for example, cos(10x), you know that e^(10ix) = cos(10x) + i sin(10x), so cos(10x) is the *real part* of e^(10x). You also know that e^(10x) = (e^(x))^(10) = ( cos(x) + i sin(x) )^(10), and you can easily find this using the binomial theorem, and you know that the real part of this (the part that isn't multiplied by i) is equal to cos(10x). Complex numbers make all sorts of tedious trigonometric calculations incredibly easy. Another example is in linear differential equations. I'm much less sure that you'd have seen this (but maybe?), but I'd be happy to try to explain how complex numbers make this easier if you're interested."
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5upnaj | why are airline crash victims described as souls typically when most other deaths are described as lives or people? | Other | explainlikeimfive | {
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"souls meaning living persons. which is passengers and crew airliners carry corpses too and they're held as cargo, not passengers. when you have a crash and you end up with 100 bodies, you need to know how many actually died in the crash.",
"Airplanes during distress may be asked to \"say your souls\" in order to provide an accurate count of the number of passengers and crew. This is related to nautical terminology that also relates persons as \"souls\". Airlines and naval vessels have many other areas of overlap in terminology."
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5upu93 | If no normal person can withstand water boarding can't it be used to get anyone to admit to doing anything just to make it stop? | Other | explainlikeimfive | {
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"confessions made under torture (any torture, not just waterboarding) have been deemed unreliable because there are way too many false positives. people say whatever it takes to make the pain stop [CIA torturers themselves]( URL_0 ) admitted this, but continued(s) to use it anyway, because torture is fun i guess",
"Yes. That is the problem with torture in general. It isn't a way to discover actual truths.",
"Specifically because it will get people to admit to doing anything to make it stop. The information gained from torture is not useful because it is not truthful. They just want the torture to stop so they will tell you what you want to know, not what you actually need to know.",
"yeah that's pretty much one argument against torture. that it's ineffective and people will just say anything to get it to stop."
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5upz0e | Why is one side of aluminum foil matte and the other side shiny? | Other | explainlikeimfive | {
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"Because they do the final rolling with two thicknesses. The inside surfaces are not as highly polished as the outside surfaces. See this [video]( URL_0 )",
"\"Frequently Asked Questions Which side of Reynolds Wrap® Aluminum Foil should I use, the shiny or the dull side? Actually, it makes no difference which side of the aluminum foil you useboth sides do the same fine job of cooking, freezing and storing food. The difference in appearance between dull and shiny is due to the foil manufacturing process. In the final rolling step, two layers of foil are passed through the rolling mill at the same time. The side coming in contact with the mill's highly polished steel rollers becomes shiny. The other side, not coming in contact with the heavy rollers, comes out with a dull or matte finish. The exception is when using Reynolds Wrap® Release® Non-Stick Aluminum Foil. The non-stick coating is applied during manufacturing to the dull side of the foil. Always place the non-stick (dull) side toward the food.\"",
"I was told in culinary school that if you wrap something with the shiny side towards the food it'll reflect more heat back at the food and cooks faster. Meaning for things you want to cook slower, like a braise, you could use the matte side. Not sure of the validity, I had a few really dumb instructors in school and don't remember which one told me this.",
"They are put through the mill 2 rolls at a time as there is a minimum thickness that you can roll with a foil mill (the rollers are much thinner than a hot mill, including the backup rollers). As /u/Ferk_a_Tawd says the shiny bit are where the foil surface touches the rolls. Interestingly after they come out of the foil mill they are put into a machine that has rotating saws that cuts the foil to the finished size, but the waste from this process is cubed and sent to paint manufacturers to use in metallic paint for cars :)",
"I was always told that the matte side was non-stick. Is my life a lie?"
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5upzpq | Why most of the games show posion as in green colour? Is it true? | Whenever i played lara croft, assassin creed, far cry etc. i've seen examples of it. I wonder if it is relevant or random stuff? | Chemistry | explainlikeimfive | {
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"As mentioned before, the colour green is associated with sickness. Many people may also think about Chlorine when they hear \"poison\" - which was used for its poisonous properties during World War 1, and is a green gas. The substances used as rat poisons ages ago were also green. Modern poisons aren't necessarily green at all, they are usually colourless (poisons aren't very effective if they look obvious).",
"I believe that it is because we associate the color green with sickness. People tend to look green when they are sick, so it is an accurate representation for poison, something that makes you sick.",
"Keep in mind that a lot of these things are perpetuated because they are already established conventions. It's not like modern games like Assassin's Creed choose poison to be green because of arsenic or snakes or whatever; they do it because they know that players already associate green with poison. The convention probably stretches back a few decades at least; just like red = health and blue = magic.",
"Purple is also a common Poison color, especially in RPGs.",
"Yet another hazardous green thing was radium paint, used in luminous clocks and watches. It is the phosphor in the paint that produces the distinctive green glow, but the radium was dangerous to people working with it, in particular painters who would lick the radium brushes. And uranium glass, although generally not hazardous, also glows green under UV light. These may account for the popular depiction of radioactive substances as glowing green, and indirectly reinforce the use of that colour for generic 'poison'.",
"It should be added that Mr. Yuck, the face used since the 70's to label poisonous items, is also green. That might have had some influence.",
"Same reason ninjas are depicted as wearing black tights. It is a convention that had some reason to start and has been kept because we, the audience, accept the symbolism.",
"There are certain colors that are associated with disease and pestilence and green is one of them. Think of moldy bread covered in green and yellow fuzz. Infected wounds tend to ooze yellow puss, so a combination of that off white yellow color, and the creamy consistency of it is unappetizing because it usually signals decay or sickness. So colors like black, green, yellow, have associations with rot, poison, decay, infections, etc.",
"poison in real life can be any color or none, it's just color coded for convenience and ease of use",
"It's arbitrary. In dark souls and bloodborne poison is purple and green is endurance In Mario green is an extra life"
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5uqkug | Why does eating something help with an upset stomach? | I'm not talking about eating saltines, but often when I feel sick, if I eat something small, I feel much better. It seems counterintuitive to me. | Biology | explainlikeimfive | {
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"In the case of hypoglycemia one of the symptoms is nausea so you eat something , your blood sugar goes back up and you feel better"
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5uqm17 | When you turn the volume up on a radio or tv, what actually happens to the soundwaves? | Technology | explainlikeimfive | {
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"The sound wave [amplitude]( URL_0 ) increases. Sound is composed of compression/decompression waves in the air (or water, or whatever). If you change how rapidly the air gets compressed/decompressed, you change the pitch of the sound. If you change the intensity of the compression/decompression, you change the amplitude (or volume) of the sound.",
"An amplifier does not generally have adjustable gain at a circuit level. In other words when you create a circuit that amplifies a signal, it amplifies it a set amount, and adjusting the volume knob doesn't change these physical properties of the circuit. So most volume control is handled using either a potentiometer, a digital mixer, or a relay/stepper system. Potentiometers or volume pots are the most simple. It's a resistor that increases or decreases resistance as the knob is turned. The downside is that they can be fouled by dust, grime, grease, and wear and tear. If you've ever adjusted the volume knob on something and heard scratchy static, that's what you were hearing. Digital mixers adjust the output level in the digital domain. For instance in a 16bit PCM sound sample, 65,356 is the decimal value for the loudest possible sound IE the highest analog voltage. If you want to lower the output voltage, you simply subtract from that digital value and the DAC or digital to analog converter, simply goes with the lower and quieter number. The windows volume adjustment in your taskbar is an example of this. Lastly you have relay volumes which step through combinations of resistance by changing the path the signal takes through a circuit, causing it to increase or decrease at regular intervals depending on the state of the relays. They are complicated but offer a good compromise of actual voltage adjustment, without suffering from noise and dust. So you have your source, which could be a record player, or a CD player (DAC chip) which outputs at 0 to 2 volts usually which is too low to hear with headphones or speakers. That signal goes into a pre-amplifier which is where the volume control is usually done. This adjusts the voltages before they go to the final output stage which is the main amplifier. Then the main amplifier amplifies the signal however much it was designed to and a quieter pre-amp source causes lower volume, and a higher pre-amp source causes louder volume."
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5uqn3f | What happens now that we have a tweeting president who can just delete his own tweets? Isn't everything out of his mouth a matter of public record? | Please, not a question of politics here, just a technical question about who is responsible for maintaining the record of his statements. If he deletes a tweet, does it go on record? | Other | explainlikeimfive | {
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"This is exactly the reason why the founding fathers ensured that citizens would be able to make screen shots and have the right to retweet",
"I have no idea what you mean by \"on record\". There does not exist any record, or any requirement of keeping a record, of everything the president says. The President has a right just like every other citizen to use social media, and delete things from social media. So in simple terms, no one is responsible for maintaining a record of his statements.",
"[It's true that the President is legally required to preserve many different kinds of records he produces during the course of his Presidency. That might, conceivably, include tweets - but it depends on their content.]( URL_0 ) The President is required to preserve documents that > (A) includes any documentary materials relating to the political activities of the President or members of the President’s staff, but only if such activities relate to or have a direct effect upon the carrying out of constitutional, statutory, or other official or ceremonial duties of the President; because such documents actually belong to the United States, not the President."
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5uqppg | Why does water appear to be white when coming down from a tap really fast or a waterfall? | I'm sure it has to do with the way light reflects off the water particles at the speed they are going but i'm just curious to see what the true answer is. | Chemistry | explainlikeimfive | {
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"Those faucet are aerating the water. This spreads it out by putting a bunch of air in between it. Older faucets sometimes don't do this and the water is clear.",
"Almost any clear substance with a different refractive index than air will look white if broken up into a lot of small bits. Take water, foam a bunch of air into it so it's essentially a bunch of tiny water pieces, and it will look white. Take ice, normally clear, and break it up into tiny snow crystals, and it will look white. Take a piece of glass and shatter it, then sweep the bits into a pile. It will look white. White objects reflect all colors of light equally. The things I listed above are transparent, but light reflects off of them and refracts around inside them where they border on air. When jumbled up with air, incoming light goes in, gets bounced around, and comes out. This makes them look white."
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5uqtjj | Why do we need drugs to make us feel good and why can't our brains just release more dopamine? | Chemistry | explainlikeimfive | {
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"The production of dopamine has to be regulated. If it weren't, it would defeat the purpose of having dopamine. Dopamine is there to reward you for doing something *good* that increases your chance of survival (or at least, something that looks like something that increases your chance of survival to a brain that's been evolving for a few billion years). Imagine if your brain could just give you dopamine whenever you felt depressed. You wouldn't *do* anything. Generally speaking, if you're feeling depressed (but you don't have capital D Depression) it's because something happened that negatively impacted you. That feeling is supposed to motivate you to fix the problem, because feeling depressed sucks. So your partner dumped you and now you're depressed. That feels shitty. Solution: find a better, hotter partner and get some of that sweet, sweet sex dopamine (and make a baby to carry your genes, too). You see a shiny new car and know you can't afford it, so you're depressed. Solution: get a better job, making you more financially secure so you can afford that shiny new car (and become a fitter, more desirable parent, attracting hotter partners), and you get a nice \"I accomplished something\" dopamine fix. Basically, your brain is forcing you to be more capable of surviving and your reward for that is not feeling like garbage. If your brain just gave you dopamine whenever you felt like garbage, imagine the scenarios above. Partner leaves you? That's fine, your brain gave you dopamine so you feel GREAT and you sit in your house and never find a new partner and never reproduce and your terrible too-much-dopamine genes don't get passed on. Can't afford that car? That's fine, you feel fine - in fact, you're fine with not being able to afford *any* car. Or a house. Or food. And you're fine because *dopamine*. So you can see that dopamine *must* be regulated in order for it to do its job in your brain. Unregulated dopamine is a disaster. In individuals who struggle with addiction, that regulation is just a little off. With capital D Depression, due to a number of factors, your brain simple doesn't produce enough dopamine. Could be genetics, could be a trauma that you can't fix... For whatever reason, you have either too little dopamine or too many dopamine receptors. Because some drugs mimic dopamine, you can get that dopamine fix and avoid being stuck in Depression, as long as you're *regulating* your usage, otherwise you get stuck in the same problem of having too much and not being motivated to do anything. Or the more likely problem, your brain builds additional dopamine receptors, enzymes to remove it, and lowers production of dopamine so it can handle the artificially high amount of \"dopamine\" you've injected in an attempt to regulate its effectiveness, so you *don't* have the motivation problem. Then, when the high wears off, you have *less* dopamine than you did before, and more receptors that aren't getting activated, and you need still more drugs. Some people go for the more natural and \"safer\" method of triggering bigger releases of dopamine through seeking out more pleasurable or riskier behavior. Hence people who deliberately [skydive without a parachute]( URL_0 ) or [climb stupidly high buildings]( URL_1 ). Which *is* just \"releasing more dopamine\", but you have to kind of trick your brain into doing it."
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5uqup1 | reality show editing | I understand how reality shows are edited, often out of sequence to amp up the drama or to drive a particular story line, but... In a show like Hell's Kitchen, how do they get the interviews to match the action on screen? For example, there'll be some action on screen where Ramsay is ripping someone a new a**hole, and then it cuts to the "interview" where the contestant is responding or reacting to what's happening on screen, and that contestant is crying... If all of the interviews are shot after the episode is recorded, how do they match the emotion with what's going on? | Other | explainlikeimfive | {
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"The interviews segments are just as chopped up and manipulated as the rest of the show. They'll even mix and match portions of interviews from different episodes, completely different situations, to alter the story as they see fit."
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5uqx2t | If the first living beings reproduced asexually, how did diverse species came to be? Also how did sexual reproduction started? | I understand that the first living beings were unicellular organisms, prokaryotes, which reproduce asexually. If DNA was only "cloned" from one organism to form an offsrping, how did different species appeared? I'm guessing it has to do with some kind of genetic mutation, but even then I can't wrap my mind around how sexual reproduction started. | Biology | explainlikeimfive | {
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"Well it helps to look at species that have various forms of reproduction between asexual and our form of sexual reproduction. For instance prokaryotes can't go through meiosis but can incorporate new DNA from other prokaryotes. Then there are some yeast cells that can reproduce asexually or sexually when under great stress. Then there are various hemaphrodites in the animal kingdom. Then there are species that can change sexes like clownfish. Then there are true sexually dimorphic species like us. Do you have a more specific question. Edit: Also it helps to think that sexual reproduction (meiosis) is really just a modified version of asexual reproduction (mitosis) done twice. Then you just have specialization of specific parts and genders overtime.",
"DNA never divides perfectly. It gets spelling errors, sometimes it gets extra bits, and sometimes bits get taken out. Over a couple billion years these changes added up and lead to diverse species. Something important to note is that sexual reproduction only shuffles genes. It does not create anything new. The only way to do that is to have it be created in a mutation when DNA replicates itself. And something else is that even bacteria have sex of sorts where they create a bridge between their cells and exchange DNA.",
"Look at the result. Sexual reproduction results in the combination of mutations from two separate lines of ancestors. With asexual reproduction favorable mutations favor descendents of that one organism. So evolution consists of one favorable mutation after another, a slow process. With sexual reproduction mutations from across the species can combine into one individual. Evolution is much, much faster. Bacteria actually have ways to share DNA. That is how antibiotic resistance spreads. It is not sexual reproduction but it works. Speciation occurs when individuals in one species no longer interbreed. They can be living across a mountain range, a river, or oceans. Gradually mutations accumulate. Eventually they can no longer interbreed."
