q_id
stringlengths
6
6
title
stringlengths
3
299
selftext
stringlengths
0
4.44k
category
stringclasses
12 values
subreddit
stringclasses
1 value
answers
dict
title_urls
sequencelengths
1
1
selftext_urls
sequencelengths
1
1
796xjh
How does the knee reflex that doctors test work?
Biology
explainlikeimfive
{ "a_id": [ "dozt8oo" ], "text": [ "There are specialized nerve cells in your nervous system outside of your brain that can control movement in your muscles. Specifically, the vast majority of them exist in your spinal cord. Although your nerves are fast ([up to 119m/s!]( URL_0 )), most of your nerve impulses don't go that fast, and sometimes you need to react faster than that. The system itself is a holdover from when our ancestors didn't have brains, but it's useful because it bypasses your brain entirely to control simple movement. Say, for instance, you reach down and touch a very hot stove. A normal nerve impulse will have to travel up your arm, through your spinal cord, and into your brain. There, the signal gets passed around so you recognize that, in fact, your hand hurts and you should probably move it, and then bounces around to the motor control section of your brain to create the impulse to move. That impulse has to travel *back* out of your brain, through your spinal cord, through your arm, and to the muscles to move your arm away. In that time, your hand is still pressed against the stove, still burning. Instead, that signal hits your spinal cord, which *immediately* sends back a signal to *MOVE YOUR HAND NOW!* and your hand flies off the stove long before your brain registers that you needed to move it. You might still get burned, but it'll be a lot less than if you had to make the decision. Another part of that system helps you stay balanced. Your spinal cord helps manage the muscles in your legs to keep you upright. When the doctor taps on your knee, he hits one of the tendons there and stretches it. That sends information to your spinal cord, that your knee is bending, and your spinal cord sends back a signal to fix that, so your leg muscles activate and you kick. The test helps determine the health of your nervous system. If everything is intact and working properly, you'll have a normal, healthy reflex. They can do similar tests with your arms by tapping on a smaller spot on your elbow. I am not a doctor, though, so I couldn't tell you what it would mean if you, say, weren't paralyzed but also didn't have a healthy reflex when they tapped your knee? Also fun, you can do the test yourself! Simply sit with your leg dangling and keep your muscles slack, and gently but firmly tap your knee slightly towards the bottom and inside." ], "score": [ 16 ], "text_urls": [ [ "https://hypertextbook.com/facts/2002/DavidParizh.shtml" ] ] }
[ "url" ]
[ "url" ]
797ezg
Why is standard compliance important with regards to HTML and CSS?
Technology
explainlikeimfive
{ "a_id": [ "doztrh2", "dozro6d", "dozrk4n" ], "text": [ "Internet Explorer 6 taught quite a few businesses why standards compliance is important. IE 6 was included with Windows XP and this just happened to occur as everybody decided webpages were a really good way to perform certain businesses processes. When these businesses went to develop these pages they only cared about then working in the new Windows with IE 6. It just so happened that IE 6 also had some non-standards compliant \"features\" and supported the now discontinued ActiveX. IE 7 comes out and suddenly those webpages don't work. Microsoft thought they had locked up web browsers but then Firefox came along and proved them wrong. Firefox was much faster and had more features so people started moving over to it. With Firefox quickly eating away at IE's market share Microsoft had no choice but to make their browser standards compliant (somewhat). Firefox was standards compliant and it's rising market share meant more pages were written without hacks to look right in IE 6. Without the IE 6 specific code, page elements would end up in the wrong place, making IE look broken (which it was). So why did everything break in IE 7 but worked fine in IE 6? Those special \"features\" in IE 6 I talked about were actually added on purpose to break support for other browsers. Microsoft assumed they would control the browser market and completely screwed themselves. If they left in support then web pages would look broken. If they took it out then businesses would not upgrade IE because it's cheaper to stay on IE 6 than redevelop their software. It was not until much later versions of IE that they detect what version of IE the page was written for. Microsoft did not learn their lesson. Each new version of IE had some very weird ideas of what standards compliant meant, breaking things that worked fine in the previous version of the browser. This lasted until the last version of IE when they eventually called it quits and started over with Edge. Meanwhile Firefox did not have these problems. Because they were standards compliant they did not have to worry about anything breaking in an upgrade. People could move to the newest version of Firefox knowing their favorite web pages would continue working exactly as before.", "Standards-compliance is important because it means that other people can adapt your work in ways you might never have expected. For example, instead of you writing a page that's compatible with a certain version of Internet Explorer and *may* work on other browsers, you can write a standards-complaint page that will be compatible with *every browser* (that is itself compliant with that standard), even ones that haven't been developed yet! You also impose a long-term cost on yourself by not being compliant. It's tempting to treat one browser specially to make a quick fix for a problem or implement a feature that browser normally doesn't support. But once you have special treatment for four or five different browsers, maintenance becomes a lot more difficult. And what works for one browser now may break something for another browser. You may even have to maintain different versions of a page for different browsers. If you're standards-compliant, writing the page is your job, and you don't have to worry about the browser developer's job.", "You want your website to look the same on all browsers. Using non-standard styles in your CSS or using HTML tags in \"creative\" ways may only work on one browser but not others. Sometimes non-standard code will even make your website completely unreadable on certain browsers." ], "score": [ 12, 4, 3 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
797hq2
Why does the CIA choose to reveal sensitive information about major investigations after many years of the case being closed?
Other
explainlikeimfive
{ "a_id": [ "dozrukk" ], "text": [ "The CIA are not the ones releasing this. There was legislation passed in the 90’s requiring the Kennedy files to be released this year" ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
797q3h
Why are superchargers measured in liters?
Other
explainlikeimfive
{ "a_id": [ "doztk83" ], "text": [ "Superchargers are rated by volume of displacement per revolution. It's just faster to say \"liters\" than it is to say \"liters per revolution.\"" ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
797vml
If beer is 90% water why isn't it considered a good source of hydration?
Chemistry
explainlikeimfive
{ "a_id": [ "dozvd8w" ], "text": [ "Alcohol has a diuretic effect on the body, meaning it causes your body to hold less water. Since beer is generally a low concentration of alcohol, it would be more hydrating than something like a shot of liquor, but there is still the possibility of becoming dehydrated bc you are urinating too much." ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
797xv5
Why is it that when you have 7 circles of identical diameter that you can take 6 and place them around one and they fit perfectly?
Mathematics
explainlikeimfive
{ "a_id": [ "dozvryd" ], "text": [ "When you put three identical circles together so they touch each other, The centers of the circles form an equilateral triangle. This is because the distance between each pair of centers is 2R, and regardless of the radius of the circle (R) 2R = 2R = 2R. Any triangle with three equal sides has 60˚ angles in each corner. One of those corners is the center of the circle that's in the center of your block of 7 circles. Since 360˚ ÷ 60˚ = 6.0, exactly 6 circles will fit around a circle with 0˚ left over (which would leave a gap)." ], "score": [ 74 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
797zly
why does vision degrade when you are tired?
Biology
explainlikeimfive
{ "a_id": [ "dozvxes", "dozx6rz" ], "text": [ "Your eyes become fatigued, as they are working muscles. So after a long day of using your eyes, they need that rest. Usually by the time you’re tired your eyes have been strained enough to feel that fatigue. It can also sometimes make you think that you are tired when your eyes just need resting too, especially if you use bright light objects such as a computer phone or television for an extensive amount of time.", "Eye tech here. May I also add that if you have been staring at a screen (computer, tv, phone) for any length of time you tend to blink less often. The less you blink, the more dry your eyes get. You need a complete tear film for clear vision. It's actually part of the refractive process. If you live in a dry climate, it's even more difficult." ], "score": [ 14, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
7981w2
Why are air dried towels more absorbent than machine dried towels?
Even accounting for fabric softener, I feel like air dried towels are more absorbent than machine dried. I could understand if machine dried towels were just more efficiently dried, but wouldn't they then dry out further while sitting in the linen closet? Regardless of the surroundings they were stored in, line dried seem to be more absorbent. Why is that? Edit: looks like the consensus is that machine dried towels should be more absorbent than air dried, so there is something wrong with my dryer. Also, white vinegar in the wash cycle to remove fabric softener residue. Thanks for all the info, reddit. I'm honestly amazed that so many people have such strong opinions about this. Edit: re fabric softener. When I said I accounted for it when I asked this question, I just meant that I normally add it to the rinse cycle in the wash, so the towels theoretically have them same amount on them regardless if I then line or machine dry the towels. Edit: Alright, Reddit. You win. I've now spent my Saturday washing my towels with vinegar. Instead of fabric softener, my house smells like pickles. I hope you're happy.
Other
explainlikeimfive
{ "a_id": [ "dp01dc0", "dozwdjt", "dozwkmj", "dp07hh0", "dp07py3", "dp0b2tr", "dp0n8s7" ], "text": [ "I know for bath towels specifically, the fabric softeners leave a waxy film on the fibres, making them less absorbent. I used to work for a cleaning contractor, and our microfibre cloths would become worthless if we forgot, and added a sheet of downy! They would also streak the hell out of mirrors and windows.", "It would be because machine drying will somewhat compress the fibers in the towel. A towel absorbs water by absorbing water into the microscopic spaces between fibers. Water is drawn and held there basically by capillary action. If the fibers are compressed by being machine dried, there is less space, and the towel will absorb less water.", "Water attracts water. Towels act through capillary action, so the faster the water can travel through the towel the better it will be at absorbing liquid. So when you go to wipe up a spill, a slightly damp cloth will be more effective because it's already primed to absorb the liquid. An air-dried towel will retain the same moisture as the surrounding air, more or less. A machine-dried towel will be much drier than an air-dried towel, so it will take longer to absorb the same amount of liquid. So it's not really about how absorbent they are, as the dryer towel will actually absorb slightly more liquid, it's that the damp towel will more readily absorb the liquid much quicker.", "Problem is that you can't \"account for fabric softener\" the way you think you can. What I find is that both softener and, particularly, dryer sheets, leave a residue on the inside of the dryer's drum that gets picked up by the load that follows it. You have to run two unsoftened loads in a row, typically, for the second load to start to approach full absorbency.", "I'm late to the party but here we go. Every time you machine dry a towel you are losing material..... Clean your lint filter and you will find some of that towel you just dried. Air dried towels don't get the shit beaten out of them in the drying process and thus their material loss is minimal. More material == more absorbance. Source: I'm tuning a 700 pound dryer right now.", "Towels are basically the same thing as a cloth diaper. I know from laundering cloth diapers that you cannot use fabric softener. The substance that fabric softener is made out of clogs and coats the pores on the cotton and other material. Also if you've ever tried to water a potted plant that is too dry, you'll know that water likes water and dry does not. Over-drying towels, especially to the point of static, which happens often in my dryer, makes it so that it's not as absorbent as if you had stopped sooner or line dried. Line dried towels would then tend to be a bit rougher but much more absorbent. There's also that lovely smell of fresh line dried laundry... ❤️", "Fabric softener do not make towels more absorbent. It leaves a thin coat of wax over the fabric." ], "score": [ 2658, 420, 106, 84, 11, 7, 4 ], "text_urls": [ [], [], [], [], [], [], [] ] }
[ "url" ]
[ "url" ]
7984e8
Why can't we see very small things?
Biology
explainlikeimfive
{ "a_id": [ "dozxsd3" ], "text": [ "It doesn't even get down to physical properties such as wavelengths. The simple fact is that your eyes have *limited resolution*. Any light that passes into your eye has to be captured by the light-sensitive parts of cells at the retina (the so-called \"rods\" and \"cones\"), and there are only so many cells in your eye. The visual size of an object varies with distance. So the closer an object is to your eye, the larger it appears to be, because the light coming from it hits more retinal cells. Past a certain distance, the light from the object is only spread across a single cell. Further away, the object fades from sight as its light blends into the light from its surroundings." ], "score": [ 7 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79875y
What is the Mueller Investigation and why is it important?
Other
explainlikeimfive
{ "a_id": [ "dozxua0" ], "text": [ "Mueller investigation is into any potential ties between Donald trump or his campaign and Russia. Its important because the absolute worst case scenario trump enlisted the help of Russia to put him in the oval office. This would mean he is compromised and could not be acting in the best interest of the American people, which would be ground for impeachment. They are also looking into the claims of obstruction of justice surrounding the firing of former FBI Director James Comey. This would also be illegal and be grounds for Impeachment. At this point we do not know how deep the investigation goes or the results of the investigation, but things have gotten quite serious. Indictments are already written and by the looks of it are being served on Monday. The Grand Jury would not have pursued charges if they did not think they had something, so it is likely something shady went down and people are going to jail over it. The question now is how high up does the potential corruption go. Only time will tell." ], "score": [ 8 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
798ozd
Why is the Pink Lake is Australia pink?
Chemistry
explainlikeimfive
{ "a_id": [ "dp01wr1" ], "text": [ "The lake is not now and has not been pink for about 10 years. When temperatures and salt levels are right for it, a certain type of algae will accumulate beta carotene (a bright pigment that also makes carrots orange). Then a pink microorganism will grow in the salt crust. So it was very colorful while those conditions were met." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
798prf
Why are screen resolutions like 1920x1080 rather than 2000x1000?
Technology
explainlikeimfive
{ "a_id": [ "dp03g4f" ], "text": [ "Originally, the standard was 4:3 since several experiments found that the human eye’s field of view (FoV) was of the same ratio (155° H x 120° V). Hence it was continued as the standard for film, camera and later for TV as well. Now, Hollywood industry had to be something different compared to the home television. As a result, Hollywood came up with widescreen movies with more picture content which created the wow factor and was successful in drawing back crowds to theaters. Since there was no standards body back then, several aspect ratios started cropping up across different film houses, some of the popular ones being Panavision ratio of 2.20:1 and a much wider format called CinemaScope of ratio 2.39:1. This way, Hollywood managed to get back its audience for movies, while casual viewing at home like soap operas & news continued with the 4:3 ratio. Going forward, to accommodate this wide array of aspect ratios under a singular standard, the geometric mean of the extreme ratios (1.33 & 2.39) was taken at approx 1.78, rounded to whole numbers as 16:9. This was done to efficiently cater to all the aspect ratios under the same screen by minimizing the presence black bars across the entire ratio spectrum. Following this 16:9 ratio, screens were manufactured. The resolution or detail (1280x720, 1920x1080) was just a measure of the horizontal and vertical pixel array size and correspondingly, picture clarity." ], "score": [ 25 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
798v9m
What would happen if one of my eyes are covered for a long time?
Biology
explainlikeimfive
{ "a_id": [ "dp03dep", "dp031p3" ], "text": [ "If you are a child and still in a developing stage for vision and perception, covering one of your eyes can cause amblyopia. Amblyopia -a disorder also called lazy eye- causes decreased vision in covered eye due to the interruption in the eye-brain pathway. If done with growing up, i think it is fine to strut around with pirate's eyepatch.", "What do you mean by \"a long time\"? Is it half an hour? Half a month? Five years? Twenty years? In like 15 minutes, your pupil would dilate(non-native English speaker, is this right? I am thinking expand), letting in more light. Therefore, if you plan on going somewhere dark, or you think it suddenly will become dark where you are, wear an eyepatch on eye. When entering the dark room, switch Wich eye you are covering. Instant night vision. If you are talking about covering an eye for more than a day, better find someone else than me." ], "score": [ 5, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79977x
why do newspapers clean windows/mirrors/etc better than anything else that is made for doing such things?
I've always used newspapers with windex, and it works amazing as far as leaving any glass surfaces crystal clear with zero streaks. But I've seriously never been able to figure out why. Is it the paper? Is it the ink they use? What gives, smart people of Reddit? Thanks in advance!
Other
explainlikeimfive
{ "a_id": [ "dp04yp0", "dp0mtpw", "dp07a17" ], "text": [ "Never heard of this before, googled, and now see it is a thing. Newsprint is very rough, meaning it is not smooth, but has tons of imperfections. Imperfections means debris can get trapped in it. Much like a shamwow or magic eraser, it is all about having a bunch of imperfections that can grab debris. News print is doing the same. And no, the ink has nothing to do with it. If anything, the ink makes it less than ideal to use to clean.", "Paper is made from Cellulose. Cellulose is hydrophilic; it attracts water molecules. with a rag you're absorbing the liquid, but it's only doing so to ap oint, when its become saturated and can't move any more liquid, causing the streaks. Cellulose on the other hand, actively pulls water molecules off a surface. And since its working at a cellular level, that means it can get into the microscopic pits and such that are all over glass surfaces (to small to see.)", "Not modern newspapers. The ink they used to use contained lampback, which is a great glass polisher. Modern inks are latex which smears horribly when you use it on glass. Windex is also a pretty big ripoff, chemically speaking." ], "score": [ 10, 4, 3 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
799b59
What are hooks in computer programming? What are they used for?
