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

[User] ELI5: Why is it impossible to travel faster than the speed of light?

[Assistant]
Finding an answer in a past thread can be a major PITA with all the helpful, humorous comments that get thrown. So try this:

It is impossible to travel faster than the speed of light because the speed of light simply is *the* speed of everything. You, me, everything in the universe (except space itself which can expand at unlimited speed) already travels at the speed of light because that is the only speed there is.

You may have heard that nothing with mass can travel at the speed of light. Well, yes and no. Everything with mass is in fact traveling at the speed of light. The question is through what it is traveling. Nothing with mass can travel at the speed of light through space. That leaves time, since we exist in four dimensional spacetime.

Your speed through space plus your speed through time always equals c (the speed of light in a vacuum). If you have mass, most of that speed is through time. For things without mass, like light, 100% of that speed is through space (light doesn't experience any time at all in this sense).

Note that this is why time and space are variable and depend on the relative speeds of the observers. The faster you propel yourself through space, the slower you move through time. The total always equals c.

Think of it this way. Say you have a car that goes 90 MPH. That is the only speed it goes, all you can do is steer it. If you steer north, then you'll be going north at 90 MPH. If you steer east you'll be going east at 90 MPH. If you steer northeast... you'll still be going 90 MPH, but neither your speed north nor your speed east will equal 90 MPH - your speed is divided over two dimensions.

It's kind of the same with spacetime. You can travel in time, space or some combination of the two, but your combined speed is always equal to c. Travel faster in space, and you'll be moving slower through time. Slow down in space and you'll then be moving faster in time.

Nothing with mass can ever travel at the speed of light through space alone - it would take an infinite amount of energy to do that. Likewise nothing without mass can ever be completely at rest in space - there is no such thing as a stationary light wave.

You can't go faster than c, and you can't go slower than c. c is the only speed there is.


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

[User] [Star Wars] It's said that Anakin could have been twice as strong as the emperor but after Mustafar he could only be as strong as 4/5ths of the emperor. Why is that?

[Assistant]
Wholeness of body and of mind.

A body can be cloned, cybernetic parts can be made, and the extremities can be regenerated with enough bacta.

But it takes far more effort to repair the mind, and when the body is lacking the process is all the more complicated.

Anakin Skywalker died in the moment Darth Vader was born - there, on Mustafar, while his wounds were cauterized by the scalding rock and his skin began to ripple and boil, Anakin Skywalker died. He had, to his knowledge, killed his wife and unborn children. He'd collapsed the government he'd previously dedicated his life too. The only man in the galaxy left who might call him friend had just cut off all of his favorite limbs. He closes his eyes, and upon opening them again

He is in a casket. A moving, breathing, blast-proof casket. For all his  efforts and pain, Anakin Skywalker had died and the resultant being was locked inside a durasteel shell, kept alive by machines, and kept in pain by man who'd led him down that path.

His body could never heal, and his mind could never find peace.


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

[User] ELI5:Why does the air seem "fresher" in the morning?

[Assistant]
Are you referring to outside air or your perception upon waking in general?  Speaking to outside air, generally speaking (noting that each climate is different) humidity raises in the morning as the air is being warmed by the sun.  As humidity increases, our perception of smell increases which would be one contributing factor for a fresher smell.

Also as the ground and air warms, more insects that interact with the plants (bees, flies, etc..) are moving around, stirring up sent particles which also can contribute.  Wind invariably still moves regardless of the time of day however insects move inside of folds and cavities of plants where a more dense consultation of sent particles are contained.

tl;dr Humidity increases in the morning, heightening our sense of smell.  Same reason your farts smell worse in the shower.


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

[User] Can a black hole be absorbed by another even larger black hole?

[Assistant] Black hole mergers are one of the more prominent theories as to how supermassive black holes are formed. The idea is very similar to neutron star mergers where the two objects are orbiting each other and gradually losing energy by radiating gravitational waves. This causes them to spiral in towards each other until they combine into a larger black hole.


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

[User]
ELI5:How unique is each persons set of capillaries, veins, and arteries compared to everyone else?

While I understand the general shape will (hopefully) be the same, how much variance is there in the path of veins and where capillaries branch off and meet back up?

[Assistant]
Not only are your capillaries unique, they're also constantly changing. Angiogenesis is the process whereby the body creates blood vessels.

As for other vessels, major vessels will be generally in the same areas (jugular vein, femoral artery, etc), but the smaller ones may have some variation from person to person regarding their exact location. The general layout and vacinity will be the same, but the exact path will vary slightly.

Just hold your left hand next to someone elses and look at the differences in the veins on the backs of your hands.


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

[User]
Question about antimatter...

Say (hypothetically) that we could create stable anti-matter particles in mass quantities.
Would it be possible to combine different anti-particles (anti-oxygen and anti-hydrogen for example) to create the anti-version of substances we commonly have on earth (like a kind of anti-water)?

Also, if this is in anyway possible, how would the anti-substance behave differently when interacting with normal everyday matter? (Other than obliterating any of its positively charged counterparts it encounters, of course.)

I saw this basic question posted as a comment in another thread and thought it deserved its own post since it's an interesting thought experiment... At least i think it is.

It IS 3:45am and I'm 15 beers deep though so i may just be drunk and missing the obvious point. if so down vote me and disregard...

tldr; Would the anti-version of common substances act any differently than their positive counterparts in a normal earth environment? is it even possible to combine anti-particles into structured arrangements and make anti-elements? Would it be possible in the foreseeable future?

[Assistant]
We could make a whole anti-you, just don't shake hands.

Though interestingly, this brings up the larger point of symmetry in the universe. Can you in fact make a mirror version of something (with everything being reversed) and still have it operate identically? Well ideally yes, but because of certain problems with observation, it seems that the universe does at a certain level favor one dichotomy over another.

One example is the absence what should have been a half antimatter universe, but instead we see a singularly matter dominated one which suggests that in some way antimatter does behave differently then normal matter in a way which is less stable. So the symmetry is only partial.

I suggest you read Richard Feynman's The Character of Physical Law, one chapter really delves into what your asking.


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

[User]
[Star Trek] What stops Romulans from being like pre-logic Vulcans?

Since Romulans broke away from Vulcans before Vulcans forsook their emotions for logic, why aren't they as aggressive as the pre-logic Vulcans were?  Why aren't they as controlled by their emotions as the pre-logic Vulcans were?

[Assistant] Romulans actually are very much like Vulcans before the Time of Awakening. They are emotional and aggressive, though they have channeled their emotions and aggression enough to form a stable and lasting society.


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

[User] How do colliders aim atoms so that they actually hit each other?

[Assistant] It's not quite correct to say that individual particles are set up for collision. Rather, streams of particles, or "beams", which actually consist of large numbers of individual particles, are aimed such that a high probability of collision exists in the detection area.  The beam line is just an evacuated tube, with an extremely high level vacuum maintained to prevent unwanted collisions. The beams themselves are steered with strong electric and magnetic fields, so as to keep the beam centred in the beam line. The obvious consequence of this is that you can't steer uncharged particles, so any experiments using neutral particles must be set up to use them as a stationary target.


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

[User] ELI5: Why we cant just put water on dry skins?

[Assistant]
Aesthetician here...dry skin is not just the lacking of water, but natural oils your body naturally produces. **Sudoriferous** glands (sweat glands) excrete water. Internally, adding more water and clear fluids to your diet will help improve the hydration of your skin. Externally, wash with a softer water  that is medium warm, and use a PH balanced cleanser.  **Sebaceous** glands excrete oils. Internally, add foods with good oils to your diet- olive oils, coconut oil, avocado. Externally, when washing, do not use uber hot water. It strips the skin of the natural oils that moisturize your skin. When out of shower/bath, pat skin dry and immediately apply moisturizer or coconut oil to skin. Not only does it "trap" the water on your skin, it restores the natural oils.
**TL:DR**...dry skin is lacking in both water and natural oils. Sorry the explanation isn't really ELI5.


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

[User]
Can you refer to something that doesnt yet exist?

Im in a music league where we submit songs according to categories. This rounds theme is songs that mention the title of a film. Theres a dispute over whether a song counts if it uses a phrase that later becomes the name of a film, e.g. REMs song Man on the Moon which preceded the film by 7 years. My feeling is this would be an erroneous use of the word mention, but Im not sure I have footing in philosophy of language to argue the point. Would Kripke or someone like that be helpful here?

[Assistant]
Wittgenstein might argue that the question, which is essentially "what does the word 'mention' really mean in this particular case?", is the wrong one to ask. Words don't have objective meaning and can be viewed as puzzle pieces in a language game played by members of a society. Thus, its "meaning" hinges on how others use it, and cannot be intelligibly spoken of apart from that.

In other words, to address your specific question, this Wittgensteinian viewpoint might suggest that, in order to determine whether the word 'mention' necessarily implies intent, it's more important to gather information on real-world use-cases, and on those around you. How did the person who picked the theme intend it to be understood? How would others in your group use the word 'mention'? Perhaps one might even consult a dictionary in an attempt to determine how the average English-speaker would use the word.

At the end of the day, the most important thing is that everyone playing the specific language game (ie everyone in your music league) agrees on the use-cases of the words being used.


