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

[User] [The Iron Giant] How well would the iron giant hold up in other universes, say like the MCU, or star wars, star trek, etc...?

[Assistant]
The problem is we know virtually nothing about the upper limits of the Giant's weapons, armor and regenerative capability.

- His firepower throws tanks around, but we can't see much damage (minus the one that is literally vanished into nothing). The chest-cannon is quite powerful - I'd estimate it in the tens-of-kilotons range, possibly more due to unexplained mechanics - but we have no information on how fast he can fire it or how it affects things caught in its blast radius

- His highest tanking feat - surviving the detonation of a Polaris A-3 missile -  was at most ~600kT, a relatively low limit by sci-fi standards. Moreover, due to how nuclear warheads work in space, it's quite possible he took far less direct energy. We don't know how he'd react to a much more powerful weapon impact.

- Similarly, we see him pull pieces back together and fix a dent in his head - but how far does this affect go? Can he regenerate bits being melted off by energy weapons?

I would personally suspect he in the middling range - above something like an AT-AT, but well below something like a Bolo or most starships. Dedicated anti-armor weapons in assorted universes may have a better chance of permanently wrecking him.


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

[User]
ELI5: Why does bowel tissue fuse with skin in an ostomy, when it otherwise normally keeps to itself?

My brother has a bowel ostomy, and the edges of his bowel (which have been brought out to the surface of his abdomen) seem to have grown into (ie fused) with the skin around the ostomy opening. Yet internally the bowel doesn't fuse with all the other stuff in the abdomen.

[Assistant]
Actually the organs can 'fuse' to other organs within the abdomen. It's called an adhesion. Surgeons commonly encounter that during hysterectomies, where the fallopian tubes have to be separated from other structures during removal.

However, the intestines are covered by a loose, apron-like layer of fat, called the greater omentum, that protects the bowel and separates it from the inside of the abdominal wall.

In the case of your brother's ostomy, as another commenter said, you have two cut areas that are brought together to heal, and the body being what it is, closes off the gap and forms scar tissue that adheres the different types of tissue together.


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

[User]
ELI5: Why do older games like to crash or have problems on newer computer?

My buddy has a pretty decent pc he can run Doom Eternal at a smooth 60, but when he tried to run Unreal Tournament 2004 it was pretty much unplayable and I was curious as to why.

[Assistant] Think of it as a language. If you'd jump back in time to a year around 1500 a.d. and try to talk to a person speaking the English language, you'd likely have quite some problems because the language changed a lot since then. Ways computers do stuff evolves too, and UT2004 simply doesn't know the latest vocabulary.


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

[User]
[Mass Effect] Why are there only a few variations of each weapon in ME2 whereas there are dozens in ME1?

I know the switch from overheating to thermal clips must have bought changes but come on, in ME1 every single one-room hut had at least five shotguns in a malfunctioning cupboard.

[Assistant]
You know how after a while all the cheap rebranded chine-er, Batarian knockoffs start to look alike? Shepherd learnt to spot the knockoffs more easily.

Not being a sucker, he now spends the extra money he would on buying authentic weapons (instead of those he found) on extended warranties for his shiny gun collection. This is why money is easier to find - he stopped spending a few bucks on replacing every weapon with an authentic one. His doctor, who moonlights as a weapons world clerk making bank from the extended warranties, tells him this is much healthier.


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

[User]
ELI5: Why isn't the human race getting more and more attractive?

Science is not my strong point and this question puzzles me.

People of all levels of attractiveness reproduce, but it seems likely to me that the MOST attractive people are somewhat more likely to reproduce than the LEAST attractive people. This suggests to me that the physical features which make people conventionally attractive should be passed on more and more frequently, resulting in a progressively more and more attractive populace.

Why isn't this the case? ...or is it?

[Assistant] There are different conceptions of beauty, and a lot of them are just cultural, not genetic. Being fat was all the rage once upon a time, and there are still some devoted to the more rotund. In some places a tan is considered great, in others a deathly pale is what gets people going.


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

[User]
ELI5: Where is all the money I pay for University tuition going?

I was struggling with a topic from one of my lectures today because the lecturer's way of explaining it was so terrible  I went on YouTube and a 6 minute explained to me what this guy had taken 3 hours trying to. It made me think, where does the money pay go to?

If it helps I'm at a Scottish University, having to pay 27,000 over the 4 year course.

[Assistant] Well, that lecturer, no matter how terrible you found him to be, still gets a salary, as do all of the other staff at the university, like the people in administration who do all the paperwork, janitors who keep the buildings clean, maintenance workers who fix things that stop working,  the landscapers who mow the lawn and trim the bushes, etc. There are also equipment costs, like replacing computers and fax machines and printers and toilets when they have reached the end of their usefulness. Let's not forget all the bills that have to be paid, like for electricity, water, and sewer. All in all, it costs a ton of money to keep a large university running, and your tuition goes toward all of it.


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

[User] ELI5: when one has a cold, how does snot keep regenerating even shortly after blowing one's nose?

[Assistant]
You've got eight sinuses connected by nasal passages, spread out over the whole top half of your face, and they can all produce and store snot. So, after you've blown your nose, more snot just runs down from another sinus, and you have to blow your nose again almost immediately. Repeat until you've cleared all four pairs of sinuses. Your mucous membranes can produce watery stuff relatively quickly, which dilutes the snot and helps it run faster, and also adds to the volume of stuff you're sneezing out.

There's also a psychological factor- you're not actually blowing out as much snot as it feels like with each sneeze. Same as how when you have a nosebleed or a papercut, it can feel like you're losing gallons of blood- but actually if you put it all in a shotglass you'd realize it's a pretty small amount. This principle also applies to certain other bodily emissions, whose volume men tend to greatly overestimate...


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

[User]
[Pokmon]If Ash had woken up on time and gotten the Squirtle he was originally going to choose, how would that have worked out?

How would the events of the anime have changed, at least in the first few episodes?

[Assistant]
He'd have a Blastoise by now and be straight wrecking fools since Charizard and Blastoise would not get along at first then through some heart warming struggle become best friends and a dynamic duo.

Or...

Squirtle would be a little wary of evolving so Ash wouldn't make(read: let) him then he'd have... a really strong Squirtle....


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

[User]
How to satellites dissipate heat in the vacuum of space?

Since resistors generate heat and many, if not all satellites have a large amount of them on board, how is the heat generated by these resistors dissipated into a vacuum?

[Assistant]
There are three modes of heat transfer in thermodynamics: convection, conduction and radiation.  It is true that there is essentially no convection in the vacuum of space, so all heat generated is dissipated by infrared radiation (electromagnetic waves that travel until they hit some object).

EDIT: heat generated by high output components (processors, memory) may be conducted by heat sinks, but ultimately, any heat dissipated by the system as a whole would be through radiation.


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

[User] Why does audio feedback always resolve to a high pitch tone regardless of the input frequency?

[Assistant]
Feedback at low frequencies is actually quite common. Its not unusual for a subwoofer and a mic to take off together at under 100Hz and rattle the venue until the frazzled operator mutes the channel.

After this has happened once on a show, they will remember that high pass filters exist for a reason and will engage them on every channel that doesnt need low end.

It all depends on the sensitivity of all the devices involved in the loop and the placement of the transducers in the acoustic field. Some combinations will cause low frequencies to take off and feed back, others will cause the opposite.


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

[User] ELI5: When lifting weights why does muscle grow the best with heavyweights in a rep range of 4-6?

[Assistant]
It has nothing to do with the reps, muscles can't count. It has to do with the amount of stress you put on the muscle and for how long.

Best rep range for muscle growth is considered 8-12 reps though. The reason for that is that you can still use quite heavy weight and at the same time keep the muscle under tension for a decent time which uses most fibers in the muscle and therefore producing most overall results.

4-6 is considered more strength training than muscle building.


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

[User] If I were to drink something that is usually injected (morphine, heroin etc.) would the effects be the same as if I were to inject them? If not, why?

[Assistant]
It depends. The concept you are referring to is "bioavailability". A drug has a bioavailability of 100% if exactly the same amount gets into your blood stream if you eat it, if you were to IV it.

However, very few drugs have a bioavailability of 100%, and the reason for this comes to to the interplay between anatomy and physiology.

When you eat anything (but in this case a drug), it goes from your mouth, into your stomach and then into your intestines. Absorption of the drug begins in earnest only once it enters you interestines. The reason for this is because 1) Your intestines have a lot of surface area for absorption 2) then have specialized transporter processes for absorbing things and 3) they have large blood supply, sucking away anything that is absorbed. This blood supply goes to one place, and one place only: your liver.

Basically everything that you eat, that ends up enters your blood supply gets sent to the liver. And the liver is prepared for this. It is a honeycomb of blood vessels, meaning that there is a huge surface area of the liver that is exposed to your blood. And the cells of the liver are packed with enzymes ready to chew up chemicals. There are literally 100s of enzymes at play here. A particular type of enzyme may target a few specific chemicals, or it may be able to chew up a vast array of different compounds. But the point is, that anything you eat has to pass this gauntlet that is the liver and its enzymes. The gauntlet is called "First Pass Metabolism".