Technology
explainlikeimfive
{ "a_id": [ "dp05syx", "dp0low4" ], "text": [ "Hooks are a type of function that allows a base system to call extension code. They’re used to allow other programmers to change or extend the behavior of an existing program or system. Every Chrome (or other browser) extension is possible because of hooks in the browser. Video games with mod support are another example of hooks in action.", "It is a general and quite broad term for giving access to and the ability to react to data being sent between software components. For example, a browser might use a hook to make it easier for antivirus software to scan downloads. When it starts a download, it shouts \"Hey, anyone listening, I'm starting a download!\", and any program listening for that will be able to react and intervene. Some hooks are intentionally put there by the developers. Others are clever tricks with existing functionality never meant to be a hook." ], "score": [ 12, 8 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
799dfc
Why/how does a hot compress bring a pimple or boil or stye to a head quicker?
Looking for a more in depth explanation than "heat."
Biology
explainlikeimfive
{ "a_id": [ "dp05x3u", "dp19j8x" ], "text": [ "Heat increases vasodilation and therefore circulation to the applied tissue. This brings more innate immune cells i.e. monocytes, macrophages and neutrophils to this location for quicker degradation of the foreign material.", "In the case of a boil the other comment is right, immune reaction. A pimple is a clogged pore and the heat also opens up your pores." ], "score": [ 46, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
799in6
Why don’t the rest of our bones in our bodies besides teeth, which are bones and composed of calcium, turn yellow and decay even though we can’t clean them like we can our teeth?
Biology
explainlikeimfive
{ "a_id": [ "dp070ir" ], "text": [ "Teeth decay because they're covered in bacteria that live off your food & their waste erodes the teeth. You don't have those bacteria inside your body, eroding the rest of your bones." ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
799isj
what does it mean to have a cousin once or twice “removed”?
Biology
explainlikeimfive
{ "a_id": [ "dp06qcl", "dp06sxd", "dp06vgz" ], "text": [ "A cousin once removed would be your dad or moms cousin. URL_0 :", "The removed but references a separation of generation. For example, a first cousin once removed is either a parents cousin, or a first cousins child.", "Once removed means the cousin is either a parent or child of the numbered cousin. A B. C D. If A and B are first cousins, A and D would be first cousins once removed. C and D would be second cousins." ], "score": [ 3, 3, 3 ], "text_urls": [ [ "https://www.google.com/search?q=cousin+twice+removed&oq=cousin+twice+removed&aqs=chrome..69i57j0j5j0.6821j0j4&client=ms-android-hms-tmobile-us&sourceid=chrome-mobile&ie=UTF-8#imgrc=Azysob6DaJB4jM" ], [], [] ] }
[ "url" ]
[ "url" ]
799s4i
what happens to grass durning winter?
Biology
explainlikeimfive
{ "a_id": [ "dp0bk1e", "dp0s57m" ], "text": [ "It hibernates (lies dormant). Plants need sun and water to live, both of which are scarce during winter. So the plants go dormant to conserve energy until snow/ice begin to melt and the days get longer.", "Many grass-like plants have adapted their cycle to also cover the colder part of the year: autumn and winter. one of these plants for example is wheat. The mechanism is simpler than you think: they produce an antifreeze-like substance, which prevent water to go solid (freeze). Like in cars and houses, where one use antifreeze to prevent water to freeze, breaking the piping, grass prevents it from breaking its own cells. then it blocks its growth and waits for spring when it has a competitive advantage over other plants which still have to sprout." ], "score": [ 5, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
799s9j
why do prescription drugs have such strange names?
Other
explainlikeimfive
{ "a_id": [ "dp09cy0" ], "text": [ "Some prescription drugs incorporate part of the scientific name. For example, EuCRISA is CRISAborole. Others describe what they do: Synthroid is synthetic thyroid hormone. Still others just use medicine-sounding names because people assume drugs with fancy names must be effective." ], "score": [ 7 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
799wiy
how does cryptographic salt and pepper work?
Technology
explainlikeimfive
{ "a_id": [ "dp0a2rx" ], "text": [ "When encoding information: Salt is/are random string(s) of numbers used when storing information. If you want to save a password in a database, you can't use plaintext, so you encode it. The sequence the encoder used to base its encription can be called the salt. You can now store the encoded password with the salt. The only way to check if someone used the right password is to run what they entered through the encoder using the matching salt. If what the person entered matches what you stored, it's the right password. However, this method is risky, as anyone using exactly the same encoder can still check passwords if they have the matching salt. Pepper is related to salt. Using the same hypothetical encoder, pepper would be an action done consistently to every password before it goes through the encoding/salt steps (like adding \"s6hk4\" to the end). This adds an extra variable to be accounted for when checking passwords. With pepper, in theory, even if you have access to the same encoder, the correct stored(encrypted) password, and salt, you still would need to guess the pepper, which is stored in a different location. [phone spelling]" ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
799y6d
Why do sapling trees not lose their leaves in the winter while adult trees of the same species do?
Biology
explainlikeimfive
{ "a_id": [ "dp0fpz6", "dp0k6qi" ], "text": [ "Some like beeches hold onto dead leaves to collect snow at their base for added water when it melts. Saplings in general hold onto their leaves longer than the larger trees to get some last minute sugar from the sun without the shading of the larger trees.", "Sunk cost and reproductive preservation. It's evolutionary cheaper for as species to \"grow fast, fail hard\" until it gets lucky then stop taking risks and reproduce than to grow slowly or the grow fast and then continue with risky behavior. So a lot of little trees try to grow as fast as they can so they become big enough to shrug off most threats *before* one of the threats to a small tree takes them out. Once it's established it slows down and adopts less risky behavior so it can successfully reproduce more times. Further reading - \"the selfish gene\"." ], "score": [ 15, 10 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79a0yu
Why can't the brain and spine heal like other body parts?
Biology
explainlikeimfive
{ "a_id": [ "dp0ajbb", "dp0al9k", "dp0ix15" ], "text": [ "The brain can and does try to repair itself. Brains form scar tissue. Unfortunately, it's so complex that basic natural healing can't do much. The spine can and does try to repair itself. Spine bones often do repair nicely. Unfortunately, the nerves running throughout are so complex that basic natural healing can't do much.", "When parts of the body are injured, the healing is done by surronding cells that begin to replicate and 'replace' the damaged cells. It seems that the brain and spine (the central nervous system) seems to be especially bad doing this. There are some reasons for this: 1. Nerve cells or neurons are extremely specialized and cover long ranges. There is cliched example of a single neuron in your brain, moving through you spine connected to the end of your toe...so that you have sensation there. Imagine if this long neuron is severed at some point...it cannot rejoin and replacing it would require a a single cell to grow all the way from the brain to your toe. This is very hard as you can imagine. This is why most neurons are produced only when you are a fetus in the uterus...and in fact are one of the first cells to get laid down. It's like trying to lay in concealed wiring for electric supply in your house AFTER the walls have been painted...it is a terribly inefficient process. 2. Because it is so terribly inefficient , it makes little sense to have neurons replicate. So neurons have largely lost the ability to replicate and replace themselves. This means that damage to the central nervous system is usually permanent. There are details here that I have skipped for the sake of ELI5. There are ways to force neurons to reestablish connections. We learn them from animals with simple nervous systems that can regenerate. And there are ways of forcing other cells to develop into neurons.", "It's like putting in fiber optic wire to your house *years after* they built your house. It can be done by careful surgery and spending lots of money but it doesn't happen on it's own naturally. In the case of your nerves it's so difficult that your species during evolution lost the ability to do it because it was impractical - it lost that ability eons ago when we split from salamanders. It didn't provide a significant enough benefit to keep around much like it doesn't provide a significant enough profit for the cable company to put new wires to an old house. On the other hand when you build a new house they put all the fixings into the ground - gigabit fiber, cable, phone line, sewer, water, electricity. They are already digging a trench to your house from existing lines and it costs very little to add another wire to the ground at the same time as the others. Similarily when you are a fetus your body is laying down all the wires as it goes in virgin ground - it's much less complicated to do it that way." ], "score": [ 67, 12, 4 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79a31j
Why does lightning emerge from a cloud as a single bolt? Why not from the whole surface area of the bottom of a cloud?
Physics
explainlikeimfive
{ "a_id": [ "dp0c88o" ], "text": [ "So there is a static field that does emerge as a whole area. But the thing is air does not conduct electricity. So it results in just a static field. When the field is strong enough, the air undergoes what's known as [dielectric breakdown]( URL_0 ), basically, the air stops becoming an insulator, and starts becoming a conductor. What happens in a cloud is there is a large static field in cloud, and the strongest spot on the field is where the air becomes conductive, the charges then move down that conductive path, towards the ground. That makes the largest static field the area near the already conductive spot (it's also closest to the ground). The process repeats until it connects to the ground, and then the charges flow between the cloud and ground until they are equal." ], "score": [ 9 ], "text_urls": [ [ "https://en.wikipedia.org/wiki/Electrical_breakdown" ] ] }
[ "url" ]
[ "url" ]
79a46u
why does the water in a glass seem to rise above the edge?
Physics
explainlikeimfive
{ "a_id": [ "dp0b21b" ], "text": [ "The 'surface' above water (or any other liquid) is called a meniscus. Water sticks to things, and to itself. When you see water in a cup \"climb\" the edge slightly, that is due to the water 'sticking' to the edge, and bringing more water with it. In many liquids, their sticking together force (cohesion) is stronger than the stick to other things force (adhesion). These liquids do not climb the edges of containers at all. **Specifically answering you:** When water gets above the edge of the glass slightly, it's cohesion is still stronger than gravity. When you add too much water, gravity becomes strong than its cohesion, and down the outside of the glass it goes. [phone spelling]" ], "score": [ 9 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79a7g6
How is insomnia different from having a bad sleep schedule or just plain restlessness? How is insomnia diagnosed?
Biology
explainlikeimfive
{ "a_id": [ "dp0fj4d", "dp0j6yd" ], "text": [ "Insomnia literally means \"want of sleep.\" It's a general term for any sleep disturbance, not a specific diagnosis in itself. Insomnia can be caused by a bad sleep schedule. Not sure exactly what you mean by restlessness, but if you're talking about a night of bad sleep, that's pretty much the definition of insomnia. There are thousands of different things that can affect sleep. It's normal to have a couple of nights of weird sleep in a month, but if you often can't sleep well, talk to your doctor to get to the bottom of your situation.", "Insomnia is a catch-all generic term for not being able to sleep long enough at the normal time of day. There's a dozen or so different *types* of insomnia. Some unlucky souls (me) have a natural circadian rythem involving 20 hours of wake time and 12 hours of sleep. Others have great difficulty shutting their brains down *ever* until they are completely exhausted. Others are wired to naturally sleep during the daytime and stay awake at night. Sometimes insomnia is just a bad sleep schedule that a person is having difficulty fixing on their own. Or temporary because of a life event. It can be almost anything that causes a person to have trouble getting enough sleep when they are supposed to sleep." ], "score": [ 13, 8 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79a7wi
How can we discover planets that are so far away?
I always wondered how can we find those planets that are light years from Earth.
Physics
explainlikeimfive
{ "a_id": [ "dp0bpaw", "dp0rups" ], "text": [ "Usually exoplanets are discovered by looking for a characteristic wobble of stars in a telescope. Because gravity from planets will affect the spin of their star, stars with planets will appear to wobble back and forth compared to other, naked stars. Then, by calculating the expected size of the star and the size and frequency of the wobble, they can make an educated guess as to the size and distance of the exoplanet from their star, or even if there are multiple exoplanets.", "5 Ways to Find a Planet according to URL_1 : 1. WATCHING FOR WOBBLE; Radial Velocity; 654 planets discovered 2. SEARCHING FOR SHADOWS; Transit; 2758 planets discovered 3. TAKING PICTURES; Direct Imaging; 44 planets discovered 4. LIGHT IN A GRAVITY LENS; Gravitational Microlensing; 51 planets discovered 5. MINISCULE MOVEMENTS; Astrometry; 1 planet discovered You can watch simple gif's and animated videos of each method here: URL_0" ], "score": [ 18, 17 ], "text_urls": [ [], [ "https://exoplanets.nasa.gov/interactable/11/", "Nasa.gov" ] ] }
[ "url" ]
[ "url" ]
79a8qz
how does ATP and Respiration work?
I strugge with understanding glycolysis, the Krebs cycle and the electron transport chain. Could someone help me out uderstanding these difficuld processes?
Biology
explainlikeimfive
{ "a_id": [ "dp0htoo", "dp0jfu6" ], "text": [ "To be fairly honest these arn't 5 year old concepts. You would be better off in ask science but here goes glucose splits making pyruvate and some energy pyruvate goes through the Krebs cycle some energy, nadh, and fadh2 are produced by th Krebs cycle they are then used in the electron transport chain to pump protons over a membrane. Those protons push themselves through something like a turnstile when they come back across this spins and makes ATP when it spins. Edit added some stuff", "Two concepts are in the core of cellular respiration: 1. Chemical bonds contain energy, when you break that bond, energy is released. 2. Having a differential on electrochemical charges at both sides of the membrane creates energy, this is similar to the concept of potential energy when you lift an object with mass, it holds more energy the further away it's lifted. The whole chain of reactions (glycolysis, citrate/Krebs cycle, oxidative phosphorylation, etc.) does exactly that, chemical bonds are created and broken to release their stored chemical energy and in the process some compounds are formed that are able to (a) receive electrons or (b) donate electrons, helping with the electrochemical differential across the mitochondria membrane. I suppose you want to understand this process for school, in that case I recommend you check the videos #5 and 7 from the [Crash Course on Biology]( URL_0 ); and the videos 20 through 27 from [Khan Academy on Biology]( URL_0 )." ], "score": [ 3, 3 ], "text_urls": [ [], [ "https://www.youtube.com/watch?v=QnQe0xW_JY4&list=PL3EED4C1D684D3ADF" ] ] }
[ "url" ]
[ "url" ]
79aasz
Heavy elements were ejected from the sun when it went supernova at the end of its previous generation. When this ejecta coalesced to form Earth, how did elements of the same type gather together (in the form of ore veins) instead of getting evenly dispersed throughout the Earth?
Chemistry
explainlikeimfive
{ "a_id": [ "dp0ddyl" ], "text": [ "Heavy elements weren’t ejected from our sun, they were part of a star that came before the sun, and were part of the explosion that happened at the end of its life. When those elements coalesced through a combination of gravity and mutual attraction (static) in a new system, most of them fell to the center of the solar system (99%!) and formed the star itself. The little leftover amount formed a [protoplanetary disk]( URL_0 ). These elements went through the same process of gravitational attraction and static attraction to coalesce into smaller bodies that couldn’t under fusion. This process (in the absence of the dusty, protoplanetary disk) is still ongoing, to some extent, because comets and asteroids still hit each other and larger bodies, but for the most part the mass in the solar system is already aggregated. So now that you understand a bit how the planets were formed, we can talk about the heavier metals... Sometimes they are pushed out of the center core of the earth, where the overwhelming majority of Earths heavy metals ended up sinking to when the earth was mostly molten liquids. This happens via tectonic and volcanic action. Sometimes they come from space! An object high in heavier elements and metals hits earth and liquifies on landing, these metals are subsequently stuck on top of the lighter, floating metals because they cool off and solidify before they can sink. Think: a penny sitting on top of an ice cube. It’s also interesting to note the elemental composition of the inner and outer planets are different. The outer planets have much more lighter elements in them, proportionately speaking. edit: cleaned up some spelling errors, added a wiki link." ], "score": [ 10 ], "text_urls": [ [ "https://en.wikipedia.org/wiki/Protoplanetary_disk" ] ] }
[ "url" ]
[ "url" ]
79almm
How come when wiping off dirty surfaces, the dirt always seems to have a somewhat same grey-brown color?
Chemistry
explainlikeimfive
{ "a_id": [ "dp0hhh6" ], "text": [ "Grey-brown is the color of dirt :-) I know that's a little tautological, but really. Rocks, soil, bits of dead biological matter... all brownish/grayish/blackish stuff with some variation here and there." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79b6uw
How did hydrocarbon lakes (oil and gas) form on Titan if Earths formed from broken down biological material?
Titan is one of Saturn's moons. There are more hydrocarbons on Titan than there is on the earth. All of ours (or so I believe) formed from broken down biological material. How did Titan come to be with so much hydrocarbon material present without ever having life?
Chemistry
explainlikeimfive
{ "a_id": [ "dp0jpfy", "dp0jvur", "dp190td" ], "text": [ "Hydrocarbons, especially the simpler ones prevalent on Titan (methane, ethane), can be produced geologically as well. Titan also has a lot of nitrogen in its atmosphere (most of it is nitrogen), and the interaction between simple hydrocarbons, nitrogen, and sunlight/radiation gives rise to more complex hydrocarbons.", "Complex hydrocarbons on Earth formed by the breakdown of biological materials under intense heat and pressure. Titan's lakes of hydrocarbons are very simple hydrocarbons like Methane(CH4) and Ethane(C2H6). These are far more likely to form from Carbons and Hydrogens floating around together than complex hydrocarbons found on earth like Octane(C8H16)", "And let's be clear: there are no lakes of oil on earth (unless its seapage). Hydrocarboms on earth are trapped, on the molecular level, in porous rock." ], "score": [ 19, 5, 4 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79beyt
Ecosystems in Biomes
Hi Middle Schooler here I have this project where I choose and research a biome and choosen ecosystem within it. I am very confused what an ecosystem is, Can reddit help me please?. I also cannot chose a Biome so can anyone help with that aswell?
