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i4pv9r | Why do the pop ups on dodgy adult/ streaming websites sometimes take you to legitimate sites like Amazon or Netflix? | Surely those big legitimate businesses aren’t paying to be a pop-up tab on illegal streaming/ adult websites? | Technology | explainlikeimfive | {
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"they do not. it is most likely to take you to a website that looks like it so they can take your information.",
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i4q0va | What makes a 64bit OS better than a 32bit, and how does it relate to a bit? | Technology | explainlikeimfive | {
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"Imagine that you could only count using your fingers. If I asked you to count to 8, you could do it. But if I asked you to count to 12, you couldn't. And even if you could show me both 8 and 5, you couldn't add them together. Now, if you also used your toes, you could do both those things. That's basically the difference between a 32-bit and a 64-bit CPU. It limits the highest number they can represent -- though there are certain workarounds by losing precision , akin to using each finger to represent 10 instead of 1, you could count to 100, but you still couldn't show me 12 (there are other workarounds as suggested by some commenters, see below) -- and, more importantly, the amount of memory they have for operations. ---- #PS: Forgot to mention how it relates to a bit. The highest number a 32-bit CPU can work with is 2^32 which is roughly 4.2 billion. A 64-bit CPU can work with a number as large as 2^64, which is roughly 18 billion billions. ---- #PPS: Wow thanks for the silver, kind stranger. I didn't expect for this comment to explode the way it did. I'll take this opportunity for some clarifications. Those who pointed out that 8 + 5 = 13, you are correct. However, as u/bart2019 pointed out, I gave example one \"you can't count to 10\" and example two \"you can't add 8 and 5\". I believe my offence is esthetical, not mathematical. As some other commenters posted out (u/earthwormjimwow or u/dbratell) you don't necessarily lose precision when representing out of bounds values on a 32-bit system. There are other workarounds as well. ---- #PPPS: Many commenters are asking the same questions, so I'm going to address them. Some of these might be more than ELI5. I also took the time to format the edits for better readability. **But I can count to X with my 10 fingers using my knuckles, phalanges, a 10-bit system etc.** Even if you use a more memory-efficient system for representing numbers on your fingers than the standard base 10, you still have to face the physical limitation at some point. **64-bit systems are most relevant when addressing memory.** This is absolutely true. To continue with my analogy: you realise that instead of counting on your actual fingers, you could draw the position of your fingers on a piece of paper. That way, whenever I asked you what the answer was, you could just look at the paper and hold up your fingers the same way. Holding a reference to information like this is called *addressing* in computer science. You could even use more pieces of paper to represent more answers (to different questions or put them together to overcome the limitation of 10 fingers). If you use more pieces of paper though, how would you be able to keep track of them? Well, you would number them from 1 to 10 and count on your fingers to keep them in order. You could even have each piece of paper be a record of 10 **other** pieces of paper. Now you could count to 1000! The problem is instead of holding up your fingers instantly, you'd have to go rummaging through your papers to find the answer. If your papers addressed other papers, it would take forever. In a computer, the papers we're talking about is the RAM. In a 32-bit system, you can address -- without shenanigans -- a maximum of 2^32 bytes (I won't get into what a byte is, let's just consider it a unit of memory), which is about 4 GB (gigabytes) of memory. If you have more than 4 GB RAM in a 32-bit system, you most likely won't be able to use it all. In a 64-bit system, you can address much much much much much much much more. In 2010, the entirety of the Earth's digital information was estimated to be 2^70 bytes; that's only 64 times more than what you can address in your personal computer today. **Why don't we make a 128-bit system?** There are 128-bit systems out there, but 64-bit systems are more than enough for the processing memory needed, not just for everyday applications, but also for more specialised uses. Most of the time, supercomputers use a large number of 64-bit processors working in tandem to get the job done, rather than relying on a non-standard architecture. Also, designing more memory-capable systems is complicated, which would raise the cost of a 128-bit system with respect to a 64-bit system. You'd have to make sure that all the 64-bit (and 32-bit, for that matters) software you might want to use work on it properly. As a sidenote, some popular encryption algorithms use 128-bit keys. It might be profitable to have a small 128-bit processor (on top of your regular 64-bit one) whose sole purpose is on-the-fly encryption. Since it only has to do one job, it would be cheaper to design than a full-fledged processor, and being able to work with the 128-bit encryption key within a single registry would drastically speed up the otherwise lengthy process.",
"As easy as I can: the processor does billions of math operations per second. Those are made between numbers that are stored in memory cells called registers. The \"number of bits\" of the cpu is the biggest size of register, which means both the bigger number it can save and the bigger number it can do math on. Matter is, depending on what the program does, it may need to do operation with very big numbers. When you have numbers > 4 billions c.a, the memory size needed to store it (and calculate it) increases from 32 bit to 64. Now, if my computer has 64 bit system and processor, then making math between those large numbers is a native operation, and costs just one operation. But if you instead have a 32 bit system (meaning that the biggest calculation it can do is on 32 bit), but the program asks for 64 bit calculation, you can't, so instead the cpu has to go all the way around, splitting each operand in multiple memory registers, making multiple operations to achieve one single sum or multiplication. In everyday use, this kinda \"heavy stuff\" almost never happens, but apply that on heavy math software, cryptography and all sort of math things and the change is heavily relevant. Last note: as someone said already, another difference is that the same size of registers applies when the cpu asks the ram to save/load data. If you have 32 bit the biggest number is 4 billion and something, meaning the \"most far\" ram address it can address to is 4 Gb (which is little for nowadays use), whilst with 64 bit you can go beyond.",
"EDIT: My first silver! Thank you, anonymous redditor! < 3I'm going to TRY explain it like you're 5, please tell me if I succeed. I'm a bit rusty on my x86 architecture and I'm trying to get used to explaining to people in layman's terms how a computer works. - I may edit this several times. Firstly, the 'bits' can be described for simplicity's sake as a binary value, a 1 or a 0. in the lowest level of computer architecture, the 1 represents 'on' the 0 represents 'off' So 32-bits is essentially 32 1's or 0's. These are often summed up as a hexadecimal value (hexadecimal allows 16 numbers - including 0 to be represented in a single character, 1-9, and A-F) each hexadecimal value uses 4 bits, or half of a byte, to represent itself. so F is 1111 in binary and is equal to 15 in decimal. The maximum number that can represented in 32 bits is **0xFFFFFFFF** or **32 binary 1's** or **4,294,967,295**. Keep that number in mind, it comes in later.I could talk about binary maths all day, and how I got to that number, I absolutely LOVE IT!! but for now all you need to know is the math is correct. So, in CPU architecture, there are these little things on the CPU that hold data, they're called **'registers'**. Two of the main registers on the CPU are called the **'base pointer'** **'stack pointer'** registers, this is like a phonebook with addresses. You want to send a letter to a friend but only have their name, you can look them up in the phonebook and that'll have their address in. The base pointer divides the phonebook up into A-Z, while the stack pointer points to a specific person/address. that's the theory behind it explained as simply as I can go. The **base pointer** and **stack pointer**, however, point to specific addresses in **random access memory (RAM)** You'll see this listed a lot when you're in the market for a new computer, normally as '8GB RAM, so speedy!!' The issue arises, when you realise that in **32-bit CPU architecture**, these pointer registers can hold a maximum of **32 bits**. Because that's how it is physically designed. So the maximum address these pointers can refer to is **4,294,967,295**, each number being a byte of **random access memory**. If you convert that to **Gigabytes** you get **4.2GB**. This is the maximum amount of memory a 32 bit computer can look at. If you're old enough you might remember this being a thing back in Windows XP's hayday; \"32-bit windows can't see more than 4GB RAM\" now you know why. In **64-bit CPU architecture**, these registers are, you guessed it, **64-bits!** meaning the maximum value they can hold is **FFFFFFFFFFFFFFFF** or **18,446,744,073,709,551,615**. Meaning they can address **18,446,744,073,709,551,615 bytes** of memory meaning 64-Bit computers are capable of seeing up to **18,446,700,000** Gigabytes of RAM. The average consumer computer has 8, 16, or 32gb RAM to put that in perspective. So one of the primary benefits of 64-bit CPU architecture already is that the CPU can address SO MUCH more RAM, which is beneficial for a multitude of tasks in the modern day, including gaming, multitasking, rendering, etc etc. This will **only** work however, if you are using a 64-bit operating system. The operating system is specifically designed to utilize 32-bit or 64-bit architecture hence why you have windows 32 bit and 64 bit respectively. A 32-bit operating system cannot use 64-bit registers, even if they are present on the machine itself, because of how it is programmed. A 64-bit operating system, can, however use 32-bit registers, and can therefore run 32-bit programs just fine hence why you will have program files (x86) on your 64-bit windows OS. The **x86** denotes 32-bit **Intel x86 CPU architecture.** So you can probably guess that that folder stores all the 32-bit software. There are also other noted benefits of 64 bit architecture, such as the enablement of multiple cores on the CPU or in some cirucmstances, multiple CPU's, because of similar reasons as noted above, and the handling of those multiple cores in x64 programs is much more efficient, so you get faster overall performance. That hopefully sums it up easy enough for you, please let me know if you have any further questions or if I was unclear.",
"People have already explained how it's about the usable memory that's the thing. But how it relates to a bit is this: Every byte of memory needs an address to be usable, and a 32 bit address book has 2^(32) addresses, and 64 bit has 2^(64) addresses. 2^(32) = 4\\*2^(30) = > 4 gigabytes. 2^(64) = 16\\*2^(60) = > 16 exabytes. So, in order to hit 64 bit memory max with 128 GB sticks, youd need 2^(27) or about 134 million sticks. Good luck finding a suitable motherboard. Also operating systems don't actually support that much. But they could.",
"In ELI5 fashion, the main big difference is how high you can count. In bigger answer fashion... Look at your left hand. With five fingers (usually), you can count to five. You can use that for counting, or simple math, or similar things. Add your right hand, and you now have ten fingers (usually), and can now count to ten, or do a little bit bigger math. The \"bit\" is when those fingers have different values by position. Doing math that way, where you only count fingers that are \"up\" is missing opportunity. If we use only \"up\" or \"down,\" we have binary bits, and can actually count to 31 on our five-fingered hands, or a 1023 on both hands. Looking right to left, as we're comfortable with our decimal positions, your right-most finger is 1, the next is 2, then 4, and so on. The right-most three fingers up, the rest down, gives you 1+2+4, for a total of 7...on three fingers. Adding one more results in that \"carry the one\" action we do in decimal math when we add 1 to 9 to get 10. You have one ten and zero ones. Adding one to our seven means we turn off our one one, and carry the one to the two, which we turn off and carry on one to the four, which we turn off to turn on the next one, giving us one eight. So then just our fourth finger is \"up\" and the rest are \"down.\" We use the same \"up-down\" concept in computers, but more \"on-off\" or 1s and 0s. Counting from one to five is then 1, 10, 11, 100,and 101. Early computers used 8 bits, counting easily to 255. The next shift was 16 bits, giving us a limit around 64 thousand. Having 32 of these bits allows us to count to around 4 billion. Having 64 allows us to count on to about 18 million billion. This helps us do bigger or more precise math. As we look at how computers store things, like how that numbering is used to address memory, it allows us to have more. It'll be unlikely with today's technology to build systems with that much addressable memory, and power it with electricity, and keep it cool... We're probably approaching 64 bits of storage on the planet, but not yet RAM, in all computers combined. Still, opening the floodgates after 4GB of RAM in a system allows for the rich graphics and full features of the applications we have today. The next doubling to 128 bits will not likely be necessary, at least for the purposes of RAM. Especially knowing we can't build RAM systems that big, it's unnecessary to consider. We have always been able to do math operations on multiple bytes, so when our 8-bit numbers got too big, we'd use two or four or whatever. For almost all purposes today, 64 covers all but the largest or smallest values, and adding another 64 bits will do the trick. We've done the same trick for addressing large storage, which is how even 8-bit systems addressed more than 255 bytes of memory or storage. Doing it in one block of bytes is just more efficient. We do use 128 bits in IPv6 addressing. However, to put that in perspective, that should allow us to uniquely and individually address each atom on the Earth, with room to spare in our address pool for more planets. About a hundred more Earths.",
"It deals with how much memory you can give to a process. Applications these days can need a lot of memory! Say you can only put one thing in a storage box, and on an index list you have a two character limit to list which box carries what. With two numbers you could keep track of what's in 100 boxes (00 through 99). If you increase that to four, you suddenly can track 10000 boxes, (0000 through 9999), two orders of magnitude more! Computers use that kind of indexing to keep track of where the ones and zeros are stored. The 32 bit address space allows for a maximum of 4 gigabytes of memory to be kept track of (2 to the power of 32). Modern computers often have much more then this, so if you only had a 32 bit operating system, you wouldn't be able to use all that memory without some inefficient workarounds. 64 bit raises that maximum to 18 exabytes (that's with 18 zeros, coincidentally), which should be enough for the foreseeable future.",
"A 64-bit Os is not inherently better than a 32-Bit OS but It can do one thing that a 32-Bit OS can't do: Work with more memory. You may think about it like this: You have some bank form where you have to write in per hand with a pen how much money you would like to transfer. In the field where you write in how much money you want to transfer onne form has room for 4 digits before the decimal point and the other for 8. Obviously the 4 digit form maxes out at $9,999.99 you can't put a larger number into that field. $10k is the max. The other form with the bigger field allows you to write in numbers up to $99,999,999.99 or almost $100 million. As long as you don't want to transfer $10k or more both forms work the same. But the form with the bigger filed allows you to go beyond that limit. So the point I was trying to make with the metaphor was that more digits equal the ability to use larger numbers. The computer uses these numbers to address things in their memory. If you have an address field that has room for 3 digits for the street number you can't go beyond house number 999 on that street. So more digits equal the ability to use larger number which allows you to address more things. A 32-Bit Os has the ability to uses addresses 32 digits long. Unfortunately those are binary digits (bits for short) not our normal decimal one. The largest number you can write out with that is something a bit more than 4 billion. It allows you to address 4 Gigabyte of memory. If you are only ever going to use 4GB of memory that is fine. If you want to use more memory you run into problems. A 64-Bit OS can address much more memory. 18 Quintillion (16 Exabytes) This is going to be enough for the foreseeable future. TL;DR: Bits are Binary digits, the more digits you have the large number you can write. You need to write large numbers to address large amounts of RAM.",
"And, if 64bit is better then why not just go to 128bit or 256bit. Is there some reason it needs to be so incremental? Why not just go boom, 4096bit!",
"A 64-bit OS isn't always better, but when it is the reason is usually the same as why having more numbers in a street address is better. Imagine a short road in a small town, with two digit numbers for the street address. 01 through 99. If you wanted to make the street longer, and build house/lot number 100, you'd need to go to three digit numbers. In bigger cities and longer roads, with more desire for flexibility, you might want 4 or 5 digits. (And the same applies to telephone numbers.) Computers don't count the same way humans do. They use binary, ones and zeros. Each 1 or 0 is called a bit, so a 32-bit number is 32 digits that are all one or zero. How many bits an operating system uses determines a lot of things, but the most important is keeping track of where memory is stored. Like house numbers, memory in a computer has addresses. An OS with more bits can keep track of more specific locations, just like more digits in a street address can keep track of more houses.",
"Everyone writing answers explaining the difference between 32 bits and 64 bits is right, but they're missing half the story. The real answer is that \"32-bit\" and \"64-bit\" don't mean just bits. When we say a CPU is \"64-bit\" what we mean is that it is a completely new type of CPU compared to its 32-bit counterpart, that speaks a completely new or evolved programming language, and has more features beyond the number of bits. The number of bits changing was just a convenient excuse to break backwards compatibility, and improve a whole bunch of other things at once. When talking about PCs, Macs (so far), servers, and some tablets, this is what the terms mean: * 32-bit: Intel x86 CPUs (also called i386) * 64-bit: AMD amd64 CPUs (also called x86-64) Intel invented the 32-bit version (they were 16 bits before!) in the 90s and AMD copied them; AMD invented the 64-bit version in the 2000s and Intel copied them. amd64 CPUs are backwards compatible and can pretend to be an old 32-bit CPU, but if you use them that way with a 32-bit OS, you don't get any of the benefits. A lot of things got improved in 64-bit mode, such as how many things the CPU can work on at once (double the number of \"registers\"), the availability of high performance features for working with numbers with decimals like SSE2 (this existed in some but not all 32-bit CPUs, but all 64-bit ones have it, so all software can assume the feature exists and use it automatically), new faster ways of communicating between apps and the OS, and more. When talking about phones and other tablets, and upcoming Macs, we mean: * 32-bit: usually ARMv7 (AArch32) CPUs * 64-bit: usually ARMv8-A (AArch64) CPUs The story is here is similar, except AArch64 changed even more compared to AArch32 (they did a clean break with the language the apps are written in, while in the Intel/AMD case they just changed some parts). AArch64 CPUs have more features, working registers, etc, and all this helps speed up software. So really, 32-bit and 64-bit are just labels. They have some meaning, but you might as well call 64-bit just \"the next gen\" and you wouldn't be wrong.",
"Think of 32 bit as a 7 digit phone number. There are about 8 million valid combinations. Think of 64 bit as adding a country code and area code to that 7 digit number which creates an addressable universe of trillions.",
"Say I give you a light switch You can turn it on and off. Then I give you another light switch. Now you can turn: * Light 1 on, Light 2 on * Light 1 on, Light 2 off * Light 1 off, Light 2 on * Light 1 off, Light 2 off so that's (2)^(2) = 4 combinations of lights being on and off where (2) is the on/off, and ^(2) is the number of light switches. Now I give you 64 light switches to play with. ... Exactly.",
"It's like phone numbers. 32 bits is like 7 digit phone numbers without an area code. 64 bits is like 10 digit phone numbers with an area code. Now imagine you called each person and told them to remember one thing. With a 7 digit phone number you could only call a medium city's worth of people. With a 10 digit phone number you can call the whole country and remember more stuff at once. All the programs running have to remember what they're doing so longer numbers lets more and bigger programs run at once. A bit is like a digit but instead of going from 0-9 it goes from 0-1. It's called a bit because it's a binary digit.",
"In computing you have 0 and 1, so in 1 bit computing you have two possible values. In 2 bit computing you get 4 possible values and onwards. Basically then you get to 32bit with over 4 billion possible values and 64 bit with over 18 quintillion values. So yeh there is a big difference to what the operating systems can allow the CPUs to do. Now as to what you as an end user will notice. A few years ago(maybe 10) that wouldn’t have been that much, whether you had a 32 or 64 bit OS wouldn’t have made much difference. And even now you will only lose a little bit of functionality that you may not even notice. However one of the biggest changes is the amount of ram that can be used. This is 4GB for a 32bit is and is 2TB for a Windows 10 64 bit OS. Like I said, up until a few years ago we would have only really had a max of 2-4GB of ram installed. These days 4GB is really the bare minimum with 8GB being an OK amount with the 16GB being required for games to run ok."
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i4t59g | Why the iPhone 7 can record 4K video, and record at 240 FPS, but not at the same time. | The iPhone 7 can record 4K video at 30FPS, or 720p video at 240FPS. Why can't it record 4K at 240FPS? | Technology | explainlikeimfive | {
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"it's not neccessarily about file size, the clips need not be very long and slow motion footage can usually be compressed very efficiently. it's about data rate. uncompressed video, the way it comes out of the image sensor (this is simplified) produces width x height x framerate x bit depth x 3 (rgb) bits of image data per second. assuming 8 bit color resolution (a low standard), we get those numbers: 1920x1080 (full HD) at 30 fps: 1.5 billion bits per second or roughly 190 MB/s 3840x2160 (4k UHD) at 240 fps: 478 billion bits per second or roughly 60 GB/s That's almost 50 times the raw speed of USB 3.1 (latest generation of the USB standard)! This data isn't stored anywhere, but it needs to be processed (again, very much simplified), and there's just not enough data bandwidth nor processing power in any current smartphone to accomplish this. But we're getting there."
