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n2pow8 | How did they achieve realistic movie CGI in the 1990s when computers back then were primarily 486/Pentium based and 3D acceleration came later? | I've seen movies like Jurassic Park and Deep Impact, and am wondering how they achieved such graphical feats that still look realistic by today's standards when computers then are achingly slow compared to what we have nowadays. | Technology | explainlikeimfive | {
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"Jurassic park, specifically, used practical effects rather than just CGI. Those dinosaurs were either puppets, animatronics, or dudes in costumes.",
"Proper computers had accelerated graphics even then --- I think people mostly used SGI for that. More importantly, this only matter for _real-time_ graphics --- when making a movie, rendering the scene can take much longer than the scene itself, so you can have a slower computer (you also have many of them and render different frames in parallel).",
"The rendering (the process of making the actual image itself) times for cgi for films in that time would be weeks, months, for a single scene, now those times would be drastically reduced to produce the same images. But a big help, particularly for Jurassic Park, was that the cgi was mostly to enhance the animatronics and puppets, rather than being the entire final image."
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n2pvht | how can car airbags inflate when they’re under a solid plastic dashboard? | Technology | explainlikeimfive | {
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"The plastic has lines on the inside that you can't see that are significantly weaker so it will split apart and let the airbag out. [There's a Slow Mo Guys video showing airbags deploying]( URL_0 ) and you can see that the cover on the front of the steering wheel breaks into two flaps that move out of the way. The plastics have intentional breaking lines built into them so that you don't end up with a chunk centered over the airbag just getting blasted into your face by the small explosion in your dash",
"Because they are explosively inflated with a pyrotechnic device. They blast the plastic cover panel out of the way as they inflate."
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n2wfst | what is an NFT | Technology | explainlikeimfive | {
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"NFT, known as Non-fungible token is fundamentally anything that isn't a currency. Let me put this in 5 year old explanations for an ease of understanding. I'll start with what is \"fungible\", because that's our keyword here. Fungible is essentially anything that can be easily replaced. For example, a penny is considered fungible because it can be easily replaced by another penny. So when we talk about non-fungible, we're talking about something that is very unique. Something that cannot be replaced. For example, say you created an art picture. You didn't copy anyone(more or less) and you made it with your own two hands and a creative unique mind. It's unique. Non-fungible. It cannot be replaced. Sure, you can copy and slap it on t-shirts or anything, but it wasn't originally created by you. To certify that an artwork you created is unique and an original, we slap a tag on it that says \"hey, this art right here is made by this person and it is an original!\". And that tag stays on it \"forever\". This tag is essentially an NFT, A Non-Fungible Token. As for why this exists, well I'm not exactly certain but I can imagine it's so we don't get fooled with fakes with modern art or something digital. Let me explain. Imagine Leonardo Da Vinci in modern times with all this cryptos and technology. Everyone loves Leonardo's work and would spend a pretty penny for his work. He creates the Mona Lisa and he puts a Non-Fungible Token on it. That Mona Lisa is now very unique and an original because of that NFT. Now imagine someone simpleton decides to make his own Mona Lisa and imitates Leonardo's work down to the last stroke. This simpleton has created a very identical Mona Lisa that you can say that this simpleton's Mona Lisa can be passed off as Leonardo's work and make tons of money off of his name. BUT WAIT, that identical Mona Lisa doesn't have a NFT and because there already is a Mona Lisa that already has its own NFT that belongs to Leonardo, the identical one can easily be known as a fake and cannot be sold(or at least for the same value the original would). And also we'd probably applaud and then berate the simpleton for being a Leonardo copycat because society and technology. So yeah. NFT. It doesn't have to be art specifically. It can be anything that's unique(hell even a tweet apparently). The value just depends on a variety of factors.",
"imagine a jpeg with a Bitcoin attached to it. Not a literal Bitcoin that has a known monetary exchange rate, but a digital code that only your jpeg has. So... like a watermark. A unique watermark on a jpeg. Now you can claim that your jpeg is rare and valuable, and sell it to a speculator for tens of thousands of dollars. Oh, and generating that unique watermark uses more electricity than a small city."
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n36gyk | Why do some power cables not have a ground prong? | For example, my electric shaver cable only has two prongs. Without a ground prong, doesn't that mean it could shock me if something went wrong with the electricity? | Technology | explainlikeimfive | {
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"The ground wire is meant to save a user from getting shocked when the metal outside of something gets electrically charged. This is not possible in case of an electric shaver since the outside is mainly made out of plastic and the blades are (probably) isolated from the electrical bits.",
"The ground wire is supposed to connect to any pieces of metal you might touch on the appliance. But your electric shaver is most likely made of plastic and therefore there is nothing to connect the ground wire to. Similarly there is no way that an issue with the wiring in the shaver will cause the electricity to flow to your body because everything is made of plastic.",
"All of the other responses give the correct technical answer. The term used to describe such tools is “double insulated.”",
"It's not always necessary. If your shaver has a plastic case that's considered insulation enough, and there's no sensitive electronics inside needing it either."
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n3az6b | Why does a rechargable battery has a limited cycle/lifetime. | Technology | explainlikeimfive | {
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"It depends on what type it is. In some you accumulate crystal errors (lithium), others corrode (lead-acid) and so on"
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n3bj1a | Why are most cheap PCB’s and circuitry green colored | Technology | explainlikeimfive | {
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"Green was the coloration given to the conformal coating that covered the first fiberglass boards. There were also some other colors such as brown or orange, but green won out as the most recognizable and aesthetically pleasing default. But, it doesn’t really matter. It is just a dyed coating, it could be any color. These days they are green because people expect them to be green, no other reason.",
"Fab houses don't charge extra for green, and there is no extra wait time. So, the cheapest & fastest way of getting a PCB is to go with whatever they are tooled up for, which is green. Other colors, they might only produce once a week, depending on demand, so they charge a premium for the tooling change, and you may have to wait. Marketing folk on high end gear think it's worth the extra wait & cost to stand out from the crowd, but color has no impact on performance.",
"The green is from solder mask, it just gives it some aesthetic over boring beige. Solder mask is required to keep the solder from spreading for surface mount components, and they tossed in some dye. It became just kinda tradition from there. Of course like you said you can get other colors, and if you send in your own circuit design to a fab shop to make the boards for you they usually have a few colors to choose from. Internally at big circuit manufacturers they would sometimes use different colors for coding -- green is just a regular old board ready for sale while red was used for prototype boards that shouldn't be sold etc."
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n3dt21 | How does the undo feature work in collaborative applications such as Google Docs? | Technology | explainlikeimfive | {
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"[Chuktropolis Welling Moran of UC San Diego]( URL_3 ) explains that different programs implement an undo feature in different ways. Recently, the undo button has evolved to accommodate collaborative text-editing systems, such as Google Docs. So what goes on under the hood? Before we learn about how a computer keeps track of undo, we must understand what a stack is. A stack is a way of storing data, where new data is added on top of old data, and the most recently added data will be removed first. This is analogous to a pile of books: the most recently added book will be on top, and it will be the first to be removed. Many implementations of undo use stacks. [Max Lynch,]( URL_0 ) the CEO of Ionic Foundation, describes the undo function as a stack of operations that the user has performed. In other words, it is the \"history\" of the actions the user has taken. Whenever the user does an action, we add the action to the undo stack. When the user wishes to undo something, each action is taken out of the undo stack. Think back to the pile of books but now imagine someone wants a book in the middle. They wouldn't want to topple the pile to get the book from the middle. Instead, they would remove each book off the top of the stack, undoing what they did, until they reach the book they need. Collaborative applications implement the undo feature in a more dynamic way using stacks. In the case of [Google Docs]( URL_2 ), the program keeps a copy of the document on each user’s computer, and sends each change a user makes to a central server. The central server then sends a signal to all of the other users to implement the change on their copy of the document. When someone undoes an action in Google Docs, the local stack of actions on that user’s computer removes the last action. Then, that change is sent to the central server, and the data on all copies of the document are updated to reflect the undo action. The main challenge that arises when implementing this is users making changes at the same time. This could cause a number of problems, including changes being applied to the document in the wrong order. To mitigate this, [Google Drive Blog]( URL_1 ) states that Google Docs implements a technique called operational transformation. In his academic [paper]( URL_4 ), Mandeep Kaur describes operational transformation as an algorithm that “transforms” the changes being received from others relative to each user’s document. This transformation is done so that the change can be completed without editing the rest of the document. The inner workings of this algorithm are very complex, but it essentially ensures that when users make simultaneous changes, these changes (including undo) happen in the correct order. TLDR: the undo function is a list of actions that is stored on the computer. When the user either clicks on the undo button or does “Ctrl + Z/Cmd + Z” on their keyboard, it removes the most recent action in the list. In collaborative applications, there is a local list of actions on each user’s computer which can be used to undo the latest action of the user. Processes such as Operational Transform apply these changes in a central server and merge actions to create simultaneous undo actions."
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n3j3i2 | How exactly does burning cds work especially when you do it from home? And why does a scratch affect how the cd reads the information? | Technology | explainlikeimfive | {
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"When CDs are pressed commercially, they actually punch tiny tiny holes in the gold foil, and those punches represent the information that becomes the music. When you burn a CD at home, you can’t punch holes, but the laser in the CD burner affects the foil and burns it and discolors it, so that it looks just like a hole to the CD player. A scratch in the plastic or in the foil destroys some of those holes, or it makes it harder for the laser to see them clearly.",
"A CD is made up of a reflective metallic film deposited on a transparent plastic substrate. A CD burner has a high intensity laser that can physically alter the properties of the metallic film, specfically change the phase of reflected light by etching microscopic grooves into the reflective metal film. A disk reader can later shine a low-power laser light on the rotating disk, then 'read' the phase of the reflected light, thus reconstructing whatever data was written on the disk. A superficial scratch that only penetrates the plastic substrate will simply cause the light to bounce off and reflect away from the reading head and thus corrupt the data. The data could still be salvageable, and the disk may still be repaired. A deeper scratch that reaches the metallic film will irreversibly corrupt the data because it will mess with the grooves created by the burning laser."
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n3jxbv | How is Wi-Fi "shared" to multiple devices? | With a wired connection, it seems pretty straightforward. Multiple devices are connected via multiple wires to a home router. With a Wi-fi connection, how do multiple devices connect to the home router. Is it like multiple devices are connected to a one large wire (that is the air)? | Technology | explainlikeimfive | {
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"Multiplexing. There are lots of different ways multiplexing can be accomplished, one example is time sharing. In other words, each device gets multiplexed for a certain time slot (often small enough time slots as to be imperceptible to us; it can be fractions of fractions of a second) in order to share the load of multiple connections at once."
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n3k4yx | how does binary work? I've had it explained to me twice at my current age and I didn't get it... | Technology | explainlikeimfive | {
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"Its just a base 2 number system. We have a base 10 number system 0-9, and when you reach the end of the system you add a digit and start over. 9, 10,11. Binary does the same thing, but you only count to 1. 0,1,10,11,100,101, etc."
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n3l6vf | How Does a Computer Know Where a File Is after I Save It? | Technology | explainlikeimfive | {
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"A computer keeps track of files similarly to how we put papers in a folder and put the folders into a filing cabinet. On your operating system, like Windows or macOS, files are put in a folder, which can be placed in another folder and so on. [As Chris Hoffman explains on HowToGeek]( URL_0 ), the largest of all these folders is called the root folder. Everything on your computer is inside the root folder (or inside a folder inside the root folder), and it’s where the computer starts when it goes to navigate to a file. In another [HowToGeek article]( URL_1 ), Chriss Hoffman states that our operating system uses a file system to track all those folders and files. Before describing a file system, we need to understand how memory works. Memory can be thought of as a line of boxes. As Carried Annie explains on [Crash Course]( URL_3 ), each of these boxes represents a specific location in the physical memory of a computer, like a few magnets on a hard disk or a cell in a solid state drive. How memory is physically stored isn’t that important for us though, because our computer handles converting from imaginary boxes to memory locations. Most files are too big to fit in one box, so we need to break up the file into pieces small enough to fit in a single box and store all those pieces across many boxes. In his [public textbook on Linux]( URL_6 ), Lars Wirzenius explains that computers create a list of boxes that a file is stored in to track files that span multiple boxes. We call this list an inode and every file has its own inode. This isn’t the sole purpose of an inode, as inodes also store who created a file, when it was created, and other properties. Finally, each inode has a unique number, called an inode number. These inode numbers allow us to keep track of all the different inodes. Folders work differently on a file system level. As Remzi H. Arpaci-Dusseau explains in his [textbook on operating systems]( URL_5 ), What we call folders are actually a certain type of file called a directory and they have an inode of their own. These directories are similar to phone books. A directory is a list of inode numbers and names of the files they correspond to, just like how a phonebook is a list of phone numbers and names of people that they correspond to. For example, the documents directory would link inode #12352 to passwords.txt the same way a phonebook would link 911 to emergency services. Arpaci-Dusseau also explains that the crux of this system is that directories can contain another directory, which allows for the creation of subdirectories and a tree-like structure for all the files on the computer. In other words, directories tell us what inodes to look at and inodes tell us what boxes to look in to find the file. To go through an example, let’s say I have a “passwords.txt” file stored in the address “/Users/Bob/ Documents/password.txt.” To get to passwords.txt, the computer starts in the root folder and looks at the root directory inode to see what boxes it should look in to find the directory. Then, the computer goes to those boxes and reads the data of that directory to find the inode number for the Users folder and navigates to that folder. The computer then repeats this process until it gets to the Documents directory and locates the password.txt inode. Using this inode, the computer finds all the boxes passwords.txt stores its data in and loads the data from those boxes. For further information, please check out this [infographic ]( URL_2 )and [video]( URL_4 ) my friends and I made about file systems."
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n3ma83 | how exactly is silicon programmed in Computer chips? | Like, who went, oh yea let me just put some electricity into this rock and make it think for me? I like to think I know my way around a computer but at the end of the day how do manufacturers go from metals and rocks to cpus? How do you make electricity make silicon think? Thanks! | Technology | explainlikeimfive | {
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"You don't make it think. It's a machine just like the ones that you more intuitively understand. The front gear on a bike pushes a chain that pushes the rear gear which pushes the ground. Similarly, the semiconductors in a computer is the same way. We found that by doping silicon, they would have specific properties when you apply electricity, much like how metal has specific properties when you apply force to it. Even then, we didn't use silicon as the first computer. Much earlier than that we had mechanical devices. You can look at mechanical calculators that function similarly to current day calculators, but they relied on a bunch of gears and whatnot. After that there were things like vacuum tubes and magnetic core memory. Only later did silicon chips become usable. Like any complex machine it's an iterative process where you come up with little pieces that do what you want (burn gas in a container to generate power, use a system of gears to magnify force) and put them together to get a big complicated machine (a car). So how do computer chips work? You can dope silicon to add certain other atoms into it and change its properties. There's a type that has more electrons than it wants (called N-type) and a type that has less electrons than it wants (called P-type). The interesting thing is that when you stick pieces of these together they behave in unusual ways. A piece of p-type next to an n-type makes a one way gate for electricity, called a \"diode\". Layering three of them together either PNP or NPN makes a transistor. It's like two diodes stuck together opposite ways, so electricity can't flow through. The catch is that if you apply voltage to the middle piece, it messes with the behavior of the material so that it allows electricity to flow all the way from one end to another. This makes it work like a switch. It's just that instead of flipping a physical switch like you have for your house lights, you're applying voltage to a wire. The important thing here is that you can turn voltage off and on a lot faster than flipping a physical switch, and you can use one switch to trigger another. By arranging these switches (transistors) in different ways you can get them to behave in all sorts of complicated ways, such as having them do math or play Mario Bros.",
"Premise is really simple: you have an item (semiconducting cell) that has 3 electrical contacts. You can pass current through contacts 1 and 2, and it conducts the circuit. You apply voltage to 3, and it stops conducting the circuit. This was first done with much larger items than the modern nanometer scale semiconductors, you could make a primitive semiconductor as large as your fist from pretty basic materials. From a large number of those semiconductors, you can construct a system which can complete certain logical operations given certain input. So.... when you just have a basic logical unit in a microchip, which is essentially a very large array of semiconductors, it's pretty useless on its own. you need the \"firmware\", which in its most basic state sets it up to be ready for general-purpose work. Then you can use it to read instructions from a program, and execute them, putting the result into an output buffer memory, from which you can extract it and deliver to the next component, like a display. Tldr: you have a very basic cell which can switch \"on\" to \"off\" and back based on how you push electrical current through them. Put a giant pile of them together, push current in a certain pattern, and you'll receive a different pattern in output. Set it up to manipulate your input patterns in different ways, and you got a computer.",
"* The most important breakthrough for computers was discovering that every kind of logic decision and every kind of math problem can be broken up into a very long series of yes or no questions. * Google \"George Boole\" if you want to know more about how that works. * After that, it was matter of getting a machine to make those yes or no decisions based on some sort of input from a user. * At first, this was done mechanically. * Google \"Charles Babbage\" to learn about that. * At the same time scientists were playing around by shoving electricity through every different sort of material they could find. * They found out that you can change the way certain metals behave when you apply cleverly apply electricity to them. * These are semiconductors. * They figured out you could turn them into little electrically controlled electricity gates. * That is, when you apply electricity to one side, we'll call it the front, nothing happens. * But if you also apply electricity to the another side, it will let the other electricity pass through. * Boom! You have a device that can make yes or no decisions."
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n3mhe1 | why do dish washers take 3+ hours to clean dishes but the washing machine and dryer takes less than 2 hours to clean clothes? shouldn’t clothes be more difficult to clean? | Technology | explainlikeimfive | {
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"Dish washers used to be faster. Recent regulations on the amount of electricity they can draw slowed them down. A big chunk of time is also the heated dry time. So they do both, wash and dry, in about the same time a load of laundry is washed and dried. Thing Explainer by Randall Munroe has some excellent diagrams and explanation of how both dishwashers and laundry machines work.",
"The washing machine was designed to allow the clothes to clean and dry themselves by rubbing together really fast and spinning them. The friction heats them and uses the soap efficiently. You can’t very well rub glass dishes together so you’ve gotta use powerful jets which pass over and through the dishes more than enough times to sanitize them and protect the company from a food borne illness lawsuit."
