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k1nwed | Why does mobile data interfere with airplanes? | Technology | explainlikeimfive | {
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"It probably doesn't. But we're not 100% sure, and we don't want to have to certify every single public Aircraft to be safe against every single type of mobile phone signal, so we just blanket ban mobile phone signals on planes",
"When mobile phones were first invented their signal interfered with wires and radio communication. Since then the wires in planes are better insulated. The radios and receivers are more precise, can select a more accurate area and are better insulated. Mobile phones now use different frequencies. The reason they keep the rules are just incase there are old planes that have not been fully updated, someone is using an old phones, or a new technology is invented that they are not prepared for which could interfere."
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k1p7yd | How can VPNs say that they can reduce ping when your physical location doesn't change? | Technology | explainlikeimfive | {
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"First, let's recognize that just because they claim they can reduce ping doesn't mean they actually do. However, it's certainly technically possible for them to reduce ping. Think of the Internet like driving from place to place on regular roads. Some of those roads are high traffic while some are low. Some of those roads will take you a long way out of your way while others will be more direct. Some roads have a low speed limit while others have a high speed limit. So while you might live 50 miles away from Grandma's house, the time it takes you to drive to Grandma's house is highly dependent on which roads you choose to take. Go the sprawling backroad route through school zones and construction - it'll take you a long time. Hop on an interstate highway for most of your trip and you'll be there in a jiff. Let's say you living in New York City and want to contact a server in L.A. If you're just using your mundane Time-Warner or Comcast ISP connection, this means you're going to be fairly low priority traffic. Your communications are going to meander across the country using the network links (roads) that are cheapest for your ISP - and 'cheapest' usually translates into 'slowest'. But now you purchase Zippy Brand VPN. Instead of directly trying to connect with that server in L.A., you're connecting with a local server in NYC. That local server is connected via high speed links to another server in LA also owned by the VPN. So it's a bit like comparing the travel time between driving from NYC to LA via backroads to driving to JFK so you can fly to LAX. Sure, you'll spend a lot of time on local roads around JFK/LAX, but for most of the journey you'll be traveling a lot faster."
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k1qrmm | How is Intel still operating on a 14nm process, when AMD, TSMC, and Samsung all have 7 & 5nm processes? | Technology | explainlikeimfive | {
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"For starters, Intel's 14nm process is still pretty dense, in general Intel's process nodes are of similar geometry to the next node down of its competitors. Intel's 10nm process for instance is about the same transistor density of the 7nm processes of TSMC and Samsung. The other thing is that as you go down in lithography it gets harder to scale in clock speed. The wires get smaller and it generates more resistance at the same voltage which means you have to lower the voltage. But when you lower the voltage, the signals (in general) switch slower. Intel is putting out 5.3GHz clocks against AMD's 4.8GHz because the 14nm is letting them get that extra 500MHz, albeit taking up 100% more power for that 500MHz because Intel's on a 14nm process and AMD is on a 7nm. On a desktop platform where you have lots of power and cooling capacity available to you, this isn't as big a problem. So for the limited amount of 10nm capacity available, they're sending it to mobile first and leaving desktops with 14nm. But this isn't as huge a problem (to a point) because single threaded performance generally scales extremely well with frequency and 14nm is letting them hit excessively high frequencies.",
"First thing to clear up here is that 14nm, 10nm, 7nm, and 5nm are set process nodes on the International Technology Roadmap for Semiconductors. If you improve your 14 nm process and can only reliably get 11nm of spacing its still a \"10nm process\" because that's the next node. Because of this naming convention, most things labeled 7nm are actually a fair bit wider and vary quite significantly. It used to be described as the closest two points in a design can be but that hasn't been true for a while as we moved into the extreme UV stuff parts stopped lining up with the nanometer size they were listed as. If everything holds true as the text books say it should then 10nm should give 2x the transistor density of 14nm nodes, and 7nm gives 2x the density of 10nm nodes. Companies have reported their best case transistor density and it doesn't scale as nicely as you'd hope **14nm** (Million transistors/mm^2) TSMC - 29 Samsung - 33 Intel - 37 GF - 37 **10nm** TSMC - 52 (1.8x improvement) Samsung - 52 (1.57x improvement) Intel - 100 (2.7x improvement!) **7nm** TSMC - 97 Samsung - 95 & nbsp; So if you look at the densities it becomes clear that while Intel was late to the game on the 10nm process node, the process they ended up creating let them get densities and performance on par with the 7nm nodes that other companies would start moving to in 2018/2019. The latest Intel chips are launching on the 10nm process, but because they did push it so far it has taken them a *longggg* time to work out the kinks in their process that were hammering their yields. If you look at the availability of GPUs recently, the poor yields of the recent 7nm chips is apparent, they just cannot make them fast enough to stay anywhere close to demand.",
"I believe it’s because intel has been struggling with getting a lower lithography while keeping the same performance per core, they’ve been able to create CPUs using 10nm but the performance was underwhelming, which is why I’m assuming they keep going back to what they’ve “perfected” which is the 14nm. Correct me if I’m wrong but I believe that’s why"
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k1seup | Why do older phones move when they vibrate while newer phones don't? | Like a Nokia 3310 vs a modern samsung galaxy s10, I've observed the former move and sometimes fall off a table but the samsung phone stays at the same place | Technology | explainlikeimfive | {
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"Older phones used to have a spinning weight in one of the top corners (usually top right) to vibrate. That specific location results in the corner dragging the rest of the body in whatever direction. Newer phones have longer spring motors that pulse horizontally, which distributes the force in equal directions over a greater area of the phone’s body."
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k208s4 | What does the printer do when it goes chrrrzh-gurhh-mbeerrch-beep-boop scrchraaaa | Technology | explainlikeimfive | {
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"Warming the ink and cleaning the print nozzles so that you'll get anice clean printout. Last thing you want is old, dried ink stuck in the nozzzles from your previous print job.",
"Inkjet printers will calibrate themselves, make sure everything is aligned properly, and clean the print heads. Impact printers (think dot matrix) are noisy all the way through due to the print head striking the paper with ink. Laser printers are warming up the heater, cleaning out toner off the drum, and making sure everything is aligned. I have studied how all these printers work for IT certifications and I still find laser printers to be advanced magic. \"Yeah let's just shoot lasers at a spinny thing moving at high speeds to change the charge on it in the shape of letters and pictures and stuff and then we will stick cool plastic dust to the differently charged bits and roll em onto a paper and then melt them in place with a heater. And then put enough checking and error correction so that this can happen thousands of times in a row before you gotta replace anything.\"",
"The initial sounds might also come from self calibration and homing of all the moving parts. Basically the printer is rather dumb, it doesn't really know where each part is (like the ink carriage etc) so to start each time with a known configuration it performs routines to move the parts until it reaches hardware limits (either micro switches or optical sensors).",
"It's a lot like the buttwiggle a cat does before it pounces on something. Changes in temperature moves things around and the printer has to warm up the ink and make sure everything is lined up so it sprays the tiny droplets of ink in the same place across the nozzles or fuser.",
"What kinda printer? Laser ones adjust themselves, but those old ones you see in post offices that go eeeeerrrrrrrrhhhhhggfhhh eeeeerrggghfhrhfhfhfhfh when they print and are an ungoly mess of noise... They have tiny needles in the printer head, and both the needles and the printer head yell while they print line by line by line.",
"The moving parts are controlled by the stepper motors. Smaller versions than those used in 3d printers and cnc machines, but what makes them noisy is the drivers they use. Stepper drivers are between the source of power and the motor itself on the circuit and controls the movement. Modern stepper drivers like TMC2209 makes the motors pretty much dead silent but they cost more and has more features than needed in say, a printer. URL_0 listen here!",
"And why does it always do this at 2am?"
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k22tpl | What is proof of stake consensus, and how is it considered provably fair? | Hi guys: I'm actually a blockchain engineer but i'm struggling with explaining my business case to people on the business side. So, I want to put together a description of blockchain at a five-year-old level, because every business person i've met basically has the IQ of a 5 year old anyway. Any ideas of how to explain bitcoin/blockchain to a five year old. PS: I am actually sitting here with a 5 year old - so I can try these out in real time if they're good. < 3 | Technology | explainlikeimfive | {
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"Proof of Stake is essentially saying the people with the most interest in a given system are the ones with the most power to validate and confirm other things in that system. The idea is the people making the determination are the ones who don't want to screw it up, while also having something that couldn't possibly be majority owned by one source. In mining or Proof of Work you could get 50% of mining and create a mess, but in Proof of Stake, to get that control you'd have to own more than half of everything, which just isn't really possible. On a real ELI5 level, imagine there's a big club of Pokemon card owners, they all own a bunch of valuable cards, you come in with your cards and want them graded for quality. They people with the most skin in the game are the ones who are most incentivized to make sure your cards and by extension their own, are graded and valued fairly, and they also have the most incentive for no one to introduce fake cards or cheat on or back out of trades. No one person controls it, but collectively everyone wants to stop everyone else from cheating to preserve their own value.",
"> because every business person i've met basically has the IQ of a 5 year old anyway. Aside, but imho this is a relatively common view one type of person with experience in one field has of other people without experience in that field, but potentially a lot of other experience. Chances are you don't understand the 'business' side any better than they the technical side. If you want to communicate better, don't try to treat them as idiots, try not to be an idiot about what they do, and then communicate to them in the context that matters to them. They're likely not getting it because you are failing to show how it is relevant to them, and they're not investing the time to figure it out without first getting why they need to understand. Was a physics major who became a corporate lawyer. 'lawyers' don't get math has some truth to it, but when those issues came up, if i started explaining the math part of the problem first it wasn't going to convince them. Needed to explain the issue my proposal was going to solve, get them to agree that was the right outcome then bring in the math. Then I switched into finance, and was same thing with legal issues. Just raising the legal point was seen as being obstructionist. Had to start by pointing to problem to solve, then talking about the legal. Now I'm in a corporate doing M & A/investments. Often the bridge between tech people and business people. Same shit, I need to invest the time to understand something about the tech and something about the business area before getting buy-in. Invariably there are major business points the tech person didn't get, and likewise business people need a carrot to get over the hurdle understanding the points about the tech. TLDR: everyone is lazy and it takes effort to learn new shit. if you want them to learn, you need to accept most people are lazy/skeptical out of their frame of experience, so need to provide the incentive to learn upfront."
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k25daz | Why do you sometimes need an area code before dialing a number and why sometimes do you need a one before that? And how about when you don’t need either? | Technology | explainlikeimfive | {
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"This is a relic of the way the phone system used to work. Back when the phone network were developed the phone centrals were simple systems, first ones were staffed by humans even before machines took over. It was therefore too much to expect that every phone central would have an updated list of all the phone numbers in the world. So they would only have a short list of local numbers, maybe four or five digits long. Most calls were local anyway. When you wanted to call a different area you would dial the area code instead which would then transfer you to the phone central that were servicing this area. You could also dial regional codes or country codes which would transfer you to phone centrals that services these too. The problem with this system was that phones became far more popular then they expected and they started to run out of area codes in some regions. So they started to have multiple region codes for the same physical location to allow for more area codes. And when cell phones were introduced these got their own regional code, which were not enough so they had to use more regions for cell phones. There are a lot of differences between countries and I just used a generic example for how it would typically be in most countries."
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k28045 | Why is 5g considered harmful to use? And is it actually harmful? | Technology | explainlikeimfive | {
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"It's not harmful to use at all. It's a conspiracy made up by truly ignorant people and people with mental issues.",
"It is considered harmful by people who do not know what 5G is, or how it works. You may also find that many of these same people also believe the earth is flat, or that we never landed on the moon. There is considerable overlap on these opinions.",
"It's not harmful. This always happens with almost any new technology. Same thing was said of electricity during its introduction.",
"The only potential issue is with weather forecasting and even that is only a remote chance - URL_0",
"People also claimed at the time that 4g is harmful, and going even further back, they claimed that cellphones causes cancer and fire at gas stations. All of which has been debunked",
"It's not harmful. The people who think it is think black people are gods and all other races are aliens, the earth is flat, the moon is a hologram, reptilians control the wolrd etc etc",
"5G is not harmful, that's based on some horrendously misreadings of studies by people who see the word \"radiation\" and jump to conclusions. BUT! It operates on frequencies very near the resonant frequency of water vapor, so while it won't forcefem you or turn your brain to pudding, it will likely cause serious problems for weather forecasts in the future."
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k29ha3 | What the hell is ping in gaming? I keep looking up the definition and I still don’t get it. So what is it? | Technology | explainlikeimfive | {
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"Ping is a pretty old concept: you send a package to another computer, and wait for an answer. And then you time it, so that you know how long you have to wait for an answer. The number tells you about the network and server response times: If you press a button, and actually do something in a game, the ping time is the time you will have to wait, at least, to get a response back from the server that properly reflects what you just did. Perhaps not particular important when you play by yourself, but when you play with others, it will give you a number on if the information you see on the screen is actually accurate. How old that information is. How efficiently you can react to that information. If it's even worth the trouble to react, or if the information is already so inaccurate that a reaction is fruitless."
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k2ar2o | Why are there so many different brand names for the same model graphics card? | For example, when I search for [Radeon RX 570 on newegg]( URL_0 ), the same card appears from Gigabyte, MSI, Asus, and others. | Technology | explainlikeimfive | {
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"In short: AMD is in the business of selling processors, and let's other companies take the processors and design/sell graphics cards based around the processors."
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k2b3od | What’s exactly so important and innovative about Apple’s M1 chip? | Technology | explainlikeimfive | {
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"It’s apples first in-house designed Mac processor instead of using Intel chips (or Motorola before that). It allows Apple to better optimize the processors with its software and rest of hardware, to gain better speed, battery life, other benefits."
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k2jj6d | why do game developers seem to have issues to get characters to walk up or down stairs properly. Some games that actually try, still only get like 70% of the walking animation to match the amount of steps of a given stairs. | It often bothers me even more when they clearly tried. But you can see a character clearly floating on steps every other one in the walking animation. | Technology | explainlikeimfive | {
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"The underlying geometry of any stair is a ramp. That's a shortcut to make programing climbing stairs easier. Half the time it's just simpler to slap a skin on a ramp to make it look like stairs. Of course stairs are different enough from a ramp that you notice it, but rather than spend time programming something you'll only be doing less than 10% of the game, they'll spend the time on more important things.",
"Walking up the stairs is 1/2 the speed of walking forward irl, but it feels completely insufferable when it's in a video game. I imagine the amount of work with the payoff of making the game slightly more tedious doesn't appeal to most game studios.",
"The process of having the computer calculate where the \"steps\" are and how to orientated the feet in comparison is called \"Inverse Kinematics\" and is generally a *really* hard problem to solve. The issue isn't so much to match the animation to the steps, but to be able to do that with the infinite number of different ways a player *could* walk up some steps. They could be walking fast, slow, stopping, at an angle, head on, backwards, forwards, strafing, zig-zag, what have you. The computer has to calculate where the step is, where the player is, what limbs are at what step, how close the steps are to the limbs, how a realistic looking limb looks resting at that point while doing the rest of the animation, and all make it look smooth and clean and not just like the foot is running an entirely different animation to the rest of the character. Hand animating it is too time consuming and really only feasible if you lock the player in to a fixed \"climb up a stair\" interaction, which is a lot uglier: who really wants a five second cutscene to walk up a few steps? Generally unless your game is focused on walking up stairs you apply the IK system to your animations near stairs with a \"good enough\" approach and leave it at that. Game development is already rushed to all kingdom come, making something that your player is going to spend a few seconds at a time doing occasionally look perfect is low on the priority list."
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k2k0ri | why each game does not provide the option to download only one graphic quality, instead of having to download low, medium, high and ultra graphics? | Technology | explainlikeimfive | {
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"Apart from textures and models, different levels of \"graphic quality\" are just effects that in and of themselves do not take much space, even though they are difficult to execute. As for the models and textures, nowadays games use systems of dynamically changing the resolution of these based on distance to conserve system load. Therefore, lower than the maximum resolution models and textures are already included for this purpose, and lower graphic settings merely make the machine choose lower res. data more often. However, there are occasionally - more so in the past - \"HD\" packages that allow you to download higher resolution models and textures into the game than the original release had."
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k2km9j | what effects would occur if Google stops for a day? | Technology | explainlikeimfive | {
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"Google services? Yeesh. Probably not great for businesses. I'd just use ecosia and forget about my email for a day, personally. Maybe twitch will livestream the brief chaos as Googlehome-driven security turns off. Edit: adsense would be off too 😁",
"A single day outage of all of Google and its services would be a single day outage of a pretty big chunk of the Internet."
