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cwtl85 | What's the point of CC'ing someone in an email? | Technology | explainlikeimfive | {
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"I usually CC a person in an email if the email isn’t direct to them, but I want them to be aware of the communication."
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cwu6ah | What is so hard about desalinization? | Technology | explainlikeimfive | {
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"It takes a lot of energy, or it takes filters that don't get clogged; it produces a lot of waste at large scales, and sucking huge amounts of ocean water up to process it also tends to be hard on the environment."
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cwxjjq | What happens when you delete a file from your computers memory? What happens? Where does it go? Does it get destroyed or zapped into non-existence? | Technology | explainlikeimfive | {
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"You can think of your hard drive like a book. As you write information into the blank pages, your operating system updates the book's table of contents with the positions of the bits and pieces of the file. Computers don't like to do unnecessary work, so when you delete a file, all that happens (at the moment, that is) is that the entries in the table of contents are deleted. The file is still \"there\" on the disk, but your operating system forgets about it, and if it has to, it'll write over the pages.",
"Imagine your computer’s memory is like a bunch of boxes. When it saves something, it basically puts a not on one that says “don’t touch whatever’s in this box.” When you delete something it basically takes that note off but it doesn’t bother getting rid of whatever’s in there. If it ever needs a place to put something new, it might find that old box and think “well there’s no note on here so I guess I can throw all this old junk out” and do that. Otherwise, all that old content is still in there and can easily be found by someone who knows to look for it.",
"Nothing happens right away. It just gets marked that the computer can overwrite it if it ever feels like it. Once that happens, then it's gone. But simple file recovery programs can get back files you recently deleted from the recycling bin for this reason.",
"It is worth noting that there is a difference between \"memory\" and \"storage\". Generally when we refer to computer memory it is in short term, extremely fast chips that lose their contents when the machine is turned off. Storage which is what your question refers to is either mechanical discs or increasingly solid state devices that retain the information when the power is turned off."
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cx6pgq | Why do the batteries of (old) phones expand so crazy and destroy the phone? | Technology | explainlikeimfive | {
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"It's designed to do that. Over time, the chemicals inside the battery will degrade which creates a buildup of gas, expanding the battery. The phone splits apart to allow room for this expansion or else the battery would just explode. If you replace the battery with a fresh one and snap the phone back together, it'll be good as new."
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cx9a73 | How come my car's satellite radio doesn't work inside my garage, but my alarm's FM radio works there? | Technology | explainlikeimfive | {
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"Hopefully someone more knowledgeable will give a better answer than I can, but in short... Satellite radio uses a much higher frequency radio wave, between 2- and 4- gigahertz, compared to terrestrial radio, which uses between 87.5 and 108.0 megahertz. Higher frequencies have more trouble penetrating solid objects, so the terrestrial radio goes through buildings easily enough while the higher frequency satellite radio gets stopped."
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cxd3fa | How does the censor thing follow the thing that's being censored (e.g. number plates, faces) so smoothly on TV? | Technology | explainlikeimfive | {
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"Key framing. If the show isn’t live, it’s on the editing room. What a key frame is, it’s a marker you place for something, and you move the marker from one place to another, in a certain amount of frames. With TV shows, I would assume they have editors that would do this frame by frame, making sure whatever needs to be blurred gets blurred correctly.",
"If the show is live, the studio may employ a broadcast delay system which may introduce a 30-second delay in live broadcast so the producers and techs have time to censor audio and video."
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cxfmdp | How are video games, new and old, able to detect when someone is using a pirated copy? | Technology | explainlikeimfive | {
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"Having worked on copy protection (and been a cracker on the C64/Amiga)... When you enter your license key, files are written to disk in \"hidden\" places that record a signature of your computer. This is usually generated from the disk serial number, MAC address of an Ethernet card and so on. It's just a \"hash\" that identifies your machine (not you). To detect tampering of the software itself, program functions are added to the original application (or game) and when run, the hidden files are checked for. If they're not found, then the license is \"broken\" and you have to enter the serial number again. If they are there, they're read from disk to see if the computed number stored in the hidden files matches the same number computed there and then. If they don't match, the license is broken and you have to enter the serial number again. If the software connects to a license server, over the internet (like Quake 3 did), it will see if the license key is associated with the computed number. If it isn't, the program will not run - or will damaged itself so as not to run correctly. With a CD based piece of software, it is easy to detect if the CD is a master or a recorded CD. If it's a recorded CD, the software won't run. If it's a master CD, a particular feature on the disk (signature) is checked to see if it's valid. If it is, then the program runs. In this sense the CD is used as a validation device. Now, for a program that someone is trying to crack, there are a few tricks to detect cracked code and a few responses the dev might make. For example, on the Mac you can disable attachment of the \"gdb debugger\" (iTunes does this). So, normally you can't attach a debugger so, as a check, the dev can run a sub-process so often to see if the parent process can be attached to. If it can, then someone removed the anti-debug code. Also doing SHA-1 style signatures of shared libraries and loadable components helps to detect alteration. You can also runtime decrypt functions and re-encrypt on the way out to obscure the protection code. The meta data for protection is (or should be) encrypted in the program itself so a cracker can't just edit it. Some reactive behavior for the program might be, say, change physics in a game or make it crash after some interval. Edit: some old c64 info. The disk version of Skate or Die used self modifying code to obfuscate its copy protection. A set of loops that XOR’ed the code it’d immediately execute after the loop. A good pain in the butt for a cracker. Edit 2: I just remembered that on the old PowerPC Mac, there was a set of instructions that could make gdb actually crash. This code was used in the “encrypted function” decoding code as an extra deterrent if they’d got passed other traps."
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cxi9b0 | How is the data from my online activity converted into targeted marketing? | I was recently trying to explain to a friend why I use a VPN, but given my lack of knowledge of how technologies work I was not capable. I'm not necessarily interested in targeted marketing, I'd like to understand: the different ways that we give data out on the web knowingly/unknowingly; what is done to this data; the ethical implications; how much of what I see on the web is tailored specifically for me? | Technology | explainlikeimfive | {
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"There are essentially 3 ways to track your computer on the internet: 1. Your computer has an 'address' so that other computers can send things to it (including web pages that your computer has asked them to send). This address isn't always constant/unique though. 2. Your web browser has memory spaces called 'cookies' where websites can save information which they can find later (the information is saved on your computer, hence you can \"clear your cookies\" to delete it) 3. You, your browser and your computer all reveal little nuggets of information (manufacturer, model, software versions, language, even the size of your browser window) which combined together can often be very unique to you. If websites can track your computer then they can remember things about you, the main types of data they might remember are: 1. Your age, sex and location. Just like A/S/L was the currency of early chat rooms, it is the currency of advertisers today. It's fairly easy to figure out (at least roughly), and highly correlates to what you might purchase. 2. Your interests, habits and behaviours. You give this information just by browsing - every search you make on a website, every category you click, every subreddit or person you follow. How often do you do this? How long do you stay? What times/days do you do it? 3. Your real identity. There's a good chance that your email address is in dozens of online databases next to your real name, address, phone number, birthday and in some databases even your credit card number, bank details and social security. So putting this all together: * Individual websites gather info on you, some of it is sold to others, with or without your real identity. * Your computer can be tracked between websites, which means info gathered from one site can be used by another or linked to your real identity. * When advertisers connect this info to your real identity they can follow you even further - from one computer to another, to your phone, or to send you junk mail to your real address. Apps work slightly differently but the principles are the same: try to track you between computers/apps, gather info on you and target you. Advertisers provide modules that app developers can put in their apps, these modules help them track you between apps. VPNs can help disrupt some of this, you should use them but they are not a single solution. The EU GDPR was another attempt to restrict tracking by forcing companies to ask for permission first."
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cxiwhl | How did we get to the point where laptops and smartphones are in the same price range? | Technology | explainlikeimfive | {
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"The difference is that most people are buying the top spec smartphones ($1000+), but not nearly as many people buy top spec laptops ($2500+).",
"Demand for fancier phones with bigger screens and better cameras = higher cost, more people willing to pay for them. That being said, this is only true if you're comparing very specific subsets of price ranges. Laptops are still notably more expensive. Unless you're say, comparing a middle of the road phone to a low end laptop which isn't really a fair comparison. Looking at only big namebrands here to remove extreme outliers. A low-end smartphone (Samsung Galaxy A10) might be $120. A low-end laptop (Asus Chromebook C523) might be $240. A top-end smartphone (iPhone XS Max) might be $1500. A top-end laptop might be anywhere from $2500 for a more general purpose high-performer (High end macbook pro) or $3200+ for a high-end gaming laptop with a high-end display (ASUS ROG Zephyrus S GX701)",
"A smartphone is a handheld computer that does most of the computing you need at any given moment of the day, occasionally you can use it to make phone calls. A laptop is a more powerful computer, usually, that allows you to do the stuff you can't do with the smartphone. You pay what you pay for a smartphone for the convenience and you pay what you do for a laptop for what it offers. I like having a computer that can also make phone calls in my pocket throughout the day, having a laptop for school/work, and having a desktop setup for everything else.",
"Why aren’t smartphones getting cheaper? I remember buying my first big screen TV, a 1080p 50” plasma for almost $2k. Now all TV’s are much better and much cheaper. Smartphones? The iPhone I bought years ago was cheaper than the iPhones now. Maddening.",
"Most consumers don't know about ram, rom, storage, processor speed. So instead most people buy the new brand-name with the bigger number. You can get relatively cheap phones and computers if you buy based on the actual specs instead of whatever is being marketed as new.",
"Related: wtf do smart phones even *do* that requires being \"top spec\". Browse web. Having a sweet camera is a thing I can understand, but a thousand bucks?",
"I have a Note 9 with dock, mouse, keyboard, HDMI, and external hard drive. Also available with 8 gigs of RAM. Phones blow my mind especially as a custom PC guy. I used to get real excited for an upgrade that was nothing compared to this phone.",
"You pay for performance and portability. Laptops cost more than their performance equivalent desktops because smaller and more specialized parts are required to get the performance. More technology tends to go into them as well. Phones are the same way. More technology goes into your phone than probably anything else you deal with on a daily basis. That combined with the fact that smart phones are now the most portable computer we carry and use, and we no longer get carrier subsidies like we used to for signing two year contracts have made price you pay for the phone go up.",
"We got there at the time that a smartphone can do the same as a laptop for 80% of people. You can have a pc to share with your family, but all those Facebook/YouTube machines get obsolete once you can do it comfortably on your phone. The rise of smart TVs handled the movie/series part of laptop use and better web design made it possible to handle most of your internet doings through you phone (bills, banks, emails ...). Even gaming is being taken over and a large chunk of pc gaming has been canibalised by mobile. Now all you need a laptop for is work, writing something that isn't an email and gaming if you don't have a console.",
"Because people will pay the same for them. Many times price is determined by what the market will pay.",
"As has been pointed out, they really aren’t. But phones probably should cost more. 1. Miniaturization is expensive. 2. Phones need cellular modems. 3. Phones need better cameras. 4. Phones have higher pixel density. 5. Phones need GPS. 6. Phones are getting waterproofing. 7. Phones need to be more durable. There’s a bunch of other stuff that make phones way more impressive from an engineering POV. Laptops really only come with bigger versions of the same components which often isn’t actually that costly. Laptops have more connectors and a physical keyboard, but those aren’t super expensive either.",
"IMHO Apple had the brilliant idea of marketing and positioning their technical products as must-have status symbol fashion accessories. Certain people were willing to pay silly prices for gadgets that were technically not worth their asking price. Then others decided to follow. I recently upgraded to a $100 octa core phone with 4GB of RAM and 64GB of storage and it's covering all my needs, including remote connecting to client PCs for maintenance. Quite a few people I know that buy $1k phones just use them to surf the net/Facebook. They justify spending the money because they spend \"a lot of time on the phone\", i.e. making calls, when call-making is probably the only feature that hasn't improved since pre-smartphones. But at least they live up to society's measurement of social value.",
"What are you actually asking about OP? Why are phones so expensive? Why are laptops so cheap? The drive for more features in phones has been very strong over the past 10+ years. At this point a phone can do everything a laptop can, but is limited by OS and screen size. I can actually doc my phone over usbc, hook a larger screen and mouse and keyboard to it and use it like a PC. The drive for laptops has been to provide a larger spectrum of options. Some being super light weight, others being very powerful, and some going cost above all else. There is way more diversity in laptops than in phones, making some from name brands cheaper than a phone. The real question here is when is that line between phone and laptop going to be so blurred we will struggle to define it?",
"You're comparing high-end smartphones with mid and low end laptops. It isn't the same market. But from an objective standpoint, the smartphones of today can fill many of the same functions as the laptops of old. And so it makes sense that they have risen in price.",
"Companies like Apple and Samsung raise their prices, people line up to pay, so they raise it more next time, people still line up to pay and so on. People are willing to spend a lot of money for phones so companies charge them that much.",
"Everything has gotten cheaper to produce but phone makers keep raising the price of their phones because people keep paying it. Good night.",
"Consumerism. Apple's pricing system is a result of people becoming devoted to the apple ecosystem and basically turning into apes in 2001 Space Odyssey when they see an Android device. Once other major manufacturer's saw this trend they adapted the pricing policy. There are many flagship devices that run as smooth as Apple and Samsung devices but people are either afraid to go out of their comfort zone or the carriers are heavily promoting the top two manufacturers. Also Apple becoming a status indicator has a big role.",
"Because phones are laptops now. When you're buying a laptop youre not really paying for the screen and the keyboard what takes up the majority of a laptop. Phones now are jamming all of that into a tiny little package. Look at it this way, the note 9 can be docked where I can run cat6, hdmi and keyboard and mouse to it. It has 512gb of storage, 8 gigs of ram and a 2.7 GHz processor. That is an insane amount of power in a tiny little pocket sized device.",
"Rapacious marketers and people who are sheep. By this, I mean that lavishly-funded marketing departments create an artificially high sense of value and people in pursuit of vanity lap it all up and shell out their hard-earned dollars. We're going to get a lot more of this as cell phone technology is stagnating and manufacturers will have to amp up the psychological manipulation to dupe people into buying newer generations of phones that have fewer and fewer new features.",
"It is easy, because we pay for them. If apple came out with a 1500 dollar phone and not 1 person bought it what do you think would happen. They would have to lower the price it is that simple. Since the 1500 dollar phone would have thousands of idiots lined up outside to buy it they charge that much for it. Quit buying them as a whole and we gain the power back.",
"What about gaming consoles or even PC's that cost less than smartphones?",
"They aren't. You can get a cheap smartphone for maybe $20-30. You can get a cheap laptop for maybe $200-300.",
"On a phone, you have to cram a load of hardwarw into a tiny space, albeit not as powerful, ergo, not as hit components",
"You, the consumer. Demand and your wallet is what allowed these devices to exist at thier price ranges. And its hella complicated tech yo.",
"Apple sheep started it all by paying the insane price that they charged. Remember when a Google Nexus phone was around $350 and iPhones were $700+",
"Phone costs subsidized with cell phone plans probably does not help. If phones had to be paid up front, just like a television, I would not be surprised to see costs lower. I may be wrong."
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cxlxz3 | How do games "generate" what you see in-game, and tell graphics APIs (like OpenGL) where/how to draw it? | Sorry if the title made no sense but this hopefully will, I guess the first question would be: How do games "generate" the view of the game (aka what you see in the game, like in minecraft it could be trees, blocks, grass, etc)? What methods do they perform to somehow squeeze (based on maybe camera angles, FOV, etc) a bunch of vertices or "data" into a big list or collection (i could be very wrong on thinking that the CPU/code generates the pixels and stuff), And secondly, how do games take whatever was "generated" and tell the GPU to render it? i found this cool OpenGL engine that uses a thing called a Matrix4, and uses 2 of them with a function called `glUniformMatrix4fv` to, i guess, render whatever Matrix4 contains (i could be wrong again). I have actually looked at a lot of sources explaining how game engines work but i still cant really get the grasp of how they get all that graphical data (what you see in games), whether it is a huge list of individual pixels or a list of vertices or something else, and how they tell the graphics API to render it | Technology | explainlikeimfive | {
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"This is a pretty complex problem, but I can give an overview for a basic 3D engine. Every object in the game is made from a mesh of triangles. When the shapes in the game were originally designed, the vertices of every triangle were ordered. Based on the order (clockwise) the computer can calculate the normal vector to every triangle. This list of vectors and vertices is just stored as a monster array in memory - nothing fancy going on here! For efficiency it's stored as one list/array of vertex x, y, z coordinates with a numeric label and another list of vertex labels in groups of three to define the triangles . This is reasonably efficient since you don't have to repeat the definition of the xyz coordinate for all the vertices shared between triangles. Next you translate everything to screen coordinates. This is a geometric transform which maps every vertex on diverging perspective lines from the centre of the camera in cartesian coordinates, to a new system where these perspective lines are parallel and orthogonal to the screen. X and Y now align to the screen, and Z is the depth into the screen. Doing this simplifies a whole load of the following calculations since you no longer need to do any computation for perspective. The particular transform you apply controls the FOV. For the game to zoom in and out, for example if you look down the sights of a gun, it adjusts the transform. Now you step through every triangle in the giant array one by one. As you step through, you first check if the triangle is behind the camera, in screen coordinates this is trivial, if the z coordinates are negative its behind you and can be ignored. Once you've done this, remember those normals I talked about earlier, you check if they are pointing towards or away from you. You take the dot product of the normal vectors and a vector along the Z axis (another convenience of screen coordinates). All the triangles which aren't facing you, they can be ignored too. For the remaining triangles, you compute the angle between any light sources, and the triangle and the pixel being rendered. There is a simple relationship between angles and brightness of the triangle. Now you render the triangle in screen coordinates based on it's calculated brightness, color, texture and place it into the z buffer. The z buffer is a piece of memory set aside which is large enough to store the RGB value of every pixel on your screen, plus the z coordinate of the pixel. As you render every triangle, you check every rendered pixel against the z buffer. If the z coordinate is less than the data already in the z buffer, then it overwrites the data in the buffer, otherwise the information is thrown away. This ensures you don't render objects blocked by other objects. Once complete, you display the z buffer contents on the screen. For the next frame, you repeat this whole process again. There's a phenomenal amount of computation going on! In reality there's a whole load more going on to make everything look smooth and textured rather than blocky - but that's the gist of it!",
"This is too complicated to put into an ELI5, but I'll try to break it down into simple terms that someone who is familiar with 3D games will understand. Modern 3D games are made up of things called objects. Each object has a position, (Called a vector, which is 3 numbers, X, Y and Z), rotation (Usually a quaternion, like is like a vector, but with a fourth number), and a scale (This is the overall size of the object). The player that you control in a game is an object, the floor you walk on is an object, even the sky is an object. The camera position is important as it is necessary to draw the objects at sizes relative to their distance from it. So if you're in a game, looking down a long hallway. The walls will be gradually decreasing in size the further away they are from the camera. The graphics software will know this based on the vector of the camera and each portion of the wall and it make them appear smaller, to simulate depth perception."