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n3mmk4 | can a airplane pilot put the plane in autopilot the whole time they fly? | Technology | explainlikeimfive | {
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"At the very least, takeoffs would still be flown by hand, since (to my knowledge) many jet's autopilots won't engage unless you are on a somewhat stable heading and are closely trimmed (flight controls set so that minimal yoke/sidestick pressure is needed to maintain the current path) to your current flight path. Landings are also often flown by hand after a certain altitude, since automated landings can be very firm and not every runway and plane is certified for automated landings down to touchdown.",
"Airplanes today can be flown mostly on automatic with my Pilot father admitting that many airlines consider pilots to be glorified troubleshooters. You're there in the cockpit in case something goes wrong. Many pilots prefer to fly manually, mostly takeoffs and landings, because its good experience and a human can react faster and adapt better than the computer to many changing circumstances. But many airlines, particularly in the far east, disagree and insist that pilots push the auto-pilot button almost the second the airplane is airborne because they trust the computer more than their own pilots.",
"Yes, and no. Yes that most of flight is done by autopilot. No that take off, landing, and any emergency is handled by the human pilot currently"
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n3vbro | How do wireless chargers work? | Technology | explainlikeimfive | {
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"There are two metal spirals: one in your phone and one in the wireless charger. The one in your wiresless charger spins the electricity around the spiral, which creates a strong magnetic charge because electricity and magnetism are inseparable. Since the spiral in your phone is close enough, it causes a \"sympathetic\" electrical charge in your phones spiral, since the magnetic charge also makes an electrical charge. This is why they're pretty inefficient: they need to hop between a bunch of material and the transfer of electricity this way requires way more power that a traditional charger.",
"Magnetism is a field of electrical charge. When designed properly, a magnetic field can be used to cause electrical charge in another object. This can happen with, for example, spark plug wires for your car's engine. Improperly routed, or damaged, wires can cause an electrical charge in a nearby spark plug wire when the magnetic field collapses (they build and collapse every time the spark plug fires).",
"Well first, know that everything that has a moving electric current produces a magnetic field. That includes the wires in your phone, the neurons in your brain, and bolts of lightning during a storm. But also, a changing magnetic field produces an electric current. So knowing this, it would make sense we could figure out a way to send power from one object to another without connecting them by wire. So first, we take some wire, and we make a coil with it, [like this]( URL_2 ). This is called an inductor. However, since we want these to fit in phones and stuff, we'll make the coils flat, [like this]( URL_3 ). So now, we have our inductors. We'll attach one to the chip that controls the battery re-energizing process, and attach the other to a similar device that will detect when another inductor is in range, and allow power to flow through the coil. Now that we have everything set up, we'll set our phone down on the energizing pad. The system on the energizer and the one in the phone will both activate, and electricity will start flowing through our energizer inductor. As the electricity moves through the wires, a magnetic field curls around the wires in a certain way. Since there are so many turns to the coil, these curls add up, resulting in a big magnetic field [like this]( URL_0 ). The other coil is inside the range of this field, and that causes electricity to begin to flow through it. As long as electricity continues to flow through the first coil, the energy put into it will be transferred through the magnetic field, causing electricity to flow in the second coil, and your phone's batter will be re-energized. If you want to know more in detail about Induction, check out [SciShow on Youtube]( URL_1 )."
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n41us3 | Why does Adobe need to update their products so much? | Technology | explainlikeimfive | {
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"By adding features, optimizing performance and such, you potentially introduce new bugs into a program as a developer. A fixed bug can even cause new bugs to appear. It's a vicious cycle that never truly ends. Especially in very complex software like the Adobe Suite."
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n4amrg | How do we record sound and what separates a good microphone from a bad one. What makes a good microphone good? What parts actually decide this. | Technology | explainlikeimfive | {
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"Sound is a pressure wave moving through the air. A microphone converts that pressure wave into an electrical signal. It's essentially the reverse of a speaker. In a microphone there is a diaphragm attached to a metal coil, and the coil is set inside a magnetic field. The diaphragm vibrates according to the pressure of the sound wave, that vibration causes the coil to move, and the movement of the coil inside the magnetic field produces electricity. The 'size' and 'speed' of the electrical signal produced corresponds to the original sound wave. There are different types of microphones but that's the general idea for what's called a dynamic microphone. A condensor microphone is a refinement of the same idea but instead of a diaphragm moving a coil, the diaphragm itself is conductive and it's movement is converted into electricity via capacitance. What separates good from bad depends on what you need to do. In general you want a microphone that can accurately capture the frequency range of the sound at a sufficient volume level from a suitable direction and at a suitable distance. Some microphones pick up sound from a narrow angle, and others from a wide one. That's a whole other topic called cardiod patterns (because a graph of the microphones 'best working area' looks a bit like a heart). Some microphones need to withstand a lot of volume before they distort the recording and others need to be much more sensitive at low volume levels. That's one big difference between dynamic and condensor microphones. So then the parts that decide what's good depends on the particular application. But in general it's the sensitivity of the diaphragm (how well it moves according to the different sound frequencies) and the geometry of the diaphragm (what range of angles it can keep that sensitivity at an acceptable level). There's really no one answer. What if you want a microphone that works well from a distance and a wide area? Well then you're going to pick up all sort of sounds that you don't want. What if you want a microphone that works best when it's close to the sound source? Well you better hope the sound source doesn't move or hugely increases it's volume. Hopefully that's a useful answer."
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n4atlx | ; What was 'vertical hold' all about? | The image on the TV of my childhood would sometimes start to scroll up or down. You had to adjust a tiny knob to stabilise the image. Why. It no longer exists as a problem or solution. What changed? | Technology | explainlikeimfive | {
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"CRT TVs worked by shooting a beam of electrons at the screen to light up pixels, that beam would go from left to right, then drop down a row, left to right, drop down a row, and so on until it got to the bottom of the screen when it would pop back up The signal coming in was timed so that it provided each row in the time it would take the beam to cover the row and provided a moment of blackness at the end of the frame to let the beam get back up without mucking up the image During this blanking pulse there was a Vertical Sync pulse to let your TV know it was time to start a new frame, its hardware would try to pick this up and sync on it, but if the TV's internal reference gets too far off then it won't be able to sync on this signal so you have to fiddle with Vertical Hold until the Vertical Sync signal was back in the window the TV could lock onto.",
"Old TVs were made with analog components that weren't very accurate, and would change with time and temperature. Some of these components were used to create timers to decode the TV signal. If these timers drifted too far off what they should be, the TV wouldn't display the picture correctly anymore. So the user would have to adjust the circuit until the timing was close enough to being correct again. Once TVs moved to digital circuits internally, the timing could be super accurate, and no longer needed to be adjusted by the user. Now, analog signals aren't even broadcast anymore, so it's a completely obsolete issue.",
"They had a cathode ray tube (CRT) that fired electrons at a phosphorent screen in a specific sequence to create an image. The vertical and horizontal holds were minor calibrations to help sink that up. CRT's are not longer used in TV's.",
"Old tube tvs made a picture by shooting a beam of electrons onto the back of the screen. The beam was aimed by using electromagnets. This would steer the beam to scan from top to bottom and left to right very fast creating a picture. If the timing was off then the picture would begin to scroll. Later tube tvs could adjust themselves so vertical scrolling was less of a problem. Now it is no longer needed because we use lcd and led screens that refresh all the picture all at once in most cases.",
"With analog TV, you get a stream of information that your TV converts into a beam of electrons that it scans back and forth across the back-side screen of your television. It goes from one end to the other, horizontally, then moves down slightly, and repeats, until it reaches the bottom of the screen. The timing of this sweeping beam of electrons has to match the timing of the analog TV signal it is receiving it it will not draw the picture correctly. But these old TVs also did not have very precise controls, so provided the ability for users to manually adjust them. 'Vertical Hold' was one of these controls. Eventually analogy TVs became advanced enough that it could automatically make sure the timing of the electron stream matched that of the analogy signal, eliminating the need for horizontal or vertical hold. Digital signals eliminates the problem altogether, as it provides explicit pixel-by-pixel information about how to draw the image.",
"Analog TV depended on a vertical sync signal to mark the top of each video frame. Because the signal could suffer from interference, each TV also contained a pair of oscillator circuits (“phase-locked loops”) that “guessed” the timing of the next vertical and horizontal sync, to provide stability of the picture if that sync pulse was missed. If the “guess” is close enough to an actual sync pulse, the TV uses the sync pulse. Otherwise it substituted its own oscillator for the frame timing. The vertical (and horizontal) hold knobs provided fine adjustment of the oscillator timing, allowing you to match the oscillator’s frequency and phase to any actual TV signal. Without sync, frames could start drawing in the wrong place on the screen- you’d get a black bar between the bottom of one frame and the top of the next. Adjusting V-hold involved four steps- try both directions to see which direction slowed the “rolling”, then turn it so it stopped completely (matching the frequency of the sync pulses), then nudge it in one direction or the other until the top of the frame was at the top of the screen. The TV would “lock” back into the real sync pulse and you’d be all set. A last optional step was to “center” that adjustment a bit so it wasn’t right on the edge and wouldn’t lose sync as easily the next time an airplane flew overhead. Digital electronics meant a TV could do all this on its own without a knob.",
"Originally, as others explained, the picture was drawn on the screen line by line and the tv needed to know when to start over at the top left corner. It also had to know when to start each new scan line. So, there were two kinds of pulses that kept the tv drawing the picture on its screen the way the tv transmitter intended-one pulse to start a complete new screen, and a different, smaller pulse to start a new scan line. The vertical sync electronics detected when the tv signal had the little blip that indicated to start a new picture at the top left. The vertical hold adjustment changed how sensitive the vertical sync circuit was. It had to be in a certain range because otherwise it would see the new-scanline pulse a a new-screen pulse or else would randomly trigger on various parts of the signal. The vertical sync electronics would sometimes slightly change adjustment with temperature, age, etc and get to where the vertical hold stopped working right. The vertical hold adjustment was so the people watching the tv could fix it without having to call a repair tech. And yes, this is oversimplified and disregards a lot of stuff but this *is* ELI5 :-) Edit: I didn't answer why this became a non-issue First, electronics got better and the TV itself could auto-adjust the vertical sync. This was very common on TVs made in the last 10 or more years of analog television Second, newer ways of sending the picture weren't based on the line by line drawing of a screen but more of a 'send each new frame as a .gif and display it on the screen' approach"
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n4dqet | LDAP (Lightweight Directory Access Protocol) | Technology | explainlikeimfive | {
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"In IT a directory service stores information about objects in a given organization. The organization does not matter, it could be a business, or your home network. Typical object types are users, computers, and groups. Objects have information associated with them stored as attributes. A user object has things like first names, last name, password, logon name, address, etc. Some attributes are required, some are optional, and some are automatically filled ( like date and time stamp of last password change.) LDAP is a standard protocol used by directory services to allow software to query information in the directory. An LDAP compliant directory service stores object information in a certain structure and uses standard attribute names for predefined purposes. They listen for connections on standard ports and support a standard syntax for performing queries. Say I am a software developer and I want to allow my customer to authenticate users with their standard network accounts, and I want to pull in information about the user for their profile in my applications, or I want to check against group memberships to see if they are authorized to access a certain part of the application. I can write my application to support LDAP, knowing pretty much all major companies use some kind of LDAP compliant directory service, such as Microsoft Active Directory, Red Hat Directory Server, or Amazon's directory service. I don't actually need to know which directory server they use, I just write my app to follow LDAP standards and it will be compatible at pretty much any company large enough to use something to manage user accounts in a centralized system. Edit: Thanks for the silver!"
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n4vr03 | How exactly our charging habit affect the lifespan/capacity of smartphone battery? | we all have heard warnings like don't play games when charging, don't leave the charger on for more than 6 hours, etc It is said that it drains the life cycle, but how exactly those things affect the battery (as in, microscopic level) ? some would even bloat the battery which requires immediate battery change. | Technology | explainlikeimfive | {
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"With modern batteries, it doesn’t really make that much of a difference. Especially on phones that do any kind of smart charging, ie learning that when you charge it at night it’s on the charger for several hours so it can charge slowly over that time instead of as quickly as possible, or stop actively charging when the battery is full.",
"Li-ion batteries age in a number of ways due to changes inside the battery, for example electrolyte oxidation. How fast they age depends on how you use them. Basically, li-ion don't like fast charging, they don't like heat and they don't like being at the extreme ends of their voltage range. If you want to keep it working for as long as possible, avoid anything that heats them up (gaming while charging), avoid keeping them at under 20% or above 80% for a long time and avoid fast-charging. Keeping them on the charger for a long time isn't a good idea because unless the phone uses a smart charging strategy, it'll be sitting near 100% for most of the night, so about 3 months per year."
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n51ngh | How are mirror scenes in movies and TV shows filmed | Technology | explainlikeimfive | {
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"Hi :-) Many methods. Other than more recent special effects, there is a lot of trickery with lenses. Tilt-shift lenses: Basically a camera lens that you can tilt and move around. In this case aligning it in a way the camera won't show, even though you'd expect it to be in the reflection with a regular lens. Imagine you put the camera just so it would be at the edge of the mirror, and then move the lens a little so it moves out of the view. URL_2 URL_0 Other methods, such as using a double or twin (Terminator), CGI or compositing... So many possibilities :-) Terminator URL_1 Other methods URL_3 In more recent movies like matrix, it's CGI or compositing. Morpheus' sunglasses, one side showing the red pill, one the blue pill. Some stuff is just effect trickery :-)"
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n589p4 | Why does water ruin electronics? | Technology | explainlikeimfive | {
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"It's conductive, and unlike alcohol it doesn't dry quickly so it can seep into all the cracks and make short-circuits",
"Electronics is small amounts of voltage that travel along a path between two points. There can be many different voltages some high, some low, all in the same area in a device. Water you find in the world is full of minerals, which makes the water conduct electricity. This allows the different voltages to mix, which can overload parts of the device which are not able to handle higher voltages.",
"pure water is non-conductive, but once it comes into contact with almost anything, it picks up a bit of that something and becomes conductive, especially salts and metals. This allows electricity to flow to places where it's not meant to flow and completely bypass the places where it's meant to go. At best, you can rinse off the water with alcohol and let it dry out completely and hope it didn't damage anything, at worst it destroys a battery and catches fire."
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n58mq5 | How do calculators work? | Technology | explainlikeimfive | {
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"What do you mean by that? Mechanical calculator, electric calculators, those on your computer? Have you tried: [ URL_10 ]( URL_10 ) I mean depending on the level you're interested in that can be arbitrarily complex. In a **high level (programming) language** (low level = computer readable and fast, high level \"more\" human readable and thus potentially more convoluted and slower) your **mathematical symbols** (+,-,\\*,/) are basically basically **functions** (black boxes that take input and produce output) that take the numbers next to it as input and then replace the whole **statement** (idk 1+2) with it's output (in that case 3). So your input statement of 1+2 is given to a function like add(1,2) which idk looks like this: def add(x,y): return x+y so in that case x is given the value 1 and y the value 2 and so the returned value is 3. However that's sort of a cop-out because all it does is calling more low level functions on your computer that have implemented how addition works. If you're interested in those you might check out: [ URL_8 ]( URL_13 ) Which is a way how to organize your inputs without [PEMDAS]( URL_12 ) [ URL_5 ]( URL_6 ) How you can make those operations with [binary numbers]( URL_11 ), because if you can do that, you can basically hard wire how those calculators work. Here is an example of how it's used for an adder: [ URL_3 ]( URL_9 ) where you basically try to add 2 binary number. Which is actually pretty straight forward. You compare them with an [XOR]( URL_0 ) (exclusive or) operation, which receives two inputs and returns true \"if **exclusively** one **or** the other is true\", so if one wire is running charge (\"true\", \"on\", 1) and the other isn't (\"false\", \"off\", 0) then the result would be that the wire after the XOR device is \"on\" whereas if both wires are off or on, the wire after the XOR device/gate will be off. So it's a pretty nifty way to add the two: 0 XOR O = 0 = 0+0 = 0 0 XOR 1 = 1 = 0+1 = 1 1 XOR 0 = 1 = 1+0 = 1 1 XOR 1 = 0 =/= 1+1 = 2 or in binary 10 or rather 1|0 just like if you'd add 5+5 you go from 1 digit numbers to the two digit number of 10. But as you only have 1 digit of information (1 wire) you only get the 0 not the 1 from your \"10\". So as you can see it already does 3 cases pretty well and the last one also fits on the 0, ... but we still need that carry over digit (the 1) as well, in order to make it 10 or 2 instead of just 0. So what we do is we fork the input cables and redirect them to another **logic gate** (like the XOR) but this time it's an [AND]( URL_7 ) which essentially just checks if the inputs are identical AND true, that is the only case where it's true in any other case it's false. Which as you can see is perfect because it deals with the missing last case without messing up the rest. So: 0 AND 0 = 0 0 AND 1 = 0 1 AND 0 = 0 1 AND 1 = 1 And then we basically take that as our first digit and the XOR as the second one: 0 AND 0 | 0 XOR 0 = 0|0 = 0 0 AND 1 | 0 XOR 1 = 0|1 = 1 1 AND 0 | 1 XOR 0 = 0|1 = 1 1 AND 1 | 1 XOR 1 = 1|0 = 2 Perfect so with this simple logic operations we build a so-called [half adder]( URL_4 ). Now there's one additional problem: What if one of the two inputs already had a carry over digit then the result would be 3 not 2. So as you might have guess by the name the [full adder]( URL_1 ) is essentially just two half adders. In the first step you compute the XOR of the two inputs as well as the AND of the 2 inputs (aka your standard half adder). And then you basically add the carry over bit to that with another half adder. So you compute the XOR of the previous XOR with the carry over bit. And the same for the other path where you take the AND from the previous AND and with the carry over. And in a last step you compare the results of the two AND operations and return true if one OR both have been true (that's why the other is called XOR because the regular OR means \"one or both\". Et voila you got all the addition that you need. Because in order to compute the result of larger numbers all you need to do is add more full adders and do the calculation one digit at a time: 1011 = 11 + 1110 = 14 ------ 11001 = 25 So the first full adder would get FA(1,0,0), so 1 from the first number 0 from the second and 0 from carry over (where looking at the last bit of both numbers) and would produce 0|0 as output. The second would be FA(1,1,0), so 1 from the first number, 1 from the second number and no carry over from the last. And the result would be 0 for the direct XOR sum and 1 for the carry. Now the 3rd is a little more interesting because now we got a carry over bit, so it's FA(0,1,1). Which yields 0 for the sum (would be 1 but with the carry it's 0) and again 1 for the carry over. So for the 4th and final full adder we get FA(1,1,1) which yields a 1 for the sum (would be 0 but with the carry it's 1) and another one for the carry. Which as there is no full adder to feed that into, becomes the final result. So as you can see with some pretty simple wiring ideas and nesting concepts like using the output of 1 half adder as the input of another, to build a full adder or by feeding full adders into each other you can build a calculator that can add numbers as large as you want (given you have enough full adders. And there are similar ideas how to do that for subtraction, multiplication and division. Now you just need to think of a way how to use your binary number to light up those 7 segments on your screen: __ pretend the vertical lines are also just 1 line then it's 7 | | | | __ | | | | __ and vice versa and you got yourself a way how to do basic calculation just by running current through some wiring. The user then basically modifies the path by tapping a switch (number pad). Also if you're really fancy you can use the [IEEE 754]( URL_2 ) standard to use binary numbers to also deal with floating point numbers. Where you essentially do scientific notation so instead of 1 number consisting of 32 places you take the first place to indicate a sign (1/0 = +/-) the next 8 places become and exponent and the remainder is the number. Where the exponent basically is your \"decimal\" point (here it's a binary floating point). The idea is that moving to the left in a binary number means \\*2 and moving to the right means /2 so: 8 4 2 1 1/2 1/4 1/8 1 0 0 1 1 0 1 So the exponent lets you shift your number to the left or right making it bigger or smaller. That way you can reach numbers that are far outside of the 32 places that you've got, BUT you'd lose precision. So you're essentially just giving the order of magnitude and the first digits of that number. So idk 12,345,894 becomes = 12.3 million for example. So now you could have an idea why calculators are both limited in how many digits they can handle and why they might screw up if you go to arbitrary accurate numbers behind the decimal point.",
"Every calculator has these microprocessors embedded in it. Microprocessors are a collection of logic gates, with a lot of if and then's. Like, if this number is pressed, display this. These gates can be programmed in a specific way with the help of codes. My first explanation in ELI5."
