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c8dkxz | What do businesses use the app “Looker” for? | I’ve read their webpage and wiki but still cannot understand. I know what SQL is and databases, etc. Is it just a way to interact with SQL data through a GUI? | Technology | explainlikeimfive | {
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"Looker is a data visualization tool, like Tableau. It takes data in its raw form and presents it in a friendly, human-readable form. It's very common when people like business executives want to peruse data."
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c8i3az | Why is it lightbulbs have to be replaced every so often but seemingly small lights (like those that indicate a TV is off/on) can last for 10 years or more? | Technology | explainlikeimfive | {
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"Older light bulbs are incandescent lights. They make light by heating a small metal filament with electricity. Over time that filament wears out and eventually breaks. Small lights like the power light on an appliance have been mostly LEDs for probably 30 years now. LEDs have a *much* longer lifespan, but until the last few years were pretty expensive to use in applications where you needed an actual bright light source. Now LED light bulbs are getting pretty cheap, and those will go years and years without needing replacement."
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c8ipl0 | How does fabric work? As in, going from say, raw cotton, to a cotton sheet or T-shirt | I ended up going down a rabbit hole on this subject tonight, I've watched a bunch of "how it's made" episodes and similar things, and I feel like I get the overall process, but there are still parts I can't wrap my mind around. Once cotton has been harvested, and had all the debris removed, it seems to be typically packed into a large bail. Now, at this point, what you have is a gigantic bail of short hairs. I mean, an individual cotton fibre, hair, whatever you want to call it, is probably only a few inches long, right? And they're all tangled up at random. I don't really understand how you go from that, to having a single long thread of cotton - like, the kind of thread you'd sew with. How do all those short hairs get combined into one long continuous thread, and how does the big mess of a bail get untangled into that? And then, once you have a spool of thread.. I still don't fully grasp how you get from thread to fabric. I've looked up things on knitting, and sewing machines, and looms, and it still seems like black magic to me. You're basically making lots and lots of tiny little loops/knots into a grid, forming a 2D sheet, out of what is essentially a 1D line, right..? I suppose what I don't get here is how it stays intact. Why, when you get say, a tiny rip in a cotton T-shirt, the whole thing doesn't just completely fall apart and unravel entirely back into thread. I found [this really cool image]( URL_0 ) of cotton fabric under a microscope, and I can see how it's all sort of held together with an under/over thing, basically each crossing trapping another piece of thread. But.. logically to me it seems that if you broke that at any point, the whole thing would just fall apart. And fabrics don't do that. You can maybe pull on a loose thread, but it stays mostly together even when cut. I find this whole concept fascinating, but I also just sort of don't get it on a fundamental level, so I'd appreciate if anyone could break it down as an ELI5 for me :) | Technology | explainlikeimfive | {
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"Friction Consider this. Take two pieces of paper and lay them on top of each other. Now pull them apart. Easy. Now take two phone books and overlay the pages one at a time. Now try to pull them apart. The friction from all the pages is so high you would need two semi trucks to pull them apart. URL_0 Same goes for rope. You have all those small short fibers. They get wrapped around each other into tiny threads with the friction between individual fiber preventing them from separating. They you wrap the tiny threads around each other to form larger threads. Then you wrap the larger threads around each other. Eventually you have a rope."
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c8j8ms | How/why does facial recognition have trouble with non-white personnel? | From the MIT researcher that wasn't noticed until she put on a white mask to the 'Kinect hates black people' jokes on gaming channels there are examples but beyond a vague 'there are mostly white men in the tech industry' nothing explains what the software is or is not doing. | Technology | explainlikeimfive | {
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"1. Because it got trained on white faces. 2. Because it uses a poor quality camera that can't accurately resolve the details of dark faces.",
"Machine learning algorithms need lots of labeled data. Essentially a computer is shown a picture of a person and the computer makes a guess whether it's a person or not. Then the computer is told the correct answer and the computer takes notes on what it got right and wrong and then adjusts itself. Sometimes this data is biased, such as being shown way more white people than black people. Because the computer primarily sees white people, it begins to associate white humanoid with person and black with not person in a more extreme case and not sure in a less extreme case. There was a really bad example of this a while ago where an AI started labeling black people as gorillas. Because the people it had primarily seen where white and the things that were dark skinned and humanoid where predominately gorillas not black people. & #x200B; With kinect specifically it may be a different problem that has a similar cause. Kinect uses an infrared camera and different skin tones (especially darker skin vs lighter skin) looks different in infrared so the more basic software wasn't capable of recognizing what it was seeing as a human (this actually has happened with hands free sinks before). In teams that are predominately white, it may not have come up during testing (engineering teams are often their own first tests) and they may not have thought about it."
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c8jxip | How do digital video game "keys" work? | Technology | explainlikeimfive | {
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"Think of it like a receipt number or proof of purchase. It’s just a serial number used to prove that you purchased the game.",
"Generally speaking it's a combination of 2 sets: 1. A key that follows a certain rule 2. A set of those keys. For example, Let's say our key is 6 characters long, the characters 1, 2, 4 and 5 have to be 1 or 0, the 3rd character is 2 and the 6th character is the sum of characters 2 3 and 4 minus the sum or characters 1 and 5 plus 4. All possible combinations are: 002004, 002013, 002105, 002114, 012005, 012014, 012106, 012115, 102003, 102012, 102104, 102113, 112004, 112013, 112105, 112114 Now let's say our product has an online activation and we want to control our release number. We think 10 serials are plenty for now, so our server will only accept the keys 002004, 002013, 002105, 002114, 012005, 012014, 012106, 012115, 102003, 102012. Any other valid key will be accepted by the installation but won't activate because it doesn't exist on our server. Now let's say our activation system is very strict, one activation per serial. A user activates 012005, the server ticks that number as activated while the program will allow it to install, a future user won't be able to activate the program with it again. That's how the system works, only on a much MUCH bigger and more complex scale."
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c8loyp | What are the technical reasons that prevent optical-fiber like broadband-internet bandwidths being directly beamed from satellites to home? | I was looking for the kind of internet speeds that are possible via satellites. GEO satellites tend to have very high latency and LEO constellations like Iridium and Globalstar have lower latencies but their throughput is lesser than ground-based broadband internet. What are the technical reasons that make broadband internet user-speeds difficult to achieve via satellites? | Technology | explainlikeimfive | {
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"The distance the data has to travel from the satellite to your receiver is the main problem. It's the same as being too far away from your wifi router or when there's lots of blockage in the way like walls. For satellite internet the blockages are mostly atmospheric conditions such as weather.",
"Power, noise, and bandwidth. A communications satellite has multiple transponders, each with maybe 36MHz bandwidth. The transponders are radio receivers and transmitters. They use a lot of power. For an economic successful system, you'll need to have thousands of satellites in LEO, and millions of users. Starlink is trying to build such a system, but you aren't going to see fiber-like speed. For weak signals, noise is a big problem. > [The Shannon-Hartley theorem tells the maximum rate at which information can be transmitted over a communications channel of a specified bandwidth in the presence of noise. ]( URL_0 )."
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c8n7gg | Can I run a modern computer game on a supercomputer e.g. Summit with its 148,6 petaflops, why/why not? | The world's fastest supercomputer is the American Summit with its 148,6 petaflops. I don't know exactly what that means, but I'm sure it's fast. The supercomputers are used for AI, various mathematical models and other research fileds in need of massive computing power. But what about say Minecraft or Fortnite, can I run those games on a supercomputer? What would that mean in terms of game experience? | Technology | explainlikeimfive | {
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"A supercomputer isn't really comparable to a single desktop PC. Really they're more like lots of servers connected via a very high speed network. In theory you could build a supercomputer from more or less standard PCs, maybe running some custom version of Linux. If that was the case, you could play a game on one of them. But then you'd be playing the game on one specific \"node\" rather than the supercomputer as a whole. Games are not designed to spread their processing workload across many computers, and even with an extremely fast network it might not even be that useful anyway because of the time it takes to transfer data between them.",
"It depends what operating system the computer uses. As the computer probably runs on Linux, then the answer may be yes, but there might be problems with drivers for a gamepad, whether it has a graphical user interface etc. It might also not have a graphics card, so the processing power could be incredible, but the 3D rendering could still be awful."
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c8rjk5 | Why Iran doesn't know how to build a nuke. Hasn't the technology been around for a while and isn't it public knowledge? | Technology | explainlikeimfive | {
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"Its not for lack knowledge but of rescources. Fissionable materials are SUPER rare and SUPER controlled. You can buy them in small amounts but enough to build a weapon would be near impossible to obtain without a third party noticing.",
"The problem isn't the knowledge, it's the fuel. Uranium exists in nature that mainly in two varieties (isotopes) - most of it is U-238 which is not \"weapons grade\", while a tiny bit is U-235, which is less stable and therefore suitable for making nuclear bombs. Uranium with a higher concentration of U-235 is called \"enriched uranium\". Enriching uranium involves separating the U-238 from the U-235, resulting in a higher concentration of U-235.",
"Baking a cake is easy. Anyone can do it. But if you don't have flour, or eggs, or an oven, or oil, and you can't just go to the nearest supermarket to buy them, it gets a lot harder. You have to build the oven. You have to learn to grow and harvest wheat and then mill it for flour. You have to learn to raise chickens. You have to build an oven. Etc... you can't just order nuclear bomb components from Amazon. They're expensive and the companies that can make them are highly regulated and monitored. remember, during WW2 the US build **an entire city** (Oak Ridge, TN) just to produce fuel for bombs. And at the end of the war we had **ONLY TWO BOMBS.** That was our entire nuclear arsenal after spending years and billions of dollars and using hundreds of the smartest scientists and engineers in the world.",
"The principles are public knowledge, but not necessarily the specifics of a design. As the other commenter said, the other limiting factor is material. It is not just rare but it requires specific technology to process or “enrich”. Basically the raw material is not pure enough to use for fission. Thus why it doesn’t do it in the ground. Centerfuges, or cyclotrons, are used to increase the purity of the material. Here is where things get contentious with the Islamic Republic of Iran. You only need to increase the purity to a certain level for use as fuel in a power plant. Iran has, despite saying they have no desire for a nuclear weapon, developed the ability and have proceeded to enrich beyond that level, towards what would be needed for weapons grade material."
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c8rvia | Why do planes take curved flight paths instead of flying straight to their destination? | Technology | explainlikeimfive | {
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"It only looks curved because you look at it on a flat map. The earth is a globe - a direct path on a globe will be curved when it is projected on a flat map.",
"They aren’t actually curved. They just look curved when you flatten a globe into a map. To prove this yourself, take a golf ball or baseball or something similar in size and draw a straight line on it. Then rotate the ball a quarter turn or so and look at it from the side. If you squashed that flat into a map, the straight line you drew would now look curved.",
"Because maps are flat and the earth isn't that's why it seems they are taking curved paths but in reality it's straight."
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c8rvnt | What is the mechanical process for recycling disposable coffee cups like the ones from McDonalds, which are made from a combination of plastic and paper? | Technology | explainlikeimfive | {
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"Depends upon your local recycling program. Most programs would not recycle these because it is too expensive. Most programs separate the products that are cost effective to recycle and send the rest to the landfill. Just because you are encouraged to put it in the blue bin, does not mean it actually gets recycled.",
"Quite simply a vast quantity of them (the majority I beleive) just don't get recycled. Most of the processes described will be too costly. Recyclable doesnt mean recycled just that they could should they want to."
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c8stnn | how do social services such as Snapchat allow you to save almost unlimited amounts of pictures and videos on the cloud. I could only imagine how many millions of people have thousands of things saved, where are these stored? How much space do they take up | Technology | explainlikeimfive | {
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"Well, a picture is about 600 KB uncompressed. It can be compressed to around 116 KB without much issue. Let’s assume that there are 100 million people who you Snapchat, and each person uploads 5 thousand photos 100,000,000 * 5,000 = 500,000,000,000 500,000,000,000 * 116 KB = 58,000,000,000,000 KB Each MB can hold 1024 KB 58,000,000,000,000 KB / 1024 = 56,600,000,000 MB Each GB can hold 1024 MB 56,600,000,000 / 1024 = 55,000,000 GB Each PB can hold 1024 GB 55,000,000 / 1024 = 54,000 PB Each XB can hold 1024 PB 54,000 / 1024 = 52.75 XB When buying storage, the more you buy, the cheaper it is. To host all those photos, it’d cost 12.7 million dollars at $0.23 per gig of storage. These companies also know that even if they offer the service of unlimited photo storage to everyone who uses their apps, not everyone use it.",
"They have large building full of servers which is where the images are stored. That, or they pay a 3rd party to use their server farm. On top of that, they usually down sample the images when you upload them which just means they lower the resolution. Most cell phone pictures are much bigger than a computer screen at full size so it doesn't hurt to just down sample them to a smaller size. Then they also save the file using compression algorithms that make them even smaller. These server farms are built to handle more than the current load and are constantly expanding. Technology allows to store more data in smaller spaces as well. I don't know what a site like Instagram would need for storage but it's multiple large warehouse sized buildings."
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c8sv5h | Why is it, with all of our technological advances, that we still don’t have cell service in all areas, especially pretty populated areas? | Technology | explainlikeimfive | {
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"Mainly, it's expensive to build more cell towers, and the companies that provide cell service don't see a need to spend more money on that."
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c8t8jz | Why marching into battle in a single file at a moderate pace was favoured instead of just rushing in as fast as you can? | Specifically talking about the period in history when guns were just starting to become widespread among different armies. Wouldn't slowly marching expose the troops to more artillery fire? | Technology | explainlikeimfive | {
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"Marching into battle single file was never favored. At any point in time. Marching into battle was done in a formation, such as firing lines with muskets, a shield wall, or a full phalanx. For the period of time you are thinking about, which would be musket formations, they were normally in 3-4 lines and they alternated firing. Front line would fire then kneel while they reloaded, then the second line would fire and kneel to reload. Then the third line would do the same, as did the fourth if there was one. When the last line was done firing the front was ready to fire again and did so. These weapons were also smooth bore and not very accurate, so they relied on volley shots that filled an area with musket balls.",
"Not sure what you mean 'single file.' You probably mean a single rank, as in people marching abreast. Anyway... The goal was not to close as fast as possible. The goal was to close with the enemy while maintaining the formation. Being the 'first' to make it to the battle line does no good if you don't have your buddies to your left and right.",
"Marching was used to maintain discipline and orderly formations. Dispersing your soldiers would help against artillery, but it was suicide against Calvary. A standard line formation would be 3-4 men deep and could mass enough firepower/bayonets to threaten Calvary. They could also form square formations to prevent them from being surrounded by Calvary. Individual spread-out men would be easy targets for Calvary. Musketmen might be able to get 2-4 highly inaccurate shots off in a minute, and by then the Calvary would have rode up and cut the soldier to pieces. Against a line formation, each calvaryman would be met with concentrated fire, then smash into a wall of bayonets, lose their momentum and be forced to retreat and charge the line again and again until they broke through or failed. In addition, artillery at that time relied heavily on direct line-of-sight and were not as deadly. Simply marching through a forest or under hill cover was enough to reduce the effectiveness of artillery."
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c8u95m | Why do cameras have different framerates for different video resolutions? | The DSLR that I own shoots video at 720p 60fps but 1080p at only 30 fps? Why cant it also do 1080p60? | Technology | explainlikeimfive | {
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"There is typically a limitation in how much data can move or how fast it can be processed. Much like a highway can be filled with fewer trucks for more cars, you can evenly trade off resolution (length of vehicle) for more frames (more vehicles). 720p frames are exactly half the data per frame compared to 1080p. 60 fps is double 30 fps. The amount of data generated by 720p60 is the same as 1080p30.",
"This is limited on the rate of how much information the camera can store/process. Let say your camera can store 65 million pixels per second. 720p is a resolution of 1280×720, or 921,600 pixels per frame. at 60 frames per second, your camera is recording the information of 55.2 million pixels per second. which is great! you camera can handle it. Now when you want to record at 1080p, that is a resolution of 1920x1080 pixels or 2,073,600 pixels per frame, so just over double the number of pixels per frame. at 60 frames per second, that would be 124million pixels per second, that is too much for your camera to handle, so we would have to cut the number of pixels to about half. To do that, you can either half the resolution down to 720p or half the framerate to 30 frames per second."
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c8vve1 | If my DVR records content from my cable TV provider (e.g., Comcast), why does it need to have an active internet connection to playback the recordings? | Technology | explainlikeimfive | {
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"For DVR content, that generally does not require an internet connection, for example, satellite services do not require it for DVR playback. For cable, internet connection should also not be needed, cable is a two-way connection, so you're always \"connected\" to your provider (although it may require you to actually be connected so that they can verify you're an active account). There are three other situations, 1) It may be an additional security measure. 2) There is some content that actually isn't DVR, but video-on-demand and may be pulled from the internet, but with cable this is uncommon as its nearly all pulled direct from the cable company, not via the internet. 3) in an effort to get more customers internet connected, they put an additional hurdle in the DVR process, its a roundabout way to get more customers connected. There's also a more obscure thing having to do with some ads, but thats not really applicable to cable either so I won't get into it."