Some chemicals can pass through the liver very well. Indeed, drug companies generally try to only work with drugs that do. But some drugs are absolutely savaged in the liver (low bioavailability). Most drugs fall in in the middle range. Morphine has a bioavailability of 20-40% meaning that 60% of it is destroyed by the liver. Ethanol about 50%. You can usually find out the bioavailability of any given drug just by googling "bioavailability <drug name>"


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

[User] [DC / Batman] So I'm just a construction worker fixing this building that was trashed by Batman. I'm told we were hired by Wayne Enterprises and that got me thinking. What does Wayne enterprises do exactly?

[Assistant]
Primarily? Real estate, construction and development, but it's also an umbrella corporation for numerous smaller companies - and "smaller" is very relative here. If it's built, manufactured or sold, the odds are Bruce Wayne has his finger in the pie.

Oh, and fun little sidebar: If you were wondering about your colleagues with the interesting tattoos, you're not just being judgmental; there's a good chance they are indeed convicted felons. Wayne Enterprises is Gotham City's single biggest employer of parolees.


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

[User]
ELI5: How does shifting work? Without it grinding and making horrible noises.

I imagine theres some sort of flywheel or some kind of mechanical terminology. But when Im driving downhill, I sometimes put it in neutral, only to shift back into drive when back on level ground.
(I know, probably unsafe too. In my mind, Im saving $$$)
But when I make that shift, isnt something going from 0rpm, and being engaged to something going 1000+rpm? Shouldnt it make a horrible noise?

[Assistant]
You are not saving money, btw. If you're going downhill, your vehicle's momentum will spin the wheels, which in turn spins the axles, differential, transmission, and finally spins the engine. If you put the transmission in neutral, the wheels can't turn the engine anymore, so the engine will need to consume fuel to maintain idle.

When you shift, there are clutches that gradually match things that are rotating at different speeds. Non-CVT automatics have friction bands and clutch packs, manual transmissions have synchronizers.


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

[User]
[Futurama/The Brain that Wouldn't Die] What is the timeline of advancing head preservation?

Hi, I'm an Earth history major at Globetrotter U. I know that head preservation started with Dr Bill Cortnet in 1962. However he used crude methods that would only last for days. When were some of the advancements discovered that allowed for longer preservation to the point we could keep people alive indefinitely?

[Assistant]
There's a dirty little secret to those rows of Presidential heads: not a single one of them is a real head.  They're all bio-constructs, built as part of Disney's planned Hall of Presidents upgrade just before the Third Korgrian Invasion glassed over Disneyland I.

Never delivered, the heads were put in storage, forgotten, sold, stolen, forgotten again, auctioned off from an old storage locker - passed through so many hands over so much time that no one remembers where they came from or why.

A curator for a museum got his hands on the collection and passed them off as real Presidential heads as a publicity stunt.  That's why there are heads from long before head-preservation technology was invented, heads of two separate Grover Clevelands - they're all cunning fakes, fakes so cunning that not even the heads themselves know the truth.


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

[User] How do we know that a black dwarf star exists if it's never been seen before?

[Assistant] It's thought that they don't exist yet, because there hasn't been enough time for white dwarves to cool. Because white dwarves are radiating away all this energy, it is thought that eventually it will cool through this process. If that is wrong, astronomers in a trillion years can find out.


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

[User] ELI5 why is directly looking at a solar eclipse bad for your eyes?

[Assistant]
Your eyes adjust to the total light in your field of view, not the brightness of any particular object in your field of view.

So during an eclipse, there's less total light, however any visible portion of the sun is just as bright as it is usually, which is bright enough to physically damage your eyes.

Thus, your iris will accomodate by expanding, allowing even more light than usual in, when the light is already intense enough to cause harm normally.


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

[User]
ELI5: How would discovering that something can move faster than the speed of light be related to the feasibility of time travel?

My professor summarized the CERN situation  this way, and I felt like a  year based on my understanding of what he said.

[Assistant]
to our best understanding, particles moving faster than light are moving backwards through time. But the problem is that with our current understanding anything not already moving the speed of light could never move at the speed of light. that means there is no way to speed up or slow down to change between faster than light and slower than light. That then means there is no way to change between moving back in time and moving forward in time.

NOTE: Tachyons, particles moving faster than light, have never been detected.


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

[User]
Question from my son: "Can caterpillars burp?"

Google was not really very helpful in finding the answer.

[Assistant] Burps are caused by releasing gas from the digestive system.  Most of the gas that gets into the system (and has an effect high enough in the digestive system to come out as a burp rather than flatulence) gets there because of the link between our digestive and respiratory systems (causing us to fairly regularly accidentally swallow some air).  Insects breath through holes in their sides called trachae.  Since their digestive system isn't connected to their respiratory system, they have no need to burp.  Some gas will be produced by digestion,however, so they do have flatulence.


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

[User]
[Death Note] What happens if someone legally changes their name, does the death note match names based on legal names or innate names?

So let's say someone legally changes their name would that make  it so that name is now what kills them in the note or is it still their old name, and does it have to be a legal name change? Does the death note like base itself on if its just a name that has been chosen but not legally changed or it has to be legally changed. Does it have to be based on like an innate feeling of the name? Does the death note have any policy for names?

[Assistant]
The Death Note requires / the Shinigami see a person's true name.  This is explicitly not tied to any legal name register. The details of what happens when someone changes their name are sparse, but it seems to be tied to the soul's sense of identity implying:

If you legally change your name and don't tell anyone just to try to avoid the Death note, it won't work.  The user will simply write whatever name you go buy that used to be your legal name.

If you hate your name for some reason and change it, and no longer respond to your old name, the name needed to kill you will be the name you chose whether or not you legally change it.


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

[User]
[South Park] Why can the characters sometimes remember Kenny dying, while other times they can't?

Throughout the series all the main characters get used to Kenny being unable to die. He keeps coming back, born anew with all his memories including the horrible pain he's been through. When that fails he can just fucking appear out of thin air. Oh, hi Kenny.

There's plenty of examples of everyone in town knowing about Kenny. "It's ok, Kenny dies all the time." "Haha, nice one!" By the gnome episode Kyle and Stan just go through their routine quickly and resume the conversation.

It's not limited to the main kids. The whole town is well aware. In one episode Timmy gives Jimmy an orange parka as a gift, and sure enough, the higher powers in this world do everything they can to try and kill Jimmy when he wears it.

But whenever Kenny's death is dramatic, or meaningful, or lasts longer before he returns, it's like people forget. There's video and photo evidence, like when the roller coaster killed him. There's government agencies in this world specifically for investigation into all the paranormal bullshit that goes on.

And yet everyone is shocked and in disbelief when they learn the truth about Mysterion. Not one person in South Park seems to remember anymore. Kyle and Stan don't offer consolation and say gee, I never thought about it that way, it must really suck for you. Cartman doesn't make fun of him for dying again and again.

What force or entity is screwing with everyone's memory? Is it unique to South Park, or a worldwide effect? Does it have anything to do with whatever power makes people forget all the other weird things that happen in their world? Like how talking animals and inanimate objects are normal, yet Token is shocked by talking lions.

We know that God is real, and Satan, Jesus, Moses, Santa, and other powerful beings. Is death itself, or the Grim Reaper, real and on a pissed-off vendetta against Kenny? When Kenny killed Death in a dream, was that less metaphor and more literal description?

[Assistant]
Kenny's curse comes from an Elder God, similar to Cthulhu. The rebirth, the memory loss, the lack of terror, everything.

But South Park is a town of powerful beings. Jesus, Satan, sentient towels and feces. Sometimes the power clashes against the curse, weakening the memory loss.


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

[User] ELI5: What is Geofencing?

[Assistant]
The wikipedia page explains this well :

>A geo-fence is a virtual perimeter for a real-world geographic area.[1] A geo-fence could be dynamically generatedas in a radius around a point location, or a geo-fence can be a predefined set of boundaries (such as school zones or neighborhood boundaries).

>The use of a geo-fence is called geo-fencing, and one example of usage involves a location-aware device of a location-based service (LBS) user entering or exiting a geo-fence. This activity could trigger an alert to the device's user as well as messaging to the geo-fence operator. This info, which could contain the location of the device, could be sent to a mobile telephone or an email account.

So, basically, a geo-fence is when instead of installing a real fence, you program a computer to tell you if you're inside or outside the fence.


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

[User]
Why do antidepressants make depressed people commit suicide?

If I'm understanding this correctly, people that are already depressed take antidepressants but not until they take them do they usually go as far as suicide? What makes them actually go *that* far?

Do they simply mix the meds or accidentally overdose? Is it something in the meds that stimulates the "depressed stuff" even more until its unbearable? Do they get like schizophrenia?..

**edit**: Oct. 26: Sorry I have not replied but i have read every last reply and thanks for responding. My computer recently died but I see these are some really emotional responses. Thank you for answering and I wish you all good health.

[Assistant] Mental health worker here.  Sometimes suicide happens when people begin antidepressants because they actually feel an upsurge of energy, which allows them to act on suicidal thoughts and feelings which might have been lingering prior to taking the meds.  Some depressed folks are too despondent and hopeless to actually act on their suicidal thoughts and the tiny boost that the meds give them can push them into action.


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

[User] [The Handmaids Tale] Are you able to leave the country at any time if you have a Canadian/other countrys passport?