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n5brv0 | Those YouTube people who manage to form a reverse connection with scammers and hack their cams and PCs, how do they do it? | Technology | explainlikeimfive | {
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"In quite a few cases, the scammers basically give them said 'reverse connection'. Essentially, a lot of remote desktop software like Teamviewer will have a scam warning built in when accepting the connection - so in order to get around this and not tip off the victim, the scammer has the victim connect to the scammer's computer first, and then press a button to reverse the connection. By pretending to be clueless and clicking randomly the scambaiter can use this window to download files, place viruses that give them remote access later and all kinds of stuff.",
"Create a backdoor connection using a custom remote access tool (RAT) like nanocore. You could also create a file like bankinfo.xml on the desktop that the scammer will open when they access your computer and use that to reverse the connection.",
"A very common method is to allow the scammer onto the home system. Once the door is open, it swings both ways. The White hat hacker can pull up a virtual machine window, downloading whatever \"team\" software the scammer will use to access your PC remotely. While the scammer is on the home PC, the white hat hacker is also in the scammer's PC and can collect and/or delete data, download malware, or even just wipe the system files and crash the scammer's computer."
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n5j5qe | What stops game developers from making a game completely shitty looking on the lowest and gorgeous on the highest settings? | Technology | explainlikeimfive | {
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"There's just a limit to how much you can have different visual settings and run the same game. Some things just can't be changed, such as the underlying physics of the game, the objects, the computations needed to calculate all the interactions, etc. What we can change are things like textures, monitor resolution, light effects, etc. But even on the lowest settings it's still the same game underneath, and thats always going to have a minimum requirement to run. That's the limiting factor in the end"
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n5k3th | Why 480p now seems me unwatchable, but 10 years ago it was like super good ? | Technology | explainlikeimfive | {
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"About 20 years ago, you watched everything on a CRT TV, which is main factor for why 480p seemed okay back then. Those displays were very tolerant of actual resolution of source, meaning that both details and imperfections were often blurred out and you got a nice and smooth TV signal with good following pictures and it was actually sharp because CRT didn't pixelate the analog signal. Nowadays, modern TV use pixel grid, where 480p video has to be stretched to cover whole screen, and this scaling isn't exact number. Meaning some pixels are twice as big while some are there time as big. This leads to major loss of quality. It doesn't help that we have 4k video sources available that makes the loss of quality on a 480p that much more significant.",
"They weren’t 480p, they were 480i the i stands for interlaced. Images back then scanned 480 *interlaced* lines of resolution onto the screen, which meant you were seeing the odd lines scanned then the even lines right after. It happened so fast that you didnt notice. This was because of how televisions worked. When we changed over to computers, they didn’t need the interlaced scanning so people started producing tv in a “progressive” format which is what the “p” means.",
"Because screens used to be worse and 480p was all we knew, its now bad because the screens we watch them on are better and we now know a lot better quality than that",
"Screens are bigger nowadays so you'll notice imperfections more easily than on a smaller screen. 480p doesn't fit evenly into our standard screen resolutions. 480p means 480 vertical pixels. Nowadays, Full HD is 1080p and 4k is 2160p. You can see 4k is double the vertical pixels of Full HD but you can't divide 480p evenly between them. There has to be some fitting that causes loss of quality. Lastly, 480p was usually recorded on VHS tapes. Digitizing them to play on current TVs may generate some differences than if you played the VHS directly in a VCR.",
"If you're referring to YouTube and many other streaming services, I can tell you straight up its because of their compression format and settings. Sometimes when I'm watching a video on YT that has clearly been filmed with a high resolution camera (2k+) I will set my video to the native format because my 1080p monitor will actually SHOW that crisp detail in most of its glory. Granted not all pixels will resolve, but the image is way better. 480p at its best looks good still, and 1080p great, but the name of the game is efficiency, and the lowest bandwidth cost that gets the job done.",
"480p being unwatchable may be a result of not associating any emotions to that format. For me, 480p was an era of a \"super\" 480i: I recorded lots of DV video of family, trips, and such. I even desire powering up old 8bit computers on original 480i CRTs. Viewing older formats bring back a sense of nostalgia. Maybe another example are black and white photographs. Unless you have some emotional connection, such as B & W pictures of family, relatives, etc. you would view B & W photos in general as unviewable. However, still respect them as they were the \"Super good\" at that time period.",
"You're used to higher quality. Way back then, when 480p was the standard you could more easily fill in the blanks. Not to mention screen resolution was smaller, so there was less stretching, too."
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n5moi7 | Why video games developers leave lots of unused content in the final version of a game? Why they don't just delete it? | Technology | explainlikeimfive | {
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"Coding in general, and videogames specifically, is a situation where if it works you don't mess with it unless you have to. Changes that shouldn't affect anything else often do, in logic-defying ways.",
"While it is rarely necessary to leave this content in, removing it is a lot of work and introduce a risk of breaking something. Stuff that is easy and safe to remove gets removed, but for everything else it's a trade off that is rarely taken.",
"It's not necessary. Much of that stuff could be removed. But that by itself is a potentially dangerous process. What do you delete? Do you have definitive proof that it's safe to delete? Does the game have some step where every item that might ever be needed gets loaded just once to confirm it's working? Let's say you have some cars in your game and you decide to drop one of them from the random selection of cars driving around the city. Are you sure there isn't a storyline character who drives that car? You took the car out of the random rotation, but are you sure it's safe to delete the whole car's information from the game? A few such things slip through the cracks. In a huge project there could be a lot of such things that happen. It's safer to just leave it in the game than to try to surgically remove it and risk unknown collateral damage."
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n5rkm9 | What causes things to be water proof? | Technology | explainlikeimfive | {
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"The openings/gaps in the surfaces or bordering edges are too small for water to fit (\"want\") through. Water likes to stick to itself, a property that can be used in building waterproof or water hardy stuff. For example in phones, gaps are so small that the surface tension of water forbids it to get in. Once it is in you have a problem (due to capillary action) but raindrops don't have much chance when waterproofing is done right."
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n5uj6c | What does the binary of a computer actually look like, and how does it understand those instructions? | Technology | explainlikeimfive | {
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"Typically, each component that's using some sort of binary code has multiple wires, and each wire carries one digit. So if there's 8 wires (8-bit) and the first 4 have voltage on them and the second 4 have no voltage, then that could represent 11110000. (Yes pedants, I know there's exceptions). Now there's two main things that 11110000 could represent. It could be a number, in this case 240. It could also be an instruction. Typically, we design processors in a way that they will often take an instruction together with a number. This makes sense, if you want to do \"add 10\" or \"access memory address 42\" then having the instruction and the number together makes things simple. So let's think of a hypothetical processor that has 8 total wires for input and output. We could say that the first 4 wires are for the instruction, and the last 4 are for the number. Let's say we want the chip to take whatever is in memory address 2 and put it into the processor's register (the register is a place the processor holds numbers it's currently working with). We could build the chip so that the command to do that load operation is 0100. So the full command 0100 0010 tells our processor to load from address 2. We could then make an add command and assign it to 0010. So if we want to add 1 to whatever's in the current register, we would send 0010 0001 to the processor. So why is 0010 add? It's because whoever builds the processor gets to build into it the operations the processor does. It's built specifically so that when it sees that code, the wiring does the stuff that is required to add numbers together. Fun fact, those numbers representing operations are called \"opcodes\". If you're curious you can look up opcode references for most popular processors and see what they are, though they are often written in hexadecimal. For example the \"jump\" command for the 6502 processor is 4C, which is 76 in decimal or 01001100 in binary. EDIT: Let me add that there are sometimes special commands on a chip that are controlled by a single wire. There might be, for instance, a \"halt\" wire that controls whether the processor is allowed to run or not, so changing the voltage on that wire will enable or disable the processor. This varies based on what the manufacturer wants to have as a feature on the chip."
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n5yfmm | How does air conditioning work? | Both in cars and in houses. I know car heaters work by pulling heat from the engine chamber (idk if that’s the right word, I know jack shit about cars) and I think a lot of houses either use electric coils or gas flames (this may all be wrong, please correct me if so). But I have no idea how air conditioning works. | Technology | explainlikeimfive | {
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"Air conditioners work by essentially moving heat from one side to the other. The way this works is by exploiting a property of gasses: when you compress them they heat up, and when you let them expand they cool down. In an air conditioner there's a sort of loop containing a gas (we call it a refrigerant). On \"outside\" side of the air conditioner the gas is compressed, so it heats up. That heat leaks out from the tubing into the outside air. Then the gas moves to the \"inside\" side. Once there it's allow to decompress, which causes it to cool. So now the tubing is sucking up heat from the air from the inside side of the AC. The gas then goes back outside where the cycle repeats. So essentially the heat from inside of your house is getting sucked up by the tubing containing the refrigerant gas and getting dumped outside of your house. There's a neat video that indirectly shows how this works. They build a refrigerator that works by stretching and un-stretching rubber bands, which heat up and cool down the same way that compressing gas does. It sucks as a refrigerator because rubber bands are super inefficient for this, but it makes for a neat demonstration of the basic principle of how refrigeration works. [Here's the link]( URL_0 )",
"You know how you can move water from one place to another with a sponge? Wring out the sponge and go back for more water? There are special fluids called refrigerants that can do that with heat. They collect heat inside the house. Pump them outside, squeeze them, and the heat comes out into the environment. Then you pump the fluid back inside the house to collect more heat. Source: am mechanical engineer. Was refrigeration tech."
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n5z33d | How does in-built "unsubscribe" functionality in Gmail work? | When you receive bunch of promotional emails from a website, sometimes there is a link at the bottom of the email to unsubscribe from similar future emails but sometimes there is no such link. However, Gmail provides with a button to unsubscribe from these emails regardless without visiting any other website. How does it work? | Technology | explainlikeimfive | {
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"The email headers (which aren't normally visible to the user) will normally contain unsubscribe links if the email is from a reputable sender. When gmail identifies that an unsubscribe link is there it will give you the option of unsubscribing in addition to reporting the spam. You can view these headers by selecting a message and then selecting \"show original\"."
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n63b1a | why does Starship make the horizontal flip instead of landing lime their other rocket? | Technology | explainlikeimfive | {
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"Because falling horizontally allows you to slow down using air resistance, which is increased when surface area is increased. This saves for the very last moment, where the rocket flips and then scrubs the remaining velocity with engine power. Braking with the engines exclusively would cost more fuel and thus more mass you'd have to slow down. This multiplies, the larger your rocket is, which is why the heavier Starship tries to manage with as little fuel as possible.",
"It needs to shed velocity through attrition, otherwise you would have to load a lot more fuel for the final landing burn, making it more expensive to launch, more difficult and risky to land."
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n63c44 | What ensures that no one is generating the exact same keypair by pure chance | I am aware that I am probably mixing up some topics in this question but lets do this: While the chances of this happening are probably unbelivably small, humanity is generating a lot of (RSA) keypairs on a daily basis. If my understanding is correct, websites use asymetrical keypairs to provide SSL certificates. How is it, that we never had two websites that are using the exact same keypair by pure chance? I vaguely remember a demo site by google showing that this is possible (using an outdated algorithm if my memory servs). Once again, I'm really sorry for my lack of knowledge and my failure in articulating this question properly but I really want to know. \^\^ | Technology | explainlikeimfive | {
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"Nothing really, other than the chance of such a thing being lower than winning the lottery several times in a row.",
"> While the chances of this happening are probably unbelivably small, humanity is generating a lot of (RSA) keypairs on a daily basis Not enough to defeats the probabilities. The probably that two random 100 digit numbers are the same is 1/10^(100). Using the [birthday problem]( URL_0 ), you need about 10^50 different numbers for it to be statistically probable for a single collision. If each person on earth (less than 10^10 people) generated a random 100 digit number every second of every day (less than 10^6 numbers per day) of every year (less than 10^4 days per year) it would take over 10^30 years to make 10^50 different numbers.",
"Modern crypto algorithms have possible combinations in the \"more than the atoms in the solar system\" territory. Beyond which, if two people did generate the same keypair by chance, it would likely not be discovered anyone unless one happened to try and decrypt something intended for the other.",
"Collisions are not really a problem, because for any public key infrastructure system (SSL or otherwise) you must have a certificate authority (CA). The CA is a trusted entity that generates issues the certificate and verifies its authenticity. Websites for not generate their own SSL certs, but purchase them from trusted CAs. A CA will not generate duplicate certificates, so if 2 parties do have duplicate certs, they will come from different CAs. It may also help to understand how SSL works. When you visit a https website it sends your computer it's public key which your computer uses to verify the identity of the website. Your computer then generates it own symmetric (shared) encryption key and then encrypts it using the public of the website. When you encrypt using the public key only someone with the private key can decrypt it. For this reason private keys are never shared. Your computer then sends the encryption key to the website and says I would like to use this encryption key for the rest of our communications. The website then decrypts the new encryption key and uses it for all future encryption with your computer."
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n65nsb | How is it that some video games have a huge Gb size than others? (more details under) | My two examples are as follow: Call of Duty: Black Ops III - 100Gb (160Gb with DLCs) Monster Hunter: World - 48Gb (96Gb with DLCs) How is it that Black Ops III is way heavier than Monster Hunter: World, even though World requires more power from my PC for the minimal settings needed (graphic card, processor...) than Black Ops III? | Technology | explainlikeimfive | {
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"Video games are made up mostly of just two things: code (what tells the machine how to run the game) and assets (all of the art that appears in the game). Code is actually pretty small, so it doesn't take up too much space. Assets, on the other hand, can be massive, and they usually represent the majority of the size of the game, especially these days as graphics tend to be very high-resolution. I would guess that BlOps3 is bigger because its art direction is aimed at realism, whereas MonHun leans more towards stylized art that doesn't require quite so much space on the disc."
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n672wl | Doge coin, how its made, how its used and why its worth what it's worth. | Technology | explainlikeimfive | {
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"Dogecoin is made by using a computer to complete math equations. It is used for meme value and speculation. It is worth what it's worth because of wild speculation. Basically it's a meme you can buy, and the more popular it gets the more people want to either buy in on the meme, or just buy some in the hope they can sell later at a profit.",
"It's not used for anything and it's only worth anything because people put money into it, when it comes to block chain technology it is literally built to shit in the face of many principals of good design. That being said value is found by what someone is willing to pay for something in an economy, not what it's actually \"worth\" so ppl tweet about it, meme about it, fomo it, and the price goes up. It will probably crash and turn alot of ppl off of good crypto when it does, or it will stay a meme coin and become a light store of value like btc(but not at such a high price.) (it'll never really be like btc because it generates so many new coins when mined, inflation is ridiculous) Edit for those older than 5: to clarify based on the below reply \"never be like btc\" means that it will not hold the same value per coin at such high lvls due to the inflation rate competing against the fiat market cap, it can go to 1 or even 100 dollars, but if doge was worth the price of btc today it would have a market cap over the total narrow money supply of the world and it adds over 5 BILLION coins to its supply each year for many many years to come(not all value of the world, just all fiat, to be clear)",
"Doge is mooning because it's mildly humorous and, in my opinion more importantly, it's the cheapest alt coin on Robinhood. Simply put, it has greater market access and the platform providing access to it is more simple to set up. The people who were FOMOing on GME, BB, NOK, AMC were able to pivot right into Doge, and whales like Musk who pumped GME pivoted just prior, and with significantly less risk. Ultimately, Doge cannot sustain its value. It has no coin cap, and it will inflate indefinitely."
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n68j75 | what is the x in the .docx file | Always wondered why document files save as .docx and not .docs what does the x mean here? And why are pdf files not .pdfx then? | Technology | explainlikeimfive | {
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"The X version is much more heavily based on XML - it’s much more readable as a standard and there is more information that can be accurately saved. It also much smaller than traditional DOC files. The DOC/DOCX was created so word and newer office versions could distinguish between the old and new formats. PDFs etc don’t need to do this as their standard just changes but the format hasn’t.",
"The X stands for XML. Originally all the Microsoft Office file formats like .doc were propriatary. This meant that you needed Microsoft Word to open and edit .doc files. There were some attempts to make third party tools to open and edit these formats but without the documentation describing what everything does and what it is for this is very hard. Microsoft would also come with updates that would break the third party tools and refuse to open files that were created with these third party tools. However this was a problem for organizations like schools and governments as they would then require that everyone they sent documents bought the official Microsoft Office package. This was of course what Microsoft intended. However this strategy almost backfired as politicians demanded that the documents published had to be in an open format that could be opened and edited with free and open source software. Some government organizations started to switch from Microsoft Office to Open Office. Microsoft did try several things to please the authorities while still making sure people still had to buy Microsoft Office. They released some documentation on the file format and even some limited software that could read these files and edit them somewhat. This meant that while it was technically following government specifications of being open source this was limited in practice. Part of this was that they changed how the documents were stored from the propriatary binary format to a variant which looked confusingly like the competing Open Document Format with XML files packaged inside a ZIP file. This new format was named Office Open XML and got the x in the filename extension. And with this most authorities were willing to accept it. It can be debated if Microsoft is actually complying with the laws as there is still no open source tools which is fully compatible with Microsoft Office. If you save a document as .docx in Word and then open it in LibreOffice Writer it may not look the same. Similarly if you go the other way."
