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9523vi | How does a cell phone with no signal search for a cellular tower? Does it sweep across all cellular frequencies? | Technology | explainlikeimfive | {
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"When a cell phone doesn't have service, yes, it looks for a tower on all of the permissible frequencies for contacting the towers. Any tower it finds, it checks to see if the tower will accept the phone -- that is, if it will agree to send and receive traffic. There may well be multiple towers that will agree to this. Some will have stronger signals, some might be roaming, some might not be roaming. Generally, the cell phone will pick the strongest signal from a non-roaming tower; if there are no non-roaming signals, it will go with a roaming tower; and if there are no towers willing to accept the phone, you get the \"no service\" message. Note that \"no service\" and \"no signal\" are not always the same thing. There may be towers that are technically able to accept the phone, but don't have a contractual billing arrangement with your phone company. You'll still get a \"no service\", but you could still make emergency calls, since any tower that has the technical capacity to talk to your phone must always process emergency calls."
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954dxf | When someone goes missing, why can't the authorities use cellular data to determine who was around the victim at the time of the crime? | Technology | explainlikeimfive | {
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"For the same reason they can't just start searching random people's homes to find them: individuals have rights and there are checks and balances in place to prevent the police from violating those. If the police wants to check cellphone data, they can. But they need a warrant. To get that warrant, they will need to show a good reason for needing it. Because else you are just collecting a lot of data on innocent people on the off chance it might be useful.",
"They do. Phone companies usually have at least the tower that your phone is talking to, so they can say what phones were in the area at the time. But unless they're trying to tie a suspect to a situation it doesn't really help to know what people's phones were in a general area, especially if you aren't sure that a crime was committed",
"The way cell towers work is that any devices in a particular radius connect to that tower . So if victim was connected to tower A and standing right next to it but there was also , say, 2500 other people connected to the tower but that included residents of nearby houses etc . So it’s very difficult to triangulate location based off cell towers . To get the gps location in most cases you need a warrant of some sort and you can get a warrant on 2500 people that’s what would be termed mass surveillance by many"
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955hlp | Why is streaming a movie/show for no profit okay but downloading a movie/show isn't? | Technology | explainlikeimfive | {
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"It's not, necessarily. If the streamer does not have permission, it's still piracy. The question is not stream versus download; it's whether or not the copyright holder has given permission.",
"It's patently illegal, but in a civil sense, not a criminal one. The owners of the content being streamed would have to hire tech specialists to find the kid's name and address, then lawyers to start the lawsuit. That's already going to cost the company $20k. All to sue a kid worth maybe $500, so even if you win you've just wasted a ton of cash to \"protect your rights\". Also, legal arguments can be made that the streamer was just watching a movie with friends as if they were at home. It will still lose, but make the company look like huge dicks and up the cost to sue. Now, once you've started making money on it, you're competition and probably financially worth suing. The streamer is also patently breaking the law and has no defense. Take his $500 and the $5 per person he charged to watch his stream."
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957hax | How does closed caption works? | Technology | explainlikeimfive | {
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"A person listens to the soundtrack and types in what they're saying. Or it comes from the show's scriptwriter, which is why it's sometimes different than what's actually said."
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95bhy5 | How are bubbly chocolate bars (such as Wispa or Aero) made? | Technology | explainlikeimfive | {
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"The molten chocolate is foamed up with the introduction of air, and is then formed into moulds in a reduced air pressure environment, so the internal bubbles maintain their structure as the thing cools. Then there's a final layer of normal chocolate coated over the top."
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95byym | How does my computer know when a program is unresponsive? | Technology | explainlikeimfive | {
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"Those programs have a GUI. When you do something with the mouse or keyboard, the operating system figures out which program is responsible for handling the input and puts so-called \"input events\" into a list for the program to handle. But the operating system also monitors these lists and when it notices that a program hasn't handled any of its input events for several seconds, it assumes that the program is stuck in some other part of the code. However, this only works for GUI programs. With a command line program, the OS has no way of telling whether a program is stuck or just working hard on something that takes a long time.",
"Suppose that Windows is a manager and a program is an employee that is supposed to regularly ask for new tasks to perform. If the program hasn't asked for a new task in a long time then Windows considers the program to be unresponsive. For more technical detail: URL_0",
"**Because it's not responding.** A lot of times we think of 'not responding' as being the same as 'frozen', 'locked up' or otherwise broken. This is not correct. Your operating system regularly asks all the running programs what they're up to, or asks them what they should do when you click on something. If they don't respond, the program gets marked as 'not responding'. It could be that the program is locked up or otherwise 'dead'. It could also just be busy doing normal work.\\* For instance, if you use programs that do complex math that takes a long time to complete it's common to see them stop responding while they concentrate on the math only to come back to life when they've completed the task. \\*A well-designed program will not stop responding even if it's very busy. However, many programs have certain features that are less-well-designed. Usually these are features that were not expected to take long when the program was designed. A common example is opening a file that is much larger than the programmer ever expected.",
"Your computer knows the process is unresponsive because the process literally isn't responding when the OS is sending it's messages. The OS: \"Hey, Chrome.exe, are you there?\" Chrome: \"....\" OS: \"Chrome.exe. Your input buffer has not been read for a while. Are you there?\" Chrome: \"....\" OS: \"Chrome.exe is not responding to the messages sent to it, ask the user if it wants to close the process.\""
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95ccz5 | when a person dies, how is their Wikipedia page updated to past tense in a very short time ? | Is there some script / bot / button that does this automatically? or is each sentence edited to past tense manually? | Technology | explainlikeimfive | {
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"Anyone can edit a wikipedia page. There are plenty of people who want to be the first to make an edit when an important event, such as a person's death happens. In other words, there are people just waiting for something like that to happen so they can make an edit.",
"Wikipedia has a very active community composed of probably thousands of writers. Everyone can find out news quickly with social media and editors can quickly edit"
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95e1p3 | Why do some posts say that it has one comment, but when you view the comments section there are no comments? | Technology | explainlikeimfive | {
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"Ghosts of Reddit. Aka shadowbanned accounts. It's a ban typically used on spammers. They can still comment/submit normally and such, but to the rest of Reddit they are invisible, and their votes don't count."
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95gdzt | What is a video game "engine," (e.g. unreal engine) and what differentiates one from another? | Technology | explainlikeimfive | {
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"A video game engine is the code that defines the rules that all the objects in a video game follow; in some cases, they are very very generalized in the sorts of rules that they have and define sort of meta-rules that a game developer can then use to make their own in-game rules (ie: what happens when a player collides with a wall? What happens when an enemy \"sees\" a player? what happens when a bullet from this gun hits an enemy? what happens when there is no ground underneath the player?). The game engine controls all of that. What differentiates one from another is, in short, the code. To illustrate this a bit more, let's compare a couple of fairly well-known games: Grand Theft Auto V and Super Mario Odyssey. Both of these are really good games, but they play and handle completely differently; the engine in GTA 5 has rules for things like switching between characters, how different guns behave (ie: does one pull of the trigger button allow for only one shot, or will there be rapid-fire?), how much health the player has, and how the AI interacts with the players and the world. Only the last two things I listed in there apply to Mario Odyssey. The operative bits of Mario Odyssey are things like what buttons you need to press for different jumps, the different world unlocks for different moon counts... Another key difference is that some engines (Unreal being a popular one) are made with the intent of selling the engine to other game developers (or in some cases, allowing the use of the engine freely, Unity is [in]famous for that) for use in other games, while some others are tailor-built for the game they're supporting (both GTA V and Mario Odyssey, IIRC, fall into this category). Still others might not be freely available, but may be used in several games a company makes (the engine from Fallout 3/New Vegas comes to mind, and a variant also powered Oblivion of memory serves).",
"So in the old days almost all games were buily from nothing using only programming languages sometimes very basic ones like Assembly. Examples include basically all NES games. This was ok because basic games didn't need to do that much. and the memory they had wad limited. As games became more complicated it took more and more time to program them. There were more things to keep track of. Often as new games were made elements of those games would be the same or similar to other games such as running jumping and shooting. Or for RPGs combat systems, item collection, overworld maps. Programmers saw this code be reused to make creating a new game much faster without building a game from scratch. Today game engines still do the same things and much more. they allow you to build games and you don't need to figure out the physics for your characters or the camera system or a system for switching to your cut scenes seamlessly. So most games today are built on preestablished engines such as Unreal. This allows companys to focus on the fun parts of the game such as actual gameplay, graphics, maps, and audio. It's like if you wanted to make a lego sculpture but need to produce your own leggos and then put them together. it's a lot easier if you can just buy a bucket of leggos and start building. Edit: What differentiates engines is what they are made to do. Unreal I believe is a generalist Engine. It can be used to make many kinds of games. Its like a sandbox with lots of buckets and skulpting tools and water and everything you need. Then there are specialized engines that might focus souly on physics or lighting or making classic RPGs. It's the same concept as above you are just building more or less of the game yourself for your own needs."
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95hfrs | What is the difference between SSDs and regular hard drives and what makes SSDs better? | Technology | explainlikeimfive | {
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"Hard disk drives have a little silver magnetic disk inside them that can be written to or read from with an electromagnet. This is the same principle behind floppy drives but much more accurate, resulting in higher data densities, or more stuff per area of disk. The problem with this nowadays is that spinning the disk to read all the bits of data takes time and magnetic storage isn't too reliable. Hard drives can and generally are reliable; there's one in my laptop that I'm using to type this. Solid state drives, meanwhile, have data stored on flash chips. This means you can store data much more reliably and much more densely. There's also no disk to spin so it's faster. Bonus fact: \"disk\" if it's magnetic, \"disc\" if it's optical. A DVD is read with a laser so it's a disc, a floppy disk is read with an electromagnet so it's a disk.",
"Hard drives have physical, spinning magnetic disks and a physical head. So the disks actually spin and the head actually moves to read data. SSDs, on the other hand, are based on nand flash. There are no moving parts. Just electrons hold the state. That's going to make SSDs (much) faster, more resilient (unlike with HDDs, dropping one or magnets won't do anything), lighter, and more power efficient.",
"This is a loaded question because SSDs are not \"better\" across the board from regular HDDs. They are different technology with different benefits and detriments. A HDD stores data on platters which spin past read heads hovering a tiny distance above them. Because of the physical constraints of moving the read head across the platters they can only read from one place at a time (although multiple platters and heads can be within a single drive) and this introduces slight delays as the head must move into position to read specific data. Their tight tolerances and moving parts also mean that they are particularly vulnerable to external shock which can damage or destroy their internal workings. That said they are relatively inexpensive, have large capacities, and are reliable for long periods of time. An SSD stores data within tiny capacitors embedded in solid chips. They have no moving parts which means that reading any arbitrary piece of data is equally quick, introducing no delay. The lack of moving parts also makes them extremely shock resistant, and also consume less power as they do not need to spin physical disks or move read heads around. However they are relatively more expensive, have lower capacities, and over time their data storage ability degrades and will fail much faster than an HDD. Sophisticated load-balancing algorithms attempt to spread out this wear evenly but overall an SSD will wear out significantly faster than an HDD. SSDs are most appropriate for use in mobile devices such as phones and laptops, while HDDs are best for fixed applications such as server farms or desktop computers. Neither is better or worse across the board."
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95hk6f | Why do printers use cyan instead of blue? | Technology | explainlikeimfive | {
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"The primary colors of light are red, green, and blue. Pigments though absorb light and reflect portions of the spectrum so their primary colors are cyan, magenta, and yellow. Printers have to use cyan because they aren't printing light, they are printing a substance which absorbs light.",
"Pixels on a screen work with RGB (Red Green Blue) because they emit light and as such can create the entire colour spectrum by changing the intensity of one single colour. This is sort of how a printer works except since it's printed the colours don't emit light but **reflect** light and to create a colour by reflecting you need the colour to absorb all wavelengths except the colour you're trying to get. This is why printers work with CMYK (Cyan Magenta Yellow Black\\*)It is with these specific colours in the intensity collaboration we can achieve the full colour spectrum on paper. *\\*The K stands for blacK because they didn't want to confuse people by making them think it stood for Blue or Brown*",
"The actual color spectrum goes from ~350 nm to ~750 nm. However, the way you see is via 'cones' that have their maximum gain at center wavelengths ~475, ~550, ~700 (blue, green, red). So if I shine a light with a wavelength of ~515, you're actually seeing a dim blue light at the same time you see a dim green light - and you interpolate that it's somewhere between blue and green. Interestingly enough, you'd see the exact same color if I shone two dim lights - one @ 475 nm and the other at @ 550 nm. Your eye can't tell the difference between the two colors and the one color in the center. As a result, it makes sense when projecting light to just match the emitters to our eyes. Because you're 'faking' the intermediary colors anyway, you might as well fake them with the same parameters as the eyes that will perceive them. However, when you're dealing with reflective light, you can't really do this all that effectively. If you tried to 'paint' individual pixels to mimic the RGB approach of monitors, you end up with something like: URL_0 Instead, what we do is mix colors togethers and generate the true colors - and then let our eyes interpret them as they do any true color. When you're mixing colors togethers, it's far easier to work with roughly equal sized frequency bands in the color spectrum rather than trying to match the lopsided nature of human visual perception. Note: This also means that what appears true-to-life to us on our monitors will often appear bizarre to other animals with different color perception.",
"You're probably remembering red, blue, and yellow as the three primary colors. I was taught that in elementary school, and it's good enough for 4th grade art class, but cyan, magenta and yellow work better. There are simply some tones RBY mixing can't come up with compared to CMY and black (Key, K, hence CMYK).",
"If printers use cyan ink, they can print blue by mixing cyan and magenta. If printers use blue ink, they can't print cyan. URL_0",
"Because cyan is a primary color. There are 3 (subtractive -or painting) primary colors: cyan, yellow and magenta. So, for printing where you need to be able to mix inks to produce as many shades as possible, using primary color inks gets you the best range possible with the fewest separate inks. Because cyan is bluish, and magenta is reddish, when teaching young children, the primary colors, are often called blue, yellow and red to keep the names simple.",
"**First a bit about how your eyes work:** Your eyes have three types of cones that are **most** sensitive to red, green, and blue light (color of light for each). However, it's not exact, so your red cones will activate for orange light and yellow light, but less so than for red light. All other colors are you see actually just an activated mix of those cones. Yellow light activates both the red cones and the green cones, which is why a TV can make you see yellow by showing you red and green pixels. Your eyes sense that something is activating the red and green cones and interpret it as yellow, because the signals to your brain for the mix of red and green are identical to the signals for yellow. The graph on this Wikipedia page - [Cone cell]( URL_0 ) \\- that shows the ranges for each type of cone might help if you are confused about the overlap. There are three colors that you can see that are straightforward mix of cone combinations: *RED + GREEN = YELLOW* *RED + BLUE = MAGENTA* *BLUE + GREEN = CYAN* And then there is this fun fact: *RED + GREEN + BLUE = WHITE* You can see other colors by changing up the proportions, but every color you can see comes down to some mixture of these three cones activating. **Now, a bit about how colors in nature work** White light is all of the colors (that humans can see, anyway) mixed together. When that light hits an object, like your bluejeans, some of that light is absorbed and some bounces back at you. The wavelengths that get absorbed **don't** go to your eyes, so if you see blue that means that red and green are getting absorbed and blue is bouncing back. *See BLUE > > RED + GREEN absorbed* *See RED > > BLUE + GREEN absorbed* *See GREEN > > RED + BLUE absorbed* *See BLACK > > RED + BLUE + GREEN absorbed* But what does that mean if you see cyan? We know that if you see cyan, you are seeing blue and green light, which means that red light is getting absorbed and blue and green are bouncing back. *See CYAN > > RED absorbed* *See MAGENTA > > GREEN absorbed* *See YELLOW > > BLUE absorbed* **So let's say you have some paint or some ink** If you mix yellow and blue paint to make green, you will get pain that absorbs some red and some green and some blue, no matter what proportions you use. So it will be a dark color because while some green light can bounce back, some is also getting absorbed. Your green will look like you mixed some black paint into it, because that blue pain will absorb some green. Now what happens if you mix magenta and yellow paint? You are mixing green-absorbing paint with blue-absorbing paint and end up with red paint, and I do mean true red, the color that gets your red cones all excited. If you try it yourself with actual paint it will seem like motherfucking witchcraft, but that's eyes for ya. *MAGENTA + CYAN = \"TRUE\" BLUE* *MAGENTA + YELLOW = \"TRUE\" RED* *CYAN + YELLOW = \"TRUE\" GREEN (aha! that's how to do it!)* **So the reason why CMYK inks are used is so you can get ALL the colors.**"
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95l344 | How can your eyes focus on the information on "smart glasses" that is so close to your eyes? | Technology | explainlikeimfive | {
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"Previous answers are missing something crucial: **a system of lenses** is used to refocus the light rays from the screen so that they appear to come from much further away. The same system is used for \"red dot sights\" on guns, heads-up displays in cars and airplanes, etc. To give more detail: light rays from an object spread out in a wide fan. The lens and cornea of your eye must bend those light rays so they converge on a single point at the back of your eye. Your eye only has so much \"ray bending power\", so that if the object is too close to your eye, the light will fan out too widely, your eye can't bend it to a point, and it ends up as a fuzzy spot. Adding extra lenses makes the light rays fan out less, so your eye can bring them to a focus."
