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5umnlz | My 9 year old LG Dare still has a full charge despite not being turned on or charged in 7 years. My IPhone 6 Plus that I powered off two weeks ago is completely dead. Why? | Technology | explainlikeimfive | {
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"Different batteries behave differently. Your 9 year old LG is probably using a low-discharge NiMH battery, which keeps its charge better. Your iPhone is using a Li-ion battery, which self-discharges more quickly. However, it shouldn't be dead in two weeks. I have iPhones that I haven't powered in 6 months that still have some large amount of capacity left. You powered it down/powered it off, correct? Some more info (see the self-discharge section): URL_0"
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5umnpy | What does it mean to "Optimize" a game? | In response to this post: URL_0 I get the general idea of what it does, but what do developers actually "do" when they optimize something? | Technology | explainlikeimfive | {
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"I'll give you a quick example, as I recently released a game on mobile, a platform where you're particularly constrained on resources. There's other kinds of optimizations, especially ones that are much more \"lower level\", but this is one example that came to mind. In my game, there's an effect where you can freeze an enemy and shatter it, causing about 20-40 shards of ice to explode away. They have physics, bouncing on the ground and fading away. I was getting bad performance when these pieces were created, because instantiating an object and all its associated components can be pretty intensive on performance. As a solution to this, I \"optimized\" it by having a pool of about 200 of these shards created at the start of the game. They are dormant, and placed well off screen. When I need them to be \"created\" for the shatter effect, I actually just move them to the game world, activate them, and once they fade away they actually go back to the off-screen pool and reset themselves. This made the performance of the effect much, much better.",
"one can optimize by A, rewriting the code to do the exact same thing but smarter. For example, if i wanted to calculate all primes under a million that also happen to be palindromes, i can first calculate all primes and then check how many of those are palindromes, or i reverse it, one is significantly faster than the other, but the end result is the same. B, rewrite code to do approximately the same, when animating a character covered in fur, you can animate every individual strand, but that's utterly insane, instead, how about you animate about 20% which gives a very similar feeling of natural movement for one fifth of the cost. C. Axe features which turn out to be unfeasible. Sure its nice that the water gives a perfectly natural reflection while in a fucking hurricane, but do you really need to dedicate 90% of your gpu to that? How about you just insert a amorphous blob instead? no one will notice. D. Work together with third parties like graphic driver developers, so that they update their drivers to include some specific changes just for your game. (this is naturally only open to the bigger dev companies.) Naturally developers prefer to do A or B, but when the deadline approaches and the limits of the hardware can't be pushed any further, sometimes C makes an appearance and really cool stuff gets removed.",
"Generally optimizing in video games is trying to get the same result by doing less work. This is usually accomplished by smarter use of the platform on which the game runs or removing redundant/useless operations that were not obviously wasteful before",
"In computer programming there are many ways to accomplish the same results. The most straightforward - and less resource demanding - way of doing something isn't always clear right off the bat. Usually we can't write a program on it's most efficient form right away. Normally when we start to construct a program we are more interested in asserting the viability of such solution and see how it fits within the rest of the system (in this case, a game). Once we got it working right, we might focus on refining, cutting corners and getting rid of unnecessary steps. Optimized programs tend to become harder to understand and harder to modify. And that's another reason for the programs to begin their life as \"unoptimized\". The optimization process comes after the program is complete and not likely to be further modified. One such classical (and possibly obsolete) technique back in the PC-XT assembly days was the obnoxious [loop unrolling]( URL_0 ). Basically we would get a portion of our program that's supposed to repeat a number of times and actually replicate the same code as many times as needed. This way, the CPU wouldn't waste time controlling how many times such piece of code was already executed. It would be simply executing a long list of commands seemingly unrelated."
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5umqot | Why does a phone call glitches (affects) a non-wireless audio system? | Technology | explainlikeimfive | {
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"When the cell phone communicates with the base station, it shares the same frequency with a lot of other devices. The way that works is that each device is allocated time slots during which it communicates with the base station, so it sends data for a short period of time, and then it has to wait a while until it gets another time slot. This signal can be picked up by the cable connecting your device to the amplifier, basically acting like an antenna. Each time your cell phone sends data, the amplifier registers a small voltage spike, and then again nothing while the cell phone has to wait for another time slot. The amplifier interprets this as an audio input, and amplifies the signal so much that the speakers play it back. The issue can be solved quite easily by using a [choke]( URL_1 ) on the speaker cable. This thing filters out high frequency signals from cellphones and other devices, but lets the audio signal pass through. You just need to make sure that it's the right kind of choke, it should say something about cell phones on the package. edit: [here]( URL_0 ) is a more in-depth explanation, with some helpful graphics."
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5umxy6 | Why is the threat to net neutrality so recurring? | It seems that every year the theat pops up, then a "resolution" comes and the subject goes away, then next year it shows up again. | Technology | explainlikeimfive | {
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"Being able to charge content providers extra for preferential treatment means more profit for ISPs. They have no incentive *not* to fight against neutrality.",
"It's not recurring, but rather, one ongoing debate. It has never had a \"resolution,\" and likely will not for some years, until all national governments have made permanent rulings on the matter (if they ever do)."
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5umyv5 | Can an electric car be charged wirelessly like the Samsung Galaxy's? | Imagine being able to park your car in a parking lot, and it's charging. No need to fumble around with connectors and not knowing if you have the right dongle to match the pump. Even just a mat that you would lay on your garage floor would be cool. | Technology | explainlikeimfive | {
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"It is coming: * September 2015 AUDI Wireless Charging(AWC) presented a 3.6 kW inductive charger during the 66th International Motor Show (IAA) 2015. * September 17, 2015 Bombardier-Transportation PRIMOVE presented a 3.6 kW Charger for cars, which was developed at Site in Mannheim Germany. * Transport for London has introduced inductive charging in a trial for double-decker buses in London. EDIT: inductive charging is still pretty expensive and slow."
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5uo4fp | How does the "ping" command on the terminal actually work? | Technology | explainlikeimfive | {
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"Simpler explanation: I write you a letter that says \"This letter was sent from < my address > on < date > and < time > . Please send me a letter back as soon as you get this, with the exact time and date you received this. You follow the instruction and send the second letter back to me. When I get your letter, I know exactly how long it took for the letter to get to you, and how long it took the letter to make the round trip. If I don't get a letter back in a reasonable amount of time, I know that something has gone with the postal service between my address and yours. Now imagine that we're two computers, and instead of a letters we're sending data packets. That's basically how 'ping' works."
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5uop2m | Why is it that Asian Countries tend to score much higher than the West in terms of Education, yet it seems the most innovation in almost any scientific/technological field comes from the West? | For a start I'm willing to be wrong about all my assumptions. I always hear that Asian Countries tend to have the best educated people. the highest literacy scores, maths scores, IQ etc. It may also be that in many niche scientific fields some massive breakthroughs have come from Asia - I really could be all wrong. As an example - I always heard that Japan had better technology than the US for mobiles in the early 2000. Media from the 80s/90s always seems to suggest Japan was way ahead of the West technologically, the same goes for South Korea, yet America now dominates the mobile market, as well as the software market. It really does seem that all the great breakthroughs in Science/Technology originate from the West. Am I right in these assumptions? If so what cultural differences may explain why this is the case? | Technology | explainlikeimfive | {
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"Many of the competitive industrial players are in the West so the best and brightest Asian students are drawn there. Likewise, a huge majority of scientific research and funding is in the West, so their scientists and STEM people are drawn there. However, the number of power global firms based in Asia is growing and the advances they have made in technology over the last 10-20 years is astounding. You say that much of the technological advance comes from there, but look at what Asian countries have done for consumer electronics (LG, Samsung, etc), Tech commerce (Alibaba), energy, banking, and transportation. All of the big advancements in high-speed rail are coming out of Asia right now and their infrastructure expertise is amazing (their contractors and engineering companies are gaining market share all over the world). 10 of the top 30 companies in the world (be revenue) are Asian."
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5uouz9 | Why do cell phones always get super buggy/get slower when a newer version of the comes out? | Technology | explainlikeimfive | {
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"The cell phone is built for the OS that was out when it was released. As a result, newer OS will not run as well as the one that the cell phone was built for. Also, the newer OS usually is more memory-intensive, so the phone naturally runs slower. Think of it like trying to run Windows 10 on a computer meant for Windows Vista. Even though Windows 10 is significantly superior, it probably would slow down the computer because it uses lots of memory.",
"To build on what u/sizzling-bacon said, a lot of smartphone users don't back up data and start fresh when they upgrade the OS. Easier to run smoothly from a fresh start, but even that only gets you so far.",
"It's known as [planned obsolescence]( URL_0 ) and is both a direct result of unchecked rampant capitalism, and an example of something completely unsustainable. We live in an awesome time right now. Our grandchildren are screwed, tho.",
"As an android user with a Moto X, the only effect I've seen from updating my OS is vastly improved battery life. Never have I run into planned obsolescence, is that a thing other manufacturers do? I heard apple does it.",
"I am more or less convinced that it's planned obsolescence - the updates they give out near/after a new product launch \"breaks\" older phones, so that their owners will get a new phone. In reality, there is absolutely no good reason a phone should get slower or become buggy just because of age (well, where age is \"small number of years\"). If it does, it's either planned, or the software is genuinely awful."
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5upjg3 | Why is it so hard to emulate (for example) PS2 games smoothly in a "basic" computer even tho they're way more powerful than the console? | Technology | explainlikeimfive | {
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"The emulator has to translate the CPU instructions of the console and game you're emulating into something your own computer's CPU can understand. Then, the emulator also has to take your input from the computer and turn it into something else that the emulated CPU can understand as well. This all requires a TON of processing power. A very good analogy is to imagine the console and computer are two different people who are talking to eachother, but speak two completely different languages. In this case, the emulator is the translator, which can be slow.",
"There are already a lot of good answers here, but I wanted to add something that a lot of them seem to be missing. Yes, it requires a *lot* of overhead to convert the instructions used on PS2 hardware to normal PC hardware, but there's something else that makes it difficult as well. The ELI5 of that being, imagine how hard it would be to translate someone very, very quickly speaking Mandarin at you, to someone who only speaks German, while you yourself are a native English speaker. And you have to be exactly correct, and really, really fast. However, what people are missing is the fact that the PS2 (or any console) has a very specific way of doing essentially everything. The memory is laid out in a certain way, disks are accessed in a certain way, instructions are executed in a certain way, etc. And, because console games are developed to only run on that *specific* console, they will often take advantage of those things. To borrow my metaphor from before, two people speaking in the same language to each other will very frequently use idioms and common sayings, that are total nonsense to a non-fluent speaker! Being able to translate those idioms (or, in the space of emulators, all of the strange quirks of memory and hardware) perfectly, into something that a non-speaker understands, is imperative in being a good translator. The same is true of the emulator. If a game takes advantage of a certain way of handling memory on a console, that same handling method *must* be present in the emulator, or the game will not function. And some of those special methods are inefficient to implement, so it further slows down an already arduous translation task. EDIT: Obligatory \"this blew up.\" I recommend checking out r/emulation if you want to learn more in depth about emulators! Also I recommend [this]( URL_1 ) article on how hard it was for the most prominent Game Cube emulator to boot a specific game. Further down I also link [this]( URL_0 ) talk on why the PS4 is an incredibly weird machine, and so would be extremely hard to emulate.",
"Your computer has to use software to emulate the hardware and OS of the device, then run the game software within that software. It's like Gameception. A good rule of thumb is that you need a device 10-20x faster to emulate an old device, which is why we can only emulate very old consoles currently.",
"The difference in hardware is the issue. The PS2 game was developed to run on PS2 hardware. This hardware natively supports a set of instructions; simple instructions like move, add, or subtract are widely supported, but instructions like division may not be. The difficulty is when the PC doesn't support all the same instructions as the PS2. When an instruction isn't natively supported, it can be emulated using a large number of other instructions. Even a subtle difference can require a large number of extra steps to accommodate. The downside of emulation is that the number of instructions to be completed necessarily increases, often dramatically. What it really boils down to is optimization.",
"The PS2 in particular takes more power to emulate smoothly due to the complexities of the Emotion Engine. It's much less like a normal computer than the Gamecube, and even now we still have to use hacks and workarounds to get some games working properly. Some games (most notably, the Ratchet and Clank series of games) are virtually unplayable. Edit: (According to u/JMC4789 this particular issue was not due to the EE! That being said, emulating such a system is still a chore when compared to the relatively more normal Gamecube or Wii, which had CPUs based on the Power architecture).",
"URL_0 Read this. It tells you exactly why.",
"It's like running a Virtual machine on your computer. Sure you can run multiple OS at the same time but you need to split the ressources (processor, RAM,...) your computer have between the running OS. Emulating a game is running an emulator that translate from your computer language to the target console OS laguage, then run the game OS to finally run the game. You need to split your ressources through your computer, the emulator program, the game OS and finally to the game. So if you try to run a PS3 game, you need to emulate the PS3 CPU (at 3.2 Ghz), you need to emulate the memory (256 Mb RAM and 256 MB VRAM) just to run the OS. After that you need to run the actual game and as others have said, your CPU use a set of instruction that he understand which is not the same set of instruction the PS3 understand. Finally, once everybody understand everyone, The emulator need to translate the video output of the PS3 for your GPU driver can understand and display it on your screen. It's easier for a Xbox one to emulate Xbox 360 game since the system architech are most likely the same people and they have acces to the actual build of the 360 and they have a better understanding of the machine.",
"^(I don't think metaphors made using \"languages\" really convey the difficulty of emulating one piece of hardware on another, because we already use the metaphors for \"languages\" in computing, and they equate to programming languages. Converting from one coding language to another can be a challenging task, akin to translating from archaic Latin to modern Mandarin, but at least you're still communicating from the same species to the same species - human to human. We generally think the same way, our brains function the same way, and we have lots of experience doing language translation. Using language translation as a metaphor for computer only really gets us as far as trying to convert Cobol to C++ while still using an x86 system.) ---- **ELI5**: Imagine you put your brain into a centipede. Your brain is way more powerful than a centipede's brain. But you have no idea how a centipede's body works. You've never had to move dozens of legs simultaneously (or in a rythmic pattern) before. The way a centipede moves is as foreign to you as the way it thinks and communicates. This is so far beyond simply translating a language. This is translating an entire way of thinking and perceiving and organizing the world around you before you can even begin to hope to understand centipede communication. To do anything as a centipede, you'd basically have to learn to emulate a centipede's brain. Imagine how difficult that would be for you, even though your brain is probably several dozens of orders of magnitude more powerful. A computer basically has to emulate the brain *and the body*, *and the language* of the centipede, *without fully understanding every detail*\\* about how the brain and body works, and the computer is only, maybe, an order of magnitude (or two or three) more powerful than the system it is trying to emulate. ---- \\*^(Emulators often have to do a lot of *guessing* achieved via reverse-engineering, but we don't usually have complete engineering plans of the hardware that is being emulated. That lack of complete understanding is often why emulators don't get everything \"just right\" - because they're doing a poor job of pretending to be a centipede. Sometimes, even when we do have complete understanding, hardware limitations prevent perfect emulation. Just like you might completely understand a dance move in theory, but not have the actual skills to pull it off in practice. Even if someone gave you a complete schematic of a centipede's brain, you probably still wouldn't be able to emulate it in real time because even as simple as it is, it would still be mindboggling complex, and your brain couldn't handle it even though your brain is significantly more complex.)",
"Part of it can depend on which game you are talking about. Final Fantasy X, for example, is something I can run on my rather barebones laptop, and I can play Kingdom Hearts with some graphical glitches. But Wild Arms 3, which by all appearances should be easier to emulate, essentially doesn't function.",
"Imagine this, you manage to get a time machine and travel back in time to the the 1500s and try to give science knowledge to a Portuguese navigator. You have more knowledge than him in various aspects, science and so on, but the language is a big barrier. It's the same with the console, it \"talks\" in a language not understood by the current processors"
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5uqm17 | When you turn the volume up on a radio or tv, what actually happens to the soundwaves? | Technology | explainlikeimfive | {
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"The sound wave [amplitude]( URL_0 ) increases. Sound is composed of compression/decompression waves in the air (or water, or whatever). If you change how rapidly the air gets compressed/decompressed, you change the pitch of the sound. If you change the intensity of the compression/decompression, you change the amplitude (or volume) of the sound.",
"An amplifier does not generally have adjustable gain at a circuit level. In other words when you create a circuit that amplifies a signal, it amplifies it a set amount, and adjusting the volume knob doesn't change these physical properties of the circuit. So most volume control is handled using either a potentiometer, a digital mixer, or a relay/stepper system. Potentiometers or volume pots are the most simple. It's a resistor that increases or decreases resistance as the knob is turned. The downside is that they can be fouled by dust, grime, grease, and wear and tear. If you've ever adjusted the volume knob on something and heard scratchy static, that's what you were hearing. Digital mixers adjust the output level in the digital domain. For instance in a 16bit PCM sound sample, 65,356 is the decimal value for the loudest possible sound IE the highest analog voltage. If you want to lower the output voltage, you simply subtract from that digital value and the DAC or digital to analog converter, simply goes with the lower and quieter number. The windows volume adjustment in your taskbar is an example of this. Lastly you have relay volumes which step through combinations of resistance by changing the path the signal takes through a circuit, causing it to increase or decrease at regular intervals depending on the state of the relays. They are complicated but offer a good compromise of actual voltage adjustment, without suffering from noise and dust. So you have your source, which could be a record player, or a CD player (DAC chip) which outputs at 0 to 2 volts usually which is too low to hear with headphones or speakers. That signal goes into a pre-amplifier which is where the volume control is usually done. This adjusts the voltages before they go to the final output stage which is the main amplifier. Then the main amplifier amplifies the signal however much it was designed to and a quieter pre-amp source causes lower volume, and a higher pre-amp source causes louder volume."
