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5w1q9z | Why do most video games take 5-10 seconds to reload the level after I die? Surely all that needs to be "reset" is the player character if all the resources were already loaded? | Technology | explainlikeimfive | {
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"Depends on if the system has the memory to store the initial level state in memory while the user plays. Restarting a level may also require running a script to initialize the physics, object locations, NPC behavior, etc. Game designers may also just get lazy and totally reload the level to avoid any possible bugs with trying to reinitialize the level state.",
"Indie game dev here - so I'm not a professional/industry voice on this. In my games - to be super careful I when I load a game I make sure that everything else is destroyed/cleaned up so that there's no chance of it interfering with the loaded game. This means that whatever is stored gets wiped away, and everything begins anew. Its often easier to be over zealous than to try to be hyper efficient. In my case loading takes less than 10ish seconds anyway. Sorry temporary universe inhabitants - but my players want less crashes.",
"Some games optimize levels by only loading things close to you. Skyrim, for example, would be impossible to run if it had everything loaded at the same time. So if you die away from the spawn point, the game has to unload everything close to you and reload the spawn area back in before plopping you into the game again. That is only one of the reasons, along with resetting variables, respawning dead enemies and all many other game dependant things. Since most of these can contain reading from files (e.g. saves), it can be considerably longer than expected since file I/O is really slow compared to RAM."
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5w1xog | Why do tv networks have to be on differently #d channels based on your location? | Feels like every city/state has ESPN on a different channel. What's the deal? | Technology | explainlikeimfive | {
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"Originally, television was actually broadcast through the air on radio frequencies. Different channels were assigned to stations in different cities to reduce interference in places that could receive signals from more than one city. So Washington had stations on 4, 5, 7, and 9; Baltimore on channels 2, 11, and 13. If you're asking about cable, it's mainly just that there's no standardization, so the local cable company puts it where they want it. In short, each cable operator places services wherever they find it convenient. Generally, the calculation is no more complex than \"we're adding another cooking channel. What's the first vacant number? Well, is there one closer to the other cooking channels?\""
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5w2355 | How does Microsoft mass produce Windows os cds? With no blank copies? | also this could be any company that sells software on any type storage device. | Technology | explainlikeimfive | {
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"The advantage of CD's is that you can manufacture them with the data already on it without having to produce it then write the data, since CD's work with pits for data you can simply stamp the CD with the data which essentially stores all the information onto the cd in one swift action"
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5w27f1 | Why does the content I actually want to watch constantly buffer but the ads play perfectly? | Technology | explainlikeimfive | {
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"I'm not an expert, but I always figured that the video ads where essentially queued up, like ready to go regardless of what video you chose the and was prepared to play before you clicked it",
"One of them usually makes the company money, so they'll invest QoS dollars to make sure it plays and thus not break contract with advertisers. The other is just content."
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5w2g85 | How does Planet Earth get all these insane angles and right next to animals without disturbing their natural choices? | Technology | explainlikeimfive | {
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"I make wildlife documentaries. This is an answer that I cut and pasted from a previous thread. I can't really say too much about long lens stuff cos I specialise on invertebrates. But for them what you do is use a mixture of sets and wild shot footage. You have certain things that you can't film in a studio and other things that you can't film in the wild. This is an example of the [former]( URL_0 ) And this the [latter]( URL_1 ) Say you want footage of the inside of a nest. You won't be able to get this in the wild without disturbing the animal. So you need to construct a specially made tank that will allow them to be calm relaxed and go about with their normal behaviour, but also allow you to light it and get good camera angles. The footage of the wasp in the tunnel in this [film illustrates]( URL_2 ) this. What I did was cut a sample tube in half, fill it with sand so it looked natural. Then stuck it to the side of an opti-White glass tank. Kept it in the dark till the wasp got used to using it, then once it had I just filmed away. Another big thing is editing. You can use careful editing to make it look like the animal is seeing something that is not actually there. For example; the scene of the harvest mouse in Planet earth two, when it is being hunted by a barn owl. The mouse was almost certainly shot in a set and the owl in the wild. The two bits of footage were edited together to make it seem like the owl was hunting the mouse. When in reality they were probably shot days if not weeks apart. Edit: I thought I would include a link to [this video]( URL_3 ) which has a sort of making of bit at the end.",
"They have cameras that can zoom several hundred feet without distorting the image. And sometimes they are literally right next to them and the animals don't care",
"If you got DVD at the end of each episode they show how they filmed some parts. It includes, helicopter(drones later) shots, hidden cameras, motion activated cameras(for snow leopards), people hiding for few days in small spaces filming through hole.",
"A couple of the shots are done in a studio mock up. If I remember correctly the scene in which the polar bear is giving birth to cubs. I'm sure there are a few more, but most of it is just waiting around for the shot considering planet earth 1 and 2 took roughly 10yrs to film each. Edit: Some examples, Not Planet Earth specifically but BBC/David Attenborough documentaries. * Tragopans - a kind of pheasant purportedly living in a Chinese forest - actually filmed in a wildlife park in Somerset for the series Wild China * clown fish shown hatching from eggs in David Attenborough’s Life series in 2009, in the ocean were in fact filmed in a tank built by Swansea University as part of a research project * a chameleon in Attenborough’s Life in Cold Blood in 2008 shown in the forest actually filmed in a studio as were leopard geckos shown mating in the desert * a stalk eyed fly, described as lying “dormant on the forest floor” in Life in 2009, was filmed not in a south east Asian rainforest but in a BBC studio Source: URL_0",
"There is an example I know of where in order to get close enough to tigers and film them hunting without disturbing their behaviour they attached a camera to the top of an elephant and rode it around filming that way. The tigers don't care about the presence of the elephants and adding a human/camera on top didn't seem to change this!",
"A lot of it is to the credit of former Alf actor Michu Meszaros' talent. He's a very small statured individual who wears these extremely realistic animal costumes and he replicates their behaviors for educational purposes. Even the larger creatures he portrays are just modeled to scale. The perspective of the camara and artificial backgrounds also contribute to the appearance of him mimicking larger or smaller creatures. It's incredible how a single man can accomplish this. If you are fortunate enough to come across the DVD with extra scenes, there's a behind the scenes portion that focuses on Michu and his performances. It's very interesting.",
"Some shots are recreated in a studio like ones inside an anthill fir example. Super awesome zoom lenses. Cameras hidden in places. Sometimes the camera guy just hangs out near then animals until they used to him/her and just ignore them.",
"In addition to zooms and telephoto lenses, the use of small unobtrusive cameras that can be planted/hidden ahead of time (like goPros) and triggered remotely. There is a great deal of planning involved too. The crew doesn't just turn up and shoot."
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5w2gz9 | Why do we still plug a big block into the wall to charge our phones, instead of something more flush with the USB port, since nothing has the grounding peg anymore? | Technology | explainlikeimfive | {
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"The power going into your phone via usb is DC format. The power from the wall is AC format. It needs to be transformed to go into your phone. That big plug is a transformer. It never had anything to do with the need for a grounding plug. Despite it being 2017 those still take up space to function and the basic rules of electrical currents still apply.",
"I don't think I've ever had a phone charger with three prongs, assuming that's what you're referring to. Also, you can buy a charger for any phone made in the last five years to plug into USB, mostly because USB is (by name) universal, and connecting to computers has become an increasing advantage for smartphones recently.",
"That block is a step-down transformer. It takes the 120 (or 220 if you live in Europe) volt wall power - far to much energy for your tiny phone - and steps it down to about 5v for your battery to charge on. It also contains a converter to change the Alternating Current in the wall (electricity is pulled back and forth- good for transmission) to Direct Current (electricity moves in a loop - like a battery) IMO the fact that the block is so small to begin with is already pretty impressive. TL;DR that block does a thing"
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5w2xcq | What is the Deep Web? | Technology | explainlikeimfive | {
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"First you need to understand how the \"regular\" Internet works. Search engines like Google use scripts called crawlers (a type of \"bot\") that visit every site they can and gather information. The information is then processed by various algorithms and indexed. The thing that made Google explode and become one of the largest tech companies in the world was that their algorithm didn't just show you the pages containing the words you used in the query, but also sorted the sites by relevance (so you're more likely to get the results you need). The deep web is sites made in such a way that crawlers either can't visit them or gather useful information. E.g. dynamically generated based on user input, password protected etc. So you can't just find the site using \"regular\" search engines, you need to use engines specific for deep web, specific Internet protocols or someway else obtain instructions on how to access the site. A common myth is that \"deep web\" means sites with illegal material, drug marketplaces, human trafficking sites, hitmen sites etc. The term for that is actually \"*dark* web\", a subset of *deep* web.",
"internet locations that aren't accessed or indexed by search engines like google. it's like an elite nightclub: you only can find it if you already know where to go, you won't ever \"stumble\" upon it.",
"I'll explain with an example. The UK government has a website for looking up car details. You type in the car's registration number (the one on the license plate/number plate) and its make, click search, and then you get a results page saying if the car tax is paid, what size the engine is, and so on. This is the page: URL_0 Now the homepage of the website is part of the 'surface web'. It's just a normal web page and general search engines like Google can find and 'index' it. But the results you can get through that page are the details of millions of vehicles in the UK. Those are part of the 'deep web', and you can see that on this website the deep web part is far *far* bigger than the surface web part. The homepage is easy enough for a person to understand but it doesn't contain instructions that Google's search engine can follow to index the results pages. Even if it did, the search engine would already need to know what make of car corresponds to each registration number in order to find the results. So that's millions of web pages, detailing millions of vehicles in the UK, that are all potentially accessible by a person but all invisible to Bing, Google, Yahoo, and so on. Deep web."
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5w3w33 | Are Data Science and Information Systems the same? | Technology | explainlikeimfive | {
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"From your title, I was going to post an immediate \"NO\" to your question. However you also mention that the syllabus for the 2 programs are basically the same. This confuses me greatly and makes me think that someone who doesn't know the field named the programs. Obviously, the course of study is what I would look at over the name, but if those are the types of things I wanted to study, I would absolutely prefer it to be named \"Data Science\". Here is my take on the meanings of each: Data Science: That's high level analytics and making sense (including predictive) of data and information that you have or gather. The courses listed certainly fit within that category. URL_0 Information Systems: That's the running of the servers and applications needed to keep the company running from a technology or computer perspective. So setting up servers and making sure each user has Office installed appropriately and connected to the network to share information. URL_1"
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5w4obw | Why does sending a picture via Messenger lower its quality so drastically? | Technology | explainlikeimfive | {
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"Here is my 2 cents: Because it gets compressed to save space and bandwidth. Same thing happens to YouTube videos. As a general rule, any file you upload or send online gets compressed depending on the server, some are better than others at this. In the YouTube video example, the difference in quality is not that noticeable because the compression algorithm used is good unlike Messenger which I would assume favors file size & bandwidth a little bit more than it should, and as a result you get crappy quality. & nbsp; EDIT: to clarify, this is done by the server and not locally on your device. When you upload the file, the server analyzes, compresses and then forwards it to your friend, so in short **the image you send is NOT the same image that you see in Messenger and it's NOT the same image that your friend receives.** Some websites and apps offer you the option of downloading the original image file, but it's not that common.",
"Messenger apps have built in compression designed to save you data because most cell phone services have some kind of data limit or cap. So when you send a picture, by default, they will compress the picture into a lower quality format that they've deemed an appropriate compromise between file size and picture quality. Many messenger apps will also give you the option to send an uncompressed version of the file although the method varies from app to app."
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5w6kfl | How do console video games improve the quality of graphics during the same generation? | For instance, how can can a game like Gears of War 2 look better than Gears of War while working with the same hardware? | Technology | explainlikeimfive | {
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"Basically, they get more experience at writing code for that hardware and learn how to optimize it. It's like getting more practice with a set of paints. You don't get more colors to work with, but you learn how better to use the ones you do have."
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5w7rog | Why is it when you download something it slows down dramatically at 99% or just simply takes a longer time compared to other percents? It's annoying. | Technology | explainlikeimfive | {
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"With bittorrent, the last percent takes a long time because there's only a couple or just one block left, and it's coming over a slow connection. You can only get a block from one peer at a time, and you were likely getting it from someone with a slow connection or it wouldn't be the last one. When you're downloading through a web browser, it's likely because your browser downloads to a temporary file location, and once it has the whole file, it has to copy it to the final directory."
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5w85dr | Why do glasses need UV protection when people who don't need glasses are fine without it? | Technology | explainlikeimfive | {
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"The same reason why you wear sunscreen. UV causes irreversible damage to your eyes and if you wear glasses anyway why not protect your eyes from UV if you can do so without adversely affecting the performance of the glasses?",
"You'll go blind without UV protection in sun glasses. Your eyes think it's darker so they open up to allow in more light so you can see properly. If the glasses aren't also blocking UV light then you'll have more UV light entering your eyes than you would without glasses. This will quickly damage your retina.",
"People who don't need glasses are not fine without UV protection. If you spend a lot of time outdoors without protecting your eyes, you will have a higher likelihood of developing cataracts in later life.",
"Glass need extra UV protection because the theory of glass is to foucs the light at the back wall of the eye (where the photo receptors are), if the sunlight passes through a lens without UV protection and there will be a high intensity of UV rays which would be harmful for the eye. Furthermore, the normal eye(without glasses) also protects from UV rays, but as the lenses of the glasses concentrate the intensity of light falling on the eye. It harms the eye all in all"
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5w9lb8 | What is an IP address and what role does it play in tracing online activities back to you? | Technology | explainlikeimfive | {
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"I assign ips, both public and private for a hosting company. Im also responsible for switch configuration and firewall provisioning. Postal service is the best analogy here. Your house address is how people send letters to you. Each up address can be broken down into street and house number but for this example let's just says it's your whole address. Routers/firewalls are like post offices, they may not have anyone there who knows where 12345 easy lane is, but it knows where the post office in Simple, TX is, so it sends it there. In the mean time while it passes through some of these routers/firewalls the traffic gets monitored and logged. Apartments are more like dynamic ips, it's a temporary address assigned to a large group of dwellings. This is most of us who have home internet connections. The apt complex knows who has what address, and when questioned they know who had apt 987 in June of 2008. This is why TOR network was created, and this is also the importance of VPNs.",
"Say you want to send a request to a web server, you put the website name into your browser, say URL_0 , and the browser ascends the request to the web server, except how does it get there? Computers and routers don't send data to host names, they need something that's easier for computers to understand. Every computer and router connected to the internet has a numeric address, the IP address. There's a process that converts names like URL_1 to addresses and your computer does that and sends the request to the address. Now, to get the response back your computer needs to have an address. I'm going to gloss over some details you can google if you're interested (rfc1918, nat, dhcp) but your computer gets an IP address from your ISP automatically and when you send a request to a server that request includes your address so the server knows where to send the reply. Now, your address uniquely identifies your computer on the internet, so if someone does something on the internet the server they talked to has a record of what IP address made the request. From that people know which ISP issues that address to a user and then they can ask the ISP which customer had that address.",
"An IP address is actually an address. It's a number that uniquely identifies anything that connects directly to the internet. As for tracing online activities - it becomes a little bit more hairy. Say you are at campus and connect through the same router as all the other students. Then the router is the only thing with a global IP address. Everyone else connecting through that router will identify as the same IP (it's called NAT if you want to read further) Your home connection may or may not be a fixed IP. There is a limited number of IP addresses so most ISP's use dynamic IP's. This means that your IP of today may be your neighbors tomorrow.",
"Have you ever been in a group with two people that have the same first name? Someone might say \"Hey John\" or whatever name, and both look up and wonder if you mean them or the other John. Usually this problem is solved by adding more information that only applies to one of them, like their last name, or simply calling them by their last name to begin with. Computers have this problem when they try to talk to each other too, especially now that we've connected thousands of them together on the Internet. This problem is solved by giving each computer that connects to the Internet a number that only they have, an IP address. Since the Internet got way bigger than anyone had thought of back when they chose the numbers used for IP addresses, they divided them into public and private IP addresses. The private ones can't connect to the Internet, so they don't need to be unique. Each home or business has at least one router, which is a special type of computer with both a private IP address and a public IP address, the latter being assigned to it by their Internet service provider, like Comcast or CenturyLink. Computers and game consoles and tablets and stuff use their private IP addresses to talk to the router on its private IP address, which then uses its public IP address to talk to other computers on the Internet. So people on the Internet can sometimes see the public IP address and can look up what Internet service provider it is from, and find the city and state it's in. Unless the customer posts it somewhere, only your Internet service provider knows the actual address of the house or business behind an IP address. A government or a hacker may be able to get that information from the Internet service provider, but is usually very difficult and rarely happens."
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5wan4h | Why does RCS need carrier support? | If RCS transmits over WiFi or cellular data, why is Google pushing so hard for carrier support, and why is it currently only available on carriers that support it? | Technology | explainlikeimfive | {
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"Because it's goes thru the carrier's network. iMessage uses Apple's servers, so the carrier is not involved. Android is a total mess in terms of everyone having the same experience, most people are not on the latest operating system and updates are depended t on your phone and carrier. By making it implemented on the carrier level, the operating system version users are on doesn't matter much. For instance, iOS 10 introduced a lot of iMessage additions, but the added features aren't appreciated on devices that aren't on iOS 10 and also those that don't have 3D Touch/the new vibration motor."
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5wb8pw | How does vector and matrix operations differs in CPU vs GPU? | Technology | explainlikeimfive | {
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"Most modern CPUs have vector units, so they do not differ from GPUs in any meaningful way. Intel's x86 family of microprocessors initially supported IEEE scalar floating point arithmetic with the x87 family of coprocessors. This architecture was integrated into the CPU starting with the 80486, providing a separate register stack of 8x64-bit (80-bit internal) registers usable only by the FPU. In 1997, Intel introduced the MMX instruction set. The MMX instruction set used the same register stack as the x87 FPU, but used the register stack for vector integer and vector logical operations. The base x86 instruction set supports only scalar integer and scalar vector operations on the CPU's general purpose registers. In 1999, Intel introduced the Streaming SIMD Extensions (SSE) instruction set. The SSE instruction set extended the register stack used by x87 and SSE to 128 bits and added even more vector integer and vector logical operations. In 2001, Intel introduced the SSE2 instruction set. SSE2 is intended to fully replace MMX and x87 (although x87 computes to a higher precision as it uses 80-bits rather than only 64). When AMD introduced the x86_64 microarchitecture, SSE2 was adopted as a standard component. Furthermore, the number of registers in the SSE stack was doubled from 8x 128-bit registers to 16x 128-bit registers. Subsequent instruction set extensions including SSE3, SSSE3, and SSE4.x were introduced over the years. In 2011, Intel introduced the Advanced Vector Extensions (AVX) instruction set which greatly simplified vector instructions for reasons that aren't germane to this post. This instruction set expanded the vector registers from 128 bits to 256 bits. AVX extended vector integer and vector logical instructions to 256 bits. In 2013, Intel introduced the AVX2 instruction set which extends floating point instructions to 256 bits. A 512 bit version of AVX2 is available on Intel's Xeon Phi coprocessor. Intel's architecture uses the same hardware to execute scalar and vector floating point operations. That is, scalar floating point operations are performed on the vector FPU hardware. This is not true for scalar integer and scalar logical operations; there are multiple scalar integer ALUs per core in addition to vector integer ALUs and vector logical ALUs. The vector portion of Intel's CPUs is remarkably similar to that found in a GPU, with a few key differences. 1. The instructions driving the CPU's vector extensions are all proper x86 instructions and are executed on the CPU. No special setup, driver, or runtime is needed for a program to invoke them. However, the operating system does need to be aware of the instruction set to ensure that it will save the registers during context switches. 2. Memory is loaded into the vector registers in the same way that it is loaded into the general purpose registers; same for storing. 3. The CPU's vector extensions run at the CPU's clock speed and are a part of the CPU's pipeline. From an efficiency perspective, there is virtually no overhead involved in setting up vector arithmetic on Intel's CPUs. There is however overhead involved in setting up vector arithmetic on any GPU. However, GPUs have a massive number of vector units and for particularly large and parallelizable working sets the overhead will quickly be overcome by the sheer amount of throughput. For any non-parallelizable working set, the CPU will usually be the best option. For a small parallelizable working set, the CPU will usually be the best option. For a large parallelizable working set, the GPU will usually be the best option."