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95nijw | It once took me 6 hours to create a single 3D screw. How do video game designers create thousands of intricate worlds, objects, and animations so quickly? | Technology | explainlikeimfive | {
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"They work in teams, not alone, and they have lots of practice behind them. Your screw may have take 6 hours, and is no small feat, but if you're making tons and tons of these sorts of objects you do get creation of them with practice.",
"Lots of practice for starters. You say it took you 6 hours? How long do you think it would take you to do the next one? Then the next one? Every time something doesn’t go quite right, you learn something and get better and more efficient. They also have access to whatever programs they need to make it happen, and super nice computers to handle it all. They’re also a team of people - depending upon the company it could be hundreds of people, whereas you’re just you.",
"Part of it is practice; they know what they want to build/design/create, and have used the software to do it for a while. They know all the hotkeys and keyboard shortcuts to do stuff very quickly. Another part of it is the relative amount of detail. Your 3D screw probably had individual threads in the polygons, but for a video game that amount of detail wouldn't really be necessary - they could make a simple 3D screw out of a cylinder with a few easy tweaks, and work with a texture artist (if they aren't doing the texture themselves) to put threads on it - bonus points for normal maps to give the threads depth on an otherwise flat surface. With creating worlds/objects, they'll often design & build a *ton* of similar assets, and plop them somewhere in the game world. There's a reason why Skyrim has a lot of the \"same\" look in places - they're not going to design a ton of different wheel barrows when one or two \"functional\" ones and a few different \"ruined\" ones to use when building an area. Animations are a bit different but come down to much of the same idea; practice & using the same animation for multiple instances. Looking at Skyrim again, they only had to make a few \"sword swing\" animations that pretty much every human enemy uses when swinging a sword - instead of having the big muscular humans swing differently than the scrawny ones, or a warrior swinging differently than an archer.",
"Most assets in video games or 3D movies will come from libraries rather than being custom made, e.g URL_0",
"Were you making a screw for an engineering class? Engineering designs require more detail and specificity than most game objects.",
"Massive teams, sometimes millions of dollars, and most of the complex things are just made out of other premade things",
"A lot of practice and just knowing how to use your tools, I'm like you, I've made screws in CAD programs and 6hours is about what it took me. But there are two issues, one, that's CAD, not CGI i'm entering sizes and dimensions and angles. I also had a friend who had an art degree and had formal training with Maya, so at least a few years experience with it. And I still remember what he did when we tested a new video card. It took him about 3 minutes to make a make a face, he then tested out animation by making stick figure and over the course of 5 minutes animated it walking. Then he simulated a thousand dropping and flying and bouncing, again, something like 5 minutes to do. The fact is when you know how to use tools like Maya, making a model is about as fast as painting. That is you can make a smiley face in 30 seconds, but a finished product you sell might be a few days work. Video game developers have multiple people with skills doing this, and also heavily use copy/pasting. So they might spend 2 weeks 30 models of trees, and the maps can have 1 million trees, but it's just a script that took a day to write that placed the trees in reasonable locations using the 30 models."
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95os40 | why phones (and othet stuff) havr an expandable memory *up to" a certain amount. | I see it all the time, a dash cam that can accept an SD card up to 32GB or a a new phone that can go up to 2 terabytes. Why can't I use the full 2 terabyte card on said dashcam? | Technology | explainlikeimfive | {
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"SD cards may look the same, but actually use different \"languages\" to enable higher speeds and larger capacities. The dashcam is compatible with SDHC cards (SD high capacity) which go up to 32GB. Larger cards are SDXC (SD eXtended capacity) which again, is the same physical size/appearance but technically a different type of memory card. The phone is either newer or more expensive, which allowed SDXC capability to be included in it.",
"Because the reader chip that dashcam mfgr installed only supports the old standard that didn't have super high capacity. The new chips are most expensive than old chips from the sd reader chip maker. The dash cam maker doesn't make the chips, they buy them from the sd reader chip maker"
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95pf6p | The difference between analog and digital recordings | Technology | explainlikeimfive | {
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"Sound is a wave. Analog recorders use a machine that vibrates along with this sound wave, and the resulting mechanical vibration is sthen written over realtime to some sort of recording media. Digital recording uses math to represent the sound wave, with a digital signal processor taking the analog audio input in chunks and converting it to something that can be represented mathematically. The standard method for doing this in a general purpose computer involves using an audio signal to drive electrical pulses; but instead of the pulse being stored as one long stream, it is synced against an internal clock and stored as a bunch of chunks of data. A 96Khz recording will have synced the stream of audio to a clock ticking at 96,000 ticks per second, with the discrete data being stored for what the sound was doing during each of those ticks. Audio compression algorithms can then take this sampled data and build a realistic waveform out of it by averaging the wave across multiple samples to correct for errors and produce a wave that looks realistic.",
"Sound is the vibration of air, but after you put it into a microphone (or before you play it back through a speaker) it can be represented as a changing electrical signal. This can be then be recorded with a changing magnetic field (on a cassette tape) or a wiggly groove (on a record). Both those things vibrate/change the same way the air did when the sound was produced. You can also record a *number* to represent the movement of the air (or electrical field) at any instant. That's the basis of a digital recording. Now, sound can change up to 20,000 times a second (the human ear can hear a frequency up to 20,000 hz). If you want to represent a back and forth vibration happening that often, you need to check this *twice* as often so you can catch both the high and low parts of the cycle. As a result, 44khz or 44,000 samples per second is common. I'm not sure I'd describe this as \"bits of sound\", each individual sample has no meaning on its own-- unlike one frame of video which is its own picture even if you don't see the ones before/after it. But there are a certain number of samples per second and the sound is not \"checked\" between those times."
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95pjkl | How do cameras focus? How do they know what they're pointing at is in focus? | Technology | explainlikeimfive | {
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"It depends on the camera, but there are two main methods. Cheap or small cameras, like your cell phone use the contrast. Basically they take a picture (from the preview), and pick a strip of pixels. Then they subtract each pixel in the strip from it's neighbor to get the difference, square each difference, and add those numbers up. That's one method for getting the contrast of the strip, there are others. Then it just focuses back and forth until it finds the focus setting that gets the highest contrast number (basically the least blurry, since that would mean it's in focus). Higher end cameras use a mirror behind the lens to split a bit of the light away to a second lens for the autofocus sensors. The lenses are focused on different parts of the mirror, and thus different parts of the lens, but also such that when in focus it is the same spot on the image. Since an in focus image is when the all the light through the lens from a point hits the same point on the film, the camera can use the different spots to determine not only if they are hitting the same spot, but how far off they are and in what direction they are off. The benefit of this is these cameras don't need to search for an in focus spot, they can see an out of focus spot and determine how the lens needs to be adjusted to be in focus which means focusing can be much faster. The downside is you can only focus on spots that are already setup with a sensor."
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95qvdt | How do police recover deleted data from phones and laptops? | Just asking for a friend... | Technology | explainlikeimfive | {
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"Bytes on disk aren't erased, just marked free for allocation. It can also be possible to retrieve overwrited data. This is why sanitizing disk usually apply seven pass with 0-1 and random",
"Same way IT dudes do. When a hard drive deletes a file, all it does is remove all references in the file system to where the file starts. If you somehow knew where that file was physically stored, you can go read all the bytes of 1's and 0's. Software programs that do this probably go read all the physical locations of the hard drive, compare that with a map of all files that are known to the filesystem and any file it sees that the file system doesn't, well thats a deleted file. Now, since the filesystem has marked those locations as \"empty\", the next time it needs to write a file somewhere it could overwrite the bytes of the old file. Now the old file is well and tryly gone (actually not, but now it falls into a few expert skils to recover; like NSA level or cleanroom lots of science shit); but usually the police don't need to go beyond that first level. This is why \"wipe\" programs exist. They go and overwrite all the 'empty\" locations on your hard drive with random bytes several times."
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95spgt | How do those chords on roads that I assume take data on traffic work? | How does this data get collected and what’s the data used for? How come there are sometimes two? EDIT: cord/tubes not chords. (I’m a musician, whoops). | Technology | explainlikeimfive | {
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"I set these down myself for my city! They are hollow tubes that allow air to be pushed down to a box at the end of the tube when cars drive over them! The tubes can be used simply to count cars or as mentioned by others, to calculate speed at which cars travel over them (when using 2 tubes at a specific distance apart). A traffic engineer would use these data points to run a simulation to see if the road needs widening, a turn lane added, or many other possibilities. It also helps correcting estimations for traffic flows as cities grow. Edit: The tubes are simply screwed into the concrete or asphalt using wire fasteners and a pilot hole. Sometimes they get ripped out/apart D:",
"You assumed correctly. Those strips are just traffic counters. They count how many times something big smushes them. If you have two of them, you can also measure speed by comparing the time between similarly timed smushes. You can use the information generated for anything that the information might be useful for. It could be upcoming construction, or zoning, or funding, or whatever.",
"Traffic Engineer here. The tube (or Automated Traffic Recorders - ATR) data is used to count how traffic volumes change through different times of day and days of week. That knowledge is useful to show when rush hours start/end and what signal timing plan to use throughout the day.",
"Sometimes they are set up simply to measure the amount of traffic that travels that road so they can decide if its worth it to do repairs",
"They count how much traffic is on a given road. Each time you drive over it, that's recorded. A scientist for the city/county then takes this data and determines where the road budget will ha e the greatest effect. Typically this means comparing the worst road conditions to amount of traffic. But for like, all roads in the area. Fun fact, I grew up in a really out of the way place, there were only two roads that got you to my neighborhood. So whenever one of those roads had one of those sensors the neighbors made a big deal about it and everyone would go do a few laps to artificially pump up our \"traffic\" and therefore make it more likely that our roads would be improved. I think this is a somewhat common practice.",
"Can someone ELI5 the question? I don't know what OP is talking about.",
"I’m seeing all these replies from workers that do this or people who actually know on the subject.. and here at 20 I learned that it’s not to prevent hydroplaning when it rains like my sister said",
"when there are two, its to see average speed to set a proper speed limit. floor it if youre about to go over a double. for everyones sake. they basically take an average (without outliers) and round to the nearest standard for the governing body (some like 10s some like numbers ending with 5) [source]( URL_0 ) ps, if theres already a speed limit, this still applies. surveying is used to see if the speed limit should be changed.",
"I'm late but I put these out for my city. The amount of people who ask if it can tell us the license plate of speeding cars is amazing. Yeah absolutely dont speed. We get your VIN and cars make and model too from the rubber tubes lol The worst is when people purposely cut them. I imagine because they sped and want to get rid of the evidence? There were clear axe Mark's in the road a month ago. Silly."
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95svvo | Why "size" and "size on disk" is different? | While looking at a size of folder on my PC, I see it very often. Is it because of some overhead used by my SSD that takes more size than the files does themselves? Thanks everyone. Got my answer! | Technology | explainlikeimfive | {
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"Your teacher tells you to write a four-page essay. So you write three full pages plus two sentences on the last page. Your essay is four pages long! Well it's not really four pages, it's closer to three pages, but it takes four pages to contain those 3.04 pages worth of text. The \"size\" of your essay is 3.04 pages. But the \"size on paper\" is 4 pages. The significance of reporting that it is 4 pages long \"on paper\" is that you only have 100 sheets of writing paper. That means you can write only 96 more pages of text, not 96.96.",
"The size of a file and how much space it takes to store it are fundamentally two separate (but related) concepts. Consider if I made a text document that stores the sentence \"The quick brown fox jumped over the lazy dog.\" That's 45 characters by my count. If we use one byte per character then that would give us a file with a size of 45 bytes. However, your computer doesn't work with files that small. Typically the smallest file is 4 kb. The size on disk may be 4 kb for this file. Now consider if I made a text document that consists of the letter L fourteen million times. The size of this file is 14 million bytes. It does not take fourteen million bytes to store that data, though: the sentence \"the letter L fourteen million times\" fully describes the file. Some file systems give the option to let the operating system compress files on disk to save space at the expense of speed. In this case the size of the file would be about 14 MB while the size on disk may only be a few kb. The operating system is telling you both file size and size on disk because it doesn't know what you care about: how big the file is, or how it's contributing to your disk being full.",
"Picture a cabinet with a bunch of drawers. Each drawer can hold at most 100 legos. But any given drawer isn’t allowed to hold more than one LEGO set. So even if a particular set of legos is small and only has twenty legos, that set will take up 100 legos worth of space. The cabinet is like the disk and the sets are like files. Basically each file ends up taking up more space than it actually needs on the disk because the drawers (sectors) aren’t exactly the same size as the file. And just to head off a logical next question, making the drawers small enough that they each only hold one LEGO is very inefficient when it comes to finding or storing the legos. So there is a balance between the drawer size where speed of access is weighed against wasting space.",
"In olden days, they didn’t used to show “size on disk” statistics. This caused perplexing problems with users, and occasionally developers when, say, a 20GB hard drive reported 4GB free but would report out of storage space when trying to create a new file, because in actuality a ton of small files had filled up all the 4K storage blocks. Windows 95/NT started showing both statistics in disk property windows, and confusion was dramatically reduced.",
"Pretty sure it has something to do with the smallest amount that can be allocated for a file/folder. When allocating space for some data, a computer can't really allocate space for exactly 3.14kb of data, it can only allocate in blocks of 4kb. (for example) So while the file is 3.14kb, the space dedicated to storing that data will be 4kb, because that's the smallest size the computer can allocate for it. Something like that. Space for data is allocated in nice even numbers, so for odd-numbered data sizes, the amount of space allocated will be larger than the actual amount of data, and thus, you see different numbers for \"size\" and \"size on disk\". The \"size\" is the actual size of the data, whereas the \"size on disk\" is the size of the space allocated for that data."
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95x7k1 | Why are US voting machines is so vulnerable? | I read an article that voting systems for up to 39 states were infiltrated by hackers. Why are these pivotal systems so vulnerable? | Technology | explainlikeimfive | {
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"Electronic voting is the equivalent of walking into a voting booth and finding a guy there, and having to tell him your vote. He promises to keep it secret, and promises to count your vote with all the others, and promises to tell the guy at the central count accurate figures. You just have to trust that he knows what he's doing, wont make mistakes and hasn't been bribed or threatened to lie about the results. And you also have to trust the guy he reports to, and so on up the chain. Paper ballots can also be messed with, but its much more difficult to manipulate hundred of thousands of physical ballots than it is to change a few ones and zeros on a network. The voting machine companies assure you that their systems are audited, that their networks are secure, that the machines are tamper proof - but you have to trust them just as much as you would have to trust some guy in a booth",
"They're made by the lowest bidder. The lowest bidder then turned around and hired the cheapest programmers he could find. Those programmes did the bare minimum to not get fired.",
"Doesn't mean they are more vulnerable than any other electronic. They are just more desired targets, drawing in more hackers, more skill. Although there's the reasonable thought that these voting machines might be hard to keep up-to-date with current cybercrime and their methods.",
"It is very, very difficult to get software right, unless you paid a lot of money for it (and even then you might not get it right) Relevant (and timely) XKCD: URL_0"
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95yq8e | How are music videos with multiple settings put together to make all the singing sync up together, or are they lip synced? | Technology | explainlikeimfive | {
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"They record the song first and when they're filming the video they play the song in the background so the artists can lipsync over it, they'll do this various different times in different scenes and cut them all together for the final edit",
"Also sometimes they’ll (try to) lip sync at double speed while the camera is shot at slow motion for a cool motion effect."
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960kcq | How do chip makers like Intel or Amd make processors that are significantly more powerful than its predecessor year after year? | Technology | explainlikeimfive | {
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"While they have increased the raw speed, these days mostly they make the chips *bigger* so they can do more things at the same time. For example, while one part of the processor adds two numbers, another part is concurrently reading in the next numbers."
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96139b | Why do file transfer rates fluctuate when transferring data from a USB storage device? | I get why downloads over the internet fluctuate due to the nature of internet connections, but why does a file transfer from a flash memory USB drive to a flash memory solid state drive fluctuate from second to second? | Technology | explainlikeimfive | {
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"# Simple Explanation Imagine you have two libraries with containing a different set of books and layout. In our analogy a book will be a file, and different books will have different number of pages which is the file size. If you want to copy a set of books from the first library to second, you could basically do the following in sequence for each book in your list. 1. Find the book in the source library (1 minute). 2. Make a copy of it (100 pages / minute). 3. Store the book in the destination library and update the index cards (2 minutes). Depending on the size and number of books the total time to copy can vary drastically, the first example is for a reference 100 pages, and the final three show different times for 1000 pages of copying. |Books|Time To Find|Time To Copy|Time To Store|Total Time| |:-|:-|:-|:-|:-| |one 100 page book|1 minute|1 minute|2 minutes|4 minutes| |one 1,000 page book |1 minute|10 minutes|2 minutes|13 minutes| |two 500 page books|2 minutes|10 minutes|4 minutes|16 minutes| |ten 100 page books|10 minutes|10 minutes|20 minutes|40 minutes| We can measure our progress using two different rates, pages per minute and books per minute (bytes per minute and files per minute), that would give the following data |Books|Pages Per Minute (ppm)|Books Per Minute| |:-|:-|:-| |one 100 page book|100 pages / 4 minutes = 25|1 book / 4 minutes = 0.25| |one 1,000 page book|1000 pages / 13 minutes = \\~77|1 book / 13 minutes = 0.08| |two 500 page books|1000 pages / 16 minutes = \\~63|2 books / 16 minutes = 0.13| |ten 100 page books|1000 pages / 40 minutes = 25|10 books / 40 minutes = 0.25| Now if you give a list of books that vary in size then as the copying proceeds, how fast it appears to be going changes. If I'm copying a 100 page book and a 1000 page book, it looks like it's going 25 ppm for the first 4 minutes and then jumps up to 77 ppm for the next 12. # Additional Complications On top of all this both hardware and software designers are driven by the desire to make things faster, so they place various optimizations in various spots to try and speed it up. Some examples with the above analogy are: * If the set of books you are copying are all next to each other on a shelf maybe you grab two books instead of 1, even if you aren't sure you need it. If you need that book then that saved you a minute, if you don't it doesn't matter you just get the next one in your list. * Another optimization might be that instead of actually storing the book in the destination library, you give it to someone else who does it if they are free. So if I try and copy two-50 page books, the first book takes simply 1.5 minutes (1 minute to retrieve, 0.5 minutes to copy, and then you give it to that person in 0 seconds). The second book (which is the same 50 pages ) takes 2 minutes (1 minute to retrieve, 0.5 minutes to copy and then waiting 30 seconds for the person to free up). This means that the ppm is 33 ppm for 1.5 minutes, and then it drops to 25 ppm for the next two. All of these make predicting how long it will actually take very difficult, because your computer doesn't actually know how long it will take, the estimates you see are just guesses and [they are often notoriously bad guesses.]( URL_0 ) # Summary So your computer doesn't copy \"byte by byte\", it goes through a process of for each file finding where the data is, and then copying/saving it. Each of these takes time and only part of this time of this depends on the actual data, the rest depends on the number of files. Indeed there are ways of making copies of USB drives \"byte by byte\" which you can do when backing up, they are faster but then all the data is smooshed together and you need to sort it out later for it to be useful.",
"There's a lot of reasons. One of them will be the sizes of different files. The thinking involved to copy one file takes a moment to process. If you have many tiny files then it will slow things down."
