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ljauhn
|
Why are cavities so damaging and permanent despite advancements in modern medicine?
|
Biology
|
explainlikeimfive
|
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"They're not...infections due to cavities and lost teeth used to be a huuuuge health problem. Now, thanks to modern medicine, it's just annoying. Cavities are permanent because you don't regrow enamel...it's not like bone, it can't heal. But once you have a cavity, modern dental techniques can detect it, remove the damage, and fill the cavity as a routine procedure. Properly done, it's basically a permanent fix.",
"Cavities themselves are easily taken care of when caught early. If left alone though the infection in your tooth can spread down into the root, and then into the nervous system causing a whole lot more complications",
"You cannot counteract your daily diet with medication and most people aren’t very good about taking care of their teeth. You can reduce the risk of cavities by attempting to remineralizing them with certain products or foods like hard cheeses but it is much more complex than that.",
"Bacteria in your mouth eat the sugars that you eat and poop out acid. It degrades your enamel. To stop this you have two choices: 1.Stop eating sugar 2.Pay 10k to a lab so they make a virus that attacks those specific bacteria.",
"Aggravated by demineralization bc modern man drinks too much sweet tea, carbonated sodas, and coffee. Wild Animals dont have dental cleanings, but relative to us, they dont use the same set of teeth for 100 yrs and they dont consume the same level of sugars (which stimulate dental plaques) seen in the western diet. Our ancestors had more in common with wild animals in that regard than modern man."
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ljbhsk
|
Why do doctors recommend to use anti-fungal-creme regularily in smaller doses instead of, say, 10 times per day?
|
Does it stop helping if you use it too much? Does the fungus inside the skin need time to „recuperate“ for it to be effective? Why can‘t you just drown your skin in anti-fungal-creme and be done with it?
|
Biology
|
explainlikeimfive
|
{
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"It doesn't stop helping if you add too much, rather it doesn't kill it faster if you do it 10 times a day. The antifungal has a 'half-life' through which it slowly breaks down and there's also a threshold for killing the fungus that you need to go above. As long as you achieve both, you kill the fungus."
],
"score": [
7
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[
"url"
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[
"url"
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ljbygk
|
Why does some water on the ground not freeze even though it’s way below the freezing point?
|
It has recently snowed where I live, some of the snow has melted and there’s water on the ground but it is just water. It’s currently -11°F how has that not turned to ice? Edit: added unit
|
Other
|
explainlikeimfive
|
{
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"text": [
"Oftentimes the air is below freezing temperature but the ground is not. That’s why the snow melted when it hits the ground.",
"Did they put salt down on the sidewalks/roads? & #x200B; Also what units of temperature is that?"
],
"score": [
8,
3
],
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[
"url"
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[
"url"
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ljd94f
|
If nerve impulses are so fast, why does it sometimes take a few seconds for you to feel pain?
|
For example, sometimes when you stub your toe the pain doesn’t actually register for a few seconds. Why is this?
|
Biology
|
explainlikeimfive
|
{
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"Nerve signals can travel down different “wires” the really fast wires are just for some things. Like some of your sensation is pretty much instant. Some is slower because the signal goes up the slow wires. These are called unmyelinated nerves. Myelin is kind of like fiber optics for your internet connection versus dial up. It sort of works like if you had a bunch of people sending a message from towers across a long distance by holding up signs with the letters, the signal jumps across long distances instantly. The regular nerves are like sending a courier to walk there."
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7
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"url"
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[
"url"
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lje7of
|
Why does the Northern Territory and THE Australian Capital Territory have self-government arrangements?
|
So I'm currently working on a project for my Legal Requirements unit of my course I am doing. I've only just now discovered that NT and ACT have self government arrangements. I don't need to know why for my course but I am highly intrigued and I can't make sense of any of the information I've found on google.
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnc0r18"
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"text": [
"Australia is a federation. This means that it is made up of federal states which are automatically self governing. The Northern Territory and Australian Capital Territory are not federal states. This means that they are not automatically self governing, rather, they are directly controlled by the federal government. The federal government has passed laws, which create a government in these territories, and lets those governments run those territories. So, it’s kind of like a state, but those powers come from federal law, and not the status of statehood. You see something very similar in the US with Puerto Rico and DC. You also see the same thing in Canada, with the provinces being like states and the territories being like... well, like territories hahah In a different way, you also see this in the UK. The UK is NOT a federation — which means that all parts of the UK are by default, run by the British government. However, the British government has created governments for some parts of the UK, and allowed those governments to self govern those parts. By the way, this process is called devolution. It’s found in pretty much all non-federations, and, in some cases, federations (ie, US, Canada, Australia, etc)"
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7
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[
"url"
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[
"url"
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lje7w0
|
What is chromosome deletion? And what’re the most common side effects?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnbxz7c"
],
"text": [
"Usually death. You need them all. Among things that don’t kill you, I have only heard of them occurring in the sex chromosomes. You can look up monosomy."
],
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4
],
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"url"
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[
"url"
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|
lje9zy
|
How do icicles form? If it's warm enough for the H20 to be water and drip, how is it also cold enough to freeze?
|
Chemistry
|
explainlikeimfive
|
{
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"gnbz67t"
],
"text": [
"The snow on the roof of your house is getting residual heat from your house and the sun. Even if the ambient temperature is below freezing it could still melt then it runs down your roofline to the edge where it’s exposed to open air refreezing it slowly extending as more and more water reaches the tip. Also it can come just above freezing in the daylight melt the snow some so it starts dripping then drop back below freezing at night pretty sure this is where you get small ones on trees. When you see crazy coverage on trees it’s usually because of an ice storm mix of freezing rain and sleet that’s coming from higher temp air into below freezing air and it freezes as it coats stuff. Source I live in Maine and have been through several ice storms and 36 winters of breaking icycles"
],
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8
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[
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ljeyhg
|
why so many republicans senators voted to acquit. I'm reading comments but I don't understand.
|
Other
|
explainlikeimfive
|
{
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"text": [
"Trump still has a ton of support from Republican voters. By voting to convict Trump, they'll piss off and alienate those voters. When next they're up for re-election, a pro-Trump candidate will challenge them in the primary and get Trump's support - likely dooming them or at least forcing them to spend a ton of money in the primary they can't spend in the actual election vs a Democrat.",
"Because ignoring the obvious connections in that attempted insurrection doesn’t cost them any votes... the honest fact is that there is very little moral fiber in US political systems... US voters don’t vote for people with high moral fiber. Just toe the line, win your election and keep your job."
],
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7,
3
],
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[
"url"
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[
"url"
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|
ljf72b
|
Can pouring hot water on windshield or window ice to melt it really crack the glass? or is it so rare that one shouldn't worry about it? and if so, how does it happen?
|
Physics
|
explainlikeimfive
|
{
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"When the glass heats up it expands. If it’s cold then pouring hot water on it will expand one side before the other and that causes stress inside the glass which might make it crack. Another big reason you shouldn’t try this is because if it’s really cold the boiling water could just freeze on the window or down the side of your car",
"It is very possible to crack a windshield that way. I would suggest using alcohol and water.",
"Yep, sure can. The same thing will happen if you pour boiling water into a glass, or pour icewater into a hot glass. All materials expand and contract a bit with heat. Normally, this is no big deal, since everything can stretch a bit. Glass, however, is very much *not stretchy*, and so it cannot stretch to accommodate some parts of it expanding while others aren't. As such, if it is heated unevenly, it'll often crack since it cannot stretch enough.",
"It happens by a process called thermal shock. Heating anything will cause it to expand. By only heating part of the windshield, where you pour the hot water, part of the glass expands, the other part doesn't and since glass doesn't bend, *crack*. Get an ice scraper from a gas station or big box store."
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5
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ljfyjm
|
What is gentrification? Why do people think it’s good or bad?
|
Economics
|
explainlikeimfive
|
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"text": [
"Gentrification as I understand it is an \"enriching of the neighborhood\" usually meaning more affluent people are moving in. People who think it's good see these people as more able to put money into the businesses surrounding them, and the neighborhood is more likely to see urban improvement as their tax dollars are surely also valuable, and there may be a loose belief that having \"hard-working people\" around will reduce crime by having less people in the area who may turn to crime to get by, or from the second point where cop presence may be bigger. People who think it's bad see an obvious problem: skyrocketing rents. Let's take San Francisco. Becoming Silicon Valley and having a lot of money in the area has caused rents to balloon, because there are more people in the area able to pay more for a given apartment/house. \"Charge what the market will bear.\" But this doesn't just target the people coming in with more money, it's often sweeping changes across whole areas that also hit people who already live there. Imagine paying $1000/mo for your apartment then suddenly they want to charge $1500, then $2000, over the course of just a few years instead of keeping pace with inflation or something. People who have lived in a neighborhood for sometimes *decades* get forced out by suddenly not being able to afford to live there even though they afforded it just fine before gentrification. This segues into the next problem, homelessness. Again with San Fran, it's becoming a huge problem and it's caused in part by suddenly not being able to afford the roof over your head. So from there you get streets that reek of urine and feces, you get \"defensive architecture\" installed intended to make homeless people sleep elsewhere, and you get hardworking people suddenly living out of a box at no fault of their own.",
"It’s when poor, rundown areas see wealthier people move in and fix things up, and real estate prices rise, Typically, white creative types like artists and musicians move in first for the cheap rents. Galleries and music venues pop up, then cafes and cheap restaurants catering to these née residents. Cool people start hanging out here, then start moving in... chefs, designers, other creative types with actual jobs/careers. As it becomes trendier and safer, people begin buying homes and rehabbing them, building on vacant lots. Investors start developing to sell. Chain businesses start looking to move into are. It’s good in that it revitalizes neighborhoods, is often areas closer to center of town instead of promoting more sprawl, it’s a sign of growing wealth in an area, creates rising tax base. But it’s also seen as a negative because it’s predominantly wealthy whites displacing poor minorities and pricing them out of their own neighborhoods because of rising rents and property taxes. Multi-unit buildings get replaced with single family homes, further reducing affordable housing stock. And local businesses that catered to that minority group also get forced out due to rising rents and reduced customer base. Often the new businesses cater to the new residents at price points older residents cannot afford. And eventually national chains come in. So the Cuban diner gets replaced by the hipster coffee house that gets replaced by Starbucks. The laundromat becomes a boutique, then eventually a Lululemon.",
"If there's a run-down section of a city, young middle-class people may move in, getting some of the advantages of urban life at less cost than tonier neighborhoods. If it goes well, others follow. Property values increase, crime rates decrease, new businesses open to serve the new customers. Which is good. ... Unless you're an existing renter in the neighborhood. If you own your home, at least you'll benefit from the rising property values, when you sell. In the meantime, you're faced with rising costs, and the old businesses that served the old residents are being replaced with fern bars or whatever, catering to the new people.",
"Gentrification is the name for the process a poorer neighborhood goes through when wealthier people move in, building/improving property and new businesses. This can be seen as a positive for the community. Because this increases property values in the area and can bring in new businesses, revitalizing a neighborhood and bringing new development. That all sounds great, but to the people living in the neighborhood it can cause problems. For one, the only people benefiting from the increased property are people who already own property. Anyone who lives there but is renting is going to find their rent increasing, possibly to extents where they can no longer afford their rent and are forced to move out. Basically a lot of people from the neighborhood may feel bitter that they’re getting pushed out of their home or neighborhood and not benefitting from the changes in the neighborhood, just getting pushed out of the place they called home.",
"Super high level and missing all the nuance. People with money (or those who want to market to them) start moving into and changing an area with lower income. They change it into what they want, which doesn't always align with existing residents and businesses. Mostly though it causes prices to rise, as well as a bunch of other behaviors and actions that force out the existing residents. Those people suddenly can't afford or otherwise are forced out, with no where to go and end up in worse situations than they already are. Some businesses and residents benefit, the city gets more tax money and economy, and bunch of people are displaced (or worse). That's the SUPER GENERIC why some like and hate it.",
"The worst part of gentrification, which probably doesn't get the attention it should, is the landlords and developers who exploit the situation. They deserve most of the blame, as opposed to the people who were attracted to a cheaper neighbourhood."
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ljg2di
|
Why do things sound louder at night than during the day?
|
for example when ever I'm walking downstairs or getting something to eat at night i feel like I'm gonna wake the whole house up
|
Other
|
explainlikeimfive
|
{
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"text": [
"\"Loudness\" is partially about the context of all other sounds. Like a jet engine is always loud in most everyday situations. But if you're judging between the loudness of talking and whispering, it also depends on how loud the environment is. Night time is way quieter than daytime because people aren't as active (meaning their machines are also less active, like cars). Why is this the case? Because perception isn't the same thing as the actual physical properties. E.g., the same wavelength of blue light can look darker or brighter if it is surrounded by dark (it'll look even brighter) or bright (it looks even darker) colors. Picture example: [ URL_0 ]( URL_0 ) famously, A and B are the exact same shade. But we perceive them differently. Perception is a complicated thing. Edit to add: I also forgot the role of attention. More attention == heightened sensory perception. You pay more attention to your sounds at night because you're aware you're supposed to be quiet.",
"Two reasons I can think of: Air is cooler and more dense at night. Sound travels much faster and further through denser materials. There is usually less background noise at night (traffic, construction, kids playing, deliveries, etc)"
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[
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ljh6d9
|
How is it that clothes ALWAYS produce more lint?
|
It just blows my mind that no matter how many times I wash my clothes I always have to clean the lint trap afterwards. My little ape brain wants to believe that there is a finite amount of “lint” that can shed from clothes but I’m willing to be proven wrong!
|
Other
|
explainlikeimfive
|
{
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"\"lint\" is not just one specific thing. Lint is made up of many different things that get stuck to the fibers in your clothes and also the fibers of the clothes themselves. Every time you wear your clothes you accumulate more lint. That's why there is always lint.",
"Lint is not just stuff that accumulates ON clothes. Lint IS clothes. Every time you wash/dry your clothes, they lose some fibers which end up in the lint trap. There is a \"finite\" amount, but that limit is when your clothes are converted entirely to lint and begin falling apart. They get *slightly* closer with every wash. Also another component of lint is dust from the world, which you pick up a fresh layer of every time you wear the clothes. So that part will never run out either.",
"Cotton/natural thread is basically lint/fiber rolled into yarns. These thread yarns are what make up our clothing/towels/etc. Each time you wash the clothes, the loose lint gets collected."
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6
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ljh6js
|
How is it that an earthquake can be an aftershock of an earthquake 10 years ago?
|
Earth Science
|
explainlikeimfive
|
{
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"gncn4ax"
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"text": [
"Earth moves very slowly, imagine dominoes getting tipped over onto each other except its the entire planet and the dominoes are in slow motion."
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5
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"url"
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[
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|
ljhaam
|
what’s the difference between a fracture/break and a dislocation?
|
This might be a silly question but I’m not sure what the difference is. I know people who can reset their own dislocated limbs but you’re not supposed to mess with broken bones yourself I guess. Maybe you’re not supposed to reset dislocations either and people just do it anyway?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Two bones come together in a joint. These are two separate bones, but come together. Think your arm and your shoulder. In a dislocation, the two bones aren’t coming together how they’re supposed to. Resetting it involves manipulating the bone that had moved back into the joint. A fracture/break means the bone is actually broken/cracked. You can’t just put it back together- imagine like a cracked baseball bat. It needs to be immobilized so the body can heal it over time, or surgically repaired with metal or similar.",
"Think of a Bionicle or Hero Factory figure. In the Lego kits, there are balls at the end of arm and leg pieces. They fit into sockets and allow for movement. Dislocation is when that ball is removed from the socket, such as your femur (thigh bone) or humerus (upper arm bone). Now think of when a Lego piece is snapped in two. This is a break. It is possible to set it back together but it requires extra tools than the kit comes with (glue) and time in order to make sure it goes back together right. Have you ever had a Lego piece, or a piece of plastic in general, that you pushed too hard on and it turned white? Maybe it got a crack? That's a fracture. It hasn't broken completely but it's not as strong any more due to stress placed on it. Putting some glue on it and letting it dry before using it again will ensure it will hold work properly.",
"Bones meet together at joints, and they're supposed to meet together in a specific way to move and bend correctly. Sometimes you can knock a bone out of its joint. This is dislocation. A break/fracture is when the bone itself actually breaks. For a dislocation, the bones themselves aren't necessarily damaged, one is just out of place and can be put back in place (if you know what you're doing). A broken bone often needs specialized treatment (such as a cast) to heal correctly."
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ljhsyd
|
how does salt make ice melt?
|
Chemistry
|
explainlikeimfive
|
{
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"text": [
"When salt (NaCl) dissolves, it forms Na+ and Cl- ions. These charged particles interfere with the hydrogen bonds that water forms when it freezes. When water freezes, the negative side of a water molecule attracts the positive side of another water molecule. This forms chains of water molecules, which make up solid ice. The Na+ and Cl- ions interfere with the creation of these water chains, lowering the temperature that ice freezes at.",
"Salt doesn't make ice melt, it just makes it harder for water to freeze. It does this by reducing the freezing temperature of water."