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

[User]
CMV: Anti-vaxxers need to be shut up.

Masks and vaccines work. That's something I want to be taken as a given in this post.

Now, we all know that this virus is very dangerous. People are dying by the thousands, and it needs to stop. This pandemic would probably be over by now if it wasn't for anti-vaxxers and anti-maskers. That means people are dying every day because of someone's personal preference. Do you think this is fair? I certainly don't. Lives are much more important than a personal preference, even if it's a widely held one.

Anti-maskers and anti-vaxxers are killing people by transmitting the virus. It may be indirect, but it's still killing people. Seems very selfish to me. While I agree with free speech, I also think that sites and people going against literal *scientific evidence* need to be shut down, especially when it starts killing people. Children are also very impressionable, and if they were told this lie they would likely believe it, creating a new anti-vaxxer.

Imagine some poor little child, dying in hospital with covid-19, because somebody felt the need to not wear a mask. These anti-vaxxers and anti-maskers are killing people, and it needs to stop *right now.*

Change my view.

[Assistant]
1. How will people react when they know they're being censored? Will they just give up? Will that really change their minds or behavior? Or will it make them feel even more like someone is trying to control them, which further justifies (in their mind) resistance against their government? Will we have another January 6?

2. Who decides what information contradicts the science, and how do they decide that? How do you make sure they're genuinely seeking the truth, and not trying to use their positions as censors in order to pursue some other goal?

3. How do you tell the difference between *contradiction* of science vs. *nuance*? Lots of people are hesitant about vaccines because they're aware of the nuances and they're concerned about what we *don't* know. Should nuanced discussion and discussion about the limitations of our knowledge be shut down, too?

4. What if the science needs to be revised? How will anyone know? Competing hypotheses need advocates order to be taken seriously and studied and tested. Therefore, in order for science to advance, people need to be free to advocate for ideas that might be incorrect. Who will advocate for hypotheses that are critical of vaccines? Can vaccine-critical ideas be presented and supported just for the sake of argument? If no, then how can anyone have a reasonable discussion where they learn anything? If yes, then how do you tell the difference between a pro-vaxxer proposing a hypothetical and an anti-vaxxer pushing their ideas and using "this is just for the sake of argument" as an excuse?


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

[User]
Eli5 Why wasnt emperor Hirohito persecuted or killed following the end of World War 2?

So emperor Hirohito died and lived to his 80s or 90s, why wasnt he instantly killed or sent to jail after the war ended. Did he get punished at all?

[Assistant]
There's plenty of room for argument as to how much responsibility the Emperor had for the decisions of the Japanese government.
In the end, Hirohito was stripped of his power, and reduced to being a figurehead monarch, like European royals. Keeping him on as that was a pragmatic decision, because it greatly eased the occupation and nation-rebuilding of Japan.

There are people who argue that he should have been pushed to abdicate in favor of his son a few years after the war, but.... By then, with the Cold War on, the Americans had a strong interest in a stable Japan.


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

[User]
Can our eyes feel temperature?

I know this sounds dumb but I noticed today while it was near freezing that my eyes are the only part of my face that wasnt immediately or subsequently cold. Is this just because we blink a lot, or smaller blood vessels, or what?

[Assistant] Yes. The cornea (the transparent part over the iris and pupil) has unmyelinated nerve endings sensitive to touch, temperature and chemicals. Triggering those nerves causes an involuntary reflex to close the eyelid. The sclera (the white part) also has these same nerves, and similar signals will also trigger the involuntary closure of the lid.


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

[User]
ELI5:If it was not meant to discriminate against gays, what was the intended purpose of the Indiana law?

Giving the governor the benefit of the doubt, what was the purpose of the new law? Who was being forced to serve people that conflicted with their religion? And could a christian now be able to not serve Jews?

[Assistant]
the bill passed in Indiana essentially makes a federal act passed in 1993 (the religious freedom restoration act) apply at the state level. the federal act was passed because of a Supreme Court ruling in 1990 that set a precedent that many feared essentially gave government the power to regulate how religion was practiced (I believe the case before the Supreme Court was whether the government could prohibit a Native American group from using hallucinogens in their religious rituals).

SCOTUS ruled in favor of the government, and to correct for a precedent many feared could go haywire, congress passed the RFRA, which does two things. first, the bill requires that the federal government demonstrate a compelling interest in the matter at hand. second, if there is a compelling interest, the government must intervene in the least restrictive way possible.

many states passed their own version of this law in 1993, and after the Supreme Court ruled the RFRA applies only at the federal level, several other states did the same. before Indiana, 19 states had laws such as this on their books.

rewind to last year, and the RFRA was actually invoked in the decision of Burwell v. hobby lobby which ruled that "closely held" companies who object to birth control on religious grounds do not have to provide coverage for birth control to their employees because the government had already made exceptions for religious organizations in the same position, therefore the requirement was not the least restrictive means of furthering their compelling interest.

since then, the RFRA has come under fire as a shield for bigots, because the fear is that a restaurant owner could object to serving a gay couple citing religious beliefs. in reality, plaintiffs don't fair too well such as in AZ last year where a wedding photographer who did not want to photograph a lesbian couple lost.

but hey, headlines.


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

[User]
Can you easily break somebody's neck by twisting their head quickly, like in the movies?

In a lot of movies, TV shows and video games (Most notably Splinter Cell), people often break the 'baddie's' neck by grabbing hold of their chin from behind with one hand and holding the back of the head with the other and yanking it in a twisting motion; instantly immobilizing the victim.

Is this possible? If it is, why is it possible and what is actually happening inside the victims body? (I presume the spinal cord is damaged?)

Thanks in advance!

EDIT: Also, would the victim die instantly or simply lose consciousness?

[Assistant] I read this question answered a few months ago on here. Basically the top comment said that a person's neck muscles are super strong, so that unless the killer really surprises the person being killed, the person could tense up and fight them off.


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

[User]
[Star Wars] What does a usual day look for an average Stormtrooper?

So let's take a look at an ordinary stormtrooper, what does daily routine look like?

[Assistant]
Wake up. Run drills. Eat breakfast. Run drills. Stand in formation. Guard something. Eat lunch. Go back to guarding something. Run drills. Dinner. Sleep.

Unless they're in a warzone or on active alert most troopers are walking patrols or running simulations to stay i peak condition.


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

[User]
[General Zombie question] How can typical zombies be attracted to light/sound/smell if their sense organs are decomposed?

For example, in The Walking Dead there are walkers in various states of decomposition. Fresher corpses may still have the ability to use their senses, but some of the 'riper' ones should be deaf, blind, and unable to smell due to their eardrums, eyeballs/optic nerves and olfactory sensors being rotted to mush or liquefied...what keeps these guys able to go after the living like bloodhounds??

[Assistant] Touch doesn't decay until the nerves are gone which would also mean the zombie was fully dead. Touch can allow you to feel heat and vibration which would allow a basic kind of tracking. The nerves of zombies decay much more slowly than the rest of them since that is where the virus resides primarily, this means that by the end the zombie is covered in tiny super sensitive sensory organs.


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

[User]
Do people physically age normally when in a coma?

Would a person who went into a coma at 20 look like a normal 50 year old when they are 50?

[Assistant]
They will age. But people in a coma will not age like people not in a coma. Without regular use, their muscles will atrophy. The part of their brain that was damages initially (to trigger the coma) might deteriorate as a result of inflammation or "maintenance" responses to the area. On the other hand, stress would be low. But the heart still beats, the lungs still breathe, etc.

A 50-year old who awoke from a 30-year coma would look like a 50 year old, but with much reduced muscle tone and severe cognitive deficits.


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

[User] ELI5: Why in dystopic films or tv shows (Walking Dead, The Last Man on Earth) isn't there power or internet available? Unless someone shut's the sources off, wouldn't they still be working until they break down?

[Assistant]
These things aren't self-sustaining.  They require a lot of work to keep working.  Even in a medium company you need an IT department to keep everything from going down constantly.

Power requires fuel, which needs to be managed.  Not everything is automated, so fuel can run out.  Additionally, during an apocalypse people are burning things, running into power poles, fires breaking out, which can also cause the grid to have issues.  There's a lot of load balancing, some automated, some manual.  If no one is around to do the manual part, then it would most likely shut off sectors of the grid to prevent a problem.

Electricity would go for awhile, and cell towers have battery backups that can last awhile too, but none of them are designed to work completely unmonitored and without help.


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

[User] [marvel] can wolverine swim?

[Assistant]
He can, but not very well. His skeleton is heavy, and not very buoyant, so swimming is harder for him, but not impossible. Still, he says that he's an awful swimmer.

Drowning is one of the few things guaranteed to kill him, as his healing factor can't just create oxygen.


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

[User] [DC/Marvel]Considering how popular cosplaying is, how common a problem are people walking around in public pretending to be heroes and villains? What sort of horrific or ridiculous things have happened as a result? Are there laws against that sort of thing?

[Assistant]
There's a Legends of the Dark Knight story that starts with Batman waking up in an alley, completely bruised and battered, and with a serious case of amnesia because of some head trauma.

He tries to make it cross town on foot, while stopping crime and helping people, except totally failing at it cause his injuries are so bad and he can't remember his training for some reason. Also his utility belt is empty.