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96190k | What is Overclocking and how/why is it used? | Technology | explainlikeimfive | {
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"Running PC hardware at higher speed than it was rated for. Used to get more performance out of your hardware and also just for epeen/bragging rights. It's possible because you can't make exact copies of hardware and so sometimes they will be able to run at higher speeds etc. Think of it as a car engine, when you buy the car it has a certain horsepower/MPG etc, but if you change parts and mess with settings you can get more power. The manufacturers only guarrenties it will run reliable at the stock specs though.",
"I’m not likely the best person to answer this as I don’t have the scientific knowledge behind it but I did build PC’s for a few years back in 98-2002. The gist of it is that the processors have a certain tolerance built in that says it will work reliably up to a certain point in a given condition. Overclocking allows a processor to be pushed hard, allowing more speed overall, albeit with an understanding that it could be harmful to the equipment. The true ELI5 - make things go faster but may break them in the process.",
"TLDR: Forcing your CPU to run at a faster speed than it's rated for to get better performance at a lower price. Overclocking is possible because of the nature of how CPU's are designed, and flaws that occur in their manufacture. Take a given processor, let's make one up and call it the Intel Peregrine Processor for the sake of argument. So you make 24 of these Peregrine's on a single sheet of silicon. However it is basically impossible to make each chip exactly the same. The nature of the process is such that you can't make each chip perfect, the sizes you are dealing with are just too small. So once you've made the 24 chips you test them for stability. 1/24 is so flawed that it's useless and you dispose of it 12/24 of the chips are decent, but when you run them faster than 1ghz they start to show faults. They are only stable at speed up to 1ghz. So we'll lock them at 900mhz so that this is the fastest speed you can get from them. 5/24 of the chips are stable up to 1.2Ghz 5/24 are good to 1.4ghz and only 1 of the batch is good up to 1.6ghz So Intel packages these chips as 900mhz, 1.2 ghz, 1.4ghz, and 1.6ghz variants of the same chip, even though they are functionally the same. Since people know more performance is better, they price these chips accordingly based on how many they make on average and how fast they are. Now this is where overclocking comes in. Since the 900mhz Peregrine is functionally the same chip as the 1.6ghz, it's possible to overclock it or make it run faster than it's rated. You bypass the chips lockout and tell it to run at a faster speed. The catch is the chip will now run hotter and start generating faults. But many of these can be ironed out by better cooling. The chip will also wear out faster. So you can in theory buy a cheap processor, get a better heatsink and fan, and run it at a faster speed. There's a lot more to it than that, but that's the basics."
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9643vy | Why is SSH more secure for accessing network devices than Telnet if you can set password authentication on both? | Technology | explainlikeimfive | {
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"In SSH the network traffic is encrypted, so other users/devices between you and the server can't see what you're sending & receiving. In telnet all the traffic is sent in clear text, so any man in the middle can see and change what is being exchanged.",
"Things Telnet is: A virtual terminal accessible over plaintext TCP/IP packets. Things SSH is: Telnet wrapped in authentication and transport layer encryption, with a dash of X terminal forwarding and a flexible proxy framework thrown in for good measure. So not only does SSH handle authentication securely, it also ensures that prying eyes can't view the content in transit AND ensures that third parties can't *modify* content in transit. You have no way of validating that nobody's messed with your telnet content without wrapping it in some sort of signing solution... which SSH is designed to do securely. Of course, SSH also includes SCP and SFTP, which handle file transfers. FTP, the file transfer equivalent of Telnet went a different route and just wrapped the entire protocol in TLS instead of creating a new bespoke protocol. Personally, I trust SSH more because the implementations are designed with security as the focus from end to end. Telnet over TLS with kerberos authentication would be as secure in theory, but the devil's in the implementation."
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966vi2 | How do procedurally generated video games work? How are players not constantly stuck in a situation where they can no longer progress due to the level generation? | Are procedurally generated levels given guidelines they must abide by? Ex. No platforms over this height, no jump distance further than x, etc. | Technology | explainlikeimfive | {
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"> Are procedurally generated levels given guidelines they must abide by yes. that's why it's called \"procedurally\" and not \"randomly\". the game has to follow a procedure that makes sure the result is a playable map. a simple example would be to allow it to make gaps in a path, but the gaps have to be < 1m wide and have > 1m of land between them so it doesnt create a too-wide gap by placing 2 right next to each other",
"Yes, Procedural means \"by procedure\", which is very different from \"randomly\". Tiles, voxels or whichever the single unit of map used is, it includes a set of rules for placement, orientation and such. I've been testing some very basic procedural generation algorithms in Unity. [Here you can see my shitty algorithm at work]( URL_0 )",
"In the context of video games, \"procedural generation\" doesn't imply 100% random level design; it only means that the levels are created by algorithms, instead of by hand. Most of these algorithms ensure that the game doesn't become unplayable due to bad luck. For instance, Spelunky's levels are procedurally generated, but must adhere to a strict ruleset to make sure that the levels are beatable (i.e. there has to be open space from the starting area to the exit, there can't be any falls that would cause you to take damage, etc). Other games, like The Binding of Isaac, have procedural level generation, but the individual elements that make up the level (the \"rooms\") are handmade by people."
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967271 | What is an API? | Technology | explainlikeimfive | {
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"Think of it like a wall plug. For each country, the wall plugs in that country have a pre-defined shape and will give a pre-defined electrical current. That means the manufacturers can create devices that will work with those wall plugs without having the specific plug in the specific house they're going to be connected to. API in software is relatively the same thing. It's a list of predefined procedures with inputs and outputs, eg. I could make 1 procedure require that you give it 1 number and the output would be wether or not that was a prime number. People make APIs so that other programmers have a documented and standardized way of working with a given software. Another example: a stock market API could have one procedure that takes in the name of the stock and gives back the current price for that stock. There is a way of presenting this information. My 2 examples above could be presented as: // IsPrime returns true of the given number is a prime number. IsPrime(int x) bool // GetStockPrice returns the current price of the given stock or -1 if the stock name is invalid. GetStockPrice(string symbol) float64 This is usually refered to as the API documentation and it means something to the programer, it's like a \"wall plug\" definition."
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968a62 | how do emergency vehicles turn traffic lights red so they can get through? | I work outside by a hospital and a few times a day I see ambulances and firetrucks go through the intersection by my work and they always turn all the traffic lights to red so they can get through faster. How do they do that? | Technology | explainlikeimfive | {
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"It’s called an OptiCon. Fire, ems and police use them, but not every emergency vehicle has them. The vehicle has to have a special light in its lightbar in order to activate the mechanism over the light to change it for their benefit. Source: am firefighter/EMT. That being said, I don’t know the absolute specifics behind it because all I need to know is if my truck has it lmao",
"At my old fire station we did have a big button in the garage that we pressed before leaving. This button signal switched all the red lights at the intersection in front of the fire station to red 10 seconds later so we could get out. Of course, this cable solution only works close to the fire station. Other red lights were influenced by a transponder we had on board that was recognized by detectors besides the road.",
"There are several systems in use for that. - A sensor reacts to the flashes of the lights on the emergency vehicle, and sets the entire intersection to red. Except the lanes the emergency vehicle are coming from. With some luck, the whole intersection will be cleared by the time they get there. Since the system is kind of old and can be fooled by flashing a light of any colour it - it reacts to the high beam of any car if you flash with the right interval - it's not widely used any more. - A computer constantly monitors a camera that overlooks the lanes. The normal use of the camera is to detect traffic patterns and make the intersection adapt to traffic, by letting a small computer constantly process the digital images. It can also often see the emergency vehicles, and the intersection will try to let it through. - Some cities incorporate public transit systems where bollards close lanes so that only buses can use them. And add lane enforcement to intersections so that only buses with a radio transmitter can request a green light when coming in that lane. It's often convenient to let emergency vehicles use those lanes too, which means that whatever type of radio signal the buses use to claim the lane, the emergency vehicles have the same means to do it. - It's also totally possible that the fire station has a radio controlled gate, and the second they open it, it automatically communicates with all the nearby intersections, that simultaneously claims a predetermined route for them so that they can always with some convenience and swiftness reach another intersection or a on-ramp without having to bother with other traffic more than necessary. This explains why the fire station is right next to the worst intersection in the entire city, has their own lane that runs straight across it, and it still seems to work alright.",
"Used to be strobe lights, and still may be that way for a lot of places. I think newer tech may use RFID chips."
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969xty | How exactly did humans across different cultures figure out the recipe for making bread? | Technology | explainlikeimfive | {
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"It's a fairly easy accidental discovery. If you leave flour in a bowl and it gets wet, and you ignore it for a week, it turns into bread dough. (You don't even need to add yeast; with enough time yeast from the air or from the original grain surface will grow.) Now you just need to cook it and you get bread.",
"People eat grains. People cut up grains into smaller bits and mix them with water to make them easier to eat. People heated their cut up wet grain bits to make it even easier to eat, and incidentally to kill parasites. One day someone left their wet cut up grains out and some fungus got into them. When they heated it, it got fluffy instead. People really liked fluffy heated cut up wet grain bits, so they did it again and again, and figured out how to do it better. It is a pretty natural progression that just about any culture with grains will eventually stumble upon."
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96clqp | How come in remote regions my phone will say I have good service (2-3 bars of LTE) but nothing will load? | Technology | explainlikeimfive | {
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"Because it's actually saying that you have 3 bars of phone call reception, which is a different type of signal than internet data. The tiny trickle of data you have is of type LTE. So it says what type of data signal you have, right next to the phone call signal strength. It never directly tells you your LTE strength."
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96dqkj | What is multiplexing? | Technology | explainlikeimfive | {
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"> What is multiplexing? Multiplexing is the concept of taking multiple connections and combining them into one connection. There are many types, such as TDM (Time-Division Multiplexing), WDM (Wavelength-Division Multiplexing), etc. There is also \"Inverse Multiplexing\" where you take a single connection and transport it over multiple connections (think bonded DS1s or DSL bonding, etc.) > What is a VLan and what does it do? A VLAN is a specific concept, with most implementations following the system defined under the IEEE 802.1Q standard(s), though other vendor-proprietary methods were developed. The concept is to allow a single physical device to support multiple, segregated LANs. As an example, you have a 10 port switch, the first 5 ports in \"LAN 1\" and the next 5 in \"LAN 2\". You can use VLANs to prevent the two LANs from being able to talk directly with each other on that switch. > What is trunkning? See above, trunking is the idea of having a multiplexed connection that can transport data for multiple LANs (with Ethernet this would be TDM). > What is a route? A route is a pointer/reference that advises a router or other IP enabled device on where to forward a packet. An example, a router receives a packet for \"[192.168.0.1]( URL_0 )\" and looks up the route and it says to send it out \"Port 1\". The router then forwards it there. It gets more complicated with hardware routing, but that's the basics of it. > Why are subnet masks different from IP addresses? An IP address is an actual targetable address on a device, a subnet mask is used to identify the scope of the IP network with regards to the number of IPs in a \"network\". While it can be stylized as \"x.x.x.x\" it can also be written via \"CIDR (Classless Inter-Domain Routing)\" notation which would be stylized as \"/xx\" (f.e. /30 or /24, etc.). > What is an IPS? Intrusion Prevention System. It is a feature of a network firewall that tries to monitor network traffic flow and functions in an effort to prevent exploitation of bugs or the attempt to exploit. Many times it will be used to hunt for abnormal traffic flows indicating someone might be trying to crash or hang an application or server. > What is an ACK? It'd be more appropriate to state \"What is \"ACK\"?\". I'm being pedantic, but in TCP an \"ACK\" is usually used to refer to an empty TCP segment that has the \"ACK\" flag set. However, the \"ACK\" flag can be set in normal packets containing data and doesn't have to be standalone. The \"ACK\" flag is used to signal that the TCP segment can be considered an acknowledgement to data sent by the remote side. This function is part of reliable TCP session handling and re-transmission of errored or missing data. Hope the answers help!"
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96faq4 | How can you tell where a cyber attack is coming from? | Technology | explainlikeimfive | {
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"A data package always has a recipient and an origin. The package contains information about who it's for, and where it's from. A sender address and a recipient address. And, since you know the address of the sender, it's kind of a good hint, don't you agree? Unfortunately, that is all that it is. A good hint. The stated sender can have nothing to do with the data, since the information can be spoofed. And even if the package comes from a specific computer, doesn't mean that you can automatically blame it's owner for the attack. His computer can be hijacked and controlled from someplace else. But that is a well known part of he game, and you will have to start over at that computer again and find out where it's controlled from. An attack often comes from several hijacked computers at the same time. If you look at all of them, you'll hopefully start seeing a pattern with where they are controlled from."
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96ihc8 | What causes CGI to look so markedly artificial? | I watched Black Panther and The Greatest Showman recently. The rhinos and elephants in each movie were shown only briefly, but they drew my eyes every time to their ridiculously unlifelike movements and textures. It’s 2018--In anime, movies, and TV, what is stoppling us from getting this perfect? | Technology | explainlikeimfive | {
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"Its mostly survivorship bias. You dont notice all the awesome super lifelike cgi, so you are left with just the stuff that doesn't look perfect. As for why every bit of CGI doesnt look perfect mainly comes down to CGI being super hard, and the human brain being super picky. Your brain takes in thousands of little details and will know if something is up even if you cant pinpoint it. Shadows not falling quite right, an object being slightly too reflective, An object not being reflective enough, Shadows looking perfect in a scene, but not moving properly in relation to the camera. All of this stuff can instantly give off a feeling of something being fake.",
"CGI of organic objects is difficult. The texture of the skin and hair is very detailed and difficult to get just right. Hair needs to be chaotic but not too chaotic, it needs to move just right. CGI skin generally ends up looking just a bit too shiny and movements aren't *perfect* You don't notice 99.9% of CGI used in movies. A CGI car looks dead on to you, a CGI person can be 99.999% accurate and your brain can spot the flaws because you have tens of thousands of years of human recognition circuits hardwired into your brain to allow you to spot the subtlest differences between people and within a person's expression.",
"Often, it's an effect called the \"Uncanny Valley\". Basically, when something looks kinda human, we tend to project human features onto it. When it's almost completly human, our brain stops telling us that, and starts asking *what's wrong with that person?* This makes it stand out, and is often unnerving. That's only for humans though. For living creatures, it's usually the lighting that's off. While it's pretty simple to calculate lighting for things like metal, soft surfaces are extremely complicated. We've gotten pretty good at approximating it, which is why fully CG Films and games can look amazing, but when you mix it with real life, it can sometimes stand out. Another thing which might affect it is animation. While we usually use mocap(motion capture) for humans, for animals it might be manually animated. If that's done wrong, it really shows.",
"Short answer: Money. Given enough time (and money) a lot of these effects could be made more realistic. But even huge Hollywood movies have budgets that they have to follow, and most of the time the budget is strained. Producer: \"We can spend 2 million on this one scene with all the animals, or we can spend $500,000 on it with less time for CG and we can save $1.5 M for the huge explosion scene at the end\". Ultimately, they are rushed, and push the CGI guys to the limit of their abilities. Somewhere along the way someone has to cut corners, and the stuff that isn't in the forefront ends up looking like crap. I think Hollywood producers don't care as much about how a film looks, since they see the public paying for tickets anyway, so why improve? Just my humble opinion I was a grip and green screen gaffer for many years, and \"We'll fix it in post\" was often heard on set. They would seem to just shoot anything and hope that the poor CGI guys can do something with it."
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96la63 | why some websites still check your date of birth when all you have to do to get past it is click a year to make yourself over 18? | Technology | explainlikeimfive | {
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"It allows them to legally claim that they took efforts to prevent a minor from obtaining the material, or to at least war them which is a major protection from lawsuit.",
"It is just a token gesture so they can't be criticized by soccer moms whose kids see something they don't like. Also maybe they can get a little demographic data, although terrible quality.",
"It's just to cover their asses from legal issues that might be lurking in the future. You are using their services by stating that you are of legal age so they are not liable to any action from authorities as burden of proof lies with you not the website."
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96my35 | How do stealth planes work and why can't radars detect them? | Technology | explainlikeimfive | {
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"Radar works by shooting out invisible light waves in all directions. That light gets reflected back to the antenna which can detect it and based on any frequency/amplitude changes and signal lost it can determine the size of an object and its distance away. Stealth planes operate on the basic principle of making sure as little of the reflected light makes it back to the radar antenna to be detected. The first method was design of the craft. By situating the panels of the craft at specific angles you could ensure that only small bits ever reflected light in one direction at any given time. That's why the initial stealth craft, like the F-117 Nighthawk, looked weird with their triangular shape and sharp edges. The second method was material type. By making the shell of the craft out of special material it could absorb the radar light, rather than reflect it, making it invisible to radar. As technology improved they could rely more on the radar absorbing material and less on the design, which allowed them to go back to the more standard aircraft design as seen in the F-22 raptor.",
"Mostly, they are designed with shapes that will reflect radar waves off in a different direction than where they came from. This prevents traditional radar devices from seeing them. Also, they are coated in radar-wave-absorbing paint."
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96n2c8 | Why is airplane mode necessary on airplanes? | Technology | explainlikeimfive | {
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"Airplanes have lots of radios in the cockpit. They use them both to communicate, and to navigate (guide the plane through the sky, and down to the ground at the airport). When another radio on board (such as a cell phone) transmits at full strength, it can interfere with the radio reception for the aircraft's radios. Most commonly you will hear this as a slightly annoying chirping in the headset of the pilot. Sometimes it will cause the GPS to lose lock on the satellites. (I had this happen when I was sitting copilot in a small jet once while approaching an airport.) In good weather, this is just a minor annoyance. In poor weather, this can cause an extra distraction to the flight crew when they need it least. So they ask that passengers turn their radio transmitters off (put phones in airplane mode) to avoid this issue. Newer radios in commercial airliners have good enough noise rejection to avoid being impacted by this (as cell phones and navigation radios work on different frequencies), but many planes have older equipment which is not as good at avoiding issues, and most pilots adopt the conservative \"once bitten twice shy\" philosophy (and rightly so). Airlines which allow the use of cell phones in flight have done enough flights with their particular aircraft and radio set up to know that they tend not to have any problems of this type."
