[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5 Why are coca plants only grown in South America & not in controlled environments throughout the rest of the world?

[Assistant]
Coca is somewhat like coffee growing. It needs very specific conditions to grow and a lot of space, thats why you see coffee grown only in certain areas. Coca needs a high altitude jungle weather (not that unlike coffee) and it also needs a lot of space, you've got to grow a ton of it to make it worthwhile.

It also needs to be done cheaply, and under the radar from authorities (or corrupt authorities), which means places like Colombia and Bolivia are often great spots for this.  Farmers can grow large amounts of it deep in the jungle, get paid nearly nothing, and it can be done quietly. Coca farms seriously get absolutely screwed

It could certainly be grown in other places such as parts of Vietnam or Indonesia, but that has many more issues as drug enforcement for hard drugs is often extremely harsh, so it is far more risky for anyone involved in growing or distributing it. Distributing it is even more important than growing it. You've got to get it where it needs to go... without getting caught. That can be very hard in most of the world

Lastly, the best market in the world for cocaine is in the US, so having somewhat close proximity into the US from South America is great.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Why are antiviral medications so much less prevalent than antibacterial?

It seems like we have a lot of defenses against bacterial infections, and have had them for quite some time.  I'm curious why it appears that anti-viral equivalents are so much less pervasive?  And the ones we have, seem so much more dangerous than the antibacterial counterparts.

[Assistant]
There are fewer unique targets, since viruses mostly use our own cellular machinery. We end up having to target the few enzymes and proteins they have, such as viral proteases or reverse transcriptases. We can also sometimes produce neutralizing antibodies that target viral surface proteins, which opens up some new options, but even there we also have to be careful that the viral epitopes arent too similar to human proteins.

In contrast, bacteria have whole suites of enzymes and proteins that are often unique or significantly different than their human analogs, so we can build compounds targeting them that are less likely to interrupt human cells.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [The Moon is a Harsh Mistress] How much, if any long term damage would be done to Earth after Operation: Hard Rock?

[Assistant]
"A maximum of instructive shrecklichkeit with minimum loss of life."

Operation Hard Rock involved roughly fifty impacts, and maybe half were over the ocean. The lunar catapult used by the rebels fired a standard load - 100 tons of rock in a magnetic steel jacket impacting at 11 kilometers per second, each impact letting six gigajoules go. As Heinlein himself notes, this is roughly equal to a 2-kiloton nuke.

50 x 2k = 1 megaton. So there are lots of demonstratively loud explosions near big cities, but very little lasting damage (aside from the craters at Cheyenne Mountain). Some cities took direct impacts, and there you'd see a lot of lingering health issues even with a relatively low loss of life. Lots of vaporized nasty stuff in the air, asbestos and plastic and all that. Local death rates will trend up.

Lots of pretty sunsets (especially in the Midwest), and local weather disturbances (especially in coastal areas which just got a lot of boiling seawater thrown into the air), but nothing that will be remarkable in a month or two.

The most important feature of the war was the antiballistic defenses which blew up a number of the impactors in orbit. There's going to be one hell of a debris belt left behind, orbiting at random altitudes and trajectories.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: If I'm in an automatic transmission car on a slight hill and I press the gas just enough to stop myself from rolling back, so I'm not moving, how does the engine not stall?

[Assistant] An automatic transmission has a device in it called a torque converter. It is essentially a big hollow donut shaped cylinder with two blades in it, and the cylinder is filled with transmission fluid. When the engine is running but the wheels aren't moving, the blade is just spinning inside the torque converter and most of the engine torque is being transmitted into the fluid. So the engine is still doing work, but it's doing work on the fluid instead of on the wheels.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Marvel/DC] Why is it that most alien races that can talk understand English?

[Assistant]
In marvel they generally cant. Skrulls and shi ar have translator tech. The FF also has something thats popped up for translations.
Skrull and kree who are send to earth as spies have to learn the language.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why can't I move my eyes smoothly without looking at a moving target?

[Assistant]
Your eyes don't "take a picture" of the view all at once, the way a camera does.  Instead, your eyes move around picking out details in your surroundings, which your brain identifies and then pieces together to form a picture of your surroundings.  Your eyes can actually see things in detail in only a very small area in the center of your vision.  You can test this by picking a short word in the middle of a page of text.  If you keep your gaze fixed on the word, you'll find that you can't really make out any of the words surrounding it.  Your brain knows that there are printed words there, but it can't see what the words are.

While your eyes are moving your vision is blurred, just like a video camera when it's jiggled.  So your eyes move in short, very quick bursts, so as to miss as little as possible.  This is called "saccadic movement" or "saccadic gaze."  Watch what your eyes are doing as you're reading this text; they're not moving smoothly along, but are jumping from word to word.

One more experiment:  Move your cursor across this screen, or better yet a screen of text you haven't read yet.  If you follow the cursor with your eyes, the movement of the cursor seems smooth but the text on the screen is blurry.  Now focus on the text while moving the cursor around, and you'll see that the cursor is blurred.  In fact, you might lose track of where it is entirely.  When your eyes are following the moving cursor, of course all they have to do is keep up with the movement; so they don't have to flit around to take in the detail, they just need to keep the cursor in the center of your vision.  In fact, relative to your eyes the cursor is hardly moving at all.

As short as saccadic movements are, there is still a little bit of blurred vision as your eyes move from one spot to the next.  Since your brain can't do anything with the information until your eyes stop at the next point, it "edits out" the "bad frames," replacing the gap in your vision with the last clear image it received from your eyes.

This is why sometimes, if you look up at a clock with a ticking second hand, it seems like it's stopped for just a moment.  It's also why you can never see your eyes moving when you look in a mirror.  Your brain has cut out the blurred stuff in between and replaced it with the last thing you saw.

Every day, about 30 seconds of your life ends up "on the cutting room floor," your own brain having erased it from your experience.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: FXX just paid $750 million for The Simpsons' syndication rights. The Simpsons is a Fox property, produced by 20th Century Fox. FXX is a Fox property, as part of the Fox media group. So, uh, isn't this just a question of in-house money shuffling?

[Assistant]
FXX is part of the Fox Entertainment Group, which is a *subsidiary* to 20th century Fox.

A subsidiary still has its own finances, its own books, its own CEO, etc. The Parent Company might exercise control over the leadership/business decisions of the subsidiary, and will reap the profits of any revenue made by the subsidiary, but the subsidiary is still its own *company*.

So that company still has to pay for syndication rights to the parent company, and that money probably comes out of its own finances.

There was a bidding process, although that might have been skewed by FXX being a subsidiary. It is also possible that 20th Century Fox might provide some financing to FXX. But its not as simple as 'here take some of our money' - there are regulations in place to keep an eye on money that flows in and out of corporations, including from parent to subsidiary and back.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Why do some electrical plugs need to be plugged in the right way (i.e. turned "right side up") and why does it not matter for some of them?

[Assistant] ELIF version - In the united states one blade of the plug is wider than the other so it must be inserted the correct way. Other countries achieve this with other keying systems. These plugs are polarized meaning one connector is the neutral and the other is the energized connector. These polarized plugs allow the device manufacturer to design the product so they will know their power switch will always be connected to the energized lead. So when you turn it off there really is no power getting into the device.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: When I get a bad cold, why does every muscle in my body ache?

[Assistant]
Muscle ache (myalgias) and joint aches (arthalgias) are due to multiple factors, but they can both be traced back to the immune system doing its normal job.

Many chemicals are released anytime a cell is injured (from trauma or infection) or anytime a foreign looking protein (think bacteria & viruses & vaccines) gets into your body. Specific immune cells respond to those chemicals by (1) moving towards the source, and (2) releasing other chemicals (cytokines). This is the beginning of an inflammatory reaction.

Inflammation is simply a word describing the collection of effects that result from those chemicals. They include (a) redness (rubor), (b) swelling (tumor), (c) heat (calor), and (d) pain (dolor). (Yes. Some of those chemicals will actually cause you direct pain, so that's part of the answer.)

Now imagine you just stepped on a nail. Cells are damaged and an inflammatory reaction has been started. Some of the chemicals that are produced at the site of the injury/infection make the blood vessels near your foot get bigger and more leaky. A larger diameter blood vessel means more blood flow to the area, which means more blood cells are nearby. Leakier vessels means that more blood cells are able to leave the blood stream in this local area. This is helpful because you want certain immune cells to collect near the injury site and begin attacking any germs that may have been let in by the nail and to start repairing tissues.

Likewise, a bigger sized blood vessel with more blood flow and more red cells will look more red in color! More blood flow also means more heat! A leakier blood vessel doesn't just let out more cells, but it also lets out more water. Water leaving your blood stream ends up gathering in the surrounding tissues, leading to swelling. Swelling causes pressure and can cause some aches.

The example gave is a nail in the foot. How does that translate to having a cold? Well, the answer is that the immune system doesn't really discriminate and pretty much reacts the same way for anything  it thinks "isn't normal." Having a rhinovirus or the flu virus buys you the same basic inflammatory process. SO DOES GETTING A VACCINATION!
One type of chemical that's made is prostaglandin. Prostaglandin E2 makes you have a fever and directly causes pain. Non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and naproxen, block the production of these chemicals. That's why they are considered a fever and pain reliever.