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n6i82h | How can MRI machines change how a new tattoo looks? | I was scheduling and MRI and they asked if I had any tattoos or piercings that were new. I do in fact have a roughly 2 month old tattoo. The person scheduling me talked to one of the radiologists and said that MRIs can change the way new (up to 3-4 month old) tattoos look. How is that possible / how does that even work? | Technology | explainlikeimfive | {
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"The ink can sometimes contain trace amounts of iron that will be greatly affected by the magnetic field generated by an mri",
"I've never quite heard that before. But live with an MRI researcher and why they typically ask is: Older tattoos in particular use inks that contain metals that are magnetic. If you have one of those tattoos they can heat up the pigment in the tattoo and give you severe burns. It also ruins the image of the scan too. It heats up the pigment by basically exciting, what I think in many cases is ironoxide, the molecules as it creates the magnetic field which allows for the scan. I'm not saying that I know better about new tattoos, technology and changes--but this is traditionally why its asked about. Edit: Here is a case study example which talks about it URL_0",
"As others said, if the tattoo ink has any trace amounts of iron, the extremely strong magnetic field could affect it. It is hard to express how strong the magnetic fields are around an MRI, so here is [an example of a floor buffer that was pulled into an MRI machine]( URL_0 ).",
"The ink in the tatoo contains iron, as other people mentioned. I will add it's not just the magnetic field, but the rapidly changing field, and the flow of current elicited by these fields can heat up the tattoo, and move around the particles within the ink. In rare cases it can also heat up and cause some inflammation. Your MRI tech and radiologist will know what to do, so don't let that prevent you from getting a scan. If your Dr. tells you that you need an MRI and it's safe, then just do an MRI. They probably have a good reason to request that since it's an expensive scan."
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n6p28k | What does the ‘abort’ handle in spacecraft cockpits actually do? | In many movies and media that depict real-life spacecraft, or near-future spacecraft that are logical progressions of real-life spacecraft, they show the abort handle or button or switch. What would happen in real-life if this handle was pulled during any given moment during space flight; takeoff, orbit, halfway to the moon, etc.? | Technology | explainlikeimfive | {
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"The classic \"abort handle\" is for the launch abort, which obviously only works while you're still connected to your carrier rocket. In that case, it activates a dedicated launch abort rocket and separates the spacecraft from the rocket. The small, but powerful abort rocket then pulls away the spacecraft from the rocket (and the imminent explosion which is usually the cause to use it). Then it usually activates the descent systems (e.g. attitude control so you're right side up, and parachutes once you reach the correct altitude for them. Couple videos from those systems in use: [Soyuz pad abort]( URL_0 ) [Soyuz in-flight abort]( URL_4 ) (these 2 were real accidents with people on board!) [Crew Dragon pad abort test]( URL_2 ) [Crew Dragon in-flight abort test]( URL_3 ) [Apollo abort test]( URL_1 ) However, the handle isn't the only way the abort can be activated, and it's more likely that it's activated by the flight computer sensing a failure.",
"It usually activates the escape rocket, which blasts the crew capsule away from the rocket. It is only usable for a certain window of the launch and then the escape rocket is jettisoned. It's not available after that. There's a different mechanism to blow exploding bolts on the hatch so the crew can get out quickly if the vehicle is still on the pad, then they get into a little cable cart that whips them away from the rocket. These are two completely separate systems with different specific windows of use. It's not like the ejector seat in a fighter plane that can be activated at any time. Once you're in space, just hope for the best. If still in orbit, an emergency re-entry may be possible, but there's a whole process for that and it takes a while. You can't just skedaddle back home all of a sudden.",
"It really depends on the space craft. In the case of Apollo and the Falcon 9 hitting the abort during launch fires explosive bolts and emergency thrusters that will kick the spacecraft away from the rocket. Which allows it to land safely. Now the abort button on say the lunar module if pressed would fire the accent stage thruster forcing the decent stage away from the accent stage allowing the lunar module to reach lunar orbit. There is really no abort during the trip to the moon. If a spacecraft has to return like Apollo 13 did you have to change the craft delta v to basically slingshot around the moon.",
"The abort modes are only used during launch. If there's an emergency with the spacecraft on the launch pad or in flight that requires the capsule to come back to Earth immediately or if there's something wrong with the booster, the abort handle or button will fire emergency rockets on the capsule that will pull it safely away from the booster. [You can see in this animation how that works]( URL_0 ). Because the spacecraft is not yet in orbit, the capsule will then coast for a bit and then deploy its parachutes for a safe landing. In some rockets, like the Russian Soyuz, the abort rockets can be jettisoned after launch. In others, like the SpaceX Dragon, the emergency escape rockets are built into the capsule. Typically though, the onboard computer will detect an emergency and activate the abort rockets automatically. The button or handle is more of a backup in case something happens that the computer doesn't detect or if the computer doesn't react fast enough."
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n6rzus | can internet providers listin in to the decryption key | So for explain if I send out a message on the app let’s say discord, I encrypt it locally, then send it out, but when starting a conversation both party’s of the conversation gets a decryption key, to decrypt the encrypted message is it possibly for internet provider to see the decryption key and thus decrypting my encrypted code I could be wrong so I apologize in advance Edit: thanks for explaining the use of public keys and private keys, I understand the concept now | Technology | explainlikeimfive | {
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"That is not how encryption works. Modern encryption works over a private and public key. The public one you share and with that people can encrypt messages to send to you. These encrypted messages can only be decrypted with the private key and only you have that one. So for a conversation you only send out both your public keys, while you both keep your private keys for yourself and just decrypt your incoming messages, without anyone else being able to do so.",
"It's depending on the encryption method, like pgp u got an private and public key, so everyone having your public key can send u an encrypted message but only u are able to decrypt it Widely used is tls/ssl it's working with handshakes, but yeah pgp was the easier to explain imo."
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n6spbj | Crypto is software, code. Isn't it hosted on a server somewhere on the world? Break the computer, break the crypto? | I don't understand how cyptocurrency can be forever. It's just code at the end of the day. That code must be run on a server somewhere right? Like all online games and data servers keep all digital data. Isn't cyptocurrency the same? If the server or computer dies, won't all the money just poof? | Technology | explainlikeimfive | {
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"Crypto currency is a decentralized system. There is no \"central server\" that is running the whole scheme. If you're familiar with Peer-to-Peer games where you don't connect to a server but instead directly to the players you want to play with crypto functions in similar terms. Crypto is \"run\" by everyone who wants to run the code. If you imagine a network where your computer is connected to a few other computers, and those computers are connected to a few more, and those to a few more, that's kind of how crypto operates. Everyone who wants can store the blockchain. Your computer is constantly chatting to its neighbors to share information and try to keep up to date with what chain is the right one and who is doing what. Unless a significant portion of the computers who are running crypto go poof you can fairly consider the system functionally immortal. You only need a single computer online to run the entire blockchain, and there are a lot of computers currently online.",
"Breaking crypto would be like killing Voldemort. Except instead of 8 pieces to kill, there’s millions, and that number is increasing. Is it possible? Look, probably? Is it in any way feasible? I’d say not.",
"Here's my shot at explaining how Bitcoin works. A word of caution- this is a bit of a long read. Albert Einstein said, \"Make everything as simple as possible, but not simpler\". I've tried my best to do just that. Imagine that someone wants to give you some tokens in exchange for something of value that you provide them. How do you protect yourself from being cheated, how do you guarantee that those tokens will remain yours? With physical tokens like cash, metal, or gems, it's easy: it can only exist in one place at a time, so as long as you're holding onto it, it can't be anywhere else. But electronically? Things which exist only electronically can be trivially duplicated. So if someone is sending you a digital token online, how can you trust that you are now the only unique holder of it, and it isn't simultaneously being copied and sent to other places online? The traditional solution is to defer verification to a central authority, usually a bank. The bank keeps a ledger, a master database of who owns what. That person would notify their bank that they'd like to transfer some tokens to you, the bank would check their ledger, verify that they have it, then create a new entry into the ledger recording the transfer. If that person were to try and send the same tokens to someone else later, the bank would say no, you can't do that. This works well in protecting you from needing to trust the other person, but it introduces a third party into the transaction, the bank. A bank which needs to monitor and track what you have, always stands between you and the person you're sending tokens to, and who has the power to deny or even reverse transactions, freeze or seize tokens, and edit the ledger as it chooses. How can you create a ledger for a digital token which cannot be duplicated or counterfeited, which can only exist in one digital pocket at a time, which can be transferred from user to user freely but cannot be double-spent, where no single entity needs to be trusted with unilateral power over the books? What Nakamoto proposed is something called a Proof-Of-Work Blockchain. A blockchain is a special type of ledger maintained by a decentralized, trustless swarm of competing agents, which will nevertheless converge upon one single un-alterable consensus ledger of transactions because of the rules about how new entries to the ledger must be written. In 2008, Nakamoto published their paper, and in early 2009 they released the first public blockchain onto the internet, and the tokens of this blockchain are called Bitcoins. There are two key concepts you need to understand: 1. Hashing algorithms, and 2. Public-Private Keypairs. Let's go over them now. A hashing algorithm is a bundle of math which functions like a precise woodchipper. If you feed something in, it takes your input and shreds it into a string of digital static called a hash. If you feed the same thing in, you'll always get the same string out. If you change the input even a tiny bit, the hash that comes out will be completely different. And it's impossible to take a hash and use it to reconstruct the original input. A Public-Private keypair is a secure way to digitally prove your identity and ownership. The Public key can be disseminated widely, and the Private key is kept secret by the owner. The Private key can be used to prove that you're the owner of the Public key. Like any bank's ledger, the Blockchain is a database, a huge list of public wallet addresses (corresponding to public keys) along with data on how much bitcoin each one contains. It also contains the complete transaction history of every single transfer of bitcoin from one address to another since the blockchain was first created in 2009. This file is massive- over 300 gigabytes as of Jan 2021. Each new batch of transactions added to this database is called a block, and each block is built off the previous one like links in a chain. However, unlike the ledger of a bank, adding a new batch of transactions to the Blockchain ledger is an intentionally hard process, and the deliberately wasteful difficulty of doing so is the key to its security. Suppose you wanted to receive bitcoins from someone. You'd randomly generate a public-private keypair, and you'd give them the public key you just generated. They would have the private key for their wallet, which exists on the blockchain and is registered as having some amount of bitcoin, and they would use their private key to transmit a message, \"hey, wallet XYZ transfers 0.22524511 bitcoin to wallet ABC, here's proof that I'm the owner of XYZ. By the way, I'm including a tip of 0.00005000 bitcoin to the Miner who processes this\". This message goes to what is essentially a public noticeboard (called the mempool). Then, the Bitcoin Miners come in. Bitcoin Miners are the people (technically, the computer systems they set up) who monitor the mempool and are in constant competition to luck out and become the author of the next block. The reward for doing so is that, in addition to the tips collected from all transactions, each block written allows the author to declare the creation of a new public wallet address which has coins from nowhere, to which the miner holds the private key. A block might look like, The previous block was block #149 This is block #150 XYZ transfers 0.22524511 coins to ABC and 0.00005000 coins to MYN SRM transfers 15.4250000 coins to KJQ and 0.00004500 coins to MYN JOE transfers 0.00752000 coins to LEA and 0.00002200 coins to MYN The new address for this block is MY2, which now contains 50.00000000 coins End of Block #150 Zombie Pirate Party Monkey You might have 2 questions in mind right now: What's stopping a miner from just writing blocks as fast as they want and minting coins for themselves as fast as they'd like? What's the deal with the last part of that block? The answer to both questions are the same, and they're related to Hashing. If you take the entire block and shove it through a hashing algorithm, you'll discover that the hash which comes out looks extremely unusual. This is the hash for the real block #150 on the actual blockchain- 000000009ca75733b4cf527fe193b919201a2ed38c9e147a5665fdfade551f4d Notice something? The critical rule of Bitcoin mining, which stops miners from just writing as many blocks as they'd like as fast as they'd like, is this: the hash of each block must start with a certain amount of zeroes. In order to write this block, the miner first writes a draft: \"The previous block was #149, this is block #150, people sending coins to each other, tips go to my wallet which is here, and here's my new wallet with 50 coins I want to add to the blockchain\", and then they hash it. It probably won't start with the needed amount of zeroes. So they add a random bit to the end and hash it again. Still no. The miner will keep throwing different random bits into their draft block, billions of times per second until, by pure luck and brute force, they hit upon a random string which makes the block pass. \"Eureka! Here's Block #150!\" they announce, broadcasting the new block to other miners. The other miners, busy with their own billions of guesses per second, spare a single hash cycle checking out this #150, confirm that it checks out, drop their own personal drafts of #150, adds this #150 to their own personal copies of the blockchain and start working on block #151, hoping to write the next block themselves. As the miners spread word of the new block #150, you're satisfied to see that person's transaction now recorded onto this latest link of the blockchain. Think about what would need to happen if, thirty minutes later, the person who sent you those coins wanted to take it back, erase that record, and spend it elsewhere. They would have to write an alternate block #150, one that didn't include their transaction to you. In order to do that, they would have to make trillions of guesses themselves before they found a random string that would make it hash properly. Then, they'd have to write an alt-#151, alt-#152, and so on. Meanwhile, the majority of the miners have already published block #153 and are now working on block #154, and nobody would accept their alt-#150 because everyone is already racing to write #154. The only way for a bad actor to reverse and double-spend a transaction which has already been written would be to create an alternate chain longer than the dominant one, and doing that would require commanding more computer power than the rest of the network combined. Good luck. And that's how you create a digital token that can't be duplicated or counterfeited, can only exist in one place at a time, whose supply is finite, which can be sent freely from any address to any other, and is secured not by trusting a third-party authority, but by math. This is what Bitcoin is, and what it continues to be today. Built around this are the far more messy human questions of, what is it worth? How much are people willing to buy and sell it for today, and what price will they pay for it tomorrow? These questions and the rancid sewers of discussion around them are beyond the scope of this explanation. Bitcoin came into existence early in 2009, and at first it was largely just a curiosity and a plaything for cryptography nerds, computer scientists, and economic libertarians. It was a neat toy, but the question at the time was, \"Okay, it's cool, but does this stuff actually have any value at all?\" Eventually, on May 22, 2010, a Florida man paid another person 10,000 bitcoins for them to order him two Large pizzas from Dominos. With this, they became the first two people in history to believe that the answer to that question is: Yes, it does. So far, people have not stopped believing that yet.",
"Thank you for asking this. Reading all the replies really helped me understand a lot about Crypto.",
"Im no expert but im prettysure thats why u have a blockchain, like having 1000 bits of identical code all in different parts of the world and they would all have to break at the same time for it to make any changes in the actual code (research 51% attack)",
"Cryptocurrency isn't code. Bitcoin, to simplify, is a pair of numbers that can be found by guessing a random pair of numbers, then operating some lengthy mathematical operation on those numbers to detect a special property. When found, that number pair constitutes a unit of currency. One then reports that pair to the centralized servers which share that report. One number is kept private, the other shared. By virtue of the mathematical operation, strangers cannot guess your private number from the reported, public, number from the pair you've found. To exchange currency, you again perform some operation on your numbers that can only be done if somebody knows the secret portion of your number pair. The results of that operation are reported publicly which transfers the unit of currency to the other person. That exchange mechanism is called blockchain. Locating number pairs is called mining. Number pairs are bitcoins.",
"I have some pedantic complaining below. None of this is meant to take away from the other answers. Those answers are correct and should be read first. So thus far this thread has discussed how things work in theory, and I want to point out a few things that happen in practice that I feel people should know. So let's say Bob reads a news story about Bitcoin and wants to buy $100 of Bitcoin. Now while (as discussed in this thread) Bob could establish a crypto wallet on his physical machine, download some software, sync the blockchain, etc and buy the coin (or even mine the coin if it were computationally possible) - that's definitely not an easy thing to do for someone with a passing interest. Bob may have seen advertising from Paypal or Robinhood about being able to buy crypto on their platform. He buys $100 of Bitcoin on Robinhood. So, here's where the theory falls apart right now. Robinhood/PayPal don't actually give Bob access to his wallet or the ability to send the actual crypto to a different wallet. As far as we know, they could just be treating the crypto like an underlying security and never changing your money from USD. More importantly, I wanted to point out that there is more and more \"re-centralization\" happening in the sense that Bob is now trusting a giant entity like Robinhood/PayPal to maintain and verify transactions to the blockchain. There's nothing stopping them from faking transactions they never actually put on the blockchain. There's nothing stopping them from messing with price discovery. There is certainly nothing stopping them from tying your transaction to your personally identifying info. Starting to look no different then banking in USD.",
"The word here is decentralized, it is hosted on multiple servers and they agree on each other. The multiple hosters are miners here, inorder to mine the transaction they need to know the full history of the transactions (Sometimes minified versions using hash). It is estimated around 1,000,000 individual miners (servers as they have full knowledge about the transaction). So unless 51% doesnt join hands and take over the system, the crypto will be safe. iirc, there were concerns when pool of miners joined and they have to reduce the pool size.",
"You'd have to kill every computer that has ever run that code. The history and ledger are immutable.",
"Imagine it like piratebay. If piratebay goes down and you have a .torrent you can still download the torrent and also upload it simultaneously for others.",
"It’s old but I only saw this recently, high five to 3B1B, such a succinct explanation. URL_0",
"As echoed by most of the top comments, the inherent benefit to cryptocurrencies is that it is decentralized. You can't just \"hack\" one entity, since the data is split among multiple users (in most cases, amongst millions). The closest anyone can \"hack\" a crypto currency is by attacking an exchange that holds user coins. The Mt.Gox \"hack\" is probably the most notorious example of what the media covered as a hack, but in reality, it was an attack on an exchange that held people's crypto wallets. The underlying technologies(BTC/ETH/others...) were in NO WAY hacked, but the offending parties were able to compromise Mt. Gox in a way that allowed them to gain access to users wallets and transfer huge amounts of money to a shady crypto wallet. On the other hand, i think the closest a popular blockchain was \"hacked\" wasn't an actual hack, but the DAO Attack on Ethereum was an exploit that allowed a nefarious actor to gain a huge amount of ETH that eventually resulted in the creation of ETC. At the end of the day, I believe that as long as money is involved, scammers will find a way to separate a fool and his cash. By holding crypto, it provides extra hoops for criminals to jump through so I trust it more as a storage of wealth compared to storing in a bank account. If someone is able to break through my bank's security, they have access to all my funds since my username/password are likely saved in a central database. For someone to break into my crypto wallet, they have to know me personally, break into my house, find the spot I hide my 30 word recovery phrase, transfer my crypto to an exchange, yada yada yada. There is nothing a hacker can do to try and get my crypto if he isn't physically able to get to me. & #x200B; Side note: I don't like ETC. edit: clarification/grammar",
"Kind of, if you took over 51% of the network you could validate your own false transactions & basically print money.",
"I'm going to be a little pedantic and clarify that \"Crypto\" doesn't always imply \"Cryptocurrency\" - especially when preceding the term \"software\". \"Crypto\" is short for \"Cryptography\"/\"Cryptographic\". Meaning obfuscation of messages/data to keep it secure. Cryptocurrency uses hashing (irreversible, unique identification data) but most people know about encryption. Coming into this thread, I was confused by the title until I read the body of the post.",
"This thread has made it clear to me how many people have no idea what they're talking about",
"Obligatory: Crypto is short for cryptography, crypto currency is short for cryptographic currency. So shortening crypo currency to crypto is very confusing, and should be avoided.",
"It's like a spreadsheet that lots and lots of people have a copy of. Loads of spread sheets can go missing and the rest still add up. And some people changing their spreadsheet to cheat will be found out by the multitude of other spreadsheets that don't agree with them. There's a bunch of math behind it, but essentially that's the idea. And there's always a total that depends on every other transaction before it so that it's not possible to alter anything in the transaction history.",
"I'll try to give it a go in a coin-agnostic way Imagine you live in a little village where there is neither physical money nor computers. Instead, every time you want to send \"money\" to someone, you must go to the village center and yell to the accountants: \"I'm giving Joe 50 bucks!\" Each accountant quickly takes note of your transaction and places it in their own notebook. When this notebook is full, the accountant says \"I'm done!\" and gets a new one. The other accountants check his book to see if there is no shady business. If most of them agree, they throw their own books away (because this one already has the transactions and everyone agrees it is fine), make a copy of this one for their own tracking and start over. The details of how they check if the book is okay or how they decide when two guys yell at the same time is not really relevant and vary from coin to coin. What's important in this analogy is that you can't \"hack\" the system because there is no single accountant. Every one can start taking notes if they like. Even if you kidnap or kill a guy, there is a bunch of other guys that have copies of the transactions and know what's ok and what is not. Now, if you could convince **most** accountants to say you have a million bucks, you have a million bucks. But it's a little bit harder than hacking one guy and, at this point, the whole system is screwed."