[Assistant] I think it's roughly comparable to Americans visiting somewhere like North Korea/Iran today. It's likely that everything will be fine and you'll be permitted to leave, but you'll be watched closely and it would be *extremely* inadvisable to step out of line.


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

[User]
ELI5: What's that weird tingling sensation I feel in my crotch when I'm on a roller coaster or swing?

Pretty self explanatory. There's a weird sensation that goes through my crotch...like through the testicles to the upper abdomen whenever I have an experience of weightlessness, what is that?

[Assistant] Your body is use to certain pressures and changes in pressure, like when you trip.  A feeling of weightlessness is a pressure you are not familiar with and the result is a unfamiliar tingle in your guts, which is rich in nerves.


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

[User] What does Curiosity do besides taking pictures of Mars?

[Assistant] It's got a chemical sniffer, a laser, and a drill.  All for looking for chemistry of one form or another that might indicate prior life, or the possibility of future life.  And when it meets Spirit and Opportunity they can join to become MegaRover!


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

[User] ELI5 : How can some people with less muscle mass have more power than those with more muscle mass?

[Assistant]
At carnivals, there's the one game where you hit a seesaw with a hammer to launch a weight at a bell. It measures how much power you can transfer from the hammer.

Technique matters more than absolute muscle mass. People would fail to hit the bell if they swung the hammer downwards with only their arms since that only uses the triceps. If you swung the hammer with a full swing using legs, core, and arms, even someone with lower muscle mass can transfer much more power since they are using multiple muscle groups.

Secondly more muscle may prevent you from  using your full range of motion. Overweight or obese people have more muscle mass simply because the muscles need to be strong enough to hold up the extra weight. However, the fat will act as padding and dampen how much power can be transfered.

On the other end, people with too much muscle may not be as flexible as someone with less muscle. If you were doing martial arts which requires swinging arms and legs, a heavily muscular person's arms and legs would hit their own muscles when swinging, reducing the power transferred.


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

[User]
[Invincible] Spoiler question

Why didn't Omni-Man start a breeding program on earth?

Why invest so heavily into one child?

I haven't read the comic but Omni-Man methods doesn't add up.

To me, Cecil could've easily set that up for him and trusted him enough given his amorality or he could've done it himself by just having a polygamous relationship.

Also why didn't Omni-Man just get rid of his bloody uniform?

[Assistant]
Both of these questions are answered by what's going on inside Nolan's head, as well as why he ultimately stopped before killing Mark.

Everything he says during his argument and fight with Mark about how much better the Earth and Humanity will be in the Empire is complete bullshit and he knows it, always has. He's long questioned the expansion of the Empire and ways of his people that he's been brainwashed into following along with.

He probably would've done everything you suggest... if he hadn't met Debbie. Her love was slowly changing him over all of those years, making him better and making him happy to just be Nolan Grayson/Omni-Man. But then Mark became...

***INVINCIBLE*** *blood splatter*

Mark gaining his powers set something off in him, something that had been drilled into his mind for centuries by the Empire. All that propaganda, the pain of his own vast lifespan compared to those of everyone he loved, the idea of Mark being condemned to that same sad eternity, the fear that maybe the Empire is inevitable and will conquer Earth with or without him.

He started fighting against himself and the good in him... lost.

The Costume stemmed from the part of him that wanted to get caught, stopped, killed, whatever to end this Hell for him.

Also, maybe the one Mark was easy enough for him to fight, but imagine if all the Breeding Camp kids turned on him...


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

[User] When losing weight, how does the body choose where to pull fat from?

[Assistant] When we burn fat our fat cells start turning the fat they store into fatty acids which can then be transported by our blood causing the fat cells to shrink. The fatty acids don't come from one specific place, all our fat cells start pumping out fatty acids. How much comes from  specific area is determined largly by genetics and not like many people seem to think by the muscles you are using during excercise. So cycling won't make your legs any slimmer than it will make your arms.


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

[User]
ELI5: Why can't manufacturers include a sturdy gps system inside of a plane's "black box"

Seems that every time a plane goes down there is this massive hunt to try and find the black box. If the box itself can survive the crash, I would think it'd be possible to design a small and sturdy gps tracker that could also survive. Do they already have this? If not, why not?

[Assistant]
TV and the movies has lied to you about how GPS works.

All a GPS unit does is receive signals to tell it where it is.

By itself a GPS unit never tells anybody else where it is.

In order to find something's location you will need something that sends signals not receive ones.

If you put a GPS tracker on something or someone, it works by figuring out where it is and then sending that information to someplace else by cell-phone or by something.

A plane has a GPS unit built in and the information from it gets send to the blackbox. Once the plane is on the ground the data in the blackbox knows excatly where the plane is (or at least where it last was before the gps receiver stopped functioning.)

The blackbox knows where it is. That is not the problem. The problem is getting that info out to the people looking for it.

You could built a cellphone device into the balckbox to try and call home with its last known location, but what are the chances that the plane went down anywhere where you have cell phone reception?

Instead the balckbox will send out a radio signal that allow people to find it.


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

[User] ELI5: Why is it when propellers or wheels on cars reach a certain speed, they appear to be traveling slowly in the opposite direction?

[Assistant]
An image is recorded as a high number of still frames per second, which are then played at high speed to give the cognitive impression of movement.

Think of it this way:

Imagine that you've got Bruce-Lee like reflexes. Someone tells you that they are going to take 4 photos of you in one second, and they want you to raise your arm to shoulder height, and then lower it back to your hip as fast as you can.

Being so fast, you can do this exactly four times per second.

The photographer shouts "Go" and your hand raises to shoulder height - the first photo snaps.

1/4 of a second later, your hand has gone back to your hip, and back up to shoulder height. The camera snaps again.

This happens 2 more times.

Now, to anyone who looks at those photographs, it will for all the world, appear that you stood there with your arm at shoulder height for a second. They will never know that you lowered your arm four times.

So, lets replay this experiment, except you can only raise your arm **three times** in one second.

So, you raise your arm, the camera snaps *just before* it gets all of the way up.

1/4 of a second later, and you're lagging behind even further. The picture is taken, but now your arm is slightly lower than in the previous picture.

The next one, even lower.

After the pictures are developed, it will look like you have taken one second to lower your arm from just below shoulder height, to about 3/4 of the way to your hip. They will not know that you actually made the complete up-down cycle 3 times in that second.


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

[User]
Is there a reason Yes took multiple etymological paths?

I tried looking up the etymology of yes, si, ans oui and had trouble relating them all back to any common branch point. Etymologyonline says that yes derives from an Old English word, oui is a compound of two Old French words, and Si goes right back to a Latin derivation. And all three origins seem to have slightly different meanings.

Seemingly "yes" means the same thing in all the romance languages now so how did it take so it it something like convergent evolution or was there some common branch point.

[Assistant]
Well, English isn't a Romance language, so there's no reason to assume that the word "yes" would look like anything in Latin, much like "water" looks nothing like "aqua."

Past that, Latin had no word for "yes," so you wouldn't necessarily expect that the Romance languages to have the same word either. Much like how Latin had no word for "computer," meaning that there's no real connection between the Spanish "computadora" and French "ordinateur."

What happened is that the various Latin vernaculars developed their own different ways of saying "That thing you said is what happened," with "si" developing from "sic," which means "thus," and "oui" developing from "hoc," meaning "that thing."

The idea of "convergent evolution" would then center on a common need for expressing agreement and not the form this agreement takes.

Keep in mind, too, that there are many ways of expressing agreement besides the word "yes." Such as the "I do" of the traditional wedding vows. Also, it's possible to have multiple words for "yes." French, for example, has two, depending on whether the statement being answered is affirmative or negative, and they are not interchangeable. So, there may not be as much "convergent evolution" as you might think.


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

[User]
How do scientists distinguish between states of matter other than the classical four?

Is there a standard that defines what is or what is not a new state of matter. I was always fascinated by the subject and i was curious about how much matter you need to define a new state.

Wikipedia does have a giant list of modern states but the properties that distinguish the states seem so random.
In contrast solids, liquids gases and plasma seem to be very different.

[Assistant]
"States of matter" are not a simple tactile or easily observable property. A state is a "region" in the space of physical quantities (temperature, pressure, etc.) where the properties of matter are well defined and continuous. Between two different states there is always a "discontinuity" in the beheaviour of matter when altering these physical quantities.

One classic example is that the more heat you give to a liquid (for example water) the more its temperature increases (physical quantity). This happens continuously up to a certain point (evaporation point), when adding additional heat will not increase the temperature of the liquid, but will start a process of transformation to another state, gas (discontinuity). When the liquid is all evaporated and transitioned to the next state, gas, adding additional heat will again increase the temperature of the system, exactly like it did before the transition.

If you extend this idea beyond temperature and to other quantities, you realize that you can define a new state every time you have a discontinuity in one or more physical quantities.


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

[User]
CMV: Sexual health classes should be required as part of the comprehensive curriculum in all public schools in the United States

Providing youth with sexual health education is critical in informing their future decisions to engage in safe sex practices/behavior and improving their overall health outcomes. Providing safe sex education provides students with the knowledge of the health risks associated with engaging in unsafe sex behavior and the associated health outcomes such as STIs and unplanned pregnancy. It gives them the knowledge on how to make smart and informed decisions regarding their health, whether they choose to engage or abstain from sex. This education provides them with tools to protect themselves and make smart decisions for their health.