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12
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lji0r8
|
- Why is it that when we look at an object in motion, our eyes can follow it flawlessly, yet when looking at a static object our eyes move point-to-point?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"What you're talking about is a \"saccade\". It happens because the portion of your visual field which is sharp and clear is actually far smaller than you think it is--the larger clear picture you see is built up by your eyes darting rapidly over the image, building up a larger, clearer picture in your head. If you're following a moving object, on the other hand, you don't have time to do that so you just keep moving your eyes to follow the object.",
"There are several distinct neural control systems for eye movements. One is smooth pursuit, which \"follows flawlessly\" by keeping the moving object centered at one spot in the retina, usually a rather small area of high resolution vision called the fovea. Another control system is for saccades, which are fast, darting motions that help build up the mind's image, again taking advantage off the high resolution fovea. Saccades are so fast that the visual image is briefly blurred during the movement, but then the eye is held still, \"fixated,\" for long enough to get a clear look. There's no way to voluntarily move the eye smoothly, because smooth pursuit cannot function without a moving target. Specifically, there's an error signal produced from the target's motion, between successive locations on the retina. The smooth pursuit system automatically tries to keep that error small. Although the brain ultimately coordinates the multiple control systems, each has distinct neural circuitry that makes some motions impossible, e.g. make a smooth saccade, or a jerky pursuit. Interestingly, the world you see is really an imaginary picture built up by your mind. The fovea's image is pretty small, about the size of two moons (as seen by your eye). The rest of the retina is most poor resolution and gray-scale. Your brain automatically makes saccades to fill in detail, and keeps a memory of past saccades. It also doesn't inform you what is recent and what is old information, nor what it made up. Yes, it makes up information. Your brain is highly predictive, and makes a lot of assumptions to allow it to focus on things of interest. This is partly why there is attentional blindness, and the famous \"Paris in the the spring\" where many people don't see one of the *the'*s. When reading, the eye can literally jump over multiple words if your brain thinks it can predict them, even if you think you read every word.",
"You can move your eyes fluidly so long as they are out of focus. Your brain is trained to move your eyes to what they are focusing on so willing your vision to a specific something is point to point. Edit: so now ive been moving my eyes around in circles for about 5 minutes and realized the eye is moving fluidly but my attention and focus is point to point."
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ljie8z
|
Why do movies depict people sliding under descending doors on their back, feet first?
|
Physics
|
explainlikeimfive
|
{
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"I know generally whenever entering and unknown space at any velocity you always go feet first. Like jumping into water. It also offers a more defensive position",
"My take is that it is because it is easier to run and slide with your feet ahead of you since there is more \"opening\" at the bottom of a descending door. If you aim wrong, you could be hitting your head on the door coming down. The reverse applies to when jumping out a window. The head/torso area is closer to the window opening, so you go head first instead of feet first."
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3
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"url"
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[
"url"
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|
ljihux
|
why can’t fish breath outside water?
|
I feel really stupid asking this but here we go. So water goes into the fish’s mouth, then it gets separated from the oxygen and shot out through the gills. Right? So the gills are there to shoot out the water once they grabbed the oxygen. Right? So why can’t they breath outside water? They get oxygen and there’s no water to shoot out. Thanks!
|
Biology
|
explainlikeimfive
|
{
"a_id": [
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"text": [
"Gills are wet, feather like things that work best underwater. When out of water, they clump up and can't get oxygen as well anymore."
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7
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[
"url"
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[
"url"
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ljivgn
|
Why does heat make the air wiggly?
|
Earth Science
|
explainlikeimfive
|
{
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"When light goes from one medium to another, it experiences what is known as refraction. At the moment it passes from one to the other, it bends at an angle specific to that substance, that angle varies depending on density and what it is made of. This is why if you look at a pool of water, your perception of depth is really odd at shallow angles. When air is hot, it rises. That rising hot air mixes with cooler air just above it in a chaotic swirling mess. Light passes from hot, light air to cool, denser air over and over and over as it mixes. That makes it shimmer and wave",
"Air at different thicknesses bends light different amounts and hot air is thinner than cold air (due to molecular energy making it spread out). A cold room or a hot room both at least look consistent, so we don't really notice the difference in most cases, but when something really hot starts heating up the air in a relatively cooler place, you get to see the differences side by side. Then when the hot air rises, it produces a wiggly effect as it worms its way through the thick cold air.",
"The same reason that water makes stuff wiggly. Change in refractive index causes light to change path. Heat in the air is changing (semi randomly) the refractive index of the air, so light coming through it wiggles.",
"When particles get hot, they love to dance. When hot particles (in your area) are dancing they can change how light (and sounds) behave. Wiggly air is just hot air dancing around making light move a little weird. To your eyes, it makes the stuff behind all that dancing air, wave and shake a little, at long distances or particularly hot and flat areas, it can even look like water.",
"Light goes faster or slower in different materials, including hotter (goes faster) and colder (goes slower) air. Also, light always takes the quickest path to get someplace. So just like if you were rescuing a drowning person at the beach it would make sense to run on the beach more and then turn toward the person as you entered the water, to get to the person as quickly as possible, light changes directions as it goes from one material to another where its speed changes. As warm air mixes with cool air, the quickest path can rapidly change, causing the shimmering effect you see.",
"You know how when you're standing next to a pool looking at the tiles on the floor, it looks all wavy? The same thing happens when you're under water in the pool and look up at the surface. The light is all wiggly, because the surface of the water is wavy. That happens because rays of light get \"bent\" when they go from one material (e.g. air) into another (e.g. water). Light usually gets bent most when it goes between materials that have very different densities -- water and glass are much heavier than air, so the effect is big. But glass and water are both similarly heavy, so the effect is not so big, which is why shards of glass can sometimes be almost invisible under water. Well, you know that hot air rises, and cold air falls, right? Well, that happens because air expands when it heats up, which makes warmer lighter (i.e. less dense) than colder air. So you see the cooler air is a denser material (like water in the pool) and the hotter air is lighter material (like the normal air above the pool), and the surface between the hot air and the cool air is wavy and bends the light, which makes the air look wiggly."
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ljj6u1
|
Why do some of our internal organs display symmetry (e.g. brain, lungs, kidneys, reproductive) but others do not (e.g. heart, liver, stomach, intestines)?
|
Biology
|
explainlikeimfive
|
{
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"The ones that you say are symmetrical are actually less symmetrical than you'd think. The brain lateralises (so only one side has a particular function) some cognitive functions. The right lung has 3 lobes, the left has 2. The left kidney is higher than the right. It's kind of a function of fitting everything into the neat space that you call your body and having to serve different functions. The general schematic of the heart is symmetric, but the left ventricle becomes enlarged because you need it to pump more pressure through the body. The liver has different sized lobes, likely because of how much each lobe of the liver receives blood when you develop. The stomach and intestines start off as a tube but become different because different parts of the intestines have different roles, and they rotate in complicated ways to fit everything into the body. There's not really an underlying special cause that separates organs that are symmetric with ones that aren't. It's just kind of how the cards fall when your body grows.",
"so, most people here are arguing for there being less symmetry than you think, and it's not exactly wrong that one teste hangs lower and that kidneys aren't 100% the same, but i would argue the opposite kinda. the fact that we have so many pairs of organs is a result of our fetal development being *very* symmetrical. this is obvious in most organs, two lungs, two kidneys, two testes/ovaries etc. but most of the ones that appear singular are developed in a similar fashion. fetuses actually have two hearts that then grow together, and you can kinda look at the heart as two separate pumps for the two circulatory systems. your brain has two lobes of course, but so does your liver. really the only odd one out here is the stomach and the instestines.",
"I thought the question was why do we have 2 lungs, kidneys but only 1 liver, stomach, etc, not their physical size compared to each other.",
"The question of how asymmetry is generated in an embryo that starts off with completely symmetrical morphology is still not answered entirely. Basically, all bilateral symmetrical organs like lungs, kidneys or gonads are derived from precursor cells on both sides of the embryo; each develops into one organ. The non-symmetrical organs either originate as a structure in the centre plane of the embryo (e.g. the gastrointestinal tract, which is a long tube from the mouth to the anus that elongates and loops in special ways) or derived from two bilateral structures that fuse in the middle (e.g. the heart). It's still not completely clear how cells know if they are on the right or the left side and therefore, if they should proliferate and initiate bulging and elongation or not. And still, in most humans, the colons starts on right and the aorta is on the left. In the early embro, there is a region that is called \"primitive node\" which carries motile cilia - moving hair-like cell appendages - that can create a fluid current. One theory states that this current induces a gradient of molecules in the embryo that determines which side is which. There is a disease called [\"Primary ciliary dyskinesia\"]( URL_0 ) in which these cilia can't move properly. Apparently, the generation of asymmetry in this case is random, which is why patients often have what is called \"Situs inversus\" - an inverted arrangement of organs with their heart on the right side and their liver on the left.",
"I actually have a pelvic kidney. Found out during my ultrasound with my daughter. They tec was searching and searching and I'm like, \"uh.. can you not find something?\" Apparently it's very common for organs not to be where they \"should\". You might even have a pelvic kidney and not know!"
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ljk22l
|
How's Dungeons and Dragons played? What's the purpose of many different sided dice (D4, D6, D12, D20, etc.)?
|
Other
|
explainlikeimfive
|
{
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"You know when you were kids and played make-believe? And then it turned into \"I shot you!\" \"No, you didn't!\" Dungeons and Dragons is like that, only with rules so that conflicts can be settled, generally by rolling dice. It's sort of a hybrid between live theatre and a board game. People sit around a table and tell a story. All but one of the participants has a character they portray, a fantasy adventurer. They could play an elf wizard with a superiority complex, a dwarven fighter who also loves poetry, a human cleric who worships a god of battle. You get to invent what character you play, using a set of rules. Many people like having people draw art of their character. One of the participants is the Dungeon Master, who is both in charge of the story and the rules. Like the director of a play and the referee of a game at once. The Dungeon Master portrays all the other characters the heroes encounter, like the old lady who runs the tavern and sells ale, the prince who has been captured by bandits, the skeleton lord who wants to use the prince's amulet to gain ultimate power. When there's battles or magic or anything else that has a chance of failure, the players use a set of rules to keep it fair. This mostly involves rolling dice, and adding the relevant stats that the character has to the result. Such as lifting a heavy boulder might involve a character's Strength stat, while convincing a guard to take a break and let this stranger through might involve a character's Charisma stat. D & D uses different dice for different probabilities. Certain weapons might use a six sided die (D6 in D & D terms) for how much damage they deal, with another weapon might use a 12 sided die instead.",
"It's playing a game of pretend with group of people that are part of a story. One person is in charge of the rules. They are the Dungeon Master or DM for short. The players and the DM use the dice to represent the chance of things happening, how much something is affected in the game or to represent random chance.",
"As addendum - D & D is only one (though it is the most popular) of many RPG systems available. There are things they have in common - they all serve as rules to support role-playing, offer you options for character building, methods of conflict resolution and a way of quantifying how good your character is at certain things. They differ in how they achieve them though. They differ in what types of game they facilitate. D & D is high fantasy - characters rather quickly learn how to perform superhuman feats and fight scary monsters, they do so with swords and magic. Shadowrun is a futuristic cyberpunk-fantasy mix, where you drive cars, shoot guns and cast spells. Vampire the Masquerade restricts you to playing vampires in a dark world of political machinations and nonexistent morals. In Shadowrun you only need 6 sided dice to do everything. Warhammer likes percentile rolls (two 10 sided dice rolled together to give a 1-100 range) for most things. Basically this is just a way of generating random numbers that the rules tell you how to interpret. D & D in particular uses 20 sided die as the main one - that gives you the general chance to hit, chance to succeed in persuasion, chance to resist mind control etc. All the other dice are extra, to differentiate how much damage each spell/weapon deals.",
"Most of the dice are just for damage, D4-D12. Everything else is done with the D20. Any time you wish to perform the action, you let the DM know and they'll give you a relevant skill to use. Each character has a number for that skill which is determined by adding the assigned stat, and any other bonuses (a magic item, if your character is proficient in that skill, etc). You then add all those numbers together with the number you rolled on your D20. If your number beats a target number set by the DM you are able to do the action which the DM then narrates. Whether that be attacking a monster, resisting the effects of a spell, or trying to charm a dragon so it'll go on a date with you instead of eating your friends depends on the scenario set by your DM, and the actions/repercussions of your party. There are rules laid out through lots of practice and testing that help the DM decide what the target numbers for the players to roll SHOULD be to make a fun and balanced game, but ultimately the DM decides the fate of the whole narrative.",
"DnD is basically a framework for improvisational storytelling and roll playing. The players create characters that have a set of numeric statistics that describe what they're good at. Things like strength, wisdom, intelligence, and so on. The dungeon master will describe a scene and then the players describe how they will react to it. If the players want to react in a way that has a chance of failure, the DM will tell them to take a test to see if they succeed or not. For example: > **Dungeon Master (DM):** We start the evening in the Laughing Faun, a famous drinking hole for rogues and adventurers. You have been winning at cards all night. The rough-looking dwarfen caravan guard sitting opposite you has had enough. \"Cheater!\" he roars, nobody wins this often! Behind him, you see his fellow caravan guards taking notice. What do you do? > > **Barbarian player:** Finally, a brawl! I will flip this table on top of the dwarf, that'll give me time to grab my ax. Most tests in DnD work the same way. If there's some kind of challenge, whether it's landing a hit with a sword, casting a spell or finding a secret passage, the test works in roughly the same way. The dungeon master will set a difficulty for the test. Then the player rolls a d20 adds the relevant stat modifier and then adds or subtracts any modifiers. Let's go back to the Laughing Faun. > **DM**: Alright, it's a heavy oak table, we'll set the difficulty at 15. Roll a strength test to see if you succeed. The barbarian player has a high strength stat, which gives him a modifier of +2 on strength tests. He is also proficient in Athletics, which provides a further +2 modifier. The barbarian players roll a d20 and score 12 + 2 for his Strength modifier and another +2 for his Athletics proficiency for a total of 16. > **DM:** with a mighty roar you flip the heavy table onto the dwarf. This takes him completely by surprise and he is now prone on the floor of the tavern. His fellow guardsmen shout in outrage and draw their weapons. They rush in to help their commander. Roll for initiative! Outside of combat, DnD is pretty freeform. You're free to do many things like moving around, asking questions, or examining things. The DM will describe the scene and the players describe how they respond or act. But when a fight breaks out, you start an encounter. These are a little more rigid and turn-based. During a round of combat, every player and NPC gets to move and act in initiative order. That means that faster creatures and players usually act before slower ones. The barbarian and his fellow players roll for initiative and get ready for a fight. The DM describes the starting situation of the encounter and then the first player or NPC in the initiative order gets to act. > **Barbarian player:** I laugh at this foolish dwarf as I whip out my ax. He'll be the first to die squirming under the table I threw on top of him. I will strike out at him! Much like flipping the table, combat is a series of tests that are modified by stats and this case results in dealing damage. Dungeons and Dragons have an enormous amount of granular information to deal with an enormous amount of situations. But it all just comes back to this basic stat check. You can be hungry, exhausted, deaf, blind, mute and so on but it all just relates back to either. giving you a modifier to certain tests or simply banning you from certain tests. If you're mute, you can't do tests that involve speaking. There are a great many monsters with a great many abilities but in the end, all of those abilities are resolved with tests. A sticky monster might prevent you from moving. Or give you a disadvantage on any physical actions you want to undertake for example. And it's really up to you how many of these rules you want to use. DnD is a framework. It's there to help you do what you want to do but no more. For example, DnD has many detailed rules about travel distance and speed. How long and far you can travel before you get exhausted and need food and rest. And it has weights for every single item in your inventory. So if you like, you can count how many ball bearings you can carry before the weight starts to tire you out. But my group finds that level of detail far too tedious so we don't use weight limits. Along the same lines, some people just get lost in the roleplaying and hardly ever fight. I've read stories about player groups who realized that a certain goblin cave had a high salt content in the walls. So they quickly killed all of the goblins and over the course of a real-time year's worth of weekly sessions they turned the goblin cave into a salt mine, the salt mine into a mining camp, the mining camp into a fortified settlement, and set themselves up as new nobility of this town. Everything in DnD has a value for selling and buying in shops. Mostly to let players play around with loot. But in theory, players can focus on that and do something like setting up their own town."
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|
ljkesk
|
How do the Great Plague/Black Death come to end?
|
Other
|
explainlikeimfive
|
{
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"text": [
"The Black Death was a bubonic plague pandemic. Some figures put the death toll at 200 million (at a time when the population of the entire world was less than half a billion). It killed so many people that it took nearly 200 years for the population in Europe to recover to pre pandemic levels. It \"ended\" because the survivors became increasingly resistant to the disease. The plague would resurface regularly infecting most of the population, but fewer and fewer people would die in each outbreak. Eventually it got to the point where too many people were naturally immune for it to cause the same level of havoc, although there were still pandemics into the 20th century. These days we can treat it with antibiotics. Basically it killed so many people that it ran out of victims who couldn't fight back.",
"You mean the Bubonic plague? No one really knows, main part was that 3/4 Europe was wiped out, which could mean the others were immune...",
"By Great Plague, do you mean the London plague of the 17th century? There is no certainty as to why the plague ended, but many believe that the Great Fire of London helped by killing and burning many of the infect fleas and rats. The Black Death (again no certainty) probably ended due to the quarantines. People stayed at home and did not travel, and thus the plague stopped to spread. A lot of people fled the dense cities to rural areas, and that helped stopped the spread as well. Plague was present in Europe for centuries, coming back every 30 years or so some cities killing thousands. It was not until advances in medical care of the 19th century and the antibiotics of the 20th century when plague was contained.",
"Probably a diversity of circumstances but one of the leading theories was extreme winter cold killing the vector. The plague was spread primarily by flees hitching a ride on rats and other animals that spread throughout human habitation."