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cxmkmk | How do emulaters work in gaming? | Technology | explainlikeimfive | {
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"In computing, an emulator is hardware or software (respectively physical object or downloadable application) that enables one computer system (called the host) to behave like another computer system (called the guest). An emulator typically enables the host system to run software or use peripheral devices designed for the guest system. In other words, if you get a PS4 emulator on PC, it’s like having a PS4 without having a PS4 but by downloading everything a PS4 has."
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cxt15i | How exactly is a CPU taught to process information? | I am talking about the first contact between the motherboard and the CPU. How does it know what gates to open? Do CPUs come with certain gates already charged so they start thinking as soon as they are powered on? Are they taught at the factories with some sort of special prearranged stencil? I have a very basic understanding of how a micro processor is made and how they work, but the intial configuration has always baffled me. | Technology | explainlikeimfive | {
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"It gets power from the motherboard and a signal to start. It then goes through a pre-defined startup sequence. It knows which pins to send signal voltags to, because that's all predefined for a particular socket. Through the signal pins, there is then a basic protocol it goes through together with the motherboard to enumerate all peripherals and memory etc. (the progress of this sequence can be seen on the 2-digit debug LED on fancy motherboards). All the peripherals and functionalities are accessible to the CPU through predefined pins (which are publically available through Intel's or AMD's spec sheets, and used by motherboard manufacturers to construct the motherboard) They aren't \"taught\" anything, they are just hardwired to do it a certain way.",
"The CPU is designed to process certain instructions. You give it commands and it manipulates memory/whatever it needs to to do what the program is designed to do. You are actually pretty on point with saying a stencil since that is exactly what is used. At its most basic, a CPU is a bunch of wires and transistors, transistors being little electronic switches. As it turns out electronic switches can be wired together in the right arrangement to process logic, say addition and what not. A stencil is designed and using a trick called photolithography, we shine light through the stencil onto chemicals on a slab of silicon which etches the design and logic of the CPU onto the silicon, along with some other chemical processes. The motherboard is designed to work with the CPU itself. It mainly acts as a thing to connect the CPU to the rest of the computer."
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cxtade | What happens to a notebook when you never shut it down completely? | I seldom shutdown my pc because I often have open tabs or programs which I am to lazy to save or to close, so I only use the battery-safe mode. Furthermore, when I shutdown my pc, it takes a long time till everything is loaded etc. I know that a notebook should not be used that intensively like a Desktop PC and shutdowns are important but why exactly and what happens when I never do one. | Technology | explainlikeimfive | {
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"The simple answer is that the longer your computer runs, the more time there is for glitches in the system to happen. One glitch usually isn't a problem, but when you have 10 or 100 at the same time, it can be enough to cause some issues. When you restart a computer, you're clearing away all the loaded memory (RAM), and any glitches with it, and reloading everything anew. The core system files on the hard drive are seldom actually altered by the computer. A more detailed answer, if you need it: everything you see on a screen, and everything the computer does, is all saved in RAM. It's the short-term memory of the computer. Files and programs get saved on the hard disk, which is like the long-term memory. But each time you run a program, or open a file, it gets moved to RAM, until you close it. With the OS, it's in RAM the entire time the computer is on. As you and I know, our short-term memory isn't always reliable, and while computers have a better track record than us, their RAM isn't infallible either. The longer something is in there, the more likely it is to be misremembered. By rebooting the computer, you're replacing the old memory of the OS in RAM with a new copy of the OS from the hard disk, which is glitch free. It's the computer equivalent of taking a nap to clear your head",
"Nothing in a perfect world where programmers don't make mistakes. But the consequences of bugs in applications you've installed and even the OS itself may add up over time and cause it to perform poorly or eventually crash. Whether that actually happens and how long it takes depends on what software you've installed."
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cxti7o | Why is restarting the computer often solves the problem? | Technology | explainlikeimfive | {
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"Programs or drivers can have bugs that causes the computer to lock up or have erratic behavior. Restarting the computer clears them out of memory allowing the computer to run as normal. If you can replicate the error by doing the same thing you were before then you found a proper bug, otherwise you may have found just a glitch where a perfect storm of events came together. The clearing of RAM is only one part of it, and as there are many reasons for the computer locking up, everything from GPU issues, kernel panic, overloaded processes, overheating, not enough storage space on your device, etc etc, it's difficult to give you just one answer why restarting works. It's a good first step as a catchall though.",
"Your computer has 2 memory devices, 1. RAM 2. Hard Disk The data is permanently stored in hard disk and when your computer is turned off data still remains in the hard disk. RAM on the other hand is opposite data stored in RAM remains there only as long as there is power. Once you turn off the computer all the data in the RAM is lost. Now, why are there 2 memory devices? Your Processor is very very fast but your hard disk is very very slow but the RAM is very fast so what the OS does is that whenever you start the computer and open an application the OS takes the data from hard disk and puts it on RAM and the Processor accesses the data fastly from the RAM. But the problem is RAM is very costly so you have very less quantity of RAM and when your computer is running lots of applications the RAM gets filled up, now as the RAM gets full problems start to occur as not all applications can put their data on the RAM as the small RAM is getting shared between all the applications. Restarting the computer clears the RAM and you start as a fresh slate and that's why restarting solves the problems."
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cxty5w | Why are magazines very typical for rifles, assault rifles, and pistols, but very atypical for shotguns? | Technology | explainlikeimfive | {
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"Pump action and semi automatic shotguns do have magazines, they're just not usually removable. They're a tube magazine underneath the barrel. I'm guessing you're asking why are detachable box magazines uncommon. It's because shotgun cartridges don't lend themselves very well to stacking on top of each other. They have a wide rim, and are plastic which can deform under pressure. This can cause feed problems which makes the gun unreliable.",
"Size of shotgun shells for starters, makes more practical sense having it in a tube fed magazine under the barrel.",
"Not all rifle magazines are \"typical\". Bolt action rifles often have integral, clip fed unremovable magazines. Lever action rifles often have tube magazines. The removable sector magazine is convenient for semi auto and full auto firearms, that is why a lot of these firearms have removable sector magazines. Non automatic firearms, such as shotguns, bolt and lever action rifles have a variety of magazine types."
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cxvlrt | Why do strange lines appear when you take pictures of a screen? | Technology | explainlikeimfive | {
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"on top of things that other people have mentioned, the two misaligned grids cause whats called a moire. the grids of your camera and computer screens are too small to make out with the human eye but when two grids are angled to one another, other larger patterns form. [moirè patterns - wikipedia ]( URL_0 )",
"Televisions work by constantly refreshing a string of lights across the screen, one line at a time. Especially on older displays, this refresh leaves flashes of colored and black lines, which happen too quickly for most human eyes to see. However, your camera is closing it's shutter much faster than you process an image, allowing it to capture the incomplete image of the television screen, while your brain would fill in any noticable gaps with other information.",
"Depending on what type of line you mean, it could either be the framerate mismatch that all the other comments are refering to, or something called the [Moiré effect]( URL_0 ), where two misaligned grids, in this case the pixels on the subject screen and the pixels on the camera screen, create lines that don't exist. It's the same reason that games often struggle with fine grilles and grids, where these pattens appear unintentionally.",
"It’s called Aliasing. One example is the Moire effect. In general, when you sample something (like taking a picture) with a resolution that is coarser than some repeating features in the picture that are finer (that is, they have a higher spatial frequency), they get “aliased” and look like features of a lower spatial frequency, resulting in lines or bands. A similar example happens with video, when something rotating at a speed faster than the video sampling rate looks like it is rotating much slower, or even in the opposite direction (like sometimes the wheels of a car that seem to rotate backwards).",
"Gavin from Slow Mo guys has an AWESOME explanation for this. Super detailed and researched URL_0",
"Because the screen doesn’t shine constantly, it refreshes at a certain frequency (24-144 Hz, depends , but usually 30/60 Hz). Taking a picture captures the light from those which shine, but not from those that are currently refreshing, or not shining."
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cxvzhl | What is the difference between “pasteurized” and ”ultra-pasteurized” milk, and why do some countries only have the shelf stable “ultra-pasteurized” kind? | Technology | explainlikeimfive | {
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"Pasteurized: Heated to 145°F for 30 minutes (normal pasteurization) or 161.6°F for 15 seconds (flash pasteurization). Fridge stable for a couple weeks. UHT, or ultra-pasteurized: Heated to 280°F for 2 seconds. Shelf stable (unrefrigerated) for ~9 months. Not sure why some countries would only have UHT, probably because it stores easier and is easier to transport because it doesn't require refrigeration."
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cxw2uq | Why do headphones seem to get quieter over time? | Technology | explainlikeimfive | {
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"text": [
"If it’s the type that goes into your ear as opposed to going over your ear it’s usually earwax. Clean them out and they go back to being new",
"I think its less in the technology and more in you. You get accustomed to listening to that volume that isn't that loud anymore"
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cxwbrt | How is a cell phone able to Make calls to 911 when its out of service.? | Technology | explainlikeimfive | {
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"It depends on the kind of \"out of service\" you have. There are basically two. One is you are not within range of a tower than is owned by the company you use, or that has a sharing contract with the company you use. The other is that you are not physically within range of any tower at all. If it is the former the 911 system will still work because it overrides the protocols that tell your phone it has no contracted signal. If it is the later you have no physical signal so it will not work.",
"Normally when you make calls, your signal must bounce off the tower of your service provider (ex Telus, Fido, Rogers, etc.). As I understand it, you can make calls to 911 when your phone shows no service because it will bounce your signal off of the closest tower, regardless of your service provider."
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cxwmep | why is nonstop loading such a common glitch among all apps/programs? | Being stuck on a loading screen seems to be universal. | Technology | explainlikeimfive | {
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"Usually the loading screen is displayed while loading assets to ram from an external source(hard disk, network, etc). If for whatever reason the loading fails(wrong paths, corrupted files, etc) than the loading process will never succeed thus the loading screen will continue to “load” forever. Edit: There might also be cases when the loading doesn’t fail, but is way slower than usual(low download speed, hdd being used to its max speed by other apps, etc...). This will make it feel like its stuck when instead it just needs longer. This is(in my opinion) a more common case, as well written software will handle stuck cases properly(terminating with an error message, trying to reload, etc...)."
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cy0ujv | How does information pass through the air? (ie, Wifi, television, phone calls, etc.) How did someone learn to do that? What? Science and technology literally blow my mind. | Technology | explainlikeimfive | {
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"Wireless communication usually uses radio waves, which are a form of electromagnetic radiation just like visible light is. While visible light is blocked by most solid materials, radio waves can pass through most substances to some extent, which is why you can use a cell phone from inside your house (but probably not in a tunnel underground). The radio waves are created by passing an electric current through an antenna. When the radio waves hit another antenna, they then create another electric current. The electric current used to make the radio waves is varied to send specific signals, and the electric current on the other end is measured to decode those signals.",
"something to think about is that radio waves have always been around but humans had no idea..... there are almost certainly things going on right now that we have no knowledge or understanding of because they are beyond the perception of ourselves and our tools.",
"*(this is pretty high level basic - like even more basic than Karen at Starbucks in October)* Imagine some kids holding a jump rope stretched out, and wiggling it so that it causes waves. [Like these kids I found on YouTube]( URL_0 ) At the very beginning of this video, the girl in the blue shirt is the \"transmitter\" and the black shirt is the \"receiver\". About two seconds in, they switch, and the blue shirt is now receiving. Let's look at the waves they're both generating. The blue shirt is generating a lot of short fast bursts, and the rope never really gets that high off the ground. The black shirt is sending slower larger waves. Now, if they both agree that \"a big wave == 0 and a small wave == 1\" we have a system for transmitting binary data. This works in theory, but we'd need a lot of rope! Here's where super awesome science comes in... In the late 1800s, some German dude named Hertz set out to prove some ideas people had about electrical and magnetic fields; ultimately he was successful in proving the existence of invisible electromagnetic waves. Now, a \"eureka\" moment is actually pretty rare in science. More often, a discovery is not that \"big\" because they are usually building on previous work. Hertz was NOT looking for a way to transmit data with his research, however during the same time period, folks were thinking \"dang, this telegraph is awesome, but it'd be nice if we didn't have to stretch the wires all over the place. Can we do this another way?\" THOSE are the clever scientists who figured out how to ultimately harness these waves, and use them to \"pass information over the air\" that we all rely on so much these days."
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cy1x5k | What is the difference between MULTICS and UNIX? | Technology | explainlikeimfive | {
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"Historically? From the Wikipedia entry for [Unix]( URL_0 ): > The new operating system was a **single-tasking system**.[\\[10\\]]( URL_0 #cite_note-DMR-10) In 1970, the group coined the name *Unics* for *Uniplexed Information and Computing Service*(pronounced \"[eunuchs]( URL_6 )\"), as a [pun]( URL_7 ) on *Multics*, which stood for *Multiplexed Information and Computer Services*. [Brian Kernighan]( URL_5 ) takes credit for the idea, but adds that \"no one can remember\" the origin of the final spelling *Unix*.[\\[15\\]]( URL_0 #cite_note-15) Dennis Ritchie,[\\[10\\]]( URL_0 #cite_note-DMR-10) Doug McIlroy,[\\[1\\]]( URL_0 #cite_note-reader-1) and [Peter G. Neumann]( URL_2 )[\\[16\\]]( URL_0 #cite_note-16) also credit Kernighan. Multics is a multi-task OS, and at the very beginning, Unix was a single-task OS. The name is a pun. I don't know what you mean by \"multiplexed\" and \"uniplexed\" in the context of an OS though."
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cy1xfa | Back then before everything like C++ and even HTML was around, how were video games for consoles like the NES developed? | Technology | explainlikeimfive | {
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"They were written in the 6502 assembly language. A few were written in C, but those apparently had a reputation for being slow due to the specs of the NES itself.",
"The CPU in a console can read and perform very simple instructions stored as bytes in the program file, so one number might mean \"load up the number from a location in memory\", another instruction-number might mean \"add two values together\". In C, you'd type something like x=y+5; // Get the number stored as 'y', add 5 to it and set the value named 'x' to the result The \"compiler\" is a program which is used to make the real program file from that human-written code. It takes that one line and writes out a whole bunch of the instruction-numbers that the computer understands. & #x200B; Before having languages like C, the programmer could still write understandable instructions, but they were more on a level with the machine language. So you'd write instructions like this for the above (not a real language). The bits after -- are just my comments and would not be part of the program (although programmers add stuff like that to explain what they're doing in real code too)., `load ptr1,4002 -- meaning get ready to use memory address 4002 (where the value of y is) by storing it in a special CPU memory ptr1` `load value1, (ptr1) -- get the number stored in the memory address that ptr1 is pointing at into a special CPU memory named value1` `load value2, 5 -- get the number we're going to add into the 'value2' CPU store.` `add value1, value2 -- do the addition - this computer can only add its special \"value\" stores together, we can't just add things directly.` `load ptr1, 4010 -- this number happens to be where we'll store the value named 'x' in the C code so set up ptr1 to point to that. We're done with the 4002 memory address that holds y.` `store value1, (ptr1) -- store the result of the addition in ptr1, which is now pointing at where we want to store the value 'x'` & #x200B; The computer still can't understand \"add value1, value2\" - it only understands some code-number that means that. So like with C, a program converts the written programs into computer code, except that you'd have to pretty much write the code as a 'human' version of each computer instruction. One line to one machine instruction, instead of one-to-many that you have with C compilers. So you could still write the program, but everything was more laborious. You had to spell out everything in simple form on the computer's level.",
"Not exactly related, but for some more info on how developers worked within the limitations of such primitive hardware, [check out this video]( URL_0 ). It's by the developers of a recent NES game called Micro Mages and covers all the neat tricks you'd use to fit a game into such a small amount of storage.",
"ELI5: Your computer is like a chef. When you tell it to do something it follows a set of steps in a recipe to make a dish. The steps are composed of the same basic instructions (add a cup of x to x, or heat y to z degrees). These basic instructions are what the computer calls assembly, and programming languages are nice abstractions on this that let you write recipes faster, but in the end the computer will still break them down into simple steps. A game is like a full dinner it's several recipes composed of thousands of steps put together. Back in the day people used to hand write each step for the computer, and now we can use libraries to just grab whole recipes or write multiple steps at once. TL;DR: we used to write the programs in assembly one instruction at a time",
"Early (computer/video) games were coded in basic or assembly. For the case of the NES it was assembly. So tldr on what \"assembly\" means: Your literally manually coding the bits and bytes in specific orders. So every command a modern programmer would write(+/-, if, then.. basic things) they would look up in an index for that processor, and then enter it in binary. Assembly is then, basically, just *assembling* binary into basic computer code (usually only for a specific system, due to the index/instruction list issue). This is also called a \"low level\" language, as it's easier to run, as it's in \"computer speak, but therefore is not immediately intelligible to humans This was part of the reason why nes games were so light on storage/packed with data; It'd be difficult(usually impossible) for modern code, in high level written languages, to be compressed that far because the instructions are so much larger and more complex in higher level code vs assembly's base level cpu instructions. You'd basically have to go write in assembly or basic yourself to get close with modern software programming. It's probably also why their super easy to break in like sooo many ways... Fun fact: because the GB (original, but also color) was basically a portable NES (as far as hardware was concerned), the original pokemon games were also coded in assembly, that was in the mid 90s, so actual languages you'd recognise (or their precursors) were around, just the hardware limitation was still a decade back in '85... So if you wanted a large scale game on the gameboy(oh idk, like; 151 pokemon, unique moves, 8 gyms, etc) ; you STILL had to code in assembly a decade after the NES era :p If your interested in the coding of a NES game someone did do it recently... Sure it runs in emulators.... but also on the NES, on cart! The modern 40kb nes game : URL_0 DevTalk on learning/understanding assembly in 2010s (for if you code): URL_1"
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cy34t6 | Why do laptops never seem to have the same types of chargers like phones do? | Its as if every type of laptop has a different charger? Its so confusing when I have an Asus and my classmate, also with an Asus, can't use each others chargers. I was curious if there was some reason for it, or if its just for money. And if it is just for money, how come phone company don't do the same thing? There was a post about this from 4 years ago, but I was wondering why the chargers haven't become more standardized? | Technology | explainlikeimfive | {
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"There is light at the end of the tunnel. Many new mid/highend laptops take USB c chargers, the same as most new Androids",
"There was never any gain in establishing a standard, so one never stuck. However, USB type C is gaining popularity, and an extension of it called Thunderbolt 3 allows you to attach a lot of external peripherals to a laptop, but also has a standard for charging. The incentive to use a common charger finally exists!",
"They use different voltage, Watts & amperage that are not comparable with cell phones. Besides if it was the same then the computer manufacturer couldn't make you buy their proprietary charger."