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k2lbim | Whats the difference from those big bulky cameras you'd see at movie sets and tv shows ,and the normal small portable cameras? | Technology | explainlikeimfive | {
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"The main reason is those cameras carry physically larger lenses and the sensor inside the camera is larger as well. These are larger both to enhance quality and to work well in low light situations, such as when actors are talking indoors. They also have a bit more electronics to send a lower quality version of the video over a radio link, across the stage to where the director typically watches on a large monitor, and technicians record this temporary version so the director can play it back as many times as they like to decide if the shot was ok. The lenses are engineering marvels themselves. They have geared focus rings so the focus is controlled by a second operator. Different focal length lenses from the same manufacturer have the focus rings in the same place so the lenses can be quickly swapped without having to realign the focus mechanism.",
"Finally, my time has come! Camera assistant on film sets here: There are a few differences between the portable cameras your family uses on vacation, and the big ones used on TV sets and movies (and differences between the TV ones and movie ones but that’s a different topic). First is the sensor: portable cameras are worried most about getting an ok image in MOST conditions. This is why some consumer cameras boast good low light, or a cool zoom lens, or how many pixels they can cram into ~3/4” of space. Movie cameras are built to be used in a set - where you have complete control over the lighting environment. Since they know exactly how much light will enter the sensor, the engineers can focus on getting the image to look as amazing as possible under those specific circumstances. Another big thing is the form factor: Your mom can use a portable camera (most of the time) by herself. These cameras are made to be easy to use, and portable (as the name implies). Movie cameras are usually operated by a team of around 3 people. They’re built for a very specific workflow that takes advantage of an operator pointing the camera (and calling the shots), a 1st Assistant Cameraman (yours truly) keeping the camera built and maintained, and a 2nd AC keeping track of all the equipment and shuttling batteries/lenses/media/etc around set. Because of this, the camera is essentially built to be modular. Here, the camera engineers can focus on just getting as amazing an image as possible, because they know that other engineers are making the glass that goes in front of the camera, others are focusing on keeping the camera powered with proprietary batteries, and still others concern themselves with getting an image to the operator/director on set - whether cabled or through a wireless tool. The people that make portable/consumer cameras have to fit as much of that into their tiny camera as possible, so less of the R & D budget gets to go to how the image actually looks in the end. TL:DR The big fancy cameras are made to do one thing very very well, while consumer cameras have to be alright at doing as many things as they can.",
"So a point and shoot is good by yesteryears standard but not terribly great at anything, then there are your amateur and pro dslr/mirrorless, they’re fantastic but need specific lenses per specific situation. In a tv/movie setting they want a camera that can do up close, long range and wide shots without the chopping of a scene and changing lenses. In come the big guns, these bad boys are great at the lot, the only downside is to get that functionality they weigh an elephant and are about that size too."
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k2m4if | Why do GPU cards need "separate" RAM? | With GPUs, they typically state RAM values as well. Why would GPUs need their own RAM when I have RAM cards installed as well? Or does the GPU really draw from the memory cards I have? | Technology | explainlikeimfive | {
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"GPUs need a lot of memory, and a lot more memory bandwidth than anything else in the system. Low end GPUs can get away with using the system RAM, but higher end GPUs will find their calculations bottlenecked because they're always waiting to get new data. The Graphics RAM holds all the textures(surface detail) for objects that its rendering, the final frame, and any intermediate frames that are rendered. Anti-Aliasing is generally a massive hit on GPU memory usage because it involves rendering the frame at 2/4/8x the resolution and then down sampling it so you get less jagged edges, but that also means you need a huge space for the frame buffer, and it'll have all this data moving in/out at least 60x per second to render each required frame. Your memory on your motherboard is meant to be universal and provide decent performance, so DDR4-4000 will give you about 32 GB/s per channel which is pretty good compared to where RAM used to be. The DDR6 on the new nVidia RTX 3080 has a much wider bus and provides 760 GB/s for the GPU to work with, and in select workloads even that might not be enough! GPUs gobble up as much memory as they can get because they are doing so many small, semi-related calculations unlike CPUs which are doing long very related calculations and can tend to store all the data they'll need for a while in their onboard cache.",
"One thing the other posters seem to have missed, is that GPUs use different / more advanced memory. & #x200B; Current system memory is DDR4, though DDR5 is said to be coming out as soon as next year. Current GPU memory is GDDR6/GDDR6x (the \"G\" is for \"Graphics\" and the 'x' version is better than the non-x version, think of it as being \"6.5\"). & #x200B; Aside from being 2 generations ahead, GDDR is specialized to work for graphics, while regular DDR isn't specialized because it needs to for for everything else in the system.",
"Graphics computations take a lot of that memory, and will therefore put a lot of traffic through the bus that allows the motherboard to interact with normal RAM. It creates a bottleneck that can/will impact performance. A common thing laptops do is to only have the graphics processor from a GPU on the motherboard - and leech off the total system RAM, this saves them space on the motherboard so they can keep the laptop slim. But this also means that you won't have great performance even if it's using a top-of-the-line graphics processor, because it's hitting a bottleneck at the RAM. If you're using a tower, though, space isn't really much of an issue as it is for laptops - and they can/will avoid bottlenecks by giving the GPU it's own memory to read/write from."
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k2mr3c | If Ray Tracing is handled by the RT cores, why does it impact performance so much even though it has dedicated (processor) cores for it? | Technology | explainlikeimfive | {
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"Scanline rendering, which is the predominant way of rendering processes every pixel in approximately the same time, so no matter how complex the surface is the amount of time spent rendering it will be predictable, and developers can thus make sure to create surfaces that are within the rendering time budget. Ray tracing on the other hand is recursive and unpredictable in nature. Depending on the surfaces in the scene, you might trace 10, or 10 000 rays per pixel. A flat smooth surface will need few rays, while shiny and/or transparent refractive surfaces may exponentially scatter rays all over the place. Now the job of the developer is harder. In some frames there may be few rays, and in other frames the whole screen could be full of shiny stuff, so how can the scene be created that never exceeds the rendering time budget?",
"Because it's just a bottleneck. If the RT cores take 16ms (60FPS) to finish it's job, and the rest can do the traditional rendering in like 1ms-15ms, then you'll always have 60FPS regardless of how good the rest of the card is, because it's waiting on the RT cores to finish."
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k2nwvg | How do MOSFETs work? | No matter how hard I try, I can't comprehend how they work. Does the voltage applied to them have to be larger than the circuit they're switching? (Aka, I'm trying to switch a circuit which takes 3.6v with a mosfet, so I can press a button and get the mosfet to allow voltage through, and have no idea how!) | Technology | explainlikeimfive | {
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"First thing first, your [MOSFET has 3 legs, a source, drain, and a gate]( URL_0 ), to turn an n-channel MOSFET on you have to get the voltage between the source and the gate above the threshold voltage, but the drain voltage can still be quite a bit higher. This lets you drive a MOSFET from a low voltage micro/power supply and control a higher voltage signal like the transformer feed in a power supply. [Here's a basic n-MOS circuit]( URL_0 ), you can see that the bottom leg of the MOSFET is tied to ground, this is the source leg of this part. This means that you just need to get the gate voltage to be a few volts above ground and the FET will turn on and let current flow from drain to source. Its important to consider how you're placing your FET when laying out your circuit. If you can get the source lead of your FET tied to ground then it becomes a lot more intuitive and you don't need a strong gate drive. If you can't, and are forced to put your FET after your power source then you would need a gate voltage *higher* than the rest of the voltage in the system, in these scenarios you'd want to use a p-MOS which is like an n-MOS but almost completely backwards in behavior"
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k2pkjz | Why do “reset” buttons on electronic devices require a needle or pin to press while on/off switches do not? | Technology | explainlikeimfive | {
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"Those reset buttons usually permanently clear some sort of stored data that you wouldn't want to be accidentally erased, so they make it hard to accidentally press the button.",
"The “reset” button usually isn’t a power reset (off then on). It usually resets the configuration of device back to factory defaults. That is not something you’d want to do accidentally so they make it so it requires a little extra work.",
"Ease of use. You turn things on and off all the time, but the times when you have to reset is pretty rare and the consequences are high. Think about your phone--if you accidentally turn it off, you just turn it back on; if you accidentally reset it, you might lose important data and it might take hours to get things set up again. Manufactures do try to help us avoid turning things off by accident too, though. The reason a lot of mobile devices have a press and hold power button is to prevent accidental powering off. It's kind of like a practical compromise between the difficulty of a reset button and the ease of use of a normal power button."
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k2xa4u | Why are computer software installs so bad at estimating time? | For example, my iPhone restore said it’d be about 8 minutes when it started. It’s been about 20 and it says that it will be about a minute more. | Technology | explainlikeimfive | {
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"Because they're just that -- estimates, and there's any number of things that can go wrong or hamstring it. Perhaps that estimate was with leaving your phone idle so it could maximize cpu and storage resources put toward completing the task. If it's restoring from an online backup, may be your 4G connection got weaker. Maybe some big files are causing slowdowns.",
"Computers stopped being easily predictable a couple decades ago. Back then, there was a single thing running on a computer, so everything was extremely predictable. If reading a block from disk took 100ms, then the next would also take 100ms, and so on. And if you had 100 blocks to transfer, that'd be 10 seconds. Easy. Today, any computer is running a whole bunch of programs, which may at any time choose to do something. The operating system may index the disk, the antivirus may scan random files, Steam might download an update on the background, and so on. Each of those will cause unpredictable slowdowns at unpredictable times. Whatever program you're running doesn't even know Steam exists, let alone that it's going to start doing stuff in the middle of its operation. Additionally, the operating system itself is trying to predit what a program will want to do and do stuff to make that faster. That means that sometimes an operation completes instantly because the OS already thought you'd want that, and sometimes it doesn't, because it didn't. All of those things mean that you can't really make an accurate progress bar anymore. You can try, but it would be a lot of work to make it accurate. Really they should just be taken as a sign that something is happening and that the update isn't stuck.",
"Installation of software is composed of many separate steps that must be completed in sequence. They are things like downloading data, reading and writing files, and processing data. The simplest method of estimating how much time a process will take is to consider how much time has passed since the task started and compare it to how far through the task it is, and from that extrapolate how much more time remains. We might be able to compile a count of the number of tasks to be performed but we would need to assume all tasks take the same amount of time which is obviously untrue. Downloading files is unlikely to take exactly as much time as decompressing them, so if those were the only two steps it wouldn't be right to say we were 50% done after we finished the downloading. But we need an accurate estimate of how far along we are to calculate a specific time of completion! Everyone's computer might be different so we can't just pre-define how long a given step takes. One person might have an old, fragmented mechanical hard drive while another person has a cutting-edge NVMe drive. Download speeds might change dramatically mid-process, CPU resources diverted to other tasks, etc. In fact with a complex install there may be no way to know how many steps there will be at all until the process is actually run! One system may need a driver or toolkit installed that another does not, the outcome of one step leading to others in unpredictable ways. Making an accurate prediction would require benchmarking the system it is to be performed on, testing and weighting the performance impact of each step in the install process, and it would still likely involve a good bit of guesswork on elements outside of your control or ability to predict. All to make a little bar and timer for a mostly tech-illiterate user who is going to obediently sit there and wait for it to finish regardless. It just isn't worth the effort to make it better."
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k2y6qq | Why are recycled paper and recycled cotton darker? | Technology | explainlikeimfive | {
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"text": [
"Recycled paper and cotton products can be bleached completely white just like their non-recycled counterparts, and sometimes they are, but it costs more to do so. It's also a marketing tactic to leave the recycled products looking like they're recycled. Many people don't want to pay a little more for a recycled product if it doesn't look like it's recycled."
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k30dai | What is happening when Microsoft Word puts the red squiggly under a correctly-spelled word and then it disappears when you click the word? | We’ve all been there: typing away confidently when suddenly the red squiggly appears under a word that you swear is correct. You question whether you are having a stroke or have suddenly awaken in an alternative hellscape where “because” is spelled “becuz.” You go to right-click to see suggested corrections and the squiggly magically disappears! What is happening here? I can’t imagine it is just some un-caught bug in the software—it’s Microsoft! | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Microsoft products are very much known to have bugs. Sometimes bugs will live for years and never be fixed. What's most likely happening is Word detected the spelling error before you finished typing the word, but didn't put the red line until after you finished. Then Word forgot to check the word again to see if it was spelt correctly. Only when you clicked on the word did Word decide to double check and which point it realized it was spelt correctly.",
"Microsoft Word scans the word you are currently typing in real time. But as you keep typing, the words you typed several seconds ago are no longer scanned for spelling errors until you stop typing and it has a chance to catch up. So let us say you type the word “becaus“. Word flags it as a mistake *before* you type the “e” to complete the word. The whole word remains tagged as a mistake as you keep on typing. But the scanning engine is no longer looking at that word so it doesn’t remove the tag, until you stop typing for a few moments so that it can take another pass at the whole document. Once you stop typing, the spell-check engine will take a look at the entire document from the beginning, and fix any incorrect tags. But if you right-click over any tagged words, it will instantly focus on it and remove the tag immediately."
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k32hyh | How can a sundial reliably work when the sun’s position in the sky changes from day to day and month to month with days getting longer/shorter, etc? | Technology | explainlikeimfive | {
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"They aren't actually accurate with clock time. They are only going to be exactly synced 4 times a year, and at the most inaccurate is going to be off by about 16 minutes. Which if you are living in times before mechanical timekeeping is generally good enough. You can add an offset based on the date though if you really need more accuracy using based on the date and a chart like this one for your location. URL_0",
"From an outside perspective, 24 hours is how long it takes for one point of the earth to spin around and directly face the sun again. From an earthling's perspective, 24 hours is how long it takes for the sun to reach the high point of its arc through the sky. This high point is called \"noon.\" It happens at essentially the same time every day, whether it's January or July. The days get longer and shorter not because the sun is moving at different speeds or getting to its high point at different times, but because the arc it carves through the sky is getting higher and lower. In winter, more of the arc is below the horizon, so the sun is up less. So the sun is still at the same *direction* every day at noon, just higher or lower in the sky, and so its shadow points the same direction at that time, just longer or shorter. So 11am and 1pm also cast the same shadow year round, as do 10am and 2pm, and so on. The only difference is the arc will be high enough where you'll get a shadow at say 6am in June, but not in December, so the extremes of the sundial can indeed be useless in winter.",
"The sun's position changes throughout the year, but that is the vertical position (altitude from the horizon). One every single day of the year at noon, the sun will be exactly dead north or south depending on where you are in the and what day it is. In summer, the sun might be dead south of you, and high in the sky. In winter however, the sun will still be dead south, but low in the sky. It is only the vertical position of the sun that changes day to day. This means that a sundial will stay accurate, but the vertical position does not matter. Sundials track the horizontal movement of the sun. The sun will cast longer and shorter shadows throughout the year, but the shadow will always be at the same horizontal angle. Now, /u/Skusci makes a good point about the Equation of Time, which does offset the times by give or take 14-16 minutes throughout the year. However, that is due to a different phenomenon than the one you seem to be addressing.",
"Sundials tell you the \"true\" time. Early clocks used complex systems to show the same time as sundials. But it was then decided it was easier to have clocks show what's called \"mean time\", where you assume every day has the same length of 24h. Sundials show you where the Earth is in its rotation about it's axis, clocks show you what the agreed on average time is, if all days were the same length. According to a sundial, the highest point the Sun makes on any given day is Noon, and is due South. According to a clock, that isn't always the case. See more at URL_0"
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k34e1s | How do people get super long exposures of the distant cosmos from their backyard, when the earth is always moving around | Technology | explainlikeimfive | {
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"text": [
"The put the camera on a moving mount that tracks the stars so that they're stationary relative to the camera.",
"There are special camera mounts capable of tracking the sky. You just need GPS coordinates. Alternatively with a wide enough angle you can post process the image digitally to track the sky."
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k35pz8 | Why are pixels made up of red, green and blue lights? Surely the green should be replaced with yellow for the primary colours to work? | Technology | explainlikeimfive | {
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"text": [
"Red, Green, and Blue *are* primary colors -- in *additive* coloring, which is the type of coloring we're talking about when we're dealing with computers and computer graphics. In additive coloring, yellow is, surprisingly enough, *not primary* -- it is made of red and green! In *subtractive* coloring, though, like painting, you'd be right; red, yellow, and blue are the primary colors. ETA: Additive coloring deals with things that emit light (like computer monitors), while subtractive coloring deals with things that *reflect* light -- ink, paint, things like that.",
"The difference is that paint is a subtracting coloring, while screens are additive. Paint works in such way that when you add a color, you are really just removing all other colors. While in screens you can only add light. Our eyes have three types of color-sensing cells, which respond to red, green, and blue. Basically, we use cymk for paint, and rgb for screens."
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k39cfo | What actually happens when you click on suspicious / bad links? (both PC & Mobile) | What series of events or what actually happens when you click on those scammy or dangerous links? How do they actually do you harm? | Technology | explainlikeimfive | {
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"Normally the initial click is not the issue (unless it wants to download and install something) You normally run the risk of being redirected to a site where further danger exists. So as an example you go to a site that spoofs(pretends to be) a legit site and tries to convince you to input personal info. Maybe they say you need to create an account before you proceed so you input an email and contact info and password then they check that email and password combo with other common sites on the off chance they can get access...(so many people use yhe same password for everything). If they can't get access they use the forgot password link and if it asks for your pets name or first car etc then they send you a reminder email to update the security for the account you created on their spoof site, they ask those questions and just like that they have your other account now. (This is only one scenario but many more exist that are way more sneaky and clever about how they trick you). If you ever suspect anything then rather google that link followed by \"scam\" or \"is it safe\" and look for published warnings. Many will show up straight away but some do slip through the net so be careful. If you have not requested anything and a link arrives for something you supposedly \"requested\" then that should ring alarm bells! I am no cyber expert and I am offering this advice based on personal experiences having helped family members who have been scammed/hacked/defrauded. Be safe all!"
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k39fql | google analytics and how does using an add-on prevent it? | Could someone ELI5 google analytics and this add-on to opt out. Why can’t I just opt out? What is this add-on actually doing? URL_0 | Technology | explainlikeimfive | {
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"Google Analytics is a free tool used by web developers to gain information about how users interact with a website. At its default, its relatively anonymous. We can learn things like the size of device you used, how long you were on a page, what pages you went to, etc. We can also learn general information like how many people were on a website at once, or in total. This information helps developers to make a website better. But it can also be used my marketers to use information about your browsing history to make their website and advertising more enticing and attractive to convince you to buy more. You can’t just “opt out” because not every website has that capability built in. But the add on essentially blocks Google Analytics from loading so it can’t track you. On one hand, you’re protecting your own browsing and privacy so that you won’t give more information than you want to. On the other hand, you make it more difficult for developers to improve a website based on general usage behaviors. In my line of work, we use Google Analytics to improve user experience. But other companies use it to try to sell you more products."
