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6cow6a | Once a phone runs out of charge, how does it continue to display the "Out of Charge" screen? | Technology | explainlikeimfive | {
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"Because the battery isn't completely out of charge. It's programmed in such a way to prevent use below a certain battery level. Most phones turn off at 2% but sometimes you'll even see the phone say 0% when you turn on the screen. However that's not entirely accurate. Very close to being empty yes, but not entirely. If it was it would be impossible for the phone to turn on.",
"A battery is not completely depleted at that point, but would be damaged if the battery is drained much further. Completely draining a lithium iin battery to zero potential would damage the battery, possibly leading to a violent failure. The out of charge screen, or led, serves to reassure the owner that the phone is functional, but has a drained battery."
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6cp7xn | Given their recent rise in popularity, how exactly do wool dryer balls reduce wrinkles, dry clothes faster, etc? | Technology | explainlikeimfive | {
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"They help to separate items being dried. This allows the hot air from the dryer to circulate and thus dry items faster. Saves energy."
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6cqajh | Why does scratching a CD cause the contents to become unreadable? | Technology | explainlikeimfive | {
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"Reading cds is done by reflecting light off each bit. I guess it's comparable to reading Braille where you feel for bumps. If you scratch the cd you no longer get an accurate reflection so you don't know what it's supposed to be. Same way if you damage a Braille book you can't read it anymore.",
"It doesn't always. The way information is encoded on a CD has some error correction, so small scratches or other defects don't cause a problem. It is only when the scratching is fairly severe that the error correction can't overcome it. CDs work by bouncing a laser off the shiny side. There are very very small pits stamped or etched into the CD to encode the information. When the laser hits an area with no pits, it reflects back to a detector. When it hits an area with a pit, the laser light is scattered and very little gets back to the detector. The changes between \"pits\" and \"no pits\" is what encodes the binary data. A scratch screws this up, typically by making the laser light scatter, even if there isn't supposed to be a pit there.",
"CD players use a laser to read the information on the disc. A bad enough scratch would make the surface opaque (or possibly deflect the laser beam) meaning the laser can't get to the information.",
"Because it prevents the pick up laser assembly from reflecting off of the data layer correctly. The data in a CD is not on the surface, it's under the silk screen material near the top of the disc. The clear bottom of the disc helps protect this data layer. If it is scratched you can buff out the scratch and continue to read data from the disc. But if the thin metal or dye based layer under the silk screen becomes scratched then the data is lost even if the bottom isn't scratched. To put it another way, scratch a CD bottom you can repair it. Scratch a CD top then your data is gone. There are also differences in how CD's are created. Recordable CD's use a reflective backing under the CD label with an opaque dye or pigment based layer over it. The laser in the disc writer punches holes in the dye allowing the laser to reflect off the backing and allow reading of data. Commercial CD discs are pressed though much like a vinyl record. The data is pressed into the soft plastic and then the plastic is exposed to vaporized metal which collects and forms a shiny reflective layer over the pressed CD tracks."
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6crav4 | Do the programs that run when idle to help research some big project actually work? If so how do they work and are any better to contribute towards? | Just heard this week's This American Life talk about contributing your computer power to help SETI look for aliens. I have a beast of a PC that only gets used a few hours a day for gaming and I wouldn't mind putting it to use if I could be sure it wasn't a waste of my electricity and wear and tear on my components. | Technology | explainlikeimfive | {
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"Yeah they do. Basically certain problems that we only know how to solve by brute force, ie guessing an answer and running calculations to see if it's correct. This is only really possible nowadays with computers that are very good at doing these repetitive tasks very quickly. Folding@home for example uses your PC power to simulate the folding of proteins. One of the objectives is to understand the mechanism of this, so that they can understand protein misfolding and hopefully help prevent diseases like Alzheimer's. SETI I believe uses the processing power to perform signal analysis on all the noise they pickup from outerspace. In this case there's just so much data that you need a lot of processing power to do a detailed analysis."
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6crjll | How do air traffic controllers/pilots choose which runway to use? | Hi all, I live near an airport and I realise that depending on the season/day/time, some runways are utilised more than others. How do you guys determine which runway to use and why? | Technology | explainlikeimfive | {
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"The main motivation is wind. Taking off or landing with a tailwind uses much more runway length. It's like having to run to catch a train that's already rolling away - don't run off the end of the platform. Crosswind is more challenging and can upset the passengers (because you takeoff or land tilted). In poor visibility, you might have better instrument approach equipment on some runways. So weather decides which runways can be used to begin with. Then you have to arrange the traffic patterns so they don't interfere with each other - more of a challenge at a large airport. Pilots must *always* have the option to return after takeoff if there's a mechanical problem. And to skip landing if they're not lined up properly or the wind does something unexpected or there is a traffic jam on the ground or, really, anything. Small airports, pilots might ask for and usually get a specific runway. If it's too small for tower control, they'll decide on their own! It's quick and easy to turn around in the air, so wind is the biggest factor."
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6cs7co | Why do dry erase boards become so dirty and difficult to erase fully even with a new eraser and proper pens? | Technology | explainlikeimfive | {
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"text": [
"This is because the special surface wears out ove time. My office actually used Dry erase paint and turned our walls into a giant dry erase board, once it starts getting hard to erase, a new coat of paint will fix it up! URL_0"
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6cx94x | What is Kik? and Why do people use it over texting? | Technology | explainlikeimfive | {
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"Kik is a messenger app, can be used with just wifi and doesn't require you to share your phone number. I prefer to use Kik over texting because 1. I don't have to share my personal phone number 2. It tells you when the message has been delivered, read, and when the person is replying 3. Standard messaging rates don't apply",
"Kik is a texting (as well as picture, video sharing, and gouptext) app that uses wi-fi or mobile data instead of cell service, similar to iMessage but can be used on Andriod and IOS. For this reason the app is fairly popular with younger, middle-school aged, teens. It also is an encrypted messaging service. So other, privacy seeking users, may find this messaging app preferable to others (for sending dirty pictures)."
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6cxq9e | The FCC and the Net neutrality drama going on in the USA. | Technology | explainlikeimfive | {
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"It allows the Telecoms who have been accused of and lost lawsuits related to price fixing/monopolizing to do this: URL_0 Currently they aren't allowed to slow down or speed up traffic to any website, if the Trump administration is able to get the rule changes they want through the courts Telecoms will be able to do that. For example, Ted Turner (owner of CNN) decides to start up an Internet Service Provider and purchases a region that comcast has monopolized in rural Kansas. He knows that in that area people prefer to get their news from right wing sites, so to be able to access to URL_2 al. will cost an extra $10 a month through his service, OR you could go to URL_1 to get your news. Either way, he not only makes money from them purchasing his internet but also from them paying additional fees to access the sites they want(again, he has non-competition agreements with other ISP's to keep them from expanding to the area and has lobbied local lawmakers to prevent subsidizing startups or government internet to compete with him). Another example would be Comcast is currently losing alot of TV subscribers to Netflix/Hulu/Amazon so they could prevent access those websites without an additional $10 fee so you have to pay $20/mo OR you could pay just $10/mo for Comcasts online video service (no addtl charge for theirs of course). The counter to this lobbyists have stated that the Telecoms won't do this, but again, they have lost numerous lawsuits claiming they have done things like slow down speeds when users are on Netflix but not other websites. Don't even need to go into detail how this negatively impacts small businesses who can't afford to pay Telecoms additional fees to let people access their websites, access things like quickbooks, etc. In other words, this is an overtly anti-citizen/pro-corporation move and it's ridiculous how brazen the GOP is in their \"we don't care about the American people\" stance now.",
"Big corporations want to be able to charge more for internet. Basically nobody in science or the public thinks it's a good idea, but it's happening because they will make more money."
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6cxzfb | When a calculator resolves 1.001^10000, does it actually multiply 1.001 10000 times in sequence? | Technology | explainlikeimfive | {
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"No. What exactly the calculator does depends on the calculator, but it is always quite complex and not very ELI5-friendly. Typically they will convert a^b to e^(b*ln(a)^) with the natural logarithm ln( ) and the exponential function. Then it can use ln(1+x)=x - x^(2)/2 + x^(3)/3 (and probably more terms, this is called a Taylor series) to find the approximate value of ln(1.001)=0.000999500. Multiply it by 10000: 9.99500 To calculate e^(9.99500) there are similar tricks, and the final result is about 21900. That way you don't have to do 10,000 multiplications, and you can also calculate 1.001^10000.35 and similar expressions.",
"The usual way is to calculate the logarithm, then multiply, then calculate the exponential. If you take x^y then log (x^y ) = y * log (x). This means x^y = e^ (y * log (x)) where e is the base of the natural logarithm. OK. So what's going on here? We've converted a exponential function into an exponential function, a logarithm and a multiplication - that's even worse that what we started with. It turns out that there are quick ways of estimating exponentials and logarithms using polynomial functions, for certain values of x; you don't get an exact answer, but you can design your function to give enough significant figures that it will do - so if you have a 10 digit calculator, the function will be designed to give at least 10 accurate digits. The calculator is programmed with the specific polynomial functions for e^x and log (x). By using these 2 functions, it can calculate any x^y.",
"So, as they said, solution is based on logarithms, making the operation faster. But even if you were not to use that logic, there are ways to do it with way less operations than just 10000 multiplications. Your operation can also be expressed as (1.001^2)^500, which is the same as (1.001^8)^125. You get the basic idea. 125 is not divisible by 2, but you can express it as: (1.001^8)^124 * (1.001^8), which in turn is (1.001^32)^31 * (1.001^8). Those are way less than 10000 multiplications, and we can go on. Logarithms and Taylor are still faster, this is just an example on how with simple math you can achieve improve the initial number of operations",
"[IEEE 754]( URL_1 ) is a widely-used standard for representing numbers in computers. I don't know that handheld calculators use this standard, but I wouldn't be surprised. There are standards for how multiplication works in IEEE 754, but they're really beyond ELI5. [This]( URL_0 ) seems like a good simplified explanation, other than it presupposes that you understand how IEEE 754 numbers are represented (which is basically like scientific notation, with a number and an exponent to which the base is raised that is then multiplied by the number). Aaaaaand I just realized that you asked about exponentiation, not multiplication. Grrr. I'm going to submit this anyway, because looking into IEEE 754 might still provide some insights. (BTW, \"IEEE\" is pronounced \"eye triple E\".)"
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6d04i8 | Why does the U.S. military still utilize iron sights for infantry? | The US military employs ~1,710,000 active men and women. Given that the cost of a relatively high end holographic sight is about $500, that would equate to $855 million for every active soldier to be equipped with a holographic sight. Holographic sights are superior to iron sights because they give the user a higher field of view thus increasing awareness of the soldier's surroundings. With the 2015 military budget approaching $600 **billion** why are holographic sights not universal amongst the US army? | Technology | explainlikeimfive | {
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"What happens if you trip and break your ACOG? I can't speak for every branch but I know the marine corps does use ACOGs and probably other non iron sights for combat training and in combat. I think I've used them on the standard range before also. But bottom line rifle training and qualification is done with iron sights because they're incredibly reliable and unlikely to break as well as teaching strong basic technique. Basically hope for the best but prepare for the worst.",
"They have to be capable of using the weapon if the fancy scopes and targeting systems fail for some reason. Knowing how to use the physical iron sights is the failsafe.",
"Iron sights teach proper shooting form. A little aside about this way of teaching: I do archery and in archery, one of the last things you put on a recurve when you first learn to shoot is a sight (besides stabilizers). Now promptly, you are probably thinking to yourself \"why put the device that makes you accurate on last? That's not efficient!\" .... but in reality, it is efficient. Having a nice sight (in archery, something like a $200-350 Shibuya/Axcel sight) means absolutely nothing if you cannot consistently find your specific and repeatable shooting cycle; without that, all your shots will be pretty moot the moment you begin shooting anything beyond 15-20yards as you will find yourself hitting all over the place. The same goes for a service rifle. If you cannot consistently use iron sights, having an ACOG/EOTech/etc. will not magically give you 100% repeatable sight picture alignment/acquisition. You need to develop a form (as its referred to in archery) and develop consistency before accuracy. EDIT: Some small grammar issues."
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6d0syj | Why was windows 8 considered a downgrade in operative systems? | I'm curious about this.and thanks in advance. | Technology | explainlikeimfive | {
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"It was a bug-ridden mess. I had programs and games that worked fine in 7, and in 10, but not in 8 or 8.1. It was designed from the ground up to be a mobile operating system but was rammed into the desktop market which has entirely different UI needs. It had weird bugs that never got patched or even acknowledged by MS, like the infamous %100 disk usage bug that slowed some programs to a crawl even on the high end rigs, and it was entirely random. It was profoundly uncustomizable. It took away the start menu, which was a focal point for a great many users who relied on familiarity to help them navigate their space. It arbitrarily changed things around to appear new, when in fact all it had done was change names of common locations and files, and made a different way to access them which needlessly confused the hell out of exactly every single person who ever used the thing. Simply put, MS slapped together a ramshackle product that swapped things around to give it an air of undeserved newness and never bothered to take responsibility for the mess."
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6d5ojl | How have car antennas gotten smaller over the years while FM/AM radio quality has gotten better. | I recall that my father's old Toyota SUV had an antenna that extended when you turned on the radio but now that I have a new car of my own the antenna is tiny with the dimensions of a pencil. On top of this when I select a station my car displays a symbol that says HD Radio. How has the technology changed over the years to allow for this to happen? | Technology | explainlikeimfive | {
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"Smaller antennas are not as good as the classic 1/4 wavelength whip with ground plane. FM radio is about 3 meters so a 3/4 meter or 30 inch antenna was traditional. Smaller ones use a coil of wire to help lengthen the antenna as far as the preamp is concerned. Radio receivers have gotten better over time. HD Radio is a digital broadcast which uses the same frequency band as the analog signal, but is transmitted at a much lower power level (1/100). It allows for multiple program streams."
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6d6fnt | Why are apps, and websites, so adamant about enabling "notifications"? | I don't like notifications on my phone. They are all disabled. This causes me to be harassed WITHIN the apps I use (and to a certain extent, websites) to enable notifications. What is the gain for the developers? Why do they want me to enable notifications? | Technology | explainlikeimfive | {
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"Notifications mean that they can engage with you *without waiting for you to come back to the site*. If they can sent you notifications, they can remind/prompt you to come back & use the site more. The more you visit a site, the more ads they can show you, the more likely you are to pay for some sort of premium features, or get involved in whatever it is they do to make money.",
"The bottom line is they want to advertise to you. They probably won't put ads in the notification. They will lure you back to their site with something they think will interest you. (They remember what you click, or even buy your preferences from someone else.) And then when they've lured you back, they will advertise to you."
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6d6hpq | There is a gif on r/gif showing a microbot "delivering" a sperm to an egg. How does said microbot work? | [Here is a link]( URL_0 ) to the gif | Technology | explainlikeimfive | {
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"It is *extremely generous* to call it a robot. It is in fact just a metal spiral which is manipulated by a rotating magnetic field. I would simply call it a creative tool which can be remotely manipulated."
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6d6n1s | How do personnel on submarines connect to the internet? | Technology | explainlikeimfive | {
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"text": [
"they wait till the sub comes to the surface or periscope depth and all the remaining data is transmitted. When submerged there is no internet access. You do without."
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6d7pqp | disk partitions, volumes, basic disk, dynamic disk, mtb, gpt | My os is on an ssd. how should I format my hdd? | Technology | explainlikeimfive | {
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"text": [
"MBR vs GPT is format for how the disk stores the information. MBR is older, has some limitations and issues. GPT is newer, stores the info at the begining and end of disk, and has fewer limitations. MBR is limited to 2TB in capacity without using advanced formatting, but GPT has a massively larger limit (1000's of times higher). Additionally, older systems cannot boot from GPT (too \"new\"), while GPT is \"required\" by EFI systems for booting (though most support \"legacy\" mode, to boot into a BIOS like mode rather than EFI). Partition and volumes tend to be used interchangeably, and unless you are using \"dynamic disks\", ... are interchangeable. In either case, they are a section/region of the disk allocated for usage. Much how a room partition seperates a room into smaller parts, so does a partition on a disk. Mostly, you see this used on the system disk (boot disk), for the boot loader, main system, and recovery partitions (windows). As for basic disk vs dynamic, \"basic\" disks are the normal, \"run of the mill\" style for most drives. Dynamic disks are Windows' software RAID type disks, and are prone to problems. As for your OS drive, let the setup decide that. It will partition and install everything \"as needed\" here, so you shouldn't need to worry about doing anything here."