At the end of the story Batman finds himself facing down some gangbangers and about to be executed by them when the *real* Batman shows up and saves him.

Turns out the Batman we've been following through the whole story is some average joe who was cosplaying as Batman for the wife, accidentally fell out of his apartment window and into the alley below, and couldn't remember who he was afterwards, but just assumed he must be the real Batman.


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

[User] ELI5: Why do we have so many different stock markets? Why not just have one?

[Assistant]
I can answer this.

In simple terms, stock markets today are businesses. They provide the meeting place, they provide the market information and they provide the rules and enforcement.  So for every trade that goes through they charge a tiny portion that covers that infrastructure and then some.  They charge the stock brokers you buy your shares through, they charge the traders etc.

Now, each of these meeting places, the information services and the rules are all slightly different for each market.  It starts to get a bit more technical, but NYSE operates differently to NASDAQ in matching buyers and sellers.  The NYSE is what we call an auction market, while NASDAQ is a dealer's market.  When you buy stocks on NYSE you are trading directly with another seller, but when you buy or sell through NASDAQ you are actually buying from NASDAQ who acts as a middleman, who keeps a stockpile of company shares ready to be bought and sold.

There are different characteristics why some traders prefer one over the other, but consider this: When you buy a birthday gift, sometimes you can plan ahead and shop around to get the best price, but sometimes you need it immediately.  Same things with shares. Some traders just need the stock immediately, whereas some think they know what is a fair price and will wait until someone can deliver it at that price.  This is what we refer to as 'best execution'.

The next question is where do you want to raise money? Companies list their shares to raise funds, and if you are a German company it probably makes more sense to list in Frankfurt than in New York, as that's where people likely to know and be interested in your company are from.  You want a market where people are going to actively trade your stock because this would ensure it is liquid, and someone can't just squeeze the price of your shares.

Also, what if you're a company and don't want to comply with strict disclosure rules, maybe you can list on a different exchange with more relaxed rules.

**TL;DR** We have different stockmarkets because they provide different services, and companies generally list where they can raise the most money.


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

[User] Why is my scrotum the tannest part of my body, even though it never sees the sun?

[Assistant] Scrotums have very high levels of melanocytes in the dermis layer of the skin.  From an evolutionary standpoint, this occurs so that the testicles were more highly protected from UV radiation, which can cause genetic mutations.


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

[User] ELI5 : When I'm doing CPR on a person and I'm breathing into his mouth, am I not breathing CO2 into his mouth because i exhale CO2?

[Assistant]
The air we breathe in is about 21 % oxygen, and contains virtually no (0.04 %) carbon dioxide.

The air we breathe out is still about 15 % oxygen, and only 5 % carbon dioxide. Theres still plenty of oxygen available, and a second-hand breath is much better than no breath at all.


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

[User]
Are there any long-term effects for people who have been in a prolonged coma as a child?

Since coma messes with your internal clock, does this lead to any abnormal physical and mental development patterns? E.g., do they have longer spines than normal people?

[Assistant]
Doctor here

The reason a child would be in a coma would be a brain injury, either traumatic (car accident, Shaken Baby Syndrome) or atraumatic (anoxic brain injury from drowning or a stroke; for example). If the injuries are severe enough to cause coma lasting longer than a week or so, the child is likely to suffer long term consequences. These include things like developmental delay, muscle strength and coordination abnormalities, difficulty with speech and swallowing, and endocrine abnormalities that can result in things like abnormal puberty and stunted growth.

Comas are indicative of severe injuries, with longer durations indicative of a worse functional outcome.


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

[User]
Why do some people simply not listen to what other people have to say?

I sell industrial equipment that could kill people if installed improperly. It is my job to know the safety requirements, ratings, etc. Many customers disregard me warning them that what they're trying to do could get someone killed.

Im not really sure how to explain the "feeling" that these customers convey in the way they don't listen, so I'm including an example.

A piece of equipment we sell has a little package of bolts inside of a tube, seated in one leg of the equipment. It's standard for me to tell the customer something along the lines of "the bolts are in a little tube in one leg. Make sure you remove them before installation. You can use a little flathead screwdriver to pry them out." I even have a package removed from the leg that I use to show them what to look for.

I had a customer come in today to purchase one of these pieces of equipment. I go through my whole spiel about the bolts, show him what the package looks like, how to remove it. Not two minutes later, he asks me (his actual words): "So where do I get the bolts to put it together?"

I go through the whole thing again, show him the little package of bolts and explain where they're at and how to get them out. When we're loading the equipment into his truck, he looks down one of legs, sees the bolt package and says:

"What is that?"
I explained: "Oh, those are the bolts I was talking about."
Him: "Well how am I supposed to get them out?"

Now, I understand this is a relatively small thing, certainly not going to be a life and death situation, but I find the more and more I talk with someone who does not listen, especially when I'm trying to make things easier for them, the more I find myself getting frustrated.

I really want to understand what goes on "behind the scenes," so to speak, with someone like this. The way this is conveyed is almost as if it seems like they're thinking to themselves "Why would I try to remember, when I can just have you remember for me?" As if they believe my time is worthless. This seems to happen a LOT with our customers.

Everyone that works here gets irritated by this kind of thing. Are we reading too much into this? Or is this a thing, and how can I deal with it better?

[Assistant]
Customers usually have their own thoughts going when talking to a vendor and it can be hard to let go of what they think is important at the moment to actively listen to what the vendor is saying.

In that kind of moment body language can help you a lot. Want to make sure they remember? Then incorporate it in your speech somehow.

"Before you install it, you have to make *sure* [pause, make proper eye contact and ensure you have their attention] to take the bolts out of that tube, you will need them to assemble said item"

The pause + eye contact is a good way to get their attention, as they will wonder why you suddenly stop and look at them.


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

[User] ELi5: How do those traffic counters (the black hoses across the street) work? How can they tell an 18-wheeler from a car?

[Assistant]
Short answer: they don't need to.

They are trying to figure out how much the road is *used*, not driven on. Obviously an 18-wheeler puts more wear on it than a motorcycle. A simple way to approximate it is just by how many tires cross the road.


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

[User]
[General Science Fiction/Future] Would exercising at a higher gravity give me super strength?

I've read about how being under the influence of weaker gravity for a few months can lessen bone density and muscle mass.  As a future security guard, I'm heading to an asteroid mine in a trip that's going to take a few months and I need to bulk up as these miners are a rough bunch.  So doc, if I train under the influence of 1.5 or even 2 g for several months, will I gain extra strength or will my body be unable to handle the stress?  If I do gain the extra strength, will I be noticeably bulkier or will I have disproportionate strength?

[Assistant]
Not in the way that some show it.

Sure, exercising in higher gravity would strain your body more, which would (if it didn't kill you), give you more exercise and thus more strength.  But it's not as simple as that.  You could exercise just as well in 1G.

Usually when sci-fi gets into strong people from high-grav words it's that they grew up in high gravity and that their bodies have adapted to it over generations.


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

[User]
ELI5: Why do house cats have sudden freak outs? Do large, exotic cats like tigers and such also have random burst of crazy energy?

After my kitten spent the last 10 mins going crazy, I'm a bit curious.

[Assistant] House cats can't spend their energy hunting food so the energy bursts out in the form of "freak outs" and it usually happens during the morning hours when their wild relatives usually hunt. They need action.


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

[User] ELI5: Why does NaCl solution conduct electricity while solid NaCl doesn't?

[Assistant]
When you dissolve an ionic substance (like NaCl) you actually no longer have NaCl what you have are Na+ and Cl- floating around in the water.

Since these pieces carry a charge, they can arrange to conduct electricity.

EDIT: Since people keep asking why salt water tastes salty:

Your salty receptors detect the sodium cation (Na +).

In fact if you have salt in your mouth, it's at least partially dissolved so it would be a more interesting experiment to try eat a block of salt with no saliva and see if you taste it( not that that's actually possible)


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

[User]
ELI5:How does Hollywood unanimously blacklist a person like Mel Gibson?

How are they able to entirely blacklist him?  Is it actors not wanting to work with or studios just saying no?

[Assistant]
Studios know that moviegoers won't go to see a Mel Gibson movie because of his tendency to go on racist, sexist rants and there are plenty of older actors to cast in roles that Mel might audition for that will draw bigger audiences and won't be as troublesome.

I doubt that all of the movie studios got together and decided to blacklist him, they all came to the conclusion independently that it's not worth it to work with him.


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

[User]
What happens to the earth/soil beneath large cities over time?

When I visit NYC I can't help but wonder what the conditions are beneath miles of tar and concrete. What are the long term implications?  Have there been many geological studies on this?

[Assistant]
It really really depends on the type of geologic environment you're building on. In NYC, it's mostly alluvial, so the foundations of the buildings go very very deep, whereas in Finland, you can build a highrise just on almost the open ground because the bedrock is on the surface.

Buildings are no where near heavy enough to cause any kind of geologic phenomena (earthquakes) if that is what you are concerned about.


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

[User]
ELI5: Humans have been around for roughly 100,000 years. Why have we advanced so much in the past 5000?

I know that we have evolved to be more intelligent and capable, but why such a rapid increase lately?