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i4uy69 | - Suppose we search something using Google and click on a result. Supposing we just browse that site and search for things there, without giving any personal information directly, what informations can that company extract from our visit that can be used to track us? | Technology | explainlikeimfive | {
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"Firstly you give away your IP address which is linked to your Internet Service Provider and very often to your rough location within your city. The browser is also very helpful in giving away information to the website. It informs the website you came from google and the exact search term you used. The browser version and all plugins and operating system along with a few settings such as language and screen resolution is also sent, in most cases this is enough to make you uniquely identifiable on its own. The website can also track timings such as how you scroll and move around. This can help find out what hardware you use and can also be used to guess your age, mental ability, state of mind, etc. It is also common to include elements from social media sites such as Google, Facebook, Twitter, etc. If you have visited these before or other sites using elements from them your browser will send cookies so you can be recognized. These sites can also sell the aggregated data back to the website allowing them to link you to information collected on you before from other websites. Some of us do have the problem that just visiting a site and not leaving any information will in many cases result in getting cold called from the exact company offering us to buy product. It does not help using a VPN or disabling cookies as there is still plenty of information identifying you. In fact using a VPN can increase their accuracy as it allows them to distinguish between different people sharing the same IP address and the same hardware and software setup which is common in companies. The only thing that helps is to use Tor Browser Bundle which is a version of Firefox that is designed to be as common as possible, this includes window size. And always start a new session to get rid of any identifiable information you might have left."
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i528m4 | Why do we need different programming languages? | Technology | explainlikeimfive | {
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"For when you want to do different stuff, or are fed up with an existing language's shortcomings. That's... kind of the best response you'll get that's even remotely suitable for /r/eli5, sorry. You have languages like Javascript which are useful for web design, C++ is better for in-depth development, Kotlin is better for android apps, Typescript is useful for if you want to use Javascript but also hate how shitty Javascript is, COBOL is useful if you work in a bank, hospital, or government agency where your computer was built in the cold war.",
"/u/Rammite is correct that there are reasons different ones may be better in different situations, but XKCD also has an answer to this: URL_0 New programming languages are developed to address shortcomings or complaints of other languages, but even if they are better in some way, they rarely *replace* the old ones because people are used to using the old ones, and existing software works with the old ones, so these developments may create new and better options, but do not simplify or reduce the number being used.",
"I'm no expert, just a computer science student, so take my words with a grain of salt. It boils to tradeoffs. I'm going to use video games to help demonstrate things. We need super low-level assembly to talk to the hardware and tell it to do super basic things like print text on the screen. Sure, you might be able to theoretically use something higher, but it would be slower, which is bad at that level. Or maybe you don't have a higher-level compiler yet and have to use assembly instead. For older consoles like the NES and handhelds like the Game Boy, assembly was the language of choice to squeeze as much power as possible out of limited hardware -- processing power and storage. Fast execution, but you have to really know how the particular hardware works, know operation codes for all the important instructions. It's a pain. Next, there's the level of C, C++, and the like. Assembly is telling the basic hardware what to do, and then C, which is used in operating systems and base utilities, comes higher up. C is fast like assembly -- basically wrappers around assembly -- but much, much easier to read. It abstracts away, or hides, details so the developer doesn't have to worry about them. Programming everything in assembly used to happen, before C existed, when hardware was all different. But assembly programming is slower and more error-prone. C is easier to develop, read, and fix. That gets the OS -- Linux, Mac, whatever -- running, as well as many programs. Older PC games are probably written at this level. Modern game *engines* come at this level, supplemented by... Scripting languages. Generally interpreted, these are higher level than C and other compiled languages. This makes them more friendly -- theoretically *cough* JavaScript *cough* -- to developers and such. Python is an example of a good scripting language. Easy to learn, easy to develop and fix. The tradeoff is execution speed. You can make good Python code that's reasonably fast, but not as fast as C or assembly. And that's generally okay. Here's where game logic and behavior might be coded nowadays. As for different languages within a level of abstraction, it depends on the application. For instance, aviation hardware, I understand, uses different low-level code instead of C because C can be tricky and run into errors that might be fatal in the application. Someone else can probably give a better explanation."
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i543wz | Green screens, why green and not any other color? | Technology | explainlikeimfive | {
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"It's not only green. Blue (and other hues) are also used in \"green screen\" technology in movie special effects. It's just that green (or blue) are colors that are the furthest from human skin tones, and therefore the least likely to \"remove\" or overlay the actor's skin in the special effect.",
"You can indeed use any other color. Certain shades of blue are oftentimes used as well. The idea is to use a color that you're absolutely not going to have show up in your scene. Florescent green is pretty rare to have in something you want in the foreground - usually a person/person's clothing."
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i58lbg | How does a higher refresh rate in cell phones make them superior? | Technology | explainlikeimfive | {
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"because higher refresh rate means smoother animation for interacting with your phone. think about it this way. 60 hz = 60 pictures in 1 second. while 90 hz = 90 pictures in a second. therefore, before the image changes every 0.016second, now it's 0.011. some people say you can really see the differences, some people say it's like a placebo. best thing to do is just to try both."
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i59ays | how can laptops fit over 1tb of storage and 16gb of ram in a tiny chill while PCs need massive ram sticks and often large SSDs? Why isn’t PC ram as small? | Technology | explainlikeimfive | {
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"The main reasons why PCs are larger are ease of access and cooling. Cooling is very important to improve performance and durability. If you make everything small and cram it into a small space, you can’t have good cooling so the system will have to slow down as it heats up. The bigger your RAM stick is, the faster it can dissipate heat. The more space you have between your parts, the more airflow and cooling you get.",
"Laptops either use denser RAM (which costs more), or save space by soldering it to the motherboard. You can buy [128 GB RAM in a single module]( URL_0 ) right now. It's just... pricy.",
"Making parts smaller, which increases price. And by positioning parts parallel to the motherboard as opposed to perpendicular, which isn't that good for the lifespan of the parts due to bad heat dissipation etc. Also laptop versions of GPUs also usually perform worse than their full sized counterparts.",
"If you open a 2.5\" SSD, you will see it is mostly empty, and not much biiger than an M.2 SSD.",
"The 2.5\" drive and ram DIMM sticks are more about standardization than not being able to make them smaller. Cell phones have everything soldered to the mainboard. Pcs can do that as well but then you lose all customizability."
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i5aphb | Why does research take so much computing power? | I always hear about scientific research needing crazy amounts of computing power but I have no idea why. As someone with an interest in hardware, I’ve always been intrigued by this. | Technology | explainlikeimfive | {
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"A lot of of problems that come up in science are not solvable by straightforward algebraic methods. Things like protein folding, fluid dynamics, stress/strain, gravity/orbits with multiple bodies etc end up with fairly complex differential equations. In the past, the only method was do make a lot of simplifying assumptions in order to make the problems tractable. As computers develop, there needs to be fewer assumptions and the computer could do a lot more grunt work calculations to get more accurate answers. But there are still classes of problems that are best approached using simulation. These generally require stepping forward in small increments (usually time) and solve the state of the problem, then step forward in time and use the end result of the previous stage to calculate the current state. This requires huge amounts of computing power if the time steps are small and if the systems for each state are complicated (say modelling movement of all the stars in the entire Milky Way or weather patterns). Then there are classes of problems requiring optimization - for example complicated molecules like proteins can be \"folded\" in many ways (think in terms of trillions and billions of ways) There is no way to predict what \"works\" so each configuration has to be simulated separately and tested. Then there are just the complicated observations (say astronomy) and experiments (say the LHC) which generate terabytes and petabytes of data. It would take thousands of years for a person to analyze the data by hand to extract meaningful data and patterns that might be useful. Some of the examples in research that take advantage of computing power.",
"It really depends on the research. This is not always true. But the thing that is most often the common cause is **algorithmic complexity theory.** This makes many problems inherently slow to compute. To the point that we were never able to compute them at the scale and precision we wanted to. And as computers get a lot faster, we just use them to compute less approximate solutions to larger problems, the way we always wanted to but only now can. For example sorting a list. The most naive approach could do it in the time proportional to the square of the number of elements. You just go over the list from left to right and compare them two by two and always push the larger one to the right. Then you do this again and again. If you do it as often as there a re elements in the list, your list will be sorted. So if sorting a list of 1000 names alphabetically takes a second. Then sorting 10000 names would take 100 seconds, 100 times as long for only 10 times more input... 1000 times more input means a million times more computation... There are less naive algorithms for this problem in particular, they are faster, but this is not always the case. Squared complexity like this is not the worst you can encounter. For example, if you wanted to know the best sequence of visiting the 5 clients you need to visit, then the best and only way we know is to try all possible combinations and chose the best. So for 5 clients, that is 5 x 4 x 3 x 2 x1 = 120 possibilities. Annoying by hand but no problem at all for a computer. For 10 clients, there are 3.6 million possible combinations. For 15 clients over a trillion. That's already the territory where modern computers will take a long time to compute those, and the input size of the problem was moderate. This phenomenon is called **combinatorial explosion**. There are also approximate approaches that do not guarantee you to find the best solution, but will compute a lot faster.",
"in phylogenetics, the more traits you have, the more accurate your systematic tree gets. the more species you include, the more relevant it becomes. however this generates an exponentially growing amount of trees which all have to be compared and evaluated.",
"The sheer complexity and size of some data can be overwhelming. The CERN LHC for instance creates 1 billion collisions each second. It needs to process each of those in extreme detail and then make a quick decision on which to actually save and which to discard as uninteresting, billions of very complex calculations every second. Then it needs to store the data it does keep, which has passed 250 Petabytes of data. They have over 200,000 processing cores to handle that and like 90,000 hard drives connected. When you think of just how many particles are in even a very tiny thing, and you're literally trying to track all of them you can see how its insanely complicated quickly.",
"Some good and correct answers in this thread, but not really ELI5. Scientific computing is like playing multiplayer games on servers that increase the player cap to an absurdly high number. You're forcing the computer to deal with figuring out a bunch of things over and over like: Are players bumping into each other? Using their weapons? Where are the weapons pointed at? What other items have they equipped? This easily overwhelms the hardware and you get lag. Instead of players in a game, in scientific computing you might have thousands of atoms that each have position in 3D space, velocity, direction of motion, electric charge, and so on. The principle is the same: The computer need to figure out the answer to a huge amount of questions. However, in science real-time interaction is not so important, so \"lag\" in the form of calculation time is fine."
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i5ce1s | why do disc copies of videogames take up as much storage as digital copies? | Technology | explainlikeimfive | {
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"Because the disc is only used to install the data onto your console's hard disk. Unlike previous console generations the game doesn't read data from the disc directly. Once the game is installed the disc is only required as a license check. It checks the disc is in the drive so it knows you have a legitimate copy of the game.",
"Current generation of consoles require that games be installed to the local harddrive, rather than running off the disc, since harddrive access is significantly faster than disc access."
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i5ez68 | - A Browser has two modes: normal and private (incognito). From the point of a site trying to track a user what exactly changes? What informations the other side cannot track from the user when they are browsing incognito? | Technology | explainlikeimfive | {
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"Not a thing changes. Incognito Mode only changes what data the browser stores *locally* -- it can't and doesn't control what data the remote site tracks. Edit: Technically, the remote site won't be able to read whatever cookies your regular session might have, and it may have a harder time associating that data with you specifically, but in terms of the data generated by that session, the remote site tracks it the same.",
"A simple example: the reason why you don't have to log in again every single time you go to Reddit, is because the website reads a cookie on your computer. That cookie has your ID in it, the website recognizes it, and automatically logs you in. When you visit Reddit in incognito, you're not automatically logged in, because now the site doesn't read that cookie. Fun side note: my friend and I were able to login as each other, without even knowing each other's password or username, just by editing that cookie to each other's ID."
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i5fw81 | If music streaming services like Spotify can catalogue and offer the vast majority of popular music internationally regardless of label, why are there no video streaming services that have the vast majority of TV shows and movies on one platform too? | I could imagine piracy would decrease if people could be offered video content of the same variety and volume as music streaming on a single platform, bundled into one monthly fee. It seems like platform exclusives are a thing of the past for music, like when Beyonce initially streamed Lemonade only on Tidal. Why do I need to buy Netflix, Hulu, Disney Plus, etc. to watch all my favorite content but I don't need to have a concurrent Apple and Spottily subscription to listen to my favorite music? | Technology | explainlikeimfive | {
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"Spotify does not have an internationally open catalogue, it just so happens that what YOU listen to is licensed internationally. Some songs/albums on Spotify are available only within certain regions. Beyoncé streamed to Tidal because her husband OWNS Tidal, it would make sense to leverage their own talent for their own platform."
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i5hmxi | How can a government ban specific web sites | I don't mean legally. How would the US government practically block a web site? Do they just tell all of the service providers to block that traffic, or are they in control of the actual wires that bring the traffic in from overseas? What about satellite internet? | Technology | explainlikeimfive | {
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"Think of it this way. When your computer tries to access a website, it sends a message packet to the website host server. It's like a letter you send to some one requesting something from them. Now if the server wishes to give you access, they will send the data( the website page data) back to your address. When you're computer gets it, it will decide if and display it on your screen as a webpage. Now, if a government wants to ban a site, they will ask the ISP ( same analogy to the post office) to not deliver any requests (letters) to them. There are way too bypass the ban and access the site but that's not the point of discussion here."
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i5j2mr | How is glass an isolator but fibreglass is used for e.g. fast internet? | This question popped up while reading this physics article which mentioned that glass is an isolator. Please correct me if my way of thinking is wrong! Admittedly I have super basic understanding of physics and no understanding of how internet access/networks work... looking forward to your responses! | Technology | explainlikeimfive | {
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"Fiber-optic internet doesn't use electricity, it uses light. A thin glass fiber will keep a beam of light within itself over long distances, and the signal travels at the speed of light. So electric data is turned into flashes of light at one end, transmitted, and re-translated into an electronic signal at the other end.",
"I think you mean insulator. Insulators can be thermal insulators (heat transfer difficult) or electrical insulators (electricity). Fibreglass is both. This means it doesn't conduct electricity. Fibre optics works on the principle of total internal reflection of LIGHT. Light enters the wire and is reflected multiple times and is transferred on the other end as it's angle of incidence exceeds the critical angle (minimum angle for TIR to happen). This is also why cut diamonds are so brilliant. Light transmitted is converted to electrical signals.",
"Fast internet uses glass fiber, but it's not fiberglass. That sounds picky. :) Fiberglass is a building material, commonly used in insulation. Like a wooly shirt made of many small glass fibers. Fiber internet, on the other hand is a single very long glass fiber, like a single strand of spaghetti, or more commonly a cluster of such fibers. These fibers use light, rather than electricity to transmit the data. This light is pulsed extremely rapidly to transmit data, with multiple light frequencies used to transmit data simultaneously on the same fiber. Since it's light (optic) and not an actual electrical signal, the very high resistance of glass is not a barrier."
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i5ly61 | Why is it when you watch a tv show or a movie at home, when characters are talking it is really quiet, but music and sound effects are really loud? | Technology | explainlikeimfive | {
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"movies are mixed in surround sound (5.1 or higher) dialogue is usually in the center/ sfx and others in rear channels and left right tvs that only have one or two speakers can't properly play 5.1 so it down mixes it to 2 channel audio and what you get is low dialogue drowned out by music etc & #x200B; you're trying to output 5 channel audio into something that only has 2 channels, so what you get won't be ideal and this is the result",
"IIRC it's because they are mixed for surround sound systems and thus the speech comes out the center speaker, so if you have surround then turn up your center speaker. Or if stereo, and if possible, set the output to downmix to stereo from surround",
"Because apparently the sound mixers for tv and movie never actually watch tv or movies at home.",
"Dynamics. Modern music is mastered to have no dynamics, so even the 'quiet' parts are loud. Movies don't do this, they maintain proper dynamics.",
"TV? Why in the hell can't my effing computer make a consistent level of sound?!?!? You'd think by this friggin' time of computer advances I would not still have to adjust 3 god-for-saken volume controls every damn day."
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i5mdrf | How hard is it to create stable game servers? | It seems like every new game that is released have problems with too many users in comparison to plan, making servers crashing or creating lag. Most recenty Fall Guys and Wolcen from my experience. Or a new release aside, take alomst any excisting game - most has server lag from time to time. I don’t know anything about creating a game server, but how hard is it to create a stable scalable game server? And aren’t there services like Azure or Amazon Web Services or Google Cloud Platform that they could buy into and scale the game on? Why/why not? Thank you in advance, Redditors! | Technology | explainlikeimfive | {
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"Technically, not that hard. There are solutions, as you mention, from several tech experts. Business-wise, it's super hard. All these technical soluyions cost money. The company has spent tons on writing and deploying the game. They finally have some cash flowing in, they are not going to go broke. Now you want them to spend on a lot of servers. If the load levels out at a high level, they might make money in the long run. But if the game usage goes down, they never make any money.",
"First of all, there are two infrastructures for gaming. One is a central server that does everything, and the other is a matchmaking server that gets you a group of people to connect with directly peer-to-peer. If it's a peer-to-peer game, like Mario Maker, the stability really depends on the weakest connection. For servers with central hosting, it's about capacity planning. You might expect that you'll have 10,000 people playing at any given time, with surges of up to 30,000. That means most of the time you'll have enough equipment idle for 20,000 connections. Trying to reduce the amount of resources you're paying for but aren't using is important, especially in small indy games like Fall Guys. As for why they don't use cloud hosting, it's about the architecture of game servers. Most game logic runs in a single threaded application to ensure consistency. You have to evaluate every single 'tick' in a game completely before doing the next, or you might not update a player position in time for a headshot to be calculated correctly, for instance. Cloud computing is built more with the idea of \"go wide\" and not \"go tall\". You can have an autoscaling web application that can handle every person shopping on Amazon at any time because each of them doesn't have a direct impact on the others. The same isn't true for game servers."
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i5oa3k | How are the new, smaller SSDs different from regular SSDs? | [Example]( URL_1 ). How do they differ from the [normal]( URL_0 ) SSD? | Technology | explainlikeimfive | {
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"Those smaller SSDs connect to a special port on the motherboard, the m.2 port. Electrically, you have two different types: a regular SATA m.2 drive, which is in effect no different from a \"normal\" SSD other than the port it plugs into. However, the m.2 slot also allows for a connection type known as NVMe (non-volatile memory express), which is a much faster connection type that uses the same PCI Express channels that your graphics card uses, allowing much higher data transfer rates directly to your CPU."
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i5r9ae | Why aren’t all disc-based video game systems backwards compatible? | Technology | explainlikeimfive | {
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"text": [
"Different operating systems. Don't think different languages think different dialects. They are similar enough that some data can be extracted but not enough to make complete sense making the game unplayable."