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6d85ck | What is a microprocessor? How does it work? How was it invented? | My 7-year-old niece is asking me these questions because she saw the word somewhere and someone told her that that's what her iPad uses to work. | Technology | explainlikeimfive | {
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"The simplest microprocessor needs three things: a place to store some data (memory); a set of instructions to carry out on data; and a working area in which to carry out the instructions. That's it. **data** Data is always represented as a number. So even letters and instructions are numbers but we store some other data elsewhere that let's the computer know (I use this term loosely) what letter or instruction is represented by a number by keeping them in a table somewhere else. All numbers in a computer are represented in binary. Binary is the series of ones and zeros you've likely seen before. 01101001. We don't need a table to look up what these numbers mean because you can use maths to transfer from one to the other (separate ELI5 question: how does binary work). We use binary because most microprocessors represent ones and zeros using a change in electrical voltage. Plus 5 volts and 0 volts are common but you can use any two voltages provided your equipment can tell the difference between the two. Each electrical voltage reading is called a bit. All of the data in the microprocessor is stored as electrical voltages in groups of 8 bits called a byte. More complex microprocessors deal with longer sets of bytes but for this example we'll just use 8 bits, 1 byte. **program in memory** A program is read into memory and stored there. You can think of the program as a tape with a series of instructions on it and in between all of the instructions is some data. You start at one end of the tape and work to the other end unless an instruction on the tape tells you to jump forward or backwards along the tape. The tape can refer to memory locations. There's lots of different memory locations in modern processors but all you need to know is that we can address them individually. **instructions** The simplest set of instructions would be the standard mathematical operators (like add, subtract, divide and multiply) and some instructions to jump to a particular part of the tape after some condition is met. **example** We write a program to subtract 1 from 10 until the value reaches 0. In practice something like this can be used as a counter for another instruction being carried out 10 times. The language I am using here is a reduced assembly language from a computer game called TIS-100. It's a great way to learn how a processor works. It might be a bit advanced for your seven year old but if she seems to get the basic concepts it's worth trying the game with her. I'm pretty sure I started writing assembly about that age, I was certainly programming by then. ACC is the \"**working area**\" we talked about before. This is the tape MOV 10 ACC (put the value 10 in the working area) LOOP1: (this can be called anything but it's a name used to jump in the code) SUB 1 (subtract 1 from the current value in ACC) JNZ LOOP1 (if the current value of ACC is not zero go back to loop otherwise do the next instruction) *Next instruction* end of the tape. In memory it looks like this:(numbers down the side show moving forward in time) ACC contents 00: 00001010 (number 10) 01: 00001001 (number 9) 02: 00001000 (number 8) 03: 00000111 (number 7) 04: 00000110 (number 6) 05: 00000101 (number 5) 06: 00000100 (number 4) 07: 00000011 (number 3) 08: 00000010 (number 2) 09: 00000001 (number 1) 10: 00000000 (number 0) And that's it. It really is that simple. The reason everything seems complicated is that the computer can do millions of millions of these instructions every second and when you put them all together they can show a video or play music. It's pretty incredible.",
"A few pretty good answers so far, but trying to answer this briefly and with ELI5 (ELI7) in mind 1) a microprocessor is a basic computing unit that does things like addition, subtraction, condition evaluation (e.g. is the result of the last subtraction equal to zero), reading inputs (eg keyboard button presses), and writing to outputs (eg pixels on a screen) etc 2) it works by using combinations of simple logical operations like and, or, xor, and reading/writing inputs and outputs ( URL_0 ) 3) originally, microprocessors were used to perform very simple computations more quickly than humans could. They have been ever evolving over the past several decades for more and more advanced problem solving. For example, microprocessors have been used to drive calculators so people didn't have to do calculations by hand, but the same operations (like addition, subtraction, reading and responding to keyboard inputs) combined in innovative ways could also run simple games like pong. Then, taking it a step further, you could do things like determine what a person is typing and create a basic command line/user prompt application",
"A microprocessor -- also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip. The first microprocessor was the Intel 4004, introduced in 1971. The 4004 was not very powerful -- all it could do was add and subtract, and it could only do that 4 bits at a time. But it was amazing that everything was on one chip. Prior to the 4004, engineers built computers either from collections of chips or from discrete components (transistors wired one at a time). The 4004 powered one of the first portable electronic calculators. You can get more of the story [HERE]( URL_0 )"
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6dadyd | When game companies are bringing down their servers for maintenance, what are they doing? | Technology | explainlikeimfive | {
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"They could be doing any number of things from implementing security fixes to adding new features to the game or updating UI. There is a great number of things they could be doing. However, when servers are brought down, it's because it's usually required for them to end all data transmissions when editing files. It's the same concept as trying to delete a file you have open on your computer. If you create a Word document and open it up, then try to delete it without closing Word, the computer won't let you delete the file. It's the same thing for those companies. They have to make sure nobody is accessing those files when they go to edit, move, or delete them."
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6dahyg | Google's new login? | Whenever you wanted to sign into a device that was not yours, you would uncheck this box. Now (after google's "new and improved" sign in page) If I want to sign out, I have to sign out, the go back to gmail and "remove" the account. In fact, this is just about the only difference between the previous and new sign in forms for google. Yes, I know I could use incognito, but it becomes an incredible hassle when doing so on a coworker's laptop. Our admin has removed the "incognito" option from chrome. So, my question is: Why would google do this? I assume that they want you to stay signed in. They track you anyway using cookies, though, so why would google want you to stay signed in? What financial advantage does google get out of this? | Technology | explainlikeimfive | {
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"> Why would google do this? In this case it has more to do with convenience than money because, you're right ... they have very elaborate and effective ways to track you. Of course, the convenience leads to more money though. You sign out of gmail (perhaps because you want to sign into your other gmail account). When you are done using that account you sign out of both. The next time you want to use gmail it's quicker for Google to have saved some of the information for you. Now you don't have to type your email, you just type your PW. That gets you logged in quicker and now you have a second or two more to visit some other page and potentially click on some link that makes them money. It's all about removing obstacles that might keep you from using their services so you're more likely to use them."
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6dapqs | Why does WiFi range seem to be determined solely by the router/AP? | I have noticed over the years, that increasing the power / antenna strength of an access point or router increases the distance that a signal is usable by a laptop/mobile phone/etc. While this might sound like a no-brainer, what about the signal getting BACK to the AP / router? It doesn't seem to matter how strong the radio is in the "receiving" device (yes, I understand the devices are also transmitting), only the "sending" device. For instance, I routinely install long-range AP's in warehouses, some rated for 250+ meters (just shy of 1,000 ft.). Several times I have been required to increase the power available to the antennas in some AP's in order to reach specific devices behind concrete walls, through racks of metal, etc. I understand that this provides a stronger signal *TO* a device, but then how does the device (such as a laptop, that has a much smaller antenna and less power) still communicate (respond) back to the access point? | Technology | explainlikeimfive | {
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"The stronger transmitter also has a more sensitive receiver. The signal threshold that your mobile device can detect is higher than what a dedicated router can pick up, allowing the mobile device to be compact and the router to pick up the slack on both sides of the communication."
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6ddzz1 | How do radio statios/tv stations know how many people tune in? | Say for example: how do they calculate how many people watch the Superbowl? edit: auto correct is lame | Technology | explainlikeimfive | {
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"Nielsen does this, they tell you how on [their website]( URL_1 ), but basically they just randomly select people and track everything they do by asking them to write down everything and walk around the streets with microphones to record whatever people are listening to. They aggregate the data and produce the ratings that everyone uses by extrapolating it. For TV they use [special boxes]( URL_0 ) that track what people watch."
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6dfr6n | Why do modern bathrooms still use tiles when grout is so hard to clean? Haven't we come up with a better solution for water-proof surfaces by now? | When I was little, there was this advertisement for a bathroom cleaning product that asked something like: "Have you ever noticed that the cleaner you get, the dirtier your shower gets?" It is so true! Why haven't we found an easier-to-clean waterproof surface by now? | Technology | explainlikeimfive | {
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"Solid plastic shells and linoleum floors. But they're generally seen as cheaper options. And they wear out faster. Tile is fancier and lasts longer and is more expensive. Slate doubly so. But trust me. The cheaper and easier to clean options get PLENTY dirty too. You ALSO have to clean them. If you're super-wealthy and can splurge money on stupid things, your bathroom can look like a chunk of nature with living moss floors, drift-wood counters, and hollowed petrified dinosaur egg shells for the sinks. And it's all an absolute bitch for your maid to clean. What do you care though, you're rich. Rich people spend money on stupid stuff all the time just to show how rich they are. Leather seats in cars are a terrible idea. They don't actually need a wristwatch to tell time, and it CERTAINLY doesn't need actual mechanical gears. Nobody actually needs pillars to hold up the front of their house. And the fancy ornate parts at the top and bottom were superfluous when they transitioned from wood to stone WAY back there. It's an old trend. tl;dr Tile is fancier than the more utilitarian option. (Stainless steel sheets are probably the most long-term high-utility material. Like the sort you find in restaurant kitchens. But don't they also go with tile floors?)"
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6dg9r7 | When you copy a file to clipboard and then paste it to a different location, what is exactly happening? | Technology | explainlikeimfive | {
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"When you copy a file to the clipboard, the computer fills the clipboard with the path to that file on the filesystem and a tag that indicates that it's a reference to the file (rather than just the text like you would get if you copied that text out of a text file that happened to contain it). When you paste it, the computer looks at the clipboard, sees the tag that indicates that what you're pasting is a file reference, and so understands that it's supposed to treat it as a request to copy the file from its old location to where you pasted it."
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6dga2b | Why Do we need even isp's at this point? Why not make everything peer to peer? | Forgive me if I've used the term peer to peer incorrectly, I mean a decentralised user controlled network(s) that links everyone together thru their own devices. Thanks for any input:) EDIT: I messed up the headline, I meant: Why do we even need isp's. SOLVED. Thank you everyone! :) EDIT 2: Why not have both? I accept it's necessary to have isp's, Why don't we build our own networks on top of them? | Technology | explainlikeimfive | {
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"Well, the obvious question is, whose line do you use to connect yourself to someone on the other side of the atlantic ocean? Laying a cable across the pond costs about $200,000,000, so even if you and your friends all agree to pay for your share on the cable, you probably won't have enough friends to make this effort worthwhile. So you gotta find someone that has laid this cable, and is willing to share it. Next up, do you pay for them, or did they do this cable laying thing as a charity? You'd have to negotiate with them about that. Even if we're just talking about connecting cities, it's still gonna be massive undertaking for someone. How do you organize this thing? You probably want to do some sort of sharing agreement where if someone else uses your cable, you can use their cable in return, and if you're sending traffic through someone a lot, then you should probably pay for them, right? Since otherwise they could just block you from sharing their internet. ISPs do all this sorta thing for you, lay cables, negotiate with all the different companies so they get sweet deals on how you can borrow cables others have laid on ground, and all you need to do is pay your monthly fee to use all of the Internet.",
"I spent 3 hours 30 feet up a 70 year old pole in the pouring ass rain fixing a cable that was hit by a tree yesterday. You gonna do that?",
"OK, so you wire up everyone in your neighborhood peer-to-peer using WiFi. You can't lay cable between your properties because that requires a utility easement and you don't have the resources to hire enough lawyers to work that out. So everyone in your neighborhood is connected via a decent WiFi signal. How do you (and your neighbors) connect to Netflix? They don't have a cable running to your neighborhood. They don't have a WiFi presence either. Someone has to provide a link between your location and the big internet actors. That someone is the ISP.",
"Is this what richard hendriks is trying to do on silicon valley atm?"
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6dh1ad | How did objects that require practice get invented? E.g. why didn't they decide that bicycles weren't usable when they couldn't ride it immediately? | Edit: things like chopsticks, musical instruments, and the like. | Technology | explainlikeimfive | {
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"You have to appreciate the history of the bicycle. We didn't leap from nothing to the penny-farthing. The first historically verified bicycle was a German invention that was called a \"running machine\". It had two wheels and was steerable, and you sat in a saddle and walked. The bicycle allowed you to glide and save effort. It looked much like a modern bicycle with two wheels of equivalent size, a frame, handle bars, and a seat between the two wheels. The penny-farthing eventually evolved because people realized that driving the wheel itself might be more advantageous. At this point, if you can glide on a running machine, it doesn't take much more to drive pedals, you can already maintain balance. They used a gigantic wheel because machining and materials were not sophisticated enough to build chains and gearing, the large wheel allowed you to build appreciable speed. The style of bicycle of the penny-farthing is called a \"Standard\" bicycle. There was a strong desire to build a modern bicycle, called then a \"safety bicycle\", because the standard was quite dangerous in a few scenarios - it had the inclination to pitch you forward and drive your face into the ground. The only thing that held it back was the gearing and chain mechanism, because small wheels under direct drive can't go fast. It was all an evolution, from one working concept to the next, and only a little daring. A lot of early innovation was like this, that the concept is sound, you just have to figure out what you're missing.",
"You're thinking of it in the wrong order. When an object is invented, it has a purpose. You already know what it is for. If you want to throw a knife far away, and you work with strings and sticks every day, it's easy to imagine a bow. You will invent the bow. You'll probably be very bad at it at the start but you know what it is for and if you want to kill some animals without taking any risk, you will practice. For object that are more complexe, like a bicycle, or musical instrument, the practice existed even before the object, it's just before there was a simpler object and we made this new one because it would be better at accomplishing its purpose. It might be harder to use but you will go faster, or you will make better music. String - > harp - > guitar Wheel - > Draisine - > Bicycle The man that invented the bicycle already knew what he was going do to with it. Before even having one.",
"There is certainly a great deal of evolution from easy to practice required as /u/mredding points out. However there is also a reason that your crazy uncle exists from an evolutionary perspective. You know the one I'm talking about. The uncle who goes \"This should work!\" as he does something again and again even as his wife shouts at him to stop messing around with that stupid X. 99 times out of 100 he is wrong and the thing won't work, doesn't work. But once in a while that insane dedication pays off big and we get something cool out of it.",
"Chopsticks are logical. They started out as implements for cooking/ serving. You don't want to stick your hand into the fire? Cool, use some sticks... Also they eventually moved into common place as they are safer than using actual sharp implements to eat with...",
"Humans understand that things take practice. So long as the device works mechanically, and can physically be operated by a human, we know that we can learn to use it, even if it isn't perfect right away. If you understand how a wheel works, and understand how a crank works, and understand that you are physically capable of balancing, then you can deduce that a bicycle will work, even if you've never seen one used before.",
"User Experience Designer here. How easy something is to use first time is *learnability* not *usability*. A learnable thing is easy to learn to use, not necessarily useful. Take a car as an example. It's extremely difficult to learn to use, so much so that you have to have government mandated lessons before you're allowed to use it in public. The pedals, gears, controls and steering while aren't even usually labeled clearly and have no immediate obvious function. Cars are not *learnable*. But once you do learn to drive a car, the interface - the pedals, steering wheel, gears and so on - gives you remarkably good control of a very powerful, very fast and extremely dangerous machine without the need for constant instructions and help. Cars, once learned, are very *usable*.",
"Musical instruments are maybe the hardest to understand. Many of them require thousands of hours to become proficient, much more to achieve mastery. But virtually every musical instrument evolved from something simpler, and that simpler thing from something even simpler still. An oboe is a difficult instrument to play well, but go far enough back and you understand that it evolved (in *many* steps) from simple flute-like instruments that were easy to learn. Ten thousand years ago young people observed older people playing an instrument similar to a modern recorder, and were inspired that their own poor playing could someday equal the talent of the older player. Over time the instrument became more complex, perhaps more notes or a more complete scale. At every improvement more experienced players existed to inspire less skilled players. Woodwinds then evolved to flutes, to single reed instruments, and then to double-reed instruments like the oboe. But every step was slow and gradual, and at every step there were older skilled players to inspire - and teach - less skilled players."
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6dh6zu | How is data transmitted through radio waves? | It is my understanding that data which is transmitted wirelessly is done so through radio waves. What does the raw data look like and how is it interpreted so fast by its recipient? | Technology | explainlikeimfive | {
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"At its simplest, a wave can be characterised by two parameters: frequency (how often it goes from its highest value to its lowest and back), and amplitude (how wide of a difference there is between the peaks and valleys of the wave). [This chart]( URL_2 ) should help clarify what I mean. Let's start with analogue radio, transmitting just audio data. That data can be visualised as a wave, like [this]( URL_1 ). That's basically time going left to right, and value up/down. Transmitting this is basically a matter of communicating what the current value is. Fundamentally, your question boils down to: \"how do we convey this value information over time through radio waves?\" As it stands, there's two popular strategies to solve this problem. One is Amplitude Modulation, the other is Frequency Modulation — you might recognise these as AM/FM radio. Both use the same idea of a a so-called \"carrier wave\" (a wave that has well known amplitude/frequency characteristics), that you then Modulate (tweak) it in such a way that the tweaks are what conveys information. For Amplitude Modulation, you achieve this by modifying the amplitude of the carrier wave. Basically, the amplitude of the carrier maps directly to the value of the signal you're transmitting at each point in time. For Frequency Modulation, you achieve this by modifying the frequency, with higher frequencies corresponding to higher values. [Illustrated]( URL_0 ). When you tune a radio to a certain frequency, you're basically telling it \"decode the data being transmitted over the carrier wave at this frequency\". Now, I assume you originally meant to ask about WiFi, or other such digital communications systems. Well, that's basically the same principle. If you think of binary zeros and ones as being represented by different notes, then you're just playing a song that alternates between those notes _really_ fast. (this is _way_ oversimplified and probably quite misleading, but a good enough approximation for the purpose of illustration)."