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5uqxcf | How do snake tamers work? What goes on between the tamer and the snake ? | Biology | explainlikeimfive | {
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"Snake charmers actually aren't really taming the snakes at all. The snakes aren't taught anything. What's going on is the snake is basically scared and is responding as it would to a threat. It lifts up it's head to look threatening, and if its a cobra it flares out its flaps (which is what they do to intimidate predators) and it follows the movement of the charmers' flute. Snakes are kinda deaf so the music is not having an effect on them, but they do basically peak their heads out of the basket in the first place to investigate what the hell is going on. The charmer also keeps a fairly safe distance and keeps the snakes in a covered basket at most times. The snakes are fairly chill, and don't really want to bite anyone. But some snake charmers will rip out the snakes' fangs or tie their mouths shut or stuff things in their mouths, to keep themselves safer. I imagine it's probably an animal rights nightmare, the snakes don't sound like they're having a good time at all. India (where the practice was probably invented and is most popular) has made progress in recent years on the issue of animal welfare, they declared cetaceans (whales and dolphins) to be \"legal persons\" with rights and outlawed ocean parks that show off trained dolphins/whales. URL_0"
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5ur25q | How does the GDP work and how is it calculated? | Economics | explainlikeimfive | {
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"GDP is calculated as Consumption (total spending in the economy) plus investment (things like homes and equipment businesses use, goods which generate future income) plus all government spending (except for transfer payments, like social security or welfare) plus the trade balance (Exports - imports, which is currently negative) This is abbreviated GDP = C + I + G + EX - IM All of this over a year's time. The government collects the data by sending out surveys to the appropriate sample size of US citizens. It is quite complicated when it comes to the details. Imports are subtracted because imports are already counted in consumption or investment or government purchases and you don't want to count them. GDP is a proxy (or indicator) of the nation's economic strength. Normally, you want to look at real GDP, which is adjusted for inflation, unlike nominal GDP. This lets you compare the true economic change in the economy over time. Real GDP per capita is also very useful because it tells you how much income per person you have in your economy in addition to adjusting for inflation. Real GDP per capita is a proxy for how well off our citizens are, their purchasing power"
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5ur3dn | Are saltwater-amphibians possible? | Biology | explainlikeimfive | {
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"The crab-eating-frog is the only known saltwater amphibian. However, it cannot live in saltwater permanently and can only tolerate 2.8% salinity, which is less than the oceans'. They live in mangrove swamps in SE Asia.",
"amphibians cant remain in saltwater for any extended period. Amphibian skin is permeable, water and even air for breathing can pass through it. through osmosis, water is taken out of the frog so that the water to salt ratio is the same in the frog and the ocean water. since the frog has very little salt in it at all, the frog will have all of its water pulled out of its body until the frog is shriveled up.",
"This is an interesting question that I never thought of. It doesn't seem to me to be a good question for ELI5 though. Maybe more like askscience or a biology channel.",
"The answers here are totally blowing my mind. It was my understanding that the first terrestrial vertebrates were amphibian analogs. Did they evolve in the limited, not connected, freshwater portions of the world? Is there a lake zero for all terrestrial vertebrates as they could not swim in saline water? how did they spread all over the world without being able to enter saltwater? edit: spelling"
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5ur9ks | Why can't humans hibernate? | Biology | explainlikeimfive | {
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"Because we don't need to. Hibernation is something that animals do to survive conditions that they couldn't survive normally. This largely only happens for mammals that live near the poles. In the winter, there isn't enough food to eat, so they hibernate to conserve energy until there is food. Humans evolved near to the equator. Where there isn't a harsh winter. We could find food all year round in that climate. So, humans had no need to, nor benefit from hibernating. So we never evolved to have that ability."
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5urilz | How is the ordering of adjectives invented? How do we know when the order is off even if we've never learnt of it? | Other | explainlikeimfive | {
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"You've never *consciously* learnt it. But neither have you *consciously* learned where to put your tongue to pronounce \"sh\", or the difference between \"the cat\" and \"a cat\", or the very complex tense system that English has developed. All of these things you learned as an infant by listening to people around you. Even before you started speaking, your brain was working overtime to figure out your native language's grammar: which words have meaning and which are just there for the grammar, which words describe things and which describe actions, and which order words are supposed to go in, and all the other grammar rules as well. All of this happens automatically, without you having to consciously think about it, simply because when you're born, your brain is wired up specifically to learn a language. It's a remarkably efficient system, as it only takes a few years. And it so happens that one of the things your brain notices is that \"the big, red nose\" is an acceptable phrase, but \"the red, big nose\" isn't. So you have learnt the ordering of adjectives. You just learnt it automatically, because you're brain was, at the time, programmed to learn grammar.",
"For anyone unsure what the OP is referring to, this should help - URL_0"
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5urjx8 | why can't we learn a "language" of other animals? | Biology | explainlikeimfive | {
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"We can, it is just it takes a lot of study and the language isn't in the same form as human language so it isn't just like learning German or Spanish and it comes with body language, scents and other non verbal cues URL_0",
"The other answers here are correct, but the question is actually much deeper than it might seem, and touches on that which sets Humans apart from Animals. Strap in, because I have insomnia. Some of the defining features of language proper are that it is arbitrary, infinite, and voluntary. Some forms of animal communication resemble language in some of these ways, but that actually makes it harder to decipher in most cases. Language is arbitrary in that the words, sounds, or symbols are not necessarily obviously understood by someone who does not already understand the language. For example, the word \"danger\" does not convey a warning to a person who doesn't speak english, but the angry barking of a dog is obvious in its meaning. The exceptions to this are called onomatopoeia, where the word phonetically resembles the meaning, and are often used to describe animal sounds, like \"bark.\" Animal noises and signals that aren't arbitrary are easily understood and imitated by humans to communicate with animals. Likewise, a dog can be conditioned to respond appropriately to commands, but the dog will always understand shouting means anger, happy noises are playful, and quiet noises are calming. Language is infinite in that you can use as many words, or create new words, to describe a limitless set of meanings. Take the example sentences, \"A noble spirit embiggens the smallest man,\" and \"'embiggens' is a perfectly cromulent word.\" Now, even if you weren't familiar with the Simpsons, the meaning of both words can be inferred from context. \"Big\" is a familiar word, with a familiar prefix and suffix that serve to define the word as \"to make one big.\" But \"cromulent\" only has a suffix to indicate it is an adjective, yet the humor of the joke relies on the fact that a person knows exactly what it is supposed to mean. New words and new ideas are the main point of contention that linguists and biologists use to differentiate between human language and mimicry. A bird might learn to produce thousands of words, but it will never create new words, and will never learn to describe new stimuli. Likewise, the tail positions of wolves might convey a variety of arbitrary meanings to other members of the pack, but those meanings are limited to the pre-defined learned messages. Language is voluntary in that we choose to say \"that's scary\" rather than screaming in horror. Animal mating calls can be arbitrary, and in the case of a mockingbird, theoretically infinite. But the mating call itself is biologically compulsive. That is, you can induce an animal under the right circumstances to make specific noises. Humans, on the other hand, choose what to say, when to say it, and how to say it. We also choose how to respond to communications from other members of the species. Our developed forebrains allow us to plan and scheme and analyze information in ways that are not available to most species. Thus, we can observe and experiment with animal communication to decipher their sounds and signals in whatever form they take, but that becomes much more difficult if the subject can choose not to cooperate. All of these aspects actually make it much more difficult to understand foreign communications. Anthropologists spend lifetimes translating dead languages, and it makes discoveries like the Rosetta Stone so precious. Explorers discovering isolated civilizations have relied on visual communication that is not arbitrary, i.e. pointing, gestures, animal sounds, etc, to learn and teach each other's langauge. Simple words are then used to translate complex concepts. \"Me\" and \"you\" becomes \"mine\" and \"yours\" becomes \"I'll trade you this shiny bead for your 1st Edition Holographic Charizard (sucker).\" Humans have an innate ability to pick up language with minimal instruction, but we lose that ability as our brains develop and our cultural linguistics solidify. But even if we could figure out a way (ethically and logistically) to raise a baby in the company of whales, we would not likely have an easier time unraveling the complexities of different songs. Without a two-way communication, we aren't able to learn or teach the meanings of arbitrary sounds or symbols. We have a hard time even determining if dolphin sounds constitute language because we are limited in what we can observe and convey. In the fascinating case of Koko the gorilla, experts disagree on whether she was actually able to combine sign words to create language and describe new feelings, or if she was merely adapting conditioned responses to achieve desires. Unfortunately, Koko couldn't teach us Gorilla because the grunts and hand waving that gorillas use don't convey complex messages. Despite the fact that gorillas don't have a true language, we were still able to learn quite a lot from Koko. We were able to observe Koko trying to teach sign language to other gorillas. We learned from her that gorillas, and likely other animals, have the capacity to learn to communicate in a way that at least closely resembles language. But the closer any natural animal communication is to language, the harder it becomes to translate. Whether it is a visual signals like the movements of an octopus, the clicks and whirrs of a dolphin, ant pheremones, or some other previously undiscovered means of communication, the arbitrary and infinite nature means we cannot guess at the message, nor can we brute force our way towards mutual understanding. TL/DR: A million monkeys at a million typewriters might write Shakespeare, but they won't understand it.",
"Other animals don't have a language. They don't communicate with anywhere near the same level of detail humans do. While they do have certain noises that certain things, biologists haveearned to differentiate and understand much of it.",
"Killer whales have what are basically cultures with different diets and styles of hunting. I'm pretty sure some animals are saying complex things to each other ... don't know why we aren't further along in deciphering some of it",
"u/Finleychops has brought up killer whales which is an excellent example of animals using complex and specific languages. Each separate killer whale pod has its own language...Not just it's own dialect, but it's own specific language. This is known because when captive killer whales have been released back into the wild alone, we know from observations that these killer whales are unable to integrate into any wild pod because they are unable to speak the language of a new pod, and vice versa. We also know that killer whale pods in the wild are able, through their vocal and body language alone, to successfully orchestrate together, very complex symphonies of group behaviour in order to successfully kill large groups of fish. Each member of the pod has specific duties to complete in these group activities in order to bring groups of fish together, to move them from the depths to the surface, and to stun them as a group, and then feed in an orderly fashion. It's absolutely incredible. And they can repeat the same hunting and killing as a group, and change the symphony of body language and vocal language as needed in specific situations, to get the job accomplished. Scientists have been studying wild killer whale pods for decades in order to decipher their languages but we still don't know how to break down their conversation and translate it into the equivalent of human language, so that we can fully understand what these complex and intelligent groups of creatures are conversing about. We need a killer whale scientist in here to explain more."
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5urkzb | What is going on with the human body during Sleep Paralysis? | Biology | explainlikeimfive | {
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"When sleeping, the brain releases a chemical that prevents the body from moving, so that actions taken in dreams will not cause you to for example, lash out your arm and break it against something. Sometimes, you come to Consciousness before the brain releases the chemical required to enable movements. That's all that's really happening during sleep paralysis. Signals from the brain to move the body are unable to go because they're being blocked by the chemical.",
"I get this mostly when trying to falling asleep on my back. But it happens in other positions sometimes too, it's been happening to me for almost 15 years and it's still scary as hell. Don't know why my body is releasing that chemical so quickly. It happens as I am falling asleep maybe 5 mins into the process."
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5urwst | the one electron universe theory | Physics | explainlikeimfive | {
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"Its kind of cool, but its also probably wrong. The idea is that all electrons and positrons are actually the same particle, just going back and forwards in time. If you go back in time there can be two of you at once, say one of you in English class, and one of you in math class. Then the two of you go back in time, and now there's 6 of you out doing different things. Repeat enough and there can be billions of you in short order. Since positrons (the electron anti-particle) are the opposite of electrons in all ways, the positron is the particle going the other way in time. Its a cool idea, but its probably wrong, since it would require the same number of electrons and positrons to exist, and electrons outnumber positrons massively as far as we know."
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5urz1j | What happens if someone dies and even after selling all their assets, they are still in debt? | Who absorbs that debt? Is it just "forgotten"? Passed on to relatives? | Economics | explainlikeimfive | {
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"No one else owes their debt except the wife or husband. Sometimes not even then. It is part of why interest is charged. When a mortgage is obtained life insurance is also bought for the outstanding principal."
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5us3t0 | How does a eagles eye not freeze while in flight in the winter? | Biology | explainlikeimfive | {
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"Wind chill doesn't actually freeze anything. Its called a wind chill because the wind blowing makes the air \"feel\" colder, not actually be colder. Despite how windy it is, the air is still whatever the ambient temperature is."
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5us6k7 | Why do the tips of our fingernails get smooth as they grow even though we did not cut it smoothly? | Biology | explainlikeimfive | {
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"It's not exactly that they grow even, they get polished by asperities and thus they acquire a smoother edge. That's also why we have fingernails in the first place, to take care of friction on behalf of our fingers."
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5us8wr | why is Planned Parenthood taking out so many ads now? | Other | explainlikeimfive | {
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"Because the government is pushing to defund them. You don't read news, right?",
"Because there is a GOP run Congress, Senate, Presidency, and soon to be Supreme Court who have made Planned Parenthood one of their targets in their rhetoric for the past few years (most notably by trying to take away their ability to receive reimbursement for serving Medicaid eligible patients). Planned Parenthood is trying to stir up support for their organization in particular as well as stir up support for easy access to abortion and contraception in general. That way when the GOP goes after planned parenthood or seeks to limit the availability of contraception or restrict access to abortion then the general public will raise hell."
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5usagw | When deep sea divers (of deep sea equipment) dive down to the depths of the oceans, does the marine life notice the increase in light or are they unaware? | Biology | explainlikeimfive | {
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"They definitely notice the white lights they use for full color images. On the other hand, a slow-moving spotlight isn't very threatening, so animals will still drift up and investigate or take bait. To record more naturalistic behavior, they use red lights, right at the edge of the visible spectrum. Most deep-sea critters are blind to red light (except the [stoplight loosejaw]( URL_0 ), which has red \"flashlights\" it uses to see prey without being seen.)"
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5usc8j | What is Universal Based Income and how does it help solve the problem of automation taking over jobs? | Economics | explainlikeimfive | {
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"A Universal Basic Income is a system where the government gives everybody a certain amount of cash every week (or month, whatever) which is enough to live on (there are debates about exactly what the appropriate level is). It could be useful in an increasingly automated society because as robots do more and more jobs, there just won't be enough work to go around.",
"Universal Basic Income - People get a stipend from the government each month to cover unnecessary expenses and participate in the economy. Automation Taking Over Jobs - Less people performing jobs + rising population = more people per job = less people working = less people having the ability to support themselves or family. An example of automation would be having someone use the search feature to find the 1,000 other times this has been asked in the last few months and UBI example would be having the results fed to you like this: URL_0"
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5ush5q | How does exercise benefit a human physiologically? | It's difficult to explain what I'm trying to say, but basically how is exercise beneficial for the human body if you're putting the body under such stress where it tears the muscles and creates an uncomfortable burning sensation during the workout? It sounds counter productive right? Also what else happens in the body that benefits a person? | Biology | explainlikeimfive | {
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"A lot of hormonal stuff happens that I don't know enough about to explain, but basically, you damage your body and your body goes \"well shit, I gotta be stronger if this is gonna keep happening.\" So then it gets stronger. Note that if you do the same exercises forever, you won't keep getting stronger, you'll just maintain that level of strength... Your body is already used to it. If you DON'T exercise, your body goes \"Oh I don't need all this muscle anymore, I can get weaker!\" And you get weaker.",
"Creating micro-tears in the muscle is one of the key components of muscle growth. The body produces more muscle fibres to fill the 'tiny holes' created by the tears.",
"If you exercise you body's muscles systematically, in a measured and controlled fashion, they become stronger, quicker and develop greater endurance. That muscular \"stress\" causes the heart and lungs to respond appropriately to support your entire system of muscles and major organs. People talk about scenarios where you may have to make a \"fight or flight\" decision, almost instantly - a body that has been systematically stressed is in a much better position to do either, successfully. In my competitive years, when I was exercising most strenuously, I never experienced \"an uncomfortable burning sensation\", but I did feel a comfortable warming of the specific muscles being worked. After a strenuous workout, a warm, not hot, shower left me very comfortable and relaxed. Frankly, I've never felt better since! If you do consistently feel that sort of discomfort, you should probably explain the conditions to your doctor and see if possibly there is something wrong."