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ljljyz
|
How do anti-depressants work?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Brain scientist here: my background is in brain biology, and I currently work in mental health. TL;DR: no one really knows. We thought we did, but it turns out the reason we *thought* they worked is probably wrong. The brain is complicated, and depression is particular is one of those disorders where we don't really have a clear understanding of the biology of it yet. We have lots of good ideas, but we're far, far from settling it. There are a few different types of anti-depressents. The most common ones are SSRIs, Tri-cyclics, and MAOIs. To keep the scope small, I'll focus on these. Before I explain the medicines themselves, I need to explain the 'monoamine hypothesis' - one of the good ideas we had about how depression works, that's currently fallen out of favor. When our nerves send messages between each other, they send out a wave of tiny chemicals called Neurotransmitters. The size of this wave, the mixture of chemicals, and the timing all are important for how our nerves 'talk' to each other. Serotonin and Dopamine are chemicals that you hear a lot about in popular science as being 'happiness chemicals'. They're neurotransmitters. Specifically, they're part of a group of neurotransmitters that we call 'monoamines' because of their structure. Each individual chemical doesn't have much meaning on its own - the mixture and timing of chemicals being sent is more important - but they do tend to be used more or less in certain signals. One idea around how depression *might* work was that the brain didn't make enough of these monoamines for some reason. In this case, it might use them up on the necessary functions (ie. staying alive), and not have any left for the less critical functions (for example, happy emotions and enjoyment). This is called the the 'monoamine hypothesis'. When people talk about 'chemical imbalances' this is usually what they mean. All three of these drugs affect the amount of monoamines in some way. MAOIs were the first wave of medicines based on this idea. The acronym stands for 'Mono-Amine Oxidase inhibitor'. Monoamine oxidases are a type of cellular machinery that acts as part of the clean up crew in tour body. Specifically, they tidy up extra monoamines, to help keep the balance correct. MAOIs slow these machines down, and the result is that your body ends up with a bigger supply of all the monoamines. They aren't used much anymore because of the side effects, though it must be said that a lot of the side effects were down to the fact that it was a new medicine that doctors didn't necessarily know how to dose correctly. Tri-cyclic antidepressants were the 'second wave'. These have a bunch of different effects, but one of the main ones is they target a particular type of transporter machinery that collects Serotonin and another neurotransmitter called Norepinephrine. This stops these neurotransmitters from even reaching the clean up machinery that MAOIs target. Tri-cyclics don't affect Dopamine, so they're more specific. I'm not actually sure where the name came from. They're not prescribed for depression much these days for a number of reasons, including because they can be very very dangerous in an overdose. They've turned out to be quite effective for a number of other uses though. SSRI stands for 'selective serotonin re-uptake inhibitor'. They prevent 're-uptake', or recycling of serotonin specifically. So basically, they're an *even more* specific drug than MAOIs and Tri-cyclics. Being specific is good because it means less unintended effects. I mentioned that the 'monoamine hypothesis' has fallen out of favor recently. I'll briefly explain why. The idea became very popular once we realised that MAOIs, for some people at least, worked quite well. This was a big breakthrough, because depression was considered quite difficult to treat. But in the research we've done since they were invented, it's become clear that while the drugs themselves may work, increased amounts of monoamines don't actually seem to be the reason *why* they work. In other words, the idea that led us to make these drugs seems to be at least flawed, but we got lucky and found something that worked anyways. The evidence for this is pretty broad, but for example: If serotonin levels were the problem, then you'd expect the depression to go away when monoamine levels are 'fixed'. But it doesn't. Monoamine levels go way up pretty much immediately, and they stay up, but SSRIs take weeks or months sometimes to start working. So, something else must be going on. Plus, many people with depression have perfectly normal levels of monoamines. There's a bunch more evidence for why the monoamine hypothesis doesn't seem to be what's actually happening *despite* the medicines we have working, but it would quickly pass the scope of eli5",
"The most common antidepressants are SSRI, which stands for selective serotonin re-up take inhibitors, depression is associated, at a chemical level, with diminished response to serotonin, one neuron releases serotonin and the neuron that receives it reacts less than expected, the serotonin goes into a space between neurons, to give the signal, and since its a scarce resource, its reabsorbed so it can be released again and not wasted, SSRI work by inhibiting the reabsorption so the signal lasts for longer, imagine I'm sending you a message but I delete before you can read it, SSRI make it so it takes longer to delete...if the message is a serotonin stimulus, if its too short it will lead to depression",
"Antidepressants work by balancing chemicals in your brain called neurotransmitters that affect mood and emotions. These depression medicines can help improve your mood, help you sleep better, and increase your appetite and concentration. It usually takes at least three to four weeks before you notice a change in your mood. Sometimes it can take even longer. Taking the medicine every day as directed helps increase the chance that it works."
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ljm0nz
|
When swimming in ocean water, how does the body avoid overdosing on salt?
|
Biology
|
explainlikeimfive
|
{
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],
"text": [
"Our skin has very poor absorption. That gross feeling you get after swimming in the ocean, where it feels like your skin has shrunk down a size; that's the salt ON your skin. And you feel much better after you wash it off with fresh water. But the salt isn't absorbing through our skin. If I was a biology teacher & a student asked this in class, I'd take out all the whisky I has stashed in my desk, and fill up a tub. I'd make u soak in it for the entire period & tell me how drunk u were when the bell rang. Alcohol and salt are both suspended in water, but don't absorb through our skin. I'd then empty out my desk & start looking for a new job.",
"Unless you’re drinking the water, you’re not taking salt into your body. Your skin, among other things, prevents it from entering your bloodstream."
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[
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ljmoby
|
Why can bones heal but teeth can not?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Your bones are surrounded with blood veins that can transport the nutrients necessary to repair your bones if they break relatively quickly. Your teeth lack this surrounding vein structure, so to repair holes on the surface they would need to transport the necessary nutrients through bone. Since bone is too rigid to do this at any perceptible pace, the acid damage from the bacteria will outpace any repair that does happen.",
"Bones are made up, in part, of living tissue. Only living tissue can be regenerated in our body (generically speaking) and, while there is some living tissue in the teeth (the pulp, or center, has blood vessels running through it) the majority of a tooth is non-living. While bones and teeth both contain calcium phosphate, teeth are not actually bone.",
"As a dentist, let me try to explain - the cells that form bones (osteoblasts) remain functional throughout your life. Hence, they can form bone whenever needed. In reality - your bone is not stable, it is constantly being dissolved and formed simultaneously by bone dissolving (osteoclasts) and the bone forming (osteoblasts) cells respectively. About teeth - it consist of 3 layers - outer white enamel, middle yellow dentin and inner pulp. Enamel and dentin are calcified (like bone, but much harder) and enclose the pulp that is a soft tissue containing blood vessels and nerves. When you have a cavity, the bacteria first dissolve enamel, then dentin, finally reaching and infecting the pulp, causing pain. The cells that form enamel (ameloblasts) die after their enamel formation activity has completed (ie - after the tooth has erupted) so enamel cannot be formed again in any case. As for dentin - the cells that form dentin (odontoblasts) remain living, but occupy the inner spaces towards the pulp (they somewhat form an outer lining of the pulp) and only form dentin again when the pulp is in danger/is getting irritated. They don't form dentin if they sense that the pulp doesn't need protection. So when infection reached the pulp - dentin forming cells sense the danger and start forming dentin, but their rate of dentin formation is slow and infection ultimately reaches the pulp and kills the dentin forming cells, further inhibiting dentin formation. Ultimately the pulp is infected and, if not treated, it dies. TL;DR - cells that form amd repair bones remain throughout your life. Cells that form (and can repair) teeth die as soon as their job is complete.",
"Related topic: why are there no vaccines for bacteria that cause tooth decay?",
"Teeth hardly have any cells unlike other bones in the body that do so cannot heal themselves."
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[
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|
ljms65
|
Does using the pill to control periods postpone the onset of menopause? Because you still have your eggs, so don’t they need to “go somewhere”?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"The presence of eggs isn't related to the menopause, menopausal women still have thousands of eggs in storage."
],
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|
ljn407
|
why does junk food taste so....good?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"junk food often contains lots of salt, fats, or sugar. those three, especially sugar, often allow lots of dopamine, which is the satisfaction and happiness chemical, to be released in the body. you of course want to have more satisfaction, so you will want more of that source of satisfaction, which is the junk food you ate.",
"We evolved to crave high energy foods. In the wild, eating every berry you could, or sucking the marrow from bones could very well help you survive the coming winter. Those instincts don’t serve us well in our modern times of abundance, our bodies always want to prepare us for a scarcity that isn’t likely to come.",
"It's literally engineered to taste good. Think apple vs. apple pie. Apple grows on tree, tastes as good as it can. Apple pie engineer is given a task: use ingredients from all over the world (vanilla, cinnamon, butter, flour, sugar, milk, cream, etc.) in any amount you want with any amount of heat or cold (ice cream on your pie, anyone?). All you have to do is make something that tastes way better than an apple by itself. If you don't, your fired, and the next person tries until there is a consistent solution.",
"Flavor enhancers. That's why fruits and vegetables may not taste as good as a fast food chicken because they're just... Fruits and vegetables.",
"It has a lot of calories and evolution has programmed humans to seek out calories since that enhanced our survival chances.",
"Fun fact: if you stop eating junk food (not just a flavor or brand, but an entire category - say, potato chips) they won't necessarily taste very good when you start eating them again. To a great degree, it's an acquired taste.",
"Basically junk food contains a lot of stuff your body wants, just in excess. Things like fat, sugar, salt etc are things your body needs/wants, but just need in small amounts. And because they're relatively rare your body has developed a chemical response system to encourage people to find and eat things that have that stuff in them. The problem is that those substances are not rare anymore, and too much of it is a bad thing. Which is why you actually can eat junk food and still maintain proper diet, so long as you do so sparingly."
],
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|
[
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[
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|
ljnjiy
|
How do these child prodigies become so insanely good at musical instruments at the age of 4-5?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Most kids don't spend 3-4 hours per day tying their shoes, the child prodigies have parents that get the teachers, equipment etc. that enable them to make the leap.",
"Many animals have an 'imprinting' time. To my knowledge, in humans this occurs around the time speech is first refined from gibberish to (run-on) sentences. Many children [are taught multiple languages]( URL_0 ) at this phase. Music in itself is somewhat a language. Granted theres undoubtedly a lot of nurture involved, and probably some degree of aptitude.",
"They’re exposed to the instrument, then they develop an interest in learning the instrument, and they practice constantly. Alternatively, some children are “strongly encouraged” by their parents to excel at certain things. Every so often, these criteria connect with a child who has a natural gift for the craft, and the rest is history."
],
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17,
11,
7
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"text_urls": [
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[
"https://www.rbth.com/science_and_tech/2016/10/28/4-year-old-russian-girl-speaks-7-languages-how-did-she-do-this_642979"
],
[]
]
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|
[
"url"
] |
[
"url"
] |
|
ljnjke
|
How does an epidemic such as Ebola in Guinea disappear, but reappear by itself 6 years later when it was considered eradicated?
|
Biology
|
explainlikeimfive
|
{
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"gne5x00",
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"text": [
"Ebola also infects other primates, so could have been present in the wild population and then jumped back to humans.",
"You have the timing a bit wrong. The last reported case in West Africa was just over a year before the first reported case in Congo. And even though that looked like an isolated event there have been other isolated outbreaks of Ebola in Congo after it. The big mystery is not the time as there could have been many untraced cases of Ebola, dormant samples on items or animal infections. The big mystery is the distance as Congo is half a continent away from Guinea.",
"Just because there hasn't been an active case in humans does not mean the Ebola did not exist there. It is transmitted asymptomatic of any symptoms in 20%-25% of spread. It is passed on via close direct physical contact with blood, vomit and feces being most common but has also been found in urine, semen, and even breast milk. In theory a traveler from an area with an infection can pass it via sex 6 years after the last previous known infection."
],
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14,
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4
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|
[
"url"
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[
"url"
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|
ljnrc1
|
what is mathematics?
|
I take no credit for this question - saw a thread on Twitter that started with the question: If a child asked you, “what is mathematics?”, how would you answer? Just thought it was such an interesting discussion that it would be great to ask here!
|
Mathematics
|
explainlikeimfive
|
{
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],
"text": [
"Mathematics is logic. It's how you can figure out things if you know other things. If I know Susie had 3 apples and she ate one then I can use mathematics to know that she has 2 left. Also if I know the sky is either blue or grey and it's not blue then it must be grey. It's not just numbers.",
"My view: Mathematics is about trying to find out what unexpected consequences a set of rules has. The best way is probably to contrast this to some things. If we compare to other sciences like chemistry or biology, they are trying to find the rules based on which our world works. No-one knows the rules in full, which makes what they do different from mathematics. However, people have figured out incomplete parts of the rules, and they can use mathematics as a tool on those incomplete parts to try to further their understanding. Another interesting contrast is to other things which deal with rules, like for example law. Probably the biggest difference is that lawyers deal with rules that have grey area. There are many different shades of red and orange, and between them is probably a shade that you wouldn't be quite sure whether it is red or orange. But it wouldn't sound out of place if a law used a word like \"red\" or \"orange\". Mathematics, on the other hand, requires that the rules you deal with have no grey area. What this has to do with numbers, and the kind of things you're usually taught in \"math class\" in school: numbers, and their addition, subtraction, division, etc. is one of the most useful rulesets of mathematics, both in terms of applying to the real world, but also for understanding other rulesets within mathematics. That's why so much attention is placed on that single ruleset when teaching math. But it's of course not the only ruleset; for example geometry is another ruleset one might study, and mathematical logic would be another one."
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4
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|
[
"url"
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[
"url"
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ljoaze
|
what is the connection between inflation and interest rates?
|
Economics
|
explainlikeimfive
|
{
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],
"text": [
"Low interest rates make it cheaper to borrow, therefore increasing spending and demand. As demand goes up, so do prices, what we call inflation. In order to slow inflation, demand needs to be reduced. By increasing interest rates, it becomes more expensive to borrow, and therefore more expensive to buy things. Since, with higher rates, more of your income is going to debt service, as well as making larger purchases more expensive, demand goes down. This allows for price appreciation to slow, or sometimes even reverse.",
"Inflation is simply when the prices of goods and services are increasing every year. One of the uses of interest rates is that it encourages or disencourages spending on goods and services. How does it do that?. Well if interest rates are low (during recessions), people see no need to keep money in savings accounts (as there is barely any return on the money), additionally people also take loans (as the repayments are very small). These factors increase the amount of spending that occurs in an economy. When more spending occurs, demand has increased in an economy. When demand increases, the prices of goods and services also increase. When prices of goods and services increase , inflation occurs or inflation increases. Essentially, +interest rates = -inflation, while -interest rates= +inflation. Hope this helps, from a 2nd year bachelor of Commerce student"
],
"score": [
4,
3
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|
[
"url"
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[
"url"
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|
ljpc9f
|
What does “sensitive teeth” toothpaste actually do to your teeth? Like how does it work?
|
Very curious as I was doing some toothpaste shopping. I’ve recently started having sensitive teeth and would like to know if it works and how. Thank you
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Desensitizing toothpaste has [Saltpeter AKA Potassium Nitrate]( URL_0 ) or a similar chemical compound that fills and blocks the microscopic pores in your teeth that allow cold or hot liquids to penetrate into your teeth where the nerves are.",
"If you look at your teeth under a microscope, especially the root surface, it’s like looking at a windowscreen. Lots of little holes, or “tubules”. Sensitive teeth toothpaste has an ingredient that seals the tubules so nothing can go through them and hit the nerve of the tooth. It’s like clear coat nail polish, it seals everything up. However, the best way to use sensitivity paste is to put it on your finger and directly apply it to the sensitive areas and let it sit there as long as you can. Like an ointment. Much more efficacious than simply brushing with it once or twice a day. Most sensitivity toothpastes work very well for sensitivity, but are not great for actually cleaning your teeth. They start working about two weeks after daily use, and will stop working when you stop using it.",
"The nerve cells in our teeth transmit pain signals *electrochemically*. Normally, when there's no pain, the nerve cells maintain a slight negative voltage potential (-70 mV) between the inside of cell vs. the outside of the cell. They do so by regulating the flow of Potassium (K+) and Sodium (Na+) ions. When nerve cells want to signal \"pain\", they let excess the Potassium ions (K+) inside the cells to flow out (and conversely, let excess Na+ ions outside the cells to flow in). This \"de-polarizes\" the nerve cell and we feel \"ouch!\" Sensitive-teeth toothpaste basically work by flooding the outside of the nerves with K+ ions, from its active ingredient Potassium Nitrate. This stops the \"pain signaling\" from working. The abundance of K+ ions outside the nerve cells stops the K+ ions inside the cells from flowing out. So the nerve cells can't \"de-polarize\" and the \"pain signal\" can't be transmitted. No signal, no pain.",
"If you live in countries outside the USA, you can buy toothpaste that contains a type of bio-glass that will fill in the holes in your teeth. Originally designed to repair shattered bones of soldiers, it was adopted for use in toothpaste. Once the holes are filled in, cold/hot liquids cannot pass into your tooth and irritate the nerve inside. I have no idea why you cannot buy these toothpastes in the USA. You can order them online from Canadian resellers. Theories range from FDA blocking it's use in toothpaste to a conspiracy by the Dental Association.",
"The active ingredient, potassium nitrate, over time absorbs into the dentinal tubules reaching the nerve and overloading the synapses with potassium. The increase in potassium overloads the Na/K pumps and decreases the total number of transmissions.",
"Others have explained how it works. I'm just gonna confirm that it (Sensodyne) does work, at least for me. My tooth sensitivity went away immediately, literally after the first time using it, and it's never come back. I wish I got paid by them, for everyone wondering if I am an ad. But alas; I'm not.",
"Wow an ELI5 I can actually help with. There are two ways toothpastes help with sensitivity. Occlusion (blocking) of the dentin tubules or desensitization of the pupal nerve. ELI5: You feel pain when a button is pushed. Someone has to run down a tunnel to press the button. Usually there is a door (enamel) but sometimes the door is broken or worn down, so someone keeps running in and pressing the button. Your teeth has a bunch of buttons inside them. What toothpaste 1 does: Occlusion/blocking. Every time you brush you put a brick down. As time goes by the place where the door would be is covered by a brick wall. No one and run down the tunnel and press the button. What toothpaste 2 does: desensitization Every time you brush you mess with the button a bit. As time goes by the button stops working. So when someone runs down the tunnel and presses the button, nothing happens. Of course there are different actives, different properties, but if you have more questions I can answer them in the comments.",
"Apparently it actually deadens the nerve endings so you dont feel the pain. In most cases the pain is due to the sensitive area under your gumline being exposed due to your gums receding or channels, exposed areas caused by tooth decay. This kind of toothpaste gets in there and mildy deadens the nerves.",
"Posts like this are why it's sometimes better to ask reddit than google. Look at the awesome answers in here.",
"Depends on the country. Novamin toothpaste creates a layer of bio-glass on your teeth that fill the holes in the enamel. Glaxo smith kline bought the patent rights and then removed it from the american market. You can still buy it in india and europe.",
"In countries other than the USA the toothpaste has a mineral in it that temporarily fills in the little holes the dentin; [ URL_0 ]( URL_0 ) In the USA you get potassium nitrate, which de-sensitizes the nerves, it isn't nearly as effective.",
"Dentist here. Lots of slightly correct info here. Can’t grow enamel back. Physiologically impossible as Ameloblasts which form enamel are killed off by time tooth erupts. What you’re thinking of is called remineralization. Novamin and fluoride remineralize enamel not regrow. It’s very hard to explain this in lay terminology so saying “it regrows” enamel is used. Can’t regrow a tissue with no active cells and no blood suppl*. *Dentin can regrow because you have odontoblasts living in the pulp of the tooth and have blood supply. Regarding the OPs question. Two types of desensitizing ingredients. Potassium Nitrate which reduces the nerves ability to transmit pain signal. And Stannous fluoride which occluded Dentin tubules. Occluding tubules works Bc the current widely accepted theory on how signals are transmitted through dentin is called hydrodynamic theory. Fluid in tubules transmits signals to the nerve in pulp. If block the tubules. You block fluid flow. This no sensitivity. I nice explain like I’m a dentist. But clearing up some things I’ve seen.",
"I was having sensitivity with my teeth a few months back, so my friend suggested sensitive toothpaste. I went ahead and used some for a few weeks and my mouth was then super sore with ulcers. Turns out I’m allergic to sensitive toothpaste. So I switched back. Lmao"
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[
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[
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ljpeyl
|
Why does your arm hurt at the injection site after a shot?