This education can also promote more open communication between students, their parents and health care providers. Students may feel more encouraged to ask questions. This communication can help decrease confusion and misinformation that students may be exposed to in the media or online. In addition, having an open chain of communications on the topic of sex and sexual health may help eliminate the stigma associated with it.

If more people are aware of the risks associated with unsafe sex behavior, they may be better informed to either engage in safe sex behavior or abstain. These behaviors can decrease rates of STIs, unplanned pregnancies and the associated health care costs.

[Assistant]
I agree with the basic premise of your argument, but with one caveat: how would it be possible to enforce this? We give states absolutely gigantic leeway when it comes to setting educational standards. If it's required on a federal level, it will also have to be funded, or states will push back. And funding for comprehensive sex ed seems unlikely given the current political climate. So sure, in an ideal world it should be included. But we're living in the real world, where it may not be feasible.

Of course, this assumes you mean to institute this in the US, and not another country.


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

[User]
[Anime] Why do anime characters yell their attacks?

Lots of anime characters shout the name of their attack before hitting their opponent. What is the point of this? Is your punch more effective if you yell "Super Destruction Punch!" before landing the blow? Are they just doing it to sound cool?

[Assistant] It's because of the same reason they keep having long internal monologues in the middle of intense battles. Anime characters have massively shit attention spans, and have to constantly remind themselves of what they're doing. This, combined with the rush of adrenaline, is what causes them to shout out the names of their attacks.


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

[User]
[Star Wars] Can I purchase a personal shield that will make me immune to blasters?

Money is no object here, although obviously cheaper is better. I've heard they had shields this size during the Clone Wars, so they must exist, right?

[Assistant]
Immune? No, not immune. Nothing carryable by a person will make you *immune*. Even the shields carried by Droidekas could be downed by sustained blaster fire.

Personal shields which could absorb a limited amount of Blaster fire were indeed common. As you've heard, they were used by both the CIS and Republic during the Clone Wars; later, the Galactic Empire sometimes issued them to high-ranking Stormtroopers. They were also used by a number of free agents around the Galaxy.

Strictly speaking, if you had a model with a quick-change energy cell and simply carried enough around, you could absorb a lot of blaster fire in a short period of time - Rebel agent Kyle Katarn was known to do just this. Even that isn't true immunity, though.


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

[User]
Do birds get charged with static electricity while flying? (air friction)

If so, do they get a shock when they land or touch other birds?

[Assistant] I don't know about birds, but honey bees build up a static charge as they fly through the air. They use it to their advantage when they land on a flower, pollen jumps up and clings to them when they land.


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

[User] Does a change in the curvature of space-time literally change the shape of a local object?

[Assistant]
First it helps to think that objects, as defined and perceived by humans, are fundamentally manifestations of fields in space-time; you can't separate them.

Now if you draw a circle on a piece of paper it is only a circle because the paper is flat.  If you curl the paper up  it is still the same drawing, it is still a circle if one considers only the surface of the paper, but it is not a circle if one considers the projected image on another flat surface (yet the circle itself has not changed).  Likewise if we have a really long pole in space that is curved only to the right (space itself curved that is), standing at one end and looking down its length it will appear straight, but from above it will appear to bend to the right.  In fact the only way to define the pole as straight is to choose a co-ordinate system that makes it such.

So the answer to your question is that there is no 'shape of a local object' to change.


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

[User]
To eliminate the need for an extra day every four years, why couldn't we just redefine the second?

Since we need (approximately) one extra day every four years to keep our calendar in sync with our orbit, why couldn't we just multiply (four years +1/ four years) 1461 / 1460 = 1.0006849315... to each existing second? After four years' time we'd be enough later to eliminate the need for the leap day, right? Obviously all GPS satellites/world clocks/etc would have to be adjusted but that seems like something that could be done.
I know this is missing something but that why I'm here!

[Assistant]
This would mean a day is not 24 hours any more. So each day, "midnight" would slip a little bit. After 2 years, "midnight" would be in the middle of the day!

The fundamental issue that can't be solved here is there are not an integer number of days in a year.


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

[User]
[Spider-Man] Why is someone as intelligent as Peter Parker so poor? Wouldn't a kid like him get a full scholarship somewhere? And possibly invent something marketable?

I feel like the kid could be making way more money than he is. What's the deal?

[Assistant]
He has actually. It took a while because he struggled managing college and being a superhero, but now he has his own tech company. He's making a name for himself and might be the next Bill Gates, Elon Musk, or even Tony Stark.

Poor Parker is just a misconception with the character. When people think Spider-Man, they think of the nerdy teenage kid living with his aunt, suiting up to kick ass at night. That was years ago. Pete's in his late 20s now, maybe early 30s.


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

[User] [Harry Potter] I'm a first year at Hogwarts, and I just heard a rumor that Professor Moody is actually a Death Eater disguised using Polyjuice Potion. Apparently it's easy to make, because 3 years ago, a first year made it in a toilet. How paranoid should I be that there are imposters all around me?

[Assistant]
First off, you heard wrong details.  It was two years ago, and it was a second-year

Second, this particular second-year is an extremely talented and knowledgeable witch (often cited as the brightest witch of her age), who had a very powerful personal motivation to make this potion properly.

Third, what you apparently never heard is that the potion is extremely difficult to make properly, and the fact that this young witch could do it at all, let alone at such a young age, says far more about her talent than it does about the ease of making the potion.

If you want to worry about being surrounded by impostors using Polyjuice Potion, youd be better off being worried about whos capable of buying it in the black market in Hogsmeade or in Knockturn Alley.


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

[User]
[Marvel/DC] Are there any laws in the US or abroad regarding the occult?

I was just watching the JLU episode where Grundy is resurrected by a trio of kids and it got me thinking; these are kids that bought a book of spells off the internet that would allow them to get revenge on their bullies. Not only is that dangerous in and of itself, but the spell doesn't even go right and Grundy is resurrected as a mindless, killing machine.

So, with that example in mind, are there laws in either of the major comic universes restricting or outright banning the use of magic or the procurement of magical items by citizens?

[Assistant] Nope, magic is not regulated by law in either universe.  But both universes have the magical realm as self-regulating.  So if you do some vile and twisted dark magic, expect Doctor Strange or Doctor Fate to show up and stop you.  Some kinds of dark magic will require you to break other laws though - like sacrificing someone is still considered murder, and stealing ancient artifacts is still theft.


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

[User]
Will frequently donating blood lead to any negative long term effects?

I try and donate blood (plasma/platelets/red blood cells) about once a month. I am happy to donate but have a slight concern I could be putting myself at risk for something long term. I understand there are some short term side effects when donating blood, but are there any studies suggesting that frequently donating blood can negatively harm your health?

[Assistant]
Plasma is mostly water, which can be replenished quickly. Platelet counts replenish very quickly too. That's why you can do plasma and platelet pheresis fairly frequently.

Red cells take longer to regenerate, which is why you're usually only able to donate once every 8 weeks or so.

If you meet the physical requirements for donating, it's extremely unlikely you'd have any long term effects. If you think it's having a negative effect, try spacing the donations out farther and see if it helps.

Thanks for donating! People need these blood products to stay alive.


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

[User] [Star Wars] I am a young man from an affluent family on a Core World and pretty straight arrow but wish to live the scoundrel lifestyle. What should I do to become a proper scoundrel without ending up being taken advantage of or sold into slavery?

[Assistant] Sign up on a spice freighter. It's pretty above-board, but a bit more rough and tumble than most trade. If it works well for you you'll find an opportunity to branch out once you have your space legs.


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

[User]
ELI5: Does my voice actually sound like that? Why does it sound so weird?

Whenever I listen to myself in recordings I physically cringe (so do a lot of people when they listen to themselves). Does my voice actually sound that bad? I feel like if it did I wouldn't have that many friends so it must not... why does it sound so weird in recordings?

[Assistant]
Imagine the voice coming out of your mouth as a speaker and your ears are two microphones. If you are being recorded or someone is listening to your voice, the microphones are placed in air some distance away from your speaker.

However, what you hear as your voice is as if the microphones are attached to the speakers because your ears are housed in the same head as your vocal cords. What you hear is then not what other people hear since there is coupling between your speaker and microphones.


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

[User] Is a baby's first breath in inhale or an exhale?

[Assistant]
The last fetal organ to mature is the lungs. In the 8th month of pregnancy, the baby's lungs begin producing surfactant, which is composed of phospholipids- mostly lecithin. Surfactant, as you know, is a chemical which reduces surface tension. In a neonate's lungs, surfactants serve both to moisten the lungs (for better gas exchange) and also prevent the collapse of the lung when the baby exhales.

Until the baby is born, it gets all its oxygen through the umbilical cord from its mother and so there is no gas in its lungs- they are deflated and have some amniotic fluid in them. So the first breath of an infant is an inhale, though some amniotic fluid may come out. Once gas exchange is happening in the lungs, vasoconstriction in the artery of the umbilical cord begins to shut off that shunt. Typically the obstetrician will accelerate that process by clamping the umbilical cord less than a minute after birth, but in some countries it is traditional to actually leave the placenta and umbilical cord attached to the baby until it falls off naturally.


