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

[User] ELI5: Why is the golden ratio common to so many things of different nature?

[Assistant]
Say you have a seed. Deep down in the genetic code of the seed is the simple genetic code that says "have these cells build more of themselves." If you let all those cells grow, the ratio between old cells and new cells will usually be the golden ratio.

The golden ratio is so common in nature because it is the product of such a simple idea: the ratio between the first thing and the second thing is the same as the ratio between both those things and a third thing. It's what you always get when you tell cells or leaves or branches or scales to just "grow more of yourself."


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

[User] [The Culture] i want to join the culture, how do that? is there a number i call??

[Assistant]
The Culture is an anarchy. There's no central authority - only a bunch of entities that mutually recognize each other as being Culture.

Basically, visit a Culture habitat, and stick around for awhile. You'll interact with the people, and the local Mind will notice how well you do or don't fit in. If you do, then over time, the Mind will start treating you as one of the gang. At that point it'll help you get all the various biological upgrades that come with being Culture (if you want them), and then if you ever visit a *different* Culture habitat, the Mind there will see that some other Mind thought you were decent folk (and if they really want to, they could ask around a bit, figure out where you came from, and get a reference), and it'll treat you like one of the gang too because it generally trusts the judgement of other citizens.


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

[User]
ELI5:What is the difference between "Obamacare" and universal healthcare in other countries, such as the Canadian system or the UK's NHS?

I know that Obamacare is sort of a compromise, and that it's not really government healthcare, but I just don't get it.  I've searched ELI5 and read some of the ones about Obamacare, but I'd like to see sort of a comparison between OC and government healthcare.  ELI5, please?

[Assistant]
It's really really different.

Obamacare is really a term to refer to the law which increases government involvement in healthcare and adds additional regulations on health insurance companies.

If we were to implement a healthcare system like in Canada or the UK we'd have started providing healthcare directly through taxpayers (in effect the government would be the "single payer") and the government would run the healthcare system as a whole.

As it stands The changes in obamacare are far closer to what we had before it, then to systems like in Canada and the UK.


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

[User]
How is it possible that Protons and Neutrons can convert into each other through beta decay (^ and ^+), but both ways emit energy outwards (as electron & electron-type antineutrino or positron & electron-type neutrino)?

Where does the energy for that come from?
I mean suppose you could just simply convert one single Proton into a Neutron through ^+ decay, and then change that newly made Neutron back into a Proton through ^- decay (or go with ^- decay, then ^+ decay, whatever), and repeat this process over and over, how does that Nucleon get the energy to create new electrons/positrons and electron-type antineutrinos/electron-type neutrinos it can emit each time there's  decay?

Also, with ^ decay: Why isn't the Atom positively loaded after emitting an electron?
And with ^+ decay: Why isn't the Atom negatively loaded after emitting a positron?
How are they still neutral after losing an electron/positron?

[Assistant]
Only neutron->proton beta decay occurs for isolated particles, because the neutron is more massive than the proton (by about 2.5 electron masses).

Proton->neutron beta decay only occurs in certain nuclei, where the re-arranging of the nucleus after the decay leads to one with lower energy (mass) than before.


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

[User] ELI5- Are lithium batteries in electric cars more dangerous or hazardous than a gasoline car? If so, why or why not?

[Assistant]
On average there are 1529 fires per 100,000 gas vehicles and just 25 fires per 100,000 electric vehicles.

I am a firefighter, we have had to look at EV's in detail not because they are catching fire at a greater rate, but because of the risks to fire crew on scene and the difficulty in keeping an EV extinguished.  There are special storage and space considerations for an EV once it reaches a yard for insurance inspection and eventual scrapping too.  An EV fire is toxic as hell (not that a gasoline fire is a delight either of course).

We have to know and understand that if an EV catches fire in a rural or remote location, then it is likely that we will not have access to sufficient water for cooling/extinguishing.  We can call for 'make tankers x ' to have a shuttle system in place for deliveries of water in 6 ton loads, but at any typical motor vehicle accident you find yourself trying to manoeuvre in 14 ton tanker vehicles in a traffic jammed, restricted location and it becomes a serious hassle.

In short, it appears that EV's are vastly less likely to catch fire, but when they do it's a pain in the arse.  It's worth noting that EV's as modern high-tech vehicles have so many safety features too (compared to 100 years of gasoline vehicles) which would help with the incidence of accidents.


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

[User] ELI5:Why do rockets go in a curved path right from the beginning?

[Assistant]
In order to stay in orbit, when falling down, you need to miss the Earth.
To do that, you need to be going really really fast to the side.

So rockets eventually start pointing all the way to the side and start firing in order to build up enough sideways speed to miss the Earth.

However, if you tip the rocket slightly, you make if slightly off balance, meaning gravity is going to pull it in the direction it's tipped. Sorta like a pole falling over.
Since you want the rocket to turn that way anyway, you can save some turning equipment and let gravity do the work.
But if it's tilted the wrong way, your rocket turns the wrong way, and that's really bad.

So you tip it early yourself.

You still want to get out of the thick air as soon as possible, so that's why it's mainly still going up.
You also still don't want to turn too fast, so you keep some control to stop it from flipping, but otherwise you let gravity do the work.

Another consideration is that the buildings to launch rockets are expensive.
If something goes wrong and your rocket can't go to space today, you want the exploding flaming wreckage to fall somewhere there's nothing important.
So best start pointing it away from the expensive rocket buildings.


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

[User]
[Dragon Ball Z] Who is Frieza selling planets to and what are they offering in trade?

At first the idea of him just selling planets makes sense if he's eliminating the entire population, but to whom is he selling them? Also what is he getting in exchange? Currency doesn't seem like a likely candidate so what is he getting in exchange for a planet?

[Assistant] Maybe he's selling lordship to a planet. Say you wanna run a planet with lots of illegal activities, but you can't take over a planet yourself. So you go to Frieza, he gives you the space and takes a rather large portion of profits from illegal activities. Similar to mob loans.


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

[User]
ELI5: How do we know the universe is 14 billion years old? Do we have telescopes that can see that far?

So, I understand we know the age because that's how long it took the light to reach us - but do we have telescopes that can see that far? If we invented modern Hubble telescope with better technology, wouldn't we be able to see farther than the current one, or am I sorely misinformed about how telescopes work?

[Assistant] The age of the universe is determined by measuring the rate at which its expanding. The light emitted by an expanding galaxy becomes redder as it moves away. This is called the red shift. The rate at which the colour changes determines its velocity. If this velocity was reversed and the galaxies move closer with the same rate of change, the time taken for them to come together to a dense point is measured as the known age of the universe.


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

[User]
How do transistors act as amplifiers?

I understand how they can Bernab like switches, but how do they behave like amplifiers? What exactly do they do to have this characteristic?

[Assistant]
They way they work as switches is essentially the same way they work to amplify.

There's three wires from a transistor-- the source, the drain, and the gate.  The gate can be thought of as a valve that opens and closes flow from the source to the drain.

When used as a switch, the valve is basically just opened or closed all the way.  Things either flow or don't.

But you don't have to open the valve all the way-- it can be a little open, or halfway, or 80%, or anything in-between open and closed.

Now... imagine that the source is connected to a big power supply.  If you send your small signal to the gate, it opens and closes the valve proportionally to the signal.  If you open the gate 50%, you get 50% of "very big power supply" at the output.

So you essentially make a much bigger "copy" of the original signal by using that signal to open and close a valve proportionally to the signal, which lets through a much bigger amount of power, and that larger power supply is shaped by opening and closing the valve to come out as an amplified version of the original.


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

[User]
Why does the fuel pump "snap" off before my gas tank is filled?

Not towards the end, but like when you've only put a few bucks in.

[Assistant] There is a small hole at the bottom of the nozzle that triggers a pressure activated switch when closed (or immersed in liquid). This is supposed to activate only when the tank is full and the fuel is at the same level as the nozzle, but in this case it may a design flaw in the pipe leading to the tank not draining fast enough.


