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90iip8 | Why would Apple want to make their own chips for Macs? What is wrong with using Intel chips? | Technology | explainlikeimfive | {
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"Part of it is that Intel is profiting from chips that Apple buys from them. *If they have the up-front money to invest* and technical skill to produce them as cheaply as Intel can, they can keep the money that would otherwise be profit for Intel. Intel chips also use the x86-64 architecture which has been the standard for decades for Windows, and over a decade for Macs. It’s highly flexible and powerful, but many of its features are overkill for day-to-day use and drive up cost and power consumption unnecessarily. This is why almost no phones use Intel chips. ARM-type designs, which can be produced by multiple companies to their own specifications, are **way** more power efficient. Another way to look at this is *if you’re limited by the amount of power available*... they can actually be more powerful. Considering Apple focuses their computer efforts in the laptop market, especially thin, portable laptops... that could make ARM based processors *better than Intel* for a lot of Macs, not only cheaper. These factors already make them very good for iPhones. Now, you need to significantly rewrite code to work on those CPUs at all, which is why portable Windows phones/tablets ARM CPUs perform worse-than-expected, and don’t run existing Windows software (which would have been the main advantage of a Windows phone compared to Android for example). It’s also why iPhones do not currently run Mac software, or visa-versa. But if Apple pulled this switch off well, took advantage of the performance potential ARM CPUs offer and make sure that plenty of software is available right away to make the computers useful— they could really make Macs *better* than they are now, especially in the area of making battery life better or trying to keep performance high without sacrificing battery life.",
"Quite simply the same reason why they are making their own X or Y of several other parts or even services all together. More control over the process. Less depended on other companies. Possibly lower costs (if not now then in the future)."
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90ij04 | What stops someone taking your open source software and selling it themselves? | For example, if I want to create a website that runs as a paid service (e.g. GitHub), what stops someone just running it on their own server and selling it themselves (potentially undercutting you)? I know there are various licenses like Apache, GPL and MIT, but they don't seem to say anything that would prevent this. | Technology | explainlikeimfive | {
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"If your license allows it then nothing stops them from doing so other than their own lack of desire.",
"Usually the fact that anyone looking to obtain that open source software is going to get it for free, because it's open source.",
"There are different open source licenses with different terms. So it is possible to prevent this with licenses but a lot of people would then not consider it a free license. But if someone takes your open source code and starts up a competing business they need something extra to get people to use their service instead. There are several examples where a company takes an open source code base and publishes it as their own charging money for support. However all the developers that knows the code and can deliver the best support is with the original company so you get a worse product then the original. And if the new company starts making changes then the original company can just take those changes for themselves. So if someone starts up a competitor to GitHub using their code then they may be cheaper but there will be lots of bugs in the service that they are unable to fix. And if they hire developers to fix those bugs then they have to charge as much as GitHub and these changes will also make their way over to GitHub so there is no longer any difference."
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90jq2k | Why can crackers crack game keys but not voucher codes like amazon vouchers? | Technology | explainlikeimfive | {
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"Crackers can crack game keys because the only check on the key lives on the game itself. It just has an algorithm that looks at a particular alphanumeric string and says \"Yup, legit key\" or \"Nope, not legit key\". Once you find the bit of code on the disk that does that check, you can reverse engineer it or disable it entirely. _Note that this is much more difficult to do now, because many games check your key against a server during play._ Amazon vouchers (or gift card for our Yankee contingent) actually verify the number against the _servers_ at Amazon, which contain a complete list of the legitimate keys. There is no formula to reverse engineer or bit of code to turn off here - you have to present an alphanumeric string that is actually in the database. Moreover, the particular voucher has to be _activated_ first - the store that sells it has to tell the database \"This card is active\". Once it is used, the database deactivates the card. So, even if you can guess one of the actual codes that exists on the server, you have a tiny time window where it might actually be active and have cash on it.",
"Software with a game key relies on a single check, done offline, to see if a code fit some secret pattern. It was fairly easy to either reverse engineer this code (giving you a keygen) or just patch the program to make it always pass (giving you a crack). Even if there's multiple checks involved, it's just more work. Something like an Amazon voucher, OTOH, *needs to be sent to Amazon*, a system you don't have any control over. They take that code and *check it against a database* of codes they know they've given out. They *should* be pretty much random but, even if they're not & you manage to crack the pattern, you still need to generate a code that has had some value assigned to it *and* has not been cashed in yet. Cracking a game is like making a counterfeit $100 bill - once you have something that looks convincing, you're free to use it. Making up Amazon vouchers is like convincing the bank that you've got $1000 in your account and they should let you withdraw it - even if you can convince them you've got an account, they have systems to track how much the account is worth."
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90p1ln | How do big manufacturing companies like Apple trace who leaked information about future products to third parties? | Technology | explainlikeimfive | {
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"There have been cases where companies have played Tyrion Lannister's trick: tell a bunch of people slightly different things and see which version of the story leaks. Fire the guy you told that version to.",
"In many cases it’s the monitoring software that most companies have on employee devices and their networks. There are other tricks like tagging the media itself in various ways."
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90p74o | What's the difference between HSRP and BGP? | Hello o/ - assuming this is the first time I've heard of these terms, what would be the simplest way to explain the difference between the two? | Technology | explainlikeimfive | {
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"They are very different things. HSRP/VRRP is for having a backup router take over in the event of an equipment failure. BGP is the way that routers on the public internet exchange routing information."
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90plac | How a one-time pad works (in cryptography) | I love reading Wikipedia articles and came across the article on one-time pads after reading about numbers stations. How do they work? The example the wiki page gives at the top of the article is confusing. | Technology | explainlikeimfive | {
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"Imagine you have a pad of paper. Every page is just random numbers from 0 to 25. Your spy in the field has an exact copy of the pad. To send a message, you convert all the letters to numbers and add them to the numbers from the pad. Convert the sums back to letters and transmit that message\\*. The person who receives the message reverses the process. Destroy the page from the pad when you're done with it. ***IMPORTANT:*** **You never re-use a page from the pad.** As long as this is done correctly, and you never re-use a page, this method is utterly secure. Julius and Ethel Rosenberg went to the electric chair because some idiot Russian spy re-used pages from his pad. ---- \\* This is just one possible implementation. The exact method isn't important; it's the one-time pad that makes it secure. As GiveMeAPingVasily points out, the key is as long as the message. If your message is a thousand letters long, then you use a thousand numbers from the pad, using each one once, and once only. The real weakness of the one time pad is that you need to provide a pad that's as long as all the messages you'll ever send, put together. When the pad runs out, you need to find a secure way to get a fresh pad to the other side. This can be a non-trivial problem if you have a spy in the field who can't sneak back home to get a fresh pad."
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90tw5o | If games can render near photo-realistic graphics in real-time, why does 3D animation software (e.g Blender) take hours or even days to render simple animations? | Technology | explainlikeimfive | {
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"Games use a lot of tricks to fake the photorealism at less cost than doing it for real (compressing textures, popins, etc.). The most important one is the lighting. You may notice that shadows don't always look right in games. You know how when you hold something colored under a light, it starts to glow that color? Games don't do this because they don't simulate the light for real, they change the textures to make shadows and light. Real animation software takes no shortcuts and renders things with full textures and full detail. This software often calculates the path of each ray of light bouncing around the area until it runs out of steam. This calculation is what takes all the time because there are millions and millions of light rays to trace. Fun sidenote: a few weeks back, Nvidia managed to make real-time Ray tracing possible using some new technology they're developing, but so far it still take colossal amounts of power to run.",
"The ELI5 answer is that games don't actually produce photo realistic images in real time. If you look closely, you can see imperfections that break the realism. These mainly revolve around how lighting works. In order to fix that imperfections, it takes a lot more time.",
"Games produce their impressive graphics with some cheats that won't work in all cases and cannot really be improved by just throwing more render time at the engine. For example the game might have a relatively simple model with textures and lighting maps produced ahead of time to make the desired effect. A program such as Blender on the other hand would be producing everything from scratch and actually rendering the geometry of a more complex model (from which the lighting and bump maps were produced) and the interaction of light with the model and texture. While this process is much more time consuming it can also produce a better image with more allowed time for calculations.",
"There is a new version coming soon with a renderer called Eevee that does render very high quality in real time, though even with this, the full Cycles render will still look better. The truth is, there is a noticable difference in visual quality between even the best realtime render vs pre-rendered cgi. For a more specific example - A fancy renderer will simulate individual rays of light on the scene your rendering(ray tracing), but a realtime renderer will approximate it. It's also worth pointing out that games 'bake' lighting maps before hand, which can take a lot of time if it's a big complex scene. You get different savings depending on wether you want baked or realtime. Baked - more ram and space on HD Realtime - more gpu/cpu time You also can't move an object that has been baked into a lightmap, or it will leave it's shadow behind!",
"The most impacting element is that generally games use shading where as rendering with blender uses ray-tracing (virtually shining hundreds of thousands of virtual photons (if not millions/billions) to illuminate an environment.",
"Games use tricks to render wonderful looking graphics in real time. Lots of games do complicated math in advance that can take hours or even days to compute. The results of this are saved and kept around to be used for final calculations later. All the time that would’ve been spent doing those calculations is saved, because it takes no time at all to look up the answer to something. Think of it like baking a cake from cake mix vs baking a cake from scratch. Let’s say you have a ton of cake mix already. You don’t have to go through the effort of measuring out the sugar, flour, baking soda, mixing it all up, etc. All you do is add some eggs, maybe some oil or water, and then pour it into a pan. Most of the hard work is done for you, but you can only make that one cake. The mix can’t easily be used to make other cakes. Something like Blender is making a cake from scratch. It doesn’t have these clever tricks and shortcuts. In fact, programs like Blender are often used to pre-compute the math (cake mix) that games use to speed up their rendering! A great example is often lighting. If you have a scene where the light is going to be mostly consistent, maybe an inn in Skyrim for example, you can pre-compute simulated light bouncing around from the candles, fireplace, off of shiny objects that are immobile, etc. This lets you save the color and intensity of light at any point in the scene, and simply look it up when you’re trying to add light to an object. This is a huge savings in time, and the results look great because you did a bunch of math that you could never pull off real time to generate very high quality light.",
"Two reasons. First, to render in real time, games have a much, much higher upfront cost in artist time - it just takes a lot more work to prepare a scene to perform well. In addition, a things like lightmaps and light probes need to be pre-calculated, which can also take hours or days. Second, games use a lot of trickery that has no basis in reality but looks ok thanks to very talented artists. But offline renderers (such as Cycles in Blender) generate the image by throwing around billions of rays of light, a lot like our actual universe does it. This makes the image look much more realistic and you can render almost any kind of scene this way without artefacts or bespoke code for this or that particular effect, as long as you throw enough processing power at it. Offline rendering is popular because computer time is many times cheaper than artist time.",
"Games are rendered using OpenGL or Direct X. Cinema 4D, Blender and similar apps use Raytracers and those Ratracers have all kinds of additions and hybrid rendering methods like Radiosity, Sub Scattering, and numerous others that actually calculate the paths of the rays and photons. This takes a much much longer time to calculate but produces much more realistic results in light and shadow and even the way skin looks. edit: spell",
"Realism is mostly about lighting. To render a 3D scene, there are two ways: 1. Try to render every object that is visible to the camera and calculate how it gets affected by an existing light. I'll take an example of a light that shoots all light rays in the same direction. If you can need to render a cube, you can draw perpendiculars on each side of the cube. Then you calculate angle between each perpendicular with the direction of light. If it's 0, it means they both are facing the same direction, which means, it's facing away from light. So you darken it. If it's 120°, you lighten it. If it's 180°, you make it the brightest. This technique is called Shading. Interesting point to note here is that it takes into account only two things: light and cube. There could be another red wall near the cube which will cast a red tint on the cube in real life. Now that can't happen with this simplistic algorithm. This can easily be computed by a graphics card on a computer in 16 milliseconds (1000th of a second) i.e. 60 times per second (60fps). Games use this. 2. The other way could be where you try to be realistic. You shoot a ray from the light and trace every object it hits and bounces on. But this is not clear, how many light rays do you shoot? 10, 20 or million? Instead, people shoot rays from each pixel of the screen. We just need to get color for each pixel of the screen. For each ray, keep bouncing until you reach a light. Now set the color of the pixel based on the objects you have bounced upon and the type of the light. This technique is called Ray Tracing. This is obviously expensive. This will take minutes to compute. If you are now looking somewhere else, you need to recompute the entire thing again. Blender etc. use this. If games did only 1, they would have shitty graphics. What you can do is ray tracing for all the objects that don't move. Buildings, mountains, trees etc. don't move in Games. If light doesn't change, they don't change and hence will look the same. You store how they look in the texture of itself, and you combine with shading, you get results as if it were baked.",
"All of the other answers about shortcuts and rendering tricks are true but also worth mentioning is that videogame consoles are hard-wired to do a lot of the specific processing a game would need to look really good—and be playable— moreso than your desktop if you haven't tricked it out in some significant way.",
"ELI5 version is that you can parallel this to calculating Pi, where games essentially do the equivalent of calculating 22/7 and gets close enough, but 3D software actually uses a much more complicated and more accurate formula, and as such needs a lot more computation power.",
"Because as good as game graphics are, they're no where near photo-realistic yet. Proper raytracing is needed to simulate lighting correctly and that's very expensive.",
"Light, hair and fabrics like very loose clothes. There is no videogame in which hair looks and behaves almost perfectly natural like some animated movies. The Incredibles is a good example, I forget the character's name but the teenage girl with long black hair. Getting that hair to animate correctly is a nightmare and videogames can't even afford to bother much with that level of detail since no personal computer could render it in real time. Same for long fabrics like long skirts and capes. Light is a whole different story with material not reacting realistically to light hitting them, shadows not looking correctly or sometimes even being animated correctly, etc. Sometimes mirrors are an issue too.",
"They are not really rendering all that in real time. A lot of the lighting is pre rendered with a method called baking.",
"Games cannot render near photo-realistic graphics in real-time. Not even close. Most of their graphics are pre rendered. 3d animation software takes days because it do all of the work by itself, it's not already completed.",
"A lot of the work to make things look real in games is baked in. Meaning they take time to pre render and compile data to make it available in game. This and many other tricks are done to make it more realtime.",
"Alot of the newest graphical features you see coming out just now in games have been around in computer graphics since the early nineties. In fact a lot of graphical features are still too calcultation intensive for games to be playable at still.",
"The cool answer is that Starting with 2.8 and the release of their new evee real time engine, blender will have the same kinds of real time renders as a video game. URL_0 The correct answer is that rendering time depends on the render method and the desired quality. Ray tracing takes longer but is more accurate, because it actually shoots rays of light and calculates the results based on how the light bounces in the scene. You shoot more light rays, you get more realistic results, takes more time. Video games use tricks to optimise. For example, you can bake your lighting in a scene and only recalculate character shadows and lights. If you have reflections, you can use a reflection sampler that calculates the reflections once and applies it kind of like a skybox to all the reflective objects in your scene. You can approximate a lot of things, like shadows and such. Vfx are usually faked using particles. etc ...",
"Worth noting that a lot of the time spent waiting for a photo-realistic render, is offloaded on the back end in video games, via hours of work via modeling, sculpting, texture creation, rigging and animation that is optimized meticulously by artists.",
"Most of the lighting you see in games has been ‘baked’. You’re walking through the rendered scene. Some of the stuff I build can take a while to compile - this is the process of baking non-dynamic light into a map or scene.",
"Blender is working on a realtime rendering engine called Eevee, is pretty good so far but crashes every 5 or so frames and is super wonky. I don't suggest even attempting to use it right now, but it looks like it'll have a bright future.",
"You can actually see how it’s done using just Blender - set up a scene, unwrap everything, create new textures and materials, and bake the scene. Switch your materials to emission materials that use the newly generated textures, change the view to material, and you’ll be able to view the “lit” scene in real-time - move around, manipulate it, etc.",
"OP. If you're into animation may I suggest using Unreal engine instead. It's going to be top quality and render significantly faster than Blender or similar software. Theres already someone out there using it for children's cartoons. It's free to use with some exceptions for commercial use. There's an expansive amount of guides out there for Unreal engine and I think video looks amazing on games using that engine(tricks or no tricks).",
"Its about the fidelity and technique. Games take lots of shortcuts you don’t notice especially when things are moving. One of these shortcuts is using very parallel rendering techniques that work well on graphics cards. Photorealistic rendering uses different approach that doesn’t many shortcuts and uses a processing method that isn’t as processor friendly. We’ve gotten so good at our shortcuts and so fast with the hardware that it’s getting harder and harder to tell the difference."