**TL;DR** When your immune system is doing its job, inflammation helps get the proper immune cells to the invading pathogens, so it can identify it and make effective antibodies against it. The chemicals involved in the inflammatory process are pretty harsh and can have unwanted side effects on other parts of your body. This is necessary for acquiring "immunity." *People often mistake these annoying symptoms for "getting sick" after they receive a vaccination.*


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why are there more visible air bubbles in tap water when it is cold outside?

[Assistant] Gasses are more soluble in a liquid like water when it is really cold, and its solubility goes down as temperature increases. In hot water, a lot of those dissolved gas bubbles have left the water, whereas in cold water, the gas bubbles stay dissolved in the water easily. Thats why you see more bubbles in cold water than in hot water.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How are the lawyers of the wealthy able to get lighter sentences than the lawyers of the poor for the same crimes?

If the laws are the same, then what is it about expensive lawyers for wealthy clients that always seems to lead to lighter sentences for their clients?

[Assistant]
Better lawyers can charge more money because they have more skill. They've got more experience, a better understanding of the laws, and better public speaking skills. They'll produce a better case than a cut rate lawyer because they're better at the job.

That's only part of it though. A rich person won't hire **a** lawyer. They will hire **many** lawyers. Each one can specialize in a certain field, bringing in a better skillset, and the defense team will have multiple people to bounce ideas off of.

A poor person however just gets whoever they get appointed to defend them. Even if their attorney is competent, they simply lack the resources that a rich person could supply.

Edit: Remember, in the US you don't need to be proven innocent to get off scot free. You're presumed innocent, and it's the job of the prosecution to prove otherwise. All the defense has to do is undercut the prosecution. If you can find a chink in the armor and keep pressing it, that might be good enough. Even if the defendant is totally guilty, if you've got enough people who can pick apart the prosecution, it might be good enough for a win.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Witcher] Why aren't the remaining Witchers more concerned that no new Witchers are being trained? Monsters are breeding everywhere, and there will be no one to take care of them after the dozen-or-so living Witchers are killed, eventually.

[Assistant]
Except they aren't, really.

The point is made several times in the games that there just aren't as many monsters left. Sure, there are small fry like nekkers and drowners, but you don't have to be a Witcher to handle those, and the bounties for them reflect that. But the big ones, the kind that Witchers were made to handle, they're going extinct and getting harder to find.

The time of Witchers is ending, and not just because they aren't making any more. The world doesn't need Witchers like it used to, and soon it won't need them at all.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why do exceptionally horrible smells like rotten meat tend to linger in my sinuses for hours after the smell has gone?

[Assistant] I'll let someone else give a more lengthy answer but basically that rotten meat smell has a lot of necrotic fat particles that bind to other flesh very easily. So even when you walk away, they have glued themselves in your nasal passages from the moment you smelled them.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5:Why do bags of dry beans have rocks in them?

Just ordinary bags of dry beans you get at a supermarket. They have rocks mixed in with the beans. Cheaper brands have more rocks, but I think all brands get a rock now and then.

Why do bags of beans have rocks?

More importantly, how do I separate the rocks other than pouring the beans out and physically picking the rocks out as I find them?

[Assistant] The rocks are left over from the soil where the beans grew. Some get picked up in the harvesting process, and those with size and density similar to a bean are difficult to sort out automatically so some are accidentally left in.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Real life applications of paradoxes?

I'm not a philosophy major, but I love the subject and thus I have subscribed to this wonderful subreddit.

One of my favorite concepts to think about are paradoxes. I'm particular to the Paradox of the Heap because I find it very applicable to many real life situations.

I'd like to learn about more paradoxes that can be applied in practical arguments, from politics to otherwise.

So I suppose the tl;dr of this post is to ask:

What's your favorite paradox to reference in real life situations?

[Assistant]
I once heard a conference talk in which someone explained the following "paradox" concerning expert consensus:

Three experts are brought in to determine what should be done about a situation where a well has been potentially poisoned.  Each is asked the following two questions: 1) If the toxicity level is above X%, should we then close the well? and 2) Is the toxicity level above X%?  The three experts answer as follows...

Expert 1: 1) Yes  2) No

Expert 2: 1) Yes  2) Yes

Expert 3: 1) No   2) Yes

If we take the majority decision on each question, it seems that the expert "consensus" is that we *should* close the well if there is X% toxicity, and that there *is* X% toxicity.  Therefore, we should close the well.

*HOWEVER*, if we don't take the most popular expert opinions on each of the two questions, but instead ask each expert if the well should be closed, it would seem that the majority (on pain of violating *modus ponens*) would say that we should *NOT* close the well.

Two seemingly equally respectable approaches (with prima facie innocuous differences) to assessing expert opinion yield opposite results.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
What triggered cosmic inflation?

As far as I know the cause of inflation is debated. Some say it is caused by a phase transition (which I didn't fully understand) which happened when the strong nuclear force separated from the electroweak force. But I also heard that that theory is old and more or less abandoned now. What is the current most accepted theory for what triggered inflation (explained in a non-techincal way)?

[Assistant]
Inflation is driven by a scalar field called the inflaton. (A scalar field being a field that is just a number, at any point in space and instant in time). The inflaton lies initially in an excited state which gives a large constant energy density in space. This triggers a violent exponential expansion exactly like dark energy does now, but at a more dramatic scale.

As the Universe expands exponentially the total energy grows immensely, because the energy density remains constant while the volume grows.

When the inflaton switches back to its ground state, inflation ends and the energy it had is developed in the degrees of freedom we know and love, and we enter what is known as the early Universe  (radiation-dominated). The temperature is probably of order 10^(16) GeV (GUT scale), that's why one gets the prejudice inflation has something to do with grand unification (which is the unification of the three forces of the standard model).

That's the general features of inflation. The different models (i.e. chaotic inflation) propose different mechanisms or details through which the above passages happen.

Inflation is not per se concerned with the origin or nature of the inflaton. Where the inflaton comes from or what it is is a separate, but interesting question. There's many ideas about that too.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Clarification about our position in The Milky Way?

The solar system has been measured to be about 28,000 light years from the center of the galaxy, and about 20 light years above the galaxy's equatorial plane, within the "Orion" spiral arm.  I understand that given what we can see of the Milky Way even with the naked eye, and the knowledge and visual recognition of other spiral galaxies, we can determine the Milky Way is also a spiral galaxy.

1: Without seeing it from the outside, how is it determined that we are out on one of the arms, and how many arms does the Milky Way have?

2: Are all of the stars (yes, stars, not light that is emitted from another galaxy when viewed with a telescope) seen at night contained in our galaxy?

3a: All images of our galaxy in its entirety are obviously an artists rendition or modeled by a computer, how accurate (from a source like NASA) are these images of the overall shape and size of the Milky Way?

3b: Is it our particular "height" above the equitorial plane that helps give us our estimate of what our galaxy looks like?

[Assistant]
1. Star counts.  Lots and lots of star counts.  Mapping the galaxy is a very difficult, pain-staking, and error-prone process.  The basic idea is that astronomers count the number of stars brighter than some value in various directions.  As you decrease the lowest brightness, you probe farther distances.  This is all confounded by the fact that stars have a large variety of luminosities and (especially) there is a lot of dust in the galaxy which obscures light.  The fact that this dust is somewhat clumpy makes the problem even worse.

As a consequence of the dust, we can't really see much of the other side of the galaxy, particularly toward the galactic center, so we don't really know what's going on there.  There could be a dwarf galaxy hiding behind the Galactic center and we wouldn't know it.  (Although, in principle it would be possible to detect something like that due to its gravitational influence on the Galaxy.)

Another technique is to map neutral hydrogen gas by observing the 21 cm line in radio.  Radio waves don't get obscured by dust, so this can be more useful for mapping out more distant parts of the Galaxy.

2. No.  It is possible to detect individual stars in other galaxies, though they are the very brightest stars.  In particular, Cepheid stars are visible.  Because their pulsation period is related to their luminosity, they are used to determine the distances to the nearest galaxies.  The main problem with observing these stars is called "blending."  Because the galaxy is so far away, you cannot distinguish a bright Cepheid from dimmer stars that are near it.  The light from all of these stars then hits the same pixel on your detector.  Although the Cepheid usually contributes a substantial fraction of the light, the presence of these other stars makes precise measurements more difficult.

3a. The size is known somewhat well.  There are some quibbles about the distance of the Sun from the center of the Milky Way at about the 10--15% level, but the overall scale is known.  As far as the shape goes, we know that the Milky Way is a barred spiral.  People sometimes argue about the presence of an additional nuclear bar, but it's unknown for certain.  We know that the disk is warped, but again there is controversy over how much and what the shape of the warp looks like.  We know of the existence of a few arms, but nothing is really known about the arms on the other side of the Galaxy.

3b.  Not really.  We're a little bit above the plane, but not by too much.  Not enough that we would be able to overcome the effects of dust extinction.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why do nearsighted people need to wear glasses when using VR?