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n6whcv | Why does restarting my router sometimes help with internet connectivity problems? | I mean, what changes with that reboot that helps? | Technology | explainlikeimfive | {
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"Imagine that you start solving an equation in your notebook. Halfway through you notice that the number don't add up anymore. You try to figure out what the problem is but you can't seem to find it. So you just tear that page from the notebook and start again from the beginning with a fresh perspective. This is similar to what happens with your computer. For some reason a mistake was made in its calculation that it's not programmed to recover from. So when you restart the computer it starts from scratch. Now, you can hope that whatever caused the problem doesn't occur again.",
"Depending on what the issue is, a restart of the router forces it to sync back up to the equipment at the exchange and then reauthenticate the connection. When it syncs back up, the equipment at the exchange will look at the properties of the line at that point and you will connect at the best speed for the conditions if the line at that time. So if something had been causing interference for a while, which has now stopped, what should happen is that the exchange drops the speed while the interference is there and raises it when the interference goes. However, this does not always happen. When you reauthenticate, most residential connections will be given a new external IP address. You may also find you will be using a different path through to the national backbone, so if some of the infrastructure that everybody uses, rather than just yourself, is having issues, a reboot may get you on a path that avoids that element. The other thing that may be happening is that the router itself may be having issues. If, for example, it has not been clearing its ram properly during use, a reboot may clear that in the same way that you would restart your computer if it was running slowly.",
"Its the general idea of \"turn it off and on again\". If something went wrong with the connection, some route or IP was messed up, then turn it off and then on again, which will force the router to go through its startup routine, which includes setting up the configuration properly. So in short, you force a reset on the configuration which will solve the problem if something there got messed up while the router was running.",
"So in a perfectly working system you wouldn't think you need to reboot. But things like power changes / brownouts, Network interruptions can all have adverse effects on a router and its ability to hand out addresses properly. Sometimes to resolve this we can bring it a electronically cleaner connection by using a good UPS that has surge capacity built in for phone or data line. If there's a buggy bad device on the network (sometimes it just takes an older device) you may find that you have more issues when one device is having issues and is constantly re-asking for data."
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n6x2d3 | Where does the data go when you format a disk? | Let's say your disk is 500 gigabytes. At around %80 percent you perform a disk format. What does the computer do to the 400 gbs of data, to have that disk empty? Also how is it so that the disk don't get full because you already stored around at least 500 gbs of data before? | Technology | explainlikeimfive | {
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"Write something in sand. Now brush it away. Where did the data go? To the same place as data on a hard drive.",
"It doesn't go anywhere. It stays on the disk and is marked as free space until something new overwrites it. VSauce has a good video about this: [Where do deleted files go?]( URL_0 )",
"There are two ways this works: 1. In a full format - the entire disk is filled with ones or zeroes - this all data is permanently erased 2. In a quick format - a new file system is created. A file system has a log of all the files. So for example it might say at the 250th GB you have this photo of your grandmother saved. Now when you open that photo, the computer looks at that section at the 250th GB. When you quick format and delete that log - the computer sees it as random data and ignores it. Often data is fragmented - if you save a 100GB file - the computer might break it into 10GB chunks and save each chunk in a random place. In this case the log will say this is part 1, part 2, etc."
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n6yos8 | why can’t phone cameras just record horizontally whilst in a vertical orientation? | Technology | explainlikeimfive | {
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"The sensor is a rectangle, not a square, and it’s proportional to the phone’s rectangular dimensions. So when the phone is held vertically, the camera sensor is also vertical. If you wanted the image to be horizontal then you have to crop it, which means you’d be using less pixels than the sensor is capable of. That’s something you can easily do after taking the picture so most manufacturers don’t bother to complicate the picture taking software with that sort of option when taking a picture. Someone certainly could build a phone where the sensor was perpendicular to the camera orientation so that you could use the full sensor but probably not many people have ever requested that feature so it’s not going to be very common.",
"Phone camera sensors do not have the same resolution horizontally vs vertically - while it's certainly possible, you will lose some of the resolution (and hence clarity) vs manually rotating the phone."
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n70ht7 | How do modern smartwatches calculate steps, blood pressure and oxygen level in blood ? | What are the technology behind this ? | Technology | explainlikeimfive | {
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"Oxygen level is done via the color of your blood. That is called *Reflectance pulse oximetry.* The watch shines a light on your skin and the color reflection lets it measure blood flow and oxygenation. Steps are calculated by the accelerometer, which basically measures how fast and where the watch is going. There is a little math and analysis going on, but basically one swing forward and back is one step, because we swing our arms synchronous with our legs."
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n71cyr | What happens when an electronic device gets "bricked"? Some parts have to still be salvageable, right? | Technology | explainlikeimfive | {
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"It usually means that the firmware or software that boots up the device has become corrupted and prevents the device from even starting. It is usually possible to get a fresh install from another source pushed to the device, but you may need special equipment to do it.",
"“Bricked” is a general term for any failure that causes the device to not turn on. This can be a software failure and all the hardware is totally fine, or it can be a total loss because you dropped it in boiling saltwater. How much a bricked device is still worth and how much data can be recovered is a case-by-case situation."
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n73dia | - Why are the cars in Formula 1 and Formula-E not identical on the outside? | Technology | explainlikeimfive | {
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"Formula E cars are much smaller to run on the tighter street circuit tracks the series typically runs. Lower speeds, tighter turning radius, more bumper car action. Formula 1 cars are *much* longer for aerodynamic efficiency at high speed on more traditional tracks like Spa. They physically couldn’t get around some of the Formula E tracks, and can barely get around Monaco these days. Formula E is also basically a spec series for bodywork so that manufacturers are spending their money researching road-relevant battery and generator technology and not fighting over aerodynamics.",
"They are completely different race categories with different restrictions. From an engineering standpoint it’s also a very different layout. Formula one cars have a 1.6 six cylinder engine behind the driver formula e as a large battery pack in the floor."
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n74exc | Why do USB-Sticks get hot when you transfer data? | Technology | explainlikeimfive | {
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"The sticks contain a little chip that is able to store data. In order to write or read data from it, a current must pass through the chip. When a current passes through something, there is some resistance, meaning some of the energy of that current is lost as heat. This is the same for all electronics and it's why computers have fans to cool their components.",
"Same as why anything else electronic or electrical gets hot when you use it: [resistive heating]( URL_0 ). Because there are no perfect, 100% efficient electrical conductors, when you pass electricity through a wire some of the energy is lost due to having to overcome the resistance of the conductor, and that waste energy is shed as heat."
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n7bjnh | Back in the late 90s and early 2000s laser pointers were very popular and you could put different tips in them to get different designs, how did those tips work? | Technology | explainlikeimfive | {
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"The lens have a structure called \"diffraction grating\". If you watch ocean waves passing around a series of rocks, you'll notice that part of the wave is reflected and overlaps with the original wave, making a complex pattern. That pattern depends on how the rocks are arranged. Since the laser light behaves like a wave, the same strategy can be used to make the wanted pattern. The lens have a series of cuts that behave like the rocks in the example and are arranged in a way that creates the desired image."
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n7bssb | why do most electronics, like controllers and remotes, need two batteries instead of one? | Technology | explainlikeimfive | {
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"Modern electronics operate off of semiconductors. Diodes and transistors. This includes LED's. These are electronic devices which do almost nothing below a set voltage. Only above this voltage do they become active. While the exact voltage can vary, this would usually be near or above the voltage of one battery (1.5 v). So, to get some function out of them, the voltage must be raised a bit. The easiest way to do this is to add a second battery.",
"They do not need two batteries you could make a remote that only use one battery. The problem is that the voltage that you need of a typical IR LED is 1.4 -1.6 V. There will be some voltage drop over the transistors you use to control it. The other chips will also have a min operational voltage. A new AA and AAA battery is at 1.5 but drops quickly when you use it. The voltage when almost empty is a bit over 1V. A rechargeable AA battery is at only 1.2V With 1 battery the device needs to operate at 1.5V and need to go down to 1.0V to use most of the battery but with 2 batteries you are at 3V to 2V The voltage range for a single battery will be too low to operate an IR LED quite quickly so you need to add a DC-DC boos circuit. The problem is that the will reduce efficiency because voltage conversion is not 100% efficient. So one battery will last less the half of two. The extra circuits also some money. Not a lot but the cost is higher than including an extra battery with the remote. There are 3V button cell batteries that are smaller and when you find them in remotes they tend to use only one. For consumers the 3V battery has some problem, there is a lot of sizes so to have extra at home require lot of batteries. They are often very expensive in stores to compare to AA and AAA batteries. So for a device that fits a AA or AAA they are a cheaper and more practical option for the consumer. The result is for remotes where you do not need minimal size the best option for the manufacturer is to use 2 batteries. for minimal size, a 3V button cell is used."
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n7d8pt | How does a computer keep track of time when turned off? | Technology | explainlikeimfive | {
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"Some components of the computer do not turn off, and are sustained by an internal battery. This includes the clock.",
"They have a small button-cell battery. If you have an old computer that loses track of the time when it gets turned off, you just need to change that to fix it.",
"Inside your computer is a motherboard and the thing that controls it is called the BIOS (basic input output system). On the motherboard there's a chip for the clock and that chip is powered, as others have said, by a cr32 battery so it's never powered down. That's how your computer knows what time it is.",
"Some computers make a call out to an atomic clock over the internet to get the most up to date time"
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n7hsfg | Why are some magazines for weapons curved, and others straight? | An example of this is 7.62x51 NATO, typically in 20-round magazines, but there are also some 7.62 magazines that are curved and not straight. Magazines for 7.62x39mm also have a distinctive curve, which is more extreme compared to other magazines of other calibers. Why is this the case? | Technology | explainlikeimfive | {
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"> 7.62x51 NATO This cartridge has a casing body with [sides which are parallel]( URL_0 ). Stack them on top of each other and you get a straight stack. > 7.62x39mm This cartridge has a casing body with [sides that are angled toward the tip]( URL_1 ). If you stack them on top of each other you get a curve. Curving a magazine can provide more space for ammunition without excessively expanding the space requirements of the weapon, but the shape of the cartridge itself shouldn't be ignored.",
"2 reasons: The first is that many carbine and rifle cartridges have tapered cases, meaning that when they nest together, t[hey naturally form a curve]( URL_0 ). Magazines meant to hold a specific cartridge tend to follow this curve, which makes feeding cartridges into the gun more reliable. The second is that beyond more than 20 rounds, for an intermediate or full power cartridge, the magazine just sticks out too far. Curving it allows the cartridges to hold 30 rounds without sticking too far below the gun which would make it difficult to fire in a prone position."
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n7l2hd | How does underwater torpedoes propell and explode to cause maximum impact? Doesn't water extinguish the flame? | Technology | explainlikeimfive | {
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"Premodern torpedo. Torpedo hit your hull, the detonator detonates the giant payload (either by contact or prox fuse) the BIG CONCUSSION hopefully breaks a hole in your hull, and you leak. This is much much less effective because you rely on flood to sink, its why you see ww2 ship sinking only after multiple torpedo hits. Modern torpedo. Big explosions, BIG FKING EXPLOSION under the ship. and when explosions happen, it displaces the water. Here's the thing, most ships will break on land, because ships are designed to have buoyancy in mind to support the ship's shape. If there is a giant ball of nothingness and the bow and stern are still held up by water, the excessive weight (especially when majority of the weight is centered in the middle section of ship) will literally break the ship in half. And obviously post attack ship sinks. & #x200B; Neither method actually produce a high chance of fire. The only possible event for a torpedo caused fire (direct) is for a torpedo to strike a ship, penetrate the ship's hull, gets lodged, explode. But if the hull is so weak that even torpedo can penetrate it. the explosive will very likely just turn the entire ship into smithereens.",
"The explosion is a chemical reaction and doesn't require oxygen from the surroundings to create, by having the explosion taking place next to the hull of the ship the water pushes all of the force of the explosion into the ship rather than letting it dissipate, once the explosion has happened there is very little direct reaction from the explosion the water will \"extinguish the flame\". However the explosion may have caused other fires to break out in stored ammunition or fuel or oil for the engines.",
"Torpedos do not need air to get oxygen as they carry their own oxidizer supply both for the propulsion and in the explosive. And when they explode the purpose is not to set the other ship on fire. However it is to damage the structure of the other ship causing it to get huge openings in the hull to let water inn.",
"Depends on the torpedo, some chemical reactions used make oxygen from the water. When It hits it's target (either electronically or magnetically detonated) it the explosive makes a shock wave, which is what causes the bulk of the damage",
"It is kinda like a bullet with a propeller. The explosive is contained in the torpedo. If water has got into either one if them, they might not work or malfunction.",
"The explosion is not a 'flame'. It's the chemical reaction of the explosive elements being ignited. This ignition generates rapid expansion of gases, and this expansion generates a shock wave in the surrounding water. It's the shock wave that generates the most damage."
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n7tdes | Why does extremely old footage appear to be sped up? | Watching old footage like from the 1920s appears to be going at 1.5X. Why is this though? | Technology | explainlikeimfive | {
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"As others have said, there wasn't a standardized frame rate (24 frames/sec) until the mid-20s. The illusion of movement happens as low as 15fps, so cameras, early on, filmed anywhere from 15-30fps. So footage that was filmed at 15fps and projected at 24fps suddenly looks sped up. **But they were never meant to be seen that way. Whoever transferred them screwed up.** Every silent film we have ever seen was a transfer onto 8, 16, or 35mm, done 50+ years ago, as cellulose nitrate film aged incredibly poorly; it became brittle and combustible (hence, less than 10% of all silent films made exist to this day). They burned like a modern-day Library of Alexandria. If they were originally transferred at the wrong frame rate, that is the only way we have ever known those films to exist and the originals were destroyed so it can never be fixed properly. After 10, years I finally got to use my degree. Thank you for asking. Edit: Yes, changing the framerate is very easy in the digital age. Every film could be corrected in speed as frames were transferred 1:1. 75+ years of silent film played too fast has changed the language with how we perceive it (i.e. it may look unnatural to us if it were corrected). It is a major part of the history of film and I think distributors choose to leave it as a document.",
"As far as I’m aware it’s for two distinct reasons: 1. The frame rates of the cameras were incredibly low and when played back on devices with a much faster frame rate, it speeds everything up. 2. Also there was a period of hand cranked cameras being the standard, so controlling the speed was down to humans which is another reason for sped up and inconsistent footage. I’m not sure if the two reasons can both be applicable to the same footage but if so that would probably explain the most extreme examples.",
"The frame rate was slower (18fps). When it’s played back on newer equipment it has to match the frame rate for now (24 or 30fps)",
"The Peter Jackson WWI documentary has a whole section on this and how they compensated for it. It’s fascinating but also really brings the reality of those boys at war to life.",
"Extremely old footage used cameras which were hand cranked so the cameraman could change how many frames were shot per second by changing the speed of cranking, so when they are replayed at \"normal\" speed the people appear to be moving really fast."
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n7zu3p | How come that professional cameras rarely have above 40 Megapixels but some phones have 50 or even 100 Megapixels? | Technology | explainlikeimfive | {
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"Megapixels say little about camera quality. The value of a full size professional camera is in the huge sensor and the large, very complex interchangeable optics. A phone camera physically can't be as good because the laws of physics regarding optics require set sizes and lengths in the optical path to produce a good image. In fact, the higher the megapixels, the worse the camera is - increasing pixel density makes each pixel noisier and worsens low light performance. Those 40-100 megapixel cameras are there because of the marketing departments dickwaving with large numbers. The iPhone and other fancy phones use machine learning and other software tricks to automatically fix up the image afterwards.",
"Megapixels was a major thing in the 2000's and worked as a selling buzz word and nowadays a lot of the buzz is around sensor size and mirror less operation but like the other poster said, it's not all about the pixels. Lens quality and the range and ability from interchangeable SLR and other modular systems combined with quality pieces of glass and the general know how of photography like exposure and composition is what makes the difference. Not many cellphone cameras let you operate in full manual or use high end lenses. Edit: sorry, grammar on a phone keyboard can be horrible.",
"Because they trade off pixel count for pixel (each individual, physical sensor) size. Phone camera sensors are about 25 mm^2, while (the \"standard\") camera sensor is 36mm by 24mm. Pixel size matters when it comes to capturing more light (which full sized cameras take full advantage of), meaning you can get away with using settings which would make a phone's camera unable to take usable pictures. Aside from that, \"professional\" cameras work with raw format, which have very little compression for more flexibility while editing, if needed. Because they have little compression, they're huge in size (my 6D's 24MP raw images weight 24 Mb, while Sony's A7's 40MP raw images weight around 100 Mb).",
"Megapixels is a measure of 1 million pixels on the sensor, 40 megapixels is 40 million pixels. Now that's just how many pixels the camera sensor can see, how much you want to save is largely independent of that, for your average Joe, you don't really want to save more than ~8 million pixels (4K images are 8294400 pixels exactly), so the camera will just average the pixels out. For a studio environment they will use those 40 million pixels exactly as the sensor sees them."