|
I just got my first round of the moderna vaccine. I know that injection site pain is common, I am not asking about moderna specifically. What I want to know and can’t find an answer to is why it hurts? Is it lactic acid pain or is it another reason? Thank you in advance!
|
Biology
|
explainlikeimfive
|
{
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"text": [
"This is because of inflammation caused by the needle. In addition, it's because your body is sending antibodies there which it reacts to.",
"Many vaccines contain an adjuvant. This is a substance designed specifically to irritate tissue. The irritation causes an outsized immune response to the site of the injection thereby increasing the effectiveness of that vaccine. This means that vaccine makers can reduce the amount of vaccine specific material in the shot and still get the same degree of immunity. It also helps people like the elderly who have a reduced immune response in general. Long story short, a sore arm is a feature not a bug.",
"The general idea of a vaccine is to trigger an immune response against a part of a whole virus that cant hurt you. So you train the immune system so it can handle the real virus and protect you. So what you feel is the result of the immune system responding to the vaccine. The second injection can have higher side effects because your immune system is then \"trained\" and can respond more forcefully. Flu-like symptoms for a few days are not uncommon because the symptoms of the flu are in large part because of your immune response. So look at it as the body training and getting prepared for any real virus infection a bit like how muscles hurt after physical exercise. The side effect depends on the person, it has not been shown that the effectiveness of the vaccine depends on your reaction to the vaccine."
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[
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[
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ljql9w
|
Why does infrared light from remotes only work on the TV it’s assigned to?
|
Technology
|
explainlikeimfive
|
{
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"text": [
"The infrared light isn't just like a flashlight, it is blinking specific codes to tell the television what to do. Those specific sequences of blinks are different for different manufacturers so the remotes are not interchangeable. There do exist universal remotes which can change their blink behavior to emulate a variety of different manufacturer codes.",
"They don't.. IR remotes from one model of TV can be used on any TV off the same model. If two of the same model of TV are next to each other, both TVs will act on the commands from the remote at the same time. IR remote controls send a series of flashes of IR light. TV's are constantly looking for flashes of IR light, but only act when the flashes of light they detect are exactly what they are looking for. It might be easier to imagine these flashes of light as beats of a drum. And TV's are listening for their favorite drum beat. All TV's of a certain model are listening for the same beats and so they will all act the same when they hear it. Different manufacturers teach their TV's to listen to different beats so they don't respond to other manufacturer's remote controls. Universal remote controls know the favorite beats of most manufacturers and that is why they will work with most TV's.",
"Remotes for any particular model will generally work for all devices of that model. A few rare products have a small A/B switch inside the remote and also on the devices so that you can buy two devices and have a different remote for each. Otherwise each remote controls both devices. Remotes are somewhat directional so you can limit this issue by carefully pointing them, providing the devices aren't too close together."
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3
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|
[
"url"
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[
"url"
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|
ljs5u6
|
Why do strongmen tend to have more body fat and less toned muscles?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"Because there is no incentive for them to have low body fat. It’s easier to build and maintain muscle mass on a calorie surplus.",
"Please note we are about to talk about the extremes of what the human body can do. We are not talking about *average* humans. This is important to understanding why the difference exists. In order to get to the extreme end of human strength, the body needs a large amount of things in its diet. It needs very large amounts of protein, fats, and salts to build this strength. In order to have very defined muscles you have to have low body fat and low water content. In short, to be strong you have to eat *a lot*, to be ripped you have to eat very little. Certainly you can be ripped AND be stronger than most people. But you can't be ripped and compete at world strongman competitions.",
"High level strongman isn't a weight class sport. They're basically all 300+ lbs, or even 400+ lbs. They can add more absolute muscle mass and total strength if their bodyfat is higher. This can come at a cost for more endurance type events (like truck/plane pulls, carrying events, etc), so they can't just bloat up to 500+ lbs. Other sports that are more weight class oriented, like powerlifting and weightlifting, will have leaner athletes. Guys that < 220 lbs in those sports are pretty damn lean and jacked.",
"Because a 'toned' muscle is just a big one that isn't covered up by fat. If you want to get big & strong you have to lift and eat a lot. Whether your goal is pure size or strength your overall workout and diet plan will be lots of lifting and lots of eating. Bodybuilders are concerned with how they look physically and how they can best show off their physique in a visually based competition. Strongmen are focused on lifting bigger weights, they don't usually care about limiting fat or cutting in order to present themselves a certain way; they seek to build mass purely for strength, in a way that would be undermined by the caloric precision and cutting techniques bodybuilders frequently use.",
"You need fuel to lift heavy things. For fuel you need to eat. The more toned you are, the (safe to assume) less you’re fueling your body to make strength gains. To get stronger, you have to eat more. This is why typically you see lifters go through what’s called a “cycle” of bulking and cutting. You “bulk” to build muscle and strength, gaining weight in the process. You “cut” by taking in less calories and toning up, (typically) losing weight and strength in the process, but have a better means of showing off those newly gaining muscles. Think of strongmen and bodybuilders as the epitome of both these ideas, on opposite ends.",
"Funny thing about competing body builders. The competition isn't about strength, but muscle size and symmetry. The week before a competition, contestants will literally dehydrate themselves in order to show off their muscles best. They're at their physical weakest at this time. Actual strong man competitions aren't about esthetics.",
"Sports like bodybuilding are geared toward optimal physical appearance, which is obtained by training and dieting in such a way that optimizes muscle size and proportion and reduces body fat to an extremely low percentage to highlight every last detail of the muscles for a show or competition. The amount of weight the person has to lift in order to get to that point doesn't really matter. (Well, it's a lot of weight to be sure, but they aren't judged on it.) Sports like powerlifting and Strongman are basically the opposite. Appearance isn't a factor, only raw strength in order to lift the maximum amount of weight. These people are eating to develop maximum muscle performance to lift a many pounds as possible and never need to diet to reduce body fat.",
"Because you are not your strongest when super lean. There's no weight limit in strongman sports.",
"Strongmen focus on getting strong. To gain muscle you need to eat a TON. If you're thinking about those that are body builders how they're huge, yet extremely lean. They also need to eat a TON, but the difference is that they cut back on their calories just before competition to cut down on the fat, while additionally dehydrating to be super lean. Strongmen focus = getting strong. Need calories to gain that strength."
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[
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[
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|
ljscbw
|
Why do we pickup bad habits so quick when compared to Good habits?
|
Other
|
explainlikeimfive
|
{
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],
"text": [
"Bad habits are usually pleasurable things so we do them without thinking about it and get used to doing them. Good habits are things that have a delayed gratification so the task itself is not pleasurable. You've got to do it even though it isn't fun to get the reward. You have to think about it and make time for it to get used to doing it and getting the reward. Bad habits come with their own reward right away."
],
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12
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|
[
"url"
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[
"url"
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|
ljssyy
|
Is self confidence related to testosterone and chemicals in the brain?
|
Other
|
explainlikeimfive
|
{
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"text": [
"At some level, everything is a chemical but testosterone alone doesn’t create self-confidence and it’s primary jobs aren’t in the brain. A lack of testosterone can make males feel less energetic but that’s a medical condition. A normal, healthy male wouldn’t benefit (and would probably experience side-effects) from testosterone supplements. You develop self-confidence over time by setting goals and working towards them. They don’t have to be big goals or anything. But maybe something like, “I want to run a 10k race.” or “I want to learn to cook Thai food.” Hobbies tend to lead to expertise (and confidence) and/or meeting people with shared interests.",
"I would say it's mainly related to GABA, Serotonin, Dopamine, Noradrenalin and Glutamate levels. Mainly because Alcohol and similar drugs has effects on these chemicals in the brain, causing increased self confidence. Low amounts of these chemicals can cause depression, anxiety etc, so I'd guess that increased self confidence has more to do with higher concentrations of said chemicals in the brain."
],
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6,
5
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|
[
"url"
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[
"url"
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|
ljukoa
|
Speed causes time dilation. Mass causes time dilation. What is the link between speed and mass which means that they both cause the same phenomenon?
|
I hope the title makes sense.
|
Physics
|
explainlikeimfive
|
{
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],
"text": [
"To try to make this very simple, space and time are both components of a single thing called, very logically, spacetime. Spacetime is a coordinate system consisting of three spatial directions and one temporal direction. Time dilation is a result of the way things move through spacetime. Both speed and gravity are related to the way things move through spacetime, which is why they both cause time dilation. For speed, again, in a very simplified way, you can conceive of everything moving at a combined “velocity” of c (“the speed of light”) through spacetime. Thus the faster you are traveling through space, the slower you are traveling through time, and vice versa. Gravity, by contrast, is the warping of spacetime by mass/energy. Just as it warps the path that objects take when traveling through space, this warping also affects the path they travel through time. The mechanics are different, and the end result is also different (time dilation due to velocity in special relativity is reciprocal. Gravitational time dilation in general relativity is not), but the common thread is the interaction with spacetime.",
"Thanks for all the replies. Unfortunately I got called into work so have only been able to skim read. From what I can tell I think it's something I don't have the brain capacity to understand. I'll get some sleep and try and digest the information.",
"Think of it this way. You are always accelerating toward the center of the earth even if the surface of the earth is preventing you from falling any further. You are in an accelerating frame of reference to the center-mass of the earth. That is what gravity is in super-basic terms. If you can get your ahead around that fact, then you are one step closer to understanding. Now imagine a person being held perfectly still 1000 miles above a precise point on the surface of the earth. They would experience a weaker gravitational effect than the person standing on the surface. So in a sense, they would have a slower acceleration than a person standing on its surface. If that all makes sense, then it should stand to reason that a person in lesser gravity (slower accelerating frame of reference), would experience a time dilation effect when compared to a person in greater gravity (faster accelerating frame of reference). \\*EDIT Added some missing words"
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|
[
"url"
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[
"url"
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ljurye
|
Why do people weigh less in the morning than they did the night before when they went to bed?
|
I’ve talked to a few people about this and the consensus seems to be that if you weigh yourself at night, then you will weigh less in the morning. Where does this shedded weight go?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
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],
"text": [
"You burn calories in your sleep, breathing, and sometimes sweat. You’re losing weight via water loss and respiration. If you weigh yourself after you pee in the morning, that helps too.",
"I get up to pee like three times a night. Loss of water weight?",
"Water weight. There are lots of things your body uses water for. During the day water gets replenished by things we eat and drink. At night it generally doesn’t get replenished for 6-8 hours even though your body is still using it."
],
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3,
3
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|
[
"url"
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[
"url"
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ljv1lc
|
How does the brain physically store memories?
|
Does the size related to how good or how much you can store memories at all? Can you physically make them stronger?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gngff15",
"gnh2sn2"
],
"text": [
"The current thought is that neural pathways are strengthened by repeated exposure to stimulus. The exposure can be external such as an experience, or it can be internal, such as obsessing about something inside your head (rehashing a traumatic memory in your head or even repeating something to yourself to memorize it)",
"While there are more parts to a neuron than just these three, the main components are Axons, Dendrites, and the Nucleus. The nucleus is the \"traffic cop\" that uses neurotransmitters to route signals. The axons are the main streets. The dendrites are all of the short cuts that get connected to the axons. The human brain is always creating new dendrites, which connect to other axons. Memories are formed when dendrites connect to axons. This is called neural plasticity. (Google worthy term for you.) The more plasticity your brain has, the more you are able to store by the dendrites connecting to axons. This degrades over time, reaching it's peak (for most people) in their mid- to late- twenties. This is also why memories fade (for most people) over time. The brain is in constant flux with Ds connecting to As where sometimes a memory will be \"over-written\". I had a rotten childhood and I am constantly trying to over-write childhood trauma by always learning new things. ;) Also remember, neurons do not fix themselves or regenerate like other cells."
],
"score": [
10,
4
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
ljvkhw
|
What determines whether a winter storm will be snow, ice, sleet etc. ?
|
Earth Science
|
explainlikeimfive
|
{
"a_id": [
"gnglegs"
],
"text": [
"It depends on the elevation where you find 32F (or 0C). The National Weather Service tweeted about this a couple days ago: URL_0"
],
"score": [
4
],
"text_urls": [
[
"https://twitter.com/NWS/status/1359927933482237965?s=19"
]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljvq0i
|
When people are on the news or a podcast how do the microphones not pick up the other persons voice if they are co hosts for example and right next to each other
|
Technology
|
explainlikeimfive
|
{
"a_id": [
"gngkv13",
"gnglbup"
],
"text": [
"There are many different types of microphones that are designed to have their own way of picking up sound called polar patterns. Some microphones have a focused point so it only picks up the source directly in front of the microphone. These are called cardioid microphones. Some of them are designed for the whole room called omnidirectional.",
"* On the news, the other mics do pick up the other people. * But an audio engineer in the control room has an audio console that has a fader and mute button for each mic. * Since they also can see the teleprompter and have reviewed the script, they have a good idea of who is going to be talking and when they are going to switch. * So they can very quickly switch which mic is being routed to the broadcast. * As for podcasts, they mics they use are very directional and don't pick up a lot of noise that isn't coming from directly in front of them. * Also podcasts are heavily edited before they are published and the audio is cleaned up. * But when two people are talking at the same time there is just a certain amount of \"mic bleed\" that occurs."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljvqaq
|
What does the "Don't tread on me" snake flag mean?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gngpxwm"
],
"text": [
"Side note, I saw a version of that flag that said \"Tread on me daddy\" that I thought was pretty funny."
],
"score": [
4
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljvudp
|
the difference between computer monitors and TVs, and why you don’t want to use a TV as your monitor
|
Technology
|
explainlikeimfive
|
{
"a_id": [
"gngly18",
"gngjwsl",
"gngkccs"
],
"text": [
"In the old days (up to 2005ish) TVs and computer monitors were generally very dissimilar -- they used different inputs (RCA jacks for TV; VGA & DVI for monitors), and monitors generally supported higher resolutions & color depths. With the advent of HDMI, digital signals, and near-universal adoption of widescreen 16:9, the lines have gotten blurry. Net, if you have an HDTV that you can connect to your computer, and you like the picture -- great! No reason not to use it. And the converse is true. Got a big computer monitor? No reason why you can't stick a roku in it and use it as a 'TV' Everything the other posters here have mentioned about refresh rate and latency is valid -- but OP isn't necessarily looking to game at 4k and 144hz. If you just need some more real estate to keep email (or slack/discord/twitch/etc) open while you work, no reason why a cheap TV can't help.",
"Pixels per inch. Let's take two screens at 1920x1080 resolution. 20\" Monitor at this resolution is 110 Pixels per inch. But, a 35\" inch TV would be 62 pixels per inch. So, while you can technically use a TV as a monitor, details will be much lower. Also, the refresh rate (how many times per second the screen can put out a new image) can be very different (the TV would be slower).",
"Mainly input delay. Monitors are made to have a low input delay whereas with TVs it's not so important."
],
"score": [
19,
10,
4
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljvzw2
|
what's the default mode network (DMN) and what is it good for?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gngperq"
],
"text": [
"It's a part of your brain that's active when you're not actively thinking about anything (that's why it's called \"default mode\"). It consists of multiple regions in the brain (that's why it's called a \"network\"), including hippocampus and a few parts of the brain cortex. The fact that it's active when you're not actively thinking about anything doesn't mean that it doesn't do any important job. Quite the opposite actually. It's the part of your brain responsible for empathy, guessing what other people are thinking (a.k.a. the theory of mind), creating future scenarios, and also forming long term memories (the main job of the hippocampus). As I mentioned, one of the tasks of the DMN is imagining future scenarios, which means that it's the DMN that's active when you're daydreaming. When you instead focus on some external task, the DMN activity reduces."