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"http://www.hypnotherapyandmeditation.com/wp-content/uploads/2015/12/Frequency-waves-e1449852744201.jpg"
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6dhtzt | What happens when data is compressed? | For instance, compressed folders on our computers. What are the benefits? | Technology | explainlikeimfive | {
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"Compression means the file still does what it's supposed to, but it takes up less memory space. There's two kinds of compression: lossy, and lossless. Lossy means the EXACT value of the data being compressed isn't important, just as long as the file made smaller. Typically this method has a better \"compression ratio\": the resulting compressed version is smallest. In picture files, JPG is a lossy format. If you wanted to compress the value 1.2190000000003 (14 digits), the computer could just squash it to 1.22 (3 digits). It ruins the data a very small amount, but makes it much smaller. Lossless means the data is perfectly preserved, and only makes it smaller where-ever it can. Typically the compression ratio is not as good, but that's the cost of making sure the file's quality doesn't degrade at all. In pictures, PNG is a lossless format. If a lossless codec was used, 1.2190000000003 (14 digits) could be pressed into 1.219[8x0]3 (6 digits). The [8x0] means there are eight repeats of the digit 0. Note that while both these compression methods are smaller than the original, the lossless one is twice the size of the lossy compression. There are many methods of compressing data, and they change widely depending on the thing being compressed: video, audio, picture, text, numbers, etc. But this is the underlying principle: find patterns and tell the computer how to \"fold them up\" and remember how to \"unfold\" them.",
"Another thing to consider... There is a direct relationship between the amount of compression (how small you can make it) and the amount of computing effort it takes. It's like packing a suitcase. You can carry a lot more stuff if you pack carefully rather than just dump stuff into it but it will take you a lot longer. So for a compressed folder you are actually doing processing work every time you want to read or write a file to it. This will slow down the performance of the drive compared to an uncompressed folder. The actual difference could be negligible depending on the relative speed of the processor (CPU) doing the work. The advantage is that you can store more data in a given amount of space. (e.g. hold more pictures)"
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6dkwdb | Why is the internet slow in space stations if they're right next to satellites? | Shouldn't their proximity allow them faster than normal internet? EDIT: my whole life has been a fucking lie | Technology | explainlikeimfive | {
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"Most of the internet doesn't pass through satellites. I'm not sure why being close to unrelated hardware is relevant. Most satellites point their transmitters and receivers at the ground. Being in space they may not be able to reach them at all.",
"To answer your original question: Internet for the International Space Station does connect via a network of satellites, but those satellites are not close to the ISS at all. The space station orbits the Earth at around 250 miles up, but the relay satellites orbit at roughly 22,000 miles up. That means the signal has to go from the ISS up 199,750 miles to a satellite, then back down 22,000 miles to Earth to connect to the internet on the ground, then back up 22,000 miles to the satellite and down 199,750 miles again to reach the station. That results in huge latency, although the bandwith is actually roughly the same as home broadband internet."
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6dlcm7 | Why do we have different battery sizes if they all do the same thing in the same way? | Technology | explainlikeimfive | {
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"To clarify, batteries have a fuel inside them that they convert to electricity (not by burning like gasoline, but through a chemical reaction). A battery that is flat is one that has run out of fuel. Just like a car with a small fuel tank doesn't have less power than one with the same engine but a bigger fuel tank, so two batteries with the same type of fuel produce the same amount of power, but the one with more of this fuel lasts longer. So, as someone else said, you always want as much fuel as you can, but obviously having too much fuel makes your device big and heavy. So batteries come in a range of sizes so that manufacturers of devices can decide the perfect amount of fuel to keep their device running a long time without being too bulky and cumbersome."
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6dlkqq | Why OLED display, which are so successful on mobile and TV markets, is having a hard transition into laptop market? | Technology | explainlikeimfive | {
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"text": [
"You'll note that OLED televisions are *extremely* more expensive than non-OLED. This isn't a big deal on tiny phone displays, but there's not a market for that kind of markup on laptops."
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6dm0qw | Why you must turn your phone to airplane mode on some airlines, while others offer on-flight wifi | Technology | explainlikeimfive | {
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"text": [
"WiFi radios can be set at specific frequencies in the 2.4 and 5ghz range, configurable by the access point. This frequency can be tested to not interfere with the plane's systems. Wifi radios generally transmit at less than a watt, and modern planes with internet access are much more likely to have better quality wiring that reduces interference. With cellular data the radios are stronger because they have to transmit farther, and there is a huge array of frequencies they use: GPRS, Edge, 3G, LTE, etc. Another factor most don't consider is the wireless phone companies don't want you using your phone during takeoff. At several thousand feet and doing 300mph, you're contacting every cell site in town and bouncing from one to another quickly. The likelihood of completing a quality call or getting decent data speeds is low, and you're using a lot of their resources to do it, so they don't want 150 of you trying. So the phone companies pushed the FAA to disallow cell phones on commercial airplanes, but got them to cite nebulous safety reasons.",
"Superstition caused by lack of understanding. When phones were new, they didn't know how they would interfere with the radio transmissions from the Flight Tower, so they banned transmissions outside of official communication during critical parts of the flight, takeoff and landing.",
"Wifi isn't the main thing they worry about. Airplane mode disables all radio services on a device, such as cellular service and Bluetooth. The radio signals could reach the point to where they would interfere with navigation equipment on the plane. But more advanced plans can allow for some of the radio signals to still remain active, that's why some airlines allow you to use wifi."
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6dmalk | How do motion detectors work? | Just curious | Technology | explainlikeimfive | {
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"text": [
"Ultrasonic motion sensors send out a pulse every some milliseconds and records the times it takes for the pulse to reflect back. If something were to move, the pulse would be interfered with and reflect back a different time. Camera motion sensors normally use software to detect whether something in the camera's vision has changed. The same can apply to infrared camera sensors. Laser motion sensors detect whether a beam has been interrupted by an object moving through it. Light motion sensors detect changes in the amount of ambient light in an area. The ambient light reading will change as something moves. Similar can be said about temperature sensors e.g. If a warm object moves into a fairly cool room, the ambient temperature will rise. ^(it's 3 am I hope I didn't blatantly miss something)",
"Passive infra-red detectors use a sensor and a special lense to detect the movement of heat. Typically the sensor has two circuits that compare between each other. The lense adds to this by allowing the heat source (people) to be projected across the sensor. Activating one side of the sensor before the other. By comparing the two different movements the sensor \"knows\" that a person is walking past it. It \"knows\" that a single heat source isn't warming up like a radiator or something.. TL/DR Passive sensors have a special lense and a special double sensor that works on movement."
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6dmsft | Why does Windows even allow deleting system32 if doing so will make it unusable? | Title | Technology | explainlikeimfive | {
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"The reason that they allow you to do it is because sometimes it is fundamentally necessary to delete, change, or add files to system32 in order to fix bugs in the system or upgrade things. The user either has access to the files or doesn't have access to the files. If they have access to the files, they can do what they want with them, including deleting them. If you create an account that isn't an administrator account you won't be able to delete System32, or many other important things. You also can't install programs. Windows has a very extensive permissions system and you can tune the permissions to change what certain users can and cannot do. Ideally, you should be running as a non-administrator all the time, and then only switch into the admin account when you actually need to do something that requires the extra permissions.",
"They're files. Files can get deleted. Normally, system files like that are going to be hidden & protected & flagged as system files so you can't just click \"delete\" but if you want to do something fundamentally stupid, you're free to do it.",
"Because in Windows, most users are logged in with administrative privileges. When you are an administrator, you're allowed to do almost whatever you want, for whatever reason, because administrators are supposed to know what they're doing. In fact, the administrator user in windows is actually *more* restrictive than the equivalent in Linux. Some files can't be touched even as an administrator in windows, while in linux, the \"root\" user can literally delete any file at any time, even if the file is currently in use. The entire OS can be deleted while the OS is in use if you're root. Ideally, you shouldn't be logged in as an admin all the time in windows, but that has unfortunately become the norm for home computers. Normal users aren't allowed to touch anything that aren't their own files, and are denied access to critical system files."
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6dn73w | Why do subwoofers use exposed wires and clips instead of a regular plug? | Technology | explainlikeimfive | {
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"text": [
"Not just subwoofers, but a whole range of home-theatre type speakers, use exposed wires because people can use a custom length of wire without worrying about A) buying potentially expensive pre-made wires that might not even be the exact right length, or B) the time consuming process of crimping a plug to the end of each wire you want to use. Compatibility is also a concern. Many high end audio customers with have a mix of several different brands in their audio setups and the companies they buy from recognise this. Therefore, speaker and amplifier manufacturers may decide against RCA/3.5mm/proprietary plugs. In the end, its all about flexibility for the user."
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6dnium | Why do lights flicker when you turn a high powered machine on? | For example: a vacuum cleaner. Why do the lights flicker for a second when you click the "on" switch? | Technology | explainlikeimfive | {
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"When you turn on any high current motor, it pulls in excessive current called an \"inrush\". This is always higher than running current. This is because interia properties resist change, so it takes more current to start a motor than to run it, it's under load. That big of a jolt on the system causes a super quick drain on the rest of the circuit and inturn makes lights flicker a little bit. The same goes true for turning on big coils or fields (large pieces of wire wound together for motors or other devices). When setting up starter units (things that start motors), I've had to use up to 200-300% of rated current to successfully bring the motor up to speed quickly enough to allow the unit to start correctly. High current motors are found in vacuums, compressors (AC, refrigerator, etc), large fans and even huge computer power supplies."
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6dnj0s | What does it mean if my drone has an max altitude of 500m. If I climb a 500m mountain, would it fly to 1000m above surrounding area or would it not be able to fly? What about people who live in high altitude areas like Denver or Tibet? | Technology | explainlikeimfive | {
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"It's probably the connection area in regards to the controller. It can fly 500m away from controller before it looses connection.",
"I suggest this: If it is about the distance from thaa controller, what if we send one drone up high, when in like 400m we will send another drone up in the same speed as the prev' one, with the controller of the first attached to it and set to keep fly the drone up, and we will do the same with a third and forth drone so on... What is the maximum number of drones we can send up?? Can we reach the moon? How high can we get???",
"In the US, 400 feet is the highest you're supposed to go. It's an airspace regulation. Most consumer drones designed to be used outdoors can fly many times higher, but they become limited on battery and flight time. Your drone might have a several mile transmission range, but it takes so much battery to ascend you won't get close to that max range before you have to start descending to safely land",
"I believe its 500m above take off point. So if you where standing on top of a 500m mountain, it would climb to 500m above you. It depends what drone you're using as well",
"Additionally... at a given velocity, aiirfoils need a certain amount of air density to produce lift. The higher the altitude, the lower the density, so velocity would need to increase to generate lift.",
"Entirely due to how close it needs to be to the controller. So it is distance above you rather than altitude."
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6dnzr5 | How are lightning strikes detected so that they can be displayed on maps online? | I've seen the UK Met Office display maps showing lightning strikes, and I sometimes use URL_0 when there's a thunderstorm nearby. How are the lightning strikes so accurately displayed? It looks like they're tracked by stations around the country, but how do these stations detect lightning strikes, sometimes many many miles away? | Technology | explainlikeimfive | {
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"When lightning strikes happen, they emit a radio signature on a predictable set of frequencies. So, it's really a matter of listening to those frequencies from multiple locations, and using triangulation to determine the location. This happens very fast. My weather app routinely reports a nearby lightning strike before the thunder gets to me."
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6dpb2p | why do some trucks have a pair of wheels that's a bit off the ground? | what purpose does that serve? and I don't think it's necessarily because of the risk of tipping over, because some of these trucks are quite long, and the risk of tipping is very low. | Technology | explainlikeimfive | {
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"They do touch the ground, once they are heavy enough, they need to be on the ground to relieve stress on the other axles. They are then raised when going around corners/bends so that they don't drag. They are like the raised axles on a transport truck.",
"They are called drop axles. They are raised when not needed, so as to save on tire wear. When the truck is loaded, they can be dropped down to relieve weight from (usually) the front axle to avoid getting an overweight ticket. The weird ones are the ones that have 4 drop axles. They look like caterpillars to me.",
"As others have said, it's to keep the weight legal when they are heavy. But why not just keep them down all the time? Well, in addition to saving wheel wear, (truck tires are expensive) they also save on tolls. Many tolls are based on how many axles you have, and an additional axle shoots the toll up substantially. If you can raise that axle, you now have significantly cheaper tolls. Edit: I can speel...",
"I run Michigan with a six axle fuel trailer. The first and last axle are self steering. Self steering axles are required by law in Ontario . The second axle on the trailer we call a Michigan lift axle. We are required to have it down when loaded in the state of Michigan, but if we cross into Ontario we have to lift it because it's not required under their weight restrictions. The combination allows us to run in excess of 120,000 pounds of loaded weight. And as has been said, but we're not loaded we only have three axles on the ground and three of them are lifted.",
"There are laws which mandate how many wheels are on the ground based on the weight of the load. So when the truck is real heavy, those wheels are deployed. When the truck is empty, or light enough, those axles are raised.",
"Other reasons that tag axles/drop axles are raised: when they are down, not only are they wearing the tires, but they also make manoeuvring much more difficult; they drag in the corners, making it harder to do tight turns, driving down fuel economy, and raising sideways stress on the frame. In some regions, they have been made illegal precisely because they reduce manoeuvrability; in my Canadian province of Manitoba, they were outlawed back in the '90s. You still see them on a few older farm trucks that have either been grandfathered in, or just haven't been caught yet due to lax rural enforcement.",
"Weight limits on trucks are both total weight and weight per axle. They're dropped down and used when necessary to lower the weight per axle and raised when not needed because they create extra drag and wear like crazy during any sort of turning.",
"The weight to length ratio of transport trucks in the USA must be within a set limit for interstate travel. This is for the purpose of not overloading bridges. So trailer length, number of axles and load all come into play. With a heavy load, the extra axles can be dropped to bear some of the load to ensure bridge load and axle load limits are not exceeded. Read more, and see the equation here: URL_0",
"Tires have a max load weight usually you see this set up on trucks that will have chances of carrying really heavy loads. Like garbage trucks 80% of the time they are not heavy then they get to one stop that has scrap metal or heavy trash and the wheels need the weight taken and distributed over another set to be legal and safe to drive. So there wont be a a blow out going around a corner.",
"Your talking about these? URL_1 In Europe there is a standard (nicknamed 2x4) of a unit being able to pull a trailer off 34tons over large distances, removing the \"tug axle\" (it's name) allows for dual lager fuel tanks. URL_3 Now, come the to uk, where these 2x4s become 2x6s, as by our laws of road transport we can carry 44 tons, on a 40 foot trailer. however we also fall under the EU regs, whilst if you have a \"2x4\" you can only carry 34tons. It basically saves the road a little and allows more weight to be carried on the rear axle of the unit. Q Edit, if you ever see a trailer with a wheel above the ground, it acts the same way, if it needs to allow more weight it will lower if not it wont. they just allow you to pull more shit over axles. Source, UK trucker 14 years ninja edit 2, some links to more examples of tug axles [26ton with tug]( URL_2 ) Bonus edit, if the above tuck didn't have the tug, it would be an 18tonner [artic with tug down]( URL_0 ) super super ninja edit, tug axled trailers do exists her in the EU, mainly seen by me by my European counterparts in the places i got however I can't seem to find a picture online"
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6dq1bz | why is there not cell phone service everywhere yet? | Technology | explainlikeimfive | {
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"Cell phone towers are expensive to build and operate, plus leasing the land, wireless spectrum, and local regulations."
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6drc2c | Why are there so many different types of hard hats? What's the functional difference between, say, a construction helmet and a bicycle helmet? | I understand that some helmets need to be very specialized, such as a combat helmet against fast-moving projectiles. But a lot of civilian helmets seem to protect against the same kind of threat - something heavy and relatively slow-moving hitting you on the head, or alternatively you hitting something. We have bicycle helmets, motorcycle helmets, construction helmets, firefighter helmets, all kinds of sports helmets -- all looking completely different. Wouldn't there only be so much "optimal" designs to protect one's head? | Technology | explainlikeimfive | {
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"It's what your protecting against, in a motorcycle accident your trying to protect the whole head, in a construction site? Falling debris, bicycle similar to a motorcycle but much slower moving, firefighters, exactly like a construction helmet, but the debris is on fire, the design isn't all that different its just slight differences and settings that we think it's different",
"No. A bicyclist needs a helmet that protects their head from immediate impact injuries, has a slippery surface so they will skid rather than break their neck, and the helmet needs to be aerodynamic to let the cyclist move fast. A construction hard hat needs to protect from objects falling from above, needs to have slots to be augmented with things like hearing protection and visors, and needs to be comfortable for long periods of work, ideally as light as possible. A fireman's helmet needs to be heat-resistant and able to integrate with SCBA masks Helmets for other sports need to be shaped for the most likely impact direction, and need to be light and comfy."
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6dsk72 | Why do some gifs load fine on the Reddit app but others won't? | I've noticed it when swiping through pages, gifs will load fine, then one won't, then the next few will and one won't again, so I'm pretty sure it's not my internet connection. And it doesn't matter if I click into it or refresh the page. Am I missing something? | Technology | explainlikeimfive | {
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"I don't know why either. Happens to maybe 20% of gifs. There is an easy fix though. If it doesn't load, click the word 'imgur' just above the post title. Works a treat."
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6dtjhv | Why does Facebook Messenger and other similar apps on the app store have random 150mb updates a few times a week? | I don't see any difference in the app at all once i update it, why is it around 150mb every time? | Technology | explainlikeimfive | {
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"Because it's easier for them, and no one really complains about it. They *could* structure the app so that smaller parts of the app could be updated individually without having to redownload the entire app. Or they could wait longer between updates and roll all the changes up into one 150mb change every 3 months. But everyone happily downloads those 150mb every time, so they don't really have an incentive to do anything about it. And for them, it's simpler to just ship a new copy of everything any time they make even the smallest change.",
"Software developer here, but not an Android developer. The way Java programs are normally distributed are through files called Jars. The one file contains all of the code necessary to run the program. When you update the app, you normally replace the entire jar file. So the update being the same size every time would be consistent with a full replacement of an entire program file.",
"The Apple App store only allows you to upload a 'full' app file. They do not offer a way for you to 'overwrite' an existing app with only the updated sections. If you wish to update your app on Apple, you have no choice but to push the full and updated file. In cases like the Facebook app, which is quite large... it means re-downloading the full 130+ MB file each time. P.S - I don't know about Android so I cant comment on if it's the same for that.",
"No one is really addressing why. Security is a huge reason. Stability etc. When a flaw happens, say a virus/exploit is found they have to patch it or risk having the app hacked and your information leaked or your phone compromised. It could be stability issues such as the app acting badly, due to a previous update that they now have to fix. So they have to release it ASAP so therefore they release these types of things as soon as they can so neither of these things happen. They can also add new things like emoji, languages, corrections to dictionaries, etc as well. So many reasons to release these things."