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cy3k0r | How do those hidden 3D object pictures work? | In the early 90’s hidden 3D object books and posters were very popular. Initially, they just look like random colors and patterns, but if you stare at them long enough you can see 3D images. How do they work? | Technology | explainlikeimfive | {
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"It's a technique called Single Image Random Dot Stereogram. It overlaps two images hidden in the pattern of random dots in such a way that when you focus correctly, each eye sees just one of the images. That creates an illusion of depth."
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cy3qjl | the meaning behind the term '8 bit' and what it entails. | The term 8 bit is thrown around a lot and I'm starting to wonder if it actually had a meaning to begin with. Also the reason I have to ask is cause I'm too young to know. | Technology | explainlikeimfive | {
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"Computers run on a system of bits and bites. Represented in binary. 01010111 Ect 8 bit refers to how many bits you have to store an instruction in computer language. More bits means more complex things an be done.",
"8-bit refers to some of the earliest computers available to consumers. 8-bits, or a byte is what is also required to form 1 ASCII alphanumeric character. 8-bit colour also means you have a maximum of 256 (2^8) colours to work with on these systems. With such limitations, I think it's mostly used to describe something old, probably low-powered. Hope this helps!",
"I would like to point out that the limit of 8-bit is not a very solid one. [Here is an 8-bit device playing back an acoustic music file]( URL_0 ). Moreover, 8-bit CPU's *can* compute numbers higher than 256, obviously. The NES could track high scores in the millions. This is done by splitting the big number up in smaller 8-bit 'digits'. In a way, we are 1-digit machines too. If you want to multiply 123 by 456 by hand, you break it up into problems like 3 times 6 and 4 times 2 before arriving at your final answer. Obviously doing 123 times 456 in one go is a lot faster, so 32-bit CPU's are usually faster."
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cy4t4k | How do impact garden sprinklers work? | I always seem to observe those garden sprinklers that go CHK CHK CHK CHK CHK CHK CHRRRRRRRRRRRRRRRRRRRR and I can never piece together how they actually work and rotate. Please, explain this like I am 5. | Technology | explainlikeimfive | {
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"There's effectively 3 pieces to it, the base where you attach the hose, the nozzle where water comes out, and the impact piece. The impact piece had 2 arms which are angled to alternately catch the water, giving the back and forth motion. The nozzle assembly can also rotate, but does so only when hit by the impact piece. There's some trickery with levers and springs so that the impact motion moves the nozzle one way slowly, CHK CHK, and then when it hits the stop it goes the other way quickly, CHRRRRR. Then it hits the other stopper and repeat.",
"The CHK CHKs are the water pressure pushing the nozzle to the next notch, and the CHRRRRRRRRRRRR is when the pressure is released, flying by the one-way notches",
"The nozzle of the sprinkler is mounted on a base that allows it to spin freely. The impact arm is longer than the nozzle and mounted on the same base so that it spins on the same axis. It is held in line with the nozzle by a fairly weak spring. When the sprinkler is running, the water shoots out of the nozzle and crashes straight into the impact arm. The water hitting the impact arm pushes this arm out of the way. The impact arm swings around it's axis until the spring stops it, reverses it and brings it swinging back towards the nozzle. When the impact arm reaches the nozzle, it crashes into the nozzle and pushes the nozzle a short distance around the circle. Then the water hitting the impact arm pushes it out of the way again for another cycle. The chk..chk..chk sound you hear is the impact arm repeatedly crashing into the nozzle. When the sprinkler needs to reverse, a small stopper pops up that prevents the impact arm from swinging as far as it normally would. Now, on each cycle the water hitting the impact arm pushes it out of the way. The impact arm swings a short distance around the axis and crashes into the stopper. This crash into the stopper pushes the nozzle back in the opposite direction. Then the spring pulls the impact arm back in line with the nozzle. Because of the restricted swing, the impact arm only pushes the nozzle a little bit when it crashes into it in reverse mode, so the overall movement of the nozzle on each cycle is in reverse. Then the impact arm gets pushed out of the way by the water again. The tick, tick, tick sound you hear when the sprinkler is reversing is the impact arm crashing into the stopper. The shorter swing distance is why the ticks are more frequent than the chk..chk..chk sound it makes in the forward direction."
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cy4w30 | Is it possible to "fake upscale" a digitally-filmed 1080p movie to 4K resolution? If so, how? | Specifically, the question is about two of the Star...War.s movies (II, III) which were filmed digitally at 1080p. If Disney, with all of its resources and technology, were to re-release a collection of all the movies at 4K resolution, would it be possible for them to modify those two 1080p movies in a way that lets them fit in with legitimate 4K films? | Technology | explainlikeimfive | {
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"Yes, it is easy to upscale to any dimensions you desire. Just pick your choice of dozens to hundreds of interpolation algorithms to get the look you desire. No, it is impossible to recreate a high-resolution work from a low-resolution one. The same, low amount of \"quality\" will merely be spread out across more pixels. There is no place to hide in between the pixels—any details that were not captured or that were thrown out during downscaling are gone. Yes, there are ways to improve the appearance of an upscaled work, such as by sharpening edges or adding noise to conceal blurriness and banding, but these treatments cannot truly replace any actual fine details."
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cy76q9 | Why do Li-on batteries loose capacity when we fully charge them and why do they last longer if we keep them between 40 and 80 % charge? | Technology | explainlikeimfive | {
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"Batteries run off of a chemical reaction that is easily reversed with electricity. Most reactions just won't work. When batteries are charged up to full, the reversed reaction starts to run out and side reactions start that render parts of the chemicals unusable. The same happens when you fully drain a battery. Do this enough times, and there's very little useful chemicals left in the battery."
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cy9lmi | why do magnets ruin Computer Monitors, phones, tablets, etc.? | Technology | explainlikeimfive | {
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"text": [
"Phones and tablets should be ok with almost any normal magnet. Hard drives and floppy disks use little magnetic zones to hold ones and zeros - magnets can change them and wipe them out. Old CRT TVs and monitors use magnets to steer an electron beam - adding another magnet nearby will mess up the steering SSD drives and LCD or OLED displays should not be affected unless the magnetic field is nuclear-bomb EMP level strong, at which point every kind of electronics will die",
"To put it simply, all of these devices store information on a hard drive. This information is essential to the function of the device and contain all the code that tells it what to do. Hard drives store information in binary - a string of 1s and 0s that come together to form something more complex ideas. Phisically, these ones and zeroes are stored by millions of tiny magnets that are flipped either up or down. If you run a magnet over a hard drive then all the tiny magnets get flipped over and the information they represent is erased."
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cyaiw6 | Rather than use air conditioners that just move the heat around and use energy, why can't we extract the ambient heat energy of a hot room and convert that heat into usable energy ? | Technology | explainlikeimfive | {
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"You get energy when moving heat from a hotter place to a colder place. Power plants use fire or nuclear reactions for the hot place and water and sometimes cooling towers for the cold place. To get energy cooling a hot room you would need a colder place where you could move that heat. The only possibilities I can think of in summer is underground or some cold water. Also, it is much easier to get energy when there is a large temperature difference. The difference between a fire and water in a river is large, and a power plant can use that. Compared to that the difference between a hot room and some cold water is tiny, and it would be hard to get energy from that.",
"There has to be a temperature differential to collect usable energy. Since naturally the heat wants to be spread equally you can collect energy in facilitating that spread. If it's already spread equally then it takes energy to make the difference greater.",
"2nd Law of Thermodynamics Extracting energy from heat differences (through a heat engine) is never 100% efficient. See any explanation of the carnot efficiency. Energy itself is not useful, the entropy of the environment determines how useful it is. There is a teemendous of low level heat energy in the ocean, but we cannot use any of it because it is just too spread out and trying to collect it would use more energy than what is available. The same applies to what you've said.",
"Everyone else’s responses are accurate regarding why you can’t generate electricity from it, but there are actually Energy Recovery Devices in some Commercial HVAC applications. For example, a heat wheel, a heat pipe, or a plate to plate to heat exchanger. These devices function by taking energy from the Return/Exhaust air stream and transferring it to the outside air. Source: I work for a company that builds commercial HVAC Air Handlers that install all 3 of these devices. Wikipedia article on heatwheels URL_0",
"The term you you should look up is \"usable energy\". Since the outside is hot too, there's not way to harness that energy without a difference in temperature",
"We can. There are water heaters that pump heat from the room into the water. All in all, gas heaters are more cost effective, so they are more common.",
"because it's not hot enough to do any real work, energy for your house is crated by using heat to turn water into steam which turns a turbine and produces electricity, the air from an AC unit isn't hot enough to do that so it's just pumped outside",
"Think of heat energy as water, and your air conditioner as a dam. The second law of Thermodynamics, in simple terms, states that the water (energy) level in the lake will always even itself out over time. What you're trying to do here is make an area with a really low water level (your room). That water has to go somewhere, so you need to pump the water onto the other side of the dam, which takes energy. Since you're counteracting the water wanting to even itself out, it will always take a lot of energy, and never create it. If you were to do the reverse, take water from the high level to the low level, you could use that to create energy. That's how most power stations work, by heating up water on one side and letting it cool on another.",
"This article talks about how Cornell University uses the cold water 250 ft down in the Finger Lakes as a heat exchanger for their campus-wide cooling systems. URL_0",
"Theres not enough temperature difference or stored energy in ambient air to make it worthwhile. It would be the equivalent of making a dam 1 foot tall."
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cybahy | how do prosthetic arms/legs work? How is the person able to control every joint? | Technology | explainlikeimfive | {
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"Older motorized prosthetics were often controlled using switches inside the cup(? Not sure the proper term) that the amputee would manipulate with their stump.",
"The really expensive ones, have been/are being developed with the help of neuroscience so that the prosthetic behaves like a real limb. In that, it responds to the same brain signals as if the limb actually still existed. The more affordable ones use simple mechanics to create interactions *similar* to limbs. So like, the one I designed in high school, would grip an object if the person wearing the prosthetic stepped on a little pedal that was built into the shoe I designed. Obviously this doesn’t work so well if a person is missing multiple limbs or there are more interactions needed than can be designed into a personal situation. The expensive ones are also more practical from a production point of view. You don’t have to survey each customers situation to help them."
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cyd8lo | Why can't large scale dehumidifiers in humid areas be used as a viable source of potable water? | Technology | explainlikeimfive | {
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"I guess it depends on your definition of viable. Really humid areas usually don't lack for water and there are way easier and cheaper ways of getting lots of water (collect rain, dewtrap, well,etc.). So you could do this, but it would be a complete waste of energy. It would possibly be effective in a \"stranded at sea\" situation. In places where water is scarce, water **is** scarce.",
"Water is so cheap it's essentially free. The industrial dehumidifiers would take a lot of energy, which is decisively not free. There is no business case for using dehumidification to produce drinking water.",
"The atmosphere already has a dehumidifier installed: it's called precipitation. So humid areas get plenty of snow or rain which collects in fresh water streams, puddles, lakes etc. A human-made dehumidifier will not be cheaper or more powerful than this. Areas that don't have enough potable water also aren't humid. That's why they don't have potable water in the first place. So there just isn't really a place where this would be a helpful technology. Of course, if you need to dehumidify a place anyway, you might as well use the water it produces to save water elsewhere. Not sure it's typically drinkable, but you could probably water plants with it, for instance."
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cygdj9 | what is torrenting and is it legal? | Technology | explainlikeimfive | {
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"100 people own Software ABC and want to \"share\" it. Each owner puts up 1% of their software information up for download. By torrenting it, you download 1% from each of the 100 owners and compile it together to form a full copy. It's illegal because it's essentially stealing from the original creators."
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cyj9fl | Why do so many sites contain anti-bot captchas? What purpose do the bots serve and why are they being regulated? | Technology | explainlikeimfive | {
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"Bots can serve many purposes. One example is guessing peoples' passwords - if you get your password wrong two or three times then you may be asked to do a captcha. Another example is flooding a site with activity in hopes of giving the server too much to handle and breaking part of its software. Another purpose of bots is making fake accounts for various reasons. Websites really don't like any of these things, so they install captchas to keep the bots at bay.",
"Captchas are also being used to train AIs. Everytime you log in you are looking at pictures and showing AI what a sign is or what a bus is. It is outsourcing literally thousands of hours of AI definitions."
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cykgsr | How people get to know which colour it is when they convert a black and white photo into coloured one? | Technology | explainlikeimfive | {
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"Partly research and partly guessing. Some elements may be obvious (brown wood, blue sky, skin tone, etc), some may be researched (most popular color of a certain year of car) and some is just a colorists’ choice.",
"Someone just converted an awesome pic from the 1900s from black/white to color and they explained in the comments that almost every gray corresponds with an actual color. But it's not an exact science. It was really interesting to read. I think it was in r/pics. I'll try to find it.",
"It is generally research and informed guesswork. If you have the original negative and know what kind of black and white film it was then you can check against a colour response curve for that film which will give you some clues as to what a particular grey is likely to be - but this still involves a lot of guessing. Mainly it is by consulting other references, e.g. we know that leaves are green, certain street signs are red or blue, bricks are red, slates are grey etc. There is one exception to this. If you have a black and white film of a video that was originally photographed in colour then there is a recently developed process that can restore the colour based on the existence of \"chroma dots\" in the black and white image. This technology is being used to [restore the colour to old TV shows]( URL_0 )."
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cypoh4 | How do force shutdowns/restarts work? | Technology | explainlikeimfive | {
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"text": [
"A normal shutdown gives programs time to save what they are doing and close down properly. A forced shutdown just forces everything to stop and close, regardless of what it was doing. It's like a bar at closing time. A normal shutdown is the bartender telling everyone to finish their drinks and pay their bill, and then waiting for everyone to do so. A forced shutdown is the bartender just kicking everyone out - some of the patrons might have been paying attention to the time and left the money out for their drinks, but others are just getting kicked out with the tab open."
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cyqx8d | When using Apple Pay how comes on the receipt it shows a completely different last 4 card numbers? | Technology | explainlikeimfive | {
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"text": [
"It is security, to protect the actual card number. They don't use the actual number of the card, but the other one as a proxy."
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cyua58 | Why is it that pictures of certain screens (usually backlit ones, like TV’s or laptop screens) get that kind of weird grid that moves when you look at it in the photo? | Technology | explainlikeimfive | {
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"text": [
"It can be moire; likely it's due to the polarization filters that all LCD screens use. URL_1 URL_0"
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cyup2j | why does a DSLR take X time to process an X time exposure photo? | I was just taking a long exposure photo (30 minutes) with my eos 200d, and now as i stare at its useless form, with 'BUSY' being the only sign of life, i wonder why a photo will always take its exposure time to process. EDIT: to clarify, i understand how changing the exposure changes the brightness of an image, i don't get why changing the exposure changes the *processing* time for the image ie: after the shutter has opened and closed I do have an electronic engineering degree, so maybe ELIHAEED (Explain Like I Have An Electronic Engineering Degree) | Technology | explainlikeimfive | {
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"What it's doing is taking a [dark frame]( URL_0 ) Sensors are noisy, and over long amounts of time, the noise adds up over itself. Turns out this noise isn't completely random but develops patterns, because for instance there's circuitry around and behind the sensor. You can see this in the sample picture. The noise depends on the specific camera, sensor, and environmental conditions like temperature, so it works best if the dark frame is taken as close in time to the picture as possible. So what the camera does at long exposures is take a picture, then close the shutter and take a photo of complete darkness. And due to noise it's not going to come out completely black, but will show a noise pattern. The camera then subtracts this from the image to improve the quality of the result. You can typically disable this in the settings, but the result will be noisier of course. Some advanced users do this by hand and do their own processing."