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

[User] [LOTR] Did any Hobbit in the original trilogy know Gollum back when he was still Smeagol, or know people who knew him then?

[Assistant] No. Remember, Gollum had the Ring for 500 years. Bilbo achieving 110 was seen as an accomplishment. Even the Old Took only lived to be about 130. Anyone who knew Smagol would have died a long time ago.


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

[User] [LOTR] Say Sauron suddenly got the One Ring towards the end of the War of the Ring, but just as he gets it, ALL of his human allies from the east and south immediately betray him, and invade Mordor. Could Sauron win?

[Assistant]
Sauron rules through fear, and if he actually got ahold of the one ring it is very unlikely that they would betray him, and if they did, they would likely just go back where they came from.

That being said, if they did invade Mordor, it is likely they would all be killed. Sauron's orc forces in Mordor were massive ( we dont have exact numbers.) The forces at the black gate completely surrounded the 6000 strong army of men, and the war was also being waged all across middle earth.

The forces of men, east or west, had no hope of actually killing Sauron if he had the ring, it litterally took an alliance of men and elves and they were didnt stop him until two literal superheros faced Sauron alone on the battlefield. They managed to mortally wound Sauron, but were both killed in the process.

If they did somehow manage to take Mordor, Sauron would have went elsewhere to rally his forces. It is extremely unlikely that that would happen. If Sauron gets the ring at the end of RoTK, he wins 10/10.


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

[User]
How can I teach myself to take a quality break?

I feel like I can't take a vacation without at least checking new papers, doing a bit of work, etc., without feeling guilty. I'm pretty burned out and dread when the breaks end even though I'm not even really "resting".
Is the only way to take a break to go somewhere without internet connection?

[Assistant] If you can't get out of town, then at least have a block of days when you're electronically *away*--set up an OOO message, then don't turn on the computer, don't check email, etc. It might even help to act like you're travelling *to* your home area: look at tourism & travel sites, then find stuff in your area that you don't normally do to do instead of being home (where the strange temptation to work might kick in).


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

[User] How accurate is the amount of a medicine in a pill (is 20 milligrams of Aspirin really 20 milligrams)?

[Assistant] What youll find when medicines are manufactured is a specification limit of something along the lines of 21.2 mg +/- 0.5 mg. This ensures that the consumer is getting at minimum the label claim without adding too much active ingredient (for both financial waste and accidental overdose reasons). The manufacturer will have validated a process that has been proven to consistently meet that specification, and the validation is subject to inspection by the FDA.  Samples will also be taken throughout production to make sure each pill is within specification.


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

[User]
[Marvel] Bifrost vs Tesseract

Now the way I understand the canon:
Tesseract = Space gem, which means it can teleport you anywhere.  Need to be somewhat sufficiently powerful before you can wield, handle its power (as with all the infinity gem/stones).
Bifrost = Asgardian technology, which can be rebuilt upon destruction, can also teleport you anywhere.

Which is better and why. And if the bifrost is of equal power to Tesseract.....does that mean with sufficient genius and technology one can recreate the effects of any infinity stone/gem?

[Assistant]
Bifrost can only teleport you from one of the 9 worlds to Asgard and back.

The Space Gem can teleport you from any place to any other place, including different galaxies and different univereses, dimensions, etc. We are talking about an infinite amount of planets and places here. And it is easily transportable, a hand held device, controlled by your thoughts. You can keep it in your pocket or mount it on your gauntlet and take it anywhere.

Biforst is a gigantic device that is stationary and controlled by a sword.

Another difference is that the teleportation with the space gem is instant. Travelling with the space gem is as easy< as going through a door. You just end up somewhere else. The bifrost takes time to load (everything must align frst) and then some additional time for the transport itself. in addition, the resulting beam stays for a couple of seconds before vanishing.

So, yes, the space gem is far superior in every way.


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

[User]
ELI5: If the planet is getting too warm, but space is freezing cold, why can't we just "vent" some excess heat into space?

Edit: Thanks for all your replies, this has been enlightening. I think we can close this post now though, there are only so many ways to explain the issue and I think I understand now :D.

[Assistant]
That's basically what the greenhouse effect prevents from happening.

Earth emits light (which carries some energy) away. However, more of this is getting trapped by CO2 in the atmosphere and, thus, less heat is getting transferred to space.

Beyond ensuring there are fewer greenhouse gases in the atmosphere, there's not much we can really do to control how much light the Earth radiates into space and there isn't really another mechanism by which the Earth, as a system, loses much energy.


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

[User] ELI5: .rar .zip .7z etc why are there so many ways to compress files? Is there a meaningful difference between them from the end users perspective?

[Assistant]
Most it is due to the history of data compression on the PC.

The first data compression programs appeared in the late 1980s, and through the 1990s there a number of competing standards, zip, rar, lha, and arj among them.  Zip emerged the winner and became the de facto standard for a while.

About that same time, the inventor of the zip format, Phil Katz started to have mental health and substance abuse issues, and the program was no longer being improved.  PC's transitioned from command line DOS to GUI Windows, and rar beat zip at making the jump by making WinRAR, the first widely used compression program for Windows.  This allowed RAR to get back into the race, and both WinZip and WinRAR remained popular.

However, the rar algorithm was patented, while Katz had opened the zip format to everyone.  As file compression started to become embedded into other programs, zip regained the crown once again.

Things didn't change much until 2008, when Igor Pavlov released 7zip.  It was a lightweight, but powerful program that handled all common compression formats, and offered a new format, 7z, with improved compression ration.

> Is there a meaningful difference between them from the end users perspective?

Not really.  WinZip and 7zip are free, WinRAR is commercial, but you can get fully functional "trial" version for free...no one ever pays for it except corporations.  The zip format is more widely used, rar might be what you have at work, and most people think 7zip is currently the superior program.


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

[User] Could you sequence the dna of cancer cells and then compare it to the persons healthy cells to locate the genetic mutation and then edit the dna of the cancer cells causing new cells to just be normal again?

[Assistant]
Yes and no.

Yes, as in technology to alter genes exists. It works quite well. We also know from most cancer species what genetic cause there is. So in theory you could alter the gene back to normal.

HOWEVER

The alteration of live human genome is not yet proven to be safe enough. You could cause other, maybe worse, random alterations.

Also, most cancer species build up a lot of different mutations over time to actually become cancerous. You would have to change a lot back to normal.

In addition, tumors have a lot of cells. To actually get to alter ALL of those cells is a challenge. Tumors are also quite heterogeneous so not every cell might need the same alteration to go back to normal. If you leave a couple of cells untouched the tumor may come back.

The now most researched option for gene editing is to cure hereditary forms of cancer. Then you have a gene alteration that already exists in your primal cells, which is easier to alter because there are way less cells you need to treat. You also don't have cancer yet, so there is likely only one mutation that needs to be "fixed". So that will be more in the field of embryonal selection and gene editing.


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

[User]
How did humans figure out that the ocean tides had anything to do with the moon?

Early humans certainly realized that tides occurs with predictable regularity. And they knew that the moon had a predictable, regular cycle.

But it's not nearly as obvious to the naked eye that there is a causal relationship between the tides and the celestial body hanging out in the sky.

When did we figure out that the moon causes the tides, and what proved it?

[Assistant] The tides tend to get stronger and weaker in about a two-week cycle, exactly half the cycle length of the Moon. You can follow that pattern over years or even decades, and it's always linked to the Moon. Full/new Moon: Large tides. Half moon: Small tides. Pretty obvious that they are connected somehow.


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

[User]
ELI5 What is the purpose of continuously spinning a lasso before throwing it?

Why spin it a dozen times before throwing? It seems like you could just spin it once and throw it and it would have the same effect.

