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nck4o6 | Why aren't letters on keyboards in alphabetical order? | Technology | explainlikeimfive | {
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"This dates back to 1868. Newspaper publisher Christopher Latham Sholes ordered the letters on the keyboard to qwerty or qwertz layout that we know now because otherwise type levers of a type writer would get caught in each other while typing, so he thought. The layout puts the letters that followed each other the most as far away from each other as possible so that the type levers would not get caught in each other while using (typing). Qwerty has solely mechanical reasons or as one would say it has a statistical background, but it only came through since the 1920s",
"Because that's not how people type. If you're designing a truly efficient keyboard, the way you do so is by examining what sequences of letters/symbols occur most often and you place keys in proximity to one another to minimize the distance the user needs to move their fingers (there are other details such as the relatively static rate at which people process the symbols themselves). However, the science behind this sort of usability design didn't exist back when the first keyboards were created. One apocryphal story is that keyboards were designed to prevent jamming - they were purposefully made inefficient so you couldn't type *too* far. That story doesn't really hold water once you look at the QWERTY layout because it *is* reasonably efficient. It's the sort of thing someone would design if they didn't have the mathematical or theoretical background to design a truly efficient keyboard. Commonly used letters are near the center, vowels are easily reached and in high-impact points, etc. So the best explanation is that someone who had an inkling of how typing actually occurs just did the best they could with the mathematical/theoretical tools available at the time. Once a standard format existed, it quickly gained a large number of adherents that made changing that format difficult."
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ncq2s1 | Why are people not visible in Google Maps satellite images (and others)? | When you call up a view of a large city in Google Maps you can clearly see vehicles and buildings, but never any people. Even in areas where you'd expect to see a large density of people they aren't visible. Why not? | Technology | explainlikeimfive | {
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"Any large scale map will be made up of many individual pictures stitched together. This allows you to zoom in and get detail in each image but still have a large final product. This sometimes causes vehicles to fade out of view from end to end, because they moved between pictures. I would imagine they turned this into a tool that allowed them to select portions from each picture that doesn't have a person, to cover others that do. That way you don't have all those people blocking the ground and any details you want from that.",
"You can sometimes, but it's largely a result of how the images are taken. The images are actually layers of several different pictures taken by satellites and aircraft at different times. Because they're taken at different times, motion gets blurred out when the layers are combined, and people tend to be moving. In places where people tend to be stationary, you can see them. [Look here for example]( URL_0 ). This is the famous Maho Beach on the island of St. Martin. Aircraft fly low right over the beach before they land, and beach-goers stand around for long periods of time watching the planes fly just over their heads. Because they're stationary for so long, they show up in the image, although the resolving power is not that great so they just look like small black dots."
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ncqmp1 | If you have an old 3G/4G capable SIM card, why do you need a new one to access 5G? | Same question as upgrading from 3G to 4G etc. Isn't the technology for connecting to 5G networks all on your phone anyway? What exactly does a SIM card do/need to make the upgrade necessary? | Technology | explainlikeimfive | {
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"You don't need a new SIM card for 5G. You need a new phone. The phone that you currently have, unless it was built with 5G specifications, does not have the capability to broadcast or receive 5G signals. SIM card doesn't matter. Your phone needs to have compatible hardware.",
"Sim card has nothing to do with it. Only your phone matters. Sim card is just a encrypted ID that says you are a unique ID attached to your carrier. It isn't even required for anything to work. You can still call emergency numbers for example without one. It's just for billing."
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nct7kf | how is it possible to program a computer to “understand a keyboard” without a keyboard? | Technology | explainlikeimfive | {
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"The thing that makes a computer understand a keyboard is just another piece of software. You can create that bit on a computer that does have a keyboard and then make it part of the OS (or even BIOS) that will be installed on the computer that doesn't have one. Your computer was built to understand keyboards before you even got it. If you're asking about the *first* keyboard: there was always some way of providing input to a computer. In the earlier days you had punchcards. They build the computer so that it could read the holes in the card, and you can 'write' the software that can communicate with a keyboard via those cards.",
"Computers don't \"understand\" anything. All input and output to a computer are a series of on and off signals. We usually think of them as 0's and 1's but in a computer it is the presence or absence of voltages on particular wires. The computer doesn't \"know\" if the signals come from a keyboard, mouse, HDD, ethernet. The signals are run through programs that decode the signals into other signals - that is pretty much it. A programmer that writes a keyboard driver (essentially a program) to do the necessary interpretation. The computer might see a number like 01010001. The keyboard driver might decode that as \"A\", the same 01010001 going through the mouse driver might interpret that as the mouse moving left. That number sent to the video card might output a yellow dot on a screen. The computer doesn't \"understand\" anything of this - it simply runs the program, takes in the input, and sends some output. That said, any device can be simulated by mimicking the input signal. The computer wouldn't know the difference."
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ncv12t | If internet is a peer to peer network and if nobody is particularly its owner then why do we have to pay for domain names while establishing a new website? Shouldn’t it be free? | Technology | explainlikeimfive | {
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"While \"the internet\" doesn't belong to anyone as a total it's infrastructure does belong to people. And if you want someone to take the effort and notify domain name servers that this domain belongs to that IP you will have to pay him to do so. You can put a website up without a domain and don't have any problems. But then people will have to type your IP in manually",
"It isn't a peer to peer network. Companies and governments own maintain the infrastructure used to keep it operational.",
"Web (that is just one part of the Internet) is not peer to peer. P2P would mean that every client is also a server which is not the case. When you setup a domain name you pay for a service that converts the IP address of the server your site is hosted at (that four groups of three digits numbers) into something more meaningful like URL_0 . While that service is provided by non-profit organization its operation costs money, there are computers, bandwidth, electricity, employees...",
"Computers on the Internet identify each other using IP addresses. If you want to talk to another computer (say, Reddit's servers) you need to know that server's IP address before you contact it. How else would you get the message to the server if you don't know where to send it to? Easy enough then. So what's Reddit's IP address, off the top of your head? ... Hmm? You don't know? Come on, they probably have several, you only need to tell me one of them! ... What? You don't just memorize a bunch of random numbers for every web site you want to visit? Well congratulations, you're just like the rest of us stupid humans. Memorizing numbers is hard. But memorizing names is easy. For computers, it's the reverse--numbers for them are easy, but names are tricky. What we need is a way to translate between the two. This can be solved with a simple list of every website on the entire Internet, where each name is matched to each number (or group of numbers). All you would have to do is type in a name, it would search the list, and it would get the IP address you need. This is the Domain Name System, or DNS. Every time you type in a website name to your browser, your computer will check its list of records to see if it already knows which IP address matches the name you just typed in. If it doesn't find it on its list, it \"knows a guy\" (i.e. another computer) with a more complete list that it can ask. If that computer doesn't know, it also \"knows a guy\" and asks. This continues up the chain until an answer comes back. This leaves a really big question: who is at the end of this chain? Someone has to be at the very end that holds a master list. And you have to be able to trust this entity to not be lying to you... imagine if the \"I know a guy\" your computer asks for new DNS records has been secretly feeding you the IP addresses of malicious computers that are disguised like the websites you want, but are actually stealing all of your data. It could totally happen! It turns out that the end of the chain for almost all people is an international, non-profit corporation called ICANN. These are the guys that have *the* master list. They could, theoretically, at any moment, decide who owns what simply by updating their list, and since basically everyone trusts them, everyone will all update their own lists to match. Running this corporation smoothly, keeping it secure and keeping the list up to date with everyone requesting new domains all the time, has running costs. Therefore, if you want them to update their list to say your computer is what URL_0 should point to, they charge a fee. The next question is, \"if I'm paying ICANN for this, why is it that when I buy a domain, I have to use a company like GoDaddy or Namecheap? Who are these guys?\" Put very simply, they're wholesalers. ICANN can't manage the needs of every single user who wants to buy domains across the entire planet, keeping up with every single country's customs and laws and speaking every language. That's a disgustingly huge task. Instead, domain registrars like GoDaddy serve as middlemen. ICANN allows a short list of vetted companies to put in bulk orders for domains on behalf of clients all around the world. They deal with all of the local faffery while ICANN can keep its attention on the core task of maintaining the list. You can always trust someone other than ICANN if you really want to. DNS allows you to \"trust\" any \"root\" you want. And there are other \"master lists\" out there maintained separately from ICANN's list. If you wanted to buy a domain on those lists, you'd probably pay money to those groups instead. You can also declare yourself to be the \"root\" and make all of your own devices on your network trust you for some certain websites. Companies might do this on their internal networks so that parts of their network can be accessed with domains they made up themselves. The system is very flexible. It's just that most PCs and programs come pre-installed to trust ICANN and no one else; if you want the computer to trust a new root authority, you have to manually set it up to do so. So, tl;dr, the Internet *is* peer-to-peer and more or less totally open and free. But to use it, you have to use numbers for everything. If you want to use human-readable names, that's a convenience feature that you have to pay for.",
"Anyone *can* create a new website without specifically paying for it (but they *do* have to pay for the connection to the internet at a minimum). What they *do* have to pay for is the service that turns URL_0 into your servers IP address (which may look like 242.214.123.2). It's a lot easier to remember \"MyFancyNewWebsite\" than the numbers....but the only way you get that is if you pay someone to tell everyone who looks for \"MyFancyNewWebsite\" what the numbers are, because you computer cares about the numbers, not the name."
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ncvv9s | How come deleting an app on a phone is so quick and easy but deleting an app on a desktop takes much longer and more steps? | Technology | explainlikeimfive | {
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"Mobile apps are installed in their own separate container, all in one place and all in the same way. Deleting them is as simple as deleting the container. PC applications (unless they’re similarly-packaged apps from the Store) have no standard single location but are spread about the the disk and various databases and need to provide their own custom uninstallation process in the same way they provide their own custom installation process.",
"In reality, it doesn't take much less time on a phone. It's just that when you select \"uninstall\" on a phone, everything happens in the background and you don't notice it so much, whereas on a computer it's generally put right in front of you. As for the easy/fewer steps part, that's because it's all handled by the app store. If you are a Windows developer then you have no incentive to make the uninstallation process simple - you want people to keep using the app! But on Android, for example, the app developer doesn't design the uninstallation process, Google does, and they want to make the experience of using their store as seamless and simple as possible to encourage people to use it."
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nd0p3u | Why do several of my devices have the same Ip address? | Most people have told me that 2 devices can't have the same address but when I type what's my ip address on google I've got the same result on all the devices I've checked | Technology | explainlikeimfive | {
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"Your home internet connection only has 1 public IP address, so every device connected to it will have the same public IP. So your router can tell the difference, each device connected will be assigned a different private IP address, but that address is only used within your home network."
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nd3190 | What is the process of digitising old literature & why are so many old books not? | Technology | explainlikeimfive | {
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"I have some relevant experience here. I've been involved with digitizing documents for a 100+ year old society and I also personally collect rare and antique books. To start, digitizing something isn't trivial. A lot of times, to get the best scan without bankrupting the organization, the books need to be torn so the page can lay flat on the scanner. Clearly not ideal but good for content that has a lot of duplicates where destroying a copy doesn't matter. For more unique items you cannot destroy, someone needs to actually handle each page and make sure the scan worked without issues (i.e. no blurring, etc). This very manual process means the cost is significantly higher not just in labor but you might need a specialized scanner. For more unique and older items, many of them are required to be in a library or some other organization where you likely won't be allowed to bring in your equipment so scanning it is simply not going to be done. Many libraries in particular might not have the resources to digitize the content. I'm not sure what you consider \"old\" since some of my books are 500 years old but anything older than about 200+ years old requires delicate handling. This means that you cannot use any regular scanner. There are slanted scanners that basically allow you open the book partially while it scans properly but like the previous example of manual scanning, this is even more expensive and more time consuming since the books are likely going to be more fragile. When you get into 500+ year old books, you also have a danger of exposing the contents to the bright light that's associated with the scanner. This could damage some books. In addition, some old books can get wavy with time so scanning them would not be ideal and would require additional work. The older the book, the more fragile it is, and the more work you need to digitize it. In a place like South Africa, they might not have the equipment or the funds (and likely both) to afford such an expense. It's a real tragedy when unique works are lost."
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nd4nj2 | Why are some password settings so strict? | Why are some password settings so specific? I've seen some that are like "You must have one special character, one number, and at least 8 letters" or something. Why does it matter that much? | Technology | explainlikeimfive | {
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"In general, the security of a password depends on length, and uniqueness. I don't know the exact number (I'm sure someone can correct me) but a password less than 6 characters can be brute forced (can be guessed by repeated attempts) in minutes, whereas a password 20+ characters long could take 10's or 100's of years to brute force. Naturally, the easiest solution to this problem is to enforce a minimum number of characters to make the password reasonably secure. The second issue is uniqueness. People tend to pick common words because they're easier to remember. There's a reason why the most common passwords are \"password\", \"123456789\", \"password123\", etc. By adding unique characters it makes it harder to guess a password since it doesn't fall within a dictionary list of words a computer can use to guess while brute forcing. This is one of reasons password managers are so great. You can have it auto-generate a password that's say 26 characters long and full of absolute gibberish. Both the length and randomness make it virtually impossible to guess, ensuring your account security. As always, here's a [relevant XKCD]( URL_0 ) that essential summarizes what I just said.",
"There are libraries of passwords and then there are programs that just try all the characters. The English language uses 26 characters, which is 52 if upper case and lower case count as different. That's really not a lot of possible combinations right? So let's at the 10 numbers, all the special characters from the keyboard which in total all ends up around 256 character to make something out of. So this means that library they use to match a password just got a lot bigger AND now you are required to use some of them, so now when you try to use a simple password like \"password\" you can't, you have to add some crazy characters which makes it more complicated. So in short, this makes it more complex to figure out which means it takes longer to \"crack\" and the. Add that you should change it every 6 months or so... It is slightly more secure.",
"Without getting into industry guidelines, all boils down to math. The alphabet has 26 letters total. Upper and lower case doubles that to 52, adding 10 digits and 33 special characters gets you to 95 total characters for 1 slot. Each added character to a password length introduces an exponential amount of additional possibilities. To attack this, we have a few methods. The most simple is a brute force attack. A computer calculates and tries every single possibility. It takes a lot of time, going up with every character added. It's limited by how fast a computer can think. Another method is a dictionary attack. I feed a computer a list of words, it checks this list. Faster then brute force, but limited by what's in the dictionary. This can be improved by creating custom wordlists that guess what your password might relate to, like your pets name, hometown, car models, hobbies, birthday etc. Rainbow tables are another method. Passwords are usually ran through a function and stored as hashes instead of plaintext, similar to taking your password, translating it to pig Latin, and storing it. Instead of attacking the password, it looks at a list of hashes to find what pig Latin phrase is your password, then compares it. These are fantastic, but are limited to only the language you're looking at. (Pig Latin vs Spanish). It's much faster for a computer to guess your password is rosewood instead of R05eW00d, and even more complex if it's R0$€w0Od, but not more secure then something like ^9oQ & 95hD. I always prefer passphrases instead of passwords, like \"This house is made of rosewood\" turned into \"Th1$ H0u$3 15 M@d3 0f R0$3w00d\" where every starting letter is capitol, if it can be a number/symbol substitution it is, etc. It's more practical and secure. You can use a site like this to test. URL_0"
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nd9oh1 | How does pirating movies, shows, video games etc. work, and why can't creators/producers prevent it from happening? | Or could creators prevent it if they wanted to, and it just isn't worth the added costs of additional security? | Technology | explainlikeimfive | {
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"Movies and shows are easy. The experience is the same for everyone, and so all you have to do is record the experience and share it. That's easy piracy. Video games are often much harder. While many approaches exist to mitigate piracy, the easiest for films and shows is to target the distributors. Websites that distribute pirated content. It's still not super effective, though.",
"There are lots of ways to prevent it from happening, but there are a lot of dedicated people out there who will go through a lot of effort to thwart it. So DRM or Digital Rights Management is a very broad category of ways to protect media and software. For media, its usually a form of crypto that encrypts or scrambles the media - if you're a legit customer, your app or website login has the key to unlock or unscramble it. For video games or software, the easiest way is simply to have the software phone home - if you (as identified by your name, key or something else) is authorized to user it, it works. If it can't phone home or your name or key doesn't match, it doesn't. Back in the day, software keys were just cryptographic hashes of a user name or your email or something. So if you had the key AND you had the name that goes with it, it would work. The next step up are \"keygens\" or programs that used the reverse engineered crypto algorithm to allow you to generate the correct \"key\" for any name or email. But now its all online - easier to implement... sucks more for the end user. For media tho, there are lots of ways around DRM - for services like iTunes, if the media is still protected, people have written apps to unencrypt the files. For websites like HBO or Netflix they've written programs that will record the video as it is played back in the legit/legal player... if not directly find out where the media is stored and unencrypt it, then repackage it. Fundamentally media and software producers are constantly playing cat and mouse with pirates. They'll come up with some new scheme to protect their stuff and within a week (if not days) the stuff will be on The Pirate Bay in glorious HD complete with crowd-sourced subtitles. There will always be people who pirate stuff. Its a \"stick it to the man\" thing. There will always be a majority of people who don't mind paying for stuff. Like I have no problem paying for a premium Spotify account even though I have an MP3 library from all my old CDs that I ripped, or downloaded from Napster etc. back in the day. Way I see it, is now that I have a good job and have disposable income, $15/month isn't too bad for every single song known to man... plus my artists get a fraction of a cent, and if enough people listen, they make more music and I win. Look, I want to pay content creators for media and software. I mean I pay the grocer for my food right? I want people to pay for the software I develop so I can eat right? The only time I'll turn to piracy is if you deliberately make it hard for me to buy it. Listen, I have an xbox/microsoft account, iTunes, google play, Netflix, spotfy, crave and amazon prime video account, steam, battlenet etc. If I can't go to one of those services and one-click buy the thing I want then fuck you Im going to pirate it. I want to give you my money. HBO is the worst (in Canada anyway). I want to watch Game of Thrones - watch it in HBO Go. Nope, sorry you need a cable subscription. But the reason I want to watch it online is because I don't have a cable subscription you idiots! Yeah, HBO is bad, I just go right to Pirate Bay for their stuff. But if you make it reasonably priced: $5 for a AAA movie, $2 for a show episode, $10-20 for a season, I'd sooner just pay for it.",
"It works by having someone create a copy of an item, whether it be a physical one (dvd, etc) or a digital one (MP3, video file, etc) using a source, which could be, again, a physical or digital one. Once a copy is made, it is then distributed via the internet (torrents, news groups, forums, etc) or physically (passing the copy on via a USB stick, dvd, etc). There are systems in place to stop it, such as fake torrent seeds (pretending to share a copy to catch those downloading it, or pretend to be a user to download a copy to catch those sharing it) or forum scrapers (automated systems which 'read' forum posts and gather information on the person who posted the content), although in some cases it was allowed to spread to assist in the item's adoption (in Microsoft Office's case, it was better for MS to lose licence fees for home users and have them become proficient in it's use, than to try to recoup the losses). You'll see things such as 'take down' notices where a company has formally requested access be removed for a site/link to an item or legal requests to end users like [copyright infringement notices]( URL_0 .)"
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ndcjqr | how do Air Fryers work? | Technology | explainlikeimfive | {
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"It's just hot air spun around by a fan, the same as what's called a convection oven. Nothing is really fried. It's a marketing trick because people like fried food and the spinning air makes the food crispier than non-moving air.",
"It suspends the food in a mesh basket inside a chamber. Hot air is blown inside similar to a convection oven, except in an air fryer air can flow under the food since it's suspended in a mesh basket.",
"There is still an important concept missing from the other explanations. Oil plays a large role in how an air fryer works. To start, let's look at how an oven, convention oven, and deep fryer work. An oven and convection oven both cook food by heating air and having it circulate around the food. Convection ovens use a fan to move air around, but a regular oven doesn't. However, a deep fryer uses an electrical heating element to heat oil. The oil is hot enough, and contains enough energy, to cause the water in the outer layer of your food to flash into steam. This is how fried foods get a nice crunchy crispy exterior. Onto an air fryer. Instead of heating a giant container full of oil (which can be really dangerous and generally splatters badly when food is added to it), a small amount of oil is added to the outer layer of a food. A quick shot of cooking spray is sufficient. The air fryer then uses circulating hot air to heat the oil, which in turn heats the food. This is how it fries foods. Without any oil, it's essentially a convection oven."