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5uslqg | How does rendering a video game at a resolution higher than what my monitor can show make things prettier? | You hear a lot of "Oh, you render more and then each pixel on your monitor becomes more pure and you get a clearer image" But that makes no sense to me, if the pixel is going to show red then it will still show the same red imagining there are more pixels. | Technology | explainlikeimfive | {
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"Imagine that you're just drawing something black and white, like text. At low resolution a particular pixel at the edge of the letter is black. But at 4x that resolution, it's a 2x2 square, of which 3 pixels are black, and one is white. These pixels are then averaged to a dark gray, which is what's displayed at the lower res. The result is a softer, more natural edge Edit: corrected typo"
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5usm5v | What would be the effects on the human body, if any, of a person meeting their daily recommended calorie intact and eating healthfully, but doing so all at one meal and not eating outside that meal? | Biology | explainlikeimfive | {
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"On the spectrum between what you are asking about and a \"normal\" distribution of three meals per day, there is an increasingly popular approach to eating called Intermittent Fasting (IF). One variation of the practice is to not necessarily reduce daily caloric intake at all, but to ensure there is at least a 16-hour window per day where no calories are consumed. This is a longer daily fast than would be common in many people's lives. So an adherent consumes all their daily calories within 8 hours or less. That's likely just two meals with the calories of three meals. The reason I bring this up is the shift from all-in-three to all-in-two is reported to improve health. Claims are made of cardiovascular health benefits and longevity. There is evidence to support these claims and less evidence to suggest it is an unhealthy practice. A couple of references for IF: * [\"Fasting: Molecular Mechanisms and Clinical Applications\"]( URL_2 ) [NIH] * [\"The effects of intermittent fasting on human and animal health – a systematic review\"]( URL_0 ) * [\"The power of intermittent fasting\"]( URL_1 ) * [\"Intermittent fasting: The good things it did to my body\"]( URL_3 ) Note that \"Intermittent Fasting\" can take forms other than same-day long-fasts. The BBC articles also talk about alternate-day fasting or intra-week fasting. Just a heads-up. The term IF seems to be used to describe several practices, with similar principles but possibly with important differences. I still think it's interesting and I hope you enjoy this with an open mind as I did.",
"For most people it would probably improve their health. Many of the illnesses of modern society which go under the name of \"metabolic syndrome\" (obesity,diabetes and so on) are caused by the body constantly being exposed to insulin. Cutting out sugar is probably the simplest thing you can do to improve your health in this regard. But increasing the amount of time between meals (without necessarily decreasing the overall amount you eat) will also help. The only problem is that it is quite hard to eat that much at a single meal! Especially if you don't want to eat too much sugary stuff. I generally eat 2 meals a day of about 1000 calories each (at about 9am and 6pm) - I don't think I could comfortably combine them into one."
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5usmjc | Why is it predators are reluctant to attack us? | I've never really understood why this is the case (as it appears to be the case). If we start with something like a bear, it is very reluctant to interact(engage/attack/etc.) with a Human, at all. Now I don't understand why, it's massive compared to us, taller, wider, stronger etc. It must know that it could easily take us out if it wanted but doesn't (a vast majority of the time). I don't understand why. Something like a Great White shark too, they don't outright attack Humans, they 'investigate'. They circle then 'nip', why not just attack us the way they do Sea Lion's etc? The same for a vast array of other animals, too. Then there are animals such as the Gray whale that even if they have a negative experience with humanity they will still approach us... | Other | explainlikeimfive | {
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"We're large enough that even a bear might get injured before it kills us, especially since it doesn't know what nasty tricks we may have up our sleeve. Since any injury can get infected and be fatal, the predator will not take that risk unless it is very hungry and has no other, more familiar prey available. And that's not even taking into account the fact that we usually come in groups, which multiplies the threat we represent.",
"Great whites don't like the taste of human. They usually only attack us if they get confused and think we are a seal. They aren't very bright. So they nip to sample us to see if we are good to eat. Other animals have learned to fear humans, and animals with that fear passed it down to their offspring. Because the truth is there is no animal more dangerous than humans. A bear is bigger and stronger than us, but we have weapons. We usually work in teams and don't travel alone. If you see one human, there are probably others, and they can kill from a distance. It isn't worth the risk. If lucky the bear might kill a solo human who is unarmed, but thats a big risk for little reward. It is better to avoid the human if possible. We're the deadliest predator in the entire world. We have killed and eaten every species of animal that it is possible for us to eat, even highly toxic ones like the pufferfish and venomous snakes. We have killed bears, elephants, hippos, and driven multiple species into extinction. We hunt in packs and arm ourselves with deadly weapons that more than compensate for our individual weakness. We are smart and wily and set traps. If you're a non-human animal and you come up against human territory, then a healthy fear and respect of humans helps you survive. Most species of animal on earth have learned that. For animals who never saw a human, they have no way of knowing what we are about; having never seen one of us they don't know what we are capable of and rightly approach with caution. Looks can be deceiving. Porcupines are small but even bears will avoid approaching them. Skunks are small and unpleasant enough to be avoided. A human shows up to an animal who never saw one before, they will be curious but cautious. An unknown quantity is dangerous. Smart animals learn quickly that humans are more trouble than we are worth.",
"When you go to the grocery store, do you just grab random stuff and put it in your mouth without knowing what it is? Or do you prefer to eat things that are familiar? Animals grow up eating certain prey species. Humans are not normally among them. They do not like to prey on things they find strange and threatening. Maybe if every generation age humans all the time, things would be different. But any animal that ate humans regularly would have either exhausted it's food or been stabbed to death a long time ago.",
"Thing is, Humans are tall. Because we stand on two feet we reach about 150-180cm. That means most predators will look up at us. Most animals aren't accustomed to that and the height difference alone makes us look much larger than we are. Cats look down on mice, for example. Similarly, lions are about eye level with most of their prey (and they're pack hunters and scavengers most of the time, they don't often hunt 1-on-1 because they have no stamina, most of their prey could outrun them otherwise.) Your example, bears are notorious cowards and omnivores, however if they are hungry enough or a mother guarding cubs you better believe they'll attack. Also, most animals haven't tasted human meat. They don't know that we're food yet. Those that do, such as man-eating tigers [are quickly hunted down when possible]( URL_0 ), because otherwise they will start to prey on humans regularly. IIRC I think the hunter riding the elephant got to keep his arm but I'm not sure. Notice how it charges an elephant and aims for the rider. Same reason you shouldn't leave food out for wild animals, they might come to associate us with or as food.",
"As for bears, they are actually less predatory than made out to be. They usually eat small animals and fish from streams, and will rarely regard something above a wolf in size as food. Predatory instinct is usually about food. If it doesn't look edible, or seems to pose a risk of fighting back, the animals won't go for it. Most 'attacks' from predators are territorial. Common instances are if you, even accidentally, come to close to where a preditors cubs\\nest is. Bears and wolves are relatively harmless otherwise. Large cats however are developed to take down large prey, using extremely large and sharp claws and their teeth, so to them, humans are small enough to be considered prey. Simply put, most predators don't like to get into a fight they could potentially lose unless it involves defending something important to them, or if they are desperately hungry. Its a stigma that we have put on them via forms of media (books, movies, tv, news). Its also a stigma that some hunters like to reinforce, to give them reason to hunt predators for ~~stroking their ego~~ environmental and safety purposes.",
"Humans have (completely or partially) exterminated most species that would prey on them like wolves or sabertooth tigers. ELI5: because we fight back.",
"I think animais don't feel the need of attacking a human. And seeing a human may not be common to wild animals so they still act cautious, even if we are smaller. About the whales, only because a species has problems with humans, it does not mean every individual of that species knows about that. And well, most animals aren't aggressive dicks. They are just living beings in a chaotic world.",
"Animals have no idea how strong we are. Humans are ridiculously weak for our size, plus we walk on two legs which probably freaks them out too. Like think of a chimp, they are smaller than us but can rip us apart with their bare hands. And would you start a fight with a housecat? Eff no! Even though they are tiny compared to us they could get in a few terrible wounds before we got them down. Predators don't have bandages and antiseptics and PTO, they don't want to get injured."
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5usmp5 | How can Medicare and Social Security be constantly under threat when we've already paid for it and are continually paying for it? | I constantly hear this mentioned and I don't really understand how it's possible. I've had deductions taken from my paycheck since I started working at the age of 16. So has everyone else that receives a paycheck. It would be one thing if they want to stop the program in the future and say starting 2018 you no longer are going to contribute and therefore no new benefits will be paid out. Everyone that has already paid into would either get a refund or partial benefits. I feel I would be sued I if I took a payment from someone and didn't provide the service or item I said I would. Isn't it illegal to take someones money and not give them what was promised in exchange? We also don't get a say so in giving this money so we're kind of forced into paying for it so that should be even a further reason that it can't just be taken away? | Economics | explainlikeimfive | {
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"So first off, and this is extremely important to understand, you haven't already paid for your own social security. You've paid for your grandparents' social security. The whole system kinda works on the honor system where you pay in and in exchange the next generation will pay for you. Now the problem comes in that there's less children in the next generation and the current generations are living longer and longer than ever. So, we can either seriously jack up the tax on younger generations to try to break even or we can cut benefits/eligibility/etc. on the older generations. Edit: With regards to the rest of your question it is important to realize that the government isn't some person that you can take money from. It's not like you get your SS check from Paul Ryan or Nancy Pelosi's bank account. Rather you are getting your check from then next generation of American workers, who didn't vote for social security in the first place. If you want to argue from a position of justice, why should these individuals be required to pay for your social security? Edit 2: Also, it helps to recognize that the social security trust fund is not some massive reservoir of reserve funds. It's around [ 2.7 trillion]( URL_0 ) which sounds like a lot but is only about [3 years of the nation's social security expenditures.]( URL_1 )",
"I wish to make one additional point from the many already given. To best understand how SS works, think about how the first generation of recipients received the benefit. Those who met eligibility requirements were able to receive the benefit the first day of the program, even though they never had a single penny deducted for the program their entire career. The money for that first group of benefit checks came from deductions taken the same month from those who were employed that month. That new deduction was tough on the employed, as it was like an immediate pay cut but it was generally understood that they would eventually see the benefit when they retire. And it works the same today. Each generation accepts a lower take-home pay by funding the program for today's retirees with the expectation that the following generation will do the same.",
"Another factor is that the government has borrowed large sums of money from social security. Social security itself is solvent. The government borrows from it, endangering its future. We should all be outraged.",
"Well as far as Medicare goes, the average lifetime medical benefit exceeds life time contributions by $100k. That's according to this story from Forbes URL_0 Sorry to tell you, but you really didn't pay for that benefit. For those of us concerned with the mounting pile of US debt heaped upon us, our children and their unborn; it's galling to hear the refrain...\"I paid for that\". \"I'm entitled to it.\" You didn't. You are simply plundering future of our once great nation. You should be aware of that before you pass on this mortal coil. It's not just. It's not right.",
"I did not see anyone touch this part, but some have made some very good points. As others have said, you are not paying for you, you are paying for those on retirement and your kids will pay for you. Ida May Fuller, I think, was the first to collect social security. She paid in something like 30 cents and collected a check for 30+ years. This should show the hazard of the program. It only works as long as the population ratio of payees to retiree's stays positive. There are two major factors you need to consider: Payee to collectee ratio, and life span When social security was started the payee to retiree ratio in 1940 was 159:1. So 159 people were paying payroll taxes for every person collecting a check. That ratio started dropping immediately, and never got better. 1960 it was 5:1 and in 2013 it was below 3:1 (2.8 I think). So in 1940 you had 150 people paying for the care of one person, by 2013 you had three people paying to care for one person. Why? Well life expectancy for one. In 1940 the average age before death was UNDER 65. Today it is closer to 80. Simply put, most people never collected from social security in 1941 since they died. Now you are expected to live 15 years collecting payments! That kind of system is unsustainable. We either need to have more payers, or extend the benefit date to 80 for the system to work the way it was written. Edit to add link: URL_0",
"I will speak only to Social Security: 1. Social Security contributions by you go to pay the benefits of retirees today. 2. There used to be a lot more people paying into social security than were receiving benefits. (It has dropped from a 13:1 ratio down to a 3:1 ratio.) The reason is that people are living longer than they ever have now, and more individuals qualify for benefits from a program that used to strictly be for individuals 65 and older only. 3. Social Security's structure (in its current form) will fail eventually. I want you to visualize the structure of Social Security. Lots of people on the bottom paying a certain amount of money into the system that pay for the benefits of a few people above them. Now add another layer at the bottom with more people paying for the individuals that were on the bottom, but are now in the middle. What does that shape look like to you? You're right, it looks like a pyramid and Social Security is the biggest pyramid scheme ever devised in the history of the world. Every time they increase taxes, or reduce benefits, all they are doing to extending the perceived viability of a system that WILL collapse someday and leave a whole generation of Americans holding the bag. 4. To those individuals that believe having the trust fund invested into treasury bonds is a good idea: You are crazy, or deluded, or both. The US government takes the funds \"invested\" into treasury bonds and uses them for day-to-day general expenditures for the government to continue to function. Even with those funds the US government runs a huge deficit. It is just now getting to the point where Social Security will need to call in those markers on the treasury bonds, and then the US government will not only have those funds to borrow anymore, but they will also have to pay back the funds that it's borrowed to this point. A full economic collapse would not be out of the realm of impossibility at that point IMO. Let's use an example. You have $1 million in a retirement account. However, you live beyond your means on a day-to-day basis. You decide it might be a good idea to loan yourself the money from your retirement account to make ends meet, because frankly living within a sensible budget sucks. When it becomes time to retire, you now need that money that was in your retirement account, but you've already loaned all of the money out of the account to yourself. Does that sound like sound financial planning to you? 5. Yeah, but didn't we run a surplus back when Clinton was in office? Um, no we didn't. The US government actually ran a deficit. However, it got enough money from the Social Security Trust fund so that $60 million of deficit looked like a $30 million surplus. I can't find it now, but I researched the shit out of this in college. The President of the United States issues a letter each year on the national debt. In Bill Clinton's letter during one of the years where he claimed that the government ran a surplus was this little gem of a quote, \"The national debt does not include money the government owes itself.\" And make no mistake that the federal government owes money to Social Security than it does to any other creditor. 6. It's beyond a political issue now, but the only way to fix Social Security permanently is to have a percentage of your paycheck (let's say 10%) go into an account that is earmarked for you only and invested into actual stocks/bonds/mutual funds/etc... If you don't pay into the system, then you don't get anything out. If everyone had 10% of their paychecks set aside for their 40 or 50 years of employment and invested in good investments then everyone would have plenty of money to retire with. As it is, someone is going to get screwed, and the younger you are the more likely it is that it's going to be you.",
"It's not under threat, this is basically a political football with zero basis in reality. There are no legit assets in any major federal fund - what they do is store non-marketable Treasury bonds. To us, a Treasury bond seems like an asset - you buy it for some amount of money, and eventually get more money back with it. Hence, it appears to have value. But the government is the entity issuing the bonds in the first place. The money that goes in through your payroll taxes goes to buy the bonds, which then become the only substance of the \"trust funds\", while the proceeds of the bond purchase go towards whatever the Treasury spends it on at present (e.g., the military). Eventually, they have to repay that bond to make good on the IOU's/bonds, so what do they do? Take the same amount of money from us, again - plus interest. So you're paying in, say, 1 + 1.5 = 2.5, to get back out 1.5. Great deal, huh? The takeaway from this, in regards to your question, is that the bonds themselves are worthless to the government - what it signifies inside the government is \"we plan to put some money here\". **Not** that there actually *is* any money there. What is the value of an IOU that you issue to yourself? *Nothing*. So if the \"Republicans are threatening the trust fund\", what does that mean? Well, the assets in the trust fund are non-marketable bonds, meaning you can't sell them. They'd have to convert them to marketable bonds, which in essence isn't really different than liquidating those bonds and then issuing a ton of national debt. What they can do (but really don't have any *incentive* to do, besides meaningless political posturing) is decrease the target amount of these \"assets\" in the trust fund, or, I don't know, maybe reallocate them to some other program (though I think this would be pretty flatly unconstitutional). The other possibility, which is a little scarier, is the *cough* \"privatization\" of the various programs, which, in spite of the typical meaning of the word 'private', would basically amount to a government-protected monopoly being created to handle the administration of this scam, likely with another slice of ill-gotten gain being ripped out of it and paid to said monopoly. In other words, they would obfuscate the administration of the program even more and make it, stunningly, even more corrupt than it already is. The clear way to understand it is that, if Medicare/Medicaid/SS were just nuked out of the water tomorrow, and we instead decided to, individually & as a society, without the government's help, fulfill the promises that had been made to seniors, the poor & disabled, etc., then it would end up costing us way less money in the long run (versus Medicare/Medicaid/SS doing the same), because we'd no longer be paying into a scam where, basically, we put $20 in a safe, someone else takes it out the back of the safe, steals $25 from our pocket, and hands us $25, and then we go, \"wow, we made $5!\"."