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5uslqg | How does rendering a video game at a resolution higher than what my monitor can show make things prettier? | You hear a lot of "Oh, you render more and then each pixel on your monitor becomes more pure and you get a clearer image" But that makes no sense to me, if the pixel is going to show red then it will still show the same red imagining there are more pixels. | Technology | explainlikeimfive | {
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"Imagine that you're just drawing something black and white, like text. At low resolution a particular pixel at the edge of the letter is black. But at 4x that resolution, it's a 2x2 square, of which 3 pixels are black, and one is white. These pixels are then averaged to a dark gray, which is what's displayed at the lower res. The result is a softer, more natural edge Edit: corrected typo"
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5uswji | how do finite numbering systems like phone numbers or social security numbers work? | Technology | explainlikeimfive | {
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"Area codes were assigned very carefully. Back in the day you had to wait for that rotary dial to turn all the way and they weren't quick. Therefore the \"short\" area codes - 212, 312, 215, etc - were all assigned to large cities, in this case NY, Chicago and Philadelphia. Meanwhile Alaska got 908, West Texas got 806. Area codes always had a 0 or a 1 in the center, but never in the other positions. When we started running out of area codes about 30 years ago those rules were discarded and since most people switched to button phones the number didn't matter. The first three digits of your local number were originally part word, part number. As a kid my number was OLdfield 9, you dialed 659. They never contained a \"0\" or a \"1\". The last 4 were random. Sometimes families shared a line, those were called party lines. SSNs are still unique to each individual. The first 3 digits are based on the region of the country where you lived when you got your number (which was rarely done before you were 16 or 18.) The middle two are a group number, like check digits. You can actually check an SSN to see if it's valid bc of those two digits. The final four are random. All this info is US only."
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5uswrl | What software do game developers use to put maps together? | I've always wondered how game developers put maps together. For example, how was the map in GTA V put together? Do they use prosperity software to stitch together assets and textures, or do they make the whole map as one solid lump in something like Blender or 3DS Max? | Technology | explainlikeimfive | {
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"They make their own most of the time. There are way too many to list, so I'm going to list the 2 most popular ones (going to skip the ones from UE and Unity): - Radiant: used in every single id Tech 3+ game and games based on that engine (the most popular one being of course, Call of Duty) - Hammer: originated from an unofficial quake level editor (not sure, if I made a mistake there, let me know), it is the main level editor for GldSrc and Source engine"
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5ut0kl | how do they get a photo or image transferd to a printing press? | How do they take a picture (lets say on a paper) and transfer the picture to the printing press, so they can print it in large numbers? | Technology | explainlikeimfive | {
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"modern day full color printing presses are basically flow thru laser printers. your image is split into 4 colors, cyan, magenta, yellow, and black. or sometimes 8 colors, cmyk and light cyan, light magenta, light yellow and light black. each of those single color shade images are electrostatically imprinted on a drum by a laser. the static charge picks up the ink or liquid toner and is transferred onto the print media (whatever kind of paper product). each color is layered on top of the others to create other shades of colors. then a heat drum if toner or just hot/dry air if ink to sets the image. URL_0"
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5ut5im | Why do people hate Steve Jobs so much? | Technology | explainlikeimfive | {
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"He was kind of a sleazy guy in real life. He tried to disown his own daughter, as in denying paternity. URL_0 He was abusive to employees, and had little regard for the working conditions of people who made Apple products. URL_1 It's not hard to find reasons why people think he was good at some things, but not good at others that are often considered more important for being a good person.",
"Because he got famous and successful by stealing others ideas. Steve Wozniak was responsible for a lot of Jobs's best ideas but he was given little to no credit for any of them. Also, Steve Jobs was a perfectionist and a bit of an asshole towards his employees, and would berate them for even the tiniest mistake."
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"https://en.wikipedia.org/wiki/Lisa_Brennan-Jobs",
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5utc7u | Why does a web page, image, or video always seem to load the exact second I press the back button? | Technology | explainlikeimfive | {
"a_id": [
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"ddwpzcv",
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"text": [
"A web page will try to load everything before it shows on your screen. Sometimes tho it gets stuck somewhere and you only see blank screen. When you press back button all the loading gets stopped and it displays what was loaded while your browser starts loading the previous page.",
"Not an expert, just an experienced user. From my experience, this happens with browsers which have a \"preloading\" function, which means they load a lot of the website's content in the background and then display them at once when everything is downloaded. If you press back before the preloading is complete, the browser displays everything that's loaded at that moment to free the backgrund memory for the website you're going back to, or to simply save some CPU.",
"I'm not a guru in web browser but once you download something, unless you delete it you still have it. So what happen might be that your web browser save a copy of the recently visited website with all the file (image, video, etc.) and when you go back, you browser check if you have visited this page recently and load the copy that you have stored in your memory. You don't have to ask the web server to send it back."
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5uu73s | How can a wireless router send MILLIONS of bits of information to a computer in only 1 second? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It sends them one after the other... and really, really fast. What are wondering about specifically? Edit: read the following answer"
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3
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5uua84 | What happens when you run a Windows program in Compatibility Mode? | Technology | explainlikeimfive | {
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"text": [
"Windows systems change over time, with new versions. Even if a program's code is still executable on a new windows version, an older program might depend on other files that older windows versions almost always had stored on the system, or it might depend on some windows features that have now been abandoned. Compatibility mode attempts to overcome this by applying workarounds and translating an old, outdated function to a new function that can do the same but in a different way. For example, if a program looks for a certain file that used to be in the user folder on Windows 98, it might not find anything where it expected the file, because on windows 7, the folder where user information is stored has now been moved elsewhere. If the program isn't programmed with a way to overcome this problem, compatibility mode can attempt to redirect the program to the appropriate location. Another example could be if the program attempts to load a dll-file that on a version of windows used to be in system32, but now is in systemwow64 instead. It wouldn't find the dll, and the program would either cease to function, or function with limited functionality. Compatibility mode would override the program's request to load a dll from system32, and instead hand it a file from systemwow64."
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5uub63 | Why do high performance engines pressurize their gasoline more than regular engines? | Piggy backed off of the post asking about the difference between regular and premium fuels. Also (semi-related), why couldn't a high performance engine use less pressure? | Technology | explainlikeimfive | {
"a_id": [
"ddwvzch",
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"text": [
"The amount of power an engine produces is a product of how much exploding it does. One way to increase exploding is to make bigger exploding chambers. That makes the engine bigger and bigger engines are heavier and limited in how fast they spin. If i want to make a smaller engine that does more exploding I need to find a way to do so in my smaller chambers. I have some options. I can explode a different fuel. Many racing cars use very high octane fuel for instance. But if i am building a car for the street i can't do that. So i need to find a way to explode more regular fuel. I know that i need more fuel forced into my small chamber to explode. But if i just put more fuel in there it won't all burn and that is bad. So I force more air in there to help all the extra fuel explode. So it takes both more fuel and more oxygen to do that.",
"Simple answer: the more stuff you cram into the same space, the more stuff is in there. The more fuel you stuff (higher pressure) into the same space (the cylinder) the more fuel there is to explode when the spark plug ignites."
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5uveru | Why are old 90s PC games so twitchy and fast on current computers? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because many of them tie their internal timing to the speed of the cpu clock, making the game run faster the faster your cpu is, not unlike how many console games on PS2 and earlier were coded. Not all games were coded like this, however."
],
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5uvfiv | What is the difference between MP and resolution in a camera? | For example, a 4K photo is 3840 x 2160. This is equal to around 8.3 million pixels, or 8.3 Megapixels. So in a camera, what is the point of having 16MP, or 20MP or more, when the resolution only shows 8 million? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"I'd imagine it'd be for clarity when blowing up images. the additional megapixels allow for images being scaled up to maintain their sharpness.",
"As other people are spectating is correct; For clarity and zoom. A good example is this link here, URL_0 , you can still read license plates from 8 blocks away with this 320 gigapixel shot. Your camera can still zoom into the image and with a higher megapixel the image still remains sharp (as long as you took a good photo) while if you were to take it with a 8.3 megapixel camera it would become more and more blurry."
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5uvq05 | Byte Storage | When a program or software claims to require "x amount of space", what exactly is happening? Such as if on a 3DS, a game claims to require 200 units of space, is that just 0s and 1s being inserted on an SD card? How and what is "put" on a hard drive or SD card exactly, 0s and 1s? Sorry if this is confusing. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Think of an SD card like a piece of graph paper. You can fill in squares and erase squares to create block pictures. You're never physically adding squares to the paper, you're just drawing and erasing sections of the already existing papers. So you're limited by whatever size of paper you have. To make a bigger picture, you need a larger section of the paper. If you fill the entire page with pictures and want to make another picture, you either need to get a new piece of graph paper or you need to erase some of your previous pictures to make space. You're not literally coloring in the square on a hard drive, but it's the same idea. For a hard drive, you set the magnetic polarity (+ or -) of each tiny block of the hard drive. For an SD card and other solid state memory (like flash drives), you're changing the way each block reacts when you send electricity through it. Devices with more storage are capable of reading and writing smaller sections (like having smaller squares on your graph paper)."
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5uvyjc | How were the older cartridge games programmed? | Did the programmers have to know machine code to make the games, or was there some sort of higher-level language that compiled down to machine code, or something else entirely? | Technology | explainlikeimfive | {
"a_id": [
"ddx9f9j"
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"text": [
"The oldest cartridge games (like for the Atari 2600) were programmed exclusively in assembly language. For the 2600 specifically, programmers often kept track of how many cycles their commands took in order to avoid overly long functions that would cause the video output to break. The book *Racing the Beam* goes into exquisitely detailed explanations about this if you wish to study further."
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5uw0p8 | How is information stored in the black plastic strip on a credit card? | Technology | explainlikeimfive | {
"a_id": [
"ddxbjc3"
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"text": [
"Iirc it's a set of magnetic zones with different directions, North and South poles, that the card reader can translate into numbers, like binary to regular text."
],
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13
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5uxmht | Why do monitors look weird when you press on them? | All of them do it, even touchscreen ones if you press hard enough. Why? | Technology | explainlikeimfive | {
"a_id": [
"ddxqg15"
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"text": [
"Not all of them do, just LCD displays. The \"L\" in LCD stands for \"liquid\", and when you press on the screen, you are moving the liquid around, causing the color from the pixels to be messed up. Most smartphones don't have this issue as the glass is much stronger, so it takes a lot more strength to push it in. OLED and Plasma televisions don't have this issue."
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5uxmyt | how are smart phones and tablets able to keep getting faster without ever needing a fan, when older computers with the same performance needed big fans? | Technology | explainlikeimfive | {
"a_id": [
"ddxogcm"
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"text": [
"The reason for this is that the electronics get smaller. Smaller electronics have less electric resistance, so they're able to do the same work without consuming as much power and therefore also without developing as much heat. Processing power has doubled without increasing power consumption every 18 months on average for the past 40 years. Within the last 10 years, power-to-performance ratio got good enough to allow us to develop phones that are as advanced as we have now. That said, the CPUs mobile phones and tablets are well behind the performance of laptop and desktop CPUs from the same year. They don't have the same requirements for multitasking and long term performance. A phone isn't pushed to its limits over a long period of time. It loads a website or an app, which consumes a bit of power for a very short time, then the cpu goes back to power saving. A desktop computer from 2012 is still more powerful in raw computing performance than a 2017 flagship phone. It's just that mobile phones never need that level of performance to do the tasks a phone typically does. If you make a mobile phone keep processing at 100% capacity for a long time, it will soon get very warm,and the performance of it will be more and more limited to avoid overheating. A laptop or desktop computer, on the other hand, are designed to be able to run at 100% capacity pretty much indefinitely. To achieve this, they require much more extensive cooling solutions, usually with active fans to remove the heat."
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5uymk0 | What happens to the information when you "delete" a file? (Ex. Empty your computer's trash, delete a picture) | Technology | explainlikeimfive | {
"a_id": [
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"Trash is just a folder where files go when you delete them so that you have an option to restore them if you deleted accidentally, they work just as any other folder. When you empty the bin, the file is really deleted from the file system perspective. Typically the data that were stored in the file is not erased, only the reference to it (so called inode if you want to google) is deleted and the space the file occupied is marked \"empty\" so the next time a file is created, or an existing file gets larger, the data of the original file will be overwritten. It is done so because it's a fast way of deleting files, it takes practically the same time to delete a 100 GB file as it takes to delete 1 KB file and since many programs use files to communicate with each other, this prevents writing big amounts of data when deleting temporary files. If the data haven't been overwritten yet, i.e. shortly after deleting the file, it can usually be restored using some tools. There are even techniques to (at least partly) restore data that have been overwritten. There are programs that try to delete the files in a way that is really permanent, i.e. they rewrite the data several times to ensure the data can't be restored. This is handy when you want to get rid of some sensitive data.",
"When libraries had card catalogs, you would look up a subject and find the Dewey Decimal number for a book. Then you would find the shelf with that number and find the book. When you delete a file, it's like removing the index card from the card file. The book remains on the shelf. Now, suppose the library just removed the index cards for any books they wanted out of circulation, but when they got new books, they just dumped some of the \"out of circulation\" books off the shelf and replaced them with new books (and created index cards for them.) That's basically what happens on disk. The old data remains until new file data overwrites the old. I was the sole maintainer of the file system for a couple of operating system groups.",
"Usually, nothing. It's still there, your computer just stops caring about it. You can think of the storage as like a long row of coins. If the coin is heads it represents a 0, if it's tails then it represents a 1. When you save a file, your computer flips the coins to represent the new data. When you delete a file, it just stops remembering that those coins represent that file. Later, when you save another file, it'll pick that same space to store it in and flip the coins around to represent part of the new file.",
"Deleting a file just tells the OS to mark that memory space as unused, allowing it to be overwritten by new files. Until overwritten, the file itself is still there, just there's no direct way to access it. But with the right recovery software, one can possibly find the file again unless it has been overwritten."
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5uytdu | Why haven't video games on numerous platforms incorporated cross-platform capability yet? What holds developers back when their game is on every platform individually? | Technology | explainlikeimfive | {
"a_id": [
"ddxvseg"
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"text": [
"The Platform companies not wanting to allow it. They believe they will get less money because people will not buy multiple copies of a game, and they believe that people may move away from their platform entirely. There are also concerns that mouse and keyboard on computers will put those players at an advantage over the controler players."
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5uyyr3 | How does Mastercard know my clothing size? | [This article]( URL_0 ) says that Mastercard knows my clothing size because "there’s enough information in a product’s Stock Keeping Unit, or SKU, to determine clothing size". This data could be used to estimate my weight and height and provide this information to flight companies. But how does Mastercard even know what I'm buying? I always thought that my local clothing store, or even bigger companies like H & M, C & A or Esprit, just submit my credit card data and how many Euros they want to charge. So how could Mastercard have any information about Stock Keeping Units? I never have to sign anything that'd allow H & M to transfer this kind of data. | Technology | explainlikeimfive | {
"a_id": [
"ddxx7ao",
"ddxyzc9"
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"text": [
"The article is about a patent that MasterCard filed. Patents are used to protect original and non-obvious ideas -- they give the owner of the patent exclusive rights to the idea for a fixed period of time. This is so you can't come up with a great idea and as soon as you put it in the market, 100 other people put out their own, cheaper version of it. A patent is a limited monopoly for a period of time; after that time has elapsed anyone can use the idea. Here's the key part: the idea does not need to already have been created and implemented for a patent to be filed to protect it. MasterCard had what they thought was a good idea. They filed a patent on it. The article says they haven't implemented the idea, and may never implement the idea. If they were to implement it, they would need to make sure that such an exchange of data would be covered under their privacy policy. But _just the idea_ isn't a privacy violation.",
"Just because they CAN doesn't mean they ARE. That said, it's not unreasonable to expect them to request specific product data at the time of purchase. You likely agreed to it at the application phase, or it's considered public information that is t subject to privacy laws."