[Assistant] Spinning it keeps it wide open and keeps a steady momentum so you can be ready to throw at any moment. Because you're typically working with a moving target, you don't always know, in advance, exactly when you're going to throw it, and you need to be ready as you're "closing in" on whatever you're trying to lasso.


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

[User]
How do migratory birds know which direction theyre going?

HOW?!?!

[Assistant] Some animals sense magnetic fields.  Others follow the stars.  Of course, it is pretty easy to tell what direction you are headed just by noting where the sun is.  In the morning your shadow points west.  In the evening your shadow points east.  At noon your shadow points north (in the northern hemisphere)


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

[User]
The hazard symbols for highly flammable and oxydizing are very similar. Why is the oxydizing symbol so similar and what does it visually represent?

I am very sorry for such a boring question, but I'm struggling to find why the Oxydizing symbol is the way it is. I need to explain what is happening in the image so I can seperate it from the Highly Flammable symbol.

[Assistant]
HAZMAT tech here.

The Flaming O oxidizing agent symbol is there because the substance is not a fuel, but an Oxidizer. The presence of Oxidizing agents can greatly accelerate the combustion of other materials, or even cause things that are not normally flammable to burn. It also broadens the flammability limits of most substances by lowering the LFL and raising the UFL. In other words, it becomes much easier for materials to burn at lower temperatures and at a wider range of air/fuel mixtures. A small oxygen leak, for example, can turn what would otherwise be a simple structure fire into a very intense, and possibly explosive inferno. Even a slight increase in the oxygen content of air above its usual 21 vol % will greatly increase the rate of oxidation or combustion of many substances.

And oxygen isn't the only oxidizing agent that can do this.

For example. Nitrous oxide is an oxidizing agent. By itself, it will not burn. But it will gladly support combustion in the place of atmospheric oxygen.

Firefighting techniques for Oxidizing agents are different from flammable agents, since if you extinguish the fire, the oxidizing agent is still there, ready to restart the fire at a moments notice to possibly explosive effect. Certian oxidizing agents can even catch water and concrete on fire.


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

[User]
[Spider-Man/Marvel] What exactly does Oscorp do?

I ask this because it seems to vary depending on the interpretation and they often appear to work on a wide array of vastly different sciences, usually dealing with chemicals, genetics, military tech, or some combination of those.

In the 616 universe, it seems like they're primarily a chemical company.

In the Ultimate universe, they seem to be a genetics company

In the Raimi movies, it seems like they deal with military technology and chemicals.

In the first Amazing Spider-Man, it seems like it's almost entirely genetics while the second one has them creating exo-suits and power plants. If you count the game as well, they also make robotics and cellphones.

The 2018 game seems to be the same as the Amazing Spider-Man where they do research on genetics, general tech, weapons, medicine, robotics, and many other things.

Basically what I'm asking is what kind of company Oscorp is overall?

Are there companies like this in real life that just dabble in all sorts of vastly different sciences? What would you call a company like this?

For example, Wayne Enterprises in the Nolan films (and many comics) is a military technology company, hence why Bruce has access to military grade tech as Batman.

Obviously, from a real world perspective, Oscorp is the generic evil corporation that does whatever science the writers need them to but it always seemed odd to me that this single company does like every type of science imaginable.

[Assistant]
>Are there companies like this in real life that just dabble in all sorts of vastly different sciences?

Yes, there are plenty IRL companies like that. Research about General Electric or Siemens. You would be amazed at how many advanced products they have

EDIT: About the name they are either called conglomerates or "Industrial goods manufacturer" (opposed of consumer goods)


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

[User] ELI5: Why is testicle pain more painful than pain in say the arm or leg?

[Assistant]
There are two good answers here, but the full picture needs to put both of them together.

Get yourself two toothpicks. On yourself without looking or on someone else without them looking, test to see how far apart they have to be for you to realise it is two toothpicks and not one when you press them against the skin of your fingertips. Try this again with the skin of your upper arm/thigh etc.

Different parts of your body are better or worse at detecting touch depending on the density of touch neurons, and subsequently a smaller or larger portion of your brain is devoted to processing those signals.

Pain receptors are different from touch receptors but the principle is the same. More pain receptors in an area will mean that you will be able to feel more pain in that area. Hence why there are more pain receptors in places that you need to survive and procreate.

 There is strong evolutionary pressure to have lots of pain receptors on your testicles, as trauma to them will screw up your chances of having kids. Therefore, making trauma to your testicles unpleasant makes you more likely to protect them, and makes your genes more likely to survive.


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

[User] ELI5: Why is university called "college" and college called "community college" in the United States?

[Assistant]
The meaning of the term 'college' varies a lot between countries.

In Canada, a college is sort of like a technical or trade school that you attend at around age 18. It's a post-secondary education path similar to university but the material is more practical/hands-on and specialized. The term 'college' is also sometimes used to refer to schools within a larger school (e.g. a college within a university).

In the UK, the term college usually refers to a bridging school that students attend around the age of 16. It may help prepare and qualify students for post-secondary education (e.g. at a university) once they reach age ~18.

In Australia, the term college may be used as a more general term for many different types of schools, including schools that are primarily geared toward teaching children under 16 years of age.

In the US, the term college basically just refers to any post-secondary institution of education whether that be a university, a technical/trade school, a 'community college' or what have you. Like Canada, the term 'college' is also sometimes used specifically refer to a 'school within a school' at universities that are made up of multiple colleges.


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

[User]
Why do YouTube videos seemingly "unbuffer" themselves when I scroll back on a video?

Surely if part of the video is buffered, it shouldn't unbuffer itself? Sorry, forgot the ELI5 in the title :(

[Assistant]
It's part of the new way videos are rendered.

Youtube used to waste huge amounts of BW, because a large percentage of people didn't finish watching videos, so all this traffic was putting unnecessary strain on their infastructure.

Some months ago they changed the way they do things, now each video is broken into segments and only the current segment is buffered (so if you leave a video paused it won't buffer past the current segment like it used to)


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

[User]
Eli5: Why do hunger strikes work?

Ive never understood this. Isnt it in the interest of people in power or people jailing you to watch you starve to death? Yet in prisons and detention centers, its always the go-to. Why do they work?

[Assistant]
First of all, they usually dont.  You hear about hunger strikes occasionally but how often do you ever hear a follow-up story about the person being released and exonerated or the policy in question being changed?

Vladimir Putin doesnt care if you starve to death, and western governments will drag you off to the medical ward and stick an IV in you if you hold out that long.

People do them because thats the only protest they can realistically do if theyre already in prison, and enough coverage and enough supporters *outside* prison can cause a larger protest movement to develop.


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

[User] Why is there so much salt in the oceans and seas? How did it get there?

[Assistant] The salt in the ocean is basically minerals washed out of rocks from rain, rivers and the ocean ground itself. It concentrates more and more because evaporated water leaves the salt back, builds clouds, and if those clouds happen to rain over mainland, the water washes even more salt to the ocean.


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

[User] [Game of thrones] what happens if caitlyn never frees jamie ?

[Assistant] Karstark would not have murdered the Lannister kids and instead might make an attempt at killing Jaime, if not Tywin would likely secure some sort trade for his favourite heir eg. Sansa or at least something to bargain with. Come to think of it the Starks gained nothing from freeing Jaime for free all it did was undermine Robs war.


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

[User]
[Star Wars] How DOES someone join the Rebel Alliance?

Like if I was a surviving Jedi and I managed to buy a starship and attacked multiple Imperial basses with a small crew would the Alliance find a way to contact me and let me join?

[Assistant]
The word "Alliance" is significant here. Up until shortly before the Battle of Atollon, there was no formal high command for the Rebellion - just dozens or hundreds of small-scale local insurrections and uprisings, ranging from a handful of angry thugs murdering off-duty Stormtroopers in back alleys to full-sized fleets defending their home systems from Imperial authority. These groups gradually got in contact with each other and built up ties of cooperation and support, eventually coordinating on strategy and planning allied strikes against the Empire.