],
"score": [
8
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljw7z8
|
What does ”if you’re not paying, the product is you” mean?
|
Context: saw this on Twitter (@ econinbricks) as a part of the poem ”roses are red, violets are blue, if you’re not paying, the product is you.” Any examples, and is this a controversial saying or a fact?
|
Economics
|
explainlikeimfive
|
{
"a_id": [
"gnglpn3",
"gngm1eu",
"gnglwjp",
"gngoi51",
"gnglylo"
],
"text": [
"This is a as pretty well regarded view. It means if the service you are using is not paid for, then it means they are selling your personal information and behaviors to other companies for profit. Aka, they are selling your data, you are the product.",
"Facebook is *free*, we are what's being sold. Our habits, location, shopping, conversations, likes, wants, searches. Basically, unless you pay someone for a service, they are taking something of value back, what they are taking may not be of value to you, but it's of value to someone somewhere.",
"* It's easy to think the users on a service like Facebook are the customers but in truth advertisers are the real customers. * And the things the advertisers are buying from Facebook is data about the user. * So the idea is, if there is a service that you use for free, the company hosting the service is likely selling information about how you use the service to someone else in order to pay for the cost providing the service and also to make some profit. * An example, by the way, is a situation the leads some people to think Facebook is listening to them. * Facebook knows a *ton* about you and the people in your social/family circles. * Lets say for example your wife's mother is coming to town in a few weeks and when she's going to be there it will be her birthday. * You have a conversation with your wife about what things the three of you can do white she's here and you wife mentions how her mother was talking about wanting a new pair of hiking shoes. * Fast foward to when your mother-in-law is in town and now you are seeing ads for hiking boots everywhere. * Facebook must have been listening right? * Nope. * But your mother-in-law did start googling hiking boots while she also had Facebook open. * And then she traveled to your physical location. * So now Facebook knows she's near you, that she wants hiking boots, that it's her birthday, and that you're married to her daughter. * It's not a stretch to think you might buy them for her and so advertisers are hitting you with hiking boot ads.",
"It’s a more cynical rendition of “there’s no such thing as a free lunch”, and while broadly correct it loses some accuracy over the traditional more general phrase in favor of cynicism. Companies that engage with you do so because engaging with you makes them money. It could be because they sell your data to a third party (Like Facebook allegedly), they could use your engagement to increase their value for deals with other companies (Firefox), they could use you data to help other money making ventures of theirs (Google Photos), or they could provide a free service to encourage you to use their paid version (GitHub). But the rub is, being “the product” is really vague beyond the general grossness of how it sounds. You are “the product” for invasive internet ads, but you’re also “the product” for over-the-air TV and radio ads when they know next to nothing about you, and potentially have no idea if you even exist. There’s just no such thing as a free lunch.",
"It means if you are using a service that is free you are the “product”. For example Facebook is free but then they sell your information to people looking to sell you products. I hope this helps"
],
"score": [
18,
15,
6,
4,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
ljxs34
|
Why do we need pillows? Do other species have similar things as well, or are they mainly a human thing?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnh1unb",
"gngv3r9",
"gnh362f",
"gnhhwg8",
"gnh2uow",
"gnhrl98",
"gni3rqe"
],
"text": [
"Baby giraffes will use their butt as pillows. I've seen dogs and cats use each other as pillows",
"Several ape species construct sleeping nests out of vegetation URL_0 This may not answer the first question, but hopefully it answers the second.",
"We don't need 99% of the things we currently have in order to survive, they just make our lives easier and help us not injure ourselves in our day to day lives uneasy that might contribute to the degradation of our quality of life.",
"I think that most of this is just due to what your used to. There are plenty of places in the world where most people will sleep on a flat hard service and prefer it to western style beds That being said, it’s possible that our “default” sleeping arrangement (that evolution had a bit time to begin to optimize for) is sleeping in large piles with our peers and cuddling for a lot of different for a lot of different reasons(peer bonding, warmth etc) and a soft platform with blankets and pillows might just be sort of close to that expirence That might be complete bullshit though pretty much everything about our behavior is dictated by culture and it’s almost impossible to figure out any sort of default for human behavior",
"Comfortable bedding helps you get a better sleep, and better sleep means a deeper sleep and more REM sleep. This translates to better brain development. For wild animals where too deep of a sleep might be detrimental, e.g. due to attackers, then a too comfortable sleep would actually be detrimental to their survival. They may need to wake up alert and ready to fight or flight, not groggy and thinking about the dream they just had. So it's not that we *need* pillows. It's that pillows help us get a deeper sleep, and we've evolved to a point (as a society/species) where a deeper sleep is an advantage.",
"We don't need them, we just often find them more comfortable. There is some evidence that pillows have actually been bad for us causing our spines to hunch forward from the less natural bending of the neck that comes from the pillows raising our heads compared to laying flat.",
"Further question; babies dont sleep with pillows, why do we at some point transition to needing/wanting one?"
],
"score": [
54,
38,
37,
14,
13,
6,
3
],
"text_urls": [
[],
[
"https://en.m.wikipedia.org/wiki/Nest-building_in_primates"
],
[],
[],
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljyah9
|
What's exactly happening when your eyes get "blinded" temporarily by a bright light?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gngy0bu",
"gnh2kgc"
],
"text": [
"Your eyes work by proteins called photopsin changing shape by light. When your eyes get overwhelmed with light, all of the photopsin changes in shape and your vision goes white. During this time your iris will also be expanding to contract your pupil in order to reduce the amount of light taken in. Both of these processes take some amount of time to occur which is the time you spend dazed.",
"The eyes contain proteins known as opsins, which contain vitamin A derivatives known as retinal. Upon exposure to the appropriate wavelength light, these chemicals change their shape, and disassociate from the opsins. This dissociation begins a chain of events that sends a electrical signals to the brain, which is interpreted as visual stimuli. Now, after the dissociation, specific enzymes are responsible for putting retinal back into the opsins. If you shine a bright light into the eyes, a lot of retinal disassociates. To 're-associate' all or most the retinal with opsins, a long time is required. No retinal in opsins means no new visual stimuli can be sent to the brain, resulting in temporary blindness."
],
"score": [
10,
3
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljyr9j
|
Why does the human brain contain such a high amount of fat, making it the fattest organ in human body?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnh0l7d",
"gnh6tl8"
],
"text": [
"Mostly because of its function. It isn’t a muscle nor much of a manufacturing organ. The cells mostly just have lots and lots of surface area. Neurons have lots of little fingers. The supporting cells coat the neurons. So the dominant cell material is cell membrane. That’s made of fat.",
"Nerves cells in the body are insulated by a layer of fat called myelin that helps the signals travel faster. Brain has the highest concentration of neurons and thus has a lot of myelin."
],
"score": [
14,
8
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljz5wj
|
Since food gives you energy, why do you need sleep?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnh2or9",
"gnh956r"
],
"text": [
"Sleep helps our body rest and repair itself. When we sleep, our body is better able to repair the small bits of wear and tear we get from all the activity we do each day. If we don't sleep, our brains stop working as well, and eventually, we can die. Sleep isn't about energy, it's about repairing the body.",
"This is an important and not fully understood question. Spending 1/3rd of your life asleep is a huge cost, so it must be worth something. A couple things: 1. When calories are available but limited, sleep reduces daily calorie use. It may be an adaptation to conserve fuel. 2. Sleep is used to repair your whole body - a ton of structural work is done when you sleep, and people who don’t sleep have systemic damage throughout their body. Inflammation, damaged organs, etc. 3. Sleep is critical for your brain to work. Your brain incurs metabolic damage when working and it must be cleared. Sleep comes with a ‘wash cycle’ for your brain to cleans out debris and keeps everything working. Not enough sleep, you get gunked up and your brain falls apart (sometimes irreparably). 4. Sleep is critical for your brain to move memories from short term storage to long term storage, link them together and assign triggers and links between them. Think of it like driving a race car. Food is gas. No food, no racing. Sleep is like new tires, new engine parts, new brake pads and other maintenance and a competent driver. Without that maintenance your car starts to break and your driver crashes."
],
"score": [
7,
5
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
ljzcgt
|
why do people get more satisfied/happier getting their "wants" instead of "needs"
|
Why is it that even though "needs" are what help us to stay alive and get through everyday, getting "unnecessary" things usually makes us much more excited/happy/more satisfied when we know those are things that aren't going to help us daily. Wouldn't it not make more sense that the brain is wired the other way to ensure survival?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnhph5v",
"gnh6153"
],
"text": [
"Not actually an answer, but a quote came to mind when I saw your question! On his book on politics, Aristotle says something like \"It is for the superfluous, not for the necessary, that the great crimes are committed\". So I guess you have at least one big philosopher backing your question! P. S.: I freely translated this quote from a Brazilian edition, which is in itself a bad translation, but I think the heart of the quote is right",
"My best answer would be this: Humans thrive in families and need social connection. If we have needs that have to be met, our emotional side could actually help us to survive when we can’t get our needs met by ourselves. Instead, we seek out others from the group and in compassion, they give us what we need. This way not only are our needs met, but we also get a boost of those feel good hormones. Also worthy to check out this study (although it’s a monkey study and that’s not cool it’s findings are pretty interesting nonetheless) URL_0"
],
"score": [
4,
4
],
"text_urls": [
[],
[
"https://www.psychologynoteshq.com/harlows-monkey-experiment/"
]
]
}
|
[
"url"
] |
[
"url"
] |
lk0yo2
|
How do firemen determine where and how a fire started?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnhdaon"
],
"text": [
"As long as something hasn’t burnt completely to ash you can get a lot of clues by looking at the remnants. What has burned and to what degree and in what patterns can tell you a lot about the temperature and timing of the fire in different locations, which tells you things about how it spread and what was burning. It’s also possible to find remnants of any accelerant like gasoline that didn’t completely burn away, or even based on the composition of what is left behind afterward, since different substances leave behind different things. As with basically anything, the aftermath can tell you a lot about how things got that way if you know what you are looking at."
],
"score": [
4
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk18sm
|
why Western movies are considered their own genre. ("The Good, the Bad and the Ugly" as a past example, "News of the World" as a present example)
|
I understand some movies set in the Wild West are classic, but I don't understand why they're considered their own genre of movie. Why are they classified in their own genre instead of saying "The Good, the Bad and the Ugly" is an action movie set in the Wild West? Obviously I'm not a movie expert, but I keep hearing the Western term as a genre tossed around to this day. I don't quite get why movies set in the Wild West need their own genre.
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnhg2dx",
"gnhftmz",
"gnhgpan"
],
"text": [
"Probably because of the sheer amount of western movies that ranged from actions to comedies to romances over the years. I mean John Wayne made 83 of them alone. Nevermind Tom Mix, Robert Redford, Clint Eastwood, the list goes on. It eventually reaches a point where there are so many movies that share one common trait (in this case, being based in the “Wild West”) that you just have to make it it’s own genre for it to make sense. Like Slasher films becoming a sub-genre of horror when originally they were just considered horror movies.",
"Because there were a LOT of them [I believe the peak was the 1950s] because they were cheap and easy to make and very popular. URL_0 More generally, genre can refer an abstract concept like comedy, drama, or romance. However, it can also refer to the setting of the work: fantasy world, medieval, Victorian England, sci-fi. Westerns [especially classic Westerns] blur the line because it refers to both the setting to the style. Westerns had a specific style and formula that was popular [again 1950s especially] and pretty rigid. This is why space-western became a thing [Firefly, Westworld, etc]. They merged the style of the classical western into the sci-fi setting of space.",
"They are action movies sed in the old west in most cases. But because of the setting, the story that works will have some part that is quite different to a film set contemporary to the production of the movie. If you look back action movies of the types you see a lot of in the 1980 and later emerged in the 1970 with maverick police like in Dirty Harry (1971) and as Hong Kong Kung fu films. The first movies you would call action films from 1920-30 were set in the wild west or older times with swashbuckler with pirates or medieval time. The contemporary action movie like we know it today was not exactly a thing back then. So western as a movie genre is older than the general action movie. As for movies Westen are quite similar in the story to Japanese Samurai movies. A Fistful of Dollars is many ways a remake of the samurai move Yojimbo. It is the first in the Dollars Trilogy with For a Few Dollars More and The Good, the Bad and the Ugly. Name and grouping exist in large part because they are useful. You could all the common superhero movies today for action movies but a more specific group tells you more about them."
],
"score": [
5,
3,
3
],
"text_urls": [
[],
[
"https://en.wikipedia.org/wiki/Lists_of_Western_films"
],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk1hye
|
Why do egg whites go from clear to opaque when heated?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnhfz80",
"gnifbwp"
],
"text": [
"The molecules of the egg have been *denatured,* meaning the physical shape of the molecule has been changed by the heat. This new shape gives the substance (in this case, egg white) different properties than what it had before: higher opacity, lower viscosity and the like.",
"The eggs when white raw form have their molecules in a linear form, think of those molecules as spaghetti as they are able to freely move around as eggs white do which is why they are liquid and clear. When we apply heat to the egg whites it's molecules which are a single spaghetti strands react with each other creating a web or a network (crosslinking). The same free flowing spaghetti cannot move now as it is now an entangled web. So, raw egg white is a thread/yarn and the cooked egg white is a fabric. Expanding on above the clear looking egg white is clear because light is passing through it without being scattered but with egg white being in cooked / crosslinked form the light scatters when it it passes through the entangled mess of cooked egg white which is why it appears white."
],
"score": [
11,
4
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk1iyb
|
Why is "mama" the same word with the same meaning in languages that have nothing to do with each other from Africa to Europe?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnhg6qp",
"gnhiees"
],
"text": [
"Because \"ma\" is one of the easiest sounds to make, along with \"da\" and \"pa\". This means babies that are making random noises as they learn to talk will start out saying these sounds to get their parents' attention, and as a result people around the world took it as the words for parents. As for why \"ma\"-derived words almost universally mean mother and \"da\"/\"pa\"-derived words almost universally mean father, I don't know.",
"Because babies all across the world make that sound, so it was easier for each isolated group or tribe to accept that combination of sounds to mean mother. When they got together, and compared notes, it stuck."
],
"score": [
110,
10
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk1pr5
|
Why do the colours in a multicoloured shirt not "run" into one another?
|
When doing our laundry, we are commonly told to always separate the darks from the lights to avoid the dark colours from staining the light coloured shirts. What happens when you wash a shirt that comes in a mixture of dark and light colours?
|
Chemistry
|
explainlikeimfive
|
{
"a_id": [
"gnhhcxn"
],
"text": [
"Most modern washers, detergents, and fabrics don’t actually require you to separate clothes anymore, so if a multicolored shirt doesn’t run that means you’ve been wasting time while doing your laundry."
],
"score": [
7
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk1usa
|
How does an airfrier work?
|
Physics
|
explainlikeimfive
|
{
"a_id": [
"gnhhr7b",
"gnhi761",
"gnhiyld"
],
"text": [
"Think it's like a little convection oven so, heating element and a fan. It blows hot air around. I'm sure someone can put it more eloquently but I think that's the gist",
"Same as a convection oven: hot air with circulation. In a regular oven, the stagnant air touching the food is cooler than the oven temperature. Stirring the air makes sure that that oven-temperature air is always in contact with the food. It's not really frying, more like fast baking.",
"Same as a regular oven just with airflow. Think of a nice hot bath. If you dont move, and the water stays still, it seems pretty comfortable. If you were to start moving the water, it feels a lot hotter."
],
"score": [
7,
7,
4
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk26su
|
Why are earthquakes so violent if tectonic plates move so slowly?
|
If tectonic plates move only a few cm a year how are the earthquakes so strong?
|
Physics
|
explainlikeimfive
|
{
"a_id": [
"gnhk1va"
],
"text": [
"In normal experience, rocks are pretty...not squishy. Under the enormous pressure of entire continents moving, though, rock gets compressed. This stores energy, like a spring. Although the entire continent is moving some local areas might get stuck or hung up. As you can imagine, even miles of rock getting stuck won't stop the motion of the entire rest of the continent, so the continent just keeps shoving and pushing, and that stuck area compresses and flexes until it can't compress or flex anymore. At that point, it either breaks through whatever friction was keeping it stuck, or some part of it breaks off - it isn't stuck anymore. All of that energy that was stored gets suddenly and violently released as the area snaps into place. Imagine it a bit like bending a piece of spaghetti. You can bend it *really* slowly, over the coarse of hours or even days. When the spaghetti snaps, it will happen quickly and violently. Or, you can think of it like [compressing paper]( URL_0 ). Paper doesn't like to compress, so it doesn't...until it does, suddenly. Rock *really* doesn't like to be compressed but when it's a continent pushing the rock, it doesn't have much of a choice."
],
"score": [
11
],
"text_urls": [
[
"https://www.youtube.com/watch?v=qTz7aKEJLV4"
]
]
}
|
[
"url"
] |
[
"url"
] |
lk27iz
|
How do plants with red and purple leaves preform photosynthesis?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnhnsb5"
],
"text": [
"The red/purple leaves still contain chlorophyll, and they capture the energy of sunlight the same way as regular green plants. High amounts of dye chemicals just make them look not-green. As far as I know, the purpose of these chemicals is debated, but a likely possibility is that their antioxidant properties protects the plant tissues from damage."
],
"score": [
4
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk2hj3
|
Why aren't commercial airplanes faster?
|
Technology
|
explainlikeimfive
|
{
"a_id": [
"gnhl7m2",
"gnhl46x"
],
"text": [
"Flying close to and above the speed of sound consumes a lot more fuel per passenger-mile travelled (due to the need for the aircraft to be able to handle the forces involved and other factors)",
"How fast do you want them to be?"
],
"score": [
13,
3
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk2k0t
|
what exactly is the difference between a "disease," or a "syndrome," or a "disorder," or a "condition?"
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnhn1uh"
],
"text": [
"IIRC a disease is caused by a pathogen but a syndrome is caused by a physiological response. A disorder is a condition that causes interference with day-to-day life."
],
"score": [
4
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk3a6a
|
What does i, imaginary number, mean in math?
|
I know how to solve problems with i, but I have no idea what it means or what im doing. I want to UNDERSTAND it, not just memorize steps. I understand 1+1, I have 1 apple, now I have 1 more. easy But what about i, how can a number be imaginary? Whats the purpose of it?
|
Mathematics
|
explainlikeimfive
|
{
"a_id": [
"gnhqj3h",
"gnhxho7",
"gnir48p"
],
"text": [
"> But what about i, how can a number be imaginary? & #x200B; Don't get hung up on the name, *i* is no more \"imaginary\" in the colloquial sense (meaning made up and not \"real\") than 1 or 2 are. i is simply the number where: *i*^(2)=-1 & #x200B; > Whats the purpose of it? Well, it doesn't really need a purpose. It's just the number you get when you take the square root of -1. That said imaginary numbers are actually super useful for modeling certain things that happen in the real world. For complex math reasons, *i* is related to trigonometry. And for other complex math reasons trig is used to model waves, so any math where you need to model a wave (like electricity) then imaginary numbers are super useful.",
"'Imaginary' is not a good name. Highly recommend watching this series on YouTube -- it completely changed my understanding URL_0 I'll try to capture the essence here. Let's go with your apples example: you can't take 4 apples from 3! But you understand that there are applications where negative numbers are *useful* -- you'll see it's the same concept that gives rise to complex numbers. One of the key mathematicians was of the opinion that 'imaginary' numbers should instead be called 'lateral' numbers -- watch the videos and you'll understand why!",
"The complex numbers field has a very nice property called \"algebraic closedness\". It basically means that every polynomial with complex coefficients has a root. The \"imaginary\" number i was probably conceived just so we can have an algebraically closed field in our hands. You can observe for real polynomials, if we treat them as complex polynomials, we can always find roots (the discriminant for quadratic polynomials etc.), albeit the roots are not necessarily real themselves."
