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c3gnf3 | When standing up after sitting down for a while, why does your eyesight get blurry and your head gets dizzy? | Answer: when you stand up your head moves from low to high, but it takes your blood circulation a couple more seconds after that to adjust and sort of recover from the sudden movement.
This basically pulls your blood out of your head and lower down into your body, leaving your head with lower than normal amounts of blood for a bit, which can cause the dizzy head and the blurry eyesight. | 423a4c05-54e8-4288-9120-8b0de410e93f |
c3gog1 | how can light have energy? | e = mc2 is not the full equation
E²=(mc²)²+(pc)²
Is the full one. Essentially, with m=0, you can remove that part of the equation, and end up with
E= pc (with p being momentum, and light, since it cannot be at rest, has momentum)
This would apply to anything "mass less" such as a photon, as the mc2 part is zero, so you're left with the pc part only. | 05ae869d-a83f-4b19-97c8-453dcfae6c2a |
c3gpax | Why/how is there so much air in our stomach? Why is it upsetting and why is it relieving to burp it out? | The air gets into our stomachs because when we swallow we actually swallow air as well as food, drink, etc. and can also come from carbonated drinks that continue to release bubbles after we drink them. It can be upsetting whenever too much of this air is in the stomach because the air is less dense than the liquid in the stomach and will want to rise upward (in the wrong direction), this is also why it’s relieving once you’ve removed it through burping.
As an extra, when air comes out the other end it is typically caused by the bacteria in your intestines releasing air as a result of eating. This is why people are lactose intolerant. Lactose is just a specific type of sugar and people who are lactose intolerant don’t digest it themselves so it passes on to the intestines where the bacteria get to have an all you can eat buffet and the result is tons of air being released. | a9c5dd5a-788d-45e4-8a83-f8c6fb0404b6 |
c3gx6y | Why are there strong and successful campaigns to ban fur clothing and not other animal products like leather? | A lot of fur items like mink or sable are killed for their fur and the rest discarded. Cows and lambs are killed for their meat and the skin is also used to make leather. One case is wasteful and pointless, the other is resourceful. Also leather is really useful, fur is seen as elitist. | 08d97974-97f0-4c80-9cc1-5b24dce615a3 |
c3h9pa | why painting this ceiling made the light “less yellow”? | The camera has adjusted the white balance. Basically, it sees a lot of blue and wants to make the picture more neutrally colored (white), so it adjusts the whole thing to the yellow side, with yellow being opposite of blue. This is most visible on things that are white. In the second picture, it doesn't do that. | 6041ac00-5325-46b2-bea3-a4fd4de32190 |
c3hsi0 | What does the dot product mean in Linear Algebra? Why is it used in movement equations? | The dot product takes two vectors and calculates how much they "lie on each other" or "how much they align." Two vectors at 90 degrees from one another will have a dot product of zero since they do not lie on each other at all, while other vectors are less so.
More quantitatively, given two vectors A and B, the dot product is also a cheap way of calculating |A||B|cos(x) where x is the angle between the two vectors. Essentially calculating the value of cosine without actually calculating cosine turns out to be very useful in other aspects.
It comes up in physics often because quantities tend to be conserved in the 3 dimensions, that is say for instance momentum is conserved along the x, y, and z directions. Having to calculate these components often involves the use of trigonometric functions, at which point the dot and cross products can help due to their inherent nature. | 6498e3ee-7abf-4626-bd71-761385cce1cc |
c3hzsq | How does Dissonance work in music? | Adding onto /u/Wesseljw 's answer: The frequency-ratio is important (the worse the ratio between two pitches, the more dissonant it sounds - going up to the irrational sqrt(2) for the tritonus), but what is more important is that music would sound boring without some dissonances, really boring actually. The development in history in that regard is pretty interesting. In the middle ages very, VERY harmonic music was prevalent at first (gregorian songs etc.), but people started to see that as boring.
Then the relationship of two melodies that flow around each other was explored deeply (early Renaissance), it turns out that **having a short dissonance that resolves into a consonance is a really enjoyable**. A good **dissonance leads to a consonance**. Then two melodic voices were not enough and they kept adding more voices (polyphony, we are in late Renaissance there), with more complicated relations. That kind of music got explored more and got more and more complex (till late Barock, Bach(!)) until it got a bit too complex on the many lines of music you had to follow.
The reduction in complexity on the "everyone kinda plays the melodies" lead to there being a more pronounced melody and accompany for the melody. The loss in horizontal complexity (less "lines of music" to follow) was made up by more complex harmonics in the accompany part. Dissonances play a great role in that music. They lead to **tensions that you want to hear resolved**. In that era composers started not instantly resolving the tensions, but going from one dissonance to another (which was VERY surprising and novel to the people back then) until eventually resolving it into a consonance. These dissonances are usually in the accompany part and are still smoothed over in the melody, so that you don't feel appalled by them.
After that people got more and more crazy with dissonances culminating in the loss of any harmonics (Schönberg(!)), then, with the general public not really understanding (nor wanting to understand) music that just doesn't sound "good" in any way, multiple genres formed and built the musical landscape we have today.
The Tl;Dr you should take away is:
**Dissonances make music exciting because you instinctively want to hear them resolved into a consonance. Dissonances can not be seen out of context and whereas too many of them make any song sound really bad, too little make the song boring.** | b54ee586-ef3b-4648-89cd-f4c00c1b0b9d |
c3i443 | What is DEF Fluid for in diesel trucks? | Diesel Exhaust Fluid (DEF) is something that gets added to the exhaust system of large diesel trucks in order to reduce the concentration of harmful nitrogen oxide (NOX) compounds such as nitric oxide and nitrogen dioxide. These compounds contribute to smog and acid rain formation, as well as deplete tropospheric ozone.
DEF's active ingredient is urea, the main component in mammalian urine. When it's exposed to hot exhaust gas, it undergoes a series of chemical reactions that convert the harmful NOX compounds into harmless nitrogen gas. | c57ec95e-97a9-4bd9-93ee-9b6be7b7138e |
c3iz3c | Why does the temperature decrease as you get higher up towards the atmosphere? | It’s colder because at a higher altitude the air is much less dense, meaning there are much fewer particles per cubic meter of space. Since solar energy or heat from the sun is primarily trapped by bouncing between atmospheric particles, the thinner air at high altitudes can’t trap heat as well and so it’s cooler :))
Hope this helps! | 4de77723-517d-4930-93ab-98b2c528fcbd |
c3j5hr | Why do lymph nodes swell up? | Lymph nodes are like little reservoirs for lots of white blood cells (the ones that fight infection). When an infection is recognized, lymphocytes that are trained to go after that infection start to proliferate in lymph nodes, forming "germinal centers"
These germinal centers can get really big, and because lymph nodes have a capsule, they are sort of like a balloon. More germinal centers = more white blood cells, so the balloon has to expand. Swollen lymph nodes are just lymph nodes with actively proliferating B cells. | a454dcc0-4d65-41eb-8105-836204c9bd21 |
c3jenz | Why, with all our advancements in telecommunications and phone technology, has phone call audio quality stayed virtually the same as ten or twenty years ago? | In simplest terms; because the telephone system is an internetwork of individual links, it is limited by the least capable link in the system. Think of having a road between two cities that starts out as a five-lane Interstate highway, drops to a dirt road, then goes back to a five-lane highway and then arrives at the destination - the traffic is limited to the capacity of the stretch of dirt road in the middle.
In standard telecoms that limitation is the enduring use of [G.711 encoding](_URL_6_) to convert analog sounds from the two ends of the call into digital information that will be carried over digital [trunk circuits](_URL_0_) in the middle. Those circuits, at least in North America, are built around the [T-carrier architecture](_URL_5_) (with the ulaw variant of G.711), which has a hard limit of 64kbps of information per circuit which, skipping over a whole bunch of technical stuff, translates into only carrying sounds between [300 and 3400Hz](_URL_2_) \- everything else within the typical range of hearing of 20–20,000Hz is simply discarded.