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nddia1 | How do smart watches/wearable fitness trackers work? | Monitoring your heart rate seems simple enough, but how do they formulate information about your sleep, calories etc.? | Technology | explainlikeimfive | {
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"The data you put in and analysis of movement metrics and heartrate. For example, if it knows your height and weight, when you go for a brisk walk it can detect the walking motion and rough speed, sometimes including GPS data, then combine height + weight + type of activity = decent approximation of calories burned. For sleep, it detects position (you lying down), the types of motion, and heart rate, and can make educated guesses about when you were sleeping. Here's a *really* detailed look at the sleep data interpretation: [ URL_0 ]( URL_0 )",
"They typically use an accelerometer to detect orientation and movement and monitor how it changes over time. For example, an Apple Watch guesses that you are standing when the watch face is perpendicular to the pull of gravity and the appropriate side, based on how you told it you wear it, is pointing down. If it detects a similar orientation but swinging back and forth and also detects the shock of your feet hitting the ground, it is generally safe to assume you are walking. Combine that with the barometer detecting an elevation change and it knows you’re on stairs. Detecting a rise in heart rate and it can deduce that you may be exercising."
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ndmghl | How are manufacturers able to manufacture really small cpu transistors? | Technology | explainlikeimfive | {
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"Photolithography. You know how a projector can take a small image and turn it into a massive projected image? You basically do that in reverse, large designs which get focused down and etched into the silicon by bombarding it with light.",
"They use chemicals to build a thin layer, use light to burn it off in places, then more chemicals to actually modify the exposed parts of the chip (e.g. acids to create channels for conductors). The advantage of using light is you can shine it through a bigger guide (that creates the necessary patterns) and reflect it down to a very small size.",
"This is a very complicated question since modern processors take like 3 months and over 1000 steps to make, but ill do my best to skip all the detail and make it really ELI5 They use special chemicals and light to draw a pattern, or mask, on the silicon. They can then modify or remove the parts of the silicon that is not exposed. This process along with several other specialized processes for each step is repeated to modify the silicon to make transistors, replace parts of it with wiring to connect everything and then build a big stack of wiring on top of it that connects it all to the rest of the computer. They key processes used are: Lithography (drawing a pattern with light and chemicals) Implant (modifying exposed silicon by adding trace amounts of other atoms to it) Etch (removing exposed silicon (or other materials) by either chemical solutions or chemical plasmas) Deposition (depositing a film on the silicon, sometimes to fill in silicon that was removed with etch, sometimes to make a new film that will be etched to have something else filled into it) Polish (smoothing out the wafer after various steps make it rough or deposit too much material)",
"You know how you can use a magnifying glass to burn stuff by concentrating rays in a tiny area? Manufacturers use a magnifying glass with a pattern on it, then the concentrated rays burn out very tiny patterns in a tiny area. The burnt areas have different physical properties to unburnt areas, and with the right pattern this creates a transistor.",
"Lithography is the term your seeing over and over here. But it's not as simple as everyone is making it sound, it's a really amazing process to generate appropriately small wavelengths of light. Eli5 version is, imagine light is like a marker, you can only make lines as thin as your marker tip, in order to make a smaller marker tip they use one marker (a laser) to make a new marker that's smaller, by shooting a laser into a perfectly round ball of tin, that tin then emits new light if a smaller wavelength (aka smaller marker) Search youtube for euv"
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ndomgc | How do body fat scales work? | Technology | explainlikeimfive | {
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"Fat tissues are much less conductive than muscles. Body fat scale runs a very weak current through your body and calculates the fat mass by comparing the outgoing and incoming current."
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ndwbcy | What's the difference between a server and a cloud when it comes to data storage? | Technology | explainlikeimfive | {
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"A lot of people are telling you what makes up \"the cloud\", but I think it is more instructive to talk about how the term was intended to be used. In the past when a company wanted to do something involving computers such as build a billing system for multiple store locations, they would draw up a big diagram for how their system would work. This would include everything involved, from the devices used by the workers at the locations (thin client, thick client, etc), the network topology, etc. A major part of that was figuring out the hardware requirements for their own billing server, where it was going to be housed, who was going to maintain it, etc. Instead many companies in the modern way of doing things will have that part of the diagram pointing towards a literal line drawing of a fluffy cloud. This is because the server is housed \"in the cloud\", which is to say they will pay a different company to provide computing resources and management. After all, if you own a chain of coffee shops you probably don't want to be building out a server facility, you don't have that talent on payroll. So \"cloud computing\" isn't really a technology as much as it is an organizational concept."
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ndy7fb | How do anchors on yachts work and how can they hold a whole boat when they lay on flat sea ground? | Technology | explainlikeimfive | {
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"That's not how anchors work. They act to hold one end of a heavy chain so that the ship can lay it out on the bottom. The chain applies the forces that keep the ship in the right area.",
"Firstly, the horizontal forces acting on a boat aren’t as big as you might think. Certainly less than the weight of the vessel. Then consider the shape of an anchor. In all cases they are designed so that if you pull them horizontally they dig into the ground. The further you pull the deeper they dig. So suddenly you aren’t just trying to pull the anchor, you are trying to pull all of the ground that it is under. You can imagine that an anchor doesn’t have to be buried very deep before the amount of ground you have to pull far exceeds any force you can apply."
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ne1ul4 | Why do some products like TV remotes still use infrared while everything else is moving to Bluetooth? | Technology | explainlikeimfive | {
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"\"If it ain't broke, don't fix it\". IR remote control is simple, robust, low-tech and extremely widely established. It just works, every manufacturer has experience with it and has the supply chains set up. You only change it when there is real benefit in doing so. For example, if you need to send more or more complex data than \"button has been pushed\". One such thing might be a remote that gives haptic or optical feedback, or has a pointer-style functionality on gyroscopic basis. All of that needs more data connectivity than IR can provide, and therefore manufacturers switch to BT.",
"There’s no interference with IR, and it uses a fraction of the power needed for radio signal.",
"Bluetooth is expensive. IR is cheap as hell. IR is just a LED light. Bluetooth needs an encoder, radio transmitter receiver, software to do handshaking and pairing,",
"First is the principle of \"if it ain't broke, don't fix it.\" Infrared remotes have been around for 40 years and work just fine. Infrared is also cheaper and less power hungry."
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ne5gdq | How are data/files recoverable off of a computer after they have been "deleted?" Is this just Hollywood trickery? | Edit: Fantastic answers, thanks all for the insight! | Technology | explainlikeimfive | {
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"Imagine your hard drive as a big notebook. When you want to write something, your operating system finds either a blank page or one that has junk it can erase and writes the data there. But in order to find that file later, it needs to write a \"table of contents\", a list of each file with the page number it belongs on. When you go and delete a file, your OS is lazy and just erases the filename from that table of contents. That means that the data's still written in the book, the OS just doesn't know where. So data recovery folks will just ignore the table of contents and go look through the pages one by one till they find the data they want to recover. There's also ways to recover data even if you told the OS to go erase the actual data, very similarly to how using an eraser on pencil still leaves indentations and smudges where the writing was.",
"When you delete a file, all you’re really doing is saying “this isn’t needed, it’s OK to overwrite” but that doesn’t mean it immediately is reused. Think of it like checking out of a hotel room. You’re key no longer works, but the room remains as you left it until housekeeping needs the room and makes it up again.",
"For mechanical hard drives, to save time, instead of writing zeroes or random data on top of an existing file, typically just the reference in what essentially is a giant table if contents is erased. To the OS, the results in the same effect: that space now contains no data of any importance and is available for future use. However, unless something else is written to that space, the physical location that file formerly resided in the disc surface will contain the data that previously was that file. Software tools can instruct a drive to go to that specific location and read what's there even if the OS thinks there's nothing of importance, and the previous file can be recovered if it is still there. For an analogy, think of just erasing a single line out of the table of contents of a notebook, instead of also going to that specific page and erasing the data itself.",
"When A file is deleted off of the computer hard drive, most times all that is happening is that the title of the file and its location on the disk are erased from the File Allocation Table. The file itself still resides on the disk and can be recovered with the right software. This is why the department of defense Recommends that you wipe the drive completely three times in order to destroy any and all information that is on it before donating, or even destroy the disk completely to prevent the information from ending up in the wrong hands. Edit to add: DOD Specs 5220.22-M specifies that you should write a random character in every space on the drive 3 times to assure that it is not recoverable. I worked in the Justice Department and we would wipe all drives three times random and then one MORE time with all zeros as some software would view 'random' as 'not wiped.' All zero's in every space took care of this bit.",
"When you delete something, the operating system marks it to be overwritten on the hard drive and hides it from being seen or accessed. If it never gets overwritten, then special software can go in and unmark it and allow it to show up again. Deleting something by overwriting the bits with ones or zeroes is called \"wiping\" the information and is done with sensitive or classified material.",
"Usually, when a file gets deleted, the only thing the computer does is it throws a tarp over the data and hangs a sign on it saying \"VACANT\". All the data is still there. This is why deleting even really huge files is basically instant, because nothing actually got deleted, it just got flagged as vacant space. When you use programs that inspect your computer's storage, they have to trust the operating system to tell them which files are actually there or not. When the OS sees the \"VACANT\" sign, it skips it over and reports no files there to programs. If a program wants to write new data there, the OS will happily write new data completely over the old stuff as if it wasn't even there. There are special programs that don't go through the operating system's normal channels and check the storage directly themselves. They see the \"VACANT\" sign and instead of pretending there are no files there, they cast off the tarp and find all the old data. If you want to truly delete a file, you have to tell the operating system to not only mark the data as vacant, but to write new data over top of all the old stuff. Manually erase it. You can write whatever you want, but customarily one would write a bunch of binary zeroes over the old data. Doing this is often referred to as \"zeroing\" the drive. In some cases even this doesn't fully delete the data, though. On spinning hard disk drives, the platters that store the data store it as tiny magnetic charges all next to one another. Writing new data on the disk over top of old data in theory should flip the charges around perfectly, but it's not always so perfect. A shadow of the old data can be found on the old drive if you inspect it with very special tools. This technique can be used to recover data from platters that have even been zeroed out the long way. One also has to be worried about so-called \"bad sectors\". That is, chunks of the disk are reported to the computer as corrupted, failed, or damaged, rendering them inaccessible by normal means. Any data that is in a sector that goes bad will basically stay there (assuming it isn't damaged by whatever caused the sector to fail). Special tools can scan these failed sectors and recover data left on these too. If you want to defeat these kinds of data necromancy from ever bringing your data back, you may want to zero-out up to a dozen times in a row or more. Or you can just straight up physically shred your drive platters into bits or destroy it by other means. Completely destroying the physical disk is the only way to ensure beyond any doubt that the data is truly gone. It's just more time consuming to do, especially at the scale of a large office that could be dumping hundreds of these things all at once, so it rarely gets done. So no, this isn't entirely Hollywood trickery. If it's the first kind of deleted data I mentioned, this is something you can easily do at home with some readily available software. The other, more specific kind of data recovery is also possible, but I understand it is very expensive and doesn't always work. The exact nature of the recovery might be embellished for a show narrative, as all things often are, but it is rooted in some reality."
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ne8wco | Neural networks/Machine learning | I'm a student of computer science, so you don't need totally ground level resources, but I'd like some really dumbed down explanations of neural networks. All help is appreciated, thank you :) | Technology | explainlikeimfive | {
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"A neural network mimics the function of a human brain. You take a very simple unit and call it neuron. It has several Inputs, one Output, weights that multiply the inputs with a constant, and an activiation function (a simple one would be sum(Inputs) > constant but often we use something smooth like a tangens) Okay this alone can't do much. But if you connect many of them they can learn to solve tasks through abstraction an pattern matching. You connect many of these neurons in several layers and then alter their weights so that the whole networks gives you a good output for the given input. So as an example you want to check if pictures have trees in them. So first layer receives raw pixel data and generates outputs that could for example be areas of dominant colours. The next layer takes this and outputs areas it recognizes as certain shapes. The next layer then looks for shapes that might resemble trunks and crowns, and then the last layer only generates a binary output \"Tree/No Tree\" You don't define how the network shall do that, it decides itself what kind of abstractions it uses (and it's almost impossible to figure that out) During the training you just wiggle the weights around until the number of correct guesses is maximized."
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neapj1 | why does the graphics rendering of night scenes more demanding than day scenes in games? | This may not apply in all games but I've played some games with day/night cycles, but overall the experience I got was that most of the time, when during night time, the game had FPS drops lower than day time. For example, I played NFS Heat and I get around 30 fps at day. When I play at night, for some unknown reason for me, it drops about 5-10 fps at most. It's a very shallow question I know, but I would love to get an answer from y'all since this has been one of those things you can't really shake off your mind | Technology | explainlikeimfive | {
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"I would guess it has to do with the number of light sources in night vs day. Daylight is usually just a single sun source, whereas the night scenes have a ton of different color neon lights and stuff. They *should* bake a light map so that its less intensive but I think those games like to use a lot of dynamic sources that will change reflection bounces based on movement in the scene rather than being statically painted. You should be able to lower graphics settings to get less dynamic lighting (look for a setting like Global Illumination or something along that line)",
"It most likely has something to do with how the game handles reflections and shadows, but this will vary greatly on a game by game bases."
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neoui7 | The ads I see in fremium gaming that claim you can "earn real money just by playing!" aren't these just scams or are they real? | I play this interior design game on my phone and I constantly get ads for other games that claim you can "win real money just by playing!" or "win real amazon giftcards by playing games!". I always just assume these are scams, but I'm curious: does anyone have any experiences with these "realmoney" games? Are they real or is it just another way for hackers to steal your info? | Technology | explainlikeimfive | {
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"bit of both. this is generally these companies having deals with ad companies ot get your data/clicks in hopes you'll buy into them. honestly wouldn't recommend as this generally is how you end up with a crapload of spam mail and potentially leaked info.",
"Depends on the game. Most of the ones you see on a regular basis are probably legit in terms of \"can you make ANY money?\", otherwise they'd get complaints and get pulled from the marketplaces. Now, how much money, that is usually the grey area. Typically you have to sink a ton of time into those games to make any significant return cause they gotta make more money on ad revenue than their paying you to play the game. So you might end up with a couple bucks a month or maybe a week if your hardcore playing but it'll never be enough to really make a difference unless you are finding some way to cheese the system 24/7.",
"I'm sure a fair number of these are scams. But it's possible for this kind of incentive to be legitimate, considering the following two facts: - Most players don't win much - It's hard to withdraw your money If you win $1.37 playing the game for 10 hours, you're probably not going to bother going through the hassle of figuring out how to actually get paid. You're also not necessarily going to spend 1000 hours to win a somewhat meaningful amount of money (more than $100). So they may actually pay out non-trivial amounts to a few very dedicated souls who love the game (or get obsessively fixated on the idea of free money) and put in hundreds or thousands of hours. But there are thousands of much less dedicated customers with tiny balances that they never claim. Gift cards are a variation on the theme. Unless you have a coder and an artist who work for free, even the cheapest games generally have $thousands in development costs. So buying say ten $100 gift cards isn't large relative to the game's total budget, and then you can honestly say people *can* win a $100 gift card by playing. Of course if 10,000 people play the game and there are 10 gift cards to go around, that means 999 players out of 1000 will get $0. This kind of thing's not exactly a *scam* in that the \"winning real money\" part is *technically* true. But if you're having fantasies of becoming a millionaire or quitting your job to play games full time, keep in mind that you'll probably be \"earning\" much less than $1 an hour.",
"Yeah they're *essentially* scams, but not in a hackers stealing your info sense. They're basically glorified ad platforms. Companies pay these platforms to tell you that they'll pay you to play their game. As far as the game company is concerned, it's paying money to acquire players, just instead of an paying it to an ad agency that tries to make the game look like it's worth playing, it pays it to an ad agency that says it'll pay you if you play it. So if our ad platform is Company A and our boring game is company B, and you are Consumer C, then B gives money to A, and A tells C that they'll give C money if C plays B's game. As far as B is concerned, it has gained a player, a player who might just like the game enough or be enough of a gambling addict to spend money on it. Meanwhile, C believes that they are being paid to play this game, when in reality company A has a bunch of obscuring factors that prevent C ever taking their earned money - things like \"you actually get entered into a lottery system where you can win the money\" or \"You can only take your money out once you've racked up £10 from playing 20 hours of stupid games\". So in essence, C has given money to B and B has given money to A, all based on the lie that A will give money to C (although imagine that C and B are the average consumer and company, not the individual - most Cs won't spend anything, but the occasional one will and that's enough). These methods can also be used by companies to get what is essentially a beta test audience for a game that otherwise wouldn't be good enough to get beta testers. In short, it's a platform for advertising specifically to people stupid enough (or desperate enough) to think that 10p for essentially doing 30 minutes of work is a good deal."
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nep8rw | Why does the pitch of an audio clip go higher or lower when slowed or sped up? | Technology | explainlikeimfive | {
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"The pitch is directly related to the frequency of the sound wave measured by the number of wiggles over time. If you speed up or slow down a song, you're affecting the \"time\" part of the pitch. Because frequency is \"over time\", slowing down or lengthening the time lowers the frequency/pitch. Likewise, speeding up or shortening time raises the frequency/pitch.",
"Typically, this would be done by speeding up a tape. Pitch is defined by frequency of notes. Higher frequency = higher pitch, lower freq = lower pitch. Imagine a length of paper tape with marks on it at regular intervals, say 1 inch between each. Move the tape at 1 inch per second, and you have frequency of 1 mark per sec. Double the speed, and the frequency will be 2 marks per second. Double it again, and the frequency is 4 marks per second. That's how you increase frequency. Frequency goes up, pitch goes up."
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nervye | How were websites created before web hosting services? | I know that you can create websites using services like WordPress, but before those existed how did people code websites and put them on the internet? | Technology | explainlikeimfive | {
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"< HEADER > HTMLv4 static web pages. < \\HEADER > < BODY > Geocities was a very popular tool with templates to make static HTML pages, or write your own code. You could host there, and setup a CNAME in DNS to get your custom domain to point to it. There were also services you could rent space on other people’s servers for a monthly fee, just like today, but again: static HTML. You could also setup a web server in your home. Today it sounds scary AF to open a port in your firewall to a web server on your home network, but frankly back in 1990 almost nobody even had a firewall to speak of. < \\BODY >",
"A web hosting service is someone else running a web server on a computer. Before they existed you had to runt it on a computer you owned. But they have existed for a long time. GeoCities is likely the first well known and it was launched in 1994",
"All things like Wordpress do is help automate the creation of the code for your website. A webpage is still an html document at the end of the day - if you want to see it, most browsers have the ability to \"view source\" in the developer tools. That source is the actual html code of the page. Back in the day, we just coded the html by hand. We'd type it in a program like notepad, save it as an .html file, and upload it to the correct directory of a webserver.",
"Your computer is on the internet, if you know what to do you can relatively easily set up your own computer as a basic web server that you can connect to and browse a small website All a hosting service is is just someone else’s computer, they also have other services to help you and make it easier to use, but at their heart, there is just a computer connected to the internet, nothing you can’t do yourself with your own hardware at home",
"> before those existed how did people code websites HTML, CSS, Javascript: Much like most of them still do. Wordpress, squarespace, Wix, and the likes are neat for people with little time, resources, or coding experience, but most websites made by bigger companies won't use them because they can be quite limiting if you want to do anything other than make a blog, a snazzy landing page, or a standard webshop. While the technologies of course have changed and have gotten a lot more convenient and advanced you can still open up notepad, write some HTML in there, CSS to style it, and Javascript to make it do more complicated functionality, and any browser will just run that out of the gate no questions asked. You can then set up a basic webserver that can serve that file straight from your own computer. While writing websites in straight HTML without any other supporting frameworks is pretty slow it's perfectly doable and was more or less how it was done for decades. At the end of the day that's still what all websites run on: A combination of HTML, CSS, and Javascript. If you right click on any website and select \"inspect element\" you'll see it: the html that's describing the website you're on.",
"You're conflating two separate things: how did people *create* websites and how did people *host* them. \"WordPress\" does a bit of both so I guess that's why you're confused. WordPress is the PHP-based software (Content Management System) which generates the website, URL_0 is the web hosting service that will host a WordPress website for you. Creating websites is easy. HTML, CSS and JavaScript scripting/markup languages are the basic requirements to build a site on the World Wide Web. They have been for about 25 years and haven't fundamentally changed that much since then. These are all just plain text files that any web browser can render. You can use Notepad to make them if you want. Sure these days people have fancy source code editors and frameworks that do most of the groundwork of creating a new website, or content management systems which have all the code and the user just adds the content, or website builders that use templates or drag-and-drop interfaces to add features. But you're still getting the same code in the end. Databases and programming languages (like PHP, Java, C) have existed for just as long or much longer, and were easily integrated into the web development stack to create more dynamic websites. As for hosting, well a web hosting service is just a third-party company that will run the servers that your website is hosted from. They've existed basically as long as the public World Wide Web has. So there wasn't really a time without them. But if you're not paying somebody else to host your website, you would need to host the site yourself. That means running a computer as a server, with the required software to host your site. That's still a viable option today if you just want to host a small personal website for yourself from an old desktop PC, or if you're a big company with the resources to manage your own infrastructure."