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5usswj | How does radiation kill you so fast? | Biology | explainlikeimfive | {
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"In general, radiation doesn't kill you quickly, unless the dose is extreme. Harm from radiation comes in two types: Stochastic - DNA is damaged, and it just so happens that a gene is corrupted which helps prevent cancer, leaving that cell more susceptible to turn into a tumour in later life. The risk of getting cancer is related to the dose. Any dose or radiation seems to increase this risk a bit (according to generally accepted science, although some people do disagree with this). Essentially, each unit of radiation, is like a ticket to the cancer lottery - you might get lucky, you might not. But the more you play, the more likely you're going to get a prize. Deterministic - Tissues are injured by large doses of radiation. Once you go over a certain dose limit, certain tissues start to show signs of damage. Skin might get red and sore; the lining of the mouth or throat might start to strip off; the bone marrow stops producing new blood cells, so short-lived cells like immune system cells get depleted and not replaced. Deterministic effects usually take a few days to show up and require a dose of more than 1 Gy. This is because the main way in which they occur (at least at the lowest possible doses when they happen) is that DNA is damaged and the DNA repair systems are unable to repair it in time. Cells which are replicating frequently (skin cells, hair cells, stomach lining, etc.) spend a lot of time copying DNA, and during copying the DNA is not available for checking and repairing. This means that the more rapidly cells are replicating, the more vulnerable they are to getting enough DNA damage to prevent the replicated cells from operating correctly. However, at extreme doses (10 Gy and up), other effects occur. Other cellular molecules are affected. This can be things such as cell membranes, energy production systems, etc. One of the things that seems to occur is that the brain can be seriously affected by this - possibly due to effects on the microscopic capillary blood vessels which become damaged and leaky. Exactly what happens isn't known in detail. But the effect is that the brain can swell up with fluid and/or the blood vessels can start bleeding into the brain. The problem is that the brain is inside the solid skull - so if it swells, it can't enlarge, instead the pressure increases. This can then cut off the blood supply to the brain due to the pressure, resulting in death. Before this happens, there can be various symtoms such as confusion, drowsiness, vomiting, dizziness, coma, etc. due to the effects of the swelling on the brain."
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5uswfs | Do the past and future exist? With time being a dimension, couldn't present be just moving with us through time and not existing in different time "points"? | Let's say there is a rock that is in the same spot for 10 years, is that rock there 10 years in the past? or have the rock moved through time and is now in the present? | Physics | explainlikeimfive | {
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"Copying and editing my response from another, similar thread: Yes, the past and future do exist, and we can prove that with causality. Causality is part of the fundamental nature of the universe, and means that something cannot happen unless the thing that caused it happened before it. And since causality \"moves\" at the speed of light in a vacuum (technically it's the other way around, light in a vacuum moves at the speed of causality) and movement takes time, there must be time in between a cause and it's effect. Assuming the rock stayed in the same space for all of those 10 years, then it will have moved through time, yes. It's hard to say what would happen if you went into the past because backwards time travel is impossible. We can't predict what would happen because it doesn't work with our current understanding of physics. Now, time can be seen as an illusion in some sense, because time is relative. The faster you move through space, the slower you move through time, and vice versa. A rock traveling 90% the speed of light would age more slowly than a rock sitting still on the earth. 10 years from now, the fast moving rock would only have aged a fraction of that (not sure exactly how much). However, I'm not a physicist, and I'm not an expert on this. Somebody who knows more about this kind of stuff, feel free to correct me. I love this kind of stuff, so if you can teach me more, please do.",
"I would actually argue that the present does not exist. At least, I would say it doesn't exist as a point in time. If the present exists at all, its only purpose is to convert future to past."
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5uswji | how do finite numbering systems like phone numbers or social security numbers work? | Technology | explainlikeimfive | {
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"text": [
"Area codes were assigned very carefully. Back in the day you had to wait for that rotary dial to turn all the way and they weren't quick. Therefore the \"short\" area codes - 212, 312, 215, etc - were all assigned to large cities, in this case NY, Chicago and Philadelphia. Meanwhile Alaska got 908, West Texas got 806. Area codes always had a 0 or a 1 in the center, but never in the other positions. When we started running out of area codes about 30 years ago those rules were discarded and since most people switched to button phones the number didn't matter. The first three digits of your local number were originally part word, part number. As a kid my number was OLdfield 9, you dialed 659. They never contained a \"0\" or a \"1\". The last 4 were random. Sometimes families shared a line, those were called party lines. SSNs are still unique to each individual. The first 3 digits are based on the region of the country where you lived when you got your number (which was rarely done before you were 16 or 18.) The middle two are a group number, like check digits. You can actually check an SSN to see if it's valid bc of those two digits. The final four are random. All this info is US only."
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5uswmp | why can't we bundle our health insurance with our other mandatory insurances like car, home and renters? Or even combine it with life insurance and other insurances? | I have owned my home and had car insurance and have 0 claims in 10 years. That money seems like it could help create more interest build overall to help fund my health insurance. | Economics | explainlikeimfive | {
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"There would be no real benefit. The money you pay for your car and home insurance premiums doesn't go in some account with your name on it. \"This is Yolo20152016's unused insurance money\" It goes towards the profit and operating costs of the insurance company. Most importantly It pays the claims of other people that also have insurance. Poof, it's gone."
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5uswrl | What software do game developers use to put maps together? | I've always wondered how game developers put maps together. For example, how was the map in GTA V put together? Do they use prosperity software to stitch together assets and textures, or do they make the whole map as one solid lump in something like Blender or 3DS Max? | Technology | explainlikeimfive | {
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"They make their own most of the time. There are way too many to list, so I'm going to list the 2 most popular ones (going to skip the ones from UE and Unity): - Radiant: used in every single id Tech 3+ game and games based on that engine (the most popular one being of course, Call of Duty) - Hammer: originated from an unofficial quake level editor (not sure, if I made a mistake there, let me know), it is the main level editor for GldSrc and Source engine"
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5usxy6 | Why did humans get skipped in having a cool-ass tail? | Biology | explainlikeimfive | {
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"Interestingly enough, this question also makes sense if you phrase it as a \"cool ass-tail.\" Also, evolutionarily it tends to get in the way of bipedal motion.",
"Interestingly enough, we (and all vertebrates) are part of the phylum Chordata, and all chordates have a tail (and gill slits!) for at least some part of their life. It's just that in our case, [only our embryos have those things.]( URL_0 ) So if it makes you feel any better, we didn't really get skipped...it's just that at some point in your development you decided \"lol nah, I don't actually want this tail\"",
"Our ancestor species had tails at some point, but we evolved to lose them at some point because they just get in the way when you walk upright. No need to spend energy on growing a tail that does little more than inconvenience you. Plus, it's one more extremity that can be injured.",
"According to [this]( URL_0 ), monkeys and apes diverged based on diet (monkeys eat unripe fruit, while apes required ripe fruit). Therefore, monkeys are evolved to move through the upper parts of trees, running on top of branches where having a tail for balance is useful. Apes evolved to swing between trees, below most of the branches, where having a tail isn't useful."
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5ut02u | when people say a medication will "make you gain weight" does that mean it just increases your appetite or that it literally changes your metabolism so that you gain weight from less food? | Biology | explainlikeimfive | {
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"In some cases it's because the drugs fuck around with your neurotransmitters, which can affect when you feel hungry vs. full. In other cases, the drugs make you retain water.",
"Pharmacist-in-training here, hoping I can provide an answer to this question. Weight gain purely from medication isn't exactly a \"definite\" fact, meaning there will be some who do gain weight after taking a medication and some who do not. During the process of testing the drug to see if it's effective, the manufacturers also see if the drug causes other effects which include weight gain compared to placebo, and report that as an \"adverse drug reaction\" if the side effect is significant enough. For antidepressants like mirtazepine notorious for weight gain in patients, the package insert reports: > appetite increase was reported in 17% of patients treated with mirtazepine, compared to 2% for placebo > weight gain of ≥ 7% of body weight was reported in 7.5% of patients treated with mirtazapine, compared to 0% for placebo So it COULD be that the drug induced appetite (as the PI strongly suggests), or the drug itself caused weight gain in a manner not studied extensively enough ~~For all we know, mirtazepine might have induced some irresistible cravings for McDonalds at night.~~ What really matters though, is that mirtazepine has a high chance of causing weight gain through evidence (regardless of why it happens), and is avoided in patients conscious about their weight or already overweight."
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5ut0kl | how do they get a photo or image transferd to a printing press? | How do they take a picture (lets say on a paper) and transfer the picture to the printing press, so they can print it in large numbers? | Technology | explainlikeimfive | {
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"text": [
"modern day full color printing presses are basically flow thru laser printers. your image is split into 4 colors, cyan, magenta, yellow, and black. or sometimes 8 colors, cmyk and light cyan, light magenta, light yellow and light black. each of those single color shade images are electrostatically imprinted on a drum by a laser. the static charge picks up the ink or liquid toner and is transferred onto the print media (whatever kind of paper product). each color is layered on top of the others to create other shades of colors. then a heat drum if toner or just hot/dry air if ink to sets the image. URL_0"
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5ut0ux | How do we remember everything? Doesn't our brain get overloaded with information? | I was wondering, how does our brain manage to do it all? Doesn't our brain get overloaded with information when we think and register things to our long-time memory? How does our brain store information? It's space seems to be infinite... | Biology | explainlikeimfive | {
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"text": [
"The brain remembers far fewer details than you might think. It compresses and discards unnecessary information all the time. Unless you have a photographic memory (which is pretty rare), you just remember the things that stick out, and your brain reconstructs the rest based on how things like that usually looks. It uses symbols and generalizations all the time, and reconstructs memories based on how you know the world to work. Recalled memories are often slightly distorted each time you try to access them. It just happens little by little, so you don't notice that your memory has changed. We're good at remembering generic things, but bad at remembering details. Usually the brain just fills in details that are likely to exist even if we don't know for sure that they existed."
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5ut4bl | How is it that people (general, public, politicians, scientists) deny climate change? | Other | explainlikeimfive | {
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"I don't think that they are denying that it's happening, but they are more suspect to the cause of it. Some people think that it caused by human influence. Some people think that it is a natural fluctuation that we just so happen to be witnessing. Then there are people who are in the middle, who see facts like cow farts' role in the production of methane, and then they think that this is a much more detrimental cause then CO2 emissions. Then then are people who are willfully ignorant of the facts all together so they tend to side with whoever side they typically side with on other issues.",
"There are different types of deniers. There are guys who deny climate change at all - they are not very smart. There are guys who accept climate change but deny that it's caused by humans. There are guys who accept that humans caused climate change but don't believe it can cause catastrophic consequences. And there are guys like me - I'm not the specialist but I'm very sceptical and I try to get all information online. I know that it's not the current CO2 level that is alarming - it's the speed of raise of that level. And also I know that all life forms produce much more CO2 than humanity started to produce since industrial age. I also know that there was kind of balance between how much CO2 was produced and how much is recycled and it might be broken now because of activities by humans. But it's very hard to prove that consequences will be catastrophic. We can't normally predict weather even 2 weeks ahead because it's very very complicated. By far, I haven't seen a 100% proof that climate change can cause catastrophe, however I haven't seen a 100% proof of the opposite.",
"There really are two parts to the global warming model: First that CO2 (and other gasses) directly cause warming through the greenhouse effect. Second, through positive feedbacks, this warming is magnified several times to reach dangerous amounts of warming. The first part really is uncontroversial, it's easily tested through experiments, and looks to be around 0.5-1.5 C per doubling of CO2. The second part, however, is *not* well tested, it's based on theory and statistical models and is required to reach the dangerous levels scientists warn us of. Skeptical scientists aren't convinced of the second part of the theory for a couple reasons: First, systems dominated by positive feedbacks are *always* unstable. Positive feedbacks are like a marble on top of a hill, a little nudge and the marble ends up at the bottom. Second, the models and statistics used to develop the theory are far from ironclad evidence of anything. The models require scientists to make guesses and assumptions about different parameters and how they relate to each other, does a have a linear or exponential relationship with b? Does c have a strong or a weak impact on d? Relatively small changes in those assumptions and guesses lead to big changes in the outcome of the model. (Note that this isn't limited to climate science. Macroeconomics, for example, has much the same problem and there is robust debate in the field about which assumptions are correct.) For politicians and the general public, a lot of the issue isn't with climate change itself, it's with the policies that are being pushed to deal with climate change. However, the rhetoric around the issue has become \"Since climate change is happening, we must do < policy > to deal with it.\" But, there's always going to be legitimate debate over policy choices because there are always tradeoffs required: If we stopped using fossil fuels completely energy would become much more expensive and that would hurt people. So, there's legitimate debate over whether the downsides of different policies balance out their benefits. However, it's hard to explain cost benefit analysis over multiple policies with decades' long timeframes, *especially* when the costs and benefits are very uncertain. (Remember what I said about the problems with macroeconomic models?) So, politicians being politicians, some of them took the easy way out and instead of arguing policy simply argue against climate change as an easy proxy: If climate change = policy, then naturally !climate change = !policy, amiright?"
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5ut5im | Why do people hate Steve Jobs so much? | Technology | explainlikeimfive | {
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"He was kind of a sleazy guy in real life. He tried to disown his own daughter, as in denying paternity. URL_0 He was abusive to employees, and had little regard for the working conditions of people who made Apple products. URL_1 It's not hard to find reasons why people think he was good at some things, but not good at others that are often considered more important for being a good person.",
"Because he got famous and successful by stealing others ideas. Steve Wozniak was responsible for a lot of Jobs's best ideas but he was given little to no credit for any of them. Also, Steve Jobs was a perfectionist and a bit of an asshole towards his employees, and would berate them for even the tiniest mistake."
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5ut6ej | If I ate 3000 calories of Green Beans per day, and my friend ate 3000 calories of fried pork chops per day, how would our bodies differ? | Biology | explainlikeimfive | {
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"Firstly, you would find it hard to eat that many green beans - green beans have about 300 calories per kilogram. Secondly, you would be missing out on loads of nutrients, whereas meat is nutritionally complete, so your friend would do fine. Your friend would undoubtedly put on more muscle than you - and that's likely to be the only weight he put on. I'm not sure exactly what would happen to you, but I doubt it would be pleasant. I haven't heard of anybody eating just pork chops, but some people have tried eating only bacon for 30 days (or longer), with excellent results (eg URL_0 )"
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5ut6r9 | Why are porn movies so long (~40 mins) when most (all) people don't last that long? | Other | explainlikeimfive | {
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"Not everyone watches it for personal friction time, aka fap. It's audience is intended to be for people who can appreciate the intricate plot, character building, and dramatic dialogue.",
"People normally watch over multiple sessions so they are longer to provide multiple scenes to watch.",
"You also have to realize that they're not actually doing the same thing over the course of 40 minutes. There's many different \"sections\" to the film that involve different positions and sexual acts over the course of 40 minutes. Many people skim through the video and find a part they like more than the rest, so in a way 40 minute videos are like a variety platter than you can choose to take a piece out of."
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5ut7eb | Why aren't microwaves hot inside after use, like an oven? | Other | explainlikeimfive | {
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"An oven works by heating the air around the food with the element or burner inside the oven. A microwave works by vibrating the water molecules inside the food, not by heating up the air.",
"The microwaves directly heat the water and oils in the food. the waves don't affect the metals, glass, ceramics and such in the oven the same way. Even dried foods are less affected.",
"How does dry stale bread get soft and soggy? Where does the moisture come from?",
"Microwaves are basically light, and the walls of the oven are like mirrors to that wavelength of light. The food is like a dark object, it absorbs the light, getting hot in the process."
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5ut8nx | why is it so much harder to make antiviral medications than it is to make antibiotics for bacterial infections? | Biology | explainlikeimfive | {
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"Because bacteria are fully-fledged living things. They do all the work needed to exist themselves - they make all their own proteins, do their own metabolism, use their own proteins to replicate their DNA and make RNA, and build their own cell walls and cell membranes. And because we're so distant from bacteria in an evolutionary sense, the processes they use and the proteins they make are in some cases very different from what we do in our own cells. This gives us a lot of targets to design drugs against (and gives evolution a lot of targets to generate drugs against as well - credit where credit is due). In contrast, viruses exist on the border between living and nonliving. They have their own proteins, but very few of them. They use _our_ cellular machinery to reproduce; the energy needed for this comes from _our_ metabolism. Since they're so much simpler than bacteria, there are fewer targets to develop drugs against. It wouldn't be as safe to develop drugs against many of the biological processes that viruses depend on, because we depend on those processes too."