Biology
explainlikeimfive
{ "a_id": [ "dp0lq16" ], "text": [ "An ecosystem is a unit comprised of living (biotic) and non-living (abiotic) parts existing in a particular territory, in an ecosystem it's important to consider the flow or matter and energy, like the cycle of water or cycle of phophorous. A biome is considered in terms of its geographical position, its climate and the predominant vegetation, rather than the flow of energy and relationships between individuals and their environment. [This map]( URL_0 ) summarizes the land biomes. Usually, an ecosystem is smaller in size and complexity when compared to the biome. For example, inside the tropical rainforest biome you can find the ecosystem of tropical rainforest birds and its relationship with tropical rainforest plants, tropical rainforest insects and other." ], "score": [ 3 ], "text_urls": [ [ "https://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Vegetation.png/500px-Vegetation.png" ] ] }
[ "url" ]
[ "url" ]
79d4jy
Why does multiple Bluetooth connections cause music quality to degrade?
Anytime when listening to music, if there's more then just my stereo connected to my phone, the music will have a slight static to it. Disconnect all devices from my phone but the stereo, restart the stereo, and music is crystal clear again.
Technology
explainlikeimfive
{ "a_id": [ "dp1bnvr" ], "text": [ "Modern BlueTooth devices support at least two simultaneous connections. The internal circuitry of your BlueTooth device needs to manage both at the same time. Some devices are better at this than others. It has nothing to do with \"two different signals in the same space.\" The BlueTooth protocol is designed, like WiFi, to peaceably coexist with many other devices broadcasting on the same frequency. There's no \"fighting\" going on over the air, but there is contention inside your BlueTooth device as it tries to manage two streams. Some devices mitigate this by only allowing one media stream and one phone headset stream at the same time. I have multiple BlueTooth devices and I've observed my phone allocate one for \"media audio and phone calls\" and the other for just \"media audio.\"" ], "score": [ 5 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79d9z4
"Appropriate" margin
So on all these "business" shows like Shark Tank or The Profit they are always talking about margin and the appropriate amount of margin that a product should be making. Like "Clothes should be a 50% margin" or "food should be a 60% margin". Where do these people pull their numbers from? It makes sense to try and maximize margin, but why the standard for different product?
Other
explainlikeimfive
{ "a_id": [ "dp13g0z", "dp111ub", "dp1692f" ], "text": [ "Comparables (other businesses in the same sector), mostly. It's more an indication of what you *could* make than what you *will* make. Some businesses by their nature sell their goods for only slightly more than it costs them to offer them - like grocery, with average margins of 2-3%. Grocery stores make up for it by selling 200$ worth of goods to 500 people every day, and hordes of people won't shop at your store if your prices are 20% higher than everyone else's. Other business have higher margins, often because they offer something luxury or rare or unique. Clothing, for example, can demand 60$ margins because if someone sees a dress they *have to have* they can't easily find it elsewhere - even on the internet it's hard to search for a specific *shape and color* of a unique piece of clothing. Sometimes the margin is demanded by the nature of the business - a luxery food market like Whole Foods can charge yuppies a lot more for their food but it's also going to have to pay more for range-fed organic all natural unseasoned no-preservative blueberries, and it's going to end up throwing a lot more of it out because it goes bad. So they have to charge more, but they sell a lot less. So they pull the numbers from other businesses that sell roughly the same thing.", "It's calculated by overhead. In general food service/sales has a higher overhead than retail so you need a higher margin to make profit. Honestly 60% sounds low unless they are talking about packaged food or manufacturers. Restaurants run at a much higher margin. They are talking about general rule of thumb things though. If you can cut your overhead down you can lower your margin percentage and undercut competition.", "If you are selling coffee, you are having people come in all day, every day. If you are selling books, not so much, it isn't something people buy daily. Both stores are going to have about the same rent and employ about the same number of people, but the bookstore is going to have to make a lot more per purchase to cover those expenses. You also have competition. Amazon knows you are online and can easily look for a better deal. But if you have already schlepped to the bookstore, you probably aren't going to walk away empty handed just to save a buck." ], "score": [ 32, 5, 4 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79de1h
Why do we add tips AFTER the server already swiped the card instead of paying the total that first time?
Other
explainlikeimfive
{ "a_id": [ "dp1379d" ], "text": [ "When the server first swipes a card, it doesn't actually charge the card, just authorizes it for a charge. (I assume it contacts the bank to make sure there are available funds, but I don't really know that side of it). Then after you sign the receipt and leave, or later in the night when they have a free minute, they go back and enter the total amount paid, at which point it actually charges the total to your card. Very few places still use handwritten tickets, most use a computer system called Micros. Servers will make a ticket for each table/group, then they enter everything ordered into the computer, which sends the food tickets back to the kitchen/bar. Thus, the computer knows exactly what food was ordered from each table. It also knows the total amount paid, the difference is tips. Credit card tips go on your paycheck; some places you keep your own tips, other places pool tips and divide them equally. Most people just pocket cash, and only report a minimal amount of that to IRS. tl;dr: The swiping of the card just authorizes it for charge; actually charging it for money happens later in the day." ], "score": [ 44 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79dfin
Why do diseases like Schizophrenia and Bipolar Disorders typically manifest at Age 18-24?
Biology
explainlikeimfive
{ "a_id": [ "dp127z6" ], "text": [ "Many of them have a genetic basis which requires the activation of those genes by the hormones associated with puberty. Even \"normal\" people undergo profound physical, mental and emotional changes at this time, which is only amplified in individuals with these genetically-based psychological conditions. The environment in which these people are raised also plays a huge part. If you live a positive, safe space schizophrenia may not manifest at all/as severely when compared to someone living in a high stress area. There's a common axiom in biology that says \"genetics loads the gun, but the environment pulls the trigger\". It's this combination of biological/chemical/hormonal and environmental factors that cause diseases of all sorts to manifest." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79dg9s
why are some small pains (like headaches) often gone after a night's sleep?
Biology
explainlikeimfive
{ "a_id": [ "dp13ttz" ], "text": [ "It's the purpose of sleep to have your body and brain stop doing all the active tasks and focus solely on passive tasks such as homeostasis (which can help relieve headaches, digestive distress) and tissue repair (which can help relieve exertion based aches and pains)." ], "score": [ 9 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79e1mg
What makes carboxyl groups acidic?
Chemistry
explainlikeimfive
{ "a_id": [ "dp19456" ], "text": [ "Acidity is largely determined by the stability of the conjugate base. COO- is pretty stable because it has resonance, meaning it has different versions that electrons can move around to create. [Image of said resonance]( URL_0 )" ], "score": [ 8 ], "text_urls": [ [ "https://upload.wikimedia.org/wikipedia/commons/d/de/Carboxylate-resonance-2D.png" ] ] }
[ "url" ]
[ "url" ]
79e4gr
Trackless train. How does that work and compelling benefits of the same?
Technology
explainlikeimfive
{ "a_id": [ "dp1d3ca" ], "text": [ "What do you mean by \"trackless\"? You could mean: * Not needing tracks like an Australian road train vs a CN train. * Not having a dedicated guideway like an articulated bus vs a subway train. or maybe you mean something else?" ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79e8bm
Alternating Current. Do electrons keep going forwards and backwards in a wire when AC is flowing?
Physics
explainlikeimfive
{ "a_id": [ "dp19z0p", "dp1glt7", "dp1g1kb", "dp1ea3j", "dp1ctyf", "dp1gglm", "dp1a1hu", "dp1f34a", "dp1h3af", "dp1gr5y", "dp1j92w", "dp1j7th" ], "text": [ "Picture a tube of tennis balls, with both ends cut off. Direct current is when you take a ball and push it in one end, causing one at the other end to pop out. Alternating current is when you push a ball in one end and it pops one out the other, then push one in the other end and pop one out the former. Over time, for constant frequency AC, the total change in distance for any ball inside the tube is 0. Does that answer your question?", "As for the answer to the question - yes. I am going to use this question as an opportunity to clear up some misconceptions that people have. Almost no layman correctly understands electricity. People usually think, that electricity is some magic substance, say electrons, that is \"produced\" in the power plants, transported through the wires into your house where your appliances \"consume\" it. Similar to gas or water. **But that's exactly how it doesn't work.** The best analogy for understanding the AC system, is to imagine that instead of an electrical socket, a rotating axle is sticking out of your wall. Actually, in the early days of industrialization, that's how factories worked. They had a huge steam engine in the basement which was connected to the belt, gear and axle system. This system distributed the rotating movement around the building and all the machines on the factory floor were hooked to this single steam engine. So in a totally same way, your little axle in the electric socket is connected all the way to the power station that has a huge rotating engine inside. Whenever you want to power some appliance, you just hook it up to the axle and draw the rotating motion out of it. So the electrons are not the electric energy itself, they are the \"axles and belts\", that just carry the force (the rotating motion) produced at the power plant, right to your home. This analogy is very precise. It explains all the things about the AC system like: **Why does the production of an electric power always have to equal the consumption?** What happens when you reach the top of the hill in a car, and keep up the constant press on the accelerator pedal? You will start speeding up! Your engine suddenly produces more power than the car needed when going uphill, so it has to go somewhere. On the contrary, If you reach another, steeper hill, and don't press the pedal enough, you will eventually lose your speed and stop. Literally the same thing happens to the AC electrical system. All the power plants rotate at the same rate of 50-60 revolutions per second (depending on your country). If not enough consuming devices \"brake\" the common axle, it will really start to rotate faster and faster. If there is too much load, it will eventually bring all the system to a grinding halt. **What happens when I cut the wires that go from a power plant?** The plant engine will suddenly lose all the load and will start spooling up like crazy, just like your car when you lift the wheels up from the ground. The operators will have to enact some emergency procedure of reducing the power quickly, like for example, release the steam that drives the turbine. On the other side of the system, all the rotating engines in all the other power plants will start slowing down, because the load is higher than they can produce. If the network operator does not have a backup engines that are ready fill the missing power quickly, the easiest solution that saves the whole network, is just to sacrifice some part of it and \"cut off\" some of the load. **What power plant am I drawing power from?** In a sense, from all of them. All of them are hooked to the same \"axle\" and all consumers are drawing the rotating motion from it. You cannot point to a single power plant that powers you right now.", "If I remember correctly, the electrons move very little in AC. They mostly just vibrate in place. What actually carries the power is the changing electric field. So yes, electrons do move, but their movement is not as important as the movement of the field.", "Yes, the electrons do move back and forth, buy I want to point out that, in an electrical circuit, the electromagnetic field is what carries the vast majority of the energy. The electrons move like 0.1 cm/s, but in the field, the signal propogates at a speed close to c. Edit: electrons speed is actually much much less than 0.1cm/s !! My bad.", "Yea basically. Have you seen models for how sound waves propagate, with air molecules moving back and forth around their individual equilibrium points? Exactly the same idea, just with electrons moving in a conductor instead of the motion of molecules in a gas.", "Saying that electrons move only backward and forward in AC current is not entirely accurate, because they can move backward in DC current too. The electron motion is random inside the conductor because conductors are not empty pipes for electrons to flow through, they have metal atoms in between into which electrons keep crashing. In DC current the electrons move randomly due to these crashes but their net motion averaged over time is in one direction. A water equivalent would be water flowing through a pipe which is filled with sponge. If you keep the pipe vertical there is no straight path for the water to go down, but eventually it will reach down due to gravity. And if you provide a source of water on top and a sink at the bottom you will get a DC current of water. With AC, imagine the pipe is horizontal and someone is pushing in water and sucking it out alternately from one end, so water would flow in and out from one end. This effect would propagate to the next section of the pipe with some delay, and so on you set up an AC current. PS. Imagining that the pipe rotates like a see-saw for AC current is wrong IMO because even the voltage propagates like a wave on an AC wire, which directly related to the field.", "To the best of my knowledge, yes. AC is almost like a push pull system - at a frequency of 60 hertz (here in NA, varies globally.) DC is more of a flow system. On mobile, so bear with me on the formatting please.", "I think a better metaphor is using water canals to transmit energy. It is possible, and with electricity, it's not electrons we are trying to transmit anyway, it's energy. If you pump water in at one end, water flows down the canal and at the end you collect the energy with a water wheel, that is like DC. If, instead of flowing water, you make waves at one end which travel down the canal and are absorbed by a machine at the other end to generate energy, that is like AC. Technically current is flowing back and forth, but in practice you can make more sense of how it works by thinking of it as a wave.", "The way i picturised is like this: DC is like cutting a log with Band saw where the log is the load. AC is cutting the log with Handsaw (assume cutting tooth are bidirectional)", "We think yes kind of. Whether all if the given elections along a length of conductor move, or if it's more like just some, or if it's more just like opposing pressure (think of a tube with a rubber separator in the middle and how it would move/stretch if you alternated pressures on either end of the tube), I'm not sure we know for sure. But AC is used to do precicely that (alternate direction back and forth) and it makes for simple motor construction and efficient electricity distribution. Is really really hard to use a simple analogy to describe AC as we have no other simple energy source to use as an example. Flowing water (the favorite) is great for DC but falls short when explaining AC. The idea is that AC is a push pull motion, like the waves or when two lumberjacks use the same saw to cut a tree. We want that back and forward motion because our motors are built to use it.", "Sort of an additional question. How does this work with things like resistors? I get in DC, your limiting the amount of electricity flowing through, the excess is turned into heat, but in AC if the electrons are moving back and forth over the same physical space, how is the actual amount of (current? not an electricity guy :P) getting reduced? Are there electrons being pushed and pulled in and out of the resistor constantly?", "Also, my own personal eli5, what happens when you take diodes to turn ac into DC? Not a diode bridge, but just say a single diode in a rudimentary rectifier that creates a half wave that's only active half the time. Does everything just stop for that reverse portion? Surely the electrons on the anode side of the diode don't keep moving backwards, as that would create a vacuum of sorts with too many electron holes? But then, a single diode isn't going to stop it I wouldn't guess, and if it doesn't, and they do indeed move backwards, how does electricity get moving again, as wouldn't that forward motion just be refilling the electron holes that were emptied in the backwards motion? Oy." ], "score": [ 2698, 450, 51, 37, 34, 17, 16, 13, 6, 5, 3, 3 ], "text_urls": [ [], [], [], [], [], [], [], [], [], [], [], [] ] }
[ "url" ]
[ "url" ]
79en8x
Please explain all the facts I should know surrounding the Uranium One deal, without any partisan editorializing. Specifically, what did it accomplish/change, why did we transfer ownership to Russia, what are the costs/benefits of the deal, and what role did Hillary Clinton play.
Other
explainlikeimfive
{ "a_id": [ "dp1djl0" ], "text": [ "* In 2010 Uranium One sold 51% (controlling stake) to JSC Atomredmetzoloto, the mining arm of Rosatom, the Russian nuclear energy agency. * The deal would give Russia control of 20% of raw uranium resources in US. * The deal required multiple approvals by the U.S., beginning with the Committee on Foreign Investments in the United States (CFIUS). * CFIUS has nine members, including the secretaries of the treasury, state, defense, homeland security, commerce and energy; the attorney general; and representatives from two White House offices (the United States Trade Representative and the Office of Science and Technology Policy). * CFIUS and others gave their approval and the transaction was complete. * Despite Clinton being on the committee, CFIUS matters were mostly handled by her then assistant, Jose Fernandez. * It isn't clear Clinton had any involvement in the decision making process but even if she did it would be completly inaccurate to suggest she \"Gave away 20% of US uranium\" since the process involves so many other heads of state, ending, potentially, with the president. * #nothingburger < -- sorry but this is a fact and so I'm including it. sauce: URL_0" ], "score": [ 29 ], "text_urls": [ [ "http://www.factcheck.org/2017/10/facts-uranium-one/" ] ] }
[ "url" ]
[ "url" ]
79env0
why should you always close the commode seat after your done?
Biology
explainlikeimfive
{ "a_id": [ "dp1dp3y" ], "text": [ "It's just courtesy, there's no reason why the seat needs to be up/down/whatever. As for the cover, you can put it down when you flush to reduce the amount of toilet water particles that spray out of the toilet. These particles are generally smaller than you can feel or see and don't really cause health issues so long as you clean your bathroom every now and again." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79eodc
How do bluetooth headphones work?
Technology
explainlikeimfive
{ "a_id": [ "dp1eah0" ], "text": [ "They work like regular headphones except instead of getting the audio data over a wire they get it through short range radio transmissions. Headphones are basically tiny speakers you put in your ears. Speakers are diaphragms which move air in order to make vibrations, which are sounds. Basically all speakers these days are operated with electricity which makes an electromagnet tug or push on a magnet attached to the diaphragm. The instructions on how to move the diaphragm are either sent over a wire or in the case of wireless headphones through radio transmissions." ], "score": [ 9 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79f1jp
do MRI’s have any effect on our brain function?