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5wbata | How did people make the "bootleg" NES/SNES/MD games back in the 90s? Like "Sonic" for the NES, or "Kart Fighter"? | Back in the 90s (and 80s too, probably) there were bootleg games for consoles like the NES/SNES/Megadrive(Genesis). Stuff like this: URL_0 That's a Game Grumps play of Kart Fighter, a bootleg for the NES. Some of these games are more recent, i.e. people made them post-2000 and they mainly existed to be played on emulators. I know a fair bit about how videogames are made, so those make a bit more sense to me. However, some of them existed back when those consoles were the latest thing (I remember playing them) - **but how did people make them, with the limited tools and knowledge available?** | Technology | explainlikeimfive | {
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"Unless development documentation had leaked to the public, pirates would have to reverse engineer their target platform. This process usually involved looking at how the game system behaved given an existing program (a legitimate game) but also could include decapsulating chips and looking at them with an electron microscope to figure out how the internal circuitry worked. After this, pirates could create their own toolkits for writing games. The lack of official documentation combined with the difficulty in completely reverse-engineering a game console is why many pirated games are rather unstable and crash-prone. Some pirate game manufacturers even went as far as to design their own expansion chips for the NES (check out iNES mapper 90 if you're interested)."
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5wbgh1 | Why do nightlights have a motion sensor as well? Is there a point to these? | Just something I realized whilst turning on my light in the bathroom today and the switch is next to a plug in night light. | Technology | explainlikeimfive | {
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"Sure it's a motion sensor, and not a light sensor? I know many nightlights have light sensors so they switch on in the absence of other light."
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5wbyl5 | If programs/software is created in such a way that it's not possible for them to be hacked , how do they actually end up being hacked? | Technology | explainlikeimfive | {
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"It is not possible to make something that cannot be hacked. Just like everything else, if humans can build it then humans can unbuild it.",
"It's very, very difficult to be sure that a program is completely secure, unless it's a very simple one. If we take a very simple model of programming, it's basically that you have an input, you process it and do something or output something as a result. Of course there are many, many different possible inputs and you can't write separate code for every single possibility, so what you do is you make assumptions about the structure of your input and write code based on these assumptions. For anything reasonably complex, there are easily dozens of these assumptions in each module, and there can easily be hundreds or thousands of modules. \"Hacking\" basically works by finding assumptions in the code that are actually false, and then providing inputs that violate the assumptions, and getting the program into a state that the developer did not expect to be possible. Some of these states then allow you to do things that the program normally stops from happening. Hardening your code against attacks means you have to second-guess your assumptions and build in checks to catch out all the ways you can think of to break your assumptions. Since you're not always aware of all of the things you're assuming, nor of all of the consequences of those assumptions, it's almost unavoidable that a dedicated attacker will still be able to find something, maybe by combining two or three seemingly unimportant assumptions and creatively mangling the input(s) so that the effects build up. As the various components of your program get more, and the interactions between become more complicated, it's basically impossible to be fully aware of all of the details. Perhaps some of the components from third parties that you are using have weaknesses in them that you don't know about... then chances are your program can be compromised, too. It's a lot of work to stay on top of all of that! Creating software that minimizes the possibility of attacks takes a lot of discipline and experience, and even then there are no guarantees."
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5wc5p0 | When will driverless cars be widely available? What is the status of their technological development and legal roadblocks? | Technology | explainlikeimfive | {
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"They are currently in the middle of safety testing in several States. They will likely be street legal within 5, but will require driver's licenses still. It will probably be 10-20 years for it to allow people without licenses to ride in one solo."
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5wc9n4 | How are 3D movies filmed? | Technology | explainlikeimfive | {
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"Most of the time, they have a special camera with two lenses that it records simultaneously (one for the left eye, one for the right). Some films that wanted to add 3D as a gimmick were shot in 2D and then modified in post-production to add 3Ds (where artists modified the original shot to create a left and right eye version)."
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5wd990 | If a civilization relied on the sun to tell time, what did they do on a very cloudy day? | Technology | explainlikeimfive | {
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"Until the modern age(locomotive trains, and telegraphs), knowing precisely what time it was, was not very important. Only when communication and travel between groups of people in different places became the norm, did accurate timekeeping matter.",
"There are on simple clock namely the [Water clock]( URL_0 ) that have been used since ancient time. You have to set it with sundial. It can also easy be used in conjugation with a sundial because it can be use at night",
"In almost every case: they went about their business without knowing or caring exactly what time it is. Specific time of day was not important information in most older civilizations.",
"Until modernity telling time was not really necessary. You dealt in generalities. Dawn, mid morning, noon, afternoon, dusk, midnight. That is about it.",
"When the sun was obscured, and the sky was cloudy or hazy enough that the sun could not be directly observed they could still see dawn and sunset. The rest was educated guesses and use of other items like hourglasses. Basically the clearer the sky, the more accurate they could tell time at that moment but even so it was in more general \"noon, after noon, early evening, sunset, evening\" sort of way. Rather than by the hour. A sundial can provide time to the minute if it is large enough, but cultures at that time did not hustle and bustle enough to break the day up into minute by minute planning. Some activities did require a more granular (smaller spaced measurement) way to measure time and so they quite literally used grains. The smaller the grains of hourglass sand or more granular it was, the more accurately it could measure time. Very fine sand could measure seconds. Coarse sand in an hourglass could measure minutes and hours. So you might time when to start work for the day, by sunrise, when to take a break when the sun reached it's zenith at noon, and quitting time, when the sun began to set. But if you needed to bake bread, or time something with some accuracy, you'd break out the hour glass, water clock, or any of the other time keeping devices of antiquity."
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5wdnci | What is IBM Watson? | I've seen it involved in a whole bunch of stuff, and I think it's some attempt at AI, but I don't know more than that. What's the big deal? | Technology | explainlikeimfive | {
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"It is a brand name that IBM is applying to a large number of artificial intelligence, machine learning, and pattern recognition technologies -- including the software, hardware, and services involved in doing so. Originally, it was announced as the machine that could be humans an Jeopardy, but it's really a big collection of technologies.",
"Watson is an AI designed by IBM to play Jeopardy!. Jeopardy is a notoriously difficult game for AIs, because Jeopordy! poses the challenges as answers, from which one must derive the question. Watson was really good at it and won. Watson is still important because extrapolating questions from answers is not an easy task, but it is applicable for a lot of different fields. For instance, Watson has been used for medical diagnoses due to its ability at linking queries and answers."
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5wdopl | How do the heart rate monitors that clip on to your finger also find oxygen levels? | Technology | explainlikeimfive | {
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"One side of the clip has a light and the other has a sensor. When you clip it on your finger, it shines both red visible light and infrared light through you finger and it hits the detector. oxygenated blood and deoxygenated blood absorb different amounts of infrared and visible light, so by comparing the amounts that the sensor detects to the amount that was emitted, it can tell how much of your blood is oxygenated and how much isn't.",
"Everyone's explanation pretty much covers how these work except that these devices CANNOT actually tell how much oxygen specifically is bound. As in, they cannot differentiate whether carbon monoxide is bound to your hemoglobin or if oxygen is bound.",
"Hi, I am an anaesthetist. I am very happy to see a question I am qualified to answer. The principles behind pulse oximetry are some of the required knowledge for basic anaesthetic trainees. As has been outlined, the pulse oximeter uses two wavelengths of light: 660nm (red light) and 940nm (infrared light). These lights correspond to the maximum absorption by deoxygenated haemoglobin and oxygenated haemoglobin respectively. This light shines through a finger, toe, lip, ear (and sometimes hands and feet for neonates) and is picked up by a detector on the contralateral side of the probe. The ratio between the two wavelengths that is transmitted gives an R value (Red/Infared) which corresponds to an oxygen saturation. An R value of 1 is equal to roughly 80% SpO2. Oxygenated blood absorbs more infrared light and deoxygenated blood absorbs more red light. I hope that explanation helps a bit. [Here]( URL_0 ) and [Here]( URL_1 ) are a couple of articles that explains the science and limitations of oximetry in more detail. Thanks for letting me answer. Edit: fixed a link",
"The instrument that reads the oxygen levels of your blood (referred to as SpO2) is called a pulse oximeter. It shines different wavelengths of light (usually IR and red) through your finger to find how oxygenated your blood is. How does it do this? Hemaglobin, which is the protein in your red blood cells that binds oxygen and takes it to your cells, can absorb light (like most materials). How much light it can absorb depends on the wavelength of light shining on it and whether the hemaglobin is holding oxygen or not. A sensor on the other side of your finger (a fancy lil thing called a photodiode) will detect how much light makes it through your finger. Plug these absorption values into an equation and you can figure out how much of your hemaglobin has oxygen in it. Hopefully if you're healthy it will be between 95-100%, although 100% SpO2 is not that common.",
"Respiratory Therapist here The pulse oximeter has an infrared sensor attached that can pick up how saturated your oxy-hemeglobin is. So if you are anemic and satting low you may be oxygenating fine but you may be hypoxic by medical definition because your blood can't carry as much O2. My teacher told me think of blood as trucks and your hemeglobin as it's tailgate. With that being said a normal number is 92-100, less than 89 call 911, or under medical prescription apply oxygen. This also explains why carbon monoxide poisoning your O2 levels appear normal, the carbon monoxide binds to hemoglobin easier effectively \"knocking\" the o2 molecules off and kicking them out.",
"Biomedical engineer. Everyone correctly describes that light of 2 specific wavelengths is shone through the finger. The amount of light absorbed by deoxy and oxygenated blood is different. The relationship between the amount of absorbance is measured and this provides the oxygen saturation levels. However, the amount of light absorbance isn't directly related to the O2 level. Instead, there have been data tables created that relate the O2 levels to the light absorbance... this was done EMPIRICALLY, i.e. by experiment, and not by theory. So the device is just correlating the light information to pre-programmed data table relationships. The relationship breaks down somewhere around 80% and below, and thus the pulse oximeter can no longer properly measure oxygen levels below this percentage. Regardless, the device would have started beeping an alert by then anyway. This is as I recall, please add any detAils if I missed any...",
"They work on the principle of spectrophotometry. Hemoglobin is the protein that carries oxygen through your blood and hemoglobin is a different color when it's bound to O2. The sensor simply emits light at a certain wavelength and the amount that passes through is dependent on how much hemoglobin bound to oxygen is in your blood. The colors they emit are red (absorbed by deoxygenated blood) and infrared (absorbed by oxygenated blood). The machine then does a calculation to result in a percentage.",
"A question I can easily answer! It is very simple, all objects, including your body, absorb light. The way that we can measure hemoglobin saturation levels is by simply literally shining light on tissue and then seeing how much gets reflected. After this we just measure the ratio of one color to the other one and we get your oxygen levels! :D TL;DR We shine light, light strikes tissue and some of it comes back. We measure the ratio of light wavelengths that come back. EDIT: Something cool that I think is worth mentioning is that literally any camera can be used to do this! You do not need a highly specialized medical equipment to find out oxygen levels. Any device with a camera can be utilized. That is why you get nowadays apps within cellphones that offer to measure stuff like this. Those cellphones either include an additional sensor/light apparatus to specifically do this, or they simply use your cellphone camera to do it.",
"Some people have described a device that has an emitter on one side of the finger and a phototransistor on the opposite side. This is valid, but it need not be the case. Upping the LED power we can place all the components on the same side, as sport watches do to monitor heart rate. Also, the wavelengths used can be pretty common. Red and green light offer a good enough contrast. Plethysmography is easy enough; the heart rate is easily found. But oximetry is tricky, as another user pointed out. As is known, hemoglobin has a different saturation of color if the iron atom is bonded to two oxygens or three (that's how oxygen transport happens). Pulsing rapidly at different times the red and green LEDs we measure different amounts of reflected light on the phototransistor. We don't need the full spectrum, just two well selected slivers. We work out the oxygen, as it was pointed out, from am empirically built table. On the x axis we plug the ratio of green vs red reflection, and on the vertical we read the O2 saturation. The problem is, the result does not correlate very well at first to the real value obtained by puncturing the finger and actually measuring the blood. The reason for the discrepancy, in my experience, was not related to the table itself, but to problems with the DC part of the measurement. This means: the base level of light received varies greatly from person to person and also depends on how snug is the sensor to the skin. Funnily enough, skin color itself was not relevant, but people seem to have a great range of different vascularization degrees from one spot to the next and from one person to the next. So the biggest challenge was removing the base level both before the ADC and later by software using adaptive moving averages. Source: I have designed and sent to the market such a medical device. Also: Yes, I talk to my 5 year old like this. I withhold no information from her. The conversations just get longer, and we both enjoy it on several levels."
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5we0uy | Why do companies continue to build brick and mortar facilities rather than create virtual offices? | Technology | explainlikeimfive | {
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"Workplace psychology is complex, but it's generally accepted that social interaction in the workplace is vital, especially *in person* interaction. There are neurological processes at work when engaging in things like eye contact that simply don't happen when trying to communicate over IM or email. There are of course practical benefits as well. Getting everyone working together is much, much easier when everyone is present in person. I honestly don't mind meetings, even large ones, but even small conference calls drive me fucking crazy and I ignore convoluted email chains unless they're addressed specifically to me. Every project that I've worked on, and every project manager that I've talked to is in agreement that managing remote teams is extremely challenging. Sometimes a manager needs everyone's undivided attention for 5-10 minutes in order to address a new development; this cannot be effectively done when everyone is working from home just doing their own things. Keeping tabs on employees to prevent shirking is easier as well. In some cases, an office is essential to protecting trade secrets and intellectual property. That's not to say that common offices are perfect. There is a near infinite supply of office grievances including loud coworkers, background noise, distractions, long commutes, and general dullness. Working remotely is a solution to many of these problems, but it is not the only solution. There's a whole field of study regarding creating healthy workplace environments that often gets overlooked."
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5wgblj | How does a rice cooker know that the rice inside it is cooked? | Usually, i cook long grained white rice in our rice cooker and it takes about 10 minutes to cook. But recently, we switched to brown rice and its cooking time is longer, i think like 25 minutes. edit: thank you for all the answers guys! | Technology | explainlikeimfive | {
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"Once the rice cooker's thermal sensor detects the pot going above 212 degrees, the water has all been absorbed. At that point, the rice is done. To prevent the rice from cooking any further, the sensor automatically trips the shut-off switch for the heating mechanism.",
"It isn't timer based. The temperature can't rise above the boiling point as long as there is liquid water present. Once all the water gets absorbed by the rice, the temperature quickly rises and the cooker turns off.",
"/u/unicoitn was correct, but I figured I'd elaborate some. Rice cookers change to keep warm once a certain temperature is reached. That temperature can ONLY be reached once the water has boiled away. So adding more water keeps the rice cooker on for longer.",
"I have owned a number of rice cookers over the years, and in my opinion, based on direct observation, there is a thermostat in the rice cooker that shuts off at a predetermined temp. The cooking time is dependent on how much WATER to rice ratio you start with. Brown rice needs more water and has a longer cooking time."
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5wgpqk | The argument against net neutrality. | Technology | explainlikeimfive | {
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"It boils down to: Private companies are allowed to serve the customers however they want, even if the service is horrible, and furthermore, internet isn't a necessity for life. The government shouldn't dictate how the company supplies the product to their customers, as the company would best know how to make their product. If a private company does badly by the customers, then the customers can just switch to another supplier on the free market. Counters that there is no \"free market\" in terms of ISPs due to monopolies and the need for vast infrastructure is met with the ideological counter argument that that is caused by flawed corporatism instead of the free market and two wrongs don't make a right. Disclaimer: I am not presenting these arguments as my own, I am answering the question.",
"I have no problem with net neutrality *in theory* but think there are some very, very concerning things about *specifically* how it was done by the FCC in the USA. The FCC pushed net neutrality by subjecting ISPs to the same 1934 Telecommunications Act restrictions that phone companies must abide by. Not only does the 1934 Act regulate how phone companies are to provide service, it also regulates how *consumers use that service.* If you read the 1934 Act, you will notice some language in [Section 223]( URL_0 ) (a) Prohibited acts generally: Whoever— (1) in interstate or foreign communications— (A) by means of a telecommunications device knowingly— (i) makes, creates, or solicits, and (ii) initiates the transmission of, any comment, request, suggestion, proposal, image, or other communication which is obscene or child pornography, with intent to abuse, threaten, or harass another person; (2) knowingly permits any telecommunications facility under his control to be used for any activity prohibited by paragraph (1) with the intent that it be used for such activity, Shall be fined under title 18 or imprisoned not more than two years, or both. I am not a lawyer, but let's just take a moment to think about how regulation that prohibits \"harassment\" or \"abuse\" or \"obscene communications\" from being disseminated on the internet would affect freedom of speech. That language - it doesn't feel right. It's off. Seems to me like a good way for the FCC to harshly or selectively regulate speech on the internet - opens the door to censorship. Will it be used that way? Maybe not. But I'd rather not go to jail for 2 years for saying something \"obscene\" to someone on the internet.",
"Another argument is that it could allow the government to institute regulations on internet content. On the weak side, there is the potential for limitations similar to those on broadcast television, like restricting usage of certain language. On the strong side, the government could *maybe* use this power to censor political opposition.",
"I'll start out by saying that I am completely for net neutrality for a whole list of reasons...however you said \"the argument against net neutrality\" - so I'll try to give a devil's advocate answer. 90% of residential network traffic is between 4-10 pm; and something like 90% of the data is now video streaming. Why should companies have to expand their infrastructure to handle a concentrated high traffic period when the rest of the time their networks are not operating at capacity? The argument is that they SHOULD be able to charge high data users more because they are hogging capacity. The only reason that is a valid argument is because there is no competition for highspeed internet in most locations in the country, A truly free market would let ISP's charge whatever they want and if they charged too much, they would lose customers. We don't have that. There are many other reasons to support net neutrality that the big companies try to shy away from, the next biggest is the steering of the public towards certain media consumption. An example that shows how insidious yet how buried this can be: TimeWarner owns 10% of Hulu. If there is a show that I want to watch (I'll use Vikings as an example cause I'm watching it now) I can watch it on Hulu or Amazon Prime. If I have TimeWarner as my cable/internet provider; they will benefit financially if they get me to chose Hulu over AmPrime because of a Hulu subscription, and Hulu has ads, AmPrime does not. To steer this they throttle my connection to AmPrime, and streamline my connection to Hulu. This also carries over to news media outlets; if an ISP wants to push a political agenda, they would throttle the ones they disagree with and streamline/redirect ones that push the narrative they want. This quickly translates to freedom of speech issues."
