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

[User]
If a hole was bored through the center of the Earth, what would the atmospheric pressure profile be?

We often hear that the barometer is really measuring the weight of the column of air above us.  This explains variations in altitude within a reasonable range above the surface, but in the interior gravity drops off and eventually goes to zero. Is there a point where pressure ceases to increase or does it continue all the way down?

[Assistant]
It will continue to increase. If you dug a hole to the center, the gravity acting on the air at the bottom of the hole would be near zero, but the air higher above would continue to press down on you. The pressure would grow slower and slower, but it would continue to grow.

It may help to imagine a planet made entirely out of air. The sphere is kept together by gravity, in a way, all air is "trying" to go to the middle, but all of it can't get there, because it's already too "crowded" down there (i.e. high density and high pressure). If you were to venture into the middle of this sphere, you'd feel being squished from all directions as all the air is being pulled towards you.


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

[User]
ELI5: How do heat pumps work

How do heat pumps work and why are the energy efficient?

Edit: the question is sufficiently answered. Thanks guys!

[Assistant] You know those canned air bottles used for dusting? If youve ever used one youll know that at first the air comes out really fast, but then it drops off. Eventually the can gets really cold. When you set it aside you can hear a fizzing coming from it. Whats happening is that the liquid inside is under pressure and would really like to expand and be a gas. Letting it spray out allows more liquid to convert to a gas state, but in doing so heat leaves the liquid with the gas. The fizzing when you set it aside is the cold liquid inside boiling as it is heated by the air in the room. A heat pump basically works like that but in a closed loop with a compressor to re-pressurize the gas back into a liquid. Heat is carried from one side of this loop to the other. Refrigerators and AC units work in exactly the same way as a heat pump, the term heat pump generally refers to a unit that can pump heat in both directions, not just one.


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

[User]
What makes a sponge an animal?

My understanding of Poriferans is that they consist of cells that are all working independently, with no true tissues or higher level of organisation. Why then, are they considered multicellular animals rather than an aggregation of unicellular eukaryotes? What differentiates the sponges?

[Assistant]
To a large extent, its because they are not plants or fungi (wrong cell structure) and create an embryo, unlike protists.

If you really want to blow your noodle, check out placozoans - they are literally just bags of a few different types of cells, but theyre counted as animals because they *sometimes* create an embryo.


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

[User] [Harry Potter] Why isn't the Obliviate spell apart of the Unforgivable Curses?

[Assistant] Although its nature is rather insidious, the memory charm is too important to maintaining the wizarding world's masquerade from muggles. A typical witch or wizard needs a tool at their disposal to deal with a random muggle that happens to see something magical, and erasing their memory of the event is much preferable to, say, killing them for all kinds of moral and practical reasons.


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

[User]
"Landing" on a gas giant-is it possible, and what might you see?

Gas giants have no accessible solid surface, but they do have an atmosphere.  What would be needed to get a probe down into the atmosphere of, eg, Jupiter or Saturn for an extended stay (not just a rapid descent like the Galileo probe).  Is a hot-air balloon or unmanned aircraft feasible?  What sort of images would they send back and are there interesting scientific questions they could answer?  How much depth of atmosphere would likely be accessible?

[Assistant]
I'll answer the questions in an easy format:

Could you have a probe live in the atmosphere or Jupiter, or Saturn for an extended stay?

You could "attach" the probe to a orbiting body relatively close to the "beginning" of the atmosphere. This could also be done with an orbiting satellite. The satellite would be more ideal, considering it could constantly push back on the gravity pulling the probe in. Another way would be for the probe to constantly thrust itself upwards with the material around it as fuel. The oxygen, hydrogen, and other gases might possibly be used as an efficient fuel.

Would a hot-air balloon or unmanned aircraft be possible?

If made from a tough enough material, as long as the balloon was ligher(or in this case, hotter) than the surrounding materials it *should* be able to maintain an altitude. For both of these, the issue would be maintaining a speed high enough to continue to orbit without falling deeper in.

What sort of images would they send back?

It depends entirely on what elevation you're at. If you're right on top of the clouds, visible light would suit you just fine. We'd be able to see the dynamics of the clouds. If we went deeper in, we'd have to switch to a thermal camera to see anything of interest. Again, we'd be able to study the dynamics of the clouds interior, and learn more about the weather systems of the gas giant.

How much depth of atmosphere would likely be acceptable?

Depends entirely on the density of the planet. If it were an extremely dense gas giant, not very far, considering the gravity would likely crush the probe. Also, the ability to transfer data would be an important variable in this.

Are their any interesting scientific questions they could answer?

Yes. How does density affect formation of clouds in the upper and lower atmosphere? Does condensation of water occur anywhere within the atmosphere? Can life be sustained in this environment? Could life form in this environment? How much does heat factor into cloud formation? Are there substorms within the atmosphere that aren't visible to outside observers? Does lighting have an affect on cloud dynamics? Are there specific hot spots on this gas giant? Is there a mean time for a storm to last? Do storms affect overall density of the planet?

The list goes on and on. So yes, there's a lot of questions.

Hope this helped.


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

[User]
ELI5:  Details & ramifications of the new socialist french presidency

What does the new French election mean for France?  For the world?  What kind of socialist is Hollande?

[Assistant] Point of clarification: Hollande's not a "socialist", that's just the name of his party.  He's more of a center-left social democrat.  This gets confusing to Americans because we're sort of unique in the negativity we ascribe to the term.


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

[User]
ELI5: Why do flies always land on the same spot on people?

Seriously, why don't they get the hint when I'm swatting them out of the air over and over again? Shouldn't they be afraid of the giant Manzilla, like other bugs usually are? "Hmm, I think he's trying to kill me. Better go back and land on that SAME spot on his face again!"

[Assistant] They likely landed there initially/stumbled across a tasty spot on you (build up of sweat, maybe some molecules of crushed berries, w/e). They decide they like it > every time you move they flip shit and buzz away for a second or two like the tweakers they are > they land back there because they still like what you taste like.


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

[User]
[MCU: Thor] The Destroyer was a pretty damned effective weapon... Why wouldn't Asgard just build an army of those to send against dangerous foes (like the Jotuns) instead of risking the lives of their citizens?

I mean, seeing how much damage a single Destroyer did against a small town while battling four of Asgard's greatest warriors, it seems like a no-brainer to send it or an army of it against their most dangerous enemies.

Afterthought: I know they have this whole Honor thing, but it just seems... dumb, when they have the tech/magic to defeat their enemies without the "nuclear option" of using the Bifrost to destroy the planet. If they're so enlightened, it seems like a waste to use their own people as soldiers.

[Assistant] If they were cheap to make you bet that a paranoid leader like Odin would have an army of them. But he doesn't, so they probably aren't cheap. Odin himself made the Destroyer in comic continuity and it's possible he invested it with a little bit of Odinforce.


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

[User] ELI5 - What happens when an artist mixes paint for a painting? Are the pigments actually changing physically/chemically? What is actually happening to make the paints change color?

[Assistant]
The pigment particles in the paint are ground incredibly fine.  When two paints are mixed, the two different pigment particles are mixed together and so closely that our eyes can't distinguish one from the other but perceive a new color, of them mixed.

Picture if you had a million red pingpong balls, and a million yellow pingpong balls, and you mixed them together in a giant pool and looked at them from miles above.  Your eyes couldn't pick out single balls, it would look orange.

Lets say you mix some red and yellow oil paint together to make an orange paint, and put it under a microscope.  You would be able to see individual red and yellow pigment particles, but the smear of paint on the slide would look orange.


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

[User]
At which point or job position is the amount of work the highest for people in the academic-researcher career?

Non-native English speaker here.

I am referring to anyone above a PhD. That is postdocs, and those in the academic-researcher career ladder from Lecturer till Full Professor, Chair, Dean etc.

At which job position or point along the career ladder is the amount of work the most for people in the academic-researcher career? What does this high amount of work and stress look like?

[Assistant] In general, the more early work you do (and the higher the quality of that work), the better the career. Thus, the work during graduate work and postdoc period (if there is one) and early years in a Tenure track job has the biggest impact on one's career - so a clever person is working their hardest then.


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

[User] Why are there thousands of blackbirds flying around, but colorful songbirds are such a rare sight?

[Assistant]
The simple answer is natural selection.
The traits that the "boring" birds have help them live longer in the wild in comparison to colorful songbirds. Colorful songbirds can only survive in areas where there is minimal predative pressure.


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

[User]
[Star Wars] How is the YT-1300 (Millennium Falcon) such a successful interstellar freighter when it's so small?

It has a length of 34.75 meters, and a capacity of 25-100 metric tons according to the specs on Wookiepedia. Compare that to ocean based freighting, where ships are generally 200 to 300 meters long. The design seems much too small for interstellar shipping.

[Assistant] A YT-1300 is generally used for either specialty loads, or last-lightyear  transportation. That is, it's basically the equivalent of a 16 wheeler rather than a massive freighter, and great for that purpose.


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

[User] If there was a body of water that was as deep as the Marianas Trench but perfectly clear and straight down, would you be able to see all the way to the bottom?