The screen in inches from ones eyes, where their vision is ostensibly still good. Yet I see prescription lenses being sold to mount inside VR headsets, and general advice of wear your contacts when using VR headsets. Please help me understand.

[Assistant]
VR headsets are calibrated to project an image that is "correctly" focused for someone with "normal" vision. But this image is a trick; it has to appear to be farther away, which makes the person try to focus like that for realistic graphics. Otherwise, anyone who used VR for any extended period would get eye strain as if they were reading a book inches from their face.

Someone with nearsightedness doesn't have that ability, so even though the screen is inches away, it's projecting an image that is like it's farther away which makes it blurry.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[The Purge]What do I do if my water broke during the purge?

Drive to the nearest hospital and wait it out by the hospital door?

[Assistant] If you're at home, barricaded inside like any normal person, you can do what humans have done for Millenia without hospitals and give birth in your home. If your outside, then you're clearly too stupid to raise a child.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Interested in teaching, less interested in research

Currently pursuing a master's degree in media that is heavily research-focused. I have no problem with my research or the field I'm in, but I prefer plain old teaching over teaching and research. I was contemplating applying to schools for a PhD once I graduate, but I'm wondering if I need to. Can I teach at the university level without one? I understand PhD programs are heavily rooted in research, which again I have no problem with doing, but I'm wondering if this path is necessary if I'm interested more in teaching.

[Assistant]
Technically you can teach intro classes with an MA. You will almost certainly not be hired though because everyone else applying for those positions will have a PhD.

You may have some luck at a Community College.

Realistically, if you even get classes, they will only be adjunct level so you will need other income unless you can get a ton of classes.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Do non-black hole masses emit Hawking radiation?

If I put a massive body in a black box, and didnt know whether it was a black hole or not, would I always observe Hawking radiation? Or is it something specific to black holes?

[Assistant]
Hawking radiation is a particle production effect specifically associated with black holes and event horizons.  Hawking radiation carries away the mass of the black hole, causing it to evaporate, and raising the issue of information conservation (the Black Hole Information Paradox).

Various other particle production effects occur in QFT, but they should be viewed as distinct from the Hawking effect, which only comes from black holes.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: What powers the microchip inside my credit card and the microchips we put in animals as identifiers for vets?

Are they actually microchips or is that a misnomer?

[Assistant]
The reader.

For your credit card it's powered through the contacts, if you mean the visible one. For RFID, they're powered wirelessly, which works fine because they only need a really tiny amount of power.

And yes, they're very much microchips and can run complex code. Most RFIDs tend to be simple -- just spit out a serial number or such. That's probably what your cat has. Now your credit card contains a complete processor capable of doing cryptography and participating in a complex protocol.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: What causes us to wake up in a bad mood sometimes?

You can fall asleep perfectly fine but still wake up irritable for no apparent reason (even when it's when your body wakes naturally). Why is this? Is there even any documented reasoning or is it just luck of the draw?

[Assistant] After a night's sleep, you've gone a longer than usual duration without eating food, drinking water, or moving.  Dehydration, low blood sugar, muscle soreness, or even substance withdrawals (caffeine, cannabis, etc) are almost universally the cause of the grumps.  Drink water, eat something, stretch, get your coffee.  You will feel *much* better.  This applies to moodiness during waking hours.  If something is making you mad, you're body is telling you it needs something, usually food or water.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
How does HIV/AIDS actually kill people?

What's the process to an individual's death by HIV/AIDS?

[Assistant]
HIV preferentially infects a type of cell called a CD4+ T-cell. These cells are commonly referred to as Helper T-cells and are crucial during infection to help stimulate various arms of the immune system.

When someone is infected with HIV CD4+ T-cells are systematically infected and killed by HIV. This eventually leaves the body with little to (in extreme cases) no detectable levels of CD4+ T-cells. This is when the patient is officially diagnosed with AIDS and like the other commenter stated dies from things like the common cold and extremely rare forms of cancer and pneumonia.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How cameramen film actors looking in the mirror without getting in the shot?

Sometimes the camera angle is centered perfectly but there's no other person in the reflection.

[Assistant]
There's a few tricky ways they do this. One is green screening an image onto the mirror, or editing out the cameraman in post production. Sometimes, they'll have an empty frame, or a glass window instead of the mirror & shoot the scene through the frame, so what looks like a reflection in the mirror is actually the actor in the scene.

Sometimes they'll use really tricky methods for mirror scenes: a deleted scene in terminator 2 had an actor's identical twin mimicking the actor's movements while they were in an identical, but mirrored, room which was connected by a framed window so it looked like a reflection.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Harry Potter] I am an electrician working on Grimmauld Place and this junction box has an outgoing wire to a house I can't find. What's going on?

[Assistant]
I mean, isn't it *your* job to find that out? What are you asking us for?

If the place you're looking for is number 12, don't bother. There was a mixup at the city council during construction. But it certainly doesn't use electricity, because it doesn't exist. And even if it did, years of constant magic and permanent enchantments on the home itself would *ruin* the wiring. Electricity acts very strangely around that kind of activity.

If it existed. Which it doesn't.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5 If humans can go weeks without eating, why do we eat 3 times a day?

[Assistant]
So the trick is that you can go weeks without eating if absolutely necessary in an emergency. But your body needs energy from food to work. Everything from breathing to walking to thinking uses energy, and we get that energy from the food we eat.

If we eat more food then we need, the extra energy gets turned into fat and stored in our body in case of emergencies.

If we don't have enough energy, our body can break down stored fat and muscle and turn that into an emergency supply of energy. But it can only do that for so long, and doing that makes us tired and weak.

Eating regularly is better for our bodies, because we get the energy we need to survive.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: What's going on when you get that tingling feeling in your body after seeing/hearing something you feel is profound?

It's kind of difficult to explain but whenever you hear some very good lyrics in a song or you see a movie trailer that absolutely hooks you this feeling starts.  Almost like a kinda good tingling feeling in your head and body, also my peripheral vision will start to fade when this happens.  What is my body actually doing when this happens?

[Assistant] Some people call it autonomous sensory meridian response (ASMR). No one is really sure why this happens, but it occurs because your senses have encountered some stimuli (visual, auditory, etc). Some psychologists support its existence and say it produces similar effects to meditation, but there is not broad agreeement about why this happens.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why do people put cologne/perfume on the insides of their wrists?

[Assistant]
I've heard 2 explanations - can't vouch for either.

1. Wrist have a lot of blood flow near the skin and hence produce a lot of heat. Heat helps release the scent.

2. Wrists are an area that are likely to get closer to other people. Guess they also always exposed where much of the body isnt.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How do gas masks work?

Like how do you get clean air in the gas mask when there's contamination around? Is it some sort of filter?

[Assistant]
There are 2 types. One type is a air purifying, the other is air supplying.

An air purifying would use filters of different types to "clean" the air you breath. For instance, a P100 air filter would clean out dust and debris, as well as some organic material.

Air supplying is obviously, as it sounds, providing you with fresh air from a hose, usually attached to a bottle, with compressed air.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Eli5: how does cancer spread from one part of the body to other parts?

[Assistant] Cancer spreads through a process called metastasis. In metastasis, cancer cells break off from their original location, travel through the lymph system and your blood, and form new tumours in other parts of the body.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[DC Comics/Batman] The batman and his friends have those crazy harpoon/grappling guns which punch holes in the buildings all over Gotham... who is paying for the repairs? Does the city have a "Batman repair budget"?

"Robin, its a quiet night for crime. Break out the plaster and silicon."

[Assistant]
Movie Batmen tend to shoot a piton device that actually punches in and anchors like a harpoon. Comic or animated Batmen are much more likely to fire a "gripper" claw that's more nondestructive. The point being if you shot a person with the movie pitons, you'd make a screaming bloody mess, while Batman sometimes uses the gripper as a tool to catch someone's arm or a desperation weapon to knock a bad guy off balance.

The piton type does leave a hole, but very likely its function requires a small one. Puncturing/splitting the material of the building wouldn't promote a good "stick" and an anchor point you can swing from. More likely it's designed to slide into a variety of materials tightly, like a sliver in your skin, and withdraw leaving only a small mark.

A more exotic possibility is that a replaceable tip is involved. The piton goes in, and when Batman is ready to swing away, he works a control that makes the grappling hook discard that tip and load in a fresh one. The one left behind is treated to weather away when exposed to oxygen for very long, but the part sunk in the building remains, barely even visible. Fixes the holes in buildings and the "But how do you make your grappling hook let go?" issue in one swoop.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Why do Scientists Bombard Specific Elements to Create New Ones?

For Oganesson, it was Calcium and Californium: 20 + 98 = 118. But why not just Praseodymium and Praseodymium? If you bombard element 59 with element 59, shouldn't it also give you element 118?

[Assistant]
There's a lot of things to consider when designing these kinds of experiments. They're fixed-target experiments, so you have a beam and a target, and you have to choose materials for both that are convenient/possible to use.