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96n2qp | Why do so many game devs tie physics and other calculations to frame rate? | So many games ported to PC have horrendous support for higher refresh rates, which I know is because the developers have tied certain things like physics calculations to the frame rate. Is this done for a good reason today, or is this a relic of the bronze age of gaming that should and will get better? | Technology | explainlikeimfive | {
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"Because it's easier. There are two other options: 1) make physics and logic still tied to the actual framerate but scale it by the time between each frame 2) run physics seperately at a fixed rate and interpolate data when you render. So the FPS may be, say, 100, but physics calculations is still running 30 or 60 times a second. --- 1) has issues, notably that if you have very high framerates then you'll get into stability issues with 32 bit floating point numbers. It's also not deterministic (testing issues) and for games with replay systems, well, no luck here. 2) is the most \"complete\" option, but it's also very complicated to implement. To tie physics and kinematics into frame rate is a simple solution that does the job. For consoles where you'll only target one framerate, it's a practical solution. These days, as third party engine use is more common it's not as much an issue, since the hard engineering work is already done by Unity or Epic.",
"Because it's quick and easy. When making a game you need to decide how often it's going to refresh. Since the player will only ever see the difference between two frames (if an update occurs between two updates corresponding to different frames, that specific refresh will never be seen by the player) it makes sense to link the refresh rate of the engine with the framerate - why waste resources on stuff the player won't even see? Of course, this does make sense on the specific condition that the framerate is constant. And a lot of players don't want to be tied to a specific framerate.",
"It's the easiest way to get consistent physics on a platform where you expect a constant framerate. Game consoles are the most common example since they all have the exact same hardware. Variable frame rate means you either have to decouple the physics from the graphic frame update or write the physics engine to 'step forward' in time in variable-length time steps. Neither option are easy and it's very common to have strange bugs like falling through floors because of weird corner cases in collisions.",
"You're kind of misunderstanding the issue. Devs don't do it on purpose necessarily to mess with gamers, but it's something that can be remedied with properly planned programming. So let me explain it as simply as I can without too much game dev garble. When programming anything, the speed of the program is automatically tied to the power of the hardware it's running on. Programmers can make their programs run on any platform at the same frame rate using an added calculation. (Time.DeltaTime in the Unity3D engine) Games for consoles only are usually programmed directly for the consoles specifications, and therefore programmers neglect to plan ahead with these added calculations. So if a programmer doesn't plan ahead, a PC port can prove to be glitchy, because PC gamers usually run hardware much higher than current consoles. Hope it clarifies a bit. Edit: This answer is 100% correct. Downvoting it won't make it any less right. Source? I'm a game developer, with a degree in game design. I've programmed and scripted for years."
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96oexj | Why do videos when loading (like on putlocker or gomovies) stop loading at certain points, as in stop at a point and require me to pause and unpause and wait? | Technology | explainlikeimfive | {
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"Video is compressed with what is called interframe compression, so a frame isn’t an actual image, but a set of instructions to build the new frame form the previous, however some frames need to be a full image, so in a big scene change it might take longer to load the frame. And also internet connection might be inconsistent due to more devices being connected and demanding data"
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96p3cj | What are cookies on websites? | Technology | explainlikeimfive | {
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"text": [
"A cookie is just a bit of data that the website stores on your computer so it can access it again later. Let's say I've made a simple web page that asks for your name, then says \"Hello, [name].\" That's pretty easy to do, but it will have to ask for your name every time you go to the site, which will get annoying. To fix that, I can make a cookie that stores your name. That way you only have to enter your name the first time, and the next time you go back to the site it can just look at the cookie instead of asking you again. Of course that's a lot simpler than what most cookies are used for on real sites, but that's the basic idea.",
"Essentially, it's a persistent form of storing information More specifically, it can be described as being either: * Session cookie: deleted when the browser closes * Persistent cookie: deleted on a specified date and time Session cookies are usually used on a smaller scale for being used across pages, like when you're shopping and you're going to different pages. Persistent cookies are the tools used for things like staying logged into websites.Controversially, this same tool can also be used to track you and form advertising data to target what you'd be interested in.",
"A cookie is just some data (usually just slme text) that a website stores on your computer. When you load a website, your web browser communicates with the server running the webpage over a protocol called HTTP. Over HTTP, the web server can provide cookies when you load a page or a file from a web server. The server can request that you set or remove cookies on your web browser when you do this. When the webserver provides cookies after you load a page, those cookies are saved to your hard drive. Once again, these cookies are just bits of text that the server sends. Each time you load a page under the domain ( URL_0 for example) that set the cookie, those cookies are sent over HTTP to the server with the request to the page. Because of this, many websites use cookies to store settings that are needed when you request the page. Since cookies are exchanged between the server and your web browser whenever you load a file, many sites use what are called \"tracking cookies\" by loading a 1x1 image on a site. For example, Google might load a 1x1 image from the same domain on many different sites. The cookies that Google might store could contain a token that Google uses to identify you on each site that loads that 1x1 image. They can do this on the server side because the cookie is sent containing the token cookie. Sorry, that was probably awful. This is my first ELI5"
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96r4c7 | Why do US households have washing machine and dryer as two different appliances instead of a single appliance ? | Technology | explainlikeimfive | {
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"A combined unit isn’t as efficient as 2 individual ones. You can fit more in a washing load than a drying load, so you either need to do more, smaller loads, or take some clothes out before the drying cycle starts. Also, you can only do one load at a time. If you have separate units you can start a second wash whilst the first is in the dryer. And as previously mentioned, if something goes wrong, you can’t wash or dry anything",
"This isn't strictly a US thing. I've only seen them as two separate units in places that I've been in Europe as well as south America. As for the reason, because they work more efficiently that way. Do you have any pictures or info on the ones they use in your country?"
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96r5zw | What are "car guys" talking about with all the numbers? | I saw a guy today driving a '73 Nova SS. I said, "nice car." He went on to say something like, "yeah, it's got a 350 over 20. I took out the 4 speed to an overdrive, and went to a 3.5. I changed the exhaust from a 2 and a quarter to 3 inch, now it rips." I was like, "and it's red!" | Technology | explainlikeimfive | {
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"So it's a 350 cu in motor, bored .020 over to increase it's displacement. He switched from a 4 speed auto to something I've never heard of on that context before. And he increased the size of his exhaust pipes to 3in in diameter.",
"So, in this case, I can make a couple of guesses. \"350\" most likely refers to the total displacement volume -- i.e., the volume of all the engine's cylinders is 350 cubic centimeters. \"Over 20\" may refer to a process called \"overboring,\" where the cylinders' diameter is increased 0.2 inches. The \"4 speed\" designation refers to how many forward gears the transmission has. I have no idea what he might mean by \"going to a 3.5,\" other than maybe he's bullshitting. Note, I'm not a car guy, so I might be wrong, but I'm unsure what might be meant by half a forward gear. Finally, the exhaust numbers are simply measurements of the diameter of the exhaust pipe."
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96ublu | How did black boxes for descrambling cable channels in the 90s work? | Technology | explainlikeimfive | {
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"Back then the way scrambling worked was they just didn't send the sync pulse (the mark for the start of the frame). The cable box then had a circuit that when authorized made a sync pulse and inserted it back in. The descramblers were boxes that just added in sync pulse to make it watchable."
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96vbui | We get the internet from ISPs(Internet Service Providers). But how do they get it? (Or how does it work)? | Technology | explainlikeimfive | {
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"The phrase \"get internet from\" doesn't really make sense. Internet isn't a thing. I can't give you a barrel of internet, the same way I could give you a battery charged with energy. When you hear \"internet\", you should think \"conversation\", except the conversation is between computers. I can't give you a conversation, but I *can* give you a private room to talk to someone in. ISPs own the cables that connect computers around the world and across oceans, as well as the routers that figure out which way a given piece of data should be sent at every junction. But fundamentally, its just a bunch of wires linking a lot of computers together. Lets say you wanted to visit URL_0 , When you type that into your browser and hit enter, a bunch of things happen. 1. Your browser knows the *name* of the website, but not where to find the computer that has the data on it, it needs its *address*, called an IP address. It gets this by connecting to a Domain Name Server (DNS) which is like a phone book for the internet, maintaining a list of names and their corresponding addresses. 2. Now that it knows the address, it sends a request for the webpage to that address, through the cable from your house. 3. Every time that request gets to a junction, the router there figures out which way to send it based on how addresses are assigned around the world. In the same way that a neighborhood might have all even numbers on the right and odd numbers on the left, there are patterns that routers can use to figure out what country, city, etc. an address is in even if they don't know the exact machine. 4. When the request gets to the servers hosting URL_0 , those servers receive it, interpret what the request is asking for, and generate a response to send back. 5. The original request came with its own IP address, like a return address on a letter, so the server sends its response back to there, and it follows the same process of routing on the way back (although it might take a different route, depending on traffic and other factors, just like navigating by road) 6. When your browser receives the response, it decodes it, and displays it for you to see.",
"FAQ here. Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Where do internet providers get their internet from and why can't we make our own? ]( URL_1 ) ^(_ > 100 comments_) 1. [ELI5: Where do ISP companies get their internet from? ]( URL_2 ) ^(_4 comments_) 1. [ELI5: How do internet service providers work and is it possible for me to connect to the internet without them? ]( URL_3 ) ^(_55 comments_) 1. [ELI5: How do internet providers provide internet? Where do they get it from? ]( URL_0 ) ^(_72 comments_) 1. [ELI5: Where do ISPs get Internet connection? ]( URL_4 ) ^(_4 comments_) 1. [ELI5: How do ISPs get \"the internet\"? ]( URL_6 ) ^(_6 comments_) 1. [ELI5:How does my Internet Service Provider (ISP) connect to a server that isn't also in that ISP's network? ]( URL_5 ) ^(_4 comments_)",
"Internet Protocol network participants essentially have a gateway address and an assigned address. When they want to send something to another computer on the network, they send the information to the gateway which then routes it to another network node that should know about the eventual destination, and so on, until it reaches the destination. The Internet works because there are only a few servers that operate at the root level, dividing it up. Those divisions are passed on to the next layer down, and so on, with each level caching the information. As such, your computer may know the addresses of a limited number of destinations, and your gateway may have the routes to those (the computers to send the data through) cached. ISPs are essentially the gateway and router nodes one level in from the most external leaves. They then have sharing agreements with each other (peering) and connections to the trunk via their own ISP's gateway servers. You don't need an ISP to do Internet networking though; all you need is a large enough cluster of networked computers. ISPs just make it all tidier and easier to find connection nodes -- plus, they often provide the transport layer you send the data over.",
"Heres how i would explain it to a 5 year old: The internet is just a huge global network of computers that are all connected. All the cables and switches and everything that connect all of these computers make up the infrastructure of the internet, and the organizations that build and maintain this infrastructure are called Internet Service Providers. When you pay your internet bill, you are paying to use this infrastructure. ISPs are split into tiers. Your local ISP is a lower tier provider. They have paid to run cables out to your house and the houses around you to form a local network. They pay to have their network connected to a bigger regional network operated by a higher tier provider. At the very top are the Tier 1 providers who operate large networks spanning whole continents, with cables running under the ocean to connect to other continents. A way to illustrate this is to think of it like transportation. Say you live in a small town and want to visit your friend who lives in a small town on another continent. The quickest way to get there is by flying, but neither of your towns have an airport. So you leave your house and take a cab to the bus station. There you get on a bus that takes you to the nearest city with an airport. Now you can board a plane to fly you to the continent where your friend lives. You take a bus to your friends town, and then a cab to your friend's house. You've gone from your house to your friends house thousands of miles away, but it took 3 different levels of transportation to get there efficiently. Your local internet provider is like the cab company. Tier 2 providers are like the bus company, and tier 1 providers are like the airline."
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96wi09 | Why does Apple and Android have a issue with co-compatibility of sending videos across platforms? It reduces to like 240p. | Technology | explainlikeimfive | {
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"It doesn't. The method you're using to send the video is causing degradation, whatever that may be. I have no issues viewing 1080p video on my android uploaded to YouTube on a mac or iOS device. If you are sending the video file via a text message (MMS) the phone will usually reduce the filesize to less than 3 MB, which is the MMS limit. iOS will likely see this same issue to other iOS devices that do not use iMessage. If you do use a different delivery method such as iMessage, it usually has a much higher filesize limit (25 MB+)."
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96wi8j | Why do electrics showers always have bad thermostats? | I've lived in 3 different houses and used around 5 or 6 different electric showers and every single one has had an unresponsive thermostat. For example this morning I jumped in the shower before work. Yesterday I showered and it was the perfect temperature on setting 5. This morning I jumped in with the setting on 5 and it was scalding. Moved it to 4 and it was still scalding, then moved it to 3 and it went ice cold. Why does this seem to be such a common theme with electric showers? - FYI I am in England. Not sure if it is the same in other countries. | Technology | explainlikeimfive | {
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"Electric showers don't have thermostats. Temperature rise depends on the selected heater power and the flow rate. Flow rate is set by the flow restrictor valve, which is the main control. Outlet temperature depends on inlet temperature and temperature rise."
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970hnt | Inmarsat’s role in Malaysia Airlines flight 370 | After the plane was lost from radar contact, how did inmarsat function to make “handshakes” hourly with the plane? what exactly is a “handshake”? | Technology | explainlikeimfive | {
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"Oh, one I can finally help with! So Inmarsat is a satellite company. Their satellites provide a ton of communication and data collection for all types of agencies/companies, but in this case Inmarsat was communicating with the aircraft. Basically this just means the satellite was communicating periodically with the plane (more importantly, the plane’s Satellite Data Unit, or SDU). The SDU and satellite exchange signals every so often (the “handshake” or “ping”) and the satellite collects the info from the exchange and relays it back to the ground. Now, when the plane lost contact with radar, this did not turn off the SDU. In fact, Inmarsat continued to receive those satellite pings from the aircraft for about another 6 or 7 hours. This is how they knew that the plane was still flying, or at least operational- the SDU couldn’t communicate after all if the plane had crashed. In terms of how they managed to get an estimated flight path of the aircraft from those pings is a lot more math and science than I can cover here, because the pings themselves did not contain this information. But it basically involves calculating the position of the satellite at the time of the pings, and the frequency of the pings. But that’s very very dumbed down. Edit: words and things"
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971jvu | How much detail can a satellite see? | Technology | explainlikeimfive | {
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"About the best commercial imagery, DigitalGlobe's WorldView-3 and -4 sats have a resolution of 0.31m under ideal conditions. So each pixel represents about 31cm. So you can identify a car, but probably not the model. Generally you can tell there's a person in the image, but no features."
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9738pw | How can smart devices generate an accurate battery percentage? | Technology | explainlikeimfive | {
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"As the amount of power in a battery goes down, so does the voltage. The phone uses the voltage to calculate how much power is left. Then it turns that into a percentage"
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974bu7 | I read that some sub marines are powered by nuclear power such as Uranium for years before having to be changed. Why cant our normal everyday electric also come from Uranium? | Technology | explainlikeimfive | {
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"It can and it does. Nuclear submarines, nuclear aircraft carriers, and nuclear power plants all generate electricity in the same way Some countries generate a significant amount of their power from nuclear energy. France generates 40% of its electricity from its 58 nuclear reactors. Expanding capacity is hard. New nuclear reactors are very expensive due to all the regulations and safety features that are required. The local population doesn't understand them and is generally afraid of the radiation(which doesn't get out) and pushes back against the construction of new reactors and power plants. We're more focused on expanding solar and wind capacity these days as they have far far less political push back and are significantly quicker and more cost effective in the short term than nuclear power",
"It does, nuclear power plants are a thing. But what you're imagining, probably, is a personal nuclear reactor to power all of the stuff in *one* house. A nuclear reactor is really complicated and really expensive and if maintained improperly can cause a nuclear disaster; after use it generates highly radioactive waste material that needs to be disposed of (and even the government has no real solution for this!). Even if they would let you build one and fuel it with radioactive material, you would probably produce more energy than your individual house would ever use. You might take a look at small reactors [this Wikipedia article]( URL_0 ); if you click \"Gross power\" you can sort by the amount of power able to be produced: it doesn't get very small! A smaller scale nuclear-powered device is a [radioisotope thermoelectric generator]( URL_1 ). Radioisotopes experience mass decay, and according to E=mc^2 they also produce energy. This has been used in spaceships going on very, very long missions. But you still have to get radioactive isotopes, so nobody would ever let you use it!",
"It can and does in many places. Problem is there have been serious problems with nuclear plants eg three mile island and Chernobyl plus another in Japan I think was damaged during an earthquake I’m not sure. In these three instances major problems occurred you can google the",
"Uranium fuelled reactors like the CANDU use ordinary uranium, however in the US, most reactors use enriched uranium for fuel, and the byproduct of that reactor can then be further processed to make nuclear weapons. Still other uranium fuelled reactors have an end product that can be isotopes used in medical testing and scientific instruments and for other scientific research purposes. And then there is the Thorium reactor that doesn't even use uranium. Thorium is plentiful and cheap. It also can be used as a reactor fuel, with a very intrinsically safe design, but the development costs are huge before a modern design can be standardised, and there is no military benefit from the end products."
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977mu6 | How do videogame companies copy-protect their games (physical discs)? | Technology | explainlikeimfive | {
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"Mostly by doing things that are easy to detect, but hard to reproduce. For instance, one technique is placing artificial defects on the disk, and checking if they're there. Many duplication programs, when encountering a defect, won't create an identical defect in the copy. They'll try reading that data, fail, and then either abort the copy entirely, or write a readable but empty sector in its place on the copy. Some such methods rely on techniques that can only be done in a CD factory and that a burner is unable to reproduce. For some of them, the drive may be capable but still refuse to reproduce it because somebody convinced the drive's manufacturer to write the drive's firmware in such a way that it would not allow to do what's needed to duplicate the copy protection."