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6dvwg9 | Why Aren't Resolutions Like 8k (and even higher) More Available. Comparing a 1080p phone screen size to something like a 60" TV gives me the impression a higher pixel density should be easily achievable. | Technology | explainlikeimfive | {
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"Denser concentrations of electronic components employ vastly more expensive manufacturing processes. The display accounts for a significant portion of the cost of producing your phone. So, even assuming price and size scale linearly (which they don't), if your 15- square-inch phone display costs $250 to produce, the cost of a 65\" panel at 500+ dpi would be somewhere north of thirty grand. That, coupled with the fact that there's no content that could be displayed at that resolution, makes the sale of such a device practically impossible.",
"People won't pay for them. People won't pay for them because there's no content for them (and as ninja said they'd cost 30,000$). There's no content for them because it's impossible to transmit that much detail on anything short of fiber-optic wire(as zei said). And frankly you can't tell the difference. pixils/inch suffers from a diminishing utility curve just like frames per second. Most people can't tell the difference between 100 FPS and 250 FPS and 1080p is fine for the current size of most TVs. In movie theaters they could produce much higher resolutions (for more money) but they don't because they get a bigger bang for the buck by going full 3d or serving beer."
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6dw073 | Why a coder can't simply "decompile" an executable to get perfect source code for reverse engineering a piece of software? | Technology | explainlikeimfive | {
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"Because the compiler preforms many irreversible changes to the code. At the very least, comments and variable names are removed, names of private functions are obfuscated, and the code is optimized to make it run faster and better. However, certain programming languages, such as Java and C#, are compiled into a intermediate language which is similar to the original source language, and these indeed can be decompiled fairly successfully (just lookup Java Decompiler or .NET Decompiler).",
"To put it very simply; the source code is 3*8+2. After compiling it the output is 26. As you can see it's pretty impossible to get the same source code just from 26.",
"In non-programmer terms: When a programmer writes code, a lot of what is written is done so in a way that humans can understand. For example, if the code has a value that represents the size of the screen, the programmer may choose to call that \"screenSize\" in his code; not because it's necessary for the code to work, but because it's easier to read and understand. When code is compiled into an executable form, all these \"niceties\" in the code are discarded away, because they are not needed for the computer to run the code. As a result, while you can then reverse engineer this compiled code, what you'll get back is only what the computer CPU needed to run, not all the niceties the developer wrote to understand and follow the code. The decompiled code will still work, but you may only see \"grfjtkbh\" instead of \"screenSize\" for the value that represents the screen size. Applied to a large amount of code, the decompiled version losses a lot of information in the original code, almost to the point where everything looks like a garbled mess.",
"The binary code is machine language. This can be \"disassembled\" into assembly language, but only the most scary programmers work on assembly language programs. Programs written in high level languages can't be easily \"decompiled\" because the compiler typically contains an instruction order optimizer that seeks to eliminate redundant operations by manipulating register assignments and reordering instructions. This process destroys information needed to reverse it, so there are several sequences possible for each optimized output instruction group. That's going to lead to code that isn't understandable. Not to mention most variable names and all the embedded comments are lost in the compilation process. That's before things are done to obscure the code intentionally, or the operating systems does its address space randomization.",
"Compiled languages like c and c++ are converted to raw assembly code during the compile process. The compiler optimizes the assembly code as much as possible. So a loop that prints the numbers 1-10 might be produced as 10 separate print statements rather than an actual loop. It does this when the cpu cycles to generate a loop exceed the number of instructions for successive print statements. Decompiled code won't really even look like straight up c code, but will look like pseudo code when run through things like ida pro. The decompiler won't necessarily know if it was written in c vs c++ vs c#. Also, major software is probably obfuscated in such a way to make it harder to reverse engineer."
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6dx80z | How do anti-malware programs determine what is malware and what isn't? | Title. How does software like that determine malware from its harmless file counterparts? Is there any chance it could remove/quarantine a harmless file/program? | Technology | explainlikeimfive | {
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"One of the oldest methods is the signature based detection, this is basically a big list of \"this file is bad\", unfortunately malware creation kits allow people with no skill to pump out vast numbers of new malware so this method is not viable any more. Another old method is the heuristic detection, rather than looking for an entire bad program, they look for bits of code used by malware writers, this is great because the automated toolkits that make new versions of the old malware generally just re-arrange older code to try and get past security tools. The problem is you need to rip apart the malware that gets through and update your heuristic signatures. But if the malware gets through how do you know to pick it apart? One of the more common techniques is to apply a weighting to the program and watch it. If the program starts watching your keyboard, add a few points to the bad side of the scale. If it starts talking to the internet again add \"bad\" points but not a lot as it could be legitimate. If it accesses a site known to be used by malware, add a whole bunch of \"bad\" points and so on. Once the program racks up enough bad points kill it and tell the user. The continuous monitoring of the program is necessary because malware will often be designed to modify itself or download extra bits whilst it is running to try and hide from older types of antivirus software.",
"Depends on the type of Anti-Malware program it is. The first kind of protection is signature based. This means that there is some database that exists that lists the signatures of known malware and if it's detected, the program is notified. So this only works when the malware is known to exist. The second is anomaly based. This contrasts with signature in the sense that for this type, there exists a known behavior of the system that it exists on. Anything that is outside of that known behavior is known as an anomaly and is registered as a possible threat. They each have their pros and cons. Signature is generally faster but is more susceptible to new malware or zero day attacks."
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6e0ki6 | How does dust affect the computer? | Additionally, why does it seem like the performance increases when I clean the dust out of my PC? | Technology | explainlikeimfive | {
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"Dust makes the system hotter, both by directly insulating the cooling surfaces and by restricting airflow. If you remove the dust, the cooling system can run more efficiently, which lets the CPU boost its clock rate. Dust *literally* makes your system slower.",
"The components in your computer heat up as you use them. The harder they work, the more heat they produce. Too much heat will damage your computer. This is why computers need fans to cool them down. The problem with dust is that it causes the components in a computer to retain heat, making it harder for the fans to cool the computer. If the components in your computer get hot enough, they will throttle themselves so that they produce less heat to prevent damage. Your computer does this more often when the dust builds up in it.",
"Dust interferes with the heat sinks. The heat sinks take heat away from the components. When there is more heat, the components like the CPU and GPU slow down to prevent overheating. Keep cleaning the dust out of the computer and your computer will keep running fast.",
"Because dust on electrical components trap the heat they produce much better than open air does. Electrical components works worse the hotter they become which is why you see a performance boost when you clean your computer. Additionally, dust on your fans make them less able to push air through them and can also unbalance them which causes an annoying sound when they spin faster. In short all the components inside the computer gets covered in dust, which means they become hotter, which means the fans spin faster and more dust is sucked into the computer. So clean your computer at least two times per year."
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6e2wgs | Why ads appear to load fine even when internet is bad? | Say Im on Reddit, and my wifi internet connection is terrible. Why is it that ads and add videos appear to load without a problem, while I can barely load a gif from the discussion ? Do ads and such get a "special" treatment by internet routers? Do ads use my 4g since that would be faster ? Am I just making up some conspiracy theories? | Technology | explainlikeimfive | {
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"Ads are usually being fed through google, or an ad network. Even if reddit servers are slow, the the webpage is telling the ad to load from a different server. And ad servers are typically very very fast.",
"Most websites have scripts. The scripts often cause the site to load the ads first. There are scripts for over things that block the rendering of content before certain parts are loaded. These scripts cause longer rendering times. It is also a nuisance that will make people leave the website."
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6e360t | How do inventors search through the enormous patent database to make sure their new invention doesn't infringe on prior art? | I read somewhere that there are roughly 9 million and more patents. This is an absurd number to search through. Also, how thorough are patent researchers/lawyers at finding this stuff out? | Technology | explainlikeimfive | {
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"It is difficult. The bottom line is you do your best to find prior art and then apply. Longer answer: searching has become pretty good these days. There are a lot of search strategies. You can search for key words that you think anybody would use when they applied for their patents. You can look for other products or ideas that are in the area that you are interested in. You can look at the patents of other companies and inventors in that area. Patents are also classified according to the areas that they pertain to. You can look at other patents in that area. You can look at the citations of prior art in other patents. You can use a combination of all the above. Some companies subscribe to a patent database that has very good search tools. It is much better than Googling for what you are looking for. As for how thorough lawyers are in searching? You never know for sure. Really the best bet are others in the area of interest that you are applying in. People in the same business know the business pretty well. Lawyers also hire a lot of this work out. Yes, you guessed it...India does a lot of it and it is resold to US attys. With my current patent application the atty said that their current searching only turns up prior art about 50% of the time BUT almost every patent application gets denied the first time. In other words you try your best to anticipate running into prior art that causes trouble for your patent but the patent examiner may turn up other information. You just have to deal with that when you get there. That is why you hire a good atty. There is a lot of strategy. Also, big complanies have access to certain resources that small companies and small inventors do not have. Any search strategy you can think of can be made into an automated update that comes to your email once a day, week, month or year. These searches can be done by hand by actual people at a chosen interval. Lastly, patents are usually expensive to get. You really want a good business case to get one. Don't buy into the idea that you can get them for a few hundred dollars. If it sounds too good to be true it usually is. The patent claims and how they are structured is everything. A good atty is worth it when it comes to structuring these right. Why do I know? I've applied for a few."
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6e3j0g | How do my Google searches on one device show up as Facebook ads on another device if neither device are connected in any way? | Here is the scenario: I have a work laptop and my Android phone. I search for a very obscure and specific thing on my work laptop and it shows up as ads on my Facebook app. Here's the kicker: There is no connection between the devices i.e. I dont use any personal emails or social accounts on my work laptop so there is no profile on there to connect me to my phone, nor do I connect my phone to my work network. How did they curate ads to something I searched on my worklap to my phone almost immediately? Keep in mind the ads are extremely specific and in no way is this a coincidence. | Technology | explainlikeimfive | {
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"On your Android phone Google has access to your phone's info - your phone number, name, your contacts, device information, etc, in fact, it is likely tracking your physical location, wired and wireless networks. On your laptop you may have similar contacts, location, connected networks, browsing history - Comparing all these facts yields a high probability of it being the same person. Welcome to machine learning Suggest reading if deeply curious Big Data: A Revolution that will Transform How We Live, Work and Think URL_1 Or In The Plex: How Google Thinks, Works, and Shapes Our Lives URL_0",
"Do you sign into Google Chrome at all on both devices?",
"Does your phone connect to the same wifi as your laptop?",
"If this happens repeatedly, I'd say at some point you logged into your work computer from one of your personal accounts and now have a cookie planted on the laptop. If the phone / computer are connected to the same WiFi, this would also explain it. However, if this just happened once or rarely, it could be attributed to one of Facebook's ad options, which is location based advertising or \"radius targeting\". Basically this is Facebook showing ads based on what people are searching for at your location, or within a specified radius of a certain point. Honestly with the abilities Google and Facebook have in this day and age to track people, it wouldn't surprise me if they can take your laptops IP address and your phones GPS coordinates (which they know are at the same location during work hours - half the battle won already), combine that with whatever other secret algorithms and such they use, maybe make connections between search history / behavior on phone / computer, and it wouldn't surprise me at all if they can determine with relatively good accuracy that they're both your devices. PS - That's not paranoia, that's just reality :)",
"Just my two cents: is it possible that someone you know has registered you in their contacts with two email addresses in a single contact entry? Something like: work e-mail, home e-mail ?",
"Microphones listen and help generate ads too- my wife talked about a particular item and I got ads on my phone for it a couple days later.",
"You're going to love this one. Facebook messenger has a \"continuous contact upload.\" This meaning, a friend or cowork might have your contact uploaded to Facebook that would show email addresses and phone numbers connected to each other. Therefore, if an email would set cookies on you, it would be able to cross reference them across devices. Therefore, laptop one has work email, laptop two has personal email, friends/coworkers have contact with both saved under a single contact. This would then connect usage habits, with location, with time frame, with typing speed, with permission preferences, with devices connected on the same network. All pretty fun stuff.",
"Big Data is tracking you and connecting everything they can get about you. The more data they have, the better is their conclusion of who you are and what you do. Your phone revealed your identity and frequent whereabouts as / u/ EasternSons/ / u/ EasternSons/device/yourphone / u/ EasternSons/location/work / u/ EasternSons/location/home. If they also have enough data about / location/work/u/ (all), they can identify and eliminate other / u/ (all)/location/work/device/(all) and conclude: / u/ EasternSons must be the one doing only work related stuff plus /interest/this-obscurity with / u/ EasternSons/location/work/device/yourlaptop. / u/ EasternSons/interest/this-obscurity. Now they make their ad network starts sending /interest/this-obscurity tagged ads to / u/ EasternSons/device/yourphone to make you buy the advertised item. They could even send it to location/work/u/(all)/device/(all) because it's very probably work related and they want all of your coworkers to buy that thing aaand / u/ yourboss might want a word with you about wtf you're doing all day. Edit: accidentally made some unwanted links, added spaces into /u/ to / u/",
"Some more information might help like: What services are common between the devices Did that search play any audio Can you confirm the devices are on the same network? If so, what carrier? It's possible that your ISP inserted a \"super-cookie\" into your work laptop's data, which would correlate the laptop with your phone as if they're on the same network, they might get the same super-cookie. Taking this further, Google and Facebook might share \"super-cookie data\" with one another."
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6e4vgd | Why do some websites stick an ad on every open nook and cranny that isn't occupied? | Technology | explainlikeimfive | {
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"Ad space is sellable and making money is often the goal of a website. When a product is offered free, you are the product."
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6e61bj | What must developers do, to convert a game from Pc to a console? | Like what must they take care of and change that it will be playable on another platform. | Technology | explainlikeimfive | {
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"They have to revise alot of the base programming. A PC (read Windows) program uses alot of the preprogrammed functions that windows has. Things like how to draw fonts, how to save files, how to draw circles, how to keep time, how to know input controllers. A console has a different set of preprogrammed functions in its OS. Functions that are named differently, functions that may work differently, functions that may not exist. You have to account for all those differences."
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6e73wq | Since America has different time zones, are tv shows aired at the same time or at different time in different cities? | Living in Germany we have only one time zone so when a show starts at 8.15 pm it's 8.15. pm everywhere in the country. But when it's 8.15 pm in New York it's (I think) 5.15 pm in Los Angeles. So when a TV show (excluding live shows of course) is let's say aired at 8.15 pm in New York is it aired at 5.15 pm in Los Angeles or is it also aired at 8.15 pm in Los Angeles which would mean, that it would be aired 3 hours earlier in New York. How does it work? I hoped I phrased my question somewhat understandable | Technology | explainlikeimfive | {
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"In the US, you generally have East Coast TV feeds and West Coast TV feeds. The other time zones are far less populated so Central Time get's the Eastern Time feed & Mountain Time generally gets the West Coast feed and those people just have to live with the inconvenience. It's actually very common to see TV shows advertised as being \"8/9 central\" to indicate that Central Time gets them at a different time. This makes things really interesting for sports fans who insist on watching things live. During NFL season, if you live on the West Coast, your team might play an East Coast team and start playing at 9-10am Sunday morning (which makes watching the game at the bar kind of weird). For East Coast fans, a late day game on the West Coast might not be over until after midnight."
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6e7q4e | how does my cell phone receive a call, or make a call, from my hand to a cell tower into someone else's hand almost anywhere on the planet nearly instantly? It seems with so many phones out there the process is infinitely complicated, yet it all happens in seconds. | Technology | explainlikeimfive | {
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"Cell towers generally communicate with each other through fiber optic cables which means your signals are going the speed of light. So at 186,000 miles a second there isn't anywhere in the world that is further than a second away. Your phone is \"provisioned\" prior to operation so when you start to dial it's ready to make the call already. Now it just needs to transport the data.",
"This is why we use computers for all aspects of telecommunications. The Unix operating system was developed by Bell Labs, the phone company's research lab. Your phone only talks to a tower near you. Your friend's cell phone only talks to a tower near them. Even if the phones are in the same room, they don't talk to each other. Once the bytes (almost all phone calls are digital nowadays) get to the tower, they spread out as IP messages across the worldwide phone network. They use a system called SS7 (very creatively for Signaling System, version 7). You may have noted that phone numbers have a structure: country code, area or city code, exchange, and number. You don't always have to dial all of it in some regions of the world. This structure makes it easier for the computers to figure out which tower can talk to the phone in question.",
"When you hit \"call\" on your phone, your phone takes a few milliseconds to process and then broadcasts a signal at the speed of light. The cell tower receives this and internally in the base station software directs the call to the wired telephone network, where your signal travels at the speed of light to the exchange and central office, where the target number is matched to the network that own it, and then sent thru wired network at the speed of light to the cell tower that phone is last logged into. The tower then broadcasts a signal for that phone at the speed of light and the phone receives it an rings."