Various methods of delivering [wideband audio](_URL_3_) over conventional digital telephone networks do exist (eg. [G.722](_URL_1_)), but if the call will eventually terminate on a conventional analog telephone (or cellphone) then the extra effort to capture and transmit that extra audio information just goes to waste as the signal must be [transcoded](_URL_4_) to meet the capability of the lowest common denominator in the end-to-end circuit.
On the other hand with pure VOIP calling, for example with Skype-to-Skype calls, most of the internetworking issues are eliminated as the sound is transmitted entirely as a stream of data which is controlled exclusively by the two ends of the call, and so the system can transmit as much audio spectrum as the designers wish.
& #x200B;
edit: goodness, gilding? I'm flattered! | 869ac5b9-abf0-4ffe-ae56-7d68bf152af7 |
c3jkx5 | Why the sudden disparity in chromosome number despite difference in complexity and intelligence? | Just because a book has more pages doesn’t mean it’s a better book.
Chromosomes in different species do a lot of different things, and some are more or less efficient, some specialized and some not.
The number of individual chromosomes (out of context of a species) is unrelated to pretty much anything | 26cf5d66-1705-4b70-8ed5-65ef22b4fab7 |
c3jvqn | Why are apple computers used so often with graphics intensive projects, such as photo editing and animation, but are never used for gaming? | Because of the history of apple computers and a series of very good advertising campaigns.
Historically, Apple computers were cutting edge as far as graphical applications, so they gained a good reputation for graphic design and that sort of stuff.
Recently, though, the designs of their consumer machines put style far beyond actual performance. Product listings are proud of the actually decent specs of the machines, but they ignore the fact that ventillation on the machines is severely underperforming. In order to manage the heat and noise, apple computers drop down the power of their components when put under any reasonably load for more than 10 seconds.
For photo-editing and animation uses, Apple is still used because of the reputation of the brand, and the specific colour characteristics of the display. For gamers, though, high performance under heavy load for long periods of time is the most important, and that is not something that the consumer Apple products can provide. | bfb03677-439c-4567-b990-e9973e755fb4 |
c3kecg | Why does the sweat from our armpits stink? | Sweat doesn’t smell but the bacteria that builds up in a warm damp place does which is why the armpit can still smell even when there’s no sweat. | b5a19940-1906-4df8-9c97-9d969570a962 |
c3kga7 | How does the whole dominant hand work? How does one side of our brain working more than the other allow us to have a dominant hand? | How come my left hand is, for all intents & purposes functionally retarded, yet it's the only hand I've ever used to wank comfortably? Right hand, which I do everything else in life with, feels awkward af when I try to get sexy with it... | 9b4aba1b-d4a1-42f2-bb1e-55f5b78a3c0c |
c3kgse | How can a game like Red Dead Redemption load quickly, while remastered old games like CTR needs loading screens that take a fair bit of time? | Optimization. Newer games use newer engines while remastered still uses the old engines.
ELI5 - think of liquids in pipes. New games are like water where older games are like a sludgey oil. | 511c27f6-e980-405d-bbc5-8d264737534c |
c3kk3h | What happens to the tiny bits of minerals, like sand, when they enter deep into your fingernails? | So under the bottom of your nails, near the cuticle, is a patch of skin called the nail bed. This is constantly making new skin, and new nail. The skin and the nail grow forwards together. When they separate at the end, the skin cells die off, and fall off as dead skin flakes.
If you get stuff stuck deep in under your nails, it will get carried out by this process. | f0eecac3-c10d-49b9-808f-47f84a7d7dea |
c3kmfk | How come we can hold on to our bladders WHILE ASLEEP better than when we were kids? | Also, it’s a muscle. The older you get the more use it gets, making it stronger. Well.. ya know, until you get too old. But that’s a different topic. | 02a0ebec-a424-4550-87de-aea515daeb25 |
c3l2fg | Volume past 50% on almost every car stereo, home stereo, TV, or computer speaker is uncomfortably loud but every cell phone's ear speaker needs to be above 50% just for me to understand the other person. 100% cell volume is only moderately loud. Why is this? | Very simple. Sound is waves. Bigger the speaker, bigger the waves louder the sound.
Phones have tiny speakers. TV’s and Cars have multiple ones and they are rather big compared to a phone | 2a741ef6-8473-4619-88f4-57dfa2696b4e |
c3l77j | How does our brain work when we choose a favorite color/number/etc? Why like something more than other? | With colors and numbers, you acquire a favorite due to positive associations with that color or number, i.e. my favorite color is dark blue because it's the color of a quilt my mother made for me when I was 6, or a certain numeral resonates because it was the number on my first football jersey. | 647ddacc-052d-4d74-9a59-185de519f8a0 |
c3lxtb | The human body is supossed to sleep for 8 hours. At the same time, sleeping 8 hours makes you really tired upon waking, why is this? | Eight hours isn’t actually ideal. Our sleep cycles are approximately 1 hour 30 minutes long, and waking up in the middle of them makes us tired. 7h30m or 9h is better since you will wake up at the end of a cycle. | f81b5211-7ca9-4703-a8f1-64285597047b |
c3m51v | How does the gps-coordinate system (XYZ-plane) accounts for the earth’s curvature? | GPS doesn't use XYZ coordinates, but ellipsoidal coordinates. Math is used to convert them to something easier for us to use on a map.
_URL_0_ | fbbac028-d738-4b95-8468-66cc75a2b944 |
c3mdht | How Physicists Define chaos/entropy/disorder (rpost EILI5) | If you talk about the mathematical definition of Entropy used in statistical thermodynamics, then you have the equation S=k*ln(Omega) where S is entropy, k is Boltzman's constant, and Omega is the number of microstates in the system described.
So, what does that mean? Essentially, the more random a system is, the more microstates the system will occupy, and hence the higher the entropy (or disorder if you want to use that language).
So there is a definition based on math, that allows Entropy to theoretically be calculated for every condition, relative to another state, so entropy really isn't based on arbitrary definitions.
The issue you are having is trying to use a layman's understanding of a fairly technical concept that is fairly unintuitive. In general people don't deal with entropy every day, so their intuition generally will fail them. Words like disorder and chaos are used to explain to laymen, when a better description might be statistical distribution. | e6f205bf-3f4e-49da-84fb-4d5a833ce65b |
c3mexx | Converting non-perfect square roots to decimal form | I’ll explain the example from the website with sqrt(10). First you get a rough estimate for the square root- it’s between 3 and 4, so we can take 3 as our lower bound. The square root will be bigger than 3.
Then you divide 10 by 3 to get an upper bound for the square root. Why does this work? Think of it like this: since 3 is less than the square root of 10, if I want to multiply 3*a, where a is some other number, and get 10, then a has to be larger than the square root of 10. When I find 10/3, I’m actually just finding a, and I know the square root has to be between 3 and a (now it’s a better bound than between 3 and 4).
Then I take the average of 3 and a. That gives me a number halfway between 3 and a, which should be a decent estimate for sqrt(10). It’s easy to check if it’s too big or too small. If it’s too big, then I get yet another (even better) upper bound and I can repeat exactly the same process. If it’s too small, I know the real value is somewhere between (3+a)/2 and a, so I can repeat the process with a new lower bound.