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5whct1 | What's the difference between an sd card (or thumb drive) and a solid state drive? | Technology | explainlikeimfive | {
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"Read and write speeds. A standard 128gb SD card will write at around 10mb/sec. An unimpressive 128gb SSD will write at at least 150-175+mb/sec. While the amount of storage might be the same, the speed at which it needs to be written and retrieved differs greatly."
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5winxt | Why do websites start with www? | I tried to do some research on my own but couldn't find much info out there. Is there any reason as to why websites start with www is it something to do with the coding? | Technology | explainlikeimfive | {
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"Domain names conventionally follow a reverse hierarchical system. The last portion (top-level domain, or TLD) is a signifier of purpose or nationality of the site (.uk, .fr., .jp; or .com, .org, .biz, .gov). The next to last portion is the owner of the site, or the name they've chosen for the site. The next portion is called a subdomain. Often this is used to indicate a purpose within the overall website for that particular page. www. means it's part of the World Wide Web; it's intended to link to and be linked to by other websites, and to be read by a browser. ftp. means that it's for file transfer. smtp., pop., and imap. are used for email applications. A website might also use the domains to indicate which server is hosting a given website. Some administrators have used this for artistic or humorous effect: URL_0 URL_1"
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5wkuv0 | How do Landline phones work when the power is out? | Technology | explainlikeimfive | {
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"A standard landline (POTS) has -48V DC power included with the signal. The phone company central office also has a bank of batteries to operate when the power is out.",
"The Central Office for the phone system supplies power down the lines for the phones. It's DC (direct current, like a battery) and the voltage varies based on what the phone is doing. When the phone is on the hook, the circuit that goes between the Central Office (Henceforth the \"CO\") and your phone is open - no current flows. One wire of the pair going into your phone is always connected to the CO, the other wire is connected when you pick up the phone. (While I'm thinking about it, the wires are called the \"Tip\" and the \"Ring\") When you pick up the phone, and get a dial tone, you're supplied with, I think, 10 volts DC. You keep that 10VDC when you are talking. When you make a call, I think it jumps up to 48VDC, until you answer it."
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5wmyvf | What is the true purpose of "Tag a friend who ..." spam-posts on facebook? | I guess it has something to do with facebook's algorithm for ads or something? Or is it just a ruse to gather personal information from people? They are annoying as hell and I'd like to understand why they exist at all. **Just to clarify:** I don't mean the Rolex spam hacks that have *you* involuntarily tag friends. I mean the posts from random very low-effort pages or just radio stations, often a "funny picture" where you are encouraged to tag a friend to embarrass them. | Technology | explainlikeimfive | {
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"Generating range, e.g., exposure. Getting a brands' name 'out there'. Every view, every click, every page loaded is, at its base level, an interaction with a brand, or product and a potential customer. Any page, be it a standalone website, a facebook page, a blog or whatever kind of means a company decides to use to promote a product, is 'counted' by said customer interactions. This is usually called the 'range' said medium can generate. An example from Twitter would be someone with 10 followers, writing a tweet. Let's assume that all 10 followers each have 10 followers of their own and all 10 retweet this one tweet. This means, with one tweet, the tweet is seen by (10x10) 100 possible customers. Now imagine a tweet written by someone who has 1000 followers, each with 100 followers. If only half of those followers retweet this single tweet, we're already at (500x100) 50.000 possible customers being exposed to the companys' product. Thus the range in the latter example is way higher, than in the former. This range is valuable in terms of what a marketing company, or similar, is willing (or has to) pay for their commercial to appear on said medium. That also is the reason why, in comparison, a print ad is much cheaper, than a tv ad - their range is hugely different. So, to come to a stop, all these 'tag a friend that...' sites try to enhance their own range, be it to gain a better position to sell their own products, *or* to have better 'arguments' when dealing with other marketing companies that want to place ads on their site."
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5wo9y2 | Why can't you compress a RAR file with RAR or ZIP? | Why can't you compress a RAR file, | Technology | explainlikeimfive | {
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"Compression is a technique for finding patterns in a file and writing it in a way that takes more space. For example instead of writing \"aaaaaaaa\" you may write 8*\"a\" which is much shorter. Or instead of writing \"abcdefgh\" you may write \"a\"-\"h\". However if you have already compressed a file and written it in the shortest way you can think of then another compression program will not have much luck trying to compress it further. If you think of your file as a sponge. It consists of a sponge material and a lot of air. This is practical for cleaning but not very practical for transport. So you put in though a vacuum sealing machine to suck all the air out and put on a plastic seal to keep all the air out. Now the sponge is much smaller. But you read of another way to do it by using a vice. However when you put the already compressed sponge in the vice you can not get it much smaller. This is like trying to compress an already compressed file."
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5woe50 | Why can't we just cover a proportion of the desert with solar panels to provide the world with energy? | Technology | explainlikeimfive | {
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"So electricity. It needs to be moved and can only be used as generated without significant infrastructure. So lets just look at moving Electricity from Arizona to say Maine. Line losses. Electricity needs to be at high voltages to move it. that is why AC won out over DC. Not because Tesla rocked and Edison was a jackwad, but because DC has a limited transmission range. Literally in the couple miles range. So we need AC. Solar generally makes DC. So the DC needs to be put into a converter that makes the DC into AC. Because we live in reality and not theory or make-believe there will be losses in converting the DC to AC. Also a line 100 miles (160 kilometres) at 765 kV carrying 1000 MW of power can have losses of 1.1% to 0.5%. A 345 kV line carrying the same load across the same distance has losses of 4.2%. So if we ran 765KV line from Arizona to Maine is like 2800 miles long. That is a considerable amount of losses. That comes out to about a 25% or better loss in the transmission of that power. So to combine the losses in the generation and swap to AC and the line losses you end up losing a huge amount. Additionally at the beginning and the end you have to step up and then step down the voltages. That incurs more losses. So overall the losses from the Sun hitting the PV panels to someone turning on their TV in maine incurs a huge efficiency penalty. So while the solar source is free, the transmission equipment, transformers, and all the other equipment is not. So now if you take the standard that solar runs at: about 10-25% and apply that and the losses you get huge generation numbers for what would need installed. 11 million MW hours of power were consumed. So to math this 11,000,000 MWh of power needed. So we need to up the production to account for the losses. So let's divide that up into 365 days of use and 24 hours per day. That comes out to needing an average of 1255 MW of production. Now we add the losses we have to make up for. That comes out to 1794 MW of production. Then we have to throw in the Capacity factor of solar. The industry runs low compared to other power systems. But a plant in Arizona has been hitting 29% so we can use that. that means we need to start with 6185 MW of faceplate capacity. And we need to be able to store that power. We haven't added storage in yet. Since the solar must be stored some place for when the sun is down. That will add in more losses and therefore more base capacity to meet the needs of the end user. Agua Caliente is 84 MW of faceplate capacity on 2400 acres. So we need to multiple and we come up with 176,735 acres give or take. That is about 276 sq. miles of solar. The problem is not with the production of solar electricity. The problem is with storing and moving the solar electricity. The other thing we have not talked about is maintaining grid stability. Thousands of small PV site feeding into a huge grid with nothing to anchor the grid will make it unstable. When a large industrial plant starts a bug line up or a aluminum recycler starts the induction heating process that load has to be absorbed and these small PV suppliers cant handle it. There are vast engineering problems that need to be solved here. NO it is not impossible, but it needs to be looked at as a whole, not just little pieces. Too many people assume the only thing that needs power is homes and basic lighting and ignore the rest of the grid and the businesses and industry we have in this country. We need a grid they can rely on. The problems are solvable, but not by activists pushing their favorite flavor of solution or the neat product of the day. Power walls are great. Except for all the drawbacks they have that we ignore. Solar is great except for some of the drawbacks. nuclear is great except for some of the drawbacks. Ask your self why we are shutting down already operational and carbon free nuclear plants, but are willing to pay extra in taxes to build carbon free NEW renewables. It is stupid. And it ignores the facts of the grid and engineering. Solar cannot be used as abase load. And the technology for storage is more in its infancy than renewables are. And before we can really have any chance of renewables really supplying the whole of the grid, storage has to be solved.",
"Who would be doing it? If you're doing it for the public good that's a government project and you need to convince stubborn politicians that it's a good idea. Good luck with that! If you're expecting to make money you need to deal with ongoing maintenance costs as well as the initial setup (even if initial setup is relatively cheap these days). And then you need to make they money back by selling the power, but what if the price of power goes down because you're providing it in such large amounts? There are some practical concerns though. Moving electricity is not free or completely efficient. Distributing power around an entire country ends up wasting a lot of it and requiring strong infrastructure and these problems would be even worse with one central source a far distance from where the power is used. And what about nighttime? Storing electricity is a problem that has NOT been solved on the type of large scale such as \"powering a whole country\". And solar panels on opposite sides of the world somehow covering for each other when one side is in the dark increases the problem of distribution even further.",
"Solar engineer here. Let me explain some of this that's been covered by some people already. __Why Not Solar In Deserts?__ If we are talking a new array away from people, someone has to lay out all of the infrastructure for it to deliver power to the grid. At the same time, someone also needs to figure out how to shut it down when the largest source of power on that power grid fails because pumping electricity into a powered down grid can have disastrous results. This is typically solved in home solar with a fast disconnect, in which if power to the home stops the array ceases function to help the main power company in the area get things going again. Next is maintenance on the panels. The thing about large constructions in remote areas or even out of the way spaces is that most companies that put something out there intend not to have to come back to it unless they absolutely have to. The issue with this and solar is panels may die, panels need cleaning, sun tracking mountings are expensive as fuck, and you'd have to pay for all the equipment and people to facilitate taking care of all this. The same fast disconnect isn't a great solution at this kind of scale either. Large power systems like this require a lot of extra engineering and planning and sometimes implementing solutions that don't even exist or cannot just be found off the shelf. (Gonna also drop that you'd have to landscape the desert unless you find a really nice flat spot and even then, you may want to have a leveler come through anyways.) Ultimately, there is a lot that needs to be managed that just aren't realistic to manage. At the same time, anyone who puts an array out somewhere needs a way to make money off it. They probably aren't going to be able to get the power company to pay for large sums of solar power without it being discounted a lot. After all, if I was a power company I don't need to buy power from someone else. The city may not because they are already getting power from the already existing grid owner. Leaving you only able to sell to new developments and offer power along side the power company to homeowners, at which point, why aren't you just an extension of the power company? And the power company does not have an industry interest in solar because fossil fuel is a bigger money industry. (This statement is wrong, check out /u/Halfway_Bayesian [post]( URL_0 ).) At the same time, your power needs to be as always available as a regular power company for emergencies and panels do not produce much at night. __Future of Solar then?__ I honestly think that the future of solar right now is in residential. Most homes can hold enough panels on their roof to offset all of their electrical costs and for a pretty fair price (about the cost of a car, between $10,000 to $40,000. Consider pricing is on average, $3.50 per watt on a panel.) I've seen in just the last two or three years alone panels going from 225w panels to 290w along side batteries and even solar shingles. The technology is improving fast and we will see a lot more of it in the next few years. However keep in mind too, not every place in the world is geographically suitable for solar power. Locations too far North and too far South won't get great benefits from solar power. Neither would a place that you could essentially call a forest. Solar I don't believe sells well in Canada or states and countries along the same latitude as Washington or Oregon state. [Check out Huppie's post here.]( URL_1 ) where they discuss solar at these more northern latitudes, I learned something new. To put things in perspective, if you live in Utah with a good South facing roof, 8 modules of 290w are enough to offset 3,000-4,000 kWh of usage at your home. For a lot of small homes, this can be all you use for a year. A lot of solar companies offer their own maintenance services or even equipping an array with other necessities like \"critter cages\" to keep birds and squirrels out from under your panels. Otherwise, you may have a ton of fried birds under your panels. They get hot. __Problems that Face Solar__ The biggest issue with the solar industry for individuals is electrical companies because they are virtually untouchable. The reason is that they technically own the power grid and if the entire city depends on it, there is nothing that can really be done. A lot of power companies lobby to keep solar out as well. If you do some research, Nevada was a booming industry. Then Warren Buffet's Pacificorp, changed how solar customers pay their bill for having solar. Essentially, they put up a premium that brings your power bill to, still less than before, but not as much savings. On top of that, you're now also buying power from a solar company or paying for panels under a loan or lease. Pacificorp, claims that they lose millions of dollars per year on administrative fees and are recouping that cost from solar customers with this premium. Some electrical companies won't even allow residents they service to have a solar panel system. There needs to be more policies for solar friendly developments and incentives for the industry. There are some, but there are also powers in the world that are cornering the market on power and do not want solar coming around because so far, solar companies are already undercutting profits from the grid owning electric company. I think there needs to be a lot more cooperation between power companies and solar companies rather than the electrical companies governing and restricting how power is being provided to consumers in an area. Tldr: __Solar panels require a lot of maintenance, the idea itself has a lot of business and municipal policy issues, and these same issues extend to the entire solar industry. Its much more feasible for residential solar to be happening for society as these same problems tend to be cheaper when costs can be levied on a private customer.__ If you want to be the one to do that though, do it.",
"Storage and transportation. You can keep a barrel of oil for months and it will still be good. You can cart a barrel of oil halfway across the world and it will still be good. And we do this. A lot. A barrel also doesn't cost much to make and can be made out of cheap materials. Getting solar power from the Sahara to Stuttgart is going to be difficult. Once it's electricity it has to be used immediately. Batteries are really expensive and made out of things that are bad for the environment. Other cheaper things like boiling salt lose energy very quickly. Building power lines that far will cause a lot of power to be lost on the way. Some scientist are working of a way to turn the energy into oil and burn it later, but it's still in the experimental phase.",
"Short answer is, we could, but it's not entirely efficient, and it would require a big chunk of money, and we'd have to deploy *vastly* more than we'd want/need to make up for that inefficiency. Other people are saying electricity can't be stored. This is obviously false. Even taking aside batteries, electricity is just energy, and you can store energy countless ways: pump water uphill, then harvest hydropower later. Lift a heavy weight, harvest the energy later to produce power, etc, etc. There are even solar plants that are [specifically designed for nighttime power generation]( URL_0 ). The other end of it is forcing transition. Oil/gas is still cheap, and there is a *huge* amount of infrastructure in place for deploying it. It's going to take a long spin up before we can compete with that.",
"Only one other person mentioned it, but why would we do that? Most of the world's deserts have incredibly fragile and ancient ecosystems. It is pretty interesting but read about the microorganisms that live in the sand at White Sands National Monument. I believe you are not allowed to stray from the path because of how fragile the organisms in the sand are. They have created these layers on top of the sand over long periods of time. That would be a great place to put millions of solar panels but at what cost? Albeit mankind is not known for giving two shits about what we destroy. Also, it would be a logistical nightmare.",
"Largely because the sun goes down at night. We have few effective ways of storing large amounts of the energy we produce. That means at any given moment, we have to produce about as much energy as we consume. Our current power grid is divided into two main kinds of generation. *Base load* is cheap and efficient power that is slow to start up, like coal fired steam turbines. This provide most of our power, but is slow to adapt to changing demand. *Peaking load* is provided by more expensive but quick to start up sources, like diesel generators. They can be started and stopped rapidly as demand requires. Unfortunately, solar and wind power are not real good at either, because you can't presume they will be available. At best they provide a buffer between base load and peaking load, but both of those other energy sources need to be available.",
"-First you have to convince politicians to get on board. -Then they have to convince the public to get funding. It would be expensive. So convincing everyone will be difficult. Do we raise taxes? -The cost maintenance is expensive. -There is also the environmental impact of it. •Solar panels require lots of water. for cleaning. •Where does the water come from? •How do we pump it? •How much will that cost? •What do we do with the grey water? Recycle it? -How will it affect the wildlife? •Even though a desert may be. inhabitable for humans there is probably a great deal of wildlife who's entire world revolves around the desert. So how will covering an entire desert in shade affect the ecosystem? -Even if we conclude solar panels won't have a negative environmental impact, we need to make sure the construction won't have an impact either. All those trucks and machines could disrupt the fragile ecosystem that's inplace. -Also solar panels are still new. Every year they get more and more efficient. So at what point do we start replacing the panels with new ones? -How much will replacement cost? -Where do we get funding for that? -Will there be any environmental impact when we begin replacing the panels? Again all those trucks and stuff. All in all its not cheap and we could be potentially disrupting vital ecosystem. And if there are any endangered species involved it would be even more difficult to get the green light. I should note I'm no expert. We discussed this in class the other day and I'm just posting what my notes say. Also this is on mobile so sorry for spelling grammar or formatting errors",
"Cost, maintenance. And the real kicker: transfer losses and storage. Not enough people would live near by to be able to maintain it cost effectively. Sand can cause wear and tear on \"things\" so you would have to engineer around that. And no major population centers nearby deserts, typicall, so the amount of power lost on the wire would be very high. And storage: would still need to produce power at night. So a hybrid approach would be cool. I don't know why they don't put solar collectors on the outsides of the windmills.",
"In addition to all the other replies that focus mostly on a technical and economical perspective, there is also a whole other one: If even your country alone (let alone the world) relied on one single source of electrical energy, you're going to have to invest a lot to make it secure and reliable. Imagine you built a giant solar farm in the Sahara desert to power your country (let's say Italy). Your power is now being imported from a different country. You might have contracts with them that permits you to use this power generated in their country, but what stops a corrupt government or revolutionists to cut your power? You may guard your solar farm, but if it's big enough to power your whole country, you'll need lots of guards. Such a project would also be easily attackable by terrorists, so it's really insecure. With that aspect alone, how would you find investors? Likely nobody would want to invest in an energy source that's so likely to be taken over by rebels or terrorists.",
"1_ it is being done in Morocco and other countries. 2_It doesn't need to be that sunny to generate electricity, Germany generates more solar power than the USA even though southern USA is way hotter than Europe. 3_ AS prices for the panels drop, it will happen.",
"It would be better to cover up drinking water resevoirs with floating solar panels as you help save water from evaporation and use space closer to a city",
"The Transmission grid is much more (complex / fickle) than you think as well. You cant just simply pump a few electrons through some metal and have everything work. All of the load must be managed instantaneously with the generation. This equation not only includes the amount of power but the frequency as well. The utility has to constantly manage the fluctuating frequency of the load on the grid. Which is not consistent with solar or wind. In the US its around 50HZ. The frequency your electronics run on. If this gets out of wack the whole grid can collapse. Its issues like this that cause renewables to be a much more problematic energy source than the general public understands. Source: I work for large utility and renewable are a pain in our ass.",
"* Solar panels are expensive. * Installing and maintaining them is expensive, especially in remote areas, especially with dust and not much rain - you want to clean them. * Cables to connect them to the grid are expensive. * The sun doesn't shine 24/7, you need some storage system or other electricity sources in addition. * There are projects in deserts, but they are not very cheap.",