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cyuvhc | How does screen auto-rotate work on the iPads aboard the International Space Station? | Technology | explainlikeimfive | {
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"In a pure zero-G environment, auto-rotate wouldn't work, due to the iPad's accelerometers reading a constant 0. There \\*might\\* be enough microgravity in the ISS to make it work, but it wouldn't surprise me if it didn't. In Xcode, one of the first screens you're presented with when creating a new iOS app has the rotation settings right front and center. Personally I always deselect Landscape or portrait modes immediately, unless my app specifically needs rotation. I'd imagine the highly-specific apps they probably use up there are the same way. & #x200B; edit: additional thoughts I feel like an idiot for not thinking about this before, since I've actually written iOS apps that take advantage of it, but the iPad has a **gyroscope** in it as well as the accelerometers. The rotation functions are coming from the gyroscope components, not the accelerometer. [ URL_0 ]( URL_0 ) < -- the fun bits"
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cyxb4z | does it matter if i power off a device from its power source or use the switch button (devices with on/off switches, not TV) | Technology | explainlikeimfive | {
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"If a device has a power switch, best to use it. Some cases it doesn't matter at all, but other times it does. Sometimes there is a clock or configuration data that will need to be reset after a hard power off, and even if you don't do this manually, it can make the next boot take longer. For high current draw devices, always use the power switch if you can, only pull the plug on something like a hair dryer or vacuum cleaner if it's on fire or fallen into water or something. The reason for this is that the switch inside the device is designed to break large currents, whereas if you just unplug it without turning it off, there will be an arc that can damage your power outlet. Single instance shouldn't matter too much, but over time you'll get a poor or no connection when you plug something into that outlet.",
"Some devices use a fan to cool off hot parts. When you turn it off with a switch, the fan stays on for a little while to cool off the hot part. If you just pull the plug, the fan won't be able to cool off the hot part and it could burn out. (I'm referring specifically to projectors, but it can apply to other electronics)",
"The simple answer is to use the switch if it has one before unplugging. The slightly longer answer is that most electronics have been designed to deal with power failure so it is unlikely that your average home electronic device would suffer any damage from a plug pull but it could happen. Lots of things also have basic batteries in them to keep a clock or simple settings so a quick power loss doesn’t put you into blinking clock hell; that’s where the power switch kills most of the power but passive modes (standby) will still be on to improve startup, boot, and passive patching times.",
"If the device's on off switch is a big meaty clicky switch that is switching mains, then no there's no functional difference. If on the other hand it's like a power switch on the back of a NAS say, that isn't a straight up pull the plug power switch. What that'll do is tell the device to power down, which might involve various housekeeping tasks, stopping hard drives, all that kinda thing before finally switching off. So the answer, as is often the way with this kinda thing is \"It depends.\" Some devices, even devices that have soft off switches (which is what that NAS example is) won't mind being pulled from the wall direct. A TV is a decent example, most TVs won't care if you just unplug them. If you did that to a PC or NAS while it was writing files for example, then you'd cause data loss. If nothing was happening and the machine was idle it'd (probably) do no harm."
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cyxsw6 | - How are color assignments made for remastered movies that were originally in black and white? | Is it by choice or is there are way to decipher color based on the tone of black and white? | Technology | explainlikeimfive | {
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"Sometimes there are surviving costumes or props or even sets that you can refer to to see what the original color was. Sometimes there are some color photos from the set, even though the film ended up in B & W. And sometimes it's an educated guess based partly on how dark or light an area appears in the B & W film, partly on what colors were fashionable at the time, etc. And sometimes they really just have to guess. And for things like skin tones, or settings, it's easy to figure out. Like if part of the film happens in a desert, you can pretty much guess what color the sand dunes would have been, or if it's a scene filled with working-class people walking home from work (as an example) we know that the average worker wouldn't be wearing fancy clothes to go work in a shipyard or a butcher shop, so we'd assume that their clothes are very basic colors. There are also loads of historical documents we can refer to, which can take a lot of time, but you can find really great info about clothing, building materials, popular paint colors, all kinds of good stuff.",
"One of the most difficult things about this process with B & W movies is that set and costume colors were not always chosen based on realistic colors. That is, they were chosen based on how they looked on the B & W film of the time. So, something that they wanted to look a certain way on film might be bright pink, even though that item might not be pink in real life. This forces a lot of artistic choices during the restoration/remaster.",
"Not entirely related to the original question, but kind of a cool story so I'll put it here anyway. There was a popular sitcom in England called *Are You Being Served* which ran through the '70s and into the early '80s. Color TV was well established by that time so the series was entirely in color, with one exception. The pilot episode had been recorded on color tape but when time came to archive it they transfered it to black and white film. This was done by pointing a film camera at a monitor and letting the color episode play while the black and white camera filmed it. For a long time only this black and white version of the pilot was available, until someone got an idea. The film took an image of the color monitor, including which phosphors were illuminated and when. By mapping the correct phosphors to red, green, and blue they were able to restore the episode's original color! [Here]( URL_0 ) is a brief video outlining the process, it probably explains it better than I can.",
"I worked for American Film Technologies in the early 90s and contributed to color versions of the Sands of Iwo Jima, Miracle of the Bells, Casablanca, and some others. If anyone is sufficiently interested I can lay out the production process tomorrow, when I am in front of a real keyboard.",
"Look up Peter Jackson explain how he did it in \"They shall not grow old.\" They go into great depth about how it was done in that particular case.",
"Each shade in a black and white image does not correspond perfectly to a particular colour. The black and white image is the \"luminance\" value of a colour. For the sake of simplicity, you can get the lumiance by adding up the red, green and blue levels of a colour. This means you can have two colours with the same luminance value that will appear the same shade on a black and white TV. For example, you could find a shade of green paint that produces a certain grey colour on a TV, but if you had a shade of grey paint with the same luminance, you'd be unable to distinguish it from the green. When you're dealing with monochromatic images, you've lost a lot of the colour information so the only way to get it back is with reference and artistic interpretation.",
"This answer describes one technique, but it doesn't apply to all B & W films. In some cases, if parts of the original footage were shot on colour film, and later converted to black and white, it's possible to restore the original colour from just the black and white footage. The monochrome conversion, when done with the older analogue filters, makes the footage noisier. This added noise unintentionally allows a remastering engineer to work out what the original colours were, and in some cases software can automatically restore them. This is more likely to apply to films and tv shows that were made when colour film was slowly becoming more popular, as not every studio or production house could handle colour footage - so it was converted to B & W. A real world example of this technique is the restoration of lost episodes of BBC's Dad's Army - when the original masters and copies were lost, black and white tapes found in someone's garage were processed and converted to colour.",
"An artists colors it in, with the help of computer software. Peacheserratica does an excellent job explaining how the artists pick the colors they pick, but they could do whatever they wanted, if they weren't trying to be accurate.",
"I'm gonna link you 2 very good explanation as to how it's done. First method is manually painstakingly coloring them in photoshop by researching the props, materials and weather Peter Jackson explained it in a video with visualisation on how he made it. They also needed to match the frame rate to match the modern standards to 24 fps as old cameras were shot as low as 16 fps. URL_2 The second method is more recent, and it has to do with AI, aka. Deep learning algorithms. Facebook has a algorithms called decrappify and there's another algorithm called deoldify Here's a paper on how DeOldify works URL_0 Here's a video demonstration of DeOldify URL_1 MOD, don't be dumb. Let people learn about these stuff. No harm will happen.",
"Many films have still photographs of the set in color and props surviving to the day. Sometimes they just do some digging and research and approximate. surprisingly artificial intelligence neural networks have been able to predict and fill in and colorized photos with extreme accuracy, and is able to correctly predict the color and hue of a garment of clothing from a black and white photograph 98% of the time",
"What about r/ColorizedHistory? Is this done the same way?",
"They try to match a known color and the rest fall into place. However they don’t always get it right. URL_0",
"Interesting discussion. But I have never liked old black and white film/pictures colorized retroactively. The hand tinting at the time, sure. But colorizing since it became a big thing in the 1980s? No.",
"Guess, evidence, and the way colours show up in YUV code. Black and white is the Y, and the RGB to YUV conversion is Y = 0.299R + 0.587G + 0.114B. This helps with fringe cases. For instance, if you see the scene has the most light it could and a car is 0.114, it can be grey, dark green, medium red, pure blue, or any combination.",
"I just saw an I Love Lucy special event in the theater that spent a lot of time explaining this. You should watch it. Old props, photos from magazines, collectors, and then in the end they changed some colors anyway because filming for B & W is so different than filming for color. For example, in one scene it turned out Ethel’s dress was much bolder and more visually appealing in reality than Lucy’s so they changed it while colorizing because they knew that would have never have been the choice if it were filmed in color."
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cz3dkj | How does x-ray work? | Technology | explainlikeimfive | {
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"Some light is really small and can pass through the gaps inbetween the molecules that make up the meaty parts of your body, but not the bones. The bones are much denser so they block the x-rays. If you shine a bunch of x-rays at the body, you can see a \"shadow\" where the bones are."
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cz3g9y | why are you able to turn on devices after they have supposedly ran out of charge? | Technology | explainlikeimfive | {
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"text": [
"Using a cell phone as an example, 0% isn’t actually 0. Batteries have operating levels and a fully drained battery is garbage. Usually they get down very low and cut off until recharged to protect the cell. With that in mind, phones shut off at 0-5% displayed battery, but the battery still has charge in it. This is especially obvious when you have a phone that cuts off at 5% and shuts down to preserve data/whatever. The battery doesn’t have enough juice to keep powering the phone, but still has a little sippy cup of power on hand.",
"Noone mentioned yet that your clock would literally reset to 0 if it drained (until your system has data connection or you set it up again)"
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cz3mgq | How do touchscreens work? | Technology | explainlikeimfive | {
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"text": [
"there are two (main) types of touchscreens: resistive and capacitive. Both have a grid under the glass and they sense where your finger on the glass is. Resistive: When touched, the screen bends a little bit in the point where you touched it. It changes resistance of the grid point beneath it and software of some kind then evaluates where the resistance of the grid changed Capacitive: It's little harder to explain but in a nutshell the screen is one side of a capacitor and your finger is the other side of a capacitor, by moving closer to the display you change capacity of this capacitor and when close enough it's evaluated as a touch",
"Touchscreens work thanks to small electrical currents flowing from it through your fingers. Human skin is actually a very good conductor for electricity. This also explains why you can't use a touchscreen qith normal gloves, because they are often made from materials that insulate."
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cz6fac | How do police radar/laser speedometers work while the police car is already in motion? | Technology | explainlikeimfive | {
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"They subtract the speed the police car is driving at from the speed that they measure with the radar speedometer, which gives them the speed the other car is going. Edit: If the other car is driving the opposite direction than the police car, they subtract their speed to get the other vehicle's speed. If the other car is in the same lane in front of the police car, they add the measured speed to their own speed to get the other vehicle's speed.",
"Depends on the unit. Some units take an input from the cruiser's onboard speedometer and subtract that from the speed calculated by doppler shift. Other units have a second radar head that measures the speed of the cruiser by the doppler shift of the signal reflected from the ground. I believe I have even seen units that have high-update-rate GPS units onboard that track the cruisers speed as well.",
"Modern laser system is plugged into the police cars speed sensor so it remains calibrated all the time. Gives real speed of oncoming traffic.",
"Follow up question: I saw what looked like a cop calibrating his radar? He was hitting what looked like a tuning fork and holding it in front of the radar. What was he doing?"
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cz8f09 | How do videogame textures work? | I understand that a mesh is the shape of the "object" and the texture is applied on that mesh. When viewing texture files they seem to be the images of the texture but jumbled up. How is the texture file applied to the mesh and how is it decided which part of that texture image goes where? | Technology | explainlikeimfive | {
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"You know how before you recycle a cardboard box, you have to flatten it out? Same idea in a 3d mesh; you take all of the faces and lay them out on a flat surface where the textures get added on. The difference being that with a box, the goal is to get them flat, but with a 3d mesh, the goal is to get everything in a certain area, so with the box you probably don't cut one side off and put it over by an unrelated side where you have some room on a 2d plane. In the 3d meshes I've made, you didn't *have* to keep everything connected (ex: if you were modeling a human skin texture for a body mesh, you could put both arms in the lower-lefthand corner of the file, then the backs of those next to them until you got to the lower-right, without regard for where it would normally go if you tried to wrap it back together (the program would mark where each part of the 3d model got its coloration/texture from and pull from those coordinates of the image file), so in a way it's not *quite* a stretchy piece of plastic, but more of a cut-out sheet of stretchy plastic that you can glue to your surface to add coloration to it in more detail than just choosing 1 color for the whole bit.",
"There's a thing called UV coordinates. Each triangle on the mesh has coordinates associated with each point. These coordinates correspond to a point on the texture, and all 3 together determine which part of the texture is applied to that triangle."
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cz9jc1 | Why Are HDMI Speeds > 1gbps But Internet Streaming 4k is < 40mbps? | Technology | explainlikeimfive | {
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"HDMI carries raw signal, e.g. exact color for each pixel for every frame. All the screen has to do is show it. 1920W×1080H×24fps×16 bits per pixel = 800 million bits per second = 0.8 Gbps [edit: better informed people below say it will be even more bandwidth] Streaming is compressed signal, e.g. \"this area will stay this color for X seconds\", or \"this whole section will move down at the rate of 100 pixels per second\". You need a computer or at least a specialized chip to decompress into raw signal.",
"Compression. Raw video requires a huge amount of storage space and it is unnecessary for 99.9% of applications, and would be downright impractical for streaming or even playback, as the end device needs to be capable of receiving and processing that data in real time. 4k video by itself will be about 880 Mbits/s raw for 24FPS.",
"The short and sweet answer is the Hdmi video signal is not as compressed. Video over tcp/ip makes heavy use of compression. This makes it use less bandwidrh but inroduces artifacts into the video. It also means it needs to be decoded at the viewing end, which takes cpu cycles and requires some sort of computer in the device displaying the video."
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czer4e | How do they make those music videos where the video seems slow motion but the singer keeps in sync with the song? | Technology | explainlikeimfive | {
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"text": [
"Usually on set for the video, they play a sped up version of the song and the singer lip syncs to it so it in post they can slow it down to normal speed and it looks like it's in slow motion."
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czfhg5 | Why is it a really bad idea to put dead or mostly dead batteries in a device with fully charged batteries? | Technology | explainlikeimfive | {
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"text": [
"As battery charge is used up, resistance increases. Fresh batteries with low resistance, pushing voltage through dead batteries with high resistance may cause it to heat up and leak. It could also cause a short in the battery, which would rapidly discharge the battery and possibly damage the device. The best outcome is just reduced power. Additionally: You shouldn't mix battery types, such as LiPo and Alkaline. The chemistry and voltage differ and may cause problems. You shouldn't mix brands. The overall chemistry and voltage may differ enough to be a problem.",
"Say there’s two dead batteries. If you replace them both, they have a life span of, oh, 1 hour (for simplicity). If you only replace one, that one battery does not last for half the time, as you’d expect, but even less. 20 minutes maybe. Essentially, the dead battery acts like a dead weight that the fresh battery has to carry around too, increasing the load (electrically speaking) and shortening its life.",
"In a worst-case-scenario, the live battery will force-feed electricity into the dead battery, in the opposite direction that electricity would normally flow through the battery. This can result in the battery popping and spraying corrosive stuff everywhere, or start a fire."
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czg6qg | The speed limits vary from 10-70 mph, with the highest speeds only being found on the interstate. My SUV can go up to 160mph. What is the point in allowing cars to go that fast if it’s illegal to actually attempt? Why aren’t general cars just capped to 80 mph? Would it not save money? | Technology | explainlikeimfive | {
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"eyy5two"
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"There are some highways in Europe without speed limits, or with much higher limits. German Autobahn comes to mind. You could race cars on private tracks. Some people do enjoy breaking speed limits. Speed limit could be indication of engine power. If empty car can do 160mph, then it should be able to tow a boat at 60mph."
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czgpf3 | Why will a gif play normally the first time but may stop and need to load when it repeats? | I often see gifs on Reddit and then go to show my wife only to have the gif get stuck loading on the 2nd play through. Shouldn't the gif be completely loaded after the first time it plays all the way through? This happens on mobile and PC | Technology | explainlikeimfive | {
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"eyydlzf"
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"text": [
"When you create a gif in Photoshop or similar programs, you can determine if the gif should loop once, twice or over and over. The other possibility would be the browser or OS you are using as certain preferences could limit the times a gif would loop."
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czgvu2 | Why are solar panels made of blue coloured materials, not black, even though Black materials tend to absorb more heat? | Technology | explainlikeimfive | {
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"text": [
"Basically because of the materials. There are both blue and black solar panels, but blue ones are cheaper to make and easier (with lower carbon footprint) because they are what’s called “polycrystalline silicon” where the silicon is heated and poured, but the molecules aren’t perfectly aligned and refract light a certain way (making it blue) The black is “mono-crystalline” where the molecules are aligned a specific way, but this is hugely energy intensive to produce, and more expensive.",
"Solar panels in two types: passive thermal and photovoltaic. Passive thermal run a fluid (usually water) through a bunch of pipes in a panel. They are indeed black so as to absorb as much light as possible and convert it to heat. That heat then gets carried away by the fluid to be used elsewhere. This can be used to heat a home or provide large amounts of moderate heat for industrial processes but is not a suitable source of electrical power. The bluish panels you refer to are photovoltaic panels. They use the photons of light to kick electrons free from a silicon crystal based material* to produce electricity. The silicon is in a pretty thin layer and unfortunately can only use a portion of the total spectrum of light hitting it. The material can be tweaked a bit to work at slightly different light frequencies but for technical reasons can never use all of it. Pure silicon is a \"metalloid\" and has a dark blue-gray hue to it. What you see in the panel is almost pure silicon in very thin layers on top of wires to conduct the current away and typically sandwiched in glass to protect it from the elements. * a proper explanation of how silicon produces a photovoltaic effect gets into discussion of band gaps of semiconductors which is beyond a ELI5",
"Solar panes do not work by absorbing light and getting warm but by absorbing light byt the photovoltaic defect and create electricity directly. They will be heated up but that in not something you what because the efficiency then drops. The difference between blue and black solar panes was explained by bertahandbasket. The black produce more power but is more expensive to manufacture. So what is used depend on the application. A satellite it is power compared weight/size that in important but for grid power production it is power compared to cost that it most important. There are Solar thermal energy where it is the heat from the sun that is used. The do not function like solar panels. To produce energy the directly on indirectly boil water and produce electricity with a steam turbine. One variant that is promising is Solar power tower where heating up liquid salt with a field of mirror and use it to store heat. You can them boil water around the clock and produce the electricity all the time."