Zooming out to the general case, the strategy is the same: I find an interval and I know the square root of my number is in that interval. I can carefully reduce the size of my interval over and over, each time making sure that the square root stays in the interval I’m looking at. After enough iterations, I can eventually make this interval as small as I want, so i can find the square root to any level of precision I want. | 7761a204-363f-408e-bcd4-d8c35f5c0a01 |
c3mqeb | Species and Asexual Reproducation | As asexually reproducing organisms, bacteria are indeed incompatible with the biological species concept that defines species based on their ability or inability to interbreed. Historically, bacterial classification mostly relied on characteristics that were either visible under a microscope or otherwise measurable in a lab. For example, the famous [Gram stain](_URL_0_) technique can be used to distinguish some bacteria from others based on their cell wall structure.
More recently though, it's become increasingly common to identify bacterial species based on DNA similarity. As early as the 1990's, some researchers had already proposed some guidelines for this; bacterial with > 97% (later increased to 98.7%) DNA sequence similarity should be considered the same species, and > 95% sequence similarity has been used as the cutoff for the genus level ([source](_URL_1_)). However, I think it's worth noting that this approach is certainly not flawless either, and many species of bacteria that have been historically recognized do not follow these guidelines very well at all ([source](_URL_2_)). | 846cb190-7e12-4268-86b2-2e5280dae8c5 |
c3ms9a | How can I go to bed with an alarm set at 6:10am and wake up at exactly 6:08am. More than 2 times a week, roughly 5 minutes before the alarm goes off. How does my body achieve this? | I'd say it's all about you thinking that you need to wake up at 6:10am the night before you sleep. It's some sort of mechanism you've set in your mind in order for not to be late. | e0029946-9c36-4ee9-95d3-99b4f80fc6b7 |
c3mvyo | Why does rubbing your eyes feel so good? | By rubbing your eyes you stimulate a nerve called Vagus nerve, which relaxes you and makes you feel good. Also rubbing eyes would cause more tear secretion which lubricates your eyes so your eyes don't feel dry and tired.
But, rubbing eyes too much isn't a good habit, it can affect the shape of your cornea which can lead to a condition called keratoconus.
If you want to feel better, rub the palm of your hands together to create some heat, then place the palm on your eyelids. | dd909bf7-1845-45dd-8e43-088e5d0ce8c8 |
c3mw0o | Why lightning flashes for only a second but thunder can be heard for several seconds? | Thunder rumbles on for so long for a few reasons - one is that the lightning strike doesn't happen in one burst. Numerous strikes follow the same path over a fraction of a second. The strike is also several kilometres long, and sound takes 3 seconds to travel a kilometre, so you hear the thunder from the top seconds after you hear the thunder from the base. The sound bounces off hills and buildings, so the same sound is bounced back to you. Lastly, the sound travels through the ground as well as through the air, and the sound moves through the ground much, much faster.
None of these things matter with the lightning. The light travels so very fast - 300,000 kilometres per second - that it doesn't matter what path light takes, it will arrive to you practically immediately. | 543ea895-9f4b-49e0-92fc-fd013b445187 |
c3n9ku | You know when you're in a quiet room like a library, when your stomach makes noises or any noise from your body that you cannot really control, is it as loud as how you hear it from yourself? | It's probably not nearly as loud to other people, especially since they're not as tuned into it as you. Also, it happens to everyone, so even if it is loud, nobody thinks it's weird or anything. Definitely nothing to be embarrassed about. | 43419fb6-f802-4a10-aa06-1a619ca245d4 |
c3nemv | What is plasma, how is it created and how is it important to things like plasma tv’s etc? | Plasma is a gas that has been heated to the point that electrons are no longer bound to their atoms. This results in the properties of the gas changing. The most notable change is the gas emits photons. This is how we get HID lighting, and also the light in plasma TVs. | 8b2ac3b6-a8da-4f78-a5ef-809b90a79fb7 |
c3ngcj | What happens in court when it’s just one person’s word against another? | > Is it really just a case of telling the story and seeing who the jury believes?
More or less, yes. Each side presents their argument to the court and then the rest of the trial is bringing in evidence (documents, objects, witnesses, etc.) to support their core argument. Once that evidence is presented, the other side has the opportunity to cross-examine and attempt to discredit the evidence through a line of questioning. This goes back and forth until all the evidence is presented and both sides make their closing arguments and then the jury (or sometimes just the judge) decides the result.
The result hinges on who was able to make the most persuasive argument and/or weaken the other's to the point where it is without merit or cannot be believed beyond the shadow of a doubt. | 972e6ee1-9c66-431a-9eaa-78818c4f10d3 |
c3nuqs | How are a model of shoes/sneakers/... are priced the same even tho the sizes are different? | [This article presents a breakdown of the manufacturing cost of a shoe.](_URL_1_)
It states that from the $70 dollars you pay for a pair of sneakers, $35 dollars go to the end retailer, 20$ to the brand/designer, and $15 to the factory. So the manufacturing cost is only $15.
Further in the article there is a [breakdown of those manufacturing cost](_URL_0_). With labor, profit, packaging and molds taken out of the picture, only 64% of those $15 is actual materials cost: $9.60.
**Conclusion:** if you make a shoe 10% smaller, the cost of materials goes down 10%, but that's less than a dollar of the total shoe cost.
People are willing to pay that extra dollar anyway, so there is no reason for companies to reduce their price for smaller sizes. | 059cb033-a8ef-4c74-8899-f454eacdcc18 |
c3nvm3 | Why does hot water work better than cold water when you're washing dishes? | The heat melts the grease, oil, and fat that is used when cooking food. Also, heat makes things softer (usually) allowing the food to be slippery and come off of the dishes. Soap, in a nutshell, makes things super slippery and will trap food particles while the water and friction of a sponge or wash cloth rinses then away. | 3f0a87cf-265a-4327-af36-b42b2927833d |
c3o5we | How can a store like Kroger sell their own store brand MTN dew for .69 cents for a two liter when the name brand cost over 2x? | When you buy something from a "name brand" company like Pepsi or Coke, you're not only paying for the product but you're paying for all the overhead that comes along with producing it and getting it on the shelf- namely the marketing/branding. Store brands are a lot cheaper because it's the result of a super efficient process. Kroger manages the distribution and has little to no advertising cost. There are some items that you should always consider getting a generic brand instead of a name brand; for me medicine is one of them. Any generic brand medicine you see on the shelf next to a name brand is under the same FDA regulation, so it's just as effective and safe, but you're not paying for the marketing or millions of dollars the name brand spent on research. | e0e7ceff-e419-421c-a58f-8acd4ef80602 |
c3o7o8 | Why do eyes make that firework effect when you rub them for long enough? | From what I understand the cells that register light are quite sensitive to changes in blood pressure/flow due to their delicate nature. When you rub on your eyes you change the pressure of the whole eyeball, which in turn registers as light or colors due to all those small delicate cells. | 78d4d393-64ec-4b65-9be3-5a79c0775d5c |
c3ofhq | Why and how do clouds rain? Why do they turn black? | The atmosphere is full of water vapor, which is to say super tiny drops of water that basically float through the air. In certain conditions the droplets can start to combine and create larger drops of water.
Eventually these drops can start getting big enough that they start blocking some sun light, and that's when we can see them as clouds. And in the right conditions, these drops can keep combining and they're big and numerous enough that they block even more light (the clouds turn darker), and eventually they're too heavy to remain suspended in the air, and so they fall as rain drops. | ddc928f8-ce2d-4f86-b30b-7323eb8aae67 |
c3olba | What causes the pressure in our ears, when we inhale sharply, or try to get water out of our ears. | Your inner ear (the part on the "inner" side of the eardrum) is connected to your nose via your sinuses and eustachian tubes. Normally this serves to equalise the pressure between your inner and outer ear, but if you raise the pressure in your sinus (by holding your nose and blowing, for example) you can feel the pressure in your inner ear correspondingly rise as there is a lot of pressure-sensitive stuff in your ear.