"WE CAN. in 2008 a 500ish billion project called desertec was launched by Germany, the EU and a bunch of other investors to build exactly that in the sahara. However unfortunately as the project was getting started the Arab Spring happened. (in 2011 people got very unhappy with there goverments in the Arab world and started lots of revolutions and wars) So people got scared and thought it would be to risky to build in those countries. It is however now picking up pace again and north African countries are starting to build huge solar farms (with some being solar thermal which even generate at night) but they want to power there own people first. Similar China has built a huge 2000 mile HVDC transmission line from the western deserts to its coastal cities so that the can start building solar farms there. Other projects being done to bring energy from far places to places where people live include HVDC lines linking volcanoes in Iceland with Europe so they can send Geothermal power to Europe.",
"Aside from the moving and storage problems, there's the whole environmental impact and simple maintenance. You'd need a TON of solar panels to create enough solar power for everyone, which means you build a giant solar farm out in the desert. This jacks with the local ecosystem. Then you need to keep the panels clean so they can operate at maximum efficiency. That means you need a lot of water to clean them. If you set these up in the open desert...where there really isn't a lot of water...now you have to ship water in just to clean them. Then there are the solar plants that use giant mirrors to reflect sunlight to then heat up water for steam generation. These things also take up lots of land, which then negatively effects the ecosystem. Birds literally get fried in the air if they fly into one of these, and the heat generated creates a giant warm air updraft that messes with planes. There's still a lot to work out. I think having massive solar farms out in the desert is impractical. I think the real solution is having a combination of solar and wind generation on your own property with battery storage. It's the only thing that makes sense.",
"Two reasons: 1. Electric power is lost if not used or stored immediately. We often want to use electric power during hours when the sun isn't shining. Storing power it is expensive and difficult (but we're getting better at it). 2. There's a significant amount of power loss that comes with transmitting electric power across long distances. High-voltage lines are more efficient, but longer lines experience more losses, so it's not practical to generate power in the Sonoran Desert for consumption in New York.",
"Just the cost to install would be mind-blowing, let alone maintenance. The approximate cost to install solar panels is $3 to $10 per watt generated. It's a large range, but it really depends on the quality, amount, and area you're installing them. The current worldwide power usage is about 340 watts, so the cost for solar panels is between $1,000 and $3,400 per person. That seems pretty reasonable until you realize there's 7.5 billion people on earth, so you're looking at a cost of $7.5 trillion to $25.5 trillion. That's just to install the panels, it doesn't even cover the cost of the land, the labor, or the maintenance of the panels. And that's even ignoring the cost to transport such a large amount of power around the globe. I know what you're thinking... so what about just the United States. Well that 340 watt per person figure was worldwide, if you take just the United States into account then you're looking at 1380 watts or approximately $4,000 to $14,000 per person. At a population of 319 million, you're looking at approximately $1.27 trillion to $4.47 trillion... again just for installation.",
"URL_1 Read this and you'll learn why... URL_0 It's not very effective. Look at the comparison from the solar panels to Palo Verde Nuclear Power Plant.",
"If this would work then how much better would it be to put billions of solar panels in space between here and the sun and have them just beam the energy to earth.",
"Actually, you dont need any solar panels to provide the entire world with unlimited electricity. All you need is a single cable. Run the cable north to south. That cable will pick up solar radiation and generate electrical current through it. This has been known since Galileo's time.",
"I would rather see power production move smaller scale than larger. In a perfect world, every house would have its own power plant. It would be a consideration when buying a house and would be something to maintain on your own, just like your roof, furnace or water heater. I know for regions without a lot of sun or wind the tech isn't there but I'd like to see the push in this direction.",
"We send electricity through wires from power plants to our home. The energy (electricity) that we add to the system is equal to the energy taken out of the system, **minus** electrical friction (heat) losses. The longer the distance from the power plant to our home, the more heat energy that is lost in the transfer process. To transfer from deserts to the world would cost too much in terms of energy loss to be benefitial.",
"We will be able to do so, someday. HVDC is a cheaper way of transmitting electricity than HVAC if the distance is *large enough*. [source]( URL_1 ). There are new batteries being developed that should be *safe* and *not-environmentally-disastrous*. [source]( URL_0 ) My guess as to why we are not doing it right now is that there is already a lot of money in other forms of energy and not enough incentives to go full solar. When I speak of incentives I mean the sum of all the factors that could make full solar, today, less profitable than other forms of energy.",
"Don't know if it's been mentioned yet, but deserts are also full of sand and wind which can scratch and damage the surface of the panels at worst, and at best require regular cleaning There are robots you can hire if you have large enough farms but they would need to be in constant use and power would drop during sandstorms Night is also usually very cold in the desert, so the big change in temperature on a daily business from high max operation temp to low 0-production temp is an engineering challenge in itself TL:Dr harsh environment = damaged components and maintenance costs",
"Intermittency - the sun goes down at night and cloud cover is still difficult to forecast more than a day ahead. Location - the cost and losses involved in transmitting electricity from the sunniest regions to the least sunniest regions makes the enterprise unviable. Engineering - the grid can't handle it, you need responsive energy generation to handle peaks and troughs in demand. Investment - Leaving the aforementioned problems aside, it would be disastrous to invest the enormous sums needed to scale up solar PV only to find that more efficient solar cells were developed a few years later, or some other innovation rendered the solar fields obsolete. Energy return on energy invested - Solar is currently way behind Wind, which still slightly lags behind oil (although the newest, largest turbines are catching up)",
"Many of the comments highlight the logistical issues with this but there are also environmental impacts as well. While many people think of places like Arizona as just massive deserts with nothing living there, deserts are home to many different flora and fauna. Here's a [link]( URL_1 ) some of the various wildlife present and another [link]( URL_0 ) showing the variety of the different types of desert ecosystems in Arizona. To make room for a solar farm you'd have to remove a large portion of these ecosystems to generate even enough electricity for a single city let alone the whole world. There are definitely logistical issues with covering the desert with solar panels but it would also be the same as removing a forest to make room for that level of energy production."
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5wri0q | What is, and what is wrong with AmazonS3? | Technology | explainlikeimfive | {
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"Amazon S3 is short for Simple Storage Service. This is part of Amazon Web Services, or AWS. AWS, to simplify, is an **ENORMOUS** pile of computing power and storage. People are able to freely rent chunks of this power as they see fit, treating that chunk of muscle as their own private server. Even better, it can scale dynamically: need twice the power for just today? need twice the power for just the next *minute*? Need ten thousand times the power for the next four years to support your growing corporate enterprise? You got it. Amazon is able to offer this for a cheap price because they already spent a ton of money building such a powerful setup made of hundreds of thousands of physical computers, and they are guarenteed that if *you* don't want the power, someone else does, and it's available to that other person immediately. They have over 150,000 major customers, including some of the biggest people on the 'web. S3 is used primarily for data storage, so lots of sites (such as imgur) use it to store relatively large items like pictures. Some sites don't run completely on Amazon's setup but just use it to store big stuff, which is why some sites would do stuff like show text but the pictures wouldn't come. Exactly what is wrong with S3? Amazon hasn't said, and they don't have to. It appears that sometimes requests for data go into the building and don't always come back out, which.... really doesn't tell us much. We kinda have to sit on our hands and wait.",
"To add: When we sent requests to the S3 server, we would get unspecified errors just telling us that it didn't work. To quote Amazon: Update at 2:08 PM PST: As of 1:49 PM PST, we are fully recovered for operations for adding new objects in S3, which was our last operation showing a high error rate. The Amazon S3 service is operating normally. Update at 1:12 PM PST: S3 object retrieval, listing and deletion are fully recovered now. We are still working to recover normal operations for adding new objects to S3. Update at 12:52 PM PST: We are seeing recovery for S3 object retrievals, listing and deletions. We continue to work on recovery for adding new objects to S3 and expect to start seeing improved error rates within the hour. Update at 11:35 AM PST: We have now repaired the ability to update the service health dashboard. The service updates are below. We continue to experience high error rates with S3 in US-EAST-1, which is impacting various AWS services. We are working hard at repairing S3, believe we understand root cause, and are working on implementing what we believe will remediate the issue."
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5ww873 | What makes it possible to control a touch screen while lightly hovering your finger over the screen? | I just realised that I was still able to control my phone's touch screen by pressing the screen, and raising it about two millimeter above the screen, so this was quite a surprise to me. Thus I was really curious to understand the phenomena further. I'm case this is not doable under normal conditions, ill precise thst I've been using a S5 neo and eating bugles for a while now before noticing the effect. I'm eager to understand this phenomenon and hear from your thoughts in the comments, thanks in advance for the reading and the answers. | Technology | explainlikeimfive | {
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"The way most modern touch screens work is the folowing (very simplified): The phones screen creates a magnetic field. Your finger (or basically any conducting object) changes that field when it is inside of it. The screen then calculates where those changes happened and therefor have the position of the touch input. And since the magnetic field is a bit bigger than your screen, you can also change it if you are not directly touching the screen."
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5wwcbr | How does a police officer prove his radar reading was specifically for your car when there's hundreds of cars whizzing by on a busy highway? | Technology | explainlikeimfive | {
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"They point it at your car. They can observe you are moving faster than the other traffic and they stop you under their own judgment. In court their judgment is generally considered to be reliable evidence that a particular motorist was behaving incorrectly.",
"Kinda related.....LIDAR guns have a sight on them with a crosshair that show exactly what the gun is pointed at.",
"A radar can be set with a \"gate\" so it only reads the vehicle, say, more than 300 yards and less than 325 yards away. If you are the first car to enter that gate you are the target. Cars coming in later while you're still there cannot be individually measured accurately. The officer learns how to use the radar and that is one of the many options available. There are techniques for almost any situation, coming or going, moving or stopped. (Also laser instead of radar can pick out anyone, anywhere.)"
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5wwfh4 | why do so many people film cellphone videos in portrait mode? | Technology | explainlikeimfive | {
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"Because that's how you hold a phone when doing most other things. It doesn't occur to them or they don't care. It's easier to hold a phone one handed especially with how huge phones are these days.",
"1) That's how people hold their phones 2) They're usually filming something that goes up and down, like a person, or a tree, or whatever, and they feel (rightly) that portrait orientation makes the subject fill more of the screen, and landscape just adds useless information on the sides of what they're trying to show. 3) People are usually close to what they're filming, so turning the phone on its side gives less framing, top to bottom, and they feel like they're cropped in too far, and don't want to step back 4) They consume videos on their phones mostly, and feel that most other people do too, so if they (and others) are going to view the video in portrait orientation, they should film it that way. I remember back to the days when dumb people were resistant to widescreen movies because \"They add stupid black bars to the top and bottom and you lose a bunch of picture\". It's like that.",
"If they are trying to be stealthy it makes sense, most people don't hold their phone sideways unless they are taking a video.",
"I just plain forget to turn it sometimes. Portrait mode is how I hold my phone for everything else, sometimes I just forget I have to flip it the other way. When I realize I've recorded in portrait mode, I get annoyed with myself."
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5wwlrr | Why mobile banking apps are so far behind in functionality compared to internet banking. | Technology | explainlikeimfive | {
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"dedcmh7"
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"text": [
"They don't need to be. Most mobile banking apps are capable of doing 90% of what you need to do for online banking - you can check your balance, transfer funds, deposit a check, pay a bill, etc. The more complex functionality, like opening a new account or applying for a loan, is done very rarely and requires more input, so it makes sense to put those on the website only."
],
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5
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5wwqcj | How was it decided that clocks move "clockwise"? | Technology | explainlikeimfive | {
"a_id": [
"deddjj9"
],
"text": [
"The way the shadow moves on sundials in the northern hemisphere. That's really all there is to it. People were used to reading sundials, so when clocks were invented, it was a natural choice for the hands to move in the same direction as the sun's shadow."
],
"score": [
53
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5wx6g9 | How do night contacts work? | Technology | explainlikeimfive | {
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"dedhpxe"
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"text": [
"My understanding is they reshape the eye. The degree of how concave or convex the lens of the eye causes near sightedness or far sightedness. Sleep contacts temporarily shape your eyes back to neutral."
],
"score": [
3
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5wxghu | How does Google manage to parse every page on it's database and show our search results on them in miliseconds? | Technology | explainlikeimfive | {
"a_id": [
"dedl8hc"
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"text": [
"In fact they already have parsed all pages in the planet and created a database of relevant words and how these words relate to the pages. By doing that they have created a rank by words and what pages to show. Then they measure the distance between words and incorporate that in the rank. For example: a page talking about \"water bottle\" and another talking about \"water gallons per bottle\" both contain the words \"water\" and \"bottle\" but in the second case the words are more distant and will produce a different rank if that search is done. Another think that is incorporated in the page rank is the number of links of important pages to a given page and what words are used to link. A link \"water bottle\" that links to a page, will increase the rank of that page, if the link is from a trustable source. To make things fast they have millions of computers spread worldwide, so the results come fast."
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3
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5wxh56 | How can siri or any other voice recognition software tell the difference when someone says your or you're, or its and it's? | Technology | explainlikeimfive | {
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"dedjr61"
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"text": [
"It determines it by context. If you just said that single word it would just have to pick one or the other, but as you add more information it can make a determination which is more likely. If you watch siri you can actually see it do this in real time. It will put a first guess for the word, but as you continue to talk prior words will change given new information."
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5wxrrr | What actually happens to the mobile phone networks/cell service when there is a large scale emergency or disaster? What do the networks do? | I've read that mobile networks possibly allow calls to be free, or turn certain service or features off so there isn't any unnecessary strain on the network in the event of large disasters etc. What's the deal? Edit: Sorry about the whole flair thing guys, I'm on the Reddit app & don't know how to do it. | Technology | explainlikeimfive | {
"a_id": [
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"Its been a while since I worked in telecomm infrastructure but I'll take a stab. > I've read that mobile networks possibly allow calls to be free You're talking about the rule that says all cell networks have to allow emergency 911 calls to any mobile subscriber regardless of plan status. Yes, even if you don't have a SIM card you can make a 911 call. > or turn certain service or features off so there isn't any unnecessary strain on the network in the event of large disasters etc. If a 911 call is made and the network is already at capacity, then the network will start dropping other calls to ensure the emergency call goes through. Obviously in an exceptional case like 9/11, the cell towers around the WTC and the Pentagon I'm sure were stressed. When you make a 911 call with your cell, it starts to channel battery into boosting your signal and ensuring talk time (so good buy Instragram app). Since they work \"similarly\" to cell networks, the emergency responder radio networks can be adjusted in real time. The \"cell\" or repeater for downtown Manhattan FD/PD/EMS was on top of the WTC. However some vehicles carry mobile repeaters to provide coverage. The radio vendor (Motorola) had an emergency infrastructure truck on site in a few hours to provide missing coverage downtown. The groups/teams/platoons of radio subscribers can be regrouped on the fly as needed, or networks of radios can be merged - this is what happened in DC, when you had emergency vehicles from 3 different counties responding; the radio networks were reconfigured to allow intercommunication."
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5wyeat | Why are smartphones getting thinner and thinner? | Is there any reason apart from aesthetics? Why aren't smartphones ignoring this in favour of a larger battery? | Technology | explainlikeimfive | {
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"text": [
"The market has said that all else held equal, they want thinner phones over doubled battery life. Every phone has to have some sales niche. Some will be designed favoring battery life over thickness, others will be extremely thin and lightweight. Tablets can be phones too if you're looking for maximum utility over bulk or battery life. It's all a cycle, and today the market says thicker phones."
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5wz0qx | Why does old plastic go yellow? Will that happen to plastics made recently too? | Technology | explainlikeimfive | {
"a_id": [
"dedxpim"
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"text": [
"A chemical called bromine is added to plastic as a flame retardant; it's usually white/colorless, but when exposed to UV light for a long time it turns brown/yellow."
],
"score": [
4
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5wz3nl | How does my key fob only work on my car? | Technology | explainlikeimfive | {
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"dedyfib"
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"text": [
"the fob sends out a signal that acts like a password only your car knows. if it recieves a signal with the wrong \"password\" it wont respond, so as long as nothing goes wrong each car should only respond to its paired fob to prevent someone from duplicating the signal to break into your car, it generates a new one periodically, but someone who knows more than me will have to explain the specifics"
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5wz4nv | Whydo developers still use Unreal Engine 3 if Unreal Engine 4 is available? | Both were also released 2 years apart so I'm not even sure if there is a monumental change in features. I do understand that they are freely accessible and new is usually better hence my confusion | Technology | explainlikeimfive | {
"a_id": [
"dedynsa"
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"text": [
"Former game developer here, Principally the reason to stay on a given platform is either because of licensing or because you're invested on a particular version and there are breaking changes if you upgrade. So what is more important? Upgrading your engine and fixing what breaks or using the engine you have because it works right now? Does the investment yield a return? What are the financial and technical risks? A more mature platform that is actively developed and supported is going to be more stable than a newer platform that doesn't have as many miles. The other reason you see old engines come out for new games is that those games started development before UE4 was even available. Unless you're Duke Nukem Forever, you don't abandon your platform once a new version becomes available. Studios don't have the time or money, most of the time."
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11
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5x063z | What is 'Legacy Code' in programming? | Technology | explainlikeimfive | {
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"text": [
"It is code, often written in archaic languages running on archaic systems, that no one who has to work with it really understands anymore. The original programmers have retired or are dead, the company that made no longer supports it or is out of business, and the requirements are lost or never existed. If it serves a vital purpose, it becomes a sort of a black box everyone is afraid to touch. It doesn't interface well with more modern software, so it takes increasingly convoluted hacks to keep it working. Eventually the company will bite the bullet and commission a project to replace it. These projects often fail and the company returns to the legacy software.",
"It's any old, established system. Generally it implies using older languages, techniques and systems. That 40 year old system written in COBOL that runs your bank on a mainframe, using a database that hasn't been sold for 20 years is a legacy system. There's also a heavy connotation that it's full of mysterious but business critical rules that nobody really understand.",
"'Legacy code' is industry-speak for 'old crap that no one wants to work on but that has to be maintained and kept running because it still does something we need'."
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5x0x0q | Can you create a flashlight bright enough to shine completely through a person? | So i was taking a minute with my flash on my phone, and was struck by how it was bright enough to go through my finger to the point where some of the light reached the table beneath it. I was wondering if a flashlight could be made bright enough to go completely through people? Why or why not? Thanks for satisfying my curiosity, reddit community! | Technology | explainlikeimfive | {
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"text": [
"No. The light is shining through the translucent parts of your finger - not the bone. The visible spectrum can't go through bones."