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i5ribs | How are phones and other electronics waterproof only up to a certain depth, which is usually shallow like 3m at most? | Technology | explainlikeimfive | {
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"Water starts pushing harder and harder the deeper you go (pressure). They can only seal up a watch or a smartphone so tightly while keeping it sleek and stylish, as well as practical. The depth rating is because the pressure at the rated depth is the nearly the maximum of what the product's seals are designed or guaranteed to withstand. You're only waterproof to a certain depth, too. If you went deep enough, your seals would pop, which I imagine damages your internal mechanisms pretty badly.",
"For a phone 3 meters of water is quite a lot, that's being dropped into the deep end of a pool The reason you see so many devices rated for 30 minutes at 1 meter or 30 minutes at 3 meters is because those are the common Ingress Protection tests defined by IEC An IP67 rated device is completely dust proof and water resistant for at least 30 minutes in 1 meter of water *when new*. An IP68 rated device is again completely dust proof (dust ratings top out at 6) and water resistant for more than 30 minutes or at more than 1 meter, commonly it's tested for 30 minutes at 3 meters. But this doesn't mean the device is completely water proof. Most phones have coatings that help keep water out but more time or more pressure will push the water past those seals and let it get to critical parts. Realistically your phone needs to withstand a quick drop in a toilet or puddle after two years of constant wear and tear which is a very different design goal than making it work for 30 minutes at 30 meters when fresh out of the box",
"It’s water resistant not water proof, they can resist water damage from rain or spills or getting briefly dropped in water, things that could most likely happen in a regular persons life, although timing them underwater is an interesting way to measure that",
"Because that is how the manufacturers design them. It is not terribly difficult to make consumer electronics 100% waterproof at a depth of 10m or more. But that would require a MUCH bigger (and more expensive) device with outer chassis and seals that most consumers likely would not want to carry or purchase. *EDIT: I bad speler.*"
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i5t1e4 | - How do refrigerators and freezers keep things cold? | Technology | explainlikeimfive | {
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"If you compress some gas a lot, it will liquify. It will heat up quite a bit as it does. If you then wait a bit until it returns to its original temperature, you can then let it expand and boil off back into a gas. This process causes it to cool off significantly. Refrigerators will compress it, move it to the heat sink (normally at the back), then once it reaches room temperature it is pumped into the fridge/freezer where it boils off (still within pipes) in the cooling coils before returning to the compressor. This cycle keeps the cooling coils (and thus the rest of the fridge) cold, while the outside heat exchanger gets heated up."
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i5u144 | why do computers have to restart in order to install an update? | Technology | explainlikeimfive | {
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"Because you can't make critical changes to a computer while it is still in this. This is equivalent to replacing your car engine while the car is still running.",
"computers don't have to do that. this is a software limitation that's not shared by all operating systems",
"The operating system consists of a lot of different files. When the computer is up and running, there are a large number of files that will be copied from the hard drive into memory no matter what you are doing with the computer. This copying is done during the booting up process. Other files only get copied into memory when needed. When you update your computer, not only are you changing a lot of those files that would get loaded when booting up, but you are also, in many cases, changing the relationships between them. For example, you might have a file of instructions called A and in those instructions there is an item that says \"go read the contents of file B, do any instructions in B and then come back to A\" As part of the update, the computer might get a new version of file B (call it B 2.0), or it might get an entirely new file to be used in certain situations. So file A needs to be changed to include pointers to file B 2.0 and instructions for when it should go to file C instead. Now imagine that file C is one of those files that doesn't always get loaded into memory, but is instead called up only when needed. The version of A currently in memory doesn't make any mention of C, so it will never be called and it has the wrong name for file B, so it will crate an error when it fails to find B. A given update may be changing hundreds or even thousands of these files. The best way to make sure the computer is using the right ones is to throw all current stuff in memory away and restart from scratch."
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i5w6eo | Why do most famous tech youtubers these days recommend/support AMD processor laptops over intel ones? | Technology | explainlikeimfive | {
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"Ams and Intel are competitors each battling over the budget/mod tier/enthousiast market. AMD released the ryzen series not only being better than Intel but also kicking hem out of the market because they are cheaper and more powerful than Intel processors.",
"Pretty simple; AMD is manufactured with *smaller* transistors. Physically smaller transistors need *less* electrons to switch them. Less electrons = less power = more efficient. And smaller transistors generally can be switched faster than larger transistors. Faster, less power, and cheaper. There are other reasons besides - but basically the move to small transistors gave AMD a huge edge over Intel at this point in history."
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i5xz0t | Why are these realtime high resolution colorful super X-Rays from the airport not used for medical X-Raying? | Technology | explainlikeimfive | {
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"X-rays at the airport are trying to look through your clothes. They are not trying to go deep into the skin. X-rays at a hospital have to be able to go through the skin to see what's underneath, often with some level of adjustable \"depth\".",
"There are no “high resolution super x rays” at the airports. They are very low resolution x ray machines and the color you are seeing is for “post processing”. It separates organic and inorganic material in different colors to tell the difference. High resolution machines are not Xray machines but CT machines that allow a 3D image of the item to appear. They are very new technology and govt agencies such as TSA are just starting to depoly them across the US. They are two very different technologies and require different training. Medical X-Rays are stronger and are designed to see through the body like u/Xelopheris says. Airport xrays are designed to look for weapon or bomb components.",
"The airport xray wants to figure out the difference between metal and human organic stuff, which is like walking through a door. The hospital one has to find the difference between organic matter and organic matter inside the human, which is like a double reverse backflip through a door. (X-Ray contrast comes from the density difference of stuff, organic-metal: easy, organic-organic: though) Fact: Breast cancer is the hardest cancer \"to see\", because the fat looks pretty much like cancer tissue with all diagnostics, so sciency texts will benchmark their tools with that type of cancer. My professor once told me a story of how they tried to bring a breast cancer sample from the US to our country and the airline wasnt happy about it all haha",
"For many things that have to be more precise than X-Rays, there's MRI and CT scanners, which deliver precise 3D images of the selected area, and are even used for brain surgery. They are very expensive to use though, so lots of things are still made with X-Rays."
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i5yg7x | How do QR Codes work ? | Technology | explainlikeimfive | {
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"A QR code is like a font that only computers can read. You scan it with a camera (the squares in the corners are used by the computer to read the boundaries), and it translates the QR code into text. If the text is a web address, most QR code readers automatically open that website, but it doesn't need to be. A QR code could just store a couple of sentences, or a phone number, or a string of random characters used as an identifier or code (like the type on a gift card)"
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i5yvu4 | How is it that ads load in 4k immediately but my 720p stream struggles to load? | Technology | explainlikeimfive | {
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"I’m no expert but one theory is that the app (I.e. YouTube for example) stores data on your mobile, like your password, username, your downloaded videos, etc as “Cache”. This cache can also store the ads that would normally be recommended to you by your preferences. Please tell me if I’m wrong I’d like to know the answer to this too. I remember one app that I helped develop did this...? I’m more front end so I don’t really know how this works :("
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i5yxwv | Why do electronic screens look like they're having a seizure whenever you take a video or a picture of them? | Technology | explainlikeimfive | {
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"Because they are being refreshed a certain number of times per second. The device you are using to record shoots a certain number of frames per second as well. The chances of these rates aligning is very small. Therefore, you might capture empty frames sometimes. Also, screens are refreshed from top to bottom, or some other method. You might catch half a frame even.",
"Same reason an airplane propeller seems to be moving forward, then backwards, then forward again as it spins up. Sync rate. You only actually see it part of the time (your eyes are too slow). Same thing with video, but the speed isn't changing. Tl;dr; because the camera is only capturing some of the screen changes. * edited for spelling and punctuation."
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i61ng9 | How are some electronic scales able to measure body fat or bone density? | Technology | explainlikeimfive | {
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"Body fat scales use a technology called bioelectrical impedance analysis to measure body fat. A small, unnoticeable electrical current is sent from one foot, up one leg and down the other leg. Fat is a poor conductor of electricity compared to other components of the body such as muscle. The more resistance the electrical current experiences, the higher the fat. They are not particularly accurate, I believe."
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i61tvd | What is an electrical ground, and why do electronics need them? | I never understood the concept of an electrical ground. And while working on my truck, I notice almost all of the fuses and switches have positive, negative, and ground. But if a tail lamp or bulb wire is touching ground, that can cause it to not work. | Technology | explainlikeimfive | {
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"A ground in electronic devices is essentially a path through which electricity can flow should an accidental connection be made between the intended electric circuit and the case, frame, or other parts of the product that can carry electricity. The idea is that the accidental connection causes electricity to flow into the ground instead of into a person touching the device. In general, modern devices without a ground on the plug are designed with redundant insulation instead, to keep the exterior from becoming live. Cars use DC voltage, with the negative side of the battery connected to the frame of the car as ground. TBH, I don’t recall any switches or fuses on cars that I’ve worked on having separate ground connections, though there are other devices that might. But it’s been a long time since I’ve worked on a car, so perhaps practices have changed.",
"They call it ground, but since your car has rubber tires that obviously isn't connected to the actual ground. The negative (usually) post on your battery is bolted to the frame and they call it 'ground' because it acts like a ground in a building. For example if you have a damaged wire, the grounded metal will allow the electrical current to flow from the damaged wire into the metal frame and back into the battery, completing the circuit (thus allowing the fuse to heat up and blow to protect your wiring from melting).",
"Voltage is relative, you need a reference. Ground in a system is the point that all other voltages are relative to, its defined to be zero volts. Generally you want a big conductor so there are lots of electrons and it won't change voltage significantly no matter what you do or where on it you measure. For your home power grid, the ground wire and the neutral wire are referenced to Earth Ground by a long metal rod next to your house. For your car there's no physical earth connection but there is a big metal chunk that'll do the job just fine, the chassis. In your car one terminal of the battery is tied to the chassis and the other provides power to other systems. This is handy because it means you only need to run 1 wire out to most systems because they can return the current through the metal of the car without needing a separate wire running all the way down the car. In your phone there will still be a ground plane despite definitely not having a connection to earth ground. This is going to be a big layer of copper in the circuit board that is tied back to one terminal of the battery. Again, the big piece of metal keeps there from being much of a voltage difference between any two points on it."
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i65rld | What exactly is the difference between a powerful pc and a Server? | Technology | explainlikeimfive | {
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"Purpose. A powerful pc is used to perform tasks for a single user. A server is meant to facilitate a service for multiple users and stay powered on for a long time. Powerful PC do job for one person real quick. Powerful server do job for many people.",
"Any PC can be a server and it doesn't even have to be powerful. The only hard requirement to be considered a server is to provide some sort of service to the local network, such as DNS, file sharing or a web page.",
"Enterprise grade server hardware is built to much higher standards when compared to the average consumer grade stuff. Often times, specific hardware is built that's exceedingly good at one part of computing: massive storage arrays, large network transfers, rapid calculations of specific algorithms, etc. Servers also usually have a back up/redundant items of almost everything: network interfaces, storage arrays, power supplies Probably the biggest difference: volume. Servers are made to be stuck in cabinets with potentially dozens of other servers so they're a very specific size/form factor. Server rooms are usually designed with a hot side and a cool side where rows of like sides point at one another. Cool air gets drawn in the front of the case and blasted it the back. Because of their shape and the way they're intended to be installed they usually have as least twice as many fans as a household computer to pull large amounts of air through their chassis. Since they're not in a living room, they usually pack a bunch of smaller fans in (redundancy) which are significantly louder than larger fans.",
"A server is a computer that provides a service to other devices connecting to it. A powerful computer is just that - a powerful computer. A powerful computer can be a server too, but a server does not have to be powerful.",
"Fundamentally, not much. A home computer can be a server, and a server doesn't even have to be powerful (I have a 15 dollar raspberry pi 1 as a dns server with \"pi-hole\" installed). All a computer needs to do to be classified as a server is to offer services to other computers. You could use any sort of network-capable computer for this task, but if the computer is hosting any sort of important service, it is a good idea to get a purpose-built server. Such a computer will for example have two power supplies, so that if one stops working, the server will still be 100% operational and there will be no loss of service. Other common features of a \"proper\" server is to have a completely separate mini-computer built into the server that can reboot the main server if needed (for example if it locks up completely), and perform a lot of low-level administrative tasks or diagnostics that you'd normally need physical access for. Redundant storage is also common, allowing the administrators to replace entire hard disks while the system is running, without it having any noticeable negative effects on the users that utilize the server. A very typical difference is that servers will often have many weaker cores instead of a few very fast cores. One of the reasons for this is that if you have for example two users that each want to view a web page, it'll take a lot less energy to do this if you have two cores at 2 GHz that each send one user a web page, than one core at 4 GHz serving both users, even if the task takes roughly the same time with both setups. For this reason, servers very often have 20 or more cores each if they serve a lot of people. These 20-core CPUs would however not be very good at some of the tasks that are common for home users, such as web browsing or playing games, because it's a lot harder for a game to make use of all 20 cores for a single game, than it is to have 20 almost entirely independent tasks evenly spread across 20 cores. When you're running dozens of servers that serve up pages 24/7, the lower power use both leads to lower electricity bills, and less heat output, which allows them to again spend less money on cooling down the server rooms. Another thing to consider is that because these servers are built to both be extremely compact (because it costs money to rent the physical location you put them in, and you might need many of them) and to be installed in rooms where humans typically don't spend a lot of time, very little effort (probably none at all) is put into making them quiet. Purpose-built servers can be extremely loud because they have a lot of very small fans that spin extremely fast to push air through the very dense internals of the server. You would not want to have one in your living room."
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i6ahdp | How do movies shot on film have sound? | Technology | explainlikeimfive | {
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"For a long time the film had a visual audio track on one side, it's a wavy sine wave looking thing that essentally works the same way as a record groove does, only using light. URL_0",
"the audio was recorded using a phonograph and was played simultaneously with the film. the movies on film have now been put together in one thing using computers/technology to combine them together. Fun fact... back in the days of silent films when they showed them in theaters they would have a musician playing the soundtrack live along with the showing."
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i6ahx9 | Why do networks share cell towers | I seen ads for cheap cell service like ting or mint using T-Mobile cell towers. How is it financially viable for networks to share the same service but one is selling for significantly cheaper, especially since these cheap services often say that their service is just as good? | Technology | explainlikeimfive | {
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"For one, wireless carriers oversubscribe the shit out of their network. If they can build a network that can support 500 concurrent calls, they’ll sell 5000 user accounts knowing that not everyone is going to be using the system all the time. Selling off capacity to an MVNO (mobile network virtual operator) is a no-brainer. The mvno basically pre-buys bulk minutes or bytes (or is contractually obligated to buy) and they have to handle all of the support and customer service. So T-Mobile gets paid for use of their network, but the other company has to handle all the end user support."
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i6cqll | How and why is the volume so much louder in video commercials? | Technology | explainlikeimfive | {
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"All sound is a wave. There are peaks and lows to the wave. The difference between the highest and lowest point in the wave is called dynamic range. Using something called compression you can reduce the range of the sound. This can bring the lows up higher making the lows sound louder while keeping the peaks where they are. For advertising, the compression is used very aggressively so it gets your attention more and drives home the message of the ad. Compression technology has evolved over the years to allow more of it without distortion of the sound, and advertisers have taken advantage of this in a bad way."
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i6e2is | How are password storing systems so secure? I’m hesitant to put all of my passwords to everything in a single place, but they are widely regarded as safe. How come they are supposedly harder to hack than a password on an individual website? | I’m really hesitant to use one because I feel like if someone gets access to it then my entire life would be exposed, but I’ve been told that’s essentially “impossible” and I’ve often seen them endorsed by computer security experts and people who know what they’re talking about. | Technology | explainlikeimfive | {
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"> I’m really hesitant to use one because I feel like if someone gets access to it then my entire life would be exposed This is true. As with most things in life, you have to make compromises, and in this case, you're trading strong passwords everywhere else against a single point of failure protecting everything else. Something like Lastpass, for example, helps you by operating on a zero-knowledge model: they do not and cannot know your master password. They don't store it anywhere on their servers; all they store is the encrypted data. Sure, an attacker could breach Lastpass and get that data, but it wouldn't do them any good without a way to decrypt it, and since Lastpass doesn't store your master password and encrypts its data with industry-leading technology, it could take, and I swear to you this is a real result: 27 trillion trillion trillion trillion trillion years for a single computer to break a single piece of Lastpass' encrypted data. Adding a thousand computers of similar spec....wouldn't help much. Divide that number by a thousand, you still have trillions on trillions of years. Use a strong master password, and you'll be fine. Just make sure you don't forget it, because a consequence of zero-knowledge is that Lastpass *cannot* help you if you forget it.",
"Great answers by others. Summarized: - **Separate passwords for each and every account.** So when one gets compromised, that's the only one. (Lots of people reuse passwords, and don't notice when an account they last used 6 years ago gets compromised, so they don't know that all their other current accounts are compromised too.) - **Long, complex passwords** - extraordinarily hard to brute force and not likely to be in a rainbow table. You don't ever have to remember them or type them in, and you don't have to make them up, because the password manager handles all that for you. - **Pure secret passwords.** Because you didn't make the passwords, you didn't memorize them, and you don't type them, they couldn't even be tortured out of you. Which means you also can't reveal them while drunk, or sleeptalking, or whatever. - **Securely encrypted** using the latest state-of-the-art encryption so even if someone gets a copy of your password vault, they can't get in without your key. - **The key is key.** Of course, you need a good lengthy memorable key phrase, many words, ideally not a common phrase, and with a personal twist or additions. But it's relatively easy to make one of those that's 12+ words plus numbers or whatever, and which you will always remember. The key is also useless without the vault - someone needs access to both to use it. Drawbacks: - **Single store.** If *you* lose access to the vault, you lose access to all your accounts. Therefore, you must keep backups, preferably in multiple locations. - **Key required.** If you forget the key, you lose access to all your accounts. Therefore, you need to make it memorable. Maybe write it and put it in a secure physical location just in case, but don't label it, so that anyone who finds it won't know to look for the vault.",
"TLDR: Using password managers promotes best practices that increase your password security by allowing you to choose impossible to crack passwords and secure them by only one password. Good analogy is having all your eggs in one basket and putting that basket in a secured locker in a Bank. This is a bit divergent but necessary to understand the argument. You need to understand how passwords are stored by the website. In modern applications no one stores the passwords in plain-text (which means storing the password as-is). The websites will store a hash (hash is a value derived from your password). Hashing a password is one-way-street. You can not find out the password from the hash. Now you may ask how the passwords get leaked? Now there are some fellows out there who have precomputed hashes of all the common passwords. Such a dictionary of passwords and their hashes is called rainbow table. Now if you have access to this list then you can lookup the hash in the list to get the password. Now there are ways to delay this but someone adamant can still find your password. Now the passwords which are easy to remember like cool-hack-123 are easy to remember but are also easy to crack. And the passwords which are difficult to hack are impossible to remember on scale (by scale I mean there are hundreds of passwords that need to be remembered). So people resort to using the same difficult password everywhere and trust the websites to keep their servers safe. Now doing this means that if one of the websites leaks the data and someone finds your password then your accounts where you used same password are at risk. The only way to mitigate this is to use different difficult passwords. Which is possible but impractical because the day you forget one password you will set it to something you can remember. This is where the password managers come in. These applications use state of the art security algorithms and processes to store your password information. They take over the job of remembering passwords. Once you start using them you are not bound by any limitations on password selection. You can select an Uber random 24 character password and rest assured that it will be there when you need it. There are algorithms like AES which when used with 256 bit keys are proven to get eons to crack. There is a public key infrastructure which can be employed to verify authenticity of the data and securely communicate it without sharing the passwords used for encryption. Now these services have best cryptographic minds working for them who have carefully selected the tools (from an arsenal of time tested algorithms) to secure customer information."