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5ut99u | If we all have different taste preferences, what is the point of a food critic? | Biology | explainlikeimfive | {
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"People have different tastes, but they tend to fall into patterns. Most people prefer food that isn't microwaved, or is fresh. A critic might also tell you how well this restaurant makes a certain type of food. Not everyone likes Indian food, so there are some people who wouldn't go to an Indian restaurant. But if you do like Indian food, a review could tell you if the food at the restaurant does a good job representing cuisine, so you'll have a better idea if you would like that food.",
"Because they tell us if a particular place males a good example of a particular food. Just because you like a burger doesn't mean you think that a McDonald's \"burger\" is the same as one from a restaurant.",
"They don't get paid to tell you whether or not you'll like the food. They get paid to tell you what the food tastes like or how it compares to other food in an accurate manner. So if you like burgers and you read a food critic/review about a burger joint, you can see if their description of the burger appeals to you.",
"A critic is supposed to measure the *quality* of a certain type of thing (be it food, car, tech, etc) whether we like that thing or not."
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5utc7u | Why does a web page, image, or video always seem to load the exact second I press the back button? | Technology | explainlikeimfive | {
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"A web page will try to load everything before it shows on your screen. Sometimes tho it gets stuck somewhere and you only see blank screen. When you press back button all the loading gets stopped and it displays what was loaded while your browser starts loading the previous page.",
"Not an expert, just an experienced user. From my experience, this happens with browsers which have a \"preloading\" function, which means they load a lot of the website's content in the background and then display them at once when everything is downloaded. If you press back before the preloading is complete, the browser displays everything that's loaded at that moment to free the backgrund memory for the website you're going back to, or to simply save some CPU.",
"I'm not a guru in web browser but once you download something, unless you delete it you still have it. So what happen might be that your web browser save a copy of the recently visited website with all the file (image, video, etc.) and when you go back, you browser check if you have visited this page recently and load the copy that you have stored in your memory. You don't have to ask the web server to send it back."
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5utgii | Why do businesses hire contract security guards if they can't do much? | Talking about the type of security guards who stand in the middle of Wal-Mart entrance observing people. I get that one of their purposes is to observe and report. But there are also sites where it feels like it's pointless to have them there such as guarding an empty parking lot after hours. If someone is caught stealing the most they can do is citizens arrest and most security companies will not even allow that for liability issues. What is the real reason a business would hire contract security when in any other day they didn't have one or rely on one? | Economics | explainlikeimfive | {
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"Presence is a deterrent. Just having someone around watching does a lot to keep people honest.",
"Some companies hire one for insurance reasons. The other can be to hire a guard company for a low wage and then get him to check freezers all night for a lower cost than hiring or paying one of their own a higher wage."
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5utgx6 | How come when we look at direct light, (Ex. Lamp, lightbulb, sun, etc.) we see flares around the object? | Physics | explainlikeimfive | {
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"The lenses in your eyes aren't good enough to properly let the strong light through without some light spreading randomly as it enters your lens, causing some light to \"bleed\" outwards from the bright spot. Your eyes' lenses are pretty transparent, but not perfectly transparent, so bright enough light is still able to \"light up\" your lens,in a manner of speaking. It's sort of the same effect that happens with cameras, except those often have multiple lenses inside, creating multiple flares. High quality lenses have special coating that prevents flaring, but it's still not always perfect."
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5utp5q | Are the different toothpastes actually different or is it all just a marketing trick? | Chemistry | explainlikeimfive | {
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"I work in the industry and in the US we are regulated by the FDA. Toothpaste is what's called an over the counter drug. This means that it has some claim that has been substantiated by a study, and an active ingredient that works toward that claim. In the case of Toothpaste it might have an ingredient like Sodium Flouride 0.24% there's lots of testing that will substantiate that Flouride at that percent prevents tooth decay via prevention of softening of the enamel. Now Toothpaste may something like \"appears whiter\" and this can be a cosmetic claim. Basically they got 20 people in a room and asked them \"after using it for a week do your teeth look whiter?\" get enough people to say yeah, and now you have label copy. But if they add 0.04% hydrogen peroxide as a whitening agent, then it will say it on the label. So what's this all mean? If two completely different Toothpastes have the same exact active ingredients they are essentially the same. Everything else is taste and filler. It also means if a Walmart brand has the same active ingredients it's just as good as the brand name. Likely also made in the same place. Edit to add: any OTC drug has a number on the back you can call and ask to see the studies that back their claim. Cosmetics also. Just call and ask, \"can I see the study that you use to verify the claim of 10 x brighter?\" they have to be able to prove it.",
"Dentist here. There are minor differences overall. But really we just recommend one with fluoride that you like for most people. I've seen people comment on here fluoride has no effect. I'm not going to post a long rambling post but that's just wrong. As the hydroxyapatite in enamel loses its ions from acid (which happens around ph 5.5) the hyrdroxyl group is replaced by the fluoride which creates fluoroapatite which is dissolved at pH 4.5. This is a great deal difference as it's the pH scale. I know that's not explain like I'm five but it is. Tartar control has pyrophosphates which do help slightly. Sensitive usually uses another type of fluoride called stannous fluoride or a chemical potassium nitrate to reduce sensitivity. Both work for minor sensitivity. Whitening has a higher RDA value usually which means more abrasive. Cosmetic claims don't need evaluation so those are almost all marketing. The triclosan in Colgate total does have studies backing it up but there is the debate of triclosan in products contributing to antibiotic resistance but it's mainly with hand soaps so it may or may not be around on toothpaste in the future. Well. Looks like it was a long rambling post. But to sum it up. Brush for two minutes twice a day. The two minutes is not only to do a good cleaning but also to give time for the fluoride to work. It's also recommended to not rinse after brushing especially at night to allow for more contact time. Just spit out excess. Edit. Also there is also Mi paste/tooth mousse which has ACP which is a bioavailable way for the ions to remineralize without fluoride. But you lose the benefit of creating the fluoroapatite.",
"I thought Colgate Total was different as it contained Triclosan. But i think other toothpastes have this too. Big difference.. Sensodyne Repair and Protect has a bioglass compound called Novamin that actually bonds with the enamel and gives it an extra coating that fortifies teeth enamel. It is the only compound and toothpaste that actually repairs or fortified your enamel. I know a new compound called Biomin has come out which is a superior version of Novamin, but it is only available in the UK for now. Edit: correction: Bioglass is not the only compound that repairs your enamel. But it is the best or among the best there is. Also available over the counter so you don't need some expensive prescription toothpaste. Novamin (a type of bioglass) was invented by a scientist and Sensodyne bought out his research, so to my knowledge Sensodyne Repair and Protect (non US version) is the only off the shelf toothpaste that has Novamin. For some reason, the version in the US does not have Novamin. If you want to buy the Novamin version in the US, buy it from Amazon here: URL_0 It takes a few weeks to ship from the UK. But the price is reasonable: $6.60 and free shipping.",
"There are actually types of toothpaste that are not based on fluoride, but on other substances that have some degree of research as to increased efficacy. For example, sensodyne in Canada/UK (not sold in USA due to patent nonsense) contains not plain sodium fluoride, but rather NovaMin, a bioglass that is designed to (in a simplified sense) fill in gaps in the teeth. Certain toothpastes, typically available as a special treatment in some Dentist offices, use nano-hydroxyapatite which some studies show to be superior to sodium-fluoride in the remineralization of enamel. While you can't buy either in US stores, except perhaps as an expensive once-off in the right Dentist office, they're readily available on Amazon. This goes way beyond ELI5, but here's some research articles: * **Enamel surface remineralization: Using synthetic nanohydroxyapatite** > * URL_3 > The use of biomimetic nanohydroxyapatite as a remineralizing agent holds promise as a new synthetic enamel biocompatible material to repair early carious lesions. * **Nano-hydroxyapatite and its applications in preventive, restorative and regenerative dentistry: a review of literature** > * URL_1 > The nano-hydroxyapatite is a revolutionary material with a wide use in dentistry. With regard to restorative and preventive fields, nano-hydroxyapatite has remarkable remineralizing effects on initial lesions of enamel, certainly higher than traditional fluorides used until now for this purpose. Nano-hydroxyapatite is, in fact, a better source of free Ca, and this is a key element as regards the remineralization, the protection against caries and dental erosion. * **Enamel surface remineralization: Using synthetic nanohydroxyapatite.** > * URL_6 > Thirty sound human premolars were divided into *nanohydroxyapatite group* (n = 15) and the *sodium fluoride group* (n = 15)...The results showed that the nanohydroxyapatite group produced a surface morphology close to the biologic enamel, the increase in mineral content (Ca/P ratio) was *more significant* in the nanohydroxyapatite group (P < 0.05) and the SMH recovery was *closer to the baseline level* in the nanohydroxyapatite group (P < 0.05). * **In vitro effects of nano-hydroxyapatite paste on initial enamel carious lesions.** > * URL_2 > Forty-eight human enamel blocks were assigned to four groups (N=12): (1) control (without agent); (2) fluoride varnish (Duraphat); (3) nano-HAP paste (Desensibilize Nano P); and (4) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI Paste Plus)...After the cariogenic challenge, the nano-HAP group showed significantly higher KHN and %SMHR values than varnish. The CPP-ACP group showed no increase in KHN. The nano-HAP group showed, via AFM, a protective layer formation with globular deposits on the surface....SMHR and AFM morphology revealed that nano-hydroxyapatite paste showed a protective effect against in vitro enamel caries development. * **Remineralization of early caries by a nano-hydroxyapatite dentifrice.** > * URL_0 > nHAP dentifrice caused remineralization comparable to a fluoride dentifrice, and inhibited caries development, thus suggesting that an nHAP dentifrice can be an effective alternative to fluoride toothpaste. * **An In-vitro Comparison of Nano Hydroxyapatite, Novamin and Proargin Desensitizing Toothpastes - A SEM Study.** > * URL_5 > It was concluded that all the three desensiting agents were effective in the dentine tubule occlusion. In addition efficacy of nano-hydroxyapatite toothpaste was greater compared to the other desensiting agents. Novamin seems somewhat similar, it's a \"bioglass\" that is supposed to fill gaps in enamel and reduce tooth sensitivity, though it may also promote remineralization. Like I said, it's in sensodyne (interesting, it is not in US sensodyne, only in other countries like Canada and the UK). * **Dentinal tubules occluded by bioactive-glass containing toothpaste exhibit high resistance toward acidic soft drink challenge.** > * URL_4 > The scoring and the percentage of occluded dentinal tubules by Novamin containing toothpaste was significantly better compared to arginine or the control toothpaste.",
"TL;DR - basic toothpaste seems to all be the same, but the \"extras\" they add in (like teeth whitening for instance) are done differently by different brands. Interesting thing - not all toothpastes (in America) carry the American Dental Association seal of approval. I was kinda surprised how few did when I noticed this. If I had to venture a guess I'd say only about 50% of the stuff on the shelf carries the ADA seal. Seems generally speaking that toothpastes that claim to whiten teeth or rebuild enamel or other such things don't carry that seal, whereas all basic toothpastes do. So what this tells me (and keep in mind, I'm just a dude... I don't really know) is that all \"basic\" toothpaste is basically the same and they figured out how best to make that stuff years ago. The only real difference is in things like flavor and texture. But the \"extra features\" in toothpaste - whitening, rebuilds enamel, removes coffee stains, for sensitive gums, improves your personality, etc - those are done differently by different brands. I think whitening in particular is something to watch out for - there are different methods for doing that. I'm not knowledgeable enough about that so I just go with stuff that has that ADA seal. Wow - that really got really long on me.",
"The differences are very minor. The core aspect of toothbrushing is the physical action of the bristles. The toothpaste acts as an abrasive polish, and all toothpastes work about equally for this. The only difference is the chemicals that can be applied such as flouride, and the scent of the paste on your breath.",
"Some toothpastes definitely have quite different active ingredients. One example is the Sensodyne line, which btw I am from the UK and I believe the active ingredients across the pond are a little different. Anyway, your dentist may recommend you 'Sensodyne' tooth paste for sensitive teeth, but which one you should buy actually depends on a few things. - Sensodyne rapid relief contains strontium acetate, which effectively blocks the tunnels leading to the nerves within your tooth to sooth pain and, long-term, block the nerves off. - Repair and Protect uses NOVAMIN, which I believe is not approved by the FDA in the US, which actually rebuilds the exterior of your tooth over the dentin, blocking off these tubules that cause pain within your teeth. Colgate's sensitive line uses completely different ingredients, I think. Anyway, not a professional - I just have sensitive teeth - but that's all certainly true.",
"A *huge* difference (at least for me) is that most mainstream toothpastes contain a chemical called Sodium Lauryl Sulfate (SLS). This makes them all nice and foamy when you brush. Which doesn't make a damn bit of difference as far as cleaning goes, but DOES make it far more likely (for me and many others) to get canker sores. Years ago I started using Toms of Maine, which didn't have SLS at the time. Then Colgate-Palmolive bought them and promptly added the SLS back in, without bothering to tell anyone. I discovered this situation when I started getting canker sores again. Bastards. Now I use Biotene which is SLS-free. FWIW.",
"While the formulations are certainly different between companies, as far as the results go the differences are not enough to be noted on a clinical scale in my experience talking with patients for the last 10 years. Some, like Colgate Total use Tricoslan ( now banned and soon to stop because of the risk of bacterial resistance) while Crest Pro Health uses Stannous fluoride instead of Sodium Fluoride, though again in my experience the average person will not be able to tell the difference. The two exceptions to that rule would be toothpaste's like Sensodyne or similar products from other companies, as these contain Potassium Nitrate 5% as an additional active ingredient in addition to Sodium Fluoride. Also, if you are at a high risk of cavities or have extremely dry mouth a RX toothpaste with higher fluoride concentrations (most common being Prevident 5000) may be prudent. My recommendation to patients is to get the cheapest toothpaste you can that contains Sodium Fluoride or the equivalent unless you have problems with sensitivity, in which you should look for a tooth paste with Potassium nitrate. In my professional opinion if you want whiter teeth you are better served using a peroxide based whitening system from your dentist or from things like OTC whitening strips. TL;DR: There are no real differences except if you have specialized needs in which other products can be recommended by a dental professional.",
"The more advertising you see for a class of products, the less difference there is between them.",
"Nice try toothpaste marketing companies! After yesterdays video about companies buying upvotes and 'authentic' user experiences I can see you coming from a mile away. You can sell your Colgate Total with Extra Whitening somewhere else. I on the other hand will stick to my Crest Pro-Health Advanced: Stronger Teeth for a Healthier Mouth. It never lets me down!",
"Dentist here - most toothpaste has sodium fluoride as is active ingredient, which is fine. Others like Gelkam and Crest Pro Health have stannous fluoride which is probably more effective at preventing cavities as well as killing bacteria that are associated with gum disease, but they also have been associated with slight tooth staining so it's less popular even though it's more effective. The \"sensitive teeth\" pastes usually have potassium nitrate which acts to block the nerve of the tooth from extreme changes in temperature so your ice cream doesn't hurt. Still others don't have fluoride in them at all, in which case you might as well be brushing without toothpaste.",
"Funnily enough I've been thinking this recently. While there are some differences between toothpastes, ones for sensitive teeth for example I think a lot of it is due to gaining visibility. If you own a supermarket you are only going to give so much space to a single product under normal circumstances but if you have several similar products and they each get that same amount of space on the shelf, altogether that creates this effective looking wall displaying your brand and making it look like the dominant brand. The biggest example being Colgate; they have several toothpastes all claiming to whiten your teeth but with different packaging so they take up a whole shelf or sometimes several shelves with it's eye catching red backed logo instead of just a small section.",
"I just got back from the dentist after a 15 year haitus. I have gingervitis bordering periodontitis. I'll be OK. Anyways, I asked them what the best toothpaste to use would be, to help prevent it from getting worse. They said it doesn't matter. It's all personal preference. Just brush correctly and floss/water pick (I have one). And to get a professional cleaning every 6 months.",
"Well I can genuinely say I had really badly sensitive teeth for months then I switched to sensodyne and it went away within about three weeks and hasn't come back. So there is probably some difference.",
"For me, there are two kinds of toothpaste; Sensodyne and everything else. I have sensitive teeth and sensodyne (even the whitening type) makes my teeth less sensitive to everything. If I have to use some other kind, I can tell the difference after a couple uses because my teeth start to hurt. If anyone knows of something less expensive than sensodyne but works as well or better, I wanna know about it! 😁",
"They have to be different in some ways. Crest Pro Health gave me a weird sore under my tongue and makes the inside of my cheeks shed. I actually thought my ex had given me herpes or something. Nope- it was the toothpaste. Switched back to what I normally use and all was well again.",
"I'm given to understand that the concentration and type of abrasives can vary slightly. So there's a very narrow spectrum with \"removes plaque better\" on one end and \"wears less at gums and enamel\" on the other. From Wikipedia: > Representative abrasives include particles of aluminum hydroxide (Al(OH)3), calcium carbonate (CaCO3), various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite Consumer Reports did a review and found that the differences in ADA certified toothpaste are small enough that it's hardly worth worrying about, but if you want to, then for soft and/or thin enamel, you want sensodyne (even apart from the potassium nitrate they add to desensitize nerves in the gums); otherwise you... want a brand that no longer exists (as far as I can tell they haven't done a new review since 2007, you also need a subscription to see their full editorial reviews and mine has lapsed). I believe they found Colgate to be slightly less abrasive than Crest. (Speaking of, brushes are probably overall more important than toothpaste in terms of abrasive cleaning, but you want a soft brush because as long as you brush consistently, you'll get the plaque, but a hard brush will violate your gums, and for some people there's actually a concern to too much tooth wear.) Additionally, whitening toothpastes are basically worthless. The concentration of whitening agents is so small, and stay in contact with your teeth for too little time; any perceived effect is probably placebo. Instead, buy those home whitening kits and use them occasionally (the same thing as what they use for tooth whitening at the dentist's office, just slightly lower in concentration, and at about 1% the cost). Basically, use a hammer to do a hammer's job, a screwdriver to do a screwdriver's.",
"I've noticed that toothpastes here in the USA Are far different from toothpastes in Japan. Anyone know why?",
"I fear whitening pastes, I feel in 10 years we'll all discover it's been sanding down our enamel for the price of vanity.",
"I can't remember the ingredient, but if you're prone to ulcers it is possibly linked to Sodium Laurel Sulphate. A few toothpastes don't use this, and my friend who is incredibly prone to them stopped getting ulcers using SLS toothpastes. Anecdotal maybe, but potentially interesting to those of you who can't pinpoint why you keep getting ulcers.",
"Don't waste by filling the whole toothbrush head with toothpaste, pea size amount is adequate.",
"All I know is that every toothpaste no matter the brand has been approved by 4 out of 5 dentists.",
"Most toothpastes are water based formulas with similar ingredients. However, there is one toothpaste that is unique in that it is not water based. Colgate's Optic White is not water based, which means they can add a higher degree of hydrogen peroxide to actually whiten your teeth. All other \"whitening\" toothpaste contains abrasives that basically sand off any extrinsic stains. Hydrogen peroxide is the key ingredient in whitening strips and dentist office treatments. Due to the hydrogen peroxide in Optic White, it does actually whiten your teeth. The water based toothpaste formulas can't have a high amount of hydrogen peroxide because the tube explodes. Crest 3D White toothpaste is just a catchy name and doesn't whiten your teeth any better than the cheapest Colgate toothpaste. Some of the Sensitive toothpastes have an ingredient that does block the tooth tubule, preventing pain (typically KNO3). These must be used continually to have the effect. Sensodyne is the most common and expensive brand out there, but doesn't really have any ingredient that is better. Save yourself some money and buy Colgate Sensitive for a quicker longer lasting effect.",
"Dentist here. What ever one you will use that has fluoride is the best one. Simple as that. If you have sensitive teeth Sensodyne is the only one clinically shown to help but toothpastes with SnF have efficacy there too."