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5x22gw | How come sometimes a coin won't work on a vending machine, then after retrying it one or multiple times it will work eventually? | Technology | explainlikeimfive | {
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"deenhli"
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"**TL;DR**: *The sorting mechanisms weren't quite perfectly calibrated, or are dirty or loose or otherwise have moved away from perfect calibration over time, or the coin went too fast or is a mess, and so the coin doesn't get slotted correctly and falls through to the return slot as a reject the first time. But you got lucky on the second or third retry.* The simplest vending machines generally characterize coins by size. The first one is done by rolling or sliding the coin across slots of increasing size, and it falls down the first one that it can fit into. So dimes go first, then nickels, then quarters for American machines (Canadian machines add slots for their $1 \"loonie\" and $2 \"toonie\" coins. Can someone comment on Euros please? Dunno about them). Anyways each passes through a size-checker to ensure it's exactly big enough to fit its designed slot, not a little smaller, and a counter that does the math using a simple computer or mechanical processor. (More advanced versions like optical bill acceptors use computer scanning and comparison, and some use magnets to affect the coin's path. But let's keep it to simple older ones that process coins.) For this to work reliably, * the gravity feeds must hit the right speed for the coin or it'll skip over the slot, so slamming a coin in too fast causes it to skip its right slot * the size checkers can't be worn down or you'll get false negatives because a coin is a fraction of a millimeter smaller than its size-checking slot now * dirt or dust didn't get in there and gum things up or change the speed of the gravity feeds (same for the coin) * the coin can't be warped and must be perfectly round. So a legitimate coin falls through because one of these didn't work, and you toss it in again... and this time it goes, because you nailed the right velocity this time to allow it to fall in its slot, or that bit of dirt moved, or the size measurement didn't hit that worn edge this time, or it bounced in a way that matched the calibration or wear-and-tear inside the sorter."
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5x37jd | What is happening when a game is loading? | If a game can render the scenery and objects as you're moving through the world, what's the point of waiting behind a loading screen? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"So imagine a fast food place that can make burgers really fast, on demand. This is like the game when it's loaded and running, it's rendering stuff quickly and on demand. In the morning someone has to open the fast food restaurant, warm up the grills and get the ingredients out and prepped for rapid burger making. This is the loading screen, when the computers loads up all the information it will need to render at full speed and gets it ready. It does all of that upfront so it can just churn out burgers later without worrying.",
"Typically this is mostly due to I/O, loading assets from a (slow) disk into (faster) main memory or (fastest) GPU memory. There may also be some processing involved, for example assets may need to be decompressed or otherwise pre-processed.",
"Imagine the system running the game is your own mind. You have vast archives of information stored in your memories, but you can't access it all at once because the human brain can only concentrate on a few things at any given time. In this analogy, your memories are the game data on the hard drive and your surface thoughts are the system's RAM. When the game is loading, it's copying the files it needs to run from the hard drive, which is huge but slow, to the RAM, which is fast but has limited capacity. Because the game has to render everything 30-60+ times per second, it's just not possible to get all the data from the slow hard drive every time it's needed - so the game copies the relevant data to the fast but small storage in the RAM, and puts up a loading screen whenever it needs to do that. Interestingly, many modern systems have enough RAM to fit an entire game - there is software you can use that alters the way games run so they copy all their data to the RAM at launch, virtually eliminating loading screens by bypassing this entire process."
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5x3jdu | Why aren't consumer computers "instant" yet, in terms of the basic functions like booting up, opening up programs, etc? I mean literally instant, with zero delay following a mouse click. Will they ever be? | Technology | explainlikeimfive | {
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"There are instant computers, you just don't think of them as \"real\" computers. Tons of devices with embedded microcontrollers (household appliances, elevators, traffic lights, you name it) have real computers in there that load their resources almost instantaneously and can get going. As for \"real\" computers, we'll probably never see instant ones because as soon as the startup process gets faster.... people dream up more functions and resources for the computer to load. As computers get faster, we just keep on giving them more to do. Microsoft Office 95 would probably load in a blink of an eye on a modern machine, but Office 2013 takes a while. But 2013 offers a ton of features and changes it's predecessor didn't that MS decided was a worthwhile tradeoff. The case is the same for most software.",
"Computers will never be 100% satisfactory in their performance at all tasks. There will always be complicated (for a computer) tasks that take it more time than it takes for us to act/react. I had to save a bunch of 1.2GB photoshop files to a file server at work yesterday and I was annoyed that it was taking almost a minute for each one. However, I was also annoyed that the file format I was required to use would not support more than 2GB file size, so I simply couldn't save the images at the resolution that would have been ideal for the task. This sort of thing will always be true, in different degrees, about computers.",
"Computers aren't instant because we keep wanting them to do more. Take a current computer with an SSD and boot to DOS 6.22 and run some old applications. You'll probably find near instant load times and response. You'll also notice all the limitations of those programs. It's the same reason why phones these days have batteries that only last a day where before they could last a week. The battery is better now, but we use more power as well. But if you want an instant computer you can find them. most smart TVs are like that, the load times for netflix and such usually is the internet, not the program",
"Some of the delay in booting up the computer comes from legacy compatibility reasons. You can not use a more modern way of doing things because the computer might have to run an older operating system and the operating system might have to run on an older computer. So for instance the PS4 are able to boot up much faster because it does not have all the legacy compatibility but can start from scratch. However this means that you need to modify the operating system a lot to get it to run, like they did with Linux. However the biggest issue is that we expect more and more from our computers. The computers that came to market in the 80's did boot up almost in an instant and loaded up programs from a cartage before you noticed. However we now demand more and more from our computers so they have to load more and more. If you are to step back a bit and set up a modern computer with less capabilities it will boot up and start the simple applications it can in very rapid succession. For instance a modern web server might reboot in 3 seconds although it can not do much else then serve web pages."
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5x48v0 | How can antivirus companies can analyse new and powerful viruses without getting themselves infected ? | Technology | explainlikeimfive | {
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"They keep the viruses contained, for instance in rooms with negative air pressure (so that any airflow runs in instead of out) and containers that the virus cannot penetrate. Then, they study them wearing gloves, or environmentally sealed garments, or with indirect tools like monitors, instead of nakedly handling them.",
"I actually used to work at an AV company! As others have said, there are mechanisms in place to ensure that infected file samples are only opened in a \"sandbox\" environment. Basically these are entirely virtual labs which are being emulated, and set up on virtual networks which are separate from the physical interfaces. With this structure, they can activate a virus sample and see how it affects the sandbox system. Its behaviors (how it loads into memory, what files it writes, etc) are then compiled into prototype virus definition files. The sandbox is reset, and they test again seeing if the new definition files successfully stop the computer virus. Provided it works, these prototype definitions are then put through a general QA cycle to ensure it doesn't break common windows installations out of the box, and is then finalized into part of your daily virus def downloads. If a customer attempts to send infected samples to customer support instead of the secure submission portal, there's a protocol we followed which involved politely reprimanding the customer and having them resubmit, as well as contacting our server department to make sure the contaminated sample is scrubbed. Employees are trained not to open any potentially infected files from customers, and we run with a rather strict anti-virus policy on our work machines. The closer the technician is to the public, the tighter the security controls. TL;DR: Layers upon layers of security protocols and locked down network environments to make sure hostile code is segregated from the rest of the business.",
"They have dedicated computers for this that *do* get infected so they can monitor the software's activities. As long as that sacrificial computer isn't networked to others there's no way for even the most devious virus to spread to other machines. Once they're done that machine is reset to factory settings and the operating system is reinstalled.",
"They use a sandbox (a kind of software container) that can protect system and test the execution of virus. And analyze it with a debugger for reverse engineering, so they can find the assembly of it and know what is able to do.",
"To analyze a virus behavior they *do* get themselves \"infected\". But they obviously do so in a controlled manner. Unlike biological viruses, you wouldn't get infected just by manipulating and storing them. Viruses, as any computer program, have to be \"run\" to actually do something.",
"Also, how do they get the viruses for testing? Do they browse porn site after porn site downloading as much crap as they can? What if a new virus spreads, do they do something particular to obtain it?"
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5x49dd | Do people without Nielsen boxes affect viewership ratings? Does recording a show and watching it later increase viewership counts? | I'm trying to find out if there are other metrics other than Nielsen. Do they still use Nielsen boxes? | Technology | explainlikeimfive | {
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"They still use nielsen pretty much exclusively. And nielsen still relies almost entirely on set-top boxes. They have a competitor in rentrak which uses actual data provided by cable provider partners. nielsen recently [struck a deal with dish network]( URL_0 ) to do the same. Their numbers are garbage and that's no secret to anyone.",
"I was told by someone who worked in TV in the UK, that there's a lot of ways of trying to work out what everyone's watching. In the UK, they'd look at spikes in electricity use after shows (because over here, we always put the kettle on when a show has finished). In more recent years, there's been more reliance on figures from catch-up services and the like. So, yeah, watching a show later counts toward viewer figures. They'll also be trawling social media to see who is talking about shows and televised sports events etc.",
"I worked for Nielsen installing the equipment to measure viewership in households, both in metered market and national. They send out written diary books but there is no way for them to measure what you watch if they don't come install the equipment and you have no effect on viewership, whether or not you record also does nothing."
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5x5c3k | From what I gather, Wikipedia seems to be a fairly neutral source. What prevents the polarization of facts on Wikipedia? | Technology | explainlikeimfive | {
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"There is a lot of arguing going on behind the scenes at Wikipedia. Visit the 'talk page' of the article on a controversial person or topic and there will be long discussions on what should be included and how it should be worded. Controversial topics also will have a lot of people watching their edits. If you want to wreak havoc at Wikipedia, then make an edit to an obscure article that nobody cares about.",
"Three points: 1) Wikipedia has a cadre of highly dedicated (occasionally fanatical) people who police the site and try to keep it on track. 2) Many fingers in the pot means that the version that survives the edit wars is the one that is most palatable to the widest number of editors. 3) Wikipedia really isn't that great. It is extremely useful and often well-done, but it also has a reputation for vicious flame-wars involving deeply entrenched factions, which often require moderator intervention. Ever notice how some Wiki pages are locked to prevent further editing? In most cases, that means the page attracted so much controversy and debate that the only way to resolve the problem is to shut it down entirely.",
"1. Community takes it very seriously 2. A demand for citation on *everything*, so statements are always backed up 3. No opinion pieces or anything like that allowed, just facts with no interperetation or opinion. Most places that consider themselves news sites (CNN, Fox News, whatever) also do \"opinion\" pieces, and while these are clearly labeled as such, if CNN runs \"Opinion: Donald Trump is a screwup\" some people will just treat that like a fact when it's really an opinion, a fact would be \"Donald Trump has done and said x y and z\" 4. No attempt to present articles that drive traffic. Most news sources try and put things on their front page that makes people hang around and read, which is profitable for them. This can often lead to cherry-picking juicy stories for more attention. Wikipedia doesn't try and present anything to entice readers other than information.",
"There are two core policies of Wikipedia work together to facilitate its neutrality: [Verifiability]( URL_4 ) and [Neutral Point of View]( URL_0 ). Verifiability means that all information of Wikipedia must come from a reliable source. Editors compile and distill this information in articles - they are not supposed to draw their own conclusions from the information (this is covered in more depth by the [No Original Research]( URL_3 ) policy). This makes Wikipedia a reflection of reliable information that already exists rather than a place that can develop its own ideas and biases. Neutral Point of View dictates that where there are conflicting statements *in reliable sources*, Wikipedia articles are supposed to represent the various viewpoints in reliable sources in proportion to their representation in the total literature of reliable sources. This makes the information on Wikipedia a neutral reflection of the (reliable) information in the world, not an arbiter of truth. See the essay [Verifiability, Not Truth]( URL_2 ) for more on this point. Of course, correctly identifying reliable and unreliable sources is central to all of this. Wikipedia's central guidelines on this are [here]( URL_1 ), but what is or isn't reliable ultimately gets hashed out in behind-the-scenes debates (which anyone can participate in!)."
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5x5ktc | Crowd gps | I'm looking into Trackr or Tile and they both mention crowd gps. It seems simple, but I still can't wrap my head around it. Does that person get your GPS location? | Technology | explainlikeimfive | {
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"defeo96"
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"text": [
"Crowd GPS apps are different in that they give your more real-time information such as obstructions in the road, red cam lights. All the added real-time information is gathered through different people who use that app. Functioning as a self sustaining community, people update the public map with new information wherever they are. Others can vote on whether this info is accurate or not in. The more people that apply to that \"community\" the more accurate and timely that info is."
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5x5zbu | AMD's new Ryzen processor. | I get that Intel dominated the market over years. But what is going on in the following thread? What are they all talking about? What is Zen? And what is that thing with the 3-5-7 number? And all this other stuff? I would be very grateful if you could please explain it like I am really 5 — or since my 7 year old cousin knows better than me how to handle an iPad please image for that case that I'm your 95 granny. Thank you! URL_0 | Technology | explainlikeimfive | {
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"Zen is a new processor architecture releasing pretty soon. The 3/5/7 is a marking nomenclature used to separate different models into mainstream/performance/enthusiast categories, very similarly to Intel's naming system.",
"Zen is a new architecture for AMD's newest lineup of CPUs, the Ryzen CPUs. 3/5/7 is just a way of dividing their processors into different categories, but also to match up with Intel's own 3/5/7 system (i3, i5, and i7). AMDs version will be the R3, R5, and R7 CPUs, with the R7s launching literally today. The biggest, most important bit of this new launch is the fact that AMD hasn't released a new CPU architecture in several years, causing them to really lag behind Intel in terms of performance. With the new Ryzen launch, AMD is selling processors of comparable performance to popular current gen Intel CPUs for a fraction of the price. As has been frequently pointed out, the R7 1800x (AMDs new top-of-the-line CPU) at $400 hands down beats Intel's 6900k, a current gen **$1000+** CPU. Ryzen's strong point definitely helps that last comparison out, as Ryzen CPUs (especially the R7s) are extremely competent at multi-threaded, intensive, more \"professional\" use tasks such as rendering 3D models and editing high resolution video. For gaming, Ryzen is definitely a little lackluster, offering little to no improvement over current gen Intel CPUs at simar price points.",
"If you want to understand all the hype the best way to look at it is through AMD's processors over the last 6 years. Throughout that time period AMD focused more on the integrated video processor built into their processors. What this means is that their processor lineup was not directly competing with intels processors because they were not as powerful at processing normal CPU tasks but rather the graphical elements like games or video rendering. This might sound like a good thing for gamers but realistically a gamer would have a dedicated graphics card to do that for them which would be drastically more powerful than anything that can be integrated onto a processor. This meant AMD had a very slim market. When they announced ryzen (originally titled zen) it was huge because this meant AMD would be competing with intels high end processors with actual processors again. This has not happened in over 6 years at this point. Over the course of these 6 years intel has charged a massive premium on their top of the line processors due to there being no competition. Everyone is excited not because AMD is making baller chips but rather due to this forcing intels prices down so the consumer isn't paying an unnecessary premium to get top of the line."
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5x63p3 | How does hashing work for single value like the letter "a"? | Technology | explainlikeimfive | {
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"You didn't specify what hashing algorithm, but in general, if the input wasn't long enough you would pad it by adding \"zero bits\" to it. Technically, even long strings often need padding as well. This is because to be able to work with the bit string properly it needs to be a certain length (or divisible by a certain length). Each algorithm has its own rules for such things. Sort of like if you had a number 42, but you actually needed a 10-digit number you would change it to 0000000042, but instead of using digits, you would use bits.",
"It depends on the specific algorithm. Generally some type of padding is added to bring the input to a proper length. Here's how the MD5 algorithm applies padding. > MD5 processes a variable-length message into a fixed-length output of 128 bits. The input message is broken up into chunks of 512-bit blocks (sixteen 32-bit words); the message is padded so that its length is divisible by 512. The padding works as follows: first a single bit, 1, is appended to the end of the message. This is followed by as many zeros as are required to bring the length of the message up to 64 bits fewer than a multiple of 512. The remaining bits are filled up with 64 bits representing the length of the original message, modulo 264."
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5x6618 | How did people slack off/waste time at their desks before the Internet or cellphones were invented? | Technology | explainlikeimfive | {
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"In the vicinity of a computer: minesweeper At home: television There are plenty of ways to procrastinate. You could even read a book. God forbid! Anything works when it comes to not wanting to work.",
"I predate the internet! When I had a private office, I'd chat on the (wired landline) phone. I'd make numerous long, meandering trips to the vending machine. I'd stick my head in other people's cubes to complain about the weather. I'd photocopy my hand and other body parts. I'd write letters (remember those?), or stories or a journal entry in my notebook. If I could get away with it, I'd read a book or magazine. Once computers were introduced, I'd play what few lame video games were available. If I was really desperate to procrastinate on a particular project, I'd do everything ELSE, like clean my desk or adjust the photos on my wall. Life was super boring back then. URL_0"
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5x68ew | Why social media apps take up so much storage? | Facebook, twitter, IG, etc all seem to take up 400MB or so each of data, and most of it is in "documents", why is this given the actual app is relatively light? | Technology | explainlikeimfive | {
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"I think the reason is primarily cached data. The apps download a bunch of content at once so it doesn't have to load progressively."