Biology
explainlikeimfive
{ "a_id": [ "dp1gk05" ], "text": [ "There's no lasting effects but short term exposure to really strong magnets can cause areas of the brain to act weird and even shut down. Neuroscientists use this to their advantage by using a method called Transcranial magnetic stimulation, or TMS for short. A neuroscientist could want to test a function of an area of the brain to test a hypothesis so instead of finding a test subject and removing that part of their brain (unethical apparently) TMS can shut off that part of the brain for a short time." ], "score": [ 7 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79f56b
How does food that advertises "No Preservatives" have a super-long shelf life?
I recently bought a jar of alfredo sauce from Wal-Mart that advertised "NO Preservatives", but also "Made with Fresh Cream". On the lid, the expiration date is 02-28-2019... Almost a year and a half away?!? And without requiring refrigeration? I know that there's probably salt in it, which is a natural preservative, but how is such a long, unrefrigerated shelf life possible, and with dairy in it? Please ELI5 :(
Chemistry
explainlikeimfive
{ "a_id": [ "dp1h71d", "dp1t0wc" ], "text": [ "It's been canned. Even without artificial preservatives, they can seal it in an airtight container after superheating it to kill all the microorganisms that would lead to it rotting. This makes it shelf stable for quite some time.", "Canned/jarred products are heat pasteurized after being sealed, which kills off any bacteria inside that could cause spoilage." ], "score": [ 11, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79ff68
Can I start a company named Tesla Mattresses? Will I be hunted down by Tesla Motors?
Other
explainlikeimfive
{ "a_id": [ "dp1jbih" ], "text": [ "You're not talking about copyright, you're talking about trademark. Trademarks are only registered to specific industries. A well known example is Apple Corps vs. Apple Computer - Apple Corps (the record company) wanted to sue Apple Computer (the computer company), but Apple Computer didn't infringe on Apple Corps trademark because they operate in separate areas (music vs. computers). [TESLA does have a trademark]( URL_0 ) but it only applies to vehicles (and everything around them such as electric batteries) and certain merchandise like mugs and clothes. This means that a mattress company called Tesla will not infringe on this trademark." ], "score": [ 6 ], "text_urls": [ [ "https://trademarks.justia.com/779/83/tesla-77983373.html" ] ] }
[ "url" ]
[ "url" ]
79fprr
Why don’t your eyes get damaged when you look at the sun in your peripheral vision?
Biology
explainlikeimfive
{ "a_id": [ "dp1malt" ], "text": [ "Your eyes are made of rods and cones. The cones detect the wavelength of light (color) but aren't as good at detecting dim light, while the rods detect the brightness of light, but not the wavelength. There's a high concentration of rods and few cones toward the center of the eye, which is why you can see ahead of you in great detail. But further out, there are fewer, and eventually no, cones, while the number of rods increase. This is why you don't actually see much detail in your peripheral vision, but can see stars at night much better by not looking directly at them. Cones are really damaged by high levels of light because when they activate, they release a chemical that causes them to satiate, or reduce the intensity of what you're seeing to conserve energy by not sending such strong signals to your visual cortex. When there's too much light, they over produce, and it can permanently leave them unable to detect light due to damage caused by the high levels of the chemical. Rods just detect brightness, and don't need to satiate as much. They can still be damaged, but since there's so few photireceptors on the edge, it's hard to notice that you've lost vision there." ], "score": [ 18 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79fqfz
Should 0.49 recurring (lim - > infinity) be rounded up, or down?
Mathematics
explainlikeimfive
{ "a_id": [ "dp1l2b4", "dp1nmjh" ], "text": [ "This number is exactly equal to 0.5 (it is literally just another way to write 0.5), so you would treat it the same.", "The other comments are completely right in pointing out that 0.4999… = 0.5 (just like 0.999… = 1), so even though it might look a bit counterintuitive, you should round the two the same way – they're quite literally the same number. The most common convention is to round 0.5 to 1, you would also round 0.4999… to 1. However, your question highlights something interesting about functions and limits, and I'll expand a bit on this just because it seems natural. The sequence (0.49, 0.499, 0.4999‚ …) can be written as (0.5 - 10^(-n-1)) where n=1, 2, 3, … If you denote rounding by [·], so that [0.4] = 0, [3.6] = 4, and so on, then you have [0.5 - 10^(-n-1)] = 0 for all n, so lim [0.5 - 10^(-n-1)] = lim 0 = 0. On the other hand, lim (0.5 - 10^(-n-1)) = 0.5 - lim 10^(-n-1) = 0.5 - 0 = 0.5, so [lim (0.5 - 10^(-n-1))] = [0.5] = 1. In other words, [lim (0.5 - 10^(-n-1))] ≠ lim [0.5 - 10^(-n-1)]. If you've done some calculus, maybe this looks a bit unusual, because in most situations you encounter, you can move limits inside functions: lim_*x→a*_ f(x) = f(lim_*x→a*_ x) = f(a) However, you're only allowed to do this with continuous functions (intuitively, functions whose graphs can be drawn without lifting the pen), and f(x) = [x] is not continuous: [Here's a graphical illustration of this.]( URL_0 ) The function graph jumps at every half-integer value, and so the function is not continuous." ], "score": [ 24, 11 ], "text_urls": [ [], [ "https://i.imgur.com/1t8XJCI.png" ] ] }
[ "url" ]
[ "url" ]
79frrv
How does a fruit become juicy after it has been picked?
A lot of fruit (peaches, persimmons and even tomatoes) are picked raw when they are going to be transported far. When they get ripe, they turn from hard to soft and juicy. Where does the water come from? Is there same amount of water in raw and ripe fruit or does it somehow absorb water from air?
Biology
explainlikeimfive
{ "a_id": [ "dp24avr" ], "text": [ "Some fruits can keep on maturating after they have been picked. They are called \"climacteric\" fruits. This is due to a reaction of those fruits to a phytohormon (a chemical that has an effect on plants) called Ethylene. When fruits like avocados or bananas are picked, they start releasing some ethylene, which activates the maturation process of the fruit. This process modifies a lot of the fruits' properties, such as colour, texture, glucidic values, fat values... and those reactions modify the way inside water is displayed into the fruit. This hormon has a higher density than the ambiant air, so if you put your fruits in a basket without holes, the basket will be full of ethylene in less than a week, and your fruits will maturate VERY fast. A good way to prevent fruits from maturating is to keep them cold and ventilate the area. At the opposite, if you keep the fruits in your living room in a basket with other climacteric fruits (such as bananas and avocados...!), they will maturate faster! Generally, citrus and berries are non-climacteric, while apples, peaches, bananas, apricots, tomatoes, kiwis...are climacteric." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79g24m
How does electricity work?
My uncle's 9 year old asked him what electricity is. My uncle is a metallurgical engineer so its not as if he doesn't know what it is. But try explaining what electricity is without mentioning the flow of electrons and if so, explain to someone what doesn't even know what a atom looks like, what electrons is
Physics
explainlikeimfive
{ "a_id": [ "dp1np22" ], "text": [ "A nine year old can understand a simple model of atoms and with that the concept of electricity becomes much easier to explain. As a cable is solid you cannot actually explain electricity entirely without that model, as the next question would be \"If that is somehow inside the cable, why does it not flow out like water from a tube?\" which is a good question that you cannot explain without an atom as model. Just go for a simple model of matter (atoms, electrons), and then say that electrons do carry energy that you can use to make a lightbulb shine with light. If you keep children stupid because you think they cannot understand simple models, then they will stay stupid." ], "score": [ 15 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79g446
the difference between an i3 and an i7 processor (physical)
Technology
explainlikeimfive
{ "a_id": [ "dp1nfax", "dp1qyf6", "dp1t48i" ], "text": [ "Yer not alone in askin', and kind strangers have explained: 1. [ELI5:What is the difference between core i3, i5, i7? ]( URL_2 ) 1. [What's the difference between i3, i5, i7, and i9 CPUs? ]( URL_4 ) 1. [ELI5: What's the difference between the Intel I3, I5, and I7 processors? ]( URL_3 ) 1. [ELI5: What are the main differences between Intel's i3, i5 and i7 processors? ]( URL_0 ) 1. [ELI5: What is the difference between and i5 and an i7 CPU? ]( URL_1 ) 1. [ELI5: i7 chip vs. i5 chip]( URL_5 )", "A [die image will probably help]( URL_0 ) CPUs are made up of many similar and repeated blocks. The biggest difference between an i7 and an i3 from a spec point of view is the move from 4 cores to 2 and a reduction of cache. These are still hyperthreaded cores and still give the same performance as the cores in an i7 so they are likely the absolute same core. In the image above you can see the die of a 7th generation i7 processor. Its got an IO control up top, 4 cores down the sides, L3 cache running down the middle, IO interface on the right side, and the GPU in the bottom. An i3 will look nearly identical except two of the cores will be gone and the cache will be smaller. Consider the image with just one CPU core on each side, a half sized cache, and everything squished in to this new area All of the supporting systems like the IO control, IO interface, and graphics will remain unchanged except in models with different GPUs but they just drop it into the same block.", "If you were to open one up, you'd probably be surprised that there isn't much of a difference, if any at all. So what gives? Is Intel nerfing some CPUs so they can charge more for them? Not exactly. Chipmakers practice a technique called \"binning\". You see, we've gotten pretty good at making tiny CPUs. We're just not good at making every one of them perfect, which is a tall order when you're dealing with parts smaller than a virus. So as each CPU die comes off the line, it's tested and sorted into bins depending on its performance. The Core i7 are basically perfect off the line, with no major flaws. Some may take higher clock speeds than others, but that's really all that differentiates them. Core i3 chips are basically i7s with a couple bad processing cores. Since these cores don't behave correctly, or just don't work at all, they're disabled. Since a smaller percentage of chips that meet i7 grade come off the line than i3, they command a higher price. Regarding the i5, they're basically i7s with a few minor flaws that prevent certain features like Hyperthreading from working. Pentium and Celeron chips are i5s with a couple bad cores. AMD does the same thing with their CPUs, but they don't have an equivalent i5 bin for slightly flawed chips, so they just disable them. Which means in some rare cases it's possible to re-enable those slightly flawed cores through some computer voodoo. It's what PC hobbyists have coined as the \"silicon lottery\". Cheaper chips that can perform or clock higher than expected." ], "score": [ 3, 3, 3 ], "text_urls": [ [ "https://www.reddit.com/r/explainlikeimfive/comments/1uq3jb/eli5_what_are_the_main_differences_between_intels/", "https://www.reddit.com/r/explainlikeimfive/comments/370ws2/eli5_what_is_the_difference_between_and_i5_and_an/", "https://www.reddit.com/r/explainlikeimfive/comments/1j2p7g/eli5what_is_the_difference_between_core_i3_i5_i7/", "https://www.reddit.com/r/explainlikeimfive/comments/2yek6t/eli5_whats_the_difference_between_the_intel_i3_i5/", "https://www.reddit.com/r/NoStupidQuestions/comments/71jjxb/whats_the_difference_between_i3_i5_i7_and_i9_cpus/", "https://www.reddit.com/r/explainlikeimfive/comments/6dinri/eli5_i7_chip_vs_i5_chip/" ], [ "https://simplecore.intel.com/newsroom/wp-content/uploads/sites/11/2016/12/7th-Gen-Intel-Core-desktop-processor-die-map.png" ], [] ] }
[ "url" ]
[ "url" ]
79g8us
How Does The Ground Not Collapse When Animals Dig Tunnels Through it?
Other
explainlikeimfive
{ "a_id": [ "dp1o8g3" ], "text": [ "The ground above is compacted and the tunnels animals dig are relatively small." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79gsi6
Electra Complex and Oedipus Complex
Biology
explainlikeimfive
{ "a_id": [ "dp1w8ds" ], "text": [ "The Oedipus complex is a theory, posited by Freud, that argues that as boys become conscious of their bodies (and their sex organs), they enter into a subconscious competition with their father for their mother's attention and affection. Essentially they see themselves as competing with another male for the female, much in the way animals do. It's supposed to end soon into adolescence but the theory goes that if it isn't successfully resolved, it can develop into personality traits like vanity and braggadocio to compensate for the perceived emasculation. An Electra complex was proposed by Jung and is the manifestation of a similar process in girls in which the girl sees herself in competition with her mother for her father's attentions and affections. They're not universally accepted theories. They're named after characters from Greek mythology: Oedipus who, without realizing it, killed his father and had several children with his mother. Electra conspired to kill her mother after her mother killed her father." ], "score": [ 10 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79gsyk
Why does your hand naturally curl up when resting?
Biology
explainlikeimfive
{ "a_id": [ "dp1sgw5" ], "text": [ "Because that's the natural resting position of the tendons (and the muscles which pull on them) on the underside of your arm. Straightening your hand actually tenses the muscles on the top of your arm. You can feel it!" ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79guz8
What makes olive oil so healthy and sunflower oil unhealthy?
Other
explainlikeimfive
{ "a_id": [ "dp1xa51", "dp1wxi0" ], "text": [ "sunflower oil contains a lot of linoleic acid, a so called omega-6 fatty acid. our current nutrition generally lacks omega-3 fatty acids while containing plenty of omega-6 fatty acids. the balance of omega-3 to omeg-6 is considered important for health, so sunflower is often called unhealthy. olive oil contains substances that supposedly have health benefits, like antioxidants.", "Sunflower oil isn't unhealthy at all. It's high in calories, but no more so than olive oil. They have different uses. Olive oil is considered more healthy because it can be used to replace animal fat in savory dishes, whereas sunflower is used in frying, which is considered an unhealthy cooking method. The reality is that sunflower oil contains essential fatty acids just like olive oil does, and is actually less saturated." ], "score": [ 15, 11 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79gyjo
How does the process for making Kobe beef make the product so special?
I was lucky enough to try Kobe beef in Japan and it was the most incredible experience of my life. My question is Why does raising cattle a certain way cause the meat to be so much more flavorful and fatty than normal beef? I've heard it's because the cows are more relaxed, but what exactly does that mean?
Biology
explainlikeimfive
{ "a_id": [ "dp1u1wz", "dp1tvoc" ], "text": [ "Just like veal, the cattle are kept fairly sedentary, so their muscles never really develop. They are fed a fairly high fat diet, and the strain of cattle have a lot of intramuscular fat, aka well marbled. If you looked at a picture of Kobe beef URL_1 And compare it to prime in the US URL_0 They are similar in fat levels, Kobe tends to have a bit more. But you probably rarely eat prime. You mostly eat select or choice, which is mostly why you thought Kobe was amazing. Atmosphere and expectations also added to why you felt it was amazing. Kobe is marketed as the best, so that biases your experience.", "As I understand it the breed itself has a lot to do with it. But as with all meats, the less the muscle is used, the more tender it will be. And the less activity, paired with the right diet makes the fat just right." ], "score": [ 9, 8 ], "text_urls": [ [ "https://images-na.ssl-images-amazon.com/images/I/41Lo0R4swyL.jpg", "https://images-na.ssl-images-amazon.com/images/I/51neteBGabL._SX355_.jpg" ], [] ] }
[ "url" ]
[ "url" ]
79h31b
Why do limbs swell when they are injured?
Biology
explainlikeimfive
{ "a_id": [ "dp2172a" ], "text": [ "\"The body always responds to an injury with a predictable inflammatory response, as the first step towards healing. Redness, heat, swelling and pain are associated with this first stage. Redness and heat are caused by increased blood flow. Swelling is the result of the increased movement of fluid and white blood cells into the area of inflammation. The release of chemicals and the compression of nerves in the area of injury cause pain. The pain and swelling can keep the athlete from using the injured part, serving to protect it from further injury. However, often times, the body's response is excessive.\" Not sure how to post the link from which I took this information so here it is: URL_0" ], "score": [ 5 ], "text_urls": [ [ "http://www.nationwidechildrens.org/swelling-bodys-reaction-to-injury" ] ] }
[ "url" ]
[ "url" ]
79h4b6
Why does the temperature on weather sites sometimes seem incorrect?
Sometimes i will feel very hot or cold, look at the temperature on my local city's weather site, and go "no way, that cant be right". E.G. Now the weather site says its 21.7 degrees celsius, this is pretty normal and yesterday was about the same temperature. Except that now it feels REALLY hot and humid. I look at the dew point and humidty level. Humidity 56% and dew point of 12.5 degrees celsius. Doesnt seem special. I walk outside of the apartment and the air still feels like its 30+ degrees celsius. There is no nearby fire or anything that would drive my apartment's temperature up, nor have I just run a marathon or anything. There have been other times when I have looked at the weather site and it says something like "28 degrees celsius" but its feels really cold. Weather site in question is URL_0 by the way. Can anyone explain this?
Other
explainlikeimfive
{ "a_id": [ "dp1vy48", "dp246d0" ], "text": [ "What you \"feel\" depends on who you are, your health, metabolism and gender. So feel is not a good indicator of temperature. Website might not have regular updates, so the temp reading might be several hours old, or from a fixed location that has a different microclimate from where you are. And being indoors vs outdoors can impact local temperature and humidity.", "Microclimes are a real thing. A 50 foot section isn't the same as another 50 foot section next to it - I've seen this in gardening where some plants can be grown in some spots and not others (same dirt/sun). Example - the presence of trees at just the right distance in or from your backyard can prevent breezes from stirring up the air, which will stay there and heat up a few degrees. 30 feet in another direction and the air is more mobile which will mix it with the rest of the atmosphere and cool or heat it to the ambient temperature. And it seems like you are trying to read your subjective experience as valid data. Don't do that. Your feeling of 'hot' or 'cold' can be influenced by what you ate that morning, any medications or drugs in your body (even days after), and if you got any exercise recently." ], "score": [ 6, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79h83s
What makes something like Frangelico a liqueur but vanilla extract not a liqueur?