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c935o3 | How does a regulator work? (Scuba Diving) Going down 15ft without one feels like your head is going to explode, but with one you feel fine..? | Technology | explainlikeimfive | {
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"It isn't the regulator that helps. The feeling you describe of your head going to explode is the air in your sinuses and inner ear shrinking due to the increased pressure as you dive deeper and deeper. Unless you equalise that pressure your ears start to hurt as the pressure outside your eardrum is greater than the pressure inside them so it feel like they are being pressed hard and it hurts. When you dive with a regulator you remember to equalise by holding your nose and blowing against the closed nostrils as a way to make the pressure inside and outside your head spaces the same. It is part of the training all scuba diving students have to go through. If you did the same thing on a breath hold dive you would also fix the problem. Because a reg is providing you with a steady and comfortable stream of air to breath you are more relaxed and equalising becomes easier to the extent that some people do it without thinking. Conversely, on breath hold diving, people can be more tense and not want to waste the little air they have equalising. That would be a mistake.",
"The regulator regulates the use of oxygen from the tank. One can go to 15ft even with a snorkel so having (or not) a regulator is immaterial and would not make a difference.The regulator does not make a difference on how you feel, it only enables you to access the oxygen tank.",
"There are a number of things going on. I'll address the \"head is going to explode\" sensation. As you descend, the water pressure increases. This is pressing on your body, on your wet suit, and most importantly your mask. Here's where the exploding head sensation comes from: your mask is being pressed toward your face by the pressure. This is the exact same effect as if something was pumping air out of the mask, causing it to press towards your face. In other words, relative to the outside pressure, there's now a partial vacuum in the mask. What you're feeling is that partial vacuum. Your eyes and the cheeks around them literally feel as if they're being sucked into the mask. Scuba divers counteract this effect by breathing into the mask slightly through their noses to equalize the pressures. Skin divers can do the same thing, but they only have so much air in their lungs to spare. This is why diving masks always cover the nose as well. If you try diving with goggles, the pressure on your eyes becomes unbearable after only a few feet."
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c99elo | How do electric circuits work? | I’ve always been very mechanically minded, although when it comes to electronics and circuits, I’m baffled. How can pieces of silicon and metal make my computer turn on, to being able to run games and programmes? | Technology | explainlikeimfive | {
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"The eli5: Electricity is a force like gravity. Electrons can feel this force, and flow like water. Wires and circuits are essentially change for the electrons to flow. When they reach a component like a motor they cause it to turn, like a water wheel. Other components often have mechanical analogs. Transistors can be seen as levers or doorways. Electricity flows against one side, opening or closing it. A clever arrangenent of these can create situations where flipping one lever closes.or opens others. This allows you to design a setup where a few small changes can alter lots of different things. Mechanical computers do exist, but are much much larger.",
"Well a circuit mostly is a conducting line connecting the power supply to whatever is put in as the consumer. But that is boring. It is better to also put in a switch. That switch basically interrupts the conducting line, unless it is closed. It gets really interesting when you have a switch that does not work by flipping a lever, but a switch that works by electricity (that is where the silicon comes into play, since it has some special properties). Those interupt the conducting line unless a current is fed into the side of the switch. And now you can build a circuit that switches the switch... or only switches the switch if two other switches are switched and so on. So that is basically playing very complex domino.... unless you notice that with two switches that switch each other, you can build a memory retaining thingy. With two electronic switches you can build a flip flop. A thing that keeps a circuit open once it is opened and closed once it is closed. It is a way to conserve information. If you put many a flip flops into a row, you got a register. Those flip flops flipping each other makes that register able to count... and do math. It is all really faszinating. You build a few circuits that add or subtract two registers when you flip a switch, and you basically have a calculator. From a calculator to a computer it is only a matter of upscaling. Your keyboard and mouse are the switches you flip and the cpu and graphics card do the calculating, shoveling data from one register (of which a computer has billions) to another. That's basically it. Everything else is software (in many different abstraction layers).",
"Certain materials called conductors or semiconductors can make electrons \"flow\" at the molecular level. As a very basic example imagine water going through a hose. This doesn't apply to all electrical circuits but for a basic understanding it is enough. There are different types of electricity, Alternating current (called AC) and direct current ( DC). Basically AC is for stuff you plug into your home using those pronged cords and DC is for batteries. The electric circuits you describe is different from the electricity that powers your house or your oven. Fundamentally it is the same concepts. Electricity is defined as the flow of electrons. They don't flow differently but for larger things like powering homes resistance is usually bad and for smaller things like microchips or your computer motherboard resistance is necessary because the amount of electricity is so small you don't want to fry it. Of course electricity on all levels must be regulated to the correct amount. It isn't just an \"amount\" to be set to. For example you can't just pour a certain amount of water into a plumbing system and expect it to work. Pressure and resistance in an electrical circuit must also be regulated. For electronics, which is different than residential electricity or construction electricity, there are a plethora of devices that are used to achieve these things. I'm not gonna lie to you, electricity can be confusing. I myself had only taken an introductory course to electricity and electronics mixed in with more advanced classes. But if you take your time to figure things out, basic problems can boil down to simple arithmetics. I realize my answer might be all over the place so if there's anything you still want to know that I didn't say, feel free to message me back and I'll do my best to explain or hopefully someone else can provide a better answer than me. I love learning the trades so I'd be happy to help you excel in your learning."
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c99i53 | - How do hydrogen cars work? Are they better than electric cars? | Technology | explainlikeimfive | {
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"Hydrogen fuel cells use the difference in charge between hydrogen and oxygen ions which provides the electric power to drive an engine. URL_0 Better is a rather subjective term and it depends upon what you are measuring and what weight you give. The output of a hydrogen fuel cell is non polluting, but the generation of the initial power might not be.",
"Hydrogen cars use the reaction between hydrogen and oxygen to make electricity and water. The electricity is then used to make the car go in the same way that an electric car goes. (A normal electric car uses a big battery to hold its electricity instead.) The water is released as exhaust. The problems with hydrogen cars are that A] hydrogen is expensive to produce, B] pure hydrogen tends to leak out of containers over time, even if you use thick metal walls, and C] hydrogen explodes if you mix it with air. These combined make them not a great choice for cars. At least until someone finds a way to fix all of those problems.",
"Hydrogen cars work off fuel cells, the technology used for electricity during the Apollo program to the moon. It's like a battery but it uses gas pumped into the electrodes. Electricity is generated in a chemical reaction where Hydrogen gas is on the negative terminal and Oxygen gas is on the positive terminal, which turns into water. There are pluses and minuses compared to electrical cars. Obviously you can get faster refuel times than electrical charging and therefore they might be better for longer range traveling, however there is currently no good hydrogen infrastructure to recharge tanks so right now that benefit is mostly hypothetical. Electric cars are more mature, design wise, but there are a lot of companies working on hydrogen cars, like Toyota, Honda and Hyundai among others. In fact, I believe every major car company has made at least a concept hydrogen car. Right now, today, I'd go electric, but I certainly hope they can make big advances in hydrogen, because I don't have a lot of faith they will ever get reasonable Electric car recharge times without damaging the battery life."
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c9agoi | "Private browsing and what your work can see." | Technology | explainlikeimfive | {
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"As a former IT guy, I can say that we can see the IP address of every computer, and we can see which machines made what requests on our network. So it’s just a matter of looking in the server reports to see what IP accessed what sites, and cross reference that with who has which computer or device on network. Sometimes we might not know the exact IP of a device but private browsing mode doesn’t stop that from being known it only keeps the computer from storing the history.",
"If you have an internal IT guy they can see everything regardless of if it’s private or incognito. They likely can access your computer remotely which means they can pull your monitor up on theirs in real time.",
"Private browsing is just on your computer, keeping history and temporary files from sticking, so people can't look at your computer later and see what you've done. Your browsing still goes over a network in whatever form it goes. Things that aren't in SSL are easy to see, but even things going SSL can leave some fingerprints, like hostname DNS requests and IP traffic. SSL doesn't guarantee privacy, either. If your company network is using an SSL proxy, the data will be encrypted to the proxy, possibly decrypted in the proxy, then encrypted again from the proxy to the end site. The legit reason for doing this is to check the content for evil, content but companies can do other snooping, too. Sometimes you can tell this happens because sites will warm you the certificate isn't what they expected. The only way to really conceal your internet presence is to use a VPN or other kind of proxy. Then all of your traffic goes through your proxy or VPN, always encrypted of you do it right, and to one sees any traffic other than that. Note these are sometimes blocked by companies, so that might not work at work. For an easy setup, look at TOR. Well, easy to see as their documentation does a good job of describing what it does. It still may not work at the office. I say these things only to answer the question, and don't endorse bypassing the security or other measures your workplace uses. If you need to do things they don't want you sound on their equipment, or that you don't want them knowing about, use a cellular service on your phone or tablet or laptop, and stay off their network. Don't get fired just for the mistaken need to browse the internet in unwanted ways on company time."
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c9ax6w | 5: Prior to the first moon landing, how did scientists get the necessary data to help them design the equipment required for them to land? For example: rockets, landing gear, space suits and stuff necessary for the astronauts re-entry into earth. | Technology | explainlikeimfive | {
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"Through space missions and experiments on earth prior to going to the moon. It's why there were space programs, like Gemini, before the Apollo moon missions.",
"In short, a lot of guessing and correcting (trial and error). First, it took the help of tens of thousands of people to send people to the moon and back. There were dozens and dozens of experiments and tests made to help the scientists and engineers design the right equipment that would be needed to safely take people to the moon and back. Each test would give a little more information and after enough tests we knew what we needed to do and what equipment to use. There were a lot of failures along the way and some of these failures ended up being very important in designing safe equipment for the astronauts."
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c9burx | Why hasn't Bluetooth been replaced by another technology such as infrared wireless, ultra wideband, induction wireless, etc.? | Technology | explainlikeimfive | {
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"Infrared requires line of sight. Bluetooth which uses radio waves does not. Bluetooth has a 20-30ft of range. Inductive has millimeters of range.",
"It sounds weird, but bluetooth was replaced by bluetooth, which was then replaced by bluetooth, most of the cheap bluetooth kit you see will be v2 with some v3 because the modules for it are cheap and mass produced so anyone wanting to add bluetooth functionality can stick a cheap chip in without any development work. Bluetooth 4 (low power bluetooth) is popular in higher end kit, Bluetooth 5 was released earlier this year with a lot of functionality designed for \"internet of things\" aka lets just stuff a computer into any random bit of junk and call it a new product. But really it's about picking the right tech for the right job. Need an ultra low power ultra short range (i.e. touching) wireless transmission go for NFC (door passes, credit cards and similar) need a short range low power transmission that can go a yard or two, use bluetooth. Need to transmit a signal around a house or small building use wifi. Need to transmit a signal between fixed points a few miles apart go microwave link.",
"what we need to do is start usuing gamma rays they can penetrate any wall and everyone needs a healthy dose of radiation"
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c9eyvx | What's the situation with 5G? Is it indeed that dangerous as people say? Or only in very high frequencies? Is the public uproar just overreacting? | Technology | explainlikeimfive | {
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"Decades of studies have found no link between cell phones and cancers like brain tumors. & #x200B; It’s easy to find claims online that the greater frequency of 5G alone constitutes a risk. [ URL_0 ]( URL_1 ) observes that “1G, 2G, 3G and 4G use between 1 to 5 gigahertz frequency. 5G uses between 24 to 90 gigahertz frequency,” and then asserts that “Within the RF Radiation portion of the electromagnetic spectrum, the higher the frequency, the more dangerous it is to living organisms.” & #x200B; But asserting that the higher frequency is more dangerous is just that—an assertion, and there’s little real science to stand behind it. 5G remains non-ionizing in nature. & #x200B; Scientists say that the most important criterion about whether any particular RFR is dangerous is whether it falls into the category of [ionizing or non-ionizing radiation]( URL_2 ). Simply put, any radiation that’s non-ionizing is too weak to break chemical bonds. That includes ultraviolet, visible light, infrared, and everything with a lower frequency, like radio waves.",
"People are not just overreacting, they are reacting on fake news. They don't bother reading some actually creditable research on the matter and instead formulate their opinion based on the things like social media or badly written articles. It's like when people found out that CERN is smashing particles together. No one gave a shit until someone mentioned that they might make black holes, then suddenly a movement went ape shit thinking it would destroy Earth. The truth, of course, is that if any black hole were to be made it would be micro black hole (so small that it would be considered quantum mechanics). There are so many reasons why it would not cause any danger that I won't even bother writing it here, but the point is people just hear something and start to panic without actually understanding the meaning of what they just heard. If we had named it something like \"quantum mechanical zero photon emitting cavum\" instead of black hole no one would care. People just took the words \"black hole\" and started using their lack of knowledge to panic. Same here, people don't even understand what 5 GHz is. they go like \"oh, it's higher than 4G!\". But try to actually look at it, 5 GHz is well below visible light. If 5 GHz was a problem you'd already be dead from normal light, considering it has more energy. In reality you need to get into ionizing radiation before it becomes a problem. 5 GHz means 5\\*10^(9). You need to get to around 10^(16) to have ionizing radiation (upper ultraviolet spectrum). What if I suddenly said \"water is actually giving you cancer with 100% chance!\", would you believe me and stop drinking water? Of course not. It is absolutely nonsense (and besides, the body is 60% water, so you'd be pretty screwed anyway if it was true). This is no different, some idiots have literally made up fictional problems and somehow it spread because the majority of people lack the ability to fact check."
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c9hrlo | How are developers able to program computers to be better at the game of chess than most humans? | Technology | explainlikeimfive | {
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"Chess is very well understood. Early chess computers worked by assigning a value to pieces and then having the computer simulate possible moves and see which ones an average lead to having a \"material advantage\". They would search through branches of possible moves and countermoves, thousands of possibilities. If a branch showed too much loss the computer would ignore it to save time. This made the play style of chess computers very distinctive and frustrating. Basically they were extremely conservative. They won simply by gradually building an advantage. Highly skilled human players generally didnt lose to some impressive trick or gambit or even incredible positioning. It just that pver time they made more small miscalculations than the machine. The endgame of chess is quite different. This material advantage strategy isnt the most efficient. Instead computers were programmed with the ability to play certain known endgames. Again the advantage of the computer is that it never makes any mistake executing the endgame. Newer chess systems like AlphaZero are harder to explain. Very roughly they start off playing almost randomly. Then when the match is finished they judge how well they did and adjust. This is repeated many thousands of times until the computer learns to play very well. The results of this had been much more interesting to human chess players than traditional chess computers. They play the game in a way that feels clever and aggressive. Even better we can track the learning of the system. AlphaZero reinvented a variety of known chess strategies on its way to playing at a superhuman level. (This is pretty validating to human players, it suggests that the traditional method really did just rely on outlasting the other player) Unfortunately systems like AlphaZero dont do a good job at explaining why they make the moves they do. So to an extent we don't know why they work so well even though it is known how to design them.",
"I feel like your question is: how can someone who does not play chess well, program a computer to play chess well? This IS an excellent question. We have to design a learning program, that evaluates chess games, and plays games then self-adjusts to win more. This is where the ‘value driven’ code looks for the best possible move to maximize value (eg: what move is most likely to result in checkmate? What move gets me closer to a move that results in checkmate? Etc, working backwards). Eventually, the computer can teach itself chess better than the people who programmed it. It also helps that the programmers will feed top level chess matches to the computer to learn from.",
"All the answers are good, but dense. I'll summarize AI in general: computers are fast, much faster than humans. You don't need to, as a developer, teach a computer how to win a game. You just need to teach it the rules and the objectives (i.e. what it means to \"win\"), and then set it out to \"learn\" the game on its own through what's essentially an incredibly huge amount of trial-and-error. Because it's so fast, it can \"learn\" the game much faster than humans can, and it's able to make better predictions than a human.",
"TL;DR Some clever shortcuts in chess strategy and good hardware. Basically, given a chess board configuration there are only a certain number of possible moves to get to the next one. There are a lot of possibilities (which is why this is significant), but since it's not infinite it's possible to list all possible moves and choose the best one. For simple games like tic-tac-toe, a computer can generate all possible moves, then all possible moves from those, etc. until it finds all possible ways a game can be played. Assuming that the opponent will always choose the best move, a computer can choose the strategy that results in it winning (or in a tie if a win is impossible). For chess, we simply don't have the hardware that can generate and store all of those possible moves in any reasonable amount of time. So programmers find clever algorithms etc. that can determine which path is most likely to lead to a win. Also, with better hardware, more options and more resulting options can be considered (thus why a \"super computer\" is better than your laptop)."