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

[User]
Is it currently possible to remove the DNA from an unfertilized human egg cell, replace it with the DNA from two human sperm cells from two individuals, and implant the modified egg cell in a woman's uterus to generate a viable fetus?

Obviously what I want to know is if two gay males can both be the biological father of their child?

[Assistant]
Currently - no.

We don't know how to deal with paternal/maternal effect genes (genes which the only active copy comes from one parent).

Also, remember that clones are typically not healthy individuals (Dolly died very early).  The DNA sequences might be correct, but the epigenetics can still be incorrect.


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

[User]
What is the maximum size a planet can have before it becomes uninhabitable?

I have wondered this for a while. What is the maximum possible size for a planet to have in the habitable zone of its solar system, for it to still be able to support lifeforms?

[Assistant]
There isn't one.  At a certain point, according to most planet formation theories, the planet will be a gas giant, at which point it becomes a lot harder for life to evolve.

But then there's no a priori reason why it's moons cannot be inhabited.


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

[User]
ELI5: Why do metals that are heated sometimes get that weird rainbow colour effect?

A few posts of welding were on the front page a while ago and the welds all had a rainbow pattern. (Will find a link when off mobile). I'm guessing this has something to do with the heat that is applied?

[Assistant] That is oxidation caused by heating.  The degree of heating will determine the color by thickness.  Unless you are an expert reading the colors for heat treatment purposes, it's only decorative as it is only a few thousandths thick.


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

[User] ELI5: What does adrenaline do to a mom that lets her lift a car when she sees her child in danger?

[Assistant] People are incredibly strong, but don't lift to full power because of risks like muscle tearing and bones breaking. So the brain has mental blocks and in an adrenaline situation these blocks are lowered.


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

[User]
[Star Wars] Why didn't Obi Wan do more about Anakin's infatuation with Padme?

Through Episode 2 Anakin's overwhelming love for Padme is about as subtle as the destruction of Alderaan. Why doesn't Obi Wan properly confront Anakin about this and try to help him. He knows that love leads to emotions Jedi shouldn't feel and it's clear that Anakin isn't strong enough to fight them alone. Is there a reason besides stupidity that Obi Wan lest this fester and grow?

[Assistant] Because he feels love for Anakin, and that clouds his judgment and awareness. Obi Wan thought of Anakin as a brother, confidant, and friend, his closest emotional tie. With the death of Quigon, Obi Wan was more or less left without a guiding figure in his life to warn him of such attachments. Ultimately, Obi Wan's love for Anakin prevented him from seeing the danger his friend was in, and Kenobi probably never forgave himself for that.


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

[User]
ELI5: Why does indestructible mean NOT destructible and invulnerable mean NOT vulnerable, but invaluable mean VERY valuable?

Makes a lot of sense now. thanks!

[Assistant]
Indestructible means it cannot be destroyed.

Vulnerable comes from the Latin word "vulnus" which means "wound". So something invulnerable cannot be wounded.

Something that is invaluable cannot be valued, i.e. you cannot set a price on it. So invaluable literally means "priceless": there is no amount of money that is equal to the worth of the thing.


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

[User]
CMV: "Uploading your consciousness" into a computer is an impossible idea that will probably lead to the formation of a suicide cult.

Extremely tech-minded internet types sometimes bring up the idea of "uploading your consciousness to the cloud" as a type of immortality. The idea is you can live forever in a virtual computer world, once all of your thoughts and memories are "uploaded" into the cloud.

This, to me, is a nonsense idea. What they've done is basically reinvented the afterlife. Instead of "if I'm good when I die I'll go live in the clouds" it's now "if I live long enough and make enough money someone will invent a computer and I can live in the cloud". The science doesn't make sense. Even if your memories and thoughts could be uploaded and integrated into an AI, it wouldn't be you.

What you're essentially setting people up for is a Heaven's Gate style suicide where they "ascend" to another plane.

now I'll be the first to acknowledge that technology can take us a very very long way from where we are to things we can't even imagine. I'm not even saying immortality of some kind is totally off the table, necessarily (although within our lifetimes it almost certainly is). I just think this particular idea is total fantasy and easily exploited.

"Yes, you can live forever in the cloud, but before you do it, be sure to transfer me all of your Bitcoin so you can use it in heav--I mean, Epic Bacon Blowjob World."

Edit: I want to clarify my issue is not the idea that we couldn't replicate human consciousness, but that creating a copy is not immortality because the human brain would still die and the consciousness would not transfer to the new version of the mind. A couple people have made the ship of Theseus argument for slowly replacing the brain with artificial parts and that seems to make sense. Although I still question if that is ethical/desirable, that wasn't the original CMV.

[Assistant]
But the 'user' doesn't get to make that jump to another existence. That tech would create a new copy of the person, but the human mind would still be there trapped in the brain; nothing changed. They aren't experiencing anything new, and are still very much mortal.

This resembles when you have a child: you've made a split off copy of yourself that is completely seperate. Parents don't feel compelled to kill themselves now that a younger, longer lasting entity is created that will be able to age past them.


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

[User]
The ability to speak English clearly should be an important factor in considering the employment of teachers and professors (in the United States). CMV.

Note: Although I do hold this opinion, it feels prejudiced to me so I am genuinely interested in having my V C'd.

I think this opinion is particularly applicable to undergraduate institutions, so I will focus on them. If a university offers an education to undergraduate, it should be concerned with its ability to provide a strong education. Most critical to this aim, is the hiring of professors that are good at teaching.

Being good at teaching can be roughly defined as the ability to help students understand a subject. Many schools go to great lengths to judge the teaching ability of their professors, conducting surveys, eliciting student recommendations, etc. However, I have never seen a question like "were you able to understand the professor's speech during lectures?"

I have some professors that speak in such a thick accent that I have to strain to make out their words. This has a huge impact on my ability to learn (and therefore the professors ability to teach). Therefore, if a university does claim to value teaching ability in its employees, it should consider the speaking ability of its employees.

[Assistant]
Just because you have never seen a teaching survey that questions comprehension doesn't mean it's not being considered. The administration is well aware of what each professor sounds like - they did interviews, and they sit in meetings and such. They are not ignorant of the handicap of an accent, and have taken that into consideration at the time of hiring the professor.

Also, there is not a limitless supply of experts worthy of being professors. Get rid of all the professors with accents, and who will you replace them with?


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

[User] ELI5: How come I can sing really well in the shower or in my car, but when I sing anywhere else I sound like a dying cat?

[Assistant] Simply, the sound waves from your singing will bounce off of all the hard surfaces in the shower. This causes an effect known as a "reverb". This reverb levels out your pitch and fills out dead spots or uneven tones in your singing.


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

[User]
[LoTR] So I need a fairly permanent light source in my deep and twisted cavern - torches simply won't do...

So I got this idea where the taskmasters under me can impale goblins and orcs to the walls and then hang parts of elven swords (*goodness don't put the whole thing there or one of the lucky buggers will have a weapon*) on the wall opposite it.  Where'd I get the swords from?  Don't worry about that part right now.  The result (hopefully) being that the presence of live but immobile orcs/goblins will make the swordparts glow bluish forever and my ~~dungeon~~ er, underground palace will have a sustainable source of energy powering its lights.

Does this go wrong anywhere?  Do the batteries wear out?  Do I have to deal with plot deciding not to light up the metal occasionally?

[Assistant]
That glow isn't anywhere near as bright as a torch and the enchanted elven weapons will be expensive and/or time-consuming to acquire and you're putting lives at risk to capture orcs and you also need to buy or raise or scavenge a constant supply of orc food.

This is easily the worst lighting solution I've ever heard of. How could it possibly be preferable to torches?


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

[User] if we ever run out of copper, for ecample for cables, what's our best bet in terms of price and availability?

[Assistant]
Aluminum's always an option; plentiful, lightweight, excellent conductor, easily reused.

That said, there are drawbacks.  Being softer than copper, handling aluminum wires means they're susceptible to breakage.  Aluminum also expands more when heated than copper does, and over time this can work wires out of connectors, causing arcs that can start fires.  Another issue is that while copper and aluminum both oxidize, copper oxide is conductive, whereas aluminum oxide isn't so much. This can change the properties of the transmission line.


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

[User]
[Halo] How did Sargent Johnson survive both the destruction of the Halo and the detonation of the Pillar of Autumn?

And how did, of all things, 343 Guilty Spark kill him if those events didn't?

[Assistant]
Johnson was immune to the Flood from his Orion Project modifications that were the basis for all the future Spartan programs. Once he survived the Flood he evacuated onto a Pelican with a few more Marines and a pilot. They all hid on the nearby moon. So Johnson was nowhere near Halo when it was destroyed.

As for Spark killing him, that was a Forerunner directed energy weapon that. You don't usually survive shots from those without a little help.


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

[User]
ELI5:Why do people with down syndrome all look very similar

Randomly thought about it today how the majority of people with down syndrome look very similar, especially their facial construction. Was just wondering a scientific explanation for this, thanks!