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nf5fea | Why do Windows' diagnostic procedures never work? | Technology | explainlikeimfive | {
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"These programs look for some of the most common types of problems and attempt the common solutions for them. Unfortunately most people don't have these problems, they have other less common problems. Also the known common problems tend to become less common as developers become aware of them so these programs are even less useful. Occasionally they do end up solving a problem though. I am honestly surprised when they do, but it happens.",
"Funnily enough I have found exactly one windows diagnosis that worked. At work people kept getting booted off of the wifi. I used windows diagnosis as a last resort because I was so frustrated, and it updated some settings and everything worked immediately."
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nf5s6d | How does a phone restart? What part makes it turn on by itself? | Technology | explainlikeimfive | {
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"It's never fully off. It can almost completely turn off, but it doesn't go all the way. Take a look at the power button. It's not like your light switch on your wall that physically disconnects the wires. With this type of switch, the wires are always connected, and when the phone is \"off\", it's still on enough to monitor if the power button has been pressed. It's also why when your phone is \"on\", pressing the power button doesn't instantly cut power to your phone.",
"One of the computer chips in a phone is the power management IC (PMIC). The PMIC turns devices on and off, regulates voltages, keeps an eye on the battery, and usually handles reset. The main processor can tell the PMIC, \"restart me\" or \"power off\". The PMIC handles turning power off, monitoring standby devices, resetting and restarting. If the battery is too discharged, the PMIC stops too. When the battery is charged a little, the PMIC is the first chip to be energized and can delay power on until the battery has enough energy to boot the main processor."
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nf6iy8 | - How do companies make money when we waste our time on their apps/websites? | I recently watched a documentary on how social media sites try to keep you on the platform and try to lure you in when you are not on the platform. How exactly do they make money when we waste our time on these platforms? These days it might have something to do with ads (which I still don't entirely understand) but what about before the ad era? When these platforms first took off, how did they make money when we don't actually pay anything to use these platforms other than our time? | Technology | explainlikeimfive | {
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"Before the ad era there was no social media. Its realy only advertising or selling advertising spots on the website to others to be more precise. Facebook knows alot about you, like where you live, your relationship status and your education. This is why they offer the best quality to any company who wants to advertise. Only facebook is able to display the advertising for a fertility clinic to young woman who are in a relatonship since a minimum amount of time. Thats why advertising on facebook or other social media is so much more worth compared to a street sign. And facebook does do just that: selling space on your devices screen in real time based on what facebook knows about you.",
"Targeted advertising. Go back to the days of newspapers, and you would spend money to put out an ad. Let's say it cost $100, and you knew that 1,000 people bought the newspaper. You were paying $0.10 per impression. However, if you had a very narrow focused ad that only really mattered to 50 people, you're wasting 950 impressions. Your cost per effective impression is $2.00. But what if you could deliver your ad to only the 50 people that you want? Would you pay $50 for those 50 ads? It's less than your $100 otherwise, and you don't really care if you don't get those 950 worthless ad impressions. This is a win for you. but it's also a win for the newspaper. They still have 950 prints to sell a different advertisement on. If it's $1 per ad, they can make $1,000 from that ad slot instead of the $100 you originally paid. This is how these websites make so much money. They have collected so much information on you that they can sell focused advertisements. Focused advertisements cost so much more than regular advertisements. Rather than ads help reduce the cost of a website like they did in the '90s and early '00s, they're a considerable source of income these days.",
"Everything you do on social media is tracked. That data is sold to companies for targeted adds. Didn't click anything and just looked at a post? They tracked how long you looked. Even just talking around your phone can bring up suggested adds. We live in 1984 already. Get comfy."
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nf7nt1 | How are wildlife video's shot that too in ultra high HD? How does a cameraman or a drone get close to animals without startling them. How do they film an exact moment of an event happening like a mating dance or a fight between animals | Technology | explainlikeimfive | {
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"Firstly: It takes *months*. Secondly: Unless the camera man is following a particular pack, most documentaries with cut together footage of different animals and \"tell the story\" of one very interesting one.",
"> How are wildlife video's shot that too in ultra high HD? You bring ultra high HD equipment > How does a cameraman or a drone get close to animals without startling them. You don't get close. You use really powerful lenses, like 15 thousand dollar ones. Source: URL_0 lens: URL_1 picture of the lens: URL_2 You also don't get close to them. You pick a spot, get some camo, stay there for a while without shower (so your soap smell won't startle the animals), and then wait until the animals get close to you. That will take a long-long time. That's why you have to be smart about it, and pick up strategic locations where you suspect that animals might pass by. > How do they film an exact moment of an event happening like a mating dance or a fight between animals You film the entire time. For hours and hours. And once a while, you get lucky.",
"There's lots of little and big tricks that the Nature Doc guys use. If you watch the end of any of the more recent David Attenborough programs like Blue Planet II they show you some behind the scenes stuff. But your main answer is lots of patience and HUGE lenses on the cameras. You're talking between 400mm to 800mm and these lenses can weigh up to 10 lbs. You can get a lot of shots done if you stick to watering hole times at predawn / dusk. If you're a decent distance away with a large lens you have about half an hour of intense activity just before sunrise and the best light as well. They have started using drones but their use is limited because animals do react to the drones - so you're talking pretty heavy duty drones with again quite significant lenses on staying at a decent distance away."
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"https://i.ytimg.com/vi/iRUJwtVLrnc/maxresdefault.jpg"
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nfbkmu | How are several lower quality photos of the same object use to make a high resolution composite picture? | Technology | explainlikeimfive | {
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"With cameras it’s all about the amount of information you can give them to work with. Having several images allows the cameras processor to stack them and use data from all of them to make filling in “missing” data (areas with less detail) more accurate than with just a single image.",
"This uses the fact that your different low resolution images are slightly misaligned. Images are composed of pixel and each pixel will show basically the average colour of what was there. Now let say you are taking a picture of a black line on a white background, and the line is half a pixel width. You pixel will be grey. But if you have another image and you able to tell this picture is half a pixel upward. Now you have information on the same area but half a pixel shifted. And when looking at this new picture, you notice that the pixel that covers the upper half of the old grey pixel is white. Now you know that on the grey pixel, all the grey you have seen is actually due to the lower half. It is roughly the same principle you apply with a bit more complex mathematical formulas. There is nothing magic though: if you want to double your resolution, meaning multiply the number of pixels by 4, you will need at least 4 images. And because they won't be perfectly misaligned, you would need actually more. You also have other techniques of Super-Resolution that do not do mathematically correct operations, but rather guess the content. Much like when you seen a low resolution image of a face, you can imagine what the eyes will look like. It won't be perfectly accurate but in some applications will be good enough."
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nffqu5 | Resampling (in audio) | Technology | explainlikeimfive | {
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"Digital audio is stored and reproduced as a list of numbers which tell the speaker how to move. Each one of these numbers is called a \"sample\", because a device is \"sampling\" the voltage from the audio signal wire periodically. In CD-quality recordings, a voltage is sampled and stored 44100 times per second. Some audio devices offer something called \"resampling\". This can mean a few different things depending on context. Often it means changing the sampling rate to something else. If I wanted to reduce my data storage requirements, or get a more gritty, degraded sound, I could resample that 44100-samples-per-second signal down to 22050-per-second, by simply throwing away every second sample. Or, if I wanted a slightly smoother result, Instead of simply discarding every other sample, I could *average* the samples in pairs. Either way, we end up with half as many samples as before. So this is one kind of resampling: Changing the sample rate of a piece of digitized audio. It's analogous to changing the resolution of an image file. Another kind of resampling, is a function in some digital musical instruments, commonly called samplers. In those instruments, you can record and play back little clips of digitally sampled audio, sometimes by triggering them with pads or a keyboard. In these devices, \"resampling\" means that the device can listen to its own output, and record *that* into a digitally-sampled clip. So you might sample some piano chords from one source, and some drum beats from another source, and mix them together in your sampler... and then when you're happy with the mix, you can resample it so that you now have a piece of recorded audio which is the drums *and* the piano together in one sound file. And then you can manipulate that recording just like you did with the other recordings. So in the context of a musical sampling instrument, \"resample\" means \"re-record your own output so it can be further manipulated.\" In the context of a simple recording, \"resample\" means \"change the quality/resolution\""
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nfhvme | How Does Radio & Royalties Work? | I have no idea how radio works. Do they pay a royalty every time they play a song? How much is a typical royalty for a popular pop song? Who decided what the royalty will be? How do they (the artist or their managers) keep track of how much each radio station in the world owes them? | Technology | explainlikeimfive | {
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"You're confusing royalties and licensing fees. There are several companies that do broadcast licensing for music. A radio station pays one or more of those companies for the rights to broadcast some or all of the music by the artists that company represents. The licensing company then pays some agreed upon amount to the record company (or the artist directly, if they're independent). The record company then pays royalties to all of the musicians/producers/etc. that are entitled to them via their contracts."
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nfl3xc | How does a country know if a plane flying over it's airspace is civilian or military & more importantly how do they know if a military plane using the airspace is friendly or not? | Technology | explainlikeimfive | {
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"Civil aircraft file flight plans with air traffic control and have transponders to identify themselves. Military aircraft have an extra transponder called an IFF (Identification Friend or Foe) that civil aircraft don’t. So if it’s transmitting IFF it’s definitely military. The reverse isn’t true…a military aircraft can turn IFF off and “look like” a civil aircraft if they stick to the same flight path (altitude & speed). If it’s transmitting nothing it’s also obviously military (or a no-radio civilian, which is rare). The only way to know for sure is visual inspection…if a country is suspicious, they will dispatch fighters to go look and see what it really is. In an actual war, this is a fairly common thing. In peacetime, most countries play nice because if you try to sneak a military aircraft in as a civil aircraft, that country is quite likely to bar *all* your aircraft from their airspace. And spark a diplomatic incident. So, outside active conflict, it’s best for everyone to have all aircraft report what they really are.",
"Planes that enter a nation’s airspace must respond to radio contact from that nation’s air traffic control. If they’re unable or unwilling to provide identification and flight plans, they may be intercepted by the local air force. Developed nations have extensive radar networks that constantly track all air traffic. Any incoming aircraft that’s refusing to identify itself would be picked up on radar quickly and ordered to land. Refuse all radio commands and angry gestures from intercepting fighter pilots and you may be shot down."
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nfq8p4 | How does a VHS/DVD that was once 480 or 720p become 1080p, and why aren't all old releases available in higher resolution or better quality? | Technology | explainlikeimfive | {
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"The classic case to look at is the remastered Star Trek The Next Generation. The principal photography (real life actors on sets) is fine for HD because it was recorded with a 35mm camera which looks great in 1080p and would even look great in 4k. The problem with TNG was all the special effects (ships, planets, consoles, phasers, etc.) were recorded at a resolution which was fine for TV at the time but looks like crap at higher resolutions. Nobody at the time realized how much resolution would improve in the next 20 years. So virtually every single special effects shot had to be redone which is time consuming and very expensive.",
"If something was filmed on a real camera, like what was used for movie production, it actually has an extremely high resolution, because film doesn't need processing power or special chips to record ultra high def images. So they used to take that super high resolution and scale it down to 480p or 720p to be stored on VHS or DVD. To re-release something in high def, they take the original camera film and work from that. If the owner doesn't want it re-released, it doesn't happen. If the special effects look like shit in higher resolutions, they might choose not to release it. If the original film is lost or damaged (fuck you George Lucas) then you can't do anything with it.",
"Actual physical film often produced very high-resolution images, higher resolution than the digital scanners of the time could reproduce. Now our digital scanners are better, so they can re-scan old film at a higher resolution than they did before. As for why they don't always go back and re-scan: sometimes there's just not the demand for it, and re-scanning and re-releasing the new version is an expensive process. Also, if there's digital effects, the film might not have them, or would be a low-resolution copy of the shot film with the effects added; either way you'd have to redo a lot of those effects from scratch to get them in the update.",
"If it's a straight VHS or DVD rip then it's a lot of attention to detail from fans of that movie/show to fill in the blanks detail wise and improve image quality. If it's something that was once released on VHS or DVD but was recorded in a studio environment then remasters may re-scan the source film, and since film is high resolution(in it's own way but that's a topic for a different comment) it can be 1080p or even 4K, but anything done in editing has to be recreated digitally."
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nftboi | How do the little name keychains work. there isn’t a battery i need to change and it always lights up. Flashes my name at me and i’ve always wondered how it works | Technology | explainlikeimfive | {
"a_id": [
"gyneppn",
"gynjzq8"
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"text": [
"There's a battery. You just can't access it or see it. The lights take little enough energy to last a long time without changing the battery. Eventually it will die.",
"Looking for similar products online, I believe they are solar powered. Not sure where the panel is. URL_0"
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"https://www.amazon.ca/Dimension-Personalized-Solar-Flashing-Keychain/dp/B00NYCE0CA?th=1"
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nfu0mb | why are TVs not the same dimensions as movies? | Technology | explainlikeimfive | {
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"text": [
"Filmmakers can choose the ratio they want their movie to be shot in. This means that you might sometimes have a movie that doesn't perfectly fit your TV screen. For example, Stanley Kubrick's _Full Metal Jacket_ is shot in 1.375 : 1, which Kubrick chose to do since that was a common aspect ratio for TV screens in the 60s and 70s. This would help immerse the viewer in the movie, giving them the feeling that they're watching the Vietnam War unfold before their eyes in a similar way to those who watched it on the news during the 60s and 70s. 1.375 : 1 is known as the \"Academy Ratio\". As you probably know, the shapes of TVs have changed quite a lot since the 70s, hence the particular ratio he chose will likely not fit many TVs nowadays. However, a more common film ratio is 2.4 : 1, known as \"ultra widescreen\". This more resembles what you see on your TV and in theaters with most movies. However, if you're watching an ordinary TV show or broadcast, it will likely be in 16 : 9, the most common ratio. To summarize, film ratio is all about the filmmaker's choice. It provides a massive stake in helping immerse the viewer in their film, based purely on what it feels like to watch that ratio.",
"Do you mean older 4:3 TVs? Because that was the standard for broadcast television for decades. Most if not all new TVs are 16:9 which is widescreen and what most shows and movies are shown in. Some movies, for example Blade Runner, are 2:39 : 1 which is super widescreen."
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ng3m17 | How did authorities enforce speed limits before the invention of radar? | Technology | explainlikeimfive | {
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"Distance over time. If it takes 10 seconds to travel from point A to point B while traveling the speed limit, and a vehicle goes that distance in less time, they're speeding. If the distance is known, the speed can be calculated based on the time, or you can pre calculate a few common overages, like 5 over would take 7.3s etc.",
"Typically it was eyeball whoa he’s going way too fast or painted lines and a stop watch. There is a B & W Andy Griffith show where Andy & Barney pull over a woman. “Andy and the Woman Speeder”",
"A very common technique is to use a stop watch and measure how long a vehicle takes to travel a measured distance. This is still very common as it allows measurements to be taken from far away and from the side. So the police might hide on the other side of the valley from the road or in an airplane and still take accurate speed measurements. Even speed cameras can do this either by measuring the time the vehicle takes to trigger two sensors on the road or even how long the car takes to pass between two speed cameras along the same road. This is also a technique which is safe from radar detectors and radar jammers.",
"There is also the pacing method. By matching the your car from a consistent distance and observe the reading from the police car’s own speedometer.",
"Pacing - Just follow at the same speed and read your speedometer. VASCAR - Invented in 1966, it used time, distance, and speed inputs to compute the target's speed. There are several modes. If there are markers of known distance, you just input that and use the stopwatch function. Can be done from car or aircraft. Or, say you spot an oncoming car speeding. As they pass a landmark (sign, tree, etc) you hit one toggle. As they come directly opposite you, you hit another toggle. And as you reach the landmark, you hit it again. It reads the distance you just drove, and knows the time the car took to traverse said distance. Then computes the speed."
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ng5gri | How do computers work at its most basic level? How did we take physical objects, put them together, and have it so when we press a button, a portion of our screen lights up? And how did we turn this into a code that can be used to make other software? | Technology | explainlikeimfive | {
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"You know how you can use a switch to turn the lights on or off? The switch sits on an electrical circuit and can break it, preventing electricity flow and turning the lights off, or reconnect it, restoring the electricity flow and turning the lights on. Now If you put two switches together on the same circuit, then it will only work (lights on) if both switches are turned on. This is an “AND” gate. If the two switches are connected in parallel, then the lights would be on whenever either of the switches is turned on. This is an “OR” gate. The computer chip is basically millions upon millions of such microscopic switches and gates on tiny circuits.",
"First, the \"theory\" of a computer came well before our ability to physically implement it. Basically, logicians several centuries ago, came up with a way to treat logical statements (statements that can be true or false) as a kind of math, coming up with the field today known as Boolean Algebra. Instead of mathematical operations like ADD and MULTIPLY, we had logical operations like AND and OR. Let's say we have two logical statements we call A and B. Doesn't matter what they are exactly, except that they can either be true or false. I can combine them together with the logical operation AND to make a new statement: A AND B. This new statement is only true if both A and B are true at the same time, and is false if either of them or both of them are false. OR is true if either of its components are true and is only false if they are both false. We also have a third operator called NOT, which basically just inverts a statement. It makes a true statement false and a false statement true. With these we can create more complex operators like NAND, NOR, XOR, XNOR. Turns out, if we treat \"True\" as \"1\" and \"False\" as \"0\" we can make these logical operators behave like mathematical operators (Add, Multiply, etc.) but only in binary (a number system that only uses 1's and 0's). So if we can find a way to implement logical operators with physical components, we can create a machine that can do math. Eventually we were able to do this, first using vacuum tubes and then subsequently with transistors. We can create those basic logical operators, then combine them in ways to do mathematical (and other) operations. We can also feed them back onto themselves to create electronic circuits that can \"store\" values (as long as they are powered), creating memory. With all of these, we have a very basic computer. Basically all it is, is a series of logical operators, implemented with transistors, that take input (in the form of electrical voltages) and produces specific outputs (again, in the form of electrical voltages). All modern day code does is allow us to program computers using easily intelligible programming languages. Other programs called compilers and assemblers take that code and covert it into the machine language that computers understand at this basic level."
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ng74js | how does drag and drop from desktop to browser work? | It's crazy that I can select an icon on my desktop, drag it to the browser window, release the mouse button and the browser will know which file the icon referred to. How is this implemented? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Not sure this is at a 5yo level but: Your desktop is just a graphical rendition of a file explorer. When you click and drag an icon it loads a file address into a 'clip board' within the operating system (OS) and when you drop it somewhere it pastes it into the location you dropped it. So, when you drop it into the browser your OS interfaces with the browser program and pastes it where ever you drop it within that program. Edit: It's basically a graphical shortcut to telling the browser to upload a file from the desktop through a file explorer interface.",
"The operating system has an Application Programming Interface (API). It's a way the programs and operating system can interact with each other. Using this interface, the program listens for events from the operating system (key press, mouse move, mouse click, etc). One of those events is the \"drag and drop\" event. The Operating System basically tells the program, \"Hey, I'm dragging and dropping this particular file into your window, do what you want with it\"."
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ngiqoj | Why a piece of microfiber cloth cleans a wet surface better when it is already wet than when it is dry. | Technology | explainlikeimfive | {
"a_id": [
"gyrj8c1"
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"text": [
"Water sticks to water! It's why droplets form - each water molecule is sticking to the next. If you wipe up a mess with a damp rag, the water molecules in the mess stick to the water molecules in the rag."