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c9i7hu | Why is it if I enter a successful password most systems log me in immediately, but if I enter an incorrect one, it takes notably longer? | Technology | explainlikeimfive | {
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"It's often a method of preventing brute force attacks. If you delay everytime you get a bad password, it slows down the attacks to the point either the attacker gives up or it gives intrusion detection systems time to say \"Hey, this guy is an asshat, block his IP\".",
"Edit: A quick search has revealed this is pretty much wrong in the modern world. Listen to /u/killfile ~~To add to what other people have said: If the system returned a failure as soon as it knew your password hash did not match the supplied password a malicious actor could perform something known as a timing attack where they get extra information based on how long a system takes to return information.~~",
"Also if your Identity is being verified against a distributed directory, password changes are usually made first against an authoritative directory server. If the directory server that first tried to authenticate you sees you have entered an incorrect password it checks with the authoritative server to make sure your password hasn’t been reset. This way it can log you in immediately after a password change without waiting for all directory servers to be updated.",
"There are also systems that might have multiple auth profiles. So first check is against a local database but then the system goes out to an LDAP or RADIUS server. The secondary auth methods take more time.",
"One reason for this is to make all failed login attempts take the same amount of time, so a malicious user cannot gain information about a login based on the response time. How could they do this? Usually you enter a username and a password. Typically passwords are stored as a hash so they aren't recoverable. To save processing time, a clever programmer may choose not to hash the inputted password until after fetching the user record for the inputted username. That way, if the user record isn't found, they don't have to waste time hashing the inputted password. If they do find it, they can hash the input and compare to the user record to see if it matches. But, this could leak information. If I enter a username that doesn't match a user in the system, the failed login attempt might return an error more quickly than it would if it found a user with the name I gave but failed the password check. Thus, I could learn at least if the username I entered actually exists in the system. By making a failed login attempt response always take a certain set amount of time, a malicious user cannot know how long it actually took to check the credentials and thus learn nothing about their partial validity."
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c9rgxn | Internet infastructure basics | I'm curious how servers and data centers and everything works. I've researched but everything I've seen seems so academic and high level. I was sincerely hoping someone could give me a quick overview of how something like Netflix or Wikipedia works with an emphasis on the layers or components in the path from company to consumer. Any light would be great! | Technology | explainlikeimfive | {
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"The question is how deep you want to go in. On the most basic level, everything is connected by cable. From your computer (either through LAN or WLAN) to you modem/router, to you Internet Service Provider (ISP), to other ISPs to the server. It isn't really any more complicated. There are many ISPs and the biggest one have a deal that allows them to share data without any cost. The smaller ones usually pay to use the data network of bigger ones. And thats the internet, a giant network of cables that are connected and maintained by many different corporations and state agencys. And in a data center it is not that different. In essencens the build a small 'intetnet' (they build a network of many computers, and the internet is just a network of computers all over the world). So when you click on URL_0 , you send a request to your ISP, who either is directly connected to the wikipedia server, or knows how to get to an ISP who is (such lists, who can connect to whom are well maintened). Your ISP connects to the wikipedia server, which takes the site you requested and sends it back. The only thing I have ommited so far is the DNS. Its kinda like a telefonbook. So you dont have to remember wikipedias ip adress but can just remember ' URL_0 '.",
"It's hard to explain because there are so many layers involved, but here's my go for how Wikipedia works. # Layers of the Internet The Internet Protocol Suite defines 4 layers on which internet communication occurs. They are, from the bottom up, the Link, Internet, Transport, and Application layers. Here are how those 4 layers, plus the Physical Layer from the OSI model (which is the layer below the Link layer) work to bring you wikipedia: ##Physical Layer: The physical layer is what it says on the tin: the specifications for cables, voltages, etc., required for transmitting raw bits (ones and zeroes). In this case, the physical layer would be the actual wires connecting your computer to the Wikipedia servers. This includes the ethernet cable from your computer to your router/modem, the coax cable from your modem to your ISP, and the massive trunk cables connecting cities together, as well as the mirror of all that on Wikipedia's end. ## Link Layer The link layer is what provides node-to-node data transfer, which includes stuff like coordinating which computers transmit when, establishes and terminates connections, and provides some error checking. This would be handled by the chip inside your computer that controls the ethernet port, and is listed in your computer as a network interface. It also includes MAC addressing, which gives computers a way to address eachother to communicate. ## Internet Layer The internet layer includes things like the actual Internet Protocol (IP). This provides the ability to transport packets across network boundaries, meaning that you can send packets from your own network to another network on the other side of the world. The basic function of this layer is to provide a way to address computers both inside and outside your network, as well as instructions for how to forward packets along to their final destination. It also provides for the functionality of 'ports'. Ports are like a gate in a castle wall, which can be opened or closed to let in carts containing cargo for a warehouse. But, only one service can be attached to a port at a time, so there are 65535 of them and they are standardized so that certain services are expected of be on certain ports (HTTP is 80, HTTPS is 443, SSH is 22, DNS is 53, Minecraft is 25535) ## Transport Layer The transport layer provdes the basic packets and transmission systems that allow you to send data. A packet is like a postcard: it contains information about where its going, where its from, the message, etc. The two most common types of packet are TCP, which focuses on reliability and maintaining connections, and UDP, which focuses on simplicity and data rate. Together, TCP and UDP make up almost all internet traffic. ## Application layer The application layer is what defines the different protocols used to format data sent in packets. Examples of protocols include HTTP, SSH, SSL, XMPP, and SMTP. Different protocols are used in different situations because they are optimized for formatting different types of data. HTTP, for example, is optimized for webpages, XMPP for chat messages, and SMTP for emails. # How this applies to browsing Wikipedia Here are the basic steps for what happens when you load the front page of Wikipedia, then search for \"dogs.\": 1. You type ' URL_0 ' into your browser and press enter 2. Your browser builds a TCP packet using the DNS protocol that contains a request for the network address of the server for URL_0 and sends it off to a DNS server on port 53. 3. The DNS server responds with a packet containing the network address of the server. 4. Your (web) browser assumes you want a webpage, so it creates a TCP packet with the HTTP protocol containing a GET request for the file named index.html (which means \"give me the front page please\". index.html is normally hidden from the URL, but is an HTTP codeword for front page of a folder) and addresses it to the address the DNS server responded with, on port 80. 5. The wikipedia server responds with an HTTP packet with the message \"here you go\", followed by a long series of packets that, combined, deliver all the text, images, and javascript that make up the front page of wikipedia. 6. You type \"dogs\" into the search bar and press enter. 7. Your browser builds a TCP packet using the HTTP protocol, with a POST request as the message, and sends it off to the wikipedia server. A POST request is a part of the HTTP protocol used for sending form data to the webserver, and is normally used for search boxes and login forms. 8. The wikipedia server analyzes the POST request's contents (the word \"dogs\") and searches its own local database for a matching entry. It finds the entry \"Dog\" and responds with an HTTP packet containing the instructions \"The matching article is Dog. Its location is 'wiki/Dog/index.html'\". 9. Your web browser builds an HTTP packet with a GET request for wiki/Dog/index.html and sends it to the wikipedia server. 10. The wikipedia server responds \"here you go\" and sends over the webpage. 11. Your web browser displays the webpage"
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c9rzan | What exactly is DNS, and what does enabling it do? | Technology | explainlikeimfive | {
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"Without DNS, if you wanted to go to a specific website, you'd have to type into your web browser something like 84.15.136.7:80. With DNS, you can simply put into your web browser URL_0 . The application of DNS is a server that your computer goes to and says \"hey, my user wants to go to URL_0 , what's the IP of that?\" The server then says \"hmm... Ah, here it is in my logs! It's 84.15.136.7!\" or \"Hmm... I don't have that in my logs right now, let me go check\" and consults another DNS server to find it."
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c9t5ts | Why was there a countdown on old film movies? | Technology | explainlikeimfive | {
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"Older films were so massive in terms of how many images were projected per second that they had to split them up into several smaller parts. A 90 minute movie might be broken into four sections of film, all spun into that familiar snowflake looking thing with little bits of film trailing off of it that we see emblazoned on movie themed restaurants and various getaways. That's a reel of film. You'd take this portion of the movie, and you'd have two or three projectors to put it onto. You would have to play a constant game of piggy back with the reels, winding and rewinding them, placing them on the projector, in order to screen a movie. It was done by hand back in the day, and there would be subtle indicators of when it was time to switch to the next reel. We call the smaller indicators \"cigarette burns\" due to their resemblance to when a hot end of a cigarette would burn itself into a piece of paper. Anyway, the projectionist knew to sync that shit up. However - - you had to sync it up to the other parts (reels) so that it made sense and seemlessly flowed like one big gigantic reel to the audience watching below you, the projectionist. When the time came to switch over to the next segment (the next reel), there would sometimes be a a helpful countdown with numbers and a spinny second hand like on a stopwatch. As a projectionist, you would match the timing on the reel that was just about to be unwound to the fresh, unwound reel that would be all the next stuff coming up in the movie. So, the people that made the print (the copy you're working from) would put in these little indicators of when it was time to switch over to the next reel, and they looked like what you're describing. If you were in a movie theater fifty or sixty years or more ago and saw that countdown thing, it would mean that the projectionist sucked, but over time it has become an emblem of watching a manually projected film. The countdown thingy gave the projectionist a chance to get the focus and intensity of the projection right before screening the final product. But raw film would often include this countdown, so it's used nowadays as a stamp of pseudo authenticity.",
"The film leader assists the projectionist in when to start the film and switch reels in longer films."
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c9tigq | How hyper precise lap time tracking, like in f1 or Olympics works? | Technology | explainlikeimfive | {
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"For F1, the cars have a transponder in the bottom of the tub, between the front wheels. There are loops burried under the surface of the track that register when the transponder crosses. The transponder transmits a unique code. Each loop decodes and sends info back to a main computer which tracks the times. F1 timing is accurate to 0.001 second. There's a backup transponder at the rear under the tail light. Page 43 of this PDF explains in more detail w/ drawings: URL_1 Photos of the equipment used + more detailed explinations: URL_0",
"I assume they use lap timers on each vehicle. I used to use these for track days. There's a very tall light curtain over the start/finish line. The light curtain emits a continuous bean of light which is very very thin. The light detector on each cars' lap timer is triggered whenever it passes through (\"sees\") this curtain. This is extremely fast and accurate. Telemetry from the timer is passed to the race officials and pit crew.",
"In Olympic swimming, each end of the pool has a “touchpad” for each lane. It senses applied pressures, and it the pressure is sufficiently strong, it will register a lap. That means the lap times record the foot touch after a flip turn (front crawl/backstroke) or hand hits (butterfly/breaststroke/finishes). There are also pads on the blocks to measure response time of leaving the block for starts and can measure false starts on relay exchanges when paired to the touchpad."
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ca0o2c | What is DNS over HTTPS? | Technology | explainlikeimfive | {
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"It's an experimental way of providing DNS resolution via HTTPS. It provides the advantage of not being vulnerable to Man-in-the-middle attacks (due to the TLS encryption in HTTPS), preventing DNS spoofing.",
"DNS is a domain name system, it is what allows you to search up soenthing like \" URL_0 \" and resolve that domain name to an IP address... Domain names mean nothing to computers. Doing something over https just means that the data sent is encrypted, specifically with TLS IIRC for https",
"Essentially, think of the DNS (Domain name system) as the internet's phone book. Websites as people you call using your phone. & #x200B; Thanks to the DNS (phonebook), instead of having to dial a phone number in order to call a friend, you instead just type in his name in your \"phonebook\" and reach him. As u/kryzsec mentioned, domain names mean nothing to computers so if you type in the \" URL_1 \" domain name in your browser's URL bar, but that domain isn't connected to a website, hosted at a server somewhere, with an identifiable IP address, [ URL_1 ]( URL_0 ) would only reach a blank / 404 page. Following the phonebook analogy, DNS is the phonebook. The IP address is the phone number. The domain name is your contact name. From within your phone's contacts/phonebook (URL search bar in your browser) you dial John (the domain name eg. URL_1 ), which is in fact the 0-800-123-45 phone number (an IP address such as 12.345.67.89). The idea is that it'd be pretty inconvenient for you to type down all sorts of digits / IP addresses in a document, God forbid memorizing them, so instead the IP address(es) are connected to domain names. Whenever you type in Domain Name X in your browser, it sends a message out to that domain's DNS, asking for the IP address of the server on which the website connected to it is hosted. Then, the DNS sends a message out back to you, resolving your domain name query with the appropriate answer; the IP address - giving you access. HTTPS is the secured / encrypted version of HTTP, secured by TLS or SSL. & #x200B; Edit: I just realized you're not asking what DNS and/or HTTP/s is, but rather a new protocol that I know nothing about to be honest."
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ca3qto | Why are computers and electronics in general restricted to binary system (0 and 1)? Why not 0,1 and 2? | Technology | explainlikeimfive | {
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"I'm no expert, but as I understand it that is because power is either flowing or not flowing to/through a system. Thus binary. Building a system that has three states becomes harder as the sizes we are talking about make perfectly steady streams of power difficult.",
"In the early years of computing, trinary and other systems other than binary was experimented with and sometimes used. In the end binary became the standard. This due to, among other reasons, that multiple level digital signals are more prone to error as the distance separating two neighboring levels becomes smaller the more levels you have in a given space, making it so a smaller disturbance can alter the signal an entire or multiple entire levels. in the end it was found that pure digital architecture could achieve efficiencies much greater than trinary or analoge architecture, part to being more robust and simple. Bonus Fact: very early computational machines where completely analoge. And the use of analoge computers, sometimes in combination with digital ones, persisted for some time. URL_0",
"You could theoretically have a base 3 system by having a cut off after which the number is incremented eg 0=0 v 1= 0-0.5 v 2= > 0.5 v but by having only two states it’s completely unambiguous at any given point whether it is zero or one.",
"The 1's and 0's in binary are used to represent the states of transistors being turned on or off. [Ternary computers]( URL_0 ) do exist, but are much harder to make since your transistors have deal with an extra state. So now your circuits would have to handle two different ON levels based on the voltage applied. Sounds simple but you'd be now adding more complexity to the circuit which would translate to cost for the extra transistors and complexity for programming such device.",
"Because Binary algebra is easier , operations gates AND, OR,XOR easy to create for binary but would be more difficult for any other system",
"The other answers are correct in that power on/off is easy to convert to binary and it's a convenient way to design and produce computers. But we did have ternary computers in the past (with 0,1,2 states). Mainly used in Russia. See URL_0",
"Because binary (0 and 1) is really simple to implement and allows for full Turing completeness. There is nothing that can be represented in trinary (0, 1, and 2) but not in binary.",
"Modern flash memory is an exception. Each cell can store one of four, eight or even sixteen possible digits. The different digits are stored internally as varying voltage levels but these are converted to and from 2, 3 or 4 binary digits.",
"At the deepest level, a computer still requires analog mechanisms. To use a 2, you have to define a 2 in some way in hardware. It's much easier to use 0 for off and 1 for on with high speed switching transistors. Using 1s and 0s in the right order gives you a way to represent 2 in binary: 0010.",
"Price pretty much. It's totally possible to have 3, 4, 5 ... or even 10 or more different voltages to represent different values. However the more different voltages you have, the more complexity is required from the transmitting and receiving ends and the more error prone the system would be as the noise affecting the data line could more easily change a value into another. On the other hand a binary system can represent any value a trinary or decimal system could so there's really no need to go for a higher ary system",
"In addition to being the simplest form of logic and therefore very robust and reliable, binary has other advantages. A transistor is like a brake pad on a car. If fully applied to the point of stopping the car, heat is produced while coming to a stop, but after that, no heat is produced since there is no motion. If fully disengaged, there is no friction, so again no heat. If partially applied however, it constantly produces heat. Similarly, a transistor would produce a lot more heat in its in-between states than in its binary states.",
"Because the entire basis of computer technology is, right now, limited by what we can mechanically achieve with electricity. As in - the earliest methods of binary computing used vacuum tubes. The simplest is \"Do I have electricity\" vs \"Do I not have electricity\". The output would then correspond to \"1, yup, 0, nope\". It's measuring a very definite state of that vacuum tube, and spitting out a 0 or a 1 depending on that state. The same kind of thing is happening with transistors, 1 it is storing electricity, 0 it is not. ;; If they add another digit to all of that, it needs to correspond to another state of that old vacuum tube, that doesn't already exist; if 0 is \"no electricity\" and 1 is \"have electricity\", then 2 would be...? In Quantum computing, they get another state which is \"both have and do not have electricity\"; but they've also built the entire rest of the computer to work with that hardware. We're a long way from publicly/commercially available quantum computing."
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ca46ea | Why can electric cars brake solely on induction? | How big would the magnet(s) have to be to equal the braking force of normal brakepads? | Technology | explainlikeimfive | {
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"When braking through induction the brake force isn't just depending on the strength of the magnet but also the speed of the car. At low speeds induction braking practically does nothing no matter the strength of the magnet as induction depends on the rate of change of the magnetic field and at low speed (=slow rotation of the wheels) that rate is always going to be relatively low. At high speeds though it could generate a greater force than normal break pads. In any case due to the low speed braking limitations you always need normal brakes, too."
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ca5kfa | Why some DJ's press unnecessary buttons in the mixer while performing? | Technology | explainlikeimfive | {
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"text": [
"Just because you didn't hear anything doesn't mean it didn't do a thing.. He was probably mixing under his headphones, preparing a transition, cue another song up, layer the beats. And a good dj would do all this in a way that someone who doesn't know the tracks won't notice a hard difference",
"There is a high chance that they are getting things ready for something coming up in a few seconds (like transition to a new song etc.)"