[Assistant] Much of it is attributed to the Agricultural revolution. For some reason, humans in Eurasia stopped being hunters and gatherers to favor farming. Farming led to more food, which led to more people, which led to more people to discover different things which advanced us further.


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

[User]
Can we find an ecological alternative to conferences?

I was quantifying my CO2 emissions for the year. I've been responsible for about:

* 1.3 tons for heat and electricity of my home.
* 0.9 tons for transportation
* about 1.5 tons for food and miscellanea
* A guesstimate of 0.3 tons for the electricity that my academic pc-based job uses

That's about 4 tons of CO2.

Then I went to 2 conferences this year (1 in the same continent, 1 with an intercontinental flight). That's about 4.5 tons of CO2. To meet a bunch of people for 4 days each. I mean... the networking I do and the things I learn are extremely important for my career. But the environmental impact is completely unjustified. It's totally against both my coscience but also logic to emit more CO2 for a 4 day thing that for heating a home for a year.

What do you think about it?

[Assistant]
Speaking as a neuroscientist who regularly attends SFN, at least half the reason for going is to get a picture of in-progress research before it hits the journals.  The other half is to reconnect with old colleagues and network with potential new ones.

The poster sessions and talks could be replaced with online versions, so long as we can treat preliminary research online the same as we treat it at the conference.

The networking, on the other hand, is irreplaceable -- there's no other way you'll ever get this sort of group in the same place together.

I've come to the conclusion that attending every year is unnecessary -- skipping at least once every three years makes more sense. Aside from that, there aren't many good solutions that don't involve the US building a world-class high speed rail network.


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

[User] ELI5: Is there any scientific reason why the US's shuttle launches were about as far East as they can possibly manage on their home soil?

[Assistant]
Yes. In order to get into orbit, you have to go really really fast horizontally so that the rate at which you fall matches the earth's curvature. Being in orbit is just falling, but missing the ground.

You as a person standing on the ground are already going really really fast in a west-to-east direction thanks to the earth's rotation. When you launch in a rocket, you carry this speed with you. This makes it easier to get into orbit if you go in a west-to-east direction. If you go east-to-west, you have to accelerate against the direction you are already going in.  Since you have to launch over an ocean so your falling booster rockets don't land on people, it's better to launch on the east coast.

BONUS FACT: Since the Earth rotates faster closer to the equator, it's also easier to get into orbit by launching further south. Hence why rockets launch out of Florida, and not Maine. However, if you want to do an orbit north-to-south around the poles, you have to de-accelerate against the speed from the earth's rotation. This makes it best to launch as close to the poles as possible. This is why rocket launch facilities are currently being built in New Zealand, Nova Scotia, Alaska, South Africa and the Shetland Islands.


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

[User] ELI5: Why have wages been stagnant since the 60s, yet housing costs have doubled and college costs have trippled?

[Assistant]
Supply and demand. The population has increased, and unskilled and skilled labor that doesn't require college education has been placed over seas where wages and cost of living are lower. Therefore you have more unemployed people desperate for work, more people pursuing housing, and more people entering universities.

However, while demand is significantly higher, the number of universities and their capacity hasn't increased at a similar rate. Furthermore, American culture has shifted from tax payer subsidized state universities to direct tuition payments, increasing perceived cost to the student (and their parents). Additionally, due to decreased tax payer funding, many of these same state universities now focus on tuition payments from out of state (and country) students that they can charge at higher rates. This decreases the available seats for domestic students, again lowering supply and increasing prices.

As for housing, these costs have increased predominantly in urban areas where population density has continued to climb. In places like D.C., Seattle, NYC and San Francisco, there has been a huge migration of people back into these urban areas away from suburbs. Due to the lack of land to develop more housing, the housing costs there have increased at an astronomical rate. Additionally, since the 1980s, there have been huge influxes of foreign investment in American housing as a vehicle to safely store foreign wealth in a form easily converted to dollars. As with universities, the mix of increasing population both domestically and by addition of foreigners, combined with a limited resource (land) that cannot develop as fast as the population grows increases costs.


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

[User]
[X-Men 2] How many people died when Xavier mind-flayed every human on the planet?

And what were world governments' response?

[Assistant] The majority of normal humans jut got a bad headache from the short exposure. Striker seemed to have taken no real damage of any kind from the experience. A few very weak, sickly, or elderly may have died as a result but their numbers were probably very low.


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

[User]
[The Mummy] Why is the curse to bring the undead harbinger of the apocalypse back to life on the first page?

No introduction or anything? Generally basic spells come first, not ones that have the power to doom all of humanity. What were the Egyptians thinking?

[Assistant]
The Book of the Dead isn't some beginner's instruction manual, you fool. It's only supposed to be read by two groups of people, high priests and those who have already moved on to the afterlife. It provides secrets and guidance to the afterlife, which was full of far nastier shit than what even the Mummy could dish out.

And more importantly. You broke into a tomb, ransacked a dead body and defiled a sacred and ancient site, and then began speaking dark incantations, knowing full well what the magnitude of the book was. You deserve every horrible thing that happens to you...filthy tomb robber.


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

[User] [MCU] When Loki and Thor are shown in flashback looking like ten year-old kids, was that actually twenty years ago, or thousands?

[Assistant] Well, baby Loki was found a thousand years ago after the war with the frost giants. Unless they age reeeeeeally slowly, it's likely that that scene is ten years after the war with the frost giants and therefore significantly more than 20 years ago.


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

[User] What happens to pain while you sleep?

[Assistant] When you go to sleep, a part of your Brain called the Reticular Formation decides what signals it should block out. This is the reason why when you lie in bed to sleep, you don't feel the sheets under your skin the whole time, as you do when you first sit down. This part of the Brain also controls what pain signals are sent to the Brain. So when you sleep, it blocks out regular signals that would disturb sleep.


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

[User] Eli5: if the lawsuit against Obama proceeds, what court is it heard under? How does this work?

[Assistant]
It probably doesn't get heard in any court.  There is a requirement in the federal judiciary that the aggrieved party (i.e. the Speaker of the House) can show harm was done to him (i.e. by Obama signing executive orders).

Keep in mind that matters of "unconstitutional behavior" are part of the impeachment process, and cannot be pursued in any court.  The impeachment process is completely in the hands of the Congress.

Furthermore, even if it were ruled that the Speaker had standing in federal court, it is unclear what remedies a court could order... but we're going a long way down the Speculation Railroad when we don't even know the grounds on which Boehner intends to sue.


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

[User]
Does power cause evil or are the people in power evil because it helps them get ahead?

It's a common belief that power corrupts, but it's also a common belief that evil people get ahead. Which is more true and why? Does having power actually make people evil? Does being evil actually give power? Is it a one way causal relationship or is it a never ending loop?

[Assistant]
With regard to "power corrupts": Power simply amplifies the expressibility of every weakness (and strength) a person has.

I am reminded of the end of Hamlet's soliloquy:

> Their virtues else--be they as pure as grace,
As infinite as man may undergo--
Shall in the general censure take corruption
From that particular fault: the dram of eale
Doth all the noble substance of a doubt
To his own scandal.

The "dram of eale" refers to a small amount of evil that destroys great good. The more power we have, the more accelerated the process of amplifying our weakness becomes. With great power, the smallest defect in human character is amplified greatly.

It is also true that already corrupt people can leverage advantages unto their idea of success faster. In the acquisition of power, the already corrupt still have their corruptions amplified. The two options in your question can exist together and also have their own independence.


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

[User]
[Star Craft] Ima marine, on my last deployment my guns and armor were fully upgraded yet when I deployed this time my gun is much weaker and same with my armor all the way down to its base level. Why is that?

Who is spending the time to downgrade our arsenal in between fights?

(sorry for thr title gore I did not get a chance to edit it fully I accidentally clicked submit before I was ready)

[Assistant]
Upgraded gear require significant logistical infrastructure to maintain, particularly with regard to vespene refinery and enrichment. High command deemed it unfeasible to erect interstellar supply lines in support of every planetary campaign. Instead, thanks to the relative abundance of vespene and raw materials, a distributed logistical approach was taken whereby forces are equipped with low-maintenance, reliable, baseline materiel as well as the resources to establish local vespene extraction and refinery on the ground.

This approach allows for rapid deployment of baseline troops where needed, without first requiring the establishment of supply lanes to maintain advanced equipment. As such Terran forces are effectively autonomous, capable of supporting and bolstering themselves almost anywhere. This kind of versatility and projection is absolutely necessary in the fight against the zerg, an agile and distributed hostile force.


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

[User] ELI5: Why have bugs gotten smaller over time?

[Assistant] Because today's oxygen levels in the atmosphere are lower than they have been 70 million years ago. Insects don't have lungs, they can't force air in and out of their body, but they still need the oxygen to reach their cells. So if they have a large body, a lot of cells are further away from their "breathing holes", so they have to steal oxygen from neighboring cells, who steal it from their neighbors etc. until some cell with direct connection to the hole. This works if there is plenty of oxygen around, but nowadays there's so little that the innermost cells would die.


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

[User]
What do heavy metals really do to a person, and what does our body do to get rid of them?

Theres been plenty of misinformation spread thanks to the vaccine scare, so Im curious to have some facts.

Lets say some unfortunate person has eaten a tomato with an amount of lead in or on it.