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90vm2r | If RAM (in typical computers) is memory used for temporary storage and is the fastest form of processor-storage transfer, what is Video RAM for? | Technology | explainlikeimfive | {
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"Same thing but for the graphics processor instead of the normal one. There are two primary processors in a computer, the GPU and the CPU. One is for graphics and one is for data, speaking simply.",
"Your assumption is incorrect. RAM is a very middle-of-the-road type of memory in terms of speed - it's only fast compared to hard drives or optical storage. Cache memory is magnitudes faster than that, and information kept in processor registers is still faster than cache. Special Video RAM is built into GPUs because it takes too much time to retrieve the information from main system RAM on high performance GPUs - it alleviates a bottleneck. That is not to say GPUs can't work off main system memory. In fact, if you completely fill up a GPU's Video RAM, it starts using main system RAM thanks to clever drivers, but at that point performance degrades very noticeably. Integrated GPUs use system RAM and work just fine, though they don't perform very well in terms of gaming. So do consoles, but those are specially designed to provide fast access to system RAM for the GPU."
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90wac7 | Why do noise-cancelling headphones make people feel ill? | Technology | explainlikeimfive | {
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"It messes with their equilibrium. Your ears and the stuff in them help your body feel balanced. Slight vertigo can happen with those headphones causing some people to feel nauseous and/or dizzy. Even when people get ear infections it can cause vertigo."
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90wmka | Why can’t a company fully charge a device before they send it through the mail? | Is it bad for the battery or does it just die in transit, even if it’s not being used? Or something else? Thank you! | Technology | explainlikeimfive | {
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"A battery that isn't charged as much is going to burn for a shorter period of time if it fails during transit.",
"The higher the energy the battery has stored, the higher the potential damage when mishandled. In the case of Li Ion batteries, storing them at a lower charge is beneficial for the cell, as certain chemical processes are slowed or stopped that would deprecate the health over time in storage.",
"It used to be you couldn't send them charged at all. Think of a charged lithium ion battery like an inflated balloon. At full charge, they are stretching to their limit - ready to burst and leaking out gass. If they are sent via air, the drop in pressure can put even more stress on them and can wear out the stretchiness of this battery-balloon. And worst of all, lots of devices need to sit on shelves for a long time before getting to the consumer. While sitting on the shelf, there is a *self-discharge* rate at which the battery will leak charge. Fully inflated, this will happen faster potentially damaging the cell and wasting that extra power anyway. As lithium+ has gotten better, industry had to change. It's not trivial to charge a battery as the product is being manufactured. It takes time. It also get used at *end of line* product testing. So keeping a little charge let's people use the device right away while complying with safety and minimizing the self.discharge and storage risk."
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90wpk2 | Why is that plastic-ey printed texture on T-shirts so annoying and why do they keep making them? | Technology | explainlikeimfive | {
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"None of the answers here are correct. I'm a printmaker, so here's the real deal. What you're desrcibing is plastisol ink, which is very commonly used for printing on t-shirts, tote-bags, hats, and other apparel. It's essentially PVC resin and pigment suspended in a liquid plasticizer. It's commonly used because it's cheap, easy to use, very versatile, and, if done correctly, robust. A lot of printing is not done well, which results in the thick plastic-y texture and flaking that you described. Well printed pastisol items will only have the faintest texture and will last a long time. The alternatives are water-based in, discharge printing, or dye sublimation. They all have their different benefits and drawbacks."
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90wsso | Why do batteries age quicker if you charge them wrong (i.e. newer smartphone batteries should only be used between 80% and 20%; older batteries had to completely charged and rundown to get the maximum lifetime) | Technology | explainlikeimfive | {
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"Older batteries had \"memory\" so if you stopped charging too soon, they would \"remember\" that as a new charging point and stop being able to fully charge. I don't remember the science behind it though.",
"The life span of modern cell phone batteries can be shorted by two major factors: * How much heat the battery is exposed to * What voltage the battery cells are charged to. The 20%-80% charging range has to do with both of these factors. The lower the battery charge gets, the more heat it will generate when you go to charge it back up. Heat slowly damages the battery cells and eventually too much heat will cause junk particles to accumulate inside the battery preventing it from charging properly. That's why you should avoid totally discharging your battery all the time since it will shorten the lifespan. That's the 20% part. On the other side is the voltage of the individual cells. Cell phone makers have a trade-off here. If they were to pick the perfect max voltage to charge the battery to, it would be about 80% of the current max voltage most phones are set to. This would help extend the life of the battery. However the means that the phone will run out of charge faster and need to be re-charged more often. Since phone makers love to claim how long their batteries last (and they want you to buy a new phone relatively soon anyway), they design the phones to charge to a higher-than-ideal voltage so that you get to use the phone longer per charge and the battery wears out faster. **Personal Note** For me, though, keeping my phone between 80% and 20% is too much of a pain in the ass, so I just always charge my phone when I can, even if that means letting it sit at 100% over night. However, in order to get the max life out of the battery on my MacBook, I try my best to keep its battery between 60%-80%. I know that's a super tight window and involves lots of plugging and unplugging the charger, but it will be worth it down the road when my battery is still performing well."
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90xo1k | Why is water so difficult for 3d animation? | Technology | explainlikeimfive | {
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"Water presents a number of challenges. First off, since it's a liquid it can move in a huge variety of ways, which means it's difficult to simulate well, and the more accurate you want to get, the more computational time it's probably going to take. If you're simulating something where the water is constantly moving (a river, or waves on a shore), that's a lot of work to be doing if you want it to look really good. A common method of doing this is having the computer represent the water as a whole bunch of spheres that collide with each other and with the surrounding geometry. This determines where the water is going, and then graphics shaders render it to look like a continuous liquid rather than separate spheres. The more spheres you add, the more fine grained and realistic your water moves, but the more you increase the computational requirements. Second, water is mostly transparent, but not entirely. So for it to look good, you want to be able to see through it, but not have it be completely clear. If there's enough water, it eventually absorbs a significant amount of light, and not equally across all wavelengths. So you have to try to get that right. Also if you're looking into the water from above it, you get refraction, and if the surface of the water is moving and/or has waves/ripples/etc. then that's even more complicated. Third, while being transparent, water is also reflective. So there's another layer of complication, and again it gets even crazier if the surface of the water is in motion. Now, a lot of this stuff can actually be simulated pretty realistically, and we've figured out ways to make it look good. But the better of a job you want to do, the more work the computer needs to do, and if you're playing a game there's only so much processing time that the computer can spend on water for each frame. So a lot of times various tricks/shortcuts/etc. are used to make something that looks good enough that we'll accept it as water, even though it's not a particularly accurate simulation.",
"Because there are so many elements which needs to be executed properly for the water to look realistic."
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90xwml | How are tire changes so quick in Formula 1 cars? | Technology | explainlikeimfive | {
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"They've really optimized their wheel designs to make it fast On your car you have to jack it up, undo 4-8 lug nuts, remove the wheel, put on the new wheel, put on 4-8 lug nuts, then lower the jack In formula 1 they just have to jack it up, undo 1 big nut, remove wheel, put on new wheel, put on 1 big nut, then lower the jack Having only a single nut greatly speeds up the process, as does having a jack that they can raise and lower with a single motion rather than pumping. They've also spent a few hundred million optimizing the hell out of this process to shave off tenths of a second",
"Practice. The crew do thousands of practice stops to ensure they get it right. Each member of the crew has a specific job to do, it takes 3 people for each wheel - one loosens the wheel, another removes the old wheel and a third fits the new wheel, the second man then tightens the nut. In addition there are two crew members that jack the car up, one front, one rear. There are often stand-bys for the jack men, in case a jack fails. Front jack man in particular is a brave soul, as they literally stand in front of the car whilst its still doing as much as 50mph, hoping it stops! Another holds the \"lollipop\" that is held in front of the driver that gives them the all clear to leave when raised. Quite often you'll see someone holding the top of the car to steady it and yet a couple more to clear the sidepods (where the radiators are housed) of debris. The guns used to loosen/tighten the wheel nut are run by compressed air to be as fast as possible. The wheel nut itself has a coarse thread and will be fully tight in about a turn and a half. The driver too, is a critical member of the crew - he needs to stop dead on his marks, if he stops late the entire crew have to take a step or two down the pit lane - costing precious tenths of a second. They use a limiter to restrict the speed of the car, but as with everything, its use is pushed as far as possible - should the drivers finger slip and the car go too fast a penalty will also certainly be the result - meaning a fast pit stop is completely wasted. If the driver misjudges his braking he risks running over/causing injury to the crew. Once the stopped the driver needs to hold the brake, if the back wheels spin it takes it difficult for the crew. Once dropped back to the floor the driver (impatient to go) needs to wait for the lollipop to lift before moving - there could be an obstruction - a crew member in the way, a gun still tightening a wheelnut or maybe a car travelling down the pit lane. When given the nod to go the driver must ensure he uses enough engine revs to pull away without stalling (there are usually a couple of crew members standing by with the starter for this eventuality). Basically every single aspect of the stop is tuned for speed - using literally as many people as they can get around the car, the equipment is specifically designed and engineered to allow the stop to be as fast as possible (high speed guns, single wheel nut, special thread etc), the teamwork too is a vital part of the process. Sub 2 seconds stops are possible (Williams have been superb in recent years) but absolutely every single detail needs to be perfect - hence the amount of practice the teams do."
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90yku2 | how do fingerprint scanners on mobile phones work and are they different from other scanners? | Technology | explainlikeimfive | {
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"There are three primary types of fingerprint scanners on the market. The one used in smartphones is called a *capacitive scanner,* as it relies on a property called capacitance. Basically, the scanner plate (typically a pad somewhere on the phone, often built into the home or power button) passes a small electrical current through itself, and when you press your finger to it, the pattern of ridges and valleys changes the capacitance through the array of cells that make up the scanner. The scanner then stores, not the picture of your fingerprint, but the pattern of capacitance changes that your finger causes. It can then check that stored pattern against a new pattern generated the next time you touch your finger to the plate. ____ This is the same as other scanners on the market, but if you have the space and you want a more accurate reading, you'll generally use an optical or ultrasound scanner."
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90z982 | Why is it so hard to get that old 'hand drawn' look in modern anime/cartoons using computer animation? | Technology | explainlikeimfive | {
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"It's not done very often because animating something that high quality would take a really long time. It's possible, just insanely time consuming.",
"There's a lot of reasons why old hand drawn animation looks different than today's computer animation. Computer animation can still be hand drawn with a tablet or Cintiq, but often times it'll be a mix of hand drawn poses and reused poses or parts (for example you may have a library of 100 different hand poses or mouth shapes to reuse). This saves a lot of time and keeps the drawings consistently \"on model\", but definitely has a different look to it. The more you reuse a library of poses/parts, the more likely the animator will plan their scenes with those poses/parts in mind and the more it looks \"Flashy\" (or maybe these days \"Toon Boomy\"). There were ways of achieving the same effect in older animation by tracing over parts of previous poses or reusing entire scenes, but even with tracing there are going to be some differences. This is probably most noticeable in computer animation that only uses a handful of mouth poses; even if it's just subconsciously, you can tell that the same 12 or 15 mouth shapes are being used for dialog, and maybe some additional shapes for extreme expressions. Even worse is if you're limited to a set of pre-approved poses; the animation starts looking very \"samey.\" Another difference is that old animation was drawn on paper, then clear celluloid was laid over top to add the ink lines, and then flipped over and the back was hand painted. This leads to a number of artifacts that are difficult to reproduce in digital animation or simply undesired. First, you have slight inconsistency with lines from frame to frame, called \"line boil\". For a big expensive production (like Disney or Richard Williams) the animators are *very* careful to keep those lines as consistent as possible; Richard Williams in particular was a perfectionist and would require his animators to redo a scene if the lines were off by as little has half the width of a pencil stroke. This can still happen on a digital production but it's easier to avoid and easier to fix, so even low budget TV shows usually won't have line boil unless it's intentional. Other artifacts included mis-colored cels that would sneak in, especially in TV animation where you had tight deadlines and low budgets; it's just too expensive to ink a new cel, repaint it, and re-shoot it. Fun fact: because film was so expensive, the camera operator was often the highest paid person on the production; you had to get it right the first time or you can destroy your budget. In addition to mis-colored cels, there was also inconsistent thickness to the paint which leads to subtle changes in the color. There are no color inconsistencies in computer animation because you're usually going to be working with a preset color pallet and pre-colored body parts/props. Even for productions that need to be colored frame by frame, if you spot an error it's really cheap and easy to fix it with digital ink and paint software. And since it's not shot on film anymore, there's no film grain or issues with focus being slightly off. Digital colors can also be much more saturated and sharper contrast than what you get with film. The cels also aren't 100% transparent, they block out a small percentage of light. This meant that scenes with more cels stacked on top would darken the background elements. As the scenes play out, you can see this darkening/lightening of the background elements as layers of cels are added and removed. With digital animation, you can have hundreds or thousands of layers without the darkening/lightening effect. And finally, animation style has changed quite a bit over time. Compare the \"rubber hose\" style popular in the 20's and 30's to the limited style that UPA popularized in the 50's, to the zip and pose style in the 2000's. There's also house styles; there's a clear difference between Warner Bros and Disney style, or Pixar and Dreamworks. It's not just the animation style, either, it's also things like character design and color choices. You can certainly emulate older animation styles on the computer, but audience tastes change over time and animation directors want to stand out from the crowd so you don't see the older styles as often in modern productions. Computer animation also lets you do interesting things that would be prohibitively expensive for hand drawn animation. Consider the characters in Foster's Home for Imaginary Friends; many of those designs would be an absolute nightmare for hand drawn animation, especially on a TV budget. But thanks to Flash and a huge library of reusable body parts, poses, and animation sequences, the costs are kept lower and you get a really unique cast of characters and an interesting animation style."
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90z9sy | How can SD cards (or other storage devices like USBs, HDDs...) of the same physical size have a different storage? | Technology | explainlikeimfive | {
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"For many flash devices, even if the same manufacturing process is being used, the physical flash memory modules (which are only a portion of the final device size may be a different size, or a manufacturing process that results in a more dense chip may be used for larger capacity drives. For hard drives, the number of physical platters can be varied (especially for 3.5\" form factor drives), and improvements in technology over time have resulted in more precise and accurate control over the read/write head and a few changes to how data is physically stored (such as shingled magnetic recording for a few drives)"
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9120ob | How do vending/cash machines know what type of dollar bill that was just inserted? | Technology | explainlikeimfive | {
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"So I do not know it vending machines utilize all (or any if these) but I used to work for a company that made cash counting machines that banks use. Our machines used image sensors, magnetic detectors, and ultraviolet light to determine the denomination of the bill.",
"They can use optical scanning to check for the amount that is printed on the face of the bill. Newer bills also have security measures incorporated into each bill that can be checked for, like microprinting or special fibers embedded in the bill."
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914nta | What are the buzzing sounds speakers make whenever a phone receives a call? | Technology | explainlikeimfive | {
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"text": [
"Interference. Since speakers have magnetic coils they act as an antenna and receive the signals emitted by your phone. it converts this into sound. But since the transmitted signal is digital format and the speaker is analog thats what you hear a burst of very fast beeps."
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91546a | How is it that in some Sci-Fi movies/shows destroying the control panel of a door would lock it, while in others, it opens the door? | Technology | explainlikeimfive | {
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"It depends on whether opening or locking the door is more useful to the plot at that specific moment. If the writers want the heroes to open the door, they will put that in the script and the actors and special effects people will make it happen. If the writers want the heroes to lock the door, they will specify *that* instead. Whichever one they choose, the writers should be careful to keep it the same most of the time unless they can come up with a sensible explanation for why it is sometimes different. & nbsp; If you want an explanation relating to real life doors - they make two kinds of electronic door locks. Fail-safe locks will unlock if the power goes out, so people can get out. Fail-secure locks will lock if the power goes out, so bad people can't get in.",
"Because the plot needs one or the other to happen. That's it. Not only are they movies and TV shows, ie *not real*, they're sci-fi. That's even more out there than if it were a modern day \"real world\" movie or show like Bourne Identity or something. It's fiction. It has no bearing on reality and there are no consistent rules beyond what the plot requires.",
"Plot convenience. In reality, we can build mechanisms that fail both ways. Eg, a door that's held closed by an electromagnet and that will automatically unlock on loss of power, or a door that is mechanically locked by default and needs a working mechanism to unlock it. In general the first approach is a good idea for safety reasons. You really wouldn't want to be locked in during a fire, or be unable to access the control room because something broke when your spaceship was hit. The second approach is good for security reasons. If you're trying to protect or contain something, you don't want to allow people to waltz in just because the power went out. Hence why building a park housing dinosaurs that are only contained by a weak electric fence is a really stupid idea. It's a scheme that is guaranteed to go horribly wrong at the first power failure.",
"In real life it depends on wether you need a systems fail-safe to open up or lock a door. Obviously in many cases you want people to be able to escape in an emergency, but in many others you prefer security and closed doors. In movies it mostly depends on what is convenient to the plot more than what makes sense in universe."