],
"score": [
13,
4,
3
],
"text_urls": [
[],
[
"https://youtu.be/T647CGsuOVU"
],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk3d5f
|
What made the cold fusion research by Frieschmann and Poms inaccurate/wrong/lacking of integrity?
|
Obviously other researchers couldn't repeat their results, what did they do that scewed results?
|
Chemistry
|
explainlikeimfive
|
{
"a_id": [
"gnhqj19",
"gnhrw3q",
"gnhw2ua"
],
"text": [
"Lied, most likely. On first reports most physicists took a look at the heat values reported, the rate of fusion and the number of neutrons. None of them added up. Namely, F & P standing there with a test tube which, if it was putting out the claimed amount of heat, should have quickly killed them with radiation poisoning from the neutron flux.",
"The school published their results, and made a big deal out of it. Then the results couldn't be reproduced. They measured a very small amount of excess heat. There was probably a flaw in their experimental setup.",
"They failed to conduct their experiments carefully. For example, they tried to make very sensitive measurement of heat \"produced\" by their \"fusion\". They didn't want to complicate their heat measurements, so they simply avoided stirring the water. Basic failure. They also tried to use a neutron detector, but didn't learn how to calibrate it properly. Basic failure. If they were students in a physics lab, they would've got F grades. Basically, there was a mad \"gold rush\" mentality after their announcement, where many physicists threw down sloppy experiments, sloppy theory papers, sloppy everything, hoping to strike it rich with some luck. Of course that meant false confirmations reported in different countries. That kept the frenzy alive, even while the original researchers failed to reproduce their results under controlled conditions."
],
"score": [
5,
3,
3
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk3zc4
|
Why do we see stars when we are close to passing out
|
You ever hold your breath too long or brace really hard at the gym and see stars? Yeah what's that about?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnhu5p1"
],
"text": [
"It’s caused by high blood pressure. You could also “see stars” due to low blood pressure if you change positions quickly, like standing up fast for example. The term for “seeing stars” is an “entoptic phenomenon”."
],
"score": [
7
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk44yj
|
Why can a rocket leave Earth's atmosphere without burning up, but does upon re-entry?
|
Physics
|
explainlikeimfive
|
{
"a_id": [
"gnhvll3",
"gnhwo5s",
"gnhvx5a",
"gnhwcqt"
],
"text": [
"The speed of reentry is much higher than the speed it reaches while escaping the atmosphere. Rockets need to do two things to get into orbit: get high enough to travel above the atmosphere, and gain lots of lateral velocity -- aka moving to the side VERY fast. The initial stage of a rocket's ascent is primarily focused on the former. Once it's out of the atmosphere, it can start picking up serious sideways speed. If it tried to pick up this speed while within the atmosphere, it would indeed burn up, because the air compression would heat it up to similar levels as it would experience during reentry. So, rockets don't start to go this fast until they're far out of the thicker layers of the atmosphere.",
"Most of the acceleration of a rocket for orbital speed is when it is outside of the thick part of Earth's atmosphere. You can see a graph of [apollo reentry]( URL_0 ) where the blackout for the ionizing around starts at 320 000 feet and the highest acceleration is at 200 000 feet. That is 97km and 60 km. It is around the Karman line at 100 km that the atmospheric reentry starts. If you look at a Falon 9 launch like the Crew-1 mission the [stage separation]( URL_1 ) at 93 km is at a speed of 6860km/h=1900m/s. The speed when the [Second stage stop]( URL_2 ) is 27000 km/h = 7500m/s at 200 km. This is close to the speed you will reenter the atmosphere at when you return. The first stage of the Falcon 9 primary lift the second stage out to the atmosphere and work against gravity and air resistance. The second stage is primarily used to accelerate the payload to orbital speed. The reentry from low earth orbit is around 7800m/s and it was 11km/s for Apollo. So we talk about 1/4 of the reentry speed during launch where reentry starts.",
"The rocket goes up slowly, until the air is thin enough. As they pitch over, they can go much faster. Going really fast all takes place outside the atmosphere. Re-entry involves going into the thicker part of the atmosphere. Going there at speed creates a lot of heat.",
"On the way up, rockets are using their engines to speed up. Almost all the resulting heat is in the exhaust. On the way down, rockets have almost no fuel left so the only way to slow down is to aerobrake, i.e., use the air to slow them down. The resulting heat is wherever the air is hitting the rocket. When using engines on the way up, they can choose to go up first to get clear of most of the atmosphere before turning sideways and speeding up. They never go super-fast in dense air. Coming down, you don't have much choice, because you're letting the air do the slowing. You can choose how steeply you come in: too steep and you melt and get very high G forces; but there's a limit to how shallow you can go to re-enter."
],
"score": [
29,
11,
3,
3
],
"text_urls": [
[],
[
"https://space.stackexchange.com/questions/37253/why-does-the-apollo-reentry-trajectory-show-a-few-climbs",
"https://youtu.be/bnChQbxLkkI?t=15310",
"https://youtu.be/bnChQbxLkkI?t=15948"
],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk5043
|
What's the Iran-Contra affair and how did it lead to the crack epidemic?
|
Economics
|
explainlikeimfive
|
{
"a_id": [
"gni0m6m"
],
"text": [
"I had not heard about its connection to crack, so if one exists, I'll let someone else fill that in. There were a lot of drugs going in and out of there for various reasons, but I am not sure it was directly related to Iran-Contra. In 1979, there was a revolution in Iran. Before the revolution, the leader of Iran (The Shah as we called him in the US) was very friendly to the US. Like, extremely friendly. Like we probably put him there. Then the revolution happened. The Shah was overthrown and US citizens in Iran were taken hostage. President Carter couldn't make any headway into getting them released. This was probably a big factor (on top of a stagnant economy) that led to him losing the 1980 presidential election to Ronald Reagan. Because Iran was now the enemy of the US (even though the hostages did get released), the US enacted an embargo. No trade of any kind with Iran. We even gave money and weapons to Saddam Hussein in Iraq to fight Iran (he mostly used them to go after his own internal enemies). In Nicaragua, there was also a revolution. The new government there was very left wing (Marxist). Reagan didn't want this. But instead of invading with the US Army, he wanted to fund the opposition to the Nicaraguan government. A group of right wing Rebels called The Contras. But money given to them had to be off the books. How to get money to The Contras without anyone in government finding out? Sell arms to Iran. Money from arms sales to Iran went to The Contras in Nicaragua. Besides the Iran part being illegal, aiding the contras was also declared illegal by Congress (but it kept getting US funds anyway). The Contras also committed atrocities, and blamed the US for them. This is the Iran-Contra affair. Reagan claimed, under oath, that he couldn't remember any details about this. He threw Oliver North under the bus to take the blame for it. North is now a popular guest on Fox News. tl;dr, money we weren't supposed to have was given to people we weren't supposed to fund to \"stop communism.\""
],
"score": [
6
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk515i
|
Why does water expand when it freezes but it contracts as it cools down in liquid form?
|
Chemistry
|
explainlikeimfive
|
{
"a_id": [
"gni3jba",
"gni0jop",
"gni34ey"
],
"text": [
"Most substances don't. Only water and a few others get larger when they freeze. Water is V shaped molecule. When it's a solid, it stick together in [this shape.]( URL_0 ) As you can see, there's a lot of empty space in the middle of the ice crystal. When water isn't completely stuck together (ie a liquid), the water molecules Vs can more freely float around and occupy that space. However, liquid water actually doesn't get denser when you cool it as an absolute rule. Only from boiling (100°C) to 4°C does it get more dense. From 4°C to freezing (0°C) it actually starts to get less dense again as the water molecules start sticking together a little more like it's solid form. 4°C liquid water is the densest form of water on earth. There's some more exotic forms of ice with a different structure and more dense fluids, but you aren't going to find those on earth. They take extreme temperatures and pressures.",
"Molecules in hot liquids are moving fast and have the energy to pull away from each other and taking up more space as a result. As they cool, they lose energy and are drawn in by the molecular forces that make molecules stick together. When water freezes, the molecules lose enough energy that they can no longer keep apart and form up into a solid but because of the shape of water molecules (2 hydrogen and 1 oxygen molecules in a sort of V shape), they don't actually fit together very well, so they actually take up more space than the liquid version because there are gaps in between the molecules that wouldn't exist in a free flowing liquid state.",
"Hydrogen bonds are a type of electrical attraction between H2O molecules. The more positive hydrogen is attracted to the more negative oxygen of another water molecule. These aren't chemical reactions between water molecules. More like electrical attraction. So, hydrogen bonds in water are strong enough that they keep the water particles \"close together\". So they stay in liquid form at room temp. If water receives enough energy (heat) those bonds are broken and the H2O molecules expand away from each other - > gas. When liquid water is heated up those bonds are broken and the molecules move away from each other. When it's cooled down those bonds are reinforced. However, when water freezes something interesting happens. The hydrogen bonds assume a very specific geometrical shape that happens to space each water molecule a little bit further away from each other when compared to liquid water. This is unusual to water, however. Most substances will have their solid form be more dense than their liquid form. Water is weird in that the solid form is less dense than the liquid form."
],
"score": [
17,
5,
4
],
"text_urls": [
[
"https://raw.githubusercontent.com/jessicamizzi/jessicamizzi.github.io/master/images/cbell-ch3-image2-crystal-water.jpg"
],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk55vd
|
How come when you bite into something cold your teeth feel weird?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gni12nl"
],
"text": [
"Your teeth have nerves in them that can be sensitive to hot and cold. Just like nerves anywhere in your body if you trigger them in a way your body feels you should be warned of (this ice cream is too cold and might damage me!) they can send a signal to cause discomfort and warn you to stop doing what you are doing."
],
"score": [
5
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk56cd
|
Why are you always an considered an “addict” or “alcohol” even if you’ve been sober for years?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gni2ka4",
"gni24t5",
"gni25q3",
"gni4ppp"
],
"text": [
"If you have an allergy to peanuts, it doesn't matter that you haven't had one in years, you better not eat some. Addicts and alcoholics are just that, they just can't have their substance.",
"It's because once those patterns for addiction are established in your brain they stay there and it's super easy to fall back into the habit. Many people feel the pull of their previous addiction every so often throughout their lives. In essence, getting clean and staying that way is a lifelong journey that will always take work.",
"Because addiction doesn't just go away. You're just dormant or in remission. I know people who haven't had a drink in almost a year but they're still an alcoholic. If you were to slip you'd just start back at the same level you were at before. It's hard wired into your brain now. It's just the way our minds process addiction.",
"The idea that every addiction is a lifetime struggle is a harmful myth perpetrated by the rehabilitation industry to increase recidivism rates. This is my personal opinion from volunteer work with mental health and substance abuse agencies, including AA."
],
"score": [
23,
19,
11,
3
],
"text_urls": [
[],
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk5744
|
After a cut or wound, how does your body replace lost blood and how does it know when you have enough and to stop replacing it?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gni1gsg",
"gni3x2h",
"gni1hhv"
],
"text": [
"Your body makes blood all the time. The oldest cells get broken down and recycled. Cuts and blood donations just leave more room for the new ones.",
"As others have said, you are always making new blood to replace old blood or lost blood. To add on though and answer the 2nd part of your question, yes your body does sense if you have enough. Your body senses how much oxygen is being carried in your blood, when it gets low and its time to make more red blood cells your kidney starts making a hormone called EPO which will make more RBCs.",
"not a professional: my understanding is that you are always producing new blood, and existing blood cells die and end up in your poop giving it its color. Theres not a start/stop per ce, its more like a as new come in, old is on the way out."
],
"score": [
9,
5,
4
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk5z1y
|
Why do we swing our arms in circles when we are falling or about to fall?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gni5vus",
"gnive0e"
],
"text": [
"The simple answer is that you are instinctively trying to re-distribute your weight, in order to prevent yourself from falling. Have you ever seen an old school weighing machine, with scales on both sides? Think the scales of justice. If one side is low (or fallen, in this metaphor), then you add weight to the other side to lift it. When you move your arms as you fall, you are trying to add more weight to the opposite side of the motion to stay upright. Sometimes it works, sometimes it doesn't",
"You are trying to use conservation if angular momentum to rotate your body into an upright position. If your arms are swing clockwise, you body will rotate anti-clockwise in order to conserve angular momentum."
],
"score": [
8,
5
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk65ut
|
Why does glueing two things together, make the edges of the things glued together to crease upwards?
|
It’s difficult to explain, if you ever glued two things together and you didn’t apply the glue perfectly or well enough, you’ll see the edges of the paper defy gravity and begin to rise.
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gni7jk7"
],
"text": [
"I would say its because when the edge is not glued, as the glue does it contracts slightly, pulling the surrounding paper towards itself. This causes the paper to curl slightly."
],
"score": [
3
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk694g
|
Why is India in the 3rd place on GDP based on PPP valuation and yet most people live in poverty?
|
Is it maybe because of uneven distribution? I thought a high rank in purchasing power parity reflects the living standard of people
|
Economics
|
explainlikeimfive
|
{
"a_id": [
"gnjm1ys",
"gni7clu"
],
"text": [
"Because capitalism is designed to extract wealth from the poor and amass that wealth in the hands of an already powerful few. This is the same reason that the United States is the wealthiest country in the world and yet a significant portion of the population lives in poverty.",
"India has an enormous population. Despite its high GDP (PPP) this wealth is spread across an *enormous* population. If we took all the poor people in the world and added their wealth together, they'd be rich! Why, then, are they still poor?"
],
"score": [
8,
3
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk6f96
|
() Why do we have to “fall asleep” to regain energy?
|
I’ve always wondered.. why do we have to actually “fall asleep” in order to be rested for another day? Why can’t a person just close their eyes and lie completely still for their body to recover? What does “sleeping” actually regenerate?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gni8w1n",
"gnilhw3",
"gni8ihw",
"gnj9efq",
"gnimmyg"
],
"text": [
"Think of your body as a restaurant. While you're awake, it's open and the kitchen and dining room is full of people. There's no way to clean, bring in new supplies, or fix issues with the building. You have to have a period of time when the rooms are not in use to do a full clean and resupply. This is sleep. It forces us to shut down our brain and bodies for cleaning and repair.",
"There's a ton of reasons but: A lot of \\*feeling\\* \"tired\" is a chemical called adenosine that builds up with activity over the day. When you sleep, you clear it out and start over again.",
"It allows the brain and body to clean itself. When we sleep our body goes to work moving waste out, especially the lymph systems.",
"This is a fascinating subject that cannot really be ELI5'd IMO. But if you find it interesting, then I highly recommend that you read \"Why we Sleep\" by Matthew Walker ( [Why We Sleep: The New Science of Sleep and Dreams eBook: Walker, Matthew: URL_1 : Kindle Store]( URL_0 ) ), which will change the way you think about the whole subject. One of the most interesting books I have ever read..",
"Sleep allows us to enter into REM sleep, during which phase we consolidate memories and regenerate cells (along with a lot more). It also clears up adenosine which accumulates during the day as a by-product of energy. Sleep- and REM sleep in particular- is therefore vital for our health and wellbeing. Often sleep meds don’t allow for deep REM sleep or not enough of it, thus why you might wake tired and zombie like after a night of medicated sleep."
],
"score": [
75,
10,
7,
4,
3
],
"text_urls": [
[],
[],
[],
[
"https://www.amazon.co.uk/dp/B06Y649387/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1",
"Amazon.co.uk"
],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lk6v1m
|
How can people with certain medical issues like POTS or orthostatic hypotension handle putting up to 10 grams of salt in their system daily? Is it harmful over time?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnic3hx"
],
"text": [
"If their issue is hypotension I would argue salt would help their situation since it would increase their basal blood pressure Regardless, sodium levels in the body is very critical to maintain so the kidney do a very good job making sure that the concentration of sodium remains relatively constant by peeing out salt or retaining more water."
],
"score": [
6
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk704q
|
How come photographers on Earth can capture our galaxy during one of those amazing time-lapse we see. But astronauts can’t take a picture of it in space?
|
Sample video: URL_0
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnibona",
"gnik86k"
],
"text": [
"Long story short... Exposure. Getting those big galaxy shots from the ground require a long exposure. On the moon they used short exposure time focusing on what was right in front of them.",
"Do you mean something like [this]( URL_0 )? You see pictures of earth more because they're unusual. The astronauts cameras aren't as good as a serious hobby telescope, so the pictures aren't more interesting that what we can get from earthbound telescopes."