So the first step to joining the Alliance is to find your local rebellion - or, if there isn't one already, to start one. Depending on exactly when this is happening, it may be years before the Alliance gets in touch, or your local cell may already be part of something bigger.


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

[User]
C-string

What is a c-string in c++? How is that different from just a string?

[Assistant]
There are two common ways of representing strings.  One is to store a length along with the characters, and the other is to say the string goes until you hit a specific character, usually a NUL, which is represented in C as \0, and has the numeric value 0.

At the time the C language was invented, memory was really expensive, and prefixing each string with a length was a waste of memory compared to adding a single character at the end.  If it's 1 byte, you can only have strings up to 255 characters.  If it's 2 bytes, you're wasting 1 byte per string, and you're limited to 65535 characters.  And if it's 4 bytes, you're wasting 3 bytes per string.

So C was given a NUL terminated string as the built in representation.  Pascal was given strings which store the length prefixes.  The two competing standards were commonly referred to as C strings and Pascal strings.

When C++ came around, it was given a std::string class, which stores the length along with the string.  Since C++ was built on top of C, and you can use C style constructs just as easily as C++ classes, when you're talking about strings in C++, it's important to differentiate that a given string is a std::string or an old-style NUL terminated string.


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

[User]
how do pharma labs choose the name of the meds they produce?

Do they follow any naming rules? from my point of view, if some names give a hint at what the medicine does/cures, most of them just look like someone found a funny name. Is there any existing rule for that?

[Assistant] They can pretty much give it whatever *brand* name they want, and generally go with something that their marketing folks tell them sounds good and conveys the effect of the drug (eg lopressor to lower blood pressure).  The *generic* names generally follow a set of nomenclature rules where a certain suffix denotes a certain class of drug - for example, beta blockers end in -lol (eg metoprolol, atenolol, labetalol), ACE inhibitors end in -pril (eg lisinopril, captopril, ramipril), monoclonal antibodies end in -mab (eg abciximab, inflixicimab), etc.  So often even if you don't know what this particular drug does, you can guess what class it is in based on the name.  Of course, there are always exceptions (for example, acetaminophen, the generic name of Tylenol, is just a shortened version of the IUPAC name, N-acetyl-p-aminophenol).


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

[User] ELI5: how does squinting help you see better?

[Assistant]
Imagine an eye without a lens or iris. It would just allow light from any direction to fall on any given part of the retina and there would be no way for your brain to figure out an image from that. Light from a ball in a particular direction would be all mixed up with light from trees, houses, etc. So there needs to be some method of "sorting" incoming light so that light from a given direction only falls on a specific part of the retina, and light from other directions is excluded. That is what a lens does.

But there is also another way to do this. Imagine for example there is an infinitely small hole through which light must pass to reach the retina. Light tends to travel only in a straight line (ignoring things like reflection, refraction, etc) so since light can only pass through this tiny hole there is only one straight path to any given portion of the retina and this effectively sorts incoming light in a similar fashion to a lens. An arbitrarily small hole is an arbitrarily perfect lens, but the down side is that it would also allow an arbitrarily small amount of light through (and your retina is only so sensitive). But this does mean that tiny holes can be effective lens substitutes provided intensity of incoming light is sufficient to form an image. A simple camera design called a "pinhole camera" uses a hole made by a thin pin to stand in for a lens.

Squinting then helps to supplement insufficient focus by narrowing the aperture of the eye and making a more clear image at the cost of making it dimmer.


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

[User]
[StarWars] If Anakin is never discovered does the emperor end up ruling the entire known universe and eliminate all Jedis?

His plan seems well under way even before Anakin gets involved.

[Assistant]
Depends. Technically Anakin was a totally coincidental thing for Palpatine, he was still going to work on taking over the galaxy regardless of if he had Anakin at his side or not; the Invasion of Naboo was the first major step in the plans for the Clone Wars.

If Anakin isn't discovered by the Jedi, then either he isn't the Chosen One, in which case he's irrelevant anyway, or through Palpatine's own actions and the Force working its will, he'd still eventually come around and destroy Palpatine.

Also, Jedi, not Jedis for plural, and galaxy not universe, as they haven't expanded beyond the one galaxy and a few smaller "satellite galaxies."


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

[User] ELI5: When you turn on the turn signal in a car, why does it sound like the clicking noise is alternating between a higher and lower sound? Is it really alternating or is it just the brain creating an audio illusion?

[Assistant]
Turn signals originally were controlled by electromechanical relay under the dash. The clicking sound was that of the relay opening and closing based on a timing circuit. The slight differences in sound was the difference in sound made by the relay when it was opening or closing.

Modern cars don't really need the mechanical circuit. The could be made completely silent by using different components (physical relay may actually be cheaper though). However, people have come to expect to hear the sound of a turn signal. Some car manufactures will actually tailor the sound to how they want. Along, a real sound is a good reminder that you have the turn signal on (or left it on by accident).


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

[User] ELI5: How come if you stay up late because you don't feel tired you will still feel exhausted the next morning?

[Assistant]
A few reasons. Easy one is that just because you didn't feel tired doesn't mean you aren't tired. Our bodies are sometimes shit at telling our brains what they need.

Another possibility that comes to mind is based on sleep cycles. You typically go through two sleep cycles per night of about 3-4 hours in length. If you wake up at the end of a cycle you feel great. If you wake up in the middle of a cycle you feel shit. So, on a typical day you get say 7 hours sleep, wake up after two 3 1/2 hour cycles and feel great. Then you stay up a couple hours and only get 5 hours sleep. Now you've had 1 1/2 cycles, woke up in the middle and feel shit.


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

[User]
ELI5: How does acid stay in a persons stomach after death and not begin to immediately eat away at the body?

 Not that your physical condition would be a concern at that point, but I wonder how the stomach doesnt immediately loose the acid into its surroundings with everything shutting down.

[Assistant]
Technically it does start eating away at the body when you die. It always does, which is why our stomach lining is constantly replenishing itself.
However, stomach acid and bile aren't so potent that they'd burn a hole right through you, so our thick stomach walls get eaten away slowly in time with normal anaerobic decay and such.


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

[User]
How does microwaving a sponge sanitize it?

Are you essentially boiling it clean?

[Assistant] Well, the idea is that a wet sponge heats up quickly in the microwave and hits boiling point and kills some/most of the bacteria, but the dirt is still in there and its still dirty. Microwaving it isn't the same as buying a new one. If its filthy just toss it.


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

[User]
Would radioactive antimatter have anti-radiation?

Since we're able to make antimatter of various elements, if we made antimatter of a radioactive element, how would what it radiates differ from normal radioactive material?

[Assistant]
Sure.

If you take the antimatter counterpart of a heavy nucleus which decays by alpha decay, the antimatter version will decay by anti-alpha emission. Same goes for any other kind of cluster/nucleon emission.

For beta decay it gets a little tricky, because even normal matter emits antimatter when it beta decays (either positrons or antineutrinos). So anti-beta decays would also emit both matter and antimatter.

And for gamma decay, the photon is its own antiparticle, so theres no distinction between a photon and an antiphoton.


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

[User]
If we had a telescope strong enough to see the surface of a planet 5 lightyears away, would the events be taking place clearly in real-time, effectively looking at the past?

If so, we should put a giant mirror in space that faces us so we can look at it and view our past.

[Assistant]
You are correct. If we had a telescope strong enough we would be "looking into the past" of another planet.

Regarding your mirror idea, if we placed the mirror 5 light years away, flying at the speed of light we would be able to put the mirror up in 5 years, and have to wait another 5 years for the light to reach us again. We could only see 10 years back, as far back as the shuttle leaving to put up the mirror.


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

[User]
How to get the most out of adjuncting? When is it time to stop?