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9782gd | Why is Windows hated? | Technology | explainlikeimfive | {
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"Its problem is popularity. If you have computer, it most likely has windows. Thus, if you have encountered problem it was with windows. Another are third party hardware vendors. Windows was very easy to destabilize by faulty driver or with bad driver combination. Bad hardware part would cause errors that look like it is windows fault too (corrupted harddrive, fried modem, whatever...) Third was user expertize. Systems lauded as stable (ie. Linux) usually had more technical users who were able to handle problems. Windows users did not have tools and knowledge to do that - even power users were not privy to some critical infromation needed to troubleshoot and fox problems. Last are memes. Windows had very bad releases in past, so people remember them as being buggy and prone to cashing. And will claim they are that way even nowadays. its just very long surviving meme nowadays.",
"Each edition has become more and more \"idiot-proof\", meaning it's harder and harder to do simple things like change your screensaver or background, or (Win8, I'm looking at you!) default to a traditional, desktop-friendly \"desktop\" view instead of the touch-friendly tiles. It also means that medium-complicated things like setting or checking your firewall exceptions has become incredibly difficult, and annoys or angers \"power-users\" when they're forced to use Windows. (Most power-users prefer Linux these days - good old command-line operating system with an optional gui.) Windows is also resource-intensive and full of bloatware that's impossible to uninstall. Twenty processes all named svchost.exe? Seriously? How many does one user need?",
"Windows is the most used operating system for desktops and laptops in the world. Its benefits are actually the source of its problems; modularity and popularity mean that Microsoft can't adequately control what types of devices, software, hardware, or protocols are used on all of their systems, which means there can be compatibility issues. There are also sometimes issues with third-party gear that can create bugs and instability. This means that if you're experienced and knowledgeable, you can create a highly customized computer that will run perfectly. On the flip side, if you don't know what you're doing, you can accidentally partition your bios (happened to my brother) or overheat your system. Systems that use MacOS don't have those problems; all gear and software is directly controlled by Apple, so they can extensively test, monitor, and design things to be perfectly compatible. They can also phase out support of outdated items to reduce the amount of different systems to connect to. All these controls limit what the user can do with a MacOS system, so you can't really screw them up."
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979rus | What are the actual physical changes that happen inside a computer while it's running? | Specifically curious about what it means to write something to memory: What happens inside a computer when I save a text file, or a Jpeg, or save a game, or anything else that changes the state of the computer from what it was before, to something else, and how it continues to exist after the computer is turned off. | Technology | explainlikeimfive | {
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"Permanent storage in computers generally is done by one of two technologies. For magnetic hard drives, there's a spinning plate covered with magnetic material and a mechanism that allows to detect and change the \"direction\" of the magnetism in very very small segments of that platter. So writing a file would involve that mechanism changing the magnetic pattern on the disk. For solid state drives (SSD) in computers, as well as the common USB flash memory sticks, the memory consists of a silicon chip with lots and lots of very small isolated conducting spaces which can store electric charge (extra electrons), and transistors to control that. Writing to that memory involves storing electric charge in some (and removing from others) of these \"pockets\" called NAND cells. Both of these things are somewhat permanent and continue to persist after power is turned off.",
"man, this question is like, an entire computer science degree. Okay. Condensing a few years into a paragraph. When you save a file, the data is represented in some way. Computers are fundamentally representational, that is, they turn something that has meaning to you into an encoded value, and then store that, and does the reverse to show it to you. Let's say, the letter \"A\" is represented by the number value 65. That'll be encoded as a series of bits, 1000001, where the first 1 is 64 and the last 1 is a 1, and stored - physically - as magnetic domains on a platter, or coloured holes on a CD. So a 1 is represented with a \"north\" magnetic domain and a zero is represented by a \"south\" magnetic domain. Then, when you want to retrieve the data, it's first read off the disk into a form that the computer can process, wends its way through and eventually gets shown on your screen as an \"A\".",
"> What happens inside a computer when I save a text file, or a Jpeg, or save a game Regardless of what you're saving, it all boils down to the same thing, depending on the type of storage. For a disk drive (HDD), you're changing the direction of magnetivity on different portions of the disk itself. Each space on the disk has a magnetic direction that represents one of two states. One state represents a \"0\" and the other state represents a \"1\". For solid state drives (SSD) you basically have little transistors that have two discrete states. If you charge it (a simplified term), it has a \"0\" state. If it isn't charged (again, an oversimplified explanation) it has a \"1\" state. There are some other memory types (notably RAM technology), but it all basically boils down to using electricity to represent a certain state. For the most part, there are very few physical changes, especially if you're not using any form of disk storage. Storage, computing, and transmission of data is primarily done by passing electricity through different components, which don't really change physically. Maybe they heat up, and technically get heavier because they have more energy, but a normal observer wouldn't be able to notice any physical changes.",
"Preface: This is a very basic explanation, newer tech probably works differently, but this is my best explanation. To understand Non-volatile memory/NVM(doesn't get erased when power is turned off, like your hard drive) you have to first understand volatile memory/VM (RAM/Cache). Your RAM contains basically a bunch of transistors, electronically controlled switches, which can either be turned on or off based on voltage applied fo the \"gate\".These are arranged in certain ways to form Logic Gates, which usually have 1-2 inputs and one output [Here's a deeper explanation]( URL_0 s/CAL/digital-logic/gatesfunc/index.html) If we arrange a few of these gates, usually NAND these days, we can get whats called a [Data Latch]( URL_1 . With these we can \"set\" an output and keep it there without constantly needing an input. There are many, many, of these in RAM, with each latch output representing one Bit, so in an 8GB RAM stick there is somewhere on the order of 64 billion of these. Great, so now we can store bits and read the outputs of the latches to read/write data while the power is on. NVM works similarly, but we use transistors that basically stay open/closed (based on what they were set to w/ power) when no power is present."
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97d8pd | How do 3d holographic projectors work and what exactly are the holograms projected onto since there is no screen? | Technology | explainlikeimfive | {
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"Most *don’t*, or at least not the way you are thinking. By far the vast majority of 3D “holograms” you see out there are actually projected onto a transparent screen in such a way that it just looks like there is actually a 3D thing behind the (see through so you don’t see it) screen. That said there *are* a variety of things in the research phase right now that work as actual 3D holograms, generally through use of invisible lasers to either ionize the air itself (think making hundreds of tiny explosions), lighting up a tiny particle that gets moved around with magnetic fields, or by using some sort of containing fluid/gas. Since the research is all really new right now there isn’t exactly a single method that everyone has figured out to be best yet.",
"There's no such thing as a holographic projector. There are projectors that create the illusion of 3D, however they are not holographic. They are just normal 2D images in a context that fools your mind. The most common of these illusion ones uses the [Pepper's ghost effect]( URL_0 ). The viewer looks at a background scene that is behind an angled pane of glass. The angle of the glass is chosen so that a projection screen is reflected to the viewer. So, the viewer sees both the background scene and the projection screen at the same time. As a result, any image appearing on the screen seems to float within the background scene. This is how the Tupac \"hologram\" and the Hatsune Miku \"hologram\"s work. Sometimes, they will use multiple glass planes so that the reflection can appear at different distances from the viewer. This is also the same way the transparent pyramid \"holograms\" that you can get for your cell phone work. You're not looking at an object floating in the middle of the pyramid. You're just looking at a 2D reflection. There are other types of pseudo-holograms that work by presenting a different image to the left eye and to the right eye, kind of like 3D movies do it, but without the glasses. Frequently, they use a rotating mirror that is reflecting different images based on how far the mirror has rotated. As the mirror pivots, your left eye sees a different image than your right eye and your brain combines them into a \"3D\" image. Despite the name, even multiplex stereographic holograms like the ones used in [*Logan's Run*]( URL_1 ) are only generating 3D using 2D images. As visually stunning as these pseudo-holograms may be, they all lack motion parallax, because all they are is 2D images. True holograms have motion parallax. If there is an object in the hologram that is blocking your view of another object in the hologram, you can move your head to the side and look behind the blocking object. I once saw a true hologram called *Pipe Dreams*. It had various objects, like a doll, that you could look at, and it had a few short tubes in the image. You could move your head and look at the doll through the tube. It was amazing. You can't do that with any other system."
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97dw1y | What causes loading bars to get stuck or slow way down near completion? Is it that developers put the hardest things to load at the end of the progress so impatient users stick around? | Technology | explainlikeimfive | {
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"Usually it's system things (like cache/index regeneration) that just takes a system dependent amount of time. There really isn't a way to estimate the progress. For example if you install a font, you might update the font cache so other applications can quickly find it, the time to update the font cache is dependent on how many fonts you have installed, so the installer really isn't going to be prepared for however long it takes. Other things are restarting system services and such, again, you might have things installed, like plugins installed that will make it take longer to load.",
"The rate progress bars change depend on whether the programmer was able to (or bothered to) put in progress reports in the thing that's being done. If what the program is doing happens small steps (this is usually the case at some level, but it may not always be practical to add progress reports), they can add a line of code to update the progress bar, but if it's say calling a function that isn't in their program (library code, an operating system function) that takes a long time to run it's often not possible to get granular updates for the progress bar so the progress bar will halt and then jump forward when the long running thing has completed. As for why it happens more frequently at the end; it may be that, as a previous commenter wrote, some cache is being cleared after the actual work has been done that isn't under the program's control so no progress updates can be inserted.",
"Basically loading bars aren't accurate cause it takes a lot of effort to make them accurate and no one is paying for that. So what you get is a best effort approach. Like maybe you are installing 4 gigs worth of data, and just count the bytes. that's reasonably accurate, except when you near the end, and you are done with 3.9 gigs, but still have to install 100000 tiny files, which goes a lot slower than a couple of big ones. making it appear to stall near the end."
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97focy | Why can the task manager close tabs while simply pressing close program cant even though they should do the same thing | Technology | explainlikeimfive | {
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"They are not the same thing. There are a number of ways to close a program. It can get a bit complicated, but what you are looking at is mostly the difference between politely asking a program to finish its current work clean up its desk and leave and grabbing the program by the neck dragging it to the door and kicking it in the butt so it will stumble out to get it to leave the office. The letter is messier, but does not rely on the cooperation of the program being evicted.",
"Clicking close is basically asking very nicely for it to end when it can find the time Ending task (task manager) tells the program YOU NEED TO STOP RIGHT NOW! ending a process (also task manager) is taking a gun and shooting it.",
"The operating system (Windows) has a range of methods available to force a program to close. The most forceful may cause the program to lose its data with no change of saving it, so they are hidden away from easy-to-launch commands."
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97hkce | How do they remaster old tv shows in HD? | Surely if something was filmed originally in standard definition, and was never re-filmed, they wouldn’t be able to enhance the quality, right? All they have is lower quality footage with less pixels, how can that be converted into HD? | Technology | explainlikeimfive | {
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"Old analog stuff was filmed on film. Film is just photographs and doesn't store data in 'pixels' but on the color change of microscopic crystals so it's storing a ton more data than even the highest resolution tv.",
"Fun fact: when pee wees playhouse was converted to Blu-ray, only the raw footage was on film, all the edited stuff was on video tape. They re-edited the entire series from scratch.",
"It wasn't filmed in standard definition, it was filmed on analog film which has a much higher quality than standard definition, and only brought down to standard definition for broadcast.",
"If the master tracks are in bad quality, they're read with a computer and enhanced digitaly (colors recalculated, noise removed, resharpened or softened, etc) - > Digitaly Remastered. Masters from some anime series and movies of the 80s have been so incredible high quality, they could burn them directly to blueray without touching anything, in part since they've been produced for higher quality home medium than VHS. Digitaly stored stuff is far more difficult to remaster than analog videos.",
"Old old shows weren't captured in TV quality (I'll avoid use of word resolution). They're captured in high film quality, then produced downgraded to TV quality so it could be broadcasted at then- SD TV quality. To make these shows HD, all you do is go back to the original high film quality and scan them in as HD. Newer old shows like 80's we're captured in TV quality technology to save on film costs. You can't remaster them as HD because the original source is only TV quality. Shows like Babylon 5, Star Trek Deep Space 9."
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97ia4b | What is file compression and how does it work? | Technology | explainlikeimfive | {
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"Every computer file is made up of just 1s and 0s ... It's binary. Binary has some really long strings, if you broke even a small text file down you could have a thousand 1s and 0s Well, in this string of 1000, you're bound to get patterns ... Ten 0s in a row, or 101010 for a few dozen characters in a row. Patterns can always be explained with a shorthand. You can take that 10101010 ... And break it down to the binary equivalent of \"10x24\" If you do that enough in a file you end up taking a million ones and zeros and making them a few hundred thousand.",
"There are a few different forms of compression. I'll try and briefly describe a few of the simpler concepts. Dictionary compression. This works well on large text documents. Say a file contains a certain few words a lot of times, the file will store a dictionary where each of those words can be replaced with a number. This means that 100 identical 10 byte words can be replaced with 100 1 byte numbers and an 11 byte dictionary entry. Run length encoding. This is normally used on image files or sound files. Say, for example, you have 500 red pixels in a line, rather than storing the 3 byte value for red 500 times, you can store the 3 byte value for red and the 9 bit value for 500 (you'd probably have 2 bytes here obviously). A lot of compression is also lossy, especially sound, image and video files. This means that the data considered less important, like sounds that are hard to hear or faint differences in colour will be ignored. This will have a small effect on the quality but a large effect on the file size, and is very effective when combined with run length encoding. There are a lot more ways things are compressed, but these are the main ways that file sizes get reduced.",
"Compression looks for patterns and redundancies - things that can be expressed using less data. For example, if the compressor sees \"HHHHHHHHHHHH\" it can tell itself \"twelve H's\".",
"If there are three people in a room, Jimmy, John, and Josh and you've taken their orders for ice cream so someone can run to the store and grab it, instead of saying \"Jimmy wants vanilla, and John wants vanilla, and Josh wants vanilla\", you realize that it's quicker and easier to say \"everyone wants vanilla.\" You're getting the same information across but in less words. So compression just tries to find the most efficient way to represent repetitive pieces of data. In a \"lossy\" method of compression, sometimes the exact data isn't saved and we settle for \"close enough\". Perhaps John really wanted *French* vanilla, but we still say \"everyone wants vanilla\" because it's still good enough, especially if he's the only person that wants French vanilla. In general, sometimes describing how the data is constructed with other, smaller pieces of data is more efficient than the actual data. For example, the number 1,000,000,000 is more efficiently represented as 10\\^9. That's 4 characters versus the original 10 not even counting the commas. The end result is the same, just the directions to that result are shorter than the result itself.",
"**Fairly broadly speaking, when you text with emojis, you send compressed data!** 🙏✌ & nbsp; It works by finding repeating patterns in some text and replacing it with a shortcut where we know what it means. For example we take the text of your question and go and compress it. > How can a file of large data be zipped or compressed into a smaller package, but then put back into it's original state later on, where does the extra data go? *This text is 159 characters.* Lets go in and replace words that appear more than once with single characters (emojis for example) > How can a file of large 📃 be zipped or compressed ➡ a smaller package, but 🍵n put back ➡ it's original state later on, where does 🍵 extra 📃 go? *This text is now just 144 characters.* But we need to write somewhere what this character means, so a a table of what means what is needed: > data = 📃 > into = ➡ > the = 🍵 We have compressed the text a bit. But you notice it takes longer to read, as you have replace the standins with their correct full text again. That's why compressing saves space, but costs time. If we have longer texts, compression becomes more and more effective, as we replace more entries with their shortcuts. Words that only appear once don't need a shorthand, as establishing the lookup table entry would actually increase the size, instead of saving it, if the shorthand is only used once. Later on, we can create shortcuts for these shortcuts themselves, to further compress it.",
"Others are going into great detail, but I am going to treat you like you are 5. Look at the following sentence: \"I would like to cram some ham and spam into a tram in Vietnam\" That is 61 characters if I counted right including spaces. Notice all the instances \"am\". What if we substituted all instances of \"am\" with a $ sign instead? \"I would like to cr$ some h$ and sp$ into a tr$ in Vietn$\" Notice how that shortened the sentence by 5 characters. Now imagine doing that in a novel. It would squish it down quite a bit and the only additional information you would need to store is $ = \"am\".",
"The simple answer is that file compression works in sort of the same way you might write short hand for words. For example, you could define that \"The quick brown fox jumps over the lazy dog\" is equal to \"Tqbfjotld\". In essence, it's a shorter set of data that is representative of a much longer set of data. This is accomplished in different ways depending on the compression algorithm.",
"While it's provably impossible to have compression that works on *everything*, most types of data that we use have some redundancy/duplication in them. So compression relies on finding out such fragments and picking an encoding that removes that repetition. For a simplified example, I could replace every instance of \"the \" in text with \"q\", and every instance of \"q\" with \"the \" (in reality, a bit more complex to ensure that it's reversible) - then that would be an encoding that would on average reduce the size of most (but not all) text files. If you're into math, URL_0 is a reasonable method of compression that's simple enough to understood.",
"It works by replacing patterns for smaller equivalents while maintaining a table for reversing the encoded message later: \"Mary had a little lamb. Mary got hungry and ate the lamb. The lamb is now dead and Mary is not hungry anymore. Mary grew up and bought more lamb. Mary them all.\" Mary = 1 lamb = 2 hungry = 3 and = 4 is = 5 \"1had a little lamb. 1got 3 4 ate the 2. The 2 5 now dead 4 1 5 not 3 anymore. 1 grew up 4 bought more 2. 1 ate them all.\"",
"Some data files have repetitive or predictable bits, and those can be coded differently to save space. For example, if you had \"aaaaaaaaaaaaaaaaaaaa\" you could instead say \"20 a's\". File compression is simply a more formal way of doing that, and they replace common character sequences like \"th\" or \". \" (period space) with less used characters like à or ð. They also add a mapping to reverse the compression. The compressed file should look like random gibberish. The less random a file is, the more it can be compressed. The measure of information content in a file is called entropy -- the higher the entropy, the more information it has, the more random it looks, and the less it can be compressed.",
"Software engineer here. There are two main types of compression: 1) Lossless - When the data is compressed and expanded back to the original size, it will be a perfect match to the original data. (zip, .7z, .rar files are good examples of this) 2) Lossy - When the data is compressed and expanded back to the original size, it will be a close representation of the original data. (jpg, mp3, mkv files are good examples of this) For Lossless, there are many techniques used to represent common patterns in the data. For example, let's say I was to take the 10 most commonly used words that are 4+ characters long in a book and represent them with \\~0, \\~1, \\~2, \\~3, etc... Every time one of those words appeared, I would only consume two characters of space instead of however long the original word was, but you could create a perfect restoration from my compressed version. One method is called RLE encoding where you take a long series of repeated bytes and represent them by two bytes (one being the number to repeat, and the second being the count, i.e. 7 \"A\"'s is two bytes while AAAAAAA is seven bytes). Huffman encoding works by sorting the usage counts of all the bytes in the file and then using the shortest binary codes to represent the most common bytes. (bytes are 8 bits or on/off switches). So 0=most commonly used character, 10 = second most commonly used, 100 = third, 101 = fourth, etc... The most common byte now only takes up 1/8th the space. For Lossy, the data is almost always either audio or image/video. This is because this data is quite large and needs to be heavily compressed, and it's interpreted by fleshy monsters that will perceive roughly the same data if it's only slightly modified. For example, our eyes are really good at telling the brightness difference between two adjacent pixels, but we suck at telling if there's a color difference. This is because we have more rods than cones in our eyes. So, one easy trick is to just represent each pair of two pixels by two intensity values and then one X,Y lookup to a color value. This effectively reduces 6 bytes of data into 4 with no perceptible change. Changes in color values tend to happen gradually in images. You don't just see red pixels next to teal ones next to red ones next to teal ones. You usually would see slightly different shades of red next to each other. So, they found it was better to store the progression of pixels as overlapping sin waves that can be equated to a single value over a significant stretch. How high you set the compression determines how many sin waves they use, and this is DCT compression commonly found in JPG's. In motion pictures, the differences from one frame to the next are typically pretty minor. So, most movie compression involves taking the first frame and compressing it with DCT and then storing a series of just \"what changed after this frame\". If there's a scene change or even just periodically, they will submit a full frame again so that it is more practical to seek into the middle of a digital video. These are known as I and P frames in the industry. There's also additional complexities to this (B frames, panning, etc..), but the basic concept still stands. For audio compression, changes in the slope of the sin wave are typically stored as a velocity vector instead of individual sampling values. This doesn't equate perfectly to the original, but it's pretty damn close, and the encoding audio rate is how many of these velocity vectors you want to include."