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czl8hg | a software application I use for work says it is Version 11.0.5.7.1378212. Why would the version # have such a high degree of precision? | Technology | explainlikeimfive | {
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"In software development, we like to keep track of *every* code change. We do this for the same reason scientists keep record of all their notes and observations, even if they're incorrect. It's important to be able to go back and see what's working and what is not. It's also important to keep everyone working and using the same version, especially if you have a lot of developers working on one project and a lot of customers using it. Software versioning tends to follow the same conventions (in my experience), something like this: [Major Version].[Minor Version].[Patch].[Revision (optional)] In your example, the version 11.0.5.7 could mean (totally extrapolating): * Main version **11** * Minor version **0** (could be an alpha/beta or maybe they just start their minor versioning at 0) * Patch **5** * Revision/Hotfix **7** The last number, 1378212, could be many things. My first impression is that it is a ***build number***. A build number is just a number that increments every time the source code changes and a new 'build' is made. A build is literally just a tangible instance of a program that has been compiled and can be used/tested. So, in this case this might be the 1378212 build of this particular piece of software since they started making builds. This number is important because it gives you an exact number (independent of the version) that you can reference if needed. If two programmers are working on the same code, and they both create builds, each of their build numbers will be different even if their versions are the same.",
"The version is likely just 11 .0 .5 .7 and the 1378212 is likely the build number of the code. The 11 .0 .5 .7 is a version set by human so you can track changes in groups. The longer 1378212 is automatic It is a number that is generate when you commit the code to the code management system increased for each change or a build number that increased each time you compile part or the while software. So it is there to know exactly what code was used So if there is a bug in testing or when developed they can know exactly what code was used. When the developers write changes for 11 .0 .5 .8 or what is will be there is a lot of changes in small steps between when a human determine that a new version number is appropriate. The human part of the version number likely only changes when it is released to the users away from the developers. So the high number is there so you can know exactly what code was used and as it is automatic it is not reason to not include it because it might be relevant some times.",
"Usually version numbers are based on the size/significance of the patch, so the first number is the major version, the second is a minor patch, the third is a maintenance version, fourth is a build, etc., where each section changes less overall than the one above.",
"People who make software have a hell of a time working out what’s causing the problem when you say something isn’t working. Modern software has many, many changes made in a very short time (what I’m working on has had something like thirty changes today alone and we’re a small team). Most of these changes are kept private and are kept only as a “diary” of how things changed to get to where we are now. That “diary” might include things where one developer changed stuff, and another changed it back because they knew something the first one didn’t. Some changes are outright rejected; they’re ignored but remain in the “diary” as part of the history so things can be checked in the future when someone says “oh, I did that in July but it was rejected”. That way, we can go back and look at whether it *was* useful after all. At some point someone has to decide that something is ready to be made public. But we don’t all down tools and wait while that happens; instead, they look at the diary and decide how everything was yesterday morning is good enough. So they pick that entry in the diary; instead of being labelled with Tuesday April 26th, 9:04am, it’s got a number that (usually) doesn’t mean very much except that it’s different to every other label in the diary. That then eventually ends up being used by you, but in the meantime we make many, many more changes. Then you discover that sometimes when you press a certain button, it stops working. We can’t work out *why* that happens unless we try to make it happen on our system too. If we try it with the latest version, things may have changed so it doesn’t happen any more (we may even have taken that button out). So we kind of “look up” your version in the diary, get our computer to make that version, and try to recreate your issue. If we can, then we can check everything that’s changed since your version and see whether what we’ve done in the meantime has fixed it, or whether it still needs fixing. The long number helps us get the *exact* entry in the diary that matches what’s on your computer, rather than one of the thirty or more that we’re done that day, or the hundreds between 1.1.3 and 1.1.4... (To software developers out there, I know I’ve glossed over a lot and bug hunting isn’t really as smooth as that but hey, ELI5)"
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czm5lf | How come we don’t have any small underwater rebreathers that can extract oxygen from water like gills? | Technology | explainlikeimfive | {
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"The human body requires far more oxygen than a small, man-portable device can extract from the water. Our evolutionary ancestors have been living on land for hundreds of millions of years and our bodies have in that time adapted to the environment.",
"URL_0 It is currently unproven technology. What is proven however are oxygen tanks and rebreathers. Both of these are proven to work and cheaper. So we use these.",
"You might think this would be possible since fish can do it. However, fish have their whole bodies adapted for these conditions (extracting low concentrations of dissolved oxygen from water). We don't and this makes it a lot harder. Just consider how big our lungs need to be to extract enough oxygen from the air to serve our needs as warm-blooded creatures with much faster metabolisms than fish. Then add to this the fact that air has a lot more oxygen in it than is dissolved in water. Then finally consider that whereas fish's gills exchange oxygen directly between water and the bloodstream, an artificial gill would have to produce gaseous oxygen, only some of which would be absorbed in the lungs (since oxygen absorption in our lungs has its own inefficiency). That should give you some idea of how large an artificial gill would need to be to enable us to breathe underwater.",
"There is not that much oxygen dissolved in the water. You'd have to process a lot of water to get enough oxygen for a big mammal like a human, that's why porpoise breathe air just like we do. Gills don't get at the molecular oxygen (water is mostly oxygen by weight) because that takes a huge amount of energy to separate."
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czm82g | Why do some electronics connect to cell phone via bluetooth, while others create a wifi network that you then have to connect your phone to | for example, my dashcam and my OBDII reader both create a wifi network and I have to then go to my phone's setting and choose that wifi network. Is there some benefit to connecting via wifi over bluetooth? | Technology | explainlikeimfive | {
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"text": [
"Wifi is around 10X faster than even the latest bluetooth connections. & #x200B; Bluetooth is an incredibly secure device-device link but sacrifices speed because of this.",
"I may be wrong but I don't think Bluetooth has the capabilities to move large chunks of data like wifi can."
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czmevk | How does the device that make things vibrate work? Is it the same thing but bigger/smaller for cellphones, game controllers, dildos, etc? | Technology | explainlikeimfive | {
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"text": [
"Usually, a motor with an unbalanced weight attached to it is used to make vibrations. As the motor spins, it swings the weight around which causes vibrations in the motor/shaft/anything else they're attached to. Higher frequency vibrations may be made by a speaker, which is just a magnet and a coil of wire, and higher still by an ultrasonic transducer.",
"It is usually variants of the same design but of different sizes. The simplest way to make something vibrate is to have a motor spin an unbalanced weight. Basically a half cylinder shaped weight is attached to the motor in the center of the cylinder and for each rotation it will push the motor back and forth. Anything that is attached to the motor will also vibrate back and forth the same way.",
"Most vibrating devices vibrate through rotors with a weight attached to them. The weight isn't equal across the entire rotor. When the rotor spins the weight, an uneven force is applied to the object. Say when the weight reaches \"left\" to your relative position, the force of the weight tries to drag the entire object to the left with it, then to the right as it continues spinning, then back to the left. As far as I know, this is pretty much the only way most devices create vibration."
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czn354 | What does HTTPS keep secret, and what does it not? | Technology | explainlikeimfive | {
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"Think of it as sending a postcard vs sending a letter. With http, anyone can see your entire message. With https, people will see the To and From fields, but they can't open it to view the contents.",
"* https encrypts the information you send from your browser to a website and the website will agree to encrypt what it sends back. * But in order to get to any website without knowing the website's IP address, you need to make a DNS request. * Unless you specific a different DNS, you ISP will either act as the DNS or will forward your request to another DNS. * In either of those cases, they will see the name of the website you're trying to get the IP address for.",
"Only the domain name is visible in an HTTPS request. The path and parameters (Everything to the right of the domain name) are encrypted. The only way to hide all traffic is to use something like a VPN or encrypted proxy. & #x200B; Technically, it is possible for your ISP to snoop in on your traffic using MITM (Man In The Middle) attacks, since they handle **all** of your traffic. But the likelihood of them doing that is slim, probably only likely in totalitarian governments like North Korea and China (Not quite totalitarian anymore, but still very strict)."
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czt8bc | How do batteries work and how do they run out of juice? | Technology | explainlikeimfive | {
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"text": [
"In a battery, a chemical reaction takes place that puts electrons on one electrode and sucks them out of the other one. When too many electrons pile up on one side or are missing from the other, the repulsion of electrons to electrons and protons to protons stops the reaction. This is the state of a charged battery that is not currently doing anything useful. When you allow the electrons to flow from one terminal to the other by connecting your electronics to them, the chemical reaction can start again. As the reaction progresses, the chemicals inside of the battery slowly run out. Eventually, there aren't enough chemicals left to react at a meaningful speed and the battery is considered dead. In rechargeable batteries, the reaction is easily reversed simply by forcing electricity through the battery in the opposite direction."
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czvb3j | why is my screen bright even with a pure, pitch black image being shown fullscreen? | So I use this video to sleep, a rain sound effect with a black screen to avoid messing up with light. However, even though it's pitch black and literally displaying nothing, the screen is still bright has hecc and brightens up my entire room. Why is it like that? Shouldn't black be, well, black? No color, no light? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The screen (unless it is OLED) has a backlight used to shine through the colored pixels. If there was no backlight it would be black all of the time."
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d00265 | What is the process of emulating a console exclusive game, such as Bloodborne, to a PC playable game? | Technology | explainlikeimfive | {
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"text": [
"There's two parts to this: First: Any computer program, whether it's a game or a \"regular program\" (and consoles are just specialized computers), is eventually just a series of \"commands\" for your processor. We call those instructions. There's quite a number of different processor kinds with different instruction sets. Consoles used to have very specialized processors which very specific instructions that come in handy for running games. Today (I think) most consoles use the amd64 instruction set, which is the same you have in your laptop/desktop PC/Mac. Don't get confused by the name, Intel and AMD processors both work with the amd64 instruction set. amd64 is the name for the instruction set that modern desktop processors understand. If you want to run a program that is written for one instruction set on a processor that has a different instruction set (for instance, Nintendo Switch uses the ARM instrcution set), then that program will use some instructions your CPU doesn't understand. So you have to \"translate\" those instructions into instructions that your CPU does understand. This is usually not a one for one translation. Second: Any program that is not an Operating System (OS) is expecting that there is an OS \"underneath\" where it runs on. The OS is exposing certain functionality to the program (for instance, the program can tell the OS \"give me more memory\", and the OS will hand it out). Consoles have very specialised OSes. So you also need to emulate the behaviour of the console's OS and expose the same functions. So, basically, emulation is making your PC behave in such a way that Bloodborne thinks it's running on a PS4 when it actually isn't. All this emulation comes at an overhead, so emulated software will usually run slower than on the hardware / OS it was meant to run on."
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d0485x | How phishers get password information. | I recently got a phishing email that contained a portion of an old password that I used to use and I was wondering how they managed to get it. | Technology | explainlikeimfive | {
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"text": [
"Probably they get any leaked database and they create their own table with a list of emails and passwords and spam every email from that list. For example if the leak was a database of facebook, they send you to change the password of PayPal and use your password they found from the facebook leak, because there is a huge probability that you use the same password on different social networks/websites. That's the basic idea behind it."
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d0894m | Given that currents can throw a boat off course, how did submarine navigators know precisely where they were while submerged pre-GPS? | Technology | explainlikeimfive | {
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"Compass bearings, knowledge of the currents, and dead reckoning. Prior to nuclear power submarines spent most of their time on the surface because their batteries had very limited endurance. So they could regularly take star sightings and utilize radio navigation beacons. Modern submarines have very advanced inertial navigation systems, since GPS doesn't work underwater.",
"There were quite a few different ways. Besides using the periscope to identify fixed points for triangulation (such as a light house, buoys, navigational markers, etc) which is called Pilotage, they used their sonar, radio, a compass, and the stars for navigation. The probable answer to your thought behind your question is Radio Navigation, such as LORAN. Long story short, radio waves travel just fine under quite a bit of water (and their radio transceivers were extendable if they got too deep) and without much effort it is easy to see \"how\" you received the radio signal (with respect to phasing or timing). Some even used an audible tone you could hear so you know if you are on path or not (single tone when on target, multi-tone if not). Radio location in some forms is still used today for aircraft instrument-assisted landing among other things. It's a technology developed I believe in the early 1900's. If I'm not wrong, it was developed by Germany for use in navigation for the Zeppelin fleet which would put it around 1910, so it was a well-established technology by the time submarines came around.",
"GPS isn't really a submarine technology, it doesn't work under water. Submarines have very accurate inertial navigation systems, which measure the movement of the sub. It doesn't matter if the motion is from the engines or the current, the INS measures it the same way. Actually it measures the sum of the motors and the current, but that's what you need to know where you are."
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d08ycv | Why did fuel cell technology seemingly disappear as a possible alternative to gas/petrol in vehicles? | Technology | explainlikeimfive | {
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"Hydrogen has a *lot* of problems, most of which stem from the fact that as the smallest and lightest element, it is very difficult to effectively contain and transport. It simply leaks out of *everything*. Not to mention the fact that it's under pressure and explosive. That means you can't have the kind of production and distribution network that oil and gas have: no continent-long pipelines or large tractor-trailer tanks delivering hydrogen to fueling stations. Instead, each individual station would have to have its own production facilities to produce hydrogen more or less as needed. That's a huge added expense for fuel stations, who usually want nothing to do with *making* stuff and only want to buy fuel in bulk and then sell it to consumers. Also, hydrogen production is costly in terms of energy. Sure, water is everywhere but breaking it apart to get the hydrogen is hard. It's exactly *because* of that strong bond that you get so much energy *out* of combining hydrogen and oxygen, and you must by the laws of thermodynamics put more energy *in* than what you get *out* to reverse that reaction. That's all well and good for plants and other natural processes because they generally go about it slowly. There's lots of sunlight available for plants to do just a little bit at a time, over a very long time. But that slow, inefficient process can't keep up with our needs. Instead, we have to pump a *lot* of energy into a *lot* of water all at once to get a *lot* of hydrogen quickly. That creates its own energy production and distribution problem. In any case, the main benefit of the hydrogen fuel cells was that they powered an electric generator, and *that* provided power to electric motors. This can be very efficient because you can keep the engine running at its most efficient speed and charge a battery when you need less power to move and drain the battery when you need more power to move. Except...that's what gas-electric hybrids do. So, the efficiency of gas-electric hybrid cars is rapidly approaching that of a hydrogen fuel cell, which somewhat negates the need for them. At the same time, battery technology is improving drastically so fully-electric cars are totally viable and more affordable, also negating the need for hydrogen fuel cells. And both of those alternatives use the production and distribution networks already in place in just about every country.",
"Hydrogen infrastructure is far more difficult to create than charging points both in terms of expense and uncertainty.",
"Hydrogen fuel cells are a type of chemical battery. They produce electricity by separating hydrogen and oxygen with a membrane. When allowing them to come together that membrane collects electrical energy from the reaction. You can allow the product of the reaction (water) to escape via exhaust, and refill the fuel cell with hydrogen and oxygen when it runs out (refillable), or you can collect the water and use electricity to re-separate it into the gases to be reused (rechargable battery). The first problem with hydrogen/oxygen batteries is their energy density. A fuel cell with the same electrical specs as a lithium ion battery, for example, weighs many times more. That means a vehicle powered by fuel cells will weigh more and therefore require more electricity to go the same distance as one powered by lighter, more efficient batteries. If the electricity comes from fossil fuels, the fuel cell has a larger carbon footprint per distance traveled. IIRC fuel cell vehicles powered by the grid had similar or larger carbon footprints per mile/km than hybrid vehicles. The second problem is the storage of hydrogen gas. Hydrogen is the smallest and lightest atom. It's so small that it can easily escape any container by passing directly through the material of the walls. That makes it impossible to store a fuel cell in a \"charged\" state. The third problem is safety. Hydrogen and oxygen each react violently with each other and practically everything else. Keeping them next to each other, separated by a thin membrane, in a collision prone vehicle, is not a great idea."
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d0copl | How do IP addresses work? | What is one and how do they work? | Technology | explainlikeimfive | {
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"Ip addresses point to devices on a network like addresses point to houses on a street. Obviously it gets deeper than that but its a large subject, came you be more specific on what aspect youre curious about?"
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d0d3zk | How do licences on software with no internet know when they will expire even if you change the clock date? | Technology | explainlikeimfive | {
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"When I dabbled in programming my application wrote a registry entry containing the date that the software was installed and last used. When the program started it checked the system date and time and if it was before the installed or/and last used date then it assumed you were trying to beat the expiry and would not run until you got a licence."