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5uzb9i | For massive websites like Amazon or Google, how are they built, scaled to a large size, and maintained? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Well I am a web developer at the opposite end of things to Amazon and Google. If websites were ships those guys are making supertankers and aircraft carriers while I am making kayaks so I can't claim the expertise to actually build things like that but maybe I have enough grasp of the concepts to try a high-level ELI5. So first of all imagine a small 'normal' website. Imagine I build an online book store. On the homepage it might have a bit in the top corner saying: Hello rokd, with a link to manage your account/profile. The main section has a list of this week's 20 top-selling books and on the right is a column with teasers from a blog where I highlight my personal favourite authors. At the most simple level I have one database storing all the stuff I need. It has a table for users (including rokd), a table for books, one for sales, one for blog posts. I then have one script/executable page of code which gathers all the information and assembles in, something like: > < header > > print link_to_user_profile(getCurrentUser) > < /header > > < main > > print get_recent_bestsellers(20, week) > < /main > > < sidebar > > print get_recent_blog_items(5) > < /sidebar > This is all well and good but this one script running on one computer and one database running on one computer is doing everything for this page, and every other page served to every other user. So the only way to scale is to make those computers really really powerful and at google levels even a supercomputer isn't enough. Setting aside that problem completely for a moment, let's imagine I didn't want to bother building a blogging system for my bookshop because wordpress already exists and why invent the wheel. So I get a site at URL_0 and I change my page to something like: > < sidebar > > print ask_remote_server_for_something(server= URL_0 , account=somersettlerbookshop, request=latest_blog_posts(5)) > < /sidebar > So now my blog posts are being stored and rendered somewhere else. I just make an API call to URL_0 and ask for something, it supplies the answer, I don't even know or care exactly what database my blog posts are stored in, or what script on what computer renders the data into html. So long as URL_0 tells me what I want I don't have to give a shit how it does it. Well what Jeff Bezos famously did in 2002 is [issue an edict]( URL_1 ) that all teams in amazon had to built their shit to talk to each other in the same way as I talk to wordpress in the example above. Even though they are within the same company, and even though, at small scales, their code might be running on the same computer, they always had to pretend they were totally separate and only communicate through remote services and APIs. So I change my code to something like > < header > > ask_remote_server_for_something(server=user_subsystem, request=link_to_current_profile(currentuser)) > < /header > And so on for every element of my site. That way separate tasks can be split across separate computers. So 1 computer just runs the books stuff, 1 for the user stuff, 1 for the blog stuff, 1 for the sales, and 1 to coordinate all the requests and piece it together in a single page for the user. Now, we might add some cacheing. For example, I only write a new blog post every couple of days. So if you load my page at 9.00pm, then refresh at 9.05pm, at present, we are loading all my blogs from the database and rendering them all over again, even though nothing has changed. Our get_latest_blog_posts code might look like this: > blog_raw_data = get_recent_blogs_from_database(5) > rendered_blogs = render(blog_raw_data) > return rendered_blogs Waste of resources. So I can tell it to cache the results of a request and only re-calculate it if a certain amount of time has passed, say, 24 hours. The code changes to something like: > if (more than 24 hours has passed since I was last asked) then > > blog_raw_data = get_recent_blogs_from_database(5) > > rendered_blogs = render(blog_raw_data) > > cached_blogs = rendered_blogs > > return rendered_blogs > > else > > return cached_blogs Note that my top level page doesn't know or care about this change. It just asks for blogs, and it gets blogs, it doesn't matter to it whether they came from a cache instead of from a database. Now let's imagine my website needs to scale even more. It's a bookshop, so books is the hardest-working subsystem I have, and 1 computer is not enough to run it any more. So we changed > print get_book_information(bookID) to > print ask_remote_server(server=books, request=book_information(bookID)) But now we need several servers: books1, books2, books3. So make it something like > print ask_remote_server(server=find_me_a_books_server, request=book_fnformation(bookID)) and have another server in the middle, called a load balancer, which keeps track of whether books1, books2 or books3 has capacity to service a request, and sends it on accordingly. Once again our top level page doesn't know or care which of the 3 books servers answers the request, so long as it gets an answer. Basically we keep breaking our software down into self-contained 'black boxes' which communicate with each other through defined protocols, and that way if we outgrow 1 server we can use 2, or 3, or 300, on different continents. Still, we can't scale perfectly, because if I'm running my bookshop on 20 servers, and it maxes out, then while my _software_ is capable of seamlessly extending across 30 servers, I can't just wave a magic wand and have 10 new PCs in my racks, all wired up to my network. That takes time. But I want my site to suddenly have twice the capacity if it gets linked from reddit. By the time I get the new servers physically installed the reddit traffic has gone. So we invent virtual servers, where an entire physical server is virtualised in software within a more powerful actual server, capacble of hosting multiple virtual servers. And we take our find\\_me\\_a\\_server code, which used to say: \"Hey, books1, are you busy? Hey books2, are you busy?\" and hand the request to whichever server said \"no\" - and we change it so that if _all_ the books servers say \"sorry, I'm busy\", it just creates a new books4 server on the fly. Once we get used to coding in this distibuted fashion we can also rewrite our algorhythms to take advantage. So rather than simply separating the \"books\" workload from the \"sales\" workload, we can also improve performance of a particularly taxing sales data processing task by splitting that into parallel tasks across multiple servers. google's map_reduce is an example of this sort of thing but getting a bit out of my depth / scope of this answer to explain that in detail. There's another whole category of scaling around databases. Most traditional databases are 'ACID-compliant', and 'normalised'. Again this comment is getting way too long for me to go into detail on that but basically they are ways of ensuring your data does not get corrupt. Say for example my bookshop is extremely busy. As you visit the homepage the code asks the sales system for the top 20 bestsellers. It returns the #1 seller, _Harry Potter_ with 150 sales in the last week (narrowly ahead of the #2, _Bambi_ with 149 sales). While it does this, three people buy a copy of Bambi and one person buys Harry Potter. My code then proceeds to tell you that the #2 seller is Harry Potter with 151 sales (because the #1 is now Bambi with 152). So your list is 1 Harry Potter 150 sales 2 Harry Potter 151 sales WTF? Looks like my system is fucked, right? Traditionally databases avoid this through ACID compliance, so the database is locked while a transaction is made to ensure consistent results. Simplistically, this would mean while you are generating the list of bestsellers, nobody else can buy a book, because that would change the results. But everybody visiting my homepage generates that bestseller list. If nobody can buy while someone is looking at the homepage, I'll never sell any books. Customers will always get a \"database locked, cannot purchase!\" error and give up and go to Amazon... So some people realised, it doesn't actually _matter_ if your bestseller list is based on the most accurate and up-to-date data. If it's based on sales as of 5 minutes ago, that's fine, then we can carry on selling. We can tell you Harry Potter is #1 when it is actually Bambi #1 since we made a few sales a millisecond ago - who gives a shit? On the other hand it _does_ matter if we tell you we have 10 copies of Bambi in stock when we actually have zero left, since we made a few sales a millisecond ago. So people started carefully breaking down which parts of the database required traditional 'safety' / consistency / anti-corruption guarantees, and which parts didn't. And for the parts that didn't, by selectively adding caches, splitting amongst parallel systems, denormalisation, abandoning ACID-compliance, or even abandoning SQL paradigms completely, they could get more performance. tl;dr distributed computing, parallelisation, cacheing, load balancing, virtualisation, denormalisation, nosql"
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5v13xh | If google encrypts my e mail in transit and at rest how do thry read it to target ads? | Technology | explainlikeimfive | {
"a_id": [
"ddyftas"
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"text": [
"It's like someone is giving you a box with a code lock and you can put something inside and he will deliver it wherever you want. But still.. He knows the code."
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5v19zn | What exactly went wrong when you have to use the pinhole reset switch on an MP3 player? What exactly does that little switch do? | Technology | explainlikeimfive | {
"a_id": [
"ddygvcq"
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"text": [
"There are times when software gets confused and lost. When it is lost it doesn't know how to get back to home, and home the only place it knows how to \"be an mp3 player\". Pressing the reset button is like having a GPS tracker on someone who's lost - when you press it, you swoop in, pick the software up and plunk it back home. In technicalities, pressing the reset button usually triggers a circuit that forces the microcontroller in the mp3 players to reset just like it would have if you removed and replaced the batteries. The circuit can be outside the micro or it can be a dedicated pin on the microcontroller. No matter where the software gets lost, resetting the micro always starts it over from the beginning where hopefully it won't get lost again."
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5v1g36 | How do the newer microwaves that can have metal placed inside them work? | I was at a Sears recently and saw some new microwaves advertising that metal could be put in the microwave without any harm to the appliance itself. How does this work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"The metal inside is rounded, which helps prevent the charge from finding a way to arc out. Metal in microwaves builds up electric charges that shoot out at the edges. Things like aluminum foil has a lot of edges and corners. Truth be told, if you ding or clip any of those metal racks they will spark and cause a bad day"
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5v1nb1 | Why do different cars require different grades of gasoline? Do some engines actually require premium unleaded or is it just a scheme to make you spend more money? | Technology | explainlikeimfive | {
"a_id": [
"ddyjjnb"
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"text": [
"octane is an additive that makes gasoline less combustable. engines that have very high compression ratio (the ratio of cylinder volume at the bottom of the stroke vs the top of the stroke) can make the gasoline detonate before the piston gets to the top of the stroke. This is bad, commonly called \"knocking\", this means the explosion is actually trying to force the engine to run backwards. anyway, so yes, cars with high compression ratios need high octane gas to prevent this pre-detonation. side note, some modern cars can vary their timing to work with any octane, getting higher power/efficiency with higher octane, but not enough efficiency to offset the cost premium on the fuel."
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5v1uyd | What are fair split screens? | Technology | explainlikeimfive | {
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"text": [
"If you're going to ask about a current Reddit post, [it's helpful to include a link to it in the question]( URL_0 ). Split screen video games are where you have multiple players, each with their own view on half the screen. Think playing Golden Eye/Halo on a single system. One of the problems you run into here is that the other player can look at your screen to see where you are, making it impossible to sneak up on somebody who is \"cheating\". A \"fair\" split screen is one that somehow prevents this. The method used in the post I presume you're talking about involves using a 3D TV and giving each player special glasses. One player only sees the \"left eye\" image and the other only sees the \"right eye\" image. When it works right, this means two people are looking at the same TV, playing the same game & seeing completely different images."
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"https://www.reddit.com/r/gaming/comments/5v00ea/so_i_heard_you_guys_like_fair_split_screens/?utm_content=comments&utm_medium=hot&utm_source=reddit&utm_name=all"
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5v26ak | What is the difference between a Get Request and a Post in HTML? | Technology | explainlikeimfive | {
"a_id": [
"ddyynec"
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"text": [
"It's a part of HTTP, the protocol that defines how webpages are transferred, not HTML, the language in which they are written. So in HTTP, there is a field in the request called \"method\" which can be GET, POST, or a few others. GET is for reading data, and cannot have a request body, i.e. the request contains only the URL of the resource you want to get. At most the URL can contain some parameters, like the ?id=123 & lang=en & page=5 you often see at the end. A server is not supposed to make any changes to the data in response to a GET request and always return the same data, because GET requests can be cached or sent multiple times. POST requests on the other hand are for changing data, and they can have a body, i.e. contain arbitrary amounts of data. So you can use them to upload files, they can change data and are not cached - which is why browsers warn you when you try to resend a POST request. If it was sent before, the data may already have changed, and you may not want to have the same change applied again. However, webapp developers often ignore these rules and use GET requests to change data or POST requests to read data. Sometimes they can get away with it, sometimes it causes problems. For example if you try to misuse a GET request to upload files, it will work for small files. But the URL parameter will get ridiculously long, and at some unknown point the browser or server will refuse to process it, or even truncate it."
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5v6byx | How does the Pirate Bay keep maintaining a well known easy to type DNS address? | After the big raid in 2006 and the other subsequent attempts to shut down the Pirate Bay, I naturally assumed that we would all very shortly end up needing to copy-paste IP addresses into our address bar to access the Pirate Bay site which we'd be sharing on forums or whatever. But to my surprise, I've never had to do that. Nor have we had to use unrelated addresses like " URL_0 " -- no, it's always straightforward "thepiratebay.country". How is this happening? I understand why the authorities aren't able to kill the pirate bay, but surely they should be able to deprive it of an easy obvious domain name. It has always remained so easy to access that a retarded monkey could use it. This seems remarkable. How have they done it? I've searched other attempts at asking this question but none of the answers were very good. Most didn't seem to understand that the question was about the domain name and those that did seemed to simply repeat "can't do it" without saying what's actually been stopping governments around the world from at least making it less easy to access through a super convenient and easy to remember domain. When I Google this, all I find are a bunch of articles about how to access the pirate bay, not about why governments haven't been able to take away their domain name. | Technology | explainlikeimfive | {
"a_id": [
"ddzjuvp"
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"text": [
"Well, you mainly need to understand the politics of domain names and ICANN. ICANN, or the Internet Corporation for Assigned Names and Numbers, is the organization that oversees the internet in general through two primary tasks, IP address allocation to ISPS, and DNS. They \"oversee\" DNS in a bit of a weird way, here is why. The ending of the domain name like .com or .org, is known as a Top Level Domain, or TLD, and while ICANN is the one to make it, it is always by request of some other organization, which becomes the administrator for that domain name. ICANN's actual control of who registers what domain name is very limited and is left largely to the administrators of the TLDs. All ICANN does is make the TLD for it by adding an entry for it in the 13 root name servers, the backbone of DNS, ask 18 cents for each domain registered if the domain is bought, and just make sure that the administrators have all the necessary infrastructure to keep that TLD up and running. Outside of that, there are hundreds of organizations responsible for their TLDs, and if you register thepiratebay for each TLD, there ain't shit anyone can do about it, Sweden forces the administrator of the .se domain (which they do because .se is obviously administered by a Swedish organization) to take it down, they switch to another one based in somewhere Sweden can't reach. ICANN has its power in the matter limited both contractually and physically, there is really no way ICANN can take down a single domain name other than asking the administrator to do so."
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5v6l1z | How does Bluetooth work? | Technology | explainlikeimfive | {
"a_id": [
"ddzlqf9"
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"text": [
"Bluetooth is essentially marketing. It branded a specific radio frequency and standardised how devices talk to each other. The actual technology is nothing special."
],
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5v79kt | How does a wireless phone charger work? How can the phone receive more energy without being connected at all? | Technology | explainlikeimfive | {
"a_id": [
"ddzrt8s",
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"text": [
"The charging base has an electromagnetic transmitter, and in your phone is a receiver that is connected to your battery charging circuit. basically, they are both magnets. Electricity and magnetism are related, and you can use the difference of potential and oscillation (think of it as a magnetic vibration) to generate electricity. So think of it like this - the plug in the wall brings the electricity to the charging base, which changes it in to a magnetic field. The receiver in your phone converts this magnetic field back to electricity which it uses to charge your phone.",
"They use \"induction charging\". The fundamental idea is that an induction coil turns an electromagnetic field into energy or energy into an electromagnetic field. If a magnetic field flows through the center of a coiled wire, a voltage is generated in the wire, which causes an electrical current to flow"
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5v79zt | How come you can us your finger or stylus when scrolling on an iPhone, but not a pencil eraser? | Technology | explainlikeimfive | {
"a_id": [
"ddzrjhk",
"ddzsx68",
"ddzvb45"
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"text": [
"iPhones (and other similar smartphones and tablets) use what is called a capacitive touchscreen. This means that it uses the electricity flowing through your body to complete a circuit to detect touch. The styluses that work with these screens are designed to have a conductive surface to complete that circuit. Pencil erasers don't complete that circuit.",
"Ok but once I actually opened an app by touching a bagel to my screen? Why the hell did it work?",
"I at first misread this as OP wondering why you can't erase pencil with your finger. Thought some of you might get a laugh out of it."
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5v9d8i | What is the difference between computer science and computer engineering? | Technology | explainlikeimfive | {
"a_id": [
"de09e76",
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"text": [
"\"Science\" is a research activity whereby new knowledge is identified. \"Engineering\" is applying knowledge to solve a specific problem. For computers, this is often seen as two fields: \"software engineering\" and \"hardware engineering\".",
"If we're talking university majors, Computer Science is more software based with a bit of a research bent, and Computer Engineering has more hardware focus. Source: am Computer Science major",
"Computer Engineer here. The difference is in focus. Generally, CS is solely the study of software, with a minimum approach to understanding the hardware of a computer. As in, CS study algorithms, data structures, multiple languages, etc. They do usually take a class which gives them an overview of the low level interpretation going on inside a basic processor, but that's about it (also depends on the school and how integrated the department's are. Personally, my school has CpE in Engineering, and CS in Science). Computer Engineering however, is more of a combination of CS and Electrical Engineering. CpE majors/grads study the software and hardware side of electronics/computers as opposed to just software (CS) or just hardware (EE). We don't go nearly as in depth in software as CS, but we usually have a pretty thorough understanding of it. But we do focus a lot on hardware. However, depending on the school the curriculum is usually either a 50/50 split focus on CS/EE or a 75/25 split. Note: when I say hardware, I mean electrical circuits/components/electronics"
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5va82m | Why hasn't a "new Facebook" broken through after all these years? | Technology | explainlikeimfive | {
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"Well, for one thing there HAS been a large number of successful social networks that have risen up since Facebook became popular, like Twitter, and Instagram. If you look at more specific services that exist to fill a certain niche, there's tons like Snapchat, LinkedIn, etc. that have plenty big enough userbases. Each one is a bit different, however, because any company that has the budget needed to actually compete with Facebook isn't going to risk competing directly. Instead, they try to provide a different sort of service, so that people not only are more likely to have a reason to use both, removing the need to actually sway Facebook's users to their side exclusively. The reason no successful service that attempts to do pretty much the same thing as Facebook has come to be can be boiled down to 3 reasons. 1. Everybody already uses Facebook. For the single user, it's already going to be difficult to convince them to jump ship since they already have so much they've put on FB that they wouldn't want to abandon, as well as the simple familiarity of the site they know. However, when you consider that FB is a community-driven service, it becomes even harder to get people to switch to a competitor, since all of their friends have to as well, not to mention all the new friends they won't be getting by using an obscure site. 2. Facebook is pretty decent, and is aimed at a mass audience. MySpace was replaced by Facebook because it had some major flaws to its system, as well as certain design choices like giving users more customization of their page made the site less likely to appeal to a wide audience. Facebook is not perfect, but it's good enough that few people are going to complain enough that they go looking for an alternative. 3. Advertising. Facebook has ludicrous amounts of money to spend on advertising, as well as the sheer amount of free publicity it gets every time someone or something tells you to add them on Facebook. This ensures that for every new potential user, Facebook is almost always the first place they look, cutting out millions of people from finding a competing service.",
"Because there already is pretty much everything. For something new to break through, it has to be original. Which is hard nowadays, considering the amount of different social networks there are. There is Facebook, Twitter which has the 140 character feature, Instagram which lets you share pictures and short videos, YouTube which let's you share videos in general and so on...",
"I think it's both a networking effect and anticompetitive practices. The networking effect as Gnonghgoi explained is simply that it's difficult to get people to join a network unless the network already exists. That means it's hard to get a network started. Anticompetitive practices involve taking ideas from other services and integrating them with their own. Facebook has integrated new ideas from Twitter and Snapchat, for instance, without negative repercussions. Or did you think \"Facebook Live\" was an original idea?",
"A lot of this is down to the network effect. Because almost everyone have facebook and facebook makes it hard to integrate with other competing services it is hard to get started in the market. For instance if you were to make a messaging service without any more features then the facebook messaging service and with fewer of your contacts then who would use it when there is facebook messaging. When faceboot messaging were first developed you could integrate it with other messaging services like Google Talk but both of those have switched to proprietary protocols to deliberately make it harder for people to integrate with."