[Assistant]
Down Syndrome is what happens when the baby ends up with three copies of Chromosome 21 instead of two. Having three copies (trisomy) of Chromosome 21 leads to a lot of changes in the body, including the unique facial shape and the developmental delay.

So why is it so common to end up with three of Chromosome 21? Why not three of Chromosome 7 or Chromosome 8?

When a sperm and egg come together and it grows into a baby, there are a million things that can go wrong. It's really common to have an extra chromosome, or a missing chromosome, or a large piece of one that's missing or upside-down.

Most of the time, these mutations lead to death (miscarriage) of the fetus.

Only a tiny number of mutations to your genetic code actually allow the fetus to survive. So those are the ones who are born, and what we observe is that babies who have something wrong with them typically have one of a set of common genetic abnormalities.

It's not that those are the only possible abnormalities - it's that all of the other abnormalities are too severe and the fetus dies - sometimes so quickly that the mother doesn't even realize she's pregnant!

One of the most common mutations that isn't fatal is Trisomy 21, or Down Syndrome. Everyone who has that has exactly the same severe mutation to their genetic code.


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

[User]
What is the Yukawa potential calculating?

The Yukawa potential seems to predict the strong interaction, the weak interaction AND the electromagnetic force. But that seems "overpowered"...

[Assistant]
The Yukawa potential is the interaction potential corresponding to a very simple coupling between particles (Yukawa coupling).

It shows up in a lot of places because it turns out that a lot of particles are coupled in that way.

Potentials of the Coulomb form (charge/r) are really a special case of the Yukawa potential where the mass of the force carrier particle is zero. So that gives you the Coulomb force and part of the strong force between quarks (theres another term representing confinement).

Then if the mass is not zero, as in the case of the weak interaction (W/Z bosons) and effective nucleon-nucleon interactions (various mesons), then you get the usual Yukawa potential of the form exp[-r]/r.


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

[User]
[1984]When Winston and Julia first meet in the woods Winston worries that there might be a microphone hidden in one of the trees. was that a realistic probability or was he just been paranoid?

every time I read 1984 I wonder how much the state is relying on people assuming the surveillance is taking place because actually watching everyone would obviously be a logistical impossibility?

[Assistant]
This is the theory of the panopticon- you can't watch everyone, but you can watch anyone. The state might not be watching all the time, but at any time they *could* be watching, and you can't tell.

So, eventually, people assume they always are.


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

[User]
[Marvel] When Scarlet Witch wished for "no more mutants", how far into genetic mutation did it go?

There are lots of things we see every day that are caused by mutation besides just the guys flying over our rooftops or the ladies levitating stuff with their minds. We all know they are caused by a mutated gene, but what about stuff like Down Syndrome, color blindness, or sickle cell? We were all so concerned with the fact that our protectors couldn't shoot eye lasers or scream a building to bits that we didn't even look into everyone else with a genetic mutation! I don't personally know anyone with any genetic issues so I though I would ask and see if any of you caretakers out there saw any dramatic changes.

[Assistant]
She knew what she meant, and so did the reality warping magic she used.

It meant "remove all traces of the Celestial induced X-gene manifestation in all potential homo superiors on the planet Earth."

All those other mutations aren't caused by the X-gene and so would've been unaffected by the wish.


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

[User]
[Star Wars] How exactly did Darth Nihilus' hunger and powers work? How was Visas Marr the sole survivor of Katarr?

They were quite vague in SW: KotOR II about how he satisfied his hunger.

[Assistant]
Darth Nihilus was a walking wound in the Force. Think along the lines of a laceration on a human body, except it's in the very fabric of the Force itself.

He was present on Malachor V when it was obliterated, and much like the Jedi Exile, his connection to the Force was violently severed due to the trauma of millions of lives being snuffed out at once.

A wound in the force is like a black hole of suffering and darkness, Nihilus was consumed by his hunger, trying to fill that "gap" in himself left by his severed connection with death and destruction.

He needed to feed on the force to remain strong and drew in individuals who had a strong connection to do so.

He chose Visas Marr because she survived. The reason is irrelevant, if not her, somebody else. She felt when Katarr died what Nihilus himself did at the moment Malachor V was destroyed. She identified with him, and he took her as a kindred and a student.

TL;DR: Nihilus fed on the force itself and absorbed it from people around him like a walking black hole.


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

[User] Why are we seeing so many more live giant squid in the last decade or so, when the first live one was only photographed in 2005?

[Assistant]
Could it be that the fact that more people have an immediately-accessible camera (aka "smartphone") have a lot to do with it?

Consider:  I'd say that 100x more people have an immediately-accessible phone than did in, say, 2000.   If we assume that the appearance of UFO's has remained constant, then there should be 100x more pictures of UFO incidents in 2020, than in 2000.


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

[User] [He-Man] Cringer appears to be scared of everything, and yet He-Man keep forcibly transforming him into Battle Cat and battling the forces of evil. Is He-Man just callously contributing to Cringer's obvious PTSD?

[Assistant]
Yes. Battle cat is the dissociative identity of Cringer which lacks all basic emotion and sanity and is left only with the aggressively and externally displaced trauma. BC sees his ptsd in and from everyone around him and sees violence as the only solution. This eventually makes it impossible for any of his identities to coexist without violence. When reverting to Cringer he can clearly see and feel that violence is the worst solution to anything. But due to BC violence is the only way he is capable of interacting with others. This leaves Cringer in a state of near catatonic apathy and permanent neurosis on the verge of breakdown.
And Adam/HM encourages this destructive transformation nearly daily and even mocks C/BC for his trauma.
Eternia is a dark place not only in chromatic theme.


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

[User] What keeps the axion terminal and dendrite of a synapse aligned? diagrams and explanations always show them as free floating, so what stops them from drifting apart?

[Assistant] There are proteins in each that bind to each other, neuroligins and neurexins. Like holding lots of tiny hands. The dendritic part will have neuroligins, the axon neurexins and both cross through the cell membrane into the synaptic spalt and hold hands here.


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

[User]
When you have two mirrors facing each other producing an "infinite mirror" effect, does it take time to "draw" each additional mirror?

You know when you have two mirrors facing each other and there are thousands of smaller and smaller reflections inside each reflection. Since light travels at a finite speed, shouldn't it take time for each of these smaller reflections to be produced? If you could slow down time, or had mirrors far enough apart, shouldn't you be able to see each additional reflection pop into existence? Help me science.

[Assistant]
You are correct, but are a few practical matters that intrude on this.

First, mirrors are not 100% reflective.  After 500 reflections, less than 1% of the light is left.  That might sound like a lot, but if your mirrors are a meter apart, that takes a little more than a millionth of a second.

Then you got alignment.  If the mirrors are 1^o off, the first reflection will be 1^o off, the second 2^o, the third 4^o, and so on.  For that 500^th reflection to be on target, you would need alignment on the subsubatomic scale and beyond.

Finally, you have the Dawes limit.  Because light is a wave, diffraction introduces a level of blurriness, even with perfect optics.  With a 1m mirror, the Dawes limit would be reached at about 500m, or 500 reflection if the mirrors were 1m apart.


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

[User]
[DC] Did Batman ever find closure with the murder of his parents?

Also is Batman considered insane?

[Assistant]
Batman is a fucking lunatic. He runs around at night dressed like a bat punching people in the face.

Insanity has been defined as repeating the same action and expecting different results. How many times do you have to lock Joker in the same asylum he has escaped from hundreds of times? How many times does Joker have to go on a murderous rampage before Batman tries something different?

Edit: To answer your initial question, no he hasn't gotten over it AT ALL. It's definitely his biggest weakness. It has definitely been used against him often.


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

[User] [Marvel] If J Jonah Jameson found out Peter Parker was Spider-Man, can he sue him for anything?

[Assistant]
Yes, and he did. In Civil War when Peter revealed his identity, Jonah (upon recovering from the heart attack the revelation gave him), sued Peter for misrepresentation, fraud, breaching his contract and a host of related charges.

His case was that by Peter claiming that he was working to get pictures of Spider-Man, when he was Spider-Man all along, he was engaging in misrepresentation and fraud. If Jameson known the truth that Peter Parker was Spider-Man, he would not have bought those photos, and could make a legal case that the contracts signed for payment of money in exchange for those photos are invalid. While the case got dropped before the trial and then Peters identity was a secret again, theres a very solid chance that he'd be found guilty had it actually gone to a court room. Its basically a more elaborate version of what Eddie Brock did in SM3, and we all know how that went.


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

[User]
How does Newton's Law of Gravity help us predict the orbits of the planets with "great accuracy"? (Please read description.)

I'm reading *A Brief History of Time* by Stephen Hawking. On pg. 17, there is a paragraph that reads:

"Newton's law of gravity also tells us that the farther apart the bodies, the smaller the force. Newton's law of gravity says that the gravitational attraction of a star is exactly one quarter that of a similar star at half the distance. This law predicts the orbits of the earth, the moon, and the planets with great accuracy. **If the law were that the gravitational attraction of a star went down faster with distance, the orbits of the planets would not be elliptical, they would spiral in to the sun. If it went down slower, the gravitational forces from the distant stars would dominate over that from the earth.**"

What does the part in bold mean exactly? (As is clear, I'm a layperson, so please keep it simple.) Thank you!