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97itfp | Why do older vehicles have a blue stripe across the top of the front windshield, but newer vehicles don't? | Technology | explainlikeimfive | {
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"I work with windshields daily, to repair them. It's a coating against sunrays and heat. Modern cars have this coating integrated into the wind shield giving the entire glass a slight greenish or purple tint. It's less noticable but its still there.",
"My 2015 car still has the blue stripe on top of the windshield, so I'd think it's dependant on the manufacturer.",
"My Toyota has a solid black stripe in that area, I assume it does the same function, it's just not blue or transparent.",
"Did you know that some old cars from the thirties and forties used to have an external metal visor to help prevent glare from the sun, but it made it hard to see traffic lights at a stop. A way around that was a little ornamental prism on the dash that would catch the colored light of a traffic light and you could tell when it turned green by the refracted light through the glass. Also, if you wear polarized glasses, it is easier to see the pinkish/purplish/bronzish glass as described above. Mercedes windshields have this, for example.",
"It's a shade band - a strip of tinted glass to aid drivers driving into the sun. It helps cut down glare and REALLY helps if you can position the tint between you and the traffic light above you to see the lights change when the Sun is practically blinding you."
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97izk4 | why consoles still struggle to get 60 FPS | It's 2018 and you can play 4k on the console, yet you still can't get 60 FPS 1080p. What is that sacred piece of technology that PC gamers have and console players don't? | Technology | explainlikeimfive | {
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"> What is that sacred piece of technology that PC gamers have and console players don't? Expensive hardware. Consoles are kind of like the games they play. Games have a price tag of $60 (I know it's not really that anymore because of DLC, Season Pass, etc), but the sticker price of $60 is really important to that segment of the market. A $60 game with $60 of \"pretty much required\" DLC will sell (and be tolerated) much better than a $100 game with free DLC. Consoles need to be $400. If they're more than that, there needs to be a reason, and even if there are higher priced versions of a Playstation, the games they offer need to also play on the $400 version. Graphics cards in a PC that are firing off 1440p/60FPS and higher are at least $500 by themselves, and often more expensive than that. Console makers usually sell their consoles at a loss and make up the revenue through the licensing of the games to publishers/developers. But it can't be THAT much over $400 in cost to the console companies. They rely on standardized hardware to try to milk what they can out of the hardware they're stuck with. This is also what makes porting games difficult.",
"I think this question is really asking about developers, not consoles. They can make a game with PS2 graphics that runs at 300 FPS, or a slideshow that's almost Pixar-quality. The game determines the framerate, and believe it or not, for a lot of people framerate really doesn't mean much. In some cases, they can't even tell if something's 60 FPS or not. So outside of certain niches, developers will prioritize graphical quality over hitting 60 FPS.",
"Cost. Games get more graphically demanding over time, yet console manufacturers want to be able to target an attractive price point without taking losses",
"Choice. It's purely choice. Any gaming device has a certain budget of magic computer beans. You can spend these beans on getting 60fps, or making each of the frames the prettiest they could be. Traditionally console game developers made that choice for you. While the PC version of the game let you decide. That's changed though now with the PS4Pro and more so with Xbox One X. Now many consoles will let you choose. Sometimes there are even three choices in a console game - prettiest version, highest resolution version, and highest frame rate.",
"2 main explanations here: 1) consoles have a specific market of, primarily, folks who play them on TVs. Further, most TVs being sold today are pushing 4k and HDR over higher refresh rates. 2) it's more demanding of console graphics cards to run 60fps at the graphics people expect than to do a higher resolution. All said, there are certainly games running at 60fps on consoles today. Though consoles like the Xbox one x are focusing primarily on 4k HDR since that's the current TV market demand."
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97kafs | How are glitches/exploits/secrets found in video games, surely people don't spend hours and hours trying to find them with only a small chance there's actually something to find? | Technology | explainlikeimfive | {
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"That’s exactly how they are found, that and dumb luck. The larger / more game breaking ones are usually found in the QA process which is literally doing repetitive motions over and over and over. A few test cases might be something simple like Jump over the box 50 times. Or there might be jump over the box 50 times while unsheathing your weapon mid air and spinning your camera around.",
"There's a few ways that I'm aware of: First, there's when you find a glitch by a accident, then figure out what caused it. Sometimes this can provide information that leads to finding other glitches. For the more complicated glitches, it's about the code. People can examine the game file, which will be a long series of numbers. By watching how the numbers change as the game is played, you can figure out what each number means, and maybe find possible glitches that occur from how the numbers are set up.",
"Speed runners call it mapping I think. They basically try to break the game to expedite finishing it they find bugs and exploit them. You should see the [Skyrim speedruns on youtube]( URL_0 ), they actually hold annual events for this, fastest I think I saw was under 50min. So that's one way."
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97nklg | Why can we use our touch screen smartphones only with our fingers? Why doesn’t it work if we use a pencil for example? | Technology | explainlikeimfive | {
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"Modern touch screens are capacitive. They detect \"touch\" when your finger (which is electromagnetically conductive) changes the capacitance of the area near the screen.",
"In order for most modern touch screens to work, the thing that touches them needs to conduct a certain amount of electricity. When you touch the screen with your finger, it completes the circuit and it registers as a “touch”."
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97nsfh | How can the speed limit be enforced by aircraft? | Technology | explainlikeimfive | {
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"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5:How are speed limits enforced by aircraft? ]( URL_2 ) ^(_ > 100 comments_) 1. [When the sign says \"Speed limit enforced by aircraft,\" is it really? How? ]( URL_5 ) ^(_._) 1. [How do they enforce a highways speed limit by aircraft? Has anyone every received a ticket this way? ]( URL_0 ) ^(_._) 1. [Are the \"Speed Limit Enforced by Aircraft\" signs actually enforced by aircraft? ]( URL_1 ) ^(_._) 1. [I just saw a sign that said \"Speed Limit Enforced by Aircraft.\" How does that work? How would aircraft help in enforcing the speed limit? ]( URL_3 ) ^(_._) 1. [ELI5 how do police enforce speed limits with aircraft? ]( URL_7 ) ^(_7 comments_) 1. [What does it mean when speed limit signs say \"enforced by aircraft\"? ]( URL_4 ) ^(_._) 1. [ELI5: What does \"Speed Enforced By Aircraft\" mean? ]( URL_6 ) ^(_5 comments_)",
"Next time you are in an area with the patrolled by aircraft sign, pay attention to the shoulders of the road. There are markings on the side of the road at specific intervals. As you pass a marker, your time between markers can be clocked. This will give an average speed over distance. URL_0"
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"https://np.reddit.com/r/explainlikeimfive/comments/33zatd/eli5how_are_speed_limits_enforced_by_aircraft/",
"https://www.reddit.com/r/NoStupidQuestions/comments/95i0he/i_just_saw_a_sign_that_said_speed_limit_enforced/",
"https://www.reddit.com/r/NoStupidQuestions/comments/8wpdbc/what_does_it_mean_when_speed_limit_signs_say/",
"https://www.reddit.com/r/NoStupidQuestions/comments/3wxcvi/when_the_sign_says_speed_limit_enforced_by/",
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97pj6k | Machine Learning and storage space | How does machine learning uses storage space? After analyzing terabytes of data, what happens to the old data, does it get purge, does the AI generates its own dataset? How much storage space would machine learning use to learn? | Technology | explainlikeimfive | {
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"Machine Learning is an *algorithm*, like **(X + 3 = Y)** but far, far more complex. Algorithm intelligence doesn't store any data, other than it's own self, which is just that one string, like I showed above. The algorithm doesn't get any longer as it learns, it only changes the variables (3 to 5, X to A). So, it stays the same size. That's why you can fit it on a flash drive. Machine learning system reads through terabytes of data as it learns, but it doesn't hold on to it. It is discarded.",
"I'd advise you take a look at[ this video]( URL_0 ) for a basic understanding of machine learning :D"
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97riuo | What exactly is Discord? | Technology | explainlikeimfive | {
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"It is a gaming chat application intended to be used simultaneously while pc gaming. It has functions that allow you to voice chat while playing, post pictures, and traditionally text chat. You can host your own channel and people join it knowing that the MonsterHunterWorld channel will be only people playing that game. Makes it easy to talk and team up. It is the evolution of older chat solutions like Vent."
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97sh45 | Why is it so hard to make bionic eye that works? | Do we know how to attach it to someone? Humans have already made bionic arms that can be controlled with one's mind. | Technology | explainlikeimfive | {
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"We don't know how to build a good-quality connection to the optic nerve, which is where the eye connects to the brain.",
"The eye is pretty tricky. It has three main functional parts - the lens, which changes shape for different viewing conditions, the iris, which controls the amount of light that enters the eye, and the retina, which is the light sensitive part at the back of the eye. All of these need to send information via the optic nerve (as u/Concise_Pirate pointed out) to the brain, in a way that's somewhat specific to each person. The major problem is with the retina. This is basically a lattice of millions upon millions of receptors, which come in a number of different types. They have to connect to the brain in a very specific way or the signal will be unintelligible. With our current technology I think it's simply too complex a task to account for all of the possible variations. Note though that we've had some success with really crude direct stimulation of the visual parts of the brain via electrodes - people have been able to see crude outlines, though with no colour or detail. That's really the very limit of our tech right now, because while we understand the very first step in visual processing (i.e. how we perceive motion, lines, colour differences, etc), we have very little idea of how that's all pieced together.",
"3 things we need for a functional bionic eye 1. Visual sensor (aka camera). This needs to be small enough to fit into the eye-socket, have enough power to run indefinitely and have resolution & colour detection equal to the human eye. This is technologically beyond us right now. 2. Connection to ocular nerves. This is a major problem, you can’t easily wire each “pixel” of the sensor to a nerve ending. In fact, scar tissue will form that blocks off the retina, making it even more difficult to connect. It would take a team of surgeons something like 1000 man-hours where they have to do extremely delicate work on a microscopic level. Impossible unless we find a way to have it connect naturally. 3. Image processing by the brain. We don’t know how the brain recognises signals. How should we encode the visual input? If we give some weird input into the ocular nerves, will the brain learn to see it as colour? Or just a jumbled confusing mess that gives you a headache."
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97sijr | How do services like Google photos and iCloud guarantee your files and pictures won't be lost due to some error? | Technology | explainlikeimfive | {
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"They make at least 3 copies of your data, stored on different devices. If one device breaks, they replace it and make a new copy of your data from the surviving copies."
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97so0y | I understand that WhatsApp messages are encrypted before leaving your phone and decrypted on the recipient's phone with a unique key. But what stops WhatsApp servers from getting these keys and doing the decryption themselves? | Technology | explainlikeimfive | {
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"Absolutely nothing, in fact they do process your conversations, think of a product that you don’t need right now and type it a few times in WhatsApp chat, you’ll be spammed with ads about that product everywhere in the digital space Privacy doesn’t exist, careful about what you say"
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97ttdz | How is a free mobile app, that has neither in-app purchases nor ads, generating ROI for the company developing it? (e.g. "Zero", a fasting app available in the iTunes store) | Technology | explainlikeimfive | {
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"Data. They are likely gathering personal information on you and your habits, which can be turned around and sold.",
"Two things: \\-Someone could have simply made the app for fun or to share a useful tool, with no goals of profiting in mind \\-Investors want to focus on growing the userbase as large as possible before making changes to the app to make it profitable. You see this with a lot of tech companies today. For example, Snapchat has been operating at a loss for its entire existence but investors are still buying into the company because they believe it will be profitable in the future. EDIT: Three things: \\-\"If you aren't the customer, you're the product.\" They could be going the facebook route of collecting user data to sell to advertisers but I'm not familiar with this app so I have no idea. Looking at the developer's [Medium post]( URL_0 ) on the topic it looks like he just wanted to make a tool to help people fast. It's basically just a timer so the only money he's really losing here is his own (small) development labor cost and app store publishing."
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97wzfv | What is the difference between string and char, and when to use each? (C and C++) | Technology | explainlikeimfive | {
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"char is a single letter, string is an array of chars. That’s basically what it breaks down to. chars can also store small numbers, and while strings hypothetically could store small number arrays there would be better options like just using an array of chars. Also chars use single quotes in C/C++ while strings use double quotes."
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97yjkj | how does software interface/communicate with hardware? | I do not know if this is too broad of a question, but any explanation would be appreciated. | Technology | explainlikeimfive | {
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"lots and lots and *lots* of layers of abstraction. At the \"bare metal\" layer, you have electrical circuits that can either produce an \"on\" (1) or \"off\" (0) signal based on what signal it gets in. These are called *logic gates* and if you've played with Minecraft's redstone circuit system you may be familiar with some basic logic gates. Once you have predictable logic gate behavior, you can use certain inputs to produce certain desired outputs consistently. These strings of 1's and 0's can then be used in a sort of code to represent other things, like an instruction to pass a sequence of 1's and 0's over to another part of the computer. Once you have that standardized, you can write in more than 1's and 0's, and have a very low-level abstraction of certain functions; this is called *assembly* and it is the \"lowest level\" that is typically worked on by most people with the mantle \"programmer\"; assembly are basic instructions given to a computer that tell it what to do with data in it's memory registers; if it is connected to other things like RAM, it can push and pull data from those, and if it's connected to something like a monitor, it can send data to that. Then there are encodings written for the monitor so that it knows that when it gets a particular string of binary, it should display the character \"A\" on screen, for instance. Once you have built up a lot of assembly code, you will realize that you have a lot of functions that you use a lot. This is where programming languages come in: they have standardized libraries of the more useful instructions for computers to perform, and create more English-looking language for the computer to then turn into machine code using what's called a *compiler*; when you run a .exe on your machine, what's happened is that the code written for that program was run through a compiler, and the .exe is the output machine-language file that can be run through your operating system. This process of building up useful small functions just *keeps happening* across computers; the C language got so big that someone took a bunch of standard solutions to common computing tasks into a big library and launched C++ (++ is a programming shortcut that you append to a variable name [using x here] to write out x=x+1 with fewer keystrokes). At the end, it's layers upon layers of pre-determined rules that boil down to what inputs to send to the processor so that it can open the correct circuits the correct way to then trigger rules in the other parts of your computer to do whatever it is you're trying to do. I recommend [this series]( URL_0 ) if you want a more in-depth idea of how each level works."
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97z67b | How do those Dyson blade less fans work! | Technology | explainlikeimfive | {
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"They're not actually bladeless, just the blades are in a different location. They're actually at the bottom, sucking air in.",
"There's an actual rotating fan mechanism hidden in the base. It drives air up a tube, and out the front of the mysterious-looking circular vent."
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981gu5 | How did people map the world before satelites? | Technology | explainlikeimfive | {
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"Cartographers, surveyors and mappers. They would sail around and hand draw the landscape. They would traverse the land with a length of chain and measure distances. They also had specialized tools such as a sextant that could help determine their place in the world based on where the stars were at that time of year vs where they should be.",
"Cartography, or the study and practice of making maps, has been used since the 6th century B.C.E. while somewhat crude and not necessarily 100% accurate, these maps helped build roads, forge nations, and cross the Atlantic. Humans have been sailing for a long time and people began using their knowledge of geometry and astronomy to map the seas. On foot, map-making has been fairly accurate from the beginning because it's easy enough to determine walking distances.",
"You sail a boat along the shore line and draw what you see and you get a local map. Glue all the local maps together and you have a global map of shorelines.",
"The simple version is that they would pick a point (a tall hill for example) and transform what they saw into a map. Then they would move on to a new point and repeat the process - eventually you have a whole array of small maps, and can then combine them into one big one. Remember as well that they were not working to the level of accuracy we have now - early maps would have been as simple as showing where the settlements and rivers are in relation to each other, so crude but functional for navigating by. When they were first mapping the globe the exact geography of the Americas was irrelevant when the big discovery was finding the continent in the first place. As has continued our abilities have grown alongside the accuracy of our maps - what was initially a sketch by eye became a survey by theodolite and other tools, which has become satellite imagery and GPS mapping."
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981z7w | Why website extension name have different prices | Technology | explainlikeimfive | {
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"Because the different TLDs (Top Level Domains) are administered by different organizations. The basic country specific TLDs like .fr or .jp or .de are administered by organizations in those countries often have limits that mean only residents can buy those addresses and often are designed to be cheap to help drive that whole internet economy thing. .makeup on the other hand is administered by L'Oréal in hopes of helping the marketing PR and advertisements of their own products. The amount of money it cost to register a domain name in that TLD is easily payable for big players like themselves but out of reach of smaller ones, so the pricing keeps out the rifff-raff."
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982ce7 | How can a phone with no reception still make emergency calls? | Technology | explainlikeimfive | {
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"With absolutely no reception, it can't. With no reception of _your_ provider's network, but with of other networks, obviously it can.",
"It can use other carriers in the area. They have it set up so those always go through. If you have actually no reception, no nearby cell towers at all, then it will not go through.",
"Your phone displays no reception if it can't reach the network *your carrier* provides. If there are other networks available, those will allow an emergency call through. If there are no networks available, you're boned."