Also, you have to consider what nuclides are likely to be produced by the reactions. The typical way that these experiments are done involves heavy ion fusion-evaporation reactions. That means that the beam energy is in the range such that the two heavy ions can fuse together and create an excited compound nucleus. The compound nucleus then "evaporates" particles (primarily neutrons and gamma rays, but also protons, alpha particles, etc.). You want to maximize the probability that the final product is the nuclide of interest.

There's some relatively narrow range of energies that will work, because if the energy is too low, the Coulomb barrier will make the fusion-evaporation cross section too low to finish the experiment in a reasonable amount of time, and if it's too high, the compound nucleus will be more likely to just fission rather than ideally losing a few neutrons and remaining a superheavy element.

Since the Coulomb barrier energy is proportional to Z*_b_*Z*_t_*, where those are the atomic numbers of the beam and target, it's worse when the two have roughly equal Z. You get the benefit of a lower Coulomb barrier, so more manageable cross section, if there's a big asymmetry in the beam and target Z.

So with all of that in mind it turned out that for this particular case with the accelerator available, it was determined that a calcium-48 beam (a doubly-magic, effectively stable nucleus with a bunch of extra neutrons) with a californium-249 target (a heavy nucleus with a lot of protons to bring the charge of the compound nucleus up to 118) was the optimal choice.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [General] why does Santa give rich kids the best presents? Does Santa hate the poor?

[Assistant]
Santa once gave really expensive presents to the poor kids. Their parents sold the presents so that they could have money to make rent. Santa took that as a personal slight, and decided that as his goal is to give toys that the children will play with rather than giving money to the parents, that he should instead give presents to children based on their economic level.

Attempts to convince Santa that he may have gone too far have not been successful.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Super Mario] How successful at being a plumber is Mario?

Between all the games he spends his time participating in rescuing princess peach or being at the Olympics or driving a kart it makes me wonder how much time he has leftover to devote to the endeavours that pay the bills.

Also, if his dialogue only stretches to the few famous phrases we've heard him spout over the years, how does he provide a quote or an accurate explanation when he identifies the problem with a clients pipes?

[Assistant]
Mario is a plumber of trade, but remember that the sewers, underground and pipes of the Mushroom Kingdom are magically infused. The skills he learned navigating and repairing these systems, have proven invaluable to his adventures.

He is not doing much actual plumbing these days apart from the odd favor to his friends. This is due to his inofficial status as Royal Consort, and official status as Hero of the Mushroom Kingdom. He recieves a fair fee for his services from the royal court itself, and has accumulated great wealth from his numerous adventures.

As such he spends a lot of time training, socialicing and adventuring. Sport events hosted by Mario are wildly popular, and attracts tourists from all the other kingdoms - bringing revenue. He also holds a permanent position in the Royal council, although it is unknown if he recieves pay for this.

Still, Mario has demonstrated that in the event he is travelling and finds himself short on cash, he is not above taking odd jobs to fund his travels.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Civil War Spoilers] Why didn't Iron man just X?

When Iron Man, Cap and Bucky fought for the last time, Iron Man was getting defeated by Cap, after he blew Bucky's arm off. But as a counter, he had Friday analyse the fighting technique of Cap and defeated him easily. If it was this effective, why didn't he do that earlier?

[Assistant]
Even if Tony is a genius who can build sentient A.I. which can adapt the suit to certain fighting styles, it looks like Tony is kind of a test pilot for his own inventions, like in Ironman 1, when he actually tries how high he can fly, almost killing him in the process.

I think this 'feature' of the suit/Friday was just a ~~Beta~~ Alpha version, he had never tested it, and kept it as a 'Joker', which might as well fail badly. He just relied on safer/tested methods until that point.

That it worked so well was pure luck. When Spiderman fought Captain America in the comics, he also thought about how he 'studied Cap's fighting style', only to get obliberated by Cap, because 'it is not a fighting style, it is just one long, perfect movement' (not finding the quote, but that was the quintessence).


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Bruce Almighty] Why did Bruce not create a program that answers all prayers?

[Assistant]
He was new to the whole omnipresent, omniscient, omnipotent experience and couldn't really handle it on a single city limitation. So his powers were not fully utilized. He was also not very tech savvy, so creating a program probably was not something he knew about.

A better way was to stop time and see all prayers he would get for the next 100 years and just answer them then and there and be free for 100 years without wasting any time for him. But again, he wasn't tapping the full potential of his powers.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Looking at stars on a clear night, why do they seem to be gently flickering?

[Assistant]
Its because of the atmosphere.

The atmosphere isnt at a uniform temperature.  There are warmer and cooler pockets of air, as well as a temperature change as you increase in altitude.   All this uneven temperature causes the air to sort of mix and undulate a bit.  Hang gliders use that undulating air to stay aloft, but the downside is that it can mess with stargazing.   If youve ever seen that shimmering mirage on a very hot day on a road in the distance, whats caused by the hot air rising off the asphalt, its the same phenomenon youre seeing when stargazing: different temperatures of air moving about.   Those different temperatures (which results in varying air density) affects the direction of rays of light going through it, like starlight.   And so, as the warm air rises off the earth, you see a twinkle.

Fun fact:  why did they make the Hubble Space Telescope?  No atmosphere = no twinkling!


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[MCU/any relevant Marvel universe] On Pym Particles and mental stability (mild movie spoilers inside)

Hank Pym says that he cannot be the one to use the suit due to it having taken a toll on him over the years.  In addition, Darren Cross is shown to be a bit nuts as he works on perfecting the Yellowjacket suit.  This shows that prolonged exposure to Pym particles can cause issues with psychosis.  However, nobody has a problem with allowing Scott to wear the suit.  Is he truly "expendable" as he himself says to Hope, or is there something about him that lets him use the particles safely?

[Assistant]
Having read a good deal of Marvel comics and seen Ant-Man, here goes.

1) "The Toll" is likely figurative. He can't put on the suit because the last time he wore it, his wife died. Bringing back that kind of emotional pain would cloud his judgement, and jeopardize the mission. On top of that, Pym is far past his physical prime, so he would be at a great disadvantage if forced to fight opponents of the same size (either normal people while he's normal sized, or anyone shrunk down via Yellowjacket suit).

2) Darren Cross was likely already paranoid, obsessive, and jealous long before he began working on replicating Pym Particles.

3) Pym said that exposure to Pym Particles while unprotected was dangerous, specifically the head. All of Cross's failed experiments were conducted on unprotected subjects. It is possible that Cross was exposed to some amount of Pym Particles, inducing psychosis.

4) Pym chose Scott because he was a very capable thief, adapted to new situations fast, and was a decent man. Pym couldn't bring himself to risk his daughter's life the way Janet did, but also couldn't hand the suit off to someone who he suspected might just take the technology for themselves. Pym obviously didn't want Scott to die.

Comics: In the comics, Hank Pym was both Ant-Man and Yellowjacket. He developed split personalities as a result of the stress of his work. The psychosis in the movie, as well as Pym's comment that he "saw himself in Cross", are likely references to this.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] How do animals get their "hard wired" instincts in the first place?

[Assistant]
Science teacher here: This is best explained by evolutionary theory. Hard wired behavioral instincts are those most likely to be selected on by natural selection. If a behavior is innate, meaning it is not something the animal learns, but rather something the animal does because it is specifically coded in the genes, then the behaviors that do not benefit the animal for its environment will be selected out. Those beneficial behaviors will pass genes on to the offspring.

If you are asking how is it behaviors are coded through DNA, then its a little bit more difficult to explain. Because DNA is incredibly complex, the genes that code for specific behaviors can be difficult to decipher. However, behavior is really just an extension of a complex interactions of proteins. The simplest kinds of behaviors, like those demonstrated by bacteria are the the easiest to consider. Bacteria that demonstrate a tendency toward or away from light can extend a evolutionary advantage under certain conditions. For example, avoiding UV light as Neil De Grasse Tyson explains in the most recent episode of Cosmos. This is a behavior that is hard wired and is simply a complex protein interaction that causes the bacteria to avoid UV light. Behaviors have gotten more complex, but if they are the innate kind, then they are just part of a line of increasingly complex protein interactions going on inside the animal, dictated by DNA that has been selected on by natural selection.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Batman] I am an otherwise honest guy who was laid off from work, and I have to rob someone to help feed my family. How does Batman treat me?

[Assistant]
Depends on how how you behaved during said robbery.

If you actually hurt people during the robbery and try to fight Batman when he catches you, you will end up in police custody with injuries proportionate to how much grief you gave him and everyone else.

If you didn't kill anyone, you'll serve your time, but upon release you'll get a job offer from a Wayne Enterprise subsidiary looking to hire ex-cons who are repentant and legitimately looking for some honest work.

If you take said job, you might even end up meeting Bruce Wayne from time to time who will show a surprising amount of interest in how your work is going, and if things are ok at home.

If you were breaking into an empty store or house after hours, unarmed, and Batman catches you, you could immediately surrender, tell him your sob story, and if he's in a particularly generous mood, he might actually let you go, but only after taking down your information and letting you know he will be checking in on you and making sure you're making good on your second chance. He might even refer you to a community center or job center run by Wayne Enterprises that can help you and your family out while you're trying to get back on the right path again.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Marvel/DC] What does Wikipedia look like? Does it have information on cosmic beings? What sort of obscure facts about superheroes and aliens could I find on there?