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ngje3r | Why do companies continue to install bloatware on devices? | Technology | explainlikeimfive | {
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"text": [
"Because while *some* people complain overall people still buy it. People complain about microtransactions in games all the time but *a lot* of people still buy the games and buy the microtransactions so why would the company take them out. Financially, it doesn't make sense. Bloatware is similar in that people complain but it doesn't stop them buying it and forgetting about it. Some people may even enjoy it."
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ngn75i | why are catalytic converters so valuable and worth stealing? | Is there a black market for them? Why do cars need them? Can we protect them, somehow? Thanks! | Technology | explainlikeimfive | {
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"They have a small amount of various precious metals. This makes them expensive. Factory cats can cost a few grand so thieves steal them and sell them for less than oem but at quite a good price. Scrap recyclers will usually pay 100 or so for each one because they can refine the metal if needed. Most of the scrap places, around me atleast, don't bother refining them and instead sell them to junkyards or various places online.",
"They're an easy part to steal, since it's on the outside of the car and you can sawzall one off pretty quickly. They're an expensive part, because they have small amounts of very expensive metals, which convert some of the more harmful exhaust products into less harmful ones. Cars don't need them to run, but they do need them to meet emissions requirements. And short of mounting some sort of shroud over the entire exhaust system, which would add cost and complexity to the car, there's not a whole lot you can do to protect them. Hence, worth stealing and easy to steal."
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nh0e1w | Why does using Mobile Data in smartphones consume more battery than using WiFi? | Technology | explainlikeimfive | {
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"text": [
"Mobile data must transmit/receive data through cellular towers, which may be quite a distance away (a few miles, or even farther). WiFi service, provided by a WiFi hotspot/router, are usually much closer, within 10-100 feet. It takes more energy for the phone to send signals to the distant tower than to the nearby WiFi router.",
"Say you're in the countryside and you see your friend a couple of fields over. You want to talk to them. You could either shout the message directly, or give them a call on their phone. Which is easier? Mobile data is like shouting. Your phone can do it, but it's \"talking\" to the internet via a tower that could be far away. Wi-Fi is like calling your friend. Your device is talking to the nearby router and letting that carry the signal to the internet, so your phone doesn't need to \"shout\" as loud."
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nh3b66 | How do bots work? | And I don't mean like spam bots. I searched this sub and couldn't find much. For example, I see people tagging u/ savevideo or u/ savephoto, and just saw one "shakespeare bot" that repeated a comment but in "shakespeare language." Are these real people? Im assuming not, but on the video one I think, I saw the "user" post they got banned. So I'm a bit confused? ELI5 I'm fairly new here | Technology | explainlikeimfive | {
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"A bot is just a program running on a computer somewhere--it could be a server in the cloud, a desktop/laptop, or I suppose you could even do it on a smartphone if you were so inclined. Reddit has the \"normal\" interface where you go to URL_0 and you see the posts and comments laid out on the page, but it also has a computer-readable format that just packs the data in nice easily digested chunks. 3rd party Reddit apps tend to consume that interface and apply their own formatting. A bot will also use that interface and check for whatever trigger the programmer sets it to. Sometimes that means checking every comment looking for certain phrases (e.g. the ubiquitous grammar correcting bots that are quickly banned because they're stupid and add nothing to the conversation). Many will periodically check for username mentions, then jump to whatever comment mentioned their name. Once the program has detected its trigger it does whatever it was programmed to do. Simple bots may just reply with a canned message. Marginally more complex would be doing a find-replace, a unit conversion, or looking up a keyword in a database (this is common on competitive card game subreddits like /r/mtg where bots are made to facilitate calling out a card by name, then the bot will look up a link to that card and post some relevant information from it). The sky is the limit here--a bot could take in an image of a chess board and tell you the best next move, or take in an entire news article and run it through a pile of AI to spit out a summarized version of the article. When that processing is done the program then usually posts a comment. Technically the bot can interact with reddit in any way a human can, but certain interactions are bannable (e.g. posting the same link all over the place, upvoting/downvoting).",
"Reddit has an API (Application Programming Interface) which is basically just a web page meant for software to read and interact with, rather than a human. In Reddit's case, it's a series of pages where a program can read comments or other information, then post their own comments, without having to deal with the fluff of the visual aspects. In the Shakespeare bot's case, it's basically asking Reddit every few seconds for \"all the posts in a specific set of subreddits,\" which reddit gives it. The program, which is running on its creator's computer, then does some processing to figure out which comments it wants to reply to and what it will say, and then uses the same API to reply directly to the original comment. However, in order to do this, the bot itself needs its own account, with its own credentials (username & password). The bot sends this information along with the contents of its post so that Reddit knows what username to associate with the bot. This also gives Reddit the power to ban a bot as if it were a human, because to Reddit's servers, they're basically the same thing.",
"Those bots either search all of Reddit (with some subreddit exceptions) for their summon word (or sometimes on specific comments like haiku bot which looks for words with specific syllable combinations) or wait to be summoned by being tagged. Then when that happens they run code to do their thing, like for Shakespeare language it replaces words based on context, and save video generates a link to where you can download Reddit videos."
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nhd7q7 | Why is Internet Explorer still around, what kind of applications or businesses still use it? | Pretty much the title | Technology | explainlikeimfive | {
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"For example I worked in a company that used some house developed software for the product database, and that only really worked in explorer, redeveloping the software would be expensive and licensing a third party software would also be very expensive, basically if it ain’t broke don’t fix it",
"IE was around for long enough, and for a long time was the only browser with really solid enterprise support, that a ton of early corporate web applications were written for it and used custom IE functions that aren't present in any other browser. I used to work somewhere that the entire CRM software was a highly customized version of Siebel and it only worked on IE. You don't just roll your entire CRM suite without being \\*really\\* sure it will work, and the business case to roll it is always terrible...it's always cheaper to keep IE than to rewrite the software. Eventually you get forced into it when Microsoft sunsets it, but you hold out as long as possible. For mission critical applications you're way more concerned about stability that \"latest technology\". IE has been really stable for a really long time.",
"The company where I work does CAD drawings using an obsolete program called CADKey. To look at these drawings, we use a program called Autovue, that for some, reason doesn’t seem to work with modern browsers. Internet Explorer is the only one. We use IE to quickly look through these CADKey files. That being said, our IT dept is looking into ways to do this without IE right now..."
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nhionx | How is it possible for a vinyl record to perfectly reproduce the sound of a musical instrument just by rubbing grooves in it? | Technology | explainlikeimfive | {
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"Because sound is waves and the grooves are miniature versions of those waves that get amplified back to the real sound. It’s literally that simple."
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nhjwrv | How do apps like Google translate, or Google maps monetize themselves? | Technology | explainlikeimfive | {
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"Google makes most of its money through advertising but not every service has them. Some products like translate are offered for free as a way to entice users to join the Google ecosystem where they can be served ads and/or to collect data which can be used to target advertising.",
"Google gets a lot of data from less-monetized apps (some of these have monetization, just not for the end user like someone performing a search) to feed into or improve their monetized ones. It’s not so much a separate, non-profitable app and more a part of an ecosystem where they have highly profitable apps. They can also sell parts of the information they worked to develop to third parties like satellite imaging. Google earth has an image subscription you can buy which is part of their practice of selling access to their APIs to developers. Businesses also license google to use maps professionally. I’m pretty sure a lot of translation tech is also licensed to third parties and sometimes used in machine learning to improve other app/future ventures which feeds the whole ecosystem. They also sell the the government. URL_0",
"they don't. They don't have to. google can offer some stuff for free with no obvious monetization because google makes so much money off of other services. The more people use google maps, the more people use google search, which they do monetize (by filling it to the brim with ads)",
"Many of Google maps features are APIs that developers have to pay a subscription to use. The user can use everything for free, but developers who incorporate these features to their websites/app actually pay money to be able to provide them to their users."
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nhlhri | How does a logic diagram work to add numbers in a computer? | Technology | explainlikeimfive | {
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"Numbers are represented in a binary form in a computer, meaning that every digit in a number can only ever be either 0 or 1. Zeroes and ones are held equivalent to False and True correspondingly. And you can work with False and True using logic. For example, if you need to add two whole numbers, then you start from their last digits. Applying the XOR logical operation to them gives you the last digit of the sum (0 xor 0 = 0, 0 xor 1 = 1, 1 xor 0 = 1, 1 xor 1 = 0). Applying in parallel to them the AND logical operation will give you the carryover to the next digit (1 and 1 = 1; equals 0 in all the other cases). Putting the necessary amount of XOR and AND gates in a sort of a chain for carryovers will let you calculate the sum of any numbers up to a certain size."
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nhlq6c | Why Microsoft shutting down Ms Explorer, instead of re-naming Ms Edge | Technology | explainlikeimfive | {
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"Assuming you're talking about the Internet Explorer - it simply is a completely different program from Edge and is being deprecated. I suppose \"Internet Explorer\" has some brand recognition that could be otherwise utilized, but since that brand recognition is mostly **negative** it makes sense to not just rename the different (better) product. It would end up being confusing anyway - why would you rename Twix to Snickers, just because you decided to no longer produce Snickers?",
"Explorer isn't Edge, Edge is Edge. It would be very confusing to rename an old product to the current name of a new one, as they would presumably need to rename Edge to something else (and have everyone think Explorer was Edge), or have ambiguity about what program anyone was talking about. Another benefit of them producing a new program with a new name is that people will readily understand it is different. Explorer is certainly a well known name but it isn't recognized by all as a *good* program to say the least. Microsoft doesn't so much need to worry about their ability to get the name out into public recognition, so shedding a checkered history is likely more valuable.",
"Rebranding. Explorer had so many ups and downs in its history that the brand name is blurred. That is, you say \"MS Explorer\" to people, and you don't know what their internal reaction will be because you don't know what history they may have had with it."
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nhtfww | what is the difference between LED, LCD, OLED, QLED, and plasma? | Recently saw a comment stating some difference between OLED and LCD. Just wondering what the differences are in the rest of the major TV types | Technology | explainlikeimfive | {
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"A lot of it is deliberately misleading branding from manufacturers, there are really only 2 main TV technologies right now (LCD & OLED) * **LCD: Liquid crystal display**. The same technology used for the display in digital watches and alarm clocks, but miniaturised to the point where they can make up the pixels of a screen. The pixels don't produce their own light so they need a backlight. Old LCDs used CCFL backlights (flat fluorescent lamps) but since about 2010 they have used LED backlights. To market the newer backlight technology manufacturers commonly call these \"**LED TV**s\", even though they are just LCDs with a better backlight. **QLED** is Samsung branding for LCD TVs that have 'quantum dot' films inside them, it's a layer between the backlight and LCD layer that enables the tv to produce more colours with higher brightness. A problem with LCD is that when watching dark scenes some of the light from the backlight still bleeds through, making blacks look grey (especially at high brightness settings). Local dimming is a technology where the backlight is divided into sections that can individually be made lighter or darker, allowing an LCD screen to look better in dark scenes, **Mini LED** is the term for a perfect version of this local dimming technology where every pixel has it's own individual backlight, this is the newest LCD technology branding you will start seeing in 2021 TVs, but it's still LCD at it's core. * **OLED: Organic Light Emitting Diodes**. This is a totally different technology to LCD, the pixels themselves produce their own light so there's no backlight. This means there's no backlight bleeding through during dark scenes allowing inky blacks and amazing contrast. Also because there's no extra layers needed for the backlight, quantum dot layer, etc OLED TVs can be extremely thin. The downsides of OLED is that the pixels break down over time and static images can get burned in, also they tend not to be as bright as LCD screens. That said companies have been improving the technology every year making these problems less and less prevalent. * **Plasma** screens were an older technology which worked by having thousands of pockets of a gas that would turn into plasma and produce light when an electric field was put across them. It offered many of the same benefits as OLED since each pixel made it's own light, but it was costly to manufacture compared to LCD TVs, and then OLED came along offering all of the same picture quality benefits and made it truly obsolete. There is a new upcoming TV technology called 'Micro LED', which is a TV made up of millions of tiny LED lights. It has the same benefits as OLED but with the increased brightness and longevity of LCD TVs, so it's like a best of both.",
"LCD is any display that uses liquid crystals to display an image, that's basically the next step after CRT's. Those liquid crystals can display colour, but no light on their own, so you need a light source. On never displays that's always done by using LED's, that's why those displays are often called LED-screens. They still use LCD's though. OLED is again the next step, by using organic liquid crystals who have the ability to emmit light on their own, so you don't need additional LED's and have a better picture with far more contrast. QLED-screen are basically still using \"normal LCD's\", but rather special LED's for the backround light. Those aren't white, but can take on every colour, which means that the colours on the screen are also better. You don't have the same superb contrast OLED's have though. Plasma-TV arent using liquid crytals as pixels, but basically small chambers filled with gas. There are three chambers for each pixel, containing different gas for displaying either blue, green or red. By connecting an electric current to them you're turning them into plasma and thus visible light.",
"Woohoo, I get to bust out [my 9-year-old response]( URL_0 ) to this question again! That response covers LCD, LED and Plasma. The other two you mentioned are QLED and OLED. * **QLED** is essentially the same as LED, but a special \"quantum dot\" color filter is added to the screen that greatly expands the color space that the TV is capable of displaying. The Q stands for \"quantum\", referring to the quantum dot filter. * **OLED** is a completely different technology. It stands for *Organic Light Emitting Diode*. How exactly it works is a little beyond the scope of an ELI5, but the key thing to understand is that it is an *emissive* panel rather than a *transmissive* one. In an *emissive* panel, each pixel is responsible for generating its own light. The advantage of this is that black pixels literally emit no light whatsoever, resulting in absolutely inky-black black levels that OLED is famous for. Plasma is also an emissive panel display technology, and it also had amazing inky blacks. The disadvantage of emissive panels is that each pixel will wear out at different rates from surrounding pixels depending on how hard those pixels are being used; as the pixel wears out, its light output diminishes. When you have uneven wear rates across the panel, with some pixels noticeably darker than others, that is what's known as burn-in. In a *transmissive* panel, there is an independent light source behind the panel called a *backlight*. The light form the backlight passes through the panel, and each pixel is designed to filter the light to generate the color it needs to be. All of these panels rely on LCD (liquid crystal display) technology for the pixels, but the backlight technology has changed greatly over the years, first using fluorescent lightbulbs, then moving to LED lights. What we call \"LED\", \"QLED\", \"xLED\", etc. are all variations of this theme. The advantage of transmissive panels is that individual pixels are not going to wear out, so you won't get the phenomenon known as burn-in. But that isn't to say the *TV* won't wear out, it's just that it's more likely that the *backlight* will wear out first before the pixels do. The disadvantage of transmissive panels is that the pixels can never really filter 100% of the light coming through the panel, so it is extremely difficult to get the inky-black black levels that you get with OLED. Manufacturers solve this problem by using *full array local dimming* whereby the backlight is divided into sections that can be controlled independently; if an area of the picture is dark, that section of the backlight can be dimmed or turned off resulting in better black levels in that area of the screen. The problem with this is that each backlight section is fairly large compared to the size of the pixels, so you can't control the brightness of each pixel as precisely as you can with OLED. Some manufacturers solve this by literally making the backlight into its own black and white LED panel, with as many \"sections\" are there are pixels in 1080p. And then there's Micro LED. This doesn't use OLEDs, it uses normal LEDs--the same as you would find in a LED lightbulb or traffic light--that have been shrunk down small enough to serve as individual pixels for a TV (hence the \"micro\" part). There's a limit to how small they can be shrunk however, so Micro LED TVs are typically massive, upwards of 100\" diagonal. It's an emissive panel, but the pixels don't wear down the same way OLED pixels do, so there's no threat of burn-in. I hope this helped!",
"Still rocking my Panasonic Viera ZT60. The pinnacle of both Panasonic and Pioneer's R & D on Plasma. It is truly a sight to see.",
"Well, if you are really five, I'll just say that OLED looks better but you are not allowed to use it to watch cartoons.",
"Liquid crystals respond to a charge to align into a polarizing filter. So you apply a charge, the element becomes a polarizing filter, and only allows light of a particular polarity through. Without the charge, the liquid crystal passively sits with a polarity that goes 90º. Line up a polarizing filter with another polarizing filter arranged to only let through light that's 90º polarized from the other, and the two filters will work together to block almost all light. So you can use a liquid crystal lattice, lined up perpendicular to a passive polarizing filter, with a regular polarizing filter to selectively let light through. Or In effect, each piece of liquid crystal is like a curtain you can open or close to let light through or not. An LCD display then is lit from behind with white light. For a black and white LCD display (fairly rare these days), imagine an grid of windows, each with a curtain either open and closed to let light through. You can electronically control each curtain, so that a picture can be seen in the windows, as viewed from very far away. Note that in order for you to be able to see anything, you still need light behind the windows/curtains. Each window/curtain is a pixel, and there is technology for letting in partial amounts of light through. So it can go from black to gray to white. The brightness of the darkest black compared to the brightest white is sometimes known as the \"contrast ratio,\" which helps describe just how much contrast the display can produce. For a color display, each window/curtain is actually a subpixel, that only lets through either red, green, or blue light. Just put some red, green, or blue film on the windows, and your window/curtain combination can start implementing color displays - block all blue, and the red and green will appear yellow. Block all green and blue, and half of the red, and it will appear to be a dark red. So LCD always needs to be backlit. The windows themselves don't create light, so you need some other light source behind the windows. It's much cheaper and easier to use one big light behind all the windows, than it is to put a different light in each window. LED backlit LCDs are better in many ways than some of the older technologies, because LED backlight is more even and more power efficient (which can make the whole display brighter). But there are LED technologies that are more about lining up a grid of little lights, each individually controlled, rather than the LCD technology of a grid of little windows, each letting through filtered light. LED is just a device that emits light in response to electrical current. Basically, OLEDs were the first emitters that could be controlled individually while being small enough to serve as pixels on a display. Traditional LEDs just weren't easy to manufacture small enough to incorporate as individual pixels. Note, though, that an array of lights that are individually controlled starts to give certain advantages over an array of windows/curtains. For power consumption, you're only lighting up the lights you use, rather than lighting up the whole screen and blocking it from going through at certain points. When you turn the light off, it's totally black (basically an infinite contrast ratio). On the other hand, there are disadvantages. Blue emitters tend to fade faster than green emitters, which tend to fade faster than red emitters. Emitters in general also just wear out, so you see pixels that are used too much start to burn out, which causes \"burn in\" on the appearance of the display. QLED display tech is actually an LCD tech, with windows and curtains, which is confusing enough. But the backlight actually goes through a fancy filter in each window, where a quantum dot technology glows a precise color that is different than the backlight. So it's not just a filter/curtain situation, but a combination of the backlight technology and a newer tech for emitting colored light. It combines some of the best of both worlds (but also suffers from that whole \"can't block out all light\" problem, so we're back to the contrast ratio issue). Some of the stuff they're working on is to have LED backlights that cover only a smaller portion of the screen, so that you can have pure black on one side of the screen (by turning off the backlight completely) while still using colors on another part of the screen. That super expensive Apple Pro monitor uses a lot of tricks like that in the background, with 576 individually controlled LED backlights."
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nhx4jg | Why are wireless headphones the only implement you can't keep using while it's charging? | Everything else (unless it's something that moves like an electric car) can be used while charging. Phones, handheld consoles, game controllers, hair trimmers, flashlights, anything but headphones. Is there a reason for that? EDIT: typo | Technology | explainlikeimfive | {
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"Well with airpod style ones, the only feasible way to charge them is through wireless induction charging. I myself have a wireless headset that I can listen to while charging."