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ca6xr2 | Why not use 48 Hz for interlaced broadcasting? | From what I read online the PAL uses 50 Hz ,25 odd and 25 even, for interlaced video. What I couldn't find is the mention of using 48 Hz instead of 50 Hz since movies and shows are generally 24 fps. Can someone help explain this or at the very least link me to an article that explicitly mentions why they went with 50 Hz broadcasting instead of **48**. | Technology | explainlikeimfive | {
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"text": [
"If i remember correctly broadcasting is highly relative to power lines frequency which is 50 Hz in some countries. For example North American NTSC system works with 60 Hz."
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ca9b6p | How does RAM work? | I mean I know how to put it in, but like what does the ram chip actually do? I know it increases RAM storage, but how does that storage work? | Technology | explainlikeimfive | {
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"text": [
"Heres an analogy comparing a computer to an office desk Obligatory edit: the context here is OP's question, this is not nor ever was intended to be the end all perfect analogy. Remember ELI5 guidelines folks. The hard drives are long term storage, like file cabinets The RAM is how big the top of the table is, like how many papers you can look at face-up at the same time (after you're done 'loading' it into the table from said cabinet) The CPU speed is how fast you can move your hands to flip papers over and do stuff The GPU speed is how fast a printer can print out high definition pictures on a sheet of paper Edit: RAM doesnt store things long term cause the \"office\" has a clean desk policy, all desk papers gotta go to the file cabinet at end of day (when the power is off) cause the janitor will just throw away anything that isnt nailed down. A bigger file cabinet (high capacity hard drive) does hold more but isnt faster, one heavy-ass cabinet sure does hold a lot but it's hard to move. An SSD is like one of those tiny desk organizers with lots of little drawers, you can move stuff much quicker but it doesnt hold as much Dual core CPU is like having two arms, quad core like 4 arms etc. You can imagine that so many arms wont always be useful, which is why a 16-core CPU (lots of skinny spider arms) might not play games as well as a few beefy hulk arms. Hope this helps :)",
"I always use the book analogy. Imagine you read a book and can remember 15 pages perfectly. But for everything else you have to go back to the book and read it again . The book is the harddrive and RAM is what you can remember without needing to go back to the book. The more you have the less often you need to open the book and search for a info.",
"The RAM chip stores information using electric charge. There are several types, but essentially they all have a bunch of wires for selecting which \"locker\" to access and another bunch of wires for providing a number to store in the locker or read out the number that was stored in the locker. When you have 64-bit RAM, then each locker stores 64 bits = 8 bytes. When you have a 8GB RAM module, it has 1 billion lockers for storing those 8 byte numbers."
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cad13w | Why does data stop working while calling? | Was calling my girlfriend today on my way home. At some point my data stopped working so I couldn't send her any cute pet posts anymore. Ending the call and calling her again fixes it most of the time, but only until it stops working again. I went into the settings to look if I could change that, found a "VoLTE calls" option, disabled that, but eventually my data still stopped working. So can somebody explain why this happens, and what VoLTE calls actually mean? Thanks! | Technology | explainlikeimfive | {
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"text": [
"It depends on your carrier. You are most likely using a CDMA carrier such as Sprint and this type of infrastructure does not support being on a call and using data at the same time. CDMA is older technology and basically limits the amount of information that can be sent at any given time. In practice this means you can either be on a call or using data but not both. On the GSM network such as AT & T you can in fact use data and calls at the same time as this is actually required for the way the technology works. Essentially, it's because you're American and you use an older cheaper network which forces your phone to choose between data and calls. Change your carrier and upgrade your phone to something that uses 4G and you'll be able to do both at the same time."
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cadzwb | Why does the price point of a digital camera increase drastically with larger sensor sizes (4:3, full frame, medium format), when it seems like you would need fewer photoreceptors per square inch, and would otherwise be much easier to fit the image technology over a larger space? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"In semiconductor manufacturing you don't really pay for complexity up to a point. Once you've picked a manufacturing technology cost scales most strongly with area, not number of parts you fit in that space. A 1mm x 1mm device costs way less than a 2mm x 2mm device with the same design even though the second device is 1/4 the density. The only way going bigger saves money is if you switch to an entirely different manufacturing technology that is dramatically cheaper. But then you have to re-design your device from scratch so it's definitely not a free bit of savings."
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caehsb | How does ping, lags, and so on works in online gaming? | Technology | explainlikeimfive | {
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"text": [
"Ping = the speed at which a packet of data is sent between one computer and another (or a server). The lower the ping, the faster the data is going back and forth between the two computers. The higher the ping, the slower the data is going back and forth. So if you live in Los Angeles and you're connecting to a server in San Fransisco, you will almost certainly have a much better (lower) ping than if you were to connect to a server in Belgium. \"Lag\" can be a couple things. There's network lag, where your latency (ping) is high - the data is traveling slow between you and the server. That means your computer and the server are having a hard time communicating - you are entering the command to move forward but the server is still asking your computer what you're trying to do. This results in what's called \"rubberbanding\", where your character slides around, sometimes through walls, snaps back to where you were, etc. Then there's \"graphical lag\" which is really just lower framerates. It doesn't have to do with the network necessarily, it's just that your computer's struggling to keep up with the game so the video slows down.",
"All of these apply to delay. Ping is delay between your computer and the other computers you're connected to. Lag is a general term for delay. Ping could also be called network lag. Input lag is where it takes time for inputs (such as your mouse and keyboard) to reach the game. One example is where I move my mouse and a quarter second later the camera moves with it. Framerate lag is where the fps drops and the video looks \"choppy\". There are other kinds of lag, but those are the big 'uns. Generally, all of the lags compound, so each one makes all of the others worse. At the end of the day, all of this comes down to \"lag\" as a whole making games much more difficult to play."
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caelsz | How do blood pressure machines work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"With no pressure applied there is nothing to push against so no noise is heard. Like high fiving the air. As soon as a sound is audible that means you have matched a certain blood pressure. Continue to increase the pressure and eventually the sound ceases as it has been choked off. This pressure is the top number. Blood pressure is thus the pressure to start hearing your blood pump and when you stop hearing it pump. The process of taking a blood pressure does this in reverse. You pump the cuff to a higher pressure than the persons blood pressure, choking it off (inaudible), then you release it until you hear the pumping, top number, and continue releasing until the last audible pump is heard, bottom number. The machine would monitor for these audible pumps as a person would."
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caf0mk | how does an air conditioner work? | Technology | explainlikeimfive | {
"a_id": [
"et8b1to"
],
"text": [
"i can put it in lay terms. ur fridge has a gas container and this gas get really cold when it gets out of the container, so we runnit through tubes which freeze and we blow air around the frozen tubes which cools the fridge. then when the gas comes out the other side of the tubes a compressor pumps it back into its original container so it can be re released again and again and again."
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cag6zk | Some lower-end video games, especially indie games, run significantly worse compared to higher-end professionally created games on the same machine. Why is this? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"How programs work behind the scenes is more important to performance than what the graphics look like. AAA titles are usually heavily optimized to get them to run well on a wide range of PCs so the publisher has the largest possible audience. That's a lot of additional work on a game though, and requires time, manpower, and skills that a small indie dev might not have available.",
"Gotta be a matter of opinion. Got any specifics? I've played some shitty triple a titles in the past and some excellent indie games. Manpower, resources, skills, etc. Large studios have a wide range of talent to draw on for their designs while indie developers have to figure everything out themselves from a much smaller group of designers."
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campjb | how in big hotels, the range of Wi-Fi is practically everywhere and only under one SSID? | Technology | explainlikeimfive | {
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"text": [
"They're using access points. Basically the actual router is connected to several access points across the site and these access points create the wifi signal. But as they're hooked up to the same router and basically just act like an extension cord they appear as the same network.",
"They use enterprise class WiFi solutions. Basically, there's a device called a WLC (Wireless LAN Controller), it's usually sitting in the network closet (Where the modem and servers are). The WLC connects to several AP's (Access Points), these are the devices that are usually stuck to the ceiling that broadcast the WiFi signal. The WLC controls the AP's, it tells them what SSID to broadcast. You can actually name two normal WiFi routers with the same exact name and set the same password. The problem is that devices that connect to WiFi will connect to the closest one, but try to stay connected to it for as long as possible. Only when you lose the signal will it connect to the closer one. This means that if you move through the building, you'll get a poor signal even though you're really close to the other WiFi router. What a WLC does is control which AP your device connects to. If it detects that you're only getting 25% signal strength and you're within range of one with 75% signal strength, it'll send a message to your device to migrate to the one with the stronger signal. With a WLC, this transition is seamless, as it doesn't need to do any authentication (Check password). With normal range extenders or multiple wireless routers, you'll notice the WiFi go out for a few seconds as it needs to authenticate with the other network.",
"Multiple access points (basically signal repeaters) are used and named the same. So whichever one is closest or has the strongest RSSI to your device is connected. I have the same setup in my house using a Netgear 3700 extender."
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caobuz | How is space debris tracked? | How can so many tiny pieces of debris going all over the place be tracked and managed? Do other satellites do the tracking, or is it a land based system? | Technology | explainlikeimfive | {
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"eta6gt4"
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"text": [
"The [US Space Surveillance Network]( URL_0 ) includes both ground-based sensors and satellites that do the tracking."
],
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caqtej | Why did underwear become a huge standard in society? How did the notion of wearing clothes under our clothes become a huge success? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"I seem to remember reading that it was down to having a layer in between clothes you would wear for multiple days and those you could wash/change on a regular basis so the outer clothes stayed fresher for longer.",
"As for the why - Having your genitals rubbing up against rough fabric tends to not feel so good. Having a soft barrier between it and your likely more rough (on account of being much sturdier) outer clothes helps prevent this, as well as it helps to wick moisture away from the region which not only makes for a more comfortable experience, but further reduces chafing. Plus if you lived in the days before washing machines or even extremely easy access to water, generally speaking if you can have all the stray fecal matter, pee, and sweat collected into a comparatively simple and cheap bit of cloth as opposed to much more expensive and important outerwear, you're going to keep said outerwear much less stanky and more hygenic for a longer period of time if you're collecting a lot of that in the underwear."
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casjq6 | What does your phone do with all of the excess energy it gets after charging to 100%? | Technology | explainlikeimfive | {
"a_id": [
"etasiq3"
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"text": [
"Modern phones don't overcharge, by design. Its not safe to do so and could cause damage to the battery or other safety issues. Generally when they reach 100% they stop charging and actually slowly discharge their power down to about 95%, then charge back up and repeat."
],
"score": [
21
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castyx | How can a tiny $399 Go Pro with small battery shoot in 4K 60fps where as the large and bulky $2000 prosumer camcorders that also eat up power bricks of energy from companies like Sony only do 4K 30fps? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"4k describes the number of pixels the camera is capturing but there are other factors like color depth that describe how many shades of color the camera is capturing. The Hero 7 can record a bitrate of up to 78 Mb/s. Prosumer cameras can record up to 400 Mb/s. So the GoPro is sacrificing color and quality of the image to get a higher frame rate. I'll also add that Prosumer cameras can do 4k at 60fps these days, at a higher bitrate than the GoPro."
],
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19
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cawgii | What is RGB? | I've seen this on photoshop and other applications. Never seemed to understand what they are meant for. | Technology | explainlikeimfive | {
"a_id": [
"etbkdt1"
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"text": [
"Basically every pixel on those devices is not whatever color you see. It’s some combination of red green and blue. For instance, when you see purple, you really see high amounts of red and blue with no green in each pixel. This is done to make every color we see in pictures on those devices."
],
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cawuij | how do self driving cars handle snow/icy/slick roads? | It seems like the best way to handle those situations is to “feel the road” and make your best judgement. Is there some software in place for this or will cars treat an icy road like a normal one? | Technology | explainlikeimfive | {
"a_id": [
"etbnsjl"
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"text": [
"Self driving cars have a large number of sensors, and can detect when the car is sliding. In the same way you \"feel the road\" the software detects the slightest slide or slip and reacts accordingly"
],
"score": [
3
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cazyfj | Besides WiFi how does internet connect or use the same servers on opposite sides of the world, Are there like thousands of kilometers of internet lines that run through the ocean connecting different continents? | Technology | explainlikeimfive | {
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"text": [
"Actually, yes, there are. Going back to the early days of the telephone/telegraph, undersea cables have been laid across the Atlantic and Pacific to carry data between continents. You can find more about them here: [ URL_0 ]( URL_0 )",
"Yes. Big cables across the ocean floors. In the beginning people used regular phone cable that stretched across the ocean floors but nowadays it lots of very big dedicated mostly fibre-optical cables.",
"Just a clarification, satellite internet is not WiFi. They use entirely different technologies. WiFi is the name for wireless communications with end user devices like laptops and phones. & #x200B; Most overseas communications is done with submarine cables. These cables are dropped by special ships on the most shallow parts of the ocean. They use fiber optics to communicate. They have thick armor to protect themselves from the elements (And Sharks, yes, Sharks have been found gnawing on submarine cables). There's over 500,000 miles of submarine cable, connecting all inhabited islands and continents together.",
"Fibre optics through the oceans, yes. Wifi is not used for anything serious, it's just a small, local \"radio stations\" in your house / train station, etc. that your laptop and phone can tap into conveniently. Copper cabling - thousands upon thousands of miles - for everything in between. Though some of those copper cables are now fibre optics. Yes, you can have a 5000km fibre optic cable going under the ocean, shine light pulses through it, and see those light pulses come out the other end. (ELI5'd explanation, but this is pretty much how it works - and you can buy runs of fibre from any IT retailer that can be kilometres long and can \\*literally\\* do this with a torch/laser pointer, etc. Because it's fibre, you can even bend it into complete circles and the light still comes out the other end just the same). Not just that - there are enough fibre optics going in all directions around the globe, through all kinds of oceans, countries, etc. that even if one breaks it's rarely a problem. The data just goes \"the long way round\", in essence, or over other nearby fibre cables. For reference, a very rough rule of thumb I use to explain to people: Your wifi is about 20 times slower than the copper cable the router plugs into (mostly because it's shared with \\*everyone\\* in radio range, and your neighbours radio interferes with your radio). Copper cable is about 20 times slower than the fibre optic that it eventually generally plugs into. So you use wifi in your house, you have a load of devices that connect to your router, your router \"converts\" the data onto the copper cable to talk to the telecoms company, and somewhere down the line (quite where depends on how modern the wiring is) lots of those copper cables are \"converted\" again onto one fibre cable. Somewhere deep in the telecoms company, that fibre cable is connected with thousands of others just like it (but obviously able to carry much more data) and plugged directly into telecoms companies in other countries, etc. The bit you missed out: Wifi does not include 3G/4G/5G, but it is very similar - it just uses a different radio signal (but still just a radio signal) to join your phone to the nearby telecoms mast. That mast almost certainly has a bunch of copper cables to receive the signal from the antenna. The data on those copper cables are put onto a fibre, which connects to the rest of the telecoms networks. 3G/4G/5G are just different \"wifi\" radios that works over much longer distances, but everything serious ultimately happens on fibres. However you look at it, there are thousands of fibres under every ocean, each fibre is carrying thousands of copper-cables-worth of data, each of which could feed thousands of \"wifi\"/4G connections."
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cb0wp3 | what made the modern Space Shuttle program so dangerous? | Technology | explainlikeimfive | {
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"The main reason the STS was scrapped wasn't actually risk, it was cost. The Space Shuttle was supposed to revolutionise the cost of space travel by being almost fully reusable, but in the end that didn't work out. The boosters splashed down, which meant due to salt water contact they needed to be so extensively refurbished it would've been effectively cheaper to just let them crash and use new ones for each mission. In addition, especially after the columbia disaster, the shuttle itself also went through extensive refurbishment, with every single one of it's more than 20.000 silica heat tiles being expected and potentially replaced. In the end, the STS shuttle was a financial Black hole, bringing none of the cost reduction it promised.",
"There was nothing inherently wrong with the space shuttle. It launched 135 times and suffered two disasters. The first was caused by launching in colder temperatures than the equipment was intended for, which caused a seal to break. The second was caused by damage to a wing during take-off. These were regrettable, but it wasn’t inherently worse than any other space vehicle. Criticism of NASA and the shuttle comes down mostly to cost. The idea behind the shuttle was that the re-usable launch vehicle would be able to cheaply and efficient taxi people to space and back. Those cost savings were never really realized. Certainly not to the extent promised. Also, the space shuttles were getting old. Given the cost of launching, the cost of maintaining or replacing old vehicles, and the competing priorities (such as trillion dollar wars) they decided that the gains were no longer worth the cost of operation. Many people criticizing the state of our space program are just complaining that we no longer have flashy missions to the moon and things like that. The US has scaled back its government space program and is now relying on foreign governments and private industry in an attempt to realize cost savings.",
"It was not cost-effective compared to other launch vehicles for tasks such as launching satellites and ferrying crews to the International Space Station. The time and money to recondition the ships for relaunches was much greater than anticipated, making the launch schedules (which were originally envisioned to be every two weeks) erratic. Due to its weight, it could only attain Low Earth Orbit, which made it useless for maintaining the most valuable satellites. It wasn't that the design of the shuttle was so bad, it was complacency at NASA about problems during launch. NASA was aware that the O-ring seals of the solid rocket boosters were being charred during launch. It took the combination of extreme cold on the day of the launch, making the O-rings brittle, combined with the charring that led to the burn-through that destroyed the Challenger. NASA was well aware that pieces of insulating foam were breaking off from the main fuel tank, but since they had not yet caused an accident, were not rectified. Eventually a foam strike damaged a heat shield tile, resulting in the destruction of the Columbia."