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5vb5f8 | Why are people getting arrested for having Kodi? Doesn't Kodi just organize the user's media? Even if the media is illegal or not, it's the user's issue. | Just as the title says. | Technology | explainlikeimfive | {
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"de0n278"
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"text": [
"It's hard to say specifically, since you do not refer to a specific incidence. However, several people have been arrested for distributing boxes that *have* Kodi, not because Kodi is present but because they have also pre-loaded software on them which features unlicensed (and thereby illegal) forms of content."
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5vbdoe | Why do different countries/regions have different voltage outputs and outlet shapes? | For example, the US and Canada have 110-120V output while the Middle East has 220-240V output. The shape of the wall outlets are very different too. I know this is rectified using adapters and power transformers but why have different systems in the first place? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Most of the world has a 220-240 V / 50 Hz (All of Europe, most of Asia, most of Africa). America (US, Canada, Mexico, central america and a couple of countries in south america) have 110-120V/60 Hz. When changing from direct current to alternate current (DC/AC) two standards settled. In America, 60 Hz and in Europe AEG decided to go to 50 Hz (it was a more \"metric\" number). The standard was applied to the colonies too. In the beginning, however, Europe had also 120 V. Then everybody realised they needed to go to a higher voltage to have less losses, so Europe went up to 220 V. In the US they decided that many households already had a lot of electrical appliances and that would have cost a lot of money. Europe, well, we were building Europe back from the second WW, so we didn't have so much stuff as the war-intact US... Anyway, the US did go up to 240 but figured out a workaround. Those 240 V split in two 120 circuits in your houses. And some appliances like the clothes drier do use the 240 V. Edit: outlet shapes. No idea."
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5vc2xd | How do the little green glowing sights on my handgun continue to glow in the dark despite being kept in a dark safe for months? | Technology | explainlikeimfive | {
"a_id": [
"de0tn7i",
"de0ttsm"
],
"text": [
"They contain a radioactive element, tritium. That excites the gas inside and glows green. They usually glow for about ten years and you will need to get them replaced of you still want that feature.",
"Probably because they use Tritium (Hydrogen-3). The radioactive tritium decays by emitting an electron (beta decay) which interacts with the phosphorus coating, producing light."
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5vc4na | What is a computer 'memory leak'? | I see it's a huge issue with PC software but have no clue what it means. Can someone kindly explain it to me in simple terms please | Technology | explainlikeimfive | {
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"de0uj2d",
"de0uf4y",
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"text": [
"Modern operating systems let you run multiple programs at once, but you only have one pool of RAM that they all have to share. The way that works is that when a program wants memory, it asks the operating system for however much it needs, and the OS finds a block that's not being used and loans it to the program. When the program is done using the memory, it's supposed to return it so other programs can use it. A memory leak happens when a program forgets about a block of memory the operating system gave it. As far as the operating system is concerned, it still has that block \"checked out\", but the program can't do anything with it, and it can't return it back to the operating system because it can't find it. The memory isn't gone permanently- when the program exits, the operating system knows it doesn't need the memory any more so it marks all the memory that was checked out by the program as \"available\" again. But it's not going to be available as long as that program is still running. It's only a big problem if the program keeps doing this. If it keeps hitting the code where it asks for more memory, but never returns any of it. Since it's not giving any memory back, the program will, over time, consume more and more of your computer's memory until you don't have any more memory to give it. At that point, the computer has three choices: 1. It can start rejecting requests from programs that ask for more memory (which generally results in those programs crashing) 2. It can try storing additional data on the hard drive, which keeps the computer running but is something like 1000x slower than RAM so your computer will slow to a crawl 3. It can try to figure out which program is stealing all of the memory and terminate that one (Linux does this, Mac and Windows don't since some programs don't deal well with not having time to clean up) EDIT: formatting",
"Software developer here, Memory is a finite resource, your computer has only so much of it. Every program needs memory, and it's use has to be coordinated to ensure no two programs overwrite each other. That coordination typically happens through the OS as the mediator between all other programs and memory. Every program keeps track of what memory addresses it's using. Typically, when a program needs memory, it will request what it needs, and when it's done with that memory, it will release it back into the pool of available memory. Most programs, it's the responsibility of the programmer to allocate and free the memory. Oversights are common, and an algorithm may allocate memory without releasing it when finished. The OS doesn't know the program is done with that memory, it doesn't know there's an error that is allocating without releasing memory, and the program error may be such that the program loses track of which bytes it no longer needs, and now it can't release it back to the OS. This is a memory leak. The pool of memory is slowly draining. This can bog down your system until the offending process is killed and the allocated memory can be reclaimed, if other processes don't themselves start failing.",
"It is a symptom of a programming error. When a program needs to store things in memory (basically whenever you do anything) it needs to request a certain amount of reserved space which is allocated by another program, usually part of the operating system. Then when the program is done it needs to tell the operating system to release that memory so others can use it. If a programmer screws up and doesn't release the memory when their program finishes those patches of memory never get released. The total amount of memory the program has allocated to it increases as the process is run over and over, gradually crowding out the other programs which need to allocate memory as well.",
"Let's consider those Halloween stores that randomly pop up in deserted shops. Every October, they rent out 100 empty shops (allocating memory). After Halloween, they need to make sure to make sure they stop their lease in all 100 shops (freeing memory). However, due to an error in accounting, they managed to stop their lease in 99 shops but not the last one. The next year comes around and they rent another 100 shops. The error strikes again and after Halloween, they now have 2 shops they're paying all year round for. Over time, if the Halloween company didn't manage to find this mistake they will lose a great deal of money! This is a memory leak. Due to improper programming, not all the memory is freed in a program so it starts to consume more and more over time, eventually hogging enough of it to slow down or crash the system.",
"I think the best ELI5 would be to equate a computer as a teacher, and computer programs as little students. So... a little kid asks for a marker from the teacher. Teacher hands it out. When the student is finished with the marker, they return it to the teacher - and the teacher puts it back into the marker jar. Now what ends up happening, is that there's *a lot* of little kids asking for markers. At once. Teacher dutifully hands them out. Now, little kids being little kids, some *forget* that they already have a marker and ask for another one. They inadvertently keep the first marker, while using the second marker. Sometimes they forget they have two, and then ask for a third. So when the teacher runs out of markers, she freaks the fuck out. Yells at all of the kids, kicks them out of the room, scours the whole room for markers, and puts them back. Now imagine each \"marker\" being a piece of memory. A memory leak occurs when the little shits (programs) forget that they have markers yet keep asking for more, and the teacher knows that they exist somewhere but not sure *exactly* where. You reclaim memory (markers) when you refresh everything and start over."
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5vc5wh | What is a "memory leak" (in a PC/phone/etc..) and how does it happen? | Technology | explainlikeimfive | {
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"text": [
"In its simplest form, a memory leak is what happens when a program doesn't discard memory it isn't using anymore. Think about it like a bookshelf. Every time your program needs some memory (a book), it goes and gets it from the shelf. When it's done with it, it frees up the memory (puts the book back on the shelf). If it doesn't return the book, you'll eventually run out of books to get (memory to place objects in). Things will run slowly (or crash that program)."
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5vcxsi | Why do some devices (like a cordless razor) slow down as the battery runs low but others can put out full power (like a laptop or smartphone) | I am wondering why my razor slows down as the battery level decreases, but my laptop can run games with full brightness and sound right until the moment it powers off at 0% battery. | Technology | explainlikeimfive | {
"a_id": [
"de1316t"
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"text": [
"As your battery runs down, the voltage it outputs drops. For a device with a motor like a razor, that means that it runs slower, since the reduced voltage doesn't push/pull on the electrons quite as hard and the current flow is reduced. With many digital devices, however, the circuit contains a \"voltage regulator\". This device takes in the power source on one side (be it from batteries or a wall transformer) and outputs a steady voltage on the output. That output is the power input to the rest of the circuit. The reason this is done is that digital logic circuits depend on the voltage being in a specific range to operate correctly. Once the voltage is too low (or even too high), the design parameters that were used when designing and verifying the circuit operation no longer hold, and it could misbehave. So on something like a laptop or a cellphone, the voltage that comes into the regulator from fresh batteries is actually higher than what the circuit needs to operate. The voltage regulator reduces the voltage output to the right range. When the battery voltage gets too low, it starts to warn the user. When it gets so low that the voltage regulator can no longer provide an output in the right range, it shuts down the device. A really cheap digital device (such as a toy) may not have a voltage regulator. It is designed to try to be tolerant to a wide range of voltages. When the voltage gets too low, it simply stops working correctly."
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5vdilj | Satellite TVs transmit terabytes of information everyday with 500+ channels and HD programming to millions of homes for very reasonable prices, why isn't the internet similarly available for public use? | Technology | explainlikeimfive | {
"a_id": [
"de16cw8",
"de1a4du"
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"text": [
"Internet is two-way. Satellite TV can broadcast the signal to everyone at once, because everyone gets the same channels. With internet, everyone's computer is asking for a different thing.",
"A satellite sends the transmissin ONCE towards the Earth. You are equpped to receive it or not (this is why you could have illegal boxes), somewhat like radio. Internet is a direct connection to every single individual users. If you have a million users, you send that same data a million times. it thus take quite the infrastructure to keep a decent speed up, and in a way having a price barrier insures you dont flood your infrastructure and give everyone a crappy speed. Still, nowadays they should be able to do much better than they are, price-wise."
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5vdz30 | How does Facebook determine which people to show activity from on my news feed? | Technology | explainlikeimfive | {
"a_id": [
"de1b2cj",
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"text": [
"That's part of their secret sauce and what makes Facebook what it is. That's kind of like asking how is Google so efficient at searching the internet. We can imagine Facebook looks at correlations, such as whether you have listed them as family in your profile, how many mutual friends you have, how often you like each other's posts, etc.. but the nitty gritty details of how it chooses to show content to you proprietary.",
"There are a few ways: First is if you have them listed to see first. In their profile you can pick see first, normal, or unfollow. Though it may put someone to see first based on my second point! Second, how much you interact with their posts. Liking, commenting, sharing, or even just viewing repeatedly makes Facebook give them more of your attention. Eventually worth enough people you'll see them first and others later. The app and web page likely both keep track of which posts you've seen and filters based on that too And lastly, suggestions based on what they know about you. Facebook logs details about posts and if they match your interests then it'll bump them up. It learns about you from what you have on your account and linked into it. Also they probably buy and sell info with other sites like Google to get more details. Word of note! Any site that lets you sign up for free and has info on you (even if just a name) will likely trade that info around."
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5vel5i | Why is the same exact text message sometimes received twice when only sent once? | Technology | explainlikeimfive | {
"a_id": [
"de1gc50"
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"text": [
"Phone: Please send this message and let me know that it's sent. Provider: I got the messag- a... it... ...ved. Phone: It's not properly sent? Let me send it again. Provider: It has been received! I got the message and it has been received! Phone: Two confirmations? I only care about one of them. Message sent. If there's disruptions in service, your phone will try to send the message again, causing a double transmission if both get through."
],
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5vg8u9 | Why is that computers connect to just one wifi connection and not multiple ones at the same time? | Technology | explainlikeimfive | {
"a_id": [
"de1uvhs",
"de1ui9c"
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"text": [
"Wifi cards only have one tuner and transmitter, think of it like a standard radio. You cant tune to 2 stations at the same time, a transmitter can only transmit on one station at a time as well.",
"It only has one WiFi card. You should be able to connect to two networks if you have two cards. I think."
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5vgc97 | Why is there a num lock key on the keyboard? In what situation would you not want the number keys to work? | Technology | explainlikeimfive | {
"a_id": [
"de1va2u"
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"text": [
"In earlier days of computing, the NUM keys were also the ARROW keys and directional keys. The Num Lock was a necessary key to turn on and off the numerical vs. directional functions of the keyboard and is a feature that is still included to this day. Even my Razer Chroma has directional keys and other functions that work when Num Lock is off. Not all keyboards were made/designed with a seperate set of directional buttons or things like Home page down or page up."
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5vgfjx | Why does every radio station seem like they go on commercial break at the same time? | Technology | explainlikeimfive | {
"a_id": [
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"They often run breaks at neat round-number times. For example the station will air news and traffic reports on the hour, so they'll put an ad break just before that.",
"most radio stations are broadcast subsidiaries of the same company, clear channel. they have no reason to stagger their commercial breaks. competing radio stations will stagger their breaks differently to compete, so when you start dial surfing you'll find a station not on commercial break, but it's likely that all of the radio stations in your area are all owned by clear channel and they have no reason to do such a thing."
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5vh8s2 | What's the difference between development and production in programming? | Technology | explainlikeimfive | {
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"Production are the servers that are actually running a business and dealing with customers and real data. Right now, you are on the the Reddit \"production\" server. While you're writing software, you need to go through various levels of testing and quality control before you decide that the software is ready to push up onto production servers. Various names for these systems include development, testing, QA, staging, etc. They're separated from the real users, real data & set up in such a way that bugs in the code you're working on won't bring the whole business down. *Ideally*, the only difference between dev and prod is that dev won't have access to all the prod data & services. In practice, this is hard to do. Having differences between dev & prod is something that often results in upgrades breaking live servers because developers weren't able to test for some condition or another."
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5vjemt | How does GPS work in space? | The SpaceX delivery to the ISS was aborted today due to GPS errors in space. How does GPS work in space when GPS satellites and the Dragon delivery craft are both moving? I thought GPS location was calculated based on a stationary object on earth calculating its position relative to moving GPS satellites in space. | Technology | explainlikeimfive | {
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"A moving object can still calculate its position relative to GPS satellites. The speed of the vehicle is negligible compared to the speed of the signals. Many receivers also keep track of a number of measurements over time, specifically to monitor their movement, and determine if they get a bad measurement. After all, many cars make use of GPS today, if one had to be stationary that would stink."
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5vjm8c | how do coin dispensing machines know the difference between $1, $5, $10 etc. dollar bills? | Technology | explainlikeimfive | {
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"Paper money printed in the United States contains, in addition to a plethora of visible security features, some very elaborate methods to assist in automated denomination recognition. The primary method vending machines use to recognize the denomination of paper money is through a magnetic scan; paper currency is printed with magnetic ink, similar to the ink on the MICR line of a check, that makes it easily identifiable to machines with magnetic scanners. In addition, each denomination is marked with different fluorescent properties. Many vending machines and other machines that read paper currency use an ultraviolet light to scan the bill, read the fluorescent response and issue the appropriate credit. Read more: How Do Vending Machines Read Money? | URL_1 URL_0",
"There are bands of ink missing on the back of bills (if you look at them in IR light). The vending machines and coin dispensing machines work pretty much the same. As you insert a bill, the machine measures the brightness of reflected IR light, and can easily know which bill is being used based on how dark/light the bill gets. TL;DR The machines use IR light to detect the brightness of the bills; bills have different brightness"
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5vjmno | How do nature documentaries get such good sound? Do they use foley artists? | There's always a whole lot of behind-the-scenes fascination behind how nature documentaries get the "perfect shot", but none ever really address how they isolate the sound of whatever they're filming. Given that they typically use zoom lenses from long distances, in environments with lots of ambient noise, it seems like they must use some kind of foley artist. Does anyone know for sure? | Technology | explainlikeimfive | {
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"One legendary sound recorder for nature docs is Chris Watson. He used to be in Throbbing Gristle. Now he does the sound for David Attenborough. I once did a workshop in field recording with him. Getting sound to match nature documentaries is really an art all of it's own. They use a lot of tricks with different mics and setups but he tried not to fake sounds, they try and get them all in situ. For example, he told us about attaching contact mics, a type of microphone that picks up sound coursing through a solid object, to carcasses of animals and recording the sounds of vultures scraping off the flesh. Stuff like that..",
"I can't remember where I saw it but I remember reading that the sounds are usually recorded using captive animals and played on top of the footage. Can't be sure how accurate that is though.",
"Small time indie film maker here. I would imagine its very similar to setting up a film shoot in a small diner (or anywhere really). You scope out the spot. So for a lion documentary, you find a den where you know the lions will return. While they are gone, place microphones everywhere you can. Film crew sets up and lie in wait with telephoto lenses, and the microphones are recording all the time. Eventually, you strike gold when the animals return. Documentary takers don't just roam the wild hoping to find the animal they are looking for. They scope out the area, find the habitat, and setup.",
"Many of these are staged. So the spot where the animal lay is rigged with cameras/nearby microphobnes",
"They also can record using shotgun microphones that are kind of \"super directionnal\" microphones. Definition from Sennheiser: > \"Sometimes you cannot get closer to a sound than still pretty far away. A highly directional microphone captures it nonetheless. Perfectly clear, and in full detail. It is like building a sonic tunnel the sound is being pulled through toward the mic, protecting it from all the other unwanted noises so it doesn’t get lost in the din. As most audio professionals know Sennheiser shotgun microphones have always been extremely good at that.\""
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5vjnms | why don't we use a slingshot, like an aircraft carriers, to launch rockets and shuttles to space. Wouldn't that reduce the onboard fuel needs? | Technology | explainlikeimfive | {
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"Keep in mind that the catapult system on an aircraft carrier launches aircraft horizontally, not vertically. I'll get in to why that's important in a second. The current (steam) system on a carrier is **HUGE**. The majority of it is housed below deck and is not visible from the outside, but believe me it's large. That entire system, as well as the aircraft's own thrust, is used for takeoff. Both the aircraft thrust and the catapult combined get a 66,000 Lb F/A-18F from 0 to 145 knots in a few hundred feet. While that seems like a lot, that only equates to about 2.5Gs. Remember the thing I said earlier about how the catapult launches aircraft horizontally? Well when you turn the catapult vertical, now you're working against gravity. So your effective acceleration for a 66,000 Lb object (that is producing up to 44,000 lb of thrust itself) has now reduced to 1.5Gs. Add that average rockets weight much, much, much more than an F/A-18F super hornet, and now you have to scale the catapult to a **MUCH** larger size. The bottom line, it's unfeasible. Rocket engines produce such a good specific thrust as it is, manufacturing and maintaining the size of catapult that would be needed is more work than it's worth. P.s. I apologize for using round numbers as opposed to specifics. I'm on mobile and it's difficult to cite references and specific numbers. Source: have ridden catapult before. Can confirm, is fun."