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ni0how | How are software update numbers assigned, for example version 22.13.001 vs 22.14.001 vs 23.01.001... what would be required to change one number vs the others? | Edit: Also forgot to include in a scenario where you have 22.13.002 vs all the others | Technology | explainlikeimfive | {
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"Different companies and different projects have different rules about when numbers change, how many numbers to use, etc. But in general, the more serious the changes in the software, you increment a number further to the left and all the numbers to the right become 0 or disappear, again depending on policy. What qualifies as a \"serious\" change is again a company policy. When chrome or firefox increment the left-most number they've added or removed something that users WILL notice, at least eventually if they use all the features and browse all the settings, etc. For minor changes - spelling corrections, bugs fixed that most users will not notice - you increment a number further to the right. 1.2.3.4 might become 1.2.3.5, or maybe 1.2.4.0. Software used by other software often uses version numbers to show the difficulty of upgrading. If their policy says that the middle digit changing does not mean work for its users, then upgrading from 2.4.5 to 2.5.6 should be safe because the left digit remains the same. But once again, every company has its own rules and this is just the trend. There are software projects that increments a number just because the number to the right got too big Linux went from 4.20 to 5.0 just because its lead developer thought `20` was a big number. There was nothing unique between 4.20 and 5.0 when compared to 5.0 to 5.1, or 4.19 to 4.20.",
"No hard and fast rule. The \"small\" numbers (ie to the right) are typically assigned to bug fixes, minor corrections - eg spelling errors, window size corrections etc The \"middle\" numbers are for minor content tweaks. For games, these are things that affect gameplay but in not a major way (like adjusting a character power, speed etc). Sometimes releasing new content. Typically these changes are fairly seamless 22.001 will work with 22.002 etc etc. The \"major\" rev numbers (ie to the left) are usually major changes to the software. It will probably have significant impact to the user. Usually not done very frequently - for stable software, it could be years. The major revs can also introduce incompatibility. So rev 22 might not work with rev 23.",
"The number is up to the developer and different developer change them in different way. A common way is the X.Y.Z variant. X is the major version number. Y in the minor version number. Z is the patch. So X changes when you consider is major changes. It might be that non backwards compatible charges, other major chages or just that you do that because you charge for uppdates to new major version. Y change when you do minor changes to the software. Z changes when you fix bugs or similar small changes. But that is just a common way to do it. As a developer you can do it anyway you like. You could release software and decrease the number start at 100 and next version is 99. It might be stupid thing to do and it confuse people that use it but you could do it There can be requirement of what to do if you use some external services like app stores to distribute the software so updates etc works"
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ni883s | Why do people buy nfts? I dont get it. | Technology | explainlikeimfive | {
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"I am very much just as puzzled at this whole hype as you are. However, the fact that there are copies of the video all over the net isn't a good argument, imho. You can get prints (copies) of the Mona Lisa all day long, it's still a different matter to actually *own* the painting. I know that this is not a perfect analogy because if you own the Mona Lisa, you have an actual physical thing you can touch. Still, this is about owning the original."
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ni9l6g | How does pausing in video games work? | What happens when you pause a game? Why are you able to just stop all the work the computer is doing and perfectly able to let it go again? With all the calculations it's doing, especially for 3D games, surely pausing it can mess up something that's in the middle of running. | Technology | explainlikeimfive | {
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"> With all the calculations it's doing, especially for 3D games, surely pausing it can mess up something that's in the middle of running. Why would it? You also can put down your pencil at any point when doing math on a piece of paper and then resume at any time. Same applies to computers. Fun fact: your computer is actually switching programs it is running at hundreds of times a second, pausing every time to run something else. It will run one program for one hundredth of a second, pause that computation and run another program for another hundredth of a second, and so on to make it seem that all your apps are running at the same time.",
"Games run in a loop: 1. Update game state (e.g. enemy positions, camera angles, etc) 2. Re-draw the screen 3. Go to 1. Typically when you pause a game, the game state is stored in memory but this loop is paused. Nothing is being updated. When you resume the game, it continues the loop with whatever state it had before it was paused.",
"You are not stopping the game. The game is still running. When you pause a game you just tell the AI to stand still and not do anything until you want it to resume. The game is still running. Its just that all the characters are not doing anything. It would be far too much hassle to shit everything down when you just want to pause."
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niik90 | How do paleontologists discover underground cities and fossils? | Technology | explainlikeimfive | {
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"Detective work really. We know fossils form under very specific conditions. Essentially an organism needs to get covered up somehow before it's eaten or decomposes. While the soil around it petrifies. Water seeping through will slowly erode the organism away while depositing minerals that fill up the organism shaped hollow that's left behind. The study of geology also teaches us what the Earth was during different time periods. That helps us look for rock formations from the right time periods. But more than that, we can also look for places that used to be conducive to the creation of fossils hundreds of millions of years ago. For example, there are many English beaches that are great for fossil hunting. The tall cliffs lining the beaches are essentially layers of sediment from across the ages. Every time there's a storm, another layer erodes from the cliff side, potentially exposing new fossils. Other fossil fields used to be a bend in the river at some point in time. Animals would die in or by the river, get swept away by the water and get stuck in the bend while getting covered up by mud. Anyway, there are lots of different indicators. But palaeontologists start by trying to find areas of the correct age with features that indicate that past conditions were perfect for fossils. Of course, there's also a lot of fossils that were found through sheer luck. For instance during mining excavations or during construction work. Human structures and artefacts are searched for by archaeologists, not palaeontologists. But the process is kind of similar. It's detective work to identify the most likely locations. Human habitation leaves signs even long after it's gone or buried. Vegetation grows differently if there's stone underneath rather than pure soil. Or buried ruins can cause unnatural-looking hills or shapes in the landscape. Human habitation is also predictable. We need water. We need land that can support us. We build roads that affect the landscape long after they're buried and so on. So just like the geological history of the land can teach us the most likely places to look for fossils, it can also teach us how humans from the past would have looked at the land to find the best places to settle.",
"Archeologists discover cities, paleontologists discover fossils. Different people, different training, some of the same techniques."
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niirw4 | How does a children's spring microphone work? | Here's a link to a diagram ([ URL_2 ]( URL_2 )) and a picture of the microphone itself ([ URL_0 d=2ahUKEwjCtNGls93wAhWQBisKHdRABGMQ2-cCegQIABAA & oq=how+does+children%27s+spring+microphone+work & gs\_lcp=CgNpbWcQA1CWHlj1JmCMKWgAcAB4AIAB-AGIAZIJkgEFMC42LjGYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ & sclient=img & ei=5AepYMKyNpCNrAHUgZGYBg & bih=625 & biw=1366 & rlz=1C1CHBF\_enAU877AU877#imgrc=iNfmh01cUYJzjM]( URL_0 | Technology | explainlikeimfive | {
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"You may have heard that LEDs can also be used as light sensors, or the reverse. We make these devices separately, because we optimize them for one function or the other, but each type of component can be used the other way if the need arises. Speakers and microphones are another pair of devices that can be swapped when needed. Speakers work by vibrating a diaphragm according to some signal, while microphones generate a signal using the vibrations of a diaphragm as a sensor. As long as you have some way to power them both, you could plug one straight into the other to create a device that carries sound from a microphone to a speaker (though the speaker would be very quiet; usually you at least want to add an amplifier onto the circuit). The fun thing about speakers and microphones, though, is that you can power them with things other than electricity. The two-can telephone is an example of this: tie two cans together with a string attached to the bottom of each, stretch the string tight, and sound will travel between the cans. The tension in the string allows it to vibrate along with the cans, and this essentially carries a signal across. All of the above is leading up to the spring microphone, which takes this principle and applies it using a single diaphragm as both speaker and mic. Like the two-can telephone, you have a spring stretched tightly that carries a signal. But unlike the string in our previous example, the spring is flexible: even as it vibrates it stretches and gives, and this distorts the signal. The distorted vibrations push and pull on the diaphragm, much like the kid'a voice, and so it gets played back like a speaker. You wouldn't want to use a spring for a two-can telephone, because that kind of distortion usually isn't deairable. But it sounds funny, so someone got the idea to make a toy out of it."
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nijh8r | How do 3D printers work? | Technology | explainlikeimfive | {
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"They work in a variety of ways, but the most common two types are FDM and SLA. FDM aid basically a computer controlled glue stick. It squeezes a long thin bead of semi molten plastic from a nozzle, which cools and hardens after it has left the nozzle. The part is split into layers, and the glue stick draws the outline of the layer, and then colours in the middle. It the moves up one layer and does it again until all the layers have been drawn. SLA uses a bath of liquid, which turns solid if you shine a bright light at it. So it uses a laser to draw on the liquid turning it solid layer by layer, much like the FDM a process drawing the outline and then colouring in the middle. The liquid is in a transparent tray and the laser shines up from below. There is a platform in the liquid which leaves a thin gap one layer in height to which the solidified liquid sticks. Once each layer is complete this platform moves up by one layer, leaving a thin layer of liquid under the solidified part, stuck to the platform and it all starts again."
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nijs46 | Why a base 3 or base 4, computer is not practically used? Won't they be able to perform more calculations in lesser bits? | The argument I heard against this idea was lack of sophisticated hardware to differentiate more than two energy level i.e. high/low (0, 1). But why haven't we made such advancements to realize a computer with (0,1,2) or (0,1,2,3) as possible values per bit? | Technology | explainlikeimfive | {
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"We kind of have but I don't think it's what you were expecting. Sensing voltage is a far more complicated circuit and would take more area than the equivalent in binary which is what's more important in a CPU. An SSD on the other hand is trying to cram in a whole heap of data into limited space uses this technique. The NAND has a voltage corresponding to the 2, 3, or even 4 bit levels and then has voltage sensing on the outputs. Since there's only one set of outputs the voltage sensing circuit takes up a minimal amount of space on the controller's die.",
"Computers are all run off of series of switches that can be either on (1) or off (0). They don't have a 3rd and 4th state. Therefore, everything needs to be done in base 2.",
"You can do it, it just gets mucky We store multiple bits per cell in SSDs, up to 4 these days so each transistor has up to 16 different levels but you need a complicated circuit on the output reading what precise voltage level it's at You could build a computer that ran on 3 bits but the gate design and logic behind it are significantly more complex. Having a trinary system won't give a performance advantage, it'd be significantly worse for the first decade or so and at best catch up with binary systems. We're limited by heat, not how many bits things can handle so anything that increases the complexity of the gates means more heat and requires a reduction in speed to balance it out Engineering is all about balancing competing needs, binary computers are a better balance than trinary ones are"
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nim2sm | Why is it that whenever we buy a new electrical item like headphones or similar, it is usually pre-charged but only a bit rather than fully charged? | Technology | explainlikeimfive | {
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"Modern lithium batteries break down if they're left fully charged for a long time, *or* if they're allowed to discharge completely. When the device reads 0%, it really means 0% of the safe amount (and 100% is really 100% of the safe amount). They will *very slowly* discharge over time, so to safely stay on the shelf *after* manufacture, after storage, after shipping, and not either end up dangerously discharged there needs to be *some* charge, but they also can't be stored fully charged. So they're partially charged, usually about 2/3s full."
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ninb4x | What does the A-10 “Warthog” accomplish that an AC-130 Gunship cannot? | Technology | explainlikeimfive | {
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"The a10 is relatively fast and can get in, hit a ground target, and get out. The ac 130 in comparison is a huge, slow target. It does have bigger guns, more ammo, and higher loiter time, but the two aircraft really have different roles and applications. A single ac 130 also costs roughly as much as 10 a10 warthogs to build.",
"The AC-130 is basically an area effect weapon, whereas the A-10 is targeted destruction at the object in the flight path, so as the A-10 flies towards an armoured vehicle it can destroy it and anything sheltering around it, the AC-130 can plaster an area wiping out infantry and light armoured vehicles and soft skinned vehicles allowing infantry to retake an area or push through a space which has been opened up in the line."
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nisbov | What is Torrent seeding and how does it help? | Technology | explainlikeimfive | {
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"Torrenting works on the basis that instead of you getting a big file from a single source you instead have a bunch of people who each give you a little piece of the file you want, and you give them little pieces you have that they need. A person who is giving away pieces of the file to others, even if they already have all the file, are seeders. They are \"seeding\" the file.",
"Torrents work not by downloading a file from a set server, but by individual people, or peers, sharing the file they have already downloaded. The original uploaded cannot be expected to keep the file available forever, so it becomes the responsibility of the people who have downloaded the file, such as yourself, to share, or seed, to future peers. Only by seeding everything you download to (at least) 1:1 (give back an equal amount as you've taken) are you helping to keep torrents alive. TL/DR: if no one is seeding, no one else can get the files."
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nivq48 | How come birds don't get electrocuted when they stand on power lines/phone lines? | Technology | explainlikeimfive | {
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"Electricity is a very lazy force. It won't flow through a path if it can't get any benefit from it. Each of a bird's feet is on the same line, and so they're at the same \"electrical potential.\" The electricity in the wire has no motivation to travel through the bird's body and back into the same wire. Now, if the bird were somehow able to plant one foot on an energized wire and touch something at a lower potential (closer to the \"ground voltage\"), electricity *would* flow through that path because it goes to a lower potential, and you would have one very crispy bird. This happens with squirrels more than zero times a year.",
"Because they're not grounded. You too could hang off of one and be safe. Just don't get up there with a metal ladder..."
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nix06n | How can Iphones detect liquid in the charging port if waters trapped inside and you try to charge it? | Technology | explainlikeimfive | {
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"text": [
"It senses more than one contact is touching themselves with each other and it shuts the port off until they stop touching each other."
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njcik5 | How was the very first computer able to understand commands? How did they code a system to understand code in the first place? | Technology | explainlikeimfive | {
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"The very first computers didn't understand computer code, they were programmed by hand using a series of switches. The famous Bronze Goddesses used to decode enigma during WW2 were programmed manually in this way. But you could argue they weren't true computers yet, as they were mono-task devices. Programming computers by hand was inefficient and impractical so the concept of the computer language was invented to be able to quickly program computers to perform repeatable tasks. Assembly languages were developed in the late 1940's which were the first computer languages. The computer processors were designed in parallel with the language in the same way that you design a car with a steering wheel and pedals otherwise you wouldn't have a way of driving it. The limits of assembler however is that you need an extremely high degree of understanding of computers and their operation to use it. It isn't practical for anything but the most basic of functions. To make computers do more we invented high-level programming languages that would act as an interface between humans and complex computer logic. Essentially creating a tool that allowed humans to write the logic (a computer program) and then translate it into assembler using a tool called a compiller. The first such language was IBMs FORTRAN created in the late 50's. Higher level languages like C came much much later. The compilers of those languages transform the easier to read code into assembler (machine code) underneath that the processor can understand. Modern languages like HTML, PhP, JAVA etc go a step further in that they produce code meant to be translated by an intermediary program, which in many cases is the browser. The browser in this case is the interface that transforms web code into machine language."
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njdj3n | how does my gps determine how long a trip will take? Because I feel that I speed atleast a little most of the way, but the time of arrival never changes | Technology | explainlikeimfive | {
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"Because it is actually really difficult to decrease travel time by simply increasing speed especially in small constant amounts. For example: 10 mile journey 10 mph - 1hr 20 mph - 30 min (saves 30 minutes from above) 30 mph - 20 min (saves 10 minutes from above) 40 mph - 15 min (saves 5 minutes) 50 mph - 12 min (saves 3 min) 60 mph - 10 min (saves 2 min) 70 mph - 8.5 mins (approx) saves 1.5 min) 80 mph - 7.5 min (save 1 min) So once you start speeding say from 55mph speed limit to something illegal, there isn't much time savings unless you're doing something really illegal like 110mph CONSTANTLY. EDIT: There is also somewhat of a \"natural cruising speed\" for highways if there is some traffic. So in a 65mph speed limit highway it is very easy to cruise between 65-75mph constantly and just overtake between gaps etc. But if you try to go at 90mph, the gaps are \"smaller in time\" and you'll constantly speed up and slow down to overtake safely as you approach traffic ahead. So the actual average will be less than 90mph.",
"Your location services already know how fast you are likely to drive on a given road. And the other traffic too, from their phones. It doesn't calculate based on speed limits, but on actual driving speeds and traffic patterns.",
"If you drive an hour at 10% over the speed limit you would have saved 6 minutes. But you can easily spend a minute going through an intersection as you need to slow down from highway speeds, wait for traffic to clear and then accelerate up to speed again. And these times are highly variable so you can easily lose all the time you saved by speeding in a bad intersection. It is not unusual to pass someone driving slower only for them to catch up to you ten minutes later as you wait in traffic. So the GPS predictions are usually quite accurate because you do not really make up much time by speeding.",
"Apps like google maps don't calculate travel times based on speed limits, they base it on how long it usually takes real people to make that trip. You speed a bit, but so does everybody else."
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njet3r | why is it people can hear our phone calls through car speakers but not our music? | Technology | explainlikeimfive | {
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"text": [
"Cause the volume on phone calls is louder?"
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njhglw | What is a short in electronics? | Technology | explainlikeimfive | {
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"Electricity wants to go the shortest path to from the power source to \"ground'. But people put a bunch of lights and chips and stuff in the way and make it go through that all first. It you mess something up and make a shorter path it will 100% take that path and not bother going the long way through all the lights and chips and stuff. Ruining your thing, with all the electricity you needed going a faster way instead of the way you wanted.",
"Electricity is lazy as shit. It really doesn’t WANT to power your lights and stuff. So if you give it an easier route to get to where it wants to go (the ground, normally, think lightning) … it’s gonna take it."
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nji8dg | Considering that CCTV footage is the primary way of identifying shoplifters, bank robbers, etc., why is the footage for something so important such low quality that you can barely identify a face? | Technology | explainlikeimfive | {
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"CCTV cameras can't be recording all the time because high res video uses up a lot of space. So CCTVs use tricks like lower resolutions, temporary shutdowns, and compression to reduce the amount of storage they require. You CAN have super high quality CCTV footage but a lot of businesses don't bother because it's too expensive. Camera systems are often very old and outdated and ostensibly only exist to reduce the cost of insurance coverage. Casinos for example have incredible CCTV setups, while a gas station will have a couple of cheap cameras and a couple TB of NVR (video recording) Catching thieves also isn't as important as you might think. A lot of businesses don't bother with the hassle of catching petty thieves since it's easy to claim the insurance or write-off the cost than it is to pursue in court. Casinos however are very much interested in pursuing and banning cheaters. The stakes for them are much much higher. Footage shown on TV is sometimes also deliberately lowered in quality to protect intellectual property or by-standers.",
"Because high definition footage requires a lot of storage space and higher quality equipment (computers and cameras) that can be very expensive.",
"CCTV mostly reduces crime through deterrence. It causes criminals to commit crimes someplace else. As a result, the imagery isn't really essential, only that there is imagery that can sometimes lead to an arrest. That makes real cameras slightly more effective than fake ones. Spending money to get good information would be much more expensive, do unless you're all in on suppressing your population (Yes, talking about you China) than it's not worth the extra cost to get good imagery."
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njkd7q | What is Zero Point Energy? And how could alien ships use this for fuel? | Technology | explainlikeimfive | {
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"Zero point energy is the lowest possible energy state of the vacuum, the \"buzz\" of the void. It cannot be accessed or used in any way, no matter how advanced the technology (unless our physics is wrong). A difference in the amount of energy is needed in order to extract some to do some work. Since every spot in the universe teems with zero point energy, there is no differential due to zero point energy anywhere that can be extracted an used. Every point in the universe has at least that amount of energy already.",
"Instead of having no energy like you would expect all empty space has a certain amount of energy by default. As far as we know there is no way to use that energy. It’s everywhere so there is no clear way to use it. It’s a cool way for fictional aliens To power a ship, free energy everywhere!"
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njl31y | If the Sun emits electromagnetic radiation and the Earth is protected by the ozone, how does things sent to space protects itself from it? (spacecrafts, satellites, ISS, astronauts, etc.) | Technology | explainlikeimfive | {
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"Very few astronauts have been at a high enough altitude in space to worry about that too much. 99% of astronauts have only been to low orbits and so are protected by the Earth's magnetic field. The ones who went to the Moon just had to accept a higher chance of cancer and the possibility of a solar storm killing them. For things like satellites, probes, etc the electronics are shielded.",
"Electromagnetic radiation is radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays. The sun primarily emits infrared light, visible light, ultraviolet light. The ozone layer blocks most of the ultraviolet light. So the ozone layer is relevant for life on earth that is out in direct sunlight. Blocking UV light is trivial, the aluminum foil you use in a kitchen will block all of it. So it is not a problem for spacecraft. It could damage optical instruments but so the visible part of the direct sunlight. Plastic can also be good at blocking UV light. Typical astronaut helmets use polycarbonate for the transparent part will blocs over 99% of all UV with the tickets used in protective glasses, A astronaut helmet is thicker. So the UV on an astronaut's face during a spacewalk is less than if you are out in the sun on the ground with no protection. There is a radiation problem with the sun but that is the solar wind with charged particles, protons, and electrons, not electromagnetic radiation. The magnetosphere protects the earth from most of the and ISS is inside the magnetosphere. That is one of the problems for astronauts if you for example travel to Mars."