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5utqb4 | Why does light need to consist of particles to explain the photo effect? | Physics | explainlikeimfive | {
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"We know from the wave picture of light that there are two ways you can increase the energy you are delivering to a system if you shine light on it. You can either: * Increase the amplitude of the light wave i.e. the height of the wave, making it brighter. * Increase the frequency, i.e. the number of wave peaks packed into a certain time period, shifting the colour. Now, when you shine light on the surfaces of certain metals, you can liberate electrons. What you find is that you will only see a photocurrent (current of electrons liberated by light) above a certain frequency of light, unique to each metal. As you turn up the frequency, the number of electrons reaching your collector will increase. But, importantly, the same effect is not observed if you increase the intensity of the light. So what are our observations? * There is a minimum frequency of light required for electrons to be liberated, and therefore a minimum energy. * Turning up the frequency increases the number of electrons we detect. * Changing the intensity has no effect on the observation of electrons. This means the energy has to be delivered to the electrons all in one go. The only logical conclusion is that the light must be delivering energy to the electrons in discrete packets, or quanta, to push them out of the metal, and that the energy of each packet is proportional to the frequency. When one of these packets, which we call a photon, hits the electron, it delivers it its energy, which will free it from the metal if it's enough. Any excess will be given as kinetic energy, meaning faster moving electrons that can travel further and hence more will reach our collector. The photoelectric effect is fundamentally inexplicable by the wave nature of light, and the particle nature is the simplest explanation which turns out to also give us views into a whole world of other phenomena related to quantum mechanics. Indeed, QM gets its name from quanta, which refers to discreteness."
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5utrh0 | Why is it more refreshing to drink cold water? | Biology | explainlikeimfive | {
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"Because the human body perspires, and drinking cold water cools down the body, which is why we enjoy it so much."
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5utrug | When a game on Steam is on sale - who gets the smaller cut? Is Steam making less money when something has a discount or is it all on the studio? | Other | explainlikeimfive | {
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"They both would make less money—per sale, at least. Steam takes a cut of all sales for providing the distribution platform (I think it's around 30%) so if the studio decides to put their game on sale, Steam gets the same cut percentage but the amount of money they're taking their cut from is less."
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5uttju | How can we know for certain if a number is truly irrational | For example if we take Pi if we find an end then the proof that is rational would be: 3.14x10^e Over 1x10^e if e is the number of digits after the decimal place in pi | Mathematics | explainlikeimfive | {
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"The most common way is a proof by contradiction, which is a style of proof where you assume the opposite and then show that doing so results in something that trivially cannot be true, so we assume that pi is a rational number and then show that that would require that two mutually exclusive things be true. In the case of pi being irrational, the actual proofs we know require some reasonably advanced mathematics, but you can see some at URL_0 .",
"yeah, it's mostly by contradiction, i.e. assume that a number is rational and show it can't be. this is easily done with the square root of 2, for instance, using a contradiction proof that shows that if we write sqrt(2) as a/b, where a and b are integers that are wholly reduced to share no common factors (which is the definition of rational) then some math will show you that 2 = a^2 / b^2 and further math shows that they share a common factor, thus contradicting the original assumption."
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5utulm | how come the rings of Saturn orbit on a flat plane around the planet, as opposed to evenly spread out? | Physics | explainlikeimfive | {
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"Same reason why the planets are in a relatively horizontal plane around the sun. Angular momentum is conserved, so as orbiting materials collide, they eventually settle into a disk. What conservation of angular momentum means, is that the total sum of each particles momentum, must but equal to their ending momentum. So you get a lot of chaotic collisions when the cloud first starts, but as more and more collisions take place, more and more of the upward and downward momentum is converted into horizontal momentum. This creates the plane or disk."
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5ututa | Why is coffee almost impossible to be reheated without it tasting burnt and is there anyway to prevent this? | Chemistry | explainlikeimfive | {
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"Not really. A lot what you're tasting is actually the changing in flavor of the oils as they pick of contaminants, and the loss of the strongest and most aromatic flavor notes which are composed of very volatile molecules. In short, coffee just doesn't last long, even as a bean. Once you brew it, the clock is really ticking. Ice coffee is then solution, because the cold mutes the bitter notes and you end up with something closer to a milder version of the original.",
"I found that keeping coffee in a thermos preserves the taste much better than actively heating it.",
"Coffee tastes different when it's been sitting out for a while because compounds in it become oxidized from exposure to the air and because the high temperature (for hot coffee anyway) accelerates chemical reactions which ultimately affect the flavor. There are other factors that affect staling of coffee but the big ones are oxidation and temperature. These chemical reactions can't (realistically) be reversed so you wont ever get the freshness back, and by reheating old coffee you'll only increase the rate of chemical reactions which lead to it being stale in the first place. If you kept brewed coffee somewhere with no oxygen and at a low temperature then you could reheat it later and it would probably taste fresh. Once you pour coffee into a mug and it's exposed to the air and ambient temperature then it's just a matter of time before it becomes stale.",
"We make coffee with a chemex Pyrex maker along with the suggested filters. The thicker paper filters out more of the compounds that make the coffee bitter. I reheat it all the time and it tastes nearly as good as fresh brewed. I really recommend this method of brewing. I like that it's all glass -- no plastic to leach plasticizers... and the coffee is so good. Not as easy as an auto drip system... but worth it.",
"Microwave back to drinking temperature, not to actual hot temperature?",
"We used to brew our coffee, then turn off the heater, letting the temperature drop to room temperature. It stayed fresh tasting to the end of the pot. For food safety, we started refrigerating our brew, microwaving to drinking temp.... no waste. We now cold-brew for even better tasting coffee."
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5uu1bn | Why does metal make sparks in the microwave? | Other | explainlikeimfive | {
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"When microwaves are running they are essentially pumping the small space full of energy in semi-random interference patterns, which leads to hot spots and cool spots. Inside the metal of a fork or a piece of foil this energy gets turned into random electrical potential as electrons get excited and this leads to things like sparks, but only at areas where the width of the metal is, IIRC, near or less than the width of the microwave, for instance the edges of the tines of a fork. The 'sharp' areas tend to be where electrical arcs occur. A thick metal table spoon in a microwave may not have edges thin enough for this to happen. It will still get hot much faster. It is also dangerous to put foil in a microwave because it gets very hot very quickly, and this can lead to fires. I had a cookie the other day which I suspect had a tiny bit of foil stuck to it because it burned a hole in the cookie when I reheated it. For other fun things you really should not do with microwaves, search for 'microwave plasma ball' on youtube."
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5uu3tg | How do creatures like birds and butterflies know when/where/how to migrate? | Biology | explainlikeimfive | {
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"As far as my studies have gone, it's instinctual. Some birds use the earth's magnetic field, some use their parents and follow them and learn the path, others are genetically engineered to just know where to go. There's a term in ecology that we borrowed from German - zugunruhe. It's basically how animals exhibit anxious behavior around migration times. I suggest looking into the specifics. Really cool stuff."
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5uu4ze | Exactly how much of the U.S. economy depends on labor from illegal immigrants? | Economics | explainlikeimfive | {
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"text": [
"It's hard to know exactly because it hasn't happened yet, but a [conservative think tank estimated that Donald Trump's plan would shrink the US economy by 2%.]( URL_0 ) The US economy would shrink by about 400 to 600 billion dollars."
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5uu73s | How can a wireless router send MILLIONS of bits of information to a computer in only 1 second? | Technology | explainlikeimfive | {
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"text": [
"It sends them one after the other... and really, really fast. What are wondering about specifically? Edit: read the following answer"
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5uu7yf | Why are Arizona Iced Tea drinks allowed to place a price on its product? | Other | explainlikeimfive | {
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"Why *wouldn't* they be allowed? There's no law forbidding the printing of a suggested price on a product. In fact, lots of companies do it, including many different brands of potato chips, [like these]( URL_0 ). Generally, the company that produces the food item will only sell their product to retailer who sign a contract agreeing to sell it no higher than the printed price.",
"There is no law preventing them from doing so. Why would such a law exist?",
"Note that while a manufacturer is free to put a price on their product, a retailer doesn't *have* to sell it at that price, unless they sign a contract stipulating that. But if they try and sell it for more it will annoy the customers."
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5uua84 | What happens when you run a Windows program in Compatibility Mode? | Technology | explainlikeimfive | {
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"text": [
"Windows systems change over time, with new versions. Even if a program's code is still executable on a new windows version, an older program might depend on other files that older windows versions almost always had stored on the system, or it might depend on some windows features that have now been abandoned. Compatibility mode attempts to overcome this by applying workarounds and translating an old, outdated function to a new function that can do the same but in a different way. For example, if a program looks for a certain file that used to be in the user folder on Windows 98, it might not find anything where it expected the file, because on windows 7, the folder where user information is stored has now been moved elsewhere. If the program isn't programmed with a way to overcome this problem, compatibility mode can attempt to redirect the program to the appropriate location. Another example could be if the program attempts to load a dll-file that on a version of windows used to be in system32, but now is in systemwow64 instead. It wouldn't find the dll, and the program would either cease to function, or function with limited functionality. Compatibility mode would override the program's request to load a dll from system32, and instead hand it a file from systemwow64."
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5uub02 | Other than just being awesome, what benefits does space exploration have? | Other | explainlikeimfive | {
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"Mastering spaceflight (i.e making it cost and time efficient) has several benefits to it. Being able to travel to other planets and moons would give us more living space when the Earth gets too crowded, not to mention it would give us the capability to save our species from extinction in the event of a disaster like a planet-wrecking meteor. Asteroid mining would be a huge step on the way to a post-scarcity society, as many of them contain massive amounts of minerals, just like moons and other planets contain different gases and resources that we desire and will eventually run out of here on Earth. It would present a new, endless frontier for us to explore and science would be advanced in response to the plethora of new needs and research opportunities presented by space exploration. It could answer one of the oldest questions there is - are we alone out here? Arguably the most dangerous thing we can do, but it'd be possible to find other intelligent, possibly spacefaring species out there.",
"Scientific discoveries, finding things that can't be found on earth, and subjecting them to scientific experiments to gain better knowledge about how the universe works. Scientific progress isn't always easy to quantify. A discovery that might just be considered curious today might be one of the building blocks for an much more complex and groundbreaking theory later. Lots of things we take for granted today were made possible because someone just randomly found out something weird 50-100 years ago. They had no idea at the time what their discovery would enable 50 years later. It also advances the field of engineering, as spaceflight requires better and better materials in order to perform their missions safer cheaper and faster. The technologies developed for spaceflight often trickles down to consumer goods some decades later. Here's a link to what NASA themselves consider noteworthy inventions based on technology developed entirely or in part by NASA. URL_0"
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5uub63 | Why do high performance engines pressurize their gasoline more than regular engines? | Piggy backed off of the post asking about the difference between regular and premium fuels. Also (semi-related), why couldn't a high performance engine use less pressure? | Technology | explainlikeimfive | {
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"text": [
"The amount of power an engine produces is a product of how much exploding it does. One way to increase exploding is to make bigger exploding chambers. That makes the engine bigger and bigger engines are heavier and limited in how fast they spin. If i want to make a smaller engine that does more exploding I need to find a way to do so in my smaller chambers. I have some options. I can explode a different fuel. Many racing cars use very high octane fuel for instance. But if i am building a car for the street i can't do that. So i need to find a way to explode more regular fuel. I know that i need more fuel forced into my small chamber to explode. But if i just put more fuel in there it won't all burn and that is bad. So I force more air in there to help all the extra fuel explode. So it takes both more fuel and more oxygen to do that.",
"Simple answer: the more stuff you cram into the same space, the more stuff is in there. The more fuel you stuff (higher pressure) into the same space (the cylinder) the more fuel there is to explode when the spark plug ignites."