Basically: there's a tube connecting your nose to your ear. | 5d648465-1828-464b-9503-a126149390a0 |
c3orac | Why is tipping in USA so common, yet in the UK for example, it isn’t? | Cause the UK pays service workers a living wage. They build it into the price of the entrees. The US wants the struggle to be real so they pay like $3.52 per hour to service workers and tipping is supposed to makeup for the shit hourly pay. | 892b19ec-1eb7-4947-b08f-0045fa9456bb |
c3otwo | Orientability in geometry/topology | A sphere is orientable because you cannot go from 'inside' to 'outside' a sphere without crossing the boundary of the sphere, it defines two entirely separate regions. With a Klein bottle, you can do so without crossing it's boundaries. | 5361f5af-376f-4c3a-a65b-f24bc474d720 |
c3p480 | What are squatters right and why do they exist? (Uk) | In short: If a person isn’t using a piece of land and someone tries to occupy it, there are ways that the new occupant can have rights to the land. The way it usually works is that if a certain number of years go by, and the owner doesn’t complain or attempt to evict the new occupant, that occupant can gain ownership of the land.
The primary reason for squatters rights is to reduce litigation. This was more relevant in Ye Olden Dayes than the modern world.
For example: Imagine you live on a piece of land owned by Sir Andrew. A few years later he dies and the land passes to his son, Sir Bob. Sir Bob loses the land in a game of cards to Duke Charles, who then sells it in parcels to Earl David. Earl David then trades it as part of a dowry to his son in law, Sir Francis. After all this nonsense, you are still occupying the land and have been building your farm for twenty years. You thought you still had an agreement with Sir Andrew. Now one day Sir Francis shows up and says he is the new landowner and he wants you gone.
So the court had two options: They can go through a process of investigation to try to identify the chain of ownership and then evict some helpless farmer. OR they can just tell Sir Francis to shut up.
Squatters rights are the latter. | 7b086d14-8a6d-4de4-ad71-e3f54d9f4a7c |
c3p7s6 | How do we have foods such as corn all year when they have such long growing times? | It's grown in different seasons in different parts of the country, and when it's too cold to be grown in the south, it's imported from warmer climates. | b45efcbb-1ff0-4628-b024-66868b336151 |
c3p7y6 | How are bridges that span long distances of water (e.g., Seven Mile Bridge in Key West, FL or Lake Pontchartrain Causeway in Louisiana) built? | Typically what will happen is a coffer dam gets set up. Basically its just some thick sheets of metal driven into the seabed.Once its set up you can pump the water out and have people start building the base. These will be the piles you see sticking up out of the water.
Now that thats out of the way you can bring in your crane barge and lay some girders. These are the steel beams you see running the length of a bridge. Now you can start building a work platform to build on top of, or just start laying some prefab concrete across the spans.depending on the type of bridge
After that it really is just like most other projects | e5135dbc-a4df-4aef-9ca6-70e9aaaf0f1c |
c3p8xl | The usage of Scripts vs Compilers | TL;DR: Compiler = Program - > other Program and Interpreter = Script - > Actions on the computer.
I'm assuming you mean the usage of Interpreters vs Compilers because a Script is a type of program and a Compiler is a program that does things with other programs.
That said let's get into the difference of Compilers and Interpreters (I'll come back to the Script part in a sec)
The main deifference between the two is what happens to the input program. A Compiler takes the input program and turns it into some kind of other program. So for example if you have a Program written in C or C++ you take a Compiler and turn that program into machinecode (also known as assembly). Same goes for i.e. Rust or Golang. But Compilers are also used in other places. Python for example gets also compiled into Bytecode first before it gets executed (if you ever happen to write a python module these are the .pyc files). And in the case of Typescript that get's compiled into Javascript.
And Interpreter takes an input program and executes that program. So i.e. the Java VM takes in compiled java bytecode and interprets that bytecode. Same goes for the Python Interpreter. And in a sense your CPU is also just an interpreter for assembly code.
The thing is an Interpreter (for most modern languages) also include a Compiler which compiles the script into bytecode which then gets executed.
Scripts are usually run by an Interpreter (though i haven't really seen a good definition for scripts yet). Again Typescript (or Javascript in general is an exception here)
There is also a 3rd type of Program which fits between Compiler and Interpreter which is called JIT Compiler. JIT stands for Just In Time and that thing is at first a normal interpreter but once a block of code is executed often enough the JIT Compiler will Compile that piece of code (That can be a loop or a function, any block of code really) and execute that piece of compiled code instead of the "script". Javascript is a goof example here since every Javascript engine used by browsers does exactly that. Also the best Lua interpreter is a JIT Compiler. | 3699504a-f73c-477d-adca-3c0a85d988ff |
c3pm5i | Why do Americans talk differently than Brits, even though they emerged from them only a few hundred years ago. | Bear in mind that there are 150 British accents. | 0ec1e9ee-9de4-4454-9bab-fc65683c2141 |
c3pr2h | Can someone explain to me why there is rising tensions between America and Iran? | Oh boy, this is a long one.
So, Iran and the United States have had a long sordid past. I can explain that if you want me to, but just suffice to say that the US govt and the present Iranian regime absolutely hate each other. The US has been trying to come up with reasons to be pissed off at Iran to justify an armed conflict. Obama was pretty much the exception for attempting to make a deal with them to stop developing nuclear weapons, but Trump cancelled that deal.
The specific incident happening now is that there have been a series of mysterious attacks on oil tankers in the Persian Gulf that no one has taken credit for. The United States government is trying to claim that the attacks were caused by the Iranians, but have not provided sufficient evidence, or really a motive for Iran to be behind these attacks. Most recently, a ship was attacked and a US drone was sent to respond, but came really close to Iranian air space and was fired at by Iranian surface to air missiles. | 3023fa47-2138-4a97-8b4d-62cc29ed59dd |
c3prfq | How do game show award money amounts work? Some game shows are only able to give away a few thousand dollars and others can give away millions. Who sponsors / funds shows and how are final award amounts decided? | gameshows basically buy an insurance against larger winnings. it is then the banks job to figure out the probability of such large wins, and offer a premium to the gameshow they have to pay regardless what is won.
for small amounts (a few thousand) the gameshows itself can probably handle, for larger ones you need insurances (but are great advertisements). In the middle range you would basically still need insurance, but the premiums (and financial overhead) would probably be too high. | 123c6f31-d1b5-490e-a351-87337d88e1b1 |
c3pu4z | Why can’t a sponge soak up mercury even when submerged in it? | A sponge can't absorb Mercury for basically two reasons:
One, sponges are made primarily of cellulose, which has a favorable interaction with water and liquids containing water. Mercury, on the other hand, is a metal, albeit a liquid metal (at room temp), and does not have a favorable interaction with cellulose.
Two, Mercury has a significantly higher surface tension relative to water, making it hard for the sponge to absorb it.