[Assistant]
Even pure water absorbs and scatters light so you could not see the bottom of the
Marianas Trench (10,994 m depth). The amount of sunlight in the ocean decreases exponentially from the surface.  The *extinction coefficient* varies with colors (wavelength) with the blues penetrating the deepest to a few hundred meters.  So even if you had the brightest floodlights in the Marianas Trench and perfectly ~~clear~~ pure water (the open ocean is pretty close except for the salinity),  you can't see anything more than a few hundred meters away.


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

[User]
Can there be a numerical system without repeating decimals ?

For example we use base 10 which has 1/3 as a repeating decimal.

[Assistant]
There is no numerical base in which all numbers have a terminating expansion. (There is also no numerical base in which all numbers have a *unique* expansion, although that is a separate statement.)

Why is the former statement true? Well, for one, with a finite alphabet (digits and decimal point), you can only form countably many finite strings, which would correspond to the terminating expansions. But there are uncountably many real numbers. So no number base can do the job of expressing all numbers with a terminating expansion.

Here's some more insight about which numbers can be expressed with terminating expansions....

Fix a numerical base *b*, which may be any positive real number (not equal to 1). Can we characterize the numbers that have a terminating expansion in base *b*? Yes. If a number *a* has a terminating expansion in base *b*, then *a* has an expansion of the form

> a = d*_m_*d*_m-1_*...d*_1_*d*_0_*.d*_-1_*d*_-2_*...d*_-n_*

where d*_k_* are the digits of *a*, and these digits must be integers. This means *a* is equal to

> a = d*_m_*b^(m) + d*_m-1_*b^(m-1) + ... + d*_1_*b + d*_0_* + d*_-1_*/b + d*_-2_*/b^(2) + ... + d*_-n_*/b^(n)

Multiplying by b^(n) and rearranging shows that *a* must satisfy an equation of the form:

> p(b) + b^(n)a  = 0

where *p* is some polynomial with integer coefficients. Now if let P(x, y) be the polynomial

> P(x, y) = p(y) + y^(n)x

this means that P(a, b) = 0. That is, there is a polynomial with integer coefficients that vanishes at the point (a, b). This is another way of saying that *a* and *b* are algebraically dependent over the integers. Intuitively, we can obtain either *a* or *b* from the other by a finite number of arithmetic operations with integers (addition, subtraction, division, multiplication, roots).

So we have the following partial characterization. Given a number base *b*, if the number *a* has a terminating expansion in base *b*, then the set {a, b} must be algebraically dependent over the rational numbers **Q**. Equivalently, if {a, b} is algebraically independent over **Q**, then *a* cannot have a terminating expansion in base *b*.

It then follows immediately that there is no number base in which all numbers have a terminating expansion, although this is not quite as obvious. It turns out that the real numbers are a so-called field extension of the rational numbers with transcendence degree the cardinality of the continuum. This tells us a lot more than we need. But, in particular, given a number base *b*, it is always possible to find at least one real number *a* that is algebraically *independent* of *b*, and so all expansions of *a* in base *b* must be non-terminating.

(If the number base *b* is rational, then we can just take *a* = e^(b), which is always algebraically independent of *b*. This follows by the Lindemann-Weierstrass theorem.)


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

[User] How does physical exercise reduce the risk of getting cancer?

[Assistant] A major factor in reducing cancer risk involves lowering insulin levels. Exercise is great for that, especially if it lowers BMI into healthy ranges (avoids insulin resistance). Insulin does a number of things related to blood sugar but it is also a growth factor. Growth factors are part of the uncontrolled cell cycle that is found in cancers.


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

[User] ELI5: Why are two-way mirrors called TWO-way mirrors if the entire purpose of them is that they only let you see through them in one direction?

[Assistant]
They are sometimes called two way mirrors, because in truth you can see through either side, what matters is which side is brighter and which side is darker in terms of lighting. The dark side can see through to the bright side, but not the reverse.

These mirrors are referred to as both two-way and one-way mirrors, confusingly.


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

[User] ELI5: What is actually happening when you stand up too quickly and lose vision momentarily?

[Assistant] Your blood pressure drops when you sit/lay down so when you stand up too quickly your brain can't get enough blood since Gravity is too powerful to overcome so your body shuts down vision, balance, and hearing to save the brain. That's why some people get dizzy, lose vision, or hear a ringing sound.


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

[User]
ELI5: Why does some ocean waters seem so crystal clear and others aren't as blue?

Why do some parts of the world have the most beautiful shores and clear water but others are meh...

[Assistant]
If you notice the areas with clear waters, they are tropical and are usually on the east coast of a continent.
That's actually because the way water flows around the equator stacks up warm oceanic water along the east coast of continents.

Along the west coast, and at more extreme latitudes, the water is coming from the local area and is full of sediments.
By getting all of the clean oceanic water, the east coasts get water that has had the sediments settled out of it.

(Edit: Typo.)


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

[User]
[Star Wars Legends] Was a particular reason ever given as to why Jedi stopped using yellow lightsabers?

As of the KOTOR/SWTOR era (c. 4000-3500 BBY), yellow lightsabers are quite common, to the point that it's considered one of the three major colors of the Jedi. By the time the movies start, they're either totally nonexistent or just so rare we never see one onscreen. There's enough of a time gap that there doesn't really *need* to be an explanation, but was one ever given?

[Assistant]
I believe one of the official lines was that after battle for Ruusan and during the war with the sith a large amounts of sites were destroyed or lost, so Jedi for the last thousand of years have relied on Ilum crystals that produced only blue or green blades for some unspecified quirk of geology. Which is why most jedi would use blue or green in the prequel era. There are still other ways to get a focusing crystal of course, so there are custom ones too, but most jedi gather their crystals at young age in controlled environment on Ilum, and usually there's little reason to replace them.

During their career, jedi might lose their weapons or pick up mementos that can be used as focusing crystals, and would get some custom colors out that.


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

[User]
[Warhammer 40k] What is highest point on Terra currently?

And is it possible to attach my Vox-Streamer to it so I can watch heretics burn in HD?

[Assistant]
Probably the highest spire of the Imperial Palace, which is itself located in what was once called the Himalayan Mountains.

And since the Imperial Palace is a country-sized complex maintained by billions of people and defended by millions of Imperial Guard, plus Titans, Sisters of Battle, the Inquisition, any Imperial Fists in the area, and the entire Adeptus Custodes, since it houses both the Astronomicon and the Golden Throne itself and is probably the single most important location in the entire galaxy...no, you cannot attach a Vox-Streamer so you can watch heretics burn in HD.


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

[User]
[The Stand] What happened to the astronauts in space?

I mean, what happens to them when the world dies of superflu? Do they risk coming back, or do they just die up there in orbit?

[Assistant]
They have methods of returning to earth without Mission Control being involved, they're just super-risky without things like weather forecasting and ground recovery support.

But then, staying in orbit without resupply is a death sentence. So they're in a "pick your poison" sort of zone: Either stay safe from Captain Tripps and die in space, or risk return and possibly die during reentry or landing, and then probably die of Captain Tripps once down on the ground.


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

[User]
[MCU] What effect does the known existence of aliens, Norse gods and magic have on religion and theology?

In the MCU, since at least 2012 the majority of the world's population now know about the existence of aliens and actual Norse gods, and a few years later now know about actual magic. Every year some new shit pops up, and recently the whole world experienced an enormous alien lifeform rise from the sea and then get threatened with "judgement".

How does this affect things like modern Abrahamic religions? The existence of these otherwordly ideals would open up a huge can of worms. Suddenly we have concrete proof that a Norse God made deals with an alien race to invade earth in exchange for a rock.

[Assistant]
Ironically, very little if any.

The Abrahamic religions *already* acknowledge the existence of magic, and outside of creationists there's no inherent clash with the idea of aliens existing. The only real issue is the Norse gods, but the idea that polytheistic gods exist as some kind of supernatural beings is a rare but not unheard of idea in Abrahamic theology- the holy books mention them performing magical feats, and false gods are common in demonology. Guess those guys were right- after all, ideas like Valhalla and Ragnarok don't seem to exist, just big guys with magic powers.

So, in short? Magic is real (told you so), God created other sentient life and there are powerful beings falsely worshipped as gods. Not a problem- God's creation is simply bigger then we thought.


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

[User] ELI5: Why does hearing yourself speak with a few seconds of delay, completely crash your brain?

[Assistant]
It's called speech jamming.

Your brain pays a lot of attention to that what you say comes out right - you are listening to yourself as you speak.

With just a tiny bit of delay your brain percieves it as what just left your mouth, it's no issue, otherwise room echos would jam us all the time.

But is the delay too long, what the brain hears doesn't match up with what goes out through your mouth. So it tries to adjust your speech for the mismatch and that essentially creates a feedback loop and you're jammed.


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

[User] ELI5: Why is being inbred often associated with deformities of the body/mind/etc?

[Assistant] It has to do with genetics, mutations, and dominant/recessive genes. If a mutation happens in a person's DNA, they can pass it on to their children. But, if the child gets one "good" piece of DNA from one parent and one "bad" piece of DNA from the other, it's possible that the mutation won't show up or cause problems. But, if two people who are related have a child, there is a higher chance that both parents inherited a mutation from a common ancestor, and the child might get TWO "bad" pieces of DNA and end up with serious problems.