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915dib | how does torrent system work? | Technology | explainlikeimfive | {
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"In a traditional situation, you have a Server and a Client. The Server is basically a big computer that handles the request of the Client, if you for example want to download a legal copy of a movie, the server would send it to you. That has the advantage of having a clear and simple structure and depending on the server, a reliable source for your movies. A torrent system is a peer to peer system, which means there are no dedicated servers, just clients, but everyone fullfils a little bit of the role of the server. If you want to download another legal copy of a movie, you would not download it directly, but download a file that basically tells you what you need to download, your client will than ask every other client if they can provide it to you (which is called seeding) and you download it from many different sources. The whole system relies on the premise that you make yourself available for seeding after that, so far that you can only download if you seed at the same time. It is basically a decentralized version of a server, stretched over many clients.",
"You want to download a puzzle. Everyone has the puzzle you want, so they each give you a different piece at the same time. You now have your own puzzle faster than if one person gave it to you piece by piece.",
"Imagine you want to read a book. You hook up with Alice, someone who is also interested in this book, but only has one chapter. Alice shares the chapter with you, so that you could pass it on to others. Next you hook up with Bob, who has another chapter, but doesn't have Alice's one. Now you can share your chapter (that you've got from Alice) with Bob, and Bob can share his chapter with you -- and as a result you both have two chapters. From that point onwards you keep on hooking up with other people, get chapters you're missing, and share chapters you've already got, until you've assembled the whole book. Now consider that any data can be split into \"chapters\", and torrent tracking sites and software just simplify the hooking-up process.",
"Simple version: A Torrent is a peer-to-peer sharing system This means someone hosts the file they want to share, this person is known as a 'seeder', the rest of the world can then connect to this 'torrent' and download it directly from them, the people downloading the file are known as 'leechers', once a 'leecher' completes the download they then become a 'seeder' and begin co-hosting the file, thus when you look at Torrent sources they often have a leecher/seeder ratio. The higher the amount of 'seeders' the more likely you are to have a fast download speed. You can stop seeding at any point by deleting the torrent in your torrenting software or by moving the file to another directory, but doing so will result in 1 less seeder for said file, if everyone stops seeding the torrent becomes dead and is no longer usable."
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916hsm | Why is the Android/iOS version of an app updated so much more frequently than the desktop versions? | Technology | explainlikeimfive | {
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"Assuming you're talking about desktop programs, it's probably because it's easier to update through an app store than a standalone program. Google Chrome is an exception though, as it updates itself without any user intervention. The actual Windows OS itself does seem to update much more than Android and iOS though."
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917hox | Why, when you’re on slow wifi, will ads load before the content you actually want to see? | Technology | explainlikeimfive | {
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"text": [
"The web site is programmed to send the ads before the content. Otherwise, you'd be less likely to see the ads, and their customers would be unwilling to pay for the ads. Remember, from a web site operator's perspective, the purpose of the site is to show the ads."
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9196fa | How does "I'm not a robot" - captcha work? | Would not be a script able to just check the box? | Technology | explainlikeimfive | {
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"text": [
"Those checkboxes are doing more that just observing when you click the box. If it was a script doing so, it would have happened immediately after the page finished loading. So the captcha is watching how long it takes for the box to be checked. Its also watching cursor movements. If the cursor makes a laser straight line or \"snaps\" to the checkbox control it knows its a script as well. Its looking for an uneven (by computer standards) shakey human looking mouse movement.",
"It \"randomly\" can make you do a task involving pictures. the randomly part has something to do with how fast you click the box and stuff. I'm sure someone else will go more in depth about it but this is just the basics of the system."
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91actn | how internet speed tests work | Technology | explainlikeimfive | {
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"text": [
"URL_0 They use servers that specifically track how fast your connection is. A server that is physically located to you will, usually, present you with better speeds than a server that's located farther away (especially if that server's located overseas). For downloading, it sends an initial chunk of data over multiple connections through a specific port. Based on that it determines your bandwidth and appropriate chunk and buffer sizes. Afterwards it sends multiple chunks of data to your computer and calculates how fast they are being received. The upload test is similar, just in reverse. ELI5: The test server sends many files to your computers for a certain amount of time. After the time is elapsed, it calculates how many files were received and based on that can figure out how fast your internet is. The upload test is the same, but in reverse - your computer sends data to the test server for a certain amount of time."
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"https://support.speedtest.net/hc/en-us/articles/203845400-How-does-the-test-itself-work-How-is-the-result-calculated-"
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91axfu | Why didn't anything happen after Telecom companies not build a fiber optic network, even though they got 400 billion from the gov't. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Phone companies: \"Relax rate restrictions. We'll build fiber!\" Government: \\*relaxes rate restrictions\\* Phone companies: ... Government: ... A small, vocal group on the Internet: \"So where's the fiber?\" Phone companies: \"What fiber?\" They built out a little. Mostly, though, the regulators forgot about it, and the phone companies were happy to let them."
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91bosf | At recycling sorting facilities, how are tiny objects such as shredded paper sorted? | How do they make sure that every single bit of shredded paper is paper without wasting time checking every single bit? Also, if you put a CD or credit card in the shredder and mix it along with the paper, how are they going to make sure that none of that goes into the batch for paper recycling? | Technology | explainlikeimfive | {
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"text": [
"They use pretty advanced machines with different technologies like optical (camera) detection, magnets, air brushes, centrifuges or even chemical methods to sort different materials. Plastics for example can be separated by a optical spectral analysis, as the material can be identified by a difference in the spectrum of reflected electromagnetic waves. But the rest that cannot be sorted is probably just burned in a furnace or dropped in a landfill.",
"Pretty sure it all goes into a vat of water and turned into pulp, but in the tank the paper gets wet and sinks, the plastic and wood float and are scraped off",
"Shredded paper will float an is skimmed off. Heavier material is then sent over a magnetic conveyor that pulled out the iron and steel. The it is then sorted by density in increasingly denser baths of magnetic media and then sorted by size by giant vibrating screens. It can be further sorted by eddy current rotors that make metal like aluminum jump over dividers or optical systems that can recognize different colors and use air jets to separate ( I worked for a big auto shredder recycler in the 90’s)"
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91eyxt | From a CRT: What is an electron gun, and What exactly does it do? | Technology | explainlikeimfive | {
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"text": [
"An electron gun is a device that emits a continuous beam of electrons when powered on. In a CRT, electromagnetic coils bend the electron beam back and forth to scan across the screen like printed text, left to right then top to bottom. The beam strikes phosphor strips that coat the inner surface of the screen and cause them to glow. The strength of the beam determines how much the phosphors glow and is continually varied by modulating the amount of power sent to the electron gun to draw the desired image.",
"Electrons are charged particles, and as a result accelerate when put in an electric field. An electron gun is simply a source of electrons (often some heated metal that doesn’t hold its electrons very well) and an electric field. The field pulls electrons off the source and accelerated them down the “barrel” of the electron gun. These are made more useful by having more than one electric field. They’ll have one electric field to accelerate the electrons, and two in other directions to direct the electrons at a target (these are at right angles to the field that accelerated them). One use is to display images. If you coat glass with a phosphorescent material, electrons hitting the coating will cause the coating to glow (commonly green). So drawing images is possible with electron guns, and thus sort of thing is really common in scientific equipment. If I’m not mistaken, cathode-ray tube televisions used an electron gun (which is the tube itself) to display the image on your screen. This is why CR-TVs are so thick and heavy, they have this huge cathode-ray tube in them.",
"Doesn't 'electron gun' sound cool? IMO it sure does, even though the heart of an electron gun can get quite hot. :) An electron gun is used as a source of electrons which are often used in imaging devices. In practice, a substance is heated to release electrons as electrons get too excited. This is called thermionic heating. 'Too excited' means their kinetic energy exceeds the ionization energy, i.e. the energy related to the electric force between a nucleus and its (outer) electron(s). The flow of emitted (released) electrons is then accelerated to desired voltage and focused with lenses in order to form a beam of electrons. As the main qualities of the beam are known, it can be used to observe or analyze material. After the electrons hit a target, the qualities of then released electrons convey information of the target. A target may be something manufactured to form an image on a screen or to analyze an unknown sample with an electron microscope. The most common types of electron guns by source material are tungsten filament, solid state crystal (CeB6 or LaB6) and field emission gun (FEG). **Tungsten filament** The cheap, traditional option. It's basically a light bulb on steroids: more power so that electrons, instead of light, can be emitted. **Solid state crystal (CeB6 or LaB6)** Offers about 5-10 times the brightness and a much longer lifetime than tungsten. **Field emission gun (FEG)** A wire of tungsten with a sharp tip (tip radius < 100nm) for improved emission and focusing ability That's about it. This is my very first response on Reddit. Hope it helped and answered your question! (And yes, English is my second language, so please be kind.)"
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91fist | Operating systems tend to throw very general errors at times. What are the complications behind making an OS tell you exactly where the bug is and how it can be solved? | Technology | explainlikeimfive | {
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"text": [
"The OS observes the things it can observe. Things like accessing/modifying memory, opening/reading/writing to/closing files, interacting with devices, etc. There are many programming errors that can lead to one of those things going wrong. If you try to access memory that isn't within your program's allowable space, the OS will see it. But it may not know whether that's because you did bad arithmetic on a pointer, or because you failed to check the length of an array, or because you just put a random value into a variable and tried to read whatever lives there. They all look the same to the OS. It's not dissimilar to being at a restaurant, and ordering the steak medium rare, and having a plate of pasta delivered. You can tell your server that it isn't what you ordered, but you can't tell him or her why. To troubleshoot that, the server and the expediter and the kitchen staff would need to go over what happened and figure out where the error occurred. As far as you're concerned, any of the mistakes that could have led to a pasta being served to you are equivalent. Wrong food. The only way for you to have a better idea of what went wrong would be for you to be observing the entire process, which would impair your dining experience (because then you would need to be observing the whole process for every dish you ordered).",
"Theres nothing stopping them. They could do it, but it would increase the overhead of the os, and further restrict the machines it could run effectively on. It's just probably not cost effective. Coderes aren't free and manhours aren't infinite."
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91flac | How films that were filmed before 4k technology was around, can be re-released in 4k? | Technology | explainlikeimfive | {
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"Film has its own inherent resolution based on gauge, emulsion, lens quality, etc., though not in a convenient pixel count like digital. Old films can be scanned at high resolution, and as long as the film is in good condition, and the film stock was good enough to begin with, it can be scanned at any resolution currently possible. As scanning tech progresses we’ll keep scanning at higher resolutions. The problem I suspect we’ll run into is the film grain becoming too distracting, but I’m sure there are plenty of smart people writing great software to fix that.",
"Because the films that the movies were shot on is high enough resolution. The conversion from film to DVD or even blu-ray is a loss in resolution. Rescan the film masters at 4k, problem solved."
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91idqg | Why don’t viruses in virtual machines effect the host computer? | Technology | explainlikeimfive | {
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"A virtual machine is completely isolated from the host computer. In some cases virus can actually affect a host computers, but it doesn't happen often.",
"A virtual machine is just that— virtual. Your computer is basically figuring out “if I was a computer following this code/instructions, what would I do?” rather than doing those things in a way that affects its own system and files. So if the code says “take tax/financial documents stored on your desktop and send it to Russia” your computer will look at *the virtual machine’s desktop* and send anything *stored there* to Russia. It won’t look through files on the host computer because as far as the virtual machine is *and code the virtual machine runs* is concerned, the virtual stuff is a normal, complete computer system. The virtual desktop folder **is** the user’s desktop folder. It could be possible to trick the host computer into doing something during this simulation process, but it would look very different from code used to infect/trick normal computers operating normally. So the number of people affected would be lower and the motivation to make those viruses less... especially because VM users are often aware/smart enough to patch and update as vulnerabilities become known, while many regular computer users don’t realize the importance of updates or know anything about security.",
"These days virtual machines are designed to be isolated from the host computer but are not 100% completely isolated. There are some viruses that are written to detect if is is on a VM. If it detects it, it can use many mechanisms such as COM ports, shared USB ports, shared folders / files and more to attack the host computer.",
"A virtual machine is running under the control of a program called a hypervisor. Everything that the virtual machine does, ie every instruction that its CPU executes and every bit of data accessed on its hard drive, goes via the hypervisor. The hypervisor will only allow the VM to talk to the components of its own VM, and not any others. The VM simply can't see the memory or disk space belonging to other VMs or to the host computer. It's one of the key functions of the hypervisor. You can weaken the defences by, for example, creating network shares that allow 2 VMs to see each other. In which case, a virus on one VM will affect another. But a VM being able to access any part of the host operating system or the hypervisor would be considered a serious security weakness and would be plugged quickly."
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91kbdo | Why do some fighter jets need two "pilots" while other only need one while doing the same task? | Technology | explainlikeimfive | {
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"The guy in the back is the weapons system officer. He frees up the pilot to focus on pilot things while he takes care of locking on to targets, dropping bombs, and firing missiles There are versions of the F/A-18 with one seat and two. The F/A-18E has a single seat so the pilot is running everything. The F/A-18F has two seats with a weapons system officer in the rear It depends on the needs of the mission",
"The F14 has a pilot and a RIO (radar intercept officer)...basically a navigator / weapons systems officer The F18 is newer and with better technology, so a lot of the RIO duties could now be done by computer and the pilot is better equipped to handle the info and responsibilities.",
"I’m addition to the great answers so far, you should note that there are some two-seat variants of fighter jets that are used for training purposes. Not many, but they’re out there and often considered when developing a new aircraft to make a handful of them for planes that are traditional one seaters."
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91lsj5 | Why when you turn off a light it emits a glow for a bit after? | Technology | explainlikeimfive | {
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"The filament in the light bulb takes a few seconds to cool off, so it still appears red hot.",
"A traditional (old tech) incandescent bulb works by passing electricity thru a thin wire until it gets so hot it glows. Turn off the electricity and the wire takes a brief second to cool to temperature where it doesn't glow. Another old tech bulb called gas discharge passes high voltage electricity thru a gas filled bulb so that it produces a lightning Arc and ignites the gas, which emits ultraviolet light and makes the coating on the bulb glow. Turn off the electricity and the gas stops igniting but the coating still glows for a brief second. Newest LED tech passes electricity thru special chip made of gallium and arsenic or phosphorus. When you turn off the electricity, it turns off almost immediately, although the bulb control circuit has storage capacitors that will still power the LED for a brief millisecond."
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91obsl | How do pitches for a video game work? | Technology | explainlikeimfive | {
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"It's pretty much a free market, especially with Indie Studios, so there is not one set answer to this really. Generally you wouldn't necessarily have to pitch this to an investor. A group of developers will form a studio, develop whatever they want, and try to get it published, or publish it themselves independently. It's a lot easier to do that now on Steam because you don't have to be greenlit anymore, you can just pay a hundred bucks to get it up. Large games that are new and ambitious can be developed under the protective wings of a very large company, having either been started by that company, or been originally a small Studio that was bought by the large company. Smaller game Studios also can create smaller new and innovative projects almost as an art form and less as a massive money maker (with the hopes to be though). I can't really imagine the game industry in which somebody would have to pitch an idea to investors like a shark tank like scenario in order to get it developed. That would be interesting though, I wonder how many Unique Ideas have been had but never acted upon"
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91pfp5 | why are Android application updates as big as the size of the app, while on Windows/steam they are very small? | Technology | explainlikeimfive | {
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"Android apps are packaged and treated as a single unit whereas on steam it is installed as a series of files. So on one hand you replace the whole unit (so technically you do reinstall the whole app), on the other you can replace individual files."