Chemistry
explainlikeimfive
{ "a_id": [ "dp21mnm", "dp2a5id" ], "text": [ "One of the main reasons in America was the Prohibition era. When the USA went tee-total, many food manufacturers complained because their ethanol-containing products would be banned, sending them out of business. By the time the Volstead Act went into effect the following year, it included a clause that made an exemption for flavor extracts. Basically, they couldn't reasonably be drunk to cause intoxication. Things like vanilla extract were later regarded as food products which meant they were given less strict guidelines and paid less tax for the alcohol used in their product. TL:DR - Frangelico is regarded as a drink and vanilla extract is regarded as a food item, so can't be classed as a liqueur.", "A liqueur is designed to be consumed as a drink. A glass of vanilla extract would taste horrific as a drink." ], "score": [ 5, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79hbec
Why you can stay up and ride out your drunkeness, but of you sleep you get a hangover
Biology
explainlikeimfive
{ "a_id": [ "dp1z2qd", "dp25tx7" ], "text": [ "Presumably, while you are awake, you are continuing to drink water and eat food. A large portion of hangovers is dehydration, so you're reducing that portion of it.", "When you stay up, the hangover hits gradually. You feel a wee bit worse every few minutes, but it's not like there was a point when the buzz ended and the hangover started. They just gradually faded into each other, and eventually it's 9am and you aren't feeling so good, so time to go to crash out. When you go to sleep, you presumably still had your buzz on. So your memory jumps from happy buzz, feeling no pain as you fall asleep or pass out, to waking up to uhhh.... shit. Yeah, you're deep in hangover territory now. Your consciousness just jumped from happy buzz to miserable hangover." ], "score": [ 25, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79hbrw
Recent experment says the Universe shouldn't exist?
I read 2 articles today explaining that a new experiment at CERN states that the universe shouldnt exist? It has something to do with matter and anti-matter and how if there were equal amounts at the big bang there should be no universe. I assume theres more to it because its just an article but I was wondering if anyone could elaborate. (Both articles I read if anyone is curious) URL_0 URL_1
Physics
explainlikeimfive
{ "a_id": [ "dp1wt0b", "dp23oit", "dp1woaq", "dp2cs3o" ], "text": [ "Antimatter is a polar opposite of matter. Everything is reversed. Regular protons are positive electrical charge. Anti-protons are negative charge. Anti electrons are positive charge. Anti neutrons are same electrical charge but ha e opposite magnetic momentum's. When a matter particle and antimatter particle collide, the annihilation reaction consumes both particles and emits energy equiv to the mass energy of both those two particles. So the question is...as we observe the universe, we see trillions and quadrillion tons of matter....but almost no antimatter. We create antimatter in laboratory settings. If equal amounts of matter and antimatter were present during the formation of the universe, it would just annihilate each other and be nothing...so what in our universe prefers matter to antimatter.", "The claim that the universe shouldn't exist is either a grave misunderstanding of natural sciences, or an abreviation. I strongly suspect that what the scientist meant with that is that the universe shouldn't exist according to our current model of it, and was just shortened to \"the universe shouldn't exist\". For scientists, it's clear what is meant, but others might easily misunderstand it. So, he's saying that there's either something that they aren't accounting for, or that their current model is incorrect. That's nothing bad at all, natural science is all about finding models that describe our world, then finding flaws in it, then finding better models that \"fix\" those flaws, and repeat. A similar situation was when Einstein discovered relativity - the accepted model back then required some medium, so-called aether, for light to travel through. However, they were utterly unable to find any signs of such an aether. Einstein then thought of a new model that didn't require such an aether - that's scientific progress.", "Well, clearly those experiments are wrong. Or not *wrong,* exactly, but they're focused on such a specific theoretical area of physics that they can come up with postulates (\"the universe shouldn't exist\") that seem ridiculous in ordinary conversation. You can breathe easy, though. I think the universe exists.", "Hi, Antimatter physicist here. tl;dr, Experimenters looked for a small difference between a specific parameter of matter and antimatter, and found no difference. The universe still exists, so there must be a small difference somewhere else, and life goes on. Full text: The Universe does exist, we just don't understand why there is an uneven amount of matter to antimatter in the observable universe. The issue the scientist is referring to - the Baryon Asymmetry problem - is because when pure energy is converted into mass (such as in the first few seconds after the big bang) an equal amount of matter and antimatter should be produced, according to experiments we've carried out here on earth. If Baryon Symmetry was conserved, the universe would have produced exactly equal amounts of matter and antimatter, which would have annihilated causing the universe to die in a brilliant flash of light. However, looking at the ratio of energy in the form of the cosmic microwave background and observable mass in the universe, we can estimate that roughly 6 baryons for every 10 million baryon-antibaryon pairs produced survived. We have some ideas of how this might happen, and might occur in the standard model under the \"sakharov conditions\" - one of which requires simultaneous charge and parity (CP) symmetry violations. CP symmetry has been shown experimentally to be violated by Kaons and B mesons, but not to the degree that explains the asymmetric nature of the observable universe. Something about matter must have violated CP symmetry in the early universe that caused it to be slightly more favourable to be formed over their corrisponding antiparticle. We can probe CP and it's bigger, more rigorous brother CPT (charge, parity and time) symmetry by searching for minute differences between matter and their antimatter counterparts. This is the challenge several of the research groups (gbar, alpha, alpha-g, atlas etc) at the antiproton decelerator section of CERN have undertaken. By searching for minute differences in the properties of matter and antimatter in a very precise manner, we can eliminate the propeties that couldn't possibly drive the CP violations (to the degree of accuracy we have observed) and look elsewhere. In the first link, they looked for any difference in a particular property (magnetic moment of the antiparticle) and found it to be equal to the corresponding particle. In this case they move onto some other property, or they change their apparatus to measure the property to a higher degree of accuracy. Because there could be a wide contribution to Baryon Asymmetry from lots of small CP violations, studying these antiparticles to high accuracy is ideal." ], "score": [ 27, 11, 10, 8 ], "text_urls": [ [], [], [], [] ] }
[ "url" ]
[ "url" ]
79hm0x
C3, C4, and CAM pathways. What is the difference between them, and in what type of plant are they used?
Biology
explainlikeimfive
{ "a_id": [ "dp214mf" ], "text": [ "C3 converts CO2 into a 3-carbon acid. Most plants use this mechanism, but it works best in wetter areas with moderate temperatures. As temperatures go up, growth is stunted because it becomes less efficient. C4 converts carbon into a 4-carbon acid, and this works in warmer weather with less water. Tropical plants tend to be this. CAM is something else entirely, where the plant takes in carbon dioxide at night and stores it for the daytime use. Then it seals off when the sun comes up to avoid losing water and photosynthesizes using the stored carbon during the day. Orchids, bromeliads, cacti, cactus form spurges, succulents, and other things without much water will use CAM." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79hxvl
Why do burns blister and why do burn wounds remain warm long after the injury occurred?
Edit: Thanks, this is the first time I ever got more than 100 upvotes on anything. Ever.
Biology
explainlikeimfive
{ "a_id": [ "dp23mbv", "dp28bzx", "dp2oq4z", "dp2brot", "dp2ddx0", "dp2wau6", "dp2niex" ], "text": [ "Burn blisters occur when the second layer of the skin is damaged, they occur to protect the underlying skin layers from more damage and infection. You could see it as the bodys/skins natural bandage, so never pop them. The skin remain warm because of the increased blood in the area to repair and replace the damaged skin.", "Blister formation has to do with the effects of inflammation and cell injury. When cells die due to burn injury, a variety of inflammatory processes go into effect, one of which is vasodilation (enlargement) of capilaries (the body's smallest vessels) in the affected area. This process serves to bring more blood to the affected area in order to fix the burn. During the vasodilation, a phenomenon known as capillary leak occurs, where the water part of blood and some soluble particles escape from the circulation and pile up the intersitial spaces (outside of the vessels) around the burn. When the top layer of skin detaches from its base due to the increased pressure, we see the blisters. As for why it remains warm, it is based on the same principle. When we have vasodilation of capillaries to one area, it increases blood flow, and with increased blood flow we also have increased heat to that area coming from the blood. The principles of inflammation are all related to the question, heat, redness, pain, and loss of function. Edit: grammar and explanation of jargon Source: med student", "I recently completed a first aid course and it was emphasized to us to cool down a burn for *20 minutes*. This is much longer than anyone typically cools down a burn for, because in the case of minor burns you'll start feeling relief much before then. The instructor assured us that the heat under the skin will continue to do damage in that 20 minutes if we weren't continually cooling the burn. And it kind of clicked for me when I equated it to, of all things, baking. I enjoy baking and there are some confections (like chocolate chip cookies) which I make sure to remove from the oven just /before/ they're done. The logic is they will continue to retain heat, and finish baking outside the oven. So if you were to take them out when they're \"done\", by the time they have cooled they might be dry or crispy or generally overdone. A similar thing is happening with a burn. Your skin is continuing to \"cook\" until all the heat has dissipated. Please remember to run minor burns under lukewarm water for a full 20 minutes.", "Quick & easy: When you have a wound the system reacts creating new mini vessels to help repair it (these mini vessels allow cells from the immune system to come more quickly), so basically there are more vessels therefore the blood flow increases and it warms up the area due to the great amount of blood.", "Speaking as someone who's dealt with industrial grade burns for almost 30 years, and having suffered some very serious burns with materials much hotter than anything found in a commercial kitchen, here's what I've learned: What's happening: The initial burn sears the outer layer of skin. When searing a steak we do this to \"lock\" in the juices, but when we do this to ourselves the outer layers of our skin lose its ability to hydrate itself. So the pours are seared/blocked, and the sting we feel is the pressure building under the layer of skin that's been seared trapping the fluids and pushing the seared layer away from still living skin below. This is also known as a blister forming. The sting is the skin layers being pushed apart. What to do: ignore mustard, butters, lotions, creams, any gimmick home remedy. Your only hope is to FLUSH WITH COOL WATER AS QUICKLY AS YOU CAN! *This is critical*. Run, don't walk, to the nearest water source and start flushing with cool water **immediately**. If you stop flushing with water and it starts to sting again, it means the top layer is still seared, pours closed, and it isn't allowing your body fluids through and it's trying to push that top layer up and away as a blister. **Keep flushing.** At some point the seared skin, though dead, will return to a porous state and can go dry without stinging, and no blister or scar will form. This might take 10 minutes. It might take two hours. Depends on the severity of the burn. If you wait too long there won't be anything you can do but seek medical attention. My worst burn was a 1,200f mass that dropped into my lap, and as I jumped up it rolled off my unprotected thigh to my knee (burning through my shirt and shorts on its way down). It took at least two hours of running water before the burn areas could go dry and not sting. Never blistered, and then the next day it looked like a sunburn where the material rolled off my exposed skin. A few days later the burn areas pealed just like a sunburn, but there was never any pain, no blistering, and no scar. TL:DR - *Quickly* running cool water over a fresh burn *until it can go dry without stinging* will prevent pain, blistering, and scaring.", "Blisters occur when small blood vessels, known as capillaries under the first layer of skin, are damaged. The damage allows smaller molecules to pass through the damaged walls of the capillaries. A blood blister occurs when the damage is large enough that blood can pass through too. Blood cells being significantly larger then water molecules. Burns remain warm due those capillaries dilating, allowing blood to flow closer to the surface. This allows the body to get nutrients and white blood cells where they need to be to protect and heal.", "Just to clear up some things here. If you get a burn, you want to run it under luke warm water. Cold water over a burn will cause more irritation. Normal body temperature is around 98 degrees so having running water jyst below this point is where you want it. What others have said about inflammation is true but the area also stays hot initially because it takes time for heat to dissipate and that's why running water over it is useful. Blisters as others have mentioned are formed from the serous (watery) portion of our blood leaks through the blood vessels in response to inflammation. If we lose enough of tat fluid our blood becomes concentrated and in severe cases you can become hypovolemic and die. This is why in patients with severe burns they will get up to 1 liter of fluid or more per hour in the emergency room to make up for the lost fluid through their burns." ], "score": [ 8036, 503, 90, 36, 18, 7, 3 ], "text_urls": [ [], [], [], [], [], [], [] ] }
[ "url" ]
[ "url" ]
79hyab
monstrous and umbral moonshine.
I'm working on an art project and the subject is hidden symmetry in geometry and number theory; monstrous and umbral moonshine. I haven't done any maths since high school and never came across these terms. Could someone give me a quick and dirty overview of these two things please? I'll be meeting with a mathematician sometime in the next few weeks to go over their personal research on the subjects, but I'd like to have a little understanding before the meeting. Thanks! :)
Mathematics
explainlikeimfive
{ "a_id": [ "dp2d431", "dxpupsr" ], "text": [ "These are *very* advanced math topics. I took a lot of math in university and didn't even come across the subject areas that they are a part of. You may need to ask in /r/askmath.", "I can't believe no one has linked to the best lay person's introduction: URL_0" ], "score": [ 7, 3 ], "text_urls": [ [], [ "https://www.quantamagazine.org/mathematicians-chase-moonshine-string-theory-connections-20150312/" ] ] }
[ "url" ]
[ "url" ]
79i04o
What is a "limit" in math?
I've done exercises with them in highschool and knew how to solve them, anyway I never really understood what they represent.
Mathematics
explainlikeimfive
{ "a_id": [ "dp22epd", "dp29xg2" ], "text": [ "It’s the value of a function as we approach a certain value for x. These are useful in cases where we can’t just plug in the value directly. Infinity is a common value to use for limits because we can’t plug it in directly, but we can also use it for smaller numbers. Take (x^2 - 1) / (x - 1) If I wanted the value for when x is 1, that would be undefined because we would be dividing by 0. However, if you graph it, you can see that the value “would be” 2 if it weren’t undefined. We can’t say the value is 2, but we can say that the value as we approach 1 is 2.", "It means \"what happens as you get infinitely close to\" a certain value. That's useful if there's something about the exact value that make it unusable, so you just get closer and closer without touching it. For example 1/x is undefined if x is exactly 0, but is easily discussed as you get very very very close to 0." ], "score": [ 14, 12 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79i3fs
The Observer Effect.
How does observing a subatomic particle such as an electron change its behaviour? What sort of mechanism causes this to happen?
Physics
explainlikeimfive
{ "a_id": [ "dp235xq", "dp2o1z9" ], "text": [ "Observing a particle essentially means measuring it. In order to measure it, you'll have to interact with it in some way. This interaction also affects the particle that you're observing, which changes its behaviour.", "I know this is ELI5, and the already suggested answer (that the only way you can observe something is to interact with it) is a great analogy that can help you visualise a particular reason this might happen, but the truth is actually more fundamental than that. Now I'm probably not the best person to try to explain this, but I'll give it a go. When you say \"change its behaviour\" it sounds like you are presupposing that it has some specific behaviour before being observed, but that's not really the case: everything is uncertain. It might be more accurate to say that before the observation the particle had a range of potential behaviours that might be observed, each with some probability. Lets say you're shooting an electron through a pair of slits towards a distant wall: the position that the electron will hit the wall comes down to chance, though some places are more likely than others. If we don't observe which slit the electron goes through then by the time the electron hits the wall there are a wide range of possibilities for where it could hit. If we set up the experiment so we know which slit the electron went through then the range of places it can hit is different because the observation limits where it can go from there. In my mind I'm imagining a police chase where the cops lose sight of a criminal and so the range of places he might have run to expands over time: a circle increasing in size. After a few minutes that circle might cover several city blocks. But then someone sights the criminal and suddenly that circle contracts to that spot! But after losing sight the circle then starts to expand again with a new centre. Observing the criminal didn't change his behaviour (well, it might have if he knew he'd been observed, but that's another story), but it does limit the range of places he could be observed going forward. Now this analogy is still a simplification, because subatomic particles interfere with themselves in non-intuitive ways so limiting what they can do lie this has complicated effects, but hopefully it at least gives you a different way of thinking about it." ], "score": [ 12, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79i3tq
How snails form their shells
I have a pet snail. Is its shell built by the snail as it grows and needs more space? Or does it grow like a toe nail? How is it attached? Bonus question: how different are snails and slugs?