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5x6gjo | What is (if there is one) the difference between machine learning and AI? | My question started from a deep comment I made on /r/gadgets: URL_0 Kind of boiled down to my last question in the thread: > ...at what point does many machine learning data sets become an AI? Is this there a line in the sand where a program is one and not the other? Are there certain meta-characteristics that present themselves in a "legitimate AI"? Or is AI just a sufficiently well-rounded group of machine learning data sets? | Technology | explainlikeimfive | {
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"This looks like a version of the [Chinese Room argument]( URL_0 ). I'll summarize it here: Imagine that I put you in a closed off room, with no interaction with the outside world other than two small slots, an \"input\" and \"output\" slot. Inside of the room you have some paper and pencils, as well as a giant book (let's say infinitely large, since we're living in a thought experiment world) that has every question that you could ever possibly ask in the English language. After each question is listed the answer, but it's written in Chinese characters. Let's assume that you don't know any sort of Chinese, so to you, those answers are just a bunch of squiggles and squoggles. So I, outside of the box, write down a question in English and I slip it into the \"input\" slot. You, inside the box, will read the question, locate it in your magically large book, and you'll write the answer in Chinese script. And I'll receive it once you feed it through the \"output\" slot. From my perspective outside of this box, it sure looks like the person inside is fluent in both English and Chinese. In reality, you don't have to be fluent in either - you're just matching one pattern to another pattern. In essence, this is what a computer does... and the bigger the translation book, the closer the computer looks to true AI. But the question you're asking is \"Could that computer ever *learn* Chinese? Or is it always just matching an input to an output out of a very, very, very large book of I/O's like our Chinese book?\" And it's a really difficult question to answer. The link I shared has a few opinions on it, but since we aren't really certain we can agree on what \"consciousness\" is, it's pretty tough to determine when an artificial intelligence could be called \"conscious.\""
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5x6uma | What determines the noise or visual pattern of TV static? | i was wondering this for quite a while, and i just want to know what makes TV static look and sound the way it does. is there anything that makes some bits white and others black? Same for radio static | Technology | explainlikeimfive | {
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"For the most part, it's stray electromagnetic noise, with about 1% being background microwave radiation. As for why the picture is only white or black, it has to do with how your receiver interprets those signals. Most television receivers have automatic gain control, so the input to the TV is always at a proper 'loudness'. When you see static, that's because there's no actual signal, and what else is there is really weak, but the automatic gain control doesn't know what's a signal and what isn't, so it amplifies whatever is there. The rest of the receiver, or the TV itself, also doesn't really know that what it's getting isn't a signal, and just tries to display it as best it can. The reason you only have bits of black and white and not any other colors has to do with how color is encoded into the signal. Back when television first became a thing, they could only display black and white. So the signal was encoded such that a 'high' level was white, and a 'low' level was black. When color was coming onto the scene, they didn't want to create a whole new standard and leave out the people who still didn't have color TVs, so they made it so that a color signal still had the same brightness level as black and white encoding, but also a quickly vibrating signal overlaid on it that color TVs could interpret as color, but black and white TVs weren't bothered by. This quick vibration only works at one specific frequency though, and electromagnetic noise can't trick the color decoding on TVs. What does work still is the 'high' and 'low' level sensing for a black and white signal, so you get the white and black static field on the display. As for radio, it's really the same reason as TVs, since analog TVs used to primarily get their signal from radio antennas, just at different frequencies.",
"All I can tell you a about static is that it's background radiation. I think in the '60s or '70s, these guys with a microwave scanner kept getting background noise and couldn't figure out what it was. They were looking for microwave radiation to make the Big Bang Theory a *theory* and not just an idea. At the same time, some other scientists were also trying to find background radiation. Eventually they got in touch and as t turns out, static (radio for sure) is theorized to be leftover radiation from the Big Bang. I know it doesn't answer you're question, but there's some context. Check Scishow Space and Bill Bryson's A Brief History of Nearly Everything for more information and better details."
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5x9g4f | How are credit card numbers validated? | Technology | explainlikeimfive | {
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"The first step in that the first few digits will be checked to correspond to a certain company. For example an Amex card will start with 34 or 37 and will be 15 digits long. Where as a Visa will start with a 4 then the next 3 digits describe the issuer and card type, it will also be 13, 16 or 19 digits long. If it then passes this then a Luhn algorithm will be checked. You take every second digit(except the very last one) and double them. Any double digit numbers are added together to get a single digit. You then sum these numbers up with the other digits and get one whole number. The modulus 10 of this number should be 0 if it isn't then one or more digits is wrong. So if you have 80 then the modulus 10 is 0 so it works whereas if you had 23 then the modulus 10 is 3 and you know there's an error. Now that you have an entry that you know is accurate the machine then contacts the bank to verify it with the CVV and expiry date to authorise the purchase."
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5x9ge2 | - Ryzen Cpu's? What's all the fuss about? | I get that they're AMDs new CPU's, but there seems to be a damn lot of fuss being made. Have AMD changed the game or something? Or same old same old? | Technology | explainlikeimfive | {
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"Long story short: For roughly the last 10 years, Intel have dominated the performance CPU market. For the last 5 years, Intel have dominated it to such a degree that they've practically stopped trying to push performance forward in any meaningful way, with gains of little more than 20% in their last five generations of desktop processors. As workloads have increased, people have become more and more unhappy with Intel's reluctance to push performance forwards, and their high prices. Intel have gotten away with coasting for so long because AMD (the only other desktop CPU manufacturer left) haven't offered any sort of competition. With Ryzen, AMD promised to change that. As we learned yesterday when the reviews embargo lifted, AMD were only partially successful - they've released a series of new CPUs that can offer, depending on use, the highest level of processing power of any CPU on the market, at less than half the cost of the equivalent Intel chip. That's brilliant. What's not so brilliant is that Ryzen isn't particularly efficient where it comes to the performance loads placed on a CPU by gaming, which has lead to a bit of a backlash from the gamer community. Ryzen's performance *will* improve over the coming months and years, as microcode tweaks fix certain issues with the chips, and as software developers come to optimize their code for AMD's architecture, where before they had only optimized for Intel's. As to whether it's a game-changer or not, it absolutely is. There is now, for the first time in 5 years, actual competition in the processor market. That's going to lower prices and push performance forward for everyone.",
"They have re-entered the game in a splash. Half the price for equal or in certain scenarios better performance of their Intel counterpart. Basically all the amd fanboys have their jimmies in the air because there is a *viable* alternative now. It's exciting. Even if you don't like them, competition is going to be good for us."
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5x9q6l | Why does the last 15% of my phone battery life disappear so much faster? | When my phone gets to the last %, normally around 15%, it visibally starts to fall! It only lasts a few minutes! | Technology | explainlikeimfive | {
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"So generally there are a few causes to that. 1. power = voltage * amperage, The lower cell is charged the lower the output voltage will be, li-pols range is 4.2V to around 3.0V, so between 100% and 5% there will be 1.4 times as much drain because the amperage will have to increase to sustain power draw. 2. Resistance inside the cells is different depending on how charged it is, its connected to the cells chemistry. 3. After a few hundred charging cycles the battery is starting to break down, and it's capacity is getting smaller, its possible that the phone sensor doesnt pick it up and guesses that there is more juice in the cells than its actually there. The phone is showing 15% but for real you are left with like 5% battery."
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5xcjnc | What exactly is the difference between "cores" and "threads" on a CPU? | I see some CPUs have cores equal to threads, but some have twice as many threads as cores. What are threads here? | Technology | explainlikeimfive | {
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"In a CPU core, various types of calculations are actually done in physically different parts of the CPU. For example, integer arithmetic runs on a different part of the silicon than floating point (decimal) arithmetic. A CPU with multiple threads takes advantage of this by letting two programs run on a single CPU core at the same time as long as both programs don't need to do the same type of instruction at the same time. This is why running two threads on a single core isn't usually a doubling of performance, because if both programs are trying to do integer arithmetic at the same time for example, they need to wait for each other. To make it more ELI5, imagine a CPU core is a kitchen. A program that wants to run is a recipe that needs to be prepared. The various parts of a CPU core are the various areas of the kitchen. You only have 1 oven, 1 stove, 1 cutting board, etc. Adding additional cores is like adding an entire extra kitchen. Adding CPU threads to a core is like adding another chef to the kitchen. Sure, you can now cook multiple dishes in that kitchen now, but only as long as they don't both want the oven at the same time. EDIT: As an anecdote, I used to do a lot of work with [POV-Ray]( URL_0 ), a free open-source 3D rendering app. In my 4-core (8 thread) i7-3770, if I tell POV-Ray to only run with 4 threads so it only uses 1 thread in each core, then run a full 8 threads, it only gains about a 10% speed increase because the extreme majority of POV-Ray's work is floating point math, so it can't effectively take advantage of a multi-threaded CPU core."
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5xdrp0 | Why do most online games feature beta testing phases, but offline games are released untested by the public? | Technology | explainlikeimfive | {
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"An online game needs to be exceedingly \"balanced\" in order to be successful. That means that a knight, a wizard, and a thief need to be all about as powerful as the other guy, else everyone who wants to play a knight will be disappointed if he's forced to play a wizard in order to be accepted into group content. Beta testing offers thousands if not millions of data points for the development team to study in order to balance the game properly. Even more so if the game offers a player versus player mode. Sure it's fun to be super overpowered in a single-player game, but in multiplayer games, one person having heaps of fun means that there's probably another 10 miserable ones. Server stress tests. When you release an online game, you are committing a ton of computing power from your own company to running the game. During beta testing, you get to see how do your servers react to a multitude of players and connections, something you can't really simulate without the testers. If there are server issues, you get to fix those ahead of release instead of having disappointed customers on day one. Also, an online game makes a lot of its revenue from continued subscriptions or \"item\" sales. Single player games get bought when they get released and their popularity dies down after that. By releasing an almost finished product as a \"beta test\", you get players to demo your game for free - so once the game is released for real, they will be even more willing to buy it and subscribe to it for a long time.",
"If your game design calls for a single player (as \"offline games\" do), you can hire X testers, put them each through the single-player experience, and determine if your game is bug-free, stable, fun, etc... If your game design calls is for a \"massively multiplayer\" game (eg: expect to support X thousand simultaneous players without the frame rates dropping to power point speed, for instance), then you probably can't afford to hire X thousand players times K number of permutations you need to test. Plus, there's all the \"marketing\" aspect of involving the community of potential players early, generating hype, to get funding in the early stages, etc etc...",
"The biggest reason for beta-testning is not to test the game, but the servers. Renting servers costs a lot, so you really want to make sure you only use the absolute minimum.",
"Open betas before a release are generally used to stress test the servers and try to make sure that the servers are able to handle the number of users. Plus since they are free and limited it adds to marketing"
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5xe6tv | The concept of abstraction in computer science | What is it? Why should I know it? How is it used? Thanks! | Technology | explainlikeimfive | {
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"Abstraction is the idea that the user of some function or method doesn't need to understand how the function works, the only thing they need to know is how to operate it (i.e. the input and output). Abstraction is incredibly important for building complex programs or circuits because each level of abstraction brings an increased amount of overall complexity and there comes a certain point when it becomes unreasonable to necessitate that the user understand all the minute details of some function. Functions that have their inner workings hidden are often called \"black boxes.\" For all intents and purposes, the user just considers it to be this magic box where you put something in and you get something out. Sometimes it's actually useful to understand on some level how the black box works because you can have two black boxes that do the same thing in different ways, and depending on the type of input you're giving it, you might want to choose one over the other due to efficiency concerns. Abstraction isn't just something computer scientists use, it's used for computer circuits, networks, weather models, scientific theories, psychology, economics, business etc. You use abstraction every time you drive your car. You understand the inputs to the machine, your gas pedal to go faster, your brake to go slower, your gear shift to park, go in reverse or go forward, your steering wheel to change direction. Most people don't really understand how cars work on a reductionist level, they just understand the high level idea of what input does what. I'll give a less 5 year old explanation: consider computer circuits. The fundamental unit of the computer is the transistor. A transistor is simply a gate that either allows current to flow or turns that current off. If you put a few of these transistors together in certain configurations, you can create logical gates like AND, OR, NOR, XNOR, XAND, NAND etc (Google these to see what they do). Using these gates, you can then build small circuits that output certain values given certain inputs. You can also make circuits that store information (these are called flip flops). You can make circuits using these flip flops and logic to create circuits that can add two numbers, that can make RAM, you can make circuits that display an image on a screen, and all the other things that computers can do. Each level of abstraction: * the transistor (which is itself an abstraction of quantum physics) * The logic gate (you don't have to worry about how the transistors are configured to make the gate) * The logic circuit (you don't have to worry about how the logic gates are configured) * The functional circuit like an adder, a CPU, a GPU (you *generally* don't need to worry about exactly how all the individual components are configured to make the complex circuit) Using abstraction, we are able to create programs and circuits and models of soaring complexity.",
"Say I make two classes with direct references to each other. This makes them tightly coupled, hindering them to be used individually elsewhere in the code. This often leads to the having to rewrite parts of code in other areas and making it a nightmare when you have to update the code a year later and only remember to update in once place. It also makes it difficult to test either class by itself, so debugging means effectively treating the two as a larger, more complex class. So the solution to this problem is to use abstraction to keep classes decoupled. You make an interface or abstract class that provides or describes some base functionality, and then anything implementing those can be used in operations throughout the code. This allows easier modification and testing, as you can add and remove classes without having to update existing code that operates on the abstracted level. And you can test the generic-handling code without relying on specific implementations of various classes. A basic example is sorting things. The sorting algorithm doesn't care what the things actually are, just what the outcome is when you compare two of them to each other. So making that an interface with some compare function, you can now implement a sorting algorithm that works with anything that implements that interface. Or perhaps message parsing. If you know your messages all build off an abstract class telling what kind of message they are and how big they are, the parser can look at this abstract level to obtain the relevant data to pass the message on to the appropriate parsing function. Or even further, perhaps the abstract class also has virtual methods to parse data, so now a generic message handler can tell the message to parse, knowing that all implementations know how to do that."
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5xhqrx | What is a "Duck" in Computer Programming? | Or "Type Safety" for that matter. | Technology | explainlikeimfive | {
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"'Type safety' refers to how much a language checks the data types of variables. For example, checking that you aren't trying to perform math operations on strings of text. Some operators work differently on different data types. For example, 'x + y' might mean 'add the numbers x and y together', or it might mean 'concatenate the strings x and y'. In a duck-typed language, I could have a function which takes x and y and returns x + y. The language only checks at runtime whether the operator '+' actually works with x and y. The term 'duck-typing' is a reference to the phrase: \"If it walks like a duck, and quacks like a duck, it's a duck\" - the idea that you can have two different types of data which both can do the same things, so you can treat them identically.",
"There is a concept called \"duck typing\". Its name is a reference to the truism \"if it walks like a duck and quacks like a duck, it's a duck\". In a duck typed language, the key question is \"can I perform operator Y on object P and Q?\" Two objects for which both implement operator Y are said to be \"ducks\". IMO this is not a useful nomenclature. If two objects implement the same set of methods, they have the same *interface*."
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5xi0uh | How do games know if its been pirated or not? How do game developers code in a repercussion to pirating a game? | Technology | explainlikeimfive | {
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"It's possible for a game to connect to an activation server and check the key used to activate the game, and if it is blacklisted on the server, it may be a pirated copy. Most cracks will try to disable this. In some notable cases, the developer released a cracked copy of the game intentionally, but with a few subtle modifications that would ruin the experience for pirated copies.",
"Do you remember the days when you used to get a game or piece of software with a key that didn't require any form of online check. This software would have used a database built into the software itself to check against the known valid hashes of the key and thus determine if the software license was genuine. These days that is all but gone. Because the database of every possible key combination and it's hash was included in the software, it's so easy for crackers to determine all the valid hashes and write a piece of software called a key generator nobody bothers with it any more. A newer technique is to use only predefined hashes of a game key that are placed into a database the game developer controls. The software then checks it's hash to see if it is genuine via the internet. This is a tad more secure because crackers cannot interrogate the key database (Or rather to do so would take a long, long time), and the game developer only has to input hashes for the quantity of games it actually releases, so instead of there having to be every possible combination of hash in the database, there only has to be as many as there are copies of the game. This makes it a lot harder to break down the hashing mechanism. Better yet, the developer can revoke a hash and therefore render a game unplayable. Crackers get around this by basically cracking the game so it does not interrogate the game developers servers, instead it gets confused into interrogating a server that actually runs on your own computer and basically says \"Yes this is a valid key\" to anything the pirated software sends to it to determine if the key is real. Because it believes the fake server to be the real game developers licensing server, it authorises the game or piece of software. This is how many software products like Adobe Cloud and Microsoft Windows are cracked these days. There is little the software developers can do to prevent this, but they can make it much more difficult for you if you go down this route. By tying a hash to a second or even third piece of information like an online account (A.K.A Steam) and a fingerprint of your hardware, they can insure any use of their services for things like online play, downloadable content and such like cannot be used by cracked copies of the game. Now there are mechanisms in place to identify whether a game is cracked or not and allow the game to respond to that. One way used to be deliberate errors on CD/DVD's that where not there on ripped games. In these days of digital downloads, one common method is a logic gate where the game has to request instructions on how to proceed from a remote server. If it can't get that information, it assumes your offline the first few times, but after a while it stops assuming and starts saying \"This is probably pirated\" and it can respond accordingly, from shutting down and requiring you to authenticate again, or far more creative solutions like [some of these game developers]( URL_0 ) have utilised.",
"Copyprotection is very complex. To answer the question in short: Assume the game has a copy-protection routine, in the older days that was tied to \"Please read the tenth word on page 3 of the handbook\". As copy machines (physical) were expensive, it was reasonable that whoever (teenager?) copied the game, but not the handbook (\"back then\", we manually transscripted handbooks for this reason! Ha!). Later the copyprotection tied into some physical aspect of the game, as certain serials on the CD and then the game required the disc to be present. That went well as long as CD burners were expensive and CDs as well. If you had to spend 2000 or 200 $ on the burner and 20 or 10 $ (or whatever) on an empty CD, well... you did not really have one. The game was protected. With the rise of the burners we saw \"bad sectors\" or so on the CDs, which the burners could not copy, but the industrial presses that made the CDs could very well create. The game then picked those up. Now to the question: Assume the game is copy-protected which prevents it from running without certain \"features\" (be it those bad sectors or...). It now looked for those and if they were gone, the game knew it was pirated (with a certain probability). During a horrible time there were copy-protection makers that made protections that went very deep in the systems and did nasty stuff with the CD drivers back on the OS level to prevent tinkering. Today, it is again pretty simple: The games usually require some sort of registration and an online connection..",
"One of the more direct methods is to require a serial number. All the serial numbers have a special, secret mathematical property, and the code checks to see if it matches. Or it connects back to the company and see if the serial number is on the list of legitimately purchased games, and hasn't been used before.",
"The safest way to counter pirating is to require that the user has an online account with the company used to login to the game. Then devs can really make it difficult or even impossible to pirate it. However throughout gaming history the usage of serial keys and checking whether they are valid and if they are blacklisted or not has been the most common approach."
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5xiz6j | Why did TVs go from squares to rectangles? | Technology | explainlikeimfive | {
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"There's a video [here]( URL_0 ) that goes through the whole history. To summarize: movies started using the 4:3 (not quite square) aspect ratio because a guy working in Thomas Edison's lab picked it seemingly arbitrarily. TVs picked the same ratio so they could show movies. Then TVs became popular and movie theaters wanted to do something new to get people in to watch. Using a much wider screen was one of the gimmicks they settled on. So now in order to view movies on a TV, you needed to either shrink the picture (and end up with giant black bars at the top and bottom) or cut the sides off the picture in order for it to fit. So, the TV companies decided to make their screens wider too. The current TV format is actually halfway between the old TV ratio and the movie ratio, so that it's equally OK at displaying both movies and old TV shows.",
"To better represent what's on screen and to match up with movie theaters. When movies were shown on TV, they'd have to be edited, either by simply cropping out the edge of the film, or by what's called \"Pan & Scan\", where they'd tried to select the \"best\" portion of a movie to show and then crop out everything else. (I'm simplifying it quite a bit, I only half understand it myself) These methods could result in you completely missing certain parts of the movie. For instance, in the movie The Abyss, there's a REALLY great scene where you finally meet the alien, and it's this amazing liquid creature with a flowing water like body. Except, when it was edited for the 4:3 screen, they chopped off everything except for it's face... you don't get to see the body at all. A 16:9/10 ratio allows TV's to show exactly what is shown in the movie, and allows TV Shows to get wider shots, and look prettier."
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5xjilp | Why is the Louis Vuitton's Youtube channel registered as an afghan channel | Technology | explainlikeimfive | {
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"Afghanistan is alphabetically the first country, so if the registration form included a dropdown menu for the country, that's what would appear by default. My guess is whoever created the channel just didn't set the country, and was left with the default."