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njxvg9 | Why do image and video quality worsen the more they are saved and uploaded? What contributes to this? | Technology | explainlikeimfive | {
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"Many of the common file formats use various forms of 'lossy' compression, which means that they reduce the file size by discarding some of the information contained in the image/video. So each time you save the file again it gets compressed again, and more data is lost. The algorithms that they use are designed to keep the data that's most important to the image quality, but they're not perfect, so over multiple save/compression cycles, more and more of the original image is lost and the amount of weird compression artifacts grows. There are 'lossless' compression file types/algorithms, but they generally don't reduce file sizes nearly as much.",
"Every time you put content into editing software and make any changes, the saved file will be re-compressed and that will reduce the quality. RAW photo files, RAW format video, and so on do not suffer degrading if that is your saved format. The problem is that the file sizes for those are huge, so no one shares RAW format."
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nk481j | What prevents us from seeing source code in closed source software? | Doesn't that code have to be somewhere in the app in some form for the app to function? & #x200B; EDIT: Thanks for all the responses. I think I get it now. | Technology | explainlikeimfive | {
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"No, the source code is more like a recipe which *creates* the app code which is needed for the program to function. The source code is all laid out in a logical, human-designed and human-readable format, and then a compiler turns that into a much tighter, optimized, machine-readable version of the algorithm which is described by the source code. This machine readable version is called, appropriately, machine code. There do exist programs called decompilers, which can go the other direction and give you source code from a piece of machine code. But a decompiler isn't just like \"Give me *the* source code this was compiled from.\" It's more like \"Give me *a* source code which, if compiled, would produce this machine code.\" What comes out is likely to be ugly, unreadable, and look like nonsense to a human, even if it compiles and runs just fine.",
"No. The source code is roughly analogous to a blueprint or a set of plans. After a program is written, it is then \"compiled\" which takes the source code and converts it into a lower level programming language that a computer can more easily and quickly understand. Your question would be somewhat similar to trying to take your house and translate it back into blueprints.",
"Source code is the recipe for making the cake. The actual program is the cake. Open Source software publishes the recipe. You can either bake it yourself, or sometimes you can find someone who will bake it for you. You can also tweak the recipe to fit your own taste. Close source software just serves the cake and keeps the recipe secret.",
"All code ultimately gets converted into \"machine code\" at some point before it is run. This is a stream of 1s and 0s representing basic actions that can be performed directly by the processor in your computer. By this stage, human-friendly names and comments have been removed, and many high-level commands will have been broken down into more basic ones. It is in principle possible to examine this code and work out what it is doing, but it can take a lot of time and effort. Depending on the software, this process may be carried out almost in its entirety prior to the software being distributed, or it might happen mostly as the software is run. So you might find that all you have on your hard disk are a bunch of files that look like random gibberish if you open them in a text editor, or you might find that most of them are human-readable code, or you might find a mixture. In addition to this, a lot of companies go to extra lengths to make it more difficult for people to reverse-engineer their code. This might include: * encrypting certain sections of code, and having the rest of the program decrypt them when they need to be run * obfuscating code, for example by removing whitespace and comments and changing names of things so that it's less clear what they mean, in order to make the code less human-readable even though the computer treats it exactly the same * requiring users to connect to your servers to perform certain tasks, so that some of the code can be kept on your servers and run there - this means that unauthorised people can't even look at it",
"The code that gets packaged with the application to be executed on your processor comes in the form of machine code. This is a format which is highly optimized and minimized so that the electronics in the processor can easily execute the instructions. This is very detailed minimal instructions of exactly where each byte of data should be copied to and from memory addresses and each register and exactly what calculation should be performed on each byte of data. However there is no mention of what exactly this means and how it fits together on a larger level. So while it is possible to convert this machine code into human readable assembly language it is very hard to interpret what this code is doing. It is not impossible though but it can be painstakingly slow to do so."
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nkcad1 | What do the letters in car models mean? | Technology | explainlikeimfive | {
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"It's mostly marketing lingo, and the letters can mean something different based on which car company you are talking about. Partly because those letters are trademarked. For Mazda RX is 'Rotary eXperimental' For Lexus RX it's 'Radiant Crossover' GTO - Gran Turismo Omologato - Italian for 'Approved for Racing' SS - Super Sport Honda CRV - Compact Recreation Vehicle"
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nkfzu9 | how do microphones in a phone not pick up any audio that the speakers put out? if I put a call on speaker mode, how do people on the other end not hear themselves? | Technology | explainlikeimfive | {
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"They do, and it is very difficult to mitigate. The first step is to isolate the speaker and the microphone from the chassis, as sound is a vibration and the chassis will transmit it better than air. Ths is mechanical engineers job, and it is not easy, esp. on a cramped cell phone. The next step is to use specific microphones that are directional, and will only pickup sound from a very near source. Then there is active noise cancellation, where a secondary (or more) microphone records the ambient noise to \"substract\"it from the one coming from the primary microphone. This is done by software. Finally, there are various filters, both software and hardware, to eliminate unwanted noise, like echo and larsen. some are integrated in chips, others need to be coded. People often use both. TL;DR: the microphone picks this up, but phones are made to remove it.",
"One very important point - conferencing software never feeds the sound from your microphone back to your speakers. They feed that sound to everyone else, but never to you. This means you can't get the short-loop feedback howl that is really easy to get in a PA. But you can get the long-loop warble from a loop that goes into your mic, out of someone else's speakers, into their mic, back to your speakers, and to your mic. Another thing they do is detect when you are speaking, and adjust the speaker volume down and the mic volume up, then restore the speaker volume and cut the mic once you stop. It doesn't make for a good result, but it works. You can also use a 'comb filter'. Carve regular notches our of the speaker sound, so that a graph of the frequency response looks like a comb. Then filter the frequencies that remain in the speaker output, from the microphone, with a 'complementary' filter. The sound you get from such a setup is - well, ugly - but at least you can get rid of the worst echo.",
"I hear myself all the time when my friends with Iphones talk to me on speaker it's fucking annoying because there's at least half a second delay and suddenly i'm talking to myself",
"The mics do record it. But then it depends on the software, as some do cancel it or ignore it. Where the hardware is placed also affects. Have a voice call in a game while playing both without headset, just speakers, and you will probably hear that feedback with a second of delay or so.",
"Electronic engineer here Sound's system in phones has something called \"negative feedback loop\" which basically means that it subtracts the output sound from the inputs sound. here is what it does in a function form (person voice + phone voice) - **(phone voice from feedback loop)** = person voice the bold **phone voice** is the signal fed through by the negative feedback loop.",
"Have you never heard yourself while on the phone? It happens (used to happen more often) and it's really annoying.",
"As someone who works in a call center, a lot of speakers do pick up their own audio on speakerphone, and the person DOES hear themselves. And we hate it.",
"Um we do? Every time all I hear is the echo of my annoying voice",
"Part of my job is taking calls from the public. I can hear everything going on in the background and I wish people didn't think phones were a magic device that only picked up speach. I can hear you eating, peeing, breathing. I can hear Wheel of Fortune in the background. I can hear the baby screaming on your lap. If you put me on speaker phone I do hear an echo of everything I say. If you call someone be courteous and do it from a quiet place.",
"I mean, I can definitely hear when someone has me on speaker. And I can definitely hear myself talking.",
"Just throwing this out there, as someone who works in a call center taking for 8 hours to people in their cellphones, your speakerphone doesn't filter out sounds as much as you think. Please, just take the call off speaker. I'm so tired of hearing myself echo back.",
"Basically, there are two microphones on most phones one of which is used for noise cancellation. They compare both audio signals from the speaker output as well as from the microphone and subtract those signals. Hence leaving the required signal to be transmitted.",
"The first thing a microphone will be connected to is a filter and then an amplifier. The filter is mostly to get rid of things outside of hearing range. Next it goes to the amplifier. The amplifier will have a built in common-mode rejection. This means that a signal on the input that is matching another signal will get snubbed out, while signals unique to the input will be amplified. Typically the common-mode rejection ratio is around 100 dB, so the sound of the speaker on your phone ends up being about 1/1000 as loud as your voice."
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nki9o2 | Is the cut-down hashrate on the new GPUs going to affect performance in usual tasks? | As far as I remember, this was created to limit mining performance. If this cut-down is not going to affect performance in usual tasks like video editing and gaming, why do GPUs have it in the first place? | Technology | explainlikeimfive | {
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"Hopefully this ends up being close enough to ELI5. As far as I know the hashrate limiter in the rtx 3060 was made in software only. More accurately with the GPU driver. I don't yet know how nvidia will end up implementing the same limiter in the upcoming versions of the other 3000 series cards, but my bet is that it's still mostly done on the software side. Basically the gpu driver is detecting a specific type of computation and in such instance throttling the performance. By the way this only applies to the hashing algorithm used by ethereum. Other algorithms shouldn't be affected. Nvidia's argument for the restriction is that that there would be more gpu's available for other users (eg. gamers), as miners would gravitate towards other cards. The more probable reason is that they will be also coming out with a miner specific line of cards. So in the end it's about squeezing more money out consumers.",
"No, they work by trying to detect when someone is specifically using the card for mining, and only reducing performance at that point. So it’s not like they just built the card and cut out a part that lets it mine, they just tried to make it smart enough to know when to throttle itself so it would be worse at mining. A lot of the same functions that make GPUs good at mining also make them good at all the other tasks people use them for. That’s why people switched to GPUs for mining in the first place. So you couldn’t realistically remove that functionality entirely without actually impacting performance on other tasks. So instead they just tell it to look out for anything they don’t want you doing and then cut performance across the board while you’re doing it. They say it’s unhackable, but that’s almost certainly not true. We didn’t really get to find out though since Nvidia released a test driver by mistake that didn’t include the limiter. So no one needed to make their own work around once they could get Nvidias. They are trying again with new cards soon, so maybe this time it’ll last a little longer."
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nkki4f | How are videogame codes protected ? | Let's say you download a game and can play it offline. In theory, everything you need is on your computer, right ? So how come people don't just find everything, copy it and massively share (or sell for a lower price) folders with everything in ? | Technology | explainlikeimfive | {
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"That's how pirated copies work, essentially. Not quite as simple as a copy & paste, of course. Games, like every other program, need to have what you could call an \"entry point\". It's a program or a function that needs to be executed to start the game proper. The entry points of games have protections installed in them that run certain checks to make sure the copy is legitimate before starting the game. They can look into windows registry, they can contact a central server, whatever. If they don't like what they find, they won't load the files and they won't start the game. That's the DRM. That needs to be bypassed for an illegitimate copy of a game to be able to start. Not all games have DRM, and those can very easily be copied and shared. edit: engrish",
"Your title and description mean two different things. For video games that are made in C++, you would need to disassemble the executable file and try to read the machine code ( which is incredible hard as most of it is just nonsense that's unreadable ). This alone takes up too much time so unless there's a BIG incentive for the hacker to do so, ( adding viruses to the crackedware and stealing your $$$, etc ), no one will do it. You can't just share game files with your friends even if you can play it offline because most of them have basic authentication that prevents you from doing so. Something simple as checking your PC HW ID, etc. No one sells cracked games because no one is stupid enough to buy them. ( Please don't confuse this with G2A, etc. Those games are not cracked. Most of them are official games with official accounts or stolen keys that lets you play them... ) Most of the cracked games you see on torrent are riddled with viruses. Even the top torrent users have been caught riddling their \"free, crackedware\" with viruses.",
"I see a lot of wrong answers here a) DRM protection: Games that will only run when a certain key is entered (it can be bypassed with enough time and effort) and games that will only run when launched through a service like steam. b) Connection requirement (for online games): If the client appears to be modified in anyway then refuse all requests for a connection to game servers. DRM protection can be byepassed, that's why you can find pirated copies of almost all games DRM free games like GOG-games can be shared just by sending the installer to someone else, even though it's not ethical to do so"
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nklb46 | Noise cancelling headphones: how can sounds waves disable other sound waves? Is it possible that before the external sound wave travels the space between my headphones’ external microphone and my ear, my device has enough time to produce a sound wave that perfectly cancels it out? | Technology | explainlikeimfive | {
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"Sound is pressure waves. And when one sound wave creates low pressure and another creates high pressure they end up canceling each other out in that perticular spot where they cross. The noise cancelling headphones just make sure that the spot where these waves cancel is right at the entrence of your ear canal. They are able to do this because the microphones are much farther away from your ear then the speakers and electricity travels almost instantanious while the speed of sound is much slower. The headphones may still employ techniques to predict the noises before they happen by analyzing the frequency and the rhythm of the various noises it picks up.",
"Yes. Without too much difficulty given modern microprocessors. Sound travels at about 300m/s. So this is 30,000 cm/s. If the external microphone is 1cm from the speaker, then the noise cancellation has about 1/30,000 s. A simple microprocessor can easily run at an instruction for each 1/10,000,000 of a second. So a microprocessor can execute 330 instructions in the time it takes sound to travel 1 cm."
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nkxwl2 | how do sharpening knives work? | I’ve heard someone say that there is a difference between actually sharpening a knife and making it not dull with a rod or something. What is the difference? | Technology | explainlikeimfive | {
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"When a knife is used, the edge accumulates damage over time by either chipping off or bending over to a side. When you use a rod on a knife, you're just pushing all the bits that are bent back towards the center. There won't be an impact to any parts of the blade that are chipped. When you sharpen a knife, you're removing material from the edge to create a new edge. If there are any bits of the blade that are chipped, they'll be removed via the sharpening process.",
"When I knife gets \"dull\", one of two things is happening. - The edge of the knife is still sharp, but it has bent or rolled slightly to one side or the other. [Here is a picture]( URL_1 ). This is known as the knife being out of 'true' - it isn't _actually_ dull because the edge is still there - and can be corrected with a honing steel. By gliding the knife down the steel, the edge is bent back to true which improves performance. This is known as honing - **not** sharpening. - The edge of the knife is worn down and is no longer sharp. [Here is another picture]( URL_0 ). No amount of honing will fix this because the edge is actually gone. You have to sharpen this knife - remove material from the cutting edge to get it back sharp again. **This** is sharpening."
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nl11l2 | Why can’t any batteries be rechargeable? Why are there specific “rechargeable” AA, AAA, and other batteries? | Technology | explainlikeimfive | {
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"Batteries use a chemical reaction to move an electric charge. When you're recharging a battery, you're basically reversing the chemical reaction. Not all of these reactions are perfectly reversible.",
"Batteries are electrochemical devices. If they arent connected to a circut the reaction doesn't happen. When you connect them to a circut then then a reaction starts that generates electricity. Rechargeable batteries can react both ways, if you connect them to electricity the reqction will happen backwards. Non rechargeable batteries only work in one direction.",
"It’s not so much that you CAN’T but more that you really shouldn’t and it isn’t worth it anyway. The chemical reaction doesn’t reverse well, and releases significant heat in the attempt. The battery can easily explode, or burst into flames from overcharging and will only partially charge besides. They use different chemical reactions to produce electrical currents. Some reactions more easily reverse than others."
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nl3w3a | What are drivers? Why do they need to be updated so often? Why are they even called drivers? | Technology | explainlikeimfive | {
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"Drivers are an interface between the operating system and the hardware. The operating system doesn't know how to operate every piece of hardware, so it needs something in between. I guess it's analogous to different cars having the same interface (steering wheel and pedals) even though under the hood they might operate completely different (gas or electric or rotary engine etc). They are called drivers because they drive or control hardware."
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nl9361 | How does indexing the internet work? Like, what does a search engine like Google do to retrieve millions upon millions of websites? | Technology | explainlikeimfive | {
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"Internet search engines employ what are called \"spiders\", automated programs which will index web pages and follow links to find *more* pages, gradually working their way across the internet to find everything which can be found. Usually when people publish web pages to the public they will want those pages to be indexed so they can submit the addresses to the search engines directly, giving the spiders somewhere to start."
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nlb9iw | why is it that so many games have separate server regions for Korea and Japan when they’re right next to each other? | Technology | explainlikeimfive | {
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"Korea has different rules and laws aboth video games and having sperate servers for those that speak different languages is always a plus",
"Korea and Japan have a bit of a rocky history between each other, but there is also perhaps a more pressing reason: The Japanese speak Japanese, and Koreans speak Korean. Just because they are somewhat geographically nearby doesn't mean that you can drop them in a game together and have any hope they can effectively communicate with each other!",
"The reason is actually because there are so many more players in Japan and Korea that a single server would struggle to handle them all. Splitting across language and legal lines is just an obvious place to divide. The same doesn't happen in Europe that often because the player count for these games is lower."
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nli9qd | how does the mechanical watches work? | I mean where do they get the energy from to power themesevles? | Technology | explainlikeimfive | {
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"There are manual wind watches, but those aren’t super common anymore. A lot of them today have a little weighted piece of metal on a rotor that’s usually on the bottom of the watch (and a lot of times visible if the bottom is glass/crystal). That weighted piece of metal spins around when you move your arm which spins the rotor. That spinning of the rotor is what compresses the spring. So you basically just charge it by wearing it. It’s also why some fancy watch cases rotate, that way they’re spinning that weight and rotor even when it’s away, which is usually considered better for the watch and means it won’t run out of juice and have an incorrect time if you don’t wear it for a little while.",
"There is a coiled spring. When you wind the watch, it tightens up the coil which then creatures the force necessary to power the gears."
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nlie3t | Cameras confuse the hell out of me. | How do they work? Is it glass or mirrors or something? It’s so confusing | Technology | explainlikeimfive | {
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"Curved glass (a lens) is used to focus light onto a photo-sensitive surface - film for traditional film photography, a sensor for digital. Oftentimes this light is reflected off of a mirror inside the camera body for design considerations.",
"For normal film cameras, it's like this. The camera is just a box that keeps light out. Inside that box, there's a roll of film. This film is basically a specially treated type of paper (not really paper, but it's made of cellulose, which is what plants are made of). The film is treated with several different chemicals, which react when they are exposed to light. If you were to take that film and just look at it in your living room, the amount of light would be too great. The chemicals would react immediately, changing the color of the paper until it was completely black. The chemicals are designed to react with only a very small amount of light. The front of the camera has a shutter on it, a mechanical device that opens and shuts very quickly when you press a button. The shutter is designed to let the right amount of light in, so that the chemicals don't \"overexpose\" the film. For a normal camera, it's open for just a tiny fraction of a second (but if you're a really good photographer and know what you're doing, you can mess with the shutter speed and change that -- for instance if you wanted to take pictures at night). There's also a lens, a curved piece of glass, that focuses light onto the film. There's also a mirror in there that reflects the light up to an eyepiece, so when you put your face up to the camera you can see what the picture will look like before you press the button. When you take a picture, a piece of film is in the correct position behind the lens so that the light in front of the camera is focused right on the film. You press the button, the shutter opens and closes very quickly, and now the film has been exposed. The chemicals react according to the level of light they were exposed to. This results in a copy of the image being \"burned\" into the film. This copy will have reversed color (brighter light causes it to burn more, causing a darker image). This is why film negatives have their colors reversed. Then there's a little lever or wheel or other mechanical piece on the camera that you can push. This little thingy pulls the film forward, so that the next frame of film is in the right spot behind the camera lens. When you're done taking pictures, you retract the film into its protective case, where it's nice and dark. You remove it from the camera and then take it to be developed. The developer goes into a \"dark room\" where they use a special type of light that doesn't react with the film, but the person can still see. They then basically reverse the process, projecting light through the film negatives to put an image on a piece of paper that has been similarly treated. You have to wash off the chemicals and wait for it to dry before the picture can be taken outside the dark room.",
"If you really want to blow your mind, take a piece of thin cardboard and punch a medium sized hole in it (like the size of a sharp pencil lead). Hold the cardboard over a table or something under a light fixture. Move it up and down until you can see the projection of the light fixture on the table. Light is so weird.",
"Digital works something like this: Imagine this thing called receptor. It's a square which tells how much light hits it. From 0 to 100%. This would give a image of resolution 1x1. If you arranged 100 of these in a 10x10, you get a 10x10 resolution image. Increase the quantity and the kind of light they receive and you get a camera like the one in your phone."