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k3bd1n | What's the difference between Microsoft, Mac and Linux Operating Systems? | Technology | explainlikeimfive | {
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"text": [
"Like WRSaunders suggested, think of them like cars. Windows would be like your bog standard family cars: anyone can use them and they are generally reliable and can run most applications and do (within reason) what ever you want. Your average consumer will have this. MacOS would be like your high-end German cars: Reliable and runs productivity applications well although more casual applications like games generally aren't supported/won't run particularly well. It comes at a premium. Linux is like your boy racer car: highly customisable and can be modified to do basically any task, even gaming if you have the right things installed. Using and setting up Linux requires a bit of knowledge so your average computer user would probably struggle to use its full potential. They are all very capable and can be used to accomplish basically the same tasks, just like all three of these cars, with varying degrees of success. It all comes down to what you want to do and what you are comfortable with."
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k3ko0r | Why can’t everything use AA batteries? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"AA batteries are quite large, which is a problem for smaller devices that don't need as much current/capacity.",
"The *number* of batteries is dictated by the voltage required by the components of the device. A single battery (no matter if it's D, C, B, A, AA, AAA, AAAA) is 1.5V (-ish, actually somewhere between 1V and 1.5V, but we'll just say 1.5V). If you need 3V (for example, if your device has even a single LED), then you need 2 batteries. No way around that. Many electrical components will require at least 3V, so realistically 2 batteries is always going to be the minimum. (Okay technically there is a way around this, with a complicated power supply, but those are very big and heavy and expensive. Edit: /u/open_door_policy corrected me in a different comment) The *size* of the batteries is dictated by how much power the device draws. While a AAAA battery and a D battery put out the same voltage (1.5V), the D battery will last quite a lot longer. Anything with movement/motors, which generates a lot of heat, or generates loud sounds (or very bright light), will draw a lot of power, and it would be silly to use AAA batteries for it. You'd have to change the batteries extremely often in that case."
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k3lgza | Why do you need a NASA computer to emulate a game system from 2001 that in terms of raw power barely outperformed a middle of the road computer from 1995? | It always puzzled me why exactly video game console emulation is so resource-intensive. Despite the systems themselves often being about as powerful as a severely outdated (at the time of the system's release) PC, their emulators always require ridiculously powerful PCs to be able to run the games at full speed and native resolution. Why exactly is it so resource-intensive? I'm not looking for an explanation along the lines of "it's resource-intensive cause it takes a lot of power to emulate the whole environment" cause it's basically like answering with "it requires a lot of power cause it requires a lot of power". I want to know *exactly* why I need a 4-core, 4.5GHz Intel i7 10th gen to be able to run a 2007 PS3 game in 720p, 13 years after its release. | Technology | explainlikeimfive | {
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"text": [
"Because you aren't running the game. You are running an operating system which is simulating a piece of hardware which is running the game. It's like... Instead of watching a movie, hiring people to reenact all the actors and crew on set creating the movie and then watching that. Which is why it's better to port a game, if possible, where you actually make whatever adjustments are needed to let it run naively in the PC.",
"It’s a bit like speaking through a translator. If you have a high-schooler that’s barely passed a couple Spanish classes, you’re likely going to have massive translation issues and it’s going to take a long time to get your message across. Now hire a professional who knows every little intricacy of both languages and you can have a near-perfect conversation quickly without pissing anyone off because they said something they shouldn’t have :) Usually with emulators, you’re dealing with two completely different hardware architectures and you can’t just run an instruction meant for Processor 1 on Processor 2. It has to be translated, and much like verbal languages, it’s usually not word for word - it has to be put in the “dialect” to be understood correctly. That takes time, and the faster the machine runs, the easier it’ll do it in real time."
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k3n3y6 | Why do the flight attendants tell us to turn on airplane mode when on an airplane? | Technology | explainlikeimfive | {
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"text": [
"RF interference from mobile devices could interfere with the airplanes electronics and navigation equipment. This is particularly critical on take off and landing. Modern airplanes are pretty well shielded to avoid this problem, but the FAA doesn't like to take any chances. With older aircraft stray radio signals could cause malfunctions. The other reason is FCC regulations. As you cruise in the air your phone will try to connect to every cell tower along the way and this multiplied by every airplane in the sky can cause cellular traffic jams as it were, loading cell towers with useless traffic",
"There is, its to avoid potential interference. While the radio frequencies used by airplanes and cell phones are different, there is no certification to ensure they don't interfere. As such, the airlines request that phones (or any device that can transmit) be shut off so that there is no potential for interference (even if its not possible). Phones aren't certified largely because the requirements by aeronautical agencies would require every model of phone to be certified which would cost manufacturers way more money than they wish to spend."
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k3nod6 | Why can’t companies like Apple (AppleSilicon) or other ARM chip making companies just make really big chips that would outperform anything and everything we currently have? Disregarding battery life and heat issues, what about a laptop that is only one mega chip that takes up all the inside? | Technology | explainlikeimfive | {
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"One thing I would point out is chip yield. The larger and more complex a chip is, they higher the likely failure rate during manufacturing and the lower the yield. I.e. a CPU today might have a 70% yield. This means that 30% of the chips you make aren't usable. The larger and more complex you make a chip, the lower the yield.",
"People wouldn't buy it. The average consumer wouldn't need that much power and the price of manufacturing such a chip would skyrocket.",
"You can only fit so many transistors on a die of any specific size. The larger you make the die, the lower the yield will be on silicon wafers. Have you ever seen those silicon wafer discs? [pic]( URL_0 ) The larger the die the fewer you get per disc, and the more expensive it is. Also, the larger the die the more chance of flaws. For every disc made sometimes portions of it are flawed.",
"One aspect is modularity. A single CPU that only functions as a CPU can be paired with multiple and various periphery chips to build out a system for specific purposes. Case in point, a laptop doesn't need 8 SATA connections, so there is no reason to have periphery chips on the motherboard to support that. They can just incorporate the needed amount. If all that was on the motherboard was in the CPU instead, you wouldn't have that modularity and there would be those unused resources being powered.",
"People haven't covered yet the other side of why you can't just have one laptop-filling chip (besides die yield itself). Chips require support hardware. For example on a motherboard around the CPU slot you'll see all sorts of capacitors and chokes and what have you, because part of a motherboard's job is to provide the power chips need -- and that includes the right voltage, and very stable. Plus, modularity. In theory sure you could bake the CPU, GPU, RAM, Storage, all that into some ultra-hyper megachip (we already do that to an extent sometimes, it's called System On a Chip, shortened to SoC). But what if you wanted to add RAM or switch to a bigger hard drive because they're inadequate? You either have to buy a whole new humongous chip or a whole new laptop. But even then it wouldn't fill the entire laptop, because it still would need support hardware and connectors, and because a Chip with all that stuff wouldn't need to *be* that big. In fact, if you research CPUs alone across different generations, even for having more and more stuff packed in them and being immensely more powerful than say 20 years ago, they're getting *smaller,* and as counterintuitive as it may seem that shrinking actually *aids* in becoming more efficient and more powerful."
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k3nuik | Why is it so difficult to achieve 4k resolution at stable or locked 60fps in gaming? | Technology | explainlikeimfive | {
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"It takes ~~twice~~ 4 times the processing power compared to 1080p 60fps. So unless your computer is ~~twice~~ 4 times as good as one that can render at 1080p 60fps, it will be more difficult.",
"Graphics programmer here. In all the games I've shipped, we provide a quality slider so that players who want 60fps gaming can achieve 60fps gaming. Oddly, the kind of people who are fiercest in their dedication to 60fps, are reluctant to turn the quality settings down below max. I don't understand why this is, and I don't know how to help these people."
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k3owqc | How do race car contests broadcasters keep up with all the changing positions of cars in real time? | I was just watching a short Grand Prix clip and I find it laughable a person could possibly be making all the switches by hand. Is there some sort of software-hardware link with the cars and the track that technologically tracks which cars are in which position and how does that work? Like the race track isn’t a straight line or anything so it’s hard to imagine how it works. | Technology | explainlikeimfive | {
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"There are roughly 20 places on any Formula 1 track where there are sensors embedded in the track. Thats enough to automatically update the positioning, and also the time intervals, every 5 seconds or so. The cars also have GPS on board, but as far as I can tell, that is only used for the moving-dots-on-the-circuit-infographic. While the sensor data is used for official rules purposes (mosty for the Virtual Safety Car, but also sometimes for things like determining the positioning after a red flag), it appears that GPS is not precise enough for that, and therefore relegated to the infographic thing."
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k3pq5d | What physically happens in a hard drive when data is stored? | Technology | explainlikeimfive | {
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"If you put a powerful magnet next to many kinds of metals, that metal becomes a magnet itself. The hard drive puts a tiny part of the disk next to a tiny magnet, to make that tiny part a magnet. It then reads and see what parts are magnets."
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k3rhym | How do obviously fake accounts get verified? | Technology | explainlikeimfive | {
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"> I’ve seen accounts such as “Jesus Christ” be verified on YouTube. How is that possible? It’s just hilarious to look at comments and see a verification badge next to the most ridiculous names. Maybe there is a misunderstanding here as to what the Verified-status means. It's not a form of personal identification. > When you see a verification checkmark next to a YouTube channel's name, it means that the channel belongs to an established creator or is the official channel of a brand, business, or organization.",
"Why not? \"Verified\" just mean that the account is not stolen, and that the account's owner has left contact informations. Youtube can contact them if they want. That's it really. They don't check if you REALLY are the person, they don't care if you us a celebrity's name, as long as said celebrity doesn't care either."
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k3rtc9 | What is the difference between 4k, UHD, and QHD when talking about monitor resolutions? | Technology | explainlikeimfive | {
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"4K indicates its 4000 pixels but really means 3840x2160 pixels UHD and QHD are just marketing speak for different resolutions UHD is ultra HD which is the marketing term for 4K QHD is the marketing term for Quad HD, which refers to 2560x1440 being 4 times the resolution then 1280x720 in pixel count. you have High Definition : 720p Full High Definition : 1080p Quad High Definition : 1440p Ultra High Definition : 2160p 8K Ultra high definition : 4320p the P means progressive scan, meaning it goes line by line, sometimes you will see a i instead of the p next to the resolution, it means Interlaced, it means that when creating the image, it does every other line, so image quality is a bit reduced but for storage and transmission you basically save half the bandwidth. So many HDTV transmissions at first were I instead of P at first."
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k3wyvo | What is UX vs. UI? Also what is Dark UX Design? Is it related to Dark Mode on a website? | Technology | explainlikeimfive | {
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"User Interface vs. User Experience. Good UI: everything is clean looking and easy to navigate on the audio settings screen... Bad UX: ...because it is just one button that increases volume by 1% every time you press it until you have the volume you want.",
"Dark UX is design that is meant to trick the user into doing something they don't want to do. An example is an advertisement with a fake close button, to trick the user into clicking on the ad when they were trying to close the ad. [Here's an article with more examples.]( URL_0 )",
"User experience (UX) and user interface (UI) are two fairly similar realms oftentimes. The terms are sometimes used interchangeably or incorrectly, so you have to parse out what people really mean. UI design revolves are the physical layout. The buttons, the assets, the graphic design. The visual elements and the actual interface itself and its key components. UX is about the user's experience as a whole with the product. They consider every possible interaction a user might have associated with the product. A large part of that is how fusterated a website might make them, which explains the overlap with UI. However, it also encompasses concerns such as: how are users discovering the product? How many pages are they navigating through to find the most common information they need one the website? How does the user feel in this process? What else could make the user happier? At the most basic level, UI is the indivual pieces and parts that serve UX's goals of creating a good user experience with the product.",
"UI is User Interface, the thing a human must interact with to use a tool, webpage, device, whatever. On a website it's things like the layout of the webpage, the use of buttons and checkboxes, popouts and overlays, and so on. UX is User Experience, or what happens when you use something and how you feel about it. When everything works smoothly and quickly, that's good UX. Bad UX is things like always having to close a pointless pop-up before you can get to the website, not knowing about complicated password requirements except when it tells you there's an error, or having to sign up before you know if it's worth it. Dark UX is the stuff that's designed to subtly manipulate you into making a particular choice that is not in your best interests. For example, when you go to the checkout on Amazon and it asks you what kind of shipping you want, it's always an expensive option that's the default selection, or starting a free trial of Prime. Everyone's going to change it to free delivery but it's a subtle nudge that over time, or if you're in a hurry, may get you to pick the option that earns them more money."
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k3zws6 | How do you program a chess algorithm "less good" | So I was wondering how you could program a machine to play chess like a 16-year old or even worse etc. | Technology | explainlikeimfive | {
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"Chess programs work by figuring out all possible moves several turns ahead, giving a score to each possible outcome, and then choosing the move that gives the most optimal one. One way to make the program easier to beat is to simply decrease the number of turns it \"thinks ahead\". Other ways are to simplify its scoring function, or add random element.",
"When a chess algorithm is 'thinking', it's playing out a bunch of hypothetical series of moves, and after it's done those moves it rates how good the resulting position is. The pieces remaining on the board are worth some points, pawns close to promoting are worth some points, having the king in check is worth points. Each chess engine has its own way of allocating points but they're all generally similar. The engine always does this points-rating at full power, i.e. doing its best, no matter what difficulty you've set. So after it's run through a bunch of potential moves, it'll have a list of all of them and their point values. The values might go +11, +8, +6, +6, +3, 0, 0, 0, -1, -2, -4, -12. (The searches are thorough, so it will consider some terrible boneheaded moves at this stage, like that -12.) One of the ways the difficulty can affect things is you can tell it to do a \"3-ply\" search or a \"5-ply search\", and it will play each hypothetical series that many moves ahead. The ply setting doesn't make a massive difference for most people, although if you turn it way down (3 or 4 moves) then it starts failing to see traps, or it might not see the outcome of a forced series of exchanges that's obvious-ish to people. Once the valued list is done, it has to select a move from the list, and this is where the difficulty comes in. If you have the engine on max difficulty, then it will just select its best move (the +11, in this case) every single time. On second-highest difficulty, it might do something like \"70% of the time, play the best move; 30% of the time, play the second-best\". If you turn it down to patzer difficulty, the table could be like \"play the absolute worst move 5% of the time, the second-worst move 10% of the time...\" and so on."
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k41ten | When a video or audio track is "remastered" what have they actually done to it, and is it better in any way than the original? | . | Technology | explainlikeimfive | {
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"The “master” copy of a track will be pretty much exactly as it came from the recording booth/room. Obviously there’ll be some effects and equalisation etc applied at time of recording, but it can be considered to be fairly “raw”. This master is then edited for release on whatever medium - frequency levels adjusted, new effects applied, maybe some segments get chopped out or moved elsewhere etc, until either the artist is happy with the final result, or they reach the limit of their time and money (producers and engineers don’t come cheap!) and have to release the track. Over the years, the artist may wish they’d done something different. Or maybe it was just mixed together poorly (a good example is the “loudness wars” where records were mixed extremely loud to the point where quality suffered). If the master recording is still available, then it can be re-mastered and re-engineered to sound better, or closer to the original vision. My favourite example is Rush’s album “Vapor Trails”. It fell victim to the aforementioned loudness wars on the original release and sounded pretty poor. A few years later they remastered it, and dropped the volume - preserving audio quality.",
"They redid the editing process in an attempt to improve it. If it's actually better is subjective, but usually they wouldn't remaster if they thought the original was perfect. As an example in music remastering usually means adjusting the volume of the individual tracks (instruments, singers, synthesizers) in way they harmonize, or emphasize something.",
"It's all in what you call \"the original\". If by that you mean studio master recordings or camera film, then remastering isn't to improve that. However, nobody gets to see that sort of thing. If you're talking about a DVD disc or online stream, the quality of the original material was destroyed to make the content fit within the limited bandwidth available. When it's remastered for a BluRay or 4K stream, it's really just a matter of compressing it less so that it's less damaged. So, a new \"remastered\" Bluray\" is likely much, much better than the \"original DVD\". Others have said great things about audio remastering into newer formulations as CD was also lower fidelity than analog recordings.",
"The process of making a record had a few stages. First you record all the tracks. Like vocals, guitar, drums etc Then you mix those all together at the right levels and apply effects. This is called mixdown. The last stage is mastering. Each format the song will be played in has slightly different requirements for level and so each version gets slight tweaks. For example the version on Spotify will be slightly different from the version on the radio and also from the version on a CD. But these changes are subtle. Usually only some equalisation ( which means adjust things like highs and lows) and some audio compression which is adjusting the difference between the loudest and softest sounds intl the record."
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k44ugj | Who actually launches the rocket, mission control or the astronauts aboard the rocket? | Technology | explainlikeimfive | {
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"Depends on the rocket, but most modern rockets launch themselves. By that I mean the start up and ignition sequence is automated and controlled by computers on the rocket. Ground Control monitors *a ton* of incoming data, and if everything is functioning properly, they'll allow the rocket to begin it's sequence, usually a couple minutes prior to it actually lifting off. Astronauts are mostly along for the ride these days. They can assume manual control once in space, but aren't doing much besides holding on in the first 15 minutes of launch.",
"In most cases, it's either the rocket itself or a computer in mission control. There's a control computer that's doing all the sequencing of major actions and checks. The astronauts and mission control have lots of ways of \\*stopping\\* the launch (as does the control computer itself), and there will be a few key decision points where the astronauts or mission control have to provide an affimative \"go\", but the actual launch (like, release the claps and fly) is sequenced by computers that will execute unless told not to.",
"Mission control turns the rocket on, and can turn it off at any time. The rocket's on-board computer controls things as the launch happens. The astronauts can also turn it off, and have some control, but are mostly along for the ride as long as things are \"nominal\".",
"Technically a computer handles the final few seconds and the thousands of small tasks to actually launch the rocket. However mission control will enable the launch computer, and if they don’t think things are favourable they will also disable it so the rocket does not launch. The astronauts (if there are any!) are mostly passengers at the launch stage, they don’t really do anything apart from confirm they’re sitting comfortably."