[Assistant]
Major public heroes, it likely has a lot of surface level information on- you could probably find out superman's public appearances, powers,weaknesses and enemies. Likewise major supervillians who are in the limelight- you could get the joker's past crimes (he may well update it himself). Big teams will have headquarters and rosters and leaders and such like. Very large concepts, like the mutant gene, will have scientific pages.

More secret/esoteric stuff is far sparser, simply because fewer people know enough to edit. Subtle heroes like daredevil and batman are more in the vein of urban legends then superheoes. Most interdimensional and extraterrestrial information is vague at best: you might get that Krypon is superman's dead home planet, but that's about it. Likewise concepts like the Speedforce or the Green or the Infinity Gauntlet- likely just a short article with "we don't know much" at best.

Generally, it would be much like any other topic- a good starter but no substitute for in depth study. You could learn who superman is and where he's been seen, but its not going to get you an in-depth analysis of kryptonian biology.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Do babies smile when they're happy because of social conditioning or because its part of their biological programming?

[Assistant] Babies that are blind from birth do start smiling at about the same age as non-visually impaired babies. They also have most of the same other facial expressions, e.g. fear, disgust, etc. This strongly suggests that facial expressions, at least the most common ones, are biological rather than social. In addition, there's the fact that these expressions have the same meaning from culture to culture around the world.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Star Wars] If a brain transplant was performed on a Jedi, (if Anakin's brain transferred to a non-Force sensitive person), would they still be able to use the force?

[Assistant] I'd say probably not. In Legends a Jedi called Callista transferred her spirit to an imperial dreadnought "Eye of Palpatine" in order to save her planet. When her spirit then inhabited the body of a Jedi she still couldn't touch the force, even after her and Luke traveled the galaxy trying everything. It's still possible because in this case no organic matter was transferred between bodies.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Wars] Did Vader order his aunt and uncle killed? Did he even know they were killed?

Did vader have any opinion on Beru and Owen?

[Assistant]
Yes he ordered their death but its a bit unclear if he ordered out of spite or just as a course of action. Vader was leading the search for the plans on Tattooine, the one place in the galaxy that he hated above all. After finding the Jawas the orders were to kill them all and make it look like a random Tusken Raider attack, to ensure plausible deniability, remember the Death Star was still a secret at this point and it wouldn't do to have the whole galaxy know you lost the plans for it already.

So when they tracked the droids to the Lars' farm, they afforded them the same courtesy as they did the Jawas, for the same reason.

Now Legend has it that Vader ordered the comlink to remain open while they were killed, but we are unsure if that truly happened.

The fact is, Vader didn't really care one way or another about Owen and Beru, they were people he met once at a very terrible point in his life.

Oh and BTW they are his step brother and sister in law, not his aunt and uncle.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Is it possible for two sounds two cancel each other out?

[Assistant]
Sure, this is how noise cancellation works, as in noise cancelling headphones.

Let's say you have an external sound. The sound hits the outside of the headphone housing and is picked up by a microphone. The microphone then inverts the soundwave and plays it through the speakers, carefully timed and adjusted in intensity to exactly cancel the incoming sound. This works pretty well for lots of sounds but it's hardly perfect since sound isn't unidirectional.

Sound cancellation also works by accident. Let's say you have a concert outside, the sound you hear will be coming directly from the loudspeakers. If you have a concert inside a room (or a hall) then the sound you hear will be the addition of the sound directly from the loudspeakers as well as from lots of reflected soundpaths. If a venue hall is designed poorly, or not designed for sound at all, then there can be "dead zones" in the room where certain frequencies of sound are mostly cancelled (because sound from multiple paths meet there out of phase).


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Why is taking hormones not more common?

I read another thread here that mentioned estrogen and how it affected body shape etc. Transgender people seem okay taking what I imagine is large amounts of hormones? Why is it not normal for people to supplement, especially as they get older and have lower testosterone and estrogen levels.

[Assistant] Need to be careful. Giving someone estrogen on its own will increase risk of uterine cancer (and breast cancer potentially). People do often use hormone replacement therapy after menopause which is a combination of estrogen and progesterone.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] How does a flu vaccine lessen symptoms when you catch a flu variant that isnt one of the variants in that seasons vaccination?

[Assistant]
First, we have to understand how vaccines work, in general. The basic premise is, we take a virus/bacteria and break it down into large chunks. These chunks are the outer shell/wall of the virus/bacteria, and as with most other cells, there are proteins that are embedded into them for communication, transport, etc.

Second, we have to understand how the immune system works. There are two phases, the innate phase and the adaptive phase. The innate phase is the first line of defense. Your body recognizes something is foreign and tries to get rid of it. It knows this due to the proteins in the wall chunks, as they don't have "self" displays within them. Once they're cleared, your immune system will begin developing other proteins (antibodies) for the adaptive response in case of a repeat infection. If you get infected with the same proteins, your immune response is much quicker as the antibodies alert better killing immune cells to Ninja in and eradicate the problem.

The issue with the flu is that it mutates a lot. Changes to the DNA and RNA subsequently change the comms proteins on the viral/bacterial walls. It might change some greatly, some not at all, but the reality is, there are some antibodies hanging out that can still tag some portions of the cell for removal. They can't tag them efficiently, or in great numbers, but it reduces the viral load down to something more manageable by the innate system than if nothing at all. Your fever spikes, you feel like crap for a day or two, but by them time you've truly noticed it, your innate system has already turned the tide and is just killing off stragglers, all the while making more antibodies for the new proteins. The new antibodies begin circulating while you have the adaptive system out in great numbers already, so they begin to work quickly as well, further reducing your infective time.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why do we need REM? Why could't we just close our eyes and dream?

Also exactly what happens during REM?

[Assistant]
Imagine the brain as a large warehouse.

Whenever memories arrive, they are shipped to the warehouse and stored. However, each memory shipment contains many parts all bundled together such as the feelings you had when you experienced the memory and the sensory data from the parts of your body. There is not enough time to sort through the shipments when we are awake because there are always new memories that are being made!

Sleep is the period when the memory actually gets sorted. However, the warehouse has to go through some changes before the sorting can start. One example is that the warehouse has to disconnect itself from your muscles so you won't be flailing around during your dreams. Your shipments of memories reduced which is why you can often forget what you were dreaming about.

It's during REM sleep where the memories are actually unpacked and sorted out. Some parts are thrown away while others are moved to long term storage. Your dreams occur when you are slightly conscious to see some of the memories moving around.

If we instantly go to REM sleep and start moving memories, we would get what are known as hallucinations. Basically, the act of moving memories may produce dreams that in turn, generate new incorrect memories. This can actually cause havoc to what you perceive as real or imaginary. The other problem is that moving memories sends signals to our body to move around. That would be rather bad if we start flailing around every time we close our eyes.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Ferris Bueler] Ferris has skipped school nine times without his parents knowing. Why did he bother faking sick this time?

[Assistant]
Do we know the previous circumstances?  Do we know he didnt fake sick before?

Regardless, if he KNOWS he has been absent several times and that it may affect his record, then it may be beneficial for (this time) to also have his parents endorsement as an excuse.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
CMV: When suing a public entity, "undisclosed settlements" should not be allowed.

Was reading about the shooting of Charles Kinsey. I had heard of the case before, but after a reply in a comment chain I had replied to I decided to read about it again.

Long story short: an autistic patient had run away from his group home. While cops were searching for a suicidal armed man, they came across the pair. While Kinsey was begging for his client's life, a cop shot Kinsey in the leg while his arms were raised. Luckily, he survived. Latee the cop replied "I don't know" when asked why he shot. I'll leave that there for you to research since it's not the point of the post.

The shooting was bad enough, but ~three years after the shooting a settlement was announced between the city of North Miami and Mr. Kinsey, the results of which are "undisclosed".

Why is it that authorities can settle and pay out a lawsuit with taxpayer money whilst not disclosing to the taxpayer what the bill is? I understand keeping some funding/budget issues a secret in, say, issues of national security. This almost *certainly* isn't that.

My view is that this should not be allowed. Taxpayers should be entitled, for the most part, to see where their tax dollars are being spent.

[Assistant]
It seems that the general public would, in theory, benefit from this knowledge (albeit it's not as though they would be able to vote directly on it or do anything about budgeting), but this could hurt the victim.

Confidentiality tends to encourage faster and higher settlements for victims, and can keep their trauma out of the spotlight, potentially allowing them to heal more quickly. Additionally, it allows for the anonymity of those victims who choose not to be identified.

In weighing the benefits for the public versus victim, it seems more important to give the option to the victim. While the public could technically call lawmakers or protest etc. if they don't like the amount of one particular settlement, at the end of the day the mere knowledge isn't really doing much whereas saving the victim from having to come out publicly, endure a trial during which they relive scarring events, and face lower amounts of payment for the pain they've endured seems to offset the public benefits.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why do songs get stuck in the head?

Why does it happen? Is there a reason some songs show up? How can a song I haven't heard in years pop in there and later be one I heard five minutes ago? Is there a process in which the brain plagues me with Spice Girls at 5 AM?