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

[User]
CMV: We should do away with tipping and either pay waiting staff a decent wage, or make all tips a flat rate of 4-5$.

First off, I dont understand the practice. Why doesnt their boss just pay them for the work they do instead of making us pay extra? To me this only appears to benefit the owners of the company.

Second, I dont think percentages are a fair way to tip. A waiter at a diner is working just as hard as the waitress at a fancy restaurant, but the waitress gets tipped 20% of a 200$ meal while the waiter gets tipped 20% of the 20$ meal. Both worked just as hard and both deserve to be tipped fairly. I dont think its fair that working at a high class restaurant garners you larger tips. The waiter doesnt set the prices at the diner, either.  I think a flat tip of 4-5$ at every meal would be much more fair.

EDIT: I tip every time the designated amount because Im not about to skimp someone of money they need, I just dont like the practice.

[Assistant]
> Why doesnt their boss just pay them for the work they do instead of making us pay extra? To me this only appears to benefit the owners of the company.

The boss would just raise the price of food to pay the waiters then and you would pay the same amount.

The reason for tipping is to give the waiters a stake in the restaurant. The more people who come in the more money they make.

>I dont think its fair that working at a high class restaurant garners you larger tips.

People who work at high class restaurants are expected to give better service to you than a person at a diner.


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

[User]
ELI5: Why do humans throw up when they see something disgusting?

I know about the gag reflex but what triggers that reflex when you see something disgusting?

[Assistant]
I saw an article once that suggested this is an evolutionary response.  Imagine life in prehistoric times, or maybe going as far back as the common ancestor between apes and men.  Nobody knows which plants are poisonous and which ones are safe to eat.  A bunch of us are sitting around eating and someone gets violently ill due to being poisoned.  If we're all eating the same plant, it's too late for the guy who got poisoned but it might not be too late for the others.  Those who get grossed out and throw up stand a better chance of not getting poisoned.  Evolution selected for the ones who puked.

Update:  if you'd like to learn more and maybe answer some of the questions below, google "sympathetic vomiting" and also look at stuff related to the Area postrema, which is the part of your brain that triggers vomiting.  Very interesting stuff.


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

[User]
[LOTR] Are hobbit house a good design ?

They were holes dug into the hillside, usually have a minimum of one round window and front door and sometimes back door.

How effective are in your opinion to control temperature and humidity ? Are they a good design ?

[Assistant] They're extremely good for that. Under that much soil they're almost always a constant temperature and well insulated. Really the only big issue would be for getting airflow through to keep the smoke from their hearths out.


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

[User]
[The Hobbit] If Bard had missed his arrow, who could have stopped Smaug?

From what I remember from the book, and the movie, he seems pretty much unstoppable, and there was only one black arrow, so nothing else could pierce his hide.

If the wind had picked up for just a second, what would have been the faith of Middle-earth?

[Assistant]
In the book, Bard talks about how the arrow has never missed, and how he has always retrieved it when used. He also says, *'If ever you came from the forges of the true king under the Mountain, go now and speed well.*

The true king under the Mountain was Thror, before he was driven out by Smaug. Some weapons seem to have a certain fate laid upon them, and they seem to find themselves drawn by circumstance to carry it out. Like Pippin's barrow blade, which was forged to harm the Witch-king and found itself at the perfect time and place to bring about the Captain's doom.

It's likely that Bard couldn't miss. But if for some reason he did, then Smaug would likely still rule Erebor, and Esgaroth would be destroyed.

But if the arrow was fated to kill the dragon, it's just as likely it would have been found, to be carried away by whoever escaped the destruction and return someday in another quiver.


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

[User] ELI5:Do memories get lost permanently when we forget?

[Assistant] Perhaps eventually. Memories that you haven't recalled in a long time tend to get hazier and harder to remember details of over time. But you'll find that sometimes a specific event will dredge a long-forgotten memory back into mind.


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

[User]
ELI5 What the Russian diamond announcement means to the diamond market, the global market as a whole, Russia, and DeBeers.

This seems like a huge announcement. What does this mean?

[Assistant]
1. Some smart people found some really hard rocks in the ground 40 years ago.
2. Things in the ground are hard to get out of the ground. Especially when they are really hard rocks.
3. Some other people decided not to tell anybody about the rocks in the ground because they were busy "playing" with their "friends" and had already decided to make their own really hard rocks.
4. They finally told everyone about their cool rocks.

****
5. The rocks are still going to be really hard to get out of the ground and it will take a lot of time.
6. The rocks aren't very pretty so they'll mostly be used for really big machines that need really hard rocks.
7. There are A LOT of these rocks. More than anybody has ever found before.
8. **This means** that once they get them out of the ground, lots of people will be able to use them in lots of different big machines (especially big machines that get very hot or that cut very hard things) and that those machines will create useful things for everyone.
9. But again they still have to get them out of the ground.

*****

Some other people (like DeBeers) mostly deal with the really pretty and shiny rocks. They already have plenty of those anyway so even if there are more nice rocks in Russia, they probably won't want any more. They certainly won't want to sell their rocks for less money.


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

[User]
[Avatar: The Last Airbender] What happened to all the lion turtles?

As seen in the Wan arc of Legend of Korra, there were many lion turtles, at least four. But in book 3 of ATLA, only one is still alive (that we know of), what happened to the rest?

[Assistant] They were hunted to near extinction. Much like how firebenders hunted dragons, it was a sign of great power and respect to kill a lion turtle. The one that taught Aang energybending was confirmed to be the last living one.


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

[User]
If morality is subjective, why do we debate/discuss it?

I know it's not the case that morality definitely is subjective. But assuming that it was, what is the function of moral discussions or arguments? How do they work?

How do arguments function when one party can always just say "that's just your opinion" about any proposition?

Further, what does it mean to be subjectively right? Is this something to do with proving that X follows from shared axioms regardless of whether X is objectively or subjectively true?

Last, any reading recommendations on this?

[Assistant]
We talk and argue about lots of things which are subjective all the time, like table manners or whatever, so something being subjective doesn't seem to be a barrier to use arguing/discussing it.

>Further, what does it mean to be subjectively right? Is this something to do with proving that X follows from shared axioms regardless of whether X is objectively or subjectively true?

Being subjectively wrong/right is pretty empty, but we can think about it in terms of hypotheticals, like 'If consequentialism is true, what sort of things should we do?' or 'If moral naturalism is true, does this point to consequentialism being true?'


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

[User] When jogging, why does my head start sweating first instead of my legs which are doing most of the work?

[Assistant]
This is a general phenomenon and not particular to just you (so it's getting released).

Sweating is a mechanism to get rid of heat. The heat is transferred via the blood stream to surfaces that an dump heat to the environment. Heads have excellent surface blood supply so they can be used as effective radiators.


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

[User] ELI5: Why do inhalers let you breathe instantly during an asthmatic attack?

[Assistant]
An asthma attack happens when parts of the lungs squeeze shut, generally in response to a perceived threat. This stops air from reaching the lungs. Normally,  your brain sends a signal to these parts of the lungs telling them to open again shortly afterwards, but for one reason or another this doesn't happen for someone experiencing an asthma attack.

The drug in a rescue inhaler (called a bronchodilator) simulates the kind of signal your brain would normally send, causing the airways to open on contact, letting air back into the lungs.


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

[User] ELI5: How does a breathalyzer accurately tell how much alcohol is in your blood, from your breath?

[Assistant]
Your lungs are essentially a big permeable membrane separating your blood from the outside air. Smaller molecules like carbon dioxide, oxygen, water vapor and indeed alcohol are free to move through this membrane. So the alcohol in your blood will evaporate into your lungs and you breathe it out. The higher the concentration of alcohol in your blood the higher the concentration of alcohol in your breath.

It is very hard to chemically analyze air for the presence of a specific molecule like alcohol. It can be done but require a lot of advanced equipment. So most police breathalyzers do not actually do this. Instead they contain a sensor which detect any volatile organic compounds. Basically anything that will burn. There is a small heater which will heat up the air and then sensors will detect how hot the air gets. If it gets hotter then expected then something in the air must be contributing with energy, such as burning alcohol. The breathalyzer does correct for things like airflow, humidity and temperature which it can measure with other sensors.

This does mean that it is very hard to fool a breathalyzer into reading low. Anything you may put in your mouth will either have no effect or cause the air to be even more flammable. There are extremely few substances which are harmless to humans and reduces the flammability of the air. So unless you happens to carry around some fluorketone just for this occasion and manages to take it without the police officer noticing it you are going to trigger the breathalyzer if you are drunk.

On the other hand since the breathalyzer is not actually measuring blood alcohol levels but use proxies it can often be defeated in court. So police do not use this as their only piece of evidence, or even the main evidence of drunk driving. But it can give probably cause to conduct more invasive searches such as looking for open or empty alcohol containers in the vehicle or taking a blood or spit sample for further laboratory testing.


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

[User]
ELI5: Why is it recommended that we wait a little bit after turning something off to turn it back on?

Also why can we restart PCs since this contradicts this recommendation?

[Assistant]
Most electronics contain capacitors. Capacitors act like little buffers to even out current in a system. A bit like having a header tank in a plumbing system. Think of them like tiny batteries that are constantly charging and discharging.