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k4715x | How do games that are in development for several years catch up to the latest graphic technologies? | For example, a game studio has started developing a game in 2015, now we are close to 2021. In those ~6 years, there can be many improvements to the software used or libraries. Examples like DirectX, HDR, Anti Aliasing options DLSS... If a part was written or rendered in 2015, are they refactoring the parts again before release to match the newest trends? | Technology | explainlikeimfive | {
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"There is continuous improvement, but it's not like these other games releasing in 2021 popped out of the ether, fully formed. Very rarely does a game have a cycle less than 2 years, often more, and in many cases the games will be built on legacy bases anyway. I'm not sure if it's still the case, but until at least quite recently Call of Duty still had some of its Quake II code in there somewhere. So the idea of the start and end of game's development cycle is a bit of an outdated idea. You also have some engines which are developed independently of games - third party ones like Unreal are the obvious examples, but also many studios will have an internal engine that gets used across games, and a such represents iterative improvements over the years. There will come a point when they have to lock down which version they're working with but that point isn't going to be 6 years before the game is released.",
"Firstly, not all of development is actual coding. \"Development\" can include project planning, game design, story boarding, prototyping, asset creation, and more. Secondly, including new graphics technologies isn't always a drastic move. The art assets are usually created in high detail, and downscaled for adequate performance on each platform. Enabling HDR and anti-aliasing only impact the renderer; that's one of the more complicated components of the game, but still only a fraction of the development effort. Most games will abstract away the rendering to the game engine, which is either developed by a different team or licensed from a third party. So those new technologies barely impact development of the core game. Regarding DLSS as far as I know the actual work happens in the GPU, there's no code change required besides adding the option to enable it. The devs do need to submit their game to Nvidia to train the upscaling AI but that would be done on the tail end of development or with individual assets/textures as they're completed. DirectX is probably the most significant change you could make to a game mid-development, but a) DirectX doesn't update all that often, b) most/all of the changes will be in the game engine, and c) DirectX by and large is backwards compatible, if you built your game on DX11 and want to support DX12, there's really only one or two additional rendering features the engine needs to add support for, if there happen to be any improvements in existing features they will be a bonus for little to no effort. As CyclopsRock said, you can iteratively update your libraries, engines and other components during development, but at some point towards the end of the cycle the versions will be locked in. Also, these new technologies don't just pop up overnight by surprise, Nvidia or AMD aren't going to announce new technologies without at least a handful of supported games to showcase it and drive sales, otherwise it's a pretty useless feature. Graphics companies are working with developers to get these new features in the game, months or even years before they're released.",
"Depends on the situation. Final Fantasy 15 was originally meant to release much earlier for the PS3, under the name Final Fantasy versus 13. But the console's hardware limitations meant the developers faced technical difficulties until the PS4 launched and they decided to restructure the project and upgrade some technical parts. Then there are games which were also delayed and launched in a more or less obsolete state, with Duke Nukem Forever probably being one of the most prominent examples as it disappointed not only graphically but also in terms of level design and game mechanics, thanks to its 14 years of development. Another category are games like Dark Souls 2 which was later upgraded to DX11 graphics and bundled with the DLCs to the Scholar of the First Sin Edition."
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k488po | How do websites know I am signed in without changing the URL in any way. | How does a website know whether or not I am signed in or out to a specific website, even though the URL stays the same whether or not I am signed in? Also, depending on whether or not I was signed in last session, it knows to sign me in again if I go to the same URL. How do these things work? | Technology | explainlikeimfive | {
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"Probably a cookie. Cookies are like a notepad, on your computer, where a website is allowed to make some notes for next time you visit. If you tell a site to log you in automatically and set the language to Portuguese, that information is stored in a cookie. The site can read that as soon you arrive, get your credentials from your browser's password manager, and have everything set up the way you like it the instant the first page loads. You can dig into your browser settings and look at the cookies that websites have written about you, but it's not super informative. I'm not sure if cookies are allowed to be plain text, but all of mine seem to be a string of hex."
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k4b3w2 | why does it seem like the unsubscribe button for emails does nothing? | Okay my question has been answered thank you! Edit: how do I turn off notifications for a post on mobile? | Technology | explainlikeimfive | {
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"One sneaky thing legit companies are doing all the time now is making the \"unsubscribe\" button unsubscribe you to those specific types of emails. Oh, you don't want to subscribe to our daily deals? That's ok, we'll still send you the weekly deals and the special deals. Some sites have like 10 different lists that you have to unsub from individually",
"It often doesn't. In fact for spam, clicking that just tells them your email is real and they can sell it to more spammers.",
"It depends on if the email you tried to unsubscribe from is a legitimate marketing list, or spam. If it's a legitimate marketing list from a reputable company, the chances are pretty high that the unsubscribe link will work, but if it's spam, it'll either do nothing, or encourage more spam. Legitimate unsubscribe links can often take days to propagate, though, so maybe mark the message as spam too.",
"This is not a certified way but try using an European VPN. Companies breaching GDPR get quite huge fines, so it is the case in general that in Europe that like actually works. Or, even better, just mark the emails as spam so that your spam filter learns to block them.",
"It's like the \"close door\" button on the elevator - just there to make you feel like you're doing something.",
"Ex contact centre employee here who's worked with email campaigns. People tend to see emails from a company as coming from one place, but in reality companies have multiple departments and campaigns, many of which will be outsourced. All of these will be using different systems. You might unsubscribe from a particular email from one part of the company, but that doesn't exclude you from others. We worked around this stating in the email exactly what they were unsubscribing from. You could in theory align those different departments to all unsubscribe, but it's work. I suspect this is why some state that it takes a few days. The other factor is how easy it is to misconfigure these things. The system admin isn't likely to know until someone decides to complain."
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k4gb7x | What is this ‘protein folding’ problem Deepmind has solved and how did it do it? | Technology | explainlikeimfive | {
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"Protein folding is predicting a three dimensional shape of a protein based on the amino acid sequence. This is critical to understanding medicine and making new medicine. Deep mind uses a powerful mathematical model or artificial intelligence to predict this with 70% accuracy. That’s a big accomplishment, but there is a long way to go. How does it work? Basically the computer is shown all the known sequences and resulting shapes. It then learns from this and can use what it learned to predict the shape new sequences will take. The key word in artificial intelligence is artificial. The computer is not thinking, it is just solving a big math equation, optimizing the input numbers with the output numbers. The scale of these math equations is mind boggling, yet fir many years we have thrown bigger computers at the problem and made little progress. That is why this is big news. It’s a major milestone in progress. The limitation of this system is that if training data contains only half of all possibilities, the machine cannot predict the other half, which is literally unknown to the machine. One key aspect that makes artificial intelligence smart is incorporating expert human knowledge by designing the math equations it solves to represent that knowledge. Again, it is still limited to what the experts know. That remaining 30% represents largely in part what we still don’t know.",
"You can think of any protein as a big KNEX toy. To make a protein, we have to connect pieces together and make long chains. We have a lot of pieces but only 20 different types of KNEX pieces. Depending on which order we connect the pieces to each other, it will give us a different shape. If I give you the order of pieces you need to put together, can you figure out the shape you will get? Deepmind learns the most likely solutions by remembering patterns in previous solutions. Patterns become probability. Deepmind is making a lot of probability based educated guesses that it learned from actual data and solutions that people have found for other proteins.",
"Proteins are long complex balls of amino acids. But each protein has a particular way it likes to get tangled (because that’s a low energy state scientifically). Predicting the exact way an amino acid will tangle is very hard, because you have thousands of atoms (Possibly more) interacting, bouncing around, and being hard to predict due to number of interactions going on. But the shape it tangles into is critical. If you find one that tangles into the exact right shape, it can be used as a medicine. For example, if you can find one that will tangle onto a HIV virus, and you’ve found a treatment for AIDS."
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k4ig8y | Why do printers need coloured ink if you're printing/copying in black & white? | Hi Printer! I'd like to copy this black and white document please Sorry you're out of Magenta Thats OK I only want black and white No. You're out of Magenta Why is it like this? | Technology | explainlikeimfive | {
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"Some printers use coloured ink to help with black and white printing too, like with getting the different shades of grey just right.",
"> Hello, I like money! - Mr. Krabs The printers can be made to work perfectly with just the black cartridge for B & W but that would mean one less overpriced cartridge bought right now. Also color printers like to use the color ink for the microprint pattern that they put on each page with date and serial number a la KGB registered typewriters, so there's that too.",
"Well listen timmy, printers only have a few colours of ink which they mix to make all the other colours. Even if you want to print something with a blue colour, the printer might still need to use some yellow to get the right colour. Speaking of yellow: Some (if not all) printers print tiny yellow dots on the paper no matter what you print. This is so police and other law enforcement can see what kind of printer made the copy. URL_0"
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k4izsc | When the old Dial-up goes “bee-boo bee-boo kshhhh...” and so on when dialing, what’s it doing? | Such a weird but familiar sound. Always wanted to know what it was doing. | Technology | explainlikeimfive | {
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"text": [
"I always loved this image that graphically represents the tones and their meanings of a modem dialing out. URL_0",
"That sound is/was part of the \"handshake\" where your modem was negotiating a connection with the remote modem. Those sounds included some diagnostic sounds for those who knew what to listen for, and were left audible until connected so you could hear things like a busy signal, human voice, or other error messages meant for people",
"Modems are analog. You're hearing them literally shout instructions at eachother over the phone line.",
"It's a modem *handshake*. It's, simplified, how the modems agree on how fast they can communicate. Somewhat more complicated, it's how the modems agree on which one is the fastest communication standard they both know how to use (this is how an older modem can still communicate with a newer modem) and a simple test of the phone line, so that they both agree that it's actually possible to communicate with that standard on the phone line."
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k4jvtv | why are the quality of voice/videocalls so low, when we can stream 1080p++ movies on demand? | Is there real reason why calls are so low in quality (relative to the hardware's maximum capability), or am i just using sh*t platforms? (I've tried using google duo, google meet, zoom, line,whatsapp etc and their quality doesnt differ much) . Additional question : is there a platform that focus on super high quality calls? | Technology | explainlikeimfive | {
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"Your movies are streamed trough protocols built upon transmitting high def video, and if you force high quality, your.movie will stop and buffer until enough data is downloaded to continue. A video/voice call uses a very different protocol, built so that communication happens in real time. On top of that, your same call service has to work for those poor kids in rural africa, to make an extreme example, so it uses adaptive audio and video quality for that purpose.",
"In addition to what others have said - there's basically two parts to transmitting audio/video: encoding/compressing the raw image stream into a size small enough to transfer, and decoding/decompressing it at the other end. In movies, half that work is already done for you - they can take their time selecting an encoding algorithm that uses the most complex maths in order to get the best possible result. It doesn't really matter how long encoding takes, as they only have to do it once (sure, there are more complex scenarios, but keeping it simple for now.) And because you can buffer the stream in advance, they only need to be able to decode at a speed just ahead of the download. Realtime streams have to encode the data really fast, transmit it really fast, and decode it really fast. That involves discarding as much detail as you can get away with.",
"Movies are a one way transmission. Zoom calls are two way, but with multiple connections. 30 people all with their video on is a lot to download plus audio. Audio is the biggest data user, as well, since its not like people are sending you 4k video. So constant upload and download. Some internet have shitty upload speeds. Then it comes to priority. Then mic quality. Etc.",
"Two main reasons: 1) Voice calls rely not just on your download speed, but your upload speed, which is usually slower with most internet providers. When you're streaming a movie from Netflix, you're streaming from their servers, which they've made sure have good upload speeds. 2) With streaming movies, you can buffer the film, which basically means that you can download a few minutes ahead of what you're watching. That way, if there's a dip in your internet speed, you won't notice it, since you can watch the buffered part until more can be downloaded. With a voice call, you can't do that, since you need to hear the person right away. This means that any lag in your internet will be immediately noticeable.",
"Movies don't have to be real-time. When you watch a movie the software is downloading chunks from way ahead of where you are. When you seek it just gets a short piece and while you're watching that it gets bigger chunks. With real time conversations not only does data from the future not exist, but you have to download it really fast and show it with almost no delay. Even live video platforms like Twitch are struggling with low latency, most streams still have a couple of minutes delay."
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k4lbsi | Why loading bars tend to "jump" to a certain % and then stay there for a prolonged period of time? Why wouldn't it move steadily from 0 to 100%? | Technology | explainlikeimfive | {
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"Because the loading bar's progress is determined by how many of the required tasks have been done, and some of those tasks take longer than others. For example, if the software has 100 tasks to do, then 1 task = 1% of the loading bar. But if 20 of those tasks take a couple milliseconds to do, then the bar will jump to 20% quickly. But if the 21st task is computationally difficult, it will stay there until the task it done and the computer can move onto the 22nd task.",
"Because loading bars are bullshit. Let's imagine a loading bar for making cookies. Your steps will look like... 1. Preheat Oven 2. Cream together butter and sugar 3. Add an egg. 4. Add an egg. 5. Add flour and baking powder. 6. Add chocolate chips 7. Spoon onto baking sheets. 8. Bake for 10 minutes. What do you do with your progress bar? Does preheating the oven count as 12% done? What about adding each egg one at a time? Most of the time is spend waiting for the oven to preheat, but we don't know exactly how long that will take so we can't really estimate it compared to the 10 minute baking time. Similar things happen on software. For instance, if you have a task that is download a file, decompress it, and then do something with it, we don't know the ratio of download speed versus processor speed to say how long the download will take relative to the decompress, so we can't really size them nicely to one another. It is possible to say that certain tasks are worth less of an update on a progress bar, making it look smoother to fill, but even then that's just guess work."
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k4mg6v | How does light traveling through fiber optic cables know where to go? | I know that fiber optic cables can be used to transmit data (packets). How do these packets arrive at the correct destination? I think they get routed by routers, and if that's the case, how do routers distinguish between light (packets) meant for one device from some meant for another? Thank you! Edit: Thank you for all of the responses! Within just 40 minutes or so, I had my question and more answered in detail. Have a good day! | Technology | explainlikeimfive | {
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"It doesn't really have a choice, that's why fibers are used. They either use reflection from the edge of the fiber or variable index of refraction to bend the light back into the middle of the fiber. As a result, the light has to follow whatever shape the fiber is put into. Light goes in one end and comes out the other. When the light gets to a router, the router decodes it back into bits and looks at the bits in the header to make its routing decisions, generating new light on the output fibers."
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k4ntxd | what is ray tracing? | Technology | explainlikeimfive | {
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"On any scene all you need for that scene to be rendered is the correct color information for each pixel. Ray tracing attempts to determine that color by firing rays into a scene for each pixel, finding the material that it hits, and tracing bounces from that surface backwards towards light sources that might affect the color of that material. If the ray hits a light it's going to be brighter, if the ray doesn't hit a light, it could be in shadow. Because surfaces in the real world aren't typically perfect mirrors, they usually diffuse light to some extent. Ray tracing engines will typically send out additional rays to compensate for this diffuse light. These rays will hit a surface and bounce different directions with different probabilities to simulate the surface. This is why ray tracing with insufficient samples per pixel looks noisy and speckled, the color information has insufficient data from the bounces and it's wrong compared to what it would be in the real world. When you take more samples, the colors get closer to their correct value and the noise starts to settle down."
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k4ojf9 | How adblock detector work? | Some websites can detect that you are using an adblock, and refuse to give you content. How are the websites able to detect that you are using adblocker? Can they actually check what you installed on your browser, or is there another way? | Technology | explainlikeimfive | {
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"At worst, they could detect the extensions on the browser but that is a security issue with the browser and normally gets fixed. Chrome had this issue before but it's not common and is not something to be concerned with. So no, they won't be able to see your extensions nor could they detect anything on your computer. All they know is the browser and the user agent (a string that identifies the browser and version) which can be used to control the page layout and functionality. Not all browsers behave the same... this is why many developers hate Internet Explorer. Typically, how they detect ad blockers is they check if elements on their website are not loaded or visible. There are numerous ways to do this. Ad blockers are also updating they way they work so this is a cat and mouse game. For example, let's say I have a site with ads: - Many cheaper ad blockers work by blocking scripts that have some banned words in their name. Something like `load-ads.js`. The ad blocker would prevent that script from loading as it has the banned word `ads` in it. - Some sites also just try to make a request to their ads provider when you visit their site. If this request is blocked, then there is an ad blocker. - Others will use a more complex but more reliable way which is to measure the ad container. This is the element that holds the ad on the website. So let's say my ad is given a space of 200px X 200px. The ad blocker would remove the ad so the element's size would be smaller than the above dimensions. This is an efficient way to detect if ads are blocked but requires a bit more work on the development team. I hope this explains it enough for you. This is my first time responding in ELI5. I have been a web developer for over 20 years and I have experienced all 3 of these methods in my career."
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k4oub9 | Why does a cracked TV screen show a whole bunch of colors while a cracked phone screen does not? | Technology | explainlikeimfive | {
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"My phone screens have done that when they break. There are two layers though, a layer of just glass and a layer of actual screen underneath, or digitizer or something. If you only break the top glass it just looks like a crack, but if you break the underneath, it gets all colorful. I imagine it’s the touch screen aspect that is the difference."