The symptoms of heavy metal poisoning are easy enough to find online, but what exactly is happening to cause the symptoms? Its usually a bad thing to have them around in the body, so what does the body do to remove them? Are they just filtered out by the kidneys like a lot of other stuff? Do they break down somehow on their own?

[Assistant]
Like people have suggested 'heavy metals' is vague so in general: proteins are constructed from amino acids basically small Carbon/Nitrogen molecules, however each type of amino acid has a specific molecular group (functional group) attatched onto the side of it (ie Glycine has just a hydrogen and methionine a Sulphur, Carbon and 3 Hydrogens). Proteins are folded into a very specific shape based on these groups due to the interactions between one another. There are likely 100s or more of these interactions that fold each protein, it's shape is integral to its function. One type of interaction between these functional groups is known as ionic ie. proteins bound to metals such as sodium, zinc, magnesium, potassium which the protein requires to perform specific tasks. Ie zinc finger protein in DNA regulation. However heavy metals can bind instead, disrupting functionality or alter the structure of a protein entirely.

Heavy metals can also bind to RNA and DNA meaning they not only effect protein synthesis and intracellular signalling of RNA, but also lead to carcinogenesis (binding to nucleic acids causing dysfunctional DNA replication). Remember DNA = Deoxy-Ribonucleic Acid.

So different heavy metals bind with different proteins (depends on frequency of amino acids present it can bind in that particular protein or how its folded and therefore what functional groups are exposed) heavy metals can also bind DNA which causes carcinogenesis. They can be excreted or sequestered differently within the body (this changes from human to human) which  affects its effects*. If you ingest mercury your gums will get sore and you'll get diarrhoea, however Cadmium will cause lung inflammation. These are acute symptoms, chronic would be cancer, neurological issues etc.

Edit: Cysteine to Glycine (been a few years).
Edit2:*

Also note Iron is also considered a heavy metal yet essential to our diet. Excretion of HM is quite a massive topic.


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

[User]
[ELDERSCROLLS] If you have magic, why are swords even used?

Think about it. Anyone can learn magic, so it isn't like wizards are hard to recruit. Also, a man with a sword has no chance against someone who shoots fire out their ass. Why are swords even used? For that matter, why doesn't everyone use magic?

[Assistant]
Being able to manipulate magic on the level of the player characters is extremely rare, and requires years upon years of research, practice and meditation.
Using magic in combat is also very tiring, and the people who sit around studying magic all their lives are very likely to be physically unfit in comparison to soldiers who fight with shields and swords, so they're likely to lose in a one-on-one battle.
Having every soldier be a mage is about as difficult as having every soldier be a mounted cavalry knight with full plate armor, shielding and training. It's very hard to find someone with the skill, dedication and resources to become a combat ready mage, so giving random mooks a sword and telling them to swing it at anyone in the enemy's group is much more efficient.


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

[User]
ELI5: Where does the skin on the body stop being skin and become something else? Openings in particular. In the case of the face does it end at: lips? tongue? throat?

In the case of the rectum I assume the anal sphincter is the last skin hurrah before its all about intestines. Correct me if I'm wrong. What about the nose, the mouth, the ears.. etc.

[Assistant]
Skin is a specific type of tissue- epithelial tissue. The other tissue types are connective tissue, nervous tissue, and muscle tissue.

Epithelial tissue covers body surfaces and lines most of our internal cavities. Connective tissues function for support and protection, such as bone, fat, cartilage, blood, and lymph. Nervous tissue receive stimuli and conduct impulses (neurons). Lastly, muscle tissue makes up, well, our muscles- skeletal muscle, smooth muscle, and cardiac muscle.

When considering the rectum to the anus, the rectum is lined with epithelium and the anal sphincter is made up of both a smooth muscle component and a skeletal muscle component. There are tissue transitions at these junctions, so the tissue will slowly become less epithelial in nature while also taking on more qualities of the smooth muscle until it is eventually all smooth muscle and no longer epithelium.


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

[User]
Does electricity need a high voltage or a high current to continue through a gap in a wire?

Say with a 0.5 mm gap would it be possible for me to get electricity consistently jumping across without dealing with a deadly current?

[Assistant]
You need high voltage. Air is a very poor conductor, but by providing the electrons with a high voltage, they have sufficient energy to ionize the air between the two ends of the wire and create a conductive channel.

At standard temperature and pressure, you'd need 3 kV per mm of distance, so in your case, you would need to apply at least 1500 V in order for the gap to be bridged.


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

[User]
[MCU] As King of Wakanda and the current Black Panther, why was King T'Chaka not wearing some kind of vibranium-armoured clothing or personal shield at the time of the UN bombings in Vienna?

I get that Wakanda was still unrevealed to the world at large, but surely the protection of the leader of the nation comes first?

[Assistant]
For one, T'Chaka wasn't the Black Panther at the time of the bombing, he had passed that mantle to T'challa by that point.
Beyond that, it was a risk calculation.  The risk of the meeting in Vienna being bombed was very low, and the risk of vibranium armor being discovered is rather high.
And on the other side of the coin, the death of the King is tragic, but Wakanda goes on.  Discovery of the truth of Wakanda's power and position has lasting implications for the whole nation.


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

[User] If Mars and Venus switched places, would Venus be hospitable for life?

[Assistant] This is an interesting question actually, hard to give a definite answer.  Venus in a Mars orbit would certainly be much warmer than Mars due to it's atmosphere. It would still have a dense atmosphere of carbon dioxide with almost no oxygen (edit: ,nitrogen and hydrogen), but life could possibly adapt to this.


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

[User]
Would debt forgiveness for things like student debt and medical bills have negative effects on the economy?

Im only asking because I saw a video on it, I liked it but I wasnt sure how actually feasible debt forgiveness would be, or rather if there would be repercussions for immediate forgiveness given the structure of debt in America. Like, would creditors not having debt to sell around have any affects on the economy in the immediate? How about generally speaking long term? Has there been studies conducted on this? I havent been sure where to look so I just wanted to come here and ask.

[Assistant]
Most lenders are companies and not governments, largely banks. This means forcing them to forgive debts is equivalent to confiscating their money and giving it to the people who owe the banks. Once you do that, banks either (1) pack up and leave, or (2) bake the probability that you will screw them into future interest rates. This effectively means that by cancelling debts for one generation of students, you doom all future students to have no access to debt - which basically means to access to higher education.

There are ways around it, for example the government might be the one issuing the loans; or more convolutedly, the government pays the loans to the banks on behalf of the borrowers. This isn't great either, because you're effectively transferring money from taxpayers to students/sick people (and banks get to pocket a bit too). But not to all students/sick people, just the ones with poor financial management (we call this moral hazard). Ironically, the ones with good financial management would have realised they can't afford student debt in the first place and not have taken any. In that case, the superior policy would be to just provide free or heavily subsidised education/healthcare, which avoids this entire tangle.


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

[User]
ELI5: What is the difference between a fit person's veins that "pop" so they are visible from the naked eye and eg. a grandma with clear veins on her hands? Are they a good sign of health?

For those who dont understand what I mean, typically when you see a very fit person's arms or legs, you can see veins running down them. But then if you look at an eg. Grandma's hand, there are several veins there also. She doesn't do weights, or not exactly the same amount of exercise the 'fit' person does, so whats the difference? Also is it a good sign of health?

[Assistant] It has to do with the mechanism by which the veins are visible. In younger people, the veins are visible because the muscles are pushing them up against the skin and there's no fat blocking them in. In older people, it's usually because the skin is thinner and becoming more pliable meaning it forms around the veins. The visibility of veins is not in and of itself healthy, plenty of malnourished people have visible veins and they are arguably not any healthier than a person of average build without veins showing. It usually just indicates a high muscle-to-fat ratio or looser skin.


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

[User] ELI5: We have seen that Honda robot tentatively tiptoeing around for the last decade, why can't we build a robot that can walk in an anatomically correct way?

[Assistant] There are some bots who can walk pretty well.  But it is very difficult, especially on uneven ground.  There would be a huge push to figure it out and you'd see them all over the place if it wasn't WAY easier to slap some treads on that motherfucker and be superior, more stable, more mobile in every way.


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

[User]
ELI5:  Romney's plan for the economy

Exactly how will Romney fix the national debt, create jobs, and keep reform taxes to be fair?

[Assistant]
well like Obama he hasn't gone into extreme detail on everything he plans to do.

But generally he thinks he can lower the national debt by creating jobs and bringing us out of a recession (growing out of debt is a well-known and effective strategy).  He says he would create jobs by lowering taxes on the rich and businesses so they would have more money to hire more workers.

He also said he would lower taxes for everyone and would pay for it by removing some tax "loopholes", although he hasn't mentioned exactly what he would remove.


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

[User] [Terminator 2] Is the T-1000 100% liquid metal? Or does it have a traditional processor floating around in there somewhere?

[Assistant] What we perceive as the liquid metal is just what these nanomachines look and behave like at a macro level. These nano machines are all connected much like a hive mind. There is no single processor floating around much like there is no single powerplant powering the thing.


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

[User] [The Expanse] Why had there been no interstellar exploration before the Nauvoo? Given how insanely powerful the Epstein drive is you'd think the UN or MCR would have sent at least probes to nearby stars.