],
"score": [
11,
5
],
"text_urls": [
[],
[
"https://www.nasa.gov/image-feature/stargazing-from-the-international-space-station"
]
]
}
|
[
"url"
] |
[
"url"
] |
lk8fma
|
- Why can't film directors film a scene from every angle with multiple cameras and remove them in post?
|
Technology
|
explainlikeimfive
|
{
"a_id": [
"gnijr4u",
"gniohi5",
"gniiawk",
"gnipb6f",
"gnioqn0"
],
"text": [
"Even if camera removal in post were cost-effective enough to use, dramatic lighting really only looks best on one side at a time. If filming multiple angles is a necessity, it will usually need to be done with compromised lighting.",
"The trouble as well is that it is not just a camera and operator that would need to be removed. There are so many people, lights, cameras, cables, special effects, monitors etc. just out of shot in every scene. They can get multiple cameras in most shot but only from a limited range of angles. The post production of removing all of this stuff frame by frame (rough guess, 24 frames per second x 60 seconds per minute, x 120 minute movie is around 10,368,000 frames that need to be perfectly photoshopped)",
"it would additionally be more expensive. And if the cameras aren’t being properly used the scene would be more cold and the cinematography will be probably not what they’re looking for when they finally get a project",
"Your question insinuates that to 'remove everything you want out in post' isn't a difficult and costly process, performed by skilled digital artists – it takes a *lot* of time and care that those artists need to be paid for. *That*'s the something that you're missing. Your post sounds like you expect someone to just click a \"make it look like you want it to\" button and be done.",
"Lighting is *huge* part of filmmaking. Different lighting can make the same shot look completely different. You can photograph the same person with different lighting, and they would look different. Directors take a lot of care to make sure the lighting is exactly like they want it for each shot. The lighting, similar to the music, the sound, the camera movements, the acting, the dialogue, etc., tells the story in its own way. The problem with lighting is that you can only sometimes set it up for one camera. If you want to the light to come from the left side of the shot for one camera, then the light direction would be different for a second camera. This is why most shots are filmed with a single camera, because the lighting is tuned for that one camera angle only. In scenes were lighting is less of an issue, then you can use multiple cameras. The lighting is a reason why soap operas have that weird look to them. Because they film on multiple cameras to save time and money, they oversaturate the set with lighting. Because of this abundance of light, the shots look odd when compared to properly lit shows and movies."
],
"score": [
15,
6,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lk8q3z
|
Why do iphones pause at 80% charge instead of 100%
|
Apple has an optimized battery charging mode where if you keep it on, your phone stops charging at 80% while you sleep and starts changing again from 80 to 100% before you wake up Why not just have the phone charge straight to 100% and it stops there?
|
Technology
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explainlikeimfive
|
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"text": [
"Li-ion batteries don't like being at the extreme ends of their voltage range. If they're below say 20% or above say 80%, the batteries will age much faster. By stopping at 80% and then finishing the charge before the phone gets taken off the charger, you make sure that it doesn't spend more time at 100% than it absolutely needs to, so you extend the life of the battery a bit."
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lk9vno
|
capacitors. what do they do? what is it for?
|
Physics
|
explainlikeimfive
|
{
"a_id": [
"gnip8wx"
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"text": [
"You can picture a capacitor like a tiny battery that has the ability to charge and discharge very, very quickly. They have all kinds of different uses, but they're often used as a kind of energy buffer. Digital chips for example don't draw power continuously, but instead they draw a large amount of power for a fraction of a second, then nothing for a bit, then a large amount and so on. A normal power supply wouldn't be able to keep up with the current spikes, so instead you put a capacitor across the power supply of the chip, which enables the chip to draw power directly from the capacitor and the power supply only needs to keep the cap 'filled'."
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7
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"url"
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lkasbv
|
What does an anti-dandruff shampoo actually do to get rid of the dandruff?
|
Chemistry
|
explainlikeimfive
|
{
"a_id": [
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],
"text": [
"All dandruff is caused by a fungal infection that infects the scalp of every person on the planet. In most people the fungus doesn't do much damage but if the scalps anti-fungal capability is weakened, it is expressed in excessive skin turnover that fall off in flakes - dandruff. Most anti-dandruff shampoos include either zinc or sulfur compounds that kill the fungus, as well as some chemicals that soothe the damaged skin. They cannot kill the fungus completely however and even if they did, the person would be reinfected pretty much the next time they meet another person. Thus, while the shampoos are effective at reducing or completely eliminating the dandruff while you keep using them as instructed, they don't actually cure the underlying problem nor are their effects very long lasting. Most of them that are based on sulfates actually further compromise the scalps own anti-fungal capacity and will thus keep a person with a problematic scalp hooked forever. To get rid of dandruff for good, one must address the underlying cause - why the scalp is weak to fungus in the first place. The most common cause is because its too dry from overuse of soap in which case, changing to soap free cleansing alternatives usually helps. At other times there may be a Ph imbalance or follicle trauma or a secondary bacterial infection - there is a very long list of possible causes, most of which have a solution. If you find your dandruff is hard to get rid of permanently, I recommend talking to a dermatologist about it."
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124
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[
"url"
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lkatlk
|
Why do things break?
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Why is it that when something breaks, like a glass shattering, the bits don't want to go back together, even if they seem to fit really well? The same for a rock, or other solid material? What changed?
|
Physics
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explainlikeimfive
|
{
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"Most of the time, what change is either a chemical reaction (usually with air) or the structure got reorganised. When you torn a thing appart, when you cut it, when you drop it or whatever that causes it to break, you bring energy to the thing which get converted in pressure, deformation and heat energy. that deformation is either definitive (the molecule got organised in a new way) and don't connect to each other, so the thing fall appart. Or will expose some part to new materials to which they bound (oxygen for example) which change the way the molecules interact with each other, causing it to fall appart too.",
"Everything is constituted of molecules. Depending on circumstances, these molecules can form a bond between them. These bonds can also break. Usually, when high enough temperature is applied to something, its bond weaken and break, leading to liquids. BUT, as it cools down, these bonds will form again, just not between the same molecules. When you break something, you break those bonds. But without a proper situation, they cannot rebuild those. They need specific situation for those to reform. Once they're solid, the bond is solid and even when its broken they simply don't bond."
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lkbjaz
|
What happens physiologically when a person “goes into shock”?
|
Biology
|
explainlikeimfive
|
{
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"text": [
"So, the medical meaning of \"shock\" is different from what people sometimes mean when they say someone is \"in shock\" (as in, overwhelmed by a situation). You didn't specify in your question, so I'm assuming you mean the actual medical term. Shock happens when there is not enough volume of fluid in your circulatory system (arteries and veins). This can happen for different reasons - massive bleeding is probably the most well-known one, but it can also happen due to an allergic reaction (which can make fluid go from your blood vessels into the surrounding tissue), neurological damage or other medical emergencies. Since blood volume is essential for transportating oxygen to your vital organs, shock is a life-threatening emergency. Your body tries to compensate for the loss in volume. As blood pressure decreases (because there is less blood), your heart rate goes up (blood is pumped faster to transport more oxygen). Think of it this way: If you have commuter trains transporting a set number of people every morning, and then take off half the carriages of the train (- > less volume) it needs to go back and forth twice as often (- > higher rate) to transport the same number of people. Your body also constricts the \"less important\" blood vessels (mostly in the extremities), so that more of the remaining blood can go to your lungs, heart and brain to keep you alive. That is why, in people with severe shock, the skin usually feels cold. Eventually, if the loss of volume continues, your body can't compensate enough. Blood flow to your brain decreases, and you get dizzy and eventually pass out. If the shock does not improve, it leads to cell damage all over the body and eventually death. If you notice someone exhibiting signs of shock, have them lay flat on the ground and lift up their legs (this helps blood flow back to the vital organs) unless you know or suspect that the shock is caused by the heart not working sufficiently (if this is the case, more blood flow back towards it may just overwhelm it more). Call an ambulance as well - someone in shock needs urgent medical treatment (usually fluids or blood, and/or something to treat the cause of the shock)."
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lkbkum
|
How can something sharp cut me through my pants without cutting my pants?
|
Physics
|
explainlikeimfive
|
{
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"text": [
"Something with a sharp point can get between threads without breaking them, poke a pin through a pair of jeans and you won't see a hole. Alternatively something solid enough to scrape through the top layer of skin isn't necessarily sharp enough to break the threads which have more give."
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8
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lkc0mf
|
why, even after vigorous shaking, i still get the pee drip onto my pants, and why does it seem to get progressively more as i grow older
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I fail to understand why this happens more often as i (m28) grow older, and the drip seems to burn the foreskin even more. I dunno if this has been asked before
|
Biology
|
explainlikeimfive
|
{
"a_id": [
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"text": [
"You may have an enlarged prostate. Other symptoms would include weak urine stream, dribbling, difficulty starting a stream, increased frequency of urination (especially at night), incomplete bladder emptying, possible pain/burning that can be in the tip of the penis or radiate from the hip. If this continues to be an issue go see your doctor as there are several reasons a prostate can be enlarged and you would need workup for an infection. Also consider applying upward pressure (a few times after urinating) to the perineum (area between testicles and anus) this will push out any urine that remains in the urethra as a result of the prostate clamping down on the urethra. As men grow older the prostate continues to grow. The vast majority of men will have enlarged prostate in their 70s, however, the first phase of growth is in the 20s and some do have symptoms (albeit rare) during that phase.",
"It's a pretty common problem that's partially due to the poor design of the male urinary tract, partially due to weakened pelvic floor muscles, and possibly partially caused by an enlarged prostate. Basically, even if you empty your bladder, there's still pee in the pipe. Think of it like a hose where, even once the tap is turned off, there's still water inside the hose, unless gravity can get it out. If your pelvic floor muscles are strong and in good condition, they can help. As we get older, or muscles become weaker, especially if we have sedentary jobs, and they stop doing as good a job squeezing the pee out, so it comes out on its own time. Sitting down to pee might help, as will using some toilet paper to catch stray drips. Keeping your abdominal core in good condition might also help. This isn't just abs, though. This is the deep muscles; people with penises can do Kegel exercises too. As for the enlarged prostate, you'll need to talk to a GP and maybe a urologist."
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lkc2dr
|
Why do people forget words they know?
|
Why do people forgot words they know? They can define a forgotten word once reminded, know how to spell and pronounce it.. Why can’t they access the word on demand from their memory? Much love ❤️
|
Other
|
explainlikeimfive
|
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"From what I understand, your brain store information by how useful it determines it to be. Something immediately useful on a day to day basis like the layout of your neighborhood will probably never 'go obscure' even years later even if you move off. Our simi-nomadic monkey brains think it may one day be relevant again. Weird facts like how geckos have two penises, while completely worthless is very weird and novel (and funny), so your brain will hold onto it. A good chance to use defenestrate doesn't come up very often. Socially people don't really care. Your brain puts it in long term storage or forgets it altogether, you can still recall it, but usually it involves trying to figure out related concepts/scents/sights/sounds. To trigger a recall.",
"Recalling a memory is a lot like doing a 2D maze. You know where you start, and where you want to go, but the path you take there might take longer depending on how many wrong turns you take. So ultimately you have the word there somewhere, it just might take a really long time to remember it. Also, sometimes your conscious memory makes mistake after mistake which makes it nearly impossible to find the memory. Your subconscious thought processes can help grab it later. That's why when you stop thinking about it, the answer comes to you a bit later. I'm super duper simplifying. Memory and brain pathways are so complex it's impossible to simplify it and stay accurate."
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lkd31b
|
How do historians know which empires gained or lost certain lands during certain years?
|
I find it amazing that historians can find this information. Were there people back then who recorded all this information every single time? How would we know if that’s accurate?
|
Other
|
explainlikeimfive
|
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"Historían use written sources for that. For example, medieval monks used to keep chronicles, writing down everything important that has happened each year. Of course they only did that for whatever they considered important at their place and time. For certain years chronicles might go like “nothing much has happened this year”, but generally conquest of some nearby lands by someone was important enough. With a lot of chronicles written in different locations historians generally can piece together a quite coherent picture. There is also a multitude of other written sources, like traveler accounts, historical accounts written by contemporary scholars, works of literature etc. Of course some of our modern understandings of historical events are less accurate than others. For example, if some civilization didn’t leave any written sources (like the earliest Indus Valley civilization) or a lot of those sources have been destroyed (like Aztecs) then historians have difficulties. But still. Edit: Indus Valley civilization left some inscriptions, but we can’t read them, because we can’t decipher the script.",
"We think that a precursor to having an empire would be the ability to write as this allows you to do thinks like accounting, taxes and even written laws. And when we do have writings then some of it tends to survive. Either as the original text if written on clay or stone or because people made duplicates to record the history of the empires. So whenever a territory switches from one empire to another we have the tax records of both empires to prove it as well as the logs of the generals or diplomats responsible. And this stretches back thousands of years. Records from kingdoms on the other hand tends to be a bit more vauge as it is possible to rule a kingdom without writing things down. There are kingdoms in Europa as late as a thousand years ago that we do not know the extent of because we only hear about them through their neighboring empires or from oral history. In the rest of the world this may be extended to hundred and fifty years ago for certain kingdoms. But still with the records we have from these ancient empires the concept of very strict boarders is a relatively new concept so this rarely applied. An empires control of a region was more or less on a scale and often very circumstantial. We still have a similar concept today with autonomous regions which you will find all over the world and you also had the feudal concept of a mark. So we do often find records of areas that looked like it was controlled by two empires at the same time and maybe even paid taxes to both and maybe even their own independent kingdom as well. In some cases it could be that records have been falsified afterwards to give legitimacy to claims but in other cases it looks like it was actually the case."
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lkdidn
|
How does your body regulate the way you feel temperatures?
|
I'm not sure how to word this question. I live in SD and it's -24°. I work at an animal shelter so I'm outside a lot. Initially, the cold takes my breath away, but only minutes later it feels tolerable. How? Why?
|
Biology
|
explainlikeimfive
|
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"Your body is one large radiator in which your blood is the coolant, flowing through blood vessels beneath the skin and rejecting waste heat to the environment. When you're in a cold environment, this heat is rapidly absorbed from your body and interpreted by your nerves as \"I'm cold\" To compensate, your body can constrict those blood vessels at the surface and shunt their load to deeper blood vessels that are insulated by fat and muscle. Beyond that, it can divert blood from your limbs to protect the thoracic organs at the cost of risking frostbite/cold injury from poorly perfused tissue. The reason you notice at first but become used to the colder temperature is that your body has adjusted to a new equilibrium by reducing blood flow to the surface of your skin, and restricting heat loss to a manageable amount.",
"The human body/mind can habjtuate to a *surprising* range of 'inconveniences' over time. If you were to take yourself out of that environment for a long enough time, with no exposure to those temperatures and then return, you'd be quite surprised at how cold it truly is"
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lkdyau
|
- Why are tortoises able to live for over 150 years?
|
Biology
|
explainlikeimfive
|
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"First of all, the turtle you're talking about have a very slow metabolism. So their cells dies and are replaced slowly, so they age slowly (compared to us). They are also living shield, able to survive many kind of attacks, so they have lower chances of being killed, letting them grow old, thus the high average life expectancy. There are some studies trying to explain their seemingly higher resistance to some deadly diseases (like cancer for example), but we are unsure for that one."
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lkey8d
|
where does the soap in a dish sponge go when you leave it for several hours?
|
Chemistry
|
explainlikeimfive
|
{
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"It breaks down. Most things do when exposed to the environment. For example bleach turns into salt, water and O2."
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lkfbnh
|
How does stomach create noises?
|
Biology
|
explainlikeimfive
|
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"To simplify this a lot, it's pretty much like internal farts?",
"For ease of explanation we are going to say that your body is mostly a sealed container of all your insides. Inside your body there are slightly pressurized areas with different pressures in different places. When your stomach is breaking down foods and such it creates gasses via chemical reactions. These gasses alter the pressure in your stomach and move around creating vibrations. Your ear interprets those vibrations as sound. Hooray poop!",
"Your stomach uses movement, squeezing, to help break down food. This movement creates noise, especially if theres nothing in your stomach for it to squeeze. Also, if you eat things that are difficult for your digestive system to break down, you will produce gas as a byproduct of bacterial activity which will also make noise as it moves through your body.",
"MD right here the movement of the stomach (peristalsis) does not generate noise, the stomach stretches and shrinks while it has something inside, from food to only stomach acid, the movement that generates noise is intestinal peristalsis, it occurs when the intestine stretches, shrinks, widens and narrow to move the food, and gas, this difference in volumes within the intestine causes the noise remember that there are 25 feet of hose that move in your abdomen and although the movement is forward it is quite messy. Excuse my English",
"Squeeze a sponge. Forcing air through water makes noise. You're basically a long tube with muscles that squeeze that tube. Sometimes when it's trying to push the water forward the air bubbles backwards. The air is both air you swallow, and gases produced by the fermentation of what's in your gut via the action of bacteria and whatnot. So it works the same way air bubbles in the pipes make your house grumble."