Hi everyone -

I teach full time at a two year school, and I've been adjuncting at a university while I search for a tt line at a SLAC (I like my full time gig enough, but I'm afraid that if I don't teach at a 4 year school at the same time, it could hurt my marketability for the kind of job that I ultimately want). I've been teaching an intro class each semester for the past two years. I really enjoy it, but I'm not sure how I an get the most out of my experience there, and when it's time to walk.

My chair has hung a carrot on a string with me about teaching a course in my specialty area since I started. He was "trying me out" with intro, with the promise of teaching my specialty - but when it's time to make the schedule, he always has a reason not to put me down for the upper level specialty course (would students really take it, this other department might get upset, our enrollment is down, etc). I'll finally be given a course for majors in spring 2018, but it's only because one of the full time fac is tired of teaching it.

I've also been strung along about becoming ft there. "We're getting a full time line next year" followed by "If only we had a line I would hire you here". Naturally, the full time line hasn't appeared. I feel like if I'm mainly teaching intro, it's not a good use of my time.

My main goal is to leave there with great student evals, and a solid recommendation from the chair. Is there anything else I can do to get the most out of the experience? Also, is it likely to be hired in full time as an adjunct should a line appear? I hear it's nearly impossible for this to happen.

Also, I'm keeping up with publishing, but not nearly at the pace that I would like to in order to.

[Assistant]
Wasn't it Chris Rock who said, "There's no sex in the Champagne Room"? Well, there's no TT line at the end of adjuncting. Don't think, "I'll make them like me and they'll want to keep me around" and bust your ass accordingly. The chair could love you, but that doesn't mean the dean and assorted higher-ups even know who you are. They're the ones who are going to approve the search and the hire after that. For all you know, the dean hates the chair and has been holding out on giving the department a chance to do a TT faculty search. Or, they'll get some stupid idea in their heads that your evaluations are wonderful and you've done the grunt work, "But what about the research?" or some such thing. And when some hotshot new PhD comes along, they'll drop you (and then you can laugh ruefully when said hotshot gets the job and takes off a year later for ivy-covered pastures).

Don't listen to them when they say this stuff about "if there were only a line...." They are using you, and this kind of stuff is unconscionable. Hope for a good letter of rec, and get out ASAP.


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

[User]
Can we learn things while we sleep?

I see videos on YouTube that are a few hours long and are meant to be listened to while sleeping to help learn the language.

Does watching these videos help do anything while sleeping?

[Assistant]
It is pretty unlikely that you have the capability to learn while sleeping like that. It has been theorized that your brain spends your time sleeping to unpack the information from the day and store it, so it may not be able to learn additional information because it is already at capacity.

However, this is a subject of study and there are many of us that would like to be able to retain, process and internalize knowledge both faster and during periods of sleep.


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

[User]
CMV: Government officials should be under oath when performing official duties.

Recently a Trump ally Roger Stone was convicted of lying to Congress while under oath.  Im no Trump fan, didnt vote for him in 2016 and wont vote for him in 2020.  However, Congress can freely get on TV, radio, and the internet everyday lie and speak in half truths with very little consequences.   Yet when a citizen has to speak to congress, they must  do so under oath and risk committing perjury if they lie.

My solution to this problem is simple.  Anytime an elected or appointed government official is performing their official job duties, they should be considered under oath.  This way if they are caught citing  fake news, conspiracy theories or trying to pump up their base they can be held equally accountable for it.

[Assistant] Presidents and other governmental officials need to be able to lie during the course of their official duties. Denying knowledge of military or intelligence operations, not disseminating classified information, etc. Forcing them to be under oath would make it a trivial matter to deduce things.


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

[User] What language in your opinion has the best ecosystem nowadays (including frameworks, IDEs etc.)?

[Assistant]
Java. Very mature ecosystem, powerful build/test tools and without the fracturing you see in python for instance where theres a million ways to package and manage dependencies. Libraries/frameworks are incredible, like Spring.

And with JVM compatible languages like Kotlin you can get all those advantages but with a modern syntax thats actually nice to write.


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

[User]
[Marvel] If there is a molecule man in every universe, how come they don't just control the multiverse?

So for anyone who doesn't know, the molecule man is a reality warper who's powerful on a multiversal scale, but there's one in every universe. So how come he doesn't just join forces with the other molecule men and take over the multiverse?

[Assistant]
Owen Reece is no Victor Von Doom.

He's just a normal guy with godlike power. He's tried the supervillian thing but he lacks the ambition, ruthlessness or frankly basic competence needed to use his powers to their full advantage- that's why he keeps getting beaten.

Basically, imagine if *you* got incredible cosmic power, right now. Would you track down all the alternate counterparts of yourself and make war upon the very foundation of reality itself? Or would you do something like sit in bed manifesting cake into your mouth?

Because the molecule man is far closer to cake end of the spectrum. He has the potential to rule the multiverse, but that's far from the only potential he's wasted.


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

[User] ELI5: Why do image file sizes differ if the lens and camera are the same?

[Assistant]
Images are compressed. Compression depends on the contents, some content can be more easily compressed than other content.

This is because compression works mainly by removing repetitions in the data, so if the data has lots of repetitions (for example if the image is just a big black square) then it is easier to compress, resulting in a smaller file.


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

[User]
ELI5:Why are lenses round but the camera sensor and resulting image square?

For SLRs the attachable lenses are circular, yet when you look through the camera, as well as the image taken, the shape is rectangular.

[Assistant]
When making lenses for a camera, it's difficult, if not impossible, to achieve a uniform distortion of light throughout a rectangular lens. A circle is very uniform and makes all refraction of light through the lens the same. Rectangular image sensors are also easier and more cost-efficient to make than circular ones, assuming you'd even want a circular sensor.

Basically, it's the cheapest and easiest way to manufacture.


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

[User]
ELI5 what does "doing taxes" in the US exactly mean

except for americans, ive never seen or heard of people. average joes.. from other countries "sitting down" to "do their taxes". where I'm from there are no taxes "to be done".. unless if you have a business in which case you hire an accountant

so what exactly do americans do?

[Assistant]
So the real reason people do their taxes is because in the US you usually don't pay the 'correct' amount on each paycheck you receive. You are allowed to essentially determine what the Fed withholds from each paycheck but at the end of the year you can use software to calculate exactly how much you owe. If the Fed had taken more out of your income than you owe, you receive money back. If they took out less, you owe them the difference.

A lot of people have the government withhold a little more than they will owe so that they get a bit back when they file.


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

[User]
Mathematical fate; Possible?

Let's say you had a bouncy ball and a cardboard box. Once you threw the ball into the box, is the trajectory of the ball not predetermined? Assuming a finite number of particles in the universe after the big bang, after gravity and strong nuclear force split from this mass as laws, would the trajectory of each particle not be mapped from the onset? I've searched the web and cannot find any information on this subject. If you take this information to be true, even the electrical impulses in the human brain would have been decided far in advance. A little help on this topic from someone with the background in astrophysics or cosmology?

[Assistant] In terms of Newtonian physics you're pretty much right yes, if you have enough information about a system you can predict where it will end up, though for a complex system you would need a vast amount of information. Quantum physics buggers that up though, by throwing various uncertainties and random variables and events into the mix than can throw your prediction off.


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

[User]
[Marvel/DC] Is hells kitched compairable to gotham as far as corruption and general shittyness? Also does the Punisher operate out of hells kitchen because he runs into Dare Devil A lot?

I know punisher operates where ever when ever but I started reading the punisher comics from the start a few weeks ago and they have run into one another a lot.

Hell's Kitchen***

[Assistant] Hell's Kitchen is probably a good comparison to DC's Gotham but on a smaller scale. As per Punisher and Daredevil, you will find a lot of the heroes have questionable feelings about Punisher, largely due to how he fixes crime. Somewhere like Hell's Kitchen is a breeding ground of crime and a perfect place for Punisher to find evil.