[Assistant] Even with the Epistine drive it was going to take the Nauvoo hundreds of years to reach its destination. We also don't know that there aren't probes out there, deep in space, making their way through the void.


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

[User]
Viruses often (usually?) have high specificity to a certain species or small group thereof. What makes rabies so able to hop between distantly-related species?

It's typically a big deal when a virus leaps from one species to another (e.g., humans) because viruses have to interact with proteins on cell surfaces, which differ greatly between species.

Rabies, however, is very commonly transmitted from nonhumans to humans; 99% of rabies cases in the world are caused by dog bites, with the rest being mostly bats. Moreover, rabies can infect all warm-blooded animals and many cold-blooded ones. Most animals can be infected, though many never show symptoms.

So, what makes rabies-causing viruses able to infect such a wide range of species?

(I know that there are lots of different viruses that cause rabies, but to me this just begs the questionwhat makes *so many* viruses seemingly more capable of crossing the interspecies barrier?)

[Assistant]
PhD in rabies here! Most warm blooded mammals share the nicotinic acetylcholine receptor that rabies uses as its main entry receptor.

There are other entry receptors like NCAM and glutamate receptor.  Basically these factors are essential for a functional nervous system and rabies preferentially interacts with these factors to enter cells.    All warm blooded mammals need a functional nervous system.  Rabies does not infect cold blooded animals.

Another reason is the stealthy nature of rabies - it slowly replicates (1-3 months incubation period in humans) and is not expressed on plasma membranes. It is essentially hidden from the body by continuously internalizing its glycoprotein, making infected cells invisible to the immune system and infected cells burst a lot slower than what other viruses do.

A third reason is its ability to promote cell to cell spread by binding motor proteins and reorganizing infected cells to create cell surface projections.

Fourth reason is the simplicity of the virus - just five proteins and the viruss host binding partners are potentially not very specific - promiscuous binding as opposed to a lock-and-key binding.

There are many things we still do not understand but these points are what science reasoned so far.


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

[User] ELI5: If there is no erosion on the moon, how is there dust on the surface?

[Assistant]
take a rock.   bash it with a meteor going 10000mph.   you get smaller rocks.    take smaller rocks.  bash it with a meter going 100000mph.   get even smaller rocks.

repeat that a million years.   you get dust.


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

[User]
Eli5: who are these robots that reCAPTCHA protects us from?

Who are they? How does it all work? What would happen if captchas weren't there?

[Assistant]
The robots are programs designed to crawl sites for various reasons. They are easy to create by programmers. Not having CAPTCHA can result in:

- content theft
- credentials theft via brute force attack
- being scanned for vulnerabilities
- increased server load (a script instance can load a server as much as thousands of users)

In many cases CAPTCHA as devolved into a due diligence checklist item that insipid security auditors with no technical knowledge insist upon for no real reason.


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

[User]
[Star Wars] Why did Queen Padms vote of no-confidence matter?

Ive just watched all the Star Wars films for the first time, and one of the many things which left me a bit confused was this.

If Im correct she wasnt a member of the Senate at the time but she was able to put Forward that motion.  What was so special about her or Naboo that allowed her to do so?

Im probably just nit-picking or skipped a couple lessons on galactic politics
Thanks for any help/information!

[Assistant]
Two potential explanations that have been floating around:

1) she requested the vote, but had no binding authority to actually demand it

2) senators (as they seem to be appointed by the planetary leaders rather than elected themselves) are more or less a proxy for the current leader and as such, the current Queen could act as a legitimate representative for Naboo.


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

[User]
Taking two-sided limits using advanced algebra. I know how to solve it, but why does it work?

Hello, sorry if this has been asked before.

I'm studying calculus on Khan Academy and one of the required skills involves problems such as this:

lim x->1 (x^3 - 1) / (x^2 - 1)

Which is apparently unsolvable because you can't divide by zero, unless you play around with algebra and make it solvable:

(x - 1) (x^2 + x + 1) / (x + 1) (x - 1)

(x^2 + x + 1) / (x + 1)

And your limit is (1^2 + 1 + 1) / (1 + 1) = 3 / 2

Ok, fine. I know what to do.

But *why*? How does a division with an undefined result magically become solvable because I played around with the variables? It doesn't make sense. Things tended to wrap around more tightly in HS algebra. What exactly is going on that solves the problem? Is there a way to explain to a non-mathematician?

Thanks in advance!

[Assistant] The limit does not include the value it is approaching. The reason why it works is because you changed the first function to form a second function that is equivalent at all values except for x = 1. The first function is the same as the 2nd, except there is a hole in the graph of the first function at x = 1. Because the limit does not include the value it is approaching, the value of each function at x = 1 is irrelevant; the values approaching 1 is what matters.


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

[User]
ELI5 the reason the brain and body ages faster in dogs than humans

What distinguishes any life form from aging at a different rate?

[Assistant]
There are a few systems at play that seem to be in common between short lived and long lived species.

The slower the heart rate, the longer they live. Whales and galapagos toirtoses can live a very long time, and have very low heart rates. A hummingbird has an incredibly high heart rate and they don't live long at all.

Smaller things tend to live shorter lives than larger things. But a bacteria is really small, and it may never die under ideal conditions. A lobster starts out pretty small, but if allowed to live they just get larger and larger and nobody knows for sure how long one might survive if left alone. Perhaps longer than a human.

The main factor for what causes aging in any animal is the limits placed on cellular reproduction by the DNA and RNA. Cells only divide a certain number of times before their internal clocks start to slow down, causing longer periods of time before splitting, and the cells get older. Usually cells are replaced fairly often, but as you grow older this slows down, so that when you're a kid the oldest cells in your body may only be a few years old, but by the time you're old it might take several years before a cell is replaced.

Having an organism that gets old and dies, is bad for the individual, but good for the species as it forces the old to make way for the new and it prevents over population. When a species has few natural predators it tends to have few offspring and a longer life. When a species has many predators it tends to have many offspring and shorter lives. If predatory pressure were removed from a species, they would over populate, leading to lack of food and death.


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

[User]
Where is the best country to be an academic?

i'm british and want to go into academia. having paid attention to recent strikes it seems like academics in the uk get a pretty raw deal. obviously nobody will have experience of everywhere in the world, but where is generally considered the best place to be an academic? US/Canada? Continental Europe? Somewhere else entirely? Thanks

I am talking specifically with regards to job security, ease of progression, pay, etc.

[Assistant]
In the 80's Thatcher plunged the knife into the UK academy's back with the destruction of tenure and the top-down, mandatory, management-consulting derived metric-obsession that ruins everyone's life from faculty to dean and beyond.

the UK academy has been bleeding to death ever since.


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

[User] [Star Wars] Do lightsabers work underwater or in a vacuum?

[Assistant]
Since none of their components relies on oxygen to operate, a lightsaber would almost certainly work just fine in a vacuum, though it wouldn't seem quite the same without the trademark hum.

Most lightsabers are vulnerable to water, however; the crystal circuit can easily short out when submerged. However, an ancient modification from the early days of the Jedi order was known to circumvent this problem. Amphibious Jedi Master Kit Fisto was the first to rediscover it, finding that a bifurcating cyclical-ignition pulse (a quick-change circuit that continuously alternates drawing its power from two separate crystals) could prevent his lightsaber from shorting out underwater.

When he added this knowledge to the Jedi holocrons it became a common modification among the Jedi generals in the clone wars, who frequently had to command on very wet worlds. One such lightsaber was Anakin Skywalker's, and Luke studied its design and later replicated it in his own green saber. By the time he founded the New Jedi Order, crystal pulse bifurcation was standard on all new lightsabers constructed.


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

[User] [Family Guy] What kind of strings do you have to pull to have the literal foot of the Statue of Liberty hand-delivered to your (or your neighbor's) doorstep?

[Assistant]
Plot Strings.

Jokes aside, this would be more criminal than legit, much like how in *National Treasury.* You'd pretty much need a team  like Danny Ocean's on Melange to get the foot free of the statue and base, as well as some A Team levels of bullshit to get it shipped.


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

[User]
ELI5: Why are there new socket types for almost every CPU generation

Is there any benefit to it ? I mean, I get it that CPUs themselves are faster, but does the actual socket (for eg. LGA 1151 vs 1150) offer any additional benefits over its counterpart ?

[Assistant]
Modern CPUs have a **lot** of things built into the chip.  You've got memory controllers, PCI Express controllers, USB controllers, graphics chips and all sorts of other things.  Motherboards need to be designed to interface with all of these things properly.  If the chip changes, you need to redesign motherboards & having different pinouts makes sure there's no confusion.

In years past, when a CPU was just a CPU & the motherboard chipset handled all those other features, it was much easier to share a CPU socket between generations of processors.  Back in the Pentium 2/Pentium 3 era, there were several major revisions of the CPU that could all work with the chipsets on *Slot 1* boards and, even after Intel upgraded to *Socket 370*, they were still *logically* identical so a Socket 370 CPU could be put into an adapter board and run in a Slot 1 motherboard without a problem.


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

[User]
[Star Wars] Are blockades really useful the way they're used?