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6e8rq6 | In HBO's Silicon Valley, they mention a "decentralized internet". Isn't the internet already decentralized? What's the difference? | Technology | explainlikeimfive | {
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"The internet actually is *decentralized* - in fact it was originally designed that way by the military to exist as a communication network that couldn't be compromised by bringing down any one node. What they're talking about on Silicon Valley is moving from a *client-server* internet to a *peer-to-peer* internet. Now what does that mean? So in the current server-client world, when you click on a link on say, Reddit, your computer sends a request to Reddit's server asking for the content for that page. The server then sends the content back to your computer, and your browser presents it on the screen. What Silicon Valley is talking about is taking the server out of the equation. Because of their magical compression algorithm, instead of a server, all of Reddit would be stored in pieces on the smartphones of individual users. When you made a request, it would fetch the data from those smartphones instead of the server. But honestly this is pretty far-fetched. Even if there was some magical compression algorithm that could make the data-storage requirements realistic, there's no way a network of smartphones could do all the work currently done by servers. The biggest limiting factors of smartphone use are bandwidth and battery life, and if your phone was serving requests all day and night it would eat up your bandwidth and your battery pretty quickly. The most recent versions of Android for example have tried to limit how active apps can be in the background to save network and battery life, and this would be going really far in the opposite direction.",
"In that show, they also show lots of shots of server farms, where there are thousands of rows of servers operating quietly in the dark. His new company is trying to eliminate the needs for those thousands of servers. And instead use available capacity on people's phones to store and serve up data. The internet is decentralized, and technically any computer in anyone's house could act like a server, but practically speaking, most of today's internet data is stored in these server farms owned by companies and institutions like Google, Wikipedia, Amazon, etc. It's done this way for speed and security reasons. Richard is trying to make individual phones able to store little pieces of it using his magical compression. Footnote: It doesn't actually have to make sense since it's just a premise for comedy writing. It just has to sound like something revolutionary that would cause buzz in Silicon Valley. So the fact that it is at all plausible is really just extra effort from the writers to make the show more entertaining for real engineers.",
"Check out something called Ethereum. Google it, it will be the first thing. Many things are being built on it, and you will see the capabilities.",
"There are two perspectives to decentralization - infrastructure and content. In our present day internet, most of the content is hosted on a central server somewhere. So if you request URL_0 it asks the Reddit server for the webpage. If that server is down due to maintenance or attacks, you can't get the site. This is also prone to censorship (see Turkey for example). However you could also host the site decentralized (look at IPFS or Storj for examples) so it is stored on multiple independent computers and when it gets requested, it gets pulled from whatever participating computer it's stored on. Now an attacker/government can't target a specific site and you don't have a single point of failure. Infrastructure is a bit more complicated. You could argue it's decentralized but in reality most of it belongs to a few big companies. The wires, the backbones, the majority of servers. This makes users dependent and puts the power to the corporations. A decentralized infrastructure would be independent connections like WiFi mesh networks. So if you want to connect to a server, instead of going through a hierarchical connection via your ISP you would connect to your neighbor, their neighbor, and so on till you're at your destination. However this would be horrible for the latency of the connection and won't work unless a large number of people join in.",
"The product they are building (distributed file-storage across many devices) basically already exists: URL_0 -- IPFS just doesn't have any sort of magic compression algorithm beyond what already is available.",
"I came to to say Ethereum. It's already here, billions of dollars is pouring in every day from around the world. The future is now!",
"We are creating the building blocks for this as we speak. Ethereum, Golem, things like Storj and SiaCoin are all nascent pieces that when properly developed could lead to this very thing",
"Yes the Internet is structurally decentralized, but it has become financially, economically, and operationally centralized to ISPs like Comcast, aggregators/indexers like Google, and social networks like Facebook. The vision of the Silicon Valley \"decentralized Internet\" is to reclaim this by allowing individual users to have the same theoretical power as these three companies without compromising their choice, freedom, or financial decisions. Practically speaking, this is actually becoming a reality today through decentralized networks like Bitcoin, Ethereum (and other Blockchain-based distributed networks), Bittorrent and TOR. For true ELI5 explanation, being a user on Silicon Valley's decentralized Internet would be like empowering every user's local lemonade stand to have the distribution, marketing, and sales potential of a Coca Cola.",
"The internet architecture is decentralized, but the services used are really not decentralized at all. When you store your photos \"on the cloud\" you're really relying on Facebook, Google, Amazon, Imgur, or someone else to keep those photos for you. If that service goes away, then bye bye your data. This is not unprecedented. If you had the magical compression algorithm that Silicon Valley has as its core conceit, then a lot of interesting things become possible. Middle out encryption assumes that you can both highly compress something AND search it without an index, IIRC, which is quite frankly insane. In theory you could store all your pictures in triplicate on other devices (why they focus on phones I have no idea, desktops are better) at a small cost. Richard's idea already exists in the form of URL_0 but freenet is slow as balls and has some major limitations. If you took freenet and added middle out encryption it would be pretty awesome, both for publishing data and for privately backing it up.",
"Decentralization is not a yes or no thing. You can actually count the amount of decentralization that exists on a network. For example, the internet at your school is probably through a link that your school has to the ISP. All the computers in the school are probably connected to a single routing server (at least). Thus, as far as the school computers are concerned, the internet is centralized - because it comes from a single routing server. If that server went down, the whole school would lose internet. The maximum amount of centralization that can exist is when all computers are connected to a single UltimateInternetProvider computer. The maximum amount of decentralization is when eery computer on the internet can talk directly to any other computer on the internet. In reality, ISPs, data centers etc. mean that the actual world wide web is somewhere in between...not completely centralized but also not completely decentralized. Anything that is *more* decentralized than the current situation is touted as decentralization - especially on TV where things are dumbed down for the wide audience.",
"Isn't Etherium meant to be something like this?",
"They might mean without niminet and dhcp. Bit torrent is kind of like this. No computer has a map of the whole network, but each has a list of its immediate neighbours. I'm probably about to get schooled by someone who does this for a living, but hopefully this is a good start.",
"I can't say what was being talked about on Silicon Valley, but I have heard of ideas that if the internet in its current form were taken down (such as happened in at least one country during the Arab Spring), people could form fairly large networks by bridging together the very large number of wifi routers that people already own and use. The way networking usually works, your phone uses wifi to talk to a router over the air, and the router is connected to a physical wire that leads to the greater physical network. When you bridge wifi devices, your phone might talk to Router B over the air, which then passes on the message to router A over the air, and A sends that message through the wire to the network. This is slower and less reliable, but lets you get network signal to more places without running wires. So the idea for the distributed network is that if the internet is not available, we set up all our routers so that I can send messages from my phone to router B, that passes to router A, that passes to your phone. But none of those connections had wires between them, all were wifi. And we can add a lot of routers between A and B and software can help figure out where to send the messages so it actually makes it to your phone. That can make the area covered by the network very large, but every router we add between A and B makes the messages take longer. Your average Wifi router is currently either not capable of bridging in this way, or is at most capable of bridging on a small scale with very similarly configured routers. (Sometimes requiring the same brand or even the same model.) To actually form a larger wifi network like this would require changing the software on most of the wifi routers. As well, that network would not magically be able to do everything the internet we know, can. For example, there would be no way to get to Reddit unless those servers were somehow connected, and every other site would have the same problem. Overall, this is an interesting idea for an emergency, but not likely practically. Edited to add a better explanation of bridging, added examples, and to simplify some things.",
"Decentralized but only so much as DNS (**D**omain **N**ame **S**ervers) will allow you to become. DNS is a centralized repository of what URL (**U**niform **R**esource **L**ocator) - or website name - goes to what IP address. Seems like there was an attack against DNS not to awful long ago (Servers running DNS service being primarily Linux machines and the code for the DNS service had a gaping security bug that had been ignored) - fairly sure they patched it pretty quickly.",
"For those redditors that haven't watched Silicon Valley and are trying to answer OP's question, it's important that you know that there is a magic compression algorithm that the entire show is based around. In the show, the algorithm, what they call \"Middle Out Compression\" is one of the most revolutionary thing to happen in technology, basically eliminating all file sizes.",
"Imagine a phone network where *in theory* you could call any number - but if you actually tried it, 99% of people would not answer your call or yell at you or report you to the cops. Instead, you're always supposed to call one particular guy - let's say Bob - and tell him to store a message for you and pass it on to whoever you actually want to talk with. That person will also call Bob and ask if he has any messages for them, etc. On a technical level, this is the Internet right now. (It's not *one* guy yet, but the number has become surprisingly small)"
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6e9yel | When you edit an application or image with Notepad, what are the thousands of lines of random characters it shows? | Technology | explainlikeimfive | {
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"Notepad assumes that *everything* you try and open with it is a text file, even if it's not. ASCII and ANSI are two popular systems on how to encode text as zeroes 'n ones, and Notepad, no matter what, starts looking for text encoded in these manners. Usually it finds *something* that matches the rules of the encoding and tries to show what letter it thinks it found. However, it's totally wrong and barking up the wrong tree, the random characters it shows don't really mean anything. A good metaphor would be if you didn't know the symbols for the numbers, **did** know the symbols for the alphabet, and saw a 0. \"Aha,\" you think. \"That's the letter O!\" When no, it's not, it just looks like that because that's all you know. Notepad is kinda the same, it doesn't know how to make sense of JPEG or application data but it knows what letters look like, even when the data ain't letters.",
"Everything computer stores is just 0's and 1's. Text files however have really simple way of turning those digits into letters, each string of 8 binary numbers correspond to a specific letter. There is basically a giant table for those, and the connection is essentially random, some guys just decided it a long ago. Other possibility for a file, beside text file, is a binary file, which essentially just means it's not a text file. So each binary digit has some other meaning beside encoding text. For program files, it's combination of command id's and numbers, for image files it's more complicated mess of function parameters, and if you open such thing with text editor, it assumes they are all letters, and it tries to show what letters, according to the lookup table it has, those numbers would correspond with. Resulting in a random mess."
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6ea0s7 | How is the motion of fluid simulated? | Technology | explainlikeimfive | {
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"You don't simulate water molecules individually - you just don't have the computing power for that. Instead, you would model the water not as a collection of droplets but a continuum. You can then derive the Navier-Stokes equations for the motion of the fluid. However, these equations are very difficult to solve analytically (exact solutions exist only in a few very simple cases). Therefore, for a fluid simulation, you would use a numerical approximation. This involves representing the continuous fluid by a discrete approximation. There are two common ways to do this: * Eulerian schemes use a fixed grid or mesh. The fluid quantities, such as velocity and pressure, are stored at the points of this grid. The more of these points you have, the better the approximation (but you'll also need more computing power). * Lagrangian schemes store fluid properties on particles that move with the fluid. These particles shouldn't be interpreted as molecules, nor do they necessarily stand for a fixed volume of fluid (though they can do) - rather, they represent the velocity and pressure of the fluid at that specific point. Some schemes (such as FLIP) make use of both Lagrangian and Eulerian coordinates to get the best of both worlds, at the cost of using more memory. For simulation of an inviscid, incompressible fluid, two steps must be performed. **Advection** is the transport of fluid properties by the motion of the fluid itself. If you are using a Lagrangian scheme, this involves moving the particles (while the values of velocity and pressure associated with those particles remain unchanged at this step). If using a Eulerian scheme, the fluid variables at the grid points will have to be updated. Lagrangian schemes tend to cope with this step better - Eulerian simulations can suffer from greater **numerical dissipation** whereby the error in the advection step causes the fluid to appear more viscous than it should do. The advection step will in general result in a velocity field that is not incompressible. During the **projection** step, a pressure field is calculated that will make the fluid incompressible. This requires solving an equation called Poisson's equation. Poisson's equation is linear, so it is straightforward to solve - but in a large simulation there may be millions or billions of unknowns to solve for. This is the main reason why fluid simulation is so computationally intensive. Different numerical schemes take different approaches to implementing these two steps - and they all have different advantages when it comes to accuracy, speed, and memory usage. A big difficulty with fluid simulation is **turbulence** - in turbulent flow, the fluid motion is very chaotic, with both large and small scale behaviour. Although the Navier-Stokes equations are still sufficient to describe this behaviour, you may need a very fine grid (and therefore a lot of computing power) to get an accurate result. Therefore, there exist more sophisticated approaches to modelling turbulence, which isn't something I know much about.",
"Developer here, These sorts of simulations are done with vector fields. Imagine a grid in 2D or 3D where each point has an arrow. The direction of the arrow is the direction of the current, and the length of the arrow is the velocity. The grid doesn't have to be regular or uniform, but the more vectors, essentially the higher the resolution. An equation is iterated over all the vectors as inputs, the output is a new value for that vector. Another method uses cells, think Minecraft. Values and equations basically determine whether a cell is full or not. More cells means higher resolution. Water is hard. In CGI, fluids have been modeled as small spheres that can roll around and model a behavior that makes them look like water. I think they used this technique in Cars. Other methods are used in simulation and analysis, and other techniques are used in rendering. The appropriate choice, if you were to take one off the shelf, is highly contextual."
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6eak1o | Why are blackboxes not used in motor vehicles? | Wouldn't determining the last few actions of a car help determine who is at fault in an accident? | Technology | explainlikeimfive | {
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"Dash cams are becoming more and more popular. They're not expensive and they can help you out with determining fault in collisions. Black Boxes are useful on airplanes because airplane crashes aren't generally caused by running into other airplanes (or running into anything, except the ground). So it's useful to have something that is recording the gauges and controls. With cars, it's more about being able to see what is happening around the car and not necessarily the actions the driver takes (or at the very least, the dash cam can show some info like where the driver is steering). In a country like Russia where people are always trying to fake being hit by your car to commit insurance fraud, having a dash cam is practically a requirement.",
"Black boxes are nearly ubiquitous in the North American market. People are just not aware that their vehicles have black boxes. URL_0 At the moment, they don't provide enough information to conclusively prove fault in all accidents though."
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6easf3 | What is the origin of the "http://" before a website address, what is its purpose, and why is Wikipedia's "https://" a significant difference? | Technology | explainlikeimfive | {
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"Back in the early days of the internet, you had to directly connect from computer to computer, and know the computer's exact address. As the internet grew, some computers started acting as servers that you could access through various protocols. You can tell a protocol is being used because there is a :// between the protocol and whatever comes after it. One protocol is HTTP, which stands for hypertext transfer protocol. When you connect to a server such as Reddit with HTTP, your computer is saying, \"Hay, Reddit server, I'd like a webpage pls.\" Reddit replies, \"k here's your webpage thx\" and delivers the usual text/images/video/etc. that we usually expect from web pages. There are other protocols out there besides HTTP. For example, FTP, or file-transfer protocol, is used to directly download/upload files. So the owner of Reddit might decide that instead of browsing to the Reddit home page, they'll use an FTP program to access Reddit's files. Instead of seeing a pretty web page, they'll see a group of folders much like the file explorer on your home computer. And then they can manipulate those files in much the same way, such as by replacing all the site images with lolcats. So let's say you see a cool link on Reddit to the Mooby's Swag Shop website, and while on that website you see a REALLY COOL HAT! Of course, you must buy it. So you enter your credit card info, and click send. However, you fail to notice that Mooby doesn't know what he's doing and he let you send your credit card number over the HTTP protocol. This is unfortunate for you, because your next store neighbor Nosy Nancy has been watching all the information you transfer over HTTP, and as soon as she sees your credit card number she logs onto Amazon and goes on the shopping spree of her life. Whoops! What Mooby should have done is change his Swag Shop to HTTPS protocol, which stands for Hypertext Transfer Protocol Secure. With this protocol, the computer you contact gives you an encoder to scramble up your message, and it can only be decoded with the decoder kept secret on the other end (it uses a nifty mathematical trick where the encoder can encode the message, but it can't actually decode the message back without the decoder!) This way, when you type in your credit card number and hit \"send,\" your computer encrypts it up, sends it to the Swag Shop, and then the Swag Shop decodes it. If Nosy Nancy listens in, all she gets is gibberish - she does not get your credit card! It used to be the case that HTTPS was a much slower protocol than HTTP, so it was only ever used for credit cards. But nowadays the speed has caught up, and the criminals have gotten smarter. Many of the big companies have raised concerns about even your logins for websites being snagged by the Nosy Nancys of the world, since they could theoretically snag your username and password off Reddit and try it on every major bank's website (since at least some people will use the same combo for both.) So in recent years Google, Firefox, and Apple have started pushing website owners to switch any page with a login screen over to HTTPS (with an eventual role of getting the entire internet to switch to HTTPS). Also, it's important to note that there are different levels of HTTPS. If you look to the left of the HTTPS on a given web page in your browser, you'll see a lock icon. Clicking on that icon tells you what level of security it has. The most basic level of security is, \"This website is encrypted, but we have no idea if it's legit.\" The highest level of security is, \"This is a real world business that's registered in a specific country and has submitted all its paperwork to prove it's the real deal.\" For example, on this website, I can click on that icon and view the certificate to see that URL_0 is owned by a company called Reddit Inc., and has been verified to be the real Reddit by DigiCert Inc., but I can't see the real world owner of the company. On the Bank of America website, I can see that it's the real Bank of America site and that it's owned by the physical Bank of America company based out of Chicago, Illinois. Why is this important? Well, if you're on someone's blog, just being encrypted is good enough, you don't really need to trust the person who owns the blog. But if you're directly depositing all your paychecks into a bank account, you want to make sure you have a ton of trust that the website you do your banking on is actually owned by your bank, and not a scammer trying to get your bank account number. TL;DR: HTTP lets you view webpages. HTTPS lets you view webpages securely. HTTP is becoming outdated, and you can expect to see most major sites switch to HTTPS over the next couple of years.",
"\"something://\" indicates the protocol being used. The protocol is the system/rules by which your computer and the remote server that has the webpage talk to each other. There's actually many, and some other ones used to be more popular, but these days http (hypertext transfer protocol) is by far the most commonly used, and if you don't specify a protocol the computer assumes that one. (ftp:// is still in use though gopher:// has long since fallen by the wayside.) So what's http**S**? The S stands for secure. It's the same system as http, except encrypted so that as your communications pass over the internet, it's much harder for anyone to potentially snoop on you.",
"HTTP is not encrypted, so if someone was sniffing through your network as you went on an HTTP site then they would get all that information. HTTPS is encrypted, notice how whenever you login to your internet banking (chrome for example) there is a lock behind the https. Most modern sites are HTTPS due to huge security risks with data not being encrypted."