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

[User]
[MCU] How did the U.S. Government (specifically SWORD) get their hands on Vision's body after Infinity War?

So Vision died in Wakanda. When the mind stone was ripped from him he died and his body was left there, in the Wakandan forest, after the snap.

What I don't understand is why would the Wakandan government let a foreign entity (especially the United States government) just take BILLIONS of dollars worth of Vibranium that's forged into literally one of the most advanced sentient weapons in the universe?

Was Vision considered a US citizen or something? Vision really wasn't born per se, he was created, and he's not even a human either. I would imagine it's probably a gray-area about whether or not vibranium synthezoids have human rights. I mean my guy is literally just code, magic rock, and vibranium.

Iirc, Vision also didn't sign the Sokovia Accords which rules out any article in it about what should happen to Avengers after they die because it doesn't apply to him.

I feel like if anything, the body of Vision should have gone to Tony and/or Banner. Technically speaking, Vision is the property of Tony Stark and Stark Industries because practically everything about Vision was created by them. Visions original AI is Jarvis, created by Tony Stark, Visions body was created by Stark and Banner in AOU, really the only thing that made Vision "human" was the mind stone. And that was gone. So I think you could make the argument that the body of Vision legally belongs to Tony or Bruce. And, if we follow that line of thinking, I think it is HIGHLY unlikely that they would just hand over Visions body like that. They're pretty smart guys.

AND, if we wanna get even more technical, the material that Vision was made of is Vibranium, which can really only be found in Wakanda. So I think the Wakandan government could say something like "The body was made using resources only found in our country, we have the right to handle those resources" or something like that.

My only other thought was that if Vision made some sort of last will and testament. Like in it, it said that he wants himself to be dismantled so his powers can't be abused or whatever. But I feel like I can still reject that theory because if that was the case, why wouldn't the Wakandan government just dismantle him themselves, why would they turn him over to a secret division of the US military with literally no assurance that he would be properly dismantled and disposed of?

Idk, what do you all think. It was the one thing that really confused me about WandaVision and I thought I'd finally make a post about it. Any thoughts would be great!

[Assistant]
In terms of how the body physically got out of Wakanda, once the battle ended there's a good chance that the surviving Avengers picked him up and tried to take him back home in the hope that Tony was A) alive and B) could do something. The Wakandans are distracted with the loss of their king, and were willing to deal with Vision as an individual and not a walking pile of contraband (he ce their willingness to help him when the Avengers first arrive instead of scrapping him), so they likely just let them walk off.

Then, later, Tony rage quits the team and it becomes clear that Vision is beyond saving. You can't just bury a body made our of the most precious material on Earth, so they hand him over to government custody instead.


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

[User]
Why does closing one eye help the pain when it's really bright out?

Shouldn't it be equally bright in each eye?

[Assistant]
You "feel" bright light when the iris contracts and makes your pupils small. This is why photophobia is a common symptom of corneal abrasion and viral keratitis, and why browache results from pilocarpine drops that force the pupil to shrink.

When you cover one eye, you reduce the stimulus to pupil constriction. The pupils still constrict (even in the closed eye) but the stimulus isn't as intense, so the response is not as "painful".


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

[User]
[The Matrix] Why are Agents missing shots?

The Agents are created by the machines for the sole purpose of policing the Matrix. They're shown to have cheat-code levels of flexibility in terms of speed, in terms of durability, in terms of awareness so long as they're wearing their earpiece...

... so why do they miss when they're shooting guns? Especially at stationary targets like when Neo is manning the minigun in th helicopter. We can write a script to auto-headshot in videogames, but Agents can't bullseye anything they point at?

[Assistant]
Morpheus states in the first film that the program has bounds, and the agents are limited by those bounds. They can be stronger and faster, but they are limited. I'd take from this that they're susceptible to making errors as much as any human in the Matrix would be. They certainly demonstrate poor decision making skills and poor judgement, demonstrating fallibility.

Regarding game hacks/exploits; remember, in terms of canon, you'd be writing code for a game *inside a simulation*. IMO these 'sub-programs' are able to be run in video games, because they still fall within the limitations of the wider simulation. If anything knowing video games can be hacked enhances the illusion.


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

[User] ELI5: Why does the sweat from our underarms smell different then that of our feet? Isn't the same sweat?

[Assistant] No, it's not the same sweat. Armpit sweat comes from apocrine glands, and contains higher levels of fat and protein than sweat from eccrine glands, which is where regular sweat comes from. Body odor comes from bacteria breaking down the fat and protein in apocrine sweat.


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

[User] ELI5:Why don't car manufacturers make all cars as visually appealing as Ferrari's or Lamborghini's?

[Assistant]
There's a lot of reasons but I'll try to come up with a shorter list -

1.)  form follows function.  There's no way to make a car that looks like an exotic sports car that can still haul 5+ passengers and carry lots of cargo.

2.)  platform sharing.  many vehicles in production today share platforms, engineering, chassis designs, etc with other models.  Ferrari's and Lamborghinis have bespoke chassis (although yes the Gallardo does share it's platform with the also exotic Audi R8).  Carmakers want to design a platform that is as versatile as possible and able to used in as many different vehicles.  Toyota uses the same design architecture (in various forms) to underpine the Camry, Highlander, Avalon, Venza, Lexus ES, and Lexus RX.  Nissan is unique in having designed a platform that can be used on everything from a sports car (370z) to a SUV (Infiniti FX) to a large luxury sedan (Infiniti M).  Then again, the 370z does not quite have the same stance as a purebred sports car like an S2000 or Boxster, and the FX is also just about the most car like SUV you'll find.  When you compare the Mustang, Challenger, and Camaro, one key reason the Mustang is several hundred pounds lighter is the Camaro and Challenger are essentially two door sedans (the Camaro sharing it's platform with the late lamented Pontiac G8 and the Challenger with the Charger), so they are heavier, whereas the Mustang does not and is designed to be a sports coupe.  Common architectures/platforms/chassis designs require compromise, and that's not something Ferrari or Lamborghini have to really do.

3.) not everyone likes the look.  for some people, their car is no different than their washing machine - it's an appliance.  they want something bland and simple that gets the job done.  making a bland looking car is also the least offensive and polarizing, and therefore more likely to have the broadest appeal.  People are far more likely to buy a car who's styling has no effect on them than one that they find ugly.

4.) a carmaker may have it's own design language that it is trying to convey.  A Mercedes or a BMW have their own distinct looks that identify the brand, and styling one of their cars to look like a Ferrari or Lamborghini wouldn't look right.  Brand identity is something very important to many carmakers, and they try hard to make their cars recognizably theres.  Look at the grill Ford is now putting on all their cars, or Cadillacs vertical headlights and tailights.  Same goes for muscle cars like Camaros, Challengers, and Mustangs.  They just wouldn't look right any other way.


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

[User] ELI5: Why are different sleeping positions comfortable for different people? Does it have to do with how we were comfortable in our mother's womb?

[Assistant]
It definitely isn't related to how we were in our mother's womb, but many factors can influence how people are comfortable. For example many women find a pillow between their legs is more comfortable as their hips are wider than men's and the spacing keeps their legs comfortable on their side. Why their side? Larger breasts can put weight on their chest so offloading it by turning to the side makes breathing easier.

Men tend to have wider shoulders which can make laying on their side less comfortable as it bends the spine more. All these are just examples though as it comes down to personal preference.


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

[User] ELI5: What is physically preventing a dead person from being brought back to life?

[Assistant]
Cells in the brain start to die from lack of oxygen that comes from the blood.   Once those cells are gone,  the is no more 'you'.

Physical processes in the body can continue (coma) or be forced to continue with machines,  but once the brain starts to die there is no going back.


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

[User]
ELI5: Why does the American public value the ability to possess a gun so highly?

Hi, I'm from the UK in my early 20's and am completely naive on the subject of gun's in general and gun legislation in America.

Edit: Thank you for all your answers!