From what I've seen, blockades are made up of a ring of ships around a planet, but they leave the north/south poles (or opposite sides) unprotected. What's stopping people from coming out of hyperspace in a different direction and landing on the planet before the blockade can stop them?

[Assistant]
Not much, really. Blockades in general, you will never be able to stop traffic completely, particularly when dealing with small/medium sized craft that are built for speed. (Thus, blockade runners)

All a blockade has to do is somewhat control the gravity well, and an equatorial orbit is good enough, particularly if you have smaller craft or missiles to launch in response to emergent threats. Even if force projection isn't fantastic, commercial vessels would have a hard time justifying risking their livelihoods should they get caught trying to break through by a fighter patrol or long range scans.


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

[User]
[Star Wars] In Rise of Skywalker, how did the galaxy know Palpatine was actually alive rather than just an impersonator who hacked into the Holonet?

Did anything actually happen immediately after his announcement to provide evidence his return was real?

[Assistant]
They didn't know he was actually alive.

This is why the Resistance needed information from a spy within the First Order to confirm that Palpatine had returned.

Also, it was not known to the public that Sheev Palpatine was a member of an obscure religion that was wiped out a millenium ago. This gives a great deal of legitimacy to those in the know like Leia and Lando.


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

[User] If free trade is so good, then why do countries insist on making trade deals? Why can't we just abolish all tariffs?

[Assistant]
In a nutshell, because free trade is optimal for overall efficiency but it can harm specific constituencies. For instance, import tariffs on soybeans will usually make soybeans more expensive in the domestic market, but they will benefit the domestic producers of soybeans. Therefore, soybean producers may lobby their government to keep the tariffs in place. And although there are many more consumers of soybeans who stand to benefit from removing the tariff, than producers of soybeans who would be harmed, the producers are a lot more politically motivated to act. Very few people would have their vote hinge on the price of soybeans changing by $150/ton. But that could make a huge difference for producers.

Trade deals are a way to package a bunch of different tariff reductions together in a way that is politically palatable for both sides.


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

[User] [Star Wars] How did a physically impaired being such as Jabba The Hutt get so powerful? Shouldn't he have been facing mutiny left and right regardless of the rancor?

[Assistant]
If you read up on the Hutts, you'll find that they're actually physically quite strong, and they're BIG. They're also incredibly intelligent (force mind tricks don't work on them), long-living, great resilience, and crave power. That's just their physical stuff.

The Hutts have been running the show in the 'Hutt Empire' for a really long time. They've developed a monopoly on all the illegal and legal activity on their planets, and essentially cover each other's backs. If someone takes out Jabba, his brother or cousin or uncle will send an army of mercs to hunt them down.

Combining the two: Intelligence and power/money, there's no reason for a mutiny. Working for the Hutts is lucrative and has pretty good deals in place. He keeps them entertained with Rancor fights etc, and safe with his armies of mercs and bounty hunters.


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

[User]
Help me make my son a birthday cake.

My son is an aspiring software engineer.  He has been learning to code in his high school intro to programming class as well as in his spare time. His 16th birthday is coming up. I want to get him a birthday cake saying "Happy 16th Birthday Son" in javascript.  Can someone tell me how it should look?

I would be greatly appreciative.

[Assistant]
console.log("Happy 16th Birthday Son");

if you want to get really fancy you could replace 16 with 0x10 for a hexadecimal 16

if you want something a little more complete you could try:

<script>

document.getElementById("your sons name").innerHTML = "Happy 16th Birthday";

</script>


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

[User] [Toy Story] What would Sid's life be like if he never came across Woody and Buzz at Pizza Planet?

[Assistant]
Sid's discovery of talking toys, and his resulting discovery of the monster world, ended up getting him put into therapy, which helped him deal with his aggression, and set him straight enough to get a decent job as a waste disposal professional by his 20's.

If he never had any of that, he probably would have kept on his antisocial path and eventually ended up mixing with the wrong crowd and ending up in and out of prison.


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

[User]
How efficient are renewables right now?

By which I mean, at any give time, how much potential wind is being turned into electricity, is there a reason why it's so inefficient?

Also, what about solar? How much of the potential sun captured at any given moment is converted?

[Assistant]
There are theoretical limits (Shockley-Quessier limit for solar, Betz limit for wind) - around 35% and 59% respectively - but in another sense you're asking the wrong question.

Imagine two PV systems. They take the same amount of space. One that costs $1 million, is 30% efficient, and makes you $300,000 a year, and another that costs $500,000, is 20% efficient, and makes you $200,000 a year. Which is better? The one that generates more energy in the same amount of space or the one that pays for itself 25% faster? There is no shortage of places to put solar panels.


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

[User]
CMV: Government employees should be paid enough so that they can afford an average house in the town where they work.

In places like San Francisco and New York teachers, police officers, etc have a hard time finding housing because their professions do not pay enough to afford an average house in their communities.  We should guarantee that if you work for a local government you can afford the average house in that community \(with the condition you must live there as part of your employment\).  If that means a lower\-level employee makes $100,000 per year so be it.  It's not fair to require people to work for an entity that doesn't allow them to live in the place where they work.

[Assistant]
> It's not fair to require people to work for an entity that doesn't allow them to live in the place where they work.

1. Nobody is required to work for the government, they choose to.

2. Why limit this to government workers? Doesn't the private sector have the same problem with low wage jobs?


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

[User]
ELI5: What does a a movie producer actually do for the movie?

Are they just putting up the money for production? What does an executive producer do?

[Assistant]
Typically EPs are ones that just put up money. Producers do a ton of work. They are the general managers of a film. They manage the budgets, all the stars, the director, organize everything on the set, ensure they stick to the production schedule, determine how to handle cost overruns, etc etc.

If Da Vinci was a director then the producer would be the person who got him a studio, his supplies, his assistants, negotiated price for paintings, finding buyers, etc.


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

[User] ELI5: Some desktop programs have such an easy time being cross-platform between all the OS's (e.g. Chrome, Firefox, Spotify, Calibre) while other programs basically need to be rewritten from scratch to work on a different OS. What is the reason not all third-party projects use cross-platform code?

[Assistant]
Your premise is wrong. These software have a pretty significant amount of effort going into being cross-platform.

Planning for cross-platform from the beginning makes it look like a low effort endeavor, but it never is.


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

[User] [Star Trek]How centralized is the United Federation of Planets, how much automony do it's members have over themselves?

[Assistant]
It really depends on the particular issue when it comes to centralization. Agriculture is very world to world, while regulations regarding orbital traffic are not.

Matters of Interstellar Foreign Policy are decided by the President of the UFP under advisement from the Diplomatic Corps, specific expert advisors, & Starfleet Command, while Domestic (read: issues within the UFP affecting multiple Member worlds) are decided upon by the Federation Council. Matters affecting specific Member worlds are generally handled locally, albeit with a support network of resources and organizations spanning the entire Federation.

Singular (planetary) issues tend to be solved by that planet themselves, except in such cases where they lack the resources, wherein they petition the Council for assistance.

All of this presumes we're referring to Member planets, formal members of the Federation. signing into the UFP carries with it certain preconditions & requirements, among them universal suffrage, civil rights, non-discrimination, & secular governance.

Aside from that basic framework, local laws & regulations can vary, especially with new members, but, over time, most interplanetary differences in civil matters fade as travel & relations encourage members to standardize so as to make themselves more hospitable & familiar (and in turn find other worlds more hospitable & familiar to them).


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

[User] [MCU] If Iron-Man would get hit by an EMP wave, would it fry both his suit and his arc reactor chest piece thus killing him in the process?

[Assistant] He almost certainly *did* get hit by an EMP wave after the nuke went off during the Battle of New York. He was unconscious, and the suit seemed at least temporally shut down, but he didn't seem to suffer any other ill effects.


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

[User]
Why does our universe continue to expand if there is a limited amount of particles? Where is the extra energy and mass to push it?

Why does our universe continue to expand if there is a limited amount of particles? Where is the extra energy and mass to push it?

[Assistant]
Alright, so there are actually two very separate aspects to this question.

You don't need extra energy for the Universe just to keep expanding. This is for the exact same reason that if you throw a baseball hard in the air, you don't need to constantly be pushing it in order for it to rise higher and higher. Once the Universe is expanding, its tendency is to continue doing so.

But if that were the whole story, the Universe would keep expanding, but at a slower and slower rate, just like the baseball will go up and up but will constantly be slowing down. But in fact we found out - to our great surprise, about 15 years ago - that the expansion is *speeding up*. This means that there must be some component to the Universe whose tendency is to push things apart, whose gravity is repulsive rather than attractive. Indeed, such a component must be so exotic that its total energy *grows* as the Universe expands. This isn't as problematic as you think, because conservation of energy isn't really a fundamental law of physics but only holds when physics is independent of time (and the expanding Universe is definitely *not* independent of time), but nonetheless it's pretty strange. We have a few ideas of what that component might be, but at the moment it's all quite speculative, and we're still actively trying to figure it out!


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

[User] ELI5: Where does excess electricity go on a grid, is it just grounded?

[Assistant]
Because of how generators work, there just isn't excess electricity. Generated electricity is pretty much instantly consumed somewhere.

Now if for some reason power consumption drops suddenly, like say a major power line gets cut, the generators that make electricity start spinning faster because they don't have anywhere to dump power. There's a lot of mass in big generators so it still takes some time, but going too fast is still a problem.