You'll need a metallic sponge to absorb Mercury. | 03833b64-ed51-4401-84bd-4171c63d49ca |
c3q11n | Why is the oven's self-clean cycle lethal to pet birds? Is it also dangerous to small furry pets and tiny humans? | Also virus, bacteria and most other forms of life. During the self-clean cycle, the oven is run at very high temperatures (could be as high as 500C) to burn off any oil, food residue into carbon and carbon dioxide which is how it "cleans" itself. | 433108a8-cad1-432c-9a61-9f16707c054c |
c3q3qu | Why do headphones get so impossibly tangled when left in your pocket? | Because there are many ways for them to be tangled, but only one way for them to be untangled. Its all just statistics. | bad67968-a116-4d57-8e9e-99a3884fb95b |
c3qdyg | What causes mutations in humans and animals when in radioactive sites? | When biological matter comes in contact with constant but not lethal amounts if radiation, the DNA and cells of whatever creature deterriorate. That is to say, the DNA is split apart. When it repars itself naturally (like regular healing) there is a chance the DNA mutates or gets out back together incorrectly. This could lead to the growth of extra limbs, or limbs at all. | a9dde31e-3a20-4c06-ae82-4251d4248704 |
c3qu9f | How to have safe sex IF you want to have a baby? | Well if you and your partner are going to have a baby I would assume both of you would know if you have any STI/STD. If you are unsure you both can get tested at a clinic. | b40c9676-45f6-4922-a00b-0e195520982c |
c3r3g2 | why do ordinarily unexciting things become super interesting when one is procrastinating work? | So I'm not a psychologist or anything, but procrastination was described to me as a battle of self-control/motivation versus the negative effects of actually performing the task. When the negativities (anxiety, stress, fear of failure, exhaustion, etc.) outweigh our self-control and motivation to get the task done; we start to seek out other meaningless things to do (such as scroll through Reddit) in order to distract ourselves from all the stress. Eventually, the pressure to perform the task increases to a breaking point (usually as the deadline approaches) and our self-control/motivation kicks back in allowing us to stop procrastinating and actually do what we're supposed to. | 249f0022-f53a-411a-b401-c0b6278e3c87 |
c3rnh1 | What are the actual risks of talking about Tienanmen square massacre in China? | You’ll get re-educated to be a more harmonious citizen in re-education camp if you have families that would make a fuss if you’re missing, if you don’t you’ll just disappear.
They actually talk about their version of the event in uni. The gist is: no protester die, many peace keeper die, there were no tanks. No info on how it started or why.
It’s a little bit better than talking about being gay in a Muslim country but not by much. | ad993f9c-2024-40f0-a7bc-422ecb03a906 |
c3rr1c | Why do men have nipples if we do not produce milk? | In mammals nipples form before gender is determined in fetal development. So both genders get nipples but only the females get fully formed breast which can feed an infant. | 18d0c541-cab3-48d6-8647-acd2bfea8a5d |
c3sjyj | Why does it sometimes take a few listens to start liking a song? | This is totally just a personal theory because it seems like a lot of how we experience music enjoyment is still being understood.
Music has lots of patterns in it and we enjoy songs when the patterns are familiar enough for us to follow while still being unexpected so we can't fully predict every pattern. Listening to a new song that is extremely different from your usual type will be unexpected without being familiar enough for it to be enjoyable.
Just like a story, if you can predict everything that happens, you get bored. But if you can't predict anything because it is random, that isn't good either. A good story has just enough predictable framework to support the twists it throws at you. If you haven't experienced enough of those stories to know the framework, the twists aren't satisfying because you were already confused.
Re-reading a hard story or listening to a new genre multiple times let's you start to see the framework and appreciate the unexpected parts more. Then it makes appreciation of similar new songs or stories easier since you already know what to look for. | a1ea29e0-5ccc-47cc-8d33-45345efc5e16 |
c3sm34 | How does sunscreen/sunblock work? | Sunblock is a layer of liquid you apply to your skin to protect your self from UV-Rays. Basically there is a type of radiation emitted by the sun called Ultraviolet, which is very damaging to humans and living organisms because it causes damage to our DNA. Sunblock and sunscreen puts a layer that is capable of absorbing the UV and therefore protects us. Here is a video of how sunblock looks in UV camera, notice how the layer added looks pure black, because it means ALL the UV is absorbed (or most of it) by the sunblock and protects your precious skin.
Video of application in UV camera: [_URL_0_](_URL_0_) | d4c5d700-a5f0-49cb-b59a-7541291fc628 |
c3ss34 | How did people get pigeons/ravens to go to specific (long distance) locations back in the day? | Just pigeons. Ravens is a Game if Thrones thing only. And all they were doing was returning home - you couldn't direct them where to go. If you want to send a message by pigeon to Rome, you need to have a pigeon that lives in Rome that you took with you. | d34a6775-d635-4f02-af54-c9d16421cf42 |
c3t01v | How do you differentiate east from west at the poles? | Exactly at the poles, there is no east or west. From the south pole, every direction is north. Close to the poles, east and west still exist; that latitude band is just a really small circle | b969676b-323b-4d10-8b83-da2ad163fd67 |
c3t7ax | What's to stop someone from buying an old Spanish gold coin, creating molds of the faces, striking their own fake Spanish gold coins, and selling them for a 10x profit by weight? | Most metallurgy trading would have to be graded and proofed. There are ways to date metal castings and alloy types.
For a more in depth explanation I'd have to probably write you a small paper but thats the jist of it. | 7d90740a-20af-4361-a2ea-01664295256a |
c3t99y | Why is it more common to have colorful eyes (like blue or green) in northern countries? | If you have dark brown eyes, it protects your eyes from the sun. It's like how dark brown skin protects your skin from the sun. But your body has to continually burn extra calories to make the brown pigment. Food is scarce so it's only worth burning the calories if the risk of damage from the sun is high. Since it's extremely sunny at the equator, it's better to have dark skin and eyes.
If you leave the equator and go to the North or South poles, it's less sunny. This means your body doesn't need to protect itself from the sun as much. Instead of making the brown pigment, it saves the energy for something else. This means that eyes can be blue or green because they don't need dark brown to protect them.
As a result people who live near the poles tend to have light skin and eyes. They tend to be a lot more sensitive to the sun (e.g., they burn easier and their eyes are sensitive to sunlight.) People who live near the equator have darker skin and darker eyes to protect themselves. They tend to burn slightly more calories to make the brown pigment.
This is more common in the northern hemisphere because the land in the northern hemisphere is really far north. Even Australia is still relatively close to the equator compared to Canada, Russia, Norway, etc. | 78edbcf2-e577-4b95-8664-fa8f798ffa19 |
c3te4m | How did humans decide which animals were pets and which would be food? | What values the animal gives is the determiner i would believe.
A cow won’t go hunting or keep your house safe. A dog would.
A hen wouldn’t (on the contrary) keep pest at bay but a cat would.
You’d keep the animals where the needs are and get the maximum return from them.
Yes cats and dogs also produce milk and meat but the return on investment is fairly poor compared to a cow. And they don’t lay eggs. | 8984d9b4-8b15-48f4-b49b-a0bc41b1a194 |
c3thtr | When a fake check is written and it bounces, how come the recipient is immediately penalized and not the sender? | You don't know who the sender is. It's as simple as that, they don't use there real name or bank account. | b3f19d7d-5356-42c8-a550-6bc98c82ba30 |
c3tidb | Why do some noises, like slurping or clicking sounds, bother us when they come from other people but not when we make them ourselves? | Depends on the situation and usually depends on etiquette standards. Depends on your culture too, for instance slurping is considered a sign of gratitude in some countries. | 4b95c7c4-ffdf-4a30-969d-bdc6e75203e3 |
c3txqj | How are nuclear fuel and control rods raised and lowered? | The are hydraulics actuator that move them.
You can for example see them [_URL_1_](_URL_1_) at the top of the reactor and moving [controllrods in reactors](_URL_0_). The one in the video is research reactor and not power plans. | e006883d-f20d-4ca0-98cc-491359cd851b |
c3u3zo | How do optical fibers made of glass bend in wire and, not just shatter instead? | If the glass fiber is 1/300 the thickness a sheet of glass, it can bend around a 300x tighter radius without breaking.
The material on the outside of the bend has to stretch in order to stay lined up with the material on the inside of the bend. If the material is thinner, the difference in radius is smaller, so the outside doesn't have to stretch as much.
Imperfections in the sheet can also drastically reduce the strength, acting as a starting point for crack formation. If you have a very small piece of glass, it's less likely that an imperfection is present exactly where the glass is in tension. | 43ac8af0-c194-463d-a24a-dc1703800878 |
c3u4jr | Why does Genghis khan only have male descendants? | They are tracking the y chromosome and its easier to confirm that the y chromosome was hous rather than having to dna test all woman and comparing their x chromosomes.