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91qpd6 | Why is it that we can watch graphics-intensive videos of games on let’s say, our phones when they have a weaker processor compared to a desktop or without any graphics card at all? | Technology | explainlikeimfive | {
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"Playing a video and actually doing the work rendering the video games are two different things. It's similar to watching a video of ninja warrior vs actually competing and doing the work in the competition.",
"I’m able to hold a Mona Lisa and present it to you, but don’t you dare ask me to paint one."
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91rmei | What is an IP and is it assigned to device or network? | What do each of the digits mean? Is IP assigned to device [ie phone or computer] or network connection? What is a static IP and a dynamic IP? In the absence of cview3 [cookie data], can a consistent IP identify a device? Thanks! | Technology | explainlikeimfive | {
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"An IP is like a phone number. It is assigned to your router much like a phone number is assigned to a phone. A Mac address is like a serial number for each device, ie your printer,photocopier etc. A static IP never changes. A dynamic IP is automatically assigned by the network. So say you connect a laptop to the network. The network assigns an IP to it. Imagine you disconnected the laptop and connected a phone. That phone might be assigned the IP of the laptop so if you connect the laptop at the same time it will need a new IP. Hope this sort of explains a bit."
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91tp26 | How bad actually is it to plug in and turn on a freezer just after moving it? (People say wait 24 hours before turning it on) | Technology | explainlikeimfive | {
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"There's oil in the compressor part of the freezer (the engine bit) that can leak out if the freezer hasn't been kept upright during transport (which you don't know for sure it hasn't if you just bought it). Letting it stand upright lets this oil settle back into the compressor meaning it's less likely to cause issues when you turn the freezer on. 24 hours is recommended but for a new freezer you could probably get away with less.",
"If the food is already frozen and coming from another freezer, go ahead and toss it in, along with a bag or two of ice. Even an unpowered freezer is well enough insulated to act as an ice chest for a day. Also, if there's enough food to mostly fill the freezer, it'll bejust like your freezer has lost power for a day (some small foods on the outer edge may thaw a bit, but most will stay frozen and good).",
"If it was on its side or anything the rule is \"the same amount of time that it was on its side.\" If it's new, give it an hour or so and it will be fine. If it's old and been on its side in storage for a long time, then it's 24 hours. New ones are usually shipped and stored right side up."
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91wic5 | How does antivirus software work? | Technology | explainlikeimfive | {
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"Yer not alone in askin', and kind strangers have explained: 1. [ELI5:How does Antivirus work? ]( URL_1 ) ^(_42 comments_) 1. [ELI5: How does anti \"virus\" software work? ]( URL_0 ) ^(_6 comments_) 1. [ELI5: How does an Antivirus work? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: How does an antivirus work? ]( URL_2 ) ^(_31 comments_)"
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91xwo4 | In the band The Eagles, one of the band's lead singers, Don Henley, is also the drummer. This is also the case during live shows. How could the mic setup for this ever work? How could a mic for vocals not pick up super loud drums that are < 4ft away? | Technology | explainlikeimfive | {
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"The mic does pic up drums. The drums are a quick impulse sound, while the voice is a melodic average volume sound. By using noise gates and compressors it is possible to minimize the drum sounds while a drummer is singing. When the drummer is not singing his mic gets dropped out of the mix so you only hear sound from the mics closest to the drums."
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921ine | How is it possible that my car keys unlock only my car and not all the others? Is it theoretically possible that my key could unlock a second car somewhere on the world (given I'm close by)? | Edit: Apologies for the poorly phrased question. While the mystery of mechanical keys is fairly interesting I always figured that there would be a limited amount of key/locks available. My question was particularly referring to the (new) wireless keys!! | Technology | explainlikeimfive | {
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"Most modern cars have 3 layers of security when it comes to keys. Remote Identification, Physical Identification, and Encryption Identification. Remote identification is your keyless entry. It’s like when you yell for your mommy outside a locked room, if she recognizes your voice, she will respond and unlock the door to let you in. Voices can be similar, so if in the rare case some other kid sounds like you, she could be confused and let the wrong kid in. Physical Identification is the cut key itself, or in the case of Push Button start, the physical proximity of the key. When your mom opens the door, she would make sure you look like her child. You have a unique face but doppelgängers or your twin brother could fool her into thinking another kid is you. Encrypted Identification is the RFID chip inside the key that the immobilizer has to sense to allow the car to run. Even if you can duplicate the remote entry or physical key, the RFID reader will still need to read the encrypted code programmed to each key matches to the Immobilizer before the car is allowed to remain running for more than a few seconds. This is extremely difficult to duplicate and very short range, so the real key would need to be within a few inches of the ignition to work. It’s like your mom verifying your fingerprint or DNA to make sure you are you, even if you look and sound like her child.",
"The key fob uses a rolling code that is stored in the fob and the security section of the ECU or immobilizer unit. The fobs are all registered at the same time and they all use a separate rolling code (multiple codes per car, sometimes 5 or 6 possible fobs) So you press unlock and the fob calls out to the car, the car answers and asks for a code and the fob replies with the code that the car is expecting. There are a buttload of combinations so it is VERY unlikely that it can unlock another car BUT it has been done before. It's often a lot more complicated when you have proximity unlock (smart entry), remote start, etc etc. The fob ID can also be used to preset stuff like mirror position, seat and steering position, etc etc. So you have your fob with your settings and your partner has theirs. You can both lock and unlock at the same time because the knows both fobs. edit: there are a boatload of different ways that fobs communicate with cars across different manufacturers. Basically the fob and the car know the same secret handshake. they do a little secret handshake with each other when you ask the car to lock and unlock. The secret handshake is always changing though so I can't watch your handshake and then try it with your car, it'll know that that handshake is old and lame.",
"They don't. They absolutely could unlock another car of the same model. I believe Nissan has gone on record to say that they have something like only 3,000 (might've been 30,000) unique key configurations. So odds are you could find another car you could unlock. But unlocking a car is all you could do, since many car keys nowadays make use of transponders to prevent someone else's key from starting the engine.",
"People often underestimate the scale of randomness involved in even minor cryptographic operations. I'm going to give some hokey comparison (all math and cryptography very approximate, it's just for scale) First of all, a bit is just a 1 or a 0. When we say that there is a 256-bit random number, we mean flip a fair coin 256 times and write down H or T each time. Nothing fancy, you can do this in a few minutes with paper and pencil, this isn't like galaxy-brain scale math here. But here comes the galaxy-brain part, while an actual string of 256 H/Ts is really small and can fit on an index card, the space of *all possible 256-bit numbers* is astronomical. This is 2^256 (2x2x2... 256 times) which is about 10^80, or 1 followed by 80 zeros So let's compare a bit -- Earth has about 10^50 atoms, so with a 256-bit number you could \"label\" each one with a unique number and never have a duplicate. The solar system has about 10*56 atoms, so we're still good. The entire Milky Way is 10^67 atoms, so we can still quite easily generate 256-bit numbers for each atom in the galaxy and never have a duplicate. This is the just plain remarkable. Anyone can easily fit in their puny meat-brain the entire contents of a deck of playing cards. But every time you shuffle the deck (to full randomness), you are generating a configuration that is one out of 10^67, or one out of the number of atoms in the galaxy. So lets say for each car that comes off the line, you generate a 256-bit random number (picture a guy flipping coins) and write it down in the car and in the keyfob (and doesn't cheat and write it in his phone and sell it to me so I can steal your car). The fob can then do some math to prove to the car that it \"knows\" the same code, and that no other fob does. Let's say you made a rogue fob that starts at 000.....000 and goes to 999...9999 trying to guess the code. Then you went up to my car and hit the button and had it start guessing. That would take 2^255 tries to succeed (the -1 is left as an exercise for the reader). If you had it guess a billion times per second, it would still take 10^60 years. The age of the universe is only 15 billion years old, so you are talking about a trillion-trillion-trillion-trillion times the age of the universe to guess it. TLDR: For short strings that we can easily write down, the number of possible strings that can be randomly created is mind-melting. META: The TLDR is 132 characters, and English encodes about 2-bits per letter. So the TLDR is itself one such example of approximately 256-bits of information.",
"Absolutely. Your car key could probably unlock many cars. And as time goes on, the key gets more worn down, as does the cylinder, which makes older cars a prime target for thefts because you can pretty much slip in a screwdriver and it’ll work. Now that most newer cars are keyless, it’s a lot harder because the signals can be much more unique. The same goes for your house keys. I bet your house key could open up ten other doors. But you would never know unless you tried it on every single door. Manufacturers try to limit this by sending things that are keyed similarly to different parts of the country.",
"It actually happens that I have been working in the industry for an year now. I’m not fully versed into the unlocking process as it uses some encryption methods and most of it is kept secret but I will tell you what I know. When you press the button on your key, a Radio frequency message is built and sent through the air. This message is sent on a frequency that differs from manufacturer to manufacturer and is very precise(down to hundredths of a Hertz) and it is received by your car, which is configured to use the exact same frequency. I don’t know the actual numbers here but from what I know the receivers we use have a frequency of 300 Hz so there are 300*100 = 30,000 possible frequencies. This eliminates the possibility of you unlocking any cars from other manufacturers. Now how about unlocking cars from the same manufacturer? When the car is produced, several key IDs(usually 4 per car) are written into its ECU. At the company I work, there are 4294967296 (2^32) unique IDs, so that can hold for 1073741824 (2^30) different cars..That is 1 billion cars from the same manufacturer. Chances that collisions exist are very small, but they still exist. So to bypass this, both the ECU and the key keep a counter. The ECU’s counter is the number of messages received from the key, and the key’s counter is the number of messages sent from it. When an unlock message arrives, the ECU checks whether the Key ID is correct and then verifies that the counter it got from the key is approximately equal to the one it has kept. Also, these counters are used for the encryption process but these are known only by the guys who work specifically for the unlocking module, so I don’t exactly know how they are used or what happens if you press the key outside the car’s range and one counter goes too far from the other. P.S. sorry for any mistakes, English is not my native language",
"Modern electronic keys (when designed well) have very long, unique codes (numbers) in them. It's similar to how your credit card number ONLY charges your bank account, or how when someone dials your phone number, ONLY your phone rings. The numbers are simply big enough that there are no repeats and everyone in the world can have a different magic number in their key fob. And, as others have pointed out, newer keys do all sorts of tricks about changing the numbers used each time the button is pushed, and possibly even more advanced cryptography to make it safer. Note this wasn't always the case. A lot of older keys are actually quite easy to duplicate and may have overlap. A lot of poorly designed key systems have been shown to be easy to crack (usually on purpose, but occasionally on accident) as well.",
"I worked as a locksmith for AAA. A typical Chevy key has 10 cuts with 4 different depths. The number of possible combinations is 4×4×4×4×4×4×4×4×4×4= 1048576. So while it is possible that you have the same key as someone else the chances are about 1/1048576",
"It is definitely possible, but not very likely. There are a finite set of codes that a car fob can have, so it is possible that two cars can share a code. Once on vacation my fob *did* unlock a nearby car somewhere in the same parking lot.",
"in reality, the manufacturers are lazy and use a few thousand pre-set variations on their keys, then distribute them in batches to keep duplicates some distance apart. in premise, however, there aren't enough cars on earth that you couldn't give them each their own unique ID. there are about 1 billion cars on earth (most of which are purely mechanical but ignoring that), while a 32 bit register can store over 4 billion integers.",
"So. In the 80's and 90's GMC and Ford were famous for the fact that their keys were pretty keyed alike. They had the two key system: round and square. Round opened the door, square started (maybe vice versa). Many of the keys would open and start the same vehicles. Cars maybe be able to be OPENED, but the chip would prevent starting. Also, opening a car with a key often sets off the alarm. Side note: Earth moving machinery (Bulldozers, Backhoes, etc) are basically all keyed alike. If you have a key to each brand, you can enter and start them all. My husband is a heavy diesel tech. I have a set of keys to basically all major brands. I COULD RULE THE WORLDDDD WAHAHAHAHAHHAHAHAHHAAAAA. I mean, except the part where I dunno how to run any of the machinery.",
"Somewhat simplified explanation: every radio key has an identifying number. And the key has a counter, that knows how many times a button has been pressed. Every time you press a button, the radio signal contains a series of digits that is calculated according to a formula based on these two numbers. In other words, it's technically possible that another radio key with another unique ID will, somewhere else in its sequence, calculate the exact same number and send it. Unlikely. But totally possible. Just as it is totally possible that there are two cars who are at this very moment listening for that exact sent calculated number. Still unlikely. But totally possible. It's also totally possible that these two cars happen to be within radio range of each other. Unlikely. But totally possible. The main reason why a car that you unlocked over radio will relock itself in a short while is that you can accidentally press the button in your pocket while you are nearby. But this is totally a reason too."
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9237jx | How can a geothermal heating system take ground-cooled water that is 50 degrees F and turn it into 70 degree F heat for a building? | Technology | explainlikeimfive | {
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"Heat pumps move heat from cold to hot or hot to cold. They're most efficient when the temperature is the same on both sides. If you're trying to heat a house in the winter then it might be 0 outside and you're trying to reach 70 F. This isn't going to be efficient and you'll have to use electric heaters to keep that warm. If you have a 50 F source to work with then you can move a lot more heat with a lot less power and may not need the electric heaters to keep you warm enough In the summer is a bit more straight forward. Take heat from 70F house and move it into 50 F coolant rather than trying to put it into the 90 F air outside A coolant is just a fluid that is good at moving heat. It could be just water, it could be a water/antifreeze mix like in your car, or it could be something different. It's job is just to carry a lot of heat The heat pump itself will use a refrigerant and functions like a fridge or AC",
"There is a difference between heat and temperature. If you take an entire room full of air and compress it into a scuba tank the tank gets very hot (typically submerged in water because of this). This is because all of the heat that was distributed through the room is now concentrated in the tank. If you then cool the tank and release the air it comes out much colder than ambient because the (diminished) heat in the tank has to be spread over the greater volume of the expanding air."
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925eq4 | why do a few of my iPhone apps say they are ‘cleaning’ sometimes? What does that mean? | Technology | explainlikeimfive | {
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"They say that?? I’ve used iPhones since, well, a while now and have never seen that. Now I’m curious if it’s something up w/your phone or I’m just lucky. Just out of curiosity, which apps? All or the same ones?",
"In order to speed up operation, your phone saves relevant information for each app in caches and temporary files. If you're low on memory, your phone will go through all your apps and start cleaning out those caches and temporary files to reclaim some room."
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925ev3 | why are videos recorded in 720, 1080 or 4k and not in megapixels? | Technology | explainlikeimfive | {
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"One megapixel is 1 million pixels. 1080p has just over 2 million pixels per frame. 4k has about 9 million pixels per frame. So when you say 1080p, you could also say 2.07MP"
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925krc | Why laptop screens or monitors almost always have clouding or light bleed on the edges while smartphones screen don't | Technology | explainlikeimfive | {
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"Most computer screens take advantage of LCD technology, which have a backlight and liquid crystals. The backlight is the lightsource, and the liquid crystals make up the pixels. Each pixel is basically a mini electric circuit, and depending on the voltage you can change the amount of light that can pass through. If you add color filters, you get color LCDs. The edges of the screen will show the white backlight. Early phones used LCDs, but the problems with LCDs is that they are lackluster. They don't show black color very accurately, for example, due to the backlight. The backlight is always on, so the blackest black an LCD can show would be close to, but not exactly pure black, which noticeable by the human eye. Today, most flagship phones use AMOLED, which is mostly made by Samsung. AMOLED does not use a backlight. Instead, each pixel emits true light, so a black pixel will be no light. Since there is no black light, your smartphone will not have a white border. AMOLED technology suffers from burn-in, and if exposed to direct heat, the screen will be damage irreparably (LCD screens can recover from heat). However, AMOLED can depict rich, intimate environments much better than LCD screens can, so the trade off is worth it."