When you turn off an item, the charge in the capacitors doesn't go away straight away. You have to wait for a few seconds to allow it yo dissipate. The charge can be enough to mean that certain buffers or bits of memory aren't properly reset, so without waiting, the restart alone doesn't always fix it.


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

[User]
ELI5: Can bubbles be made in any liquid, or are there types of liquid that actually cannot create bubbles?

I know that bubbles are just little pockets of air that didn't break surface tension of liquid, but are there any types of liquid that cannot make bubbles at all?

[Assistant]
By definition, and as you said already, a bubble is just a pocket of gas in a liquid.

So, to avoid bubbles, we just have to be in such conditions that gas cannot exist. Simple enough.

Since Helium has the lowest liquefaction temperature of any element, at 5 K (or -268.15 C), no gas bubbles could form inside liquid helium, as no element could be in gas state.


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

[User] Eli5, How does a railgun work?

[Assistant] Have you ever seen a baseball pitching machine? The kind with the rotating wheels that sling out fastballs at a batting cage? Imagine a bunch of those laid end to end with the baseball passing through each one. Now swap out the rotating wheels for electromagnetism and the baseball for a conductive projectile and that's basically a railgun (without getting too much in the weeds about the Lorentz force and right hand rules).


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

[User]
[DCU] What sets the underworld kingpin known as "Penguin" apart from regular mob bosses like Falcone and Maroni?

Penguin occasionally uses his trick umbrellas (what those have to do with penguins, I don't know), but aside from that, his only real distinguishing feature is his physical deformity and his sweet Iceberg Lounge, which is not like the gimmicks employed by costumed supervillains such as the Scarecrow and the Riddler. Yet I frequently see him listed *amongst* them. So I ask you, what separates Penguin from a regular mob boss and makes him a **supervillain?**

[Assistant]
You're more familiar with the more recent version, but older versions of the Penguin were more hands-on about their supervillainy. They committed bird-themed crimes (with trained attack birds!) and even engaged Batman in direct combat.

For example, the Penguin in 1992's *Batman Returns* had an army of circus people and another army of weaponized penguins, while the Penguin in 2004's animated series *The Batman* had trained birds, kabuki-ninja henchmen, and martial arts skills nearly on par with Batman's.


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

[User]
[Starship Troopers] How are Federation soldiers able to take massive amounts of injury and continue fighting?

It has been observed that while in the field soldiers are able to have limbs severed, crushed,  melted and sustain mortal injuries such as being impaled through the torso. Is there any scientific reason behind this, or are Riko's Ruffnecks really just that tough?

[Assistant]
Generally, at the time of the injury, they're not fighting back. They're getting triaged. It just so happens that technology has advanaced where wounds that were considered mortal can be patched so the soldier doesn't bleed out.

When the trooper is back at a hospital, what can be repaired is repaired. What is lost is usually replaced with an advanced prosthetic.


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

[User]
[TheDarkTower]Is it set in the future, im a bit lost?

Ok, So i just started reading the Dark Tower series over the weekend, and i feel a bit confused and lost.

The world of the gunslinger confuses me a lot.  At first i thought it was a fantasy world (like LoR, or Game of thrones) but then there are characters talking about beetle songs and some characters mention Jesus?

Just trying to get a mental image of where all this is taking place, is in on earth in the future?

Edit: Thanks everyone.  Got me really hyped to read this series!

By all means if im just being a dumb and need to read more to understand, please tell me.

Also if the answers contain spoilers, please just tell me to go read and not ruin it.

Just looking for a little guidance to anchor myself in this world, its kind of confusing.

[Assistant]
Our world exists. Think of it as an axis upon which all other worlds rest.

The Gunslinger's world runs perpendicular to our world. If our axis were to fall away, so would the world of the gunslinger.

All of King's books run perpendicular to our world. Some worlds are stacked on others - nested on top. If those worlds crumble, so would the world on top.

There are thin spaces between these worlds that can allow characters to travel between these worlds. Things bleed over from one reality to another (like hey jude in the saloon).

Some worlds are on the brink of dieing. There are forces out there that actively seek their doom and destruction.

You will find out more if you keep reading.


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

[User] ELI5 When we're frustrated, why do we want to hit/break something?

[Assistant] Cathartic release. When we have a build-up of [emotional] energy, we need some way of relinquishing that energy. Typically as we mature, were able to use words to express how we feel, which is great catharsis. When were younger and dont have words to express our feelings, or for people who are immature and never learnt to use their words to express their emotions, they tend to go for hitting/breaking things.


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

[User]
[LoTR] So other than control and curse the wielders after the One Ring was forged what did the other "Rings of Power" actually do?

Did they provide any benefit to the people who acquired them before Sauron took control? and why was it only the rings given to Man that seemed to have a lasting effect?

[Assistant]
>Did they provide any benefit to the people who acquired them before Sauron took control?

Yes.  The main purpose of the Rings was preservation.  The Elves' goal was to stop the changing of their kingdoms from time. This is why Lorien and Rivendell are like a window into the Eldar Days during the Third Age, Elrond and Galadriel use their Rings to preserve the kingdoms. The elven kingdoms would have been even more magnificent when they had all 19.

>and why was it only the rings given to Man that seemed to have a lasting effect?

As described above, that isn't exactly true, both Elrond, Galadriel, and Gandalf used the Three throughout the Third Age.  But the Nine given to Men provided them with a sort extended life.  Their Rings (along with the 7 given to Dwarves after Sauron took the Rings from the Elves) are inherently corrupt as Sauron directly helped make them (this is not the case with the Three).  Just as Frodo and Bilbo did not Age (or did never slowly) the same happened to the Men who had the Nine. Dwarves proved resistant to the Sauron's control, though not totally so from the Rings' inherent corruption.

All the Great Rings generally enhance their bearers as well.  The more powerful the bearer, the more power enhance by the Rings.  ^(This is not why hobbits become invisible!)  From the perspectives we see, Frodo and Bilbo have enhanced senses, and ability to read people, though not full on telepathy (though that may have been possible for them if they trained themselves to the task).  Someone like Gandalf or Galadriel are no doubt enhanced in other ways (likely strength of mind/will), though we don't really see explicitly how.


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

[User]
[BTTF] What happened to the Lybian Terrorists?

Sure they crashed their van. But these guys were almost able to have a nuclear weapon on American soil. Did Doc and Marty just leave them there? Did they get arrested? What would the international fallout of having terrorists able to procure nuclear material identified and active in the U.S.

[Assistant] The Libyans in the timeline we see at the end of the movies were just actors hired by Doc to ensure Marty went back to 1955. Remember, the Doc in timeline-B worked with Marty in 1955 and got a letter about being shot by terrorists.  He worked out another way to get plutonium, but had to still have Marty travel back to 1955 thinking that Doc had been killed by terrorists, so he recreated the scenario that the original Marty experienced, creating a closed time loop.


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

[User]
Could "Cogito Ergo Sum" be false?

Hello! I am Alex, A 16 year old boy who has been tinkering with the ideas of Rene Descartes' "Cogito Ergo Sum" "I think there fore I am" for a while now and have come to realise something about it.

I confess I have not read his particular book "Meditations on First Philosophy" where this quote originates to my knowledge. I will probably in the near future read it but I have studied online about the quote itself and the meaning of it. I have a particular question in mind that has plagued me for months now, which I wish to address first before dwelling deeper into Rene Descartes' philosophical studies.

Descartes questions and doubts that can he be sure of any beliefs of his to "exist" or to be "real" and that what if a demon could be deceiving all of his beliefs and thoughts to be "wrong" or that he could never be sure of them. He begins the disproving of the demon by removing all of his beliefs he has off the table of certainty out of the question to find are any of them out of the demons grasp of influence as they could be of the demons tampering. He "proves" the existence of doubt. As he had stated: if you are doubting that you are doubting, you must be doubting then! But my question on this matter is, how can descartes be absolutely sure, doubting do you doubt proves there is doubt? People might say it is self evident, but what if the demon is tampering that doubting doubt equals doubt and descartes has been deceived by the demon to come to this conclusion? What if doubting doubt equals something else than doubt but the demon is hiding the fact it is? Does Rene Descartes own "demon belief system" prove his findings false itself and the idea of "I think therefore I am" false therefore?  -Alex

:EDIT: This idea of "doubting doubt equals doubt means it exists absolutely" led me to read about logical axioms also, as an example of the axiom "X = X" is an "absolute truth" or axiom but how can one be even sure X equals itself? Isn't it just a mere "belief" in the end ? And nothing really has been proven? Is all we merely "perceive" just belief? A whirlpool of infinite doubt as we doubt until we doubt for infinity and doubt isn't even the concept of belief a belief and so on and so on.

[Assistant] Hume famously offered a way to doubt this. The term "I" in the phrase is something that is being assumed, not something we actually observe. Hume says that there's no reason to think such thing as this "I" exists - all we have is a series of impressions, related to each other via similarity. We have no cause to believe there there is some sort of "self" having the impressions that is unified into an "I."


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

[User] How does a fractal pattern camouflage on Jets work? I understand how Army camos work by blending with the environment but in an open space like the sky,how does it benefit by the use of such pattern? Example image inside.