Biology
explainlikeimfive
{ "a_id": [ "dp25slj", "dp2bphz", "dp2k5po" ], "text": [ "The shell is attached by the inner surface, and it grows a bit like a toenail. Snails and slugs are not exactly taxonomic terms, but in general they're actually pretty far apart. Assuming you're talking about just land ones, snails are generally herbivores while slugs will eat anything. Dead animals, insects, plants, mushrooms, worms, and all sorts of things will get eaten by slugs while snails will *usually* stay away from most of that. There are carnivorous land snails though and many water snails also eat meat.", "As the snail grows, adds to the \"leading edge\" of its shell. So the small twist at the top never gets bigger; the snail just adds more rotations as it grows. Most snails will max out at a certain size, but some marine species will grow indefinitely. The snail's shell is made of calcium carbonate, the same material as eggshells and oyster shells. Slugs are all over the place. The majority of land slugs *are* in the same order as snails (Sigmurethra), so they're basically shell-less snails. But some land slugs are in a totally different order, more closely related to sea snails.", "They move their mouth back and forth across the leading edge of the shell depositing new calcium." ], "score": [ 110, 27, 7 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79i4b5
how does recycling work
What do companies do with recycled materials, and how are they reused?
Technology
explainlikeimfive
{ "a_id": [ "dp268fs" ], "text": [ "There are many different ways that companies use recycling in daily operations. Paper Paper is very often recycled by means of mashing it into a pulp like consistency and reforming more paper. This can be used in anything from grocery bags to pages in a book. & nbsp; Glass Similarly to paper glass is sorted by clear, color, and brown varieties which are ground down to very small particles which are then melted to form new glass containers and bottles. Some companies (especially milk suppliers) reuse their glass bottles by extensively cleaning them and then bringing them back into circulation. & nbsp; Plastic Plastics are one of the largest parts of recycling centers and one of the largest pollutants of landfills. Much like glass plastic is sorted by color and then melted and made into another form, sometimes it's bottles or containers. Now they are making clothing, insulation, building materials, and much more. & nbsp; Metals The most common form is remade into sheets after removing all the paper labelling etc. From this form it can be molded into anything. & nbsp; You can see that recycling involves much of the same principles but the underlying goal is to reduce the need for \"new\" materials to be needed. This has thus far been a partial success eliminating a lot of waste from entering landfills, but there is a lot of room for improvement." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79i4d3
why are transplant patients placed on steroids (particularly heart/lung recipients)?
Biology
explainlikeimfive
{ "a_id": [ "dp23rnc", "dp2aoij" ], "text": [ "The very simple answer is that they suppress the body’s natural defenses that would attack the transplanted organ. They, in high doses, suppress white blood cell function, they suppress the production of antibodies, and other systems the body would use to reject something that was not “self” that is something transplanted in the body that had a different cellular antigen profile to the rest of the body. Each cell in the body on its surface has an antigen profile that the body’s defenses recognize as its own and the body ignores. A transplanted organ does not look like it belongs here so the body will attack it quite violently and can destroy the new organ very quickly, steroids help to suppress this system", "Steroids cause the immune system of our bodies to be suppressed which lowers our immune reaction to foreign cells and proteins. In the case of a transplant patient it would make sense to do this to prevent an immediate rejection of the foreign organ by the body. Long term, they would need to take drugs that will suppress the immune system to prevent rejection as well. When you get a steroid shot or take pills like prednisolone to get over the flu, what it's doing is reducing some of the symptoms of the illness like inflammation which are actually caused by your body fighting the invader, rather than the virus or infection itself. The side effect of this is that your entire immune system is suppressed which actually makes it easier for you to get an infection. Anybody who has ever taken methyl-prednisone to get over an illness, and later found a carpet of white mucus on their tongue has experienced this first hand. The steroid lowers the bodies immune response, and naturally occurring fungus in the mouth is able to grow un-checked and causes a thrush infection. Usually steroids are given with a round of antibiotics so between the body not fighting the fungus, and no bacteria to compete with, the fungal spores in the mouth grow." ], "score": [ 8, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79iag0
Why are our voices deeper in the morning shortly after waking up?
Biology
explainlikeimfive
{ "a_id": [ "dp25jee" ], "text": [ "When you first wake up, your muscles are more relaxed. This includes your vocal cords. Like a loose guitar string, relaxed vocal cords have a lower pitch." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79iohf
We use water to create cement mix. What stops cement from turning to mush again when it gets wet?
Chemistry
explainlikeimfive
{ "a_id": [ "dp28hvg", "dp2abuu", "dp2ac5o" ], "text": [ "There's a chemical reaction taking place. It's the same reason the paint on your walls doesn't get wet again if you get water on it, and the same reason you can't turn bread back into dough just by adding water and mushing it up.", "Edit: Oops, I forgot I was in ELI5. See below for a more full explanation, here is my attempt at ELI5: When you mix cement and water the cement dissolves in the water and new stuff starts growing. This new stuff (called C-S-H) has a larger volume than the cement and the water combined, the new stuff runs into each other and this is what makes it hard. The new stuff also turns out to not be soluble in water, so now we have a solid material with not of a lot of air space in it and water doesn't wash it away. Awesome! More concrete questions! Currently working on a Ph.D. in concrete materials science. First off, I want to clarify a few terms. Cement is a dry powder that produced in a high temperature kiln. When cement is mixed with water, we call that a cement paste. When cement, water, rock, and sand are mixed we call that concrete. As for why cement paste stays hard after you mix water and cement, ordinary portland cement (the most common type) is what we call a hydraulic cement. Hydraulic cement meaning that it reacts with water to form a material that is not water soluble. This is because a lot of complex chemical reactions take place when you mix cement and water. In order to simplify things a bit, lets take a look at the two phases in cement that are primarily responsible for hardening. There are other phases that do other stuff, but for the sake of this conversation lets ignore them. These two phases are alite (Ca3SiO5) and belite (Ca2SiO4). When alite and belite mix with water they partially dissolve and the water starts becoming saturated with calcium hydroxide. When the solution is saturated with calcium hydroxide, we start to see precipitation of crystalline calcium hydroxide and a semi-amorphous phase known as calcium-silicate-hydrate (called C-S-H). The C-S-H has a larger molecular volume than the alite and belite, so when it grows it ends up running into each other. This is essentially the hardening process. The alite and belite phases act pretty similarly, the primary difference is that the alite reaction happens more rapidly because there is more calcium. The calcium hydroxide is fairly soluble in water, but the C-S-H is pretty insoluble in water. The C-S-H is the phase of cement paste/concrete that actually holds everything together, arguably the most important phase and making up around 70% of the phase composition of hydrated cement paste. It is the fact that C-S-H is fairly insoluble in water that when you get cement paste/concrete wet after it hardens that it doesn't turn to \"mush\" again. However, when you have concrete that gets a lot of water passing through it, such as through cracks. You can get what is called \"leaching.\" This is when the water dissolves the calcium hydroxide and removes some of the calcium from the C-S-H. Generally, this isn't super harmful, but is more and indicator that there is another problem (the problem being that there is a crack for water to flow through). If you look under old concrete bridges you might be able to see small, white stalactites on the bottom of the deck. These stalactites are the result of calcium hydroxide solution coming out of the concrete by way of leaching and then when the solution reaches the surface it reacts with atmosphere carbon dioxide and precipitates calcium carbonate (CaCO3, the same composition as limestone and a bunch of other stuff).", "Chemistry :) The water and the dry ingredients in something like portland cement, under go an exothermic reaction that produces heat, and hydrated minerals which are actually water proof. The cement is not soluble though and it can even set underwater. Water can penetrate concrete but only in the pores and not undermining it's structure. When water becomes bound in the crystalline matrix of a mineral, it's said to be hydrated. You could use heat to drive the water back out of the concrete which would break down it's structure, but you can't break it up simply by adding more water because once the minerals hydrate, there is no room for additional water and so they become water proof. When you get a piece of toast wet, it turns soggy because the water diffuses into the bread and is absorbed by it. The water tries to act like a solvent rather than getting bound up in the structure of the toast because toast is not a crystallized mineral." ], "score": [ 41, 22, 3 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79jwbc
How do we know what's happening in complex biochemical reactions?
I'm not sure how to phrase this... I'm studying pharmacology which obviously involves a lot of biochem. It blows my mind how many enzymes and chemicals and reactions there are. How did we discover all the individual enzymes and reactions that take place in the Citric Acid Cycle, for instance? How are we observing cellular metabolism? It seems so complicated and amazing.
Biology
explainlikeimfive
{ "a_id": [ "dp2o8dq" ], "text": [ "This is a bit of a complex question, and I wish you'd asked it in askscience... but nonetheless... We need to go very historical on this, or otherwise this explanation will be circular. I'm not going to use the citric acid cycle as an example, because as you pointed out, it is very complex. Instead, I'm going to talk about the Cytochrome p450 enzymes, which as a pharmocologist, you are going to learn a lot about. Scientists knew that compounds in the body got broken down. They knew this because, for instance, if someone got a fright, they had lots of adrenaline in their blood, but rapidly that adrenaline disappeared from the blood. They also thought that adrenaline might get broken down into something called noradrenaline, because they could put adrenaline onto a mush made of fresh liver, and get noradrenaline. Because other scientists had said that this reaction shouldn't happen very fast without help, the scientists suspected that there must be an enzyme that did this. By carefully measuring the amount of adrenaline added, and the amount of noradrenaline formed, they found that for every molecule of adrenaline added to the liver, they got one molecular of noradrenaline formed. This really strongly suggested that the adrenaline was being converted to noradrenaline (rather than adrenaline causing the release of noradrenaline). By using centrifuges, and various other simple chemical techniques, they were able to make relatively pure samples of this enzyme. Once that happened, then real progress could be made. For instance, we already knew that enzymes can be \"saturated\". That means that if an enzyme is doing a chemical reaction, by converting compound A into compound B.. if you add more of compound A the transformation into compound B goes faster. However, if you add too much of compound A, the transformation into compound B cannot go any faster. You can think about this like if you were making a sandwich: If I gave you two pieces of bread, which you converted into a sandwich, you could do that. If I gave you two pieces of bread every half hour, you could make a sandwich every half hour. Now if I gave you the bread faster, say every five minutes, you could make a sandwich every five minutes. However, if I gave you two pieces of bread every second, you could not make a sandwich every second. You are now \"saturated\" with bread. No matter how much more bread I give you, you cannot go faster. So the scientists investigated how this enzyme in the liver which converts adrenaline to noradrenaline behaved, and they found just that. That once they gave it lots of adrenaline, it could not make noradrenaline any faster. But they found that if they added another compound (which I can't remember right now), the enzyme was able to break that compound down. How could you explain that? If you were busy making sandwiches as fast as you could, and I all of a sudden asked you to make oatmeal, you couldn't. The only explanation was that there were actually TWO kinds of enzymes. One that broke down adrenaline, and one that broke down the other compound. The scientific word for this is \"competition\". The adrenaline and the other compound were not \"competing\" for the same enzyme. Scientists continued to do experiments like this. If chemical A was saturating the enzyme, and chemical X could still be broken down, then the enzyme that broke down chemical A and chemical X were different. However, if the enzyme was saturated with chemical A, and now chemical Y could not be broken down, then chemical A and chemical Y were broken down by the same enzyme. By doing a lot of these experiments, scientists were able to discover that the original \"enzyme\" that was isolated was actually hundreds of different enzymes. They were all of the same family, as certain chemicals were able to block all of them, but they were all different, because they liked different compounds. This family is now called the cytochrome P450 family. Similar experiments were done to reveal all the enzymes in the citric acid cycle. Basically, they knew that certain compounds were being converted to other compounds. They found that certain chemicals could stop this, and when they did that, they found that instead of getting the conversion of compound A into compound Z, they got compound A turning into compound F... hence they thought that compound A turned into compound F, which then turned into compound Z. They did this kind of experiment with better and better chemicals, until the whole cycle was revealed." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79k3jx
How come our phone screens can make it harder to fall asleep if used before going to bed, yet it’s so easy to fall asleep when watching a film/tv
Technology
explainlikeimfive
{ "a_id": [ "dp2kjs8" ], "text": [ "The blue light in the phones screen is the same spectrum as sunlight. Sleep patterns work around sunlight, as you become tired as night falls. I've used apps to cut off the blue light at a specific time and the first night I knocked out at my laptop." ], "score": [ 4 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79koaq
What is Ethos, Logos, and Pathos?
I just can't interpret the meaning of these three ideas.
Other
explainlikeimfive
{ "a_id": [ "dp2pqcx", "dp2ye3b", "dp2tm8v" ], "text": [ "Ethos - Ethics. Knowing right from wrong. Logos - Logic. Knowing what can be proven and is factual. Pathos - Emotions. Knowing how someone feels about something.", "I teach college composition where we discuss these three rhetorical appeals. Let me break it down to you in a similar way as I do for my students. Okay, so \"rhetoric\" is, for our purposes, \"the art of persuasion.\" It's more complicated for phds who study rhetoric but you're a college student trying to pass an undergrad class so we can stick with the simple definition. People are trying to persuade you of shit all the time. In fact, I would argue that all forms of communication, from a restaurant menu to a car logo, are rhetiorical. But we use all sorts of different tactics to try to persuade and good ol' Aristotle broke them down into three: ethos, logos, and pathos. Ethos is credibility. Some people have cred on some topics and others don't. I used my credentials as a teacher to persuade you that I know what I'm talking about. Doesn't mean it is always successful but it is the method of the attempt. So, if Michael Jordan tries to tell you Steph Curry is the best basketball player of all time, because he has credibility in the sport, that will carry more weight than Stephen Hawking trying to convince you Le Bron James is the best player. Of course, Hawking has far more credibility when discussing astrophysics than Jordan would. Logos is logic. Seems straightforward, right? Seems like the only appeal we should ever use is logos, right? It's more complicated than that. Sure, a thick packet of data on drunk driving with tons of peer-reviewed articles *should* carry more weight than a slick commercial with celebrities saying it's wrong to drink and drive but people's minds don't always work the way we want them to. Even smart people are probably not going to sit down and read your dry packet with loads of statistics. Additionally, logos isn't always right. If you manipulate statistics, like maybe you use an average instead of a median to push your agenda, it is still a logos appeal even if it is a bad use of statistics. Pathos is emotions and it usually gets treated as the silliest appeal, the one we enlightened minds should all be above, but it's actually the one we encounter most often and we should really take it quite seriously. Your mom yells at you for staying out past curfew? She's using pathos to attempt to persuade you to not stay out late. (Would a graph on times when young people are abducted be more effective? Probably not.) Political ads, movie trailers, nostalgia-infused merchandise, jokes in online dating profiles, even the cute face your dog makes when he wants something...we are bombarded by pathos appeals and we all think we are impervious and we absolutely aren't or they would stop using them. It's also worth noting that most things mix the three together in some fashion. Also, rhetoric isn't always a lie or manipulation. Also, a rhetorical analysis isn't a position paper.", "Please donate the school fundraiser because... * logos (logic) - ...well-educated children will result in a better society for everyone. * pathos (emotion) - ...you want to help the children, right? * ethos (credibility) - ...leading experts on education agree this program will help our children be better educated." ], "score": [ 37, 7, 5 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79kqas
If oxygen and carbon dioxide are non-polar molecules, how can they dissolve in water?
I thought a molecule has to be polar for it to be able to dissolve in water.
Chemistry
explainlikeimfive
{ "a_id": [ "dp2qe4j" ], "text": [ "Some of the Carbon dioxide (CO2) will combine with Water (H2O) to form Carbonic Acid (H2CO3). Additionally, with regards to carbonation, you can \"force carbonate\" water / beer / soda using high-pressure CO2, by forcing the CO2 into solution with water. Effectively, the CO2 fills spaces between the water molecules, and if held at high pressure it will stay \"in solution.\" Any excess CO2 that doesn't dissolve in water will slowly bubble out (which is what makes it bubbly) when the pressure is released (opening a bottle of soda or a beer). Let me know if I'm way off base, this is just my understanding of it via my time working in a brewery." ], "score": [ 10 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79kt9q
is there a difference in probability between being the one chosen out of 100 people, and being the last picked out of 100 people?
Mathematics
explainlikeimfive
{ "a_id": [ "dp2r0xh" ], "text": [ "It's the same probability. You can only be picked last if every other person was picked before you, that's true, but that's a pretty inefficient way to calculate the probability. The best way to look at it is like this: If you lined up yourself and 99 other people, in how many arrangements are you last in the line-up out of how many total arrangements there are? Since we don't care about the order of the other people, we can ignore that (since for every position you could be in, there are the exact same number of orderings for the other people). Well, there's obviously just one way you could be last, just like there's just one way you could be first, out of 100 possible arrangements (one for each position you could be in). If you *wanted* to calculate it the other way, you could. You have a (99/100) chance of not being picked first. You then have a (98/99) chance of not being picked second. Since you first have to not be picked first, you have to multiply these chances together. So your chance of \"not being picked first or second\" is (99/100) \\* (98/99), and you'll notice that the 99's cancel out, leaving you with 98/100. This makes sense, because in 98 out of 100 arrangements, you're not in the first two positions. Keep going if you like. Not being in the first three would be (99/100) \\* (98/99) \\* (97/98). You'll notice that the 98's cancel out this time, leaving you with 97/100. Keep going all the way, and you end up with (99/100) \\* (98/99) \\* (97/98) \\* (96/97) \\* ... \\* (2/3) \\* (1/2) with the last (1/2) representing your chance of not being chosen second-to-last (when there are two people remaining, the other person is picked instead of you). Each denominator cancels out with the numerator just before it, except for the numerator at the very end (since it doesn't have a denominator to pair with it) and the denominator at the very beginning (since it doesn't have a numerator \"before\" it). So you're left with 1/100." ], "score": [ 5 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79ktgz
Why are metals attracted to magnets?