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5xl6qx | Exactly how does an MRI work? | Technology | explainlikeimfive | {
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"Your body has 7*10^27 hrdrogen atoms which are spinning on their axes that are all pointing in random directions. When you are placed in a MRI machine, the magnetic field aligns a small majority of those atoms' axes with the direction of the magnetic field. Then, using three big electromagnets called gradients, it slightly alters the rotation speed and phase of these atoms (the gradients pulsing are what creates the loud noises you hear during a scan). It then pulses RF energy causing the atoms aligned with the field to flip 90 degrees so they are perpendicular to the field and are in a high energy state. As the atoms relax and realign with the main magnetic field, they release the energy they gained from the RF pulse. The MRI machine picks up this energy and can pinpoint the locations of the atoms, due to them spinning at different speeds and phases, and reconstructs an image of the tissues in which the hydrogen atoms reside. This is a very basic explanation of the physics involved. For a more in depth explanation, although still fairly basic, check out this awesome youtube video I watched when I first started working with MRI machines. [MRI: Basic Physics & a Brief History]( URL_0 )"
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5xlctp | Why is the performance of a graphics card tied so heavily to the drivers, to the point that a bad driver can cause a sudden drop in performance? | Technology | explainlikeimfive | {
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"Yo don't write code to be executed on the graphics card directly. Yo write code in a API like DirectX or OpenGL that the driver converts or thing that are executed on the graphics card. So the performance depends on good the driver is. The reason for not writing directly to the graphics card is that then you would have to write different code for each new model of graphics card for it to work and have maximum performance. It is simpler that the manufacturer writes the driver for their card once. The not writing directly is not quite true because of shaders and OpenCL etc but that is not a ELI5 answer"
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5xm77q | Why do we continue to make nuclear weapons, despite a seemingly global hatred for them? | Technology | explainlikeimfive | {
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"There is an acronym called m.a. d. Mutually assured destruction. While we all live in a word where we don't want nuclear weapons they are still here and because of that if one country wants to attack another country they know the other country can match there nukes.",
"Personally I'd sum it up to paranoia and human selfishness. Country A won't disarm because Country B won't disarm, because Country A won't disarm. And then Country C looks at Countries A and B and feels threatened by them, so it builds nukes to deter possible (but imaginary) attacks from A and B. It's a vicious cycle that will never end unless every country disarms at the exact same time, which is impossible because they'll never agree to do it."
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5xm9q8 | How do hacking attacks compromise user accounts if passwords are stored as hashed values? | Unless you could reverse the hash back into the password, wouldn't the password be safe? | Technology | explainlikeimfive | {
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"It depends on which hashing process was used, and how strong your password is. Your comment is right, by definition you cannot reverse a hashed password. That is what a hash is. Your password is fed into a one way grinder (\"hashing algorithm\") and transformed into gibberish. This means if anyone is able to get access to your PC they don't have your passwords, just some gibberish. The problem is this gibberish is the same gibbersih every time you enter the password into the grinder (\"hashing algorithm\") So if for example your password was \"password\" and you used the Sha1 hashing algorithm this would be turned into \"5baa61e4c9b93f3f0682250b6cf8331b7ee68fd8\" Every time you enter password it will always return \"5baa61e4c9b93f3f0682250b6cf8331b7ee68fd8\" So a person who has access to your hash could simply guess some passwords, like \"12345\" or \"iloveyou\" or \"password\" and enter them into the algorithm, and if the output matched they would have worked out what your password is. There are a fair number of freely available tools to automate this, which will try hundreds and thousands of guesses a second, trying to just \"brute force\" their way to your password. For example, one commonly used by pen testers (professional, legal, hackers) is \"john the ripper\": URL_0 Any password can be \"cracked\" this way, it just depends on how long it will take, seconds, hours, months or years. The longer your password and the better the hashing algorithm, the longer it will take and the better your security is. Remember, there is never such a thing as being 100% secure, you just want to make sure breaking in to your things is not worth the effort that it will take.",
"It depends on how long it takes to hash a password, and on how many tries it would take to guess your password. A bad hashing algorithm(like MD5) means people can brute force the password, just checking every possible password(especially with GPU based password crackers). A better hashing algorithm just increases the amount of time it takes to do this kind of attack. But assuming you have a long password, the bigger danger is a dictionary attack, which are really good at guessing the types of modifications people make to their passwords in order to meet typical password requirements(like capitalize the first or last letter, stick a number in front or after words, etc). Here's a good video on the topic: URL_0"
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5xmjd9 | Why does water fry electronics? | Technology | explainlikeimfive | {
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"Electronics have defined paths through which electricity has to flow. These paths are designed such that there is always a regulated flow of electrons from low potential to high potential. This flow also generates heat due to resistance and electrons colliding into each other. Water is usually not pure and conducts electricity. When it is spilled over these paths, it creates short cuts for electrons to flow unregulated. This creates a lot of heat and causes the components to melt. This damages the electronics and \"fries\" them.",
"Despite popular culture, water (pure distilled water) is an excellent insulator. It's the impurities in water that make it conductive. [Link]( URL_0 ) Impure water fries electronics because paths are formed that were not supposed to be formed. A fatal path called a short can be formed. This is usually defined as the power supply being connected directly to ground. Imagine if you took a piece of wire and connected it to both ends of a battery, it would heat up or even blow up. That's because you've essentially shorted it. TL;DR: Higher than normal power is delivered to areas of the circuitry which cannot handle that power. This results in damaged components."
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5xmyzl | What is Facebook's rationale for having my friend's comments on strangers pages show up on my feed? | I understand Facebook does many things to gather data/increase monetization. But I don't understand how showing friend F comments on their friend G's (a stranger to me) page, on my feed, gathers data/increases monetization for Facebook. And on my end, I can't remember ever engaging with one of these conversations because I don't know G so I wouldn't comment on G's page. So if it doesn't appear to help Facebook or me, what is Facebook's rationale for showing these comments? | Technology | explainlikeimfive | {
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"They're hoping that you and G become friends. Either you know each other in real life but haven't become Facebook friends yet, or perhaps you haven't met but you join in the conversation and become friends.",
"Facebook makes money through targeted advertisements. If they have more information about you, your ad space is worth more. Facebook tracks how long each post is present on your screen, from which they can roughly estimate how long you look at a post. By showing a friend of a friend's post (or comment) they can establish your closeness to this mutual friend as well as other variables in the post (location, product mentions, etc). This is slightly more data rich than the average post they show you. They're not just doing this willy-nilly.",
"Number one goal of Facebook is giving you reasons to look at Facebook for longer durations and in greater frequency. They either have numbers (or are testing in hopes to get numbers) that suggest showing this stuff increases engagement in some way (time in app, time until next visit) more than not showing it. Why it increases usage is a separate question. And while interesting, Facebook doesn't necessarily need to know why. They just need to know that it does.",
"While it's true that the core reason Facebook shares lives and connects people is to make money, I'd like to instead address something I see underlying the question. I interpret your question as wondering why Facebook is making public a conversation that you observe or interpret to be private (or at the very least personal). The answer is that your friends are having a conversation in a public place. Your friends are opting to make this conversation public. It's true that Facebook thinks that this might be of some interest to you, and your friends do too. When we post on Facebook on someone's wall or comment on their posts, we do so in a public forum (not totally unlike Reddit or other forums and aggregates). Keep in mind that Facebook has a private message service where interactions are not shared with other parties. Once your buddies are willing to share their conversation out loud and in public, Facebook is more than willing to leverage it to engineer your attention. Others have pointed out that the more connections you have on FB the more likely you are to engage with the service. The more you engage, the more ads you see. edit: Just to add one more thing: to some degree by opting to have this conversation in public they are all but inviting others to join in. Or at the very least to observe. While your particular manners may preclude you from jumping in uninvited, I would say that those manners do not always extend to public forums... or ever to public forums.",
"I have no explanation, but will say that this specific feature is directly responsible for my decision to leave Facebook and move to other social media (IG and Reddit, specifically). I have an uncle who had no qualms about hopping into one of my friend's posts to start political arguments with me. It made me uncomfortable as all hell. When I found out I couldn't escape the problem, I deactivated. Best decision I've ever made.",
"I think there's another possibility that hasn't been addressed. so far. They're trying to make it more of a \"social space\" like Reddit. Two people start discussing a political or environmental issue, more people from various groups weigh in. There is dialogue and argument. People end up spending more time talking to strangers and sharing opinions. This behavior then redefines how some people will use facebook in the future. Keeping people engaged and participating in conversations beyond birthday wishes and comments on pictures means that fb also gets more advertising time with you, but other people have covered that aspect of it well enough."
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5xn0v3 | Why do many installers tell you that it's "recommended that you close all other applications"? | Technology | explainlikeimfive | {
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"The operating system and execution environment of most modern operating systems have \"shared libraries\" that are directly mapped into memory. This means that the file(s) that do various things -- like run your display or control the audio output or whatever -- become part of the way a program runs. So those files that provide functionality to programs -- \"DLLs\" for windows, \"shared objects\" for linux, and so on -- can not be changed while the program is using them. So in the way that you can't change the breaks of a moving car, or replace the belts and spark plugs of a running engine, you really could't (safely) change key parts of the operating system while they are in use. In the case of windows in particular, the most central libraries and tidbits are known to the installer. If a program needs to replace one of these core componenents then it can put the file aside and then add the file's name to a list of files that need to be moved/copied/deleted next time the system is booted. This deferred install step is why sometimes, but only _sometimes_, when you install something (particularly new hardware) it will tell you that the system needs to be rebooted. But there are _lots_ of component libraries that an application developer _might_ want to use. These are completely optional parts. Like lets say I've made a really neat widget to let you pick colors. You use it for your Foo application. But I also sold it to my buddy Bob for his Bar application. Bar is using version 4. Your Foo application needs version 5. So you want to replace the BitOBearsColorChooser.DLL file with the newer version. If Bar is running when someone tries to install Foo, then Foo will not be able to upgrade the file and the Foo won't work correctly. It's impossible to _know_, for sure, that none of the running applications will have this sort of conflict until you try to do the install. Lets say BitOBearsColorChooser.DLL is the last file in your application installation. The user has been watching the DVD spin for twenty minutes as your application tries to install itself. Then it _fails_ because Bar is running. Then it spends five minutes cleaning up (deleting) all the files it just tried to installed. The user is going to be _pissed_. So to prevent that sort of strife you take the simple measure of \"strongly suggesting\" that the user no be running other programs while installing your application. --- There are other, lesser issues. If the installer has to decompress some files (which uses a lot of CPU/processing power) or needs to do some memory intensive work... and you happen to also be running something CPU and memory intensive... then the two demands on the system can make both the program and the installer take _forever_. That's another headache from an angry customer. Another issue is that if your installer is writing the application files to the disk while some applicatoin is also writing to the disk, the files can get interleaved (fragmented) and that will lead to both the data from the running application, and the code files of your newly installed application, to _suck_ (technical term, that) because they are spread all over the disk as fragments instead of being big chunks that can be read all at once. So if you run one application while installing another, your new application might take extra long to start until/unless you defragment your hard drive. So it's all about avoiding conflicts that can lead to unhappy customers.",
"When you run a program more goes into that program than the program itself. These are called libraries and contain common code that do various things on your system. In fact when you look at a loading screen you an see some of these being \"advertised\" to you, such as a graphics library. When the program installs it need to change those libraries. It cannot replace open files. This is done for file security. So if you try to install a program with another program that has libraries or other files open the install will fail. When that happens you have a partially installed program, which is now a much harder problem to address.",
"It's likely due to a DLL that is common across other applications. If the program I am trying to install requires a newer version of a DLL and you leave a program open that is using that older DLL I will not be ableto replace it because the DLL is in use. If it is a DLL created by the software company they can check that there software is not running. If it is a DLL by a third party the DLL could be used by any program.",
"Because when installing many programs, the registry often has to be accessed and changed. The registry is basically tells the OS how to access a program, what settings to use, etc. If you have applications open that are accessing the registry at the same time, this can cause problems with your new program installing."
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5xnaas | What algorithms do programmers use to produce "randomness" | I know that it is impossible to make something truly random, but what algorithms do most people use to do so? | Technology | explainlikeimfive | {
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"There are different possibilities: There are so called \"hash functions\". You put a number in, you get a number out. The important thing: if you put two close values in, you get two vastly different outputs. If you use now the system time, you can get pseudo-random numbers. Another way is that your Operating System helps you. A computer can \"gather\" randomness by user input (what does the user type? how fast? how does he move the mouse?) and hard drives (how long does it take to read?). This is much better randomness, as it can't be predicted by software how you type. Then, when the randomness is gathered, the Operating System allows programs to extract random numbers.",
"Most programmers use the operating system-provided random number generating function. It is typically actually a pseudo-random number generator (PRNG), which means that it’s not _truly_ random—just made to look as close to one as possible. PRNGs are based on algorithms very very few people are actually interested in, usually made more random by adding some type of confounding ‘noise’—often things like whatever is happening on the computer at the time, which is generally unpredictable ahead of time. Think the mouse moving, or data packets moving back and forth the wifi. So as a very simplified illustration, you could imagine that an algorithm produces you the number 5. At the same time the mouse happens to move 4 pixels. You add 5 + 4, and then you apply another round of randomness on top of _that_. The final result would be very difficult to predict. It’s also possible to have a _true_ random number generator, but those will be based on more exotic technology like measuring radioactive decay. There are some services that (at least purport to) provide you with such true random numbers.",
"So, there a couple of goals for making a pseudo-random number generator: - Simplicity - Random-like The first one is important because you might want to generate a lot of random numbers very quickly. Because it cannot be truly random, usually it is more important to be very fast. The second one is important for more obvious reasons, but is a little hard to define. In short, it should be unpredictable enough that it looks like a statistically random output. There are a lot of very simple methods of doing this, for example the simplest method is just to loop through a pre-computed list of random numbers. A lot of random number generators are not good at making numbers random enough for encryption, but some are. These are usually less simple, but, obviously, more secure. There is another method of generating 'random' numbers, which is to get the user to provide it. Mouse movements and keystrokes can be taken and fed into an algorithm, which then creates a random number using that as an input. It has the advantage of being more unpredictable, but can also be a lot easier to manipulate, as well as being particularly slow."
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5xoacz | If child pornography possession is illegal, why hasn't Snap Inc's CEO gotten arrested? | Technology | explainlikeimfive | {
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"I am not a lawyer and not your lawyer and this is not legal advice. I used to work IT for a very large computer services / sales corporation where an employee had child porn on their system. I was the IT employee who discovered it. I had to preserve the evidence and eventually testify. Every child porn possession case I've read since then all center on the prosecution proving *intent* — that the person being tried for the crime, *intended* to be in possession of the child porn. Snap, Inc. does not intend to be in possession of child porn. They make at least an effort to inform their users to not break the law with their service. If they bothered to use end-to-end encryption of messages, there would be absolutely no question of prosecutability because they would have no way to understand the content.",
"That would be like arresting Apple or Microsoft CEOs for having a cloud service. Plus I'm pretty sure when you start using Snapchat you agree to a terms of service that prevents what you are suggesting.",
"It may not be written in the law, but I am certain there is a precedent of sorts that differentiates between private ownership and third party ownership. For example, if you keep stuff in a storage locker, the storage company becomes a third party owner. If you kept your locker full of illegal material, the owner of the company would not get in trouble. The same can apply with bank safety deposit boxes, the postal office, or any other institute that that holds someone else's possessions.",
"No because they are no facilitating it. They also are not looking at what people upload. When they do learn of this stuff they remove it. The CEO doesn't personally oversee everything and as long as it's not his policy to keep/promote child porn on the servers(or really any illegal content) then they can't be found at fault.",
"Section 230 of the communications decency act offers a lot of protections for a website operator with regards to content posted by users. You can read about it here: URL_0 In the case of Facebook, the objectionable content may be viewed by other parties depending on privacy settings, so reporting tools are made available to the user. In the case of Snapchat, the message is directed to individuals who aren't likely to report the content as objectionable.",
"I've been curious as to why no one suffers any consequences for underage girls who post nudes on their stories. Like the \"Cash me ousside girl\" posts nudes all the time. She's 13. Everyone knows about it, yet no one does anything about it. How can shit like that go on without the cops getting involved?",
"Same reason the UPS guy wouldn't get arrested for delivering it to your house. When you provide a service to transport goods or data for the general public, you are not required to scrutinize every item you carry, nor are you responsible for inadvertently transporting illegal items if someone misuses your service. In general, you can are only guilty of a crime if it can be shown you intended to break the law. If you unknowingly commit an otherwise illegal action, you are not guilty of a crime."
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5xovw6 | -Why won't ethanol work as an alternative fuel source? | Having a discussion with my dad the other day about solar and other alt energy and he says we should focus on ethanol, since it's renewable. Since I'm dumb, I really don't know why, but it seems like I've heard loads of smart people say that ethanol won't really work. But I've never really heard why. | Technology | explainlikeimfive | {
"a_id": [
"dejq8f6",
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"In the US, ethanol has two problems: * in part because Iowa votes very early in the presidential primary process, ethanol production from corn is subsidized...corn is a pretty terrible thing to make ethanol out of * making ethanol out of any food product destabilizes the market for food Brazil's national fleet runs largely on ethanol, which they make from the much more efficient sugar cane.",
"taking cost out of the equation ethenol works just fine. much of S America has been using it for years. many gas stations have both gas and eth pumps, and conversion kits for older cars are easy to install. the problem OUR industry faces is they are trying to use corn which is more expensive to grow, yields less then other sources and is intensive in its care. Other countries have been using sugarcane ethanol which is so abundant many have offered their surpluses to us in the past when we first initiated our desire to look into using it as fuel. which of course we refused because hey corn subsidies gotta be paid man. on the plus side ethanol burns really clean and provides a lot of power. many cases of old gunked up engines from years of gas fuels suddenly dying because the ethenol ends up cleaning and breaking down the carbon residue and then fouling up the engine with the crap too big to just exhaust.. 7000 combined Horse power of alcohol fueled madness : URL_0",
"ethanol doesn't magically appear out of thin air. you have to grow a plant to have the raw materials (sugar) to make ethanol from. the US, because of the corn farmers lobby, uses corn to make ethanol from. problem is...corn is a bad plant to use to make sugar from. it takes alot of water and alot of land to make corn. so that you can use it to make ethanol. a much better alternative is sugar cane and sugar beets, which brazil and cuba and venezuela grow and makes wonderful ethanol wtih. problem is farmers in the US don't want to grow those crops. they'd rather use their existing equipment that used to grow edible corn to grow ethanol corn."