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d0egcw | Why do electric cars not have solar panels on their roofs to recharge the battery when parked? | Technology | explainlikeimfive | {
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"It's a size vs efficiency issue. The roof is not large enough to do an adequate amount of charging in many situations. However, the Prius added an option a few years ago that you can get a solar panel on the roof that will allow the A/C to run on low when the interior temperature gets above a certain threshold. It doesn't make it 'cold' in the car, but it makes it 'tolerable' when you get in, and you don't have the initial blast of warm air when you get in and start it up.",
"The numbers wouldn't work out for it to make much sense. Roughly speaking, it would give less than 1% charge per hour. And then the car would have to carry all that additional weight which offsets this. So the electrical portion doesn't make sense. The financial/cost numbers are probably even worse. Solar power for homes probably start to make sense (costwise) in the 5kW and above range (10kW if you're conservative) to justify the cost of the electronics involved. (with a payback in many years!) At the 1kW range (the limit for the size of most cars very aggressively speaking), the payback just isn't there.",
"Let's crunch some numbers! Let's assume that the roof of a car is roughly 1 square meter (\\~11sqft). A solar panel can generate, theoretically 1000W per square meter of surface (per hour). However, the efficiency of even the best solar panels top out at around 20%, which then means your output ends up around 200W per square meter (per hour) under ideal conditions (remember that, we'll come back to that). So, theoretically for a 24 hour day, if the sun shines for 12 hours of that day, you'll have a total output of 2400Wh, or 2.4kWh. Now, let's look at the most popular electrical car, the Tesla. With the lower end models having a battery of 50kWh you would need 250 hours of continuous charging to fill up your battery. More than twenty days, as you'll only be charging for 12 hours a day. But wait, there is more! Remember those \"ideal conditions\" I mentioned? Yes, the sun doesn't really shine for 12 hours a day, nor does the sun shine from the ideal angle onto the solar panels (which is why some solar panels are motorized and track the sun), nor is the weather always sunny, the solar panels aren't always clean, etc etc. There are so many factors that impact how much electricity you're actually generating. In reality you'll end up generating far less energy than you need to power your car, by far. It may be enough to power low powered devices, like the aforementioned Prius AC unit, but not to make any significant impact on your battery. Even those that advocate for installing solar panels at home to charge up your electrical car advocate for at least a 2500W system, meaning more than ten times the surface area I mentioned to begin with. And even that is calculated based on only 4-5 full charges a month, not a full charge every day.",
"A better option is just to have all of the charging stations be solar powered. 100% renewable energy is the goal",
"Pretty new, but they exist or will soon: URL_1 URL_2 URL_0 Right now though, even the best of these only manage to generate enough charge to power the car for 35km of range over the course of a cloudless day park in direct sunlight (basically enough for a 15-20 min drive). For some people with the right lifestyle it may be enough that you rarely would have to plug into a charger, but they are probably a **very** small minority.",
"Root issue is this: 1 horsepower = 746 watts. Typical car 180 horsepower = 130,000 watts. There is *so much energy* packed into the chemical bonds of gasoline, and we're just not there with battery technology and solar panels. 200 watts per panel, pfft."
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d0folj | CPU cache. | Technology | explainlikeimfive | {
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"Imagine you're in an office, and there's a bunch of files in the basement that you regularly need to bring up to your desk. Now because you're lazy and don't want to run downstairs all the time, you copy the files each time before you bring them back downstairs, and store them in a file cabinet inside your office. Then, if you ever need to read that file again, you can just grab it from the cabinet. Once it's full, you throw the oldest ones away. That's basically how a CPU cache operates. The cache trades some extra time when reading something from the memory (it has to copy stuff each time), but frequently needed data can be accessed nearly instantly. They usually have numbers such as L0, L1 up to L3 - that tells you how far away from the core they are. L0 is the smallest, but also the fastest, whereas L3 is very large, but slightly slower.",
"CPUs perform a lot of instructions very very quickly. So quickly that on a high-end modern CPU, in the time it takes to go through a single CPU cycle, an object moving at the speed of light could only travel a few inches. Each of those instructions works with some stored values in memory, for example \"add number at memory location *x* to number at memory location *y* eighty-one times.\" The CPU sends a signal to RAM to get value then sends a signal to RAM to get value y, performs the addition, and sends a signal to RAM storing the new result at y. A good modern CPU would be so fast at actually doing the addition that 99% of the time would be spent waiting for those signals to travel back and forth and for the right value to be selected from the huge multi-gigabyte piece of RAM. To speed things up, CPU manufacturers add a tiny amount of ultra-efficient RAM that lives right next door to the CPU itself, which can be accessed much much faster, and this is called the CPU cache. You can only have a tiny amount of it in comparison to RAM, because it has to occupy a tiny amount of space right on the CPU die and is manufactured to be ultra-efficient which is difficult and expensive in comparison. But even having a tiny amount makes an enormous difference. Now the CPU can pull x and y into its cache, do the eighty-one addition operations, and send the result back into main RAM once, saving a ton of time. Modern CPUs tend to have a few 'levels' of cache. Level 1 cache is the absolute fastest but also the smallest, then there's Level 2 cache which is a bit larger and slower, then there's Level 3 cache with is larger and slower still. A CPU might have for example 128 KB L1 cache, 512 KB L2 cache, 4 MB L3 cache, then hit 8 GB of main memory. And if main memory fills up modern operating systems usually allocate some extra space on the hard disk that can be used like additional memory, with the downside that this is massively slower. To illustrate the differences in speed, on one benchmark for a 2017 Thinkpad laptop, retrieving a value from L1 cache took around 1 nanosecond, from L2 cache around 6 nanoseconds, from main RAM around 100 nanoseconds, from an SSD around 16,000 nanoseconds, and from a magnetic hard drive around 2.6 million nanoseconds."
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d0fpoi | why is "hand-made" synonymous with high quality? | Technology | explainlikeimfive | {
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"It implies that the builder, creator, manufacturer paid an attention to detail that can be missed on an assembly line.",
"It's marketing mostly, yeah. It's an implication that there's extra attention to detail, a break away from soulless mass production (even though hand manufacture can still in some instances be in massive numbers). It also takes advantage of the link that is there between hand made stuff and quality. Take food for example. A meal from a skilled chef is always going to have an advantage over a mass produced stab the plastic with a fork three minute in the microwave meal. That thought process is what's being appealed to with Hand Made marketing.",
"It works by making you think the product is unique and someone out there made it just for you, so you are special somehow.",
"It's kind of double edged marketing sword. Nobody wants handmade precision automotive components. But a hand-made leather good is another matter. Do human eyes and human hands enhance the end product, or introduce imprecision?"
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d0fsz7 | Why is it necessary to wait some time before turning something on after turning it off in order to make it work again? | Technology | explainlikeimfive | {
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"Mostly found with electrical devices. Leaving it off for a bit allows all the left over electricity inside the system (batteries/capacitors/relays/etc.) to pass causing some parts to lose their memory. So when you turn it on again everything starts up from scratch. Its inside those bits that remember settings where the fault lies sometimes. Usually caused by systems not putting back properly the things they used or needed.",
"The purpose of power cycling electronic devices is to wipe their short-term memory (RAM). Cutting power to the RAM makes it lose all the data it currently holds, and with it any program errors that may have been lingering and causing trouble. But there are some components such as capacitors that need a few seconds before their voltage drops all the way to zero, so if the power cut is too short, the RAM might not reset."
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d0gpg8 | Why doesn’t GPS work underwater? | If a satellite can pinpoint my location from SPACE, how come a (relatively) small amount of water prevents GPS from working? | Technology | explainlikeimfive | {
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"Water absorbs radio waves across a considerable band of wavelengths. It's so good at this that your microwave oven can quickly boil water by pelting it with radio. Since the GPS is relying on radio communication to triangulate itself, it will lose contact quickly under water.",
"The other replies have explained that water eats microwave, but I wanted to mention that your understanding of GPS is backwards. All the satellites do is yell, \"my name's Gary, and it's exactly 8:54 AM!\" By counting how long it took for your device to hear that message, you can figure out how far away you are. If you get three messages from different satellites in different places, you can trilaterate your position. If you stuck your head under water, it wouldn't be Gary's fault that you couldn't hear him.",
"Because water, and *especially* salt water (but not pure water) is a really good electrical conductor. That means electromagnetic signals get attenuated and absorbed very quickly, which means they don't penetrate the surface very much, or at all. GPS satellites transmit in the L band of the microwave portion of the spectrum, which is between 1-2 GHz (wavelengths of 1–0.1 m). This is called UHF, or ultra high frequency. These signals are essentially immediately absorbed and don't penetrate water at all. You can tell how well water absorbs these signals because your microwave oven can literally boil water, and it uses similar frequencies. Signals with much lower frequencies can penetrate water better, but you need to use what's called VLF, or very low frequency. Frequencies in this band are 3-30kHz (wavelengths of 100–10 km), and they can penetrate up to 40 or so meters depending on the salinity of the water.",
"How come the sun doesn't shine through my walls? I mean, it makes it ALL THE WAY THROUGH SPACE, but is blocked by 6 inches of wood and plaster? That reason, but water instead of wood.",
"GPS doesn't work underwater because GPS communication is at microwave frequencies, which water absorbs very effectively (this is the mechanism that makes microwave ovens work)."
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d0ivw2 | How web apps like Akinator works? | Where they are gathering such big ammount of data? How he managed to do the trick at the very begginig? | Technology | explainlikeimfive | {
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"Well, it can gather a lot of data from the players. It's also not always right. If you consider 3 options for each of 20 questions (yes, no, other) There are already billions of different conclusions you could reach. Assuming you pick your questions well enough to always eliminate half the remaining options, you'd reliably be able to guess about a million different possibilities.",
"It's....game of 20 questions. A very well understood game of divisive choice making. It would be pretty easy to compile a list of popular fictional characters and attach attributed to those characters that can be categorized and queried on. You're talking a dataset that's probably only in the millions. Thing is...your dataset doesn't need to be complete at day 1. It just needs to be reasonably substantial to make the guesses have a good shot at being correct. There's no real penalty for being wrong."
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d0j4qi | What are beam forming microphones and how do they work? | Technology | explainlikeimfive | {
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"Beamforming microphones are microphones designed to listen for sound from a specific direction. This is done by comparing the sound received by various microphones in slightly different places to separate the \"noise\" from what you're listening for."
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d0l4py | Other than banking info, how is stolen data valuable to a hacker? | Technology | explainlikeimfive | {
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"A user often uses same or similar passwords. So if Armorgames database gets hacked, it is certain that some users used the same passwords on their Gmail accounts, or Facebook etc. Other than that, the data itself is really useful. Hackers use the stolen data to \"fine tune\" their \"brute force\" attacks. They use the millions of passwords to create a \"dictionary\". So when they try and guess someone's password, they use the patterns they learned from the millions of passwords, and the attack takes a short time, compared to years it would take without using a dictionary.",
"A big one is password re-use. People often end up re-using the same password across a bunch of different sites, including, but not limited to banking sites. Even something like the Starbucks app or Domino's app can be used to steal money/free food. That happened to someone I know as a result of the Yahoo hack. His Yahoo password was compromised, and it was one he re-used across a lot of phone apps, where it was particularly difficult to type in a more complex password (this was before the automatic suggestion to let IOS generate a complex password for you). He ended up with several hundred dollars worth of Starbucks gift cards being rung up on his account, then transferred off to physical cards. He also had a couple large Domino's orders charged to his card as well. Other uses include personal details that can be used in phishing Emails to make the deception more convincing to the target.",
"If they can accumulate enough info to convincingly fill out an application, they can apply for credit cards, loans, or passports/ID cards using your information. And of course, raid your bank accounts.",
"Typically the hackers are not the ones who use the data themselves, aside from passwords. Most of the other info is sold to other people who will make use of it. * Emails and phone numbers are sold to advertisers. Usually only the scammy kind of advertisers, the ones who want to sell you extended car warranties and boner pills. * Credit, debit and bank info is sold to thieves, most of the time only the cards are used, as those are easier to use without getting caught. * Personal details (Name, birthday, address, SSN, etc.) will be sold to identity thieves. This is so they may attempt to open credit/loans under other peoples identities.",
"Data tells you things about a person and those things can help a hacker (or other hackers, data can also be sold to others). With more data available an attack profile can be made, which can help/be used to gain access to other perhaps data that is more valuable to the hacker. Two small examples I've personally seen used: 1. A hacker finds out that you use vulnerable remote control software for all of your PCs and uses that to log in on your home PC. On your home PC you might have your browser set up so you log in on several websites automatically. The hacker uses that to order products and ship them to an address he has access to. (bonus tip: keep your systems up-to-date) 2. A hacker knows you use a certain e-mail address on a website he wants to get access to. He checks if that e-mail address can be found on lists of previous hacks and finds out this is true. The hacker then uses the passwords found in those hacks to try and gain access to the website. (bonus tip: check out [ URL_0 ]( URL_0 ) )"
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d0ma2s | In C#, why is the ‘float’ type only accurate to 7 digits? Why do you have to put an ‘F’ at the end of the value? | Explain in the simplest way possible because I’m dumb and a complete beginner | Technology | explainlikeimfive | {
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"The standard format for floating point numbers is IEEE 754. For a 32-bit float (as opposed to a 64-bit double), this would mean 1 bit for the sign, 8 bits for an exponent and the remaining 23 bits for the mantissa. 23 bits of mantissa can represent a range of values from 0 to 2^23 (8,388,608). Those are your 7 digits right there. You can't have any more precision because you don't have enough bits. With a 64-bit double, you use 52 bits of mantissa, which gives you 15 digits of precision."
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d0n6vf | How do electronics with no moving parts degrade over time? | Technology | explainlikeimfive | {
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"I'm told that a lot of it comes down to thermal cycling and mechanical vibrations. Electronics are made of a bunch of different components fit together on a microscopic scale. Changes in temperature cause these components to expand and contract at different rates and slowly wiggle themselves apart. Not only this, but normal vibration also contributes to the wiggling problem.",
"One common cause is electrolytic capacitors. With heat and time they dry out and go out of tolerance. Many times old electronics can be repaired just by replacing those capacitors.",
"Over time, multiple parts of machinery oxidize, rubber dries out and creates micro fractures that allow air and dust to penetrate metal components, and the electrical currents degrade the wiring and circuitry until they inevitably burn out. It’s important to acknowledge that just because you can’t see the parts working and stressing themselves doesn’t mean that the parts aren’t under stress and undergoing wear and tear. Oftentimes, components can be replaced or repaired, but they will require routine maintenance to mitigate the damages to the equipment caused by the atmosphere over time and the electrical currents passing through the wires and circuitry, because those are constants.",
"Techie here but this is only a guess. You still have current moving around the system and even though there are no moving parts heat is still being generated. So there is friction happening still. That will cause those electronics to degrade",
"Electronics are built with tiny metal circuits created on \"boards\" made of silicon and other polymers that have the ability to transmit and conduct micro-currents (think tiny amounts of electricity flowing across multiple wires). The issue they face is that of heating and cooling processes that occur due to both operating and environmental factors. When a device heats up it is typically due to a large draw of electrical current from the battery (causing the battery to heat up) by the processor which in turn the battery then dissipates that heat across the many parts of the device. A device heating up can also be because the environment is hot due to the suns radiation or some other external source. Over time as the device goes through hot and cold cycles the internal parts undergo degradation (think how steel gets more brittle and hard the more often it is heated and cooled). Add in the fact that devices are subject to movements and vibrations such as finger taps on a screen or being dropped on the ground, and you begin to create microscopic cracks on the various materials which in time affect the ability of those parts to conduct micro-currents. Eventually a part fails and causes malfunctions. Thus while the parts may never have an actual purpose resulting in physical movement they are still subject to very small forces that move them slowly over time."
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d0o966 | How does games sync up NPC so accurate? | Like in GTA V, every car, motorbike, even single NPCs are at the same place at the same time for all the player on the server. | Technology | explainlikeimfive | {
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"Server sends every player's computer a data packet containing information like an NPC's coordinates and clothes."
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d0o9ea | What do all these companies use my data for? | I've read some articles and papers here and there but I'm still fuzzy on some points. So I know some companies have my data. My mundane, trivial, freaky and sometimes grotesque data. What do they use it for? Aside from using it to target the right ads my way. I don't mind a personalized experience in the appropriate settings, ie shopping online. But what about the other companies? The ones that are not online shops or social media sites. | Technology | explainlikeimfive | {
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"The data is used to assess your credit risk in various situations, or to partition large groups of people for targeted services or investigation. A lot of data has historically been collected on the assumption that it may someday be valuable. Big Data is used for fine tuning political campaigns, gerrymandering, setting insurance premiums, deciding where to invest in infrastructure, and pretty much anywhere else someone has to decide where to spend a lot of money. Of course, that data is used by data thieves to manipulate and to steal identities as well.",
"In their perfect world, they would like to know/learn exactly everything you are going to do before you do it, so they will provide your perfect advertisement, purchase, etc., etc. They might even steer you to do things you wouldn't normally do (which is what advertising really is, isn't it?). If you are a minimalist and don't do anything, they will know that and move on to the next person."
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d0qc0f | Nothing is ever truly gone on the internet. Why is that? | Technology | explainlikeimfive | {
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"Contrary to that saying, lots and lots \"goes\" from the internet all of the time, it's actually a huge problem for people who care about preserving information and history. Fortunately there are more and more archival sites, but they still struggle for funding and manpower. The saying though just reflects that you should never assume (or expect) that something you say or do online will be forgotten or lost. Odds are it will be preserved in some form, but this isn't actually a guarantee.",
"The saying is a healthy assumption to follow, but not a statement of literal fact. If you have your own personal website, put up some information, and then take it down seconds later before any person or bot has a chance to see it, then realistically the information is gone from the Internet. No one's finding that information unless you post it again. But practically it's just way too hard to control where information goes once posted. People can screenshot and save stuff to post elsewhere later. Search engines and bots are busy crawling and archiving whatever they find. And if you delete something like an email from your Gmail inbox or a post from Facebook, it is often the case that the service provider will still retain a copy."
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d0qkqp | Why do gas stations ask us to turn off our mobile phones? Why is there a risk of explosion if we are using our mobile phone in gas station? | Technology | explainlikeimfive | {
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"There was a theory back in the day that mobile phones could cause a spark or an electrical current some how that will cause gasoline vapors to ignite. There was no evidence that backed it up and Mythbusters actually did a test on it and confirmed it wouldn't happen. I haven't seen one of those warnings in a while. Now it just says to not put your hands in your pockets and discharge any static you might have built up before pumping/touching the pump.",
"Not to sound sexist or anything, and slightly off topic but it still applies... I actually saw that It’s ok to keep your car running, play with your phone, etc, but the biggest problem with gas station fires is caused inadvertently by women. The theory was because men will get out of the car and stand by the pump until it’s done. Women will start the pump, get back in the car because it’s safer, get back out, causing more probability of them causing static when they remove the pump from the car."