Physics
explainlikeimfive
{ "a_id": [ "dp355wz", "dp2vjir" ], "text": [ "**tl;dr - electrons are little magnets, and materials are magnetic based on how their electrons and atoms are arranged** Electrons are magnetic. They have a quantum property called intrinsic magnetic moment, which makes them act like very small magnets. Atoms *can be* magnetic. Electrons in atoms tend to group in pairs, orbiting in such a way that their magnetic moments cancel out, which means only atoms with half full, or nearly half full, outer shells (Iron, Nickel, Cobalt, etc) are magnetic. Lots of magnetic atoms together in a material *might be* magnetic. If the overall crystal arrangement of the atoms in a material means that the magnetic moment of its atoms point the same way, the material will be magnetic. If not, you may be able to run a magnet over the surface of a material to temporarily align the magnetic moments of the atoms, magnetising the material.", "Most of them aren't, just a select few. Notably iron, nickel, and cobalt. A few alloys (mixes) of other metals can be too. Iron being the most common metal we use means a lot of metallic objects you see are ferromagnetic (attracted to a magnet). Others like copper, gold, tin, etc aren't attracted to magnets, nor are some steel alloys even though they have iron. Magnetism is created by moving electrical charges. It's why you can make a electromagnet by passing electrical current through a coil of wire. Atoms have electrons in them, which possess spin making each one a little tiny bar magnet. In most materials they end up canceling each other out and the material becomes nonmagnetic. Only a select few elements/compounds happen to have the right amount and orientation of electron orbitals to end up with a net magnetic moment and be ferromagnetic." ], "score": [ 11, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79l4j1
What is the effect of sinking ships on the sea floor and surrounding marine life? For example the titanic, when it sunk, was it damaging in anyway? So sinking ships cause any specific effects or change the ecosystem? Does the impact of large sinking objects have any large effects?
Other
explainlikeimfive
{ "a_id": [ "dp2u3lb", "dp2uhx1" ], "text": [ "While you might consider a ship to be \"large\", they are *tiny* compared to the ocean. Yeah, they might crush whatever was directly underneath them, but again, that's negligible. Now, if an oil tanker breaks and leaks a crazy amount of oil, we have documented cases of the harm that does. But a regular ship, even a large luxury liner, that's a tiny, localised issue.", "they take retired ships, strip out all the bad stuff like oil and other liquids and whatnot and them intentionally sink them to make marine habitats. Sea life whill migrate to the sunken shinks and create whole eco systems." ], "score": [ 7, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79l715
What is "interest rate" in (Macro)economics?
I looked through my TB and Quizlets and other websites, but simply couldn't comprehend the academic definitions. Specifically, I'd like to know a kid-friendly definition of "interest rate" and it's relation to these graphs. ( URL_0 ) Thank you!
Economics
explainlikeimfive
{ "a_id": [ "dp2v9sl" ], "text": [ "It's reimbursement for the opportunity cost you've incurred by having capital on loan. Not an economist, just a guy." ], "score": [ 11 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79l8h3
Why is it that a batter is less likely to get a hit when batting against a pitcher who throws with the same arm as he bats with?
Other
explainlikeimfive
{ "a_id": [ "dp2ve3u" ], "text": [ "The batter is standing on the side of the plate opposite the one he swings with. I.e. a right handed batter stands to the left of the plate. Right handed pitchers release the ball on their right side, the one the batter has a clear view of. When the pitcher has the opposite hand they can release it obscured from your view by their body. That's just a rule of thumb of course. There are odd batters that do better against pitchers with the other hand and pitchers that do better against batters of the opposite hand." ], "score": [ 5 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79la6p
what’s the difference between emigrate, immigrate, and migrate?
Other
explainlikeimfive
{ "a_id": [ "dp2vgqb", "dp2vcfd" ], "text": [ "Migrate is general and just suggests moving from one region to another. Emigrate is to move your residence out of your country, and immigrate means to move your residence *into* a new country. So, if I move from Germany to France, I have emigrated from Germany, immigrated to France, and I have migrated from one country to another.", "Migrating means you leave and return on a cycle (and usually refers to animals), emigrating is moving to from your nation another nation, and immigrating is coming to live in a nation." ], "score": [ 15, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79m0hc
why so many sexually assaulted victims come forward against their attacker shortly after one victim does
Other
explainlikeimfive
{ "a_id": [ "dp31kk2", "dp32c9n", "dp32pxx", "dp32xvh" ], "text": [ "Because they were scared to say anything for fear of not being believed or being ridiculed. When someone else comes out, too, it adds credibility to their claim and you share any embarrassment.", "There are a lot of factors that discourage victims from speaking against their attacker. After an attack, the victim can feel shame, or a sense that due to various societal and cultural factors there is no point in coming forward against an attacker, because they might feel nothing will happen, or it's not worth the amount of emotional distress that they have to go through reliving the attack. There can be a sense of isolation, or the feeling that it comes down to \"he said, she said\". The reason victims come out of the woodwork following one victim speaking out is that there is strength and solidarity in numbers. When one or two people speak out against an attacker, it sends the message to other victims that it didn't happen to only them. It validates their feelings - they're not overreacting or making something a big deal. It shows that what happened to them was real and legitimizes their feelings about it. This can encourage people to find the support they need to speak out, because they know that they are not alone.", "While attackers seem to have the \"benefit of the doubt\", victims appear to have the \"consequence of the doubt\". When there are more people to corroborate a story, the likelihood of just persecution is greater. It turns it from a \"he said vs she said\" situation into a \"he said vs. they said\"", "First thing to ask is \"why didn't they come forward earlier\"? And that could be for a whole lot of different reasons. * They may think it's \"their fault\" they were assaulted, even if it wasn't. \"If only I'd known better\". \"If only I'd seen the signs.\" * It's intensely intensely embarrassing and can be super hard to admit that someone victimized you. * They don't want the publicity that it'll bring. You don't have to be an introvert or a very private person in order to not want your name splashed all over the place in the headlines or, if not a famous person, within your family. * They could think that it's incredibly risky to reveal what happened to them. It could cost them their job, wreck their family's stability, or the person that assaulted them could find some way to get back at them. * They could be thinking that they are entirely alone in this, so who would believe that this \"nice person\" would have done this to them? * And other reasons as well. Some of these reasons, particularly the one about being alone, instantly go away when someone else says \"Hey X assaulted me too.\". Other reasons may stay, but the massive sense of personal relief someone can get from no longer having to bear this cross their entire lives all by themselves can outweigh them. So when they hear that the person that hurt them is being accused, it's way way easier for them to say \"Hey, me too!\"" ], "score": [ 12, 4, 3, 3 ], "text_urls": [ [], [], [], [] ] }
[ "url" ]
[ "url" ]
79m3yk
What creates the red color in corned beef?
Just out of curiosity and I like corned beef.
Chemistry
explainlikeimfive
{ "a_id": [ "dp33bkx", "dp4593c" ], "text": [ "Cow muscles contain a protein called Myoglobin to hold onto oxygen inside the muscle. Most recipes for corned beef use chemicals called nitrates or nitrites to kill certain kinds of dangerous bacteria. Myoglobin just so happens to react to these chemicals, becoming Nitrosomyoglobin. Nitrosomyoglobin just so happens to be pink in color.", "The color for the most part is because of sodium nitrite which also tenderizes the meat and gives it the \"corned beef\" texture" ], "score": [ 8, 3 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79madw
What is the meaning of "1.4" in "1.4 Petrol Engine"?
Technology
explainlikeimfive
{ "a_id": [ "dp33g9t", "dp33fju", "dp33qra" ], "text": [ "1.4 is the engine displacement. It's measured by the cylinder bore (width) and stroke (the difference in the farthest travel up and down in the cylinder). Grossly overgeneralizing, larger engine displacements will result in greater power production, while smaller naturally aspirated engines (not turbo or super charged) produce less. Can't speak for where you are located, but 1.4 L would be on the smaller end of engines here in the USA. Edit: a word", "1.4 is the number of litres the cylinders have collectively, i.e. in a 4 piston 1.4 L engine each cylinder has a volume of 350 cc. How it relates to power is that the larger the volume/cylinders, the larger the explosion in each cylinder so the more force generated in the engine.", "Nowadays, it's mostly marketing, but their meaning used to show engine displacement (i.e. swept volume of all the pistons inside the cylinders of a reciprocating engine in a single movement from top dead centre (TDC) to bottom dead centre (BDC)), specified in liters. So 1.4 means the volume of the piston chamber that is where the explosion happens as the pistons move down is a total of 1400 cubic centimetres. However, these figures are usually rounded up, for multiple reasons, so you can have a 1211 cm^3 engine that is labeled as 1.3. Historically, displacement meant more power, since there was more room for the explosion, thus a more powerful explosion could happen. Furthermore, displacement is far less important in modern engines that make a lot of power from less displacement, with significant fuel savings." ], "score": [ 13, 3, 3 ], "text_urls": [ [], [], [] ] }
[ "url" ]
[ "url" ]
79mbci
Why do we get bags under our eyes when we haven't had enough sleep?
Biology
explainlikeimfive
{ "a_id": [ "dp36i7f" ], "text": [ "when the body is tired, production of a hormone called cortisol is increased to help give you the energy you need to stay awake. cortisol increases the volume of the blood in your body, which causes the blood vessels to dilate (specifically the ones below your eyes). dark circles are mostly caused by you seeing your blood vessels/blood through your skin, and the reason why they're dark is the result of light being reflected back off of the blood vessels, only blue light is reflected back and that's why they look bluish/dark." ], "score": [ 10 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79mc7h
If vegetables are so important for healthy nutrition, what do eskimos eat?
Biology
explainlikeimfive
{ "a_id": [ "dp33s5g", "dp356v9" ], "text": [ "The eskimo part is really interesting, because we wondered about that for quite a while. You're definitely not the first one to ask this, and it puzzled researchers for some time. It turns out that because eskimos tend to eat every part of their seafood catches -- typically raw -- they can still get all of those vitamins. When you're either eating purely the meat, and/or cooking everything, you don't get those vitamins. If you add the organs to your diet and don't fully cook them, you can still get all of the necessary vitamins.", "/u/Ohh_Yeah got a big part of the answer in that raw organ meats is a huge source of vitamins that us more southerly folk get from plants. But there's another huge source of nutrition that native northerners have access to: blubber. Blubber, the insulating fatty layer in whales and seals that keeps them warm in freezing-temperature sea water, is a highly nutritious and dense source of calories. It's super healthy for your heart and arteries as well. So between that and the organ meats, humans up there get everything they need to live long healthy lives." ], "score": [ 5, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79mds7
The circulatory system...
Learning advanced science at the moment but struggling to grasp the whole concept of the heart. Like the left and right components and how it all works....
Biology
explainlikeimfive
{ "a_id": [ "dp34oo9" ], "text": [ "Here's a simple explanation: Your heart has two sides, the left and the right. In each side, there's an atrium and a ventricle. Atria collect blood, and ventricles pump it. The ventricles are far more muscular than the atria. Blood enters the heart from the body into the right atrium, which collects blood. Between heart \"pumps,\" the heart is relaxed, allowing blood to flow into the right ventricle. It is then pumped through the lungs to get oxygen, where it comes back into the left atrium. The next time the heart relaxes, that blood moves into the left ventricle. From there, the heart contracts and pushes blood out of the heart into the body. **In short, it's: Right Atrium - > Right Ventricle - > Lungs - > Left Atrium - > Left Ventricle - > Body.** The atria have some amount of muscle that slightly contracts to move the blood to the ventricles, but not as much. There are also one-way valves between the atria/ventricles, preventing blood from shooting back to the atria when the heart contracts. If the left side of the heart doesn't work well, blood backs up in the lungs and causes problems like coughing and difficult breathing. If the right side doesn't work, blood backs up in the body and causes swelling/fluid leakage throughout the body, though mostly in the arms/legs." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79muf2
In the movie "Dante's Peak" there is a scene where they are in a boat and it starts to corrode
Other
explainlikeimfive
{ "a_id": [ "dp3771y", "dp37bof" ], "text": [ "Gases that are released from fissures in the ground seep into the lake, due to heat and pressure forcing it up through the soil. The heat is caused by the lava flow and pressure itself from the displaced and heated bedrock. These acidic compounds change the ph balance of the lake, making the lake more acidic compound than inert water to the degree needed to corrode metal. Structure of boat material was compromised by chemical reactions taking place at point of contact with acidic lake water, extreme heat able to boil the water may have also caused failure by more abruptly.", "Apparently, the scene with the dissolving boat in the acid lake is actually quite accurate. Not sure about the credibility of this source, but the explanation seems solid enough to me. [Source]( URL_0 )." ], "score": [ 5, 3 ], "text_urls": [ [], [ "http://www.creative-science.org.uk/hollywood4.html" ] ] }
[ "url" ]
[ "url" ]
79mvl7
Why does the human body begin to shut down after hours of sleep deprivation?
Biology
explainlikeimfive
{ "a_id": [ "dp375dm" ], "text": [ "The true answer is that we aren't *entirely* sure. Keep in mind I'm talking purely about sleep deprivation to the point of death despite proper nutrition, as opposed to simply being tired. The leading theory from peer-reviewed research is that it has to do with adenosine. When you're awake, the body produces adenosine, and it accumulates in the brain. The cells in your brain that clean up waste (astrocytes) can get rid of it while you're awake, but not at the rate it accumulates. At \"healthy\" doses, it encourages the brain to produce other chemicals to make you sleepy. In high concentrations, adenosine has shown to interrupt processes in the brain significantly. It can cause anything from cardiac arrhythmias to hallucinations. In that sense it is considered to be a neurotoxin, to some degree. As to how it works, I don't believe we've quite nailed that down yet. All we know is that at some point, adenosine begins to impede on the brain's ability to maintain homeostasis, and that finally passing out leaves a large enough window to stop breathing and die before the astrocytes can get rid of it. Mice who die from adenosine-related sleep deprivation will breathe until they pass out, at which point their brain stops breathing autonomously for them." ], "score": [ 16 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79ne51
Why does food turn black when it burns?