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5vkftr | How many earth-like planets can aliens see in our solar system using our technology? | For example if Aliens lived on a planet around Alpha Centauri, how much would they be able to tell about our planets? & nbsp; Would they think the probability of life on earth and mars (and venus) are pretty much the same? Or would they say that mars is "probably" just a rock and earth has water and atmosphere? How many of our planets could they detect? Pluto < 3 ? Could they detect any of our signals (like radio) and know that there must be life? & nbsp; Edit: Assuming human-like aliens, no livin gas monsters Edit: Thank you guys! | Technology | explainlikeimfive | {
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"On one hand, they would probably have trouble seeing Earth, since we have several gas giants on the outer edge of our solar system; most Human technologies for detecting planets has to do with gravity's effects, and having large gas giants can obscure the smaller gravity wells of the inner planets. But, if we were a human-like alien, on an Earth-like planet, with Earth-like technologies looking at Earth's solar system from light-years away, and weren't put off by Jupiter and Saturn, they would see three earth-like planets in the habitable zone: Mars, Earth, and Venus. There's a slight possibility that their math may be inconclusive and detect a 4th planet just inside Jupiter's orbit or mis-measure Mars' size and orbit, due to the asteroid belt, but the asteroid belt doesn't have much mass (less than the moon) so it might not be an issue."
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5vkp0q | What exactly is, and the significance of, NASA's announcement today? | Technology | explainlikeimfive | {
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"NASA announced today the discovery of a small star system with \"Goldilocks zone\" planets orbiting the star. By this, I mean that all 7 planets are approximately the right distance away from the star to have liquid water or water ice and habitable temperatures on the surface. Additionally, the small size of the star system means that all 7 planets are very close together. In theory, this would be an ideal location to send a colony ship, and the interstellar colonists would have their pick of close worlds to explore. In the next year or so, this doesn't mean much to us. In roughly a year, we'll launch the James Webb space telescope, which will be powerful enough to get us much more data on the planets, including their atmospheric make-up. Long term, we should be able to at least get a probe to one of the world's by 2150 or so. They're only about 40 light-years away, which is practically local in the scale of interstellar travel.",
"The main reason is this: Astronomers are _really_ interested in learning about other planets and especially earthlike planets. Specifically, is Earth a one-off oddball or are there lots of earths out there? And is _life_ rare or common? At the present time, we can't find out much about planets in other solar systems. We can get estimates of how big they are and how far they are from their star, but that doesn't tell us much at all. Earth, Venus, Mars...from that kind of data you couldn't tell that one had life and which one it was. You can't even tell the difference between an airless rock like Mercury and a planet like Venus with a super thick atmosphere. You can only get the vaguest of ideas what other planets are like. But...if you can get an idea of the atmosphere of a planet, suddenly you can learn a whole lot more! Can this planet hold on to air or has it lost it all. Does it have a CO2 dominated atmosphere, or is there oxygen. Is there methane? Etc. Planets bearing life should pop right out because they have mixes of gasses that shouldn't coexist, like oxygen and methane. But you can also get some idea about the geology and composition of a planet. How do we do this? If a planet passes in front of a star, the star's light shines through the atmosphere. The atmosphere leaves an imprint on the light (you can think of it as the color of the atmosphere changing the color of the starlight) and this spectrum change can be measured. That will tell us what the atmosphere is made of. And that's the reason these planets are exciting. They are some of the closest planets known that are potentially earthlike _and_ pass in front of their star. These are the best chance yet we have to measure the atmosphere of planets...and not only that, but earthlike planets...and not only that, but there's a whole passel (7, with 3 in the habitable zone) of worlds to look at which means the odds of at least one of them showing something weird and interesting are higher. There's very good odds that we'll get a look at their atmospheric data within a couple of years, and if life is very common we might even see signs of it there! If you ask me that's pretty cool. **TL; DR:** Unless a Mars rover stumbles over a fossil in the next few months, this offers one of the best chances so far of spotting signs of life in the universe in the very near future. It's not certain at all that life will be there, but it's one of our first chances to really look.",
"This is only just the newest of NASA's great discoveries. They have an amazing track record of coming up with brilliant discoveries every February. I'm sure it's the result of having cleared their heads over the Christmas break, and nothing whatsoever to do with the fact that the federal budget usually gets submitted in the start of March.",
"In the near term? Not much. We have no way to reach those planets and none of our current telescopes have the resolution to get a good picture of them. In the longer term it's more evidence that virtually every star seems to have a planetary system and they're close enough that near-future telescopes can attempt to measure their atmospheric composition."
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5vktb2 | Where did the folder name "DCIM" come from for the names of the folders made by digital cameras? | Technology | explainlikeimfive | {
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"DCIM stands for (D)igital (C)amera (Im)ages. It's the name for the file folder digital cameras should store images, specified by the Japan Electronics and Information Technology Industries Association, which created the book of standards for digital camera file systems (called the Design rule for Camera File system). The DCIM folder is supposed to be the top folder. Each camera is supposed to have subfolders that start with three numbers and then up to five letters for the name of the manufacturer. So an iPhone might save pictures in DCIM/100APPLE. In your example, I'm guessing XPBH is an abbreviation for the camera maker. This is done so that you can keep images taken on different cameras separated in different folders within the DCIM directory.",
"It stands for Digital Camera IMages. It is part of the Design rule for Camera File system (DCF), which defines a standardize way for cameras to access memory cards. Directories have the format 999XXXXX, and most device models will use a preferred directory name. Files within the directory use the format XXXX9999, which again might be specific to the device.",
"i'm not sure about 100XPBH, but DCIM means digital camera images. the 100XPBH could have something to do with the type of camera."
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5vly5l | Why would a government want to invest in coal powered power plants as opposed to wind/solar? | Technology | explainlikeimfive | {
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"It shouldn't. There is no economic reason to be investing in coal at this point, as coal is more expensive, more dangerous, more damaging to the environment (and thus to your taxpayers), and less efficient, than more modern forms of energy production. The reason Trump wants to invest in this outmoded technology is because we in the United States have a whole belt of states whose economies have collapsed over the past several decades as coal companies steadily went out of business or got into other fields. Coal - producing states have been left behind by US economic policy. Trump promised to bring coal back to get those states' votes, and it worked. Those states gave him the election. The problem, of course, is that he can't make good on that promise. Coal company execs are on record saying their industry is doomed, it's not going to magically come back just because the president promised it would. Even if we removed all regulation on coal burning plants, it would still be more expensive than wind and solar in most areas of the country at this point due to massive advances in those fields. What needs to happen is an effort to reinvest in former coal producing areas so they can be part of the new energy economy. Factories producing solar panels could be encouraged to move there with the right federal encouragment, and that would provide new economic boosts which would actually survive into the modern era. Coal is an economic dead end.",
"The amount of power that coal plan produces can be easily controlled by the people running the plant. Need more power, burn more coal. Need less power, burn less coal. Wind and Solar on the other hand depend on nature. It's easy to scale down (cover your panels), but you can't make wind power if the wind isn't blowing. So, this brings us to the question of power storage. While I'm sure you've heard that wind / solar is cheaper than coal, that's only when the wind is blowing or the sun is shining. Once you factor in power storage (compressed air, gravity storage, battery, etc...) to power your city when on a calm windless night, it becomes a lot more expensive. So, until we solve the storage problem, coal / oil / gas plants will always have a place. Then, you have to bring in geography. A train / truck will move coal from one place to another easily. You can't move sunshine up to Alaska for example. You get what you get. *edit: typo",
"Because they're trying to prop up a failing industry to save jobs. Because that's easier than finding real solutions to help the people working in those outdated jobs get retrained to do something else.",
"Unlike solar or wind, you can make a crap-load of power with coal. I've worked in coal fired plants that can easily pump out 350 to 600+ MW of power. I think the largest planned solar site might make a 100MW on a good day. Coal is dirty and dangerous, but it will put the lights on at night.",
"Wind and Solar is not stable production. You generate no power when there is no wind with wind turbines. You generate no power when there is no sun with solar. And there is not an efficient way to store the power they generate for future use at the scale needed for the power grid yet. As such solar and wind power is great supplemental power but you still need a primary power source that is more controllable and reliable. Those are currently nuclear, coal, diesel, hydro-electric, and natural gas. Edit(And Geothermal if you are near a volcano).",
"Right now, the best bang for the buck is natural gas, as we are producing more than we ever have in history (byproduct of fracking for oil) and so all new power plants probably will use this technology. Power companies will use whatever is the cheapest and most reliable. Wind and solar are neither of those... yet. Plus as other posters have mentioned, there are storage, weather and geography problems with both wind and solar. Plus there is the environmental impact. What, you didn't think there was any environmental impact from wind or solar? Think again: URL_0 So no matter what technology, someone, somewhere is gonna be screaming about something.",
"Corruption and populism. Modern US politics is largely about getting re-elected. Anyone trying to get elected in coal country had better be selling hope. To a people whose fathers and grandfathers made good union money with a pension, nice house and two cars, hope looks a lot like a return to the past. So that's what he peddles: he tells the voter that unions are the reason coal is gone. He tells her that he's been working to bring coal back but it's hard work and he needs another term. He tells her that, if she works hard and cheap, prays every night and, mostly, votes his slate, coal *will* be back."
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5vlzx2 | With the new finding of the seven earth sized planets, how will humans determine whether there is life on them and how long would it take to do? | Technology | explainlikeimfive | {
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"The planets are 39 light years away, so getting a probe or something over there would take quite hundreds of years or more with our current tech at it's best. Fortunately, we don't have to do that. The best thing we can do is to look for signs of the kinds of gases life makes: oxygen, carbon dioxide, methane. When Trappist-1's light shines through the atmosphere of one of the planets, we can watch for which spectrums of light are and aren't filtered out by the atmosphere, which tell us what types of gases are in it. This is of course not SUPER conclusive, but we'll be able to get proper answers on it within the decade. And there's plenty of other exoplanets out there to try the same tricks on. We've been discovering exoplanets at an enormous rate lately, which is amazing since it took until 1992 to fundamentally find and prove the existence of planets around other stars, and now we've got bucketfuls of data about 'em to sort through and start oogling."
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5vmcia | How does Google know that you get the letters correct in a captcha! if they were designed so that computers can't read them? | Technology | explainlikeimfive | {
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"There are two(ish) main types of captcha: 1) Computer generated word images. In this case, it's obvious why the computer can know if you've typed it in correctly. 2) Not computer generated captcha. This is the kind that comes with two word-images. Only one of these words is actually the human test. The other one is there so that the computer learns what most people write it out as. Once enough people have written an identical answer for that word, it can become one of the testing word-images. So during a particular captcha entry, you are simultaneously proving you're a human, and teaching the computer what a particular word-image says. Interestingly, some captchas incorporate words from scanned books that the google intelligence can't decipher. These are the non-test words. When answering these captchas, you are both helping create a new test word-image, and helping digitize books!",
"The same capatcha is often given to many users, and for Google's two-word recapatcha, one of the words is a known by the computer, the other is unknown"
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5vmera | Can SETI listen to radio activity from TRAPPIST-1? | Technology | explainlikeimfive | {
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"They can. May not be worthwhile, though, as from what I recall the system is pretty young (possibly less than a billion years old). We can also send a signal at them directly, although it'd take 40 years for the signal to reach them, and another 40 years for their response (if any) to get back. Interestingly enough, on the (**highly** unlikely) chance that they managed to hear the Berlin Olympic broadcast and figure out it was coming from our system, their response could be coming any day now.",
"Sure. But keep in mind that system is 40 light years away. You'd need a pretty substantial amount of power to transmit a signal over that distance. If you are sending an omnidirectional signal, it'll attenuate (not sure if that's the right word) at the same rate as gravity, a-la the inverse square law due to the spherical expansion of the signal. They might be able to use a directional or focused signal if they knew we were here. If they can do those things with the right amount of power, yeah, we'd be able to hear them. But what we're hearing is 40 years old."
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5vni9l | Why do people tend to behave more poorly on Facebook despite a complete lack of anonymity? | I know this is **extremely generalized**, but, why is it that people tend to behave worse on Facebook even though your real identity is literally on display? You'd think that that fact alone would cause people to act completely differently. Compare that to a site like Reddit; people here have the ability to be completely anonymous and have multiple accounts, and yet most seem to follow very particular expectations and social rules. Edit: Grammar | Technology | explainlikeimfive | {
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"Anonymity is a very powerful promoter of bad behavior, but it is not the only one. Two things that help promote good behavior is consequences and our natural empathy. On facebook there are somewhat limited consequences, especially when interacting with strangers. Tom Jones from Hawaii may be able to see that you are Cindy Feldman from Florida, but there may not be any meaningful way that he can retaliate against you being a jerk with that information. To the second point, when you interact face to face there are powerful factors that are at play in most people. Seeing actual other people in pain and suffering can cause mirrored emotions ourselves. This natural empathy is short circuited not by our own anonymity, but by the anonymity of our victim. They are a random avatar on the computer screen, not a breathing person whose mom is in the hospital, whose face is twisting in pain at an insult, who just stopped to help us jump our car, etc. Faceboom turns the wold into a giant game of Sims where others are just AI that we can interact with.",
"From my experience, I believe there are two very distinct clades of people on Facebook. You have those people who abstain from politics altogether (like myself) and then you have the rest who do the exact opposite and make Facebook their political soapbox. Why does clade B behave more poorly than you might otherwise think? It's because all of those friends who disagree with them politically or those friends who fall into clade A defriended them a long time ago and thus they know full well that they're talking to a tribal audience! This results in an echo chamber situation. URL_0 Rush Limbaugh, Sean Hannity etc aren't successful because they aim for inclusiveness, they are successful because they have a core audience whose beliefs chime with their own. And as their careers took off, they learned that more invective and more bombast meant more positive feedback from their headbanging crowds. This is exactly what happened with Donald Trump, whether you agree with him or not. Their careers are nothing but long positive feedback loops of frothy anger and rage aimed at one side of the political divide. Thus, you have Facebook and people acting like fools. My mom fits this bill to a T. She says the most vile things on Facebook sometimes and she no longer has any leftward leaning friends to smack her down a peg. So she's become conditioned to only say things which earn her \"RIGHT ON, BRO\"S and \"FUCK YEAH\"s from whatever friends she has left. So sad.",
"I thought it was just because Facebook was for everyone and Reddit attracted a less stupid/aggressive demographic."
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5vok7v | Why are radios so complicated? Why can't someone just plug an antenna into a speaker or oscilloscope and catch a frequency? | Basically, I was wondering what all of the components and chips inside of a radio are for | Technology | explainlikeimfive | {
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"You very nearly can just plug an antenna into a speaker and catch a frequency. What you're describing is a 'crystal set' and operates purely on the radio waves without the need for it's own power source. Crystal sets were popular in the 'olden days' as kits for children/introducing people to electronics. In addition to the speaker and antenna you need a couple of extra pieces in order to adjust the frequency you want to listen to. Modern devices contain a lot of extra components that handle amplification of the signal, digital displays, and other additional features of the radio. URL_0",
"Just as you hear with your ears when you hear a noise, voice or music, a radio works on the same principle. In order for your ears to hear a sound the vibrations are transferred through a medium, in this case air. Sound you get out of a radio works in a similar fashion. In this case the 'medium' is a radio wave. What a radio will do is encode the 'information' to be transmitted onto a specific frequency of electromagnetic radiation. I'll leave out the fancy mathematics but essentially all the components of a modern radio will combine the specific frequency of the carrier medium with the 'information' (a song for example). This is then fed into a radio antenna that transmits that combined electromagnetic signal which a radio will pick up if it's tuned to the correct carrier frequency. There are 3 basic ways that you can encode the information you wish to transmit onto an electromagnetic wave. **Amplitude modulation**, **Frequency modulation** or **phase shift modulation**. There are more complicated variations of those but i'll stick with AM and FM as they are the easiest to convey. AM will 'modulate' the carrier frequency with the information by increasing or decreasing the amplitude, that is to say the maximum height the signal will be if you looked at it on oscilloscope. FM works by modulating the frequency instead which requires less power to transmit than AM and allows for more information to be encoded per channel than AM for reasons that get complicated. **TL;DR** AM is simple so a wire of sufficient length will pick up the frequency of a channel potentially transmitting information. FM is more complicated and also amplifying circuits make up the bulk of an FM receiver.",
"Radios have to two things: * latch on to a single frequency while eliminating all the others * amplify that very weak signal into something audible That's the part that is going on between antenna and speaker."
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5vp4sv | How could scientists confirm life exists on another planet "very soon"? | Technology | explainlikeimfive | {
"a_id": [
"de3scoz"
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"text": [
"If they detect certain gases in significant amounts (specifically methane and oxygen) this would be **very** suggestive of organic chemistry. These gases don't tend to stick around before turning into something else so their presence would suggest an active process that is creating them. There are some non-organic processes that can create them but these would usually be short lived or only produce small amounts. Organic chemistry produces them in large amounts here on earth however so if we see that happening somewhere else then it would be suggestive of earth-like organic chemistry."