[Assistant]
There are a lot of different theories as to why exactly (and there's a Straight Dope article that lists a bunch), but I'll cover a few.

It's probably safe to say that a song that could get stuck in your head probably has a catchy beat and is fairly simplistic. However, it's also probably the vocals that you'll keep hearing repeated in your head (simpler), and there might be a few reasons why.

Most likely is that your brain is just repeating a familiar part of a song and the more you try to ignore it, the longer it repeats. Also, your brain may be trying to remember the song for later or just try to recall the song but something isn't working. Maybe you can only remember parts of the song so it keeps repeating.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Mad Max: Fury Road] The filmmakers have confirmed that the majority of the film takes place on a dried ocean floor. There is also vast amounts of water underground. With only mentions of nuclear war and "water wars", where did all the surface water go and what could cause this?

Since water doesn't just disappear, where has it gone?

[Assistant]
I can think of a few things. But mainly it gets seeped into deep undergrown reservoirs that the survivors cannot reach. There is also the idea that there is water elsewhere but it became super salient and the people don't know how to get clean drinking water out of it. Another possibility is that there is water elsewhere but the location of Mad Max has been cut off from the source point but geological activity.

One terrifying idea is that prior to the events of the movie, someone figured out how to use water as a weapon and literally ripped water apart to deny their enemies drinking water. The hydrogen and oxygen would still be in the atmosphere, but may not have the time to reform in the years following the wars.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
You have a stopwatch on Earth, and one in the center of the Milky Way, and you start them at the same time. In 10 years, what would be the time difference between the two stopwatches?

We have to adjust the clocks on satellites to account for their speed in relation to us. We must be moving very fast across the ecliptic of the Milky Way, in relation to the center. I wonder how much the difference in time will be.

[Assistant]
Part of the reason clocks on satellites don't experience the same rate of time passage is due to gravitational time dilation.  The clock closer to the source of gravitation moves more slowly than a clock farther from that source.

That said, motion is also a factor.  The speed of the solar system relative to the center of the Milky Way is about 220 km/s, which is only .073% of the speed of light, so the Lorentz factor is still pretty close to 1.  The actual value is about 1.000000269, meaning we experience time at a rate that is 0.000027% slower than that at the center of the galaxy.

This equates to a little more than 2 hours and 21 minutes per 1000 years.

Edit: Just saw "10 years" in the title.  Over 10 years, our stopwatch would only experience about 85 seconds less time than the stopwatch in the Milky Way center.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: why do politicians and the media never just call people liars?

[Assistant] Because that can be considered defamatory, leading the person to file, and win, a lawsuit against you. This will have the effect of making them look like a victim, and making you look like an asshole while paying them a bunch of money.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why is pain amplified when the temperature is lower?

[Assistant]
The nervous system has a threshold for pain.  If someone brushes your skin, that contact doesn't come even close to the threshold over which your nervous system decides that something hurts.

So basically, things hurt more when it's cold because the cold external temperature is already stressing your nerves.  Feeling cold can be considered a form of "pain," so when something additional happens- say, you stub your toe and your feet are already cold- it not only crosses the threshold of "sensation vs pain", it ROCKETS over the threshold.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: What does the crisper drawer in a refrigerator actually do? How does it work?

[Assistant] The crisper acts like a separate container keeping the mositure of the vegetables in a small area where if it was on the shelves the moisture would fill the whole refrigerator and be lost every time the door is opened. It's really nothing fancier than that. Some crispers will have a little slider or lever that opens and closes a vent to release more or less moisture.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[DC] how powerful is booster gold? What are some cool things that he has done.

I remember everyone freaking out over booster gold, and fanboying over him, I wanna know what the hype is about?

[Assistant]
Booster Gold has a power suit from the future that provides a decent amount of super strength, forcefields, energy blasts, and a visor that provides different modes of enhanced vision. He has time travel tech incorporated into his suit as well as being able to fly with his Legion ring.

Booster dosent have many combat feats, but his force fields are pretty damn good. He's taken hits from Doomsday and kept going. Honestly with his strength and durability he could probably take down most average supervillains, but his arrogance causes to aim above his weight class.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[TMNT] How long will the turtles live

At one point one of the turtles mentions that a few years is nothing to a turtle, as a normal turtle will live upwards of 100 years. But the teenage mutant ninja turtles are larger, and far more agile than normal turtles, thus they probably have a faster metabolism. So would the fact that they are essentially half human mean that they would have closer to a human life span?

[Assistant]
They'll 'live' until the sewer-dwelling hermit that calls himself Splinter dies twitching in a forgotten tunnel from the same toxic waste poisoning that's causing his hallucinogenic coma-dreams of turning into a rat and teaching martial arts to a bunch of walking turtles.

With his last, gurgling breath, he will whisper "Kowabunga, dude," imagining one last pizza party with the four students he never really had.

Weeks later, the discovery of his corpse will be used as a rallying cry by environmentalists against the unregulated dumping of industrial waste, eventually triggering the formation of the eco-terrorist organization that now calls itself 'The Planeteers'.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Using title 'Dr.' on resume

If you hold a PhD and were applying to non-academic jobs, would you include the title 'Dr.' before your name on the top of the resume? (Dr. John Doe)

Or would you write as follows? (John Doe, PhD.)

Or would you just list that you have a PhD in the education section? (John Doe)

On my academic CV I just write my name (John Doe) because education is the first item listed. From what I've seen my supervisors format their CVs the same way.

For a resume in a non-academic sector however, education is often listed further down the resume and is easily lost under nebulous headings like "skills".

I couldn't find any authoritative take on the matter published online. Links or suggestions are welcome.

I want to foreground the fact I have a PhD as this would likely separate me from many other candidates. However I am concerned about coming across as too formal or elitist.

With more PhD holders pushing non-academic careers I wonder what the convention is regarding this question.

Edit: Thank you everyone who replied. The most popular opinion is to write John Doe, PhD (when crafting a CV in North America).

That's also what I agree with and will do.

[Assistant]
I've seen "John Doe, PhD" but not "Dr. John Doe".

You could also just list education first if that's what you want to emphasize. If you've recently finished, your PhD is your most recent job. You can rearrange/deemphasize it once you have relevant industry jobs.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5:When I'm tired, why do I feel a burning sensation in my eyes?

[Assistant] As you get more tired, your body tries to shut down so you'll go to sleep. That affects the amount of tears that are released by your tear (lacrimal) gland. So, less tears flowing, eyes dry out, and it burns. What's your body's solution to that? Close your eyes to cover the dry surface. Which, when you close your eyes, your body will also want to sleep. The burning is telling you to close your eyes and go to sleep.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Batman] So the joker kidnapped Nightwing and I'm the only member of the jokers gang who knows where both of them are....

I know the bat is after me so I ran but it's only a matter of time before he catches up to me. I know he won't kill me and I won't tell him anything so basically how screwed am I? How far will the bat to get the information out of me?

[Assistant]
Ok buddy, deep breath. The joker is a sick fuck, and you have every reason to be afraid of him. That said, you should be much more afraid of the bat. The joker will kill you. The bat will torture you, cripple you, and lock your ass in jail, where you will be killed by joker thugs for cracking under the torture and telling Batman what he wanted to know. Yes, you will break. Doesn't matter how long, YOU WILL TELL.

If you want to avoid a lot of pain, suffering, jail time, and a shower time shanking, you need to tell batman everything. He knows what the joker is capable of. He knows the kind of power joker has over people, and he knows that no matter how long you've been a thug, goon, or mook, there's still a chance at redemption.

When Batman finds you, surrender immediately. Tell him what he wants to know, and beg him for his help. He's not about to throw you bad to the joker, though you shouldn't be surprised if his idea of witness protection involves leaving the country...permanently.

Also, he's probably already got eyes on you. You used the internet to post this question, you're using it to read the answers, and he's been tracking your location ever since. Seriously, Batman is probably looking over your shoulder right now with a bemused smirk.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Star Wars] Given the obvious advantages of a robot army, why were they made so inefficient?

A droid army should be able to communicate wirelessly, have perfect aim, act in perfect unison, flawlessly execute and react to any strategy, and be so heavily armored and mobile that conventional weapons are useless.

Instead the Separatists made an army of weak robots with terrible aim that are laughably foolish and borderline goofy.

Why would you ever make an army of robot Jerry Lewises?

[Assistant]
The hardware designs were intentionally economical because they had to be mass-produced (advanced units like Destroyers were in production, but very very slow and expensive to make). They were working out the software glitches, but Sidious forced them to act before they were ready. They expected their enemies to surrender at the sight of their arrayed troops, but that didn't happen.

After all, Sidious didn't need an army of robots. He needed an army of clones.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[The Addams Family] [Wednesday] Why was Wednesday so mean to Pugsley?

In the original Addams Family movie, Wednesday and Pugsley are always trying to kill each other. Knives, electric chairs, poison, etc. But, in the new Wednesday TV series on Netflix, Wednesday saves/helps Pugsley.

[Assistant]
In the Addams Family movie continuity, the whole family seem to be able to survive extreme methods of torture/pain. (Even Fester/Gomez talk about the things they did to each other as youngsters) Regular siblings torture each other all the time so that's how the Addams siblings interact.