A man passes an x or y chromosome and his male descendants will also pass their x or y chromosome. | 5e9171d0-9d13-4c0a-8c36-3e0a1a6eec9a |
c3uoh1 | Why is Hunter S Thompson popular | His craziness wasn't an act. He was honest in his desire to get the most out of his words by any means necessary. Also, he was a turbulent man that lived in and documented a very turbulent time. He isn't the greatest writer but he has great content. | 6529c80c-2623-49d7-ab0b-41abad114f34 |
c3uoke | Why is beer foamy? | Beer has head (foam) retaining properties really not exhibited by any other beverage in the world. Malt and hops aid in head retention. And yes, we force carbonate or naturally carbonate to style specific volumes of dissolved CO2. Hope that helps! | a899635c-06f5-48f7-a869-40f2b740be95 |
c3uq2e | BPA in food containers | Picture a steel chain in your mind. Flexible, strong, super useful. A single link, however, doesn't really do all that much.
Plastics are literally chemical chains. Individual molecules aren't all that remarkable, but when connected in regular patterns they have incredible properties. Specifically, when BPA is mixed with phosgene, it forms polycarbonate- strong, clear, flexible plastic.
Now, if you ate pure polycarbonate, you'd be fine. Your body doesn't really recognize it and it would eventually be excreted with other waste.
But to make polycarbonate, you essentially take a bowl and mix BPA with phosgene. Unfortunately, no chemical process is 100% efficient. There's always a little leftover that doesn't end up reacting. So intermixed with the polycarbonate product are little bits of unreacted BPA, sticking to the plastic.
If that plastic is then used to make a water bottle, some of that BPA may then dissolve into the water. When food is heated in a microwave, the container gets warmed up too. This helps dislodge the BPA from the plastic and allows more of it to dissolve into your food/drink. I also think BPA is used in things like thermal paper receipts, and touching them can cause BPA to dissolve into you through your skin.
The problem is that while polycarbonate isn't that interesting to your body, BPA is.
Have you taken ibuprofen before? When your body feels pain, a enzyme binds to a molecule, let's call it molecule X, and converts it into a chemical signal for the pain response. Ibuprofen looks enough like X that the enzyme tries to turn it into a signal too, but fails. So while the enzyme is wasting its time with ibuprofen, molecule X just sits around and nothing happens- no pain signal is created.
BPA works the same way. Enzymes in your body called hormone receptors bind to hormones (a type of chemical signal) such as testosterone and estrogen. Obviously these enzymes are really important for development. Testosterone tells your body to do one thing, estrogen another.
If you drink water with BPA in it, your body may absorb the BPA. BPA happens to look a lot like estrogen, so it binds to those hormone receptors and your body thinks it's getting an estrogen signal, so starts to do things related to that signal.
Is it dangerous? It's hard to say. We can give people more and more BPA until we notice bad things happen, but that isn't really useful. Nobody is eating pounds of BPA, so if eating a pound of BPA is toxic, it isn't that helpful to know that.
The problem is, what happens when you absorb tiny amounts of BPA over the course of years? If a few cells accidentally think they're getting an estrogen signal once, it probably doesn't do anything. But if they keep getting that response over and over and over again, does it add up? Does it matter for everyone, or just young people who haven't fully developed yet?
The ideal experiment would be to have two identical babies, feed them exactly the same food and expose them to exactly the same stuff - all BPA free, but feed only one of them a little bit of BPA as well, and see if there are any differences.
Obviously, we don't have 80 years to wait around and see those results, and it would be deeply unethical to experiment on babies like that, even if the experiment were possible.
So instead we have to make models that try to approximate things. The most common one is zebrafish, whose nervous systems are similar to ours. We can grow a lot of them, control their environments, and dissect their brains to study them.
There are more problems, though. How much BPA do we give them to be representative of how much BPA humans get? How does the BPA affect them and would it be the same in humans? Does it matter if the BPA comes from food or drink? etc etc etc
So ultimately, the answer is that we don't know. The plastic lobby is really powerful and they make it very hard for scientists to get funding to study this. I personally know a few people who study BPA with these models, and their lives have been turned upside down by plastic companies smearing them and attacking them.
Should you be worried? Experiments in some models have shown pretty scary results if zebrafish embryos are exposed to BPA, but there haven't been enough experiments to know if that's really the fault of the BPA or if it's a design flaw in the experiment. Honestly, at this point it could truly be either, and trying to apply those results to humans would be pretty worthless.
If you are a young child, have a hormone disorder, or are pregnant, it'd be something to avoid to be on the safe side. Otherwise.... do what you can if it makes you feel better. I can't say if it'll hurt you or do nothing.
I personally avoid touching receipts because there is no reason to even get them most of the time, and I try to use BPA free plastic. However, if someone hands me a water bottle and I'm thirsty, I don't worry about it. In the grand scheme of things, it's more dangerous to be in the sun (skin cancer), or eat junk food (heart disease) than it is to get a little BPA exposure. | 1e122a53-d26e-4168-9eca-1797f3cfdc71 |
c3uuk6 | How come we can see stars millions or billions of light years away, but we are still unsure if there is another planet inside our own solar system? | Stars are really bright (at least some are really bright, some are dimmer) and create light, which can be detected pretty easily (photodiodes); a planet which is far away from light can’t be seen easily. We need to essentially make a giant telescope to capture the minimal amount of light it reflects, and then somehow prove it exists and isn’t some other planet or reflection, stars are easier. | 0f11cc44-7b68-4cc7-a1c8-3e5ec1ece4b6 |
c3uvin | how are dish sponges considered sanitary enough to use to clean something? | In the same way a loofah or bath scrubber is not efficient by itself for actually cleaning yourself, it's a tool used for applying a lather of soap and water, with a material conducive to physically removing food debris | a5d07481-6fa2-4218-8a9a-fa8cc7af7338 |
c3v1p5 | Why is it that a drink that has cold condensation on it is very slippery, but a warm drink that is just wet, isn’t? | Condensation is caused when the cold liquid in the glass cools down the surrounding air. This causes the air to lose its capacity to hold onto moisture and therefore the moisture precipitates out of the air and sticks to the side of the glass. It doesn’t happen with warm liquids because the warm liquid causes the air around it to warm up, as opposed to cooling down. | 764a9b7a-d964-4d0b-a7e2-40af7327bdaa |
c3vgg1 | How exactly computers work, and what exactly computer code is. I've been trying to wrap my head around how they work and what the applications on them actually do. Additionally, how do websites work? | A computer is fundamentally an arithmetic machine. At the heart of the primary component (the Central Processing Unit - CPU) is an Arithmetic Logic Unit - ALU. This can only do simple operations - addition, subtraction, shifting, moving, and comparison. Technically it can also multiply and divide, but these are fundamentally just repeated additions or subtractions.
You will have heard that computer data is stored in Binary, which is ones and zeroes. What this really means is that it is stored and transported in electronic circuits which are either on (one) or off (zero). So to do a calculation you feed your two numbers into the ALU on the data circuits, and on the control circuits you tell it what calculation to do, and out the other side comes your result, which you tell it where to put.
So at its basic level a computer does nothing that a human being can't do themselves; what's clever is how you decide to use that information; and what's powerful is the scale of just how quickly you can do it. Your mobile phone's CPU will be spitting out results to calculations like those over a billion times a second. It's so fast that in the time it takes your computer to perform a single calculation, light can only move around a meter, or less for very high end CPUs.
As to computer code, well it's all zeroes and ones too, eventually. At that very low level it's called machine code, and it literally shows the on/off state of each control line for the CPU, and sometimes the data lines too (but most of the time the data lines are fed from data storage registers). A slight higher level is called assembler code; this is a little more human readable, but still literally describes every step in complete detail such as:
ADD R1 R8 R24
Which might mean "Add the contents of register 1 to the contents of register 8 and put the result into register 24"
A level higher and we get to something much more readable:
a = b + c;
We no longer worry about exactly where a, b, or c are stored, we leave this up to something called a compiler. This takes our code and converts it into the assembly and then to machine code.