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k4sxn2 | What do network engineers do to get servers back online when servers for games/services go down? | Technology | explainlikeimfive | {
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"That's a bit like asking \"What does the mechanic need to do when the car stops moving?\" ;) That entirely depends on the problem the caused the car to stop in the first place. Does it have an empty fuel tank? Did it get into a collision? Is a part of the motor broken? Is the road full of cattle?",
"I'm a software engineer, so I can explain to you how my company deals with servers going down, but every company is different. We use Amazon Web Services (AWS) as our server hosting service, and all of our services are containerized using a service called Docker. Think a self contained service running independently on your computer - we have a few of these running on each server. So when our service goes down it could be a few problems: 1) AWS went down - we can't really do anything about this except wait for AWS to come back up 2) One of our Docker containers went down - we have our docker containers set up so if they go down they automatically come back up, so again we kinda just wait a few minutes and it should come back up 3) If it doesn't come back up after 5 minutes we go into each server and check the docker containers to see if they're still up & #x200B; We do extensive testing on all of our releases so we know that our services shouldn't go down for a random reason, but if they do we have logs from each docker container and we can check to see where the issue came from. That's pretty much it to be honest.",
"Most of the time: turn it off and on again. This is the magic of getting things working again. If you ask how to restart a not working machine: there are admin interfaces to restart the servers even when they are down. Most servers are virtual machines today."
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k4u8un | How do gear changes in bikes work? | Lately i've been trying on some mountain bike routines and i love it, but i don't quite get the reason why we need to always be doing changes in gears whem in uphill and downhill. My bike has two changes (I guess for the front and back wheels). | Technology | explainlikeimfive | {
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"The gears (specifically the *ratios*) are all about achieving a mechanical advantage. The \"ideal\" way to ride a bike is to always pedal at approximately the same number of strokes per minute (say ... 120). On smooth, flat ground (eg a road), in \"top gear\" you may be pedaling 120x/minute, but the *gear ratio* of 2.5:1 makes the wheels turn 300x/minute. If your wheels are 6' in circumference, you're moving 300x6' or 1800' per minute, or about 20mph. When you're riding *uphill*, you want to be able to keep your same *pace* - but since you're doing far more *work* raising your body+bicyle up the grade, you use a different *gear ratio* to keep your feet moving at a comfortable rate, but make the gears work for you in moving you *slower*, but with *less effort per pedal*. So maybe you've switched into another \"gear\" with a ratio of 1:2 - for every 120 pedals you make per minute (the same *pace*), your wheels are only turning 60 times. With the same 6' circumference wheels, you're now going 60*6' or 360' per minute, or about 3mph. With modern bicycles, you may have 21, 24, 27, or even more, possible gear ratios to choose from. And those ratios are achieved by combining the front gears (where you're actually pedaling) with the rear set (on your rear (or \"drive\") wheel). You're not shifting gears on the \"front and back wheels\" - only where your pedals hit bottom support of the frame, and your rear wheel. They're there so you can make the ride comfortable and consistent, regardless of how steep (or flat) the route may be. Your owner's manual should provide you with a full breakdown of all the gear ratios provided on your bike."
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k4wsx2 | How does a device or a program choose a "random" number | Technology | explainlikeimfive | {
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"They take a starting value, called a *seed*, and put it through a mathematical formula of some kind. If the seed is kinda-sorta random (like, \"the CPU's current temperature in degrees multiplied by the milliseconds place of the current time\"), then the result of the formula will be \"pseudo random\". Pseudo random numbers are \"random enough\" for almost all common uses.",
"It's never a random number from a computer. It's a calculation taken from data gathered somewhere. It could be the seconds × minutes ÷ hours, or these days they can even do some weird arithmetic based on fan speed, cpu temp, clock speed etc. Back in the 90's when I was in school doing computing, the teacher got us to boot up 3 acorn archimedes computers, open the basic console and ask for a random number, they all showed the same number."
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k4yi1b | How can someone tell if an item from 2,000 years ago is authentic? For example a Chinese bowl, can’t someone just make another with an accuracy of 99%? | Technology | explainlikeimfive | {
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"Really good forgeries are hard to detect. However, if somebody is paying millions for something, they want to know the history of it, where it was found, etc. So now you need to not only fake the item, but fake the entire backstory as well. Also if you do an exact copy, it's not going to be that valuable. People want things that are 1 of a kind. If there are 100 identical bowls, they aren't going to be that valuable, so no point forging a 101st. So then you need to make something unique. And that gets tricky, because you need to know the style of the time exactly correctly. So if you go for lower cost forgeries, in the $1000s of dollars, now you are limited to how much effort you can put into your forgery and still make a profit. So your forgery won't be as good, but the person buying won't know as much, so you can probably get away with it. That said, forgeries quite often do end up in museums and art collections."
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k51ouu | why does it seem to help your connection when you unplug your router or modem and plug it back in? | Technology | explainlikeimfive | {
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"It forces the modem/router to renegotiate the connection, so you get a fresh setup that often works better than the one which you had before. It can also, as others say, be because the router itself has been on too long and is clunking a bit.",
"Software is normally very complex, bloated and rushed into production with numerous bugs. When something has been operating for a while, it’s common for the software to encounter one of these bugs and get into a “wedge state” where something critical (like DNS) fails or the errant section of code goes in a loop and burns CPU cycles, affecting performance for the rest of the box. The possibilities are endless. Rebooting the box reloads the software and clears the hardware memory and it’s likely to take a while before some other problem occurs and destroys performance again, forcing another reboot. I work in IT and some of our boxes need to be loaded on a regular basis in order to try and prevent performance issues. We’re constantly upgrading software to eliminate one set of bugs, only to learn a year later that we’ve introduced another set of bugs. Embedded software sucks mostly...",
"Think of it as flushing the queue, like how the lines are much shorter when a theme park opens than they are midday. Routers are exactly what they say in the name: things that route. You have on external connection to the outside world, and lots of internal connections in your home. Over the course of they day, due to software bugs either in the router or even other devices on your network, these queues can get longer and longer. It's as if there's annoying teenagers who are trying to spend the night in bathroom stalls at the park, so they can still be first in line in the morning. Over time, there's more and more lines getting blocked by these kids. Eventually, the park might call security to do a full search and kick them all out. This is akin to restarting your router (that's a stretch of an analogy lol). Generally you shouldn't need to do this with your router though, unless it's pretty bad. If it's happening a lot, consider a new router, haha. Modems are pretty different pieces of tech. They're only tangentially related to Routers, and that analogy really doesn't explain why you might need to restart them at all. Another poster mentioned that restarting them allows them to reestablish connections, which is essentially true. Your modem is usually supplied by your ISP, and is often junk. Your ISP is also junk themselves (pay very close attention to the fact that I didn't qualify that with \"often\": that was on purpose). If something gets messed up somehow in the connection, instead of paying any attention and restarting the connection itself, it often needs to be done by toggling the hardware off and on. Sometimes you even have to call the ISP and have them toggle some crap off and on outside of your home! It's ridiculous."
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k52gu5 | How do radio telescopes, like the Arecibo Observatory, work? | How do they work?! I understand telescopes like the Hubble, but not these. It looks to me like they’re made of concrete as well.. I don’t get it. | Technology | explainlikeimfive | {
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"text": [
"Radio telescopes, as their name implies, detect radio waves rather than visible light. A regular radio telescope, like Jodrell Bank, has a steerable parabolic antenna--a parabola focuses the incoming radio waves at a particular location, where you put the receiving equipment. Arecibo wasn't steerable, so it was a spherical reflector that would concentrate the incoming signal at a point depending on where it was coming from, and they would move the receiving apparatus (the bit that's currently collapsed) to the right point to pick up what they were looking for. This isn't as efficient as a parabolic reflector, but Arecibo was so big it compensated for that."
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k52q2i | How are LED lights capable of being brighter than traditional incandescent bulbs but still use a fraction of the energy? | Technology | explainlikeimfive | {
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"text": [
"Efficiency. Have you ever touched an LED bulb? The really bright ones may be noticeably warm, but usually that's it. Now go touch an incandescent bulb (actually, no, do not ever do that). So much energy is wasted in producing heat instead of light. This is why LEDs are much more efficient. As for why incandescent bulbs produce heat, they're essentially burning the filament (the little coil of metal inside) and gas inside. LEDs work instead by \"transforming\" energy in the form of electricity into light.",
"They just use different processes. Incandescent bulbs work by heating up a wire to a very high temperature where it starts to glow and let off light. This is incredibly inefficient since a lot of this energy goes into heat rather than light, which is fine if the heat doesn't escape but its hard to insulate well. LEDs use a trick that directly converts electricity to light, skipping the heat step.",
"Incandescent bulbs work by heating up a tiny piece of metal so hot it glows. Most of the energy is wasted coming out of the bulb as heat rather than light. LEDs produce more light and less heat, because they're using a different physics process, that doesn't rely on making something very hot."
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k58k6b | Why do you need prescription lenses for VR? If you wear glasses but can see anything close to you clearly, would you still need them? | Technology | explainlikeimfive | {
"a_id": [
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"The VR headsets does have lenses in them making the screen look like it is much further away then it actually is. Howver if you have a perscription then these lenses will overcorrect for you. You therefore have to wear glasses in order to get the focus point back to where it should be.",
"Interesting observation: I’m very nearsighted, and wear contacts. With my contacts in, I also need reading glasses to focus on anything closer than about 3 feet. But not in VR. With my son’s Oculus on (and wearing contacts), I can bring objects right up to my eyes and still see them in perfect focus.",
"VR headsets have lenses that make the screen appear to be about 2m away despite being a few cm away. As far as your eyes are concerned the screen is 2m away and if you need glasses for that distance in real life you'll need them in vr. There are also prescription lenses that you can buy to replace the ones in the headset to account for your eyes being less than perfect."
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k5cjhc | After downloading updates in phones and computers, why do we need to restart them for the changes to take effect? | Technology | explainlikeimfive | {
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"text": [
"Some things only happen during startup. To make it be different (that is, use the update), you have to go through the startup process again."
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k5eag5 | Why are video games and DVDs region-locked? I get changing things that better appeal to different countries, but why region lock them? | Technology | explainlikeimfive | {
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"text": [
"DVDs are priced to be profitable. This is a different number for everywhere DVDs are sold. So if I, a young and enterprising grifter, decided to buy thousands of DVDs where they are cheaper and having them sent over to me where I can sell them for cheaper than the price everyone else can offer, I'll make a killing. The companies that produce the movies, and in turn produce the DVDs, don't want people like me (the hypothetical scalper) to cut in on their profits. They are region locked so that I can't do this. If I may quote a line from a really terrible Tom Cruise movie: what is the answer to 99 out of 100 questions? MONEY.",
"That allows you to sell them at different prices in different regions: You would sell a *lot* fewer DVDs in India if you sold them at the same price you sell them in the US. So, if you region lock them, you can sell them in India without worrying about them getting reimported to the US and sold for a cheaper price."
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k5eaqr | What technical limitations caused the '2.5D era' of video games instead of directly moving from 2D to 3D? | Here Im mostly asking about PC games, as the full 3d era in console gaming was pretty much started with the PS1 launch (December 1994) and the N64 launch (September 1996). Case in point is two of my favourite games, Star Wars Dark Forces (February 1995), and Dark Forces 2 (October 1997), pretty much the same formula, but totally different technical capabilities. Dark Forces was solidly lumped in with the Doom era of games, being 2.5D. Basically the environment was 3D, enemies were rendered by a 2d billboard sprite, and for Dooms case, all levels were essentially on a 2D grid, with the appearance of raised ceilings and uneven floors essentially kludged into the engine. Dark Forces slightly expanded on this by somehow adding in the ability to have multiple levels (is it only 2 different vertical levels or more?) and the ability to pan looking up and down ([although this again seems to have been a hotfix to an inherent issue in raycasting engines]( URL_0 )). So then a little under 3 years later Dark Forces 2 is released by the same publisher, you can do pretty much everything you can in a normal game engine, look in any direction, completely 3d environments, and the graphics still look passable even now. I get that there are some technical hurdles to cover between 2D games and full 3D, particularly without a graphics card (first hitting the market in 1999) to reduce the performance issues with rendering only what is in view (occlusion I think?). What I dont get is how the technical issues were solved so quickly between 1995 and 1997, and in particular why the 2d grid necessity went away so quickly. | Technology | explainlikeimfive | {
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"Well, what it mainly comes down to is that PCs of the time didn't have dedicated 3D hardware the way they do now, or the way that the 1994 Playstation did--it wasn't until the release of the 3Dfx Voodoo 3D card in 1996 that this capability really started to become mainstream in gaming PCs. So, any 3D in a game had to be rendered entirely using the machine's CPU, and ray casting engines like the ones used in Doom were simply a far more efficient way of rendering 3D, albeit they took some shortcuts in order to do that. I actually remember playing through the whole of the original Tomb Raider (1996) on the PC in software rendering only, and the huge difference it made once I got a 3D card and ran it via that instead.",
"Doing true 3D polygons requires a lot of floating point operations (the PS1 did use intermediate integer shortcuts on top of dedicated floating point hardware which is why PS1 games have that distinctive warped perspective and shimmering) but in 1995 the target for PC games was still the 486. The fact that the makers of Dark Forces demanded a whole 8MB of RAM when there were still many people with only 4MB drew some interesting complaints at the time. Unfortunately the big performance difference between the existing base of 486 users and the new Pentium adopters was the processor's floating point performance. That's why Quake (1996) required a 75Mhz Pentium and even on a 100Mhz 486 would run at about 10fps (I know because I only had the 486 at home so it was easy to compare just how big a difference the Pentium's floating point unit made). So the two advances that allowed for 3D games where processors with strong floating point performance (Pentiums) and dedicated accelerators cards that could do many floating point operations in parallel (even better than a Pentium). By comparison 2.5D games required no floating point operations and could use small integer based lookup tables. 2.5D games are based on a very simple ray casting. For each vertical line on the screen the game projects a ray along the 2D overhead grid until it hits a wall. It then takes the distance to the wall to determine which scale lookup table to use and draws an appropriate vertical strip of pixels taken from that walls texture, which unlike 3D texturing aren't from arbitrary points but rather a simple vertical line using that lookup table to know when the duplicate (stretch) or omit pixels to draw it at the correct scale.",
"Most of the answers so far are talking about the lack of 3D rendering hardware at the time as the cause. This actually wasn't the issue at the time. The issue wasn't how quickly to render the polygons; the issue was how do you determine which polygons you need to render. And that is not a graphics card issue; that is a CPU issue. In all games that have a moving viewpoint, from way back in Battlezone all the way to today's best looking games, the computer needs to rapidly filter out what it can ignore and not even send to the video card. Carmack and iD made the breakthrough of using Binary Space Partitions to \\*instantly\\* know the exact list of walls they had to consider rendering based on where the camera was located. [Ars Technica has a great article going in depth on it, probably at a higher-than-ELI5 level...]( URL_0 ) **At an ELI5 level, what is Binary Space Partitioning in a 2.5D game?** Simply, the level is looked at from the top, so processed on the basis of the \"floors\" of the model. The computer splits the the floors into triangles on the basis of what walls can be seen when the camera is on the triangle. Depending on how varied that list can be, the triangle can be cut into further smaller triangles, so the list is as close to totally accurate as possible. (Imagine one giant rectangular room with 10 hallways coming off of it. Depending on which hallway you are looking down, the walls will be vastly different. So the giant room gets cut into many many triangles rather than just 2). This processing takes a very very long time, and is saved with the level. It is not done on the player's computers. Additionally, the use of triangles mean the game never needs to calculate \"which triangle am I on?\", because when the triangles are built, they also save what triangle is on the other side of each edge. So when you move from one triangle to the next, the game already knows \"crossing edge B of Triangle 12 moves you to Triangle 16\". **Oh yeah, and additional ELI5: What does Binary Space Partitioning mean?** Complex word and complex science, but actually very easy conceptually: * Binary: Means two options, \"on or off\", or \"yes or no\". * Space: On the map/level * Partitioning: dividing So, Binary Space Partitioning means \"dividing up your level so you know if you are in front of or behind each wall\"",
"When the first \"3D\" engines were created, there were no 3d acceleration. So doing actual 3d were not possible. With the ID Tech 1 engine, they basically made a 2D engine but flipped the textures for the walls to make it look 3D. There are a bunch of videos that explains how it works and why it was revolutionary. It is thoroughly fascinating. What I loved was the 2D background with 3D characters on top kind of games that worked around the early limitations in processing power. Games like [Final Fantasy VII]( URL_0 ) and [Silver]( URL_1 ). Silver can be bought on GOG and has aged very well in my opinion."
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k5ecp6 | Can someone explain what is compressed memory, cache memory and committed memory in RAM? | Technology | explainlikeimfive | {
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"Compressed memory is how much memory have been compressed in order to save space. Memory compression is a way that use up processor power to increase the memory capacity of the computer and might also increase memory speed. Cache memory is memory which is used to store data that is actually stored on the hard drive so that your applications are able to retrieve them faster. It is much faster to get data from memory then from the hard drive so files that is often used will have a copy of it in memory, whenever the computer needs more memory for applications it will kick out parts of this cache. Committed memory is how much memory the operating system have promised to give applications. This number is usually not very useful as applications are often very greedy and will ask for way more memory then they actually use. However this is fine because the operating system will not actually use any memory unless it is actually used by the application. The operating system have a lot more information about what memory is actually in use, what parts of the disk is in most use, etc. and is therefore able to make much more informed decisions about the memory then any single application.",
"Committed memory is earmarked for an application, by the OS. Cached memory is typically a 'copy' of a file in memory, for quicker retrieval. These are discarded as RAM becomes full. Compressed memory is not unlike a zipped file. It's memory contents that have been compressed to free up RAM. Keep in mind memory and RAM aren't exactly the same thing. Memory is virtual, RAM is physical. Memory includes RAM but memory can also be extended to swap files (on a drive) as RAM becomes full. Drive are comparatively slow. So you use RAM as cache if it's unneeded to speed up file access. You start discarding the cache when applications require more memory. You compress RAM to avoid also using swap space as memory."