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i6hl12 | Why do older people find it so much more harder to understand tech? | Technology | explainlikeimfive | {
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"Well for one thing, like most things, there are exceptions to every rule. I'm 60 years old but I'm the one who EVERYONE I know comes to to fix their computers. This includes my two children who grew up with computers. I think it comes down to anyone can learn and understand what they are interested in. If you aren't interested you don't pay attention to things that are shown to you. Older people know how to be \"in the moment and not always staring at a screen\" and don't appreciate tech as much as most younger people.",
"As an adult in their 40s that teaches 100 teenagers every year, I can confidently say that young people don't really tend to understand how to use technology any better than older people. I have to teach my students how to do very basic computer tasks, like how to rename files, and how to attach them. And a good 25-50% of them are very quick to let me know that they \"don't do tech.\" I think most people just can't be bothered to tap the buttons and find out what happens, or to look their question up. My parents taught me how to use computers, and my mom in her 60s is better with her phone than most of my teenage students, who can't even figure out how to forget a WiFi connection. People who grow up using tablets and smart phones are going to tend to be better with them than people who didn't, but it's about being used to that particular format, it's not because they're \"better with technology.\"",
"Ever tried getting into a completely unfamiliar field? Like say you're trying to build something from wood. How hard can that be? You go to the store and suddenly realize you have no idea about anything. What kind of wood do you need? How thick? How do you cut something in a straight line? How do you make a hole in the right place? Do you need a belt sander? Do you need to spend $20 or $200 on this thing? What is that weird thingy you saw on youtube that looked really useful called, and how do you explain what you need without looking a complete moron? Every field has a myriad tiny things that you need to understand to even be able to make coherent questions at all. If you don't know them, there's a lot you must learn before reaching even basic understanding. Then there's that a lot of people want just to get stuff done, and don't want to spend 5 hours first on getting the basics of computer technology. Children on the other hand mostly get started by playing around with stuff, without having a pressing goal like \"I must send an email to my boss within the hour\", so those skills are much easier and less frustrating to pick up when messing around with stuff is the only point.",
"Your younger cousins grew up using technology and it is „natural“ to them, your parents on the other hand didnt grow up with it and dont have much experience with it.",
"It’s all about exposure. Kids these days play with tablets before they can even talk. Try explaining agriculture (or something that was part of your parents generation) to your cousins and you will have the same problem."
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i6ib9g | how do breathalysers work to detect alcohol in breath and how accurate are they? | Technology | explainlikeimfive | {
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"Alcohol is not digested by your body and directly enters your blood stream. Our blood also passes through our lungs where some of the alcohol passes through membranes and evaporates in the lungs because of its volatile nature. Now when you blow into a breathalyzer, if there is alcohol in your blood a chemical reaction occurs in the machine which causes a colour change. This shows the amount of alcohol in your bloodstream.",
"Alchohol circulates in your blood, and your blood reaches your lungs. Alcohol also diffuses out of your blood, so it mixes with the vapors in your lungs. This means it really is \"on your breath\". Breathalyzers are fairly accurate. They measure the amount of alcohol in your breath and multiply it by 2100 (breath-to-blood alcohol ratio is 2100:1) to get a decent estimate of your BAC. This is still just an estimate, though. There are a few things that can affect your readout, though, including; higher body temperature, differences in blood composition, how recently you drank, electrical interference, presence of methyl compounds (from things like paint remover, vinegar, cleaning fluids, diabetes compounds, etc), acid reflux, blood or vomit in the mouth, etc, etc. Heck, even having recently smoked a cigarette can affect your readout. All of these things can add up to about a 15% difference between your breathalyzer readout and your actual BAC. If you're ever arrested for a DUI, police will probably run a blood test when they get you back to the station. There are even lawyers who make their living challenging the accuracy/reliability of breathalyzer tests."
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i6ieqv | why can music CDs only hold 80 minutes of content while gaming CDs can hold many hours? | Technology | explainlikeimfive | {
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"Audio CDs are uncompressed and typically require about 10MB/min. The quality of the audio is fixed, so spoken words and even perfect silence take up just as much space on an audio CD as dynamic music or random noise. Games, on the other hand, can store their audio in a compressed format and then decompress it while the game is running. This allows them to 1) store the same audio with the same quality in less space, and 2) use a lower quality for sounds that don't require a lot of resolution (like sound effects or spoken words), saving even more space.",
"An audio CD is in a raw format with no compression. It is in a medium that is ready to be consumed by a CD player that has no major \"brain\", just the ability to read the CD and play exactly what it says. You can store compressed audio files on a CD in a data format much more efficiently, but then your CD player must be capable of understanding that format. While iPods were starting to become commonplace, a lot of companies that made CD players were making MP3-CD players. These were portable CD players that could understand the MP3 data format and play the music off of it. However, these were pretty short lived. MP3 players became much cheaper much faster and the storage of a CD was actually pretty low compared to memory cards."
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i6m3mi | How do video games keep a constant frame rate? | As I understand video game code, it's based on a central loop (one repetition of which is a frame) that takes input, updates the gamestate, and renders the changes. Based on this understanding, a faster computer would run the loop faster, and the game would simply run at a faster speed. Obviously, this doesn't happen, so what am I missing? | Technology | explainlikeimfive | {
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"> a faster computer would run the loop faster Exactly! That's why people buy better hardware to get better framerates. The game does have access to the system clock so it's not like in the 80s where games had no idea how long it took to make one loop and you had to lower the clock speed if you had a too good CPU. Any decent game can adjust to having variable frame rates (though in some cases 100+ FPS can slightly freak out the physics engine in games like Skyrim that were originally intended to run locked to 60FPS).",
"If a game allows it you can have the max fps possible with your machine. To limit the frames the time to calculate a frame is measured and if the frame is calculated too fast your computer idles until expected time is reached.e.g. 60FPS = 1 frame each 0.016s. If your pc only needs 0.001s it waits for 0.015s until it shows the next frame.There are frame dependent games so upping the frames per second would lead to a faster game, but normally the game loop or physics uses the real time that is passed between calculation. So it is possible to have 1000 frames per second but all calculation are based on the time thats passed. e.g. 1 meter per second fast object 1000 FPS = 1 frame each 0.001s = > 1 meter times 0.001s = 0.001 meter 60 FPS = 1 frame each 0.016s = > 1 meter times 0.016s = 0.016 meter 30 FPS = 1 frame each 0.033s = > 1 meter times 0.033s = 0.033 meter & #x200B; So all reach 1 meter in 1 second, but they will show it more or less accurate. \\[Edit: forgot a s for seconds and a space+a dot new lines got lost after edit, added the example of a too slow pc\\]",
"Computers have timers built in. If the game is supposed to run at 60fps, but the code only takes 1/80th of a second to run, it will do all the work it needs to do, then it will pause and tell the operating system to wake it up after the remaining 1/240th of a second. The operating system may be able to use that time to run some other processes on the same CPU core if necessary. The lower the frame rate you set the more time the computer will have to do other things.",
"The program is able to keep time. Having a higher framerate may allow you to sneak in input a bit more often, but the game knows your framerate and can measure time to keep everything running at the right pace no matter how often the updates happen. Side note, if you're interested in learning a bit more about this kind of thing... In unity there is an \"Update\" function which runs once per frame, and there is a \"fixedupdate\" function which runs on a set interval. Using fixedupdate allows physics to happen properly outside the confides of framerate. check it out if you'd like"
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i6njt6 | Why does it take a while to charge things like phones or controllers and isn't instant? | Technology | explainlikeimfive | {
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"It's like filling a car tank with fuel. Imagine if you pumped the fuel fast enough that it was instant! Super convenient and fast, except the part where the fuel pump explodes, the pipe bursts in your hand from the pressure (taking your limbs off in a shower of gore) and the jet of hypersonic fuel literally cuts a hole straight through your car like a waterjet cutter. It's kinda like that with batteries, but they just melt and explode due to not being able to shed the heat they would be able to get rid of if it was generated over a long period of time.",
"Batteries store energy in chemicals. When you try to run those reactions faster you can get heat and/or sparks. Either can damage the device, so that's a bad idea. Chargers are carefully engineered to prevent charging too fast."
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i6q6oo | How did Duck Hunt work back in the day, with a Gun pointing to the screen? | Technology | explainlikeimfive | {
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"The Zapper is basically a simple light detector with a lens at the end of the barrel. Basically, think of it like a really really low megapixel camera. When you press the trigger on the Zapper, the whole screen except for the position of the ducks is drawn as black for a frame or two. The ducks show as white squares against a black background. Since old CRT Televisions did not give off any real light in black zones, the Zapper only had to \"look\" to see if it was aiming right at a bright light or not. If it was dark or black, no duck. If it was bright white, duck. The flash would then revert to normal graphics and continue on. If you slow it waaaaay down, you can actually watch it happen. It's pretty neat. This is also why you could aim the Zapper at a light bulb and pretty much never miss. It would always detect bright light and thus register a hit.",
"When you shoot the zapper, the tv screen goes black for a split second and the duck on the screen turns into a white square. The gun registers a hit if you’re aiming at the white square. It’s looking for light on the dark screen hence the term “Light Gun.”",
"How did it know which duck you shot if there was more than one on the screen?",
"8-Bit guy made a video explaining how it works. (Starts at 8:40 though the light pen is also interesting) URL_0"
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i6u97h | So can someone explain what is viewing angle?How come an oled panel has such a wide viewing angle compared to it's lcd counterpart? Why does pixel lose color at a certain angle? | Technology | explainlikeimfive | {
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"It happens because of how the technology works. In an LCD the lights are always on and there’s an electrically controlled filter in front (the liquid crystal) that blocks or let’s the light through. The filter transmits the most light straight ahead and the light drops off as you get off center, like looking at a lightbulb through a pipe. On an OLED there’s no filter, you just turn the light on and off very quickly. It’s like a lightbulb without the pipe."
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i6wioj | - How am I able to talk to someone across the world with minimal lag | Technology | explainlikeimfive | {
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"The circumference of the earth is about 40 000 kilometers. Light travels at just under 300 000 kilometers per second, meaning light can circle the earth in less than 140 milliseconds. Modern voice communication is converted to light pulses and sent along fibre optic cables, so it travels at close to the speed of light. 140 milliseconds is too short a delay for humans to notice, so the communications feels instant and without lag.",
"Speech (sound generally) for humans can be quite efficiently converted to digital data - this means it doesn't need a lot of data per second to convey sound quite effectively. Not more than a few thousand bytes per second, say at most 10-20 thousand bits/second, for normal speech. Humans are also fairly tolerant of a bit of delay. (ie you probably don't notice lags of < 0.25 seconds) For modern network equipment and computers 0.25 seconds is a lot of time for processing the data from sound to data and data to sound. Data signals travel at the speed of light and modern equipment passes data through at rates easily greater than 1 billion bits per second in a single channel through the major network paths. Any reasonable modern ISP can send data at many million bits per second to your home. This is easily enough data and short enough transmission lag for conversations - most home connections today can even support video communication (which requires a lot more data)"
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i6wj4i | How does the ZFS raid allow for just a small number of drives to be used for copies of data and guarantee that data won't be lost in case of failure? | What I mean is that according to linus tech tips, if you have five hard drives, you can dedicate one of them and it can guarantee that if any one drive fails, no data is lost. I just don't understand how that works. How come you don't need the same amount of backup storage as normal storage to guarantee that? How can it store a backup copy in a fraction of the space? | Technology | explainlikeimfive | {
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"For a RAID setup with 5 hard drives and single parity, each block of data you store in the RAID array is divided into 4 parts. From these 4 parts, a 5th part called the parity information is calculated (see URL_0 for a non-ELI5 explanation of this step). If you lose any 1 of the 4 parts of your data, the remaining 4 parts (3 original + 1 parity) can be used to determine what the missing part is. This gives you limited protection against data loss in the event of a hard drive failure. If you can replace that hard drive and let the RAID array rebuild the missing data before any more hard drive failures occur, you can avoid data loss. But if another hard drive fails before the rebuild can be completed, you would not be able to recover the unrebuilt data since you would not have enough parts to do so."
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i6xr1u | How do lights that turn on and off when you clap work? | Technology | explainlikeimfive | {
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"Typically these devices have a microphone, a filter circuit and a switch. The microphone takes in any and all noises from the surrounding environment and converts it to an electrical signal. It does not discriminate. The filter circuit is where the magic happens. It takes in the electrical signal from the microphone and cleans it up. It will typically do this in two parts. First by removing anything outside the frequency of a clap. Second by focusing on short but strong bursts of signal. When it detects a clap in the signal from the microphone it sends a much cleaner and more simple signal to the switch. The switch listens to the signal and decides to open or close."
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i7052f | What kind of tasks are humans going to be still doing manually and cannot depend on automation or technology to do them? And why? | Technology | explainlikeimfive | {
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"From a robot technician: Current robotics are just starting to merge the fields of AI with real-world applications. See \"Spot\" for an example of this. However, the vast majority of robotics nowadays are in factories, and these robots are able to react to limited input, as long as its pre-programmed. For instance, if the part Is red, use bolt 1, otherwise, use bolt 2. Generally speaking the more repetitive some task is, the easier it is to automate. For instance, screwing toothpaste lids on in an assembly line. It's nothing but a repetitive motion, and a robot could be set up to do this task in probably less than 10 minutes. Whereas say a travel agent takes a starting location and a destination location and looks for the cheapest price. This is more complex, but can be broken down into many simpler processes. (Find itineraries, find cheapest itinerary, book itinerary), and is why online travel agencies have be one commonplace over the last 10 or so years. A task such as designing a vehicle for instance, does not have one correct answer, and there are many many factors and processes tdd o consider, as such this is a very difficult process to automate, potentially even impossible. So the safest jobs are those that are complex, but cannot be broken down to several simpler tasks, or those professions that require creativity.",
"Teaching. People talk about having remote/simulated/robot teachers. I’m a secondary school teacher and it would just never work. The relationships at school only work when there’s respect both ways which a computer will never be able to emulate.",
"Social workers, psychiatrists. These jobs need human contact. During corona they had to work online a lot, via video call and it just didn't work. Human contact is needed.",
"I'll just mention translation because it is in a very peculiar place right now. Machine translation is used and is now expected to be used by younger translators but it's still not good enough to be used professionally on complex texts. It's supposed to be a pretty creative job because a word in English is not equal to another in a given language, yet machines got good enough to become part of the market, while not being self sufficient at all. I'd be curious to read what people from other fields of expertise think about that."
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i74lbg | Why are backup cameras so common on most cars, but you never see them on the 50foot semis | Technology | explainlikeimfive | {
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"Trucking companies are insanely cheap and never do anything to make driving easier or safer until it's mandated by law. Even then, they try to find loopholes or just ignore the law until they're repeatedly punished.",
"It's honestly not needed. Most drivers are only backing up in a lot full of other trucks or at a warehouse dock that has other drivers who know not to walk behind, kids are absent from the are. Also note that they would need the cameras on the back of all the trailers. Conservativly guessing there are at least 1 million trailers in the US alone. 95% of drivers won't keep the same trailer longer than 2-3 days. They drop a trailer off and pick up a new one very frequently. It's just not practical."
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i74lzn | How does the steering wheel of a car automatically return to it's original position when accelerating after a turn? | Technology | explainlikeimfive | {
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"Both front wheels are angled inward or they have slight \"toe in\" which makes them want to go straight.",
"The short answer is that steering engineers have engineered the steering and suspension system so that the wheels and tires point straight. The simplest explanation can be seen on shopping carts: the wheels \"follow\" the direction of the shopping cart. By placing the center of the shopping cart wheel behind the pivot point of the wheel, the wheel always gets \"dragged\" behind cart, so it always tracks straight. In reality, there are many other design parameters that affect steering e.g. camber, caster, toe, king pin inclination angle, control arm geometry, etc, that engineers must optimize so you get a proper steering system. One wrong design choice and you can have a car that is dynamically unstable and virtually impossible to drive.",
"Mechanic here i can answer this one ... so the suspension is set with a small castor angle (basically the same principle of shopping trolleys wheels when they’re on the ground they go straight because they are always trailing) likewise in a car that kind of angle is built into the design to allow the car to correct the wheels to the centre just like a shopping cart ... the wheels in turn turn the steering wheel back to straight... this principle i use a lot when doing tracking to ensure the stearing wheel is straight for the customer... if it was not built with a castor angle (think shopping trolly wheel) it will be going down the motorway and just decide i want to go left ... there’s nothing to correct it"
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i762r6 | How can information be transmitted so accurately with little to no errors even at several MB/s? | If I'm not wrong, information is transmitted in 0s and 1s which is binary. 0s replaced by 1s or vice versa is all it takes to corrupt a file. How is this not prevalent even at high speeds? Even slight disturbance or delay could destroy such fragile signals. | Technology | explainlikeimfive | {
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"The most common protocol used for communication is TCP/IP which includes mechanisms to confirm all the data is received accurately. Data transferred over the internet is broken into smaller chunks called packets. That way if a file gets damaged during transport only a small part of it (a single packet) will be affected. Packets are typically 1500 bytes, or 1.5kb in size In addition to source + destination, filename, etc Each packet includes a verification called a checksum. Think of the checksum like a skill testing question 4 x 7 = 28 When the packet is received the checksum is verified. If it has become damaged then the checksum will no longer be valid and the receiver sends a message to re-transmit that packet. 3 x 7 = 28 ERROR Once all the packets for a file have been received and verified, the file is re-assembled. Not all traffic is verified in this way though. Instead of TCP some types of traffic use UDP which is 'best effort' protocol. This is used for things like voice chat and video that operate in real time and can afford to have a couple of errors during the transfer process.",
"Error correction is vital, yes. But 1s and 0s are uniquely easy to transmit compared to other data formats. Say your circuit operates with a voltage from 0v up to 5v. A 0 should be near 0v and a 1 should be near 5v. The difference between them is *as big of a difference as the circuit can produce*, because they are complete opposites. If you get something in the middle, say between 1v-4v, you could discard it and ask for it to be sent again. You don’t need any nuance or ability to recognize in-between signals because all you’re interested in is an on/off, or yes/no, or 1/0 status. Yes, delays can be an issue. This is a lot of the reason for Cat 5e and Cat 6 (or even higher) Ethernet cables. Ethernet can be very long and though they have the same amount of wires inside, higher speeds need less interference between the wires and for each wire to be kept at the same length as the others. USB also requires quality cables to achieve its best speeds. So do DisplayPort and HDMI. In fact, all of the new high-speed communication methods that I know of need a cable built to a higher standard, even though older cables may have been similar with the same number of wires and contacts in them. It seems easy to solve these problems because you can just walk into a store and buy a cable certified for USB 3.2 speeds, or Gigabit Ethernet speeds (or 10 Gigabit!), but a lot of work went into developing, testing, and producing those cables accurately enough to avoid problems.",
"It's called error correction. On the low level (0s and 1s) the information is not transmitted \"as is\", it uses specific codes where we add a few extra bits (there 0/1s) per this low-level message and encode it in a specific way where, if any bit (or several) gets an error, the receiver will be able to restore the original content. On the higher level, the information is usually grouped into packets (tens of kBs in length each) and each packet has a thing called the checksum which is, to put it simply, a fast way to check if the packet is broken or not. So even if the packet is wrong after that low-level correction, the receiver has a way to identify it reliably and ask the sender to resend that packet.",
"There are two ways: error detection and error correction. Error detection involves adding a checksum (e.g. TCP) or CRC code (more advanced protocols). If there's a problem in the data you received, the receiver can tell, and ask the sender to re-send that chunk of data that was bad. Sometimes it's not feasible to ask the sender to re-send the data, typically because the data has been stored and you're looking at it later on. Error correction involves storing not just simple checksums, but enough extra data that corrupt data can be reconstructed. This is a rather advanced topic, but google «hamming codes» for more information.",
"We use error correction codes to deal with them. The simplest is to make your message, then count the number of 1s in the message and attach it to the message. The receiver can then count the number of 1s and see if they match what the sender counted. If they don't match, the receiver asks the sender to retransmit the message. It's unlikely (but not impossible) for random bit flips to garble the message and also produce the correct *checksum* for the new garbled message. More advanced error correction codes also exist, that [add redundancy to the message so that if a small portion is lost it can be reconstructed by the receiver without retransmission]( URL_0 )."