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cb3d3d | The new iPhones and other flagship phones have 2 cameras to create a bokeh effect. Why do they need 2 cameras while real cameras can do the same effect with only one? | Technology | explainlikeimfive | {
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"Because the bokeh created by an iPhone is fake, it takes two pictures and combine them by software. Cameras in phones are too small to reproduce depth like a DSLR, so they emulate this effect by using two focal points, one for the focused target and another for the background."
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cb78z3 | Why do some countries use second-level domain country codes (. URL_1 or . URL_0 ) and others do not? | Technology | explainlikeimfive | {
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"TLDR: The DNS is a total mess where none of the established rules really matter. Back in the days when DNS was brand new some nations decided that it would be a good idea to use second-level domains to have their own versions of .com, .net, and .org . URL_1 is supposed to mean a commercial business in the UK While other countries like Canada adopted second level domains to refer the provinces . URL_0 New Brunswick . Canada This implementation was up to the various nations, and since it was a new technology they just kinda ran with it. However in the real world people soon abandoned these standards because they weren't enforced. Web developers and companies used different top-level domains as marketing gimmicks instead of what they actually stood for. Canada for instance rarely uses the provincial domains anymore. While companies are using Domains belonging to the island chain of Tuvalu .tv and claiming it means television when it doesn't. While other companies bought up every of .org, .net, and .com domains that were even remotely close to their company name just to prevent other companies from using them. Knowing this kind of thing drives my OCD mad.",
"Real answer? Be because each country can decided to use and divide their top level domain code however they want. Originally, there were only 7 top level domain suffixes - .com, .edu, .org, .net, .gov, .mil, and .int After the forecasted success and exponential growth of the internet, the TLDs were expanded to include the ISO two letter country code for every country, and delegated ownership to those countries (or some appointed representative organization for that country). So, really, . URL_1 exists because that's what the UK wanted to use, and . URL_0 exists because that's how Canada wanted to use their TLD."
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cb8mdj | Battery capacities and charging capabilities | My Macbook Pro has a \~8500 mAh Battery Capacity and there's a portable charger I'm trying to buy, it has a 27000 mAh battery (130W). On paper it should be able to charge my Macbook 3 times, but the website says it'll do one full charge before depleting completely. How does this work? | Technology | explainlikeimfive | {
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"The macbook's battery is almost certainly a few cells in series to create a higher pack voltage, such as 11.1volts. 11.1V 8500mah is close to 27000mah at 3.7v, assuming nearly perfect conversion/charging efficiency (a really unrealistic assumption, but who cares)"
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cb8qm1 | How to doctors keep your heart beating during bypass surgery? | Technology | explainlikeimfive | {
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"text": [
"They don't, they use a machine to circulate your blood while your heart is being operated on."
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6
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cbb36e | Why can't advertisers just buy space on a website from the host, and effectively avoid ad-blocker that way? | What I mean is if an advertiser says to a guy that owns a website, to put a literal image of an ad on their site, with maybe a hyperlink on it. That wouldn't trigger the adblocker, would it? Since it's a part of the website, an image on the site? | Technology | explainlikeimfive | {
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"For large websites, to display all of the advertisers that request this would require constant updating. Also, when advertisers use Google’s ad service, they advertise on multiple websites. They would have to pay one website to display their ad instead of paying to display their ad on multiple, which will result in a larger outreach. Therefore, the loss from a very few amount of users is little compared to the difference between the amount of users seeing their ad if it is projected on many websites instead of just one.",
"Ad blockers do try to recognise those types of ads, too, but it is easier for sites to bypass that recognition. The main reason is that it is really hard to do. Finding and negotiating with advertisers is a full-time job, really a full time job for several people, and the person making the website wants to use their time producing content. So they let someone else manage the advertising. So if you are running a big enough web site, big enough for you to dedicate a whole department to selling your ad space, then you might do so. But if you are such a site, then the information about your viewers is more valuable to advertisers, and they will pay a premium for access to them, making it much more profitable to still contract with a large ad network."
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cbca6f | Why do certain songs sound louder than others even when they’re played at the same volume? | Technology | explainlikeimfive | {
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"One thing to blame is the [Loudness War]( URL_0 ), where producers mastered their albums to be louder on the radio than other songs.",
"There's an audio technique called levelling, where the overall average volume can be changed. Some CDs have different levels depending on the production values, and sometimes because the range of volumes in the music (loud vs. soft), more common in orchestral pieces. You'll see levelling used on radio and TV stations, they use it to keep the audio low so that they can blare commercial sound, used to be a common tactic.",
"They’re probably not actually at the same volume. If we record you whispering to me, and me yelling at you, and then play them both back at 100% volume, it doesn’t change the fact that we recorded you doing something quiet and me doing something loud - the playback volume may be the same, but the source volume is different.",
"[Perception of Loudness]( URL_0 ) The frequency of a sound impacts its perceived loudness. Source: audiologist",
"FYI some PC audio applications like snackamp can take your audio library and \"auto-level\" them for you, do you don't have to mess with the volume controls all the time.",
"* If one song has loud peaks every now and then, and another song has loud peaks all the time, the second song will seem louder even though the peaks of each song are the same level. * Producers use a technique called \"audio compression\" to do this. * Also TV and Radio stations use it too. They use it to make songs and commercials easier to hear in noisy environments.",
"There's a lot of answers on here about modern mixing/mastering, overuse of compression for publication, and all that stuff is accurate. But at the heart of the question, if you really do play two distinct songs (or sounds) at the same exact volume, you will hear certain frequencies clearer than others. This is described by what's called the Fletcher Munson curve, and is important for any audio engineer to understand: URL_0 Basically our ears are tuned to hear the frequencies around the human voice the clearest, and even if there are lower/higher frequency sounds at the same volume, you'll hear the midrange vocal frequencies the clearest. This is used to certain ends in audio mixing, like electric guitar frequently has a big midrange spike so that it \"cuts through the mix\"",
"2 main things. 1, the amount of limiting/compression. Compression (and limiting, which is the same as compression, just more extreme) is essentially done by making the loud parts of music quiet, so you can make the quiet parts loud. That is, there is a defined peak loudness that a sound can have. If we take the loudest parts of the sound and smash them down, we can raise the overall loudness of the sound. Imagine recording a gunshot. The very first few milliseconds of the recorded sound are massive, but the rest of the sound (99% of the sound) is much smaller. If we take those first few milliseconds and squish them down, we can raise the entire sound wave. Next: Perceived loudness vs actual loudness. By limiting the peaks, we’re bringing up the rest of the signal. Even though we have a defined peak (in digital audio there are only so many bits in a sample), we can make it sound louder. If you look at a waveform of a song that hasn’t been limited, it has lots of peaks and troughs of varying magnitudes. If you look at the waveform of a mastered (heavily limited) song, it looks like a sausage. The songs are both the same loudness, but the squished one sounds louder. Hope this helps. Source: multiple Grammy nominated recording engineer."
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cbdsm9 | how do android apps collect data after we deny them permissions ? | ref: [More than 1,000 Android apps harvest data even after you deny permissions]( URL_0 ) [1] once we deny permission, how do the apps still have access to those data? [2] what does the "deny permission" setting actually do? [3] is it one of those "fake switch" things that do nothing internally ? [4] was google aware of this before the FTC mention? | Technology | explainlikeimfive | {
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"1. After skimming TFA, it seems that these apps work around not being allowed to access location data by doing things like reading the location tags in photos if they have access to those or using GeoIP-like databases to locate the phone's IP address when connecting via Wi-Fi. Others simply scan through files where other programs that *have* the relevant permission store the stuff they want to know if they are in a location the malicious program can access. 2. It does just what it says it does: When a program wants to e.g. read your location, it asks the operating system \"Hey, what's our current location?\". This will either result in an actual location or a \"nope, you're not allowed to know that\" (or a prompt to the user of which of those two to send). But that has no impact on using sneakier methods of obtaining said data. 3. Nope, they work perfectly fine. It's other security measures that are failing here (mainly read permissions per app). But those are far harder to implement consistently and without them being a pain in the ass for the user. 4. Probably not those specific issues.",
"Essentially, your data is inside a big guarded castle with a moat and portcullis and soldiers on the ramparts, but a sneak-thief has found an unguarded way in through the sewers. On Android, there is an \"official\" way to request data, and that is strongly locked down. If you say DENY, then the app *doesn't* get the data. For example, `Contacts.lookupContact()` will always return \"permission denied\" to an app unless it lists `READ_CONTACTS` in its manifest, and calls `ActivityCompat.requestPermissions()` and the user says ALLOW. Apps *cannot* get around this mechanism... so they have resorted to sneaky actions. They've found data they *can* get, in ways Google did not expect could be abused. * If you grant access to one app, e.g. to read your phone state, it will save that private data onto the SD card so other apps can read it * If you grant access to your photos, but not your location, the app will scan through all your photos to see if any of them have a location saved in them * They found a low-level API call in the Linux kernel that is not locked down by the Android permission system, and can give them your device's MAC address (ioctl(SIOCGIFHWADDR)) * They found the Linux file `/proc/net/arp` is not locked down, so they can read MAC addresses from that The researchers disclosed this to Google before the FTC presentation, and Google have responded by [fixing everything in the next Android release]( URL_1 ), but either can't or won't fix it in older versions of Android, because plugging these leaks would also stop thousands of non-privacy-invading apps from working. The linked article didn't like to the actual research, which is here: URL_0"
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cbf5d2 | If I disconnect my desktop from the internet and power source for a couple of weeks, reconnect the power and start it up, how does it keep the correct time and date? | Technology | explainlikeimfive | {
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"text": [
"The motherboard has an onboard battery (usually something like a CR2032 button battery) that it uses to keep a small bit of storage running. That storage contains your BIOS settings (boot order preference, BIOS password, etc) and a system clock. The system clock has a tiny circuit attached that allows it to store the system time, and have it progress normally, even if the system loses power. It won't actually be the correct time and date, though. The onboard oscillator will be imperfect and will deviate from the actual time. The deviation will be too small for you to notice, but it'll be enough that the computer wants to update it ASAP. So once you reconnect to the internet, it'll connect to a time server and download the correct time, and set that system clock to that time."
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cbk6h8 | What is Redstone in minecraft and who are it's "engineers"? | Technology | explainlikeimfive | {
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"text": [
"Redstone is a system in Minecraft based around a fictional substance called \"Redstone Dust\" that can communicate pseudo-electrical signals between various blocks and components. The system has enough components in it to make functional logic and memory circuits, meaning that it is entirely possible to make entire computers within Minecraft. Because Redstone signals can interact with various blocks in various ways, a clever minecraft player can build contraptions that do all sorts of tasks, from sorting items to making secret entrances to even making functional 3D printers within the game. While Redstone itself does not truly act like electical signals, many of the principles of electrical and computer engineering do apply. Thus, Redstone Engineers are those players that have studied and experimented with the game's mechanics to make increasingly complex machines.",
"Redstone in minecraft is a type of ore you can find in the game when digging around. When touched the more emits a faint glow, and produces a few units if redstone dust when mined. This dust can be used for many interesting builds such as: making red stone torch (form of a source of power or very dim light), wiring (when placed on the ground), pistons and other rails and such. Redstone works as in game electrical system, and e engineers are people who make neat contraptions in the game. The most basic would be a lever attached to some redstone dust which leads into a metal door. Therefore the door opens when the lever is flipped. More complicated systems such as logic gates and memory systems can be made if you have the time and patience."
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cbl92e | ; How does Instagram know the difference between male and female nipples when detecting nudity? | Technology | explainlikeimfive | {
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"text": [
"Image recognition and machine learning built off of user reports. So digital images are just really long strings of numbers and code derived from an algorithm right? If you didn't have the algorithm to decode the jumbled mess of letters into a picture on a screen, you'd look like [this guy]( URL_0 ). But, if you spend all day looking at those numbers, and I feed you 1000 pictures of what are definitely trees, you'll know what they look like numerically. Something like a a bunch of green in a triangle formula with some brown in a rectangle formula. Then I can start feeding you an unknown. You'll look at it and say \"80% sure this is a tree, 20% it's a [black guy with a birthday cap]( URL_1 )\", because there's definitely a triangle and a mass of brown. That's basically what machine learning algorithms are doing. They can process the images as computer code, and have been fed a ton of known male nipples and known female nipples. Either Instagram paid someone to find nipples or just uses the user reports to spot them to avoid privacy and copyright issues. So the computer has been trained to spot nipples, guess at male vs female, then reject those that meet a \"certainty threshold\". So, if you upload a sweet picture of your man tits, if the algorithm sees them as 60% female, they'll probably get rejected. If your sister uploads her flat raisins without any girly stuff, there's a decent chance that she'll be flagged as 70% male and have some n00ds up until someone reports her.",
"Just a wild guess but it’s probably some form of machine learning that over time has learned the difference with trial and error.",
"Other people have answered so instead of repeating that I thought you'd get a kick out of this. There's an Instagram account called genderless nipples that exists solely to prove that banning only girls' nipples is stupid. They post user submitted closeup pics of nipples and keep track of how many male and female nipples get taken down."
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cblpir | Can a smart watch charge from everyday movement? | We are moving around all the time, so doesn't that have energy associated with it? Can't the watch somehow use that energy to charge the battery? Then, you wouldn't have to plug it in to charge, it would just always be getting energy from your movements. | Technology | explainlikeimfive | {
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"text": [
"For \"dumb\" watches we have had automatic movements which wind themselves with a free spinning pendulum inside the watch. The problem with converting that into smart watch tech is efficiency. There are a few companies trying to solve this right now. Sequent is one of them. Check out their kickstarter. URL_0"
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cbpalo | How do refrigerated/freezer trucks keep their batteries from dying quickly? | Also, how long do they last and do they keep cooling even when not hauling anything? | Technology | explainlikeimfive | {
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"text": [
"The trailer has a separate fuel source for the trailer. Basically, fuel feeds generator, generator runs ac."
],
"score": [
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cbquzf | Why in old films of NASA and USSR rocket launches do the NASA engines emit yellow flames and USSR 's are blue? | > I've been watching "Chasing The Moon" on PBS and in the historical films of NASA launches the US vehicle engines pour out a very yellow, smokey and less structured flame than films of Soviet rockets where there's very little smoke and the flames look almost like what you would see on a gas stove. Blue and a very tight flame. Is it the fuel? Basic design? Maybe the color rendition of film itself? | Technology | explainlikeimfive | {
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"text": [
"It could be the fuel as almost all US rockets use liquid oxygen + kerosene which results in yellow glowing exhaust due to all the carbon left in it. Though the most used Russian launch vehicles were/are from the R-7 family that use the same fuel and generally their exhaust looks the same, Russian Proton rockets use nitrogen tetroxide + hydrazine which does burn in a more clear flame."
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19
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cbsi2b | how can phones be waterproof when they have so many holes (charging port, headphone jack, etc)? | Technology | explainlikeimfive | {
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"text": [
"Any holes, like the charging port and headphone port are sealed so water cannot get into the body of the phone. The seals are fairly thin which is why they are only good to about 5 meters, to much pressure will allow water to seep through.",
"Those aren't holes; they just have contact areas which allow electric signals to travel in and out of the system. Not holes."
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cbumby | Why high level languages implement purticular flow control mechanisms? | Only recently I discovered Ben Eater's video on how to make a computer Turing complete. I was thinking about such things a lot myself lately. After I argued to myself that conditional jumps are necessary for Turing completeness, I started to think about why higher level languages decided to implement specific flow control mechanisms s.a. branching and for/while loops in particular? Well, if-else statements are pretty much self explanatory, but is there any other motivation behind for/while/do-while loops other than just these were the most common use cases programmers were using conditional jumps for? Can anyone answer that precisely, please? | Technology | explainlikeimfive | {
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"text": [
"If you want to perform the same set of actions lots and lots of times, you're going to want a conditional loop to do it, rather than retyping out the same block of code a thousand times."
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cbwfsu | How do one use game codes work and would I be able to randomly enter numbers until one works? | Technology | explainlikeimfive | {
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"> **would I be able to randomly enter numbers until one works?** & #x200B; ~~No.~~ Incredibly unlikely. In fact *extra* unlikely because of the following: & #x200B; * These kinds of codes use something called a **checksum**. * A checksum is a set of rules that impact some of the characters in the code. * Every code that a user enters is processed using these rules to determine if it's valid. * A simplified example might be the following: * Each code is 10 characters long * The third character is alway \"3\" * The 9th and 10 characters are always odd numbers. * The sum of the 3rd and 7th characters is always 4 * This wouldn't be a real set of rules but it illustrates that concept and so you can see that entering random numbers is not practical.",
"On an online game you would probably be blocked after you entered a certain number of ones that didn't work. The number of available codes is huge."