[Assistant] America was formed from a country that revolted from a monarchy which restricted freedom through armed suppression of the population. In an attempt to prevent that ever happening again the right to bear arms was ensured to every citizen.


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

[User]
CMV: I paid off all $30k in student loans and I dont wish it on anyone.

I worked my ass off to pay my undergraduate student loans off and I dont think this should be forced on anyone. The government should relieve all student debt, immediately.

I have a wonderful degree with a professional job and a living wage. I wouldnt have any of this had I not gotten substantial help from my family when I had medical issues. Nor if I did not split rent with a partner who works full time. Nor if I did not get a research scholarship covering my graduate tuition. Nor if my grandparents didnt give me a free car. But thats me, and Im privileged as shit.

I dont personally feel I lose out if someone else gets their loans relieved, and the net benefit to society would be immeasurable. I dont understand why so many people in my position feel the need to simp for Navient.

Id be paying student loans off too if my hospital stay had bankrupted me, if my ancestors had been black and not given the option of homeownership, or if I was single and paying full living expenses.

[Assistant]
If all we do is pay off peoples loans without doing anything else, the impact on society would be immeasurably bad.  The current system is broken. Tuition is too high, the loan system is predatory, there is no pressure on students to make wise decisions, just pressure to get money and get the degree. Students should be encouraged to plan financially for a degree that can be paid off by the career it enables.

We need to fix the system to efficiently allow people to affordably get a degree that enables their future. If we just paid off everyones debt without doing that we are just continuing the cycle. Once a better system is in place, then you can (and should) address the existing debt.


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

[User] I have recently heard that astronomers have found an "exomoon". I am quite scientifically illiterate so what exactly is an exomoon and how could it affect us on Earth?

[Assistant]
A planet in a solar system other than our own is called an exoplanet. Similarly, an exomoon is a moon in another solar system (and orbiting an exoplanet).

These things are so far away that they don't affect Earth at all. But the reason that the discovery is interesting is that exoplanets are already difficult to detect, but exomoons are even harder to find, so finding one (or even a "candidate") is quite an achievement.


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

[User]
[DC] Where do these villains keep hiring goons?

In Gotham for example, the Joker gets new goons just about every time he goes about doing his thing, he's even responsible for some of them dying.

Where do they find these guys?

[Assistant]
I suspect there's a pool of ex-cons who are down on their luck and have few legitimate employment options. They float from gig to gig, henching for different villains between stints in prison, rehab, and attempts at "going straight".

Recruitment is largely by word of mouth. Prisons and gangs have their own informal communication networks.


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

[User]
[DC]Would The Flash disappearing into the Speed Force cause the creation of the Justice Lords?

In the JLU episode 'Divided We Fall', The Flash pushed himself further than he'd ever gone before in order to separate Brainiac from Lex Luthor. In doing so he started to fade into the Speed Force.

In the episode 'A Better World', we find out that the Justice League became the Justice Lords after Lex Luthor killed The Flash. If The Flash had fully faded into the Speed Force, would that have had the same effect has Lex outright killing The Flash?

[Assistant]
Maybe.

Who can say? Timelines and multiple worlds being what they are, it seems entirely possible.

On the one hand, maybe it's not enough to say "Dead Flash = Justice Lords." Luthor killing the Flash is bound to cause more resentment and rage than Flash sacrificing himself for the greater good.

On the other hand, maybe it's simply the continuing presence of the Flash that kept them in check. His light humor, his power, his friendship. The other members of the Justice League tended to be a bit... stoic. They were teammates, they cared for each other, but no one really had the levity of The Flash.


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

[User]
Regarding the physics of lightning and electricity.

What causes a bolt of lightning to form so rapidly, in the order of microseconds, when the drift velocity of the electrons carrying the charge is in the order of meters per hour? Furthermore, how does such a high potential difference equalize so rapidly if the electrons are moving so slowly?

[Assistant] In general, when current flows, the electrons that come out at one end aren't the same electrons that went in at the other, they're electrons that were already in the conductor and were pushed out. You can think of it like a tube completely packed full of marbles, but open on either end. At one end of the tube, you push another marble in, and it pushes the marbles in front of it, which push the marbles in front of them, down the line until it gets to the other end, where one marble falls out. None of the marbles were moving very quickly, yet the signal was transferred almost instantaneously.


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

[User] What works of Kierkegaard should I read to fully understand the Knight of Faith?

[Assistant]
Definitely *Fear and Trembling*.

I'd also recommend reading the works of Kierkegaard and Nietzsche back to back for the stark contrast it provides. Kierkegaard is unabashedly devout while Nietzsche is vehemently atheist, and yet, they arrive at many of the same conclusions.

Also, if you're someone who struggles with the religiosity or nihilism of either author, you can read them alternatingly for the same effect, as a sort of counterpoint to one another.


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

[User] ELI5: Why arent dominant traits always more common than recessive traits?

[Assistant]
Dominant traits aren't preferentially passed along between generations, they just express more strongly if they are passed down.

If a dominant gene is rare, it may continue to be rare unless there's some selective pressure killing off animals without it.


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

[User] ELI5: why our body temperature is 98.6 degrees but 98 degree weather is too hot for us.

[Assistant] Our optimal temperature is 98.6 degrees, but metabolism produces heat.  When the flow of heat away from the body isn't sufficient to keep the temperature at 98.6, you begin to sweat and feel uncomfortable.  At 98.6 degrees of air temperature, there will be no heat flow away from the body unless you begin to sweat.


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

[User]
Are there really "schools" of economics anymore? Referring to "Austrian," "Keynesian," etc.

Do economists still use the labels "Austrian," "Neoclassical," or "Keynesian" anymore? I never hear economists use or refer to these terms, they sound old-fashioned, and seem pretty unscientific to me. How can you be a dispassionate, analytical scientist if you acknowledge that your work is guided by an ideology?

[Assistant]
These groups technically still exist, but that's mostly because of a pretty small number of fringe economists as well as many more people who cling to the ideas of these schools because they find them ideologically appealing.

As far as actual academic economics is concerned, these schools were basically "merged" and their bad ideas thrown out so that what exists nowadays is essentially just "the mainstream". Economists don't think in schools of thought any more unless they want to deliberately be an "alternative", and those people are usually not particularly credible. The mainstream accepts everything that's up to scientific standards and just as good or better at explaining the world than the current status quo.


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

[User]
CMV: The Jan 6 commission will not hold anyone accountable. It is all political theater.

It seems like the people that need to hear the commission are the ones least likely to tune in. At best theyll get cherry picked clips by their favored media source and have media personalities shape their outlook.

We saw during the impeachment trials that subpoenas can just be ignored with no repercussions. Weve seen countless senators and reps break the law. Weve seen people in power threaten politicians (Flynn revisiting an AR and saying maybe hell find someone in Washington.)

Nothing gets done. No one is held accountable. This commission will be no different.

[Assistant]
> We saw during the impeachment trials that subpoenas can just be ignored with no repercussions.

That was only possible because the president (Trump) claimed executive privilege on literally evryrhing. Seems pretty unlikely that Biden will stonewall his own partys investigation into a MAGA attack to overturn his own presidency, no?


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

[User]
CMV: Technological Improvement is the only Practical Solution to Addressing Climate Change

Nobody, or rather not enough people are willing to make sacrifices to their convenience or quality of life or their money to make a noticeable impact on climate change. I am one of them and I am not advocating for people to make personal sacrifices to better the environment. I'll use driving as an example.

Personally, the climate impact from me driving XX km per year isn't as bad as the inconvenience I would experience by not driving those km that year. I only drive if it makes sense from a convenience and financial perspective. I walk / drive / bike / bus when its better for me. Those XX km of driving have saved me a lot of time than if I took public transit, and the personal benefit of that extra time vastly outweighs the damage I did to the environment by choosing to drive over public transit.