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n86lcc | How did the scientists track the falling orbit of Long March 5B in real time, and make predicition about the possible landing spots? | Technology | explainlikeimfive | {
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"Radar. Radar tracking can tell us the position, altitude, and velocity of any object. Over the last few days, various governments were tracking it with radar and noting how its orbit was degrading. We can do a reasonably good job of modeling orbital decay so we could say \"its altitude is dropping by X amount each orbit, by this orbit it'll be so low that it'll just burn up\". Of course there are always variables so we couldn't pinpoint the exact spot until after it happened."
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n86o0b | Why is it such a big deal if the source code for a program/website is leaked? What's the worst someone could do with it? | Technology | explainlikeimfive | {
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"The source code is like the recipe for that software. It literally is what the program does and how it works. There are two reasons source code leaks are bad: 1. A competitor can get it, figure out how the key bits work, and add them to their own software. This negates whatever competitive advantage the original company has. 2. A malicious actor can find bugs and write exploits for them. Potentially opening up whoever uses the software to cyber attacks.",
"Someone could work out if there is a potential flaw in it and use it hack the system. What could they get? Well depends what's stored? CC numbers? People's passwords? People emails, addresses? Maybe other stuff. Or they could just sell the flaw to criminals who could do it. Identify theft is a thing. And next what about the trust the company has lost? Who would trust them with info? This is the kind of thing that could destroy a business and potentially the lives of many people."
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n8a5u2 | what can you do with an IP address? | Hi, so what can someone do with your IP address? So if someone managed to get ahold of my IP, can they find out where I live, and essentially my identity? Just wondering because I’m wondering how streamers get swatted. I’m not going to swat anyone obviously but I thought IP address only show a geographical location, can hackers really find out where you live and your identity? Or is an IP address useless? What can an ordinary person or hacker do if they got ahold of your IP? | Technology | explainlikeimfive | {
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"> So if someone managed to get ahold of my IP, can they find out where I live, and essentially my identity? At first they can find out roughly where you live. So like your next bigger city, nothing else. If they want more they need the information your ISP has, and they will only give it out to the police when they have a warrant. So if you're not doing anything illegal you shouldn't worry about people seeing your IP. In fact every website you visit has it.",
"As others have said, it really depends. IP addresses identify your ISP; your ISP is likely able to map an IP address (and the time it was used) to a given customer. So law enforcement, or someone who works at your ISP, can probably determine your real-world identity from your IP address. A random person on the internet is far less likely to be able to do that; what they are likely to be able to do is identify your rough geographic area, through a variety of techniques. (The network layout of many ISPs--the IP address, but also the route to get to that IP address--often gives away some rough geographic data, at the city level; a number of services also exist that aim to do better (more accurate, finer grained) IP geolocation from other data sources.) However, again, it depends on what kind of access someone has. I'm dating myself here, but an oldie but goodie is Samy Kamkar's talk from Defcon 18 (which apparently was back in 2010, so apparently I'm old now?): [ URL_0 ]( URL_0 ). Some of this is no longer current, but it gives you a sense of what might be possible."
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n8aazd | How can Digital data be stored on Magnetic tape? | Technology | explainlikeimfive | {
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"to simplify: magnetic tape is a piece of plastic with some iron on the surface. Iron can be magnetized if exposed to a strong enough magnetic field. A magnet has two poles, north and south. The easiest way to save digital data on a tape is to expose each section of the tape to either the south pole of a magnet or the north pole and magnetize it. The write head has a strong electromagnet that is used to generate the required magnetic field. Since digital data is a series of 0 e 1, each bit can be encoded as the orientation (north or south) of the magnetization of the tape. The read head has a sensor that detects the magnetization without altering it. Modern devices are more complex than that but the principle is the same.",
"Just as one can encode analog data (sound, images) on digital signals, the opposite is also possible: encoding digital data on analog signals. Magnetic tape just stores the digital information in the patterns of magnetism on a magnetic tape. This is exactly like how data is stored on a hard disk drive, but instead of a spinning metal platter, the magnetic pattern is stored on a plastic tape."
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n8p0xo | Why do SD cards have higher storage capacity than thumb drives | Technology | explainlikeimfive | {
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"You may need to take a look at the catalogs again. You do get thumb drives up to 2TB at quite reasonable prices today. And these may be small enough to fit entirely within the USB port without anything sticking out. In fact most thumb drives on the market is a tiny chip inside a big case.",
"The physical side of a thumb drive is scaled to make them easy and convenient to handle. SD cards typically get inserted and left in place. Personally, I worry more about losing a thumb drive more than a SD card. I have a few very large thumb drives. Like 1/2 terabyte. I suspect that the is just not the market demand for larger thumb drives but the limit in available products is not a technology limit."
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n8sjkt | How did memory in computers increase over time? | I'm having a hard time wording this one. We always see posts about how a super computer decades ago holds less capable memory than a hard drive today. How does that work? What changed? How are advancements even made? | Technology | explainlikeimfive | {
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"Over time, due to technological advances, semiconductors have become smaller and smaller. As a result, microchips are able to perform more calculations in a smaller footprint. By the same token, memory chips are able to hold more data because more diodes, switches, and transistors are able to fit into a smaller area (on a solid-state drive). Not sure exactly how this tranlates to mechanical hard drives with magnetic platters and a stylus, but I imagine it's more or less the same concept.",
"There are these pieces in computers that are called capacitors. They’re either turned on or off. That’s where code gets the 1 and 0 for either on or off. Over time these capacitors have been made smaller and smaller which means there are more switches inside giving it more power!",
"The manufacturing process for semi conductors is constantly improving, meaning they can make circuits smaller and smaller and with increasing amount of complexity. This means that with each passing year they can put more and more memory onto the same chip while reducing the cost. A lot of what this comes down too is the ability to etch silicon wafers accurately down to smaller and smaller sizes."
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n92g75 | what is vRAN and how does it differ from RAN? (Whatever that is) | Technology | explainlikeimfive | {
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"RAN is a configuration of hardware. vRAN is a virtual implementation of an RAN. the vRAN can be updated/modified by a software update, whereas to reconfigure an RAN, hardware needs to swapped."
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n92zjz | Why did digital audio/cds allow for increased dynamic range and wider stereo separation compared to vinyl? | Technology | explainlikeimfive | {
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"A record player needle can only vibrate so much. That accounts for the higher dynamic range of CDs, the difference between the lowest and highest dB sound it can produce is lower for vinyl. This also accounts for the higher level of stereo (channel) separation. There is a lower dynamic range to work with on vinyl, so the channels can't be as far apart.",
"Vinyl only allows a needle to lift or drop so much, limiting the range that it can produce. It is also limited in how fast it can go up or down, creating some limitations for how quickly you can change from a low note to a high note (or vice versa).",
"Vinyl records audio directly in a single groove. This means there are technical issues -- how thick is the needle, how fast the disc is spinning, how precise is the manufacturing, how small of a feature the plastic can have, what is the needle's inertia, etc. All of those things directly affect how precisely it can represent the signal. That's also why not just any record player will do. How good is the driving mechanism and the quality of the needle matters. In digital similar issues exist, but the important difference is that they don't change how precisely the data is represented, they just affect how many bits we can squeeze into a given amount of room. We can allocate the available bits in any way we want. So if you want to put 24 bit, 192 KHz audio on a CD, you can. You won't fit a whole lot of it, but that's the only issue. For stereo, since there's only one groove, stereo is encoded at an angle. The incorrect ELI5 explanation is that one channel is left/right and the other is up/down. The real explanation is that this is that both are at a 45 degree angle from the vertical. Meanwhile, in digital we can just interleave channels. Have a track that goes \"5ms of channel 1, 5ms of channel 2\". You can have as many as you like and the separation is perfect because they have nothing to do with each other."
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n96j75 | Why are space rockets shot straight up? Wouldn't it be easier to make a spacecraft that ascends like regular aircraft until it's out of the atmosphere? | Technology | explainlikeimfive | {
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"They aren't shot straight up. They start pointing straight up, but very gradually turn so that by the time they have exited the atmosphere, they're more or less parallel with the ground. The reason is aerodynamics. The wind slows down the craft, so we have to make the rocket very pointy to cut through that. If we tried to slowly go up like a plane, it would need too much fuel, and fuel is heavy. The more weight you carry, the more fuel you need, so it goes in a big loop getting worse and worse. So the most efficient way we know of is to go straight up, then slowly level out. Even this is tricky with the amount of fuel needed, so there's lots of math and weight considerations.",
"They aren't shot straight up. They're shot in an arc. And to escape Earth's gravity you have to reach a certain speed. It's very difficult to reach that speed with an aircraft. Rockets provide much more thrust than aircraft engines. An aircraft engines push on air. The higher you go, the less air there is, and at some point aircraft engines won't work any more, and wings can't provide lift. Rockets carry their own propellant rather than pushing on the air.",
"Everyone posting earlier hit on various elements regarding escape velocity, regardless of actual trajectory, rockets provide the most efficient means to reach the escape velocity (25000 MPH). There have been a few engineering attempts with Virgin Galactic, but no one, as yet, has been able to engineer the amount of energy needed into a flyable form."
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n97t8h | Why some games need to be restarted when we change the resolution or graphics settings while others manage do it on the go? | Technology | explainlikeimfive | {
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"Let’s pretend all the code segments are little miners in in the gamebox gold mine who do all the little things that make the game work and the foreman is the main game application. At the start of the day the foreman issues them all instructions for the day saying they can mine up to 3 feet without a collapse. After mining the foreman realizes there has been a change to the instructions and now they can only safely mine 2 feet for the day. Instead of slowing down work by shutting down the mine and recalling and the miners the little foreman instead goes to find each miner and give them updated information himself. The foreman thinks he found everyone and gave them all updated instructions. But he forgot Frank in the lowest portion of the mine. Frank has already dug 2.5 feet when he feels the mines walls shifting. Frank quickly drops his tools and starts running but he’s too late, the collapsing mine swallows him. The ensuing collapse starts a chain reaction, the rest of the miners in the levels above him feel the floor fall out from beneath their feet. They too are trapped in the rubble slowly waiting for oxygen to run out in the all consuming darkness. Let’s say instead the foreman decided to recall every worker to the top on the PA system stopping work, took a head count to make sure everyone was there THEN issued instructions. None of the workers would be dead in a collapsed mine. TL;DR It’s to prevent crashing due to missing dependencies or missing/conflicting parameters",
"When changing some settings, it's just easier to reset all the variables to their starting values rather than trying to account for all the changes that would need to be made to allow the setting to be changed on the fly. For instance, maybe the game calculates physics based on screen resolution. Changing the resolution means lots of variables that were previously set need to be recalculated. This can become a nightmare for testing, and lead to very subtle bugs. So the easy way out is to just apply the setting after the game is restarted."
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n999pm | What's the difference between LED, OLED and Mini LED | I'm looking to get the newest iPad pro, and I was wondering what the difference was between the mini LEDs for the latest generation, the LEDs of the previous generation, and the OLEDs of the iPhone, since it's become such a huge selling point. | Technology | explainlikeimfive | {
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"OLED is a way to make tiny LEDs smaller than a pixel, so each pixel is its own LED and you get the best possible contrast and real deep black The problem is that these LEDs are made from organic materials that decompose and deteriorate if they are used too much and they can’t be calibrated as well as LCD LCD screens traditionally were just lit by regular fluorescent lights, but once we figured out LEDs well enough, we started using those instead for better efficiency and since they are easily dimmable we can now selectively dim dark areas of the screen to increase contrast, it’s not as good as OLED, but still pretty good Now we have mini LED which is just an LCD panel again, but the backlight has a lot more small LEDs so that you can have even more local dimming zones and even better contrast, again not as good as OLED, but still better"
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n9cgiq | how is space navigated after we leave earth? | Im assuming we dont use conventional methods (north, east, south, west or left and right), so how is it used on current space or will be used on future spacecraft? | Technology | explainlikeimfive | {
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"By knowledge of [**ephemeris**]( URL_1 ), a standard we agreed upon that JPL maintains. All objects in our system are constantly orbiting something. To plan a successful trip, you need to simulate trajectories of your spacecraft in relation to other moving objects, and that means knowing many **orbital parameters** in a commonly accepted reference frame, especially your starting point and destination. That reference frame is currently **ICRF** (international celestial reference frame, now on its third version) and it basically uses 1 - center mass of our solar system (as observed), 2 - calibrated by observed positions of quasars (radio signals), and 3 - an agreed-upon way of defining time. There are computed ephemerides tables available to you for this planning, actively maintained and computed from astronomical observations. The database contains over 1 million asteroids, nearly 4 thousand comets, 200 moons, 8 planets, our sun, lagrange points, and centers of mass regions, and it even accounts for galactic drift. You can access this database with telnet on any computer to plan a journey. For example: telnet URL_0 6775 phobos Enter some query dates and options and you will get reliable projections of where Mars' moon Phobos will be located tomorrow. Parameters are right ascension, declination of an orbiting body, in that ICRF (reference plane). Date__(UT)__HR:MN R.A._____(ICRF)_____DEC 2021-May-11 00:00 06 45 33.51 +24 27 07.6 2021-May-11 01:00 06 45 40.02 +24 26 58.6 2021-May-11 02:00 06 45 46.37 +24 26 49.0 2021-May-11 03:00 06 45 52.77 +24 26 40.4 2021-May-11 04:00 06 45 59.40 +24 26 33.1 2021-May-11 05:00 06 46 06.28 +24 26 27.1 2021-May-11 06:00 06 46 13.29 +24 26 21.2 2021-May-11 07:00 06 46 20.22 +24 26 14.5 It takes a lot more math and physics than just this, but all the centuries of knowledge humanity has distilled for astro navigation is available at your fingertips and it can be understood with great patience. Sci-fi authors have for a long time used or made romantic relative navigation terms such as \"starboard\" as a relative direction on the solar plane, meaning toward-the-star. But in practicality, that means nothing useful. Stellar navigation takes immense planning and computations, so it'd never be a directional estimate.",
"One way I know of are star trackers. Basically a camera which continuously takes pictures of the stars. The movement of the stars between pictures tells the spacecraft what orientation it is in.",
"Using points of reference. Leave the earth orbit and you still have the sun as point of reference. The directions in orbit are: 1) prograde, retrograde, that's in direction of your movement and against direction of your movement, 2) radial and anti radial, meaning directed towards the object you're orbiting and away from. 3) normal and anti normal, right angle to the plane of your orbit. \"Up\". This one is sort of arbitrary as there is no true up. You just come up with a convention. Earth \"up\" is north pole.",
"When we pass an Australian spaceship will the be upside down?",
"The ecliptic plane is the “surface” along which earth travels in its orbit around the sun. Another orbit can be inclined from that plane. The ecliptic plane intersects with [insert bunch of stargazing jargon here] at the ascending node. This defines a constant direction pointing out of the ecliptic plane, a bit like north being well defined on earth. These two are used to describe where an orbit is oriented/placed around the Sun. The orbit itself might also have a unique shape described by argument of perigee (rotation around its own axis), eccentricity, radii etc. Within the orbit you can usually define where you are within it using the eccentric anomaly which is analogous to hours positions on a clock but for an ellipsis and not a circle. You can also make a coordinate system with the nadir/zenith (in/out of the object you are orbiting aka up or down), north and east. This is used for things going out of or into earth from space. There’s a lot of different ways to measure your position and orientation as long as you have the correct measurement devices. These include sun sensors, star cameras, horizon sensors, magnetometers and gyroscopes. And of course good old gps and radio. If you have plenty of data you can switch between coordinate systems with ease, so you can take all these funky circle directions i described and turn it in to X,Y,Z if you wish."
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n9d5jm | Why the headphone jack hasn't been improved or replaced by any other type of connector since the 50's? Is that as best as it can get and there's no need for anything else? | Technology | explainlikeimfive | {
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"Because it’s not needed, it works fine now it is now, all you need is 3 (or 4 if you need a microphone) wires, and the 3.5 mm jack does that absolutely fine, why get a new standard? You’ll just make new problems for nothing Unlike other digital connectors like USB there is really nothing to be gained by improving it, you can’t “make it faster” because it’s analog, all the quality comes from the devices and not the connector",
"Simplicity and practicality. There are better cables and connectors for audio (see studio grade audio equipment), but the investment in said improvements makes things bulkier and costlier. The added benefit is imperceptible to 99%+ of listeners. The fact is, propagating audio signals is not that complicated from an engineering standpoint and the headphone jack as is does a fine job, even in the studio.",
"Because there's no reason to \"improve\" on it. It is cheap, works with any quality headphone set, and is extremely effective. And it also works for microphones as well. Think of it like the door frame of a house. The door itself and the house are changed constantly as time goes on, but the frame remains the same because it serves its function. The only thing that changes with a jack is the headset itself which can enhance quality profoundly while still using the same jack your $1 low quality headphones do. However, there has been improvements in the tech. It's called bluetooth. Bluetooth negates the need for the jack altogether. But if you don't want to charge wireless stuff constantly, the standard headphone jack invented in the 50s works even with the highest quality surround sound headset in 2021. There's just nothing about the jack itself that needs to change.",
"Look at it this way... What's 'wrong' with it? What do you need that it doesn't do? What different idea do you have that you think someone might need? There needs to be either a new supply or a new demand for something to change."
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n9db8u | How did a 70 year old computer (Lyons electronic office I) use Mercury as memory? [2K (2048) 35-bit words (ultrasonic delay line memory based on tanks of mercury)]? | Technology | explainlikeimfive | {
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"Delay line memory works by sending a current through a loop where it is slowed down. If you want to write, you wait until the loop comes to you and inject a bit value. If you want to read, you wait until the loop comes around and read what's on it. Mercury was one method used to delay the signal by having it turn into an ultrasonic pulse through a column of mercury, and then back into electric. One column could hold several pulses in flight at the same time."