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nliql6 | Why, although planes are highly technological, do their speakers and microphones "sound" like old intercoms? | EDIT: Okay, I didn't expect to find this post so popular this morning (CET). As a fan of these things, I'm excited to have so much to read about. THANK YOU! | Technology | explainlikeimfive | {
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"I’m a commercial airline pilot and there is a lot of misinformation here. First of all, 99% of the time we’re on VHF AM, not HF AM radio like people have suggested. Second of all, the radio has nothing to to do with the intercom anyways. The real reason is weight. Good speakers are heavy and the fuel to carry those around for the life of the airplane costs thousands to millions. TLDR; Good speakers are heavy and cost too much fuel to carry around.",
"*TL;DR - the speakers, microphones, and all of the plane's audio systems have a narrow frequency response in order to maximize intelligibility over the aircraft's AM radio equipment and between crew members in noisy environments like the cockpit.* Their audio systems, generally speaking, are all on an older, simpler analog standard, for important reasons. The main issue (everything else stems from this) is that the radios they use in the aviation band (~118-136mhz) are AM radios (like AM broadcast radio, or like CB radio). This is weird, because almost everybody else uses FM (like FM broadcast, or like walkie-talkies) at those \"VHF\" frequencies because of the better audio fidelity and noise suppression. However, when two radio operators accidentally talk over one another at the same time (\"double\") using FM, the result is a garbled mess in which neither one of them is guaranteed to be intelligible. (A comparable effect would likely happen with some sort of digital audio transmission.) When two operators double using AM, the result is often just hearing both of them at the same time, so pilots and air traffic controllers can still at least make out what one or even both operators are saying. *Edit: there's been some discussion of this in the comments. If the two AM carriers aren't exactly the same frequency, yes, you may get some nasty interference sounds. All I can say is... FM doubling is a lot worse than two AM transmissions that are tuned to exactly the same frequency. [Further info.]( URL_0 )* So getting back to the audio quality of aviation audio systems: if you're using AM (amplitude modulation), you only want to invest your radio amplitude into audio frequencies that are useful and important to understanding a voice. (This band pass filtering doesn't really matter for FM transmissions, which is a larger discussion.) When, as a ham radio operator, I use amplitude-modulated voice communications to talk to someone in e.g. New Zealand from here in Montana, I limit the audio frequencies I transmit (and receive) to about 150 through 3,000hz. When someone talks, you hear sounds all the way from 100 through 20,000hz, but only about 15% of that range is really crucial to understanding what they're saying. Investing radio power into transmitting all those other audio frequencies is basically just a waste of your radio power, and is likely to get lost in radio noise, anyway. So, the microphones that pilots use, any audio processing, and even the headphones/speakers, really don't need to be very high bandwidth like the speakers/headphones you'd want for hi-fi music listening - they're all geared for maximum intelligibility in the presence of noise, not maximum audio quality. And hence you get \"from the flight deck\" or flight attendant messages over the intercom that sound like low quality audio - it's all part of the same audio system the pilots use to communicate with ATC, one another, other planes, the crew, etc.",
"Small cheap speakers sound bad. Small cheap microphones sound bad, but are very durable. It's not worth the cost, weight, and maintenance to get better audio since there's not much benefit to it in the first place. Good audio doesn't really contribute to a good flight in a way that's worth any of the costs.",
"Commercial Airline Captain Checking In ! ÉDIT: thanks for all the upvotes and badges < 3 Many considerations : - in aviation and aerospace we need to make sure safety related equipment are reliable. That is why multi million dollar planes are equipped with sometimes CRT screens : they don’t break at the first turbulence. Same for the intercom in the cabin : we could install Bose PA speakers but you’d need to make sure first they are designed to be fail proof. We still do check them as part of the cockpit preflight because we need to know in case we do need to announce a no-time emergency (like « emergency descent ! » or « EVACUATE ») they were at least working. I personally listen to it on my mixer to be SURE they work when I use them - laws : they have to follow a specific standard that is very precisely required and there must be only a handful of makers on the market, just like my plane the B737 has only two providers of autopilot controls. In particular there is a need of everything in the plane to be ignifuged to retard fire in case one breaks out. There must be design specifications for, for example, working through interferences, not breaking during a spike surge of electricity (we do connect and disconnect several time a day massive generators of 400hz 115V Ac generators from the planes or the onboard generator or external ground generators and each time a solenoid jumps and spikes can go through the electric busses and would maybe fry mainstream grade equipment) - money : there are certainly weigh considerations for EVERYTHING on board. This equipment is not exempt and modern grade equipment that are not designed with weigh in mind can’t find a buyer from Boeing Airbus or the new competitors. Mind you, a big American airline decided to remove 1 or 2 olives per on-board meal after the first oil price crises : they estimated it saved them half a million dollars in fuel a year. There is no little savings when it comes to weight on a plane. - and finally probably the most likely reason why PA speakers don’t upgrade : Certification. Every system on a plane, every sticker, is certified. Next time you go to the toilet check the stickers : they have a number somewhere that links tl their certification. Each plane is designed with specific design plans and the most basic of its structure is part of the certification. That is notably why you pretty much never have a window perfectly adjusted to your seat : they are designed by Boeing but every airline chooses the seat configuration. The cell stays the same. Now I’m not 100% sure of it, but the speakers might be tied to the plane type. When a plane is upgraded to a more modern one like the 737 which cames from 200 (legacy) to 300 (classic) to 800 (Ng) and now max (-8), at each time the manufacturer can only modify 25% of the désign or the planes is deemed needed a new certification which means a whole complete flight test campain which is extremely costly and also means pilots need to train for the new type instead of a short transition called « difference training ». Since most of this is taken by the update of the wing design, engine, systems here and there that improve fuel efficiency and comfort, a PA speaker is probably last on the list. Mind you the overhead panel controls of the max are still the same as the -200 for some parts because changing it would mean the plane needs a new certification and although it’s 2021 the max doesn’t have push buttons with lights like the new planes because companies have too many of them to want to pay for the transition. Notably Southwest pressured Boeing to not modify the overhead to a modern styled one for this reason alone. Trust me, we pilots would love a redesign of the cockpit that is old fashioned (albeit cool because of that) and noisy for a more modern and quiet one, so if those controls are not updated, the PA will be last Given all that though, each generation of planes gets better on all parameters and I would bet a B787 sounds better than a B727 in the cabin - unless the PA makers have stayed the same ? TL,DR : reliability, laws, weight, R & D, certification, cost to airline training due to said certification",
"While poor comms can be a problem, in general the actual quality that the pilots/ATC perceive is higher than the recordings you’ll find online. The online recordings are generally made with volunteer receivers in areas of poor reception whereas the ATC transmitter sites are professionally set up on top of mountains/towers etc. Pilots do sound more muffled if they’re wearing an oxygen mask (fighter pilots or airlines under emergency) or pressure suit (U2 pilots).",
"Most commerical planes are ancient, in terms of technology. Everyone assumes they are the height of technology but there is a good chance, depending on the route (in the US at least) the plane you're flying in is 20+ years old. Many of them are designs that are even older than that. Look how long the 747 has been flying lol",
"Aircraft Technician here, I’ll presume your asking this question from the perspective of a passenger on a large transport airplane. It’s all about expense, the manufacturers build airplanes the operators will buy, the operators don’t care about PA sound quality. It’s designed to meet the minimum requirement at the lowest cost. Some aircraft that have been designed more recently like the A350 and B787 will probably have better PA audio quality due to advances in technology, but it’s still going to be cost driven. Older aircraft PA systems usually will not be upgraded if they continue to meet the minimum requirement, again due to cost. All this talk about AM and FM frequency bands is lol, there is a very specific HF and VHF frequency range for aircraft communication with Air Traffic Controllers. HF is for long range communication when aircraft are transiting an ocean, VHF is used while over or close to land. This has everything to do with the wavelength of the frequency and nothing else. The sound quality on these transmissions is normally higher quality then regular cabin announcements, because the type of communication on these radios is important for safe operation of the aircraft, thus the operators are willing to pay more for it. Also, any overlay these frequencies may have with AM or FM radio frequencies is coincidental, it’s not important information to answer your question. You’ll also notice the sound quality in the cabin is better when the aircraft is on the ground as opposed to inflight. One, the cabin air pressure is different in flight and this affects the way we perceive sound due to the different pressure in our inner ear. Second, the aircraft smashing its way through the atmosphere creates a lot of air friction and noise near the cabin doors due to the irregular shape of the interface of the fuselage skin and door skin, and some small air leakage at the door seals. Third, nearly all of the PA microphones in the cabin are right next to the doors, so they pick up all the back ground noise of the doors.",
"They make you sit in the cheapest, most uncomfortable, seat possible and you wonder why they don't have high-quality audio? Corporations will do anything to save a buck.",
"Another reason that I don't see mentioned is that there really is no reason for high fidelity in a comms system. The system they have is good enough for understanding what's being said, anything more would just raise costs in an already expensive industry",
"Petition to stop all pilots from needing to report every little detail to passengers; unless there is an emergency or change of plans. I do not know of anyone that gives a damn about airspeed or outside temperature. All the pilots are doing is waking us from our rest.",
"So to all the commercial airline pilots that are chiming in, here is a bit of advice. Figure out what you are going to say before you start talking. \"Hi! this is John your ahhhh pilot here. We are going to be ahhhh flying to ahhhh Albuquerque and we expect the flight to ahhhhh take about ahhhh 3 hours and ahhhhh...\" I don't know about the rest of you, but every damn flight... which is strange because I rarely fly to Albuquerque."
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nluqlo | How do people with amputated Appendages (Arms mainly) control prosthetics to the point where they have control of the prosthetic fingers? Awesome technology, seems it's only getting better, but was wondering how the connection is made when they attach the prosthetic like a glove. | Technology | explainlikeimfive | {
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"A robotic neuroprosthetic (a prosthetic that you can move with your brain) works by implanting electrodes in the brain on specific locations where your brain will activate when you are trying to move the missing limb. Your brain has a designated “motor centre”, where the signals to move come from. When you move, your brain sends a message from this part of your brain down your spine to the nerves in the body part it wants you to move. Those nerves activate your muscles, and they contract, which moves your body part. When you lose your body part, you do not lose the accompanying part in your brain that was able to move that body part. It’s like having a remote without the television. The prosthetic is attached in place of the natural limb, and the electrodes are attached to your brain. These electrodes are able to sense your brain sending those messages. The electrodes are activated by the brain’s messages, and the prosthetic moves."
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nlvryp | Why do storage devices always seem to lose storage? | I bought a 64GB micro SD card for my switch and once I inserted it, the system tells me I had about 60GB. I've noticed USB devices do the same where if I buy a 32GB one, I would only have about 28GB to use give or take. Where does the extra storage go? | Technology | explainlikeimfive | {
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"When you buy a 64 GB SD card, you're getting 64 gigabytes of storage. That's 64,000,000,000 bytes, since 1 GB is 1,000,000,000 bytes. However, when Windows shows storage, it shows it in the approximate binary equivalent, gibibytes (usually abbreviated GiB to avoid this exact issue). One gibibyte is 2^30 , which is slightly more than 1,000,000,000 bytes. 64 gibibytes is 68,719,476,736 bytes rather than 64,000,000,000. That means your 64 GB SD card will be displayed as only 59.6 GiB. Similarly, a 32 GB USB drive is only 29.8 GiB. You also lose some storage to formatting, but the gigabyte vs. gibibyte issue is by far the biggest contributor to the difference.",
"There's been some disagreement about the correct unit of storage and how to name it. Computers have historically used a binary variant of the scientific prefixes/terms kilo (thousands), mega (millions), giga (billions) etc. They're binary machines after all, and circuitry would use a power of 2 for communication. A kilobyte would be 2^(10) = 1024 bytes. However the proper scientific definition would be 1000 bytes exactly. The term \"kibibyte\" has come about to represent the 1024 variant. It's turned into a mess of some hardware makers and software makers using different numbers in different contexts. A 32 GB SD card probably means 32,000,000,000 bytes (approximately... it's never exactly a round number like that). However Windows probably reports a gigabyte as being 2^(30) bytes = 1,073,741,824 bytes. If you put these two different interpretations together, windows reports the card as being 29.8 gigabytes. Even computer experts *hate* this differentiation. For example, an old 3.5 inch floppy disk held 1.44 megabytes. That's 1440 kibibytes... or, 1 megabyte = 1000 kilobytes but 1 kilobyte = 1024 bytes. A 650 MB CD-ROM holds 681,574,400 bytes, but a 4.7 GB DVD holds around 4,700,000,000 bytes (rounded). Ugh.",
"The units that the device manufacturers and the operating system in the computer are not the same. Kilo is a prefix for metric units and means 1,000 and has been used since 1795. Mega for 1,000,000 was added in 1873. Giga for 1,000,000,000 and tera for 1,000,000,000,000,000 was added in 1960 Computer memory is addressed binary so it is multiples of 2, not 10. 1024 is a multiple of 2 and people started to be called 1024 a kilo because it was very close in size The same way you get a * mega of 1024*1024=1,048,576* * *gigi 1024*1024*1024=1,073,741,824* * *tera 1024*1024*1024*1024=1,099,511,627,776 For giga the variant with 1024 is 7% larger than the 1000 variants The storage medium is sold with units using 1000 and it tends to be stated on the packaging and websites of the manufacturers Operating systems tend to use the 1024 definition. So a 64 GB memory card will be 64\\*1000^(3/10243) =59.6 with the 1024 usage 32 GB will be 29.8. So there is not extra storage but different units. The file system will use some space but it is not a lot."
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nlxig9 | How can USB-C standard be updated to now support 240W power delivery when the plug size and number of pins don't change? | Technology | explainlikeimfive | {
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"More voltage Quick Charge and USB Power Delivery aren't stuck at 5V like old USB devices were The current USB Power Delivery spec allows for 5, 9, 15, or 20 Volt supplies and up to 5A on the 20 Volt supplies for 100 watts of power The new spec supports up to 5 A at 48 V for 240 Watts which is handy for quick charging of laptops and the like. The cable is mainly limited to 5 amps of current because there are only a couple pins providing the power, but there's decent space in there so we can crank the voltage up a bit to sneak power through, just need to make sure charging stops if something gets wonky so buy good chargers",
"When two devices are connected, they negotiate power delivery. When a cable is plugged in, the power delivery pins are set to 5V, 2A, 10W. Then other pins receive a message that indicates the version of the protocol. In the first version, a device then sends a message that indicates which one of the five profiles to change to (the sixth was unused). These are specific power delivery amounts - 10W, 18W, 36W, 60W, 100W. The second version of the standard allows the device to select a specific voltage (5V, 9V, 15V, 20V), and then provides a way to fine tune the wattage from there. The messages allow 0.5W changes to the power delivered. The third version allows even finer grain control. The messages allow 20 mV changes to the power delivered. The fourth version, the new one, allows a larger range of voltages up to 50V to be selected. The other device has the opportunity to say it doesn't support the version requested. The devices will see if they both support each version, newest to oldest, until they can agree on a version or the basic 10W is used."
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nlyfxh | what is a NFT? Been seeing a lot in the news about videos and pictures being sold as NFT | Technology | explainlikeimfive | {
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"All you need to know is that NFT’s are terrible for the environment because of the exorbitant amount of energy used to create them. Stay away."
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nm2ps5 | How can digital currency cause blackouts? | Technology | explainlikeimfive | {
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"Bitcoin 'mining' can put a huge strain on a local powergrid, as people are trying to power more and more energy-hungry mining rigs. Basically crypto mining rigs are supercomputers that just try to solve math problems over and over again extremely quickly and at extremely high volumes. Enough people doing this on the same grid can pull too much power and cause a blackout."
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nm48yb | why do hdmi/usb cables top out at around 50 feet long, when buildings can literally have miles of ethernet cabling and function just fine? Aren't they all just ones and zeros? | Technology | explainlikeimfive | {
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"First, while there may many miles of ethernet cable in total, each length of cable between two connections is limited to several hundred meters at best. So there are not miles of a single cable even for ethernet. Second, 0 and 1 are symbolic representations. The actual way to encode the 0 and 1 are different for different protocols. So one might have \"0\" encoded as 0V and \"1\" as a 5V, others might use frequencies such as 99.9 MHz as \"0\" and 100.1 MHz as \"1\". These different systems have different performance characteristics by design. Third. Each system is designed for different uses. The higher performing uses are generally more costly in terms of the hardware needed and the amount of software needed (why ethernet has things like switches and routers costing tens to hundreds of thousands of dollars) USB is designed as a low cost, simple interface which is why it can be put on devices costing even less than $10.",
"Ethernet has a limit as well, approx 100m. It takes a lot of power to push a signal a long distance. So you need wires capable of supporting that much power... which means thicker cable, more shielding, etc... then you have to protect equipment that is getting full power just 3m away. So engineers come up with compromises. For ethernet around the whole building, there are switches, hubs or other devices in place to receive weakening signals and push out a quality signal for another 100m.",
"Voltage drop and loss is a thing and outside interference messing with the signals is a thing generally if your going to have long cables you'll have signal boosters and data compression along the length",
"Every wire - has a conductor inside it - mostly of copper. The copper used is of a high grade of purity - yet has some impurities in it. Hence even the good quality metal conductors / wires (like those used in hi-fi electronics / video cables) have some small amount of internal resistance to carrying the signal current across it. The \"ones and zeros\" are in the form of an electric voltage / current. When electricity encounters this resistance - it has to work to overcome it (and in the process generates a small amount of heat - which is why some wires heat up when high current is drawn through it). This work done by the electricity (signal) reduces its signal strength and over some distance this loss of strength is so much that the receiver gets either a partial / broken signal or of very low strength or intermittant signal or no signal at all. This leads to \"loss of functionality\" of the equipment / purpose for which the wire is being used. Hence the wire length is controlled based on the signal loss in the wire (and they use amplifiers / signal boosters when very long lengths of wiring is to be done). This problem is largely solved in \"fiber optic\" cables - where phenomenally long distances can be covered using FO cables without boosters. This is because of the very low resistance of the FO cables to transmitting light (where the \"ones and zero's\" are in the form of light pulses)"
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nm7g36 | how can NASA connect to distant planet rovers and far off satellites but there are still dead zones to cell phone coverage and internet connectivity on Earth | Technology | explainlikeimfive | {
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"NASA's satellites have a clear line of sight between whatever's on Mars or in space. On earth there's a ton of radiation interference and construction materials that block radio signals... cell signals are also based on towers on the ground. If you live 500 miles out in the woods and you're the only person there and there's no tower you're not going to get a signal.",
"The simplest reason is because NASA is using large, powerful radios and radio telescopes to do the communication. While cell phone communication is done with much smaller and comparatively weaker radios.",
"Because the communications are designed that way. Wireless communications involve tradeoffs of power, speed and latency. If you're willing to compromise on one aspect, you can gain in another. You choose encoding and power based on what you want to accomplish. Dead zones exist for cellphone coverage because it's not considered economically viable to close them. In rural areas, this is due to not wanting to build towers to service very few customers. In urban areas, it's mostly due to interference and obstructions. Again, these could be solved, but it's not worth the effort to do so - putting an antenna in a tunnel just so people momentarily passing through it can keep their connection isn't worth the bother. On the other hand, when NASA designs a rover for operation on Mars, it chooses power levels and encoding designed to operate at that distance because it would pointless to send a rover if you can't communicate with it."
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nm9tj8 | What exactly is a computer doing when it "installs" something? | Like is it just creating the right files and folders in the right place or is it actually creating a special link or internalized set of protocols within the system? | Technology | explainlikeimfive | {
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"Both. The files & folders all need to be copied to wherever they're supposed to be. But the operating system (usually) needs to know the program exists so that it can send it the right type of files. For example, when you double-click an image file, the operating system looks up \"Who opens .jpg files? Oh...it's this Photos app.\" In order for that to work, the Photos app had to tell the OS that it exists, what kinds of files it can handle, and how to \"talk\" to it. For most large software, the software is also using a lot of shared resources (both hardware and software) on the computer. Part of the installation process is the program figuring out what and where those shared resources are, installing any that are missing, and generally figuring out \"where stuff is\". It's like unpacking after you move in.",
"both most installers will do a few steps. - generate a directory if one doesn't exist - check for any file dependencies and fix as required - setup the shortcuts and file associations(so the system knows that x program handles the files made by itself.) - cleanup after itself and setup a uninstaller script for later use."