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6ecbdg | What causes audio and video tracks to fall out of 'sync' with each other during recordings? Why can't computers/devices just play them back at the same time? | It's 2017, why is it that sometimes recordings and playbacks have issues with sync still? | Technology | explainlikeimfive | {
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"The biggest cause would be using a different sample rate than standard. For example, standard frame rate for a video is 24 fps. Standard audio rate for a video is 48,000 samples per second (think of it as frame rate for audio). This way, you have exactly 2,000 samples per frame. If you use a different sample rate, like 44,100 samples per second (the standard for CD audio) you wind up with 1837.5 samples per frame. This is fine if you don't touch the video at all. If you do change the video quality while not touching the audio, or change the audio without the video, you can wind up with frames of audio not syncing to the video correctly. Things get messy when you use other frame rates, like 60fps, or 29.97 fps, etc."
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6ed4h4 | Why do animal brains tend to operate far more efficiently than even the best computers? | Brains occupy a low volume and use very little energy compared to computers. How is this possible? What's preventing computers from becoming more efficient than the brain? | Technology | explainlikeimfive | {
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"What makes you think they are less efficient? Computers are vastly more efficient than brains, at some tasks. Running a modern game requires billions of floating point calculations per second. Even if you drafted the entire population of the planet you couldn't get that kind of throughput. We win at other tasks like path finding, but not by much any more.",
"My understanding is more with the brain and less with computers, so if any computer people want to correct me by all means. Brains are super complicated. We don't now how they work (despite the progress we've made). We have plenty ideas and we now the mechanics of how a neuron fires and how some learning happens, but we have not successfully mapped out a human brain. Trying to store all the info and connections of a human brain would take up a horrendous, impractical and (i believe?) impossible amount of space on a hard drive with our current tech, and even then we wouldn't know how that brain works when it's firing (when it's alive, in other words). On top of all that, think of computers for a moment. You don't see the computer when you use it, you see the OS-- in other words, the little windows and screens and start bar and whatever. This OS is programmed and we understand it exactly, and it uses the guts of the computer and the brains and processors to do what we tell it to. For a human, what's out OS? It's basically consciousness, and we don't understand consciousness well at all from a neurological point of view. Hell, even philosophy debates it plenty. So that's also impeded us in our efforts to compare brains vs computers..",
"I think there is a bit of faulty reasoning comparing a human brain to a computer. I don't think that the human brain is preforming 4 billion mathematical operations per-second and doubt it will be capable of that any time soon but comparing the brain to the computer assumes that the human brain operates in any way like a CPU does. Even if the brain may carry out instructions in ways that seem like If-then statements or Boolean operations, its pretty unlikely that the brain is using biological logic gates to make those decisions.",
"Brains occupy a huge volume compared to silicon computers. Your brain uses the equivalent power draw of a 40 watt light bulb to function. Your laptop can use that power in an area the size of a stamp, vs a basketball. The human brain is quite big and heavy."
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6eeaq9 | How do certain apps like Facebook Messenger and Steam chat still work even though my internet service has been interrupted? | I've wondered this for a while. My internet was interrupted, but I can still use Steam chat on my computer and the Messenger app on my phone through wifi. How is that possible? | Technology | explainlikeimfive | {
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"Because your Internet wasn't interrupted. Your computer connects to a WiFi hotspot that connects to a modem of some sort that connects to a series of routers and switches inside your service provider's network that connect to other networks (i.e. the Internet). If that connection is _actually_ interrupted, i.e. you remove one of those connection points from the mix, either in your home or your service provider's network, then *no data* is going to pass between you and the people you were chatting with. What likely happened is your DNS service failed. Domain Name Service (DNS) is the service -- usually provided by your internet service provider -- that a computer uses to translate domain names (www. URL_0 ) into numeric Internet Protocol (IP) address (151.101.33.140). You enter \" URL_0 \" in your browser, the browser sends off a request to a DNS asking \"What's the IP for URL_0 ?\", the DNS responds \"151.101.33.140\" and then the browser uses that to contact the URL_0 servers to get the website. If DNS fails, then your browser won't be able to get the IP address for any website you try to navigate to by a domain name, either by clicking a link or entering the domain directly. So it won't be able to retrieve anything from the web -- it'll throw an error on ever web page. Usually it says something like \"cannot find server\" in the error message. That can make you *think* your service is interrupted. That doesn't mean your Internet service is *actually* interrupted though. The bits are still flowing through your Internet service; your computer just can't access the address book (the DNS) to know where to get them or send them. If you knew the IP yourself, you could bypass the DNS and just enter the numeric IP directly. That would work fine. But it's impossible for us stupid humans to keep track of that many numbers, so we rely on a Domain Name Service. So why would Steam Chat continue to work? Because Steam Chat (IIRC) is a peer-to-peer system. That means *once it makes a connection*, the connection is direct between your computer and your friend's computer. After the connection is made, it has no need to look up the DNS; it *already knows* the IP address of your friend's location. Since it's not looking up the IP through a DNS, and your internet service isn't *actually* interrupted, the Steam Chat client can continue to connect directly. (It would probably fail if you tried to connect to someone you'd never chatted with before.) So why would the Messenger app on your phone continue to work? I know less about how Messenger works, but a few possible reasons: 1. The Messenger app is sending and receiving messages from a central service and the app already has the IP recorded for that service. Since it's not looking up the IP through a DNS, and your internet service isn't *actually* interrupted, it can continue to send and receive messages. 2. It's using a peer-to-peer approach as well, like Steam Chat, and same thing: not using the DNS, already knows the IP, your service isn't actually interrupted = continues to work. 3. If the ISP's DNS fails, the Messages app falls back to using your mobile network instead of your ISP for messages. Your mobile network and your internet service provider don't share a DNS, so if the ISP's DNS goes down, that has no impact on your phone apps' ability to find an IP address through the mobile provider."
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6eek6a | How in the world did the NES light gun work? | Technology | explainlikeimfive | {
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"When the trigger is pressed, the entire screen turns black for one frame (~1/25th to 1/30th of a second depending on TV type), except any valid target on screen. The \"gun\" detects whether or not the part of the screen it is pointed at is dark or light, and the game gives you a hit or miss based off of that.",
"In addition to that, with many light guns, aiming the light gun at a soft white light bulb guaranteed a hit everytime because it would interpret the light as a hit.",
"The gun had a very simple light detector. When you pressed the trigger, for a fraction of a second, your screen became all black except for your hitbox who became white. So in effect your gun was just detecting if it was aligned with a black part of the screen or a white part.",
"[Here's a video of Roo from Clan Of The Gray Wolf explaining it.]( URL_0 )"
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6eenbu | Why did so few Genesis/SNES games allow you to save your game progress? | Technology | explainlikeimfive | {
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"Because these older game consoles had no built-in place to save games onto. The consoles only had a minimal ROM and no permanent storage to save anything on to and no good way to connect any to it.. Usually the problem was solved either via not allowing save progress at all and instead having a list of passwords that you unlock for each level or savepoint. This was the older way in previous generations of games. The other method that became much more common in that era was to put the the savedata into the cartridges themselves instead of the consoles. This mean you could take your Super Nintendo game cartridge and take it to a friend's console and have the same data. It also meant that the cartridge was a bit more expensive because it needed more hardware. Finally there is the problem that the battery that allowed the data to persist when the power was turned of eventually stopped working at which point you lost all your saves.",
"Sega genesis carts had the save memory on an extra chip on the cart. This cost money. Leaving it out means it's cheaper.",
"They needed a battery in the cartridge back then to save games, which made the games more expensive to make, so it wasn't as widespread. Also bear in mind that these were the first generation of consoles to have a real save feature, so it wasn't as demanded back then."
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6eey0t | What is R? | All I know is that R is a data analysis tool, though I'm interested to know what it actually is and what it's used for. Thanks | Technology | explainlikeimfive | {
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"R is a programming language geared toward data analysis. It's a free, open source alternative to SAS, which is itself a closed, proprietary steaming pile of shit from the 50s or 60s that had language feature after language feature hacked on, making the syntax so complicated you end up calling SAS Institute to write the code for you. It's used primarily for statistics and data analysis, and has a seemingly endless number of extensions to facilitate different types of analysis, parallel, concurrent, and distributed computation of big datasets, and visualizations. My wife uses it in her job in marketing, but it can also be used to analyze insurance, engineering, simulation, finances, and trading. For example, my wife used it to perform a cluster analysis for a matched market test, to identify markets that are similar enough so they could have a test group and a control group.",
"I'm a PhD student, and I use R a lot. It's basically a programming language, but geared towards statistical analysis. Being open source and widely used, you can install a wide range of packages which greatly expand the functionality. A very simple use of R would be to import some experimental data, carry out a statistical test to see if there is a significant effect, and produce a plot of the results. But as per the above, you can do all sorts of other things - analysis of images, sounds, spatial data, statistical modelling, data mining..."
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6efyd8 | Why we don't have a computer processor that's can exceed 5GHz without overclocking? | Technology | explainlikeimfive | {
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"Short answer: because we can't make processors small enough. Signals travel at close to the speed of light through the processor. The speed of light is 300,000 km / sec. In a 3 GHz processor, the electrical signal has only 1/3 of a billionth of a second to flow through the processor before the next clock tick. That translates to a distance of about 10 centimeters. In a 5 GHz processor, it has only 6 centimeters. For the same complexity, the processor would need to be 40% smaller. This is a dramatically oversimplified answer. It *is* possible to make a processor run at 5 GHz, but there would be so many other compromises that with today's technology it wouldn't be worth it. However, we've had more luck making processors run at 2 - 3 GHz and do more work each clock cycle, so that's what we do."
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6egww2 | How come games like The Sims are billed as too complex for console if modern consoles are so powerful? | I'm aware there have been prior console games for The Sims franchise (that were heavily stripped down) and I'm aware there are games produced for the Playstation that are (kinda) *like* some console games (World of Warcraft and The Elder Scrolls are often compared when I bring this up) and that there are games that are just played better on console for speed (like Starcraft). I'm obviously a Simmer and recently I've been wondering why the plans for converting *The Sims 4* into a console game are basically just rumors and the speculative answers to the question of '*why not console*' varies from the game not being received well enough to the game being 'too complicated' to convert to console. Except, they just announced an app (that I imagine is also super dumbed down). Is there any actual merit to the consoles not being able to run a game as in-depth as the PC versions due to the game itself? Or can consoles legitimately not handle certain types of games? Thanks! | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"\"Too complex\" doesn't mean that the console can't handle the calculations. Obviously, modern consoles are way more powerful than the PCs that ran the original Sims game. It's a matter of interface- some games, like platformers, work really well with a controller. Others, like First Person Shooters, are more accurate with keyboard+mouse but can be played with a controller as well. Games that have a lot of interface elements- a lot of buttons to click and sliders to move and so on- work much better with a mouse than they do with a controller because you have more precise control over your movements and presses.",
"Pretty sure it's them just being lazy. They ported Sims 3 to console and it worked marginally well. Random freezing, they didn't bother to patch..",
"I'm not sure that it's a technical issue that these people are talking about. It's generally an input concern. The mouse is easily replicated in a touch interface but has had troubles moving to the console. Yes you could move a joy stick, but either it's too slow or not sensitive enough. Generally to compensate for this consoles have 'cycled' through options instead of giving you the ability to select out of order. In the PC Sims you can jump from Bob, to Jane, to Bob to Billy. In the console version you'd have do Bob to Jane, through Billy then Bob then through Jane and then Billy. That's just a family of 3! Imagine a whole house. The newer Sims have way to many options and inputs that just don't transfer to a controller well."
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6ejgd4 | How is the White House over 200 years old but still able to keep up with modern security standards? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It has been updated and renovated on several occasions since it was last burnt by the British."
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6ejqrq | How do the pressure sensitive alkaline battery meters work? | How do the non-rechargeable batteries that have a '[powercheck]( URL_0 )' function work? Why does squeezing it show the charge level? Any reason they seemingly appeared in the early 2000's, disappeared, and then came back recently? | Technology | explainlikeimfive | {
"a_id": [
"diattve"
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"text": [
"From my understanding, pressing the points completes a circuit with a resistive load, generating heat. The indicator changes color in response to heat, and the amount of heat generated is related to the voltage of the circuit."
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6el6vc | With thousands of workers producing new iPhones, how come not way more information about them is leaked? | And how do these huge factories prevent espionage? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"They guy who oversees the shoe sole making machine does not necessarily understand how the rest of the shoe is made. There are not a whole lot who actually understand the whole thing, and those who do are probably under a close eye and NDAs.",
"They're scared of losing their job and will probably face harsh prison terms if caught. Most are poor and illiterate workers... So their livelihood is on the line. There's always leaks after the product is finalized and ready to go."
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6elwg5 | Ethiopia has blocked mobile internet within the country. How are they able to block mobile internet specifically? | Is it by demanding the satellite owners stop providing access within the country? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"By forcing all cellular providers to block their internet. Cellphones don't connect to their network through a satellite, they connect to a nearby cell tower which is connected to their service provider's network. The service provider's simply needs to block data communications, just like they can do if someone chose to disable their data plan.",
"Mobile internet is not satellite internet. Mobile internet is handled via cellphone towers which then connect you to a physical connection that is run to said tower. It is a process similar to how your home WiFi router works but on a larger scale. The country simply requires the cell phone companies to not allow said connections to be installed or to be turned on."
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6en1ku | How do Naval submarines stay in contact with the mainland? | I know that regular frequency waves have an extremely hard time penetrating water, and I know that the lower the frequency is, the less feasible it is to submerge the entire transmitter. So how do submarines stay in contact with the surface? Say if a nuclear strike was ordered? | Technology | explainlikeimfive | {
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"text": [
"Your intuition that low-frequency radio waves are the only means of transmitting through water of any significant depth is correct, as is your intuition that the antennae required to transmit such radio waves are too large to mount on submarines. But you're missing something pretty significant: the antennae required to *receive* these radio waves is no bigger than any other receiver. This means that submarines can still *receive* VLF radio transmissions (circumstances permitting) even if they can't transmit them. Of course, the fact that we're talking about VLF means that the bandwidth is so low that only text communication is practical. There's not enough bandwidth to broadcast real-time audio signals, let alone video. We're talking 300bps. A high-end consumer-grade broadband connection can be upwards of 300**M**bps, literally a *million* times faster. That said, VLF radio waves only penetrate to depths of perhaps sixty-odd feet, so a submarine at its normal patrol depth would not be able to receive transmissions without ascending. Sometimes this is what happens, but for subs that stay at depth for months at a time, this is clearly not an option. One solution is radio buoys, tethered to the sub and floated to transmission depth while the sub itself remains far below. But the long and short of it is that a sub at patrol depth will probably be out of contact with the mainland most of the time. For what it's worth, most *two*-way communications with subs is via the same satellite communications network used by other naval vessels. This does require subs to surface, or at least ascend to a depth shallow enough to permit the exposure of an aerial/mast, but it's pretty much the only effective means for submarines to *send* messages, not just receive them. There are also rumors of acoustic communications systems maintained by the US and Russia. These would involve acoustic sensors/transmitters being set up at specific points on the ocean floor that nearby submarines could use to send and receive messages that way. The existence of acoustic communications networks has not been definitively confirmed, but even if they did exist, they would be of very limited utility. These would presumably be encrypted so as to avoid interception, but that's not the only problem. The mere *fact* of a transmission would tend to indicate a nearby sub, and even that much of a hint is something most sub captains try to avoid at all cost.",
"Certain submarines that are required to patrol deep use a buoy or a long positively buoyant antenna that comes out of the ship and ascends to the surface. This allows for 'passive' or recieve only communications. If the ship wishes to transmit communications, they are required to go to periscope depth (just below the surface) and raise a mast with an antenna that transmits to a satellite/shore based communication site."
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6enlh1 | Why when a new CPU is showing, the companies insanely overclocks it to show performance? | I recently saw a new about the Intel i9-7900X and they used nitrogen liquid to overclock at ~ 5 GHz to beat RYZEN Cinebench score. I mean, how many customers would do that? | Technology | explainlikeimfive | {
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"The same reason why car companies advertise very fast 0-60 mph times or have a speedometer that can go to very high speeds. Even though most people will never accelerate or speed that fast, the possibility of that car being able to do it adds to its worth.",
"Very few [if any], and usually the enthusiasts who perform these tests are not affiliated with Intel, although may be sponsored. LN2 cooling is extremely unpractical, but is a very effective way of cooling a CPU. These tests are generally a \"let see how far we can push this thing before it crashes\" test, rather than \"how much can we realistically expect out of this thing\"."
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6eno5f | Why there are so many viruses for Windows but not for Linux or Unix? | Maybe I'm wrong, but I often heard statements like you are quite safe using Linux or Unix systems regarding to the thread of catching a virus. Is this true? And if yes, why is this so? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Software developer here, OP, so far, the answers here are terrible. People think only in terms of Windows and Linux *desktops*, which, while it's true that Linux is still not a very popular desktop, is a very '90s way of thinking about things. Apple's desktop and phone OS'es? All Unix. And truth be told, Linux, a type of Unix, is the most widely installed OS in the world. Ever hear of Android? Linux. And smart phones today are now mobile computing platforms full of concentrated, very valuable data. The majority of all computers on the internet are different Unixes. There is HUGE incentive to write malicious software for Unixes. Windows is actually the minority OS in the world, they only have the lion's share of the desktop market, and that's not that important anymore, relatively speaking. There are a number of reason viruses on these platforms are rarer. By the nature of their architecture, the trick is the malicious software needs privileges to even run on the system, and then it needs privileges to access the the parts of a system it wants to exploit, and then it has to exploit that in an attempt to gain higher privileges, so that it might actually be able to do something. Windows, by contrast, is still a very open environment that lets do things they want with little restriction. Privileges have been an afterthought, and so you have to opt into locking down the system, instead of opting in to open it up. And one thing Windows does get credit for is maintaining backwards compatibility with software like few other companies and platforms. You see this kind of shit only in mainframe computing. And on that note, Windows stays rather free and open with too many features and services running and exploits as a backwards compatibility feature so that older software can work. It's the perfect place for viruses. As for the Android and iPhone, while they expose themselves to the dangers of the internet, WiFi and Bluetooth, and by physically connecting to other computers, they are pretty much controlled platforms. You can't just go and download an app and install it yourself in a way that doesn't go through an app store. This makes it hard to get a junk copy of something on a system since there is at least some screening process before your product is offered. As for the Unix and open source communities, Unix is old, and has many meanings, which is to say there is a lot of diversity. Even among Linux, they have hundreds of \"distros\". It's hard to write a virus for all of them because they're all different enough to be incompatible. Even if the Unix world were more uniform, different versions of software proliferate. The version a virus is exploiting might not be widely installed. And the community (I'm not talking phones, though) rarely, if ever, installs software binary blobs, as is so popular in the Windows world. You don't know what you're getting. Instead, they'll download the source code and build the program themselves. It's hard to sneak malicious code past the open source community."