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lkfesf
|
Where do those extra four minutes go every day?
|
The Earth fully rotates in 23 hours and 56 minutes. Where do those extra four minutes go?? I know the answer is supposedly leap day, but I still don’t understand it from a daily time perspective. I have to be up early for my job, which right now sucks because it’s dark out that early. So every day I’ve been checking my weather app to see when the sun is going to rise, and every day its a minute or two earlier because we’re coming out of winter. But how the heck does that work if there’s a missing four minutes every night?? Shouldn’t the sun be rising even earlier, or later? And how does it not add up to the point where noon is nighttime?? It hurts my head so much please help me understand.
|
Earth Science
|
explainlikeimfive
|
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"23 hours and 56 minutes is how long it takes the Earth to make one rotation relative to the rest of the universe. However, while it is doing that, it also makes 1/365 of a revolution around the Sun. In order to face the Sun in the same direction as it did the previous day, it has to rotate for 1/365 of a rotation, which takes 4 minutes.",
"By the time the Earth has completed one rotation it has moved a little bit on its orbit around the Sun (about 1/365th of the full circle). So the Sun is now at a slightly different angle and the Earth needs to turn a bit more to face it exactly the same way as one rotation ago. It takes about four extra minutes.",
"There are plenty of other great replies in here, but I thought I'd add a gif that shows what others have already described really well: URL_0",
"It has nothing to do with a leap day. The earth takes about 23 hours and 56 minutes to turn around once on its axis in respect to the stars around us, but in that time the earth also moves forward in its orbit around the sun by about one degree. Basically after the Earth turns once around its axis, the sun is no longer where it was before and the Earth has to turn a tiny bit (about 4 minutes) more to be in the same position it was in respect to the Sun. Over the course of a year those 4 minutes add up to about one day. Basically the earth turns around its axis 366 times a year but thanks to the fact that we also obit around the sun once we only get 365 days per year. If you count days by the rising and setting of a star you will get one more day than if you counted days by the rising and setting of the sun. The whole leap year thing is a completely different thing. It comes from the fact that an orbit around the sun does not take exactly 365 days (as i pretended above) but more like 365 and a quarter days. The length of the year is not a whole number of days. We take the quarter days that are left over each year and then when we have enough for a whole day we add a February 29th. This is sort of every 4th year.",
"Damn. I thought I knew the answer until I re-read your question. The leap year keeps the seasons from progressing but you raise a good point. After a month noon should be 2 hours earlier. I’m gonna sit down and wait for an answer with you.",
"The 4 minutes is because of the earth's orbit around the sun. A day is an average time between two solar noon. Solar noon it the point in time when the sun is highest in the sku If Earth was not rotating the sun would move around it once per orbit. so the orbit creates a day that is a year long. That means the sun will be in the same place in the sky 24\\*60/365=3.9 minutes later. So earth rotation + earth orbital moment around the sun result that the average time between two solar noons is 24 hours. This is the average length because earth orbit is elliptical. The shortest say is 21 seconds less than 24 hours and the longer 30s longer. This will change the time of solar noon by +-17 minutes during a year. So if we based the clock on earth rotation noon would move around and it could be at any time during a year. But because we base our day on the solar noon is around the same time every day. The position of stars in the sky move around during the year because of this. & #x200B; This is not why days in the winter is short and long in the summer. It could not be because the southern hemisphere has summer when the northern have winter. The length of days and the season is because the earth's axis is tilted relative to our orbit around the sun. During the summer the hemisphere you are on point towards the sun and the days are longer and in the winter it points away from the sun. & #x200B; Leap days exist because a tropical year is 365.24219 days. To have a calendar that follows the season you need to have years with different lengths. 1 extra day every 4 years is a close match 365.24219\\*4-365\\*4-1=0.031 days. So we need special rules for years divisible with 100 and 400. A topical year according to Wikipedia is > > > A tropical year (also known as a solar year) is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice. This differs from the time it takes Earth to complete one full orbit around the Sun as measured with respect to the fixed stars (the sidereal year) by about 20 minutes because of the precession of the equinoxes. The 20 minuted difference from the obit around the sun is because the earth axis slowly changes direction. The difference is why the day of the zodiac do not match today and when the common variant was made around 2000 years ago. 20 minutes per year after 2000 years is 20\\*2000/60/24=27.7 days. So small difference per year adds up.",
"So why do star charts have a full 24 hours of right ascension on them? Is a sidereal second slightly less than a SI second? EDIT: I looked it up. Yes, a sidereal second is shorter by the amount one would expect.",
"Why doesn't the sun move 4 minutes per day? Because the stars do! The earth spins once every 23h 56m compared to distant stars. But the earth also orbits around the sun. So during that time it's also moved along its orbit by one day. So it needs an extra 4 minutes of spin for you to see the sun in the same place in the sky. And this is why the stars move 4 minutes per day. And why the stars have seasons. Each part of the year the night side of the earth is facing outward from the solar system in a new direction.",
"A nominal solar day (say sunrise to sunrise) is 24 hours. If you time when a star rises each day it's 23 hours, 56 minutes. That's called a sidereal or star day. A given star will rise 4 minutes earlier every day, or about 1/2 hour a week, or 2 hours a month. This is why the sky shifts and changes over the course of the year--if you look at the sky before sunrise in winter, it's the same stars you'll see 6 months later in the evening sky (12 hours timewise), because we'll have gone halfway around the sun. Conversely the bright stars of winter you see now in the evening sky will be in the morning sky come summer. And as mentioned, it's all because of Earth's orbit around the sun, and our point of view shifting that tiny bit day by day over the course of the year.",
"Ok putting together some of these responses, I think the main idea is that we don’t define 24 hours as the time it takes for the earth to spin exactly 360 degrees, but instead as the time it takes for the sun to re-appear in the closest position in the sky from one day to the next. Therefore the 4 minute time difference is irrelevant to daily timekeeping with respect to the sun. (?)",
"It's not leap day. If the earth weren't spinning at all, the sun would still move across the sky because the earth is going around the sun -- a day would be the same length as a year. The sun would move about 1 degree East per day, so it'd be going backwards. We spin the same direction we orbit the sun (counter clockwise if you're looking down from the north pole), so in the time we've made a full rotation, we've also moved about 1/365^th of our orbit around the sun. That means the sun is about a degree \"back\" from where we'd expect it to be. So we need to rotate an extra degree, which takes about 4 minutes. Or another way to look at it... In a year, we spin ~366.25 times, not 365.25. But moving around the sun \"unwinds\" one of those spins. That unwound day is spread across the days of the year. 1440 minutes in a day, split among 365 days, is about 4 minutes.",
"A sidereal year is 365.256363004 days. A tropical year is 365.256363004 days. A sidereal year is the time it takes for the Earth to return to the same position in relation to a certain star (the Point of Aries). A tropical year is 365.24219 days. A tropical year is the time it takes the mean position of sun to advance 360 degrees. This is what the calendar is based on. Leap years are added to correct for the difference of the odd length of the year compared to an integer number of days. We add an extra day to the year every 4 years, unless the year number is evenly divisible by 100, then an extra day is not added, unless the year number is evenly divisible by 400, then an extra day is added after all. Thus: 1996 was a leap year, it follows rule 1 1900 was not a leap year, it follows rule 2 2000 was a leap year, it follows rule 3 This system has been working for the last about 500 years. There is a small error but it will not amount to a full day until about 3800 AD."
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lkhb1i
|
Are deep voices related to high testosterone?
|
Are deep voices related to/caused by high testosterone?
|
Biology
|
explainlikeimfive
|
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"gnjvof2",
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"gnk0808"
],
"text": [
"During puberty, testosterone drives development of secondary sex characteristics typically associate with male sex. This includes the lengthening of the vocal cords, which causes the voice to drop. So, kind of.",
"No. There have been several studies trying to see if circulating total/free testosterone levels are correlated with lower voices with men, and no correlation has been found that reaches the level of statistical significance. Similar to penis size and other physical characteristics that guys tend to obsess about, as long as you have sufficient testosterone to trigger and fully complete puberty, your voice will eventually drop to its lowest target level as defined by your genetics. Vocal depth is more related to the size of the person, the size and laxity of their vocal chords and muscles, etc. If you don’t have sufficient testosterone to trigger puberty at all, then you’ll obviously never deepen to your genetic limit either, but that’s a different question. (Edit: note this is also separate from the theory that some genetic male adult sexual characteristics are “primed” by levels of exposure to testosterone from the mother in the womb, for which there is slightly more evidence, but not the question as asked.)",
"My voice deepened from pregnancy, both times. I used to sing soprano, now I am a firm alto. Relaxin or however it is spelled, which makes the joints and tendons more flexible so that the baby can exit the birth canal loosens the vocal cords as well. So like a looser string on a cello, violin, or bass is a lower note, the looser vocal cord also produces a lower/deeper note. So while testosterone can be a cause of lower/deeper voice, a more relaxed throat can also be a cause."
],
"score": [
18,
15,
9
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lkhbzy
|
When making any animated show episode, is the voice acting done earlier or the animation?
|
If the animation is done first, do the actors have to remain strictly to script leaving no room for improv and also have to nail their timing? And if the acting is done first, how do they time it? Do they have to do it blindly, only by imagination?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnjsjfv",
"gnk38c9",
"gnjrx51",
"gnjyjnt",
"gnkbehj",
"gnkk0w0",
"gnkaec3",
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],
"text": [
"The principal voice cast are normally first, doing multiple takes and allowing for improv at the recording sessions. The final voice performances are edited together from different takes, and are the basis for the final animation. The voice actors may have a simple animatic to help them get the timing right, or just a script and their imaginations. If it's practical, putting dialogue partners together to record shared scenes helps get the flow of a conversation right. Additional voice cast such as translated versions are often much more constrained by the timing of existing animation. Sometimes a film can be re-rendered for translation (For instance, [Zootopia]( URL_0 )) but it's not really common.",
"From me - VFX artist whos worked on a number of animated cartoons in my day: Voice acting is done before the animation. They generally stick to the script, but it's up to the director if they want to do multiple takes, allow for some improv etc. *Generally* speaking there is not much improv in what is said, but they can do multiple wildly different reads of the same lines (which is an art in itself). For the animation part you'd be surprised how quickly animators are able to match the lip sync. We will animate based on the acting from the voice track. *Sometimes* we had recording of the voice actor in studio to refer to, but not *always*. Most high-budget movies will record the actor these days but it's not always referred to. Sometimes after the animation is done they will do a polish-pass of parts of the voice acting. We call that ADR (Though I think we use that term incorrectly). ADR is where they might want to adjust some lines once they see how the sequence looks in the edit, or to add grunts/effort/reaction noises that just add little bits to the animation. The actor will watch the cut and act/grunt/etc which being able to watch the latest cut on a screen. Full disclosure: I work in post production (VFX) and haven't worked in animation in 15 years or so so some of the process may have changed, but this is loosely what my experience was.",
"Not an expert by any stretch, I've just watched a few documentaries. Seems like it is a little of both. Kind of like its live action cousin, the voice acting is done after blocking but before final production. There is still room for some flexibility in higher end productions. My guess is that in lower cost productions, the voice actors are held to a more strict dialog. Think Aladdin with Robin Williams vs Scooby Doo.",
"Opposite the other comments, dubs of course already have animation completed, so they have to make translations, and voice the lines in a way that matches the existing animation as best as possible. They might do a couple takes, then artificially change the speed of a line for some fine tuning later, and stuff like that.",
"Typically voice work is done at the animatic stage. Basically, the storyboard is crudely animated to give the production a sense of timing and what everything will look like. [Robot Hell Animatic]( URL_1 ) [Robot Hell Finished]( URL_0 ) As far as sticking to the script, it really depends on the director. If the actor comes up with something better, the animatic can be easily updated before major work is done, but is is about the director's \"vision.\"",
"I want to say that there have been many excellent answers that go into great detail why and how voice acting is done and I can confirm as well, voice acting is done before the animation. *In the west* In Japan it's often actually the other way around. Usually the production team would have a good idea what the scene is going to be about, but won't have any finished dialogue and the voice actors would work off of the almost finished movie. It has thrown a lot of westerners off when they work on any anime production.",
"Voices are recorded first for a lot of animation (and then the animators match the facial animation to the voice). But I just recently watched a YouTube podcast (called \"Trash Taste\"), where they interviewed a Japanese anime animator (Ken Arto) who has animated on a lot of the most popular recent modern animes.. and he said that for Japanese animation, they do the animation first, because it's 'faster' that way. This is somewhat surprising, because among people who watch anime, there's often a split between fans who prefer \"dubs\" (where English voice actors dub the Japanese animation) vs \"subs\" (where the show is presented with English subtitles and the original Japanese audio). But it turns out that, apparently, all anime is \"dubbed\". So maybe the truth is somewhere in the middle. Different animation studios do things differently.",
"I work in the film and tv industry, there is almost never animation done before the voice acting. There can be sketches of what the characters look like but not usually. They will video record the actor as well so the animators can use the actors facial expressions as reference. I've done sessions for some big budget films and they only have animations after they've done the majority of the principle recordings and decided to change the script, either to add/change lines."
],
"score": [
438,
80,
16,
12,
6,
5,
5,
3
],
"text_urls": [
[
"https://www.mentalfloss.com/article/76784/zootopia-has-different-news-anchors-different-countries"
],
[],
[],
[],
[
"https://youtu.be/DR7rurcamNo",
"https://youtu.be/d7h6rdrCP-I"
],
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
lkhoze
|
Why are mothers so keen on becoming grandmothers?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnjvf4c",
"gnjtlwp"
],
"text": [
"Being a grandparent is like having another baby. You just get to outsource all the awful stuff.",
"For my mother she misses having a baby/young child around so sort of lives vicariously through her children!"
],
"score": [
23,
4
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lkhqzh
|
Why is it so common that flags are lowered to half mast, when a well recognized person dies?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnju4cf",
"gnjtooi",
"gnkffwj"
],
"text": [
"Flags are by their very nature used as signaling devices. Someone can look at a flag and know where a vessel came from, or know which group controls an area. They would also be used to rally troops around on a chaotic battlefield; things could get confusing in a hectic fight but soldiers would always be able to find their fighting unit by following their flag. Because of this the flag bearer was very important, as if they went down the flag wouldn’t be visible and the fighting unit could disperse and was generally seen as defeated. A common method of signaling distress is to lower a flag to half-mast; it is still visible but the lowering references this concept of the flag falling meaning serious trouble. When someone dies flags may be lowered as a symbol of the distress their death caused to the group symbolized by the flag.",
"Sometimes when we really like people, we do things to show how much we like them or miss them.",
"In addition the the other comments posted, one reason I have heard for this tradition is that the flag is lowered to make room for the \"Invisible Flag of Death\" at the top."
],
"score": [
12,
4,
3
],
"text_urls": [
[],
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lkktb6
|
How are English muffins pre cut, but still in-tact around the outside?
|
I hate ripping my muffins :(
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnktvln"
],
"text": [
"English muffins are not pre-cut in a continuous manner, instead they're \"fork split,\" meaning rods like a fork tine were inserted horizontally through the perimeter, making a sort of \"tear on the dotted line\" arrangement allowing you to peel the top off the bottom. If the pre-splits aren't close enough for you to evenly peel the pieces apart, use a fork inserted horizontally around the outside to make more splits, then peel. If you use a knife, you don't get the jagged bumpy hills and valleys inside the muffin which so very nicely hold the melted butter."
],
"score": [
4
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
lkkwu5
|
Why does taking deep breaths help ease stress and anxiety?
|
Biology
|
explainlikeimfive
|
{
"a_id": [
"gnkfivi",
"gnkgam6"
],
"text": [
"One reason is because deep breathing increases carbon dioxide levels in the blood, which quiets down parts of the brain, like the amygdala, that handle your anxiety response. It also helps synchronize your heartbeat and breathing. [Source]( URL_1 for more info on that. Other reasons can generally be described as reversing the cause/effect chain of the sympathetic nervous system, but that's an oversimplification. Think of it this way, if stress causes things like increased heartrate, dilated blood vessels in skeletal muscle, and whatnot, diaphragmatic breathing uses all sorts of mechanisms (cellular, mechanical, etc.) to reverse that flow. It would be like if stress caused the head of a drum to vibrate faster and faster, and diaphragmatic breathing was essentially you placing your hand on the drum to reduce those vibrations. [Here is a pretty good article]( URL_0 .) on some of that.",
"The changes in our body from stress and anxiety are caused by the fight-or-flight response. During this response, chemicals are pushed into the blood that cause increased blood flow to our muscles and brain and we end up breathing quicker to maintain this high energy state. When we expended the energy or are able to breathe slowly again, the body starts to tune the response down. The response is great for physical stressors like a large predator chasing us or running away from a natural disaster. Once you've expended the energy and are able to breathe normally again, the stressor is gone and your body can relax. However, in our complicated world today, most stressors are often not physical. Anxiety about money, relationships, or even just purpose in life can trigger this fight-or-flight response. Physically fighting against it typically goes against the law. Running away ends up making it worse. Therefore, we have to manage this stress response in other ways. Forcing ourselves to breathe slower tricks the body to thinking that we're more relaxed and will turn down the stress response. Another way is to exercise and expend the extra energy in the body caused by stress. Once we're able to control our biological response, it's a lot easier to deal with the actual stressor with a clear mind."
],
"score": [
13,
3
],
"text_urls": [
[
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7602530/#:~:text=Diaphragmatic%20motion%20in%20breathing%20directly,by%20modulating%20intra%2Dabdominal%20pressure",
"https://rightasrain.uwmedicine.org/mind/stress/why-deep-breathing-makes-you-feel-so-chill#:~:text=Deep%20breathing%20\\(sometimes%20called%20diaphragmatic,span%20and%20lower%20pain%20levels.)"
],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lklicd
|
how are people able to hack into webcams and spy on other people?
|
Technology
|
explainlikeimfive
|
{
"a_id": [
"gnkfd39"
],
"text": [
"Because the people who set them up, don't use secure passwords, and so when a hacker finds the device they just try commonly used passwords, and get in. People are warned over and over to use secure passwords, but they don't because its hard to remember. Also, many companies have 2 factor authentication, but people don't want to be bothered with it because they are lazy. Only you can protect yourself."
],
"score": [
8
],
"text_urls": [
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lklomr
|
Why arent sports unisex?
|
Other
|
explainlikeimfive
|
{
"a_id": [
"gnkfz3u",
"gnkgcvw"
],
"text": [
"> I'm sure there are plenty of women who would be able to compete better than players on mens teams now There *really* aren't. Male biology gives a pretty huge advantage in a lot of sports. For example the women's world record for the 100m is equivalent to a pretty good time for a male runner in high school.",
"The differences between men and women physically are far larger than those between different men or women. The only sport so far that I've seen where women outdo men on an even playing-field is the ultra-marathon. Testosterone is one hell of a steroid."
],
"score": [
6,
4
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
|
lkmcmt
|
How do countries like US, Japan and Italy continue to be top economies despite maintaining more debt than their GDP?
|
Economics
|
explainlikeimfive
|
{
"a_id": [
"gnkkfy0",
"gnkl2jh"
],
"text": [
"Does your house cost more than your annual salary? Then you have more personal debt than personal economy, and that's relatively common. Plus, you might die or retire some day and your personal debt has a \"limited shelf life\", so to speak. These nations last much longer than people, so their debt is even less of an issue. I wouldn't invest in Somali government bonds, as they tend to replace their government rather more frequently.",
"\"Economies\" in the informal use of the term typically refers to all the economic activity that occurs within a country or region. This includes activities of private entities as well as public entities. Without more specifics, \"debt\" I am guessing refers to \"government debt\". This is the borrowings of the government and not private debt. They have some relationship but directly comparing one to the other is not very meaningful. There are poor economies with little debt, poor economies with high debt, good economies with reasonable debt and good economies with high debt. Public debt isn't a good predictor of economic strength or vice versa."
],
"score": [
5,
3
],
"text_urls": [
[],
[]
]
}
|
[
"url"
] |
[
"url"
] |
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