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cbyw1w | How do hybrid cars work? (Simple version please!) | Technology | explainlikeimfive | {
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"Hybrid vehicles are electric vehicles which use a gasoline motor to charge the battery. Why do they do this? Gas engines are designed to work well and most efficiently within a certain RPM range. In a typical gas car, this means that in order to keep the gas engine working in its \"optimal range\" as the car moves through various speeds, you need a transmission - gears that convert the engine's speed into the car's speed. Transmissions are complex, heavy, prone to wear and failure... so if we can do without one we're better off. Electric motors have (to simplify things) the benefit that they work most efficiently across a wider range of speeds. So we don't need a transmission. But batteries (currently anyway) don't have the same energy density as gasoline. You'd have to recharge an electric vehicle more frequently than refil the same size / performance gas vehicle. And batteries are _heavy_. so lets combine the strengths of both. We get simplicity of an electric vehicle, but we can reduce the size of the battery by adding a small gasoline motor that is only there to charge the battery. Oh, and to help the brakes we can recoup some of our electricity as we brake."
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cbzp90 | Why does radiation distort film? | Watching NOVA: Building Chernoblys Megatomb and they show old footage from inside. In the footage you see all these white flashes spark across the screen like an old video camera from well the....80's lol is the distortion caused by the radiation or the technology of the time? | Technology | explainlikeimfive | {
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"Ionizing radiation can expose photographic film. It was even used for personal radiation dose monitoring. People wore opaque badges with bits of film inside. After a period of time the film would be developed and the exposure calculated. Photographic film uses silver halide which is converted to metallic silver when exposed to light or ionizing radiation. The change is developed and the image fixed by chemical processing. I can't say whether the footage you speak of is genuine, but it wouldn't surprise me if it was. Modern video cameras are also susceptible to damage from cosmic rays. One sensor in the Hubble Space Telescope has 2.7% bad pixels. [PDF]( URL_0 )",
"Radiation damages film in the same way it can damage your body. Ionizing radiation - such as that released during the Chernobyl incident - is made up of particles, x-rays, or gamma rays that have so much energy that they damage whatever they come in contact with. This radiation can damage DNA, circuits, and film."
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cc1dzo | Why do you get better performance when playing a PC game in Windowed (Borderless) than you do in Fullscreen? | Technology | explainlikeimfive | {
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"The only thing I can think of which would cause full screen to work worse than windows mode (borderless or otherwise) is because of: * outdated drivers * resolution outside optimal settings (such as resolution set too high or too low) * v-sync and other anti aliasing settings too high or game graphic settings set to too demanding * a program/app/window in the background is trying to gain focus while your game is running (such as an app set to \"always on top\" or some sort of overlay like steam, origin, uplay, twitch. * you have a 2nd monitor and the frame rate/resolution do not match your primary monitor resolution * you have a 2nd monitor and you have a video playing. Edit I though I was in a tech support subreddit for some reason. Here is the ELI5: Video game use a combination of either the CPU (the brain of your computer) and/or your graphics card to render ( or draw) what you see on your screen in the form of a single picture, called a frame. Your computer will process multiple frames per second to show you a smooth picture that has movement. The more frames you have the smoother the image. When you have multiple requests to your video card or CPU to render (or draw) images to your screen, you are using up resources that your computer has. Generally the beefier your computer is the more resources you have. Such as more ram, better processing speeds etc. When you run in full screen you are telling your pc not to draw the desktop and icons and instead draw the game you are playing. This mode gives your computer more resources it can use to give you more frames per second or better quality. However the higher the details/graphic settings for your game, the more your computer has to work to finish the rendering. If it gets to the point where it's taking too long to render the game at high settings the more lag you experience in the form of low frame count or frame drops. There are some games that benefit from high frames such as first person shooters and other multiplayer games. Generally you want to have lower graphic settings for these games so that you can have higher frames per second and thus see movement much faster and cleaerer. On the other hand if you have a single player game that dosent require fast reactions, a higher graphic setting will give you a more vibrant and detailed environment at a lower fps ( frames per second ).",
"What exactly are you referring to as performance? Just FPS? Typically that is not the case. Fullscreen is known for being better performance since it allows your computer to rest and not strain itself with the explorer.exe process. Hence why alt tabbing usually sucks when playing full screen. It could be possible you are experiencing a similar issue to something that occured for me and that was, my computer found it so easy to run the game that it stopped trying. My CPU was running at like 10% load even at low settings and the second I turned my graphics to ultra, my fps went up by about 70 because the computer realized it needed processing power to keep up.",
"You shouldn't. Going fullscreen removes overhead processes from memory - atleast temporarily. It leaves more processing power for making the game run smoother. If you are not, and you are using one display, you have a serious issue with resource management with your system. Try dualbooting into linux and playing some linux-friendly games and seeing what happens. If results are the same, ship your card straight back."
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cc1fqz | What’s the difference between different sound file extensions like .mp3 vs. .wav? Is there any cost to converting from one to another? | Technology | explainlikeimfive | {
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"In some cases, the extensions indicate the container types and not necessarily what is in them. Most times, like in the example case, the extension indicates the types of CODEC (file compression) was used to reduce the audio. The [MP3 uses MPEG1 (or 2) Audio Level 3]( URL_1 ) but the [WAV is a container type that could house different audio types]( URL_0 ). A good playback app will just read the header to determine what's inside. Theoretically, you could have MP3 compressed audio in a WAV file. That said, converting from one CODEC to the other is bad, m'kay. This is because during the compression phase, a good portion of the original data was thrown away, never to return. And each time you run a compressed audio file through a CODEC--even the same CODEC--you will lose additional data and the quality will be degraded [even more].",
"The main difference is the type of compression. Wavs are typically uncompressed, so they have much larger filesizes than MP3s of the same length. MP3s use lossy compression. That means the file size is much smaller, but it loses a bit of quality. However much of the data that's thrown away is supposedly imperctible to humans anyway, so MP3s are fine for the casual listener. There are other formats like FLAC which use lossless compression. That means the file size is smaller than an uncompressed wav, but no data is thrown away, it's just represented in a more compact form. So there is a cost from converting to a lossy format, or from one lossy format to another. Every time you do the conversion you lose some quality, so after a few conversions it will sound pretty bad."
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cc377e | How are we able to get such crisp pictures of astronomical objects, when the earth is constantly moving and destabilizing the image? | Technology | explainlikeimfive | {
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"I mean while we're constantly moving (and at a pretty snappy pace), the objects we're photographing are so far away that relative to us they seem relatively static over short time periods - just like when you're in the car driving and the Moon seems to stay in the same place in the sky no matter how fast the car goes. Plus a lot of the more incredible images are space telescopes, and so the actual rotation of the Earth isn't a factor, just it's orbit.",
"The moon is moving at about 3600km/h speed, or between 3 and 4 times the speed of sound. But it's far enough that it seems like it's standing still on the night sky. The Sun is moving at 30km/s, or about 120,000km/h, or 120 times the speed of sound, relative to us. The Sun is even further away, and it too seems almost completely still relative to us. (for both objects, their \"movement\" is mostly apparent motion, caused by Earth rotating. Sun seems to travel across the sky in one day, but that's just Earth rotating. How long it actually takes for Sun to do this trip across the sky, discounting Earth rotating, is one year. But anyway, it should still suffice to note that due to the distance, this insane speed of 120 mach is just not really visible) Basically, the further an object is, less it seems to move when it does move. Think of trees when in a car. Close trees seem to pass you very quickly, far away trees and objects seem to travel slower. And astronomical objects generally are soooo far away, it's hard to tell if they even move at all without extremely fine measuring devices, despite insane speeds objects have. Basically, from Earths perspective, basically everything seems primarily dominated by Earths rotationg where everything is, on short timescales. Discounting that, on few days to couple of years timescales, objects in our solar system can be seen to move. But it actually poses a problem to astronomy that objects in our galaxy move so very little in the few centuries that we've had telescopes it's hard to spot the movement of objects. And objects outside our galaxy? Well, they are so perfectly frozen that even the most fine measurements we can make with our best equipment are quite unreliable in many ways. Funny enough, we can measure pretty well if galaxies move towards us or away from us, but the sideways motion is afaik borderline impossible to detect. And this despite the fact that say, andromeda galaxy is moving towards us at whopping 500x faster than the speed of sound. We don't afaik know how fast it's moving sideways relative to us. It's probably some mind-bogglingly large number, but the age of astronomy has been too short to notice."
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cc4rt6 | Inspired by recent meme on r/steam, How does verifying the cache of a steam game (TF2, CS:GO, etc) solve so many problems that could be lengthy fixes? | Technology | explainlikeimfive | {
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"To explore what cache verification does, it's important to be passingly familiar with a particular concept in computer science: that of the *checksum.* A file's checksum, briefly, is a small piece of data that a computer can create by looking at the ones and zeroes that make it up. A checksum, then, is sort of like a fingerprint. Each file (theoretically) has an individual, unique checksum, and altering a file even slightly produces a different value. Why is this important? Well, what cache verification does is instruct Steam to take checksums of every file in your game directory and compare them to the checksums in Steam's servers. If there are any differences, that means that a file you have doesn't match what Steam says you should have, and so your client will replace it with a known good copy from Steam's servers."
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cc6e8b | How do places like Churches or MacDonald's avoid losing internet over illegal download copyright strikes from ISP's due to random folks who use their net? | Technology | explainlikeimfive | {
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"I had no idea that churches had wifi. & #x200B; But any big company will have a specific type of networking that disallows connection until a browser is opened to a specific webpage(usually it will open if you are connected and haven't been there yet) that is a ToS saying \"We are not responsible for dumb shit and will comply with any legal investigation\" before it allows you to connect. & #x200B; Smaller open wifi networks are not protected by this, even with a password protection. There is a possibility they may be held accountable for illegal activity. However, there are general laws, which protect sites like Reddit too, that say that the provider is generally not liable for what it's users do.",
"Think more about schools. I work school IT. A thousand kids all accessing everything all over the place. Maybe filtered, but filters are far from perfect. Maybe logged but trawling through logs is hard work and more often than not ends up with \"oh, it can from this chromebook alright, but the kid says he lost it days ago when someone took it from his locker\"... so even identifying the device and user doesn't tell you who actually did the bad thing they're alleging. Generally, they don't even bother to try to shut us down - it's the people running \\*services\\* they are after, and you wouldn't be able to run a massive download service from our connection. The individual torrent, etc. users? Small fry and they don't care. I haven't had even a notification of such in over 15 years. I know it goes on, it flags on certain reports, and it's more often than not staff and guests with things running constantly in the background on their laptops (e.g. uTorrent). When you do get one - and I have had a couple in my working life - you literally just write back and say \"We're a school, we operate public wifi, hundreds of devices and don't keep logs going back that far that we could reasonably analyse. Additionally, even if we identified the device or account in question, there's no way we can identify the actual person who sent the packets in question\". That's the last you'll hear of it. If anything, the smokescreen of being a public wifi point means that you're more protected than if, say, you were doing it from your home account where only a few people live or could ever possibly have connected to it. But even at home, you just write back and say \"Sorry, we don't keep logs, I have no idea who did that and no way to tell. I'll have a word with the family about this.\" EU law, especially, has pretty much established that even if it happened on your \"connection\", that's not identifying enough to prosecute, fine or pursue a single individual. An IP address isn't a person. You can't sue an IP address. You can't even sue the bill payer of an IP address at a certain time, they might be completely innocent (and a terms-and-conditions breach is civil so you can't really do much about it). Sure, if it happens enough, the ISP might well put extra monitoring on your connection, send you some warning letters and terminate the contract - that's about all they can do. And they really don't want to do that, so the evidence needs to be pretty hefty for them to even bother. Mainly because you'll just say \"Okay, I'll just use another ISP\". It's not like you have to take out a \"pirate credit check\" when you sign up to another ISP. Generally speaking, in schools and other places offering public wifi, things classed as \"civil\" infringements (copyright, private prosecutions, someone random \"suing you\" etc.) just fall by the wayside and nothing really happens (I might find the user that I suspect did it and give them a slap on the wrist, but that's about it). It's only \"criminal\" infringement (i.e. the police want to track an terrorist message, determine who hacked a website, etc. etc.) that actually gets any action whatsoever. Generally criminal infringements either demand the information from the ISP and then demand it from you (so the ISP really has no dealings with you in it, they are just required to comply), or they deal with the IT team direct in order to preserve evidence. Neither of those is likely to lose you your connection, unless the whole company is literally knowingly party to the same crime. There's a reason that you've probably never been to a cafe or a public airport and had all your website accesses replaced with a \"This connection has been terminated because of repeated copyright infringement\" notices. It just doesn't happen."
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cc6w7e | why do unused tabs drain CPU power | Technology | explainlikeimfive | {
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"They may be unused, but they’re probably running a bunch of JavaScript crap on the page. Things like banner ads rotations or animations. All those burn cpu cycles whether the page is the focus or not.",
"On a separate note, you can use Chrome flags (if you're using Chrome of course) to enable only the tab you're working on and put the rest on sleep mode until you go back to them."
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ccao1o | why a submarine drone hasn't uncover all of Mariana Trench | YT suggested clips on Mariana Trench so after a few vids I noticed it's all speculation. Yes it's 36k feet deep and the pressure would crush a person. So why no submarine drone? Or stay at a reasonable depth and shine a spotlight down?? | Technology | explainlikeimfive | {
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"The Mariana Trench is 2500 km long and about 70 km wide covering an area roughly the size of Florida. Light doesn't travel well underwater, it only makes it about 200 meters so you can't even survey much of the trench at a time. If you've got a zippy drone that does 55 kph and can see 200 meters to each side of it, then it'll take you 331 days to cover the whole area. Realistically you can probably only see 100 meters to each side and do 20 kph so you're looking at 5 years of piddling around the ocean for no financial benefit",
"[30 feet of water = 1 atmosphere]( URL_1 ). 36k feet of water = 1000 atmospheres. 15,000 lbs of pressure per square inch. One sq. inch of surface, 15,000 lbs on it. Weight of an elephant, per sq. inch. Even a small sub would have to the tune of 100 sq. inches of surface, 100 elephants crushing it from all directions. Steel can deal with the pressure, but you need glass or transparent plastics to see out or have cameras take shots, so it's not an easy thing. It's expensive, and marine research does function on funding, and perhaps doesn't get enough. Water also [absorbs light]( URL_0 ). 600 feet, the light from a source as bright as the overhead sun, it's absorbed, pitch black. The sub would need powerful lights, and would need to stay close to the bottom anyway, you save maybe 1k out of the 36k of depth and pressure."
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ccdhp8 | Why is a PIN more secure than a password in Windows 10? and why is considered a passwordless method? | Microsoft is promoting its "Windows Hello" login system as a passwordless login system, aside from the biometrics methods, there is also a PIN method which according to Microsoft website is more secure because: PIN is local to the device PIN can be complex (not only numbers) Is not all this what a password has always been in Windows? | Technology | explainlikeimfive | {
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"PIN is tied to the device One important difference between a password and a Hello PIN is that the PIN is tied to the specific device on which it was set up. That PIN is useless to anyone without that specific hardware. Someone who steals your password can sign in to your account from anywhere, but if they steal your PIN, they'd have to steal your physical device too! Even you can't use that PIN anywhere except on that specific device. If you want to sign in on multiple devices, you have to set up Hello on each device."
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ccfekg | Why do Bluetooth and Wifi use the same frequencies? | My girlfriend recently got a pair of wireless earbuds and noticed that they functioned poorly if at all next to her router when compared to anywhere else in her house. I was curious if they ran on the same frequency and if it was caused by interference and apparently my suspicions were correct. From what I've gathered, Wifi ranges from 2.401ghz to 2.495ghz while Bluetooth runs between 2.402ghz to 2.480ghz (feel free to correct me if that's wrong). Why would the two share the same frequencies? While I'm at it I guess I'll throw in microwaves that run at 2.450ghz, right in the middle. I've personally experienced the interference there. Isn't the FCC supposed to prevent this from happening? I would imagine that there must be some rhyme or reason to it that I'm not seeing. | Technology | explainlikeimfive | {
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"Because the FCC is who allows you to transmit over the air, they allow manufacturers to make devices that transmit in certain bands depending on what the device does. WiFi and Bluetooth are relatively new technologies, before this the 2.4 GHz band was considered useless because it couldn't travel very far and was susceptible to interference, and it's what the microwave uses. The FCC opened this band up recently (the past ~20 years) and they opened up 5GHz for the 802.11ac standard 6 or 7 years ago. Companies pay thousands of dollars in licenses to operate radio stations, so you're not allowed to interfere with their transmissions, emergency equipment must rely on the fact that certain frequencies are clear from interference to work, the same for GPS and other aircraft and maritime navigation systems. So if you build an electronic device that transmits frequencies, it has to be in the range that the FCC allows."