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k5hl5i | Why do mobile apps have almost daily updates, what's being changed so often? | The title says it, I am technologically challenged. | Technology | explainlikeimfive | {
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"On mobile devices, usually every app you have is managed by the same update system. This means that product improvements and bug fixes will trigger an update on the system, as will any changes in the development chain. So if you have 30 apps installed, chances are, at least one of them is going to be involved in some update every day or two. Additionally, dev teams tend to work on agile sprint-based release cycles, which result in more incremental updates instead of scheduled monthly roll-ups. The app update process is designed to support this. And beyond those two things, apps that have had recent updates show up higher in the App Store search results.",
"In just about every app, the code is complicated enough that there are lots and lots of bugs to fix. Many of them are small or rare enough that most people probably don't notice; they might just make the app a little slower than ideal, or only occur under very specific conditions. They're still worth fixing. Also, many larger apps will add capabilities for possible upcoming features, or design changes—even small ones—and then enable them selectively for some users to see people react to them. Running this kind of experiment still needs you to update as many users as possible so you have a large pool to test on.",
"They don't. Most mobile apps have an update every two weeks to two months. But you usually have a lot of apps on your phone, so there is at least one app that needs updating every day. You don't necessarily notice this on PCs, since you use websites more often than apps (and most updates are barely noticable to the average user) and thoze apps you do use don't always ask you for updates unlike the Play store."
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k5p10i | How do phones join other carrier networks for emergency calls? | Carriers generally don't allow a phone to connect to their cellular network unless the device is using their SIM. Given that in most countries, cellular providers are required to allow any device to connect for the purpose of making a call to an emergency number, how does this work on a technical level?What prevents a device staying connected to that network after the call is completed - or just connecting and not making an emergency call afterall? | Technology | explainlikeimfive | {
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"Carriers don't prevent the phone from connecting unless it has their SIM, they just don't tell the phone it can get service from them. At the technical level the phone can talk to the tower just fine, but the tower tells the phone \"I won't serve you because I don't know you\" so your phone can't make calls or get data. BUT...there's a carve out for emergency services. If you try to dial an emergency call, the tower's going to see \"oh, you want emergency service, that I can do\" and connect your call. But it'll only do that for the emergency number, nothing else.",
"Saw it somewhere that in the US, even the phones themselves can connect to 911 services without the SIM card. It is under some law specifying life-saving rights or something. Edit: The Wireless Communications and Public Safety Act of 1999required that all working cellular phones (“working” as in it is able to power on, dial, and make a call) are able to call 911, whether or not the phone has service."
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k5p7ds | why did fast charging take so long to appear in devices and how does it work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The problem is USB standards. USB specifies a minimum current rating and a maximum voltage which limits the normal amount of power sent across it. It was never really intended for charging, but the convenience of being able to charge from any USB port, and also use the port for communication to computers for transferring files basically kept this as the defacto standard charging connector. Fast charging works by bumping up the maximum voltage allowing more power to be sent across the same gauge cable. The problem is that doing this with a device not equipped to handle it will fry the device so there needs to be some communication beforehand to make sure that the device on the other side can handle it. Where it gets messy is that for quite a long time phone manufacturers didn't want to wait to collaborate on a common standard for this communication implementing proprietary protocols that would only work with a matched charger from the same manufacturer, meaning that you couldn't just buy a third party charger and expect it to work with different phones. The current state where fast charging is is because USB C development presented an opportunity to build a common fast charging standard for anything that used a USB C connector, dumping all the previous competing standards at the same time as dumping the physical connector."
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k5pfbh | Why do newer touch screens seem harder to smudge than older? Is this a thing? | Got a new phone a couple of weeks ago. Using it hardly left any fingerprint marks right after I got. It seems easier and easier to smudge over time. Is this a thing or is it just my imagination? If it is, why does it happen and can I do something to "restore" it? | Technology | explainlikeimfive | {
"a_id": [
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"No this is really a thing. It's called an oleophobic coating (meaning it repels oils like skin oils). Improves slidiness of fingers, and keeps oil from sticking. It's usually a fluropolymer (think teflon). Unfortunately this is a thing that is done to the screen during manufacture. It should last around 2 years but will eventually wear off depending on how often or little you use your phone. There are some spray coatings that will do the same thing but won't last as long. A few weeks seems really short though. Some cleaners can damage the coating, high percentage isopropyl is one of them. For restoration option A is to just get a screen protector with a similar coating. It's just a peel and stick film. The other option is of course to replace the screen, but I'd just go with the film."
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k5um4j | Why is the colour green assosciated with CGI? Almost 99% CGI uses green colour for putting effects. Why is it so? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It is used in a specific special effect called chromakeying which helps seperating foreground objects from the background by using a specific background color. This allows them to replace the background with different images and even compose different foreground elements together in the same scene. A limitation of this effect is that the color chosen for the background must not appear much in the foreground objects. So shades of yellow and red is rarely used because foreground objects are most often humans as it would conflict with the color of the skin. It used to be that the background was blue as this was very easy to filter on using simple electronics. However a lot of foreground objects tend to be blue so green is now the prefered color in most cases. You do still see blue background being used a lot when the foreground does contain green."
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k5uu7f | Why are governments not able to permanently bring down piratebay? | Technology | explainlikeimfive | {
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"The beauty (or evil, depending on how you view it) of Pirate Bay is that its first and foremost not a company or person, so there isn’t exactly a legal entity or person the government can go after to stop them once and for all (e.g. like how the Chinese government can just block google outright). Then comes the concept of a website - they are essentially just “doors” for a treasure trove of data and information that can be quickly recreated even if taken down. And because Pirate Bay isn’t a single company or person, the treasure trove of data has been replicated by multiple hobbyists and sits in servers all over the world - so they can easily be brought back up even if one website is brought down (i.e. one door is closed, another can be easily opened)",
"Piratebay gives access to its database freely, so anyone can either access it or clone it. This is why there are thousands of 'proxybay's, which all provide *mostly* the same service. I'm not up to date with its situation right now, but I believe that *THE* pirate bay is situated on a boat in international waters, so its untouchable as of this point, it just has minimal service capacity.",
"pirate bay operates somewhat like an old-school telephone directory, it hosts the information to tell you computer where to go to find the pieces of the file you are after. just because you burn the phone book doesn't mean the phones stop working or that someone else doesn't also have the list of locations.",
"A website is just a bunch of files sitting on a server. A website address(URL) is a way to get the IP address to the server. So while governments can seize website addressees and servers to shut down a website (after a lot of bureaucratic procedures), they can't \"seize\" the files because they can be copied and distributed as long as you have access to the files. So at some stage the original creators of The Pirate Bay shared all the files for the website in order to make the site impossible to shut down. This is why there are multiple mirrors for the site up on the internet. One gets taken down another two spring up."
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k5vg2i | Why is dedicated graphics memory better than system shared memory? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Let's say you're the CPU, and I'm a program (let's be honest, game). I ask you to tell me where this guys, and that guy, and those items, how they're moving, what they're doing... All of that stuff are things that you have to calculate based on previous states, and new input. Now, I ask you to also draw all of that, keeping in mind that there's light there, there and there, and what can the player see then? As you can imagine, that's a lot to keep track of. And you're ok at everything, since you are a generalist, but drawing still takes a lot of time for an ok result. So instead, you get a new guy on board. His job is to draw the stuff I ask you to draw. He's good at it, he's been trained to do so, and he's fast. So you'll get better pictures faster.",
"Good question and I would also like to know. I do know that the graphics card memory is often considerably faster than the system memory, which is important for graphics performance. But then, why not just install faster system's memory and share that? Hopefully someone more knowledgeable can shed a light on that.",
"The amount of data you can transfer from the memory per unit of time is limited. So if you add dedicated graphics memory of the same type the GPU and CPU can now each transfer the same amount of data to and from memory as needed to share in the past. So the amount of data per unit of time is doubled Graphics memory is today not of the same types a the CPU use. They transmit a lot more data per second to the GPU but the latency is a lot longer. Latency is the time from when you ask for the data until you receive it. So a CPU has a memory that quickly returns data but the data then arrive slower. For a CPU getting data quickly, it more relevant the amount per unit of time. A GPU need lot of data per unit of time but a delay when you start to get it is not relevant. You can compare it to a motorcycle courier vs a truck in a city. The motorcycle courier will deliver a small amount of stuff faster but a truck will deliver more but take longer to get there. So what you use depend on the situation a CPU would like the motorcycle courier but the GPU the truck"
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k5yhhr | What causes somebody to require an inversion to the Y/X axis when playing a videogame? | Technology | explainlikeimfive | {
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"X axis inversion is pretty uncommon, but Y axis inversion comes from planes When working with a mouse, generally pushing the mouse up causes the cursor to go up and pulling back on the mouse causes the cursor to move down. But if you're playing a flight sim with a joystick then pulling back on the stick makes the nose go up and pushing forward makes the nose go down, the exact opposite of traditional mouse controls. The invert Y axis option is there so you can use the controller or mouse how you please. Maybe you're really experienced with using the controller in FPS games so you use the standard up is up layout, or maybe you mastered joysticks long ago in flight sims so you use inverted controls when using a controller, or maybe you want inverted on your joystick but sometimes play with a mouse that you need normal. Having the option there is nice for people who may have different backgrounds and experiences",
"I invert the Y axis only, because I grew up playing games with an inverted Y axis, many of which couldn't be changed. A lot of older games did this, especially when flight simulators were more popular. For a flight game, it makes perfect sense, because you push forward on an aircraft's controls to go down, and pull back to go up. But even a lot of big first person shooters like *Goldeneye* used it, so it became ingrained into muscle memory long, long ago.",
"Conkers Bad Furday: Live and Reloaded. But honestly think of it like it’s a stick in the back of your characters head, push the stick down guy looks up and vice versa."
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k5zm7k | How can the Task Manager in Windows or Force Quit in macOS close frozen, suspended, unresponding programs instantly. What do they do different than clicking the X button in the corner? | Technology | explainlikeimfive | {
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"They forcibly stop allocating system resources to the program, instead of politely asking the program to relinquish those resources once it’s finished. It’s the difference between asking a drunk patron to leave the bar vs grabbing him by the collar and tossing him out the door.",
"The difference is that clicking the X makes the program close itself down. But if the program isn't responding in the first place. Clicking X won't do anything. The force quit is the operating system. That will simply put delete the memory that holds the program.",
"There are actually a number of kill signals that the operating system uses that range from politely asking to shut down to simply killing it no matter what trouble that is going to cause. Now hitting the X, send a polite signal to shut down and usually the programmer can set for himself how to react to that signal, meaning the program can delay the shutdown and instead do something else before shutting down. So for example often enough instead of shutting down the program you're greeted with a dialogue asking whether you're sure about that or whether you want to save stuff or whatnot. That's meant to give the program a chance to wrap up what it's doing so that no important stuff gets lost or whatnot. Open connections get closed, parameters get saved, tmp data gets deleted and whatnot. So when a program freezes it can also ignore that signal because \"it has better things to do\", now if you disagree with that assumption you can send a more forceful signal in terms of what the operating system has to offer that simply ends the task altogether without a chance to wrap things up.",
"The Task Manager in Windows (or Finder in macOS) communicate with programs by sending them *signals*. When a program receives a signal, it briefly pauses (gets *interrupted*) to respond to the signal. There are a couple common signals an OS might send to a program: * **SIGTERM**. (Terminate signal). This signal is a request for the program to exit gracefully. For example, the program could save its data to a file before exiting. It is functionally similar to a user issuing a File > Exit or Quit command. Note: since SIGTERM is only a request, a program could ignore this signal and continue processing. An unresponsive program will not be able to handle the signal, and therefore may fail to exit. * **SIGKILL**. (Kill signal). This signal is sent to forcefully terminate a program. Unlike SIGTERM, SIGKILL is not a request and cannot be ignored by the program. SIGKILL always terminates a program unless there's an operating system kernel bug or an extremely anomalous condition. So if we take macOS's Finder as an example, selecting Quit from the dock menu will cause a SIGTERM to be sent to the application's main process, while selecting Force Quit sends a SIGKILL instead."
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k60w9j | Why do phone chargers eventually end up having to be bent in all directions in order to work? | ELI5 Why do I have to keep replacing my charger every 4 - 6 months because of this? 👆 | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"When the cords get bent and twisted all up they eventually breakdown inside. The electrical stuff inside becomes disconnected so you need to bend them to \"reconnect\" them. If you were to take care of the cord then they'd last a lot longer. I've been using some of the same charging cords for years now.",
"If you're changing the cord every 6 months you're most likely the problem. You also most likely have an iPhone. Buy Anker and they'll last alot longer.",
"I always had this problem with micro USB. My issue arose from the shitty little clips that are supposed to hold it in. They would eventually give up on life, and the cord would need to be leveraged at an angle in order to make it charge. That issue entirely disappeared with USB-C."
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k62kkv | is what's the difference between windows 32bits and 64bits | Technology | explainlikeimfive | {
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"32 and 64 bits refers to the processor's internals and your operating system (and preferably programs) should match it. You can't install 64 bit stuff on a PC with a 32 bit processor. You *can* do the reverse but you'll experience some drawbacks. > Will that affect the performance of the computer ? Extremely, on the OS level. The most visible thing is that a 32bit system cannot use more than 4GB RAM (because that's how high you can go before you run out of addresses that fit into... 32 bits). A 64 bit system can use any amount of RAM you can physically cram in it (for the foreseeable future).",
"Well 32 bit means 2³² possible addresses which are approximately 4 billion bytes or 4GB (giga=billion). So if you have more than 4GB of RAM and actually want to use it you need more addresses. Now 64bits have 2⁶⁴ which sounds like double the amount but is actually a lot bigger: 32 bit = 4,000,000,000 64 bit = 64,000,000,000,000,000,000 Also 32bit software can run on 64 bit systems (just using the last 32 bit ignoring the first), but the reverse doesn't work. So 32 bit is usually for older systems and 64 bits is the new standard."
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k645cl | How are developers able to decrease the file size of video games for lower powered consoles, i.e. the Nintendo Switch? | For example, Doom Eternal for the PC is 57 GB, but only 18GB on the Nintendo Switch. What do the developers do to massively lower the file size and get it to fit on the Switch? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Smaller textures. The Switch seems to have 4GB of memory total, without dedicated VRAM. The computer I'm typing this on has 64GB RAM and 8GB dedicated VRAM. There's no point shipping huge textures if you can't make an use of them anyway.",
"Former game developer here, The biggest part of any game are the assets. The code itself is usually pretty small. Models and especially their textures are just gigantic in size. So when you go to a smaller platform, you're going to drop the poly count and the texture resolution to balance acceptable presentation with acceptable performance."
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k69xp3 | How can huge buildings (hotels, skyscrapers, etc.) have WiFi throughout them but a moderate sized house has trouble with the WiFi signal reaching the other side? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"They have many access points, mounted systematically to provide good coverage, wired to a high speed connection in a comms room in the basement. Homeowners aren't willing to cut into walls to run wires to put their access points in the best places.",
"I'm pretty sure those buildings have expensive set-ups with multiple routers and extenders and they probably pay for a higher network-bandwidth than the average home.",
"Large commercial buildings don't use just a single cheap home wireless router to distribute their signal. Instead they use commercial grade routers and repeaters to extend the network as needed, with professionals determining placement to prevent dead spots instead of tucking it behind the home AV equipment."
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k6abvi | ; When your GPS says that you're in the middle of the ocean, and you're absolutely not, what is actually happening here? | Technology | explainlikeimfive | {
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"text": [
"GPS from satellites takes some time to get all the data it needs from the satellite feed to start calculating your location. It is absolutely NOT instant. When it shows you in the middle of the ocean, whats happening is that your GPS device is defaulting to a set location while it waits to get the data from the satellites needed to determine your location. It has no idea where you are and is just displaying that temporarily until it has the info it needs"
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k6aena | How do etch-a-sketch’s work? | Technology | explainlikeimfive | {
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"Contrary to popular belief, the stylus you use to draw doesn't draw the line. The inside \"screen\" of the toy is coated in aluminum powder, and when the stylus scrapes it out, it reveals the darkness inside the toy. When you shake it upside down, the beads inside the toy coat the screen, making it look \"blank\" again. EDIT: Funny how you marked it technology.",
"The etch-a-sketch is filled with a sticky aluminum powder that coats the screen when you shake it upside down. Inside the machine is a stylus that rides on the screen and is connected to two sliding rods that are moved by cables attached to the control knobs. Turning the knobs slides the stylus acrosss the screen scraping off the aluminum powder and leaving a dark line in the screen. [This]( URL_0 ) is the machinery inside under the screen.",
"You can see how an etch-a-sketch works by drawing over the entire screen. As you draw bigger and bigger black spots, you start to see through. The lines aren't black ink. The lines scrape off a powder coating on the inside of the glass, exposing the inside. When hardly any of the screen is clear, the inside is dark, so you see a dark line. But as you start to clear off bigger areas, you see inside. What's there is a sort of stylus, pressing against the screen, and a vertical and horizontal bar which move the stylus around when you turn the knobs. The stylus scrapes the grey powder off off the glass. There are also a bazillion tiny balls. When you turn the etch-a-sketch upside-down to \"erase\" it, those balls spread the grey powder all over the glass, covering up the parts you cleared off. Try it! It's cool."
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k6d961 | How does water ruin circuit boards? | When I drop my phone in the toilet, or dive with my phone in my pocket, or spill water on my notebook, what happens to it? Why does it stop working? Is rice any better than just letting it dry? | Technology | explainlikeimfive | {
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"Water (or more accurately the impurities within it) conducts electricity, so when electronics get wet the water redirects the electricity within the device resulting in electrical faults. Sometimes an electronic device may work again after it has been dried, but if it isn't properly dried or the misdirected electricity shorted components within the device it may be permanently affected."