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i7dg4q | I keep reading the word "Discord" and "Discord Servers". Am I missing out on something? | Technology | explainlikeimfive | {
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"Discord is a (primarily) relatively new service aimed at gamers to help them coordinate and communicate while gaming. It was made a replacement for Skype and other voice call services. It combines a forum style text system with easy to use voice channels. Each community gets their own server, which can have a permanent or semi permanent invite link. You only really need it if you plan on using it as part of a community.",
"Discord is an app used for communication, much like Skype and Whatsapp, but it has some extra features that are pretty neat, which caused its popularity, such as servers and bots, among other features. Discord servers are like groupchats, but more organized. A server has channels. Think of it this way: A server is a house, and the house has rooms in it. You can visit one room at a time, and each room has a different sort of thing expected from it (a kitchen is for cooking, a living room is for just hanging out, etc) Discord also has traditional groupchats.",
"It's a chat program, voice and/or text. A lot of people use it to talk with friends while playing a video game, and more and more internet... content creators(?) have a Discord server for Patreon patrons and such to have a private place to talk.",
"Discord is an application for chat and voice communication. Any community can create their own Discord group, which is known as a Server. This is despite the fact that Discord actually hosts everything in their own infrastructure. It's kind of a fallback to the days of IRC and Ventrilo/Teamspeak servers that gaming groups would have. While it does do direct messaging between friends, it's feature set is more made for group discussions or voice calls."
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i7e8eg | how an EMP doesn't harm humans, considering the brain is constantly using electricity? | I ain't no rocket surgeon, but I know that brain cells use electricity to communicate. What separates the affect of an EMP on an electronic device from the human brain? Can it affect humans, but in a less noticable way? | Technology | explainlikeimfive | {
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"EMPs are just really (really really really) powerful electromagnetic waves. Anything conductive will pick up those waves, similar to how a radio antenna picks up radio waves. The amount of power you pick up from the EMP depends on the size, shape, and material. Small electronics are really good at being EMP antennas; they pick up a lot of power and fry themselves. Your brain is not nearly as good...it's not nearly as conductive and it's not a great shape or size. It's roughly similar to why a metal fork in the microwave will generate great big sparks in a few seconds but nothing bad happens to your hotdog until you leave it in there for 30+ seconds. Your brain is much closer to a hot dog than a fork. The EMP still has an effect on you but it's not nearly as bad.",
"You can get shocked by grabbing the bare wire from an outlet and that doesn't fry your brain. The human body is a very poor conductor of electricity, and an emp is basically like a huge static electricity charge. So it's going to be picked up by things that are better conductors, like all the metal in electronics.",
"What makes metals conductive is that the electrons in them are sort of floating around freely. They're bound to the overall material, but are constantly shifting between individual atoms. This means that even tiny amounts of electromagnetic force will cause the electrons to shift to match the electromagnetic field that they're being exposed to. Radio waves are really just a projection of electromagnetic force. Exposing a piece of metal to radio waves causes the the electrons in the metal to re-orient, generating a small charge. This is why wires and electronics have to be shielded. If they aren't shielded then they generate a small amount of electric noise from the radio waves that they're passively exposed to. An EMP is just a fancy name for a burst of high energy radio waves. Electronics are shielded to protect them from the amount of radio waves that they are likely to experience in normal operation. But an EMP is a radio wave that is millions of times stronger than that - so much so that minimally shielded electronics will generate a large amount of current. That current causes them to generate a lot of heat, which will melt wires or pop transistors. The human nervous system uses a completely different type of electrical system than electronics. Whereas electronics work by moving electrons, the human nervous system works by moving charged atoms. Part of the appeal of moving electrons is that electrons weigh very, very little. It doesn't take much force to cause them to move around a lot. The charged atoms in the human nervous system weigh tens of thousands of times as much as an electron. That makes them much more difficult to move around. Whereas a small amount of radio waves can generate a large amount of current in a single electron, it takes a huge amount of radio waves to generate that same current in a charged atom. The human nervous system is also really well shielded against outside interference. Think about how much material a wire is wrapped in - maybe a fraction of a millimetre of light rubber. Now think about how much material your brain is wrapped in - its a cm or two of dense flesh and bone. That means that even if your body is exposed to enough radio waves to affect your nervous system, most of those radio waves will be absorbed by your flesh and dissipated as heat. That could be a problem in and of itself - if you're exposed to enough radio waves you'll get burned, but if you're close enough to the source of an EMP that the radio waves will burn you then you probably have bigger problems to worry about."
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i7fofu | What's the difference between Emulator and Simulator? | I've read many blogs, but couldn't understand the striking difference between these two. From the perspective of Android or iOS. If a software claims to be an iOS emulator, how is it different from an iOS simulator? ***Edit:*** *Added more details. :)* | Technology | explainlikeimfive | {
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"An emulator is capable of running content designed for the platform. An android emulator like bluestacks can run android apps, connect to the app store, etc. It is essentially an android operating system running on your pc hardware. A simulator is a mock immitation of something else. If you made a game in unity that had a graphical interface that looked and operated like an android phone, you could call that an android SIMULATOR not an emulator.",
"My basic understanding is that Emulators mimic something logical or virtual and simulators mimic something physical. Farm simulator is mimicking a farm while an emulator is mimicking the operating system you play farm simulator on.",
"It's easier than you're making it out to be. A simulator is some software that creates a virtual environment of a real world situation. Think flight simulator, driving simulator, etc. An emulator tries to mimic software or hardware of something else. Think playing old Nintendo games on your PC. Your PC hardware is emulating the hardware of a Nintendo in order to play the game."
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i7gz58 | Why are "bot verify checks" becoming so hard? If bots became too smart would somrthing else be implemented? | Technology | explainlikeimfive | {
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"If captcha programs have not been upgraded, it's basically just a matter of time. A computer would likely recognize and select which image has the designated object much quicker than a human. Just give a few seconds and make your best guesses. Although I have to say, I have never come across a captcha with anything more than mild difficulty. Even then, it was really just me not being sure if an object qualifies. Like if a van or truck counts as a car.",
"A bot can solve those pretty quickly. It's there to stop a bot from making thousands of things per second. With the check, it might drop it down to single digits per second. And that would take some decent hardware. The latest generation of \"Click the bicycle/traffic lights\" type checks are ironically enough, designed to teach bots how to solve them faster, with the slowing down internet bots being a secondary effect. If they can figure it fast enough, you can put the bot in a car and have the bot drive. By having a human click, it tells the bot \"this is a bicycle, remember that!\" and \"this isn't a bicycle, remember that!\" Earlier in the internet, they often put hard to read printed words, to teach bots how to read printed text, so we could save books on hard drives instead of on paper."
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i7iswp | what process goes into capturing photos of stars, planets, galaxies etc.? | Technology | explainlikeimfive | {
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"Step one: build telescope Step two: teach telescope to find and follow objects (sort of a pain) Step three: take some calibration images—I usually do this once a night, one all white one, one all black one, and one just of the electronic noise Step four: take all images at one wavelength—you can do as little as 1 for a demo or as many as 50 for an art quality piece. Some NASA images have thousands. Step five: repeat step four for all wavelengths. With visual telescopes, we usually just go a red green and blue image or a white, red, green and blue image, but radio, gamma ray, and other telescopes can be mapped to color in other ways. Step six: import images to Astro photo manipulation program, and calibrate them with the light, dark, and “bias” frames I mentioned earlier Step seven: remove any images that have weird artifacts, like airplanes or freshmen pointing lasers in the telescope Step eight: add the images together Optional step 9: screw around in photoshop to make it look better And that’s how most nebula, galaxy, and cluster images are made"
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i7krkf | How do deep space telescopes work? | Technology | explainlikeimfive | {
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"I assume by \"deep space telescope\" you mean a wide and stout telescope like [this]( URL_2 ) or even the Hubble telescope. These telescopes are called reflecting telescopes, and they work differently than the long, thin refracting telescopes (which look like [this]( URL_0 )). A *refracting* telescope works like a looking glass or binoculars; it is a long tube with lenses that focus light to create an image. The problem is that these telescopes have very small \"objectives\" (the piece that receives light) compared to *reflecting* telescopes. These are used for deeper space observation because (among other reasons) they collect more light. They are wider, so they collect more light, so they can see dimmer and farther things. So how does a reflecting telescope work? It's actually very simple. Curved mirrors focus the light into a small area. That's it, really. There are various designs, and the [Wikipedia article]( URL_1 ) has some good diagrams, but the principle is very simple. They work just like a satellite dish, where a large, curved surface focuses radio waves to a receiver. The only difference is that these telescopes use mirrors to reflect the light, and they may reflect it multiple times."
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i7lk6a | Why do photos of the same size have different file sizes? | Technology | explainlikeimfive | {
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"text": [
"The complexity of the photo drives the file size. Take for example, 10 white pixels are next to eachother. Instead of storing \"white\" 10 times, it stores \"white x10\" once, which requires less space to store This is a rudimentary example of how file compression works. JPGs and PNGs compress, but there's are certain \"native\" file formats that don't compress, resulting in filesize largely proportional to pixel count",
"Why do boxes that are the same size weigh different amounts? (Note - I’m not trying to be a smartass, but a couple of people have already given more detailed answers so I thought I’d pose a question that might make it much more intuitive without providing many actual details, kind of like what you may do with an actual 5yo.)"
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i7m9qh | How do aimbots in first person shooter video games work? | Technology | explainlikeimfive | {
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"The most rudimentary bots take a screenshot, process the pixels and look for a cluster which looks very much like what the bot has been told 'an enemy head' should looks like. They aren't accurate, but they are almost impossible to detect by anti-cheat software. The bot works completely outside the confines of the video game boundaries. Then you have aim bots which work based on the aiming system. In a lot of games, you have what's called a \"hit scan\" system. The software knows where the enemy is on your screen. The software knows where your crosshair is pointing. When you press the trigger, the software checks if you are pointing at \"an enemy\". Since the software knows where \"an enemy is\", the aim bot can dig up this information from the computer memory. It can then convert it to X,Y coordinates on your screen and snap your crosshair to it. This is easier to detect by anti-cheat systems because the game's memory will show as being accessed by foreign software."
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i7mo6f | Why is it when you talk about a product, activity, place, action, etc; you get ads about that across social media? | Technology | explainlikeimfive | {
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"There are two possible explanations: 1) When a service is free to use, you're the product - meaning that Google, Facebook, Twitter etc. makes their money primarily by selling data about your plans, habits, interests and needs to ad-companies, or using it to improve their own targeted ads. Then there's the \"conspiracy theory\" that e.g. Facebook and Google actually listens to you in secret, using the microphone on your smartphone, and including things you *talk about* in their profile about you. I use quotation marks because it started out as such, but there is now *some* evidence that this is actually the case. 2) The second explanation is the Baader-Meinhof effect. In short, whenever you learn about something new, your brain puts emphasis on encounters with said thing and remembering them. This makes it feel like you're suddenly encountering said thing everywhere. E.g.: You find out that segways are legal to drive in the streets in your country, and consider buying one, and suddenly your brain pays attention to every ad about segways. The experience you're having could be either of these, or a combination hereof."
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i7nxj9 | How can one tell if an online information source is accurate? | Technology | explainlikeimfive | {
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"text": [
"It depends on the type of information you're looking for. URL_0 offers everything science related. If you're looking for world news your best bet is looking at several news outlets to even out their own bias (and preferably stay away from newsfeeds that will try to give you just what you think anyways)"
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i7wj9c | How does a CPU and Motherboard clock and bus speed work together? | I am getting an A+ cert and my tutorial just mentioned that my CPU speed is 3.9 GHz, but my motherboard is 200MHz. I understand how the motherboard mulitiplies speed. Mine usually does it by 33 times, but still, that isnt even CLOSE to 3.9GHz speed. How does my output on my computer not lag all the time? | Technology | explainlikeimfive | {
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"200MHz is still really really fast so you're not going to see lag just because the motherboard speed is different and slower than your CPU. Think of it like speed limits on the road; the CPU is the interstate and goes very quickly between specific points, the motherboard is the local roads that go everywhere you could possibly go but not as fast. You need both to get to your destination efficiently. Most CPUs need several clock cycles to do anything useful. For the sake of example, let's assume it takes 10 clock cycles for the CPU to complete an average calculation internally. If the motherboard was running at the same speed as the CPU, it would spend 90% of it's time waiting around for the CPU to finish its calculation. There's no value in the motherboard being faster than the CPU can input/output information, which is slower than the CPU can internally compute. There are also physical reasons you can't run the motherboard as fast; higher speeds get harder to maintain as things get larger. The CPU is only tens of millimeters across, it's relatively easy to maintain high clock speed over that distance without synchronization or loss problems. Doing the same across the whole motherboard, which is tens of times larger, is much more difficult. There is a tradeoff between the two speeds. CPUs that execute instructions in less clock cycles can by synchronized more closely to the motherboard speed. This is why reduced instruction set processors (like ARM or old Apple RISC chips) have lower clock speeds but can still maintain roughly equal performance to a higher clock speed but more complex CPU."
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i7y2ju | Why do most countries have a different kind of electrical plug? Does/can a universal plug exist? | Technology | explainlikeimfive | {
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"Electricity propagated before international travel was common for most people and international manufacturing was nascent. Each country developed their own standards because there was no incentive to do otherwise - the US manufactured its own electrical appliances and sold them almost exclusively to US citizens, so all that mattered was that everyone in the US used the same standard. A universal plug can exist, and many people are pushing for USB-C to become the universal standard of electronic devices.",
"Electricity was a thing before international travel was big, and even before international travel while bringing electronics was a thing. Each electrical system has a lot of momentum with their plugs. It also prevents you from plugging something meant for one electrical grid (which are at different voltages/frequencies/etc) into another without the right transformers in place."
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i81v3p | What is that sound or feeling you get before the power goes out during a storm? | There is this Erie feeling and a sound almost high pitched right before the power goes out. What is it or is it all coming from the brain? | Technology | explainlikeimfive | {
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"text": [
"Since you said during a storm, here are the most likely explanations. The high pitch sound, almost like a tearing sound, right before lightning is from the \"failed leader\". This is a streamer of positive charge that goes up from the ground towards the negatively charged cloud. When lightning strikes there are many leaders reaching for the cloud, but only one or two will make contact, complete the circuit, and result in lightning. The rest of these \"attempts\" are called failed leaders and may create noise without ever being visible. Now, during a storm these charges are leaking and balancing in anyway they can. That means into and out of powerlines as well. You will sometimes hear a high pitch coming from powerlines. In a process similar to the failed leaders above the charge is leaking from the lines or into them. The power grid is designed to handle this and it does a pretty good job. You might see the lights dim or brighten as it gets a rush or major draw. However, if a sudden rush comes from a direct strike on the grid this will blow breakers and likely damage the lines/relays/transformers. This will result in a localized blackout to everyone connected to that part of the grid. Edit: The Erie feeling is also you detecting the change in electrical potential in the air around you."
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i86i8a | How does a country just turn off the internet? | In recent events, Belarus was reported to have shut down the country’s Internet. How does that happen? Does the government control all the servers, or so they have a kill switch somewhere for all the service providers? What about mobile internet? Logistically, it doesn’t make sense. | Technology | explainlikeimfive | {
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"> Does the government control all the servers In a sense, yes. They send the police (or military) to the server companies and say shut the servers off or face arrest (or worse). They do the same with mobile providers.",
"The internet is a series of connected computer networks. All you need to do to turn it off is to go the places they connect and pull the plug. So if you are the government you go to the isps that provide service and tell them to turn it off. / disconnect. Threat of arrest / death normally works pretty well here. As for mobile that eventually gets back to a hard line connection and the same thing applies tell the people to turn it off. Near the borders it might be harder to do with mobile but the radio waves only have a limited distance they can travel.",
"Belarus has seen a spike in TOR usage. URL_0 So they have internet fortunately.",
"The government controls all the pipes. They can shut down the backbone connections between the country and its neighbors. Sure, maybe you can catch the neighboring country's mobile signal at the border, and maybe someone has a satellite uplink, but most of the traffic can be shut down. Remember, the Belarussian dictatorship has been in place since 1994 - predating the spread of the Internet in the country. The networks in the country were built under the dictatorship's oversight to begin with."
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i89j4l | Why is 'colour' spelled as "color'' on computers? | Technology | explainlikeimfive | {
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"text": [
"The short answer is because Color is the Americanized spelling of colour, and a lot of computers and computer programs are owned or operated by American companies",
"Because you have your computer using US English. Set it to UK English and it should be fine. Source: working abroad and using multiple language/keyboard language settings"
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i8d0hl | Can anyone tell me what is github and how do people normally use it or understand? | I've recently come across the name 'github' and i know that it is a server in Scandinavia somewhere which people can apparently use it somehow idk. Would help if you someone could lay down everything regarding it... | Technology | explainlikeimfive | {
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"GitHub is a cloud storage site for Git repositories. Git is a version control system for software development, allowing developers to roll back their code to previous versions, branch off and develop new code without affecting the old, and various other useful things.",
"When people write programs, they can use github to version, manage, and store their code. Generally speaking, it’s a version control system that provides developers to save their code code while developing. It also allows teams to work together on projects through a concept called branching. Branching allows two or more people to start from the same code base and work on different aspects of the program, later merging their changes together. At this point, the developers will work through any merge conflicts, and after pulling their hair out and pleading with gods borrowed from every religion imaginable, will usually have a stable, improved program.",
"Github is an online platform for managing software code. As you can imagine, with dozens of programmers working on a project that could be several million lines of code, you need a good way of tracking who made what changes when, what those changes were, and so on. Github gives you that and some other useful tools like bug tracking, feature requests (for users to request new functionality) , and some other project management tools. Some people have expanded its use beyond just code. After all, code is just text with a particular meaning to a compiler for that language. So they'll use GitHub to manage other text-based documents where they also need that level of tracking and group editing capability.",
"There is a version control tool called \"Git\" that software developers use. It handles incremental version management of software so that you can have multiple branches and handle merging them together, or do things like handle rollbacks. GitHub is a service that offers a centralized repository for Git. You can push your repository here and other people can pull from your repository. The best explanation... GitHub is to Git as PornHub is to Porn.",
"A site to share program code and collaborate with other software developers. It's not that different from a plain old filesharing service like Dropbox. It has however a massive amount of tools that simplify working as a team on a single piece of code, in its entirety called **Git**. This makes it possible to e.g. \"fork off\" your own versions, make changes, and then automatically \"merge\" them back into the main version after you've finished doing your work. And it's not the only site that uses Git in this way, just the most popular one. Git is free software, anyone with a web server could set up a similar service."