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5vpvoj | What actually happens when we shut a website down with the "Reddit hug of death"? | Technology | explainlikeimfive | {
"a_id": [
"de3utbl"
],
"text": [
"The server that the website is hosted on is bombarded with too many requests at the same time for that website. A great analogy for this is a mail room. A mail works fine when there aren't that many people sending mail. But when lots of people try to send their mail at the same time, the whole system begins to slow down. Increase the size of the mail room, and it takes more mail to slow it down. But people will sometimes link to websites that have a small server, or 'mail room', and so it can't deal with the large amount of traffic - or mail - that is coming it's way."
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5vq9vo | How interruptive are the effects of Wireless and Electromagnetic waves on living organisms? | I recently had the wild realization that for the most part, the vast majority of the population lives in neighborhoods and houses surrounded to the brim with Power-lines and loads of gadgets inside. Are living organisms (such as forests or animals) affected by these waves and if so what exactly is happening? Have there been any experiments to show that Wi-Fi hampers plant growth? | Technology | explainlikeimfive | {
"a_id": [
"de3xhce"
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"text": [
"It's important to realize even without gadgets, powerlines, and wi-fi, you are *still* and *always* being bombarded by electromagnetic waves. Essentially every object in the universe is emitting electromagnetic radiation, including you, rocks, televisions, air molecules, toilets, corn (both harvested and unharvested), and Rex, your dog. 'Wireless' is simply a part of this spectrum, not some other thing. This radiation is the non-ionizing kind. It can cause heating when absorbed, and if an organism absorbs enough (like grabbing hold of a radar or putting yourself in a microwave) cause burn damage."
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4
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5vqye0 | How did old games and computers display large numbers? | For instance, the NES was 8-bit, and 8-bit integers can only be between 0-255. Yet the score (in say Super Mario Brothers) can be into the hundreds of thousands, something even a 16-bit integer can't handle. Pac-Man also let you score up to over 3 million even though the level counter would break at level 256. | Technology | explainlikeimfive | {
"a_id": [
"de43km7",
"de43ipi",
"de4ez02",
"de433yw"
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"The same way you write and do math with numbers larger than 9 despite the fact the only digits you have to work with are 0-9, you chain them together. 8-bit microprocessors are designed with instructions that make doing operations with data made up of multiple bytes easy. So for example the \"add\" instruction included a 'carry' flag, so if you had two 16-bit numbers X2-X1 and Y2-Y1 (where X2, X1, Y2, Y1 all are 8-bit numbers) added X1+Y1 and got something larger than 255 it would set the carry flag. Then when you added X2+Y2 the processor would add +1 if the carry flag was set. This means you just need to iterate your add/subtract/whatever instruction through the 8-bit numbers that make up your 16-bit (or 32-bit, or whatever) number. Like I suggested at the beginning, this the same approach you probably take to doing most math. Do the 'ones digits', do the 'tens' digits, do the 'hundreds' digits...etc.",
"When a system is 8 bit that means that the processor can only handle 8 bits at a time. However it is possible to calculate with bigger number by breaking it into multiple smaller numbers. Just like an 8 bit computer can only deal with numbers between 0 and 255 humans can only deal with numbers between 0 and 10. However if I gave you 3890+4978 you would be able to calculate it by adding one digit from each number at a time. A processor have the same capability so it can in theory do maths on numbers as big as the machine have room for. However limiting the space available for each number to a fixed size makes the coding much simpler.",
"In the same way modern computers do it: by storing large numbers in several consecutive bytes in memory. The only difference is that modern CPUs have instructions to perform arithmetic with large numbers natively. Older CPUs didn't, so we have to perform those operations by running a short software routine. As an example, the Z80 CPU can add/subtract 16-bit numbers. If you need to, for example, add two 32-bit numbers you would start by adding the two low words using the ADD instruction. If the result doesn't fit in 16 bits then a 1-bit flag inside the CPU (called C for \"carry\") turns on. Next you add the two high words using the ADC instruction, which adds up two values and the C flag. If you have a larger number (56-bit, 64-bit, 4096-bit...) then you just keep adding each pair of words using ADC. Source: I grew up using MSX computers and still use them today. I've done my fair share of programming in Z80 assembler.",
"Just split it up into several bytes. 255 255 255 gives you quite a high score. Sometimes it's just that simple :)"
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5vr15v | How do Bluetooth IEMS/Headphones actually transmit sound without any physical connection between the IEM and device it is paired with? | Technology | explainlikeimfive | {
"a_id": [
"de45jas"
],
"text": [
"The sound is converted into a radio wave and broadcast to the receiver, which then receives the waves and converts them back into data. This data could be sound, or it could be any other kind of data you'd like to send. Anything and everything \"wireless\" works in this way. What makes Bluetooth different from FM radio is the frequency it uses, and the way it encodes data. Bluetooth uses a much higher frequency than your car radio, which means it has a much shorter effective range, but also means it can send more data at once."
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5vr6xm | How do headphones work? | Technology | explainlikeimfive | {
"a_id": [
"de454n7",
"de4zjh1"
],
"text": [
"Pretty basic. The audio plug is called a TRS (or TRRS, it depends). The connector has three leads: \"left\" and \"right\" voltage signal and ground. You can see this for yourself by counting the number of sections on each audio plug (the sections are divided by bands). The two \"positive\" leads (the left and right signals) run to the left and right audio speakers, which are in your headphones. The speakers convert the electrical signal into vibration, which is sound. I have taken apart many audio cables before, but I can never recall the proper order of TRS plugs. I think that the first section, which is the tip of the plug, is the lead for the LEFT SPEAKER and the second section (the \"ring\") is the RIGHT SPEAKER lead, which leaves the final one (the \"sleeve\") as GROUND. See this diagram: URL_0 For TRRS audio plugs, there is an additional section to fit a microphone lead also.",
"In addition to what /u/lonesentinel19 said, a headphone works like a speaker. In a ridiculously simplified explanation: A fabric cone is glued onto a magnet, and a wire passes over the magnet. As electricity is passed through the wire, it generates a magnetic field which moves the magnet by attracting or repelling it, which moves the cone thats glued to it, which moves the air around your ear, which is what sound is. Microphones work in the reverse, you blow into a fabric cone attached to a magnet that moves up and down and generates electrical current in a wire, which travels through a cable to your speaker wire, which moves a magnet attached to your speaker cone which moves air around you generating sound. Electromagnetism is beautiful."
],
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"https://i0.wp.com/www.circuitbasics.com/wp-content/uploads/2015/03/TRS-Pinout.png"
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5vrh4h | Why in most computer calculations 1/(0.2-0.1-0.1) gives the correct result but 1/(0.3-0.1-0.1-0.1) doesn't? | In all programming languages that I've tested, in MS Excel, in Google Sheets, in Windows and MacOS caluculators, in Wolfram and so on, the calculation `1/(0.2-0.1-0.1)` give an error or "infinity", but the calculation `1/(0.3-0.1-0.1-0.1)` gives a number ~`-3.6E16` and `1/(0.4-0.1-0.1-0.1-0.1)` gives the same number only positive? Mathematically, they should all give the same result. Something in floating point calculation is "wrong". | Technology | explainlikeimfive | {
"a_id": [
"de48bhg",
"de48v9j",
"de4jsnk"
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"text": [
"The problem is that it's doing the calculations in binary and can only store a limited number of digits. 0.1 can't be stored exactly in binary, in the same way as 1/3 can't stored exactly in decimal. You get rounding errors similar to the problem you'd have dealing with 1/3 in decimal: 1 - 0.333333 - 0.333333 - 0.333333 = 0.000001",
"When represented in binary, 1/10th does not have an exact representation, much like 1/3 in decimal. If you represented 1/3 as 0.333, 1 - (0.333 + 0.333 + 0.333) = 0.001, not 0. You are basically doing that, but in binary. > Mathematically, they should all give the same result. Something in floating point calculation is \"wrong\". Actually, no. Floating point was designed to represent approximate values, not exact ones. If you measure you drive to work, you might come up with 10.22 miles. But that doesn't mean *exactly* 10.22, it means 10.22 with a reasonable margin of error. That's the kind of value that float point is used for, and managing that error is your responsibility. In your case, 0.2 doesn't mean *exactly* 0.2, it means a measured value we are rounding to 0.2. If you need exact representation, you need to use a different data type than floating point, like integers or rationals.",
"rounding errors. Basically, when you store a decimal number in a computer, it is stored as a floating point number. That means that the computer stores a certain number of significant digits, and an exponent. If the number has more than a certain number of significant digits, then it truncates the number and they are lost. eg: if a computer stores 8 significant digits, then 1.2345678 is stored as 12345678 10e-7, but 1.23456789 would lose the 9 and *also* be stored as 12345678 10e-7 because it only stores 8 significant digits. The result you are getting is a very large number, but that is what one should expect from dividing something by a very small number Basically, however the math interpreter in the program parses that math problem you posed works, it is getting a number with more significant digits than its floating point variable stores, and truncating the number, which leads to a VERY small, non zero number- normally, this wouldn't be an issue at all because that error should be drowned out by the rest of the result, (who cares if the result is 1.2345678 or 1.23456789, either way it's close enough for most engineering purposes), but since you're trying to achieve a 1/0 calculation, you need to exactly return to 0 and that minor error is screwing up the results noticeably. That said, I pulled up windows calculator to see if I could reproduce the error there, and I could not, so I think it's more a bug with those programs. However, I could not reproduce the error in Wolfram alpha, all of the above produced infinity as their result"
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5vryas | iPhones regularly start to malfunction after 2-3 years of use. Why is this not considered a bad product at $700-800 MSRP? | Technology | explainlikeimfive | {
"a_id": [
"de4d67s",
"de4dis7"
],
"text": [
"What sorts of malfunctions are people experiencing? I'm not trying to be snarky; I honestly didn't realize there were problems with the products. We (my family) bought 3 iphone 5s in December ~~2102~~ 2012 (thanks, /u/naf623, for pointing out my error!) and haven't have one bit of trouble with any of them. 4 years of constant daily use by all three and they're still all going strong. Have we just been lucky? Heh I hope I don't jinx us with this post!",
"Do you have any stats/articles/info to back up your claim that iPhones 'regularly' malfunction after 2-3 years? From what I can see, Apple does a great job supporting devices through software updates for years after release. You can have phones that are 3-5 years old that are not only functioning properly but updated to include new features and, perhaps more importantly, security protocols. It's my opinion they have a better build quality than most competitors as well. They also have an integrated support system so if your phone does start to malfunction you don't necessarily have to deal with a call centre or your carrier's sales staff, but can bring it into an Apple Store. If I'm spending 700-800$ (or more, a lot more) on my phone, do I want: **Google Pixel**, which I can't buy/return in person, comes with software/call centre support, and might only be eligible for Android updates for 18-24 months, or: **iPhone**, which I can buy/return in person, get support in person, and I know will be continuously updated for years to come?"
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5vs1wp | What's so special about the AMD Ryzen | Specifically why did it take so long to catch up to intel and how did they do it? | Technology | explainlikeimfive | {
"a_id": [
"de4e0pg"
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"text": [
"Someone will probably come along and give you a longer more detailed explanation but the TLDR version is: Bulldozer cores were designed for high frequencies and multithreading at the sacrifice of ipc(instructions per cycle). Bulldozer's IPC was actually considerably lower than AMD's previous architecture. It's a common misconception that AMD couldn't afford to build a good cpu. That wasn't the case, they just designed the wrong cpu for the market. So, while AMD did improve upon Bulldozer as best they could, they, almost, immediately began working on Zen. So the thing with Intel is that they really haven't designed a new architecture since Ivy bridge (or maybe it was core 2), they've just been making minor improvements and node shrinks each year. That couldn't be done with bulldozer, it had to be redesigned from the ground up, and building a new cpu architecture takes years. Now, what's so different about Zen? Well, Bulldozer cores aren't really cores. You could more accurately describe them as \"ALU Clusters\" (as a friend of mine puts it). Zen cpu cores are actual cores. [this]( URL_0 ) will help visualize it. On the left, is a bulldozer module (2 bulldozer cores). On the right is a single Zen core."
],
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5vs78d | The first SHA1 collision by Google | Technology | explainlikeimfive | {
"a_id": [
"de4f37n"
],
"text": [
"SHA1 is a hash algorithm. It takes some data, runs it through complicated math, and gets something like a fingerprint. You always get the same fingerprint for the same data, but you can't get the data from the fingerprint. SHA1 only produces a fingerprint of 160 bits (1's and 0's). That's like 40 hexadecimal numbers long. There are only so many combinations of 160 bits. That means sometimes different data will have the same fingerprint. Ideally, it's should be nearly impossible to get a specific fingerprint *on purpose*. If you see a fingerprint, you shouldn't be able to figure out what data you need to result in that fingerprint. The only way would be to keep trying random data over and over until it matches. The guys at Google have done math wizardry to come up with a shortcut. Now it takes less time to find a matching fingerprint. Why does this matter? Let's say your password is \"Dog123\" and the hash is \"ABCDF\". Computers usually store the hash of a password and just compare it to the hash of what you typed in. Instead of trying all possible passwords until they get \"Dog123\", they can cheat and find out \"ILikeDogs321\" has the same hash. It's not your password, but since your computer only compares the hash it still works. You might also use a hash to verify the software you downloaded is the software you wanted. This method potentially allows someone like the NSA to insert a virus into software, but make it appear as if it's not been tampered with since the hashes match."
],
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5vsgyl | Will there be a point of video games graphics becoming so advanced that the technology will plateau and the human eye won't be able to perceive any further improvements? | Technology | explainlikeimfive | {
"a_id": [
"de4k46o"
],
"text": [
"Perhaps, but we are still far off from that point. Our brains are wired to notice all kinds of details about lighting, things that tend to be computationally intensive to simulate. Hair is still very hard to render believably in real time, for another good example."
],
"score": [
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5vsnqq | Why aren't computers and other electronic devices instant, why is there a 'loading' time? | Technology | explainlikeimfive | {
"a_id": [
"de4izxq",
"de4q5yv"
],
"text": [
"because of how electronics work at the basic level. everything is synced to a metronome called the processor clock. the entire orchestra of several billion transitors operates on the processor clock's conductor timing. when processor clock says your data's ready to read, then read, not before. at the electrical level, it's because electricity doesn't flow instantly. it takes time to charge a circuit until the voltage reads more than 1.5volts, reading as a 1. and time to discharge a circuits so the voltage is less than 0.5volts reading a 0.",
"All those electrons still need time to move and that stacks up. An instant is still a measure of time. Now stack that up. Instants become seconds- minutes - hours."
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5vst7l | What's the point of the "press any button to continue" screen in some video games, why not just boot to the main menu? | Technology | explainlikeimfive | {
"a_id": [
"de4k6fg",
"de4nces",
"de4o8zp"
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"text": [
"Artistically maybe they wanted to show a \"clean\" screen without a bunch of menu options on it. But there's really no technical reason to have one. A bunch of games boot directly to the main menu. A better question is why are there unskippable splash screens? And the answer to that is that the game is loading in the background, sometimes the menu itself is loading in the background (ex: Just Cause 3, though for a cool reason, because there is no transition from menu to game when you're ready to play, the menu is created from your save file progress... look up a video of it, you'll understand)",
"[This is the thread]( URL_0 ) from when this was asked last month. I particularly like the answers from /u/PrionBacon and /u/white_nerdy",
"Some games use(d) it for deciding player order. The controller that first gave input would be player 1, for example, and could then navigate the menues w/o being bothered by anoying siblings."
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5vtmdz | Information Tech professionals of Reddit... How can you tell what people are using their work computers for? | Someone in my office got fired today for unethical use of their work computer. How does IT know what is going on? Does clearing search history/browsing info/ cookies/ ect really do anything? What information can IT departments tell about computers and how? | Technology | explainlikeimfive | {
"a_id": [
"de4rf06",
"de4sfyu"
],
"text": [
"All your internet traffic is sent through a device called a router. That router keeps logs of what IP address (a unique identifier for each computer on the network) performs what actions and what traffic goes through it. If a known viral program is accessing the internet through your computer, we get alerts. If you're visiting websites that you shouldn't be, we get alerts. The history on your browser has nothing to do with it.",
"In my last job we had software which would scan the machine for any images which may have been porn. We also got a monthly report on the web monitoring software which would highlight questionable websites visited, time spent on youtube etc. ELI5 - IT departments can monitor everything you do on your computer, it just depends on the company policy how indepth the IT admins check it."
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5vucp9 | Could two different passwords have the same hash? Would this seriously affect password security? | Technology | explainlikeimfive | {
"a_id": [
"de4xsua"
],
"text": [
"Yes, this is called a \"hash collision.\" How common collisions are depend on the algorithm. With typical algorithms it's quite unlikely that two users would actually pick passwords that end up with the same hash. The real problem with collisions is that it makes it much easier to crack passwords: there are multiple correct solutions that correspond to a stolen hash, instead of just one. Hashing algorithms where collisions are relatively frequent are not safe for use in password security."