In the Wednesday continuity, Wednesday gets upset that someone besides herself feels they are entitled to torture Pugsley.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Scientific basis for thinking that old stuff was better? Ex: every generation seems to think snl was best when they grew up with it. Is there an "old stuff was better" syndrome or something?

I think it has something to do with just remembering the good and not the bad, making music etc. from earlier times seem better than what we have now. Is there a scientific explanation and name for this?

[Assistant] Your brain has all these little rules which enable you to make complex decisions quickly. These produce cognitive distortions, which tend to make people overgeneralize or be dichotomous in their thinking. This means that they tend to take a few instances of an event, and give it more weight than it realistically should have. Dichotomous thinking is where you tend to see things as being all negative or all positive. There's other types of distortions, but yes, it's the factory programming that gets us every time.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5 What causes you to see things out of the corner of your eye when nothing is actually moving or there?

Why do people have the sensation of seeing something moving out of the corner of their eye when there isn't actually anything there or moving?

[Assistant]
There could be any number of factors for this. A common one is that despite the sense that your vision is steady and focused, your eyes are actually constantly moving and adjusting the field of view very subtly, and the differing images are compiled and averaged in your brain. Particularly sensitive areas of vision, such as motion of the periphery (which might have evolved to detect ambush predators such as wolves or great cats attacking from the sides), will be able to pick up the subtle shifts of your eye movements given the proper context or backdrop.

Another contributing factor is that your eyes' contents themselves are not uniform. Small amounts of tissue can become dislodged in the jelly of the eye, and as it floats may cross in front of light entering the eye, which you can see as motes or "floaters". If one of these motes crosses the sensitive peripheral vision, the motion could also be detected.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[LotR] How long did it take Saruman to build Isengard's army?

What's the time scale from the initial order of *"Build me an Army worthy of Mordor"* and the battle of Helm's Deep?

The films don't give much indication of how much time has passed, and Frodo seems to imply that from leaving the Shire to attending Aragorn's coronation was 13 months, unless I misunderstood. That's a very short time to produce 10,000 Uruk-Hai from nothing.

[Assistant] About ten years after Sauron was ousted from Dol Guldur, Saruman was enticed into darkness via his palantir. He slowly gathered his armies of orcs, men, and his uruk-hai over the 70-ish years between Bilbo's adventure and the Fellowship of the Ring's formation.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: why did two sexes become necessary for procreation instead of one that handled both aspects?

[Assistant]
genetic diversity. what you suggest is asexual reproduction which many bacteria and some aquatic life here and there do. the issue is that every copy is more or less identical to the first. why is that bad? well, a single disease could now wipe out an entire population. more so no form of reproduction is without glitches here and there and now that bad trait will be copied for every and the species ability to survive decreases.

sexual reproduction ie mixing of two brings in a lot of diversity in the gene pool. yes certainly you can get all the worst traits mixing but you also get a case where all the best ones can mix and you get a super awesome offspring who will go on to likely make more super awesome offspring. that's why sexual selection is such a big thing. they want the best mate to ensure their offspring has best chance of surviving. why mutts ie dogs of unknown breeding are usually much healthier than purebred dogs. they are mixed with everything and are likely to be really hardy and resistant to a lot of stuff.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Has there been any research done on the effects of divorced parents bashing their exes in front of their kids and--if so--what effects have been noted?

My sense is that this is a common occurrence that likely has consequences for the children. Any thoughts on the matter?

[Assistant] I cant think of a specific article or research, but it does exist. It is called parental alienation if you want to look it up and see what research has been done in that area. Its mainly used by the parent to get the child on their side and pity them and view the other parent as evil and responsible for the divorce.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: How does Bill Nye get so much credibility?

[Assistant]
This one is hard to answer objectively...

I think the main thing to consider is that Bill Nye made science *interesting* to an entire generation. Since he was covering simple science that we could easily validate or try for ourselves to see it was true he created trust. We could see his kid friendly diagrams and experiments and say, "How neat!" We would later find these things to be true in science class.

He became a household name in science, just like Stephen Hawking or Einstein. When his show was taken off the air he was remembered as being friendly, trustworthy, and knowledgeable to millions of people.

Then of course he would appear on cable news channels, where anyone can appear genius when surrounded by foam-mouthed journalists. They would typically bring him on the show to talk about a part of science that the general population can easily understand (or at least be aware of). He becomes, and remains the face of science for decades.

His new show tarnishes all of this because it does not resonate with the majority anymore. (Plus, it was generally a horrible show)


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How are cars able to go 100k+ miles with little maintenance like oil changes, tire replacements, etc.?

Theres so many moving parts. The parts are exposed to temperatures of below freezing to above 200F within the engine. Its crazy to me how these machines are able to withstand so much for so long without breaking more often.

[Assistant]
Ive worked for automotive and aerospace companies.

Nothing is half-assed.

Say you want to use a bolt inside a car engine thats made by a new supplier.  Even if its the exact same size, material and specs as an old suppliers bolt - you cant just use it.

That bolt needs to be tested and the suppliers manufacturing process needs to be inspected to make sure there wont be future variability in bolts that are manufactured. Bolts that show up at the factory are documented by the manufacturer assuring that processes were followed and that they were inspected.  The factory will also pull a few to inspect out of the lot.

So imagine this with every single one of the 10,000 parts that go into a car.

That is just the manufacturing process after the car is designed. The design process is just extensive as well going through lots of analysis and testing.

With over 100 years of experience passed down and built upon, machines like cars are incredibly reliable.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why we have only 118 elements in periodic table?

I've read somewhere, that we're currently limited by technology. But is it teoretically possible to create element with 119 or more protons? If yes, could you please ELI5 what would it take to make such atoms?

[Assistant]
All of the naturally occurring elements have been discovered, the newer ones with high atomic numbers were created for very brief fragments of time in large colliders by firing small packets of protons and neutrons at atoms of larger naturally occurring elements.  They then use special instruments to detect and record the creation of these new elements.  However, the atoms of the newly synthesized elements are very unstable and breakdown to elements with smaller atomic numbers within fractions of a second.

It is theoretically possible to one day synthesize other, larger elements, but that would likely require a whole new technology.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why do cats stare at blank walls?

I've seen my cat, my friends' cats, and cats on the internet stare at blank walls, seemingly looking at nothing. Why do they do this?

[Assistant] A cat is unlikely to be staring at nothing rather an insect or even a trivial thing like dust or the play of the light. Cats are very keen hunters, with a strong instinct for tracking such things so they just can't help it.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Avengers] What would happen if Hulk swallowed the Cosmic Cube?

[Assistant]
The Cosmic Cube is a sentient device capable of immense access to cosmic energy. However, it is also an object triggered by the willful desire of a sentient being.

Absent any orders or requests it would remain dormant, and as there's no indication that the Hulk's digestive system could breach it's containment shell, it would pass through his system just like any other object would, unharmed.

If at any point it sensed it was in danger of being significantly damaged, it would defend itself with all the considerable powers at its disposal. That would like be deadly (even if only temporarily) for any being it was inside, including the Hulk.

the TL;DR of it is that the Hulk would eventually have a cosmic-level bowel movement.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Are there are any philosophers who actually identified as postmodernist?

It seems like postmodernism is a catch-all term for pretty much almost any French philosopher who wrote extensively in the 70's. However, I struggle to think of any philosopher who did not reject that label. Usually the people who are grouped under the label "postmodernist" are Michel Foucault, Jacques Derrida, Gilles Deleuze, Roland Barthes, Felix Guatari, Jean Baudrillard and maybe Jacques Lacan, but if I'm not wrong, all of them rejected this label. And even in the cases of the above philosophers, not only did they reject the label, but even when it comes to other people labeling them as postmodernist there is some controversy. So not only is it hard to find a philosopher who self-identified as postmodernist, it is hard to even find one where there is a large consensus from *others* that they are postmodernist!

With this in mind, two questions arise: Is there anyone who actually identified as postmodernist, and considering all this, does the label even have any value, or is it too general and all-encompassing to the point where it becomes meaningless?

[Assistant]
"Postmodernism" in philosophy isn't any sort of philosophical view or school of thought or set of beliefs. In fact, if anything, it's a number of various projects of critical modern philosophy which took place in 20th century France. Far from any kind of philosophical view *after* modern philosophy, as some people suppose, it's really just modern philosophy that's fairly at home in the broader trends of 20th century philosophy.

It's in this way that you're not going to find the 'usual suspects' of postmodern philosophy identifying themselves as postmodernists. Rather, they were quite consciously critiquing and expanding various, prior developments in modern philosophy, such as structuralism and phenomenology.

Even still, their critical projects are quite distinct from each other, and their personal relations vary, and occasionally acrimonious like the fallout between Derrida and Foucault after the former's critique of the latter's *History of Madness*. Even when any of the 'usual suspects' do mention postmodernity, like Lyotard, Baudrillard, and Jameson, these are sociological theses on the current state of postindustial societies and economies, not manifestos or programs of a philosophical view by that name.