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ccfthv | If Ethernet cable can transfer so much data, why not use this instead of HDMI and other cables for data. | In physics class I remember using Ethernet cables to connect two “gates” used to measure speed for objects. I also know that Line 6 guitars use an Ethernet cable to connect your guitar to your guitar processor. We also use an Ethernet cable to power our LAN phones at work. So why is the Ethernet cable not the master cable of electronics? | Technology | explainlikeimfive | {
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"> So why is the Ethernet cable not the master cable of electronics? You actually hit an idea that has been getting traction off and on for a decade or so. Basically, you CAN use Ethernet for all sorts of other purposes, including replacing an HDMI cable. Ethernet (twisted pair) could replace a whole bevy of different cables. Twisted pair wires work really well for a lot of stuff, they are cheap, and durable, and go long distances. It's a pretty good option. The problem... well, it just doesn't work as good for certain special things like a specialized cable like HDMI does for video. HDMI is purposely built to deliver very high bandwidth uncompressed video, to achieve the same with Ethernet, you'd need a pretty robust system, heavy shielding, and likely more than one connection (i.e. two Ethernet cables). Side note: HDMI actually can transport data as well (much like Ethernet), but there has been basically zero consumer implementation of this in devices. But could we replace a lot of \"generic\" cables with twisted pair (ethernet)? Yeah, we probably could, but there really hasn't been much interest to do so, and that the [RJ-45 jack]( URL_0 ) is fairly large, makes it quite impractical for smaller devices, especially ones that may need several ports.",
"It's not really so much data. Video is incredibly bandwidth intensive. The current HDMI specification allows 48 gigabits of bandwidth. Most consumer Ethernet hardware is Gigabit Ethernet with occasionally 10 Gigabit. Much less than HDMI. While there exist higher speed Ethernet standards (25/50 and 40/100), they're rare outside of datacenters, the former only uses fibre optic cable, and the latter is brand new and the hardware barely exists. 40/100 also requires the fancy new category 8 Ethernet cabling and can't operate on older category 5/6/7 cables.",
"There's one crucial reason that hasn't yet been addressed: the end user. Let's say that, as an experiment, a motherboard manufacturer decided to do this very thing, and replace all the ports with RJ-45 ports. The most obvious and glaring problem with this is how would you determine where to plug in any given cable just from looking at the I/O panel? It'd be an absolute nightmare. The physical shape of the jack and port tells us a lot about what the cable is supposed to connect to and what data it carries.",
"well, usb 3.2 with type c connectors seem to be becoming the \"master cable\" you speak of. I think that throughput is just better, and most importantly, it's really small.",
"* **Ethernet** is actually a system for transferring information. It happens to use Category 5 or 6 cable (known commonly as CAT5 or CAT6) * You can do lots of stuff with CAT5 cables that has nothing to do with ethernet like your physics class and your Line 6 guitar. * There already are products that use CAT5 and CAT6 to get things like audio and video signal from one place to another. * BUT! The reason we have HDMI is because the movie studios wanted a technology they could control. * In order to make an HDMI cable, or a device that has an HDMI connector, you need to pay a license fee and agree to a legal contract that says you won't design your device in a way that lets people make illegal copies of protected content. * Back when DVDs were the main way you could watch movies at home, they forced everyone to switch their DVD players and TVs to HDMI. * Laptops went along with it and now basically everything relating to consumer video is HDMI."
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cck2u8 | How do they get the footage for ocean documentaries? | I'm watching Blue Planet and I have so many questions. Do the filmmakers use manned vessels with cameras? If so, how do they get so close to where the animals and ocean life continue to act naturally? Do they use some kind of remote controlled camera? How about the Deep? How do they capture such high quality footage with no light? If they add light wouldn't that disrupt the ocean life and scare them away? | Technology | explainlikeimfive | {
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"There are many ways that it can be filmed. Some may be by drivers physically filming underwater. The do used manned submarines and underwater drones (basically remote controlled submarines). I spent time in the past looking up how they film in the very deep water onetime. The light can actually attract some of the fish and sealife.",
"There's an actual documentary of how the blue planet was made and how they shot everything. I remember that for the deep sea shooting they used a small submersible vessel and they went deep into the ocean. It was like an ocean car which was used to shoot the part in the dark. And here was light but it didn't scare the fish. And also they had high tech cameras!"
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cclv5d | Mobile phone game ads where you can play the advertised game in the ad. How does that work? | Technology | explainlikeimfive | {
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"text": [
"It's the same as if you were playing a flash game in the browser. When the ad comes in, it loads this \"flash\" game, it's a specifically designed ad that allows you to play for 30 seconds and then it turns off to a normal static ad usually",
"Sometimes the ad is an iframe and other times the browser loads the ad's code in a sanitized environment. These are more rare probably because they are more expensive and must be screened properly; to ensure they are not using some kind of exploit to do something malicious to the end user. Flash was a major proponent of interactive advertisements in the 06-11 era but, as you can imagine, security flaws were way too evident to be worth the risk."
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ccnous | Why does it take so long to manufacture contacts for a person who has a bad astigmatism? | Technology | explainlikeimfive | {
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"text": [
"They are made with your prescription strength but also with a weighted side so that gravity spins them to make them align to match the shape of your eye. Since there are so many variables they usually don't have your perfect set in stock and have to custom order them. That's why it takes so much longer."
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ccpt1e | Engines | Quite a few questions: 1a) How does gearing work? b) How can the fuel consumption not be higher at higher gears, as youre moving faster, therefore needing more fuel. 2) Turbos! What are they! 3) Electricity, how does the engine make power to charge stuff in the vehicle, is there a seperate generator?!?!?! 4) How come, at low rpm, the entire vehicle shakes? 5) Last one, how does clutches work? Sorry if this is stupid, but it's been bugging me for a while! *Edit: Thank you all so, so, so much for the amazing explainations! You actually made this difficult topic easy for me to understand, and i love y'all! Thank you so much! These things have been bugging me for so long, but the answers have always been in a difficult language.* *I wish I could give each and every one of you a platinum, thank you so much.* | Technology | explainlikeimfive | {
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"Not an expert on all your questions, but I’ll have a stab at it: The gearbox (speaking of a manual) is full of pairs of gears of different ratios. Like a bicycle, when you use a bigger gear on the driven side and a smaller gear on the non-driven side you get more power (your top speed is higher) but less torque (you accelerate slower). To understand how the shifting etc works you’d be best looking up a howstuffworks video. Fuel efficiency is a function of how hard the engine is working - as with the gears, when you’re traveling quickly you will usually be in a higher gear with the engine turning (relatively) slowly, and the power multiplying effect of the gearbox making it more efficient for a given engine speed. The other factor is that it’s very energy intensive to accelerate the car, but quite easy to maintain speed so cruising will use much less fuel. A turbo is a compressor that forces more air into the cylinders, which means more fuel can be injected, which means more energy is generated in the combustion stroke. There’s a generator (called an alternator) driven by one of the belts connected to the engine. The alternator produces power to charge the battery while the engine is on, which is why if you leave your lights on and have a flat battery it’s important to go for a decent length drive to give it a chance to recharge. Engines are designed to be ‘balanced’, which means the forces of an explosion in one cylinder are counteracted by the force in the opposite cylinder (ie the front left and back right cylinders fire at the same time). When the engine is running properly at its idle speed or better the engine seems to be running smoothly, but if the rpm drops too low or the combustion in each cylinder isn’t equal any more (which can happen for a number of reasons, like spark plugs failing, the fuel/air mix not being right, or compression leaks) then the engine will become unbalanced and rock the whole car. Clutches are several plates of high friction material that are forced together by springs to join the drive forces of the engine to the gearbox. When you push the clutch pedal the plates are forced apart which separates the drive forces from the gearbox and allows the car to stop while the engine is still running, or to change gears without destroying the gearbox. There’s a heap of videos out there that can help you visualize how these systems work - I really learned how to drive a manual well once I watched a few videos of how the clutch works and understood what happens at each step of changing gears"
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ccq03z | How do computer machines/smartphones keep track of time? | Technology | explainlikeimfive | {
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"Computers use an internal clock powered by battery/capacitor, and smartphones use data sent to them from satellites. This is why smartphones automatically change the time based on where you are on the planet as well as daylight savings time if you are in a region that observes it. Edit; correction, smartphones don’t connect directly to satellites, but use the time sent to the towers by said satellites."
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ccqgqd | How do cops easily pick out the person speeding on a busy road with only a radar gun? | Technology | explainlikeimfive | {
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"Well... Anyone can figure out who is speeding on a busy road, relative to the other vehicles around it moving at a normal rate (speed limit). The radar gun, let's them know the speed for the official report and ticket."
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cctmja | How do dehumidifiers work and how do they collect so much water in a seemingly dry room | Technology | explainlikeimfive | {
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"I'm gonna blow your mind here: Gases can dissolve liquids. Air dissolves a little bit of water into it, which is another way of looking at evaporation. This dissolved water cannot stay dissolved if the air gets cold enough, and when this happens the water forms droplets. This is how rain forms, as well. Now, in a dehumidifier, air is sucked in, cooled down, the water droplets are collected, and then the air is pushed back out. On the way out, the cold air warms up while inside of the machine, and ultimately the room actually gets slightly warmer.",
"Ever notice how a cold drink cup sweats? That is dehumidifying the air by having water condense on a cold surface. A dehumidifier works like an air conditioner, but instead of pumping heat outdoors, it cools air to collect water on the evaporator and then heats it up again by running it over the condenser. The evaporator drips water into a collection bucket. The evaporator gets cold because refrigerant liquid is allowed to expand and in doing so it absorbs heat. It then goes to a compressor and a condenser where it becomes liquid again and in doing so gives off heat.",
"It’s basically an air conditioner, it’s has a coil that gets cold via Freon. Moisture in the air passing over it freezes. It defrosts and wallah water"
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ccv1et | How does a car radio "hold onto" a weak signal for a long time, but if you change the channel and try to change it back, it can't pick up on it again? | This also works on an internet signal. | Technology | explainlikeimfive | {
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"If you are using the seek or scan function there is a minimum signal threshold for the radio to stop on a certain frequency. It is designed to not stop on scratchy radio stations. In other words, \"It's a feature!\" It only becomes an issue when your traveling takes you to an area where the signal is weak. It will always stay on a station once it is tuned in, no matter how weak it gets, but it won't tune back in due to the way it is designed. If you could type in a specific frequency, or if your radio allows you to advance from one frequency to the next (88.1, 88.3, 88.5, etc.) using the \"tune\" function, then you can avoid this problem."
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ccvsjg | How are files compressed? | I've recently rewatched silicon valley and this aspect of the show intrigued me. | Technology | explainlikeimfive | {
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"There are lots of different ways of compressing things, but one of the most common that works for a variety of file types is to find repetitive patterns and remove them. For example, imagine you had a book where the main character had a *really* long name that came up often. You could compress the text by replacing the full name with some shorthand token, then decompress it later by replacing the token with the full name. This works for images as well as text. PNG compression works by grouping pixels that are the same color together and representing them as blocks instead of individual pixels. So instead of storing \"pixel 1 is 255,255,255, pixel 2 is 255,255,255, pixel 3 is 255,255,255\" and so on it just says 'pixels 1-x are 255,255,255.\" Another method of compression that works on many small files is to condense them into a single large file. This works because not every byte has a separate address on your hard drive, so a small file sometimes takes up more space than its actual size. For example, on Macbooks memory addresses are 4kb, so a file that's only a few bytes still takes up 4kb on the hard drive. This is why when you inspect a folder with many files the reported size and \"size on disk\" are sometimes different. When you compress all those files into one large file then they don't need their own memory addresses, so tiny files don't take up extra space. Another way that works for images is to remove data that isn't necessary. For example, in a typical image each pixel is represented by 4 bytes with values for red, green, blue, and alpha. If the image has no transparent pixels then you can remove the alpha byte, reducing size by 25%. If all pixels are grey then you can remove two of the color bytes. If the image has a higher bit depth (meaning it uses more than one byte per color, allowing for more variety in colors) but isn't actually using any colors that require a higher bit depth then the bit depth can be reduced, reducing the size."
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cd1mat | When you turn down or up the volume on devices with either a wheel or button, what actually happens that allows it to sound quieter or louder? | Technology | explainlikeimfive | {
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"A volume knob or wheel is an example of a device called a *potentiometer*, which is a device that adjusts the voltage going down a wire by increasing or decreasing the electrical resistance. If the resistance increases (if you turn the volume knob down), then less voltage makes it to the speaker, the cone vibrates less intensely, and the sound is quieter. The opposite is true if you turn the volume up.",
"Depends. On purely analog devices audio is just an electric signal. When you adjust the gain you are controlling how much electricity you are letting through, like a water tap. On digital devices this is more complicated but, generally speaking, when you press the volume buttons you are also controlling how much electricity is being sent to the speakers although not directly. Some code is interpreting your actions on the volume buttons and then this either results in the digital audio signal having less amplitude, or controlling the analog amplifier, or both.",
"Sound travels through your electronic device as a very small electrical current. Think of this current as “flowing” like water. When the volume knob is all the way up, all of the water is allowed to pass through it, but as you turn the knob down, less and less water is allowed through. The amount of “water” coming through = volume.",
"Others have talked about potentiometers but OP asked about a \"wheel\" (which is not a knob) and a button. The \"wheel\" is known as an encoder. It's a device that has many different positions. The device tracks which position the wheel was at and which position it has moved to. So it knows which direction the user is turning the wheel. If they turn it clockwise, then the system will send a signal to the amplifier to increase the gain (volume). If the user is turning it counter-clockwise then it will send a signal to lower the gain. & #x200B; This is what allows the user to continuously turn the wheel in a given direction. A regular knob has a fixed range and will only turn up to a certain point. & #x200B; As for buttons, it's the same idea, there is a button for \"up\" and button for \"down\". The system decides to increase the gain or lower the gain simply by which button is pressed. This is why you can have a touch screen with a volume slider . It's all digital information.",
"Nowadays the wheel or buttons generate pulses that control a computer that controls the D/A converter that controls the volume of the signal. To get increased dynamics, there can be one D/A converter for the volume and one (much more high resolution) for the signal, multiplied to get the end result, but it's not a given. Also, the equalizer is completely digital, using digital (calculated) filters.",
"A system consists of some signal source (tape player, radio etc), usually a preamp, an amplifier and a speaker. The volume control sits between the preamp and the amplifier. The preamp produces a signal that is (generally) about 1 volt. The volume control has a long resistor, with a wiper that makes contact with the resistor at some point along its length. The preamp output is connected to one end of the resistor, and the other end is attached to the 0 volts point ('ground'). The wiper is connected to the input of the main amp, which produces a signal with the voltage and power needed to drive the speaker. When the volume is high, the wiper attaches to the resistor right beside the input. So the full 1volt signal appears at the input of the main amp. When the volume is fully down, it the wiper attaches to the resistor right down at the ground point - there's no voltage there, as it is at 0 volts, so the main amp sees no signal and you get nothing out. Anywhere between that, the wiper contacts the resistor somewhere along it's length, and so the main amp sees somewhere between the full 1v signal and nothing, controlling the volume."
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cd4rsq | How does video-game save data work? Particularly in modern, expansive and intricate games | Technology | explainlikeimfive | {
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"Typically, games are saved my finding the minimum possible data needed to save all of the information needed. This data is saved in binary as bits on a hard drive, and it can take billions of these bits to store a particularly large file such as PUBG's or ArmA's maps. Things like maps are often stored as heightmaps, which you can think of as top-down pictures where the color corresponds to height. Each pixel in the picture represents a part of the map, and the height of the ground at that point is saved as the \"color\" of the pixel. Now, things like rocks, trees, buildings, and players are saved as X,Y,Z coordinates in a separate file, and when the map is loaded this data is all compiled to form a map. Player, chest, and other character inventories and data are often also stored in the file where their coordinates are located, usually as lists. To compress this data as much as possible, items are assigned numbers. You can think of item Ids in Minecraft as an example. Instead of saving items by writing their whole name, it simply says \"1\" and then it knows that \"1\" is \"stone\"."
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cd4z41 | How do we know the internal temperature of our planet? | Technology | explainlikeimfive | {
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"We measured the melting point of iron at various pressures, and we know what depth the iron core transitions from solid to liquid. This allows us to know the temperature at this boundary, and we can extrapolate some from there."
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cd5kdp | If we use electron microscopes to see atomic nuclei but we can't see the electrons because they're smaller than the nuclei how do we use electrons in the microscope? | Technology | explainlikeimfive | {
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"An electron microscope is sending out a stream of electrons that then bounce back and are picked up as data and then converted to a visual image.",
"We can't actually *see* atomic nuclei. We can see bonded atoms because electrons are much smaller than atoms but we can't actually visualize the nuclei. In fact, that nice model we have of protons and neutrons as nice little spheres is almost certainly wrong. Now it is often shown as a 'cloud' with areas that are positive and neutral which are the neutrons and protons. We can detect nuclei, we can smash stuff together and reveal the nuclei (in a particle collider) but we don't actually get to *see* them."