[Assistant]
1: This isn't a common pattern of camouflage and may be experimental- in other words it might not work that well.

2: In general, the blocky/pixely/fractal patterns on many new camouflage designs works by breaking up straight lines as much as possible. If you aren't really close, like in that picture, the human eye would see the dark/light interface as a fuzzy blur. Just like how pixels blend together on a computer monitor. Military camo is designed to break up the outline of whatever you might be looking at so your brain doesn't separate the camouflaged object from its background.


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

[User] Do peoole in comas have cycles like sleep/wake for brain activity or is a general muted brain activity the whole time?

[Assistant]
In general, a coma is a state of unconsciousness you can't be awakened from.The brain doesn't go through normal sleep cyclesand you can't move in response to pain. Comas are caused by brain damage from head injuries or illness.

However some coma patients (up to 15% of patients) can show normal looking brain activity.


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

[User] ELI5: Sometimes raindrops are misty, sometimes theyre large. Why? What dictates the nature of raindrops?

[Assistant]
Raindrops tend to be bigger the lower they fall from and the higher the air pressure.

More rain, less wind and lower clouds tend to result in bigger drops.

Temperature also has an effect, because the colder water is the greater the surface tension (which makes the waterdrop more resistant to splitting up).


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

[User]
Why is it that a vaccine like J&J can reduce severity of Covid-19 even in cases where it doesnt provide full immunity?

The trials indicated that full immunity varied by country, probably due to the different strains. But it was effective at reducing severity across the board at similar rates, regardless of strain. Why does that happen?

[Assistant]
Vaccines elicit more than just antibodies. They can also stimulate the differentiation of T cells that recognize the antigens (the proteins of the virus) and these help coordinate the immune response as well as destroy infected cells.

For the virus SARS-CoV-2, how quickly the T cell reaction can respond is critical to how severe the disease can get. A rapid response often results in no or few symptoms, while a delayed T cell response can result in an uncoordinated immune scramble that results in severe illness and/or 'long COVID'.

Vaccines that attenuate disease but don't prevent infection are common. The vaccine for shingles is given to people who have a latent varicella virus infection (after childhood chicken pox); it prevents the disease from flaring up.


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

[User] ELI5: When I tap a concave glass beer bottle bottom on top of another glass beer bottle it foams up uncontrollably, but if I just tap something flat on top of the other beer bottle it doesnt?

[Assistant] It's not the shape of the bottle that causes it to overflow, it's the hardness of it.  A beer bottle hitting a beer bottle creates a pressure wave that goes through the bottle causing it to bubble.  If you hit it with something flat but soft like a book it would cause a less severe wave and be less likely to foam (unless you used more force).  Basically anything that causes the bottle to make a clinking noise will have the same result if you apply equal force.


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

[User]
[Avatar] Where are the water and earth shamens?

We know that the Air Nomad monks are responsible for identifying the Avatar when the rebirth cycle is on air. We know that the Fire Shamans are responsible for identifying Avatar's when the cycle is on fire and that they're supposed to be helpful and loyal to the Avatar, no matter which nation they're born into. Yet, when Aang travels to the Water Tribes and Earth Kingdom, he never even considers tracking down their Avatar temples.

This is especially strange since the Water Tribes should be on call to try to find the next Avatar after Aang went missing.

What's up with that?

[Assistant]
The four nations are each culturally distinct. While the Avatar plays a role in every nation's spirituality, how that manifests is different for each group.

In the hundred years war the Water Tribe has sort of drifted away from their spirituality. They maintain traditions, but mostly for traditions' own sake. Not that the people aren't strong spiritually, just that their society has shifted. (This is a plot point addressed in Legend of Korra)

The Earth Kingdom is huge, and has many culturally distinct states. If the Avatar was born there it would be up to local authority figures to put the pieces together. Kyoshi's Avatar-hood wasn't discovered until she was 16. That's probably fairly common among Earth Kingdom born Avatars. In Ba Sing Se, the institution that would take on that role is the Dai Li. (So, not exactly helpful to Aang)

There are temples to the Avatar all over the world. Visiting them each individually doesn't really serve much purpose to the Gaangs' larger goals. There's also something to be said for subtlety; Sozin ordered a genocide of the Air Nomads to wipe out the Avatar. Azulon did the same thing to the Southern water tribe. The idea of Aang showing up was so inconceivable that Ozai used finding the Avatar as a way to banish his son. At what point do the organizations whose sole role it was to find or serve the Avatar just disband?


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

[User]
[Halo] Why did the Prophet of Truth favour the Brutes over the Elites?

This has never seemed to add up to me. The common answer is that Truth felt that the Elites asked too many questions and were insufficiently blindly loyal for his liking. Certainly, there had been prominent Sangheili who had questioned the Covenant's religion before (like Fal Chavamee) and others who had argued in favour of admitting humanity into the Covenant, but there's no indication that these were anything other than a small fringe. After all, most Elites were clearly fully devoted to belief in the Great Journey at least up until the Great Schism. And even after that many Elites continued to worship the Forerunners.

By contrast, it is argued, the Brutes were more unquestioning and blindly loyal. But that clearly wasn't completely true, given that there were Brutes (most notably Atriox) who saw through the lies of the Prophets and rebelled. Heck, Atriox was even the most successful rebel in Covenant history.

Surely the experience with the Banished should have made Truth realise that Brutes are just as capable of disobedience as Elites?

[Assistant]
1. The Elites failed spectacularly at the destruction of the first Halo Ring.

2. The Elites were getting suspicious of the Prophets plans.

3. The Brutes were getting too rowdy after the fall of the first Halo and moving them up to replace the Elites placated them.

4. The Brutes were much easier to deceive than the Elites.


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

[User]
[Astronomy] If there were once water on Mars, why isn't there now? What happened to it?

Did Mars' atmosphere change? If so, how/why? Is it possible there is still water underground on Mars? (I know that is a slightly separate question.)

I ask this in light of Curiousity's recent discovery of pebbles that appear to have been formed by water.

Thank you for your knowledge and insight.

[Assistant]
one of the biggest reasons for the lack of surface water now is the lack of atmosphere.  Mars' surface pressure is about .000006 atm's - it barely has any atmosphere at all.  The atmosphere is gone mainly because the magnetic field died down, allowing the solar wind to slowly strip away the atmosphere.  There is not enough pressure to retain water on the ground.  Even ice (since it is very cold there) will slowly sublimate away into the atmosphere, where it will suffer the same fate of being stripped off by the solar wind.

Yes, it is very possible for water to remain underground, since it would be under enough pressure from the ground itself to keep it from evaporating/sublimating away.


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

[User]
Why do we see colours and 'stars' when we close our eyes?

What is the brain doing that makes us see the random swirling colours and spots when we close our eyes but are still awake?

[Assistant]
That's what we call "visual snow." In your visual nervous system, there is a small baseline level of neurological activity going on, even when you're not getting a stimulus. Basically it's just random firing of a few neurons here and there. Usually this activity is washed out by all the visual information you're getting from your eyes.

Think of it like a radio that's just a tiny bit out of tune. Normally, when the music is playing, you wouldn't hear the small amount of static that's there. Once the music stops, however, you can hear the static. It's the same thing with your eyes. When you close your eyes, you've eliminated the external stimulus (the "music"), and all that's left is the baseline neurological activity (the "static").


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

[User] Why can we freeze embryos for IVF but not adult humans? What makes it possible for embryos?

[Assistant] Hello! Not an expert in freezing and thawing live specimen but well practiced in freezing and thawing dead specimen while keeping organs and microstructures intact. The major concern with freezing biological matter is the formation of ice crystals. Water forms crystals and expands when frozen and can result in burst cells and organelles. To avoid this, we introduce cryoprotectants. These are basically antifreeze that diffuse into the cells and around it to avoid formation of crystals. It's very easy to diffuse these new compounds into microscopic specimen because the surface area to volume ratio is very high compared to humans. Very rapid freezing with liquid nitrogen, also known as flash freezing, also helps in avoiding formation of large crystals (slow freezing means more time for the molecules to align). So the simple answer is size. We can't introduce cryoprotectants into every part of a human being fast enough nor can we flash freeze a human body fast enough.


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

[User]
Do you format your code manually or use formattting tools ?

I personally haven't managed to find a formatting tool that fully suits me.

So I mostly format manually, with some exceptions.

I use IDEA for java and VS for C#.

[Assistant]
Formatting tool, definitely.

As soon as you start working on a large enough team, you'll learn that being 'that guy' who causes all the merge conflicts by insisting on using different code formatting rules to the rest of the team, gets you a lot of angry looks and eventually thrown off the team.

Typically you would  format all the code you changed before creating a pull request, and a lot of the formatters allow the rules to be stored in a config file which is part of your source base, so you can't say, 'I didn't know the rules'


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

[User] ELI5: If looking through a periscope, would a short-sighted person be able to see less far than a normal person?

[Assistant]
In a simple, mirrors-only periscope a near-sighted person would need their glasses otherwise everything would appear blurry.

However, more modern periscopes use lenses for focus and/or magnification, so they can be individually focused based on your eyesight like binoculars or a telescope.