For something like a steam turbine, if the power plant can't reduce steam input fast enough (it's hard to turn off a coal fire after all) they vent excess steam into the air.


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

[User]
ELI5: What's the difference between top load and front load washing machine detergent?

And, what happens if you use top load detergent in a front load washing machine (or vice versa)?

[Assistant]
There's no such thing as "top load" vs "front load" detergent. There's just normal detergent and high-efficiency detergent. Most front-load machines are high efficiency and most top load machines are not, but you can get top-loading high efficiency machines these days.

The high efficiency machines use less water, so they need a detergent that's designed for that. The high efficiency detergents are designed to make fewer suds (bubbles) than the traditional detergents. If you try putting a non-HE detergent in an HE machine, you'll end up overflowing with bubbles.

 If you put an HE in a non-HE washer, your clothes might not be as clean as you'd like, but it will otherwise be fine.


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

[User]
Does gravity have a range?

This might be a stupid question, but I'm curious about the range of gravity. When we say we are in zero gravity are we actully that or is the gravity forces just so low, that they have no practical effect? If there is a max range, how far should I be from an object with the weight of 1, before it would have no effect on me? If there is no max range, will the object furthest away from each other in the universe eventually be pulled together?

[Assistant]
No, gravity affects any object, no matter the distance. But at some point, it will not be noticeable at all.

When talking about "zero gravity", you probably mean a space station or something. First, usually the term is "micro gravity", and second, there is quite a lot of gravity out there. The astronauts don't feel it because they are in free fall around the earth. You can do the same in an airplane (costs you something like five grand).


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

[User]
ELI5: Does the gay population increase over time due to certain factors, or has the gay population been staying constant in relation to the total population?

Don't quote me on this but I vaguely remember reading a theory that argues that whereas it was a survival necessity for men and women to reproduce a long time ago, in today's day and age we are suffering from over population and we no longer have to be forced to reproduce between men and women, so the gay population is predicted to increase over time as part of our evolution. I don't have the sources for this theory but I'm wondering if there's any truth to this?

[Assistant] It is likely that the population of people who identify as LGBT is relatively constant.  Increased acceptance leads to more of that population coming out as openly LGBT, where in decades past those individuals might have not openly identified as such.


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

[User] ELI5: How are baby's urine and feces kept contained while in the womb?

[Assistant]
Urine is excreted out into the amniotic fluid and swallowed by the baby. no big deal, it's as sterile as can be, and metabolic wastes are also removed via the placenta.

Baby poop stays in the colon, the baby's first poop is a weird,black, gooey substance called *meconium*, normally they will have their first poop of this meconium after birth, but pooping before or during birth can be a medical emergency due to contamination.


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

[User]
[Pirates of the Caribbean] After receiving the Black Spot, Jack retires from piracy and reaches mainland America where he lives out his days. What can Davy Jones realistically do to him?

In Pirates 2 Jack orders the ship keep to the shallows to avoid the Kraken in an attempt to postpone Jones' judgement.

Supoose he manages to reach America and gives up his life of sailing and piracy and makes a living inland, far from oceans or large rivers like the Mississippi.

Could Jones still send crewmen to try and collect on Jack's debt? Do they have an innate way of sensing where he is (such as Wraiths being drawn to the Ring)?

[Assistant]
The Black Pearl and his various sea-based obsessions are the only things keeping Jack mentally afloat and focused. Jack will begin to sink into alcoholism and depression before he runs very far.

In 1720 there's very few inland places he can run anyway. America as we know it is a thin smattering of British villages and small towns along the coast or built on major rivers. He could become a town drunk in like Concord, or chill with the Native Americans until he discovers they don't know what rum is.


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

[User]
ELI5: Why do songs sometimes sound at a different pitch when the volume is low?

This can happen even with very famous songs, or songs that you know very well. As a musician, I feel confident to know the pitch of those songs I know well yet when the volume is too low I cant make out the exact pitch for 1-2 minutes.

[Assistant] Something harmonically important is not loud enough to establish the tonal center. Likely the bass. Without the bass notes (the chord roots), the tonal center can easily become ambiguous. Sometimes the remaining musical parts, such as guitar, piano, melody, etc., can still define the key and tonal center, but often in pop music, a lack of strong harmonic instruments isn't always present.


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

[User]
[Suicide squad] How are these guys supposed to take on a superman tier threat?

Ok Waller's pitch was basically "what if the next superman is evil?"

And her solution is team with powers including pyrokinesis, projectile accuracy and animal hybrid.

These guys are street levelers, they're not taking on supes.

Hell the most powerful "member" is the enchantress, who can't be properly controlled, since it relies on blackmail and whatever emotional tie she may have to her host's boyfriend.

[Assistant]
The idea was to get permission to weaponize any metahuman prisoners they can get.

Waller likely wasn't *actually* planning on using the Squad for metahuman threats; rather, she wanted a few readily accessible attack dogs to use for whatever mission she deemed appropriate. The Superman pitch was just to make it sound sweet.

As for the lower-tier members, you've seen how they perform in a fight. They're definitely useful as mercenaries if not outright soldiers.


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

[User] [Dune] if water is deadly to sandworms why do they attack and eat beings that are mostly water? Does eating a person kill the worm?

[Assistant]
Sandworms are not intelligent; they are bestial and operate on instinct.

As territorial animals they will attack and destroy creatures disturbing their domain; their primary method of attack is via their maw.

There are mitigating factors that reduce the impact of lifewater on the makers.

First is size: "adult" sandworms are hundreds of meters long (Paul's first worm ride was a worm that was 2,778 meters long). Their would likewise be a hundred or more meters in diamter.

So imagine our six quarts of blood as less than a droplet.

As well, sandworms generate a ton of heat, so you're probably going to get a little fried before getting swallowed.


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

[User]
Do discharged batteries weigh less than fully charged batteries?

All things being equal other than charge. Do expended batteries weigh less than full?

Hypothesis: I'd say yes, as chemical energy is being converted to electrical energy and then sent out of the battery there must be some loss of mass.

-edit-
Thanks everyone! As with most scientific things, this has only lead to more questions;)

[Assistant]
Answers depend on the specific battery chemistry. Zinc hearing aid batteries will gain mass for example. An A675 will gain about 200ug as it discharges from the oxygen and CO2 it captures from the atmosphere.

Lithium-ion and NiMH generally lose mass when charged due to the parastic gasses produced (mostly hydrogen and oxygen) they'll sometimes incorporate little pressure valves in their design to vent these volitiles.


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

[User]
ELI5: Why are hypotheses used when doing research?

If the point of doing research is to figure something out, then why does the scientific community care about your guess before you ever do any experiments?

[Assistant]
Let's say you want to figure out what makes grass grow.

How are you going to do that? What should you measure? There are a billion things you **could** measure, and billions of experiments you **could** run, but which ones should you focus on?

If you have a hypotheses (such as "I think grass needs oxygen to grow") you can easily design an experiment, test it, and either validate or reject your hypotheses. That is scientific progress.

If you don't have a hypotheses, you are likely just doing random stuff and it's hard to *learn* anything. ("I added blue confetti, and the grass still grew")


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

[User]
What would remain of a human body after nine thousand years?

If, say, someone died in the middle of a tundra nine thousand years ago, what would their remains look like today? I assume they'd be completely buried, much like ancient cities are today.

What if they died in a cave at the snowy peak of a mountain?

What if the entrance to the cave collapsed and their body got sealed off from the outside world? How preserved would they be? Would they go through mummification?

Would a person's skeleton survive that long?

I've, so far, asked three subreddits (two of which were incredibly helpful) and I figured this'd be the best place to ask. Thanks in advance!

PS: I used the Archaeology flair because I felt that'd be the most fitting, mummies n' all. The next ones I'd pick'd be Anthropology (because of Forensic Anthro.), Biology and Human Body.

[Assistant]
Hi, archaeologist here.

We'd find nothing of the person that died in the tundra. Their body would be eaten by all kinds of animals, insects and microbes.

The cave on the snowy peak might or might not save someone's body. Is it permanent snow or does it melt once a year? What altitude is it: does it harbor many animals that eat meat or not? Is the cave warmer that the surroundings outside? If it's seasonal snow, we'd probably still not find anything. If it's permafrost, and it freezes in the cave too, we might find a mummified, freeze-dried body, provided it didn't get disturbed by animals.

With the cave entrance collapsed, the body would probably be isolated from the cold and still decay, at least as long as there's oxygen. The skeleton would be left though because that needs more to decay than just soft tissues.

Human skeletons can survive 9000 years if the conditions are *just* right. More often than not though, permafrost isn't all that permanent over 9000 years, deserts don't stay deserts for 9000 years and bogs don't usually stay bogs for that long. So even if the circumstances are good for preservation in the beginning, climate change and landscape change (earthquakes, floods etc) will change the circumstances and suddenly animals, insects and oxygen will have access to the body and it will still decompose.

In very rare circumstances though, when the environmental factors don't change after decomposition, we can still find a "silhouette". The decomposition chemicals cause discoloration of the soil and we can still make out the way the deceased person laid and do some microbial sampling. The body itself is still gone though.