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d0s21m | How does cross platform gaming work? What is the path of data across platforms? | EDIT: To clarify, I mean PC to Mac or even PC to Console gaming. | Technology | explainlikeimfive | {
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"I assume you are talking about multiplayer games, where say Windows users can play with Mac users. Essentially, when you play a multiplayer game, the game sends out some data to the company servers. The company servers then sends back some data (like other player's health etc) to your game and your game decodes the data and updates locally. Therefore, it doesn't really matter what your peers are playing on, every game client (on all supported systems) sends out the same data to the company servers, and receives the same data. The only difference would be the game itself, and how the data are decoded into what the local system can understand. **ELI5 version:** Game running on windows is like the Chinese man, the game running on Mac is like the English man. The game server is like Morse code reader, and both the Chinese man and the English man knows Morse code (the data). When you play a game, Chinese man sends Morse code to the Morse code reader, and so does the English man. Morse code reader sends back some Morse code to the Chinese and English man, and both of them translates the Morse code into their own language. So, it doesn't matter what language they know, as long as they understand Morse code, they are fine.",
"In theory, cross platform gaming is easy to implement. If all versions of the game send the same data in the same format then there's nothing to stop people on different platforms playing against each other. However in practice it does take some work because most games rely on online services provided by the platform. For example Xbox Live provides user accounts, friends lists, matchmaking and stuff like that. So making online play work between different consoles, or consoles and PC, means you have to somehow make all these different systems on different platforms work together. In the past the main thing preventing cross-play between consoles has actually been that the companies that make the consoles had rules against it, not that it's especially difficult on a technical level. This is less of an issue now though because Microsoft, Sony and Nintendo have all loosened their restrictions on it. This isn't really an issue between PC and Mac. Lets say your game comes out on Steam. It's Steam provides these services (some of them at least), not the PC/Mac's operating system. And Steam works on both PC and Mac, so there's no particular reason PC and Mac players shouldn't be able to play together."
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d0tksb | Why did India just fail a moon landing when 50 years ago humans landed there successfully? | Technology | explainlikeimfive | {
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"During the [fine braking phase] ( URL_1 ) India lost radio communication with their moon lander. This prevented the spacecraft from being given appropriate adjustments to land properly. It probably attempted landing at too high a velocity, not allowing the landing gear to deploy in time. If this was a manned mission to the moon, a human pilot could have probably made the adjustments in time. This [broadcast] ( URL_2 ) is a mix of hindi and english but has more details Any comments made about the United States having better minds in 1969 is not accurate. If anything, India in 2019 has a lot more experience and technology to draw from than did NASA in 1969. The truth about space exploration is that it is dealing with a large number of uncontrollable variables, and very large distances. All of these factors can not possibly be planned for, thereby making space flight [very dangerous] ( URL_4 ). The US, China, the EU, Russia, and pretty much every organization that has attempted space exploration have had their fair share of [set backs] ( URL_0 ). The two advantages that those previously mentioned organizations have had so far over India are: resources and political will. The keyword being \"so far\". India's space program is accelerating quickly. And it should be noted that they do two things better than almost every other space program in the world. They are able to achieve the same mission goals as other programs with [far less money spent] ( URL_3 ), and they are surprisingly good at collaborating with other space programs. Two traits which one day might give them a competitive edge over other organizations.",
"You're trying to something very complex and precise over an extremely long distance. The signal delay alone is over a second. So all the information a lunar vehicle sends our way is over a second out of date, any instruction you send back is 2 seconds out of date from the original situation plus any time you spend analysing it. Before braking maneuvres, these vehicles fly at hundreds if not thousands of metres per second. The 1969 moon lander required last-minute adjustments by the human pilots to avoid crashing. But sending humans as a fail-safe is a pretty risky solution. Sure, it's great to be able to have people on location that can make adjustments on the fly as the situation develops but for the most part we prefer crashing an unmanned lander over risking a manned one.",
"If it's relevant, the first manned moon landing mission (Apollo 11) had to switch to a manual landing for the moon surface approach after the radar landing signal failed. The US had spectacularly trained pilots there for just that. Unmanned exploration has a long history of failing when it comes to the moon.",
"No mission is same. Every mission is dealing with something new, and that is why we are doing it. In this particular scenario ISRO was attempting their first ever soft landing on any non-terrestrial body. Not sure how much of a knowledge transfer they got from NASA or the Russian body. Irrespective they were attempting landing much further south than ever attempted. This created newer challenges which were never faced by any of the predecessors, who in turn had their fair share of failures in their landing attempts. Also, ISRO works on a much much stringent budgets than any of their counterparts."
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d0usa7 | What are Thorium reactors? | Technology | explainlikeimfive | {
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"They make their nuclear fuel “just-in-time” from widely available thorium, which itself is not useful for nuclear weapons or appealing for use in dirty bombs. Thorium reactors essentially “burn” through a potential fuel bed like a flame along a strip of paper. The leading edge turns “fertile” thorium into “fissile” uranium. This uranium is almost immediately consumed by a nuclear reaction, advancing the edge of the reaction wave in the thorium and giving off heat. Thorium is cheap, abundant and relatively safe to mine and transport. If a bad actor tried to break into a thorium reactor, there is very little uranium or plutonium to divert or steal. The reactor is mostly thorium, a small amount of uranium (of a type that is hard to weaponize), a vanishingly small amount of plutonium (also of a type that is hard to weaponize) and spent fuel products.",
"The most important feature of thorium reactors is that they do not operate at high pressures. Current reactors operate at extremely high pressures and are built in containment vessels to keep that safe. Any problem or flaw risks breaking that containment vessel, which can cause explosive decompression, essentially ripping the pressure vessel open and spraying nuclear fuel into the air. Thorium reactors do not need high pressures and can operate sealed, but not under pressure. Any flaw in the casing would cause it to 'leak' like a toilet overflowing, but not 'explode'. They are also shown to be able to scale down. This means that they can be made much smaller and self-contained to the point that they could become modular devices. Small self-contained units that could be dropped off to power arctic bases or etc. Run for 10-20 years, and be reconditioned or replaced. Certain designs are also thought to be able to consume existing nuclear waste as fuel. The idea is that large thorium reactors could be built next to existing plants or storage facilities and burn the stockpiled waste removing the problem of storage for 10 000 years. Probably the best aspect of thorium reactors is their narrow band of sustainable reaction. It was tested at Oak Ridge Labs that thorium reactors don't really 'melt down'. If they get too hot, the reaction moves out of the operating range and actually slows down, which cools it off, and lowers the temperature back into the correct range by itself.",
"There are some decent explanations here, but much of what you hear in articles about Thorium reactors is either false or kind of mischaracterized. Here's a good resource written by some nuclear engineers that lays out some of those misconceptions and the advantages of Thorium reactors compared to uranium reactors. URL_0",
"Not an expert, but basically a thorium reactor would produce power with far fewer radioactive byproducts in the spent fuel. Those products are much shorter lived too. Current reactors produce waste that has half lives in the tens of thousands of years. Thorium reactors would produce waste that has half lives in the tens or hundreds of years. The byproducts in the Thorium reactor waste also cannot be used in nuclear weapons. Tldr \"cleaner\"",
"So are these reactors being built? Or plans to be? Seems like a safe, clean power source."
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d0uv31 | how do car radios receive the title and artist information for songs playing on the radio? Why does it sometime lag and display the wrong information? | Technology | explainlikeimfive | {
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"When radio stations propagate sound there is also hidden digital data that can by only \"heard\" and decoded by receivers with RDS standard. They are lagged mostly because of loss of data packets.",
"There is a system called RDS that transmits the information along the radio waves. It might be possible that there are delays in the broadcaster end to update the information when a song changes."
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d0w6xc | When describing computer components, I've heard the term architecture referenced several times before. What does it mean? | Technology | explainlikeimfive | {
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"Architecture refers to the structural design. Every couple years a CPU/GPU manufacturer will release a new chip that has it's internal layout and configuration changed significantly, this is a new \"microarchitecture\" Sometimes they just shrink a process or optimize how they build the chips. Since the internal layout is fundamentally the same this isn't considered a new \"microarchitecture\" Intel's 6xxx processors are the Skylake microarchitecture, as are the 7xxx and 8xxx (codenames Kaby Lake and Coffee Lake). They only differ slightly in design and performance, the biggest gains generally come from a new microarchitecture",
"It means how different blocks interact, how they fit together and how they exchange data or such. How the '' layers'' of your system are built."
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d0wx3m | How does the signal between a drone and the controller/headset not lose connectivity? | I've seen people race them and fly a drone through buildings at high speeds; how does the connection remain so strong between the drone and the headset? Particularly at such a fast rate that drone pilots can fly the drones with very quick reactions to what they see? | Technology | explainlikeimfive | {
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"radio waves travel at the speed of light, interference can cause problems but think of it this way, the time it takes the light from your car lamps to hit whatever is in front of the car is how fast the signal travels through air.",
"It takes relatively little data to control a drone. When flying around obstacles and such, the drone may have trouble keeping a proper connection due to obstructions, but a little bit of data can still get through. When you're watching a youtube video, you want a few megabits per second for your connection. A drone might only need a kilobit per second or less."
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d0y1qb | How you record on cassette tapes, and how there are cassette tape that are converted to be an aux cord. | Technology | explainlikeimfive | {
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"Cassette tapes work as a medium of magnetic particles. The arrangement of the particles can be read by the head of the player (which is just an electromagnet) Similar to the binary dots burned into a CD or the raised grooves of a record. This is how the information is stored. On an aux-tape, there is an electromagnet like the read head on the player. It get’s it’s signal from the aux cord and arranges the electromagnetic head as dictated by the voltage of the signal the same way that voltage goes to earbuds and drives the speakers.",
"Tape is an analogue technology, which means that it records information (sound in this case) by replicating the signal with different levels of magnetic charge on the tape. The tape can be written to by applying a strong magnetic field to the tape to magnetize it, and can be read by applying a weak magnetic field to the tape, and measuring the response. A tape recorder / player is essentially a device that converts a magnetic analogue signal to an electrical analogue signal, and vice versa. An aux cord is just an ordinary electrical cable that caries an electric analogue signal. Most cables can carry two signals at once, for stereo sound, but some cables can carry three signals, two for sound and one for a microphone. Nothing special needs to happen for a cassette player to send audio over an aux cable, except that the signal from the tape might need to be amplified to be audible. The aux cable just needs to be connected to the players analogue output, and the other devices analogue input."
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d1158q | how can an untivirus know a software is a virus? | Technology | explainlikeimfive | {
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"It’s simple, they can look up from a database ( that’s why it’s important to keep your anti-virus up to date, even Windows Defender ), or they can see if they’re doing suspicous things ( if something is trying to delete System32 it’s pretty safe to say it’s harmful )"
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d17dtf | why do people have grass for roofs? | I see this constantly in certain European counties, and mostly in villages, but still, why? Is it ascetic, or is there an actual purpose for these type of roofs? | Technology | explainlikeimfive | {
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"text": [
"green roofs keep ur house cool, produce oxygen, save money on shingles, reduce stormwater and its good for our health to be surrounded by nature",
"Sod roofs are waterproof, heavy (which is good for a log house), reasonably good insulators, and made of materials that are free. All of those things make them a pretty good choice for rural areas in cold climates."
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d184w0 | What's a DDOS attack? | Technology | explainlikeimfive | {
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"DoS = Denial of service. DDoS = Distributed denial of service. Imagine a fast food joint. Normally the cashier says \"Hi! How can I help you?\" when they're ready. Instead of that imagine you just rock up and go \"Yo. Big Mac.\" and they're just ready for you. Now imagine you doing that over and over and over and over. They'll fall behind with the orders. That's a DoS. A DDoS would include you and your entire family rolling up and doing that over and over and over.",
"It ia like when a big crowd needs to leave a concert and there is a narrow exit. Everything grinds to a halt. A DDOS is like that, but due to malice instead of incompetence."
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d18ld1 | how can hackers read emails in transit? In addition to phishing for account details and accessing someone's email account directly, is it possible for hackers to "read" ongoing email communication that is not encrypted? | Technology | explainlikeimfive | {
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"They either need access to your machine (easiest), access to your mailserver via your credentials (super easy) or access to the server itself (med), be your ISP (lol) or set up a man in the middle (hard), or have access to the mailserver or machine of the recipient. Encryption only prevents the man in the middle reading your email as it's only encrypted in transit (like SSL) and not at rest on the servers. It's an outdated, insecure protocol that shouldn't be used for anything but sending electronic post cards. Assume everything you send is a postcard that others can read unless you are using additional encryption to ensure the messages contents are encrypted at rest too such as PGP/GPG.",
"1. Emails are like convertible cars they don't have a roof to keep you dry when it rains you get wet. The email protocol was designed before hackers were a problem it has no security or secrecy built into it. 2. , Imagine having to present your bag to a private security guard at every school and shopping centre you went to. And the security guard will open your wallet and read all your credit cards and open letters and bills. Packets are routed through the network to anyone with a network device. The owner of the device can open every email that arrives at their device requesting to be delivered somewhere else. Note: modern email clients use secure methods to forward emails but the email client you use and the email provider you use must both use these methods or the email is sent unsecured. This is different to Web browsers which encrypt the the request before sending it. Gmail is an example that gives some clear warnings when using unsafe transit methods."
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d1bzu1 | Huge Cranes | How do they move those huge cranes. Its been haunting me for years. | Technology | explainlikeimfive | {
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"text": [
"Cranes build themselves by raising their top section up on stilts and then lifting a piece of it's 'neck' up and then into the open section. You can see a video of this happening here. Outside of that, they're just moved to building sites in large chunks by trucks or trains and they go from there. URL_0"
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d1ev6b | How is it that adverts always load quicker/more easily than everything else? | Technology | explainlikeimfive | {
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"Since ads are going to be fed to just about everyone they are stored on a local server. Take your example of Instagram say you are looking up your Aunt Mable's cats account. You may well be the only person in your area looking at it so the data has to be fetched from the main Instagram servers. The ads however are going to be sent to everybody in your local area. To save having to fetch the same data for every person ISPs have local caching servers that store regularly accessed content to save bandwidth. The ads will be loaded from this much closer server.",
"I could be wrong, but I believe adds are stored locally on a server as they are directed at a target market."
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d1fd3a | How can someone DDOS servers of multibillion dollar company (Blizzard) and how hard is to track the person who does it? | Ok so like two days in a row there is someone DDOSing Blizzard WoW classic servers. How can someone does this to such a big company? They have so many resources. And how hard is it to track the person who does this? I rly dont understand why would anyone do this in a first place, will the person go to jail for this or is it "untrackable"? edit: looks like they got him [ URL_1 ]( URL_0 ) | Technology | explainlikeimfive | {
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"The \"D\" in \"DDOS\" stands for \"distributed\", and it means that there are many computers on the attacking side. Those can be from a botnet where the attacker has managed to install some sort of software on them. Or they can even be volunteers, where somebody posts a call for action on some forum and people voluntarily join in. If you consider that somebody with a good connection might easily have 100 Mbps or more available, it adds up to big numbers very quickly. Also consider that while Blizzard has a lot of servers, individually they're not that strong. If a given machine has say, 10 Gbps networking, then that particular machine only needs to be attacked by about a hundred machines or so. Bringing down a single machine might be plenty. It could be a particular server the attacker wants down, or worse it might be some sort of central authentication server. Then nobody can log in even though you've just taken 1% of the datacenter's total capacity. Then there are amplification attacks. For instance, if you find something you can send to a server that's small but produces a large response, this works in your favor. You send 100 bytes of junk, you get a 1KB error page back, that's the victim doing your work for you. Now you only need 1/10th of the bandwidth on your side to take up all of theirs. One can also attack other resources rather than just the network. For instance if disks are slower, or if some particular action consumes a lot of CPU time you can get a lot of effect that way. If the server needs 10 ms to process a given command, you only need to send 100 of those per second, and suddenly the CPU is 100% busy.",
"Normal method is to hijack other computers to carry out the attack so unless you can track who hijacked the computers all you can track is the \"innocent\" people who got hacked first.",
"Tracking the person can be fairly difficult depending on how the attack is carried out. Botnets for example are hard to find what the originating IP is since the DDOS attack is coming from 100 different \"people\" all taking commands from somewhere else. In todays case - the DDOS attacks on Blizzard were done by someone waving their new toy around using a 5+ year old twitter account (that has since been suspended.) - A seemingly rookie mistake If Blizzard had the police involved, Twitter will have the IP's of every login connection made on that account in those 5+ years, some of which I can almost guarentee will be from the attackers home address, then all Twitter has to do is give the police this data, who'll then talk with ISP's to find out who had the certain IP's at the given time and boom, jail time.",
"Same principle as any ddos attack, just on a larger scale. Also there are some security services which they have to find a way around, but as almost allways there are more people trying to break in than people defending. If enough small fish try to get through the huge wall eventually someone will find the crack. Tracking is quite hard, these attackers normally know what they are doing. So normally it's almost impossible to find the person reliably.",
"It’s really hard to trace people who do this kind of stuff, but there’s always a way. Multiple people have been arrested and found guilty for this kind of crime before. Usually, because they make mistakes - they use the same email address in relation to another service online, where they can be traced to some information that links them to their real identity. Or in many cases, this kind of activity is the prelude to (illegal) selling of their services. Attacking Blizzard and Twitch and Wikipedia is an advertisement, telling people they can do this and offering to sell their services to paying customers. This makes them easier to track and eventually take down.",
"> How can someone does this to such a big company? You normally would use something called botnet. Botnet is a collection of compromised devices connected to the network - these devices could be video cameras, home routers, laptops - basically anything that runs OS that can have new packages installed. And there are A LOT of devices that can be compromised, since security is at best an afterthought. So these devices in Botnet sit dormant and do nothing malicious (and thus undetected), until somebody tells them to do something. And that something could be as simple as \"try logging in to Blizzard account\". And if at any given time there are lets say 1000 people logging in every second, Blizzard will not be able to handle one million devices trying to log in at once. And keep in mind that Blizzard has to process each request to figure out whether it was legitimate one or not. > And how hard is it to track the person who does this? The companies that offer botnets for hire usually operate in dark net, where it's somewhat harder to track people's connections. And they take payments in all kinds of different formats, some of which is also very hard to track even if somebody could get a hold of that company;s records (which I bet they don't even keep). Can it be done? Yes, definitely. But it won't be easy. I would not be surprised if some special services can do it, but they wouldn't do it for some trivial DDOS attack that didn't cause any massive disruptions.",
"Do we know if the WoW and the Wikipedia attacks were from the same source?",
"basically think of it like this. theres a big open room, inside this room there are several doors these doors make up the different servers, a DDOS attack is like someone gathering 10,000 people into the room and them all rushing the doors at the same time, they block the doorways and make it impossible for anybody else to get through.",
"Distributed denial of service, essentially someone (attacker) rents some time with a botnet (a network of computers with viruses on them, each of these installations of the virus takes control of the computer and connects to what ever it is attacking. This overloads the server so no one can use it. If you could figure out which botnet was used AND who rented it, sure. But botnets are almost never run from the the wealthier nations, so that's difficult. It's not impossible but it is next to impossible. (Edit: also a hacker isnt going to say to whoever he/she is renting the botnet from hey my name is Alice Sophie Jackson, can I rent your botnet? They will use usernames at most."