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i8g352 | Vacuum tubes. How and why? Transistors: Same question, but how are they better than vacuum tubes? | Technology | explainlikeimfive | {
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"People were using electric circuits to make devices. To turn a circuit on and off you need a switch. But a switch that you push with your finger or engage with an electromagnet can be slow and easy to break. So they invented the tube. It works like a switch, but with no moving parts. Instead it uses an voltage signal to turn it on and off. That means you can switch it super fast. But it’s still easy to break because it’s made of glass and thin filaments. So they invented the transistor. Now the switch is just 3 layers of some materials encased in plastic. Still controlled by a voltage signal. It’s pretty sturdy, can switch super fast, can be made very small, but is vulnerable to over heating.",
"We wanted to modify and control electricity flow on-the-fly. Turns out, we can create an electron stream by applying an electric charge across a pair of plates in a vacuum, as long as we heated one of the plates enough to excite them. Then, we can put a screen across the stream to block or enhance the flow, therefore controlling it. That is a vacuum tube. Transistor control electron flow basically the same way as vacuum tubes, but they use a solid rock with pins attached to chemically modified areas instead of plates and screens. They have several advantages. They don’t need pre-heat so they save energy and start faster. They are much smaller so they save space and weight. They have fewer parts so they save cost. They don’t wear out like vacuum tubes. They do not require a vacuum so they are more rugged and durable.",
"Why? Amplifiers. Both vacuum tubes and transistors were invented for amplification of weak radio signals. The earliest radios drove a speaker off the power received by the antenna from the radio signal directly. Well, you can imagine - the power of the signal drops with the cube of the distance, so to reach a broad area you needed massively powerful transmitters, and you'd still only cover a small area because the volume would drop off to the point you couldn't hear it anymore. How? Well, that's two parts. First, the most basic concept - you have a big current - say, from your wall outlet, and that current is going to drive the speaker. That big current is controlled by some sort of electrical valve; crack that thing open a little bit, and you get a trickle, open it all the way, and you get a torrent, and everything in between. So the amount of the big current you get to drive the speaker is proportional to how much you open the valve. That valve is controlled by a little current, like the little current you get from your antenna. Amplifiers are more sophisticated than a single vacuum tube or transistor, they can, even back then, adjust themselves to normalize their output, so you don't get a louder and louder output just because you drive the ol' Buick closer to the transmitter. The second part is how they physically work. Vacuum tubes have two plates, one is charged with electrons. These electrons will flow as a stream through a vacuum from one plate to the other. There is a gate - a wire mesh that, so long as it has no current, will block the electrons. There are also elements that shape the electron stream. By design, they're very clever and simple. But their elements do get hot and burn out. They're not meant to glow like light bulbs, in that no one designs vacuum tubes *to* glow, they just do as a consequence. You'll notice the inside of the glass is silvered. After they draw a vacuum on the glass and seal it, they have a metallic layer on the elements designed to be cooked off when the device is first electrified at the end of their manufacturing. This metallic deposit, when vaporized, will bond with any stray gasses, and deposit on the glass. It actually makes for a more perfect vacuum. Transistors are a bonding of two metal layers, the combination which make up a P type and an N type. This isn't an alloy, it's a sandwich of two separate elements touching each other. We call it a junction, a PN junction. These two metals, whichever they are, have a curious property - electricity will flow in one direction, and be impeded in the other. It's a one-way valve. A diode. (There are vacuum diodes, too.) If you make a PNP or NPN junction, you have a transistor. Current wants to flow from one side to the other, but it needs a proportionate current in the middle to allow it. How the electrons actually, physically move from one side to the other immediately goes into quantum physics, and I'm not going to even attempt. As an addendum, these components, which are good for amplifiers, aren't necessarily good for computing. In a computer, you want a crisp on/off, but in an amplifier, you want a gradient. Luckily, these devices can be engineered to do a particular job better than another. The transistors in your computer would make for terrible amplifiers, and your amplifiers would make for terrible computers."
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i8giwo | why do some boats have 4 engines with 300 HP. Does the horse power stack? | Technology | explainlikeimfive | {
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"text": [
"This phenomenon usually happens with outboard motors, where the entire motor pivots and turns. A single 1200 HP outboard motor would be impractically enormous. 4 x 300 HP gives you the same total power but in a much more convenient package. Because you can hang the motor out the back, it also takes up way less space inside the boat hull than one 1200 HP would. You also get the advantage that if one engine dies, you still have 900 HP to work with. If you have only one 1200 HP engine and one engine dies you have nothing. This advantage drops off really fast in $ terms, so it usually manifests as two motor installations, very rarely three. More than three is purely for packaging efficiency, not redundancy. Depending on how fast the boat is and how the drive works, there can also be speed reasons. Going very fast requires a very fast propeller and it's easier to spin smaller props quickly. A 300 HP prop is a lot smaller than a 1200 HP one. Four smaller props putting out the same total power is a lot (lot!) less propeller weight and complexity and draft.",
"Yea it stacks, it's putting 1200hp into the water. It's not only for the speed/power, it's for redundancy, packaging, and price. Multiple 300hp outboards is cheaper and easier to service than a single 1200hp inboard. If your single 1200hp fails, you're fucked. Even if 3/4 of your 300hp outboards fail, you can limp back to the dock."
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i8m444 | Why all camera lenses are circular but photos and videos are square | Technology | explainlikeimfive | {
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"text": [
"The film strip (in a film camera) or the sensor (in a digital camera) is rectangular. Fancier cameras actually show you inside the lens what parts of the photo will be captured and what parts won't be.",
"Manufacturing lenses is done in a circular manner (or more accurately, spherical). The curve of lenses actually match the curve of spheres of certain sizes, so all the cutting is done with appropriately circular tools. If you went and shrank it down to a square lens, you just add room for problems. Damage while cutting, or alignment problems. You can leave the lens round just fine. As for why the photos/videos are square, we originally recorded everything with analog film. A film strip was just a continuous feed of stuff to record on. If you have rectangular recording area, you can pack it nearly 100% effectively. If you have a circular area, you're going to lose a lot of packing efficiency on that strip."
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i8o23s | How did we get computers to understand anything in the beginning since it's just electrified rock? | Technology | explainlikeimfive | {
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"text": [
"Just for clarity, the computer doesn't understand anything and it doesn't think. It's just a bunch of switches (on = 1, off = 0, usually). We figured out how to connect switches in clever ways to implement simple logic functions like AND, OR, and NOT. You could do the same thing with a bunch of hardware store wire and some light switches if you were so inclined. All the computer does is have a *lot* of switches and move them really fast. All of the fancier functions that we make computers do, like image processing or video games or figuring out how proteins fold, are eventually reduced to a bunch of very simple binary comparisons running really fast. In the very first computers you had to hard-wire all this stuff yourself. Programming literally consisted of stringing wires. That sucks, so we've found progressively more efficient ways of doing the programming. Today you write in a programming language. The compiler takes that language and translates it into simpler instructions called assembly code that are hard wired into the computer processor.",
"Computers don't think. Computers are huge chains of cause/effect dominoes. [Here's a bunch of wood that adds in binary]( URL_0 ) A CPU is the same sort of thing, just much, much, bigger. That's a block that adds. Imagine a block that multiples, a block that divides, a block that compares whether A is greater than B, and they are controlled by another block that decides what block gets to perform the work depending on what configuration of marbles is used... and that's kinda what a CPU is on the inside."
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i8q93m | How does hacking work? | I dont have any plans of hacking or anything like that. But I am genuinely curious to know how the hell you can manage to break into cyber security and steal all sorts of information and cause damage. How does that even work? How can such a feat even be possible? | Technology | explainlikeimfive | {
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"text": [
"Hey, CS major here. Computers have a lot of quirks in their construction at a hardware level and at a super low level of code(think binary or assembly code). These quirks can be exploited and abused to gain control of a computer or some other data. Also, coding languages like C have quirks in them that allow for them to be abused/hacked. I can get more technical and explain types of hacking if you want! Finally, some people when coding aren't security minded and don't secure their encryption keys or other important data, so it can be super easy to steal. Some people post their encryption keys in public places without even knowing it. Quite a bit of \"hacking\" is people looking for unsecured keys online, then using those keys to get direct access to the information they want. I don't necessarily consider that last part hacking because they aren't manipulating code or hardware, but it achieves the same purpose as hacking. Hope this helps!",
"How do you break into a house? Well, the more you know about houses and house security, the more you can figure ways to break in. It's the same with computers and cyber security. The more you know about how different systems are built and how they're protected, the more you know about vulnerabilities and how to break in. There are also examples of how people have done it in the past, which can serve as a bit of a guide.",
"Software and computers and the security devices that protect them are created by fallible humans, and therefore have gaps and oversights that can be exploited by others. Granted, the “hacking” that you see on TV and in movies is dramatized and overblown. Most hacking originates from social engineering, using tricks and psychology to obtain credentials (usernames/passwords) or physical access to systems/areas through legitimate entry points. Sometimes it’s just a weak password that is easily guessed. I once had a coworker who was responsible for a breach (luckily by a paid tester) because they set their password as “password”, and they had administrative access to everything."
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i8qgik | Why is wireless power so difficult to implement? | Technology | explainlikeimfive | {
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"text": [
"Wireless power is actually incredibly easy to implement. Tesla did it for kicks. What's hard is doing it efficiently. You're sending power in all directions, usually. That's a lot of power going nowhere in particular. If you want to, you can instead direct power into a beam. This needs to be actively aimed (relatively expensive to achieve prior to maybe 1980), but still suffers from significant transit losses over long distances. These losses are quite huge, and get significantly worse when weather gets bad."
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i8r50q | How do video game engines work and how do they differ from each other (Unity, unreal, etc)? | Technology | explainlikeimfive | {
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"text": [
"They're basically a framework that has all the super basic shit like lighting, shadows, movements, some ai behaviours and physics and all that prebuilt so it doesn't need to be coded every single time. You just make the engine once and then every time after that simply customise or change what's there and add new stuff. They differ cause they serve different purposes. Like Havok is a physics engine. That's all it does. Most devs used their own engines now though that are specifically catered to their own type of games."
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i8t8cp | What IS Electricity? | I think it’s the flow of electrons, but how does a couple of tiny bois flowing run an appliance like a blender or a computer | Technology | explainlikeimfive | {
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"text": [
"1) More than a couple. Copper has 85,000,000,000,000,000,000,000,000,000 free electrons per cubic meter. 2) The electromagnetic force is very strong. 37 orders of magnitude stronger than gravity.",
"Technically it is the flow of charge. 6.25 x 10^18 electrons per second pass in one amp of current, so it is much more than a couple. This flow of charge can cause a motor to spin or can switch a transistor on or off. In the case of a blender, the motor is driven by converting that flow into mechanical power. Transistors, transformers, capacitors, and inductors can store or alter the characteristics of that electric flow by reducing current, increasing voltage, or storing charge.",
"Can I ask a follow up?? Why can I hear the electricity running in, for example, my phone charger sometimes?"
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i8tz51 | How does a GPU differ from a CPU? | Technology | explainlikeimfive | {
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"specializaton. Chips have hardware in them that perform various tasks. CPUs have to be very general because they need to be able to do everything. With a GPU, you know what tasks you're going to do frequently and you can design hardware to do it. So a GPU might require less instructions for the same tasks. Additionally, GPUs have a LOT more cores than a CPU (my CPU has 4 while my GPU has 1664). A GPU can split the screen up into a bunch of tiny chunks and work on each task independantly. You can typically do this to some extent with CPUs but typically not as much. Doing this allows you to have slower cores while still completing tasks faster.",
"Rhey dont. A CPU is perfectly capable of rendering an image, it'll just be VERY slow. A GPU is designed specifically for video signals, and tend to have a lot more cores. For example the current highest score count CPU is a 256-core AMD Ryzen. Last I heard (this is almost definitely out o fcb date now) a high-end NVIDIA card (1080TI I think?) had ~4096 cores. A CPU is great at doing a few complex calculations happening simaltainiously. A GPU is amazing at doing hundreds to thousands of short calculations simaltainiously.",
"I don't think you'll ever get a more elegant picture of the difference than the [Mythbusters' live demonstration with paintball cannons]( URL_0 ). To summarize, a CPU is tooled to be able to do all kinds of tasks... whatever you want it to do, really... just with the restriction of one at a time. That's represented in the demonstration by the \"smart\" cannon that draws the image, one shot at a time. A GPU, on the other hand, is more suited to doing lots of instances of the same task, all at once. This makes it great for, well, graphics, as that tends to involve tons of small but incredibly numerous and repetitive tasks. This is represented in the demonstration by the multi-barrel cannon. Every barrel has one task. They all have the same task. And they all execute in tandem. But it can't really do much else.",
"The same way that a 4 door sedan is fundamentally similar to a 2 door sedan, both can fit 4 people comfortably, but the 4 door sedan lets people exit and enter the car faster from the back seat. The 4 door sedan has been optimized to let people in the rear seats enter and exit faster than the 2 door sedan. A CPU is a general purpose processor. It processes simple tasks and complex tasks at the same rate. You can ask it to open a word processor program, to browse the web, to play a game, whatever. Everything will happen at the speed the CPU processes stuff. If you ask it to draw 3D images, it can, but since it's not specialized to do so, it's going to do it at the same rate as it does everything else. A GPU is a specialized processor. It has been designed to be very efficient as drawing 3D graphics on your screen. It has all sorts of instructions built in to do light tracing, shadows, smoothing, water, etc. But that special design has made it not good running simple programs, browsing the web, running word processor programs, etc. So there is a trade off."
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i8yncu | How does doxxing work? Besides the obvious, personal information, what should I avoid sharing online? | Technology | explainlikeimfive | {
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"Your name is Abdullah, you are 29 years old and live with your parents. You're from Pakistan and are a semi-devout Muslim. I found this from a brief scan of your Reddit history. I also found a link in one of your posts that, in the metadata, showed your full name. Upon googling your full name and occupation, I found a website that uses the same icon from your Reddit profile. I also found your LinkedIn and Instagram page, the former of which states what city you live in and latter of which contains pictures of you in various places around that city. Several of those pictures show pictures of both the inside and outside of a house, which can then be cross referenced against pictures from Google Street View to locate your approximate (if not exact) address. Public records associated with that address reveal the names of two people who share the surname from your LinkedIn profile, along with the phone number of those two people, which based on your Reddit posts, would also be your phone number. A search through a combination of leaked databases and public records found several email addresses associated with that phone number, one of which closely matches a username you use online. So with a little bit of digging, I found your name, phone number, home address, email, occupation and age.",
"Where you live, car you drive, pictures of you inside or near where you live, places your frequent, location of your work. A couple of those pieced together with other info can make it really easy to doxx someone. Most of all if you buy a house, don't post it on reddit. That makes it too easy.",
"Anything that could be tracked back to you. Doxxing doesn't have a specific method, it's just scraping together all information you can get and try to interpolate from that. The less different kinds of information you share the harder it gets, and especially when you use different accounts for different things that can't be linked together."
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i8ypx1 | Why are video games more GPU-intensive than movies? | You can watch movies at highest quality without needing a dedicated GPU, but video games almost always require a GPU. What is it about gaming that makes it so resource-intensive as compared to videos? You can explain this with technical lingo if you want. I do understand the basics of computers and gaming so even an intermediate level explanation would be great. Thank you! | Technology | explainlikeimfive | {
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"Because the video is just a row of still pictures, where the videogame is actually a 3D simulation from wich your GPU calculates a 2D picture every frame. Depending on how \"AAA title\" that videogame is, there might be super intense calculations to find the lighting of objects (the GPU calculates every lightray individually, potentially reflects them several times and so on.",
"I shall try to explain in an analogy. Imagine that you are an artist, Mr. Game, showing off a bunch of paintings. You bring along 5000 blank canvasses and all your paints and tools and equipment. Then, Mr. Player from the audience loads up the Game Genre: A forest. Okay, so you kind of have your idea of what you want to show. So you have to paint it now. But Mr. Player wants this painting in ONE SECOND. Oh dear. That's hard. But somehow you get it done. But it's not good enough. Mr. Player wants the same picture, but one degree to the LEFT. Now you have to do it ALL over again, and also in one second. Luckily, you brought along your auto painting machine Mr. GPU who can help paint these paintings by feeding it some general information and directions. It is still a HUGE amount of work, but somehow with you two working together, you are able to present all the pictures that Mr. Player requested. Now, take Mr. Video. Mr. Video is smart. He does NOT take requests. In fact, he is the one who dictates what people see, and it will always be the same all the time every time. This means he does not need to use the help of Mr. GPU robot as much. He already has made 5000 painings at home, HIMSELF, and brings them all to the museum. The only thing Mr. Audience can do is request to see the next painting in the sequence, and if Mr. Video feels up for it, he will show a painting by request. Flipping through all those paintings is a breeze with his mpeg file cabinet and mediaplayer robot file picker. It's barely any work at all, but it comes at a tradeoff of the Audience not being able to alter any of the paintings. In essence, a game is making everything up on the fly, EVERY second it has to render a billion things, taking into account programming and actions on the side. A movie file is PRE RENDERED, meaning all the information is there and doesn't change; it just gets PRESENTED to you, and thusly needs a lot less computing power.",
"Movies are just a series of images in a storage medium, along with some audio data and some subtitles maybe. Games (especially 3D games) are taking models, textures, logic, lighting, audio, input, etc, and turning them into images the same as a movie, but in real time, rather than everything being already done by the movie company. It's like asking why does it take more resources to get a painting of a lake when it takes next to no resources to get a photograph.",
"Because the movie scenes are rendered once, in the studio, with powerful processors, and it takes hours to do, while your game has to do it in real time.",
"Your computer doesn't need to figure out how to change the image when thor drops down with a giant hammer and slams the ground. It just needs to play back a series of pre-rendered images. Your computer is basically making the movie as it's playing it when you're playing a game.",
"A movie is pre-rendered, meaning all the math related parts of it like CGI, special fx, compositing, etc. that might be done with a computer are already finished and all your computer has to do processing wise is maybe decode some compression. A video game is rendered on the fly based on player input. So it has to calculate everything as it happens using the rendering engine. For most games these days that means a lot of complicated 3D math which is exactly what GPUs were invented to solve. They usually also handle the bulk of physics calculations as well so you can have ragdolls when enemies die or seemingly simple looking things like cloth physics. Tldr; games are created in realtime and movies are just recordings being played back."
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i8yw7k | How do fingerprint sensors on our phones work? | Technology | explainlikeimfive | {
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"I assume you want an answer from someone who actually knows their stuff, but since no one is replying I decided to do a quick google search and copy & pasted this from [ URL_0 ](https:// URL_0 ). & #x200B; > The way an optical **scanner works** is by shining a bright light over your **fingerprint** and taking a digital photo. The light-sensitive microchip makes the digital image by looking at the ridges and valleys of the **fingerprint**, turning them into 1's and 0's, and creates the user's own personal code."
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i8zlpw | Why does film footage shot in the 50s still look great now? | I was watching the trailer for this film, where the footage was shot in 1953 [ URL_1 ]( URL_0 ) How come it looks so good even now? | Technology | explainlikeimfive | {
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"Film is a super good way to image movement. Professionally made movies of the 1950s have higher resolution than 4K video, because they used a better sensor. The cost of all that film was super high, so that's why we don't do things that way anymore. We've spent almost 100 years trying to get the quality of film at the cost of digital.",
"Back then, videos were shot on film. Film doesn't have a resolution like a digital camera has, but it has a grain size - that's the average size of the particles that react to light. The bigger the grains, the more sensitive they are to light, but they will also result in [grainy]( URL_0 ) photos. Inversely, smaller grain film required lots of light to work, but could achieve high quality. So sometimes, old footage looks great today because they shot on large diameter, small grain film under good lighting. Sometimes it doesn't, because they shot on small diameter film (such as 8mm) using too little lighting. Now the reason we think of old videos looking terrible is that a lot of stuff was shot on TV-cameras and stored on tape, which are limited to a low resolution and have bad contrast compared to the film cameras used before. They did this because it was a lot cheaper, and if it wasn't going to run in theaters anyway, there was no point using film."
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i90ikl | Software Defined Networking (SDN) | What is SDN? How does it differ from the 'regular' internet that we use? | Technology | explainlikeimfive | {
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"You know virtual machines? SDN is like virtual machines, but instead of running Linux/Windows, you run router and switch operating systems that connect to each other inside the host computer's memory and to outside networks/computers via the host compuetr's (numerous) ports. This means you can rearrange entire network topologies without moving a single wire."