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n9smnv | What Causes JPEG Compression? | I save, modify, and share a lot of images online, as most of us do, typically in the JPEG format. I often see JPEGs posted that are of very low quality, obviously having been saved and reposted many times, to the point that the lowest quality are considered "ancient." They get blocky, defined edges get blurred, yet it seems to follow a distinct pattern so that a JPEG corrupted in this way is still distinctly a JPEG. I know that saving an image and reuploading it will reduce the quality, but what are the actual mechanisms that turn a JPEG from crisp to a barely recognizable jumble of pixels? How fast does it happen, and what can or has been done to preserve image quality over time? | Technology | explainlikeimfive | {
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"Basically, any lossy copression will introduce artifacts. JPEGs are intended to make those artifacts relatively difficult for humans to spot in natural scenes, and for the most part, they do — but they’re not good for artificially-created scenes. Let’s make those artifacts obvious by looking at an artificially-created 32x24 scene with a variety of JPEG quality levels (lower quality means more aggressive compression, hence a smaller file). The first way JPEGs introduce artifacts is by transforming colors from RGB (Red Green Blue) into a colorspace that separates color information from gray level and reducing the number of bits used to encode color. The 100% quality JPEG most obviously differs from the master image primarily because of this. However, you’ll notice that at lower quality levels things don’t get blurry, but get distorted by a organic-looking, but blocky, pattern. That’s coming from the use of an 8x8 pixel DCT (discrete cosine transform) that compresses by limiting the range of spatial frequencies within each 8x8 block. An arbitrary sharp edge within an 8x8 pixel block requires both high and low spatial frequencies, so limiting frequencies can shift features; solid-color regions can get a pattern introduced. It is this 8x8 DCT that creates the block-wise distortions that most bother people when JPEG compressing images that contain lots of sharp edges and evenly-shaded regions — such as simple diagrams or a photograph of a natural scene with sharp text overlaid on it. Basically, JPEG encoding looks great for most natural scenes, but isn’t very effective for artificial scenes with solid colors and sharp edges. For the types of images that are most problematic as JPEGs, PNG encoding usually can produce relatively small files despite using lossless encoding. By the way, MPEG video encoding is very similar to JPEG compression, so you’ll often see similar artifacts.",
"JPEG is a lossy image compression format. Basically to reduce the space used by the image it does not store the value of each pixel but instead looks for patterns in the image and stores these pattern instead. And since it is lossy it is allowed to loose some informaiton. If the JPEG algorithm finds a pattern that fits close enough for most people to not notice then it will use this pattern even though it does not produce the exact same output as the input it was given. Lossy formats are much more effective then lossless formats. There is however a few potential issues with this. Firstly it is possible to configure the threshold for what it consideres close enough. And if this is set too low then you get a very small JPEG file but with visible artifacts in the output. The patterns it found took up very little space but the output image is only vaugely similar to the input. Secondly if you uncompress an image and then compress it again with a slightly different algorithm or with different settings it might not find the exact same patterns. This means that while it may be hard to distinguish the original from the first compressed image and this image from the final image there may be some clear differences between the original and the final image.",
"Storing every pixel as a separate data point gets *really* expensive real fast when you're dealing with images consisting of millions of pixels. That's why compression formats exist. The two main types are lossless (which conserve all the data so a picture can be exactly reproduced) and lossy, which make sacrifices and remove some data in order to reduce the file size. For example, jpeg groups an area that's approximately the same color into one big square and writes the information of 50 pixels as only one or two large pixels. If you do this once it saves a ton of storage space and since our eyes don't actually perceive pixels the same way as a computer does, the image still looks nearly identical. If you do this many times however, you end up with multiple passes of an algorithm that compound the mistakes and approximations of the previous pass. Kind of like the telephone game that we played in kindergarten, each pass loses a bit more information. The best way to avoid it is to share the original image instead of compressing it again. Don't take a screenshot, but instead directly download the image for example. That way the compression is already written in the image and your phone doesn't need to do it again. Edit: jpeg does a lot more than just that obviously, but that's the most prominent feature that gives it that blocky look"
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n9tdi4 | Why do some 'Heavy Games' like Arkham Knight, GTA V, Watchdogs 2, etc run without any issue (with acceptable CPU, GPU usage & temperatures exceeding not more than 50% & 70°C) where as while playing 'Light games' such as My Little Nightmares, Stick it to the man, etc GPU usage is around 80-90 | Technology | explainlikeimfive | {
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"Well, there are many reasons for this and I’m not enough of a computer expert nor do I know these games well enough to give you a concise explanation. But one of the reasons could be: - Optimization, sometimes, games just aren’t optimized, resulting in more unnecessary things being performed despite not being necessary to do the same thing. You’ll notice massive differences in things with huge lighting engines or generally just.. complex mechanics. To add on to that, My Little Nightmares isn’t exactly a light game (based completely off what I’ve seen of it) considering how many things are moving at once and all of the rendering that is done.",
"Developers on these games have often spent considerable time trying to get the most performance out of your system as possible by optimizing every single bit of code to give the same high quality performance with less resources. Smaller games are usually from smaller development teams who do not have the time to optimize the game and therefore end up doing a lot of things inefficiently taking up much more resouces then is required.",
"The more money and time you can throw at a game’s development, the more polished and efficient it’s code can potentially be. So if a game is one guy with no budget created, definitely won’t have 15 experts behind it all brainstorming the most optimized code for every single platform the game might be releasing on etc"
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n9tz8a | What are twitter bots and how do they work? | Technology | explainlikeimfive | {
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"Bots are basically just automated systems. There's a *lot* of different types. I'll focus on the simplest one: a follower bot. Follower bots are automated accounts that... follow a specific account. Usually this is a paid service. The accounts are made to look authentic at a glance so that they seem like real people. How they work is as simple as it sounds. They make a new account (or hijack one) and follow the account they've been told to follow. That's usually it. There's also reply bots, share bots, like bots... they function very similarly to Reddit bots, coded to do one or two things. Like Automoderator posting a comment in every thread with a rules reminder, for example. You can go deeper and make specific rules like \"share tweets with these keywords\". As you can imagine this is great for influencing people, and that's generally what they're used for."
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n9w60l | If I plug a usb-c power bank into my laptop, how does it know to charge the laptop off the power bank, and not the power bank off the laptop? | Technology | explainlikeimfive | {
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"USB is a 'smart' protocol. When you plug a device into another device, they exchange information with one another about their capabilities and then negotiate what each device will do/send to the other. If you plug the power bank into a wall charger, the charges says \"I'm a wall charger - I can give you power but that is about it.\" The power bank will then say, \"OK, i can receive power, so go ahead and send some.\" In contrast, when you plug it into your laptop, the laptop will say, \"I'm a laptop, I can do a whole bunch of stuff, including give and receive power.\" The power bank will reply, \"OK, I can send and receive power, so I'm going to send you power to charge.\" to which the laptop replies \"OK, send some.\" Now, the _actual_ conversation is technical (not colloquial) but the principle is the same."
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n9x0k1 | Why would anyone pay for a good or service with crypto? Isn't the possibility that it would go up or down in value a huge deterrent for both parties? | Technology | explainlikeimfive | {
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"Yes and yes. This is why the volatility of cryptocurrencies acts against their use as a *currency*. Part of the idea of cryptocurrencies is that they're free from government control and thus more stable - particularly, protected against inflation (their value falling). However currently they're behaving more like investments - where the value might go up or down, but a smart investor can tell when to buy or sell - or simply like gambling - where the change is completely unpredictable. (Or possibly even *scams*, where certain people can control or predict the changes.) That means you only want to *have* crypto if you're ok with the risk. Some people will use crypto in transactions because they like it as an investment. Some are true believers in its other benefits. If you just want to use it for a transaction, then you should buy it then use it or receive it then sell it as quickly as possible. Some business might accept it, because they know a proportion of people will like using it to pay, and then sell it asap. In some cases there are technical benefits to using crypto over other payment methods. In many others - perhaps most - the purpose is to conceal the transaction because you're doing something illegal.",
"My thoughts have been exactly the same for the last 4 years. I finally started investing in crypto for a couple reasons, I think blockchain technology has a place in the world. I also think some of the projects out there solve a problem. I feel like stabilization will come eventually but there is growing to do before then, which includes this volatility. Definitely do some research!"
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n9xigb | :Why does "percussive maintenance" sometimes work on delicate electronics? | Technology | explainlikeimfive | {
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"It is not as common on modern devices, but on older electronics the heat generated would often cause small warps in the circut boards or other materials. These warps would unseat components over time and break their connections. Hitting the device would often cause those components to reseat themselves, restoring the connection and restoring functionality. This doesn't really happen anymore as most components are soldered in place and don't come loose. TLDR - On old electronics, hitting it would knock things back in place."
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na40ie | Why do tech companies constantly change their terms of service? | Technology | explainlikeimfive | {
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"text": [
"There may be new laws they have to account for or explicitly address, there may be new technologies that come into existence or that they want to use and need to cover, they may need to better clarify based on consumer concerns/feedback or lawsuits/threat of lawsuits.",
"Generally it's to account for various laws being enacted or expiring. Say that there's a class action lawsuit against Company X, and the case gets decided upon a particular phrase in the X's Terms of Service, and Company X loses. You own Company Y, and you have that same phrase in your Terms of Service. You're going to want to eliminate that phrase as quickly as possible so you don't also get sued. Or imagine a state passes a law that forbids forced arbitration. You'll need to put an exception in your Terms of Service that say that the forced arbitration clause of your ToS don't apply in that state."
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na50jr | Why the colonial pipeline Hack caused a gas shortage? | Technology | explainlikeimfive | {
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"No, a lot of the company's operations had to be temporarily shut down because the computers controlling various pieces of equipments were [potentially] compromised. As such, oil products weren't flowing from sources near Texas up the east coast.",
"Running a pipeline means, among other things, that you have a lot of computers that help you. Computers that control the valves and the sensors that are spread out across the line. Computers that send and receive commands from the operators. Computers that collect statistics for billing. When your computers are at risk, so is your permit to operate the pipeline...because you will be blind. If something fails, you cannot guarantee that you see the failure. You cannot guarantee that the control equipment reacts as it should on a fault. You risk an environmental disaster that will cost you your company and the rest of it's profitable future, if you get a leak at a time when you can't see it and it gets out in the press and to the overseeing authorities that you knowingly risked a failure. Shutting down was the sensible option.",
"> Are there not manual controls that they can use to get the oil into barrels or trucks? Yea, probably like 3000 manual controls. Which is why a computer has to manage it. Can't have 3000 people standing at each control flipping switches all day. It doesn't scale."
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na5r4c | how the hell do you read those Twitter screenshots? I feel like everytime I see one they are in a weird order, and I never know the chronological sequence of comments. | Technology | explainlikeimfive | {
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"Especially on newer screenshots there will be a white line connecting the profile pictures of the people conversing. Simply read those from top to bottom.",
"It's so frustrating! Doesn't help that after 2 replies Twitter hides the rest and goes \"And here are unrelated tweets, formatted exactly like the replies were!\" Always feels like the conversation just abruptly goes full non-sequitor. I'd say it's the most-frustrating social media format in my life, but nothing will beat tumblr conversations that go more than 5 replies deep and turn into upside-down pyramids of letters",
"Normally, a thread of people replying to each other goes top to bottom. But if you see a tweet \"embedded\" within another (a quote tweet), you read the innermost one first - that one came first, and the user whose tweet you're viewing commented on it.",
"I couldn't finish the one with the vertical humpback whale. Twitter cropped both ends off."
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na64h1 | Why can't we use railgun technology to launch satellites into orbit? | Technology | explainlikeimfive | {
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"Low Earth orbit requires a speed of 7800m/s So lets say you have a humongous rail gun that’s 400 meters long. The lazy math says that to exit at 7800m/s, the satellite will be spending something around 0.06 seconds accelerating. That gives you an average acceleration of 130,000m/s^2 That’s 13,250 times earth’s gravity, and your satellite is pulverized.",
"Keep in mind, that going into space is not about getting up high, it's about going exceptionally, ridiculously fast horizontally. So fast that as you fall back to earth, you \"miss\" as the Earth curves away from you. This means that your rail-gun has to launch your satellite at a speed of about 8 km/s. This is 23 times the speed of sound! Rockets only start to hit this speed once they've left the thick parts of the atmosphere. The rail gun has the disadvantage of having the projectile hit that speed in the atmosphere. The result would be an absurdly high amount of pressure, heat, and drag. It's not just not happening.",
"We've [tried]( URL_2 ) several [times]( URL_1 ) at [this]( URL_0 ) point. Turns out its hard and requires a really really big gun. The root of the problem here is muzzle velocity, how can you get something moving at 8000+ m/s? A high velocity rifle round might be 1000 m/s, a high velocity tank round might hit 1800 m/s, but orbital velocities are significantly higher. Light Gas Guns are basically the only way to do this, they require a main explosion that squeezes a chamber of hydrogen or helium gas to build up the pressure and send it shooting down a much narrower pipe at high speed and launch the projectile on the other end. Bad news, they're big and don't work great with massive projectiles. SHARP was a ginormous light gas gun that had a 47 meter long barrel and it was only able to get a 5 kg projectile up to 3 km/s, that's about a third of where it needs to be and only the mass of about 3 cube sats. There was an even bigger version planned with a 3500 meter barrel to get things up to orbital velocity for the low price of $1B Rocket based launches are good for a few reasons 1. They work, we know that by now 2. They don't subject your payload to ludicrous G forces, most are under 3 Gs during launch so you don't need to make your satellite heavy by packing all the holes 3. They can move fairly large things, communication satellites are over 1000 kg these days 4. You aren't forced to launch into a specific trajectory like with a cannon We'll always be looking into space planes and non-rocket space launches but for now rockets work well enough and the price has been coming down for years."
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na82c5 | How does clicking a link to a malicious website allow hackers to gain control over a computer? | Aren't browsers suppose to be sandboxed? Assuming you never run any file that is downloaded, how does malware go from within the browser to gaining root access and encrypting your file system? | Technology | explainlikeimfive | {
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"There are various ways to break out of the sandbox. Among other things, the webpage can be set to automatically download a file when you load it, with virus files being quite small and quickly completed. Then, it is just a matter of tricking you into opening the payload. Like pretending that your computer has a virus and directing you to download their super awesome virus remover tool. Don't worry, it is all legit, the virus in your computer is just manipulating Windows into thinking our antivirus is a virus, really. Other fun tricks are to spread cheap casual games with an installer that installs special web browsers that allow for foreign code to be run. And yet another exists that runs a Macro (a prerecorded set of instructions) on Microsoft Word, which (you guessed it) runs a virus program. The best way to avoid many of these attacks? Vigilance. 1. Never click any sort of links in an unsolicited email. Not from a stranger, not from a bank, not even from your parents (until you have a chance to confirm they sent it). If your bank sends you an email about your account, type your bank website into the address bar. 2. Never click on ads. Like ever. But especially not when that ad is saying you won a contest, may be infected with a virus, or has a big blinking button that says \"Download\" 3. Never do your personal business on your work computer. That way, if you screw up, it doesn't affect your work, and if someone else screws up work, it doesn't affect your personal business."
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nahzob | how do voltmeters, or multimeters that can measure voltage, work? | Technology | explainlikeimfive | {
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"text": [
"I assume you mean the analogue ones. They run a current through a coil of wire which causes a magnetic field. There's a permanent magnet nearby so this creates a force proportional to the amount of current flowing. Then you have a hinged needle attached to a spring which converts the force into rotation. You can use this arrangement directly for measuring tiny electrical currents, i.e., as a ammeter. If you want to measure voltage, you use a resistor; the current that flows through the resistor will be proportional to the voltage. You can use different resistance values to measure different voltage ranges on the same multimeter; those dials on the front just switch in different resistors."
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naijgi | Why do news stories about new major diseases treatment (cancer, AIDS, and etc) end up as a story and not become widely used? | Technology | explainlikeimfive | {
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"text": [
"COVID not withstanding, it normally takes many years from a cure that works in a lab to turn into a cure that your doctor can prescribe you. The whole testing and approval thing takes time normally. There is also the problem that science reporting in mainstream media is terrible. The take things out of context, remove all qualifiers and come up with the most attention grabbing headline possible. Of course the press offices of universities and institutions aren't any help in this either. If there is a for profit company involved especially one seeking investors they will overstate things even worse. Some researchers may go \"we found promising results that may eventually lead us to a path to a potential cure for x\" and you read in the newspapers \"researchers found cure for x\" Despite all that we doe end up with improved treatments for all sorts of diseases all the time. You probably won't hear much about them unless you or someone close to you has that disease and you pay attention.",
"There's a bunch of science related reasons behind why but I'll go with the media angle. MAJOR BREAKTHROUGH ANNOUNCED! sells ad space, sells papers, sells whatever. PREVIOUSLY ANNOUNCED BREAKTHROUGH WAS A DEAD END! admits that your media outlet sucks at fact checking and not many people would care anyway because it's not click baity enough.",
"The vast majority of groundbreaking new disease treatments end up as dead ends for one reason or another, but when a promising new treatment fails to deliver, that's not news."
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nak3kv | How does Disney recycle animations from one movie to another? | I watched this video, that shows side-by-side comparisons of animations which were recycled by Disney in different movies: URL_0 As you can see, the movement and framing are practically identical in the clips, but the characters’ looks sometimes vary. For example, Little John has other clothes than Baloo. How is this recycling done? Presumably, iy saves Disney time (and probably money) to use the “same” animation, but there are still some changes made to the recycled scenes. What does the process of changing the scenes look like? | Technology | explainlikeimfive | {
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"Most of the work required to make animated movies is to figure out the motions of the characters. There is a lot of little details required to make the characters move in a realistic way. Once all the movements were figured out the process of actually drawing the characters is much easier. You are just looking at referance drawings and filling inn all the details on the scetches from the animators. What Disney did a lot was to reuse the animations from earlier films and just have the artists draw different characters on the same scetches. This means you do not need animators for these scenes and they can spend more time making the new animations for other scenes instead.",
"By tracing them. These were hand drawn animations, with each cell a picture drawn by a talented animator. So, they could use tracing paper and copy the rough outline of the image from the previous film, which would still be in Disney's storage somewhere, and then make this light changes to adjust it to be the new character for the new film. Reportedly, the process of tracking down the animation from the previous film and then having to slide the ultimate with so much of a hassle that animators felt it would have been easier to just redo it from scratch, but orders are orders."
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"url"
] |
naqtyu | How does rubber go from liquid from a tree to being a tire or a rubber band? | Technology | explainlikeimfive | {
"a_id": [
"gxv1wdj"
],
"text": [
"Rubber is mixed with various fillers, oils, resins, and anti-oxidation chemicals to get the right consistency and then a final mix of sulfur curing agents is added. When heated under pressure, the sulfur molecules crosslink the rubber molecules together, turning a bowl of rubber spaghetti noodle molecules into a solid and impenetrable molecular chain-link fence. This process is called “Vulcanization.”"