Now for the clever bit. In order to get them to do things like show pictures, connect to the internet, play games, it's all about how we choose to interpret that data. Here's something you can try yourself; make a copy of an image file, and then change the .jpg at the end to .txt instead. Windows will complain, but just agree. Now try to open that file - see how your notepad is full of lots of different characters? You've just told your computer to interpret data that was intended to be a picture as text instead. And this is what happens in all sorts of ways inside your computer; we say that a particular piece of data is for the screen, and we make a screen that interprets it in the right way; we say that another piece of data is the location of a tree on the map you're playing, and we make the game interpret it that way. But it's just a string of zeroes and ones at the end of the day.
Pull all of these clever things together, and you can connect to the internet and download a webpage. First your web browser asks a Domain Name Server (DNS) for the right numbers; the _URL_0_ that you type into the address bar is meaningless to the computer, and the DNS returns an Internet Protocol (IP) address for the server of the website you want to access.
The website server then sends a HyperText file back to you. This is what the HTTP stands for at the beginning of website addresses; Hyper Text Transfer Protocol - it's a way of sending and receiving the data that describes a website. So it tells your browser what colours to use, what lines to draw, what images to download and where to put them in order to display the page. Take a look, go to a website, right click and you should see an option for "view source" | b9d47f76-d8d7-4d98-8c19-45ed03b79db6 |
c3vr15 | . Gasoline pricing | It’s called [psychological pricing](_URL_0_). Basically, it’s an attempt to take advantage of the fact that we tend to perceive prices that end in .9 or .99 as being slightly lower than they actually are.
A gas station could end the price with a whole number, but a competitor could price at the.9 price and potentially steal a lot of business for effectively no cost. Therefore, everyone does it. | 4a771305-a900-4aa8-a7fa-9758c2afae59 |
c3vr8f | When we focus on a moving object we can smoothly move our eyes however if nothing is there we cant smoothly move them from left to right? | Horizontal saccades (eye movements) feel like they are smooth, but they aren't.
They are always somewhat jerky, but your brain corrects the visual input so that you interpret it as smooth movement.
When you have a moving object this allows the brain's "correction software" to do a more convincing job of making you think it was a smooth movement. | b109f829-46af-4364-9e8a-4a930d9f1bba |
c3w73s | Why do men get random boners when we are travelling in cars? (In Australia, we call them Travellers) | Aside from certain medical priapisms, erections are caused by blood withheld from exiting the penis more so than an increase of blood in.
The human body has a number of venous mechanisms for exiting blood from the lower body in particular, including the penis region. These evolved to counteract the force of gravity, but they may be thrown off by simultaneous seating position, and even more so by Australia's being upside down. | 1b7c85d3-670e-406a-8fde-11128f03d4d9 |
c3we1h | Why is the song “American Pie” titled that? | The song is about the death of Buddy Holly, Big Bopper and the others that died on that plane crash. It also references Bob Dylan, Elvis and other popular musicians of the time. American Pie, to my understanding, is referencing the phrase "as American as apple pie," and it acts as a farewell to those musicians and their style, making way for the rock and roll of the later 60s and 70s. | 9ee3789f-ba7b-465a-90c7-2d695264186f |
c3wlux | Why are some berries poisonous and others aren’t, even though berries are a primary method of seed dispersal? | The poison is a defense mechanism to prevent the "wrong" (as in those that would consume them without adequately dispersing the seeds) creatures/fungi from consuming the berries. Whichever berry you are looking it probably has some organism that is adapted to deal with the poison. | 999a60d3-7f76-4d4b-bf37-93a61dcbfafc |
c3wy55 | How do those “push and twist” drug bottles work? | They utilize a thread with an interruption on the bottle and a small bit of spring tension on the cap. Unless the cap is pushed down it cannot interact with these thread to come off. | 8708f86b-ae75-494b-b3b2-7e56186d04aa |
c3xi86 | How do those windows, wich you can turn non transparant with a switch, work ? | There's a film of liquid crystal inside the window, specially constructed and treated so that the crystals inside respond to electric current. When there's no current, the crystals go out of alignment, and their random orientation blocks light.
When you flip the switch on, a low-voltage electric current forces the crystals to align, letting light pass through.
[This website](_URL_0_) can tell you more. | d3da5f7e-ea4f-4f4a-9e51-009ca9cf1fb4 |
c3xmxd | How does a turtle’s shell grow while the turtle grows? What is it made of? | The shell is made up of panel-like things called scutes. With most types of turtles, these scutes shed periodically to allow bigger scutes to form. They are made out of keratin - same as human hair & nails.
Source: I’m a turtle fan. | 73c1a8ab-4b97-4be5-85cd-ff8b7d05ad97 |
c3xowg | Why do most people who live in the US use wood instead of cement in buildings? | Wood framing is much less expensive than concrete block in the US. The US has a lot of land devoted to farming trees for lumber, so pine boards are very inexpensive.
Strong hurricanes are fairly rare outside a small part of the US, and wood frame buildings can be built to withstand storm winds. | ca8a3355-0928-472a-b440-6528e2e3195c |
c3xqwp | How does salt in a salt flat create almost a large mirror? | Those are probably the ones where it has just rained and there is a little bit of surface water remaining that actually creates the mirroring effect. | dd3abd96-80a9-4954-8ad8-b94ef92c303f |
c3xs04 | how do bongs work? | Smoke follows air flow, by pulling air and smoke through the water into the standpipe you can control how much smoke is made and trap it in the pipe by putting your hand over the top and pulling the burnt part out of the device. This allows users to only smoke the desired amount and have it be cooler than if smoking out of a pipe or cigarette/joint. | b8df6887-b969-4536-a6aa-a70dd22ad23d |
c3xtt3 | Why is the picture in night vision goggles green? | When the light enters the goggles, it's converted to electricity, then boosted electrically, then the light hits a phosphor screen (like the screen part of old school CRT displays) and converted again to light. There's no way to preserve the color, so it's effectively a black and white image, but it's converted to Green because our eyes see better contrast that way. | 94c93b34-62a2-460d-bac0-3fc25ae440d7 |
c3xvql | Why is eyeball size (generally) related to body size in animals? | In most cases like this I would look at the evolutionary drivers. Hunter or prey, day or night etc. Eagles and hawks hunt during the day, owls mostly at night so there are different requirements and different size eyes and vision. Killer whales hunt near the surface, Sperm whales in the deep so they have bigger eyes and the same goes for the prey animals. Evolution usually doesn't extend beyond what is required so while it would be really cool to have a hawk's eyesight the reason we don't is because we don't need it to survive so there is nothing driving the evolutionary change. | f2f1430e-315a-463e-8eb7-cb9957faaac3 |
c3y4kh | Panpsychism | Panspychism is the belief that all (or most) things can think for themselves or, somewhat think for themselves. A religious aspect that could be taken on this is spiritism, which states that human interaction with objects makes them gain discreet spirits. However, removing the religious aspect means that objects such as tables have particles, right? The particles moving or vibrating is their own very simple consciousness. So, when it comes to humans, those very simple particles that are thinking for themselves combine their thinking to make one big, complex human consciousness. Hope I answered your question. You can find a link that helped simplify it a little here: [the link](_URL_0_) . | 56249256-9ddd-4717-a87a-d9904668113a |
c3ycwa | What is Software Defined Radio? (SDR) | I'll try to answer ELI5, but theres a lot of technicality to it, so it may be difficult.