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

[User] ELI5: Why doesn't cold fat, such as lard, taste good to us like hot fat, such as bacon grease? Aren't they both high in calories and almost the same thing?

[Assistant]
Your tongue doesn't taste that much. A lot of what we consider taste is actually from the nose smelling the food. Cold fat is less likely to give off the same amount of type of aromas as heated fat.

Also, comparing lard to bacon grease, the bacon grease has the added smell and taste of the cooked bacon in it, which gives it a very rich, meaty smell. Lard is generally pure fat, with no additional smells/tastes.


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

[User]
ELI5: Why do OTC medicines go by age instead of pounds?

Got my 6'3" son cold medicine and it has dosages by age instead of weight. This makes no sense. It's been bothering me for years. All OTC meds do this, but prescriptions go according to weight.

Any ideas why a petite woman would get the same dosage as Terry Crews?

[Assistant]
Because biology is complicated, and going by weight isn't that much more accurate.

Let's say Terry Crews's body is twice the weight of your typical Olsen twin's.  Is his brain?  His liver?  His thyroid gland?  Is the drug used throughout his body, or is it simply triggering a response, and beyond a certain amount doesn't matter?  What if the twin started porking out until she weighed the same as Terry?  Her organs didn't suddenly get bigger.  What kind of math would you have to use to take all these factors into account?

Instead, drug manufacturers play it safe and give the appropriate dosage for a small adult.  They will let doctors and patients assume any risk of increasing that dose.


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

[User] ELI5: why does not drinking enough water cause headaches?

[Assistant] Dehydration causes your brain to shrink. As your braincase is essentially sealed, this shrinkage causes negative pressure between your brain and skull, which has the effect of pulling on the inside of your skull - like being squeezed, but from the inside. This is what causes the pain.


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

[User]
ELI5: What exactly causes you to feel "choked up" when you're crying?

That squeezing in your throat feeling when you start to cry?

[Assistant] There's something in your throat that blocks the windpipe opening when you're swallowing called the glottis. It's kind of like a little trapdoor that stops food from getting into your lungs. When you cry, or have anxiety, or are upset etc. the glottis swells up and creates unfamiliar pressure down there, triggering a reaction similar to having an obstructed airway and causing trouble swallowing and the "lump" feeling. Basically humans have poorly designed holes and crying is weird so weird stuff happens.


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

[User]
[Jurassic Park] Why did Nedry cut power to the fences?

Couldn't he have just disabled security/power in the specimen room area or just the building he was in? He should have known it would be harder to escape with dinosaurs on the loose.

[Assistant]
He needed to get through several electrified gates in order to rendezvous with his contact on the ship.

He was dropping off frozen DNA samples to Ingen's competitor and didn't want to get caught, so he planned a circuitous route through the park.


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

[User] Is there a way to visualize the fourth dimension?

[Assistant] Imagine a two dimensional person drawn on a piece of paper. Now draw a square around him. To him, there is no conceivable way to escape from the box. There is only up, down, left, and right, all of which are blocked. However, to a three dimensional observer of this (you), there is a simple solution: bring the person up out of the plane of the paper and place him back onto it outside of the box. What you have done is introduced a new dimension to him. This dimension would be completely invisible to him, and when he re-enters the second dimensional world he is accustomed to, he will be magically outside of the box. Now lets extrapolate this idea into three dimensions. Imagine you are in a cube. There is only up, down, left, right, forward, and back. There is no way to exit the cube that you can see. However, to a fourth dimensional observer, there is a very simple way to exit the cube: introduce a new dimension to you. This would be completely invisible to you, and when you re-enter the third dimension, you will be magically out of the cube. Also, a two dimensional being would cast a one dimensional shadow. We are three dimensional, and we cast a two dimensional shadow. Therefore, we can assume that a fourth dimensional being would cast a three dimensional shadow.


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

[User] ELI5: In what way is the skin inside your mouth (always wet) different than the skin on the rest of your body?

[Assistant] The skin in your mouth is living cells that is constantly lubricated by saliva. The skin on the outside surface on the other hand is living cells coated with a layer of dead cells and is filled with a substance known as keratin which gives it excellent protection from the wear and tear of everyday activities. Also areas on your body that experience more wear and tear have a thicker layer of dead cells for increased protection(like your soles and palms).


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

[User]
ELI5: Why some front page posts get the upwards of 8000 up votes (like the Thanksgiving donut cop post) and hours later votes drop down to 2000-3000 votes?

Edit: wow I just kinda threw this out there and expected either nothing or just one or two quick answers. As I've been reading and understanding more, I think what I did mean to say is a post's points rather than up votes. I didn't realize they kind of weren't one in the same, so I suppose people have explained how the weighted system works and spam bots putting an impact on why the points may drop so rapidly. Thanks for making this my top post and for all the help!

[Assistant]
Points and votes are different. As the votes get bigger, they are worth less points. Points are what you see the posts score as.

This next part is speculation

It's possible that a post can get so popular so fast that it doesn't get those beginning down votes. Once the post is that big, naturally it gets downvoted back down to an average level.


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

[User]
(Marvel) Could Xavier prevent Banner from becoming Hulk?

If Xavier built a mental block into Banner, could he prevent Banner from triggering Hulk?

[Assistant] It could work temporarily, but The Hulk is not just a part of Banner, mentally.  I'd imagine  psychic blocks would work a little more effectively than meditation, but as soon as Bruce was put in danger (as he occasionally finds himself), The Hulk would overpower them.  The Hulk won't allow Banner to die, and if I've learned anything about The Hulk is, he gets his way.


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

[User]
ELI5: how does a spaceship know how fast it's going?

We know how fast Voyager 1 is going, is that because it has a device on it to measure its speed? Or is it because we visually measured its speed compared to background objects, and have implied it?

A tire is the object that rotates and measures a vehicle's speed. Air speed passing by a sensor determines a plane's speed. We don't know what dark matter is (and presuming we don't have sensors to measure it), so how do we know how fast a vehicle in space is going?

[Assistant]
We know how fast the spaceship is going because we knew have fast it was going, exactly where it was heading, and how long it's been travelling, as well as everything near it that matters (the sun, basically).  If you know all those factors you can figure out what speed it will be moving in the future.

In addition we can tell how fast it's going based on the signal that it's sending to earth.  This is also how we can tell how fast other galaxies are moving away from us.

But in all these cases the speed is actually **speed relative to something**.  Voyager 1 is listed as travelling X mph away from the sun, but it's exactly as accurate to say the sun is moving at X mph away from Voyager 1.


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

[User]
Is the worldwide consumption of coffee at a point that should something happen to coffee production, there would be severe global HEALTH problems?

Basically, since coffee is drunk as much as 1/3rd of normal tap water and is the 2nd most traded product in the world, I'm wondering whether what problems would happen globally if the global production of coffee met with some disaster?

Ignoring economic problems, I'm interested in the health problems that might happen to a large global population.

[Assistant]
Coffee has a fairly minimal nutritional profile so a sudden break in the worldwide supply of coffee would have little to no impact on world wide nutrition; no one is going to starve nor suffer any deficiencies.

Caffeine is moderately addictive/habituating but withdrawal is fairly short lived typically with minor to modest effects. A fair number of will people with marked addictions will likely be kinda irritable and maybe have some headaches or problems getting to sleep for about 2 days (possibly up to about 1 week); rarely some people report nausea or anxiety issues too.


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

[User] Where do cows get all that calcium from?

[Assistant] The plants they eat, of course.  Green, leafy vegetables have plenty of calcium.  Cows eat lots of those.  Of course their intake can be supplemented by prepared feed, but naturally there's plenty of calcium in plants.


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

[User] ELI5: Why aren't there seatbelts in public busses?

[Assistant]
The chances of you needing a seatbelt in a bus are far less than in a VW bug. The weight and size of a bus makes it inherently safer to drive in than a smaller vehicle.

The only problem here is if the bus flips. Then you're fucked.


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

[User]
[1984]why does the Party need to bother creating edited versions classic works of literature that contain material that conflict with party doctrine in their original form? why not just expunge them from history entirely?

Why does the party care if people in 2084 know who Shakespeare is?

[Assistant]
As Tyrion Lannister said in Game of Thrones: "When you cut a man's tongue out, you are not proving him a liar. You are only showing the world that you fear what he might say."

If the Party attempted to outright purge classic works of literature that are a huge part of pre-Party culture (which is clearly still lingering on and difficult to get rid of, hence the Ministry of Truth's entire reason for existing) it would be a huge signal to the world that those works of literature are dangerous to the Party. Someone might find a way to hide a copy and hang onto it. Perhaps over time, that copy might contribute to the foundation of a resistance that will eventually overthrow the Party.

By releasing edited versions of the literature, the Party slowly muddies the water over time to the point where the original loses its power to hurt them. People won't see it as proof that there exists a factual reality outside of the Party's doctrine, they'll just see a "wrong" or "misprinted" copy of the literature that they're already familiar with.

Romeo and Juliet didn't die for love, they died for the Party, silly. Where'd you find that old piece of rubbish?


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

[User] Why does ice pop when you pour water on it?

[Assistant]
Thermal expansion. The ice warms, causing it to expand. Once the stress is too much on the ice, it snaps, making noise.