To understand the period of work that people usually have in mind when they talk about postmodernism in philosophy or postmodern philosophy, check out Gary Gutting's *French Philosophy in the 20th Century.*


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why when on the phone do I do repetitious things like walk back and forth, arrange objects, etc.?

[Assistant]
disclaimer: IANANeuroscientist

Attention is really split into two parts in the current view, an audio loop (sound, reading, inner monologue) and a visuospatial sketchpad (vision, geometry, organisation), both of which are controlled by the central executive. A phone call utilizes only the phonological loop, without any visual stimulation. Part of you gets "bored" because of the one sided functioning, and rectifies the situation by doing actions that fill up visual processing time.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: How can a person have 8 pack abs when theres only 6 rectus abdominis?

[Assistant] Actually you just have 1 rectus abdominus muscle, which is split in the middle longitudinally by linea alba (white line). And there are tendinous insertions horizontally that gives the impression that you have 6 different muscles. There are normally 3 of these insertions, hence 6 bulges, but some have 4 of them making a 8-pack.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why is Nigeria so strongly associated with scams?

[Assistant]
It's called an advance-fee-fraud and was made popular by nigerian groups in the 80s via fax and now via e-mail. They send you a letter in pretty bad english (they are africans and they want you to believe them, so they don't speak flawlessly) and say that a nigerian prince has a lot of money and wants to transfer it out of the country or something in that fashion. Usually, you have to pay a little amount of money, so they can "set it up", of course, you will never see any money.

This is also known as the Nigeria Connection or the 419 scam (The nigerian law code 419 is about scams like this)


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
Is the human body affected by the changing seasons?

If we dont grow a winter coat like dogs, we dont have a set mating season, we dont migrate, etc, are we affected in any other way? If not, at what point did we lose those traits?

[Assistant]
Yes, assuming you actually go outside.

Your temperature preference should move with temperatures outside as your body's homeostasis primes itself for certain conditions. A good example is if you take someone from Michigan in the dead of winter and drop them in SC, their body is already primed to generate more heat than is necessary for SC weather.

The other big noted effect is the rise in depression and poor mood due to lack of Vitamin D production which is driven by sunlight exposure.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
[Warcraft]How is life proceeding on Alternate Azeroth since the Dark Portal never opened and the orcs never invaded?

Because of the events in Warlords of Draenor we subverted the potential invasion of Alternate Azeroth(Azeroth B), because of this Ner'zhul never arrived, The Lich King is never created, Arthas is never corrupted by him.

Was Medivh in Azeroth B still corrupted by Sargeras and still attempted to open the Dark Portal only nothing came out?

How are the different Kingdoms getting along with each other since an Orc invasion never took place? Have the Humans even discovered Kalimdor without the Third War taking place?

[Assistant] There is no alternate Azeroth, because it wasn't created along with AU Draenor, which didnt exist until it did, and only sustained itself by anchoring itself to the prime timeline, which is why it was the actual Archimonde who showed up at Hellfire, not some alternate demon.  Unless something from the prime line interferes, alternative events eventually fade into nothing.   Since the prospective AU Azeroth was never connected to the prime line, it simply never existed.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Vampires] If I rent my house, does the the vampire need my permission or my landlords permission to enter?

[Assistant]
It depends on whose HOME it is. The magic surrounding vampires and hospitality are about what space a human considers their home, which is magically protected from creatures of the night.

If the renter is just temporarily staying, with their eyes on a real home elsewhere, and the landlord has a deep connection to the property (maybe they lived there for decades and recently moved out and started renting their old house for extra income), it might still be their home, not the renter. The vampire would need to ask the landlord.

If the renter has been living in the house for years, and the landlord is just a distant concern who sees the rental as a business with no emotional connection to the property, it would be the renter's home.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why the USSR and the USA didn't remain allies

Why was it so sudden that after WWII ended the two super powers were at each others' throats, why couldn't they have continued being close allies?

[Assistant]
They weren't exactly close allies in WWII either, just reluctant bedfellows, due to a common enemy.

In fact, the beginnings of cold war scheming, on both sides, had already started before WWII ended.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] ELI5: Why does oil fry food and make them crispy while water boils food and makes it soggy?

[Assistant]
Actually you've kind of answered your question right there.

Oil fries food and makes it crispy.
Water boils food and makes it soggy.

But oil that fries food does so at a *much* higher temperature than 100^o centigrade, the boiling point of water.  That sound you hear when you fry something?  That's the water boiling away out of the outside layers of the food.  Frying *removes* water from the food by boiling the water off.

You could accomplish the same thing by baking the food, but frying heats the outer layer of the food much faster than any other method, so the outside gets hotter faster, while the inside of the food stays cooler.  Cooler means moister interiors and hotter means cripy exteriors.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: Why is water in fruits safe for consumption?

When I dig up the soil and drink water from it, I'm pretty sure that I'm going to be sick because of all the bacteria, pollutants and chemicals in this water. I can't drink tap water, river water, or even the rainwater where I live for this reason, too.

However, somehow when I take water from these sources and feed it to my plants, I can trust that the water I will consume later when I eat the fruits or leaves (in the case of vegetables) from these plants will be safe for me. Why is that?

I guess what I hope to know is: When plants take water from the underground, where do all the bacteria, pollutants and chemicals go? Are they filtered by the root and stem of the plant? Or are they "killed" by some kind of immune system that the plants have?

....................................

EDIT: Thank you everyone for answering. I did not expect so many replies, I think I understand this topic much more now. I used to think that water in fruit is always sterlized and completely safe to drink, but apparently that is not the case.

A lot of comments also asked where I live that I cannot even drink tap water straight from the faucet. It is my understanding that in Europe and North America, tap water is often safe to drink, but that is not the case at all in many developing countries. In fact, I remember being VERY surprised when I first saw American people drinking from fountains in parks or filling up a glass of water straight from the kitchen sink in Hollywood movies.

I live in Vietnam. The tap water here mostly comes from rivers, and it undergoes all the filtration and chemical treatment that we can give it, but we are still recommended to at least boil the water first before drinking.

When I was a kid, we did not even have a system to deliver tap water to every homes, even in the capital city (Hanoi). That was as recent as the early 2000s, (I was born in 1993), and most people used to drink and cook using either water from well or collected rainwater. But nowadays, many wells in my city are found to have lead, arsen and heavy metals in it, and rainwater is recently reported as unsafe to drink basically anywhere on Earth because it had "forever chemicals" in it that will never decomposes and can cause cancer. Tap water and bottled water are basically our only options, though the goverment still recommend boiling tap water or at least filter it one more time before drinking/cooking with it.

[Assistant]
>Are they filtered by the root and stem of the plant? Or are they "killed" by some kind of immune system that the plants have?

Both.

Plants are highly efficient at filtration.  They are also really good at sequestering different substances in different parts of the plant.  They also have immune systems that protect against many kinds of disease threats.

Of course sometimes that can be a problem.  If plants sequesters all of the lead they take in from polluted soil into their roots, then if it's a root vegetable that could be a problem for you when you eat the root.  But with fruit, the plant is pretty much going to make sure it's as clean and uncontaminated as possible.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
What does the Schrodinger equation mean and what does it tell us?

I am beginning quantum mechanics and we have been studying the Schrodinger equation pretty extensively. But I am confused about what this equation represents and why can't we derive it?

[Assistant]
The time-dependent Schrodinger equation tells you how a quantum state vector evolves with time. It says that the Hamiltonian operator is the generator of translations in time. If you know the state vector at time t = 0, the Schrodinger equation and the Hamiltonian tell you what the state vector will be for all time.

You can't derive the Schrodinger equation because it's a **postulate** of quantum mechanics. You can either postulate linear and unitary time evolution, and the TDSE follows, or you can just postulate the TDSE directly. Either way you're making an assumption about how quantum states evolve with time. This is a fundamental assumption to quantum mechanics, hence why you can't "derive" it.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] Why is human night vision so bad compared to many other mammals?

[Assistant] we lack a *tapetum lucidum,* which many animals have.  It's a reflective layer behind the retina that reflects back any light that missed the photoreceptors in the 1st pass-through, imnproving night vision.  It's the reason cat's eyes glow when you shine a light directly at them.


[System] Given the following post, respond as if you're commenting on Reddit:

[User]
ELI5: How come parts of the body like your hands get colder significantly quicker then parts like your head?

Just coming in the house, hands are freezing yet face is warm, eli5 pls.

[Assistant]
So your body wants to conserve heat.  When it's cold is does this by not sending as much blood to things that aren't 100% needed in that moment.  This is because blood near the skin will lose heat faster than blood inside your core.

However, your head has a lot of important organs in it.  Your brain, your eyes and these always need a good supply of blood.  Your arms, fingers, ears, etc don't need a constantly supply of blood when it's cold.


[System] Given the following post, respond as if you're commenting on Reddit:

[User] [Leisure Suit Larry] How is Larry doing now that Tinder is a thing?

[Assistant] His selfies are all too close for his big head, he writes down creepy things in his profile and he has strange obsessions in his moments section. Even then he keeps scoring on a pretty regular basis every few years when he drops into a fugue state and becomes a pickup master.