So in order to view, record, or measure radio frequency (RF) signals, a number of different devices can be used depending on what you are trying to accomplish. If you are just listening to music, like on the radio in your car, you would need to extract the audio information from the RF signal. This is called demodulation, since the audio has been modulated onto an RF carrier signal. Special demodulation hardware exists in your car radio to do this. Another example is a spectrum analyzer, a device which sweeps through a range of frequencies and gathers information on signals present in that frequency range.
So the difference between these and a Software Defined Radio, is that the devices mentioned first off have Hardware specifically made to perform these tasks, and a SDR performs these tasks using software. The SDR basically gathers a ton of raw data from the radio environment, and then software is used to perform the advanced functions like other devices. So for example, if you used your SDR to record the entire radio environment for 10 seconds, you could come back later and demodulate the audio signal on it, see what it looks like on a spectrum analyzer and many other things that you would otherwise need multiple devices to accomplish.
Hopefully this clears it up for you, and I didnt get too far above the ELI5 mark. | e6900c47-d4e5-4e01-97e8-2976f216e551 |
c3ydc3 | How does donepezil work? | There really is no answer to this question as we don't even know how Alzheimer's really works. In fact, most drugs people take for any illness are likely known to help, but we don't know what they actually do.
The best guess is this. Your nervous system uses a group of chemicals as signals, one of these being a chemical called acetylcholine. Neurons exchange these chemicals to communicate with one another.
There is an enzyme in your brain called cholinesterase, which takes acetylcholine and chops it up, destroying it. Normally this is good because you want to get rid of old signalling molecules so they don't build up and cause problems.
One theory (although I don't think it's really supported much anymore) is that Alzheimer's is caused by the brain being unable to make acetylcholine. In that case, any that gets chewed up by cholinesterases cannot be replaced.
Donepezil binds to cholinesterases and turns them off, preventing them from breaking down acetylcholine, hypothetically delaying the onset of AD.
However, I don't believe there is very much evidence that it actually works, and new hypotheses, such as the amyloid hypothesis, are supplanting the acetylcholine hypothesis. If it does help, it maybe boosting brain function for a little while but ultimately cannot stop the progression of the disease. It'd be like pouring a cup of water on a house fire, sure it may put out a small flame but it won't stop the house from being gutted. | 97e07731-34fb-471a-b996-f3e09bd3a504 |
c3yhhb | Why do some plugs have prongs that are the same size, while some have one prong slightly larger than the other? | The ones that have differently sized prongs are like that because the holes on the socket are different. In some devices, it doesn't matter which prong goes into which hole, and so they have equally sized prongs. Other devices do care how they are plugged in, so they have a larger prong on one side to they can only be plugged in with one specific orientation. | 2b4dfdc9-b2c5-464d-b2c3-585df9f686ab |
c3yht6 | What's happening when someone wakes up from surgery/a coma/head injury and knows a different language? How would it be possible for someone to materialize knowledge of all that vocabulary, and sentence structure? | That doesn't actually happen.
Those stories are creations of TV shows or tabloid magazines. | 3aca4580-2714-4b5b-8391-c5887be5e213 |
c3yirb | Why do airplane emergency oxygen masks have bags if they are meant to not inflate? | They inflate temporarily, if you pause in breathing, so that the oxygen can flow out of the source continuously. When you next inhale, the bag deflates again.
It other words, it's a *buffer* in the oxygen flow. | cb843784-1d74-492b-8736-b495fda11eeb |
c3yjhh | Why is 60 FPS the base for smoothness for PC gaming? | Basically, you want your FPS to match the refresh rate of your monitor. Most monitors are 60hz, therefore 60 fps is the ideal for them to be in sync. However, if you get a 144hz monitor and runs a game at 60 fps it won't seem as smooth because they are not in sync. Monitors with a higher refresh rate are becoming more popular/affordable, however 60hz is still the most common for the price (although 75hz is gaining a lot of space too).
& #x200B;
So basically: The monitor will determine how much frames it can show per second and you want your fps to match or surpass that quantity thus creating the "smoothness" feel. | 66e82c1a-4814-4b7d-8e5a-19eda0f0f15c |
c3yq33 | how do show/ movie directors get shots and scenes of totally abandoned cities? | They're not in real cities. They're on a movie set, and the rest of the city is faked with CGI.
Check out [this demo reel](_URL_0_) of how prevalent CGI is in TV shows. | c347ea12-429c-42aa-8485-2358f502963c |
c3yt11 | How does something, like an internal parasite, survive without the need of oxygen? | Parasites usualy have slower metabolims and doesnt require as much oxygen to survive. Guts have low levels of oxygen from the air you swallow while breathing eating etc and thats enough for them. Some parasites on the other hand are anaerobic creatures which means they dont need oxygen to survive at all. | cc268549-71f5-4c9d-bda6-d8852f3fecdb |
c3z3js | Fatty acid metabolism, how and when does body burn fat? | The body is very smart; it knows which organs are most important. When times are tough and you don’t have much glucose available your body starts to pull triacyglycerides (body fat) to break down into Fatty acids, which can then be broken down into small molecules that enter later steps of energy bearing cycles that your body normally carries out using glucose.
The brain can basically only use glucose however (and ketone bodies kind of but that’s a whole other cycle and too complex). In times f stress the livers glycogen is converted to glucose, transported to the brain, and used in glycolysis (energy production) so that your brain has the power it needs for you to think how to get your next meal!
Your body has learned to err on the side of caution because it can be difficult to tell when the next meal is going to be. So, the body saves the precious liver glycogen for the brain!
If your body used all the glycogen in the liver instead of burning fat, all of it would be gone after maybe an hour or two and your brain wouldn’t have the energy or needed and you would starve to death.
So why should you eat 6 meals a day if you want to burn fat?! Well when you consistently get a meal every 2 hours or so, your body starts to “learn” that the next meal will be very soon and there is no need to store excess fat. Ie. metabolism speeds up because your body knows it will get fed very shortly. For an analogy, imagine you work a job where you get paid on a single, random day each month . You would probably be very hesitant to spend all of your money in a single day right? Because you never know if you won’t be getting paid for a 3+ week stretch. On the contrast, if your boss consistently paid you every single day, you wouldn’t have a huge problem spending your money because you know for sure you’ll be getting some money tomorrow. | 86b1e663-7148-46f0-8014-d62add5f7dae |
c3z70b | Why can two engines have the same horsepower, but one will produce more torque? | This one is pretty simple math:
Power = torque x RPM (speed)
If power is constant, an increase in torque = decrease in RPM.
So if we have 1 power, 1 torque, and 1 RPM (ignoring units for simplicity):
1 = 1x1
If you have another engine with 2 torque but 0.5 RPM:
2 x 0.5 = 1
Same power. | 162c3081-e871-4122-8984-08b108ad6305 |
c3zi4m | Why do modern cinemas still use projectors? | If they're using a blu-ray player, that entire wall would have to be a tv-type screen, making it the complete opposite of cost effective. | ecaad232-19dc-482c-8bff-c341f27ababb |
c3zlm9 | Why is it called first aid? | First aid is the first thing someone would do to provide 'aid' for an injury. In many cases, it's all you need, but for more serious injuries, proper application of bandages or taking efforts to stop bleeding until professional aid can be provided can mean the difference between life and death. | 6687c293-2882-402b-95fa-45abe9b8cbf9 |
c3zof9 | Why is the head of a university called a Vice-Chancellor? | Because the Chancellor is a fairly ceremonial position / a governance position. In the british model (which is where the name comes from), chancellor's usually basically the chairman of the university's governing council (senate), whereas the VC is the actual person in charge of university operations. It's analogous to the difference between Chair of the Board and CEO of a company, with the chancellor being chair of the board and the VC being the CEO. Some universities dont have the same kind of Senate like body, but retain the name VC for the effective managing director anyway. | c20bf53a-57a4-4b1a-b900-111e2dd6d1cc |
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