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6epw9w | How did media control symbols become standard (play, pause, fast forward, etc.)? Do other parts of the world use different symbols? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"URL_0 There is actually an international standard for all forms of icons. I'm going off of personal knowledge here, so correct me if I'm wrong, but during the 80s when electronics started to become more widespread globally and production switched from the west to the east, many of the manufacturers understood they would need a standardized way of denoting controls on electronics. They held a convention to draft up a list of virtually any kind of control one would need as a symbol that could be understood. There like a huge book of hundreds of symbols. TL;DR the symbols we used are arbitrary and standardized internationally. EDIT:removed the extra \"d\".",
"They come from audio tape players. Audio tape used to be on a supply reel on the left, with a take-up reel on the right. So, to play it, the tape moved from left to right, in the direction of the arrow. Fast forward and fast rewind are just two arrows showing \"double speed\" and which direction the tape moves in. Pause probably comes from a similar background: In order to keep the tape moving smoothly and precisely, there is a device called a pinch roller. The tape is pinched between a rubber roller and a vertical metal spindle called a capstan. On bi-directional tape players, there is a capstan/pinch roller on either side of the play head. When the pause button is pressed, the tape remains pinched between the pinch rollers and the capstans. The pause button is reminiscent of the two capstans holding the tape in place. On many decks, you couldn't fast-forward or rewind from pause because the tape was held in place by the pinch rollers. You had to disengage them to allow the tape to move. That's why the Stop button doesn't have the capstan images."
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6epyng | How do sites such as URL_0 find your heritage? | Technology | explainlikeimfive | {
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"text": [
"Typically they use the information you give them on your family and compare it to the public records they have available to them (e.g. birth certificates, death certificates, census records, military records) and follow that as far as they can."
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6eqnr7 | When I'm driving through a tunnel (specifically underwater) I lose radio reception but I still have cell reception (i.e. Streaming music)? | Technology | explainlikeimfive | {
"a_id": [
"dic9orp",
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"text": [
"This can happen when cellular access points have been added to the tunnel. The tunnel still shields out external signals, but it has interior signals all of its own.",
"Probably a 30 second or more buffer. My son has come out of his room complaining the internet is out but I'll keep watching Netflix on my roku for another 5 minutes."
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6eqxb4 | When electronics, such as smartphones, preform multiple tasks at once, or for an extended period of time, what makes the device hot? | Technology | explainlikeimfive | {
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"text": [
"Any time an electric current passes through a conductor, a little bit of heat is generated. If an electronic device is hard at work, you have lots and lots and lots of tiny currents passing through lots and lots and lots of tiny conductors. Together those tiny amounts of heat add up to a substantial amount I really. This isn't limited to handheld electronics. For one or two decades computer hobbyists have had fun trying to push their computer hardware to work faster than what it was designed to do. This practice is called \"overclocking\" and one of the key challenges is controlling the heat that gets generated to prevent the circuits from getting damaged. This means overclocked computers will have very intricate cooling systems. Some even use liquid (contained in pipes and tubes) to cool the circuits!"
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6et6kn | Hacking, and what the process actually would look like | Whenever I envision hacking I just see someone at their computer mashing away at the keyboard, but what actually IS hacking? How does one do it? What does one use? | Technology | explainlikeimfive | {
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"Hacking, fundamentally, is to force a system to operate outside of its intended parameters. Even if the term is most widely used for breaking into someone else's computer system, using the term in non-malicious and benign situations is perfectly valid. When talking about computer security, using the term \"hacking\" as described above, can be seen as forcing a system that's intended to be secure to behave outside of intended parameters as well. That would mean it's no longer a secure system. The system has been compromised. To \"hack\" a computer system involves (among other things) writing code that specifically targets vulnerabilities in the system's software or hardware. By exposing a system to a situation it isn't capable of handling, you can cause the system to partially break down and start doing things it shouldn't be doing. \"All\" software is designed to handle a lot of unintended situations. A program that adds together two numbers and stores the result in a space that can only hold 3 digits might have code that makes it double-check that the result isn't 4 or more digits before it tries to write it, for example. If it gets a result that ends up bigger than 3 digits, it'll stop before doing something illegal. When a hacker tries to attack a system, they try to find the errors that a program *doesn't* know how to handle properly, and then cause it to perform an action that causes this error. Then they attempt to cause this error to change things in the system that allow for even greater changes, hopefully a change that would allow them to gain full control of the system. When a \"patch\" comes out for a program, this may be the creator of the program changing the problem that the hacker found. After the patch is applied, the hacker now needs to look for a different weakness in the program, which the creator of the program again will have to fix with a new patch. As you can see, this is basically an arms race. More and more sophisticated attacks being launched at more and more robust software. As for what's used, sometimes, it's analyzing traffic coming in and out of a system, looking for patterns or anomalities. Other times, it can be going through a program's source code, attemting to find portions of code that would be vulnerable. The \"hacks\" themselves are often performed with an array of viruses, malware, etc. that is sent to a system. These are written with text editors that are optimized for coding or with software engineering tools similar or the same as what \"nice\" coders use. Then there is also social engineering, which is isn't as much hacking a computer system, as it is to trick the users of it. If you can fool a user into giving you their password, you don't need to attack their system directly with malware or viruses. This is what often is the case when someone on social media says they've \"been hacked\". Usually, they've been lead to believe they were using the real website of a service when they entered their login information, while they in reality were not. Once they've done this, criminals can often figure out the username and passwords for other sites this person uses, because a *lot* of users reuse passwords across sites and apps. Social engineering is often used in conjunction with more technical attacks. If you can trick an employee into giving you their login info, you can use this to plant malware that wouldn't have been able to penetrate a company's network from the outside. However, if the malware was planted *inside* the company's network instead, by a compromised employee's account, it could work.",
"Hello u/PM_ME_YAOI_ it seems that your reddit subscription expired. Please login again by typing your password as a reply to this comment. You would be surprised how much of hacking looks like this. Then they can also trick user to run program with malware on his computer. I.e. Click here to install this awesome emoji pack. And then there is brute force attacking. Loads of servers try one character combination after another trying to login to a system until one of them works.",
"If you're got ~45 minutes - I'd highly recommend this DefCon talk: URL_0 DefCon is a hacker convention (most of them work for security firms and are trying to improve security, and to do so, have to find the vulnerabilities). This specific talk, the speaker is trying to find a way to highjack the control of a hobbiest drone from his annoying neighbor-kid who keeps bothering him with his drone. It includes stealing control of the drone from the person holding the remote, interfering with it's control systems, GPS, etc.",
"Let's say you have a system that manages user accounts, one feature of this system is changing user passwords.. As a user, I simply say \"My name is xxxx and I want to change my password to xxxxx\", the system will then perform this action for you. Now, a hacker would see this is a window to exploit the system, and could try \"My name is yyyyy (a different user) and I want to change my password to xxxxx\", if the system doesn't validate the request from the user and notice that the user is actually changing someone else's password then there is a problem with said system. A hacker is someone proficient at finding these exploits, hacking is actually using exploits to make a system do things that it was not originally intended to do."
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6etgh3 | How much more secure does a password become by requiring it to include both capital and lowercase letters, numerical characters and letters, etc.? | Technology | explainlikeimfive | {
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"Length beats complexity. If the password does not contain any words from a dictionary and someone tries to brute force it (try every option), then there are p^n options for a password of length n with p options per letter. If your password is 8 lowercase letters long, there are 26^8 = 208,827,064,576 options. An attacker doesn't know you only use lowercase letters, but they can check these 209 billion options if they have an interest in your account. If you add uppercase letters (26), digits (10) and maybe 20 special characters as options, you get 82^8 = 2,044,140,858,654,976 options, a factor 10000 more. Alternatively, you could make your password longer: 11 lowercase letters give 3,670,344,486,987,776 options, 50% more than the shorter more complex password. The numbers above assume that you have absolutely no pattern in your password, and choose every symbol randomly. People don't do that. Replacing the \"o\" in \"password\" by a zero, capitalizing P and adding a special character to make \"Passw0rd!\" doesn't make your password strong. It is an incredibly weak password because attackers know about these obvious substitutions. They will try all the slight variations of \"password\" very early on. Password rules like \"it has to have all these things\" lead to people doing things like that. It doesn't really improve the security of passwords notably. Longer passwords are much better. A famous example is xkcd's [correcthorsebatterystaple]( URL_0 ) - just lowercase letters, but much more secure than everything like \"Passw0rd!\". There are also ways to get the password that do not depend on how complex the password is. And some attackers are just interested in getting as many accounts as possible with minimal effort - they will try \"123456\" and similar for all accounts to get all the easy accounts, and don't bother checking billions of options for each account.",
"The requirements for special characters and upper/lowercase and numbers is done mainly to steer people away from using simple, single word passwords. By increasing the total pool of possible symbols, you increase the number of different passwords an attacker would have to go through, and (ideally) reduce the number of people who have easily guessable passwords. Different password requirements on different sites also means it's harder for people to use the exact same password over multiple sites, although of course not impossible. The downsides are, of course, that people are less likely to remember their passwords, and therefore have to write them down. This can be a problem if you do it at work, where strangers might catch a glimpse of it, and where people might be specifically interested in attacking your particular computer network, but it's generally not as big a problem for home users. The odds of a hacker from halfway across the globe getting on a plane to break into your house and snatch your password notes are miniscule. Often times, if the password rules allow for it, using several random but easily memorizable words can give you stronger passwords than short passwords with lots of random characters. This of course still demands that the words you pick are actually not predictable, and that the total length of the password gets very long compared to the shorter \"typical\" passwords of 8-10 characters."
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6euu3w | How can steam have big sales so often and still stay profitable? | I.E. X game that usually sells for $60 is almost always cut to $30 when a sale comes around. | Technology | explainlikeimfive | {
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"Random of guy passing through I have no real explanation but I would imagine the fact that they don't have to pay for actual stores, inventory, employees, and basically everything else that say GameStop would have to, they save more than enough money to stay profitable. The cost of having all those games keeping a store moving inventory and much more can be very expensive.",
"Once a game is created, what' the marginal cost to sell another copy? A few pennies to cover the bandwidth for download... so to have a sale and boost sales means it's a wash. And the sense of urgency probably causes people to \"stock up\" and buy more titles than they would otherwise because they don't want to miss out on the deal.",
"Well a few things for one steam just takes a cut of each purchase made on their platform. They make a ton of money and really have no worries on the other hand the game companies (developers / publishers) do have to worry. Next thing to know if there is a sale they get approval from the game companies to do the sales they don't just get to randomly decide to sell a game for half off. The last thing is that most games sell the most they ever will in the first two weeks and every week after there is a steep steep fall off of course there are some exceptions for super popular games but the vast majority only have a small window in most cases to make the bulk of their money aka profit. So after those two weeks for most games sales stagnate and a good way to boost sales back up well is a sale. This will temporarily boost sales back up and bring in some more money. Of course it's not the same as when a game launches but it's still more than they could have hoped to make on an older game otherwise. Steam essentially realized this and created a big event where a ton of sales would on sale all at once and no surprise it became mega popular which makes even more game makers want to participate because of how popular steam is (popularity of platform = more sales). Also steam generally only does two major sales a year (summer / winter) so there's plenty of non sale time in the year."
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6ev588 | How do lights with two separate switches work? | I understand how a single light switch works: there's a circuit, and the position of the switch determines if the circuit is open or closed. When it's closed the light turns on. I'm asking about a setup like the one in my apartment: the kitchen light can be turned on as you come in the door or from a panel by the bedroom. Even if switch A is in the on position (pointing up), using switch B will shut the light off, and if I then "turn off" switch A (pointing down), the light will turn on. | Technology | explainlikeimfive | {
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"The configuration is known as “multiway switching”. Here’s a diagram from [wikipedia]( URL_1 ): [Diagram]( URL_0 ) Red “mains” is power. Notice that changing the position of either switch moves from an “on” state to an “off” state.",
"Same basic idea, but you have two pathways. Throwing a switch connects one pathway, and disconnects the other. If both switches have the same pathway on, the circuit is complete and the light is on. If they are opposed, the circuit is broken, and the light is off. A-A = on A-B = off B-A = off B-B = on"
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6evce9 | Why are headphone jacks being phased out of cell phones? | Technology | explainlikeimfive | {
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"The debate is that it takes up valuable space in the phone when the same function could be performed by a more universal port such as USB-C or through Bluetooth wireless communication. It is also a type of port which is difficult to adequately make water resistant which is another focus of recent phone development.",
"Several reasons. For what they do they're huge. They're basically impossible to make waterproof. You can tie your users even more tightly into your eco-system (e.g. a Brand X phone user won't switch brands, because then all their Brand X accessories will become useless).",
"Headphone jacks are not as profitable as separate pairs of Bluetooth headphones. It's all about money.",
"Allows easier water-proofing and can add larger battery etc. To be frank, it is a good thing to do. USB C port will replace the audio jack and can act as a better audio interface. If you use a USB C port based headset, it will be able to make use of audio software enhancements like bass boosting etc that you will find with the current USB A type based \"gaming\" headsets."
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6eviqh | The PageRank algorithm | I'm currently studying Computer Science at A-level and I am struggling to understand how the PageRank algorithm works, the formula looks pretty complicated and I was hoping someone could break it down for me in simple terms. | Technology | explainlikeimfive | {
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"The simple version is this. You want to know if a page is popular. To determine if it's popular you start with the basic idea that \"a page is popular if popular pages think it's popular\". To solve this you need two things, \"how do you know a page is popular\" and \"how do you know that one page thinks another page is popular\". The second one is pretty straight forward. If you link to a page you are effectively endorsing the content. So use that for your \"thinks that page is popular\" indicator. Now for the first one, what we can do is start with the idea that every page is equally popular. So let's give them all a score of 1. Now for every page take that score and divide it by the number of pages it points to, and give each of those pages an equal share of that score. Once you've done this you basically have a list of which pages or popular by simple number of links to the content. But that's not what we said we were trying to do, we don't want the pages that most pages point to, we want pages that *popular* pages point to. Well if you take the score from round one and you apply the logic again, now the more popular pages from round one have a higher score, and therefore their opinion matters more. Keep iterating like this and over time the scores will reach an equilibrium, and now the pages with the higher score are considered the most popular."
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6exotw | Why did camouflage take so long to catch on in the military? | I mean it just seems so logical now. | Technology | explainlikeimfive | {
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"For a very long time it wasn't particularly logical. Until about the mid 1800s camouflaging individual soldiers wasn't just pointless, it was actually counter-productive. It was important that soldiers be highly visible. It wasn't until accurate repeating rifles made their battlefield debut in the late 19th century that the common infantryman needed to hide. Prior to that of course camouflage was employed to stage deceptions and ambushes and to conceal your forces before they engaged. Once the shooting started though it was best if everyone was easy to see."
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6f0yp6 | Why are bar codes relatively large when usually you only need one thin scan line to identify an item? | Technology | explainlikeimfive | {
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"text": [
"You May have expierienced how long it takes from time to time for the employees to find the Barcode, now imagine its only half a cm thick."
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6f14iu | What is HDD or SSD cache, and why does it make the storage device faster? | Technology | explainlikeimfive | {
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"Caching is the concept of using a smaller faster storage medium to store the most accessed data so it is faster. For example when you access something on your hard drive the operating system will store that data in the main memory. But when you are done with it the operating system will not delete it from memory and the next time you access the same data it will just instantly give you access to the data in memory. However when you write data it can not use the main memory as it gets wiped when the power goes out so the changes would be lost. For a long time you could get RAID cards with built in memory and battery to work as write cache. However with big cheap SSDs it is more economical to use an SSD for both write and read cache. This also means that you can cache things even if the main memory is filled. It should be noted that cache does not improve throughput that much. The data still needs to be read and written to the main disks. So it will only help on throughput for often accessed data like program files and does not help throughput for file transfers and similar operations. The main focus is latency. But even with latency there are limitations. For read the cache will not improve latency for data that is not in the cache, it may even hurt latency a bit. And for write it can only improve latency until you have filled the cache at which point it reverts back to the latency of your main hard drives. So the performance improvements of a cache will depend on your workload.",
"Imagine you run a library, you have a service counter where an employee takes requests. The employee gets a request for \"The Davinci Code\", he checks the location on the computer then runs down the aisles to fetch a copy of the book. After a few days he realises that 60% of requests are for the Davinci code so on his next trip he grabs up 50 copies and keeps them next to the counter. In doing this he has a 'cache' of the most popular book so for 60% of the requests he can just hand the book straight over, this speeds up the overall operation of the library significantly."