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986mcg | How are swords forged? | Technology | explainlikeimfive | {
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"You take a chunk of metal, heat it up, and beat it with a hammer until it's nice and flat. Than you cool it, and sharpen it in a sharpening wheel.",
"Metal is super heated --- > molded into a certain shape --- > super heated again and hammered to create shaft and further form the blade--- > dunked in oil... repeat last two steps until it looks how it should. --- > sharpen using a whet stone and make it nice and sharp. --- > make a handle so you don't only hold a small metal rectangular prism. --- > make a sheath so you don't hurt your self---- > kill your mentor and take over the 9th infantry battalion."
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9891yh | Why do you have to eject a usb drive before yanking it out? | Technology | explainlikeimfive | {
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"For the same reason you can easily step out of a parked car, but would have a less fun time stepping out of a car going full speed down a highway",
"I may have found yer answer, matey. Yer not alone in askin', and kind strangers have explained: 1. [ELI5:Why do computers insist that we \"safely\" eject USB drives? ]( URL_0 ) ^(_ > 100 comments_) 1. [ELI5: Why do I have to eject an external disk before unplugging it? ]( URL_4 ) ^(_ > 100 comments_) 1. [ELI5: why do you have to \"eject\" USB drives before removing them from your computer? ]( URL_3 ) ^(_9 comments_) 1. [ELI5: What exactly happens when I click on \"Safely Eject\" for a USB or external hard drive? ]( URL_2 ) ^(_40 comments_) 1. [Is it harmful to directly remove an external hard disk from your computer without \"ejecting\" it first? ]( URL_6 ) ^(_15 comments_) 1. [ELI5: Why is it bad to remove a flash drive (or similar) from your computer without 'ejecting' it first? ]( URL_1 ) ^(_9 comments_) 1. [ELI5:Why do I need to eject my usb before I remove it? ]( URL_5 ) ^(_4 comments_)",
"Ejecting makes sure there isn't anything being transferred between the computer and the USB drive and tries to make sure no new transfers will start If you yank out the drive while something is being written to or read from it, the file, and possibly the drive, could become corrupted."
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989wp7 | How does CUDA or OpenCL work in GPU based password cracking implementation for cyber forensic applications and what is the difference between them? How is this benchmarked? | Technology | explainlikeimfive | {
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"> How does CUDA or OpenCL work in GPU based password cracking implementation for cyber forensic applications Not all that different than a CPU. A GPU is essentially the same as CPU, just with many thousands of cores (compared to the ~4-8 you might see on a CPU). This means you can run many many operations at the same time, as long as they don't depend on each other (if they do depend on each other, you have to wait for the previous one to finish, so most of the cores will just sit idle). Something like guessing passwords are independent, so you can have each core doing different guesses. This can let you get to obscene amounts (in the billions per seconds) of tries. With that many tries, you can brute force some stuff. These often aren't necessarily super informative, because you generally need some kind of direct access to whatever you're trying to crack (there is a reason most sites have a limit on attempts. Even if you could theoretically crack the passwords, if you're only allowed 10 guesses/hr instead of billions/sec, it's essentially a moot point). However if you were able to say, download a giant password database locally to your computer, you can play around with it and potentially brute force it. > what is the difference between them? They're more or less the same thing- software/libraries for running GPU operations. Both are derivatives of C/C++. It's not all that different than the normal kernel running your CPU- just specialized to be efficient for thousands of cores (ie, transfering data to those cores can be a lot trickier than just communicating with 1 core, or making sure there's no conflicts etc). CUDA is proprietary- it's owned/developed by Nvidia. In general CUDA tends to be faster/more standard for most general GPU applications, but it has the big con that it's closed source and only works on Nvidia cards. But NVidia throws a pretty decent amount of money at developing it, and it was available early, so it's hard to get away from Open CL is open source version of essentially the same thing. It's designed to work on most hardware (and even can default to using a CPU if a GPU isn't available for some reason). So it's a lot more flexible, although generically it can be a bit less efficient. OpenCL/GL is getting better and better though. > How is this benchmarked? I don't know the specific benchmarks offhand, but in general, the way you do a benchmark is to find a few \"standard\" problems and just run them and time it. (Hashcat seems pretty popular) It's important to have problems of different types to identify *where* the differences are. There are a lot of password cracking algorithms (for example, there's just plain brute forces, vs dictionary attacks, etc), as well as different encryption algorithms (WPA,SHA etc)"
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989yev | why and/or how does internet data usage (by my home internet connection for example) cost internet service providers money? | Or is it just something they use to leverage more money out of people? EDIT: To clarify, I totally understand there's a whole lot of costs associated with connectivity and staff and skills and equipment and electricity. But why is data the precious digital commodity that can largely determine the cost of internet and phone plans? | Technology | explainlikeimfive | {
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"While you might not see it day to day, they have to pay to maintain the infrastructure, lay the cables, produce the hardware, give you an IP address. There are lots of pieces of the package which we don’t have in our homes but is required to get you online, and it costs money - these charges are passed to you, plus a significant margin. ☺️",
"Because data represents your share of the bandwidth available. You may pay for 10mbit for example but you're not necessarily paying for 10mbit 24/7 (data usage equivalent to approx 3.2TB / mo). Let's say you have an ADSL link, for arguments sake, and let's say that due to the quality of the copper in the ground and the length of the cable back to the DSLAM you are able to sync at 10mbps. Now you say, why can't I just download at 10mbps all month long and data use not be a factor? The answer is that there is not a 1:1 contention ratio from that DSLAM back to the core of your ISPs network and beyond. If you wanted a guaranteed 10mbps from your house to the ISPs handoff (or all of their hand offs for that matter) it would cost you more than most people could afford in a month. The solution? Oversubscribe. You have 10mbps and so do 200 other people in your neighborhood but the ISP only has a 20Mbit link back to the rest of their network. So in this case you have a 1:100 contention ratio. Now if two people were to use their full 10mbps all month long, nobody else in your neighborhood would be able to use the network very well and would complain. Hence bandwidth is a scarce resource. The solution? Cap your speed, or limit your usage. Most people would prefer their speed be good when they want it and have a data allocation, to prevent them hammering the network 24/7, rather than have a realistic speed cap placed on them that allows unlimited usage. Some of this is historical, and these days, in many countries/areas, the networks have enough of a buffer built in to them, and people are generally accepting enough of fairly significant swings in their download speeds, that unlimited connections are becoming more common. This only works if the proportion of people who abuse the network is below a certain threshold though. If everyone downloaded at max speed 24/7 we would all still suffer."
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98e208 | Why do phone touchscreens react to skin and water but not to metal and other conductors? | Technology | explainlikeimfive | {
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"A touchscreen will work with any conductor, but there needs to be a large enough surface area touching the screen to make it work. Try touching a fingertip-sized piece of metal to the screen.",
"They actually do, but the phone filters touch input (Edit: Based on size) in software to prevent accidental inputs.",
"Phone screens sense changes in capacitance, not conductance. Most metal, although good conductors, have little capacitance. Basically there are conductive wires within the screen that are supplied a voltage that is constantly changing. When something like a finger or other capacitive material gets close it will absorb some of the power as the voltage increases and emit some back into the screen as the voltage decreases. The phone will see the changes in the voltage waveform and interprets them as a user input.",
"Capacitors in the touchscreen are activated by an electrical signal between your fingers and the touchscreen. Charging the capacitors via touch creates a response on the screen, but this charging cannot be done in the presence of water, gloves, etc., due to their interference between the screen and your finger. Edit: I should probably expand a bit. This is specifically in reference to capacitive touchscreens; resistive touchscreens work via electrical current as well, but the force exerted by your finger on the screen is what causes its response (these are commonly found in grocery store checkouts and ATMs). I figured your question pertained moreso to phone touchscreens and the like. Also, this explanation doesn't get into the nitty-gritty of capacitor function since its an ELI5, but basically the electricity from your finger (or really, any source with an electrical current) completes an electric circuit in the touchscreen and generates a response at that part of the screen.",
"How come I can use my iPhone while wearing rubber coated gardening gloves then?",
"[(Here's how I think this works) Excuse my paint skills, but yellow is your finger and red is a pencil or a metal rod. The little black dots are the touch detectors.]( URL_0 ) These detectors are invisible to the eye, but are embedded in your screen.",
"ELI5: There are invisible pixies in the phone and when you touch it, it makes a special hole for the pixies to fly away. It only works if the hole is big enough though, and the thing touching it is big enough and pixie compatible. This is why a pen or large piece of wood won't work. The pen is too small, even if there is metal on the outside, and wood isn't pixie comparable. More technical: It's about capacitance. Your body is a large slightly conductive object and thus it can act roughly as a ground. When you touch the screen your finger makes a small circle against the glass and forms a weak capacitor. This roughly \"shorts\" the voltage in the screen to \"ground\" (your body). And sensors in the screen can detect the coordinates of the short. Any sufficiently large, mildly conduct, object that can get surface area tight against the screen will work.",
"While we're on the subject, how come my phone responds better to my touch when I'm holding it, versus when it's just sitting on the table and I try to use it with one finger, not holding it? When it's just on the table, it seems somewhat glitchy.",
"The first Apple iPhone screens reacted by picking up the electric charge from potassium in your skin. They would also react to a banana peel.",
"My charge cord annoys me because it trigger the touch when it hits the screen. So other conductors definitely activate it.",
"If surface area is important, how doea the Note pen work?",
"Corollary, if they react to skin and water, why do they not react to a wet finger?"
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98glpd | When a song is remastered, what are they actually changing about said song to make it sound better? | Technology | explainlikeimfive | {
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"If the original master tapes were stored properly, then the first big difference is in the fidelity of the release. Modern digital (and even vinyl) mediums have much lower noise, distortion, and better frequency response than old vinyl pressing techniques. This means you have a more truthful capture of the original recordings on the rerelease. If you listen to modern remasters of recordings from before the mid-late 60s, the difference is just staggering versus surviving vinyl copies. Sometimes remastering will involve processing the old master. It's hard to point to specific techniques because every remaster is going to be different. But there are some things we can do today that would be simply magic to the original mastering engineers, for example removing noise and unwanted sounds (back in the day if there was a mistake, it stayed there forever). Sometimes you'll wind up with remixed records. The difference is a remix takes the original tracks (could be 4, 8, 16, whatever) and recombines them, whereas a remaster will only take the original mix of those tracks. A remix can be done for a couple reasons. A big one is stereo. Before the mid-late 60s, almost all records were mono (single channel, one speaker). Some of the early stereo mixes are straight trash too (listen to the Beatle's Rubber Soul in stereo, its disconcerting). So what we can do today is use some fancy techniques and tools to recombine the original tracks and mix them to two channels for stereo, to make the mix more balanced. Sometimes there's a monetary component. A remaster is a great way to make money off something twice. There's also some records that are famously terrible, like Metallica's Death Magnetic, and some of Led Zeppelin's early work, and a remaster is an attempt to fix the original mistakes. It doesn't always work. Sometimes musicians are just perfectionists and are always trying to improve their records. Edit: there's also a field called \"forensic\" audio that borders on magic. For example, we have recovered recordings of Thomas Edison and Teddy Roosevelt from wax cylinder recordings using modern digital technology. One famous example of this as \"remastering\" tool was to recover a recording of a Castrato opera singer (a castrated man trained to sing a particular range, you don't see them around anymore obviously).",
"Amateur musician and producer here. Imagine we are in a crowded restaurant and trying to listen to the conversations around us. Everyone is talking at the same time, and so it's hard to make out what everyone is saying. Some people talk louder than others and we can hear them better, but that also makes it harder to hear people who are talking more quietly. Some voices are high pitched and stand out and are easier to hear if the majority of the other voices are lower in pitch. The same with lower pitched voices. So in order to hear audio detail as greatly as possible, we need to control how loud a sound is, what pitch or frequencies it's using, and balance these against all the other sounds that will be heard. This is what a recording and mixing engineer does. There are many tools at their disposal for doing this. Compressors take loud sounds and soft sounds, and make them closer to the same loudness, quieting loud ones, and turning up the volume on soft ones. Equalizers and filters can change which frequencies an instrument or track is using, so that for instance your bass guitar, and your piano player aren't fighting for the same 200hz frequency of audio. You add a low pass filter on the bass so it's sound stops at 140hz, and you apply a high pass filter to the piano, so it's lowest notes stop at 140hz. Thus giving each instrument a little more room to exist in the mix. When a track is re-mixed they basically take that process of matching sounds to each other, and changing their loudness, frequency, etc and re-balance them. The average loudness of the track is determined by dynamic compression, which is the difference between the softest sound and loudest. Over time peoples tastes have grown to higher average listening volume, or more dynamic compression. So often when a classic album is re-mastered, they apply more dynamic compression to make the over all loudness of the track greater. Sometimes new technology comes along after an album is released and allows a person to clean up or repair a less than ideal master recording, making a better sounding new master. For instance many of the original Beatles recordings had a limited number of tracks to work with, and they were recorded to analog tape. They would take a group of instruments on separate tracks and bounce them down to a single track, do that several more times and then bounce all of those down to yet another bounced track. So the master recording may have artifacts like tape hiss, limited dynamic range, the recording levels had to be very high in order to improve signal to noise. The actual remastering process takes these original recordings and moves them to a new medium like digital storage, similar to transferring a movie from film stock to DVD or Bluray. They may be able to remove noise and other artifacts from the original recording, improve it's dynamic range by changing compression to re-expand it. Etc. If you want to hear a good comparison, listen to these 2 different versions of the same song by Geographer. Listen especially to how the drums sound different. It's the same instruments, but how loud they are, their EQ curve, and the amount of compression applied were changed making some instruments more easy to hear, and others more blended. [Kites original version]( URL_1 ) No reverb on the primary melody. Drums have a lot of reverb, low compression, and are very loud in the mix. [Kites Remastered]( URL_0 ) Convoluting Reverb added to primary melody. Drums have had dynamic compression turned up, high pass filter to remove bass from kick drum, re-EQ'd to sound tighter, reverb lowered and gated to sound cleaner and faster attack. Over all volume of drums is lower. Piano was brought up in the mix to be heard better."
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98gscv | If director’s like Christopher Nolan and Quentin Tatentino insist on using film instead of digital, how are they able to use special effects? | Technology | explainlikeimfive | {
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"They just shoot with film and convert it to digital for everything that happens during post production (which includes VFX). Nothing stays on film for the entire production cycle anymore."
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98humb | How can two ISPs in the same city start with the same prefix? | Why can an IP address from both CenturyLink and Xfinity both start with the same number? (174 in my example). A CenturyLink IP here in Albuquerque can start with ([ URL_1 ]( URL_0 )) and my Xfinity IP also starts with ([ URL_1 ]( URL_0 )). Why is this? I thought they both had to be different considering they're different ISPs. | Technology | explainlikeimfive | {
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"It's not really correct to think of the 174.x.x.x as a prefix - it just happens to be the first part of the number, but doesn't really mean anything. An IP address is a 32 digit binary number, but for the sake of making it a bit more human friendly we chunk it up in four three digit numbers separated by dots. The range you've mentioned, in binary, looks like 10101110000000000000000000000000 through 10101110111111111111111111111111 - you can have any combination between those two. How many combinations is that? 16,777,216 that's how many. (OK, there's actually a few in there that we can't use for technical reasons, but it's still quite a big number) If you were to allocate a single block to a single ISP, then you'd be giving them nearly 17 million IP addresses, all to themselves. Once you've allocated that block, it makes it unavailable for everyone else. Instead, we chunk the block up a bit more finely. Even if we give you ISP 174.1.x.x then that's 65,536 IPs. Maybe they'd start with that one block when they were a young fledgling ISP with not many subscribers, but as they expanded they'd request some other blocks and end up with something completely different - they might get give the 214.6.x.x block instead - it would make things marginally trickier from their side, but by no means impossible. In terms of the internet as a whole though, it's far better to only give people the IP addresses they actually need instead of doling out massive ranges that most ISPs could never fill.",
"Check the netmasks to figure how big the IP range you're sitting in is. Not all ISPs have class-A IP ranges (AKA a /8). An ISP doesn't even need to maintain everything in a contiguous block. [Here's a list that Comcast posted listing their IP ranges). Apparently you're looking at Xfinity addresses in 174.48.0.0/12. Centurylink doesn't seem to publish their ranges but they've got a bunch 174.124.x.x and 174.125.x.x stuff."
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98iedm | Sometimes in video games and in video game glitches the characters will all of a sudden fling up into the sky at a thousand miles per hour. If games attempt to stimulate mass and physics, what are they getting so wrong that causes this to happen so regularly in video games? | Technology | explainlikeimfive | {
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"Divide by zero errors or an overflow error or clipping errors. Sometimes what can happen is something will push your character out of bounds and the physics engine try to correct by moving you back in bounds as quickly as possible. But now maybe your clipping into another object so the physics there pushes you back and they kind of tug of war between the two objects. It's possible that each push from either object is giving you inertia because the character is \"moving\" even if it's just vibrating between two objects. When you are suddenly dislodged all the inertia can send you flying into low earth orbit. Same thing can happen with objects two objects. See tank flipping in halo one. The first tank is forced through the second one causing their physics to interact in an unpredictable fashion.",
"There's a variety of causes but sometimes the physics computation gets bad data as input. Under the hood physics engines are basically just math formulas. Games are dynamic and it's impossible to account for every single combination of things the player does or anything else that might happen. So sometimes the game will give the physics engine numbers that are too big or too small, etc and weird stuff happens as a result.",
"Game physics are really really rough approximations of actual physics. Good realistic physics generally just cannot be calculated fast enough to keep up with real time game play, especially considering all of the other stuff that the computer needs to calculate each frame (graphics/AI/sound/etc). So physics engines in games take a ton of different shortcuts to make things run acceptably fast. And one of the results of substituting speed for accuracy is that you can end up with some really weird edge cases that the system just doesn't deal with well. Just as a general example, a huge portion of physics in games is collision detection. Figuring out when objects are touching each other or intersecting. Generally games will check for this at some sort of fixed rate (say 30 times per second or whatever), but depending on what is going on in the game, objects could intersect in between those checks (sometimes referred to as 'ticks'). If an object was moving fast enough, by the time the engine checks to see if it's hit a wall or whatever, the object may have actually moved far enough to be in a position well inside the wall. In real life, the object would've started hitting that wall at some specific point in time, but in the game engine that collision can only start during one of the physics ticks. So by the time that next physics tick comes around and it sees the collision, the position of that moving object is now well inside the wall. The physics engine knows that the two objects shouldn't be interacting, but it doesn't really have a way to 'realistically' separate them, because that's a behavior that couldn't actually happen in real life. So sometimes weird things happen like objects getting ejected at ridiculous speeds at random directions as the physics system tries to cope with situations that weren't ever really planned for. Game developers can do various things to try to minimize these sorts of occurrences. For example, if performance allows, you might increase the rate at which the physics engine checks for collisions. Some times objects are given collision shapes that are significantly larger than the actual rendered object, so that their collisions with other objects are likely to be detected sooner. And so on. But there's just only so much you can predict and plan for, and once thousands of players start messing around your game, they're going to stumble across lots of edge cases that you never got around to fixing or even predicting."