[Assistant]
Newton's law of gravity tells us that the force of gravity drops with the square of distance. So if you are twice as far away from the Sun, you feel one quarter as much gravity. We call this an "inverse square law", because the mathematical equation 1/r^2 is called an "inverse square".

It turns out that an inverse square law has a lot of very convenient mathematical properties.

Firstly, if the gravity somewhere is dominated by a single object, then you get very simple orbits. This is called a "Keplerian" system. Our Solar System works like this, because the Sun dominates the gravity by far - it has over 99% of the mass of the Solar System.

In a Keplerian system, orbits always perfectly repeat themselves. If you have an elliptical orbit, you're sometimes closer to the Sun, and sometimes further from the Sun. In a Keplerian system, these points always happen at the same stage in your orbit. So you are always closest to the Sun at one time of year, and you are always far from the Sun at one another time of year. This consistency makes it really easy to predict orbits over a long period of time.

This is a lot more complicated if you have a lot of different objects producing the gravity. For example, in a galaxy you have lots of gas and stars and dark matter producing gravity together. Even though each of these has an "inverse square law" for gravity, all of these sources of gravity add up to give us a different law for the galaxy's gravity. This makes it a lot harder to predict the position of stars around a galaxy over time. The maths doesn't work out so simply. Stars can orbit in a "spirograph" kind of pattern where they are closest to the centre several times in an orbit. They bob up and down too. They don't follow a simple ellipse around the Milky Way.

Secondly, there is a maximum amount of acceleration that you can get from an inverse square law. This is difficult to grasp without calculus. The basic idea is that if you were falling onto a star from your location, the speed you'll reach when you hit its surface is given by adding up all the acceleration you feel as you fall onto it. If you flip this, this also gives you the speed you would need to escape from the star's surface back to that point.

With an inverse square law, the speed you need to escape to a certain distance from a star constantly increases. *But* it reaches a maximum. This is the escape velocity. Above the escape velocity, the force of a star will never add up to enough to pull you back in again.

However, if the force of gravity drops down just a little bit slower than an inverse square law, then this speed never reaches a maximum. That means there is no escape velocity, and you can never completely escape from a star. No matter how fast you are going, a distant star will *eventually* pull you back.

This means that we can't just think of the Solar System as an isolated system. We would need to consider the effects of every other star in the galaxy, because we haven't escaped them. This would make orbits extremely difficult to calculate, and probably wouldn't let you have the nice simple hierarchy of orbits that we have at all.


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

[User] ELI5: Why do computers inevitably become slow and glitchy overtime?

[Assistant]
The slowness is less about the computer itself and more about the software... mostly. Unless you let your computer get jammed up with dust or the fan is damaged, computers don't really get "slower". For example, well maintained gaming consoles (which are computers that just are specialized for video games), from the Gamecube to the Atari 2600, will play their original games as today as well as they did the first day they came out of the factory.

If you don't properly maintain your computer, things can get damaged, either limiting performance as the computer automatically uses less power to keep itself cool, or problems with parts of the hardware can cause all kinds of weird glitches.

However, the reason most computers start to feel slow is because of the *software*. When Microsoft updates word, when Youtube adds features, when entirely new software hits the market, they are expecting their average user to have more and more powerful machines. They stop optimizing performance for older CPU's/GPU's, start expecting their customers to have greater and greater amount of RAM and faster Harddrives.

Your computer isn't running slower, it's just being asked to run more and more calculations than it used to.


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

[User] ELI5: Why we sleep at night instead of during the daytime?

[Assistant]
While many mammals turned nocturnal during the age of dinosaurs, modern primates have turned diurnal for probably a lot of reasons.
-  Most importantly we don't have very dominant diurnal predators anymore.
-  Early primates learned to live out the night in the trees which offered some protection from nocturnal predators.  (incidentally, this is the theory of why we sometimes spasm or jerk ourselves out of sleep, it's a holdover instinct from our tree dwelling days to keep us from falling out of trees while unprepared for sleep)
- We don't have to compete with nocturnal predators.
- Our food is easier to see during the daytime (as are our enemies and potential mates)
-  Primate eyes are specialized to work better in daylight as opposed to some mammals who have made compromises, i.e. the cat's tapetum lucidum which allows their eyes to collect far more light than our eyes (their eyes sort of reflect light back through the retina twice, which is why their eyes appear to glow at night) but hinders image resolution a bit.  Mammals lost most of their color vision during the age of dinosaurs but we gained a lot back pretty quickly.  Still tho we are far behind the visual acuity of birds, who made it through the KT extinction with a massive head start on daytime vision, although to be fair we don't need the same acuity they need.  Primates are one of the few mammal groups that can see red because it helps us identify ripe and nutritious food.  At night anyone's color vision is shit
- We have relatively efficient thermoregulation methods and can weather heat relatively well.

So for these and probably many other reasons (other will probably list more) may as well sleep when it's dark.


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

[User] ELI5: The meaning of "Time is relative"

[Assistant] Speed is the ratio of space to time. If space and time are absolute, then the speed of light must be relative, depending upon the speed of the observer. The speed of light is absolute and does not depend upon the speed of the observer, therefore, either space or time must be relative.


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

[User]
Has anyone written about the idea that war is not a temporary condition, but the default state of affairs, from which peace elevates itself?

A lot of journalism and popular history seems to ask "what caused this war?", "what caused that war?". This seems to be based upon the underlying assumption that peace is the normal natural state of affairs, which is interrupted by war.

Has there been any theoretical analysis of this assumption and it's implications? Has anyone academically proposed that conflict is the natural state of affairs, the default condition in nature, and that human history is dotted with various temporary (and some thankfully long-lasting) outbreaks of peace?

Edit: for clarification, I don't equate "natural" with "good". By asking if war is somehow natural, I'm looking for explanation, not proposing justification.

[Assistant]
Thomas Hobbes famously draws the conclusion that the natural condition of man is a state of war. This state of war can be escaped *nationally* through the creation of government but according to Hobbes and many realists can not be solved *internationally*. As long as anarchy remains in the international system, war will be a regular feature.

You should read realist works in IR theory. For a classical realist account, see Morgenthau's *Politics Among Nations*, which holds that conflict is rooted in human nature. For two neorealist accounts, see Waltz's *Theory of International Politics (1979)* and Mearsheimer's *Tragedy of Great Power Politics (2001)* which offer contrasting accounts of how anarchy shapes state behavior and causes states to act in ways that lead to regular war.


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

[User]
ELI5:What's the core differences between the CIA, the NSA, the ATF, The FBI, the Secret Service and Homeland Security?

Why can't they be combined into one agency?  All seem to do pretty much the same thing.  I'm confused as to what each of them can and can't do and the jurisdiction of each agency.

*update*  Thank you everyone for kind, thoughtful answers.  I had a general idea of what each agency was supposed to do and assume they all work together as needed, just not the fine points/jurisdictions.

[Assistant]
They all have very different charters and are tasked with very different activities

FBI:  detect and prosecute crimes against the United States

CIA:  Counterterrorism, nonproliferation of WMD, counterintelegence, cyber intelegence and forgien intellegence gathering

NSA:  global monitoring, collection, decoding, translation and analysis of information and data for foreign intelligence

SS:  Prevention and investigation of counterfeiting of U.S. currency and the safety of current and former national leaders and their families

Don't believe what you see in the movies - they each have a very specific charter and duties.  They are also all very large organizations with complex managment structures to control the power that the agencies wield.


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

[User]
ELI5: Why do flying insects spend such a large % of their life flying around? Doesn't it expend a lot of energy?

With birds, they seem to only fly if it's really necessary. Why are insects different?

[Assistant]
Bugs actually don't have to expend hardly any energy at all to keep themselves flying.

They are so incredibly light that it takes very little energy to keep them in the air. It also takes very little energy to fuel them because food is plentiful if you're an insect and you can just fly around, access it, and you're so tiny it doesn't take very much.

Plus because most insects are willing and can eat foods other, larger creatures can't, just makes them even more adapted to survive.

Insects are pretty much the most successful group of animal life there is because of their small size.

One rotting meatball has enough calories to keep a fly alive for decades.

Whereas a bird is much, much larger, and can't be sustained as easily, thus energy conservation is something to consider.

With an insect they don't really have to worry about energy conservation because they live in a world of resources.


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

[User]
ELI5 Why are the penises of Ancient Greek and Roman statues so abnormally small?

I had a conversation with a mate a few days ago which eventually led to this question and it has been haunting me since. Did every notable male in history have a microdick?

[Assistant] In greek society it was unsightly to have a large penis, a product of their social norms. Obviously not all men had small penises so most greek statues are carved with a very flaccid penis to simulate the ideal of the time.


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

[User]
ELI5: How do submarines withstand so much water pressure?

Man has reached 7-mile ocean depth. How does a machine withstand that much pressure?

[Assistant] High yield strength low alloy steels, or in some cases titanium alloys, formed into spheres to best resist collapse due to external pressure. Windows are polymethyl methacrylate (acrylic), annealed to relieve stress and formed into shapes which, in conjunction with their seats, best resist that pressure. Unmanned spaces (batteries, electrical housings, motors, lights, machinery, etc.) are either built heavy to withstand the pressure, or oil filled and pressure compensated to eliminate the differential pressure. Buoyancy foams are hollow glass microspheres embedded in an epoxy matrix, so very resistant to pressure collapse, with density dependent on design depth of the vehicle.