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k6hu0a | How did phone operators work in the past? | I love watching old movies and TV. Often times they have characters who use telephones via the old switchboard technology. Someone calls into a central system where their call is routed to the proper location. How did those switch boards work? Especially in comparison to modern phones... (I would also love any extra info on "party lines" where anyone could join) | Technology | explainlikeimfive | {
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"Way back in the day, when telephone lines were new and neighborhoods were small and close-knit, people would share a single telephone line. Meaning, instead of dialing a number, you simply picked up the phone and “rang” the line, usually by sending a small current through to ring a bell connected to the phone. This would cause everyone’s phone to ring, and everyone would scramble to the phone to see if it was for them or someone else. As more and more people became connected with this technology, it became apparent that having entire cities put on one phone circuit wasn’t an option. So different lines were split up into smaller sections, and instead of leading to each other, all of the lines lead to one area: the switchboard. A switchboard operator would sit and wait in front of the board, and when a call came in for the operator, that output jack would light up. The operator would put a headphone jack into that line, ask who you needed to call, and then physically wire your phone line directly into theirs. Today we have massive server farms with computers set to automatically handle these connections, but this is where all of our telephoning terms come from. Busy: someone else is already talking to who you need, meaning that there is a line into their phone already. You physically could not talk to anyone until the first person was done. Operator: the person who would actually connect you to your intended recipient Telephone technology back then was simply a more sophisticated version of two cans and a string, but the string is now wire and the cans are specifically designed receivers that hook to this wire together. When two people are on the same line, they can talk. We still use this basic form of telephoning with landline phones, which is why you can still pick up a phone in the house while someone else is using it and listen. As for party lines, just imagine getting a third can and tying a new string to the middle one. Now speaking into one can let’s both others receive your voice. Bonus fun fact: in rural areas that couldn’t afford proper phone line, people would sometimes hook their phones to their fences. Many of these fences had unbroken lines of wire that ran along multiple houses, making them a perfect substitute infrastructure.",
"Those switching boards connect individual users. Back then when you picked up the phone, someone in the call center answered it. If the line was free, then they would connect you to the other side. What they basically did is connect those 2 endpoints with a cable so you can directly talk to the other. After that those switching boards where automated. That's why we have phone numbers, so it can be done without an operator. Rotary telephones used electric pulses to tell the call center who you want to call. Later those rotary dials where changed to the push-button phones. Bell System developed it under the name Touch-Tone, also known as DTMF (Dual-tone Multi-frequency signalling), which is still used today. Modern phones are much more complicated than the old ones, but the concept is the same. A mobile phone sends out a message to the call center that he wants to talk to this number. The call center then routes that traffic in the direction of the number (to other service providers network for example). If the other side is free then it's sends back an OK. Audio codecs are selected as well."
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k6i7xg | Why does the screen momentarily turn black when plugging in a second monitor? | When a second monitor is plugged into a laptop, its screen turns black for a brief moment. Why does this happen? See example: URL_0 | Technology | explainlikeimfive | {
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"The way computer monitors work is that, many times per second (usually 30 or 60 times per second depending on your monitor, but sometimes even more), your computer calculates what should be displayed on the screen - calculates a color value for every pixel - and then updates the image on the screen based on that calculation. This is called a \"screen refresh\". For example, imagine that you are running an application that has a button and a text box. During every refresh, your computer would go through a process something like the following (no need to actually pay attention to the math; it's just an example): * This text box is 200 pixels wide and 100 pixels tall, and is white * This button is 20 pixels wide and 10 pixels tall, and is blue * The text box is 20 pixels below from the top of the application window * The text box is 20 pixels from the left of the application window * Therefore, pixels (20, 20) up to (220, 220) inside of the application window need to be white * The button is 20 pixels below the bottom of the text box, which is 220 pixels from the top of the application window * The bottom is 20 pixels from the left of the application window * Therefore, pixels (20, 240) up to (40, 250) inside of the application window need to be blue * The application window itself is 100 pixels below the top of the screen * The application window is 100 pixels from the left of the screen * Therefore, pixels (120, 120) up to (320, 320) on the screen need to be white * Therefore, pixels (120, 340) up to (140, 350) on the screen need to be blue Of course, this is *vastly* oversimplified - in reality, there are much more complicated things being calculated, the results of some calculations can be reused across multiple screen refreshes without needing to be recalculated, etc. But this is the basic outline - every 30th or 60th of a second, calculate what color every pixel on the screen needs to be. Have you ever been on a computer that is lagging for some reason, and the screen is sort of \"jittery\"? What's happening there is that it's taking longer for the computer to calculate what to draw on the screen than the allotted time budget (i.e., longer than a 30th or a 60th of a second), and so it's updating the screen less frequently; if it updates infrequently enough, the illusion of motion is broken because your eye can see the individual steps, kind of like a really low frame rate movie. When you plug in a new monitor, your computer has to do a *bunch* of calculations - *way* more than it would do during a normal screen refresh. This includes things like \"should I move this window to the new monitor that just got plugged in?\" and \"do I need to change the screen resolution?\" and other things that will affect what's displayed on your old monitor. There's no reason in principle that your computer couldn't try to keep updating your old monitor while this is all being calculated, but if the programmers weren't super careful, you'd end up with lots of weird effects that would be visually confusing (e.g., maybe first the resolution would change, and then later one window would disappear, and then even later a second window would disappear, and then even even later both of those windows would appear on the new monitor, etc). Since monitors getting plugged and unplugged happens relatively infrequently, it's much simpler - and provides a cleaner experience for the user - to just blank everything out until all of the calculation is done. For the same reason, your screen will go black when you make other big monitor changes like changing screen resolution."
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k6kdz3 | How does video data travel vast distances so quickly (in milliseconds) on Zoom chat? | Recently had a zoom chat with my cousin in US (I am in India). Still blown away by the fact that millions of bits of video and sound data can travel across half the planet in seconds. How is it possible? | Technology | explainlikeimfive | {
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"Data travels at the speed of light, minus time for processing and routing. At the speed of light it takes .13 seconds to go all the way around the world (a full circle) and in your example it didn’t have to go that far.",
"The distance (along the surface) between the US and India is about 13,500 km. Your data will travel close to the speed of light at around 300,000 km/sec. In an idealized sense, this means it will take roughly 50 ms (about a 1/20 of a second) for the data to travel. Obviously there is some pre- and post- processing of data sent that must be done and the data doesn't take a direct route, but all these things generally are much smaller factors than the physical travel."
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k6m4db | Why did it take us so long to be able to draw in 3D while humans have been sculpting 3D statues for millennia? | Technology | explainlikeimfive | {
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"Because traditionally you draw on paper. Which is 2 dimensional. Drawing things 3d on 2d platform is just visual manipulation off 2d art to appear 3d",
"It’s not that “3D” drawing was unknown, it’s that the idea of art as being representative rather than figurative is a pretty new concept. Artists in Ancient India and Medieval Europe weren’t aiming and failing for realistic depictions, they were in a way abstracting for some aesthetic reason. The introduction of perspective in Renaissance art was controversial particularly in the context of religious art, because depicting heaven realistically blurred the line between the transcendent metaphysical world and the “real” physical world."
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k6mepm | Why are screens and video imagery rectangular, while camera lenses are round? | Technology | explainlikeimfive | {
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"The sensor inside the camera is rectangular, so the image the camera creates is rectangular. The lens focuses light on the sensor, and could be any shape as long as the light ends up covering the sensor (think about eyeglass lenses: they often aren't round). However, it's easiest to make round lenses, so that's what they use.",
"Rectangles are easy shapes for screens and sensors; circles are natural shapes for lenses. It's really not more complicated than that."
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k6mex5 | How do headphones make it sound like the sound is coming from behind you/in front of you? | Technology | explainlikeimfive | {
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"The headphones do not do that. The recording or software that produces the sound that is responsible. You tell if a sound is common from in front, behind, above, or below by how your ears and skull interact with the sound. If you do [Binaural\\_recording]( URL_0 ) with a fake head with ears and put a microphone in each ear the recoded sound. Now the sound has been changed the same way as when you hear is normal and you can play it back in headphones. A computer can simulate the effect and change sound the same way a human head does and the result is the same.",
"So, true surround sound speakers that offer 5.1 or 7.1 actually have multiple speakers in each headphone cup... to do exactly the same thing as a multiple speaker home theatre setup. Cheaper, virtual surround headphones can fake it to a certain degree. And how they do it depends on the manufacturer (the methods are quite proprietary). But probably one of the ways they do this is to modify the frequency mix of the sound to take advantage of your skull and ear shape. Sound reaches your inner ear from a multiple of angles. Most of it comes as compressed air or sound waves bouncing in off your ear, into your ear canal and across your eardrum. But some of the sound we hear travels through the back of our skulls, or through the back of the ear. Obviously that sound is altered and dampened somewhat, but your brain knows that if hears sound that is muffled by your skull more than how it sounds if it comes through your earhole, then it knows \"oh, that must be from behind me\". So if you know how _that_ mechanism works, you can modify your sound to \"mimic\" the \"from the rear\" sound and your brain interprets it as \"behind\" you."
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k6mge2 | What is a Sprite and how is it different from a regular image? | I've read several articles about this topic, but I still don't get what exactly a sprite is, why it's used in game dev, and how it's different from any other image. | Technology | explainlikeimfive | {
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"A sprite is generally a smaller image that's composited onto the background image--they're generally used for moving objects in 2D games. Many computers and consoles back in the 2D days had \"hardware sprites\", meaning they had the built-in capability to have these things moving around without disturbing the background.",
"A sprite is just a way of describing an image that is used to represent an object that isn't static. For instance, in Super Mario Bros, Mario has a sprite, as do Goombas, Piranha Plants, and other enemies. Things like the ground or pipes are images and not sprites. Some things are a combination, such as the flagpole being an image, but the flag itself being a sprite. Often times, sprites use slightly different tools for how they're done programmatically. The main distinction is the use of a Sprite Sheet, which is a whole series of images that represent the object in different states. For instance, Mario has sprites for standing, some for walking, jumping, ducking, firing a fire flower, and so on. Rather than reference a different image for each state, the system can just reference a different position on the sprite sheet."
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k6o8o3 | is it more efficient to turn off your heat or to turn it down when going to sleep/leaving your home for long periods of time? | Technology | explainlikeimfive | {
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"It's always more *efficient* (or at least *as efficient*) to turn it off, but that's not the primary concern when it comes to one's home. Overnight, there's a minimum temperature below which the occupants will get uncomfortable. Set the thermostat to that level. If the home passively retains enough heat overnight to remain above that level, your energy savings will be identical to turning the heat off entirely. There's also a minimum temperature below which damage can occur to plumbing and appliances. When leaving the home for a day or longer, set the thermostat to that level to avoid expensive repairs. Again, if the home passively retains enough heat while you're away to remain above that level, your energy savings will be identical to turning the heat off entirely.",
"Heater is usually an on/off switch controlled by a thermostat. Basically it runs this computer code in a loop: ``` IF current_temp < set_point THEN turn_heater_on() ELSE turn_heater_off() ``` Say you keep your thermostat at 70 when you're awake, and 60 when you're asleep. If it takes your house 15 hours to cool down from 70 degrees (F) to 60 degrees, there's no difference between turning down to 60 vs turning it off when you sleep (assuming you're a normal human who sleeps for less than 15 hours a night). Think of it this way: Option 1, turn it off. Option 2, tell the computer to turn it off as long as it's above 60 degrees, but it never actually gets below 60 degrees. There's a big benefit to turning it down instead. If you're in an area where it gets below freezing in the wintertime, setting the heater to a low value keeps pipes from freezing, if you're unexpectedly away longer than planned. How long it takes your house to cool down depends on a lot of factors: Outside temperature, size of your house, insulation, windows, opening / closing of doors. Nowadays you can get a thermostat that you can set to change temperature based on time of day, or even lets you control remotely from your smartphone (so for example if you're running errands and don't know when you'll be back, when you're done with your errands and ready to head home, you could use your phone to tell it to turn up the heat.)"
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k6o9df | why tech companies are in San Francisco when they could have cheap offices and fast internet pretty much anywhere? | Technology | explainlikeimfive | {
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"It's a self-sustaining cycle. Tech companies are in the Silicon Valley. That means the talent (engineers, programmers, etc.) go to the Silicon Valley to work. If you form a new company, do you want to be in the middle of nowhere where you have to fight to attract employees? Or do you want to be in the Silicon Valley where you can just poach from Cisco/Oracle/Apple/Facebook/Google/Intel, etc.? And employees face the same question. You could get a tech job in Kalamazoo. But if you don't like that job, there's no local employer to move to. So you take the job in Silicon Valley. If you don't like it at Google, you go to Facebook just down the road.",
"Silicon Valley originally arose around San Francisco because universities around there, including Stanford and Berkeley, were pioneers in early computing. Now, tech companies continue to have headquarters in San Francisco because that's where the industry is. Sure, it's expensive to be there, but there are a lot of benefits to being where all the other tech companies are. There are lots of tech employees there, so you have a lot of people you can hire without them needing to relocate. There are tons of associated businesses there; if you need a PR firm, or a law firm, or investors, who are specialized in working with tech companies, SF is where you'll find them. Even though it's possible to do a lot of this stuff remotely, and you don't need to be in the same city as the people you work with, it's preferred, so companies want to be where all the other companies are.",
"Prestige and access to talent. These days, when anyone in tech can arguably work more productively remote, it's mostly prestige.",
"It's where the whole ecosystem developed... research at universities like Stanford spun off companies who stayed in the area and recruited from those schools to get top talent. Other tech/programmers, etc. moved to the area because of the concentration of jobs. Investors/Venture Capital firms were also in the area, so it's easier to seek out funding for new companies if you're in the area. Some tech companies are starting to move some operations out of Silicon Valley. Apple has offices in places like Austin. Hewlett-Packard, the original Silicon Valley company, recently announced it's relocation to Texas. It will be interesting to see what happens as more workers work remote. I suspect companies will remain in the Valley but downsize their presence and perhaps set up small satellite offices in various cities for remote workers to occasionally use, hold meetings, etc.",
"For the same reason that here in Canada all of the big financial institutions are in Toronto rather than Regina or Prince Rupert where it’s much cheaper, because that’s where the most talented graduates and the supporting institutions are. A lot of people want to live in big cities and it is difficult for some companies to find people who are willing to work in more provincial areas, especially if they aren’t getting really big relocation bonuses."
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k6p1bt | How does 3D printing work? | Technology | explainlikeimfive | {
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"A long string of plastic is slowly fed into a heated nozzle. Plastic melts and is placed very precisely onto a heated surface (which allows it to stick during printing.) One layer is placed at a time, and by the time a following layer is placed, the layer under it has cooled enough to fully solidify. Actually quite simple. Printing with metal is more complex; to my understanding, essentially metal powder is placed in a thin sheet and a laser heats it up in specific places to solidify the powder into an attached layer. When the print is done, excess dust is carefully removed."
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k6t10o | If we know the algorithm used for current day password hashing, how can we not just undo it to get the password? | I have read that SHA-2 is currently unbroken due to the amount of resources and time it would take to crack the hashing, but if we have the step by step algorithm, why can we not just do the steps backwards? | Technology | explainlikeimfive | {
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"Because it is a one way function. This means that it is - at least - practically infeasible to invert it. Optimally it would be a function that doesn't even have an inverse. There is one operation called \"modulo\" where one basically divides a number x by y and receives the remainder. So for example 7 mod 2 would be 1 because it is 3 with remainder 1. This means I can have an infinite amount of numbers mapping to the same output, but you can't reverse it. If I give you 7 mod 2 you can easily see it's 1. But if I said \"I received 1 when doing modulo 2\" you can't know it's 7, it could as well be 9, 11 or literally any odd number there is. So even though you know the \"algorithm\" to get from 7 to 1 by using modulo 2, you simply can't reverse the process. This is the main principle hashing functions use, thus you can't just invert them.",
"Because in a hash function, information is lost when you run it. That's why it is called a hash...it's like running meat through a grinder. You can't put it back together again. Except a cryptographic hash is semi-unique. Keep in mind that you can run a 2000 page document through a hash and get a result that's 16 bits long. \"*Once bread becomes toast, it can't go back.*\" - Ajax",
"> if we have the step by step algorithm, why can we not just do the steps backwards? Let me give you an over-simplified example. Here's my hashing algorithm: 1. Take the password, and replace each letter with a number representing its place in the alphabet. So A=1, B=2, C=3, . . . Z=26. 2. Jam all the numbers together into one long number. 3. If there are not an even number of digits, prepend a zero to the beginning. So 126 would become 0126 4. Group the list into a series of two-digit numbers. 5. Add all the two-digit numbers together. 6. If the resulting number is more than two digits long, go back to step 3. Otherwise, continue. 7. The result is your hash So if your password is \"password\": 1. P=16, A=1, S=19, S=19, W=23, O=15, R=18, D=4 2. 16119192315184 3. *already an even number of digits* 4. 16 + 11 + 91 + 92 + 31 + 51 + 84 5. 376 6. *number is too long, go back to step 3* 3\\. 0376 4\\. 03 + 76 5\\. 79 6\\. *number is short enough, go to step 7* 7. Your hash is `79` Now that you've seen how this works, your assignment is to take `42` as a hash and reverse the above steps to find out what the original password was. I'll wait. . . . Can't do it, can you? That's because the above algorithm is a one-way function. It cannot be performed in reverse, because it throws away information. The only way to find out what password results in a hash of `42` is to *try to hash every single possible password* until you find one that gets the results you want."