],
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5vuvom | Why do computers slow down significantly over a few years compared to when it was purchased if hardly anything has been downloaded? | Technology | explainlikeimfive | {
"a_id": [
"de53gpu",
"de556rm"
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"text": [
"They do and they don't. They do in the sense that if you use a computer enough you will eventually create loads of temp files, startup programs, etc. This causes things to slow down as the computer has more to load. A fresh install of the operating system can fix this if that's the issue. They don't as in its a perception thing. You may use other devices and computers that come out with newer better hardware. Then you go back to the old computer and it may feel slow to what you're used to. There are other things such as driver support ending so they stop optimizing certain things. Another thing is as features get added to programs it may take more processing power to run those features.",
"As a rule, the hardware will always run at exactly same speed, so if the computer is slower its must be because its being asked to do more in software. There are a few exceptions to that rule, where failing hardware can in fact slow down a computer but not cause it to crash or report errors, but they're uncommon to say the least. Now as to what additional tasks the computer is doing in software that would cause it to be slower, you'd have to know the specific system to answer. But even if you didn't explicitly download something, one of your apps or even the OS itself could have added a hundreds of megabytes of software to the hard drive since modern systems pretty much update themselves all the time now."
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5vuzsu | why does the max volume on my device vary so much based on what it is playing? | For instance between one youtube video and another, the max volume can be very quiet or decently loud. Why can't the quiet video sound just as loud? | Technology | explainlikeimfive | {
"a_id": [
"de53k5p"
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"text": [
"It is entirely dependent on the volume level used when mastering the video/song/etc. Some use a standard 'volume'. This is why all songs on iTunes are almost identical volume when they play at the same level on your phone. However, YouTube doesn't require this and as such some videos published retain the low 'master' volume used originally in the editing software. A good example of someone abusing this principle is the obnoxious vines that master the volume of a vine initially low so you turn your device up - then increase the master volume to make it seem extremely loud all the sudden on the device."
],
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5vvg3e | How does getting rid of Net Neutrality improve competition in a way that benefits the consumer? | I've been seeing this argument from the dawn of time and never understood it. | Technology | explainlikeimfive | {
"a_id": [
"de58p8b",
"de579od",
"de5aau6",
"de5a919",
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"text": [
"Getting rid of Net Neutrality does NOT benefit the consumer. CGP Grey have made a 3½ minute video about it, that is vary easy to understand. URL_0",
"This question cannot be answered because the premise is false. It does not improve competition in a way that benefits the consumer.",
"Lets say you watch pay for a subscription to stream movies on website A, but website A is lacking in the anime department. You figure there are a lot of people like you, so you make your own website, B, that for a fee has all the anime you could ever want. You negotiate with the providers that own the rights to the anime, make an experience that's easy to use/find titles, buy a domain, advertise, you're set! Except...how do people get to your site? The internet. Under net neutrality, the internet provider *has* to treat websites the same (load them all the same rate, etc.), so both website A and B load just as fast (way oversimplifying, there is some nuance with back end servers and all that), so in theory, all the anime fans can say \"hey B is super great it has all the anime that I was missing with A!\" This then would cause A to realize that B is taking customers from them because they don't have anime, and A adds anime titles to compete for those customers back. Launches a big advertising campaign, the works. B obviously doesn't want to fall behind, so it adds live streaming of *new* anime as it airs in Japan for diehard fans. And back and forth, constantly competing for customers in an arms race. Customer wins here because no matter which option they choose, the other will always be trying to improve to get that customer. Now, the scenario without net neutrality: Internet providers become virtual gatekeepers. They *can* treat websites differently, and say \"hey, A is willing to pay us $1M per year so we load their website at full speed, we'll do that.\" Meanwhile, B is trying to gain traction and make money, and can't afford to pay $1M to Big Internet. So what happens? Big Internet says \"bummer...you're on our 'so slow dial up would've been a better choice but it'll still load eventually' speed if you don't pay up.\" And Big Internet isn't a bad guy for doing this! Yes, its totally exploiting their position of power, but literally *every* company would do this, simple economics. If a company *can* and *will* pay for preferential treatment, profit off of it. So then, what happens in the long run? Customers think B sucks. They say \"it loads so slow!\" or \"Who cares if its a live stream if I can't get it to open before next week?\" and they abandon the site. A then gets all the traffic and, yay A will keep catering to these customers! Right? Wrong. Now that customers essentially don't have a choice (site that actually loads, vs one that's slower than Verizon to adopt unlimited data), A has no incentive to improve its selection. They essentially become a monopoly which, like Big Internet, can do things that make sense economically, but are overall dick moves. The idea with net neutrality is that it protects the \"little guys.\" And what might be \"little\" now may not be in a few years. Amazon? Started as a book store. Now it sells everything. But if there were another, richer book website when Amazon started up (call it \"Nile\") and net neutrality weren't in place, Amazon never would've gotten off the ground and we'd probably have a mediocre Nile experience with books at overall meh prices. Getting rid of net neutrality **doesn't** improve competition. It hinders it. Those arguments are propaganda by Big Internet that want to line their pockets more. They'll say things like \"net neutrality forces us to give bad service\" and all that, which simply isn't true. What ***is*** true is that ***without*** net neutrality, they could give the best service only to the highest bidders, leaving new sites in the dust without a chance to ever compete. **TL;DR:** The only people saying getting rid of net neutrality is a net positive for the consumer are part of Big Internet (and the politicians they fund). It's like TurboTax saying a complicated tax code is good for US Citizens, when in reality it's good only for them.",
"It does not benefit the consumer. It arguably hurts companies creating content. It does, however, benefit ISPs--and it does so bigly. This is worth writing or calling your members of congress (State AND National).",
"Getting rid of net neutrality benefits the large actors with big bank accounts. This will only be detrimental to consumers, and the development of internet as a whole."
],
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5vwhel | what did CloudBleed take or break, and how is it used maliciously? | Technology | explainlikeimfive | {
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"For some domains (for example URL_1 ) Cloudflare sits between you and the actual website. This way they can prevent websites from attacks and also make sure the website loads fast on your laptop, because they always have a server nearby. The problem is that Cloudflare made a mistake in their code, which meant that private communication that should have stayed between you and the website you were visiting was shown to others. This only happened with a small percentage of traffic to Cloudflare, but since it is used so much, it could leak private information of up to 200.000 requests per day. This private information was shown to random other people connecting to Cloudflare, also to crawlers from searchengines like google. Crawlers store what they find on the internet so people can search through it. And that is how they found out. A guy at Google noticed all this private info and notified Cloudflare. Cloudflare fixed the problem in a few hours. Even though the leak is fixed you should still change your passwords, because Cloudflare was leaking for more than 5 months and searchengines or other people may have stored your password and other private that you've sent to these compromised websites. ~~By the way: URL_0 wasn't effected. So you only need to change that if you used it's password elsewhere. In which case you should change it, never re-use passwords.~~ Reddit _has_ used Cloudflare until October 2016, so it is recommended to also change your Reddit password.",
"I have a basic understanding of the interworkings of this, but I do want to preface this by saying that I am no expert, this is not my field of expertise, etc. The following is how I understand it, and I welcome anyone to correct me where I am wrong. This is also as best of a ELI5 I can give, so will be oversimplifying some aspects. Here is how I understand it: Let's say I am running a server (point C) that serves my website, not using cloudflare, and I have my own tls certificate that encrypts communication between it and you (point A). Anyone snooping on you only sees gibberish that only my server knows how to decrypt, use, and then send back the encrypted response that still looks like gibberish to anyone snooping, but now you know how to decrypt and use. It's a direct connection between point A and C. Now down the road I decide to start using cloudflare, which becomes point B, and uses their own encryption certificate, and also adds an extra layer of caching. For the caching side, you request a page from my site, my server does all the computations to figure out what should be sent back, and then sends it. The next 50 people after you are trying to access the same page, so instead of my server doing the same computations 50 more times to send it back to each of those people, cloudflare saves what it sent to you, and then sends that same thing to them instead of asking my server to do the work. So when you made your first request to my server, instead of calling it directly from point A to point C, and using my servers tls certificate to encrypt our communication, you are now calling from point A to point B using cloudflare's tls certificate. Being that cloudflare's and my server's encryption keys are different, cloudflair can't just volley that information to my server. Cloudflair has to decrypt what you sent it, and then use my server's tls certificate to encrypt communication between point B and point C. All in all, should work great right? All communication is still gibberish no matter where someone is trying to intercept it. A to B is encrypted, B to C is encrypted, and the same on the way back from C to B to A. The problem is when that after that encrypted communication from A to B is sent, B (Cloudflare) has to decrypt it and then it gets encrypted again using a different cert to go from B to C. While it's at B after being decrypted and in plain text, it is stored in B's memory. Well B's memory was leaking out like a water sprinkler. B isn't only caching my site, but hundreds of thousand other sites, ready to send it back to all of the other users asking for websites that are using cloudflare. So that sensitive information that you knew was encrypted, and sent to my site proxied through cloudflare, is now leaking into the cached pages being sent back to everyone else. This data doesn't just appear somewhere on the page inside of the browser, so the person looking at the page has no idea that they were just given this information they didn't ask for. But if you go digging through the raw data that was sent, then you can see it if you know what you are looking for. This in itself is already a security risk, then you have web crawlers. Search engines, like Google, send \"robots\" to look through your pages and cache the data on their end. This is how you can see a snippet of a website's content in googles search results page right below the link to go there. Well google actually caches the entire data of the page, so if your sensitive data that you sent to my server was then water sprinkled on all of these other pages cached at cloudflare's level, and google's robot crawler was then sent that data and cached it on googles end, anyone can see it by looking at google's cached version of that data. The scary part of this all is that there is no way of telling who was sent the cached versions of other sites that your information was water sprinkled onto. There is no way of knowing how many web crawlers there are out there, who owns them, whether they still have all of that data saved somewhere that they can now go back and analyze since this has been made public, even after cloudflare fixed the issue to plug the water sprinkler. This is why, especially for the ones that use the same password for everything, you need to change passwords for anything and everything related with the internet. This really is no joke, is probably the biggest security hole in the history of the internet, and should not be taken lightly. The water has already been sprayed and the sprinkler can't suck it back in, all anyone can do is hope their information has evaporated before someone has the chance to play in it."
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5vxqam | Why will my phone's autocorrect suddenly replace real, properly spelled words with some other word? | Shouldn't they just correct mistakes? How does it determine what to change? | Technology | explainlikeimfive | {
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"Based on the context of your typing, the autocorrect thinks that you're supposed to say something else - a word that probably most users say in that context.",
"In that scenario it's being predictive - Basically, if I type out \"Let's go to the\" and then type \"male\", it's more likely based on either a phrase list and/or a massive amount of compiled analytics on text usage that I actually meant \"mall\", even though \"male\" is a correctly spelled word."
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5vxrvv | Why is seemingly every TV's volume unbearably loud at like 30/100? What is the last 70% for? | Technology | explainlikeimfive | {
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"de5oo1b"
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"text": [
"many people have many needs. not every TV is placed in a bedroom or a living room. most are, but people have different uses for TVs. a bar, a school, small auditorium, office etc where they'd need for it to be louder"
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5vxzpe | The Cloudflare incident and what I, a consumer, need to do about it. | Technology | explainlikeimfive | {
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"Cloudflare is a company that provides a service to websites that help improve security and performance for those sites. A big service they provide is DDOS protection. They act as a proxy between the user and the website servers, so a lot of data passes through Cloudflare. Cloudflare had a bug that allowed for certain HTML data to cause Cloudflare to leak sensitive information about the web site. This information could allow information such as passwords to be leaked to a hacker. Users should try to change their passwords on any site that uses Cloudflare and look out for emails from websites warning them to change passwords.",
"Repost from another thread about the bug: ## Quick overview of the bug itself Let's imagine I operate a website that uses one of cloudflare's affected services. You request a webpage from my website. Cloudflare grabs the page from my servers, does its magic on it, and sends you the actual page contents. Now, imagine there's another page that also uses those cloudflare services, and the code for that other page is broken in some very specific ways. Somebody else requests a page for that site, and, when cloudflare tries to apply its magic to the broken page, it fails. The problem is, the cloudflare service needs some memory to work with to do its magic. Sometimes, the memory that it used to do magic on my page when it's serving your request gets reused when trying to handle the broken page. When the bug gets triggered, it doesn't actually put the right things in that memory, so the memory still contains the stuff that was used on your request. Then the service sends the contents of that memory to the second guy, as if everything had gone right. Result: The guy requesting stuff from the broken page gets data that was meant for you. Cases have been found in the wild where this \"data\" included passwords, authentication tokens, private messages, and more. When I say \"the guy requesting stuff from the broken page\" that actually includes google, bing, duckduckgo, and other search engines that have crawlers exploring the web repeatedly. As a result, some of those secrets ended up in search results, visible to the whole world. At least Google has since purged as many of those as it could find, I can only assume others have too, but it's unsafe to assume all those things are gone. The issue has also been around since mid-late 2016, as I understand it. ## What it means for you If you're a user of any affected cloudflare-using website, your credentials might've been compromised. Some fine folks are collating a [list of affected websites]( URL_0 ), you might want to force logout and change passwords on all of those."
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5vyhzs | "Cloudflare Reverse Proxies are Dumping Uninitialized Memory" effects on normal, every day Internet users | Web security gurus, please explain: URL_0 | Technology | explainlikeimfive | {
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"text": [
"## Quick overview of the bug itself Let's imagine I operate a website that uses one of cloudflare's affected services. You request a webpage from my website. Cloudflare grabs the page from my servers, does its magic on it, and sends you the actual page contents. Now, imagine there's another page that also uses those cloudflare services, and the code for that other page is broken in some very specific ways. Somebody else requests a page for that site, and, when cloudflare tries to apply its magic to the broken page, it fails. The problem is, the cloudflare service needs some memory to work with to do its magic. Sometimes, the memory that it used to do magic on my page when it's serving your request gets reused when trying to handle the broken page. When the bug gets triggered, it doesn't actually put the right things in that memory, so the memory still contains the stuff that was used on your request. Then the service sends the contents of that memory to the second guy, as if everything had gone right. Result: The guy requesting stuff from the broken page gets data that was meant for you. Cases have been found in the wild where this \"data\" included passwords, authentication tokens, private messages, and more. When I say \"the guy requesting stuff from the broken page\" that actually includes google, bing, duckduckgo, and other search engines that have crawlers exploring the web repeatedly. As a result, some of those secrets ended up in search results, visible to the whole world. At least Google has since purged as many of those as it could find, I can only assume others have too, but it's unsafe to assume all those things are gone. The issue has also been around since mid-late 2016, as I understand it. ## What it means for you If you're a user of any affected cloudflare-using website, your credentials might've been compromised. Some fine folks are collating a [list of affected websites]( URL_0 ), you might want to force logout and change passwords on all of those."
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5vyj3p | The difference between RFID and NFC | Technology | explainlikeimfive | {
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"NFC stands for \"near field communication\" and basically uses a passive magnefic coil on the physical application end of things. Your phone can use induction to get information from the NFC coil. Basically it involves two magnetic coils getting close enough to each other that they can send information to each other. RFID stands for \"radio frequency identification\" and uses radio waves to transmit information. A passive RFID tag would use energy from the radio wave to power itself while an active tag would have a power supply of some sort. Basically it uses radio waves to get information from programmed tags or devices. It doesn't need to be very close to the object either."
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5vzc9e | Why is there so much footage of nuclear bomb tests, etc. from years ago, but no recent or modern footage now? Has the world stopped testing or is it just now made public? | Technology | explainlikeimfive | {
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"Most testing moved underground, literally. Specially constructed facilities that sort of resembled bomb shelters, but in reverse, and deep underground. The footage from those is sort of a \"dark place, really dark, blindlingly bright, camera destroyed\". The tapes you are talking about were cameras spaced out from \"nearby\" to \"far away\" where the camera might not be destroyed, or at least the camera could get several seconds to a few minutes of footage before being knocked over.",
"The Comprehensive Nuclear-Test-Ban Treaty bans tests. Over 150 nations have signed this treaty. URL_0",
"There is a test ban treaty that prohibits above-ground testing. This treaty was passed in 1963. Underground testing is still okay. Obviously, regimes like North Korea do not observe the treaty.",
"Some countries have continued testing, India, Pakistan, and North Korea are the most recent that come to my mind. Their tests were done underground. You can't hide a nuclear \"test shot\" on Earth. The seismic effects are telltale and can be measured all over the world."
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5vzgb5 | If someone wipes their hard drive, how do computer forensic people know what they did? | E.g. in the Waymo v. Otto lawsuit, the guy wiped his hard drive. So how did they figure out all the stuff he did? | Technology | explainlikeimfive | {
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"there's a few ways. 1. wiping your hard drive doesn't actually wipe the contents. for example, OS's operate in a similar fashion to the dewey decimal system. the OS stores a table of pointers, that point to where the actual data resides. if you wipe this table, all the data is still there, but it can be freely overwritten at any time. 2. if you actually over write the data stored. due to the propeties of magnetism and such, even if you overwrite a location, you can still guess the data that was there because of lingering magnetic fields.",
"For most operating systems, deleting files actually does not remove them from the hard drive. When you delete the file, the first character of the file name is replaced with the \"~\" character. This hides the file from the directory structure. Much like erasing a building on a street map does not remove the building. More advanced removal involves writing a pattern of characters over the \"blank,\" area of the hard drive. Even this process is not a full proof method of deletion, because advanced low level recovery can read the slight differences in the layer of magnetic material of the platter (think of it as a CD but magnetic like a tape.) The second method is costly and often incomplete but can recover significant amounts of data. The last method is retrieving data from Off-site storage. Many programs provide cloud based storage. Occasionally people will think they have removed a file but there is a remotely stored copy."