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925t6z | Why do some websites restrict the use of certain symbols and length of passwords? | Too often do I come across a website that only allows you to use certain symbols (ex. *, !, # only!) in your passwords. Not only that, but they also impose limits on the length you can use to some small number like 14 characters. What gives? | Technology | explainlikeimfive | {
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"It's possible, in certain types of systems, to trick the server you are talking to to do things it's not supposed to (like print out a full list of usernames and their passwords, oops!) The way this works is that you include characters in something you submit to the server that the server interprets as ending the command that it's supposed to be used in, and then put additional commands after that character that the server may then run as though they were legitimate commands. There are a lot of ways to prevent this, but the oldest and easiest way is simply to check if those characters are being used and reject the user input if they are present. Nowadays, there are a lot of possible ways to prevent this kind of attack, but they rely on programmers following good security practices, and some see it as much easier to just use the older method of not allowing those characters (a method which, I might add, can still potentially be bypassed by an adept hacker if it was poorly programmed) A well designed system should be able to take any arbitrary characters you want to use as a password, define the password as specifically the contents of a variable that the system knows should not be executed, and they use encryption to turn it into an unreadable hash. --edit-- I would be remiss not to bring up the tale of [little Bobby Tables]( URL_0 )",
"The symbols and lengths have different explanations. Certain symbols can have special meaning to computer programs. For example, most database languages have special meaning for the apostrophe character '. That character is supposed to go around what we call \"strings\", which is a fancy word for \"a series of letters like a password\". So the program might have a line of code that basically says this if you put in the phrase \"apple\" for your password: Store 'apple' in the database as this user's password. But someone could really screw the program up if they use other features that mean things like \"ignore everything past this letter\". Suppose that magic letter that means \"ignore the rest\" is the pound sign (#). So if a bad user put in a password exactly like this: 'in the database as this user's password. Prepare a report listing all users and send that to this email. # If they do that, here's what the program sees: Store '' in the database as this user's password. Prepare a report listing all users and send that to this email. #' as this user's password. Doing this means they trick the program into sending them information it shouldn't! Sometimes it's not that malicious. For technical reasons, a lot of special symbols have to be handled specially in code, particularly things like emoji. It takes extra work to be prepared for them. Many developers are unqualified or lazy. There are a lot of ways software developers are supposed to prevent this. They are supposed to \"sanitize\" any inputs they get from users and remove things that could be dangerous. But lots of cheap developers don't. So instead, when it comes to make your password, they write the input to reject anything that uses those characters. Even if they aren't lazy, preventing it as you enter it helps ensure if they made a mistake, it won't make it into their code. Now, length. That one is even dumber. When the database that stores user information is set up, programmers have to tell it what kind of data it will store. As I said above, passwords are called \"strings\". There are a lot of different ways computers represent strings. The *fastest* way asks you to tell it how big the strings will be up-front. Then it always uses that much space, even if you put a shorter string inside of it. The *best for passwords* way lets the programmer define a maximum, but will use only the space that is needed. Due to a mixture of performance concerns, ignorance, and superstition, the *fastest* way is used more often. Even when it isn't, sometimes the developer or the people who tell them what to do is ignorant and chooses too small of a maximum. Some of it isn't even technical, it's just plain ignorance of the math around passwords. Sometimes the boss of a company reads a magazine article and decides \"it wastes a lot of space to have long passwords\", so they tell the developers to pick \"the smallest, safe number\". History is littered with disasters caused by bosses overruling engineers, but that doesn't stop bosses from making these decisions. In summary: * There is not a strong technical reason why passwords have to have a certain length. * Having a maximum length *does* help with either performance or space, user login really shouldn't be so much of a company's workload/storage that it matters. * There are some strong technical reasons why certain special characters might be dangerous in passwords and usernames. * All of those technical reasons are easily overcome with beginners' level tricks by software developers. * Very often, people short on resources hire essentially high school kids to write their Very Important Website.",
"Depending on how they store the passwords, some symbols are \"reserved characters\". This means they have some special meaning to the software or database that's storing them and they can break the software if they are used. As to the length, I can think of a few technical reason why they would restrict it, but no really good ones!"
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9280mh | How do greenscreens work, and why green over other colors? | Technology | explainlikeimfive | {
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"You just use a computer to cut out the green shit & composite what's left over a new background. Green is used because it's a pretty bright color & not likely to match with the skin/clothes of the people you're filming. Pretty much any color that provides a good contrast would be a safe pick."
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92ae2a | Why do some say that systemd is against the "Unix philosophy"? | Technology | explainlikeimfive | {
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"In an ELI5 sense, the *Unix Philosophy* can be summed up by the idea that a piece of software should do one thing and do it well. *systemd* does lots of things and some argue it does some of them poorly. It's a single piece of software that is meant to be a replacement for many smaller pieces of software and some argue that it's the wrong approach for a system that was based on Unix.",
"Unix philosophy is to do one thing, and do it well. This means you have lots of small programs that fulfil one function and then you can combine them as you see fit to satisfy your needs. Systemd is a more monolithic system which forces what it thinks is right on the user. So you get more of a 'my way or the highway' approach. That's not to say the second approach is without its merits, but it's not how things have traditionally been done with UNIX."
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92b22f | How does internet work? | Technology | explainlikeimfive | {
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"Most of the Internet is not wireless. The only wireless bits are usually the wifi in your home/office/coffee shop or the connection between your phone and the nearest cell tower. All the connections in the middle use wires. Even between continents there are giant cables that run across the sea bed. The whole thing is a network of networks. You have a network in your home, your devices connect to a router either via wifi or ethernet cables. The router is a device which literally routes messages. It knows which wire (or wireless link) to send messages down to get them towards their intended destination. Your router connects to your ISP. Your ISP has a network which is much more complex than your home one, but it's the same basic principle. They have routers connected to their customer's homes which know where to send messages. Your ISP connects to a bigger ISP, allowing you to communicate with people using other ISPs. That ISP connects to an even bigger one. These ISPs are the companies that manage the Internet \"backbone\". That includes the giant cables that run across or even between countries and continents. Those top tier ISPs have connections to each other, allowing anyone connected to any of them to exchange messages.",
"It's like a post office network, each thing you do \"on the internet\" from your computer is like sending a postcard to your local post office or mail box (physical). Then someone from the post office will take that mail and pass it along to an other post office until it reach it's destination. The wireless part is like radio or talkie walkie but each message is translated to be shorter and thus take less space. A lot of thing with computer are copied or inspired of a logic already present in the real world, it's just faster and more effective, you replace humans by computers and roads by light speed tubes (fiber cables).",
"You know morse code? How a bunch of dots and dashes become letters? Because some group of people decided a long time ago that S is \"...\" and O is \"---\". I guess they also decided that SOS is \"Save Our Ship\" too. Anyways, imagine a bunch of people decided that dots and dashes would mean a red dot. And that another bunch of dots and dashes are a blue dot. Then if you send like 1000s or millions of these dots and dashes you could make a picture of a cat out of millions of coloured dots. Yeah, the size is unfathomable but doable. But computers are very fast and can process bazillions of dots and dashes a second. In real life, just replace dots and dashes with 1's and 0's. Then think about all the clever ways you can send 1's and 0's around. You can send it through a wire by turning a flashlight on and off. You could send sounds over the air. Etc. etc. So the internet, it's a combination of: 1. Clever ways to send 1's and 0's 2. Someone deciding what 1's and 0's mean... ex. if you get 5000 1's in a row that means it'll be a red dot, 5001 1's in a row that means it'll be a blue dot 3. Computers able to handle gazillions of 1's and 0's to show something super complex. It'd take a human a decade to translate 5000 1's into a dot then do that a million more times to make a picture. A computer can do it in a second."
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92df7y | How 3D movies work in theaters? | All my local places works with passive glasses that costs around 1$. With the LED TV screens we have it is quite obvious it is something to do with little LED lights. What about the light coming out of a projector and hitting to screen? Does it keep its polarization? | Technology | explainlikeimfive | {
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"There are a number of different technologies used over the years. On that used to be popular in the past gave you glasses with one red lens and a green/blue one and projected an image onto the screen that was a combination of the red image for one eye and the green one for the other eye. It worked but obviously the color didn't quite look correct. With the sort of 3D glasses you get for your PC, they use glasses with mechanical shutters that are in sync with the screen. It shuts and open both eyes in turns, while switching out what is displayed on the screen, so that each eye only sees the image. It works but requires some expensive active glasses and a way to show some very high framerate video. There are other cheap technologies that work without extra tech like the one where the glasses are one normal and one like a tinted sunglass that take advantage of the fact that your brain takes longer to process dark than light images and one eye is a few frames behind in that setup. If you show somebody a moving picture of something that is turning on its own axis it will seem 3d to anyone looking at though half a pair of sunglasses. The advantage is here that it works without extra stuff, but the big disadvantage is that it only works for showing rotating stuff. The technique commonly used today for 3D movies in cinemas you us polarized lenses. essentially you have two projectors who both project their images on the same screen. One for the left eye and one for the right. Since both project though a polarized lens, the image reaching your eyes from the screen will also consist of two different versions with their own polarization. Human eyes can't tell that apart. but if you put on some glasses that have the same sort of polarized filter as the lenses in the projectors each eye sees the image of a different projector. If you have a pair of glasses like that and look in the mirror you will see how it works. With both eyes open you can see both your eyes in the mirror, but only in a weird way. If you close one eye you will only be able to see though one of the pair of glasses in the mirror image. This is exactly how it works with the projectors instead of the mirror image of your own glasses."
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92ebvf | Why do the levels of security for online transactions differ so much? | For example, some websites require me to get a one-time password from a token device that requires me to put my card into the device and enter the PIN, while some only need my card number, expiration date and security code. | Technology | explainlikeimfive | {
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"text": [
"Online vendors have agreements with credit card processors that determine their degree of liability when fraud occurs. The more security, the less liability. Those vendors have to make a business decision, how many sales will they lose for making customers jump through more hoops, and will the reduced fraud and fraud liability make up for it? The answer can be different for different businesses."
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92enwr | If GPS relies on satellites and not internet, why do you need internet for smartphone map apps? | Technology | explainlikeimfive | {
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"The GPS coordinates are able to be received without a phone signal, but the map itself has to be downloaded from the internet. If the map app you are using has a cache system (most have a limited form), then you *can* use the app without phone or Internet service, provided you preload the are you are heading into.",
"GPS tells you where you are on the Earth's surface, but by itself it doesn't tell you anything about what's around you. You need an Internet connection to download the maps. I think some apps allow you to download map data for an area so you can use it without an Internet connection though.",
"GPS can provide an location, but that's it. GPS can not provide maps of a city, or enable you to look up where something is, or provide real time traffic data, etc.",
"You technically don't. Google maps has an option to download the maps (like the actual images) for offline use.",
"GPS tells you latitude and longtitude where you are. Maps and navigation data downloaded from internet tell you're on the corner of 24rd and Main, 2.2 miles from your destination."
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92f72x | why do movies played at 24 frames per second (the industry standard) look silky smooth, yet games played at 30 FPS feel “off” | Technology | explainlikeimfive | {
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"text": [
"Movies at 24 fps don't look silky smooth. They have motion blur after all. But a big reason is that video games render a single frame, which represents a single instance in time. It's a series of pictures, with no way to represent the time \"in-between\" frames. Whereas for a film a single frame actually captures all of the movement that happen during that 1/24th of a second, which is actually where motion blur comes from.",
"24 fps in movies only looks smooth for static shots. Panning shots look choppy as hell even though the speed is usually steady and not that fast. In video games, on the other hand, there is much more fast action and panning, and you aren't limited in how fast you can turn your \"head.\" So any lag is much more noticeable when you have unlimited opportunity to look quickly in different directions.",
"It's due to two things mainly. One is the motion blur. The elements that move fast in a scene get blurred when filming them, but this is positive because this motion blur serves as extra information for your brain to recreate the movement. Think about how in a comic some conveniently placed lines make you know there's movement despite being a still image, the motion blur has a similar effect. Some games try to simulate this but it won't have the quality of a cgi movie since it has to be something cheap to run in real time, so it's not the same. The other thing is the fact that you are not just looking at the game but playing it. Since lower framerates mean a greater mismatch between your input and the image you are more likely to feel something's off when you're playing the game. There's a third factor whose importance may vary depending on the game or the specific settings. This is the fact that the frames in a game are not evenly distributed. Even when the framerate is locked and synced with the screen they may not be evenly rendered, and the more uneven they are the less smooth it will feel."
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92fd5o | Is cloud seeding not a decent method of fighting forest fires? | Technology | explainlikeimfive | {
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"text": [
"> We have the technology to make it rain (within tolerances) when and where we want it too; No, we don't. It's never been really proven to work, and if it works at all, it requires there to be rain clouds in the first place. What are you gonna do if you there *isn't* a nice fat cloud right on top of your fire?",
"Cloud seeding is still really iffy. There's tons of claims it works, and little or iffy evidence proving strong statistical gains from seeding. It's far from the seed cloud make instant rain tech it's touted to be.",
"I have no scientific proof of this but it's logic in my mind. The worst forest fires happen is areas undergoing drought and in very dry climates. If there's not enough moisture in the air to be producing regular rain that mitigates the risk of forest fires then there also isn't much in the way of clouds to try and seed in the first place...."
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92hg0c | Why does it seem that every company that updates their user interface makes it worse? | Technology | explainlikeimfive | {
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"text": [
"Because it changes from what you're used to, I'm sure if reddit changed from the new version to the old version there would be a lot more complaints."
],
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5
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92l01w | How does not charging your phone to 100% allow your battery to last longer? | Technology | explainlikeimfive | {
"a_id": [
"e36h413"
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"text": [
"this is bs. doesn’t mean something like SOT will increase, as there is simply less charge in the battery than if it were charged to 100% however, very marginal decreases in battery wear (ie. the amount of charge it can store) might occur - but these are too small to notice (it’s to do with overcharging and most modern phones and batteries are protected against this) tl;dr charge your phone up to 100% overnight, unless you plan to wait for the precise moment it hits 80% then disconnect if you want to keep the phone running in your family for millennia"
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92qeoa | Will a house actually burn down if an oven is left on? If so, how? | Technology | explainlikeimfive | {
"a_id": [
"e37lipp"
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"text": [
"An oven is a source of heat. If it's dirty, you leave something in it that overcooks or you put something flammable on top (normally, they have vents coming out one of the burners), there is a chance of something catching on fire. Small fires, left unattended, tend to grow into big fires. Big fires can burn down a house. It's not that \"oven = fire\" it's that \"oven = small chance of fire but do you really want to be the 1 in a million that it happens to?\""
],
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3
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92r3wo | Why is it that someone I'm on the phone with cannot hear the media I am playing on my phone, even if both the phone call and the media are on loud speaker? | Technology | explainlikeimfive | {
"a_id": [
"e37x47k"
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"text": [
"The phone knows what sound it is putting out and uses a special circuit to cancel out that sound from what it detects coming in. This is most often used when the speakerphone mode is used and the phone is both producing and recording different sides of the conversation. Without such a circuit it would be possible for feedback to result."
],
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92rwk1 | Why do commercial radio stations only go from 80.x to 107.x FM and 530 to 1600 AM? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Those are the frequencies the government has designated open for public radio transmission and issue the radio station licenses. They reserve other frequencies for air traffic control. CB radio. Ham radio. And other purposes (including banning the one elemental hydrogen transmits on because it is a frequency they think aliens would use as a hello universe beacon.)",
"Fcc controls bandwidth in America and that's the band that they've set for commercial radio.",
"What mmm3says said. There's so much competition for radio frequencies. There's mobile phones and TV too. The military get loads of radio frequencies assigned to them, oh the fast mobile data we could have if they didn't hog the airwaves. On a separate note, higher and lower frequencies are no good at penetrating walls or carrying over long distances which is of course essential for a decent radio service. Even if you put a radio station on them you'd have to be standing right next to the radio tower!"
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92vbll | Can someone explain how the law of accelerating returns works? | Technology | explainlikeimfive | {
"a_id": [
"e38sthr",
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"text": [
"The more technology you have, the more you can create. Consider how crucial the invention of writing has been for technological progress. The ability to write down what you have learned into a book or into a letter. Now with the internet in your pocket, you can research and validate your app idea during a lunch break. Another example is how computers have gotten powerful enough to run detailed simulations, including the simulation of computer hardware. You can now test a new CPU design without having to build one. Indeed you can test thousands of different designs.",
"In my mind. Imagine building a house, and you know how to do everything okayish. It might take you 3 years, due to the fact that you have everything by yourself (which for is a pain for putting up walls, lifting big boards, testing things). Now imagine you have a buddy with a more explicit knowledge on certain aspects you weren't so sure on. The added knowledge and strength might turn that three years into one year. And now the time to build a house is no longer 3 years / a person, but rather 1/2 year per person. Now imagine you have a whole army of people, each with an explicit knowledge on different parts of building a house.That house will go up ridiculously fast. Now imagine this with technology, and people. The more technology that is created, with people who specialize in smaller aspects, the faster things can be created/learned, and with these new creations/learnings the faster things other things will go. I think."