Pouring the water onto the ice would make a liquid flow, which increase the rate of heat transfer, making the noise created more obvious.


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

[User]
ELI5: Why does bring your knees up to your chest relieve stomach pain?

Just wondering how bringing your knees up to your chest relives stomach pain.

[Assistant]
Something along the lines of: when you bend your knees up to your abdomen, it relieves the pressure inside your abdominal cavity that is causing the pain (usually triggered by the nerves in the lining of the abdominal cavity rather than from organs, themselves)

Edit: Textbook answer:
"A patient with severe abdominal pain will often...draw his knees up toward the chest, and breathe fast and shallowly to reduce the movement of the diaphragm. The condition usually involves irritation of the peritoneum (lining of the abdomen" (Brady Prehospital Emergency Care, 9th edition)


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

[User] [MCU] Just as a comparison, how strong or durable is Steve Rogers compared to the average man? How much stronger is he over non-enhanced heroes like Sam and Clint?

[Assistant]
Steve's two highest strength feats are probably lifting the girder off of Bucky in the Project Insight carrier, and not getting immediately squished when he grabbed Thanos' hand, trying to prevent him from using the Gauntlet.

The girder probably represents a multi-ton strength feat. His ability to kick a truck and send it skidding, and curl a helicopter trying to take off, all suggest similar strength levels.

As to durability, Thanos is at least as strong as the Hulk, and while he wasn't going all-out when he backhanded Steve, Steve still tanked a shot from one of the most physically powerful characters in the MCU.

Bucky is playing the same game as Steve, but he received a lesser version of the Super Soldier Serum, and his physicals aren't quite as impressive. Sam is probably near Olympic athlete levels of physical performance, and has excellent reaction times, but isn't even close to Steve or Bucky in terms of strength or durability.


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

[User]
[Asimov] If a robot sees me being attacked by another person, will he attack my attacker in order to save me?

The 1st law of robotics states that a robot may not injure a human being or, through inaction, allow a human being to come to harm.  So, what happens if a robot needs to injure one human being in order to save another?  What will it do?

[Assistant]
Yes, it will save you by inflicting the minimum amount of harm possible in order to stop the assault.  Or, alternatively, if the amount of harm being done to you is less than what it would take to stop the assault, it will let the attack continue.
In either case it's positronic brain will likely be damaged by the event.


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

[User]
ELI5: Why are typically those cities with the highest housing prices so crowded?

And how can actually so many people afford living in e.g. New York, Hong Kong or Paris, when the average housing prices are so incredibly high?

[Assistant]
You are looking at it backwards. The prices are high BECAUSE it's crowded.

Those places are crowded because more people want to live there. Each place has their own specific reasons, but the crowds CAUSE the price.


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

[User]
[That Mitchell and Webb Look] What happened to Sir Digby Chicken Ceaser? Did he ever defeat his nemesis?

Edit: Sir Digby Chicken *Caeser*. Clearly this error was the work of Sir Digby's nemesis himself.

[Assistant] Sir Digby's ceaseless fight against misery, injustice, and having to buy something just to stay in a shop continues to this day. Wherever criminals or inattentive old ladies can be found, he's there. Whenever the Realm is in peril, he appears (unless he's on remand). He is: **Sir Digby Chicken Caesar!**


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

[User]
Afraid of posting pre-prints

Am I stupid for being afraid of posting pre-prints? I am afraid that since I am an early-career researcher, someone will steal my data or whatever. Am I silly?

[Assistant] If your field commonly uses pre-prints, then it doesn't really need to be an issue. If you're submitting to an established pre-print server, and it has been accepted and given a DOI, then there is a clear record that you were doing this first.


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

[User]
ELI5: Why is Norton hated so much? What makes an antivirus/antimalware program good or bad anyway?

Follow up questions: Given it's so notoriously bad for some reason, how come sales reps at electronics stores push it so hard?

And also, what's the best antimalware software?

Edit: Oops, sorry, I just found a previous question about Norton. I *did* search for it so tbh I'm not sure what's going on there. Consider the first question redundant then :)

[Assistant] Nobody likes Norton because it is a resource hog that slows your computer down. It doesn't effectivly do it's job. Norton's CEO even admits that it only gets 40% of viruses at best. So why would people pay outrageous for a program that slows down their computer, and only does less than half the job. Stick with Microsoft Essentials; it is free and makes sense that Microsoft would know the in's and out's of their own code better than some 3rd party like norton. Norton is a complete waste of money.


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

[User]
ELI5:Why some accents are loved while others are frowned upon?

Is some logical reason behind it, which makes the accent likeable.

[Assistant]
It can be influenced by your own language and experience, but in general there's two contributing factors.

First is our expectation: "Frrench is ze lang-wajj of r-r-ro-MANCE!", for example. So if we're a bit romantic at heart a French accent may make us have a positive response. This has been influenced by the media too - certain languages and ways of speaking are often associated with villains in movies, for example; others are often associated with nurturing characters (Mary Poppins). And some are unfortunately tied to more redneck or primitive feelings (Disney Goofy's "Gawrsh!" and "Hyuck!", for example) versus the sophistication of a Cary Grant or Hugh Grant.

But a big part of it is some languages have a cadence and flow in them that is less guttural and harsh than others. Compare the "lilt" of an Irish person's speech against the guttural harshness of a German one or the abrupt jarring of a heavy Cockney accent. We're inclined to prefer the former due to its smoothness and flow.


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

[User]
[Star Wars] How do human characters understand droids like R2D2 and BB8?

How do human characters (and others) understand what seems like random beeps and whistles? I get that they can emote with certain sounds (ie screaming or being excited) but how do people actually understand what the beeps and whistles mean?

[Assistant] The beep and whistles are a form of binary. So understanding it wouldn't be much different than learning morse code. Not many people understand binary though, people like Anakin spend so much time with droids they just begin to understand it. Due to the intended uses of the droids, they don't really need to communicate with people in such a way/more sophisticated languages not worth programming. Droids that only speak binary communicate with their owners through written basic that's displayed on connected computer screens. Like through the interface on a X Wing for example.


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

[User]
[Batman] Do chaotic and crazy criminals like the Joker; actually pay their henchmen, or do the henchmen follow out of fear?

Im speaking to modern era Joker... the one more geared toward destruction and chaos over the Silver Aged, gimmick related crime committing Joker.

Are there any issues related to the financial foibles of trying to manage a payroll or having to have a budget talk with the crews CPA?

Does someone of Jokers erratic mindset have the mental acuity to understand that people are depending on him for a source of revenue?

[Assistant]
It's mentioned in a comic that the Joker's erraticness makes working for him a gamble. His crimes are more about philisophical points and batman then money, but he does steal money anyway. He just doesn't care about it. So if he steals a million dollars, he might just *give* you the million dollars if you ask nicely.

It's a gamble- some days he might not pay you at you and shoot you if you complain- but if you catch him in a good mood he can pay a lot more then a saner more reliable boss. It's a high-risk/high-reward strategy but, if you're not comfortable with risk, you don't work for the joker.


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

[User]
ELI5: Why certain types of comedies were popular in the past but not in present times?

Not that they lose their punch but it seems like we cycle in types of humor. Like we start with slapstick, then went to wit, then went to shock value.

Why do we crave different or new comedies rather then one specific type?

[Assistant]
The basic formula for comedy involves someone in a situation doing or saying something that's unexpected. Not everything unexpected is funny, but everything genuinely funny is unexpected.

A joke dies when it's context becomes too familiar. This can happen because we've heard the joke one too many times, or because we've learned a lot more about the premise. For example, jokes about how people use the internet for everything stopped being funny because that's just like now, and blond jokes fell out of fashion after people realized that stereotyping women was dry and predictable. New stereotypes about groups that we haven't historically stereotyped, however, like instagram users, are still funny (but will soon also get old).

Once it is expected, a joke stops being funny. Humor is an ever-expanding art that needs to be improved and refined over time. This can take place over whole genres - the idea of physical violence being used in common scenarios without anyone really being hurt was very unexpected once upon a time, and you'd be all "WHAT" when Punch hit Judy, but today slapstick is tired and old.


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

[User]
My friend's mom died this morning after a 3 year battle with cancer. ELI5 why it's so hard to cure, and why we haven't done it yet.

EDIT: Thank you everyone. Your replies have been extremely helpful. My friend was actually the one who asked me this question this morning, over the phone. I'm going to tell him about this thread in the morning. Meanwhile, I think I'm going to take a break from reading and upvoting replies and get some sleep. Something about simple science that gives you a little peace of mind. Thanks you guys. :)

[Assistant]
Cells in your body duplicate to replace dead cells. They know when and how to do so based on information found on their DNA. When a cell replicates it makes a copy of the DNA for the other cell, but sometimes something goes wrong during this process and the other cell's DNA is messed up.

Now most of the time this is fine but should there be an issue in the DNA about how and when it should replicate the result can be a cancer cell. Cancer cells split constantly, producing even more cancer cells that continue to split. The resulting group of cancer cells is called a tumor. If the tumor gets to big and damages a vital organ the result can be death.

It is hard to cure because you have to find a way to kill every single cancer cell without doing to much harm to the rest of the body.

Sorry to hear about your friends mom :(


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

[User]
Having debts during time of inflation is a good thing?