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6f197t | the second half of TLS/SSL | I get that it uses asymmetrical encryption - so when I connect to a site's server it gives me a public key - I encrypt my data in a one way function (e.g. I encrypt with the public key my whole payload and it can only be decrypted with the site's private key.) Makes sense - the data going to the site's server is encrypted. Now how about the response? How can the server send me back data over the theoretically open internet that only I can decrypt? Does my browser send over a public key to encrypt the response that only my browser has the private key for? How's that response from the server work? | Technology | explainlikeimfive | {
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"The public key isn't used to encrypt the data, it's only used for key exchange - the client uses this key to encrypt and send information that will be used by both parties to generate a shared key, just for this session. This key is then used for a symmetrical encryption such as AES."
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6f1om9 | What does Big Data really do with our data? | I want honest, true answers please. No fear-mongering or anti-corporate propaganda. | Technology | explainlikeimfive | {
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"\"Big Data\" isn't an entity so it does nothing with our data. \"Big Data\" refers to the concept of using large amounts of data to draw conclusions or direct action. Some company might collect \"Big Data\" about their customers and then try to draw conclusions about their customer base, such as what products to carry or advertise. Similarly selling that data to other companies would be profitable, and buying such data could in turn help grow a business.",
"Big Data isn't an entity. It's just the phrase used to refer to the existence of comprehensive collections of data, most of it taken from public record or purchased legally from companies you've allowed to have the info. Data brokers develop lists which incorporate info from many sources to create profiles of individuals, so they can sell the names and addresses back to companies that want to reach, say, married women with no kids and a house worth > $100K (or whatever). Basically, this is all about selling you more stuff, more efficiently. It's not a plot. There is another use of the word, which involves reporters synthesizing huge public databases to investigate whether public agencies and politicians are working for the public or for themselves.",
"They mostly use it to figure out what kind of person you are so they can advertise best to. If they know you are a parent and know your income and know the age of your kids, then they will make sure you are getting an ad for the brand new toy for your kid's age. Target did an interesting thing regarding that. There are certain items that newly pregnant women will buy. So if you buy those things, you'd get a special advertisement in the mail with a bunch of prenatal items. They [got in trouble]( URL_0 ) a few years ago for it. What they do now is they'll send an ad with a bunch of sale prices for random things with a bunch of pregnancy stuff thrown in there so it doesn't look so creepy.",
"So think of a company like Amazon. When you buy something on the site you don't just buy the first thing you see. You search, filter, read reviews, descriptions, change searches and so on. Well each of those is an event which amazon collects. Then they analyze this data. Now for 1 person it's simple. But when you get into the thousands/millions/billions of events like this occurring this get more complicated. Big data is just the process of storing, processing, and analyzing that data to help you make business decisions. Because if a person bought a washer than they probably need a drier."
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6f1zic | Why are credit/debit cards not coded with the card type? | Frequently when I purchase something with my credit card, the machine asks whether I'm using a credit or debit card. I've even chosen the wrong one before out of curiosity and the transaction went through just fine, and showed up normally on my statement later. So if it's going to work regardless of which button you press, is there a reason this information is necessary in the first place? And is there a reason the card type isn't just encoded on the magnetic strip or chip? | Technology | explainlikeimfive | {
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"It seems you misunderstood. It's not that the terminal is stupid, it's because the terminal is smart. The reason some payment terminals ask you the type is because your card is of both. It has credit side which means your bank pays for you and then sends you a bill later, and debit side which is attached to an account with your own money and no one bills you for that transaction later. The system is merely giving you the choice to select which part you want. This is quite typical in Europe.",
"The system by which debit and credit transactions are processed are different, both historically and today. Most cards nowadays are able to work with either one (i.e. debit cards can be run as credit too). It's giving you the choice because your card supports both, not because it can't tell which one you have. As you pointed out it usually doesn't matter, but I know of plenty of local shops that have a minimum for using one method, or a flat rate added to the other method, etc. There are times when you'd want to explicitly use one or the other.",
"A lot of great answers, but I'll try my hand and ELI5: When you use a card for a transaction, the modern process works kind of like a car going to a set destination. For example, you may be able to take back roads or a highway; both will get you to the same place, but in a different manner. In your card's case, you could say the \"back roads\" are a PIN debit network (common ones are Cirrus, Pulse, Star, etc.). While the highway could be a credit card network (MasterCard, Visa, and by proxy the various processors that process the transaction such as First Data, FIS, or Fiserv). So, why two paths? Well that's complicated, but the ELI5 reason is money, called interchange. The various networks work kind of like tolls; the back roads may charge 1.25, while the highway costs 2.50. these fees are paid by the merchants to the networks and ultimately back to the Financial Institutions as income for offering you a card and a convenient checkout option. This is often why merchants may have a minimum charge; if you buy something for 50 cents, and the minimum interchange is one dollar, then the merchant actually loses money (note, these values are just hypothetical examples, interchange rates vary widely by network and category).",
"Its asking you whether to process through the ACH system or the credit card system. ACH does checks too and pulls directly from your bank account. Credit only does credit accounts so it uses Visa/Mastercard/etc, one of those backs your debit or you wouldn't be able to run it as \"credit\". ACH is much looser and has fewer protections in addition to making you input the pin. I strongly prefer credit but my card likes to default to ACH because its cheaper for the merchant. I've had a \"debit\" only card before and it would fail if you tried to use it as a \"credit\" card. On many terminals nothing stopped me from trying it as EBT (foot stamps) or a gift card. Obviously those transactions did not go through. Its kind of like a website asking you to log in with facebook, google, or a local account. ACH = URL_0"
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6f25lz | how does a Chromecast work | When I cast a show from Hulu or Netflix how does the Chromecast still play after on my TV while my phone is off the wifi network? | Technology | explainlikeimfive | {
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"Your phone tells your Chromecast over WiFi what to play. It also tells your Chromecast what volume to play, to play/pause, and to skip if you request it to. Since it basically just tells your Chromecast what to play, if your phone goes off WiFi it won't stop playing since it's not streaming directly from your phone. I think.",
"Your phone is just a remote. Everything is done on the chromecast. All that happens is your phone sends a short url (link) to the chromecast, the chromecast loads it. Nothing more. Your phone isn't needed in the process for stuff to continue playing or anything. It's just like if you press channel up on a remote, the TV goes to a new channel, your remote doesn't need to be involved in keeping the TV running."
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6f2rgd | How do railroads work? Are they just like freeways for trains? Could I buy a train and drive it anywhere I want? | Technology | explainlikeimfive | {
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"Nope. Either you own the tracks, or you negotiate the right to use it with the owner (\"trackage rights.\") Most railroads in the U.S. are privately owned by companies like Norfolk Southern or Union Pacific. Amtrak is a peculiar case: It's a for-profit corporation, but partially government funded. Outside of the Boston-Washington corridor, it mostly uses privately-owned tracks from other companies, meaning Amtrak trains often have to wait for more-profitable freight trains. In many countries, the rail network is fully government-owned, like the SNCF in France. I don't know the exact legal framework, but I'm confident they don't allow people to use them without asking.",
"Railroads in the united states are all privately owned. Engines and railcars are all owned by the railroad companies. You can rent whatever to use, but you still must follow the rules of the company who owns the track. There are very specific rules for when, how and weight limits for and given length of track. Only one train can use a track at a time for example. You will see colored lights every so often signaling the conductor much like a traffic light would for a car. Check with your local railroad for more specifics. I know for most of the railroads, you need an engineers license to drive an engine.",
"In America, the railways own the track and a certain distance on either side (for instance 15' from center of track). So no, you would have to sell the idea to the owner of track before using it. Fun fact, there's a contracted lease for every single power line and road crossing that exists."
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6f31uh | Since I assume hacking/DDoS attacks are illegal, how have groups such as Anonymous and Our mine not been discovered and arrested? | Technology | explainlikeimfive | {
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"text": [
"It helps that Anonymous isn't a group. It's just a name that some hackers and a lot of neckbeards operate under whenever they're doing things. Individuals definitely get arrested but you can't arrest everyone who calls themselves Anonymous, only the ones who do something illegal and get caught.",
"first of all, the assumption is that the person is within the jurisdiction of the law enforcement agency. in the modern age, a person from any country can connect to any computing device in any part of the world. the FBI can't enforce US laws against a person sitting in Moscow. secondly, a good attacker doesn't leave traces for you to follow. the attack doesn't come from his computer in front of him. he attacks using computers he infected from all over the world. none of the attacking machines is actually tied to him."
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6f345b | How do people remove vocals from a song for adverts for example? | Technology | explainlikeimfive | {
"a_id": [
"dif0ewi",
"difax5k"
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"text": [
"Most songs nowadays are composed using layers on a track. So all it really takes is removing the layer. It's trickier with older songs that didn't use this production method.",
"Little late to the party but I figured I'd add my two cents and hope you see it. I'm an audio engineer in a studio in Pittsburgh, and before that I worked in a large studio in Chicago called CRC. CRC is one of the biggest independent studios in the country and we did both music and post-production (video games, movies, tv shows, etc.) What other people are saying about layers is correct. You have multiple tracks in a single session/song. When the final mix is done, all those tracks are combined into a two channel mix and very often a summed mono mix so that normal stereos can play the track. While I was at CRC, it was very common for us to finish the final mix, and then do multiple variant mixes that we would then give to the artist. For example, we would print the final mix, then we would turn the vocals up a pinch and print a VOX Up mix, then turn them down and do a VOX Down mix, then mute all the instruments and do an acapella mix and then mute all the vocals and do an instrumental mix. We would give all these mixes to the artist or label and then when someone wanted to use the instrumental track for something like a movie trailer, the artist already had an instrumental mix that they could send right away. Once a mix is printed it's damn near impossible to remove just the vocals and not affect anything else. I say damn near because there could possibly be a program out there that could do it, but I don't know of any and I'm not sure how it would be possible. Like you mentioned previously, if you isolate the frequencies of the vocals you're also going to isolate and remove any instrument that falls in that frequency range. Hope this helps!"
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6f4ktq | Why are there so many almost inaudible volume notches on TVs? | Technology | explainlikeimfive | {
"a_id": [
"difeg1c"
],
"text": [
"It's easier to have your volume start at zero and increase by a set amount for each 'notch'. In order to have useful sized increments at higher volumes you end up with some at the lower end that seem pointless. If you run your tv through an amplifier also, some of those lower volume changes do become noticeable."
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6f4pmw | Why in most video games, does it seem that Friendly/Ally A.I. has a much worse A.I. then what Agressive/Enemy A.I. have? | For example; many games have enemies that will only attack the player once they are in sight, but the ally will notice enemies through a wall and will attack the wall thinking they are making progress. | Technology | explainlikeimfive | {
"a_id": [
"difjpyo",
"difeaw1"
],
"text": [
"In a lot of games, the friendly AI is restricted to doing very little so that the player has to do most of the actions required to progress. You see this in a lot of FPS single-player campaigns where your squadmates often seem to be doing nothing useful despite their shooting at the enemy.",
"This is usually done deliberately to make life for you, the player, harder. Also, in some games the AI is better suited to attacking one person (you) than it is multiple enemies (your allies vs your enemies)."
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6f5w9r | How is push-to-start button on cars safer from theft than the old school manual-key-to-start? | Technology | explainlikeimfive | {
"a_id": [
"difo7ui"
],
"text": [
"Simply, it isn't. The push vs latest version of turn has no bearing on security. With a modern turn key, the turning doesn't start the car. It's the key electronics that start the car. The mechanical motion is just user design."
],
"score": [
4
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6f6ey0 | Why aren't large files like games downloaded as zip files then unzipped to save time? | Technology | explainlikeimfive | {
"a_id": [
"difs2zb"
],
"text": [
"They typically are, although not as .zip format. The download is compressed as much as possible - have you not noticed that the installer is much smaller than the installed game?"
],
"score": [
13
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6f6i7e | To what extent would electric cars help in reducing carbon emissions? | If there is a sudden increase in electric cars, the demand for electricity to charge the electric cars will also increase. This would lead to more burning of fossil fuels to produce enough electricity to cope with the rising demand, especially considering that electric cars don't have great mileage. So would the net carbon emission decrease be worth the millions invested into developing this technology? PS- Not a skeptic, I've been wondering about this for quite a while, and hopefully someone proves me wrong. | Technology | explainlikeimfive | {
"a_id": [
"difw0jv",
"difssqn",
"difsvkz"
],
"text": [
"Others have pointed out that using electricity from fossil-fuel plants in electric cars is more energy efficient than using the fossil fuels directly in combustion engines. Here is a (simplified) calculation by how much: Energy efficiencies: Electrical power generation in a fossil fuel plant (chemical to electrical energy): 50% Transmitting the electricity from the power plant to the car (electrical to electrical): 93% Storing electrical energy in a Lithium-ion battery (electrical to chemical energy and back): 85% Using electrical energy in an electric motor (electrical to kinetic): 80% Combined: 0.5 * 0.93 * 0.85 * 0.8=31.6% Burning fossil fuels directly in a combustion engine (chemical to kinetic): 23%, optimistically Again, this is simplified and the percentages vary a lot, but power plants+electric car are definitely more efficient than conventional cars. Not taken into account: Energy expenses for transporting the fossil fuels to gas stations. Also: electric cars typically weigh less and may use regenerative braking energy (more efficient); conventional cars consume gas when motor is turned on but standing still, while electric cars do not. Sources and further information: URL_0 URL_3 URL_1 URL_2",
"1. You can produce electricity by methods other than fossil fuels. Nuclear, hydroelectric, solar, wind and geothermal. 2. Power plants are more energy efficient than internal combustion engines.",
"Two things - Power stations that use non-renewable energy tends to have better efficiency than cars engine. So, given the same amount of fossil fuel, a car can move further(or less fuel required for the same distance). Second, Power station are usually further away from most people live. So even they emit bad gas, less people suffer. Cars, however, run on roads and cities, the bad gas they emit causes harm to the pesdestrians. Is the investment worth it tho, I dont knoe any solid figues. But if there's anything would help improve people's health, I would say the investmen worht it"
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"https://www.fueleconomy.gov/feg/atv-ev.shtml",
"https://en.wikipedia.org/wiki/Energy_conversion_efficiency",
"https://en.wikipedia.org/wiki/Electric_car#Energy_efficiency",
"https://en.wikipedia.org/wiki/Internal_combustion_engine#Energy_efficiency"
],
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"url"
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6f81c2 | What do we measure in MHz when we are talking about CPUs, does it have any moving parts like a Hard-Disk does? | Technology | explainlikeimfive | {
"a_id": [
"dig663w"
],
"text": [
"A CPU is essentially made from switches. Tiny areas on a piece of silicon - a microchip - can be created such that they allow electricity to pass from one place to another when there is electricity supplied at a third point and not otherwise; or the inverse, they prevent electricity from passing through when there is electricity applied to the control point and not otherwise. These are then wired together by making areas of the chip conductive, or by just layering metal on top of the chip. All logic is built out of these. (Good things to Google for are pnp / npn junctions, logic gates, flip flop, half adder, ALU, VLSI if you want to read more about this stuff). At this level, electricity isn't always \"fully on\" or \"fully off\". The switches take time to switch. When the inputs change, the output takes a while to settle down to a stable level. When a bunch of switches are wired together into a circuit, the whole thing takes time to settle down. Human programmers working with the CPU need to be able to reason about its behaviour as a whole. It is easiest to reason about a system that, as a whole, goes from one well-documented stable state to another in response to some input and has no unpredictable behaviours. For this purpose we introduce the idea of a clock: something that regularly pulses electricity. We design all the various circuits such that, when a clock pulse starts and only then, they latch onto their inputs and all the switching starts; this means that as all the switching happens and all of the various outputs fluctuate before settling into the resulting states, we can ignore this fluctuation since the things the outputs are wired to won't look at them before the next clock pulse. The closer together we space the clock pulses, the faster we can go from one state to another, and so the faster we can do work. But we have to wait at least as long between them as it takes for the part of the CPU that takes the longest to settle to a new state when something changes to do that. This rate at which we decide to run the clock - the clock speed, the number of pulses per second, or Hertz - is the MHz (megahertz, million hertz, million pulses per second) figure you are asking about. There are alternative ways of designing a CPU; e.g. \"dual rail logic\" allows each circuit that makes up the CPU to individually tell the things reading its outputs when its outputs are ready, so no overall clock is needed and each part can potentially run at its own speed. This makes the system as a whole much more complex and harder to reason about, and so is rarely done."
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6f8iln | Ubuntu, Debian, Linux - What are they exactly? What's the difference? | Technology | explainlikeimfive | {
"a_id": [
"diga5lw",
"dig88bw"
],
"text": [
"Linux isn't an entire operating system, it's just the core of one- the part that interacts with the hardware, called the kernel. All the tools and programs that run on top of that layer, the parts you interact with (called the \"shell\") aren't part of Linux. With commercial operating systems, the entire operating system is a bundle so you don't have to care that Darwin is the core of osX or that NT is the core of Windows 10, but with open source, you can swap the different parts of the operating systems. Debian and Ubuntu are both the full operating systems- they include all of the pieces. They come with package managers for installing programs, terminals, desktops, and file managers for letting you interact with them, tools for running processes automatically, and so on. Ubuntu is based on Debian, so it includes a lot of the same tools but they add their own features on top of them. Technically, they aren't even tied to Linux. In addition to Debian GNU/Linux (the Debian packages using the GNU tools on top of the Linux kernel), you can also install Debian GNU/kFreeBSD (the Debian packages running on top of the FreeBSD kernel). Someone even got Debian running on top of Darwin, the core of osX.",
"Collection of preinstalled software on top of a common base system. If it was a car, Linux provides the engine, Ubuntu and Debian are different people's views of what seats, what colour, how big the trunk is etc. Some things are similar (in this case how you install things) some are different (the default look and feel/Debian seems to be more servery, Ubuntu more usery, though both can be used for both use cases. )"
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