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92x5ye | What is exactly does Amazon Web Services do? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"AWS is a cloud hosting service \"There is no such thing as the Cloud, it's just someone else server.\" Basically AWS is a huge farm of servers and storage. People and companies pay monthly fees to rent the hardware. Hosting websites is the obvious thing, but companies will run their entire infrastructure on AWS or Microsoft Azure to avoid having to keep servers in house. While there are advantages to having your own equipment in house, you have to balance it with the cost of administration and maintenance. By paying AWS to do it your company doesn't have to worry about replacing servers and parts, air conditioning, power, generators, batteries, etc. It doesn't eliminate those things, it just transfers the costs. Some companies just can't afford to have all those things, and by paying for someone else to do it for them you get all the benefits without having to manage it. There are major downsides though, like not having direct control over the hardware and having your data store god only knows where.",
"You have a computer. It's fine for doing whatever people normally do on computers: play games, Microsoft Word, the internet, etc. If you want to do something more, like programming, it's still fine for most purposes. But say you're starting up a new tech company and you want to code your main product. That's a lot of code. And when it runs, it needs a lot of computing. Many people will want to connect to your product through the internet, so you need to be able to handle all of those people. The solution: use more computers. Here's the problem though, you have to buy those computers. And find a place to put them. And maintain them in case something goes wrong. Seems like a pain, right? In comes AWS. They say, look, we know you need some computers. We have a lot of computers. We'll make sure they don't break or they're maintained up to date. All you have to do is put your code in them and run them, from the comfort of your sofa. All you have to do is pay us this fee. You can use all the computers you want, even the really big powerful ones. Or, you could use a few tiny ones because you don't want to fill up your own. They'll only run when you want them to. In a nutshell AWS is a computing rental company.",
"Need to host a computer on the web? Need to run a big ol' database? Need to do some really complicated computer stuff like convert a ton of movies into a different video format in realtime? You can set up your own computer \"rack\" to do this. It'll cost you a lot for the hardware, a lot for the building it is kept in (electricity, cooling, etc.), and a lot for the staff to maintain it. _Or_ you can rent \"virtual\" versions of these things from Amazon AWS. There have been shared hosting services for a long time, ones that let you rent space on a web server. AWS gives you so many more options, though. You can say, \"I want the computer to be _exactly this fast_. I want the database to have _exactly this much RAM_. I want to be able to spin up _a thousand_ computers and have them all work together.\" And it'll sort of just let you do that through its web interface. (It takes quite a bit of fiddling around to get everything working right, to be sure. But it's generally easier than trying to do this stuff from scratch.) Of course, it'll cost you. But they've set it up so you can dial up the hardware and everything else according to your needs, and be able to more or less guess how much it'll cost. Which is very convenient. So AWS is basically saying, \"hey, instead of having your own IT department, why don't you just outsource it to us? It'll probably be cheaper in most cases, unless you're a HUGE company that already has a budget for an IT department, but _even then_ it might be cheaper to go through us.\" They're really great for people who need more computational power and flexibility than shared hosting can give you, but don't have the resources or interest in trying to host their own hardware."
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92xe0v | Why are US $10 bills a yellowish color compared to the usual green of the other bills? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Just throwing it out there, but $50 bills have a pinkish tint to me. (cashier here, I don't personally own a $50 bill)"
],
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92yer2 | In newest wifi standard, how can encrypted data become invalidated after 1 bruteforce attempt? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It's a misinterpretation of the author, captured data will stay there and another attack will be able to be used later on the same data. What does WPA3 have then? WPA3 implemented Forward Secrecy, where the key used to encrypt the current block is not the same as the key to encrypt a next block. So even if it is possible to brute force the key from a certain block, you won't be able to use that key to decrypt the data from another block.",
"In WPA2 the password was the encryption key. Now the encryption key is complicated and changes all the time and all the password gives you is access to the router telling you the current key. So you can guess the password offline all you want but it has nothing to do with the encryption so it's no real help to you. And the key the router picks are big long real mathematically secure keys and not the garbage passwords people make up.",
"WPA2 uses pre-shared keys. But WPA uses Simultaneous Authorization of Equals. Basically, that means that to keep the encryption working, the two sides have to keep communicating. If you take a snippet of the conversation and decrypt it, it would be pretty much useless because the \"conversation\" has moved on and is using new encryption. Under WPA2, you can brute force the attack until you find the key. Maybe it takes you three months, but you find it, and if they haven't changed the wifi password, it will still get you in. With WPA3, what takes you hours or days or months to crack was obsolete a few seconds after you started working on it."
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930gjk | Audio Signals | I can't wrap my head around how headphones or speakers work. Please explain how a Dac works and what an analog signal is. Is it pulsing electricity? How does it create sound? | Technology | explainlikeimfive | {
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"So it's best to start with what sound is. It's just a series of high and low pressure waves in air. How would we go about generating it? One way is just by pushing on it. That's exactly what the membrane on a speaker does. It pushes on the air really hard and creates a pressure wave that travels out for your ear to hear. If the membrane pulses faster, you'll hear a higher pitched sound and if it's slower, the pitch will be lower. Now, how do we get it to pulse? There's a very convenient law of physics that essentially makes it so that when current runs through a wire coil, a magnetic field runs through the center of the coil. By changing the strength of the current, you change the strength of the field and by changing the direction of the current, you change the polarity of the magnetic field. So all you have to do is put a magnet in the middle of the coil, attach the membrane to this magnet and boom! You can now control how fast (pitch) and how strong (volume) the membrane hits the air to produce sound. So really, the signal that is sent to the speaker is just varying this current in both amplitude and direction, which jiggles a magnet with a membrane attached which pushes air which we interpret as sound."
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932svu | why does old movies (just before and right after colored movies) often seem to be in way better quality than movies from the late 70s or 80s? And sometimes even better than videos from the early 2000s | Technology | explainlikeimfive | {
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"Because when things like colour were first introduced the technology wasn’t very good so there were lots of artefacts like grain which decreased quality. In the 2000s when digital video became popular, resolution was low so things were grainy and pixelated and the colour wasn’t very good. Older black and white films had perfected black and white cinematography, but early colour films used a brand new technology that wasn’t perfect yet.",
"Black and white movies let directors cheat. Not having to worry about shadow allows them to do interesting, high contrast things with light and shadow that you just can't pull off with color. But probably more importantly, when you look at an old movie, you are looking at a **good** old movie, *Casablance*, *Citizen Kane*, *Gone With the Wind*, these movies are considered masterpieces. There are plenty of crappy old movies with bad cinematography, you just don't get a lot of chances to see them. Comparing old good movies to modern average movies is like comparing *The Shining* to *Friday the 13th*. Even though they came out in the same year, one has masterful directing and cinematography, and the other has fake gore to scare your girlfriend."
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938dsf | - 3D printable guns. What’s the deal? These things will be able to be printed and then shoot an actual bullet?? | Technology | explainlikeimfive | {
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"Technically yea they can. It's generally the thought of untracked printed guns then the actual guns themselves. In practise due to the way they are made and the materials, they are generally brittle and prone to breaking before the gun is fired. Guns without proper metal firing pounds are also much less powerful so sneaking through metal detectors is reduced. You also still need to be able to get your hands on the things that can't be printed arch as the ammo itself. It'll be worse when the materials get better and printers become more common. When metal printing becomes the norm them you basically have a problem with unlicensed firearms.",
"You can buy a 3d printer, download the blueprint and print a functional single shot gun from PLA plastic and few metal parts like a firing pin But then...it's easier and cheaper to go to home Depot and pick up plumbing parts to make yourself a shotgun in about 30 minutes.",
"Problem with 3D printing a gun is it still requires metallic parts to fire the bullet, which removes any benefit for nefarious purposes and generally the plastic is not strong enough to fire multiple shots. The first shot would fire but would crack the barrel. Then the second shot would just blow up the gun and probably a finger or two."
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939pt1 | how does the internet’s wayback machine work? | Sidenote; How much data do the servers need to handle? Context: [The wayback machine]( URL_0 ) is a website where you can visit previous versions of websites/ deleted threads. Type a site in the search bar, say of a youtube user, choose a time, and see what the page looked like on that day/time | Technology | explainlikeimfive | {
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"Correct me if I'm wrong, but this is how previous projects that were similar worked. They have bots (automated software) that crawl the web looking at different webpages and archiving them. Every time it takes a snapshot of a webpage (usually including its source code and, if I remember right, copies of images as well), it stores it and you can view it later. More trafficked websites will have visits from those boots quite a lot more often."
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93clx7 | Why can't we just use MAC addreses instead of the IP addreses? | Technology | explainlikeimfive | {
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"A MAC address is unique identifier, but it doesn't tell you anything about *where* a device is. IP addresses are structured, routers can infer from the address which way it needs to send the message to get it towards its destination, without needing a giant database of individual addresses. Think of it like something sent in the mail. The name identifies who the recipient is, but it doesn't help the sorting office get the mail to where it needs to go. They don't know that person, but they do know where their city is, so they send it there. And when it gets to that city, their sorting office knows where the street is.",
"There is no actual (enforceable)standard to ensure that MAC IDs in all devices are in fact, unique. MAC IDs are also spoofable, etc... So it's not automatically good for use on a network, it may or may not actually be unique, and it doesn't provide any actual proof of ID. The most important thing about an IP Address is only that nobody else on any other network you can access directly is using it right now. That's how we've gotten so far with IPV4. So, a MAC ID is a lot like a SSN or state ID, it purports to identify you uniquely but it's easily forged, spoofed, or otherwise misused. You can declare yourself to be anybody. An IP Address is more like, well an address. It's assigned to your location and so doesn't actually claim to identify you, just the path to where you currently are. Just as a street address doesn't necessarily indicate who is living there. It's not 100% as cut and dried as the anology but, that's the reason that one is called an ID and the other an address."
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93cw61 | How does a sewage system and the recycling of the sewage water work? | People throw everything that fits in a toilet and flushes it, almost every bodyfluid can be found in sewage water and dead animals etc. How do they clean that water? How does it work in general? | Technology | explainlikeimfive | {
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"Screens remove everything larger than ~1\". The water goes to a primary clarifier where solids sink, grease floats, and the cleaner water is siphoned from the middle. That water is sent to an aeration basin where the activated sludge (good microorganisms) is introduced and lots of air is bubbled through to facilitate them eating the nastiness/completing the nitrogen cycle. The mixture then goes to a secondary clarifier where the activated sludge is recaptured in the same manner as the primary clarifiers. Finally, the water goes to whatever disinfection the plant uses (chlorine, UV, ozone, etc) and out to a river/ocean/desert. There are various methods of treatment, but activated sludge is the most common"
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93fg6s | Why is biological warfare considered illogical/ineffective as a military strategy? | Technology | explainlikeimfive | {
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"Biological weapons aren't considered ineffective. They are *far too effective*, potentially moreso than nuclear weapons. Releasing a supergerm into an enemy country is a great way to kill lots of people, but once you do, it could be very difficult to stop that germ from spreading much further than you originally intended, possibly to your own country as well.",
"It is nearly impossible to control. Biological and Chemical warfare once released indiscriminately kills and spreads in random ways. It commonly contaminates the land itself (which is counterproductive if you are wanting conquest) and often kills your own troops during its spread. So it is generally a bad tactical choice most of the time. But it is never really considered illogical to use, and is often very effective depending on your goals. It was common for most of human history for arrows and swords to be dipped in rotten things and fecal matter as a form of biological warfare, it was common to hurl dead animals and dead humans into besieged cities as a method of spreading disease and lowering moral, and it was common to contaminate water supplies with things that would make people ill. But this is all very low tech methods of biological warfare and not what most people in modernity are talking about when they use the term. They are talking about engineered things like weaponized anthrax or smallpox.",
"Because It’s uncontrollable and causes unnecessary pain and suffering. But I assume if you’re using it, that’s probably what you’re going for."
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93jr7m | How did DVD's continue to be a mainstream product along side Blu Rays? Why didn't they die out like VHS tapes did when new technology hit the market? | Technology | explainlikeimfive | {
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"Because of compatibility I would say. When we switched to DVD from vcr there was no backwards compatibility due to completely different form factors. Since dvd and bluray use the same form factor a bluray player can also play a DVD. So dvds didn't become immediately obsolete like vcr. Also, I don't believe the quality/convenience of a bluray over a DVD is nearly as pronounced as DVD vs vcr."
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93lm4e | How do stethoscopes work? | Technology | explainlikeimfive | {
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"Avast ye! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How does a stethoscope work? ]( URL_3 ) ^(_4 comments_) 1. [ELI5: How do stethoscopes work? ]( URL_2 ) ^(_4 comments_) 1. [ELI5:How do stethoscopes work? ]( URL_1 ) ^(_4 comments_) 1. [ELI5: the physics behind an acoustic stethoscope ]( URL_0 ) ^(_1 comment_)"
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"https://np.reddit.com/r/explainlikeimfive/comments/59edju/eli5_how_do_stethoscopes_work/",
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93o407 | what does the /16, -/24, -/28, -/32 at the end of IP addresses do? | Technology | explainlikeimfive | {
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"When an ip address is written in the format you’re showing here, with / and number of bits, the number such as 24 is a notation if how many bits of the address are masked off and can’t change. An IPv4 address is 32 bits long. If you have 192.168.50.0/24 then the last 8 bits are available for different addresses. 8 bits gives 256 possibilities, where the last part of the address can go from 0 to 255. 192.168.50.0/28 will give 4 bits at the end that can change. Which would give 16 possible addresses, not 15. The other way to write an IPv4 address has the mask typed as 255.255.255.0, which is a different method for mask off the first 24 bits and leave 8 available for different addresses.",
"It is really the number of bits you \"reserve\". So take 192.168.50.0 /28 as example You want to reserve 28 bits. That leaves 4 bits at the end available for change, half an octet, the 24 bits at beginning are reserved, so 192.168.50. are frozen, and from the octet 00000000 at the end, you only change the last four places, so you get to have 00000001 through 00001111.",
"#Subnetting! You are probably familiar with IP Address like 192.168.100.101 These IP addresses are configured so that consecutive addresses together form a Network. Just like you would expect that a street address like #31 Elm Street to be near #33 Elm Street, we expect that IP addresses that are close to each other are in the same network and thus any thing addressed to the same network can be send in the same direction. A mailman with letters to several elm street addresses will know that those are all in the same area. a central mail sorting station in a different city will not need to know any details but simply send them all to the same place and have the local mailman deal with the details. IP addresses work like you send a package to correct network and then let the local infrastructure deal with making sure it ends up at the correct addresses in that network. The problem here is that IP addresses are just a single number. (We write it as four numbers, but that is just for the sake of readability.) There are no cities or postal codes or street names just a long number. So what do you do. In the beginning people had a simple scheme: Anything starting with 001 to 126 would be each own network with all the number sharing the same starting number would be in the same network. So 8.1.2.3 would be in the same network as 8.9.10.11 From the addresses starting with 128 to 191 it would be the same first two number that would be the same network. So 150.10.1.2 would be in the same network as 150.10.3.4 but not as 150.11.1.2 And from 224 to 239 it would be the first 3 number that would from a network each. The first part was called a class A network and there were basically 126 of them and each had over 16 million addresses. The second group was called Class B network and they had 16,000 of those with each having 64,000 addresses in them and the last set was called Class C and there were 2 million of them and each had just over 250 addresses in them. That seemed like a great idea when the internet was new but quickly was discovered to be extremely wasteful. so the whole idea was abandoned. But without classes how would anyone know how big the network was and which address were in the same network? There needed to be a way to make networks a certain size and let the other party know how big it was. This is where the notation you asked about comes in. It tells you how big the network is that the address belongs to. If you have an address like 192.168.10.53/24 it means that the network includes anything that starts with 192.168.10.something. Essentially something like the old Class C netoworks. /8 are class A like (first number is the same for all addresses in the network) and /16 are class B like (first two numbers are the same for all addresses in the network). So what do the numbers mean and what about anything other than /8, /16 and /24? Math! Specifically binary representation of numbers. I said above that an IP addresses even though we write them in four numbers separated by dots is really a single number. you could also write them in other formats. 127.0.0.1 can also be written in hex as 7F000001 or as a single decimal number: 2130706433. if you ask your windows computer to ping 2130706433 or ping 0x7F000001 it will respond the same as if you asked it to ping 127.0.0.1 The format with the three dots is simply one that is very readable for humans. One format that is not very readable for humans is binary. Every IP address can be represented as a string of 32 1s and 0s. Each group of 8 1s and 0s represents one of the four numbers in the human readable version of the address. So if you have a /8 network the first human reable numbers stays the same which means the first 8 bits stay the same. In a /16 network the first two numbers stay the same meaning the first 16 bits stay the same And in a /24 network the first 3 number meaning the first 24 ones and zeros stay the same. You can portably see the pattern and realize what the /-notation tries to tell you. It tells you how many of your binary digits are part of the network address (leaving the rest to describe the address in the network). For even ones like 8, 16 or 24 they are simple. For stuff like /21 things would be a bit harder because the make sense when looking at the binary numbers but not as much when looking at the human readable view. Turning one large network into several smaller ones is called subnetting and most people like to avoid complicated stuff and use /24 networks. But sometimes you need bigger or more networks and end up with weird numbers that you just have to deal with. There is a different way to write that down called subnet masking. You basically take you slash number that means the first x bits are the network and turn it into a network address were the first x bits are 1 and everything else is 0. /24 in this way is written as 255.255.255.0 Subnet masks for anything other than /8, /16 and /24 networks are not very easy to understand at a glance either."