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i90l0s | With how far we’ve come with technology, why are computers still made with x64 architecture rather than going to something higher? What’s keeping it at that point? | Technology | explainlikeimfive | {
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"There's not really a point. The reason we went from 32 to 64 bit processors was because we started hitting the limit of RAM at 4GB. This is because processors had to say where in memory they wanted to address in a single instruction, so they were limited by the number of bits the CPU could handle at once. When we went to 64 bit processors, we can now address up to 16 Exabytes of RAM. When we eventually get close to that, we can look at going from 64 to 128 bit, but we're still a few orders of magnitude short.",
"I'm assuming you mean 64-bit in general by \"x64\", which is just the 64-bit version of the popular x86 architecture. What stops it from being replaced is the property of exponential growth. 64-bit systems can't only handle numbers twice as big as 32-bit, but 2^32 times as big. And 2^64 is a number large enough for most intents and purposes. 2^32 seconds are a little less than 140 years, 2^64 seconds are 585 BILLION years, or 45 times the age of the universe. And for the few applications that need larger numbers than that, there are mathematical tricks to calculate with larger numbers even on 64-bit systems. You lose some efficiency, but considering how rare these applications are, it's nowhere near worth changing to 128-bit for just that.",
"There is no point in using a more than 64 bit architecture in mainstream CPUs. We are *nowhere* near its limitations, and adding more bits increases CPU complexity very fast.",
"I work in processor architecture design, so I can answer the question. But I'm going to simplify a lot of things here. Latest CPU have a 512 bit datapath and most common ones have a 256 bit datapath, per core. And for GPU we are more into the 512 bit to 1024 bit, per core. But at the same time, CPU are still 64 bit, and GPU are still 32 bit. But what does that mean? It's because that datapath bitwidth can be split into smaller chunks. If you have a 512 bit datapath, and do 32 bit operations with it, you get 16 operation per cycle. If you do 64 bit operations with it, you get 8 operations. It happens that nobody really rarely need more than 64 bit computation, and when we do we can do it the \"slow way\" which is 3 to 4 times slower. (In C you can use int128_t to do 128 bit computation on a 64 bit CPU for example, computer are Turing complete after all) GPU tend to do graphics, and in that domain 32 bit is already more precision than needed. So there is a tiny bit of hardware that can do 64 bit computation, but most of it is dedicated to 32 bit or less. Modern GPU actually bring back 16 bit computation as machine learning is happy with that kind of precision. Note that we kind of stopped increasing the datapath bitwidth of our cores and started to go with more cores. Because we might as well do completely different operations at the same time, instead of big bunch of vector operations.",
"Simple: more is not better. 32 bit allows you to build a computer that can natively address 2 Gigabytes. 64 bit allows you to address over 8 billion gigabytes. Not twice as much, but 4 billion times as much. A 128-bit computer can address more, but we're not even close to (nor do we expect to get close to in the foreseeable future) maxing out this capacity. So there's just no need for it. While it's true that a 64 bit computer can process bigger numbers than a 32 bit computer, at the end of the day, there's twice as much of everything in the cpu. Which uses up more power, makes bigger chips (which have to run at a slower clock speed), gives worse yields (twice as much transistors on a chip means there's a higher chance of getting defects in any one chip), etc. 64 bits is kind of a sweet spot that gives us unfettered access to as much memory as we can practically put in a computer while not consuming too much power and giving acceptable yields. If we want to process tons of data, we now have gpus that can be used, that are better suited for that kind of task. edit: I messed some numbers up by a factor of two. 32 bit allows you to access 4 gigabytes, not 2. 64 bits allows you to access 16 billion gigabytes, not 8 billion",
"there is no purpose ...yet. consumer tech is nowhere near reaching the limitations of x64, going further atm is not only not necessary, its not profitable because it makes CPU design more complex for lil to no benefit. for the very few applications for addresses higher than what 64 bit allows, modern CPUs have instructions that enable them to perform calculations of values in the 512 bit range(obviously gonna be much slower since this often requires multiple cycles and more memory space, but it IS possible)"
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i91gpy | What is the "silicon lottery"? What makes 2 of the same model of CPUs better/less suited for overclocking? | I'd like to know what makes them behave differently even though they are the same model. | Technology | explainlikeimfive | {
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"The silicon chips is manufactured at extremely high precision, on the very limit of what we are able to produce and indeed what is physically possible to produce given the size of the atoms. So sometimes the exact distances between semiconducting elements and the width of traces might varry a bit. This is normal manufacturing defects and can be caused by random vibrations, temperature differences or just the random positioning of individual atoms. But this means that some of the elements like transistors, resistors and diodes might behave differently between dies and differently from each other on the same die. This is called the sillicon lottery because even if the chips are of the same design and manufactured the same way you do not know how bad the manufacturing defects are until the chip have been made. Manufacturers therefore add tolerances and allow parts of the chip to run at a lower frequency or even shut it off if it turns out the defects are great enough. They can then be sold as cheaper units even though they were manufactured as more expensive units. This process is called binning as each model is a seperate bin that components are put in after their evaluation. End consumers may also take part in some of this silicon lottery. Sometimes the manufacturer runs out of some of the cheaper models and therefore have to take perfectly good higher quality chips and sell them as the cheaper models. If you get one of these chips you might be able to push it past its expected performance. But even within each model there can be a wide range of possible chip qualities that are just sold as the lowest common denominator. If you are lucky you can get a chip that just bearly failed to qualify as a more expensive model. Especially the most expensive model can have a wide range of quality. A third possibility is that a chip might have failed to certify as an expensive model because it performed worse under higher temperatures. In this case it is possible to get a much better chip by just adding enough cooling instead of the stock cooling option.",
"It’s the manufacturing process. So for one model, through a manufacturing run of 1 million units they’re not actually gonna come out to exact specifications. There’s variation. Now as long as the variations are within acceptable tolerance then they’ll be sold to customers. The ones with variations with higher performance would be considered silicon lottery."
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i93gy9 | On MMORPGs, how can a server laglessly handle thousands of players across the entire game world, but experiences problems when lots of players are in one place? | Evening. Not sure if this is the right place to post this question, but I thought I would give it a try since the internet and networking seems super complex and I'm not a big brain. I play WoW and Final Fantasy XIV. Recently I've been in areas where hundreds if not thousands of players are in the same area in the game world. Client-side computer graphics/processing capacity aside, how come servers seem to chug/have lots of lag when everyone is one place, aside from that same amount of people being spread out across the game world? In WoW especially, the play quality of an entire server begins to degrade when this happens, despite few players being outside of that one area. Edit: Well, that's a lot of answers. Thanks to everyone who has replied, I think I understand it a little bit better now! | Technology | explainlikeimfive | {
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"Hi! 20 year MMO server-side engineering veteran here, so I'm delighted by this question. The best way to answer it is with a very specific example, to get you a general idea. One of the most important checks a server has to do is to verify whether players are colliding with each other, or the environment, or are aimed right for weapons fire, etc. Because these checks are computationally expensive, we resort to clever tricks to avoid having to do them for everything in the world every time. One trick is to partition your world. Take your game map, and divide it into four quadrants. If two players are in the same quadrant, you know you have to look closer to see if they're colliding. But if one player is completely in quadrant 1, and another is completely in quadrant 4, you can skip that check because you know there's no way they can be physically touching. But say two players are both in quadrant 1. Well, you can also subdivide quadrant 1 into four quadrants! 1a, 1b, 1c, and 1d. Now similarly, if both players are in 1a, you need to look closer. But if one is in 1a and another in 1d, you can skip checking them. You keep doing this until the quadrants become so small that further partitioning isn't very useful. Another benefit with this approach is parallel computation. For example, you can have one server thread or process running the check on everyone in quadrant 1, and a separate process running it on everyone in quadrant 4. They can do this independently because you know you don't ever have to compare anyone across these quadrants. Trouble is, if EVERY player is in tiniest quadrant 1a-iii., now you're back to having to directly compare every character to every other character in the most expensive way possible, and there's no super easy or cheap ways to parallelize that computation. And that's when your server hardware starts to choke. This example is only about collision. But the point is, there are probably 9-10 different places in MMO server development where we *conceptually* take similar shortcuts -- even down to simple things like just how much data a server can physically upload to players over its network card at once -- which rely on the assumption that not everyone is in exactly the same place. (Edit: tweaked a few words for clarity, based on some of the excellent follow-up questions I got asked.)",
"Servers have to work harder when more people are in the same area. If two people are in different areas, there is no need to check if they are colliding, for example. There is also no need to even tell the players where those other players are. But when a lot of people are in the same area, more data needs to be sent out and more calculations need to be made.",
"Because now it needs to handle sending everyone’s information to everyone else. When you’re on the server, and move your character, your computer sends a message to the server with what you did, and then the server, takes that, interprets it, and sends it to any other players that can see you to display it correctly on their screen. When there’s just handfuls of people grouped together, this isn’t too bad to do. But when you have hundreds of people all in one spot, that then means every little action you do, instead of being forwarded along to say 10 people, is getting forwarded along to 100 people. And the same goes for everyone else, so you get and order of magnitude larger number of actions that the server has to deal with, causing it to lag.",
"MMORPG is like McDonalds. It can have many stores around the city so that everyone can order happy meal. However, if everyone in the city goes to the same McDonalds stores then that store does not have enough happy meal for everyone.",
"The goegraphical area of the game \"world\" is usually spread out amongst individual servers. A particular town or region and usually specific dungeons (or instances) are handled by specific servers or farmed out to temporary servers (\"shit, < twitch streamer > streamed a raid on the Dragon of Light temple, now everyone is raiding there! Spin up some extra server shards to handle the Dragon of Light raid\"). It could be that some MMO platforms allow for load balancing and sharing between servers, or allow for extra capacity to be called on.. but that stuff is hard. In the context where a dungeon is \"instanced\" i.e. when you raid with your party you exist in a specific instance of that dungeon. Its not like 11 different parties are raiding the dungeon all at once, you'd trip over each other. However in the context of an un-instanced environ, the more players present, the more work the server has to do. Or maybe the server can only do x ticks, or slices per second and beyond Y players it can't do all of them, so it will priorities the ones that got missed THIS slice to be done first the next slice... and so on. Or it can just skip players at random leading to glitching, stutters, jumps etc. EVE online handles this differently. TO over simplify, each solar system... or each space station, planet is a server. Beyond maybe a few dozen players in the same spot, the server runs out of time to process player actions and redistribute to every other player. So instead of skipping players, or time, it _slows time down_ using time dilation. Don't ask me how the \"slow\" zone matches up with the rest of the universe I dunno (I think they just ignore that for simplicity), but time dilation with hundreds of users fighting in the same spot can slow time down by orders of magnitude. Check out URL_0 - where like a considerable portion of the entire userbase was fighting the same battle. Time was slowed by like x1000. If your real-time weapon recharge was usually 30 seconds, it now takes HOURS. But in that game its better than being so glitchy its unplayable. Works for them.",
"Because of the N\\^2 problem 10 people? 10 people have to be sent to 10 people, 100 events. 100 people? 100 people have to be sent to 100 people, 10000 events. 1000 people? 1000 people have to be sent to 1000 people, 1000000 events. It takes CPU time to do all the computations involved in sending player equipment, positions, and aim positions for example. As other people mention, each map area is its own server which means the load can be distributed among servers. They don't do that when players are in the same area. ( It is possible, just uncommon and difficult to solve cross server communication live )",
"What you call a server and what an infrastructure engineer calls a server are two different things. If I connected to my WoW server, the box that is processing my character in Orgrimmar is not necessarily the same one as the one processing in Stormwind, or the same one processing instanced dungeons. Your character will get handed off to whatever actual server is doing the work for that region. The more people in that region, the more work that one particular server is doing.",
"I'll use Eve Online as an example, because it's a \"single shard\" game... literally everyone plays on the same shard... everyone is in the same instance, there are no different instances you can connect to (there's one for experimenting with stuff and testing changes, but that one gets wiped regularly). **Yet, the shard itself is comprised of many servers. Systems, and even entire constellations share a single server. Each system is isolated from the next, so there's no potential for players on different physical servers to interact with each other (which would be very hard to implement).** That there is the crux of it. Interaction. When players need to interact, they need to be on the same server so that things happen in the correct order. When they don't need to be interacting with each other, they can be on whichever server they want. And the devs spread out that load as much as they can afford to do so. Yet in Eve we're well known for having [very]( URL_1 ) [large]( URL_2 ) [Battles!]( URL_0 ) Because of how insanely autistic we are about Eve (spaceships are very serious business), we plan ahead and warn the devs when we're going to have a big fight (the writing's usually on the wall already, but we make sure). In doing so, they move that particular system onto a dedicated high power server (they call it fortifying the node). It's still generally not enough, so they also implemented a very innovative system called TIme DIalation (TiDi), where they literally just slow down time in the game... if it took you 10 seconds for a cooldown before, at 50% tidi you'd take 15 seconds to do it. Which in essence doubles the amount of time the server has to handle everything. It goes all the way up to 90%. TiDi is unpleasant, but it lets the fights go on. Sometimes, for days. Which is better than just crashing the node, which we still manage to do from time to time even with Tidi and a fortified node.",
"In WoW specific, people have speculated in combat its the amount of procs and rng effects every player has and can create. Specially in BFA with azerite gear, essences and Corruption. All of those systems are to 90% RNG effects/stats procs. Preach has a really good video on that topic. Those are only speculation, but some devs of other games have mentiones rhis could be a cause. Also don't forget WoW is more then 15 years old and the Engine isn't extremly good optimised for the newer processes/ architexture etc. [Preaches video]( URL_0 )",
"Regardless of how many players are in the world, *each* player is only getting information about the players around them. A thousand people in one spot mean that the server is mediating the input coming from all thousand of them *and sending it to all thousand of them*, every frame.",
"The same way there can be thousands of miles of open highway on earth, but you're still stuck in traffic.",
"Some great answers & discussion in this thread, and I'm probably too late for this to get seen, but one factor I've not seen explained simply which very much applies to the example you asked is the following: The server has to communicate the location of nearby players to your client and your location to those same nearby players. It obviously doesn't have to exchange locations for people in a different zone, because we aren't concerned with those. This creates an exponential growth in traffic as more people are in the same area. Imagine 10 players are in an area. Each player has to be told the location of the 9 other players. That's 90 'location' traffic 'packets' the server has to handle. Now imagine there are 100 players in the area. If the growth was linier we'd now expect the server to have to handle 900 location packets, but it's not, because each player has to be communicated the location of each other player it's actually 9,900. For this reason large numbers of players congregated in a small area is much more taxing than the same number of players spread across the map. And of course location data is just one example - other things that need to be communicated to other players face this same exponential issue - imagine all the data having to be communicated when lots of people are fighting in a small area.",
"For WoW specifically, Preach did a video explaining the current lag that happens in BfA. URL_0 starts around 3:10 if you want to skip the intro. At some point later Blizz even sorta confirmed it by referencing Preach's video."
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i98i5v | Why is it so hard to make flawless collision detection in video games? | Technology | explainlikeimfive | {
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"Video games need to run the simulation very very fast. Typically they only have a few **milliseconds** to compute the physics for everything that's moving. To do this at all, they need to use coarse approximations, which sometimes fail to replicate real world physics correctly. > do developer's simply don't care enough A lot of games use third party physics engines. These are build by experienced devs using state of the art techniques and sold to game or engine developpers. Dark souls uses [Havok]( URL_0 ).",
"Ur basically asking \"why is it so hard to replicate real life physics in a miniature simulation of reality.\"",
"You have to define everything in mathematical terms. So to stop objects from passing through each other you have to define their shapes as geometry, then do calculations to check if the shapes intersect with each other, and then if they do decide where they should move to instead. Game models are complicated enough that they are made up of thousands of triangles. And accurately doing collision detection on all those triangles against all the other triangles that are in the scene takes a lot of processing power. So games usually use simplified geometry for physics detection that is good enough most of the time. It's better to do that than have a game that has perfect collision detection but runs at 1 fps. Then there's figuring out what to do if some geometry does overlap. In real life that can't happen because the universe runs at an \"infinite frame rate\" (not sure if that's technically true, but it might as well be). But in a game it's essentially making snapshots every 1/30th or 1/60th of a second or whatever the framerate is. So it's not always simple to resolve collisions that have theoretically happened between those snapshots. To complicate things further is the fact that for the most part animations are \"canned\", i.e. they are pre-recorded movements. There's usually some blending of animations going on to make it seem more natural, but it's not doing a full physics simulation of the character's muscle and bone structure. So if the animation causes the character's hand to go through something it's not simple to figure out where that hand should go instead. Games can deal with to some degree, but it's only an approximation and doesn't work perfectly in every situation and doesn't necessarily produce natural looking results.",
"You would have to drastically raise the hardware requirements in order to run the game since they have to calculate all of that in real time. Would better collision detection be cool? Yeah, it would be awesome. Are you willing to spend ten times as much on your PC or console to run the game now? Probably not. It's one thing to render a complex model on screen. It's another thing entirely to calculate and track every single point on that model and check it against every other point on every other model (including ones that aren't on screen right now, because you can also collide with something off screen if you are moving fast enough) and check for collision."
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i98r72 | Why does a radio work better when you put your hand on it's antenna? | Technology | explainlikeimfive | {
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"g1djjy8",
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"text": [
"you become part of the antenna. And can pick up more of the signal due to more surface area.",
"Because you also act like an antenna and the bigger the antenna the better the signal received."
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i98ycf | How is it possible that a cell phone tower can send out thousands or tens of thousands of messages and data simultaneously and everyone's phone knows exactly what data is meant for it , and how does it know exactly where you are to send the data to the right spot? | Technology | explainlikeimfive | {
"a_id": [
"g1dija1"
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"text": [
"Every piece of data is wrapped in the digital equivalent of an envelope with the \"address\" of your phone on the envelope. Your phone watches for packets addressed to it and ignores all others. The cell tower has to keep track of everyone all at once but that's why it has far larger computers to make it run. Your phone has a much simpler task...\"Is this for me? Yes, OK, I'll read it. No? Ignore it.\" The cell tower doesn't know exactly where you are, unless you're on one of the networks that trades GPS signals with the towers. It knows what direction you're in by which antenna is getting the strongest signal from your phone. It will check periodically and switch antennas if you're moving, or hand you off to another tower if some other tower is receiving you better. It's basically the same thing that a WiFi network is doing, except at much longer range."
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i9ar35 | Why do phone scammers often use phone numbers almost identical to our own? Aren't they intentionally making themselves look more suspicious? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"This is intentional. Scammers in general don't want to waste their own time and resources on people who won't fall for the scam. Making scams look like scams is actually an efficient strategy.",
"Phone scammers aren't targeting young, healthy adults. Young, healthy adults don't have much money and aren't likely to fall for any scam, regardless of how sophisticated it is. The people that they're targeting are very elderly people with dementia. Dementia is a spectrum and towards the middle of the spectrum people are still technically capable of living on their own, but no longer have the mental capacity to really understand the concept of lying and fraud. People who are suffering from this middling dementia are extremely likely to fall for any scam, regardless of how obvious the scam is. The problem for the scammer therefore isn't to come up with an elaborate, convincing scam but rather to just get the target to pick the phone up. The almost identical phone number is designed to confuse these people. They see a phone number that feels familiar and are likely to pick up the call even though they don't know who is calling. And again, the scammer's goal is just to get them to pick up the phone. Once the phone has been picked up there is a decent chance that the scam will work. People with dementia are unlikely to pick up a call coming from an unfamiliar phone number, if for no other reason than that many of them grew up when long distance calls were expensive.",
"They're trying to make you feel like it might be someone you know by using the same area code. You think, \"Hm maybe someone in my friends circle got a new phone\" or \"Maybe a company I applied for is calling to set up an interview\". You lower your guard and pick up the phone and then they blast their stupid recording in your ear.",
"This is called the \"neighborhood\" scam. In the US they use a fake number that uses the first 3 digits of your number. So if your number is 546-1363 they will call you with a 546-XXXX fake number The idea is that you recognize the \"546\" part and think its a legit call from someone you may know."