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cd75jb | Why are some items recyclable while other seemingly identical items are not? | For example, I have a plastic milk jug that has a recyclable stamp on it, while I have a vinegar jug that does not. | Technology | explainlikeimfive | {
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"The simple answer is they are made of different types of plastic. Vinegar is acidic so it may use a different plastic in order to maintain the integrity of the bottle compared to milk which is way more neutral.",
"Just the fact is doesn't say it is recyclable doesn't mean it isn't. It could be that the bottle is recyclable, but the manufacture didn't communicate it. Look up the material the bottle is made from. Most food grade plastic is either PET or PE plastics, both of which are recycled in most Western countries. Also, basicly anything is recyclable. However, when the cost of labour is higher than just using raw materials, companies just do the latter."
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cd89tc | How do radio stations gauge how many listeners they have? How accurate is it? | Technology | explainlikeimfive | {
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"Radio stations in the US don't measure it themselves. A separate company called Nielsen does. You've probably heard of \"Nielsen ratings\" for TV? Well they do basically the same thing for radio. For radio, they do it two main ways, 1) They give people diaries, yes diaries, and they literally write down what they listened to. 2) (This is the primary way) Some people are given small devices (which look like an old school pager) called a \"people meter\" that you wear on you and it listens for the radio and logs what station it was. And well, then they take all of that data and estimate it out. Their methodology has always been a point of contention (especially in radio), but they are still considered the industry standard."
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cdfc2n | What technological advancements have occured for the 5G mobile network to be so much faster than it's predecessor? | Technology | explainlikeimfive | {
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"I used to be a patent lawyer for some of the companies doing this work (Ericsson, Qualcomm, etc.) so I feel pretty comfortable answering this. In my opinion, there haven’t been any truly groundbreaking technologies in this field that have allowed for 5G. Rather, 5G is a mix of a number of now relatively standard technologies that work in sync with one another. To understand why things are working out this way, you should realize that the number of devices that use wireless signals have increased exponentially, and that different types of devices work better in different configurations (i.e., different frequencies, different distances, different battery lengths, different amounts of data to transmit, etc.). While this all might seem relatively obvious, it is the big motivating factor for 5G. For example, if autonomous vehicles are going to work at a large scale, then there needs to be a network capable of handling their needs. These needs include large data transmission, high reliability, high speed, and high continuity. To meet these needs, an eNodeB (i.e., a radio tower) can transmit a high frequency signal to the vehicle because more information can be included in a higher frequency signal. However, high frequency signals tend to be disrupted by their surrounding environment more easily than lower frequency signals. For example, millimeter wave signals (i.e., high frequency signals) can be blocked by trees, human bodies, some buildings, etc. To counteract this type of path interference, you need to have more antennas over the same area. So instead of having an eNodeB every .5 km^2, you might place them every .1 km^2 (by the way, this is where the term \"cell\" in cell phone comes from, because each of these areas are considered a \"cell\"). While all of the above might cover the autonomous vehicle use case, we have also seen a major boost in internet of things (IoT) devices, like small sensors that are remotely located, not hooked up to a connected power source, and do not need to transmit a lot of data. For example, there are sensors that are attached to various portions of a bridge that transmit vibration signals, amongst others, back to a central server to monitor the structural integrity and wear on that bridge. Since these devices only need to transmit a small amount of information every so often, they can be set up to send very intermittent signals at a low data rate to conserve energy and battery power. Since they are usually remotely located, they also may be better set for low frequency signals, as those types of signals don't experience the same path interference that higher frequency signals usually do. Therefore, you might want to send lower frequency signals at a lower rate to these devices, but they might occur at a much larger volume because there are more IoT devices than there are self-driving cars. Your standard smart phone falls in the middle of these two use cases, but it is slowly creeping toward requiring more and more data with more and more reliability. So what does 5G do to accommodate all of these needs? Well, they do a bunch of things, almost none of which are super groundbreaking. One thing they do is use antenna arrays. Antenna arrays are devices that include a bunch of antennas, and different antennas in each array can be configured to emit a signal of a different frequency. The antennas in each array can also be configured to change the direction and/or intensity of its beam so that it can avoid potential interference along a path. 5G also uses something called MIMO (multi-in, multi-out) to increase bandwidth and/or reliability. This technology has been known for a while now (you see it in multi antenna wifi routers for example), but they are now applying it at a larger scale and across multiple users (referred to as MU-MIMO (multi-user MIMO). 5G technologies also include using machine learning technologies to understand user preferences so as to predict behavior of a user and needs of a device. Many 5G technologies also include energy harvesting (e.g., solar power) technologies so as to increase operation time for IoT devices, for example. These technologies also use various forms of coding, such as trellis modulation, turbo coding, and a number of other mathematical techniques to increase data transmission and/or reliability. In summary, 5G is really just adding a bunch of existing technologies together in a relatively new and complicated manner. If you get involved with this field, you find out pretty quickly that most of the researchers and engineers are throwing different combinations at the wall to see what sticks (i.e., what the 3GPP adopts to their standard). I really just grazed the surface here, so if you have any follow up questions I'd be happy to answer. **TL;DR:** There aren't many new technologies. 5G is just adding existing tech together in a complicated manner. **Edit**: I initially only posted the first paragraph, but I added the other four to provide some more detail.",
"The max amount of data that can be transferred in a second increases as the frequency of the waves being used increases. 5G uses a significantly higher frequency than 4G, so can be faster. The downside is that around the radio and infrared spectra, increasing frequency also decreases the ability to penetrate objects, so 5G needs more towers per unit area in order to get acceptable strength everywhere. & #x200B; If you've ever had a dual-band wifi router it has the same effect. The 2.4 GHz band will give you a lower peak speed in general (assuming your connection is fast enough) but will have a better signal away from the router and give wifi service at a greater maximum distance. 5 GHz will be faster but have less coverage and strength over distance."
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cdijp2 | How do my solar power calculators that I never expose to direct sunlight work for so long. | I use calculators in my study that gets almost no natural light, and I've never had any die on me. | Technology | explainlikeimfive | {
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"Artificial lights, such as florescent lights and incandescent bulbs, mimic the sun's spectrum. Therefore, the calculator doesn't know it is getting charged by artificial light and not natural.",
"Calculators require very little energy to work so very little light is needed to make them work and it doesn't have to be sunlight any light will do."
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cdj2tj | When videogames are in development for years on end and there's new generations of consoles, how the hell do they keep up with adjusting the quality and graphics? e.g : Kingdom Hearts 3, FF15, etc. Do those videogames just constantly rework their textures ? | Technology | explainlikeimfive | {
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"> do the devs just constantly rework or update the graphics of their game? No, they develop with the idea of what kind of graphics that will be possible in that time. When it comes to 3D models; they are made at the \"highest\" quality and then reworked to \"lower\" quality a game can support. You can do this yourself in Blender if you want. Also since majority of games are developed for consoles who have their hardware set for the next 6 to 7 years, the developers don't need to worry about not keeping pace with hardware. > How do they manage to not release something that's 10 years behind in technology (including AI and other features) Because either A: those features are already built into the engine, or B: they themselves develop those features. The game F. E.A.R - who's more than a decade old - still has better AI than most, if not all, shooters."
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cdjq5k | when shopping online at a store that has physical locations, why does it almost always not have the "closest store" correct? | I shop online at [ URL_1 ]( URL_0 ) to see if I can run in and grab something and not wait for shipping. When I click on "store availability" it almost always has a store within 150 miles of me but never my exact store. How can it know to be close but not close enough? If there are some cookies online wouldn't that allow it to be more precise than a 150 mile range? | Technology | explainlikeimfive | {
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"Because the website is looking at the address of your ISP, and the physical address for their hub is not normally in your backyard. It gets even worse when you are using mobile data, the last point in the chain of hubs between you and the store could be in another state."
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cdsa2s | What are the cores and threads on a processor and why does it seem like more = better? | I've been looking for a new processor to buy because my current one is pretty bad. I quickly found that apparently cores and threads are a thing. How do they work, why do they matter, and why would you want more or less of these in your CPU? | Technology | explainlikeimfive | {
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"In bare bare basic terms a core is like an office and a the threads workers. More cores more space for workers. Some processors are able to have 2 workers per office (hyperthreading Intel and multithreading amd). More workers more productivity. Although it is not always the case. And the new ryzen 3600 for 200 us is a super good deal for budget gaming or work machine. 6 cores 12 threads."
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cdv53j | What is Kernel? | Technology | explainlikeimfive | {
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"The kernel is a section of code within a computer's operating system that has the most amount of privilege and has direct access to the hardware. When a user has a program that needs to access the hardware, say to read from or write to a hard drive, the program must request permission to have access from the kernel. A system call is the process by which a program requests these accesses to the hardware, and the kernel grants or denies access based on permissions. In windows the kernel is made of two layers. The upper layer is called the executive and this contains functions for object management/retention, permission verification, memory management, etc. The lower layer is the actual kernel, which is responsible for low-level processor synchronization, interrupts and exceptions handling, thread scheduling, and recovery from power failure (power loss, hard shutdowns, etc). These layers work together to provide everything that a user may need to access the hardware and make changes to the system as they need to and are allowed to. Forgive me, but I don't have as much knowledge about Linux to this level, but the kernel performs basically the same in Linux (I'm a windows instructor). Instead of being built with layers, it instead has kernel loadable modules (KLMs) which can provide additional functionality to the kernel. Hope this helps.",
"The Kernel is the computer's Mom. It tells the computer who it can play with and who can see it.",
"I feel like this needs to be explained more in the context of operating systems and history. Originally computers took up rooms and could only run a single program at a time. There was a circuit by which a program was loaded using punchcards or what not and then the computer would run that program to completion or until someone halted it for some reason, maybe if the program took up too much time. A program is just a list of instructions the CPU knows how to read. Each instruction can do something from jump to another instruction if a condition is met or manipulate numbers stored in computer memory. The main thing an operating system allows us to do is run multiple programs at the same time. So how does it do this? Firstly each program exists ultimately to manipulate memory so the operating system has to give it memory to do so, but it must keep the memory of different programs separate since issues arise if they use the same memory. Additionally the programs need something to execute their instructions, so we have to give them some processing power to do their thing with, so the kernel additionally manages the CPU and gives each program some time with the CPU to do its thing (this part of the kernel is known as the scheduler). Normally the way this works is that the kernel code gives control of the CPU to the program being run but computers have an additional circuit known as the timer interrupt circuit which \"interrupts\" the CPU's current program execution after a time specified by the kernel and jumps to code specified to be run when a timer interrupt occurs (this is normally loaded during boot of course, and this code is of course kernel code). In this way the kernel can both grant control of the CPU to a program and then take it away as it pleases. Nowadays we also have files and devices and stuff, and we want to allow programs access to those but only the right ones. So we make it such that to read or write a file, the operating system has to give it permission to do so, so we have programs ask the operating system to read these files for it. All of these are basic kernel functions but there are also a lot more. Its essentially the core of an operating system, an OS needs to be able to handle multiple processes working with hardware given and its the job of the kernel to do this.",
"The kernel, also known as the \"null space\" of a function from set A to set B, is the set of all x in A that make the function value zero. In your early math courses, you've probably referred to A as the \"domain\" and B as the \"range\". A contains all of the values you can put into the function as inputs, and B contains all of the values you can get out of the function, given values from A. With the kernel, we're specifically looking for all the values in A where we can feed them to the function and get out zeros. For equations that describe a straight line (linear equations), this is just the x value where it hits the x-axis; you can find it easily on a graph, but you can also just solve for y = ax + b = 0 - > x = -b/a. This can be extended to systems of equations as well, and the solution in this case makes up one of the four fundamental subspaces of the system. This is a fun and interesting topic to explore, especially if you follow along with Gilbert Strang's lectures on the subject! For more complicated equations, the set may contain more than one element. For example, a parabola has two places where it crosses the x-axis (even if they're the same place!), while sines and cosines (and other trig functions) have an infinite number. You *were* talking about math and not corn, right?",
"It is the seed of a corn....... Oh wait, are we talking about computers?",
"In a computer context, a kernel is a low level program that interfaces the hardware with the software. The kernel's job is to allocate CPU time, RAM, etc to different programs, to take input from the keyboard and mouse and route it to programs that need it, and other things like that.",
"You walk into a restaurant and sit down. You order food, and a little while later the food comes out and you get to eat. You are not allowed in the kitchen, and you are not a chef and you don't know how to use all the stuff in the kitchen, or where things go, or how food is rotated in the fridge, or who's job back there it is to cook what. And guess what? The staff back there doesn't care what you do either or what you talk about, they only care about what you order, bringing you food, and cleaning up after you. & #x200B; You are a program running on the computer. & #x200B; The kernel is all the restaurant workers; waiters, bussers, chefs, supervisors, dish washers, line cooks, etc. & #x200B; The computer hardware is the stuff in the kitchen; the stoves, sinks, refrigerator, stuff in the fridge, food on the stove, etc. You are not allowed in the kitchen. If you need something from the kitchen, you ask the wait staff to get it for you. They are allowed into the kitchen. & #x200B; The \"Front of the house\", the tables, chairs, decor, menu, and even the wait staff and hostess, are what the Kernel allows you see. You don't see and can't get to the hardware in the kitchen - nor should you really care about it.",
"Question: Are you interested in the programming one, the mathematical one or the yummy one?",
"Imagine a nut, like a walnut. You have the shell, the part you can see and feel and interact with. If you crack it open, the kernel is the meaty part in the middle. The operating system kernel is the deep low level program that does stuff like get the computer started and keep different programs from messing each other up"
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ce1k22 | What actually is a game engine, and how do they differ from one another? (e.g. Unreal Engine vs Cryengine) | Technology | explainlikeimfive | {
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"Think of the game engine like a medium, or a canvas, a computer world where the laws of physics have been made, but it's completely, or very nearly, empty. Even though it's called an engine, it's all just computer programming. Once you have your engine, the game developer then comes in to create the world within that model, molding the landscape, adding objects and characters, painting it, as well as adding music, dialogue, and story, as well as the specific game rules. Different game engines may be written in different coding languages, or have different capabilities as far as what can be modeled in the game, and how fast the game can be (also dependent on your computer as well), as well as what kinds of games can be used by the engine, and what consoles the engine can be used in.",
"In programming things are built up in layers. Instead of coding everything in binary, we build languages. Instead of reinventing code, we create libraries of reusable code to use on new projects. A game engine follows the same idea. It's basically a big toolbox that full of tools for building a game. It's a little more complicated than that, for example, some tools depend on other in complex ways that make it so you can't necessarily just hack two engines together, but that's basically it. All these tools are generally jammed together into one big program that acts to not only hold all the tools, but also to compile or outright run the game, and often a code editor and GUI elements to help developers.",
"A game has \"assets\" - NPC's, scenery, vegetation, buildings, furniture, clutter, weapons, armor, vehicles, etc. All of these are stored in nice little files and make up about 90% of the game size, the gigabytes you have to download to install the game. The game engine is the core program that sets up all these assets so they look like a game rather than a collection of art assets. NPC's move and interact, trees sway in the wind, buildings allow entry and exit etc., weapons function, armor can be put on and taken off, etc. It's the job of the engine to make all of that work. The various engines differ in how they do that job (programming language) and how they're optimized. Some engines are optimized for small indoor areas, others for large open geography and huge armies, others for 3D movement like flying in space and landing on planets, etc. Sometimes a game will use one engine to let you fly in space, and another to let you walk around on a planet after you've landed."
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ce1o2l | How are emergency numbers (e.g. 911) handled near borders of countries? | What happens if the calls get to the other country? | Technology | explainlikeimfive | {
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"Well in the EU it's the same for all countries and they route 112 to the nearest emergency dispatch. While standing in one country and being connected to a different countries cell tower could cause issues they generally inform the correct emergency service and worst case a German ambulance will pick you up in Belgium.",
"I assume you're talking about cell phones in this case. The issue exists not just on country borders but locally as well and is handled the same way. When cell phone companies deploy new towers they have to submit paperwork to 911 centers with am address and coordinates for the tower as well as showing antennas and the direction and coverage angles. The 911 center then tells them the info they need to route 911 calls properly. However when it is on a border that form first goes to the 911 center where the tower is located and they make the determination based on the antenna direction and width of the signal which antennas they're going to accept coverage for, with some additional back and forth the neighboring 911 center will take responsibility for the other antenna/s. Often you have where an antenna covers both areas, in that case it is a judgement call based off of population and other factors such as roads as to which one they route the call to. It isn't set in stone and based on call volume they could change that down the road. In the event that a call does end up at the wrong 911 center once the dispatcher figures that out they can route the call to where it belongs.",
"Well here in Australia our emergency number is 000 (which was the worst by the way since when everyone had desk landline phones curious toddlers would stand on their tippy-toes trying to reach the phone on the desk and would always mash 000 since it was the only number they could reach) but if a US citizen is here and needs emergency services and just instinctively dials 911 it will redirect to 000. So tl;dr I think any emergency number will just redirect to the country you are in. I could be completely wrong as I'm just basing it on what happens in Australia."
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