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

[User] Why are so many people against background checks for purchasing weapons?

[Assistant]
We already have background checks when you buy from a dealer. The issue is background checks for private sales. It would make buying or selling a firearm difficult for private citizens. If you had a friend who wanted to buy a gun from you, then you would have to go to a dealer to facilitate the transaction since regular people don't have access to the National Crime Information System. It wouldn't be fair for the dealer to be forced to use his manpower, Internet connection, and subscription to NCIS for free, so they would be able to charge a fee.

The only people this would effect are the law abiding citizens, because the criminals won't comply with the law.


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

[User]
CMV: The NFL Hall of Fame Should Be the Hall of Very Good Stats

The NFL Hall of Fame should induct members based on stats and achievements, and players that shouldnt have been inducted in the past shouldnt validate inducting players with the same statistics. Ive been thinking about this debate since Eli Manning got benched for Daniel Jones, and people started saying Eli Manning should be inducted since he beat the Patriots twice in the Super Bowl. I saw Benjamin Allbright, a popular NFL journalist, claim that the Hall of Fame isnt just the Hall of Very Good Stats, subsequently citing Joe Namath. However, isnt that basically what the Hall has become? The NFLs last class of Hall of Famers included 6 players, each of which had significant career statistics. The class combined for 49 Pro Bowl appearances and 36 All-Pro recognitions, and Johnny Robinson added significant contributions from his AFL days. Given that Eli Manning never achieved All-Pro status and had mediocre career numbers at best (60% completion rate, .500 win percentage), I believe it reaffirms that the Hall of Fame should only induct players with great career stats.

[Assistant]
The Hall of Fame represents the history of football, and the history can partially be told through numbers, but we humans prefer stories. And images. That's where the "fame" comes in. It means notoriety.

Joe Namath is one of the most important figures in the story of the NFL because we attribute the merger of the AFL and NFL to his "guarantee" and subsequent success in Super Bowl III. You can't tell the story of the league without that moment. You can't make a historical highlight reel without the footage of him waving his finger in the air as he left the field. Those are the lasting marks that were left. That's where the "fame" comes from.

"Fame" can come from years of consistency (Jackie Slater) or brief, but integral contributions to the story (Gale Sayers).

Fifty(one) years later, those singular moments don't mean as much to us because we've added so many new details to the story. They start to blend in, unless they're unmistakably crucial to the narrative. The Giants two Super Bowl wins over the Patriots were extremely valuable pieces of the narrative. They showed that David can still beat Goliath (especially when they prevented the perfect season). And the proper response to that as a Hall of Fame could be to induct Michael Strahan and leave it at that, but we're humans. We need MOAR TO THE STORY. And we like quarterback stories best of all. So Eli will probably make it in.

Most people lean that way. They aren't excited about Frank Gore passing 15,000 yards because it hasn't been the most exciting story. But when it comes to voting, and telling the story of the league, that's where we'll always gravitate. Just like in life, if it doesn't make a good story, people aren't going to pay attention.


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

[User] ELI5: How come when you have a fever and your temperature is so high you feel cold?

[Assistant]
Because the way a fever works is by tricking your brain into thinking that your normal temperature is *supposed* to be higher.  So, instead of 98.6 degrees, your brain might now register 104 degrees as its desired normal temperature.  So suddenly your core body temperature is 5 degrees lower than it "should" be, so you feel the same as if you didn't have a fever, and your core temperature had dropped to 93 degrees.

Further, even once you get your core body temperature up to the brain's desired fever range, the air around you is a lot colder compared to your temperature than normal.  For instance, if you're running a fever of 104, and you're in a room that's 72 degrees, it feels the same as not having a fever and being in a room that's 67 degrees.


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

[User]
[Witcher] Why bother carrying steel weaponry?

Ok, witchers carry a silver sword for monsters and a steel one for humans. Why not just carry the silver one and spare the excess weight?

I get that silver is expensive and not as strong as steel so you probably don't want to be bashing it against armour or other weapons and whatever, but when your powers include mind control, telekinesis, pyrokinesis, a magic shield and traps, super speed, super strength and super reflexes, surely your fights against humans are going to be so one sided that there isn't going to be much dueling involved anyway?

[Assistant]
The silver sword he carries, along with being more fragile, doesnt hold an edge as well as the steel one.  Think of the steel sword as his every day, chopping whatever need to be chopped sword.  Humans, animals, vines, whatever - steel sword.

Its only when things have taken a dramatic turn for the horrendous that hell risk using the expensive, rare, enchanted and softer metal sword.

Lastly, the additional weight is inconsequential due to his heightened Witcherie abilities.


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

[User] [Star Wars]If the rule of 2 ensured only the strongest Sith would rule, why is Darth Maul defeated by a padawan?

[Assistant]
Several Reasons, actually;

Obi-wan was very advanced for a Padawan. There were almost certainly some politics around him not having faced the trials yet, seemingly centered around Qui-Gon butting heads with the council.

Obi-wan was completely outclassed by Maul; Obi-wan won because he pulled off a maneuver far above his skill level, and he got away with it because Maul was arrogant and assumed he had already won.

Darth Sidious believed he was the culmination of the rule of two, so he didn't bother to teach any of his apprentices everything he knew. In reality, none of them were "true" Sith apprentices, merely pawns in Sidious' new paradigm, "The Rule of One."


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

[User]
Why is nuclear fuel used to generate steam for electricity is it not possible to directly use nuclear energy?

Damnit I missed a semicolon. Don't suppose a mod can fix it for me? Revised title:

Why is nuclear fuel used to generate steam for electricity; is it not possible to directly use nuclear energy?

[Assistant] You can use the thermoelectric effect to directly convert heat to electricity, without the steam turbine, but it would be less efficient. Satellites/Space Probes use this method because they can't afford the mass of the turbine.


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

[User]
[MCU] Captain America's shield absorbed a full strength hammer smash from Thor leveling the woods around him in the first movie leaving cap unscathed, yet Ultron got knocked away by a casual hammer swing by Vision in the second movie.

The shield and Ultron are both made of vibranium, why did this happen?

[Assistant] Vibranium can be applied in different ways for different purposes. The difference between the solid vibranium (alloy?) frisbee and a complex machine made up of individual vibranium components was a matter of purpose. The shield was designed to be a solid plate of metal that can withstand a hit. Ultron designed his final form for mobility and sarcasm.


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

[User]
ELI5: What does a blind person see?

Is it black? White? Does it make a difference if they are born blind vs. go blind later in life?

Someone told me people blind from birth literally see nothing (not black, literally nothing), but I'm having a hard time wrapping my head around that.

[Assistant] Close just one eye, and note that instead of seeing blackness like you do when you close both eyes, you instead see "nothing" out of the closed eye. That's what a blind person would "see"... nothing at all. Or simply imagine that other people had a sense that you lack, such as an ability to sense magnetism. When they asked you what you "sensed" when you tried to detect magnetism, what would you tell them?


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

[User] [ATLA] Is Air Bending allowed in pro-bending matches?

[Assistant]
As it exists at the start of Legend of Korra, the rules are hard-coded that each team gets an earth bender, a fire bender and a water bender. There is no valid position for an airbender, because the rules were written on the assumption that one wouldn't be available for all teams, and letting the few teams that could find one have one would be tantamount to cheating.

This is reflected in how Korra is forced to play; she's playing in the water bender position, so she's only allowed to use water bending. Even when she does get her airbending down, using it would be a giant foul, as would swapping to fire or earth.

It's possible that after the convergence, there could be a four-man variant introduced.


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

[User]
ELI5: How do homeless people generally end up in the inner city?

I never understood how they get there and not like in suburbs or anything.

[Assistant] Everything in the city is much closer together (they are on foot all the time), and there are more public spots to hang out at. In a city you can beg from a lot of people and hang out under a bridge or something, but in the suburbs you would be in someone's yard most likely.


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

[User] ELI5: How is it that all these houses in the UK can hold back a river. Are all the doors completely watertight, and they have brick walls that let no water in at all? What is this sorcery?

[Assistant]
Some houses, in some areas, where flooding has previously been a problem have adapted their houses to be much more watertight.

This involves sealing flaps over air vents and dams for doorways, and ensuring the toilet doesn't back up. Houses that have been extensively renovated after previous flooding will almost certainly have had all the wiring moved up above the expected flood level.

Brick walls are surprisingly watertight if they're in good condition. If they're not then you can waterproof them with sealant.

Of course - the best solution is to not live in a wet bit, but sometimes floods come along with cover areas previously never submerged.


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

[User] Do UV sanitizing wands really work and if so, how?

[Assistant]
UV radiation damages the DNA of cells. The idea is to hurt them to a point that prevents them from being able to replicate efficiently, not to simply kill them off the first go.

UV radiation however is only good for surfaces and only OK for water sources (need more intensity/time to do the same effect). For damaging cells within the bulk of an item, high energy X-rays, gamma rays, and electron beams can be used (and are used very often for sterilizing foods and medical equipment). The best part of it all is that you can package an item, and then without even opening it up, sterilize the contents!