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5uufai | What is light actually? | What is light? How does it get from the their source and to our eyes, and how is it formed? | Physics | explainlikeimfive | {
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"There's something called an electromagnetic field that is everywhere. When you put energy into it, it ripples. These ripples are light.",
"Light consists of particles called photons. A photon is an excitation of the electromagnetic field, which exists everywhere in all of space. Photons can also exhibit wavelike behavior; a single photon can interfere with itself and create patterns that one would think would only be possible with multiple photons. You know how throwing a rock into a lake makes a ripple pattern? Imagine if the exact same pattern was being created by a single droplet of water! Lots of things can cause photons to be generated. For example, when an excited electron falls back into a lower energy state, the atom emits a photon with an energy equal to the difference between the two electron states. Photons always travel at the speed of light. *Always*. Even in massively refractive materials, the actual photon never stops moving at the speed of light, but rather its path is altered such that it takes the photon longer to move through the material than it would through an empty vacuum. The photon gets to your eye by moving through space. To us this takes a measurable amount of time. From the photon's perspective (if it had one, that is) its creation, journey, and end all happen instantaneously. Photons can exist in a huge range of frequencies, from the radio waves we use to communicate, all the way to x-rays and gamma rays, which are energetic enough to seriously mess you up inside, killing your cells and screwing up your DNA. What we think of as \"light\" in our day-to-day life consts of a very small range of frequencies, roughly from 400 nanometers to around 700 or so."
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5uul28 | Why is Potassium Sorbate (Preservative) still so widely used if it has possible Toxic / Carcinogenic properties. | Obviously theres a lot of crazy sites out there that make wild claims. Im in no way asserting that these claims are true, which is partly why im doing this ELI5. A few days ago I had some flavoured water and read through the ingredients list, as you do. I spotted Potassium Sorbate. Then today I had a can of Fanta, again; Potassium Sorbate. Later today I bought a drink, and yet again Potassium sorbate. So, out of interest I researched it. After this the sources used seem to show that whilst serious side effects seem to be in theory rare, it seems like an extremely dangerous compound relative to other things. I would also like to note; Im well aware that there are many, many questionable chemicals in food. They dont bother me to be honest, but Potassium Sorbate seems to be the only one Ive come across that people basically say "Yep it could cause cancer, you should probably stop consuming it". Anyway, down to the ELI5. If Potassium Sorbate is according to these sites unquestionably a Carcinogen, how come it used *everywhere*. It astounds me how it hasnt been banned based on the info from these sites. | Chemistry | explainlikeimfive | {
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"The dose makes the poison. A little bit of sunlight helps your body make Vitamin-D. A lot of sunlight causes skin cancer. A little bit of potassium sorbate keeps fungus from growing in our food. A lot of it might cause cancer. You'd have to eat about 20-60 times the amount of food you usually do to reach the potassium sorbate levels that start to cause damage. I wouldn't snort the stuff, but the small amount in your food is great. URL_0"
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5uulzl | How are boneless fish made? | I have seen plenty of those, where there's a whole fish, and it as just no bones in it, as if it never was born with any (I doubt that, though.). What's the process behind it? | Other | explainlikeimfive | {
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"text": [
"When they slice open the fish to pull its guts out they pull out the bones too since they are all connected."
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5uunub | what's happening to a person's mind when they're over amping and digging worms out of their arms | Other | explainlikeimfive | {
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"I take it this means \"What's happening when someone overdoses on meth, and starts self-harming?\" Meth abuses a brain chemical called dopamine, which is \"encouraging\". It makes us feel interested, motivated, encouraged, to do something. But it's part of normal psychology, and we can resist impulses if we have a reason not to do them, or to do something else. We'll normally stop picking at cuts, or scratching, or whatever, when we realize it's going too far. But with stimulant drugs, someone feels so \"encouraged\" that they may not be able to stop. It seems very important, irresistible, and necessary to them."
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5uup4b | Bio/Organic Chemists:Can you identify whether a particular organic is edible (fat/protein/carb), a drug, a poison, or not edible (ex: byproduct of crude oil)? | If so, is there some way you can describe it (ELI5) how you know? Would you be able to to describe it to a person that passed high-school biochemistry? Edit: When i say organic, i mean organic compound looking at the picture of the carbon structure. | Chemistry | explainlikeimfive | {
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"In general, simple crude oil derivatives are long, straight chain carbon chains with just hydrogen attached. For example, butane (like in camping gas) is 4 carbons with 10 hydrogens around it. A heavier, longer carbon chain of 8 carbons (octane) is a liquid. The longer the chain, the stronger the interaction between each chain and so it follows gas > liquid > solid. Now as for proteins, they're made up of amino acids, which are small carbon chains with an amine group (NH2) on one end and a carboxylic acid (COOH) on the other. These have various side chains that make 20/21 separate amino acids. These link together through peptide bonds (amine + carboxylic acid) to form long, curling, complicated structures called proteins. Fats , or lipids, are generally harder to classify, but they will have long, long chains of carbons attached to some head group. As with crude oil, the longer the chain the more viscous the fat - unsaturated fats (with double bonds causing the chains to bend) cannot stack together as well as saturated chains, so do not have as strong interactions and so are less likely to build up and clog your arteries (in very simple terms). As for poisons and drugs, that's a lot harder. They will be cyclic (have ring structures) but they vary massively. There is usually a functional group that will attach to whatever needs to be affected by the molecule, and contain nitrogen, sulphur or a few other natural elements. They could have amine, alcohol (OH), methyl (CH3) or aldehyde (COH) groups. If you google pictures of LSD, morphine or epinephrine (adrenaline) , you can see the similarities. It's also worth noting that a lot of poisons are proteins (like ricin) or bacteria (like anthrax) or salts of elements (like arsenic) rather than single molecules."
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5uup4g | Why does a room being kept at 70 degrees via air-conditioning feel colder than a room being kept at 70 through heating? | Physics | explainlikeimfive | {
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"Human's perception of temperature is relative. You can only tell if something is hot or cold relative to something else. The air-conditioned room will feel cooler because you're comparing it to when the room was warmer. The opposite is true for the room being heated. There is a simple experiment you can try to prove this. Line up three bowls that your hands can fit into. Put very warm water in the bowl on the left and put cold water in the bowl on the right. Put room temperature water in the bowl in the middle. Now stick your hands in the left and right bowls and keep them there for a few minutes. Now stick both hands into the bowl in the middle. All the water in that bowl is the same temp but one hand will feel cold and the other hand will feel warm. Pretty shocking if you've never tried it before.",
"Rooms aren't heated/cooled to a particular temperature by blowing that temp air into the space. Furnaces send 100 degree air out, while A/Cs blow 50 degree air, each of which mix with existing air until it reaches the desired temp. So you'll feel that hotter or cooler in spots since the heating isn't uniform across the space.",
"Heated air is relatively dry, cooled air is relatively humid. That changes perception a lot.",
"A typical thermostat can only read the temperature where its sensor is located, which is typically close to the center of the room to try and measure the average temperature of said room. so with a/c you will have cold spots in the room and hot spots with a furnace (compared to what the thermostat is set at) What dodgeball rocks said is also correct, how your body is climatized also plays a big part in how hot/cold you feel."
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5uurte | why do credit cards not have a PIN number attached to them? | Economics | explainlikeimfive | {
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"They do on Europe. Americans are resistant to the change and they don't wanna risk losing customers over forcing them to have a PIN to use their card. Ruh roh, I hope this answer isn't so small it gets autobaleeted.",
"In the UK all cards have a pin attached. Newer cards will also have a contactless option, but that only allows payments of under £30",
"The cost associated with that for larger companies is in most cases $1,000,000+. The hardware isn't cheap, and modifications to the software to handle the new requirements is also expensive. Years ago when Europe went to pin & chip the estimated the cost of the US doing it was in the billions... it was in the $10million+ range just to convert the cards over.",
"I remember reading that it was because the US pioneered the credit card technology, while the rest of the world implemented it later, when it had matured enough. Thus, the US was using magnetic strips while the rest of the world started with chips, protected by PINs. Since the card reader and most cards where magnetic strip-adapted, it was too expensive to change it to chips.",
"This is a holdover from the beginning of credit cards. Credit cards used to be processed completely offline. Your card would be imprinted onto a charge slip, and then the charge slip would be mailed in to the credit card company to collect the money. In the very beginning of credit cards, these charge slips would be mailed back to you with your statement. When chip cards were introduced, American credit card companies thought that it would be too much change to require PINs, and that consumers would use credit cards less. So they left the signature verification in place. Because credit card fraud ran rampant in the US for decades, American credit card companies invented other forms of fraud prevention. The biggest one used is abnormal purchase monitoring - if you live in Cleveland but all of a sudden there are like $5000 in charges in Moscow, the credit card network will go all, \"Hm, that doesn't make sense.\" This is why you have to call your bank before you go on a trip. Alongside believed consumer reluctance to use PINs, merchants protested having to purchase PIN pads on top of costly new chip card readers."
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5uusdt | How exactly do we hear ourselves talking when we think? | Biology | explainlikeimfive | {
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"When we speak out loud there are 2 signals that the brain receives: the internal monologue and (assuming you are not deaf) auditory feedback from our speech output. This may be why we tend to think we are speaking louder than we actually are. Your brain also receives a 3rd feedback signal from the articulation/speech muscles. Your brain learns to associate all 3 signals with each other (thinking a word, with the sound of the word, and the movement of the speech muscles needed to speak the word). So if you are thinking internally, your conscious brain will only receive the internal monologue signal. But as I mentioned, the internal monologue is extremely closely related to the production of speech (this topic is known as \"embodiment\"). Studies show that when people read text silently, muscles used for speech are slightly activated. Also, speech production areas of the brain are activated when people speak internally. This all suggests thinking and speaking use similar neural pathways, and so the brain perceives thinking almost like speaking. Note: this is referring to clear-cut intended internal speech. More ambiguous \"thought\" is going to be much more complex. tl;dr: The act of speaking, the sound of speaking, and the internal thought which is correlated with the speech, are all highly associated with each other (They use similar brain pathways). So when you \"hear\" yourself think, it is probably because you are activating the same brain pathways used for normal speech and hearing",
"There was a thread about this not long ago where it became apparent that many people, including me, don't 'hear' themselves at all and find it weird that others do.",
"Fun fact to add to everyone else's answers: Deaf people that use sign language as a first language think in sign language. Also: ESL students with two equal first languages can go back and forth between languages pretty seamlessly in thought.",
"I think about this all the time. I have a lisp and stutter alot when I talk out loud, but the voice in my head has no speech impediments.",
"I don't know the answer, but when I read to myself, not only do I hear myself, my tongue quietly moves as I involuntary mouth the words. No words come out, and there is minimal movement to my lips. I have also noticed this (lip movement) happens when I'm mad at someone and I argue with them in my head. Also I will make facial expressions as well. I can only imagine what anyone who sees me might think.",
"The reason one can actually hear one's own voice or music in one's head, or sounds during dreams, is because the signal paths from the primary sensory processing areas to the parts of the brain responsible for thought and self-reflection aren't necessarily one-way. The higher areas of the brain can send signals backwards and stimulate these areas to produce sounds, images, etc. In situations where one is more isolated from external sensory input, such as sleep or a sensory deprivation tank, these sensations can become vivid enough to be mistaken for real.",
"You're basically talking about metacognition. It's the ability to understand that you hear yourself thinking. It's a super interesting area of psychology. I'm drunk as fuck otherwise I'd link sources.",
"It is marvelous. All that is you are the stories you know and or believe in. Many of these clips drop unused on the cutting room floor. Most, though, make up you and the stories you believe. Let us keep focused on your question and not include genetics. With one exception, all of the words we think about do, though, include genetics as a foundation, OK, enough of that. Let us consider, this the inner monologue never stops during our consciousness. There is always some kind of flurry of disjointed or coherent words flowing from where to where? What we are hearing are words, sentences, paragraphs, and on we go. Yet, back to your question, keep in mind that you do not own this inner monologue, it happens. You don’t control it. In the brilliance of youth they are extremely vivid monologues. As you grow older you lose your acuity as you do your muscle fibers. That should be enough of a scaffold to answer your question. The answer to your question lays in what is listening to this monologue. What is listening is your body and as your body is the instrument of the brain, it plays on and on. This music coincides with your emotions that start the process. The genius of the system is that as these musical vibrations flow in and around your whole body, so does your body, using the same instrument to emerge as your awareness of what you are thinking. We are music beings. Think of stones thrown into a little pond. Each of the waves created continue on the way uninterrupted so that when it encounters another wave they slip through each other. I guess there was a little more scaffold required to understand the answer after all. Yet, now we are ready! The anatomical devices that form words out of these directed emotions is physical. Vibration enters the interpreter and from the interpreter, words emerge according to our culture and upbringing. Well, where does free will come into this? When do we control these thoughts? We don’t. The words that flow through us are a river of words and like a river directs itself on a course of least resistance. There is no free will. The watched is simultaneously the watcher. This watcher translates these codes into a learned language. All this is possible because each of us has a personality and it is this that is the course of least resistance. What you say to yourself is heard using your ears, but in this case there is no outside vibrations.",
"I can't quite explain why it happens but I find that repeating something easy like 1 2 3 4 shuts this off in your head because your vocals are occupied. It helps me to think more quickly or speed read through something."
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5uv2vl | What is Thiomersal and why is Robert De Niro and Robert F Kennedy so concerned about it? | Chemistry | explainlikeimfive | {
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"Thiomersal is a compound that is used to increase the shelf life of vaccines. When people started claiming that vaccines cause autism (even though there's no evidence of this), they pointed to thiomersal as a possible culprit because it contains mercury and they've heard that mercury is bad for you (even though there's no evidence thiomersal causes problems at the levels found in vaccines). As part of a general effort to reduce exposure to mercury, vaccine manufacturers in the US stopped using thiomersal in vaccines intended for children in 2001. Despite the fact that removing thiomersal from these vaccines had no impact on autism rates, and there not being any scientific studies saying otherwise, many people continue to point to it as a possible cause of autism in children.",
"Compounds that contain mercury are called organic mercury compounds. An organic mercury compound is made up of a Mercury atom that is linked to another group of atoms, and looks like: R---Mercury where \"R\" is an additional group of carbon atoms, which are described by the name \"methyl\" or \"ethyl\", depending on how many carbon atoms are in the group. This is important, because the number of atoms in the carbon group greatly influences how that compound will behave. It is widely known and established that organic Methyl-mercury is extremely [toxic]( URL_0 ), and potentially even more toxic than elemental Mercury, or Mercury with no other atoms linked to it. Ethyl-mercury is less toxic, and is used as a preservative in vaccines. What has been debated is the toxicity of Ethyl-mercury, however I should stress that there is *no evidence whatsoever* that Ethyl-mercury causes autism in any way. A [recent study]( URL_1 ) (may be paywalled) looked at Ethyl-mercury and the effect of toxicity with Methyl-mercury, and several others have examined the toxicity of Ethyl-mercury. So far, there seems to be no conclusive evidence that Ethyl-mercury causes neurological or other damage in the amounts that are in vaccines (the influenza vaccine uses Thiomersal), or would potentially be in vaccines."