Let's assume you borrow money let's say for a mortgage an have a fixed interest rate of 1% for 10 years, and all of a sudden the inflation rate is 5%. Isn't this a great situation to be in for the mortgage holder?

If so how do you calculate how much you are better off?

Let's say I borrow 100k. Need to pay 1k in interest but in real terms 100k would be 95k because of inflation. So the 1k that I need to pay is better than the 5k that I lose right?

Does that make sense at all?

[Assistant]
Yes, you are correct.

You could also say that the real interest rate of your debt is 1%-5%=-4%.

Of course it doesn't necessarily work out that way in real life. Does your wage keep up or not? On average it does, but especially with sudden jumps, this can be a bit laggy.

Also, with expected inflation, as it is the case when banks meet their inflation target of ~2%, this inflation target is baked into interest rates so that the real interest rate is not affected. Unexpected jumps in inflation can still lead to benefits on that front. But many interest rates are also tied to inflation in some way.

In short, unexpected jumps can be good for debt whose interest rates don't "keep up", and if it's not offset by other negative effects of higher inflation.


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

[User] ELI5: How were the 'adult' ages of 18/21 established in the western world for things like voting, drinking, legal liability, etc.?

[Assistant] 21 was first for voting decided at the framing of the US. It was figured that you were likely married and might start owning land that young. It likely also flowed from the British system. Eventually states started making drinking (generally 16-18) and legal adulthood laws(generally 18-21). The military started bringing up their minimum recruitment age to 17 with parental consent and 18 without. Prohibition made alcohol legally banned so when it came back, the rules were generally stricter than before with most states setting it at 18 for purchase. During the Vietnam war many 18-21 y/os were serving, but missed out on the election. Massive protests and activism led to the 26th amendment bringing the age of voting to 18. Shortly after it applied to all local votes too. Mothers Against Drunk Driving started a campaign to reduce fatalities and lobbied individual states and the federal government to raise the drinking age to 21. Many states did so on their own, but once the federal highway act funding required the 21 limit it was pretty much set in stone.


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

[User] How does sound pass though objects, but light (mostly) cant?

[Assistant] Sound waves are a series of uncompressed and compressed molecules. When you slam your book on your table, the molecules of the book pushes the table surface molecules down, which gets them pretty close to the next set of molecules. The first group then retracts since they don't want to be so close to the other molecules, and the same goes for the second set of molecules, except they push further down. This continues until the energy dies out, or when it reaches the other side of the table, except the molecules being pushed are air molecules, which will also continue until the energy is lost. This *is* a sound wave, so it's not the fact that sound waves are traveling through an object, it's that the sound wave is manifested *in* the object(s).


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

[User]
How can the liver break down so many different chemicals?

The liver is where a lot of chemical compounds are broken down into useful or waste compounds. But how does the liver correctly handle so many different compounds? There are literally thousands and thousands of different compounds we can ingest, how do the liver cells know how to deal with each one correctly?

[Assistant] The liver has a lot of different enzymes and isoforms of those enzymes that takes care of most things we encounter in the world.  All these enzymes systems are in homestasis with your body at any given time. That said, there's only about 12+ or so reactions that take place in a biochemical system and your plethora of liver enzymes and their isoforms can cover most anything you can run in to. Problems occur when a toxin irreversibly binds to a specific enzyme and the regular ligand can't bind. An example would be cyanide which binds and enzyme in the last step of making ATP, the energy your cells run on. Basically the body runs out of ATP and its ability to make more and you die. Another way you can die is if you overwhelm a particular enzyme system by taking too much of a substance.  The liver is an amazing organ but we still need to take care of it. Avoid over doing on any substance, food or drug, including alcohol and you can live a full healthy life.


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

[User] Physiologically, what is happening during heart palpitations?

[Assistant]
It depends.  Frequently; absolutely nothing abnormal.  Usually if it isnt simply anxiety, its either atrial fibrillation, atrial flutter, tachycardia (the very unspecific SVT or anxiety induced sinus tachycardia for example), or frequent PVCs (premature ventricular contractions.  Occasionally youll see palpitations that are the result of nonsustained ventricular tachycardia (NSVT) but that typically only occurs in folks who already have known heart failure.

Edit: Im not going to go too deep but to be more help:  most of these are the result of some combination of one or more of the following; electrolyte disturbance (usually an excess or deficiency of potassium and/or magnesium), overactive thyroid, family history, interruption of the normal conduction pathways due to heart damage (usually from heart disease), extra corporeal stimulation of heart tissue from something like an implanted device or catheter (usually a central line of some sort that is placed too deep), or irritation that results from manipulation during open heart or thoracic surgery.


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

[User]
[Marvel] What kind of pranks do teams like the Avengers and the X-Men play on each other?

I imagine Spiderman webbing up door handles and Iceman freezing the Jean Grey school hallways.

[Assistant]
* The classic "Mjolnir on a toilet seat" bit.

*  Assuming there's a statue of a dead professor, enlarging its head.  Massively.

* Similarly to the above, shrinking the X-Jet.

* Random mid-afternoon downpour on campus.

* Danger Room auto-locks and instead of generating holographic enemies it blasts Caramelldansen at full volume, not freeing them until the entire team does it (or vocally admits that the Avengers are the better team and that Iron Man is the best).

* Cerebro gets tuned to amplify more...base thoughts.  Similarly to the above, users can't shut down the system until they find a woman fantasizing about Tony Stark.

* Professor for home economics is out for the week and replaced with Vision.


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

[User] Why did tardigrades evolve to be so resistant to everything?

[Assistant] They live in environments that change drastically throughout the day, like the droplets of water on moss. The moss will sometimes dry out, and to survive this they enter their tun state - think hibernation combined with freeze-drying yourself. They end up a shriveled little ball a fraction of their original size, and then expand and return to normal when the water comes back. They also can enter their tun state for things like temperature changes they'd otherwise die from. They don't seem to age much during this process and have lots of resistance to radiation in their tun state, which is a lot more useful when you're that small and radiation damaging a single cell could mean you lose an entire eye.


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

[User]
ELI5: why does the sound of thunder come in successive booms?

Okay, bear with me.

Im sitting outside watching a thunderstorm, and I see a bolt of lightning flash. I do the counting thing, to tell me roughly how far off it was, and it finally came back at 4 seconds. But then it kept going for another second or two.

I understand how the sudden burst of energy causes the hot air to rush away faster than the speed of sound, but Im curious why we dont just hear a single boom?

[Assistant] The average lightning bolt is five miles long. That means that for any given bolt you are unlikely to be equidistant from every part of it, meaning we would expect the sound to be drawn out to some extent. Another factor is that the sound will bounce off large features such as hills and mountains, again extending the sound by echo into a longer rumble.


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

[User] ELI5: If humans can only hear sounds between 20Hz and 20,000Hz, how does it matter if headphones and speakers have frquency ranges that are greater than 20-20,000?

[Assistant]
We can feel frequencies below our audible range. Some film producers/directors use "infrasound", as in, sound that has a frequency of below 20hz to introduce suspension or fear in the audience to enhance a scene.

When you are walking on a suspension bridge and it sways, you can feel that, its still vibration, just not audible. If the bridge vibrated hard enough and fast enough, you would hear it as it would push and pull the air fast enough to make it audible.

In terms of headphones, the effect of infrasound and sounds above 20khz are negligable. That's because the drivers \(speakers\) in your headphones are more than likely too small a diameter to accurately produce those frequencies to a sound pressure level \(db\) that you would be able to "feel".


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

[User]
ELI5: Why is it that when electronic devices malfunction, turning them off then on works so frequently?

E.g computers, Wi-Fi routers, tvs, consoles. All these items malfunction every once in while and all I do is turn them off then on again to get them working again. Why?

[Assistant] Most electronics work via a chip that has memory of what it is supposed to do. Like a set of instructions. Sometimes it gets overwhelmed and loses its place. When you turn it off and back on, you reset it to start back at step one, so now it knows its place and what to do next.


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

[User]
ELI5: when a new company trademarks a logo, how does the trademark office know its a unique logo without manually reviewing millions of other logos?

Bonus points - how did they do this before they had computers to help?

[Assistant] Trademarks are only valid for the line of business it is actually for. For example using five rings to promote your sporting event is a big no-no because it resembled the olypmic rings. However using five rings to promote your line of sports drinks is fine, assuming nobody have registered a similar trademark to promote their line of sports drinks. This means that the patent office does not have to look through all logos to find similar ones but can limit themselves to one section. In addition any logos that is submited for trademarking requires a text description. This can be used to look up an index over already trademarked logos. In addition a granted trademark may be appealed if it can be shown to have been erroniously issued. So even if the patent office misses the similarities between two trademarked logos this may be resolved once these similarities are discovered later on.


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

[User]
Why is the Earth not tidally locked with the Sun?

The moon is tidally locked and always has one side facing Earth, so why doesnt the earth do the same with the Sun? Given enough time, will it?

[Assistant] Theoretically yes, eventually it will. If the sun doesn't expand into a red giant and consume it before that happens. The moon is a much smaller body and probably had less spin to begin with to slow down. The Earth IS gradually slowing down, though. Days were shorter during the time of the Dinosaurs.