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5xoy60 | how stealth operations really work since most depictions of silencers/suppressors aren't realistic | I've read/seen from different sources that silencers and suppressors on weapons don't actually "silence" gunfire, and shots are still quite loud. Since most depictions of stealth operations in videgames and movies depict teams quietly picking off hostiles while making their way through an area so they don't raise any alarm, how do these situations go in real life? | Technology | explainlikeimfive | {
"a_id": [
"dejqbh2"
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"text": [
"Suppressors dull the sound of a gunshot slightly, but more importantly they dull its ability to echo, and they dull the recognizable 'pop' or 'crack' of a gunshot, turning it into a some kind of 'chiss', 'tssk', or if you use subsonic rounds, 'chack'. These two features, less echoing and less recognizability, are used by stealth teams to dispose of one sector of enemies without the other sector knowing about it on-time and arriving to reinforce them. Suppressed weapons also make it harder to tell where the operator is, thus strike teams will quickly confuse their opponents as they wipe them out. Overall, movie depictions are naturally not that accurate. Stealth teams rely on coordinated strikes to remove groups of enemies without raising the alarm, and even then teams must have contingency plans in the rather likely case that someone radios one of the dead or sees the team moving through. Real stealth operations are extremely fast and fluid because every second not spent killing is a second someone sees what's going on. There will still be quite a bit of sound, but it will be concentrated and not drawn-out."
],
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13
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5xq2bg | How is /r/mildly interesting able to detech immediately that the image I've posted is a screenshot? | Technology | explainlikeimfive | {
"a_id": [
"dejzc62"
],
"text": [
"Can you see the top notification bar from your phone in the picture?"
],
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3
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5xqk92 | Why is the launch price for the Nintendo Switch nearly $100 more for Australian buyers? Even converting the US price to AUD equals $394 D: | Technology | explainlikeimfive | {
"a_id": [
"dek3hxa",
"dek4t9y",
"dek4mki"
],
"text": [
"There may be extra costs involved for Nintendo. The price of importing a product is more complex than simply the sales tax the consumer pays. Besides import duties there is some one-time safety/legal obstacles to be cleared and if they expect to sell fewer in Australia, the cost of meeting their laws/requirements is split across fewer devices than the cost of meeting America's requirements (even if America isn't necessarily \"cheaper\"). Also, it's priced to take advantage of what people can and will pay. Minimum wage in Australia is higher, so for some groups of people particularly towards the poorer end of the population, it's just as affordable or more affordable.",
"So the conversions 299 usd- 395 aud Meaning the prices are the same, but the us price does not include sales tax while the Australian price does. So it's actually cheaper in Australia",
"Same with everything in Australia. You're damned to pay more than almost anyone else, anywhere for anything. You can establish a U.S. 'virtual mailbox', and have your stuff re-shipped to you from there, if you like. Of course, that will cost more, too."
],
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5xqkxc | Why has air traffic control not been automated by computers? Wouldn't a computer be able to more accurately keep track and maintain all flight paths and altitudes? | Technology | explainlikeimfive | {
"a_id": [
"dekcjwm",
"dek3rsi",
"dek3pb6",
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"text": [
"Air traffic controllers think on the fly more than you would assume. They look at their radar scopes and plan each target to work with others by working their speed, altitude, and path. Computers could probably work out these, but then how would they relay that information to pilots? Another thing to think about is the vast number of VFR aircraft who are not on a flight plan going A to B. ATC is able to communicate with them, learn their intentions \"we saw something neat and would like to orbit here for 5 minutes\", and help them see and avoid other aircraft. The fact that they are humans who you can talk to is tremendously helpful in emergencies as well. If I'm fighting a sick airplane I might not have the time or focus to find the nearest suitable airport, get weather information and important notices, and plan a descent. A controller watching over me sure can though.",
"All aviation-related technology is tightly regulated and goes through an immense amount of testing and consideration before use. All of the obstacles we have around self-driving cars-- \"whose fault is it if it crashes\", \"how do we know it's safe enough before letting it on the road\", \"do you still need a licensed driver\", etc-- are 10x more problematic in the sky. It isn't necessarily harder to automate, but is harder to declare \"officially safe enough\".",
"In a way, air traffic control is computerized and automated with alerts, but you always need a human that can think critically in certain situations, like when an aircraft has an emergency situation.",
"There is also a requirement for hightly efficient algorithms to do this on large scale, which as of now are not available",
"Main reason: Strange situations happen. While humans can fuck up when confronted by something unexpected, they usually fucks up in a reasonable way. Computers, on the other hand, has no common sense at all, so they can fuck up really, really badly."
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5xtl6t | Being a millennial who has been raised around screens of all types; how -realistically- have I been affected? | Technology | explainlikeimfive | {
"a_id": [
"dekq5le",
"deksz7m",
"dektl7i",
"dekqnls"
],
"text": [
"By screens? As in LCD displays? As a millennial you are probably safe. Us old people who were raised around CRT TVs and displays have more to worry about. LCD displays are pretty safe as far as radition and other harmful effects are concerned.",
"OP I believe a better phrasing of your question would be \"Being a millennial who has been raised with access to technology such as TV, computers and smartphones, how has my cognitive and physiological development been affected by these environmental factors?\" Correct me if I'm wrong, though. If that is what you meant, perhaps some other people can weigh in.",
"Probably no more than the generation of lawyers, doctors, and teachers in the 70s and 80s who watched TV non-stop. Seriously, pediatricians these days are WAY too alarmist and need to stop doling out advice until they have measurable proof, not conjecture/speculation based on anecdote and public perception. /rant",
"\"Screens\"? There are basically two different types of screen, CRT and LCD (OLED I'm making a subset). A CRT is a \"cathode ray tube\" which uses an \"electron gun\" to spray electrons from the back of a vacuum tube toward a target which is the front of the screen. Electromagnets are used to create a narrow beam which is swept back and forth across the inside of the screen very rapidly, causing a phosphorescent coating to glow. Separated into a grid with differently colored filters over tiny spots, this can be used to form an image. You will recognize these devices as being bulky and heavy with slightly curved glass screen fronts. They can glow and get a small amount of static electricity on the surface of the glass but are otherwise harmless. The other kind is an LCD screen which is \"liquid-crystal display\". There is a white backlight to these screens, often spread across the entire screen by plastic sheets lit from the side. This white backlight is blocked by tiny crystals in tiny cells filled with fluid. Those crystals block light in one orientation and allow it through in another, and can be aligned one way or another within their tiny cells with an electric field. This is used to make an image. These displays can be recognized as they are thin and light, but can show weird colors at sharp viewing angles, and can never get completely black in the dark (A CRT can just turn off the beam but an LCD always has a backlight which isn't completely blocked by the crystals). An OLED display is very similar to this except each cell or pixel is an individual LED light source which turns on and off. LCD/OLED displays just put out light and are completely harmless to the user. The mere existence of these screens has effectively zero health impacts on the users."
],
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5xtvec | Why are "Pro" cameras so big/heavy | I've got a relatively nice Canon mirror-less camera. What makes a "pro" camera like the Canon 5D so big/heavy. The sensor is obviously a little bit bigger and there's a few more dedicated buttons, but it doesn't seem like there should be that many more things inside to justify the size/weight difference. | Technology | explainlikeimfive | {
"a_id": [
"dekt7bx"
],
"text": [
"Presuming both cameras are SLRs there are still several things that add weight: * larger more powerful moters (for cameras that support in body rather than on lens focusing) and to operate the reflex mirror much more rapidly. * large pentaprisms rather than penta mirrors (internal reflections in prisms reflect more light than mirrors) but prisms are a large chunk of glass). 5 thin glass mirrors are considerably lighter. As you note, pro cameras have a larger sensor, which frequently means a larger viewfinder (so more glass throughout the viewfinder's lenses) to go with the larger sensor. * a full metal body rather than plastic. * pro cameras often have a larger heavier battery that allows more shots per battery charge"
],
"score": [
11
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5xu3wi | How do the fingerprint sensors in modern smartphones work? | I am constantly amazed by how quickly and reliably the fingerprint sensor on my phone works. I'm wondering what kind of technology is responsible for the accuracy of fingerprint scanning. | Technology | explainlikeimfive | {
"a_id": [
"dekwwo9"
],
"text": [
"Optical readers take a picture of your fingerprint with a digital camera. Apple chose a capacitance reader, which is far more interesting. Touch ID uses a capacitance sensor to detect small differences in electrical conductivity on the surface of your finger."
],
"score": [
15
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5xu4t9 | How does Navigation in Space work? | Technology | explainlikeimfive | {
"a_id": [
"dekwlif"
],
"text": [
"Using a triangle metod.. You send a signal to nearest station or satelite(but their position must be know), and you get resposnse after some time. Repeat that with three stations(satelites).. Using a simple formula v=s/t.. you get three diameters and a place they intersect is the place you are... Repeat that process and you are familiar with path and position."
],
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3
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|
5xuutd | Why are PC-tune up programs considered a scam by some people? | Technology | explainlikeimfive | {
"a_id": [
"del1neq",
"del1hrp",
"del7qd8"
],
"text": [
"They are deserving of being suspect as they can't, by definition, fix the problem. So then what are they doing? And we're going to explore a couple important questions: What do these programs suggest they can do that, say, Microsoft, doesn't know about their own software? Or Google? Who are these people? Do they think they know better than the top talent hired into some of the most knowledgeable and technically competent companies? --- The problem is several fold. Especially in the Microsoft world, their software gets bloated with patches, because to their credit, they maintain astounding backwards compatibility. The bug fix usually comes with additional runtime logic that comes with a cost, as does the compatibility layers that cause many levels of indirection. Additionally, with more powerful computing, there are more powerful features that tax performance or, frankly (and my professional opinion as a software developer), sloppy code that performs \"good enough\", that in aggregate is non-performant, but consumers are quite tolerant these days. There are also huge data sets cached in memory for all sorts of crap, and as your memory usage grows, that much more has to be swapped to disk - you're, and really I mean your operating system, is keeping essentially useless caches up to date, wasting time and performance. These shitty little programs flush these caches through existing interfaces, which you can already do yourself, or are handled automatically and as necessary by the owning programs, which is honestly the way it should be. These flushes have no impact on performance. It doesn't matter how much data or how many programs you have installed on your disk. Effectively, if you disconnected your hard drive after you system loaded, your performance would still be shit. People talk about swap and disk space and fragmentation and caching like they have any idea what they're talking about regarding performance and they're mostly wrong. At the very least, when you're diagnosing performance problems, stop thinking about your hard drive and what's on it, that's not where the problem is. It's all about what you're doing with what's in memory and how your runtime is tuned for performance. And don't run \"free\" software that promises to do what it can't deliver if you don't know for sure, or understand, what it's actually doing, just because it says so. If you're going to go that route and hope some program is going to perform some magic, pay for it, so you can at least threaten the publisher with a lawsuit for stealing your money when it doesn't deliver. Also, this is why there isn't a huge market of such software, because publishers know better and aren't going to stick their necks out to get sued over such a bullshit claims.",
"Most of the tune up apps are malware in and of themselves. Of the ones that aren't they don't actually tune anything up. And because many delete registry files they can do more harm than good.",
"first, the target demographic of people who would download a PC tune-up program are not technologically literate, and would not recognize malware. People who do are technologically literate know that it is unnecessary to \"tune up\" a computer outside of regular system maintenance."
],
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5xvbey | Why do hard drives have the same RPM speeds (like 7200 or 5400)? Is there a specific reason? Or could they go 7205 and still work? | Technology | explainlikeimfive | {
"a_id": [
"del8j91",
"del9kbh"
],
"text": [
"Carry over from old AC motor driven harddrives that use to run at 3600 RPMs. US AC power runs at 60hz per second, which resulted in 3600RRPM drives, until manufacturers figured out they could provide more power using brushless motors at higher factors(5400, 7200). The speed factor kept the description of the drive well-distinguished between good performance, and better. Technology now does not restrict them from making a 6150RPM harddrive, its just not very practical for manufacturing.",
"Ignore brandon's response, it is completely wrong. 5400 rpm translates to 1/(5400/60 s) = 90 Hz. 7200 rpm translates to 1/(7200/60 s) = 120 Hz. They could manufacture intermediate values, but there is no reason to. There is a meaningful cost to implementing a new spindle speed, the control system that aligns the head with a track on the disc needs to be very finely tuned. The spindle motors in HDDs need to be very precise, so there are also manufacturing tolerance concerns."
],
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10
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5xvhrt | How does self-modifiying code actually work? Does this just mean it can continuously teach itself to get better with now peak? | Technology | explainlikeimfive | {
"a_id": [
"del7yo6"
],
"text": [
"Software developer here, That is highly dependent on context. In Lisp, the code is data, and it's absolutely trivial to reason about it as data, at runtime, in your program. This is quite common to do in the language, as runtime code generation and execution is a fundamental language construct. This means you can take your data, blend it with your code, which is just more data, and execute it as new code. Often enough there are constraints put on self modifying code to where the system isn't going to give birth to Skynet. Genetic Algorithms are one such example, where an encoded sequence, the \"genetic code\" maps to a set of basic constructs, which you can consider to be a domain specific language, where when evaluated, can make more complex structures and behavior. I've seen this used in AI in video games, and I've known it to be used in radio to solve some sort of frequency problem and my late cousin used it in earlier Alzheimer's research. Typically the use of self modifying code is to optimize code paths, for example, if a computation can be replaced with a constant, or if a branch (decision) can always be found true or false, then the other branch can be eliminated completely and the branch doesn't even need to be evaluated. I've read of solvers that again optimize code. For example, given a sorting algorithm an example input and the expected output, the solver can optimize the algorithm for space or speed. The optimization tends to be specific to the test set, and while you can use a prover to show it's correct for all cases, it may suffer an extreme performance penalty for for any input other than the test set."
],
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3
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5xw914 | Why are Vending machines so picky when it comes to paper money? | Technology | explainlikeimfive | {
"a_id": [
"deldbaw"
],
"text": [
"When I was 12 we used to photocopy dollar bills and exchange them for quarters in the local laundromat machine so we could go and play pinball. They're pickier now because of kids like me."
],
"score": [
4
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|
5xwepk | In a world where we have devices the size of a deck of cards with enough computing power to launch the Space Shuttle, why does it still take an hour to update software? | Technology | explainlikeimfive | {
"a_id": [
"deldl9r"
],
"text": [
"The task of getting an update to your machine and applying it moves down a very long pipeline. First the data is stored somewhere on a physical hard drive inside a server someplace. The server has to know about your request for the data, access it, send it along the network to the ISP or internet backbone, then the data moves in packets along the internet to your ISP, sent to your area, then to your internet connection drop in your house, then to your modem, to your router, to your computer, stored in your cache, then written to the hard drive, executed by your operating system, your CPU tells the hard drive and RAM which parts to read and store, which files to modify, etc. That's a lot of moving parts just to get v1.7 from YourApp and replace v1.6. And the whole process is as slow as the slowest part in the chain. If the server is slow, the whole process is. If your network is congested, if your CPU is slow or working on other tasks. If your RAM is full, if your hard drive has a slow read/write speed or is failing, and on and on. Each piece of the process has a certain speed it can handle data, whether reading it, writing it, executing it, sending it, or receiving it. Any of those points can bottleneck the entire process, and the rest of the data has to wait until that one slow piece finishes what it's doing before handling the next piece."
],
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3
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5xxqrd | What's the difference between a message being 'sent' and 'delivered'? | Technology | explainlikeimfive | {
"a_id": [
"deloczv",
"delq3a2"
],
"text": [
"When you put a letter in your outgoing mail, it's been \"sent\". When the letter carrier picks it up, it's \"in transit\". When a letter carrier drops the letter off at its destination, it's \"delivered\". When the recipient opens the letter, it's \"read\". Even though things *seem* instant, electronic messaging systems generally have a similar flow as far as an ELI5 is concerned. For example, if you message somebody who is offline, the message has been \"sent\" but it's not received until it is actually seen by them.",
"If you send a message while the recipient is offline, it will be \"sent\" from you, but not \"delivered\" to the recipient. When the recipient comes online again, it will contact the server that temporarily stored the message while they were offline, and request any messages that might be there. When the recipient finally receives the message, it will send a verification to the server that it has downloaded the message in its entirety and without any (detectable) transmission errors. The server now tells the original sender that the message has been \"delivered\". Some, but not all messaging networks also keep track of whether the recipient has actually opened the message as well, but not all. Those that do mark the message as read by recipient when the recipient's device tells the server that it has been displayed to the person at the other end."
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5xy164 | How do websites like Bitly and google (and maybe other websites) shorten links? | Do they host them? Sometimes I even see other links shortened, like Washington Post to URL_0 or something | Technology | explainlikeimfive | {
"a_id": [
"delrfnj"
],
"text": [
"Say you tell URL_0 to generate a short link for your user profile page, Bitly will tell you to use a link that looks something like this: ` URL_0 /aabbcc` When you asked Bitly to generate the link, they write a note in their private database which says: \"The short link /aabbcc should send the user to the full URL URL_2 \". Then when you go to the URL URL_0 /aabbcc the Bitly website will generate a small, simple webpage based on the note in the database. That small, simple webpage will use some means to tell your browser to go to URL_2 instead (this can be an HTTP header or some Javascript code). URL shorteners are mainly used on Twitter due to its aggressive character limit. A lot of more technologically inclined people don't like URL shorteners, because (1) they hide exactly where a link is going to take you and (2) it allows Bitly to gather information on who's visiting what website, that's a little invasive (although TBH avoiding this sort of tracking on the web of 2017 is a losing battle for most people)."
],
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[
"bit.ly",
"bit.ly/aabbcc",
"https://www.reddit.com/user/ByeHammet"
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5xz6gi | Why and how do dead pixels spread across a screen? | Technology | explainlikeimfive | {
"a_id": [
"delzvrd",
"delzzw0"
],
"text": [
"If anyone can explain also how a vertical line of dead pixels in my monitor came back to life, I would appreciate that as well.",
"physical damage and shock aside (where a physical trauma breaks connections, such as a drop or a hit), a 'dead pixel' can sometimes be a symptom of a systemic problem with the array of transistor nodes, bonding, or junctions. screen technologies such as led, oled or plasma pixels are driven by a very large array of transistors. transistors are made up of multiple 'junctions' internally and also bonded connections externally, these are temperamental to things such as shock force, temperature etc - it is common to have manufacturing faults or tolerances such that a lot of these are faulty and have a lesser capable 'range' than others. that understood, a screen where a number of pixels have already failed (either partially or fully) is indicative of a process either during manufacturing or subsequently that left the junctions/bonds *more* fallible. so that screen would be more likely to suffer at narrow temperature and other ranges than one in which all pixels were fine. so it is not that 'all screens with dead pixels get more dead pixels', and it is not that 'every dead pixel creates more dead pixels' - it is a case of '**a screen with dead pixels is more likely, statistically, to get more dead pixels over time**' : there are no absolutes."
],
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3
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5xz6vs | Why can Apple control the shape of its chargers but other companies have to follow the regulations and change it to USB C? | Technology | explainlikeimfive | {
"a_id": [
"dem004o"
],
"text": [
"Apple still has to comply to European standards and as a result, all iPhones sold there have to have a microUSB to lightning adapter, and probably USB-C to lightning adapter soon. It is just easier for the other companies to switch to microUSB after the standardization law was passed in Europe."
],
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Subsets and Splits