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5uv8wr | Why do people claim that Fluoride is harmful? | Biology | explainlikeimfive | {
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"From my understanding it's just one of those things really paranoid people freak out about. Fluoride can be harmful to humans in large doses over long periods of time but brushing your teeth with it is never going to hurt you. Kinda like how some people think vaccines cause autism in kids. It's not backed by medical science but some people think they know better",
"Essentially hogwash. It's one of those things people freak out - it sounds scary, flourine can be harmful in certain forms, and people don't trust the government to do anything. However, it can be harmful if you overdose (one of the reasons you're not supposed to swallow toothpaste), but it's nothing you need to go crazy worrying about. It's not going to happen in the levels found in community water supplies. via: URL_0 > Prolonged ingestion of fluoride through drinking water, in excess of the daily requirement of 1.5 mg/L as the upper limit (as set by the WHO) is associated with dental and skeletal fluorosis.[2] Signs of skeletal fluorosis become evident on consumption of 8–10 ppm of fluoride in drinking water for approximately 10 years or more.[9] Note 1.5mg/L is roughly ~~ppm and URL_1 > Starting in 2015, the recommended level is 0.7 milligrams of fluoride per liter of water > National survey data show that prevention of tooth decay can be maintained at the recommended level of 0.7 milligrams of fluoride per liter of drinking water. This recommended level updates and replaces the previously recommended range of 0.7 to 1.2 milligrams per liter. > *Experts have weighed the findings and quality of available evidence and concluded that there is no association between water fluoridation and any unwanted health effects other than dental fluorosis.* > The independent, non-governmental Community Preventive Services Task Force has noted that the research evidence does not demonstrate that community water fluoridation results in any unwanted health effects other than dental fluorosis, a condition that causes primarily cosmetic changes in the appearance of tooth enamel.",
"It is hogwash. Fluoride is found naturally in drinking water in many places and it has a proven beneficial effect in preventing tooth decay (it was the natural sources of fluoride that made dentists realize why some areas had much lower incidents of tooth decay than others). The amount added to drinking water is less than that found in many of these natural water sources that people have been drinking for hundreds and hundreds of years. There are *some* valid concerns (should the government be allowed to dictate that some additives be added to drinking water? Etc) but most of these fail to see how beneficial water fluoridation is or they have made up claims of mind control chemicals or other ridiculous things to make their case.",
"I have fluorosis. When i was young, i swallowed my toothpaste. I thought it was what you did when you are done with it. As a result, i had high doses of it in my bloodstream. It actually did permanent damage to my teeth (deep yellow pits) and sensitivity. There is also such a thing as flouride poisoning, but i do not have anecdotes about this. For every hundred or so people who benefit from flouride, there are a few like me. I do not know water fluoridation has or increases this effect but it should be considered by the \"flouride can do no wrong\" group.",
"Not going to say that it's harmful, but flouride, chloride, bromide, and iodide are all part of the halogen group. Your thyroid needs iodine/iodide to function. Your thyroid cant tell the difference between the halides, excess flouride and chloride from tap water and bromide from bread, over time replaces the iodide in your thyroid and can lead to an imbalance of you don't keep up on iodine. Try starting an iodine supplementation and you'll eventually have a metallic taste in your mouth as the other halides are flushed from your system. Don't quote me on this, I could be wrong, but this was essentially the ELI5 that my Dr gave me. Don't get me wrong, I'm not one of those conspiracy theorists and I don't avoid tap water or anything like that.",
"Because it is harmful, just not in the quantities we are exposed to - people really like to exaggerate. A lot of substances are harmful/toxic in large quantities but we use products containing those substances all the time because the amount we get from those products is not anywhere near the unsafe levels. Unless you eat your fluoride toothpaste on purpose you won't reach unsafe levels of fluoride. In small quantities it is found in water and toothpaste it is good for your dental health.",
"fluoride can be harmful if you consumed in large concentrations. That said the amount of fluoride that is put into our water supply is well below what our body can properly filter out.",
"I don't like the government mass medicating an entire population on the pretext a percentage can't maintain a personal hygeine program. The fluoride added to my water supply comes from a by-product of the fertilizer process. It is a toxic substance that cost the industry a lot of money to dispose of before they had the great idea to just dispense it in the populations water supply.",
"Because it accumulates significantly in the pineal gland and elsewhere in the body in order to get the job done. Fluoride is meant to \"saturate\" your body so that it ends up in your saliva. People always argue the amount is so small it does nothing etc but the fact is it does get stored unnecessarily and there are some very decent reasons to believe it could cause issues later in life. I can link studies if you want. edit: forgot mb. see /r/fuckfluoride you can find some there"
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5uv9ff | Why do metals change color when they're heated? | Why do metals turn red when heated? I would think it's got something to do with excess energy being converted to photons somehow, but that's all I got. | Physics | explainlikeimfive | {
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"You are correct, the metal becomes brighter as temperature goes up due to highly energized photons being expelled. Also the automoderator can go choke to death on a bag of dicks. As it becomes hotter, they turn yellow, orange and then finally white, you can see that phenomena in the gun barrels of the M134D Gattling gun."
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5uvc4b | Why was the electron planetary model incorrect, and what is the currently accepted model? | Chemistry | explainlikeimfive | {
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"Almost as soon as the planetary model was created, scientists recognized a problem with it. If the model was correct, why don't electrons gradually lose energy as they revolve around the nucleus? But initially, no one had a solution to this puzzle. It wasn't until quantum mechanics that it was recognized that electrons (and other subatomic particles) aren't just tiny little spheres. They are more like \"matter waves\" with poorly defined positions in space. Electron positions inside of an atom are described as [orbitals]( URL_0 ), and take on a variety of shapes, depending on the atom in question. If we try to pin down the position of an electron, it will *mostly* be found inside of that volume. One of the weird things is that electron positions are described using probabilities, and (in most cases) the probability never quite goes to zero, even for locations far away from the nucleus. So in theory, an electron from a given atom could be found anywhere in our universe.",
"the electron planetary model shows electrons as particles in orbit around the nucleus. electrons actually act more like waves. you can never know for sure where it will be, only the probability that it will be in a given area."
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5uveru | Why are old 90s PC games so twitchy and fast on current computers? | Technology | explainlikeimfive | {
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"Because many of them tie their internal timing to the speed of the cpu clock, making the game run faster the faster your cpu is, not unlike how many console games on PS2 and earlier were coded. Not all games were coded like this, however."
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5uvfd2 | What causes a sunburn and why does it lead to a tan? | Biology | explainlikeimfive | {
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"A sunburn is literally your skin being burnt by the sun. More specifically by the UV (ultraviolet) rays which carry more energy. A tan is a defensive response from your skin which secretes more melatonine and goes darker. Why ? Because the more dark your skin is, the more radiation it can absorbs, converting ultraviolet rays into heat instead of \"deflecting\" it (and therefore taking damage in the process). More generally, having a darker complexion makes you radiates more heat and more resistant to the sun rays (useful in southern area), whereas having a light complexion makes you retain more heat but more vulnerable to the sun (useful in northern area)."
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5uvfiv | What is the difference between MP and resolution in a camera? | For example, a 4K photo is 3840 x 2160. This is equal to around 8.3 million pixels, or 8.3 Megapixels. So in a camera, what is the point of having 16MP, or 20MP or more, when the resolution only shows 8 million? | Technology | explainlikeimfive | {
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"I'd imagine it'd be for clarity when blowing up images. the additional megapixels allow for images being scaled up to maintain their sharpness.",
"As other people are spectating is correct; For clarity and zoom. A good example is this link here, URL_0 , you can still read license plates from 8 blocks away with this 320 gigapixel shot. Your camera can still zoom into the image and with a higher megapixel the image still remains sharp (as long as you took a good photo) while if you were to take it with a 8.3 megapixel camera it would become more and more blurry."
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5uvige | When you turn a cup/bowl of water in your hand, why does the liquid inside seem to remain still while to cup turns? | Physics | explainlikeimfive | {
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"Think of the cup and water as two different objects. You are providing forces for the cup(object 1) to move, buy you are not directly involved in the moving of the water(object 2). The water is moved by a coefficient of friction from the cup. As cups are usually quick smooth, the effect of friction is very low resulting in very little movement of the water. The basis for all of this is that \"an object in motion will stay in motion unless acted upon by another force\", similarly an object at rest will stay at rest. Since the cup and water are two different objects, the water will stay at rest unless friction can provide enough force to move it."
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5uvkud | When you get pulled over by a cop and they "run" your license, what are they actually doing? | Other | explainlikeimfive | {
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"They are checking your id against numerous databases to see if you have outstanding warrants for your arrest, if this is a repeat offense, if your license is up to date, if your license has been revoked, etc.",
"I would like to point out that there is an /r/AskLEO subreddit, where you can directly ask law enforcement officers questions"
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5uvn4r | why does being hungry cause me to get a headache and be in a terrible mood? | Biology | explainlikeimfive | {
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"Blood sugar levels, the brain runs off of sugar, so when you are hungry or when you have low blood sugar, this is your brain telling you to refill the stores."
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5uvpa3 | What's he difference between Karate, Tae Kwon Do, Jiu jitsu, and Judo? | Other | explainlikeimfive | {
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"Kicked in the face, punched and kicked in the face, thrown down on your face, bent in a postion where you can see your face",
"Karate is a Japanese art developed originally in ancient Okinawa. It's become a blanket title for many empty hand combat arts. Many different styles have diverged from the original Okinawan line, giving hundreds if not thousands of offshoots. Some considered watered down, others more true to their original roots. It consists of strikes with open and closed hands, and kicks to vital areas, intended to put an attacker down quickly. It's practiced with a partner or in katas, which are solo movements that are designed to hone your footwork, hips, and coordination. They were created with a concept in mind. To deal with attacks from certain angles or multiple attackers, but sadly in many styles it's just become the memorizing of movements with no explaination. Tae Kwon Do is a Korean martial art, it's often used interchangeably with karate in America, but their origins are different. There are similarities in methods, but Tae Kwon Do tends to be more kick heavy, and in some styles, striking with the hand has been abandoned all together. It use to be the world's most widely taken martial art because it became so kid friendly, some would say watered down. I wouldn't be surprised if Brazilian jujitsu has dethroned it. There are still very legitimate schools of Tae Kwon Do out there, but do your research. It's trained with partners, and katas, and weapons, as well sparring. Often times point sparring. Jiu-jitsu is a Japanese martial art considered to be one of the samurai martial arts. It consists of strikes to critical areas, joint manipulation, chokes, and some ground fighting. It's the father of Brazilian jiujitsu, and judo. It's trained with a partner. Judo is a Japanese art designed to incapacitate attackers/opponents by taking their balance and throwing them, or breaking limbs and choking. There are very few strikes thrown in Judo, but practitioners are known for having impeccable balance and powerful hips, and the ability to fight on the ground with joint manipulation. By using their hips, timing, the opponents energy, and leverage, judoka can generate some amazing and dangerous throws. It's practiced with a partner, usually with high resistance. Both jiujitsu and judo require a lot of training in learning to fall, or, ukemi.",
"Karate and TKD focus mostly on standing combat, punches and kicks. Judo focuses a lot on grappling, controlling and throwing opponents. Jiu jitsu is about taking your opponent to the ground and controlling them there, either by controlling limbs or by choking them."
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5uvq05 | Byte Storage | When a program or software claims to require "x amount of space", what exactly is happening? Such as if on a 3DS, a game claims to require 200 units of space, is that just 0s and 1s being inserted on an SD card? How and what is "put" on a hard drive or SD card exactly, 0s and 1s? Sorry if this is confusing. | Technology | explainlikeimfive | {
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"Think of an SD card like a piece of graph paper. You can fill in squares and erase squares to create block pictures. You're never physically adding squares to the paper, you're just drawing and erasing sections of the already existing papers. So you're limited by whatever size of paper you have. To make a bigger picture, you need a larger section of the paper. If you fill the entire page with pictures and want to make another picture, you either need to get a new piece of graph paper or you need to erase some of your previous pictures to make space. You're not literally coloring in the square on a hard drive, but it's the same idea. For a hard drive, you set the magnetic polarity (+ or -) of each tiny block of the hard drive. For an SD card and other solid state memory (like flash drives), you're changing the way each block reacts when you send electricity through it. Devices with more storage are capable of reading and writing smaller sections (like having smaller squares on your graph paper)."
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5uvxdf | What part of the mammalian reproductive system is responsible for the perfect 50:50 chance of the fetus becoming either sex? | Biology | explainlikeimfive | {
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"Let's use humans as an example. Most of our cells have two complete sets of 23 chromosomes (46 in total). One of those in each set is a sex chromosome, that exists in X and Y versions. In females, both sex chromosomes are the X version, in males there is one X and one Y. Sperm and egg cells, however, have only a single set of 23 chromosomes. Each one is more or less randomly chosen from one or the other of the two complete sets we have. Since females have two X chromosomes, all egg cells contain an X chromosome. But since males have an X and a Y chromosome, sperm cells have either an X or a Y, with a 50:50 mix. So when sperm and egg combine to give two complete sets of chromosomes again, if the sperm cell contains an X, the offspring will have two X's and will be female. If the sperm cell contains a Y, the offspring will have an X and a Y and will be male. tl'dr: sperm cells randomly get assigned an X or Y chromosome, and that ultimately determines the sex of the offspring.",
"Sperm and egg cells form through [meiosis.]( URL_0 ) Normal cell division (meitosis) duplicates the DNA in a cell, but meiosis splits it into two halves. In a female this results in all eggs having an X chromosome, but in males it results in exactly half the sperm having an X and the other half having a Y. When sperm combine with eggs, then, half of the resulting are male (XY) and the other half are female (XX).",
"No one has mentioned Fisher's Principle, which describes why the sex ratio of most species is approximately 1:1 between males and females. Suppose you have a situation where male births are less common than female births and, subsequently, there are fewer males than females in a population. This means a male in that population will have better mating prospects than a female because the male has are more mates to choose from. A male can, therefore, expect to have more offspring. That means if any set of parents in this population are genetically predisposed to produce more male than female offspring, they will then tend to have more of grandchildren born to them. Therefore, whatever male offspring favoring genes they have, will spread more quickly, and this leads to male births becoming more common in that population. As the 1:1 sex ratio is approached, whatever advantage associated with producing males dies away. The same process would occur if the situation was reversed for the sexes. Therefore the 1:1 ratio is the evolutionarily stable strategy. Edit: Changed \"less common\" to \"more common\" at the beginning so it made sense. Edit 2: Changed \"more males\" to \"fewer males\". I hope this makes sense now.",
"It isn't a perfect 50% chance. More like 51.5% chance of a male child (in industrialized countries- there are variations due to environmental factors). Other than that- these kind folks have given fine explanations for the close-to-50% chance.",
"The male testicles make the sperm that determine a babies sex. Because sperm is produced by splitting the chromosomes into 2 halves, x & y, there's an even split of male producing sperm and female producing. This even split is what should result in a 50:50 split. As others have said, that's not exactly what happens but pretty close. Regardless, testicles are responsible.",
"Is this thread \"explain to me like I'm 5\" or \"complicate the shit out of it\"?",
"As a male you have XY chromosomes and when sperm is made it basicly takes a chromosome and rips it in half making one X spermcell and one Y spermcell thus there is a 50/50split between them. It should be noted that the Y chromosome has less mass the spermcell is somewhat faster causing a 51,5/48,5 (with variations) split",
"There are two kinds of chromosomes: X and Y. If you have two X chromosomes (XX) you are female. If you have one of each (XY) you are male. During reproduction, the mother (XX) contributes an X, the father (XY) contributes either an X or a Y, at random. If you get a Y from your father, you're a dude. If you get an X, you're a chick. (This doesn't take into account special cases; this is the ELI5 version. Nor does it address gender, OP asked about sex.)",
"None of the answers so far are actually saying or even attempting to explain the seemingly random chromosomes supplied by the sperm cell and biologically why each sperm cell has so close to a 50:50 chance of holding either one. I know it's ELI5, but I'm fairly sure that the actual question hasn't been properly addressed yet.",
"Although the chance at conception is 50:50, the chance at birth is slightly skewed to more live male births. And yet, by the mid 20s, in most societies that do not practice selective gender based abortion, we are back to the ratio of 50:50 Is it that more males survive gestation? Not exactly. The egg is fertilized before it implants in the womb. Not all fertilized eggs implant, many 'cruise on by' and become ... nothing. So is it that more females cruise on by? Not exactly. There is a condition known as secondary infertility. When a couple who welcomed a healthy baby without difficulty, cannot seem to get pregnant again. Researchers noticed that this happened more often when that first healthy child had been male. This phenomenon, devastating as it us to the individual couples, keeps / kept the species balanced. I put the past tense in because if the societies practicing gender based abortions. So it seems that the human race prepares itself for the testosterone fueled 'loss' rate of fightin' and fast drivin' and bravado by having about 2% more male births with an equal loss rate by adulthood."
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5uvy2f | how do people with hemmoroids not constantly get e.coli infections? | Biology | explainlikeimfive | {
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"Physician here. Hemorrhoids are veins that have becomes swollen In the rectum. Occasionally they may bleed which leaves an open communication between the blood stream and the colon but they don't often get infected. Why? Think of it as a small weak fish (bacteria) trying to swim upstream against a fast current. It doesn't get anywhere right? That's the pressure behind the vein. Now imagine the same stream with a bunch predator fish swimming around eating the small fish. This is the immune system in and around the rectum. So we have a two protection systems against infection. The most common reason hemorrhoids become infected is when the blood supply to the hemorrhoid ceases (strangulated or thrombosed). So now there is a dam, river comes to a standstill and the predator fish can't get in so the little fish (bacteria) can go wherever he likes including right into the now dead tissue of the hemorrhoid and wreak havoc."
],
"score": [
1239
],
"text_urls": [
[]
]
} | [
"url"
]
| [
"url"
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|
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