Chemistry
explainlikeimfive
{ "a_id": [ "dp3a9h0", "dp3ixag", "dp3m6o2", "dp3zlbn", "dp4783o", "dp48yng", "dp3tnk6" ], "text": [ "Burning could also be called carbonising. I'm sure there's someone who can explain better than me, but burning food is the exact same as burning a lump of wood. Burning is a chemical reaction called combustion, and I can't remember any exact formulas but it uses oxygen, along with the organic compounds in the wood or food (generally composed of carbon, hydrogen and oxygen with some other fun things in there). One of the by products of the reaction is carbon dioxide which is just released into the air, and another is solid carbon, which is the black stuff left behind. Sorry if this answer is a bit long but basically; TLDR: it goes black because the combustion reaction uses up most of the other parts of the compounds in the food, and what's left is solid carbon which is black. Edit: as a few people have pointed out, it is incomplete combustion that produces solid carbon, which is the result of imperfect combustion conditions, for example not enough oxygen available for the reaction.", "When food gets really hot for a long time the complex carbons in food react and break down enough to leave behind pure carbon, which is black. This will happen with pretty much any food. At lower temperatures, foods will brown due to similar reactions, but form flavor and aroma compounds instead of deteriorating completely. If this is done with amino acids and proteins, such as the grilling of meat, it is called the Maillard reaction. If it is done with carbohydrates such as sugar, is called caramelization.", "It’s a combustion reaction, the same as burning wood. Ideally a carbon-hydrogen source reacts with oxygen to form CO2 and H2O. This means if you burned anything carbon based, there shouldn’t be anything left of the material other than water and carbon dioxide gas. But oxygen is the limiting reagent in this reaction which gives harmful byproducts like CO and volatile organic compounds and leaves unreacted products like plain carbon (the black stuff). Charcoal is essentially just carbon and is often used as briquettes in barbecues because of the increased heat it gives off compared to wood. Its created by limiting oxygen during the combustion of wood to a point where only hydrogen, water and methane are released from the wood leaving behind pure carbon. tl;dr The black stuff is carbon from incomplete combustion of anything carbon based", "A lot of comments here are getting at the carbonization part, i.e. the fact that most organic matter such as food is made out of carbon (C), hydrogen (H), oxygen (O), and other elements (N, S, P), and that when you burn it, the H and O is evaporated away in the form of water (H2O), leaving behind a bunch of C. (This is a super simplified picture actually, food is very complex and consists of complex macromolecules such as carbohydrates, fats, proteins, etc., and they all respond differently to combustion/pyrolysis--with some of them actually becoming quite tasty! And while the stuff left behind is mostly carbon, a lot of other residual compounds are also present.) A detail I want to point out though is that not all carbon is black! For example, diamond 100% consists of carbon, but it is actually clear and transparent. This is because carbon atoms can be arranged in many different ways, leading to the existence of different forms of carbon, called allotropes. Some of these forms of carbon include materials such as graphite, diamond, buckyballs, graphene, and amorphous carbon. Now you might remember from chemistry that every carbon atom can form up to four bonds with its valence (outer shell) electrons. [Visual guide to allotropes of carbon]( URL_0 ) If you take a look at the image linked above, you can see that while in diamond, every carbon atom is bonded to exactly four other carbon atoms, for other materials such as graphite, the carbon atoms are only bonded to three other partners! When this is true, the extra electrons not participating in the fourth bond are actually \"delocalized\" or distributed/shared among all the carbon atoms, sort of like a giant shared electron cloud. Now to fill in the last part of the picture, where does color come from? Basically, when light or any other electromagnetic radiation hits a material, it can either be transmitted, reflected, absorbed, or scattered. Light also comes in many different frequencies, and each color is associated with a specific frequency/wavelength. For example, blue light is 450-500 nm, orange light is 590 to 620 nm, etc. When you view a colored object such as an apple being red, that means that for the white light (from the sun, artificial lighting, your camera's flash, etc.) shining/incident on the apple, all the colors making up the light are absorbed/scattered EXCEPT for the color red, which is reflected back at your eyes. Now here's the interesting part--what colors an object absorbs/scatters is completely dependent on its atomic/molecular structure! For diamonds, the carbon atoms form an extremely well-ordered and regular, almost perfect, lattice, and the frequencies of energies they absorb are very narrow as a result. This in turns results in diamond not being able to absorb/scatter any colored light in the visible spectrum, and diamond being a clear and transparent material! On the other hand, for materials such as graphite, the delocalized electrons we mentioned earlier have a lot of freedom of movement, and their random motions enable them to absorb/scatter a broader range of frequencies, including visible/colored light. This results in graphite's blackish color, since almost nothing is being reflected back at you. Suffice it to say, burned food is mostly amorphous carbon, graphite, and miscellaneous random carbon nanostructures such as nanotubes, all of which do a mighty fine job of absorbing/scattering all the visible light you can throw at it. In general, the more disordered/random/amorphous a material is, the better it is at absorbing/scattering light. If only burning food could create diamonds though, but alas, that process takes quite a bit of energy input (high pressure, high temperature, or Superman's grip) to get all the carbon atoms to form that nice, ordered lattice. Anyway, it's just super interesting how it's not only important to consider what a material is made of, but how the stuff it's made of is organized! The chemical/physical basis of color is also a fascinating topic to consider, since the color of things (pigments/dyes, veins, the sky, etc.) is something we take for granted on a day-to-day basis. Probably not quite ELI5, and I'm pretty rusty on my materials science, but just wanted to share my perspective on things!", "The same reason everything turns black when it burns?", "cause it starts to turn Metal of course. after 20 minutes at 250 degrees it reaches Black Sabbath level. After that is all cannibal corpses.", "Carbon forms a lot of different, chaotic, amorphic, and complicated structures when it forms: graphite, charcoal, diamond, nanotubes, Buckminster fullerines.... And sometimes it is a mishmash of all of the above structures. And these structures of carbon tend to be bigger than the light waves and packed. When light off the surface of the carbon, they usually just reflect into other carbon. At each reflection, the carbon absorbs a bunch more light and this continues until all the light is gone. And so it looks black: It's nearly impossible for light to miss this three dimensional forest of complicated structures. When food (mostly carbon, hydrogen, and oxygen) burns, the hydrogen and oxygen pop out of the structure and leave as water and CO2, and leave behind hot carbon (which forms the above black structure) and all the metallic and sulphur and other solid oxides (rust) that the hydrogen, oxygen, and carbon utilized." ], "score": [ 1440, 1247, 22, 16, 14, 3, 3 ], "text_urls": [ [], [], [], [ "https://www.scienceabc.com/wp-content/uploads/2016/12/Eight-allotropes-of-carbon.jpg" ], [], [], [] ] }
[ "url" ]
[ "url" ]
79nl7a
When people say that the pressure deep underwater would crush a human, how would that go down exactly?
Physics
explainlikeimfive
{ "a_id": [ "dp3bqqm" ], "text": [ "Archimedes principle: pressure is evenly distributed in a fluid. So what hat means is tiny ball scenario, you would be crushed from all sides. That being said, I don’t think the pressure is high enough to literally crush you into a tiny ball, it would just be too high for your lungs to open and breath. Either the nitrogen would get pushed out of your blood (and you would get a bubble in your vein and die) or you would suffocate. But the pressure would come from all around you." ], "score": [ 14 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79nw9k
... What is Kinematics
For my college work. I'm studying game engines and we have no idea what it is. Thanks.
Technology
explainlikeimfive
{ "a_id": [ "dp3gx2w", "dp3i5dp", "dp3e1ag" ], "text": [ "Mechanical engineer graduate here. Kinematics is the study of the motion of that object through space due to it's geometry, not forces applied to it. If you're designing something, especially something that has movement, many times the priority of your design isn't whether it can handle the loads applied to it, but how it moves. A great example is the [4 bar linkage]( URL_0 ) that's used everywhere. If you're designing an adjustable light stand, or a car trunk opening, you already know the linkage won't experience high load, so you can de-emphasize it in your design while you prioritize it's motion. You want the trunk to open a certain way. Gears and cams also fall under kinematics.", "Coming at this as a (very) amateur animator, which might be relevant if you're approaching from a game engine pov, kinematics get divided into forward and inverse. Forward kinematics would involve posing the shoulder of a character, then the elbow, then the wrist to get the hand where you want it. Inverse kinematics involves setting up rules and relationships between the bones so you can move and rotate the hand where you want it while the rules handle the bones between the hand and the body.", "It's the study of movement due to geometries, without taking into account things like forces or inertia. So if you have a hip joint and a knee joint, the knee moves in a spherical space around the hip's ball and socket joint, but the knee can only move as a simple hinge, opening and closing in its plane with less than 180 degree motion. So it only consists of the geometry and the geometric constraints imparted by the geometry of the design. Once you get into things of how fast they can go through the motion and the forces and inertias, you are veering off into kinetics." ], "score": [ 52, 35, 5 ], "text_urls": [ [ "https://en.wikipedia.org/wiki/Four-bar_linkage" ], [], [] ] }
[ "url" ]
[ "url" ]
79nwmm
Why do animation movies/shows credit a "cinematographer"? I thought these were drawn and made.
Other
explainlikeimfive
{ "a_id": [ "dp3e90h" ], "text": [ "A cinematographer is an artist who plans the angles; the perspectives in the shots which helps tells the story. It’s a major role in the visual storytelling. Think about a comic book and all the angles and perspectives the story is drawn from; that is what a cinematographer does." ], "score": [ 6 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79nwze
what is the difference between treason and conspiracy against the united states?
Other
explainlikeimfive
{ "a_id": [ "dp3evtt" ], "text": [ "Conspiracy against the United States is committing a crime as part of a group that would otherwise be named something, if you were acting solo. So if you commit tax fraud solo, you can be tried and convicted of tax fraud. If you do it with someone else, you can also be charged with conspiracy against the US. Treason is a much more specific crime. It requires actually making war against the US, or joining and giving aid to those making war on the US." ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79o2k3
How is foreign investment raising housing prices in Vancouver?
I heard that foreign, mostly Chinese, investors put a lot of their liquid cash into real estate in Vancouver, Canada for tax evasion reasons, but I don't know how this translates to higher real estate prices. If the investor is Canadian, would that also raise prices?
Economics
explainlikeimfive
{ "a_id": [ "dp3k7pl", "dp3fdhx" ], "text": [ "It's not tax evasion, but security of assets... while China has loosened up and is much more capitalistic than in the past, there's always the threat of a crackdown or attempt to confiscate assets, whether a government-wide thing or going after somebody who crosses a particuar official, etc.. It's a lot harder to do so when the asset is a house/condo in Canada or the U.S. So you have an increase in demand (number of people wanting to buy), which is growing more quickly than supply can grow. So instead of having 1 interested buyer for each property, you have 2 and that causes higher bids, potentially bidding wars, and so on. In a balanced market, you might see somebody list a house for $500k, be offered $460k and settle for $480k. In a market with low supply and high demand, somebody might offer $510k and somebody else comes in and offers $550k to outbid them! And you have actors with different goals than most real estate buyers, While the traditional home buyer or investor needs to buy something that will appraise for what they pay because the need a mortgage, and because of the real world constraints of budgets they need to get a fair deal. But for a Chinese investor who is most concerned with protecting assets from seizure, they don't care as much about the right price -- they're paying cash (no mortgage approval) and the more money they can tie up, the better. Additionally, they are often not using the homes... let's say that there are 100k units and an average of 2 people would normally be living in them. But now you've got 1/4 of the units owned and vacant -- no owners living there, and no renters either. Maybe they come visit for a week each year, or let friends/family crash there, but it's empty most of the time. So now you've got housing for 50k people sitting empty while 50k people are needing housing with that much less supply available. And since these units aren't rented out like a traditional investor might, that cuts the available number of rental units on the market. And it raises the prices of those units sold to investors planning to rent them out, meaning they need to get more in rent to cover their costs. Even all rental building are affected, because the price paid for land, paid by investors for rental buildings are benchmarked against things like rents and sale prices of comparable units.", "It is really just a result of supply and demand. Supply of housing in most markets is fairly static. However, when more people come to the market to purchase homes, there is more demand to buy the fairly static supply of housing. Econ 101 teaches us that when demand is higher but supply remains static, prices go up." ], "score": [ 8, 4 ], "text_urls": [ [], [] ] }
[ "url" ]
[ "url" ]
79o845
why do insects go through this huge metamorphosis process instead of being born close to finished like mammals do ?
Biology
explainlikeimfive
{ "a_id": [ "dp3go1c" ], "text": [ "The idea is that different generations of the insect can exploit different resources, expanding the total available food supply. For example, the larvae of a butterfly might eat leaves of one plant, but the adults might eat nectar of 5 other plants. The adults and children are then not in competition for resources!" ], "score": [ 10 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79o8jz
Why does shaking our arms/legs after stretching make them feel better
Biology
explainlikeimfive
{ "a_id": [ "dp3nf0w", "dp3n0ye", "dp3ob4f", "dp3qbou" ], "text": [ "ELI5: It helps get blood moving. More: Blood returning to the heart in a vein passes through a bunch of one-way valves that prevent blood from flowing down into the feet. A muscle contraction squeezes a vein together from the outside, and the one-way valve means the blood has nowhere to go but up. Shaking your arms and massaging your muscles essentially accomplishes the same thing.", "I am not an expert so I might be wrong but I would assume that it causes blood to flow to those areas and since blood carries all those nutrients it feels better", "We have a natural tendency to shake our limbs after a really good stretch, which is known as [stretch reflex]( URL_0 ). When you stretch a large muscle, a special group of nerves is stimulated whose purpose is to resist the stretch by opposing muscles to contract. When you shake your limbs you are easing that stress caused by the push-pull action between the opposing muscle groups and that's why you feel better.", "In addition to the common answer of blood flow here is something else that stretching helps with, my housemate learnt about this for one of his university modules and it was super interesting. NSFW Barely just some dead body parts of people but it's not grousome. No gore. [The Fuzz]( URL_0 )" ], "score": [ 414, 15, 5, 3 ], "text_urls": [ [], [], [ "https://en.wikipedia.org/wiki/Stretch_reflex" ], [ "https://youtu.be/VCfclmGrjMk" ] ] }
[ "url" ]
[ "url" ]
79ohsa
Why is something annoying to everyone except the person doing the annoying thing?
Biology
explainlikeimfive
{ "a_id": [ "dp3j0ff" ], "text": [ "If they were aware enough of what they were doing to be annoyed by it, they wouldn't do it. You only get annoyed by the things they are not aware of. Also, we perceive what we are doing very differently than others perceive us. If you are, say, chewing your food loudly, that sound is going to be a small component of your eating experience, and likely go unnoticed. Also, since can hear the sounds in your own mouth even when you are eating quickly, you aren't going to notice much difference." ], "score": [ 3 ], "text_urls": [ [] ] }
[ "url" ]
[ "url" ]
79ovdf
What causes us to laugh at things, instead of just smile
Biology
explainlikeimfive
{ "a_id": [ "dp3noti", "dp3sxwk", "dp3wp86" ], "text": [ "Laughing is a way that humans diffuse conflict and promote bonds. Laughing signals to another person that you enjoy their company, but also that you aren't going to attack them. And it's audible for the same reason that we make other mouth sounds: more communication. This is a useful skill in a species that works in groups. Imagine that someone accidentally trips you and you fall on your ass. You *could* get angry, and some people would. But others would feel compelled to laugh, even if it's awkward. We tend to like those people more, because they're reassuring the rest of us that the situation isn't that bad. URL_0", "When we see something dangerous we shout, it's an instinctive communication to other people that you've spotted a threat. Laughing is a similar response, but it's an \"all clear\" message instead of a warning. It means you've spotted something that *looks* dangerous but isn't. Like shouting, \"don't worry, false alarm!\" That's why jokes are always about subverting an expectation, usually hinting at something dangerous or taboo. The difference between a smile and a laugh is whether or not the punchline, or realization of a non-threat, is surprising enough. Like the difference between noticing a scary shape in the shadows or having something jump out at you. The first might scare you, but the second startles you. Laughing is the \"all clear\" equivalent of being startled.", "A psychology professor/researcher in CU Boulder has a theory around this called the [Benign Violation Theory]( URL_0 ) From the site: According to the theory, a violation refers to anything that threatens one’s beliefs about how the world should be. That is, something seems threatening, unsettling, or wrong. From an evolutionary perspective, humorous violations likely originated as threats to physical well-being (e.g., the attacks that make up tickling, play fighting), but expanded to include threats to psychological well-being (e.g., insults, sarcasm), including behaviors that break social norms (e.g., strange behaviors, flatulence), cultural norms (e.g., unusual accents, most scenes from the movie Borat), linguistic norms (e.g., puns, malapropisms), logic norms (e.g., absurdities, non-sequiturs), and moral norms (e.g., disrespectful behavior, bestiality). However, most things that are violations do not make people laugh. For a violation to produce humor it also needs to be perceived as benign. That is, it needs to seem okay, safe, or acceptable. Research in HuRL has highlighted three ways that a violation can seem benign: 1) Alternative norms (e.g., one meaning of a phrase in a pun doesn’t make sense, but the other meaning does), 2) commitment to a violated norm (e.g., men find sexist jokes funnier than women do), and 3) psychological distance (e.g., “comedy is tragedy plus time”)." ], "score": [ 670, 107, 17 ], "text_urls": [ [ "https://www.scientificamerican.com/article/the-science-of-laughter-and-why-it-also-has-a-dark-side1/" ], [], [ "http://leeds-faculty.colorado.edu/mcgrawp/Benign_Violation_Theory.html" ] ] }
[ "url" ]
[ "url" ]
79p22n
How do scientists know the temperature on the surface of the sun.
When the temperature is very high on the surface of the sun than how is it possible that scientists measured it?
Physics
explainlikeimfive
{ "a_id": [ "dp3nv4a", "dp3o88e", "dp3nrse", "dp3ofxh" ], "text": [ "The color. We know (because of complicated math) that certain colors correlate to certain temperatures. Specifically, these colors are wavelengths of light that we can see, and different wavelengths mean different amounts of heat. Think about a candle flame: the blue center of the flame is hotter than the redder-colored outside part. So if a star is bluer, we know it's hotter; if it's redder, we know it's colder. URL_0", "Measuring the surface is quite easy. Everything radiates black-body radiation that is depending on the temperate. That is the heat that you can feel radiate from a hot object and why even warmer thing like molten metal or a incandescent light bulb emits light. Infra red cameras (often called FLIR) also looks at the blad-body radiation to be able to see at night. The frequency distribution ie the color for visible light depends on the temperature and by only looking at the amount the sun emits of difference color we can determine that is is 5778K", "Our sun, like most stars, emit light, a form of radiation. By measuring the wavelength of the star you can roughly estimate the heat that a star radiates. There’s a bunch of equations and stuff, and using other stars for relative guesses, but idk about that stuff.", "There are a couple of ways that astronomers go about finding the surface temperature of the sun, or any other star for that matter. Consider the heating elements on an electric stove or in a toaster. As they heat up they begin glowing, first a dim deep red while cool, then brighter and whiter as they get hotter and hotter. The brightness and color of the light will be related to the temperature of the object, so that you can tell the temperature just from the light you see the object emitting. Additionally, in stars some of the light being emitted from the center of the star will be scattered by atoms in the outer layers of the star resulting in certain colors of light being seen as dimmer. These are called absorption lines in the spectrum of the star. The amount of light that these lines block are dependent on temperature and provide a second way to measure the star's surface temperature. Also, since these lines have a unique pattern for each type of atom in the star's atmosphere, we can tell what the star is made up of as well." ], "score": [ 14, 6, 3, 3 ], "text_urls": [ [ "http://www.ucolick.org/~bolte/AY4_00/week4/star_temp.html" ], [], [], [] ] }
[ "url" ]
[ "url" ]