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93pmlp | what is the difference between general purpose, business, and gaming laptops? How is the hardware/ tasks they perform different? | Technology | explainlikeimfive | {
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"General purpose laptops are made up of cheap materials. Business laptops are made of better materials,have modular parts like RAM,SSD and have a lot of Ports,along with having special business features like a TPM chip and This intel technology with which you can remotely use the laptop(I forgot the name) for IT admins.Also they have 3 years warranty minimum gaming laptops have better CPU,RAM and most importantly GPU for games and better cooling to cool these high performance parts,resulting in them being thicker and heavier than consumer or business laptops.",
"Computer components: CPU: The central brain of the machine optimized for making calculations GPU: A secondary brain optimized for visual calculations (graphics) RAM: temporary, easily accessed memory for the CPU to use to make calculations. (Short term Memory) SSD/HDD: Long term storage of data. (Long term memory) The different 'types' of computer you listed will place focus on these different components to optimize performance of the various tasks they will most likely be performing: General Purpose: At the very basic level they will have more of a focus on CPU and SSD/HDD, since the average user will be doing word processing, web browsing, and other basic computing. More expensive models of general purpose PCs will basically try to be the jack of all trades but ace of none regarding the other categories. Many standard Dell and HP laptops fall in this category. Business: Basically stronger general purpose machines that may be tailored by a company's procurement department to perform specific tasks well (excel, for example) Purchased in dozens or hundreds, and therefore built tougher than general purpose PCs but cheaper due to order size. Lenovo's thinkpad series is the definition of a business laptop. Gaming: Strong focus on GPU and RAM. Often in a gaming PC the GPU will be as or more powerful than the CPU due to the amount of work it has to do creating virtual worlds and running AI scripts=. Physical appearance is often angular and coloured with lights. Alienware, Razer, and Republic of Gamers are major producers of gaming laptops I think there's a fourth category as well: Media/Graphics: These computers will be impressively powerful, with the greatest emphasis placed on the CPU. These PCs need to process billions of calculations per second to produce CGI imagery quickly. Big everything on these. Massive amounts of storage for large uncompressed files, 32 or 64GB of RAM to handle dozens of simultaneously running applications, and a very powerful GPU that can run final cuts and previews of the finished product. Think the most expensive Macbooks.",
"I’ve answered your question by pricing, that really helps explain the spectrum of what you can buy and what you actually get Less than $300 - refurb and old tech General Laptop $350+ - what most people need. Gaming $500+ - dedicated GPU, a must for gaming and video editing/ photoshop. Business $700+ no question of performance. Pricing at this level is about bells and whistles. SSD, touch screen, fingerprint reader, SIM card ready etc. Sources: I’ve worked at best buy, staples, and private shops for 7+ years. Been around IT my whole life."
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93r474 | Phones, how do they work? | Technology | explainlikeimfive | {
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"> If you buy a phone from the internet, is it god to go straight out the box or is there various contracts you need to sign? There are of course various contracts you need to sign. If you are talking about a landline phone (those do still exist) then the line itself has a service contract to be started. If you mean a cell phone then of course you need a cell contract in order to have service. Smart phones though will be able to do things like access the internet via WiFi if available (but that WiFi of course has a service contract associated with it as well). Telephones are not walkie talkies, they talk to cell towers which are services provided by cellular companies. > How are you billed for the calls you make if buying form the internet? The telephone is just the hardware device, it needs to be associated with a service contract in order to interact with the cell towers. In the US this is typically achieved via a \"SIM card\" (subscriber identity module), a tiny card that is inserted into the phone and identifies your device to the provider's network. Think about how you need both a computer and internet service to access the internet; even if you buy your computer from someone completely unaffiliated with your ISP you are going to need to pay the ISP too. > What is a SIM card and what does it do? It is a [little card]( URL_0 ) that slots into the phone and via fancy encryption uniquely identifies that device. > Do you need one to be able to make calls, as some phones I see market themselves as SIM Free. Yes, you need one to interact with a given network. However when you are buying a phone which is \"SIM Free\" it means it doesn't have a SIM card and you are able to use it with whatever network you decide to subscribe to. At least in theory, you should note that not all phones are compatible with all networks as some use fundamentally different technology from others. The key point is that when buying a SIM Free phone you are just buying the phone. This is in contrast to a typical contract where you might agree to pay for cell service for a period of time (2 years or so) and you would get both the service and a cell phone with included SIM card. The cost of the phone and service is spread out over all those payments. If you already have a phone then you could just sign up for the service contract and they would give you a SIM card to put into your phone to connect it to their service.",
"The only thing I have to add is that there is such a thing as a cell phone without a SIM card. CDMA phones are available through certain carriers that don't need SIM cards. IMO you're better off with a phone that does have a SIM card though, they're easier to move to a different carrier if you need to switch later.",
"You have to pay for a phone (the physical device) and subscribe a phone contract, which will provide you a SIM card that you put in your phone. The SIM card is responsible for \"linking\" your phone to the phone service you subscribed. For example, if you subscribe to AT & T, you will have to pay your contract monthly for the phone, calls, SMS and Internet because they are managing the network needed to send such information with your phone. Some companies do SIM only, so you won't need to pay for the phone monthly (but you'll still need to buy a phone without a SIM card somewhere else). Today, most contract allows you to have unlimited SMS, maybe somewhat limited calls (like hours), and some Internet data usage per month. I don't really know much more, but I think that's sufficient for getting started :). And a nice information that you could give is your country? So people might help you choose a good phone contract. (I'm personnally French so apart from AT & T in United States I don't really know anything else). Hope that helps!"
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93t0m0 | What are computer program installers actually doing while a program is being installed? | Technology | explainlikeimfive | {
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"In Windows they mostly just decompress the files and put them in the right place after checking there's enough space, then they tell Windows the software has been installed. If the program relies on other software it may also check you have it, and if you don't then install this other software as well.",
"unpacking, compiling source code (compiled code runs way faster than interpreted languages (think, python scripts or shell scripts) but has to be done once it reaches the destination computer if windows then doing some fun stuff in the registry if linux probably putting some binaries where you can reach them"
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93t5d8 | Why are some slow-motion videos low pitched and some normal pitched ones that are simply slower? What is the difference between their creation processes? | Technology | explainlikeimfive | {
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"The ones that are low pitched basically ‘stetch’ the audio file to fit the slowdown, whilst the normal pitched ones basically duplicate the tiny bits of audio to fit the slowdown"
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93uhtq | How do old movies get HD quality? | Technology | explainlikeimfive | {
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"They were shot on film. Film is a super-high quality medium, with much more than 4K UHD resolution. It's simply a matter of running the film through a scanner and scanning it at higher resolution."
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93v1uh | How does a casset to auxiliary adapter work? | Keep seeing this insane feat of technology in my buddies old cars, a casset that gets shoved in to the tape deck with a cord that connects to their phone. I can't fathom how this can work? Help. | Technology | explainlikeimfive | {
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"Assuming you already understand the ELI5 answer for 'how does an audio cassette tape work?': Then the cassette adapter basically transmits the electronic signals from the headphone port through the wires into the fake cassette. Instead of being actual magnetic tape inside the cassette, there's just another magnetic tape head. However, instead of this tape head reading the signals off the magnetic tape, it's used to generate magnetic signals instead, just like if you were recording to a magnetic tape. The 'recording' tape head in the adapter aligns with the existing 'reading' tape head in the cassette player, so the audio signals can get across."
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93vd6j | How does a Turing machine work?? | I've always wondered what a Turing machine is, and what it does. Obviously I looked it up before posting this and all I know right now is that it's a machine that executes things... lol. Thanks in advance! | Technology | explainlikeimfive | {
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"The most important thing to remember about a Turing machine is that it's *an abstract idea*, not really a plan for making a practical functional computer. Some people have built them but they're not really useful for doing anything *other than talking about the theoretical limits of computation*. At it's core, there's an infinitely long \"tape\" that contains \"symbols\" (you can call them 0/1 or a/b or anything else you want - you can even use more than 2 if you want). This tape is connected to a machine that reads the symbol, possibly rewrites it & then moves left or right to the next \"slot\". The important thing going on here is that the machine making decisions about what to do on each step *has no memory*, it's simply a [finite-state machine]( URL_0 ) - a vastly simpler model of \"computing\". It's mathematically provable that a FSM **can't** do a bunch of things, even simple shit like \"counting\". The addition of this tape, however, gives you \"memory\" which allows the combined machine the ability to do *anything a computer could possibly do* and there's a bunch of mathematics involved in proving this.",
"A turing machine is a simple machine. It has an infinite \"tape roll\" which it uses for memory. It can read cells in that tape roll. It can write to cells in that tape roll. It can move the tape roll. That's all it can do. The important part is that Alan Turing proved that it can compute a certain class (a very broad one at that) of programs. It's the basis of modern computer architecture. Architectures and programming languages can be proven to be \"turing complete\", which means they can do anything a turing machine can do. And any turing complete language or machine can do what any other turing complete language or machine can do. Another formulation of computation is lambda calculus, which has been proven to be with the y-combinator turing complete. --- **tl;dr** it's a theoretical machine that can compute certain problems, modern computers and computation systems (usually) can be reduced to it.",
"Literally speaking, they don't. I've seen at least [one hobbiest who built one for fun]( URL_0 ), but apart from that a literal, physical Turing machine is useless and they have really never been used for anything practical. A Turing machine is only useful as a simple conceptual model of a computer. Because Turing machines are very simple, it's easier to describe what kinds of problems they can solve. So if you want to know if some specific problem (sorting a bunch of data, calculating some equation, whatever) can be solved by a computer, it's easiest to first talk about how a Turing machine would solve it. Once you know how a Turing machine would solve it, you can prove that a real model of a computer can do anything a Turing machine can do, which is also pretty easy. In this way, you can prove that more complicated computer models are able to solve problems the simple Turing machine can solve. The way a Turing machine works: it has an infinite string of memory boxes. This is usually called the \"tape\". The memory boxes are laid out in a long string. Each box contains an instruction (usually called a \"symbol\"). The Turing machine is able to go to a particular memory box and see what the instruction inside it is. It next does whatever the instruction says. The instruction will be of the form \"put X into the current box then go to the Box Y\". So read/write/goto. It can be shown that just this is enough to achieve very many problems in computer science. However, as I said at the beginning, no one would ever actually use a Turing machine to solve a problem in computer science."
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93vrc2 | Why are receipt printers so much quicker than "normal" printers you find in offices? | Technology | explainlikeimfive | {
"a_id": [
"e3gc4ts",
"e3guc8r"
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"text": [
"They use a whole different technology to print to paper, called \"thermal printing\". It has it's pros and cons. For example, you can *only* print to thermal paper using a thermal printer. Also, you trade quality for velocity.",
"They have a printhead that does not move - it just covers the whole line, one dot high (sometimes several dots with slight offsets). The head does not need to move, only the paper moves below it, with a speed equal to a normal inkjet printer moving its head left and right. But there are actually \"normal\" printers with that technology, inkjets with fixed, paper-wide heads. And they are *really* fast, as in 50+ pages per minute."
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93vzvj | [deleted by user] | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It was a growth of what humans had to do by hand, each level increasing the complexity slightly until we got our operating systems. The first computers could only run one program, and they were physically built using physical wires and often mechanical components. To change the program you had to rewire and rebuild the whole thing. So computer people got lazy and started putting switches you could turn on and off to change the program. Then computer people got tired of repeatedly flipping the same switches for programs they barely changed. So they punched the switches they wanted flipped onto cards, and got a machine to read the cards and flip the switches for them. Wound up having a bunch of people wanting to use the same computer, so they made people put their boxes of cards in a row, put some tape on it to tell when it should be loaded and got some guy to load the jobs by hand. Then that guy got sick of it, so they made a machine to do it for him. Then they realized, not all of the machine was being used all at once, so they figured out that they could just let multiple programs run by switching between them. Since they had something doing all that automatically, they decided to add on a way for someone to tell the machine directly what to do, so they hooked up a screen and a keyboard, called it a Terminal. Then people got board of typing and wanted something that was easier, so they invented the GUI. And that's pretty much where we're at for now."
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93xl0z | HTTPS:// vs HTTP:// | As the title. Why is HTTPS better? How is it encrypted? | Technology | explainlikeimfive | {
"a_id": [
"e3gqt0l",
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"text": [
"You want to give Bob a letter, you don't really know anything aside from his name/address. So a guy opens the door, says \"yea, I'm Bob\" and you give the letter away - That's HTTP A guy opens the door says \"yea, I'm Bob\" and you say \"prove it\", and he shows you a paper that says \"It is Bob, signed by Frank\". Now, if you know Frank's signature you give the guy the letter. If the paper says \"It is Blob, signed by Frank\" or you don't know Frank, or the signature is not the same as Frank you know, then you don't give the guy anything. - That's HTTPS There's more to it, because you exchange encryption keys with Bob for further letters once you made sure it's him. So afterwards someone can't slip in an envelope full of shit and say it's from you or from Bob. And even if someone opens letters during delivery they can't read it or change it without knowing the key. Also sometimes there are more levels of signing, so paper looks like \"It is Bob, signed by Frank. It really is Frank's signature and Frank's an honest dude, signed by Joe\" and you know Joe.",
"To secure a communication channel, you need to be secure on three levels: authenticity, confidentiality and integrity. * Authenticity is the most known part. A server has to provide a certificate which proves their identity. This uses public key cryptography. Only the server can create a valid certificate, but anyone talking to the server can verify that it is valid. This results in the green indicator in your browser. [More: wikipedia]( URL_0 ) * Confidentiality is the encryption itself. This uses regular symmetric encryption, meaning both client and server encrypt and decrypt with the same key. Of course, they have to aggree on a key without anyone intercepting this. Here they use the [Diffie-Hellman Key exchange]( URL_2 ). The [paint analogy on wikipedia]( URL_1 ) shows how both parties can aggree on a secret key without ever exposing that key itself. * Integrity is the simplest part. To ensure that nobody tampered with the messages, a checksum is added to each message. EDIT: HTTPS does all of them, HTTP does none. Leaving out one of the parts allows you to circumvent the two others, so it's an all or nothing case."
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"https://en.wikipedia.org/wiki/Public_key_certificate",
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"https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange"
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93y1hh | On the old CRT TV sets, why/how did smacking the TV fix the picture? | I remember when we were younger, anytime the TV would get a bit shaky you'd give it a good whack on the side and it would magically work. Same with other electronics like the radio. How did this actually work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Since this era's electronics was made up of discrete components, probably hand-soldered into the board, dry solder joints were more likely that for modern surface-mount, flow-soldered boards. There were also more daughter boards, cables and valves / tubes all plugged into sockets. All of these could end up making poor connections, which a good thump might jiggle and fix."
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8
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94094s | What sustains Moore's law? Why is it exponential and not linear? | Technology | explainlikeimfive | {
"a_id": [
"e3h8rhe",
"e3h93ex"
],
"text": [
"It's exponential because each new technological advance builds upon the gains of the last technological advance. What keeps it going though is probably just competition between technological powerhouse companies. The technology is going to have to jump platforms to keep going though. The integrated circuits at the current scale are providing increased capability, but at the cost of security... which is likely going to cool advancement for a while.",
"It's only being sustained because the industry sees it as a good guideline for how fast we should progress. The problem is that the Law is arguably dead, as we have reached the limit of integrated circuits. To keep the law alive we will probably need to delve into some sort of quantum computing."