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5vzhgz | how do traffic lights know when to change? | Technology | explainlikeimfive | {
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"text": [
"It depends on the lights. There are a wide variety of control mechanisms for traffic lights, so I'll try to break them down and list their pros and cons, and where they're more commonly used. I should clarify that my experience of traffic systems is UK based, and while much of this is international, regional differences will exist. First off, I'm going to explain some common terms, which will make this conversation easier. To do so, I'm going to take a sample junction in London, which is a simple crossroads with a \"scramble\" style pedestrian crossing. Stages are they different steps a set of lights can go through. This junction has three stages, 1-3, plus an \"all red\" stage, 0. The traffic light controller can send the junction to any of these stages. Phases are individual traffic movements. In the above example, you have phase A for the traffic coming from the South arm of the junction, B for the North, C for the West, D for the East. E is the standard pedestrian crossings, and phase F denotes the diagonal \"scramble\" movements. Phase G is used to refer to the all red stage, although really there are no phases active at all. Intergreen times are the time gaps between two stages. For example, when you go from stage 3 to stage 1, you have to wait for the lights to go amber, then red, then amber again before the lights on A and B are green, and the stage is considered to have started. I'm mainly mentioning this because it's important to remember that the timings below include their intergreen times as well. So, the different forms of control. Fixed Time: This is the simplest form of traffic control. The controller will just go through all the numbered stages, in order, regardless of any other considerations, on a set schedule. On the above sight, for example, it might look something like this: Stage 1 for 30 seconds Stage 2 for 14 seconds Stage 3 for 16 seconds This would cycle every 60 seconds, and keep doing that forever. It's not very efficient, so it's rarely used as a primary control method. It's sometimes used for temporary signals during roadworks, though, or as an emergency fallback if your primary control method fails. Vehicle Activated: Vehicle Activated control is quite common on less frequently used junctions. Essentially, the junction will sit at its \"rest\" state until a detector at the junction detects a vehicle on one of the other arms. In our example above, the site would sit on stage 1 as standard. Then if a vehicle approached on phase D, it would be detected, and the system would change to stage 3 for a while until that vehicle had passed. There's usually a minimum time the site will have to spend back on stage 1 before it could be pulled away again. V.A. works pretty well on sites with low traffic volumes - particularly when one of the arms has very low usage and you don't want to give it time unless it's necessary. It's still pretty inefficient for busy junctions, though. UTC: UTC, or Urban Traffic Control, is how the most important sites in London, and a lot of other cities around the world, are controlled. Every site has a comms connection (usually ADSL these days) to a central control server. This server monitors all the sites, and sends out commands based on the way it wants the site to work. UTC allows a lot of flexibility, but it generally operates on a similar cycle to Fixed Time, except for a few factors. Firstly, stages can be demand dependent. Most pedestrian stages work this way - when someone pushes the wait button, the controller will tell the central server a demand has been placed. Then, when the pedestrian stage's time comes up, it will be instructed to call it. If there's no demand, it will stay on the old stage, avoiding unnecessary calls to stages that aren't needed. Secondly, the timing of the cycles can be varied. This is usually done based on the time of day, to give important trunk roads more time during peak hours. At midnight, for example, the cycle time of our junction might be 42 seconds. This is very short, and means that the side roads and the pedestrian stage gets a lot of the time, but means shorter waits for each stage. at 8:30 am, though, the cycle time might be 72 seconds. That extra time will go almost entirely on the main North-South road, allowing it to get that busy commuter traffic through. The side road and the pedestrians will have a longer wait, but it's more efficient in terms of getting large volumes of traffic through the junction. SCOOT: This isn't really a separate form of control so much as an extra system run on UTC sites. It stands for Split Cycle Offset Optimisation Technique, so called because it optimises the junction based on Split, Cycle time and Offset. It does this based on SCOOT loops, detectors placed in the road that measure how much traffic is coming into and going out of the junction. The cycle time, as already covered above, is how long it takes for the whole system to cycle through its different stages. the split is the amount of that cycle time associated with each stage. It's used on busy intersections where all the roads could be busy, to identify which arms of the junctions have the biggest queues, and give them the extra time they need to clear traffic there. The offset is only used for sites that are linked in SCOOT corridors. The idea is to link the sites together so that their green lights line up with traffic flow - the so-called Green Wave effect that means that the lights change just as you're getting to each junction. It's very hard to get this right, especially if traffic is moving in both directions, but if you're able to do it it saves a huge amount of wasted time coming to a stop and then starting again. CLF: CLF, or Cableless Link Facility, is the system that UTC sites use when they lose communications with the main server, either because the comms line breaks or because the server isn't responding. It uses estimates of cycle times and splits for the junction based on time of day and day of week - obviously not as effective as live control, but better than nothing."
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5w0c1o | Why do websites make you have a complicated password when most account breaches come from a hack and not just guessing? | Technology | explainlikeimfive | {
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"When people hack sites for passwords, they usually get a list of the hashed passwords. That means when you put in your password, the site can check if it's the same password you signed up with but it doesn't know what the password is. It's like a one-way secret message. The way hackers figure out passwords is they know common hashing techniques and they guess common passwords using those techniques. Since \"password123\" is a common password, they'll put that in the hash, see what comes out, and match that output to the stolen list of hashed passwords they got. If they can't guess your password to input, then they won't be able to know what it is. Complex passwords make it harder to guess the hashed passwords once they're stolen. The biggest factors for making a password hard to guess are the total numbers of characters you can use and the length. So forcing you to have three special characters and two capitals and a number doesn't really help, but allowing you to use any character and requiring your password to be long does help. In other words, \"a%6L7\" looks like a more securepassword than\"!XthisismypasswordforthissiteX!\", but the latter is actually more secure since it's longer and can possibly use just as many symbols. Longer passwords are harder to guess because the possible combinations of guesses increase quickly as you add additional characters.",
"This is like asking \"why do we have locks on the door, when burglars often break a window?\" They break the window -- which makes their crime harder -- *because* the door is locked.",
"You complex password isn't just for breaches. A couple of years back a ton of naked pictures of celebreties was stolen off of iCloud, this hack was done because of social engineering (figuring out their login) and weak passwords (using brute force to gain access). If your password is a word or simple, it will take fewer guesses. If a hacker knows your login and wants to get *your* password, they will usually start with a dictionary attack (lists of common word and combinations); by requiring your password to be at least 8 characters with numbers, the amount of guesses needed goes way way up - if you have 4 characters and numbers it's 4^37, if you have 8 it's 8^37 (not counting symbols etc), that's hours vs. billions of years of computing. Now when a breach happens, complex passwords are still your friend *if* the website did their homework. *A lot* of people use the same username and password on all their accounts; facebook, linkedin, twitter, pornhub etc. and this is where complexity starts to matter. They now have most of your credentials, they know what email you sign in with and they know the hash of your password for *this* website. Now most website worth their salt will have a custom way of salting their passwords, however the hacker just gained access to everything, which probably includes the source code for the login, they can now start to figure out your password, which probably gains login to everything. If your password is complex and the salt is correctly made, it will still take billions of years to brute force the hash. So the reason why they require you to make it complex is for your own good. We *know* our websites are susceptible to attacks, it's simply impossible to make anything hacker proof, short of disconnecting it from the internet, turn it off and bury it in 10 ft. of concrete in the Mariana Trench. You *have* to assume that you have a data leak at some point, having good policies for password and other sensitive data will mitigate the fallout.",
"> most account breaches come from a hack and not just guessing? This is a direct result of those websites making users have complex passwords. If password were easy to guess then that's what the attackers would do.",
"Most account breaches come from guessing, you just never hear about them because they often go unnoticed. Think of a snoopy family member or \"friend\" trying to see what you've been up to. If you use an uncomplicated password, they can probably guess it, and they'll probably never tell you they logged into your account without permission. Also, dictionary attacks on websites that don't have password restrictions can also fly under the radar unless the website publicly discloses that accounts were compromised. Which isn't likely; if they don't give a fuck about your password strength, they probably don't give a fuck about who is using your account. Finally, there are many security reasons for password restrictions. Passwords are often stored as hashes which, if stolen, can be brute forced if the attacker knows how the hashes are generated. The more complicated the password, the longer it takes to brute force it. A good password with special characters can take a single computer upwards of billions of years to brute force, whereas bad passwords with only lower case letters can be forced in milliseconds.",
"The breaches you *hear* about come from hacks, because those are breaches that involve thousands and thousands of accounts all at once and make the news. When Bob from Idaho's account gets broken into because it has a weak password, it's not going to make the news.",
"Incompetent and/or uneducated developers genuinely believing they are helping you. Aware that security is an issue but unaware of why, they instead choosing to solve the \"how\" by thinking like a human instead of a computer. Oh, and just because it's not here yet: mandatory relevant [XKCD]( URL_0 ) Edit: It's just a comic, dammit! Not an example of \"how to do securityz\". Sheesh.",
"It is because of this thing security researchers called \"social engineering\". Passwords are like locks - at best they are a deterrent against unauthorized access. The harder the lock is to crack, the less inclined a thief will be to break in. A lot of hackers can engineer or \"guess\" a password by looking at social aspects of your life. The harder you make it for them to \"guess\" your password, the harder they have to try to hack into your account. At one point they will just give up because it is not worth the effort.",
"Because if you didn't have complex passwords most breaches would come from guessing. (...?)",
"Because if the site didn't require you to make a complex password, the hacks would be even more frequent and would be from guessing.",
"Like you’re five: Your password is like the code on a safe. When someone hacks a site, they steal everyone’s safes, but they still need to break the code. These are very good safes that cannot be physically broken and can be secured with very long codes. But if you choose a simple code, the thieves have your information almost the moment they escape with the physical safe.",
"Irony is that by enforcing certain password characteristics (min/max length, must contain at least one of X), the site is actually making your password easier to guess for the hakers...",
"most hacks involve guessing. Ok so breakdown on how passwords are stored: If whoever is storing the password for your account isn't a toolbag, they don't ever actually store your password. Instead they feed your password to a hash function and then store what that outputs, and then whenever you input your password, they just feed it back through the function again and check to see if it matches what they have stored. May need to explain what a hash function is so let's detour for a minute. A hash function will take some input of any length and it will output something of a fixed length (usually quite long), the input should always map to exactly the same output ever time and it should do so in a way that's quite easy to do, but very very very hard to undo. For example: using the md5 hash (which isn't one that should ever be used for storing passwords) feeding it \"password\" outputs 5f4dcc3b5aa765d61d8327deb882cf99, \"password1235483\" outputs c048f211d0c6e9dcd83316b042a6723c and and mashing on my keyboard for a hundered chracters or so produces bae019d234e18408edd8b82c9437fecf So this means that if a site is compromised and someone makes off with whatever database they're storing the hashed passwords in, they'd stuck trying figure out what the hell the hashed passwords are. In general this is accomplished via a lookup table which looks kinda like this 286755fad04869ca523320acce0dc6a4=password 10b222970537b97919db36ec757370d2=password1 7576f3a00f6de47b0c72c5baf2d505b0=password123 f2c93f0625019e5461379cd1a4ed1b16=p455w0rd and so on. Then you compare the hashed passwords that were stolen with the known ones and see what matches. Infact because computers are good at what they do, you can just find the hash for basically every combination of characters under a certain size. there's only a few billion passwords with 6 characters or fewer, and it would not take a computer very long to build a database of the hashes for every single one of those passwords. And it also doesn't take a computer very long to check the a bunch of stolen passwords against that list. If you have a weak password, they're going to find it real quick. If you've something much longer and more complex, then it's probably not sitting in some lookup table. Infact, hashing in general isn't the only thing that happens to a password. Instead what they really really should be doing is a salt+hash method. which means instead of feeding just your password to the hash function, they feed it and some other randomly generated \"password\" (the salt) to it. In a simple case this could be something like yourpassword64sdf55c4c1w34372654263r4236r623r23r423564415... where yourpassword is what it says it is and then the random stuff afterwards is the salt. Done right this has two advantages. The first is if two people use the same password there will be different salts used and so the hashed passwords will be different. The second is that it makes lookup tables much less useful, and forces anyone wanting to figure the password out to fall back on brute force guessing. And while a weak password is a little better off in this case, it still won't take very long for a computer to run through a bunch of really common passwords and eventually find yours."
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5w0o3m | How are we able to download files for a game but be unable to view code? | Obviously people want their code to be a secret but I'm curious otherwise | Technology | explainlikeimfive | {
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"Code written in programming languages is for humans, and it gets turned into machine code before it can be executed by computers. Machine code is what the computer actually runs. When you download a file, you are not downloading the source code. What you download is the compiled version of the code which is in machine code. Generally it is pretty hard to go from machine code to source code (decompile). You lose information as you go from source code to machine code, and it isn't possible to regain all the lost information going in reverse. For one thing you lose all the comments in the original source code. That's what it means for a software to be 'open source'. The company publishes the source code publicly. There are no secrets.",
"In the same way you can buy food but can't tell exactly what went In the the making / making process of the food, even though you have the food in front of you!",
"You can view the code. It'll usually be in files marked .exe or .dll if it's a Windows program. This is not source code, though, this is executable machine code. You can look at the raw binary with a hex editor, or you can use a program called a disassembler which will attempt to translate the machine code into assembly code (but this translation isn't always straightforward, as it can be difficult to determine what is code and what is data, and where instructions begin and end). It isn't necessary to have the source to run the program, so many developers do not distribute the source code for their programs at all. If source code is available, it is usually distributed seperately, as not all users will want it.",
"PHP developer here (not quite games but it could be used for browser based games in theory). Similar to how a game engine such as Unity or Game Maker Studio or Unreal Engine allow game developers to write code and export it, usually into an .exe file. I program my code in a language called PHP and I can write a code such as < ?php echo \"Hello, World!\"; ? > which runs through something called a compiler on the web server, and than relates that information in the form of HTML and what the user would see is simply the text \"Hello, World!\". If you wanted to take it a step further, you could right click using Google Chrome and click \"View Source\" and you might see something similar to < p > Hello, World! < /p > which is actually HTML (compiled code). If I were to do something more complex such as < ?php $x=5; echo $x+$x; ? > the user would see the number \"10\" in plain-text in the browser, again, they could take it a step further and right click > view source > and they would see something like < p > 10 < /p > in the form of HTML but they would have no idea what the logic was that caused the browser to choose that number when on the server side of things, it's clear that this is the variable $x = 5 (basically just the number 5) added to itself to get the number 10 (5 + 5 = 10), but the user is unable to see this as my \"Developer code (PHP/Server side)\" is hidden from the user. This is the same reason that you can visit Facebook and read and update and share posts but you can't just right click > view source > copy > paste and basically create your own Facebook, user's don't have direct access to the server side code (PHP, sometimes different languages for different sites), what they see is the final compiled code, usually HTML, CSS, JavaScript. These same principals can be applied to game engines compiling their code into a user-version which cannot be viewed the same way in a \"human friendly way\"."
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5w1gug | What happens when the Semiconductor Fabrication Process gets to 1nm or lower? | I see that with each new lineup of CPUs, the "nm" gets lower and lower. I see the same thing with Nvdia's GPU. Basically, what happens when it gets to 1nm? Will it go lower? Why do they have to go in order? Why can't they skip straight to 1nm? It's it a technological limitation or is it a financial motive? | Technology | explainlikeimfive | {
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"I doubt that semiconductor fabrication as we know it will get to 1nm. Silicon atoms themselves are about 2nm in diameter, and the materials used to make the gate dielectric are generally on that order or a bit larger. Plus there are great difficulties in actually forming transistors that small. Even 7 nm is pretty hellishly difficult. Why didn't we just skip to the smallest possible size years ago? Because it takes a great deal of research and engineering work in a variety of disciplines to \"shrink\" transistors. At each increment we've learned things that we didn't know before, and each one was a very difficult process taking years and years of work and lots and lots of money. Trying to jump ahead too far would be an enormous investment and would likely not be successful. And even a giant like Intel doesn't do all of the work on their own. They rely on a variety of outside vendors to do some of the work. You'd have to not only commit your own company's future to a very risky proposition, you'd also have to convince a bunch of other companies to do the same. What happens after Moore's Law hits the wall? Semiconductors can still do a lot of innovation. One of the big ones going on now is finding ways to connect multiple chips together without long conductors between them. That can offer nice improvements in performance and/or size. If you were to take something like a cell phone and figure out how much of the volume is actually semiconductors, I suspect you'd find that it is rather small. We waste a lot of space with packaging, interconnect, decoupling capacitors, etc. There are also things that can be done to make transistors a bit faster and lower power without shrinking them. Ultimately, we need a replacement for semiconductor/transistor technology as we know it. Quantum computing, biological computing, etc. Want to be the next Bill Gates? Come up with the successor to integrated circuits, which have driven our technological explosion for over a half century."
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5w1gvf | Why do some people cause interference with radios? | Technology | explainlikeimfive | {
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"Everybody causes interference with the radio waves, Your body is mostly salty water which absorbs radio waves pretty well. Nobody emits interference. Your cell phone could cause interference with radios. Even though the phone uses frequencies far higher than the radio, it can overwhelm poorly shielded circuits."
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5w1khf | What is the point of XML? | I have a great understanding of database systems, HTML and CSS but I after reading for hours and even watching videos I cant see why anyone would ever use this. It does not seem an appropriate or efficient way to deal with data. | Technology | explainlikeimfive | {
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"XML is a well defined, general purpose, data transfer language that's designed to facilitate the transfer of data from one system to another in a standard way. Before XML was a thing, every program had its own protocol so you'd have to write new parsers for data import or interchange between every system. XML is basically HTML intended to be used for machine-readable data. It's not intended to be efficient from a CPU or space perspective. It's intended to be a single, easy to work with standard so that all systems can transfer data between each other using a standard XML parser to interpret the data - it's efficient in terms of *programmer time*. Whether it's actually effective at this is a matter of debate.",
"XML allows you to define complex data sets, including metadata and relationships, in a plain text format without the need for a database. Now adays JSON tends to be the road more traveled because it's easier to interpret and traverse in a program, but XML still has its place, if for no other reason then it would take a lot of effort to rewrite all those systems that used it previously."
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Subsets and Splits