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98if90 | How does humidifier work? | Technology | explainlikeimfive | {
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"So unlike boiling water where you have to heat the water to make it vaporize, humidifiers work differently. What happens is there is an item inside the humidifier called a wick. The wick is almost like a sponge the just soaks up water. When you turn the humidifier on it sucks in air and blows it through the wick. Small warm particles of water are grabbed by the moving error and are sent through the air."
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|
98janl | Super Capacitors and other power sources. | I've been trying to find a basic explaination for how these things work, but havent been successful yet. How do they differ from typical capacitors? Where do they make sense to use? Pros and Cons? | Technology | explainlikeimfive | {
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"e4gfvp2"
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"text": [
"A super capacitor isn't really a power source instead it is a method of storing energy on a temporary basis, a bit like a rechargeable battery."
],
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98jbd5 | Why do some whetstones need water, oil and some work dry? | Technology | explainlikeimfive | {
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"text": [
"to understand, you need to know how a blade wears down. when a blade cuts into something, the leading edge deforms. this can result in blunting (the metal squashes), chipping (where pieces of the metal break off), or warping (the edge bends) warping is fixed by *honing*, which primarily just pushes the metal back into place. while lubrication can make this a smoother process, it's not really required. if you've ever seen a barber run his blade over a piece of leather (called a strop), that's what he's doing. (somewhat of a tangent, razorblades are so fine that the edges bend easily, and shouldn't be subjected to the harshness of stone, which is why they use leather) chipping and blunting are fixed by removing material, the same way you would buff out a scratch in a piece of wood. stones meant to do this need the liquid to carry the removed material away. otherwise the metal will just be stuck on the stone and will keep the stone from biting the metal. that said, most stones *can* work dry, just not as well.",
"Usually whetstones that are for really sharp edges work with water or oil, this is because the edge will take off small parts of whetstone and form an abrasive paste that ensures even material take-off."
],
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98jcs8 | Why Did Gran Turismo on PS1 look so good but other games looked terrible retrospectively | Technology | explainlikeimfive | {
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"text": [
"It’s all about time and experience. GT was the third racing game the company developed and care out over 2 years after PS1 was released so they knew how they were able to get more out of the console. You’ll see similar outcomes with franchises when you compare the first on a console to the last. Yes, GT wasn’t the last but they put enough time into developing and into gaining experience with the other games that it all had an impact.",
"Cars are a lot easier to model than i.e. humans. They have a lot of features that are easy to represent with few polygons, unlike, say, a human face, or even a dog. If you can get away with fewer polygons on all the cars, you save a lot of processing power that can be spent on other graphical effects. For example, a car's rear spoiler can be represented much more accurately with two polygons than a human ear can."
],
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98lpe8 | Why do airplanes needs a high and low pressure air system for lift instead of just using an inclined plane? | Airplane wings can generate lift even when they are parallel to the direction of movement due to their high and low pressure sides generating lift. This was pioneered by the Wright Brothers (I believe). If you take any piece of hard material and angle it in wind, it will generate lift, so what was so revolutionary / what was the need for this high and low air pressure system? An addendum to this would be: Why are the front sides of wings rounded instead of sharp? | Technology | explainlikeimfive | {
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"text": [
"You've got 4 forces that are in play with an airplane and they come in pairs Drag and Thrust Weight and Lift You can get more lift out of an airplane wing by tilting it upwards but you will also significantly increase the drag which means you'll require more thrust to maintain your speed. Most planes don't have crazy strong engines relative to their weight and would prefer to rely on lift from the pressure differential rather than lift from angle of attack which will significantly cut into their speed or fuel economy Planes that do have a powerful engine compared to their weight don't particularly care. This is why stunt planes can fly upside down for extended periods of time or why fighter jets can stand upright on their tail. If you've got enough thrust you can trade it for lift, but if you're trying to be efficient then you want to minimize drag as much as possible.",
"There is more drag in the \"high attack angle\" configuration. That's the aircraft term for what you are describing. Drag means bigger engines and lower fuel economy. Engineering an airplane is all about optimizations.",
"That stuff you learned in school about high and low pressure on opposite sides of the wing is largely crap. As you observed, any inclined plane will generate lift. What the shape of the wing does is generate a little bit more lift, which was important back in the day when engines were barely powerful enough to get an airplane off the ground. Most planes continue to do this because you get more lift for free and there really is no reason not do it. However, planes that need to operate at odd orientations, like stunt planes and fighter jets, will often have more neutral wing shapes and rely on a stronger engine for lift.",
"There's only so much lift you can get from a wing per unit of power so in the context of the first planes a flat wing just wasn't good enough to make planes fly given the available tech. And after that, let me turn your question: why using a flat plane when you know there's something better? Flat planes have a low Lift to Drag ratio, stall early (further limiting the range of angles since not only it needs a minimum angle but also has a low maximum angle) and the maximum lift coefficient isn't high, so they're good for nothing whatever the focus of the plane is. They don't necessarily simplify the structure either given that you need a bigger wing to achieve the same result."
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98m5ie | Why do leds light up instantly while incandescent bulbs turn on with a fade | Technology | explainlikeimfive | {
"a_id": [
"e4h1ay1",
"e4h4zng"
],
"text": [
"Incandescent bulbs use Tungsten filament which emits light at high temperature. The electric current heats up the filament and it takes a second for that to happen. Once heated up, it emits light.",
"And why are LEDs instantaneous? Because the current through an LED knocks loosely bound electrons away from their atoms, and in order to fall back to their lower energy state they have to emit a photon to dump the energy. Because this effect is only due to the presence of current, and not due to incandescent heat, it starts emitting as soon as current starts flowing."
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|
98nmsr | How does a coal burning engine work? | Technology | explainlikeimfive | {
"a_id": [
"e4hdu5h",
"e4hd7zt"
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"text": [
"One I can actually answer! Coal burning engines are better known as steam engines. Most people associate these with steam locomotives but there is a difference. Basically a steam locomotive is a steam engine on wheels. A steam engine works like a giant tea kettle. The part where the coal is, is called the fire box. The coal is burned here (much like in a charcoal BBQ) the heat that is produced by the coal is used to head up a large container of water once that water gets hot enough it creates steam. That steam is then used to move a piston back and forth by putting fresh hot steam on alternating sides, the new steam is always put on the side of the piston that is closest to the wall of the cylinder (what the piston is inside) because when hot steam is put into a small space it wants to spread out and cool down because it doesn't like being hot. Because the steam expands it forces the piston back against the other side of the cylinder (and the old steam that was on the other side is pushed out through a different hole then it came in). The piston is attached to a bar or lever which is then attached to a wheel of some kind and the action of both the piston and the bar spin the wheel. Thus creating the motion. A very simple steam engine looks like . (keep in mind the firebox and water tank are not shown) If you want an ELI5 of steam locomotives I can give that too. Source: Currently studying to become a steam locomotive operating engineer (read repairman) and 7 years of experience as a Conductor at a steam locomotive Railroad.",
"They are to my knowledge steam engines. The coal is burned and heats water and the steam from that is used to drive pistons in and out."
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|
98q4n3 | What do the numbers on a photo on your phone mean? Do they serve any function? | Technology | explainlikeimfive | {
"a_id": [
"e4hxydd"
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"text": [
"I'm not 100% sure what you're referring to, but I think you might mean the filename; typically it takes the current date and time and appends it to a predetermined name, so that every time you save a picture you don't have to type in a file name that the system knows it as."
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98rkv7 | Why is the pixel density(pixels per inch) of most smartphones better than laptops? | Technology | explainlikeimfive | {
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"e4i8c2x",
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"text": [
"A smaller screen with the same amount of pixels have a higher density. On a phone can you need a higher density just because they are smaller, and a smaller device is usually held closer to the face.",
"Ultimately screens are designed for their intended viewing distance. They are manufactured to have the best pixel density possible for the target audience. The smaller a pixel is, the more expensive it is to create. Manufacturers are trying to make as much money as possible so they will make a product that provides acceptable performance that a lot of people will buy. They try to make this product for as cheap as possible, because people also base their purchasing decisions on price. You hold a smartphone closer to your eyes than you view your laptop, so the laptop does not require as high of a pixel density to be considered acceptable (high end displays are available of course, but carry a larger price tag). Think about any jumbo screens you have seen at a football stadium, these only have a couple hundred pixels per square foot! Which is perfectly fine when you are viewing them from hundreds of feet away, but if you had the same pixel density on your phone screen you wouldn't be able to do much at all."
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|
98ugdk | How did Google know I was playing Civ 5? | Technology | explainlikeimfive | {
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"e4ir4g7",
"e4iumh6"
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"text": [
"\"Closing\" Chrome doesn't actually end the Chrome process, unless you change a certain checkbox in Chrome settings. Google was able to track you because the Chrome process was still running.",
"If you hadn't fired up Civ 5 saturday morning, would you have paid attention to the news story about a new Civ 5 mod? It's likely that Google didn't know you played Civ 5, but just showed you the news story regardless, but because you had recently played the game, you now noticed the story."
],
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14,
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|
98wgdo | - no viruses for linux? | Allegedly there are no computer viruses for linux based operating systems / computers. Is that true? Why? | Technology | explainlikeimfive | {
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"text": [
"Lack of users, plus a well informed user base. If you're a virus maker, which are you going to write viruses for? Windows 10, with over 400 million install, many of them by people who dont really know how to be secure properly, or Linux, with somewhere between 8 and 25 million installs, most by people with SOME IT background or knowledge?",
"Well. That ain’t true. There are viruses for Linux-based operating systems. They are often a lot less efficient then they are on a windows machine because the operating system is better locked down. But that is not certain either, so it’s more a feeling than any kind of truth. Linux users are often more technical. Knowledgeable. Aware of risks. And as a result, more keen on getting all the latest security patches as soon as they become available. And that is what does it. That you try as best you can to not become a target. Because it’s always easier to attack the one who doesn’t bother than the one who constantly tries to stay safe. Linux systems used to be virus free once, but that was only true as long as the system wasn’t particular widespread. Say, mid 1990’s or so. Because once there are a lot of machines available, they are more worth as a target. Trying to attack an obscure system that is ran by someone who is very good at what he is doing and constantly pays attention, that takes a lot more effort than just managing to get control over a few thousand poorly configured standardised installations that the owner doesn’t really know how to use.",
"Its not. Theres less viruses in Unix world, in part due to design, but also become less market for virus writers to exploit. There's less incentive in writing a virus to steal bank passwords when it only works on less than 1% of end users."
],
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98wv0x | Why can certain videos look higher definition than real life | Technology | explainlikeimfive | {
"a_id": [
"e4jbkm4",
"e4jb5sb"
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"text": [
"It's not the fact that the image appears HIGHER RESOLUTION, but that areas in a photo or video are unnaturally well lighted or in focus, for example. Why can they be that way? Because camera lenses and various image processing, postprocessing techniques do not work the same way the human eyes and brain work to form images.",
"I honestly don't know what you mean. This actually happens to me, but it's because I need glasses."
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98yd83 | Hearing Aids | How do hearing aids improve one’s poor sense of sound? | Technology | explainlikeimfive | {
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"e4jn60f"
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"text": [
"They are custom programmed to amplify the frequencies of sound (usually high pitch) in which the wearer has lost. If the hearing loss is too profound, bone anchored hearing aids or cochlear implants transmit the auditory vibrations without using the ear drum."
],
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991jfh | Why can we make 911 calls literally anywhere regardless of service but can't make regular calls? | Technology | explainlikeimfive | {
"a_id": [
"e4k8hkr",
"e4kgvii"
],
"text": [
"The simple answer is that 911 calls are very, very important. So important, in fact, that all the cell providers have agreed with authorities to let any phone through that needs to make an emergency call. No matter if it's their customer or not. Because it's one of those times when who you are paying your bill to shouldn't really matter. Emergency is emergency, and that is that.",
"You can't, literally anywhere. If there is no network servicing the area, your phone can't create one out of thin air to call 911. However, if your phone can reach *any* network, they will allow 911 call through because it is expected to be *of an emergency nature.* You can't make regular calls this way, because the company owning the network wants you to pay for the service before using it."
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993a1a | Have we advanced enough in science to effectively harness the energy from thunderstorms?(if not what is the biggest hurdle) | Technology | explainlikeimfive | {
"a_id": [
"e4kjrol",
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"text": [
"The biggest hurdle is it simply isn't that practical, but it can be done. Lightning delivers a lot of energy in a short time, which makes it hard to store or route, and they occur in variable locations over variable timescales, which would make it difficult to build infrastructure to handle it. Beyond that, it simply doesn't provide all that much power relative to our other power generating technology. So basically, the biggest hurdle is \"there's no good reason to do so,\" with \"it would be rather difficult and costly\" coming in as a runner-up.",
"Define \"effectively\". The issue with thunderstorms is that we don't really know where they will be and they only exist for a few months out of the year in most places. Then on top of that, even though a lightning strike has a ton of power it last only a fraction of a second which makes it difficult to capture and store, so it's not really that much energy. Think of it like a fire hose, yea it can spray a ton of water but if it's only on for 1 second it's really not that much. To put that into perspective Wikipedia states that 1 lightning strike is about 5 billion joules of energy. A 60 watt light bulb over the course of a year takes 1,892,160,000, or nearly 2 billion joules. So basically 1 lightening strike could run less than 3 light bulbs for a year. It's not really worth the R & D to harness that. So could we harness it? Maybe, but to do it effectively in a way that makes economic sense isn't really feasible."
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994qz9 | How do bladeless fans work? | Technology | explainlikeimfive | {
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"Most of them aren't truly bladeless, just they hide the actual fan elements inside and then direct air flow out the top ring, usually pushing along more air with it as it exits.",
"If you’re talking about the Dyson Air Multiplier, the blades are in the tower. It pulls in a small volume of air, forces it out through the ring. This pulls in surrounding air along with it through inducement/entrainment.",
"The Dyson ones have a motor/blades in the tubular base that forces air up and out a small gap in the face of the unit.",
"For the ones that truly are bladeless, they tend to either use temperature differential (expanding heated air rises) or they use particle ionization (they create a charge in the particles in the air, the particles attract others, causing directional airflow). Usually we think of the temperature-based ones as heaters or air conditioners, and the ionizing ones don't push much volume. So in both cases, they're usually backed by a fan blade somewhere in the mechanism.",
"They're made of lies. The blades are in the base and air flows upward and out through angles slits"
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9954a9 | what is ray tracing? | I’ve been seeing this as a big deal on all sorts of GPUs specifically the nvidia 20 series. What is the big deal with this and is it a large advancement or is it mostly for marketing? | Technology | explainlikeimfive | {
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"Today games produce images through rasterization. The GPU works from the back of the image forward figuring out how each object is lit and which ones are blocked so the camera can't see them then tries to assign a value to each pixel on the screen based off what triangle is in that square. This has issues with lighting and shadows because any object not in the camera's view isn't considered for lighting and shadows(like a big fire on the side) Ray tracing comes in two modes. The one relevant for gaming is shooting a ray from each pixel back into the scene and tracking what it bounces off of until it reaches a light source. This gives better lighting and shadows. Movies will sometimes opt for the hard version of calculating rays coming out from the light sources, tracking what they bounce off, and when they hit the camera. This gives really good results but most rays don't make it to the camera so the performance isn't good Microsoft and Nvidia are planning to use it sparingly to improve shadows and reflection",
"To make a computer generated object more realistic looking, the computer has to account for how it is being lit by local light sources. Not only will it be lit directly, but also indirectly as light bounces off other objects. Figuring this out is called ray tracing, as you are computer paths of light between sources and objects. The more ray tracing you do, the more realistic the object looks. A Pixar-type CGI movie will use years, even decades of computation time to render its images, and ray tracing is a big part of that.",
"Programmers use algorithms to realistically mimic the properties of light as it interacts with objects in 3d space. Ray tracing dynamically adjusts the way lighting effects are rendered, taking into account the changes in object position and their relationship to any given light source. Because ray tracing is so processor intensive, it was most commonly employed while rendering high quality animation, such as CGI effects used in motion pictures. With the recent introduction of next gen graphics such as Nvidia's RTX series, there is the promise of real time ray tracing effects dramatically improving the graphical realism of video games.",
"It allows renders to be much more realistic and faster. For animation and some scientific applications it can greatly improve the speed. Many games have used cheats(like shadowed textures or not actually tracing light) to avoid Ray tracing so they can run faster. Nvidia has encouraged game developers to make new games that use the real ray tracing and patches for old games so they can use ray tracing as well. It will improve the quality of the images/frames on the screen. It may not necessarily increase the frames per second but should improve the quality of each frame. Edit: ray tracing is tracking light and how it bounces off objects in a 3D environment.",
"Imagine that your computer screen is a glass screen instead, and imagine there's an actual 3D scene on the other side of the glass. When you look at that scene, you see it. Why is that? It's because rays of light come from some sources (e.g., the sun or a lamp within the scene), bounce off some objects in the scene and then hit your eye. Your computer attempts to create the same effect. To do that, it needs to approximate the colors of the rays of light that would go towards your eye it if the scene was really where it pretends to be. The term \"raytracing\" is a broad term that covers multiple ways of doing those calculations. The easiest way to do this is to imagine going backwards: when doing the calculations you start from the eye, you go through a pixel on the screen, and you follow the ray (tracing its path, hence the name), bouncing off mirrors and such, until you find out which object with color it had to hit last on its way to your eye."
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