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944fan | How did Game Genies work for nes/Sega Master System? | Technology | explainlikeimfive | {
"a_id": [
"e3i842p",
"e3i7n5s"
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"text": [
"Game Genie's worked a little different depending on each system because each system treated cartridges a little different. In general a Game Genie was designed to sit between the console and the cartridge and when the console asked the cartridge for data the game genie could secretly change it before passing it back to the console. So for example you have a game where you start with 3 lives. That number 3 exists somewhere in the data or code on the cartridge. Let's assume the number 3 is stored at the 5000th byte of the cartridge's data bank. On the Game Genie you'd enter a code like \"50 00 99\". This would tell the genie that every time the console tried to load the number from address 5000 to send back a value of 99 instead of what was really there. Now when a new game starts you have 99 lives because that's the number the console recieved. While that code is obvious in its meaning the genie usually used scrambled codes in a known way, so for example you might actually enter the code \"90 05 09\" and it would get unscrambled into the more meanful code. Different consoles had different ways of working. On the NES the cartridge was linked directly into the CPU bus in such a way that it could control *all* memory, not just the cartridges (this allowed NES cartridges to enhance the original hardware, not just provide game data) by routing any memory access through the cartridge pins first. This means that the cartridge could even override the data in the consoles built in ram. So Game Genie codes for the NES might do things like \"hold\" a byte. What this means is that it essentially kept a value in RAM locked - attempts to change it wouldn't work. So you have a place in ram where health was stored and when health reached 0 you are supposed to die. The game genie could just hold that value at 99 and now you are invincible.",
"In normal operation (no Game Genie) the console will ask the cartridge what the rules of the game are (how many lives you get, how high you jump, etc). The cartridge will then provide those rules and values to the console, which proceeds to create the game on your tv. What the Game Genie does is what for the console to ask for certain information, at which point it jumps in and gives the console a wrong value. The console can't tell the difference between the cartridge and the Game Genie, so it just accepts this erroneous value."
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944ksn | [deleted by user] | Technology | explainlikeimfive | {
"a_id": [
"e3i8fpg"
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"text": [
"For a good dishwasher, they do not. I saw an interview with a dishwasher designer who was visibly upset that people keep rinsing their dishes before using his machine."
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8
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94a0sb | Difference in block level and file level backups | What’s the difference between these two types of backups? And how would the restore process differ depending on which type of backups you used? Is one seen as superior to the other? And is there a third option other than these two I’m unaware of? Thanks. | Technology | explainlikeimfive | {
"a_id": [
"e3jdtd1"
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"text": [
"A block level backup doesn't have any notion of files or directories, those are just another use of the blocks on a drive. If the drive fails, you can put all the blocks back and get a drive identical to the one before the backup. File backups preserve the relationships of files and directories to the data blocks. This allows you to restore a single file without restoring everything else. It takes a much more sophisticated restore program, which essentially emulates the operating system's file manager, to extract a single file from a block level backup."
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94c38v | How do volunteer computing companies/labs use my CPU time? | I’ve ran some software which donates some CPU time that I don’t use to help with research projects that require many resources. I’m stuck with a (probably) basic question about all this. How does the process look like? What are they doing with my CPU time and how can they use it? What is my computer actually doing and sending them? | Technology | explainlikeimfive | {
"a_id": [
"e3jutr2",
"e3jw0oq"
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"text": [
"They send your computer data through whatever tunnel you setup for them. So they send data that tells your pc \"hey pc#1234 whats 1x2?\". Your cpu then calculates the answer and sends it back. Be careful doing this has this can easily open you up to malicious attacks if you authorize the wrong people to use your computer.",
"At the main node, a program is run that communicates with all the helper nodes to split the computation work. Usually the work of one node does not depend on the work of other nodes, which allow all of the nodes to work at the same time. The main node continuously collects the results computed by the helper nodes to keep track of what has been done and what still has to be done."
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94eov9 | what is the purpose of those robocalls where no one is on the other end | I get the calls that say “This is the IRS, you are going to be arrested. Please call us immediately to take care of the problem, etc.” because they are an attempt to get your financial and personal information. But what value could a call be that gets no information other than you picked up so it’s a live number? | Technology | explainlikeimfive | {
"a_id": [
"e3kj2rw",
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"text": [
"> But what value could a call be that gets no information other than you picked up so it’s a live number? That information is useful to reduce the calling list to numbers that at least work. Robo-calling outfits operate by having a call center full of workers ready to pick up and start the scam. The system automatically calls people and then if someone picks up will transfer them to a worker with an open line. But if more people pick up than expected and there is no open line available the call might not be connected to anyone and the system will just hang up.",
"It's a ploy to check if a number is working or not. If they happen to fool you with the IRS bit, then they'll scam the hell out of you for your personal data. If you don't fall for the scam, but you pick up, they know that the number is working and they can try a different tactic. Some have the option to 'remove you from their list,' but usually that's just a lie and they'll just throw you into another list to try something else. Most of the time, they have bots that run everything so that they can just scan through the numbers of an area. Scammers have even started masking their numbers to make you think it's someone from your part of the country. If you call the number back, you get the number of some random person and not the scammer. This makes it hard track them and they get the desired result."
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94g9ke | Why does proximity to my hand/body seem to focus the sound from my radio transmitter. | A transmitter like this [car transmitter ]( URL_0 ) . The music coming from it always is less fuzzy when my hand is closer or closed around it. | Technology | explainlikeimfive | {
"a_id": [
"e3ktipj"
],
"text": [
"You're acting as an antenna, the large inductance of your body gathers the radio waves and then re-radiates them. The same principle as putting rabbit ear antennas on an old broadcast tv."
],
"score": [
4
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94h6kr | How do logic gates work? | I already know their truth table etc. I'd like to know how they "physically" work, like what happens inside them. | Technology | explainlikeimfive | {
"a_id": [
"e3l0ek0",
"e3lbi8a"
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"text": [
"MOSFET Transistors have 3 Pins, the source, drain and gate. When a voltage is applied across the gate, the area between the drain and source is depleted of electrons, creating “hole” charge carriers. Basically, imagine a highway between two cities jammed with traffic. I open up an exit, some cars leave the highway. The absence of cars is known as “holes” and instead of saying cars moving forwards, we say “holes” are moving backwards. The large number of holes reduces the Drain-Source resistance to near zero and allows current to flow, so the transistor is now “ON”. By arranging transistors in different patterns, you can feed the drain current from one transistor into the gate or sources of other transistors and create complex circuits, which act like idealized logic gates.",
"We use transistors to build them. Most are made from MOSFETs and there are two kinds. N-type are off until you apply sufficient voltage to the gate, P-type are on until you apply sufficient voltage to the gate. We use a mix of n-type and P-type to build logic gates. [This is the transistor level circuit for an AND gate]( URL_0 ). You can see that if either A or B isn't true, then one of the bottom transistors will be on and pull the output low, but if both A AND B are high then both upper transistors are on and both lower ones are off so the output is high(as it should be for an AND gate)"
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94ht9j | [deleted by user] | Technology | explainlikeimfive | {
"a_id": [
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"e3l67va",
"e3l4etz",
"e3liko0"
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"text": [
"an automated system cannot solve the captcha codes and convert them to text. they usually give tasks that cannot be done by artificial intelligence to prove that you are a human.",
"Suppose I create, say, a bot that mimicks the cursor patter of humans ?",
"The I am not a robot box works by tracking how your mouse moves across the screen or how your finger moves into position on a touch screen. When tracking this movement it's looking for little shakes and movements that differentiate humans from code designed to move a cursor",
"I'm not too pleased with any of the other answers here so allow me. I'm a Developer who has not only seen RECAPTCHA do it's job very well I know how it works. RECAPTCHAs that do not require any human input do a few baseline things, such as check your IP address (a value given to you by your Internet Provider as a unique identifier to your network) to find your history across the Google Platform to find out if you've completed things such as a few Google searches here and there, created or excessively used a certain Google account. If your IP address is considered \"static\" (I can provide an explanation for this one if asked) you've already got a little something against you because the machines that host spam bots use static IP addresses. You have also seen that RECAPTCHA scans for mouse movements around the page. Due to the fact that a spam bot could simply \"click\" the box from the top of the page (I can explain this one too.) RECAPTCHAs that require Human input pose challenges that tests prove Bots can't complete such as showing you letters on a varying background because they believe that only human eyes can separate the letters from the background or the images with cars/roads/hills/store fronts. In my reading for this answer I also found that RECAPTCHA compares the user agent sent by your browser to that of your reported \"environment\", my reading also found that Google attempts to render a very small Canvas on your page (which a bot running as a script without a browser couldn't see!) TL;DR: Googles Risk Analysis team does the most and fastest unintrusive methods to ensure the end user is not a robot to protect a very large part of the internet from spam."
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94i8uu | How do hundreds of users access files on one server simultaneously without the server crashing? | For example, each school in the school district I work at has it's own server. With hundreds of teachers and students all accessing their data at the same time, how does the server keep up with this? With solid state storage it makes a little bit more sense how this is possible since SSDs are so much faster, but with mechanical drives I just can't wrap my head around it since the drives can only spin at a finite speed. | Technology | explainlikeimfive | {
"a_id": [
"e3l77n4",
"e3la90s"
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"text": [
"There’s several things at play: 1: computers are really fast these days, if used efficiently. As an end user it might often seem like things are sluggish and slow but that’s often due to inefficient apps. Server side software is often much more optimized for performance. Reading a small file to disk and sending it out over a network interface doesn’t use a lot of resources and can be done really fast. 2: SSDs and RAID. Flash storage reduces access time drastically and RAID allows you to spread load over several of them. 3: caches: after a file has been loaded once, it’s in the operating system’s file system cache in RAM which is even much faster than SSDs. The file sharing software might also have its own caching mechanism in addition to that. So if many users read the same file, especially when it doesn’t change, the physical storage drives often aren’t eve used when the file is in cache. 4. Load balancing: a file might be hosted in several places and a load balancer directs each user’s request to a different server to spread the load.",
"A file server won't really crash due to a lot of concurrent access, it'll just get slow. It may be too slow to be useful but it will still work. Besides that: * Caching. If 30 students go to the same file, it doesn't need to be read 30 times, only once. * Fast drives. 15000 RPM drives. Those are expensive and too noisy for consumer use, but that's not a problem in a datacenter. * Multiple spindles. When you have an array of a dozen drives, different files are on different physical disks, so the load gets spread between them. * Idle times. If the teacher asks everyone to go download an assignment, humans aren't robots. Some will do it a bit faster and some a bit slower, and that will spread out the load. * Tolerance for low performance: Something that might be intolerable on your home computer isn't necessarily that bad for a file server. Eg, if a file that normally would take 1/10th of a second to read takes 2, that might be seriously annoying on a home computer. On a file server which you use rarely, and so have to wait for far less often it's not that big of a deal. This of course depends on the workload."
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94ji8e | [deleted by user] | Technology | explainlikeimfive | {
"a_id": [
"e3lfhgp"
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"text": [
"No, the delays don't add up this way. If it's 3 seconds at the beginning of the interview, it's generally going to remain about 3 seconds throughout the course of the interview, unless there's some sort of latency issues in the connection. It might be easier to understand it in different terms. Imagine you drive a mile to a store to buy a gallon of milk. It takes you five minutes to drive to the store and five minutes to drive back. But you forgot to get eggs. You're not going to magically be driving ten minutes to get to the store, it's still going to be five minutes to drive that mile and five minutes back."
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94kxmu | Why does the storage capacity on hard drives keep increasing rapidly as the years go on? | Technology | explainlikeimfive | {
"a_id": [
"e3lr6o3",
"e3m5mr8"
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"text": [
"Basically a combination of technical advances and dropping prices that allowed to include more Magnet Discs in one single Drive and to dense Up the amount of Data written on each disc",
"Moore's Law was about transistor's in a circuit becoming smaller so the processor would double in speed every two years (IRL 18 months). But it has also applied to storage and RAM and whatnot. Scientists are constantly striving to miniaturize and get more efficiency. So far this has been a linear process more or less, we could always make it a bit smaller and faster. There isn't a huge incentive to jump technologies, that's why your breakthroughs don't happen more often. The company always wants a few price tiers going, so it needs to constantly replace the top tier and let the rest move down a spot. But we always knew there was a physical limit to how small a transistor can be. The solution was adding more cores. With storage we went from optical lasers like DVD from magnetic tape drives, now the big breakthrough is SSD. Each time a technology hits a limit other technologies become more viable and cost efficient."
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|
94ovzz | - why are so many Windows programs installed in "users\AppData" instead of "Program Files"? | Technology | explainlikeimfive | {
"a_id": [
"e3mnudx",
"e3monwk"
],
"text": [
"It's easier to let different users have different customizations in the program if there are individual working directories for everyone instead of just the one.",
"The program isn't installed there, it's just a folder with the same name that is used to hold your personal files for that program. If other people use your computer, their personal files are stored in their own, separate folder."
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|
94qazj | Why is every website I go to on my mobile browser desperate to get me to download their dedicated app? | Technology | explainlikeimfive | {
"a_id": [
"e3myfqr"
],
"text": [
"Also installed apps can gather more data from your phone and can also push notifications. In the end installing and never opening is still a win for them."
],
"score": [
3
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|
94qvka | During WW2 why didn't the Allies replicate the MG42 when it was superior to their variants of machine guns | Technology | explainlikeimfive | {
"a_id": [
"e3n25q6",
"e3ndnl2",
"e3ne0p2",
"e3nwski"
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"text": [
"Time, money, resource management, getting them to the front lines would be a pain. Also, it wasnt necessarily better than the American weapons used at the time. But it shot with a fast rate of fire, a large caliber, and its ability to easily swap its barrels made it more useful for the type of combat.",
"There's a lot of reasons, some which come to mind are: - Cost of research and reverse engineering - Cost of replacing all current production lines - Cost to replace all existing machine guns in the field - Time to retrain all of their troops in a new weapon platform - Sometimes a GPMG is a jack of all trades master of none, it is not necessarily superior in all regards. The British Vickers gun for instance was incredibly reliable, as in one military college put over a million rounds through one and only had to replace the barrel.",
"US infantry doctrine was that you had infantrymen with rifles who were supported by machine guns, wheras the German infantry squad was basically a machine gun that was being supplied and guarded by riflemen. It wouldn't have been enough to simply reverse engineer a German machine gun, you'd have to change your whole style of fighting to really get much of a benefit from it.",
"The mg42 on its own was a very good gun. If you wanted to put large quantities of bullets down range, then the mg42 is probably the best gun for that at the time. The problems with the mg42 are largely logistical in nature. First the things are not accurate at all. This is fine if your fighting a defensive war, but spoiler Germany tried to fight an aggressive war during even after that was no longer possible. Compare that to a British bren who could flank an enemies line and suppress the entire line until an advancing unit was basically on top of the enemy. Can't do that if you fear shooting your own men. Secondly, the MG42 was not the easiest gun to move in comparison to things used by the allies. The British bren gun was quite easy to move and could be fired from the shoulder. In comparison the MG42 pretty much had to be shot from the ground meaning the gunner had to set up a position in advanced to actually do anything. It cost maybe a minute of time, but sometimes you really don't have that time. Finally the MG42 chewed through ammo. It ate more ammo than the gunner could realistically carry, which means the riflemen in the unit also had to carry ammo. The lead to quite a lot of german riflemen not shooting their rifles. This meant that any unit with an MG42 was pretty much only the MG42 and a bunch of armed guys defending it while feeding it ammo. The MG42 was a perfect gun made for the wrong war."
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|
94veki | Why can the sound volume of commercials on internet TV be double the actual show's volume? | Technology | explainlikeimfive | {
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"The commercials are allowed to be as loud as the shows. That means if the show has a gunshot, or an explosion, or a big dramatic music swell, then the commercial is allowed to be as loud as that. Thing is, the loudest sound in the show lasts for a few seconds at most, whereas the volume in the commercial is as high as that for the whole 30 seconds.",
"They compress the sound, making everything sound as loud as the maximum volume in a clip. Usually there are dynamics in a song or any audio clip. Some parts are played lower than others. Compression makes everything equally loud, removing dynamics but increasing the overall loudness.",
"It is illegal in the USA for broadcasters, cable, and satellite providers to have louder commercials. The [CALM Act]( URL_0 ) lays out procedures which must be followed. One problem is that some programs are 30 minute infomercials while the CALM Act applies only to commercials. You should register complaints at: URL_1"
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"https://en.wikipedia.org/wiki/Commercial_Advertisement_Loudness_Mitigation_Act",
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