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d1jtkj | Why is an emulator required to play Playstation/Xbox/Nintendo games on a PC? | After all, doesn't a PC contain all of the same components as video game consoles? (Hard drive, GPU and CPU, etc.) | Technology | explainlikeimfive | {
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"PCs and game consoles both contain CPUs, yes, but they speak different languages. You need an emulator to translate back and forth between console-speak and PC-speak."
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d1ks5g | How do computer applications like windows media player actually play sound and video? | Can anyone familiar with this explain how these programs work? Like what is the process that the program goes through when its fed a .MP3, .JPG, or .AVI file for example? | Technology | explainlikeimfive | {
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"So, graphics and sound are stored and played somewhat differently. So, first let's break down that process. For video or images, the data essentially describes a grid. Imagine a mosaic of tiles - different colored tiles can be placed next to each other and, when you look at the whole thing, it resembles a picture. In the same way, a raster graphic file describes a grid with each pixel being a point on the grid with a specific color value. To make a video, a \"stack\" of those images are played in succession - much like a flipbook, animated cartoon, or celluloid movie would. These files use some tricks to reduce size and increase performance (like interframe encoding where only changed pixels are stored between key frames) but the end result is a map of different colored pixels that make up the image. Audio is a bit trickier to describe, but it comes down to describing a wave. Sound is, as you might know, transferred as a wave. That wave can be described digitally by drawing \"slices\" under the wave. So, think of a curve, then draw lines of different lengths from the curve to a common axis. Each line is a sample of the wave. By stacking the samples, you can recreate the wave. And, the more samples, or \"slices\" you have, the better the definition of the wave, and thus the sound being played. For video, it's just a matter of linking the two streams together. I believe this is done by using key data in the streams to keep them in synch. Sort of like a clapper is used to film a movie. The clapper provides a common point to start both streams and, as long as they both playback at the same speed, it's all synched up."
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d1p1cg | How are QR codes maintained without any repetition? | Technology | explainlikeimfive | {
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"QR codes are just a different way of writing stuff down so it is easier to read for computers. You can easily make any sort of QR-code that says whatever you want. A common thing to write with QR codes are URLs (the addresses you type into webbrowsers). for example this should go to the URL of [your reddit profile]( URL_0 ). In practice the QR-code is just like a different font to write in and to making things unique is a function of whatever you write down. If you want to write a QR code that just says \"Hello world\" you don't need to have this be unique. Web-addresses are unique due to how they are made and independent of how you write them down. Lots of other things you might want to write down with QR-codes like MAC-addresses or phone numbers or ISBN-numbers have their own way of ensuring that there are no repetitions. The QR-code itself doesn't have anything like that build in.",
"QR codes are not a unique ID, they directly encode data such as a number or short text in a format that is easy to extract from an imperfect image. There is no expectation of any generated QR code being globally unique.",
"Simply the amount of information it can hold, the largest QR code can store about 15,000 bits, which (according to Wolfram Alpha) can be arranged in 2.817960879631397637428637785383222308241674912977296×104515 different ways."
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d1pxh7 | How is fMRI done when physical tasks are required? | For example, a book I’m reading talked about a neuro-psych study done where brains were mapped while the subjects completed repetitive/boring tasks, allowing their mind to wander. Another study I read about mapped brains in people with certain types of pain immediately after exercising. How are images captured when physical tasks are involved and how accurate are images when there’s a lag (even if short) between task and imaging? | Technology | explainlikeimfive | {
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"For the images to be sharp you only need for the head to be still, or more specifically the brain. The rest of the body can still be moving around and the patient can even move his eyes and mouth without impacting the image quality. If it is hard for the patient to keep their head still it is possible to mount it in the fixture that keeps the skull from moving. The subject can be put in such a place that only their head is inside the MRI machine leaving their body free to do other tasks. For example it is possible to install a weightlifting rack right outside the MRI machine to take fMRI while the subject is weightlifting. However care must be taken that no ferromagnetic substances is used."
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d1q5h3 | Why do older emulated games still occasionally slow down when rendering too many sprites, even though it's running on hardware thousands of times faster than what it was programmed on originally? | Technology | explainlikeimfive | {
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"A lot of old games are hard-coded to expect a certain processor speed. The old console had so many updates per second and the software is using that timer to control the speed of the game. When that software is emulated that causes a problem - modern processors are a hundred times faster and will update (and play) the game 100x faster. So the emulation community has two options: 1) completely redo the game code to accept any random update rate from a lightning-fast modern CPU Or 2) artificiality limit the core emulation software to the original update speed of the console Usually they go with option 2, which preserves the original code but also \"preserves\" any slowdowns or oddities caused by the limited resources of the original hardware.",
"Part of it is how accurately you want to emulate. Take the game Space Invaders. You may recall there's many enemies and as you kill them they speed up. That was not coded in, it was a happy side effect of the processor being able to render fewer faster (and one super fast lol). If the emulator is not coded to run at the same speed as the old processor then you won't get this effect. Edit: I didn't learn this from Game Maker's Toolkit, never heard of that show.",
"Accuracy of emulation. If the original hardware would have done it, your emulator should do it. Simulating hardware means reproducing all the features as well as all the limitations. Some emulators have an option to overclock the emulated CPU or raise the sprite limit, but there are risks if the game isn't prepared for it. Behaviour of not running on the original hardware is undefined and you are in uncharted territory for the developers.",
"The games are not emulated, the systems are. A chip has instructions on it, that can not be changed. Software has instructions that can be changed. What this means, is that an emulator \"emulates\" the system, not the game. That includes clock frequency.",
"Not exactly a super old game, but Age of Mythology was made when computers only had one core, when they re released it on steam it had massive lag and gameplay issues and no amount of computing power really helped because the game could only be run through one of the computers cores. What they needed to do was build it up from a bit further back so that the game couldn't utilise the newer computing power. Could be totally wrong on this, as this is just what other community members have told me and I have no idea what I'm talking about haha",
"To add, \"rendering too many sprites\" doesn't cause slowdown. You could (in theory) completely lock the CPU up and the game would continue to render at 60fps. This is because sprites (and backgrounds) are served up to the TV at 60fps no matter what the CPU is doing. The hardware is reading a specialized block of RAM in the console called OAM (Object Attribute Memory), that says what sprites and tiles go where. When you see \"slowdown\" in old console games, what you are really seeing is the game failing to update the OAM on a frame, and so you see ~the same frame again, still at 60fps. This is usually because (eg the NES) has too much CPU work to do to get it all done in the ~30,000 cycles before the next frame. A great example is collision detection - I read somewhere that doing box overlap tests for all the sprites in Super mario bros would have meant they could only update the game at 30fps, so they only do half on one frame, and half on the next...",
"If the original hardware slows down at a certain point, emulators will too, because they are simulating the original hardware at the original speed. Other people have given this answer and good explanations, so I'll focus on something else. Old arcade and console games don't slow down with too many sprites, since the sprites themselves are actually generated using dedicated hardware. Ever wonder why the NES could only display 8 sprites per scanline? That's because it has 8 sprite generators. An NES generates each pixel in sequence and wires the output directly to the CRT signal (more or less), because that's cheap and efficient. Nearly all old consoles used this general pattern (and most arcade games). A simple example: each sprite generator is primed at the beginning of every scanline by being loaded with 2 important pieces of information, the x-coordinate of the sprite, and a row of pixel data. The x-coordinate is loaded into a counter, which specifically counts down. Every time a pixel happens, it counts down by one. When it hits 0, we now know that the pixel is at the right horizontal position on the screen to begin drawing the line. The pixel data is loaded into shift registers (1 for each bit of colour), which move bits in a direction. Each pixel after the x-coordinate is 0, the shift register moves the pixel data 1 bit to the right, and the current rightmost bits of the registers is used to decide which pixel colour to output for this pixel. That is then fed directly into the a \"muxer\", which takes all of the pixels for each sprite generator and also the background (tile) layer and then decides which pixel wins (normally the lowest numbered sprite) and goes to the video output. On the NES, the logic at the start of the scanline simply checks each sprite in the 64 sprite slots and loads the first 8 that exist on this scanline. It takes exactly the right amount of time, and always the same amount of time, to fit in the short time gap at the end of each scanline (the HBLANK). It can't load more than 8 sprites because there are only 8 sprite generators. If you are experiencing slowdown on these older games, it's because of something the CPU is doing (CPUs are not inherently time-bound, the sacrifice we make when we give them the ability to execute complex conditional programs, unless you are very clever with the way you program them). If the CPU takes too long to do everything before the next frame needs to be rendered, most old games will simply miss the next frame (but this is not always the case). It's actually very rare for these games to slow down, since they tend to be written in a way that everything always takes the same amount, or a very similar amount of time. It's actually for this very reason that we have to emulate them running at this slow speed, for example, Super Mario Bros relies on the exact speed of the CPU to count a number of scanlines and then \"corrupt\" the PPU (term GPU was invented later) at exactly the right time that instead of glitching everything out, it would scroll everything below the scoreboard independently. If the CPU was allowed to run as fast as possible, this code wouldn't work. Now, when we move to old PC graphics, PCs often didn't have sprite generators, instead they had screen buffers, a large (proportionally) amount of memory dedicated to remembering the colour of every pixel on the screen. Drawing sprites here means copying them into the memory directly using the CPU (or a co-processor which does the same thing but faster), this is commonly called **blitting** since you would typically use special Bit Block Transfer instructions dedicated to copying (and sometimes comparing) the data as fast as possible. Since blitting is now a CPU concern and not a pipelined hardware thing, our sprite drawing is no longer time-bound, and we could see slowdown with too many sprites. As game hardware developed, GPUs started to include programmable elements, becoming \"semi-programmable\", which would lift restrictions of fully dedicated sprite generators, but also lose the nice property of being time-bound (the better description is time deterministic). Now, our GPUs are largely fully-programmable, they are just large arrays of SIMD processors (a story for another day).",
"1. Consoles have very specific hardware components, and they don’t like running if anything is different. 2. Emulators simulate hardware components with software, and have to make the translation in real time. For example, a PS2 uses the MIPS instruction set, which is different than the x86 instruction set. So, the game outputs data in one way, then the emulator has to translate it so the computer can process it, then do the reverse and send the data back to the game. Basically, mimicking specific hardware = difficult, and adds processing time. Edit: thanks u/FailureToComply0 for being more specific. Modern computers CAN process the data quickly, but the game expects it to be processed at the original speed. To avoid ‘confusing’ the game, the emulator slows down the rate at which data is sent back to the game.",
"While we have some emulation pros in here: What's entirely possible with a 2016 i5 and 8 gigs of RAM, no dedicated video card? I've not done anything close to gaming for decades but am starting to reminisce about old console games on n64 and PS1/2 from my childhood. Emulation was always pretty messy - needed to download stuff from seedy places and it all felt pretty precarious/unstable. Have things gotten better and I could be playing some Turok or 1080 Snowboarding tonight?",
"Didn't see a link to it so I'll throw it up here... URL_0 This article does a pretty decent job, with examples, of what it takes to accurately emulate old games. Edit: Fixed autocorrect.",
"Some of the old consoles were really weird. The Sega Saturn was specifically designed to run sprite-based Capcom fighting games. The problem is that it came out as the Playstation 1, which made 3D games cool. In order for the Saturn to do 3D every polygon had to be a quadrilateral, which makes the geometry unlike any other console.",
"I once saw this asked and I will try to re-state the best answer that I saw. Imagine that an old game is a very old text, written in an ancient language. The hardware in the old systems were native to that language, they were fluent in it. Now imagine a modern system as a modern person. They don’t know the ancient language and aren’t fluent in it. They can translate it but translating takes a lot longer than just reading it as if they were fluent in the language.",
"There's two schools of thought on emulation and broadly it could be broken into, accuracy and improvement. Both sides in general still have the same goal: create a piece of software that can emulate as much of the hardware and systems for x-console as accurately as possible. Emulators are software forms of a console/hardware, so their a way of adding \"consoles\" into the internet's archives (often questionable) public domain(?). The accuracy bunch is all about making their emulator to perfectly emulate a system as close to hardware as possible; errors, lagg, slowdowns and all. Often these are the kinds of emulators you'd do a speedrun on as they have minimal cheating utilities and maximal authenticity. These emulators will often even include an option to link it to a BIOS for the console, taking the emulation from starting when the game boots up, to then when console boots up (important for some RNG manipulations; say in GB red/blue speedruns, using the known RNG to preform actions on certian frames to get precise outcomes; that couldn't work without the bios and overall accuracy in emulation); so if you had a bios, the emulator would turn onto the usual console's splash screen of [Gameboy] or [Sega] or [GameCube], with the little jingle+animations, whereas without a bios the game would just start playing on it's own start screen, without actually emulating the software running off the console itself, leading to a less authentic experience, that's unaceptable for the authenticity/accuracy emulators. Then there's the improve it/update it group; it's not like their emulator doesn't emulate the same system nearly as well, or as well, but it'll add modern features like; shaders(3d) or filters(2d), HD+ resolutions(not available on original), including different cheating devices built into the software like action replay or gameshark, and even up into unlocking the framerate (aka \"speed\" sometimes, depends how it's programmed). So in this unlocked/speed mode the game can run at 10s,100s, or in the case of 2d games on modern hardware, 1000s of time their original speed... Now no one can play a game at 1 frame IRL per minute IGT, in most cases, so instead of completely unlocking the framerate it's most commonly changed to a set multiplier.. like say if your playing pokemon on an emulator that just unlocks instead of has a set multiplier; that battle went like 200 times faster irl, but it also just took you like 20+ in game minutes for you to kill a single pidgey. Even if I was technically running at 8000-12000 fps(150-200x60fps), did it gain any real benefit over running at a locked 120 or 240 (2x and 4x)? So yes, the games can run faster on modern hardware, sometimes to the point it would be unplayably fast, but the goal of emulators are to EMULATE the old system in its entirety within a piece of software, that's including the original hardware's limitations and all; so in more complicated systems, you need a 'mod' for framerate or resolution changes. Take cemu (Wii u emu) and BOTW [I own it+100%ing it physical (116 shrine ~400 poops)... but kept up with the emulation because 1080p60/4k60 +shaders looks smooooothhhh]. Cemu needs external plugins, textures+shaders or whatever else to tell breath of the wild; what textures to use for the higher resolutions, how to use shaders and what shaders to use, or how to change it's max framerate without severely impacting the game (ie:playing back at double speed instead of going from 30 to 60 fps with the same physics and flow of time). They couldn't untie fps and physics up untill modern 3D PC/multiplat games on newer engines with high/variable framerates like 144hz/240hz/300hz, vsync,gsync, etc, all in mind. all of these are fairly new and either didn't exist or weren't casually affordable up untill the 2010s.... So then, no one was programming anything to go above 60, or oftentimes 30/24 fps from 1960s-2009(+/-), as they were usually designed for limited hardware; like a single console, or in the early days, even just a single processor/computer model.... ie:codes written in assembly, like NES/GB(C) games, are processor specific; as assembly directly writes instructions to the cpu(from a chart/graph), and the instruction sets (what the instructions did, were numbered,ordered,etc) weren't standardized between processors... (You can see how accuracy in something like a NES emulator's 6502cpu code is of the utmost importance) I hope that lightly covers emulation's core philosophies, also a little on programming (emulators and games), and how fps is usually centrally tied to the game engine/physics in most older games or console games... Tldr: emulators aren't trying to directly run an old game on modern hardware (although they allow it); their trying to accurately emulate a console entirely within software, flaws and all, because the more accurate the emulation is to the hardware itself, the better it is as an emulation platform (causing less new bugs and a more accurate experience). yes, most games could run at 100s or 1000s of fps on modern hardware, but FPS is more complicated than that; most (especially older) games have some link between the framerate and the rate the game is played at; this is usually just how the games are coded to render, because their programmed for set fps or only one specific piece of hardware (like a console). So often, without other adjustments to the game or emulator, upping the framerate is directly multiplying the speed of the game's playback. It's still a problem up into some modern(ish) 3d titles (namely mid series elder scrolls, botw a bit [on emulator]; normally it's games expecting a locked framerate that are unlocked anyways). Also worth noting: 95+% of consumers/gamers have 60hz (60fps) displays, don't *need* much more, even today, apparently.",
"I too have been playing /loving the snes rebirth on my switch. Childhood all over again... Just wish you could download the game and play it offline :(",
"I was wondering this while playing a link to the past yesterday on my Switch and noticed a huge drop in FPS when I got attacked by a swarm of bees."
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