],
"score": [
6
],
"text_urls": [
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} | [
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|
naqxqj | How can one pipeline deliver different brands and octanes of gasoline? How do they separate them at the destination? | Technology | explainlikeimfive | {
"a_id": [
"gxv3nln",
"gxv3tqk",
"gxv0y39",
"gxv0sr1",
"gxvbbek"
],
"text": [
"All of these folks saying pipelines only deliver crude oil are incorrect. While that is the most common scenario there are some large pipelines that transport gasoline and diesel refined products along with typical crudes. These pipelines are batched systems and the operators account for an interface mix of the products (transmix). This is a sacrifical cut of a lower quality product to maintain the quality of the higher value product. The batch train lineup in the pipeline is carefully scheduled to avoid contamination.",
"There is an interface of the different fuels, like diesel and gasoline. They do mix a little but due to the different densities they stay pretty much separate. When the product (s) gets to a tank farm they will run that interface into another tank then likely introduce that into a diesel tank because the volume in the tank will dilute that interface and still.keep the product in spec (I mean a huge tank with thousands and thousands of gallons). I have worked where a pipeline comes into a tank farm and this is how they receive the different fuels. Like I say some mixing does occur but it's diluted in the large tanks. They will typically not interface with regular gas and premium because the density is too close and they would mix more. Edit This is for fuel pipelines, I am.not sure how or if they separate crude in the pipes.",
"They either use the mix or they will put in a \"pig\" a larger rubber stopper to separate the mix...",
"The pipeline only carries one thing, gasoline. After it comes out of the pipe additives are put in by the customer to raise the octane rating, add cleaners and detergents, etc. But every gas buyer is getting exactly the same gas out of the pipeline.",
"They can insert a pig into the pipeline, the pig goes between the different fuels. Example pig seen here: URL_0"
],
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[
"https://en.wikipedia.org/wiki/Pigging#/media/File:PipelinePIG.jpg"
]
]
} | [
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] |
|
nasz42 | Trying to choose between these LED therapy device options and understand why 1 is better than the other | Technology | explainlikeimfive | {
"a_id": [
"gxvea7p"
],
"text": [
"There's [no evidence they actually work]( URL_0 ), so you're probably wasting your money."
],
"score": [
3
],
"text_urls": [
[
"https://www.health.harvard.edu/staying-healthy/led-lights-are-they-a-cure-for-your-skin-woes"
]
]
} | [
"url"
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|
nb98b9 | Does the speed of the internet depend on quality of the LAN cable? | Technology | explainlikeimfive | {
"a_id": [
"gxy3xi0",
"gxy4r1v",
"gxy4tlh"
],
"text": [
"Kind of. In theory yeah different cables will handle different data rates. Making sure the cables are installed properly (no twisting, listen to the minimum bending radius, terminate properly) will help In reality I really can't see a LAN cable being the weak link for an internet connection, not unless the cable is outright faulty. For an internal intranet then maybe. Or maybe even an industrial office with internet. But a standard residential property I don't see it being an issue.",
"Your speed is only as fast as the slowest link. For example if you are using a cat 5 ethernet cable (rather than a cat 5e or cat 6), you are going to be limited to 100Mbps. Some cables are also shielded better than others, which prevents interference and improves performance.",
"Depends on lots of things. There are shielded lan cables because electromagnetic interference can induce unwanted noise into your cables. There’s different categories of cables to support various bitrates. For the last 20 years cat 5 has been sufficient, but in the last 10 years we see more cat5e, and lately people are building houses with cat6 or even 7 just to future-proof. If you have fiber-optic internet, a cat5 cable might be a bottleneck. If you’re at all concerned, get a good shielded cat6 cable and see if you have better speeds or less drops."
],
"score": [
7,
4,
3
],
"text_urls": [
[],
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} | [
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|
nb98zv | How are URLs guaranteed to be unique across the Internet? | For example, what's preventing me from creating a GoDaddy account and making my own domain called URL_0 ? | Technology | explainlikeimfive | {
"a_id": [
"gxy3mg8"
],
"text": [
"Ultimately, the Internet Assigned Numbers Authority (IANA) which sold GoDaddy the names they can assign. GoDaddy won't sell you URL_0 because they *can't*, and the DNS servers won't accept your claim of the address. The internet functioning depends on all these organizations working together, but you could totally do this within your own personal network. If you wanted to host your own DNS server and direct URL_0 to your own machine, then go ahead. But you can't do this for the internet at large, and if anyone tried they would be cut off from the rest of the internet in short order."
],
"score": [
8
],
"text_urls": [
[
"google.com"
]
]
} | [
"url"
] | [
"url"
] |
nb9uqn | How is it possible to convert a 30fps video into 60fps? | I've seen some videos that were originally 30fps get converted into 60fps, and it looks totally normal. Where do the new 30fps come from? | Technology | explainlikeimfive | {
"a_id": [
"gxy6kbw"
],
"text": [
"It’s a technology called interpolation. An FPGA (typically) at the frames either side of the one it wants to create, then predicts where things should be based on the motion in the past and the future. Then it draws the missing frame. As for it looking normal? Them’s fightin’ words."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
nbb3fy | Why cant gas cars use diesel and vice versa? | Technology | explainlikeimfive | {
"a_id": [
"gxydu9q",
"gxycqts"
],
"text": [
"Gas cars can’t use diesel because it doesn’t burn as easily and the engine won’t run well, furthermore it’ll ruin your catalytic converter While Diesel engines could in theory run on anything that burns, they are designed to take diesel fuel which is much more lubricating than gasoline, so the pump will break along with other stuff They both might run on the wrong fuel for a while, but not well and not for too long",
"Okay found the same post made a few hours ago"
],
"score": [
5,
3
],
"text_urls": [
[],
[]
]
} | [
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"url"
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|
nbcr9w | What is instantiation, explained to a non-developer? | Technology | explainlikeimfive | {
"a_id": [
"gxz0c7u",
"gxyk7e3",
"gxykqvw"
],
"text": [
"Instantiation means creating something using a mechanism to create it with certain constraints. Imagine having a 3d Printer File. Actually printing it would be instantiating (creating an instance of) that object.",
"When you instantiate something, you're creating a copy (an instance) of something. It's analogous to having a blueprint of a car and then producing (instantiating) vehicles (i.e. the copies/instances) from said blueprints.",
"A class is a box. When you press the blue button, [you *instantiate* a Mr. Meeseeks object]( URL_0 )."
],
"score": [
7,
6,
4
],
"text_urls": [
[],
[],
[
"https://youtu.be/qUYvIAP3qQk"
]
]
} | [
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] | [
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|
nbg84j | Ram Swap, turning Storage capacity to RAM | 1. How RAM and hard drive differs, and how is it possible to use them interchangeably? 2. This recently blew up in the android community, apparently this is not a new thing, so why is it not done earlier to cut costs as higher ram variant cost significantly more than the lower variant? | Technology | explainlikeimfive | {
"a_id": [
"gxz3bha",
"gxz5l24"
],
"text": [
"1. RAM is random access memory. It is the very fast, but impermanent memory that your applications use to do stuff while they are running. ROM is read only memory. It is used to store data that is not ever changed and only accessed - like an old video game cartridge. They are not interchangeable. 2. A RAM swap file is a portion of the hard disk that is used _like_ RAM when a system runs out of available RAM for its programs. The advantage is that the swap file prevents programs/OSs from crashing when there is no RAM to allocate, but it is _much, much_ slower than RAM so it is only used as a last resort.",
"ROM stands for Read Only Memory. Information is burned into the chip and cannot be updated. That would make it useless as RAM. RAM stands for Random Access Memory, the main type of memory used in computing systems because anything could be stored and retrieved from it over and over again."
],
"score": [
9,
3
],
"text_urls": [
[],
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]
} | [
"url"
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"url"
] |
nbs243 | What is the purpose of a video game disc? | Technology | explainlikeimfive | {
"a_id": [
"gy119dt",
"gy11k7g"
],
"text": [
"These days, one of the main uses is essentially digital rights management: the game can only be played if the disc is inserted into the console, allowing the game to be transferred between users. It's also nice when the whole game doesn't have to be downloaded from the internet, since that can take time and/or be expensive as well",
"You've nailed it - discs have no real advantage over digital copies aside from the ease to lend, sell, or transfer them and the niceness of having the box on the shelf. The only other really relevant perk is the ability to install a game without an internet connection - especially if you happen to live in an area with a poor or intermittent connection. But considering how many games need major day 1 patches to clean up bugs and such, an internet connection is still fairly handy for modern games. Even so, taking the primary game code (often tens of gigabytes) off of that download definitely reduces the annoyance for anyone with a poor connection."
],
"score": [
8,
3
],
"text_urls": [
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} | [
"url"
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|
nbvaa0 | How do they change the tires off an airplane? Do they have airplane sized car jack to help lift up the plane? | Technology | explainlikeimfive | {
"a_id": [
"gy1j307",
"gy1kb4h"
],
"text": [
"Special aircraft service facilities have stands that can support the entire airplane off the ground, in order to test the landing gear going up and down, particularly after the landing gear has been repaired or serviced. The same technique *could* also be used to change the tires, however it's usually easier to just use a lift on the bogey [like this]( URL_0 ) (it's the silver metal thing that says KLM on it).",
"There are lots of videos of aeroplane tyres getting changed on YouTube, you can watch them do it. They lift the landing gear off the ground with a jack- remember that the landing gear goes up into the plane after takeoff, it is designed to rise up without lifting the whole plane up. While they're lifting up one wheel the plane is still steady on the rest of the landing gear."
],
"score": [
19,
4
],
"text_urls": [
[
"https://live.staticflickr.com/5492/14345979489_3c29e6427c_b.jpg"
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]
} | [
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"url"
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|
nc35xn | How do multiplayer shooter video games track bullets. In games like Battlefield thousands of "bullets" can be fired in a round. How does the game know who fired what and who hit/killed who? | Technology | explainlikeimfive | {
"a_id": [
"gy2rc80",
"gy344rk",
"gy2w0yc",
"gy56pd7"
],
"text": [
"A bullet is an entity, storing the ID of the player who fired it and the direction of the bullet, maybe also what weapon fired it, the speed and the damage depending on the game It’s programmed to move until it finds another player or the ground and if it hits a player, damage is applied and since it knows who fired it you can do What You need to do. Another even simpler way that is used is to, when a player presses the trigger, look for all players in a straight line form the muzzle and damage the first one, since it’s instant, there is only one player that can shoot in that instant and you don’t need to store the player who shot it or anything, but this is falling out of use because it’s less accurate",
"This is basically a weird way of asking “how do computers work” or “How do games work”. Everything that exists inside a game is it’s own entity, or game object. When a bullet is fired, that bullet is an entity that exists in the game, and holds a ton of information. Information including what the ID of that bullet is (for example, ID 2887), who shot it, how fast it’s travelling, what direction it’s going in, is it effected by gravity, how much damage will it cause, how far can it travel before being deleted, etc etc etc. It just holds a list of everything it needs to know, and does some maths to work out where it’s travelling. A server is powerful enough to hold all of this information, for every bullet that ever exists in a game, 10000 times a second. Each player has their own “Player ID” of some form, so when a bullet hits another player, the sever is basically saying “bullet entity 2887, from Player ID 180837, collided with Player ID 788973”. “Reduce player ID 788973’s Health points by Bullet 2887’s damage output”.",
"1. You aim, pull trigger 2. Your game says to game server, he pulled trigger, aiming *here*. 3. Game server does some math, figures out what you hit, sends message back to your game. 4. Your game shows your enemy's head exploding (or not). 5. Meanwhile, if you blew his ass up, game server sends, \"YO ASS GOT SHOT!\" message to that guy. Or maybe just \"YUO DEAD, BRO!\" 6. This usually happens about 10 times a second, maybe more depending on the game. How does it keep track of everything? It keeps a lot of lists and updates them really fast.",
"Code is very simple minded. It's not very bright. There's a bit of code in there whose only job is to watch the player and count how many bullets they fire. So it's sitting there thinking... Nope. Nope. Nope. Nope. Yup! Nope. Nope. Yup! Now, if you ask it how many, it'll say 2. That's *all* it knows. There's another bit of code puts that number on the screen. That bit has no clue it's counting bullets, or anything else about the player that's firing them. It only knows how to put the number on the screen. When you break a large complex problem/task down to very small simple bits, it's much less complex."
],
"score": [
44,
38,
5,
3
],
"text_urls": [
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|
ncaxav | what is a horse power ? | Technology | explainlikeimfive | {
"a_id": [
"gy3xy9p",
"gy3x9d5"
],
"text": [
"Advertisement. To promote steam engines, they had to compare to something people knew. Mill horses, specifically. The amount of force or work the horse could do in 1 minute was estimated, then compared with the steam engine. So when the steam engine was marketed, they could advertise it as doing the work of 4 horses, or 4 horse power.",
"About 750 watts. It is a measure of power, or the strength of a push or pull. And it was called a horsepower because that is roughly the maximum fairly safe capacity you can pull with a horse. Obviously exactly how much the horse will carry will vary with the individual."
],
"score": [
14,
9
],
"text_urls": [
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} | [
"url"
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|
ncbu9q | When a video is lagging/internet cutting out, why does the audio keep playing for a while after the video has stopped? | Technology | explainlikeimfive | {
"a_id": [
"gy42f7a",
"gy42ll5",
"gy5hmts"
],
"text": [
"Because the audio and video are not entirely connected. You can load audio data from a video file without loading the video, and you can load video data from a video file without loading the audio. It's also not necessarily a 1-for-1 ratio - one MB of audio data in a file might cover 30 seconds of audio, whereas one MB of video data in a file might cover half a second of video.",
"First, we have to talk about what a thread is in computers. A thread is just a sequence of execution for a particular program. Many programs may be single threaded, which means it steps through one instruction at a time, and ends up jumping from task to task within the code. Others are multithreaded, which means multiple cores on your CPU can actually process different things for that application in parallel. Normally, the audio is run in it's own thread so that it does not have to wait if the main thread possibly being a little laggy (which would result in jittery sounds). It is traditionally made up of a series of sound files that are queued up by the main thread to play back to back to back. That thread can keep playing the sound files it has had queued for a little while after the main thread freezes, but once that queue is empty, it has nothing to do.",
"A CODEC works by spooling the data (in what's called an elastic buffer) before decoding it. This is an old trick for handling intermittent data pipes. When playing back the video, you can lose data for a bit, while the elastic buffer continues to provide data to the display (so you never notice the loss of data). Since the audio and video go thru separate CODECs their buffers are also separate and may be different sizes. And since video data rates are higher than audio, it takes more data to buffer the video than the audio for the same amount of time of buffering. In addition, CODECs work well by taking advantage of human factors. A well designed video CODEC will keep the audio going without disruption while losing the video since the human brain is more annoyed by loss of audio than loss of video. When you have an intermitten data loss, you don't really notice the loss of video (it'll start out as some pixelation, then if worse some freeze frames) because the audio continues w/o any disruption (and your brain just goes with the flow). Since it's easier to buffer more audio than video (because of the different data rates), and since it's important to keep the audio going even with loss of video, the CODEC will buffer more audio than video. So, when you completely lose data, the audio will continue spooling out for a little bit longer than the video."
],
"score": [
18,
3,
3
],
"text_urls": [
[],
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} | [
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|
ncc33q | What makes a gel pen write so much more smoothly than my other pens? | Technology | explainlikeimfive | {
"a_id": [
"gy4tis2"
],
"text": [
"I’m no pen expert, but it could do with the their being water in the ink. Other pens would often dry up or are uneven, resulting in skipping, ink drying as your in the middle of writing a sentence, and can look more rigid depending on the hand writing. A gel pen is more smooth, though smudging is more readily apparent and more likely to occur compared to other pens."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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|
ncc45g | How do games "tone down" the graphics for low graphics settings? | Pretty much what's in the title. How does the game choose what to "tone down"? Is it just the quality of textures or are there less objects? Is the polygon count affected? Is it all in the engine or do developers have full control over what elements are "expendable"? | Technology | explainlikeimfive | {
"a_id": [
"gy44xi1"
],
"text": [
"There are many options. They can reduce the draw distance, when objects get too far away, the graphics engine stops drawing them. They can change what this distance is, so that there are less objects to draw. You'll see this a lot in old games where objects just pop into existence as you move towards them. Textures can be lower resolution or not used at all. Different models can be loaded that are made out of less polygons. Features can be turned off completely: shadows, advanced lighting, particle effects, antialiasing."
],
"score": [
16
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
ncczrl | Lots of electronics take AA or AAA batteries which are round cylinders, 1.5V with terminals at each end. So why do some devices want a 9V rectangular battery with weird plug-in terminals on top? | & #x200B; | Technology | explainlikeimfive | {
"a_id": [
"gy4a06c",
"gy49gju",
"gy4ax88"
],
"text": [
"Most 9V batteries are actually a 6 pack of AAAA batteries (AAAA cells, technically)! The small rectangular format is just more convenient than a half dozen tiny AAAA batteries.",
"different electronic devices use different voltages. sure you can design electronic devices to use multiples of 1.5V but that makes it more annoying/complex. whereas a 9V battery has enough voltage to power a step up transformer and voltage multiplier so you can get whatever voltage you need without using 6 AA/AAA batteries. the weird plug in terminal is so people don't plug it in reversed.",
"The 1.5V generated by a normal alkaline battery is usually too low to do any practical things with. This is why most devices require multiple batteries and put them in series to generate higher voltages. But you may need to put in way more batteries then is reasonable if you want a reasonable voltage. You need 6 battery cells to produce 9V and even 6 AAA batteries are quite big for some applications. There are smaller batteries then AAA but they are quite big and heavy for their charge because of the metal casing that is needed around them. This is the reason for the 9V battery. It contains 6 battery cells connected in series all contained within a single metal casing. The connector on top is actually a fairly common connector for these types of battery holders. There are also other types of multicell battery formats. But none are quite as popular as the 9V format."
],
"score": [
13,
5,
3
],
"text_urls": [
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} | [
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nck2sw | What’s Kubernetes? | Technology | explainlikeimfive | {
"a_id": [
"gy5h5ja"
],
"text": [
"This is gonna be hard to ELI5 but I'll try. Think of a physical \"home computer\", say a laptop. It's got some internal circuitry, some short-term memory that it uses to store stuff when it's turned on, some long-term memory (often a \"disk\") that it uses to store stuff when it's not turned on, and other doodads like a mouse and keyboard and screens. In order to make those things work you need an \"operating\" (working) \"system\" (bunch of processes that help make it go). All that together is your computer, right? Cool. Now let's talk VIRTUAL (meaning not completely real). Instead of an actual keyboard, most smartphones just create a VIRTUAL keyboard on its screen that behaves like a regular one. It's not real, but it does the job. Now let's go bigger with VIRTUAL, and make a whole virtual computer! If your physical computer is powerful enough, you can actually tell it \"Hey, use your short-term and long-term memory to create 'pretend' computers inside you\". Each of those virtual computers inside your big computer aren't \"real\"... but they behave like full-blown physical computers! They each get a single chunk of its short-term memory, long-term memory and each has its own working bunch of processes (okay, \"operating systems\"). And each is separated from each other too. Okay, almost there. The problem with that virtual computer inside your physical computer is it needs its own operating system because it's a computer, right? *But what if you don't need all of that operating system?* What if you only need, say, ten pieces of it for what you want to do. ENTER THE CONTAINER (dun dun dunnnnnn) A container is sort of like an operating system, but it ONLY comes with the bare minimum needed to do what you want the virtual machine to do. No wasted space. No unnecessary commands that you'll never use. Just the bare minimum. Kubernetes... makes containers. Little virtual boxes inside big physical computers that run just enough pieces of operating systems to do the work you want them to do. And each is completely separate from the others."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
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"url"
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