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k71yhl | Why do email addresses have the form of websites? | Or what does ends like .com mean? | Technology | explainlikeimfive | {
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"text": [
"Email comes from the days when there were a very small number of computers on the internet, and they were all big computers that had lots of different user accounts on them. When you sent someone an email, you had to say what server you were sending it to, and then which account on that server. Email still works the same way, but now the server is the server for your email provider, and the account name is your email account. The way to identify the server is to use a web address. (there's another level as to how web addresses actually mean anything, and I can get into DNS if you want)"
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k73gcn | Why are solar panels only like ~20% efficient (i know there's higher and lower, but why are they so inefficient, why can't they be 90% efficient for example) ? | I was looking into getting solar panels and a battery set up and its costs, and noticed that efficiency at 20% is considered high, what prevents them from being high efficiency, in the 80% or 90% range? & #x200B; EDIT: Thank you guys so much for your answers! This is incredibly interesting! | Technology | explainlikeimfive | {
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"Physics and cost. The theoretical efficiency limit is 95%. This is solely determined by the temperature of the sun and the temperature of earth. Whatever you do, a higher efficiency is never possible. However, there are a couple of limitations. First, the solar panel has to *send out* light as well: the temperature of the panel is above absolute zero, so it emits heat. This brings it down to 86.8%. But that assumes that the incoming light comes from every direction at once. In practice, the sun only covers a small part of the sky, bringing it even further down to 68.7%. And that's still with a perfect solar cell! That assumes the cell is infinitely thick and has zero losses. If we try to actually build cells, the best we can currently do is around 44.4%, which isn't too bad! But those cells consist of multiple layers, use exotic materials, and are very expensive to construct. It is *way* cheaper to construct less complicated cells. Turns out we don't really care about the absolute efficiency: there is plenty of sunlight available. We just want the most power at the lowest cost. The most common (and cheapest) cell type is \"single-junction\". The theoretical efficiency limit for those is 33.16%. Then we have some losses due to the protective coating, the wiring, being unable to cover 100% of the panel with cells, and loooots of other small stuff. So yeah, it might not sound like much, but an efficiency in the 20ish% isn't too bad. Don't expect anything over 30% soon, because we're already rapidly approaching the limits of physics!",
"My physics teacher explained this to me and im basically 5 so here goes. The easist explanation she gave was to think about it like this. If friction, heat or even sound is generated, energy is lost. Energy goes into making those instead of into making electricity. Sunlight's hot right? Solarpanels heating up mean that energy is lost because that energy that was supposed to be converted into electrical energy becomes heat energy instead. Solarpanels also cant capture all the energy from the sun because some hit it at the wrong angle, or get messed up by the clouds. Like a big net trying to catch balls being thrown at it, but the gaps in the net are sometimes big enough for a ball to slip through. 90% is also a really high number for efficiency. Someone in class asked the same thing. Even gas cars dont have that. we could solve our energy crisis with an engine like that. If you knew a way, youd easily become the richest man on earth.",
"The main comment doesn’t mention WHY the single junction architecture cuts the theoretical efficiency down so much, so let’s talk about that a little in 5 year old terms. Solar cells work when a photon of light hits a semiconductor and knocks an electron across an electrical junction. This electron now takes on the energy that gained by crossing the junction, and this is the amount of energy that takes from the photon. But different colors of light have a different amount of energy, the violet and blue ones have the most, the red ones have the least. However, the junction has a single energy level. If a photon that has exactly the same amount of energy as the junction hits, all of its energy is converted to electricity. But most of the photons have more or less. If they have less, then they can’t hit an electron over the junction. And they can’t “gang up” either—no matter how many lower energy photons hit, they can’t knock the electron. So ALL of the energy from those photons is lost. Now if a photon has more energy, then it will hit the electron over, but it only turns the energy of the junction into electricity. The “extra” is lost. So these two factors greatly lower the theoretical efficiency. If the junction energy is too high, you will lose too many electrons that can’t activate an electron. If it is too low, you will lose too much energy from the photons you do get. In the case of silicon, the junction energy is pretty low, in the red region. So you get most of your photons but they are mostly cut off in energy. But most photons are in the green region and there are a lot more red photons than blue so it’s a decent compromise. Plus it’s an easy material to work with. Now, you can raise the theoretical, and therefore the practical, efficiency tremendously by having multiple semiconductor types each with their own junction energy. You arrange them so that the photons are likely to be absorbed in the region that has a junction energy that closely matches the photon energy. So you maximize the number of photons you get AND the energy you get from each photon. But these are harder and more expensive to make, so since we have tons of land to put solar on, making efficiency a lower priority than price, we don’t use those much. However in cases where efficiency is supreme, such as spacecraft, these are used.",
"The main issue is that its extremely difficult to build a single thing that can interact with the entire electromagnetic spectrum at once. Just like how your eyes cannot detect infrared or ultraviolet light. To make them detect that sort of light, we'd have to add entirely different components. That would make the entire thing more expensive and bigger. And we would have to keep adding more components and making it more expensive and larger for each one. Its not at all cost effective to do any of this. And that's even without the increased cost of manufacturing them, installing them and servicing them. Until we come up with a way of dealing with this issue, We'll never be able to get those very high numbers. And even then, we're still only able to get sunlight from a very small part of the sky. Anything but direct sunlight drastically reduces how much it can convert. Systems that track the sun are an improvement, but not a solution.",
"Tangential info : thermal powerplants (coal, gas, nuclear) are far from 100% efficient too, about 30-40% is converted into electricity, the rest is waste heat (which can actually be reused, in a cogeneration plant, to provide heating to neighbouring towns).",
"Aside from heat, not every ray of sunlight ( photon) is converted into electricity (moving electrons). Moving electrons is a moving charge which is basically an electrical current. So we want to make electrons move. Basically what happen is that a photon is sometimes absorbed by an electron. If this happens, the electron tries to move to a spot where it is accepted with its higher energy (a hole). It will often fail to find a hole and so the electron has to get rid of its energy again, by emitting a photon again, instead of moving. That's a loss. Electron-hole pairs are fussy about how much energy they will absorb. Too little and it is emitted again, too much and it is emitted again. So it has to be just the right amount of energy, like Goldilocks. This gives extra losses. Aside from that, the electrons need to find holes, and in order not to distract them, they need special material, with lots of moving space and little distractions. Semiconductors give the moving space, impurities give extra holes which accept electrons. But your material cannot be 100% impurities. Like a building, you need walls before you can build another floor. This 'supporting' material also means extra losses.",
"Light particles (photons) from the sun come in different energies. And the way that solar panels work is that if they absorb a light particle with more than X amount of energy (X depends on the solar panel material), then the panel \"produces\" an electron with X amount of energy (even if the light particle had much more). So you can choose X to be high so you'll get a lot of energy per electron (voltage), but you'll get few electrons (current) because fewer of the sun's light has that much energy. Or you can choose X to be low so you'll get a lot of electrons, but you're \"wasting\" a lot of the energy because their energy is forced to be that low amount of X. If you graph the amount of total energy you get depending on X, you get an [inverted U]( URL_0 ), with a maximum efficiency of about 35%. IIRC it corresponds to green light.",
"Oh glboy have you fallen down a rabbit hole. Search up simple engineering and their video on it. It's great",
"That's 20% of all the sunlight hitting the area of the solar panels. The solar cells only take up a part of the sunlight's energy spectrum defined by the materials used in the cell. I.e. standard silicon cells has a theoretical limit of about 30% accounting for this. From 30% down to 20% its mainly due to losses from heat, contacts (shading), resistive losses in wires, etc. etc. Record silicon cells perform up to 26.6%, however around 16-20% efficiency is the cost efficient alternative atm.",
"There are great answers here, most of them indicate this but it is worth saying: This is less a question about solar cells, it is more about how people understand numbers and particularly percentages. When you saw % you believed that there was a valid range between 0 and 100. But the actually range turns out to be something like 10-60. You also needed some references on that scale like 'oil is about 40' to give the number context This is true of all numbers, without context like units and min/max range they are meaningless. So when your governments quote percentages at you, be sceptical."
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k73hb4 | what is actually happening when your internet cuts out and you have to unplug the modem and replug back in again? | Technology | explainlikeimfive | {
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"There are many issues that could be solved this way. Memory leaks, overheating, software bug, hanging transaction. The reason turning it off is so effective is it wipes out everything and let's you start fresh.",
"Modems and routers are small computers, and like all computers, they have state. \"State\" means the way it is right now. A computer's state is all of the information stored in its various types of memories at each moment in time. That information includes instructions, and data records pertaining to the work it has done and what work it needs to do next. Just as an example, a router is keeping track of all the connections between devices on your home network and servers on the Internet. When you browse to a web page, the browser makes a connection through your router to a web server on the Internet to request the web page. The server responds, sending the page data back to the router. The router knows which device on your network to route the page data back to because it stored records in its memory to keep track of the connections. Because of a hardware flaw (a defect in the physical machinery) or a software flaw (bad instructions), sometimes a computer can get into a bad state. A bad state could be incorrect records stored in memory, running out of memory, getting stuck in a loop (frozen), or many other possibilities. Simply put, the device wasn't designed to deal with the state it's gotten itself into. It's a bit like getting lost on a journey because you were given bad directions (a software flaw) or you failed to follow the directions (a hardware flaw), and you didn't know how to find your way back because the directions didn't say. Unplugging the device and plugging it back in causes some of that memory to be erased, and then the device restarts from its beginning state, a known good state using the instructions and data that are stored permanently in the device. Restarting a modem or router is like restarting your journey from the starting point with a clean sheet of directions.",
"It could be any number of things, but none of them are supposed to happen. If you have to do this regularly, then your ISP is unreliable or your modem isn't working properly. Sadly, many ISPs do in fact provide shoddy equipment that doesn't work properly. Communication problems happen, but there are always supposed to be time-outs where if either side realizes there is a problem or successful communication hasn't been possible for a while, then they both restart the connection process automatically. You should never have to reboot it yourself if everything is working according to specifications."
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k7dqts | On Instagram, how is it that a celebrity can tell the difference between a DM from another celebrity and a fan? | Technology | explainlikeimfive | {
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"Just to note... a lot of these interactions are arranged outside of Instagram by their agent/PR/marketing people who all know each other to make sure everything is correct and good. Industry people all have lists of who to contact and such for each celebrity. Also, most agents/PR people don't want their clients (the celebrities) randomly messaging other people without a plan and approval... this is obviously not always followed That being said... verified accounts on instagram and twitter are easy to confirm whats going on.",
"I'm assuming that you never tried direct messaging a celebrity. But if you go try it you can see that the verified checkmark shows up next to their name. Also, I'm not sure if you know about the feature that when someone receives a message, they first have to accept it before comes up in your inbox. Before you do that the message shows up in a different inbox\\*(also called “message requests”). If you're already both following each other then you don't have to go through that process. Let's say that celebrity A and B are both following each other. If A messages B then the DM will show up in their normal inbox. But if B ISNT following A back then it first goes to a separate inbox. If a fan messages celebrity B then it will show up in the same one as if A messaged them but B didn't follow A. \\* I've attached a link that I think explains better than me, what the message requests look and act like [ URL_0 ]( URL_0 ) I hope I was of some help, but English is not my first language so if you need clarifications please ask."
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k7kgnb | If technology (phones, tablets, etc) are designed to be intuitive, why can't old people figure them out? | Technology | explainlikeimfive | {
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"Because there's a big difference in what counts as intuitive for you versus your grandparents, especially where it comes to technology. When you've grown up with computers and the Internet, a lot of the assumptions it makes get baked into the way you think. No one needs to tell you that a bunch of tiny pictures scattered across the screen open different apps when you poke at them because that's what they've always done for you. But the first time most older people encountered such a thing they had to figure that out with a lot of unrelated prior learning getting in the way. As a result, that concept is never going to be quite as intrinsically connected to its result for them as it is for you. And your \"intuitive\" smartphone is absolutely filled with such concepts. It's probably also a little bit that they've lived through information technology's early years, where things as reliable as a smartphone were unimaginable. Computers were weird and arcane and it was very easy to make them catch fire and fall over (figuratively speaking); it was better to leave them to the nerds. The fear that a lot of older people have that they're going to break something, I suspect, comes from that. Obviously, it'd be cool if we could design something that's intuitive both for you and your grandparents. But, well... intuitive is actually *really* hard. Even the somewhat restricted definition of intuitive that you're used to. Truly broad-scope intuitive design is genius-level stuff.",
"Because intuition and common sense aren't inherent in a person but the culmination of all their experiences. The elderly simply don't have the background that the current generation has. Ice had to walk many people through using a mouse to click icons. Early adoption of the mouse faced similar hurdles by the sale staff. There is nothing intuitive about modern technology, without the framework you get through interaction. The young get more of the interaction because it's new, they are more curious, and they learn faster, as well as have no preconceived bad habits. So what they can learn on one interaction, takes those that are far under perhaps a dozen. The mix of worrying doesn't help either. Talk to them of saving a file, and they think of a physical copy for instance.",
"This is actually a really good question. My theory is that old people can learn it just fine, but their refusal to adapt to it is an emotional response. They feel cheated that all their clever ways of doing things before technology were for nothing. Or they think if they play dumb with their new macbook, they can use that as a way to get their grandkids to visit.",
"I don’t think you can compare a generation growing up with technology to one that has not. They are like different languages and become inherent traits for people raised around it. Yes, I think an older user can adapt, but it’s not the same. My kids are raised in a generation that thinks if you touch a screen, it responds. It’s a learning curve for my parents to understand you can pinch to zoom. Technology and devices are loaded with hundreds of features that are aimed to meet most users where they are. I think there are too many factors to give a simple response why everyone doesn’t pick it up so easily."
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k7mtrj | How does the spark igniter on my gas stove know when the gas is off. | Technology | explainlikeimfive | {
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"The simple and obvious way is to just use a temperature sensor. The cool sweet modern way is to try and send current across the same gap the spark goes through. Flame is a good deal more conductive than air and can support a small current. Flame goes out, current flow stops, and electronics sense this and fires off some sparks."
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k7n7ul | how do night vision devices work? | Technology | explainlikeimfive | {
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"Three ways. Light amplification. They take the very little light that is there, and amplify it. Allows you to see, although does amplify some noise. Also very sensitive to bright areas. These are the cliche green night vision goggles you see military people use in movies. A single incoming photon triggers a single electron to be energized, sort of like a camera. But the device is setup so this single energized electrons triggers a reaction of a lot more electrons in the same area. This mass of electrons is then converted back into a mass of photons, that you can now see. So little bit of light, little bit of electricity, amplify to a lot of electricity, and then back to a lot of light. Near infrared. Near infrared is basically red, we just can't see it. It's emitted by things like the sun, it's reflection off the moon, light bulbs, etc. It then bounces off objects just like visible light. A camera can be made it pickup near infrared. A wider spectrum of light means more light available. Additionally, because humans can't see it, you can have a near IR light shining to light things up. It's a camera flash a human won't notice. This is what most security cameras do. Pretty much all digital cameras can actually see near IR, the sensors we use pick it up. It takes fancy cameras with lens filters to actually block out. Aim your phone camera at a TV remote and hit a button and you'll see the near IR LED in the remote. Well, unless you have a fancy phone with a fancy camera lens. Thermal camera. These cameras see far infrared. This is the light that 20 °C room temperature objects give off, opposed to the light that a 2000 °C fire or light bulb filament or 6000 °C sun give off that we can see. This is looking for the far infrared light the objects are emitting themsleves, not reflections, so ambient light from a source doesn't matter. It works the same in pitch black as it does daylight. This also differentiates warm and cool objects, and can even remotely measure temperatures."
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k7ni4z | How can a 1080p image be rendered at 4k? Where does the extra "pixels" or details come from? | I sometimes see how people share 4k,8k,12k,etc. versions of Images where the original was 1080p or a different lower resolutions. How does that work? Where does the extra details come from ? I can understand "stretching" pixels to fit a screen but not the other way around. | Technology | explainlikeimfive | {
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"It is called image super resolution. In simple terms, let's say you layout a 3 by 3 set of blocks on the floor. All are red except the center is green. Now let's say you want to increase it to 6 by 6 blocks, how would you go about doing this? It is actually the exact same question as with pixels. There are many ways to do this, but the absolute simplest approach would be to swap every block out with 4 of the same block. So each red block is now 4 red blocks, and the green is 4 green. So long as you still maintain the same location, it will now be a 6 by 6 grid with an identical pattern. On a screen with pixels, your computer sends 1 pixel to 4, 9, 16, etc to get to your viewing resolution, just like the blocks. This is also why if you do this too many times, it will start to look like a bunch of squares instead of a crisp image. Of course, at which point this happens becomes a visual psychology problem that's beyond the scope of the OP question. Hope this helps!",
"Your intuition is correct. There is no additional detail gained by just resampling at a higher res. Consider each character below a pixel. Original 'native' image is at 4x2 resolution: abcd abcd Upscale that by 2x, so 8x4: aabbccdd aabbccdd aabbccdd aabbccdd",
"Well it basically works like scaling a regular image. The new image is made buy guessing what values should be there based on the old image. The easiest way is nearest neighbor where you just pick the closest pixel in the original image and duplicate it to fill space. It's super easy but looks terrible. More practical is bicubic or bilinear scaling. This is where the new image looks at a square of pixels in the original image and merges all those to get the new pixel values. Bicubic merges 25 pixels in a 5x5 square, bilinear 9 in a 3x3 square. Larger squares are better for smooth features, but tends to blur sharp lines. Bilinear is good for preserving sharpness but is less good at smoothness. Modern TVs will tend to use smarter algorithms that look at the original image, determine what image features are present (sharp lines vs smooth gradients) and pick an appropriate scaling method based on that. There's at least one brand of TV that I'm aware of from Samsung, and probably more nowdays that uses a neural net to figure out how to scale up images and make it look good. The new image won't match what the original would be exactly, as it's still guessing at what should fill in the blanks, but it is designed to look good, not be accurate, and is more nocible when you start to upscale images past about 4x the original size. Neat neural net zoom enhance article here: URL_0"
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