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i9g9y3 | What is “phone radiation,” and how is it different from EM radio waves? And how could it be harmful to humans? | I know some very intelligent people who believe phones, 5G, and WiFi are seriously dangerous I just can’t seem to understand why... | Technology | explainlikeimfive | {
"a_id": [
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"Phone radiation is basically a certain part of the EM waves, as are WiFi etc. There are people who believe it's harmful, because they think the EM-fields phones and anything electric and electronic creates (by just having an electric current run through them) induced electric currents in our blood, but that's not harmful, because if it even happened, the currents wouldn't be strong enough to deal any noticable damage. Some people also think those EM-waves used for phone and radio communication were increasing cancer risk, but while the waves are able to pass through our skin, they are not able to do damage to the DNA, wich would cause cancer (lower-frequent ultraviolet light would be able to cause cancer, but also doesn't get far through the skin)",
"There are two types of radiation: ionizing (it can cause electrons to move atoms) and non-ionizing (it can’t). Radiation used in phones and other wireless devices is low pier and non-ionizing, so it has no effect on your body. Microwaves however, while non ionizing, are at a frequency that heats water molecules, so high concentrations can cause issues with biological tissue. 5G is interesting because the GHz band of 5G is in the range that is emitted by falling rain, so it’s prone to causing interference with weather sensors and being interfered with by rainstorms. It also can’t pass through skin, which means while your internal organs can’t be affected by it, transmission power sometimes needs to ramp up significantly, which could potentially cause issues at the skin surface (but this has not been seen in practice at the levels cellphones and towers emit). Truth is, most “5G” is just LTE signals with stricter guidelines about what gets transmitted and fancier receivers that can optimize lower power bandwidth use — in other words, they’re less risky than previous versions. The high frequency 5G band is too short range to be used anywhere but in dense urban areas, and requires fast internet cables nearby to provide any useful service; as a result, even in places where high frequency 5G is deployed, most people will likely rarely or never use it.",
"Any kind of electromagnetic wave is considered radiation, such as radio waves, microwaves, infrared, visible light, X-rays... and the energy carried by these waves is determined by their wavelengths. The EM radiation is divided in two categories, ionizing and non-ionizing. Any wavelength within or higher than the visible light spectra is considered non-ionizing, which means that it doesn't have enough energy to detach electrons from atoms and molecules. That doesn't mean that it cannot do any harm, since it can cause temperature elevation, as does the microwave oven or the visible sunlight. However, there has been extensive research on the subject by the [ICNIRP (International commission on non-ionising radiation protection)]( URL_0 ) and there are several guidelines to limit the EM wave emissions in devices to levels that are safe for humans.",
"Phone radio, EM radio and wifi are basically the same thing at different frequency and treated differently. The waves themselves are just low energy electromagnetic waves, it can makes some thing to heat (microwaves and some infra-red). At the power these things are emited, it can't really hurt your body, but we're talking here about long term exposure to some electromagnetic waves that makes some materials acting weird, so I can understand why people are kind of afraid of that. I am sort of part of them, but not because I think it is harmful, but more because I think that everything you sell should be thoroughly tested to prove that it' can't be dangerous. & #x200B; Also, I think I read an article a few years ago saying that there is some form of tumors that can appears because of some of the radiation (electromagnetic waves if you prefer the fancy name) that your phone emit. But this was long ago, it didn't lead to anywhere, so I kind of stopped caring about that."
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i9gsr1 | how do computers actually store information? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It depends on the technology were talking about. WW2 computers stored information either by how they were hardwired or on paper. Your current computer on the other hand stores the information in the hard drive that is basically a disc that have tons and tons of tiny magnets that your computer can polarise in a sense or in an other. Then, you just have to tell your computer up = 1, down = 0 and voilà, it can store the information. Now, to read the information, I guess the computer also have a magnetic sensible part that can determine the polarisation of a magnet."
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i9j1oj | What is the internet cloud and what is the difference amongst SaaS, PaaS and FaaS? | Technology | explainlikeimfive | {
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"text": [
"Cloud simply means you use someone else's hardware. Instead of storing files on your local computer you store it in a large server and can download it everywhere you have an internet access. SaaS, PaaS, Faas and also IaaS are simply different ways how to use the foreign hardware. SaaS is Software as a Service, wich means a program is preinstalled on the server and you may use it remotely. PaaS is Platform as a Service, wich basically provides you an enviroment to program remotely",
"The internet cloud is just someone else’s computer. You can rent their computing power. SaaS means Software as a Service. That way, you rent a software (e.g. Office365) and can access it via the Internet. You only have to put your data in, everything else is taken care of. PaaS is Platform as a Service. That means you have access to a certain computer with pre-installed operating system (e.g. MS Windows) and can install whatever you want. FaaS is Function as a Service. This one is more abstract and can be generally seen as a combination of several SaaS. (e.g. Alexa Skills)"
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i9jyjc | How does a RAM array know where to load data from? (Adress in RAM array) | Hey there, currently I am reading `Code: The Hidden Language of Computer Hardware and Software` from Charles Petzold. I am more than half through but I am a bit lost here. [ URL_0 ]( URL_0 ) "As usual, the instructions begin at 0000h because that's where the counter starts accessing the RAM array after it has been reset. " But as seen in the picture, how does the operation code 10h point to the adress of 0010h? the opcode 10h just says "Load" I was looking long time for the answer but just cant get it in my head and really want to know how a computer works from the ground. | Technology | explainlikeimfive | {
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"text": [
"Every operation is made of 1 or more bytes. In your case first byte (10h) is code for Load, and next 2 bytes are address you are looking for (00h as high byte, and 10h as low byte). PS. In your example memory is arranged in big-endian order (most significant byte is on lower address). That is why values on addresses 0001h and 0002h combined give value 0010h. If you had little-endian (least significant byte is on lower address) memory organization, then value would be 1000h. PS2. More explanation on u/maximuse_ comment. Depending on processor, op -ode can be longer or shorter (1 byte, 2 bytes, 4bits...). And depending on op-code, you will have next bytes reserved for parameters of that very operation. For example, you could have operation Increment, which increments value by 1 in accumulator - you don't need any additional parameters (you know where accunulator is). So unlike Load, which requires 3 bytes, that increment would require just 1."
],
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i9jyl9 | How do touchscreens work? | Technology | explainlikeimfive | {
"a_id": [
"g1fhn04"
],
"text": [
"There are different concepts. The most common one is the capacitive measurement. The screen is slightly charged with an alternating electric field, and your finger changes how that field behaves."
],
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i9kh1q | How do radios work? What are radio waves and radio signals? What are radio frequencies? And how do antennas work? | Sorry for the large amount of questions about radios, im just really interested | Technology | explainlikeimfive | {
"a_id": [
"g1fo3dz",
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"text": [
"Radio waves are a subset of electromagnetic waves, a form of energy. Since your other question implies that you are an 11-grader, you should at least know about the electric and magnetic fields (if you don't, we'll explain). They are actually two \"sides\" of a single electromagnetic field and changing one of the fields produces another field (i.e. a change in the electric field produces the magnetic field and vise versa). This way, a disturbance in one point produces a \"wave\" where electric and magnetic field alternate between each other. This wave spreads out in all directions at the speed of light because a disturbance in one point affects all neighboring points. This wave can be described using its power (i.e. how strong the fields get) and frequency (i.e. how fast they alternate). If you divide the speed of the wave by its frequency, you will get its wavelength (i.e. distance between \"peaks\" of one field as the wave spreads in space) Visible light is an electromagnetic wave as well. A lot of [other rays]( URL_1 ) are electromagnetic waves as well. Radio waves are the longest of them all. Radio frequency is the average frequency of the wave used to transmit the radio signal (for radio stations 1 FM = 1 MHz or one million oscillations per second). To encode signals in the wave, they use [the process called modulation]( URL_0 ) where the wave is adjusted to represent parts of a signal (such as sound wave). Radio stations use frequency modulation (thus the name FM) where they adjust the wavelength. Amplitude modulation (where the power of the wave is adjusted) can be used as well. Antennas are basically pieces of conducting metal. When an electromagnetic wave hits the antenna, it causes an electric current to appear in it (this is called induction). This current can then be picked up by the device and decoded into the signal.",
"## EM Fields A scientist named Maxwell (after a lot of fundamental discoveries of equally important scientists before him) understood that there is a thing called **electromagnetic field** that permeates the universe. Think of gravity: there is this force that is able to attract things with no physical contact - the earth doesn’t have arms pulling you down, it just does. It’s nice to think of a Gravitational field, because in that way you can study gravity without bodies actually being there. It’s like saying “I don’t see anything falling in front of me right now, but I know *gravity is there*, and if there was something in mid-air, it would fall down.” Same thing with EM fields. They don’t act on masses, but they act upon electric charges. If something is generating an EM field, you know it’s there even if there are no charges to observe it. If there are some charges somewhere, you’ll see them interacting with the field. ## EM Waves One important discovery from Maxwell & friends is that the EM fields are not *just* stationary, but they can also oscillate and ripple. So, thinking of gravity (which can in some sense do the same!), a charge is not necessarily pulled by an EM field, but if the field is oscillating then the charge is subsequently pulled, pushed, pulled and so on. The cool thing about those waves is that they propagate in space. So if something generates a EM wave somewhere, you can see the wave somewhere else - just like the waves of the sea! And us humans discovered that we can encode information in those waves. Say, for example: I’ll send you big waves, then small waves, then small, then big and so on, and we have a way to interpret those waves, like if they were Morse code or binary numbers. A **radio signal** is just that: something “wiggles” the EM field in a way that a receiver can interpret. ## Wave properties Speaking of waves in general, there are various properties like amplitude (how tall the wave is) and frequency (how quickly it goes up and down). Frequencies are fundamental for reasons that are hard to ELY5, but let’s say that in general all things contain an “intrinsic” frequency information that you want to send, but they can also be used to encode data and to transmit data with no interference, like using different frequencies for transmissions is like having multiple lane roads where each car can do whatever it wants in each lane. ## Antennas Antennas are a very complex topic in the details, but at a basic level they are the things that allow us to send and read the “wiggles” in the EM field and also direct them. If I want to send you a signal it’s going to cost me some power, and I’d like the power I spend to be put to well use and actually send the information toward you. Waves tend to spread in all directions, and power that’s not going towards you is just wasted. Moreover, receiving antennas also help “scooping” a bit more power that wasn’t directed right on point to your device, but also slightly around it, kind of like a magnifying lens with sunlight. I hope I answered some of your questions!"
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i9l4n6 | How does CPU cache affect the performance/processing speed of a Laptop? | Also, what is a cache/cache memory? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"In general, the bigger the memory, the slower it gets. In pure theory, your computer could work by only using your hard drive. But it would take literal days to do any basic thing because the hard drives (also SSDs!) are SO slow. So there’s RAM. A lot smaller, but much faster than a hard drive. Your computer can work much better now. But still, RAM is kind of slow with respect to the speed of your processor. And so, the next step is cache. Cache is an even smaller, much faster memory that’s next to your processor so that it can do its tasks at full speed without having to wait for slow memories. The usual example goes like this: if you want to read a book, you could go to the library next to your house. But is it worth it if you only needed to cite a sentence? What if you need just a couple sentences from multiple books? You’d have to go there every time. Solution? You can rent some of the books and put them in your bookshelf, so that at least you don’t have to leave your house. And if you’re working with one book right now, maybe it’s easier to just keep it on your desk right? Same reasoning here. The bigger the cache, the bigger the desk, so that you can put more books nearby and reach them without leaving your chair."
],
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i9pxf2 | So, where do emails/texts/messages etc. go when they get lost in the interwebs on their way to the recipient? | Example: Sometimes, an email says it was sent. But the recipient has never received it. Same with a text or voicemail. Im just confused as to what happens! | Technology | explainlikeimfive | {
"a_id": [
"g1gmcpb",
"g1gnk5j"
],
"text": [
"Either to the wrong recipient or nowhere. All digital communication is a one way transmission, even video calls. It's just very quick one way communication from two sources. If the data you're trying to send doesn't reach it's intended destination, it doesn't go anywhere.",
"It depends. Sometimes it's as simple as user error or a typo, someone giving the wrong e-mail address or phone number or something like that. Other reasons require a bit of an overview about networking, namely that networks a lot of people envision kind of like a direct wire between two devices, but in reality the message has to be relayed across several devices on the way. When a message gets lost this way, and it wasn't that it went to the wrong place due to an incorrect address from the sender, then the culprit is generally that one of those hops along the way was unavailable or backed up, or the message was backed up and lost during a reset or soemthing. How this gets to happen after there's an acknowledgement of receipt is generally specific to the protocol, and there are as many weird ways for this to happen as there are ways to send a message over the internet, but in a broad sense the data just gets deleted or lost or misdirected somewhere in that signal chain."
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i9q3gw | Why do gifs take longer to load than videos? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Gifs have to load the whole file onto your computer before playing. Videos on streaming services are encoded in a way so that they load in order from start to finish. This process used to be called \"buffering\"; you would wait a few seconds/minutes after loading a page with a video, and then as the video played, in the background your computer would load the later portions of the video. Nowadays connections are fast enough that you generally don't have much lag time between loading the page and starting the video. Gifs were made a long time ago, before we had the sort of network speeds to conceivably send even standard-quality video across the internet, but loading several images was fairly quick as long as the images weren't overly large; this was all before there were protocols that allowed things like streaming, and so the .gif format doesn't have the advantages of those technological advances; for backwards compatibility reasons, trying to change the format now would be a huge headache. In theory, new formats could be created that could stream images like this, but in reality, loading that many images in succession is a big part of the strain on the system imparted by streaming a video, so there's not much benefit to not using an existing video format but not including sound, versus making said new format.",
"If you're using a gif as it was originally intended, for basic animation with large areas of flat colors, they load quickly, but the format was never meant for actual video. Video formats, however, obviously were made for video and are very efficient at encoding them. The file size for a video will be only a fraction of the size of the same video inefficiently re-encoded as a gif.",
"Videos are compressed across space and time. Each frame of a compressed video is compressed like a JPEG, and then they are compressed across time (if a 2nd frame is virtually identical to the frame before it, you can simply encode the difference between the two frames, and you'll be using much less data). Gifs are only compressed across space - it's a series of still images that are compressed individually."
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i9qfmm | how did/does a radio station know how many listeners they have that day? I'm really curious to this question posed in the 80s or 90s when tech was far less than now. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Surveys. Radio stations hire (usually) independent survey companies to run surveys in their area to get a rough estimate of what percentage of people are tuning in. This could take the for of in person asking if questions, phone calls going to houses, mail, or even online ones. Once they find the rough percentage of people that regularly listen, they can use that to estimate the actual number of people. Note that this is on average, they have no way of knowing how many people are listening at any one moment"
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i9ui48 | How does an SSD hard drive make a computer/console run faster? | I’ve heard that swapping the normal hard drive that comes with something like a PS4 with an SSD hard drive would make it faster, how does it do this? | Technology | explainlikeimfive | {
"a_id": [
"g1hj5dc"
],
"text": [
"An HDD has to physically move an arm with a magnet on it to read the data stored on a literal disc covered in tiny magnets. To read data somewhere else, the arm has to move again. Once the arm is in place, the disc turns so data can be accessed. when you read what you wanted, you move the arm and start again. With an SDD, the data can be accessed from anywhere on the disk basically instantly. there is no need to move physical parts, it is way faster"
],
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i9v40h | How do external hard drives work? | I suppose I’m actually asking a fairly specific question. I have an external hard drive that I’ve had for 6 years. The first time I backed up my hard drive was in 2014 and periodically throughout the years. I just went through a pretty big purge of pictures and documents I don’t want or need to keep anymore. I just backed up my computer again and I’m wondering if the external hard drive automatically deleted the files it had retained but that are no longer on my computer? Or do those files stay in the external hard drive forever, no matter what I delete from my computer? Should I wipe my external hard drive of everything and re-backup my computer with only the existing files I want to keep? I’m not tech savvy enough to accurately explain my question, so please lmk if you are confused. Answers would be great! | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"depends on what software you are using to take the backups. there are various schemes it could be employing like generational backups. [this page]( URL_0 ) summarizes the 3 main strategies."
],
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i9vft7 | Why do floating point operations often yield results that are very slightly off? | Technology | explainlikeimfive | {
"a_id": [
"g1hr88n",
"g1hpt64"
],
"text": [
"Computers store numbers in binary (base 2). They only have two digits, 0 and 1. So when we convert 0.1 into binary we get: 0.000110011001100110011001100110011001100110011001100110011001… (Note the 1001 repeats forever) We store binary numbers in floats or doubles with are either 32 or 64 bits. Since we can only store 64 bits and not infinite bits, we need to chop the number off somewhere. Once we chop off the end, and later convert it back into decimal we get: 0.1000000000000000055511151231257827021181583404541015625 Which isn't quite 0.1, but it's pretty damn close. So when we add that to 0.2 we get a number that isn't quite 0.3. When dealing with floating point numbers (numbers that aren't whole numbers), never compare them directly. You need to define what 'close enough' means. How you define 'close enough' depends on what you are doing. If this isn't good enough for whatever you are doing, you will need to find a library for arbitrary-precision decimal arithmetic. This will give you the results you expect, bu will be slower and use more memory.",
"Many terminating decimals do not have terminating binary equivalents. You’re picking up the rounding error when converting between the two."
],
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i9vp92 | What is the purpose of motion blur in video games? | Technology | explainlikeimfive | {
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"text": [
"Motion blur is added to games to give you an incentive to check out the settings menu as you immediately search for a way to turn off the motion blur when you see that a game has it.",
"First, our eyes don't \"update at 24-48 fps\", it is a continuous analog process where there are different response times to things like recognizing motion and processing what an image is of. 24 fps is just about the minimum required to convey smooth motion with motion blur. Motion blur is the consequence of how cameras work. A light-sensitive sensor or photographic film is exposed to light during a period of time appropriately called an \"exposure\". During that period of time things being imaged can move resulting in the light from their position being smeared across the frame. This results in motion blur, the blurry track of a moving object during an exposure. With multiple exposures this blurry track will merge with the end of the blur from the previous frame and start of the blur in the following frame, helping the viewer connect the images in sequence. Without motion blur a moving object seems to jerk between positions in an unnatural way (remember the eyes are anolog so motion is normally perfectly smooth).",
"Your brain will interpret 24 fps as continuous motion. But if those 24 frames are clear, in focus pictures they do not look realistic. Irl a car speeding by looks blurry to us, not a clear car moving bit by bit. \"Go motion\" was invented for Star Wars so the space ships would look blurring fast when they moved. Older stop motion had an unnatural look because everything was always in clear focus when it moved.",
"You can see the effect of motion blur in real life by just quickly waving your hand. Your hand is moving faster than your brain can process, so your brain kinda just guesses what happened by blurring what it saw together. Subconsciously, we perceive something moving and blurry as fast, and something slowly moving as clear. Since video games want to be realistic, adding motion blur helps maintain immersion."
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i9wb9h | why do some digital cameras struggle to 'pick up' on artificial light while others are great, and what kind of details can I look out for when shopping to predict its performance in low / artificial light conditions? | Technology | explainlikeimfive | {
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"Indoor lighting is thousands to millions of times weaker than outdoor lighting. *Any* camera is going to struggle with indoor or night shooting. Traditionally, increasing exposure on a camera will increase motion blur (shutter speed), depth of field blur (aperture/iris), and grain/noise (sensitivity). Smartphones have a tremendous advantage in processing power, being able to reduce noise and some blur, and adjusting color. Your action camera doesn't offer a similar range of exposure controls, as it is designed mainly for daytime video, and doesn't have flash for adding light. The screens from both will not be able to show you the full extent of noise or blur being captured. You'll get better video with any camera by using studio lamps to increase the amount of light in your scene. Typical room lighting will never be enough."
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i9wmwx | How does file compression work? | How can a file become smaller in size but still contain the same details like a picture or a game for example. | Technology | explainlikeimfive | {
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"text": [
"Typically algorithms are designed to find patterns and represent them in a smaller way. For example: AAAAAAAAAA 10A Both the above can represent 10 As. The first is 10 bytes and the second can be represented as just two bytes (if using int8)",
"The data of the following example file AAAAAAAAAAAAAAAAAAAABBBBBBBBBB takes up 30 characters of space. A compression algorithm with the task to reduce the file size might instead process the content to 20xA10xB taking up only 8 characters of space. While no information has been lost and some computing is required to restore the original file content, the file size has been reduced by 22 characters."
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