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nmcunq | When you convert an MP4 to a GIF, why does the file size often become larger? | When you convert a video with sound to basically a slideshow of pictures and effectively remove that sound from it, how would the file size actually increase? Shouldn't it decrease due to the smaller amount of data it now carries? | Technology | explainlikeimfive | {
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"Gif uses an extremely old and inefficient form of compression, not really made to deal with anything like a movie. Gif is best suited to low color moving artwork. It was never intended to be used for video, and any video usage is just showing that you can brute force things if you really insist and don't mind throwing obscene amounts of bandwidth at the problem.",
"No, a gif has MORE data because every frame is reproduced at full pixel resolution. Video compression saves bytes under the assumption that not every pixel changes frame to frame, so there could be a bunch of frames where only the pixels that DID change (or change beyond a specified threshold) are encoded - if a pixel isn't mentioned the player just leaves the pixel value from the previous frame as it is. Now every bunch of frames there'll be a \"key\" frame which IS a complete full resolution frame of every pixel which kinda resets things to normal. But a gif is a full resolution picture each and every frame."
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nmjdi3 | - What Is Radio Squelch? | I've tried asking a few people in person but I haven't really gotten a good explanation. Thanks! | Technology | explainlikeimfive | {
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"Radio bands are \"noisy\"...there's always some constant background signal from random natural sources. We hear this as static on the channel, particularly for AM broadcasts (most commonly in the VHF used for hand-held and marine/aviation radios). \"Squelch\" is a function that basically says \"shut the speaker off if the signal is below a certain threshold\" so you don't have to listen to constant hissing. It goes totally quiet until a signal above the threshold comes in, then it turns the speaker on and you hear whatever it was that the radio received. The potential issue is that you'll miss weak signals...if the squelch is set too high, a weak real signal won't be strong enough to breach the threshold and you'll never hear it. If it's set too low, even the background static overcomes it and you have to listen to the static all the time. So you need to set it right and, periodically, check it relative to current conditions to make sure it's doing what you want."
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nmoree | CPU chipsets | Is the chipset on the CPU or based on the motherboard? Like say an A320, is an older chipset for motherboards and cannot support ryzen 7's? Is it basically like a platform for CPUs, and the older chipset sometimes/most of the time accept the newer CPUs? | Technology | explainlikeimfive | {
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"> Is the chipset on the CPU or based on the motherboard? The chipset is physically based on the motherboard. They control communication between all the other components of the computer, allowing the CPU to work with everything else. Their design is done by the designers of the CPU (AMD or Intel) but are necessarily on the boards made by third parties. A given chipset is typically designed to be compatible with at least a few future generations of CPU, until they advance far enough that legacy chipsets can't support their features. This was an issue with AMD early in their CPU market share revival, as they were advancing quickly enough that chipsets had a very brief lifespan causing motherboards to have very narrow compatibility."
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nmsglc | How does a refrigerator work? | Technology | explainlikeimfive | {
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"Expanding gas cools as it expands. First law of thermodynamics. Inside a refrigerator is a reservoir of refrigerant. This is a gas that is compressed into a liquid, as a liquid is a good way of storing a large volume of gas. The system allows the liquid to slowly bleed out of the reservoir. Where it expands rapidly into a gas, cooling as it expands and circulates. Providing refrigeration. At the other end of the system, a compressor sucks in the gas and compresses it back into a liquid in the reservoir. As the system runs the compressor gets hot, and you can get condensation inside the refrigerator. The condensation can be redirected out of the refrigerator to drop onto the hot compressor, where it evaporates."
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nmwla6 | Why does 4K on youtube look better than 1080p on a 1080p monitor? Theoretically it should look the same because the monitor can only display 1920 x 1080 pixels max. | Technology | explainlikeimfive | {
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"More data All video is compressed, some more than others. When you ask for a 1080p video, YouTube sends you the file that has been compressed with settings that should looks pretty good on a 1080p screen, it won't be as good as the original and there will be artifacts you can pick out but it'll be about 1/100th the size which is good for their servers and your internet connection. When you ask for the 4k video it sends you the file which would look pretty good on a 4k screen, but to keep it looking pretty good they have to send more data which means its a bit closer to the original. Your TV/computer takes the 4k data and goes \"I can't use that, let me shrink it down\" and gets to take all that extra data to create finer details on the 1080p screen that weren't included in the much smaller 1080p video stream. If you were to watch your bandwidth usage this would make sense too. Streaming a 1080p video for an hour might be 2GB while a 4k video is 7GB. That 3x increase in data results in an increase in fine detail on the screen. For reference, uncompressed 60 fps 4k video should be around 5TB per hour so we really squish it down so you can get it without crushing the server, your network connection, and even your own computer's ability to process data.",
"The way Youtube works is that it allocates a certain amount of bandwidth to each quality of supported video. Since 4K allows much higher bandwidth than 1080p compression artifacts will be reduced and so the video will appear higher quality, even when shown at the same resolution.",
"There is a little dirty secret of common digital video: the image is sent in 3 \"layers\": a brightness layer, and 2 colour layers. You might think the 3 layers would be Red, Green and Blue but they're not. If you blanked out the two colour layers you would basically get a black & white image. .. However, for a 1080p video the colour layers are actually sent at 540p resolution. For every 2x2 of pixels the basic colour is the same and only the relative brightness varies. This is one of those \"your eyes can barely see the difference\" things that really saves disk space/bit rates, but has a permanent impact on image quality. This does mean, however, that a 4k resolution video would have 1080p resolution colour layers. When the 4k video is downscaled to 1080p you effectively have full colour information for each individual pixel. This can subtly improve image quality.",
"4K downscaled will always look better than 1080p because it is essentially averaging four pixels for ever pixel resulting in antialiasing and truer colors. Throw in data compression on videos and you end up getting less compression artifacts, as you have more “blocks” that are used for motion vectors in compressed video on top of the pixel averaging",
"People say bandwidth. But in reality, it’s because of chroma sampling. Digital vídeo usually is represented with 4:2:0 colorspace. That means that for every 4 pixels, the video file only stores information about how bright the pixel is for all 4 pixels. It only stores an average of the 4 pixels into 2 pixels for color information. Without getting into the whole chroma/luma Blackhole, a 4K video has twice the color resolution of a 1080p video when the 4K is scaled down to 1080p",
"It reminds me of when blue rays first came out and every time you watched a DVD they also had an ad for Blue Ray where they showed this stunning video of how great the quality was on Blue Ray and how crappy the quality was on DVD... but the thing is, it was on a DVD, so what they were really showing was how good the quality of DVD actually is when done properly. And that is the thing with 1080p, it is an amazing picture quality when used properly. So often the sources of media we get in reality via streaming and even expensive cable television isn't even proper 1080p, so the upgrades to 4K and even better quality of devices, isn't usually worth it (although 4K is standard now anyway, so you can't really pay less for worse)."
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nn2366 | What is physically different between a high-end CPU (e.g. Intel i7) and a low-end one (Intel i3)? What makes the low-end one cheaper? | Technology | explainlikeimfive | {
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"The process to make computer chips isn't perfect. Certain sections of the chip may not function properly. They make dozens of chips on a single \"wafer\", and then test them individually. Chips that have defects or issues, like 1/8 cores not functioning, or a Cache that doesn't work, don't go to waste. They get re-configured into a lower tier chip. In other words, a 6-core i5 is basically an 8-core i7 that has 2 defective cores. (Just for reference, these defects and imperfections are why some chips overclock better than others. Every chip is slightly different.)",
"Through history occasionally are devices where a high end and a low end were similar, just had features disabled. That does not apply to the chips mentioned here. If you were to crack open the chip and look at the inside in one of [these pictures]( URL_0 ), you'd see that they are packed more full as the product tiers increase. The chips kinda look like shiny box regions in that style of picture. If you cracked open some of the 10th generation dies, in the picture of shiny boxes perhaps you would see: * The i3 might have 4 cores, and 8 small boxes for cache, plus large open areas * The i5 would have 6 cores and 12 small boxes for cache, plus fewer open areas * The i7 would have 8 cores and 16 small boxes for cache, with very few open areas * The i9 would have 10 cores, 20 small boxes for cache, and no empty areas The actual usable die area is published and unique for each chip. Even when they fit in the same slot, that's where the lower-end chips have big vacant areas, the higher-end chips are packed full.",
"Most reply seem to focus on a process often called binning: disabling and rerouting defective or underperforming parts of a chip to \"act\" as a lower-spec config. However, this only works for specific lines of processors - in GPUs you often see this happening between the top-tier and sub-top tier of a line. For the rest of the range, chips are actually designed to be physically different: most chips are modular, cores and caches can be resized and modified independently during the design process. Especially stuff like cache takes up a lot of space on the die, but is easily scalable to fit lower specs. Putting in and taking out caches, cores and other more \"peripheral circuits\" can lower the size (and fail rate) of chips without needing to design completely different chips. & #x200B; edit: use proper term, no idea where I got \"harvesting\", binning is def. the proper term.",
"Most of the answers in this thread are incorrect, at least for the processors mentioned by OP. Intel Core processors vary in core count and cache size across the range, if not in actual architecture.",
"Guys, binning and architecture are not the same thing. Binning is used to determine the clock speed of a chip within the same family. The differences between i3 and i7 are not just limited to core/thread count. It's also architectural. These have different features on the die that determine their capabilities.",
"Imagine the job you want your processor to do is eating food. You know how I eat faster than you do? Part of that is having a bigger mouth (L1 cache), using bigger silverware (L2 cache), and having a larger plate (L3 cache). It's also about making sure that I'm taking the right size bites, constantly chewing because I make sure that the next bite is ready to go into my mouth by the time I'm done chewing (hyperthreading and pipelining).",
"In many cases, they are the same physical chip. The i3 just has defective sections turned off or slowed down. It's cheaper because selling a partially functional chip at a discount is better than just throwing it away.",
"Imagine a fancy bakery. Their main customers expect nothing but the best cakes possible, and they make them. Every so often, they'll mess up the frosting, and the entire cake isn't worth the price. So instead of throwing the cake away, they'll repackage it and sell it cheaper instead. Non ELI5: A CPU is just a lot of silicone transistors. And i mean a LOT. Billions even. Imagine a sausage made of silicone, about as wide as your palm, which then gets sliced into thin discs called wafers. There's multiple chips on one wafer. Silicone isn't perfect, and often, there'll be a crack or imperfection right on top of a chip. So instead of throwing the whole wafer away, they'll use what they have, and sell it cheaper. Silicone is ridiculously expensive, so they have to use every little bit they can. EDIT: It's silicon, not silicone, I'm baffled by how I messed it up",
"Usually i3/i5 are chips that aren’t good enough or has damages so it can’t be sold as i7. Design wise they are usually the same. Every die is tested and depending on its property it could become an desktop or a mobile chip with 4 to 8 cores with or without igpu. Usually the parts that aren’t used will be disconnected from the rest of the die, got some rare cases when they didn’t do it and you could upgrade cpu/gpu via firmware if you got lucky On a silicon wafer usually center yield the best quality, and especially in the corner the quality is usually lower resulting in more cpus where not all cores are working",
"Imagine tiny guys working in your CPU. The i7 has more tiny guys that can work at a faster speed, the i3 has much fewer that work at a lower speed.",
"i3-10100 die area is 125 mm², i7-10700 is 200 mm² so the i7 chip is almost twice as big. They use the space fore more cores and more cache.",
"To give a very simply answer, size. An i7 is much bigger than an i3. A CPU is made up of transistors, the more transistors you have, the faster your CPU. An i7 has way more transistors than an i3.",
"The basic differences between a top-tier CPU and a mid or low-tier one are going to be in clock speed, cache size and internal optimizations. Core count also is a factor, but not as much as one would intuitively believe. The lower-tier variants can't handle as much memory and their internal cache will be smaller, meaning it has to do more moving data around to work on it. If you want a very rough analogy, a core i3 is a base model, a core i5 has some nice options added like a turbo, and a core i7 is fully loaded with a better engine that has more power. In reality, the die is the same for all of them and what options are available are dependent on manufacturing- if they don't perform up to spec, some options and features are disabled and it's sold as a lower-tier chip.",
"Silicon area is expensive. Chip design is expensive. To make the numbers work, intel makes building blocks of chip parts and can \"print\" different versions. A 4 core chip takes up half the wafer as a 8 core chip and thus costs much less. There is a fixed cost to process 1 wafer. If you can squeeze more \"CPU\"s on a wafer they are cheaper to make. This is different than having a 16, 12, 10 or 8 core design of a family where 'bad\" cores are marked unused and sold as lower core count. Those chips still take up the silicon area of a 16 core chip, but instead of wasting them, the sell them with lower cores. The other cost reduction is \"binning\" where they test the chip at the full rated speed. if it does not pass they test it at a slower clock speed. And keep dropping the speed until it passed. These lower clocked parts are sold cheaper because they can't run at their design speed. There are lots of ways to save money once you made the chip. But silicon area is the main driving factor. Which is why they are always shooting for smaller transistor sizes. Not just because smaller transistors can reduce power use, but smaller process size means they can put more chips on a wafer.",
"Other than arbitrary pricing in a non-competitive market situation, the main thing that affects CPU pricing is the **number of non-defective CPUs per wafer**. CPU manufacturing starts with a big cylinder of silicon. That cylinder is cut into discs, or wafers. That wafer is then engraved (via secret magics) with as many CPUs as they can fit. They can't make bigger and bigger wafers, because that original cylinder of silicon still has to obey the laws of physics and thermodynamics and cools differently in the middle vs the outside. Imagine the difficulty of making a cupcake vs. a giant cake, where if you don't do it juuuuuuust right, the outside will be burnt while the inside is still raw. All else being equal, the more features a CPU has, the more transistors it requires, the more space it takes up on a wafer. More space = fewer CPUs per wafer. Furthermore, the more transistors a given CPU has, the greater chance of a defect being in there somewhere. Defects = > fewer CPUs they can sell per wafer = > higher costs. The main high-level feature differences between i3, i5, and i7 CPUs are clock speed, # of CPU cores, and size of the cache. # of cores and cache are basically directly responsible for the size of the CPU on a wafer. An i3 with 2 cores and 256K of cache will take up far, far less space than an i7 with 8 cores and 8MB of cache. Less space means more CPUs per wafer means less cost per CPU. Others have touched on the idea of binning where an i7 with 2 out of 8 defective cores is sold as an i5 with 4 cores or something like that, but that's really secondary. Being able to make an i5 out of a partially defective i7 helps them recover waste from a wafer full of i7s, but that's far, far less important than being able to get 2x as many i5s out of a single wafer of non-defective chips in the first place. As their manufacturing process improves, the defect rate gets lower and lower and they wouldn't have enough defective CPUs to market to the more price-conscious consumers. Binning is much more likely to be used to sell lower-rated CPUs in the same general class.",
"Think of the half watermelon you buy at the shops, it was cut in half because part of it wasn't suitable to sell, this could be your i3/i5... if you ONLY sold whole melons you'd have to throw away all the imperfect fruit when there's people who are happy with a half or quarter melon. That premo perfectly shaped whole melon is your i9/i10, definitely the target but hard to grow a perfect melon every time. In conclusion, you can't trust a pig with watermelon."
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nn3zi9 | Website names market. How can we buy and sell a piece of the internet? Who is the original owner, and how did they come to be in their possession in the first place? | Technology | explainlikeimfive | {
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"Basically, a non-profit called ICANN (The Internet Corporation for Assigned Names and Numbers) plays the central role. The origins go back as far as one researcher doing it. Then, the US Department of Commerce took on a role but almost everyone agreed it shouldn’t be under the control of one government. So, ICANN was set up and the Dept. of Commerce gradually gave up control. It’s not affiliated anymore. ICANN outsources the actual registration sales. So, different companies sprung up selling domain names. Over time, people made different proposals to expand the “top level domains” (like .com or .org) and we ended up with the early ones, national ones for each country, etc. There’s a Wikipedia page with which are which: URL_0 Eventually, ICANN decided the top-level domains could be anything and opened them up too. Nowadays, anyone who pays a (I think $200,000) fee can own their own TLD and limit it however they see fit. So, that’s why now, there’s URLs ending in things like like .cool or whatever."
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nn9rja | How is HTTPS any more secure than HTTP, if literally anyone can implement it? | If I can just go grab free certificates online and edit my own server configuration to serve a site over HTTPS, how does that add any security at all? I thought the security was because there was some vetting process that served as a barrier to entry. | Technology | explainlikeimfive | {
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"It secures the data between you and the webserver, so someone in the middle cannot see the contents of the page being sent or received (like when you're sending your credit card number). It also verifies that you are the site you say you are. It does not prevent someone from registering a site that's a common misspelling of a popular site and hoping people not notice.",
"> If I can just go grab free certificates Because only you will have the private keys to those certificates. Your public keys will be just that -- public, anyone can download them and view them, but those can't be used to impersonate you. If someone ever gets ahold of your private keys, then yes, they will be able to pretend to be you and HTTPS is useless. Keep your private keys safe! Never send them over an insecure connection like email, or store them unencrypted.",
"> If I can just go grab free certificates online and edit my own server configuration to serve a site over HTTPS, how does that add any security at all? I thought the security was because there was some vetting process that served as a barrier to entry. Yes there is still a vetting process. Go online and try to get a certificate for URL_0 , you will not be able to.",
"Just to add some additional info on top of what has already been said, bear in mind that even if you were able to acquire a legitimate certificate for URL_0 , people wouldn't be going to your server when they try to go to URL_0 . The DNS for URL_0 tells people which IP addresses to use in order to actually reach Google, and you wouldn't be listed on their DNS records. If you had physical access to someone's PC or their immediate network, you could override that DNS in various ways but you couldn't do that to every user on the internet. So there are several pieces here: - Public DNS to route people to the right servers. - Certificates issued for the domains by a trusted certificate authority that vets domain ownership. - A small set of trusted certificates authorities installed with common operating systems like Windows, macos, and Linux. - Private and public keys to ensure safe means to encrypt data across an open and untrustworthy internet."
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nnd945 | Why are phone batteries measured in mAH and car batteries measured in kWH? Why aren't the measured the same? | Technology | explainlikeimfive | {
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"You calculate Wh by multiplying the voltage of the battery with the capacity in Ah. Phone batteries all have the same voltage, so you can just look at the (m)Ah rating. A 3000 mAh battery always has more energy than a 2500 mAh battery. EV batteries have different voltages, depending on the make and model, so the Ah rating alone doesn't tell you much. A 200 Ah/400 V battery contains more energy than a 250 Ah / 300 V battery.",
"One is milliamp-hours, and the other is kilowatt-hours. Milliamps are units of *current*, whereas kilowatts are units of *power*. Power is *current* times *voltage*. Since phone batteries have more-or-less constant voltage, it doesn't really matter much if you choose to measure output in terms of current or in terms of power -- you can convert from one to another simply by multiplying by the voltage of the battery. In fact, for phones, it's more natural to think in terms of \"current draw\" rather than \"power expended\". Otherwise, the units are chosen for convenience (phone batteries have much less capacity than car batteries, so this avoids having 0.0005 kWH phone battery or a 40,000,000 mWH car battery).",
"They're measuring storage capacity vs work capacity. If you're buying a car battery and you're paying attention to power, you might want to power other things, like extra lights or a fancy radio. In that case, you want a battery that can power these things. To do that, watts are the unit you care about. The amount of work a battery can do. But for phones, you care about how long it can keep your phone running. That's mAH. That's what that measures",
"I would suspect it relates a bit to how the batteries are used. For example, a phone battery or a AA battery would always provide about the same voltage. You charge them with a single voltage charger and so the amp-hours of a battery relate directly to the storage of the battery. Since the voltage doesn’t change, the amount of amps is the only thing that changes power (watts). On a car, you can slow charge it from your regular house outlet (110 volts), from a level 2 charger (220 volts) or from a super charger (400 volts). Because the voltage changes, charging the battery is not directly related to only the amperage of the charge. 15 amps on a 110 volt outlet is only half the power of 15 amps on a 220 volt charger. I suspect, In order to make it easier for people to understand, they use watts instead. 15 amps on 110 volts is 1.7 kW, and is the same as 7.5 amps on 220 volts. It’s easy to compare how quickly your car is charging based on the wattage because it’s a scale that works with any voltage. 5 kW will always charge faster than 1 kW no matter what voltage you are using. And if you are going to use kW as the unit for understanding power for charging, then it makes sense to rate the batteries in kWH. It’s a unit that can be understood in relation to charging it."
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