This wouldn't contribute to climate change (as much) if my car were electric and electricity was generated by renewable energy. These technologies need to progress to the point that from a strictly consumer perspective they are better than conventional options. I mean as a consumer all I see is my appliances working and my bank account debited to pay for utilities.

Therefore, technology needs to develop such that we can **continue our current way of life** without harming the climate (as much). Whether it's technology that lets us do things more cleanly, or technology that "repairs" damage by less clean processes, it needs to get better.

Now, this is just me, in a developed country, living quite comfortably. If I were in a 3rd world country, IDGAF about climate change at all. I'd be 100% for using natural resources to industrialize and improve my countries future prospects, just as developed countries did. There's no point in dealing with climate change if I'm (or my family) is at great risk of starving to death, being homeless in the next 5 years, being victims of violent crime or disease or (insert problems in developing countries and are not seen in developed countries).

[Assistant] 10 corporations are responsible for 71% of all greenhouse gas emissions. If you really believe that individuals are responsible for it, or should be responsible for fixing it, the brainwashing has been successful.


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

[User]
[Star Wars: Episode 2] How is Padme such a resourceful and effective fighter?

Padme was queen of a planet of pacifists, and as of the time of Clone Wars, she still regularly uses body doubles and bodyguards from Naboo.  Starting in the area of Geonosis, she repeately demonstrates amazing fighting talents.  She's resourceful, physically strong, better than Storm Troopers with a blaster, firing instinctively (without aiming) and with one handed no less, displays excellent tactical ability later on, and is even able to survive an otherwise fatal fall from a great height at high speed and just keeps on going. I know the prequel trilogy is... shall we say highly criticized, but I'm wondering if anyone has a legit, in universe reason why a Senator, an aristocrat, a former queen of a pacifist, non-militarized world would have developed expert fighting talents.

[Assistant] Its covered in the novelization of Phantom Menace as well as a few other sources. The royal handmaidens of Naboo act as bodyguards and aides to the queen and have to go through extensive training in fighting. Think of them as the secret service. Padm went through the same training since part of the security system for the queen involved the queen assuming the role of a handmaiden while the handmaiden acted as a decoy queen.


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

[User] [General] Ghosts are immune to physical harm, can fly/float, and have no physical needs. Why are there no ghost astronauts or ghost deep sea divers?

[Assistant]
There's debate over what exactly ghosts are, but they can't seem to go where they never went in life. Most stay near where they died or where some other significant moment happened to them. If a guy died by being ~~lied~~ tied to a rock and dropped in the sea then maybe you would get a deep sea diving ghost, though not by choice.

Ghosts are no creatures of ambition - just a lasting memory or a fragment of someone unable or unwilling to move on. They don't go on adventures.


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

[User]
How do they load operating systems onto completely blank computers?

Say I have a computer that is just the absolutely bare electronics. Nothing to read a usb or any inputs. How would I load an operating system onto it? How do computer manufacturers accomplish this?

[Assistant]
The motherboard of a computer is equipped with something called UEFI (Unified Extensible Firmware Interface), the successor of the BIOS (Basic Input/Output System). The UEFI handles the first steps of starting a computer. It contains enough logic to manage storage devices (HDDs, SSDs and USB storage), input devices (keyboard, mouse) and display output. The UEFI software is stored on a dedicated chip on the motherboard, which is preloaded by the manufacturer.

When the system starts, the UEFI will check its settings to determine which devices to search for operating systems and it will hand over the reins to the first operating system it finds in the boot order. In this context, a USB stick with an OS installer also counts as an operating system that can be started. Once started, this OS will handle the process of copying the files from the installation media to the permanent storage location (typically from USB to SSD).


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

[User]
Why do some downloads take significantly more time for the first 3% of the file(s) than the other 97%?

Of course the 3% may instead be 10%-20% or whatever, but I am curious why downloads take longer in certain sections of the package. Do some pieces of data really take longer or are the percentages inaccurate?

[Assistant]
Computers don't just "know" exactly how fast the connection is between two points, and even if they did that wouldn't be completely helpful because they'd have to know exactly how congested the connection was and how much free bandwidth existed. But it gets even more complicated because there are actually multiple connection paths between your computer and a server. Trying to solve the problem of exactly how much bandwidth exists along that route is a very difficult problem, and would require gathering an amount of data that was a considerable fraction of the amount of data actually being transmitted! That's not an easily tractable problem, so instead computers use different techniques to transmit data that is more flexible.

Instead of trying to find out how much data they can send/receive and then sending that amount they'll try to dynamically scale how much data they send and then start pulling back if it seems like they're sending more than the connection allows. In TCP, the transport mechanism for the internet in general, a typical behavior is to start off at a certain rate then begin exponentially (multiplicatively) increasing that rate (by a factor of, say, 2 between time steps) until packets start getting lost or something along the line says "you're going too fast!" then it'll typically back off down to the last know good rate and then begin increasing speed at a slower (additive) rate. This makes it possible to get close to whatever rate the network (including whatever congestion/load exists) can support but it does require some "acceleration" phase. That's why the very first part of a download might take longer, because of that acceleration phase.

I should add that in the case where a download begins during a period of heavy network congestion or routing trouble or what-have-you then that can interrupt the fast part of the transmission acceleration phase, and the transfer can spend a lot more time in the slower acceleration phase even if it ultimately gets up to a high download speed.

Additionally, for some protocols like bittorrent there is a phase proceeding the download phase that involves collecting information on the download and collecting information on the network of peers.


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

[User] ELI5: Why are cops allowed to be fat?

[Assistant] Because height, weight, and physical ability testing is done at the time of qualificationthere's no ongoing fitness or ability requirement in most places.  As many commenters have already pointed out, very few cops actually sprint after perpetrators all day, or ever.  They mostly sit in cars or behind desks, same as the rest of us.


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

[User]
ELI5: What is preventing Toronto from acquiring an NFL franchise?

Toronto is the 4th or 5th largest city in all of North America. It's a major metropolitan area. It has a sport team in all other North American major pro sports. What is keeping Toronto from getting an NFL team?!

[Assistant]
Football is the only major pro sport that has a viable and independent league in Canada. Toronto already has a CFL team.

In order for Toronto to have an NFL franchise, they'd have to figure out how to convince the NFL that they could have two viable pro football teams. Toronto is big but it's not that big. They could, of course, shut down the CFL team, but this would likely anger fans so badly that the new NFL team would be doomed from the start.


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

[User]
Is it becoming longer and harder to get a PhD?

As I understand it, to earn a PhD you must complete original research that contributes new knowledge to the field. Over time, does completing a PhD become longer and harder as original ideas are taken, particularly outside of STEM?

[Assistant]
>Is it becoming longer and harder to get a PhD?

It does depend on field and country obviously, but I'll say from the UK Astro POV: no.

We're still limited to 3-4 years and we still get it done in that time, but the approach to the PhD seems pretty different here compared to the US.

The time limit is enforced first, which means committees have to prioritise good science over good results. You can do amazing research and end up with unimpressive or "null" results. If your research idea was a good one and you did good research, then the supervisor takes a bit of the heat for directing you on an "unsuccessful" project and the rest is chalked up to bad luck. Unfortunately, the Universe is under no obligation to make sense to us or to act the way we expect it to. A really promising line of enquiry can completely fall on its face. If it happens early then you can change direction, but if it happens late, they take bad luck into account.

I think in the US the priority is on having definitive positive/negative results, and you graduate when you have enough results that are impressive enough, which could be 3 years or 7. In that case it might be getting harder to get those original (non-null) results.

Our PhDs *have* become a little longer in general because a lot now include extra time for industry training (CDTs), but the total research time on the thesis is about the same.


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

[User]
[The Night Santa Went Crazy] Why are the National Guard and the FBI involved in bringing down Santa?

The North Pole is legally under international jurisdiction, covered by a load of treaties. Surely Russia, Canada, Denmark and Norway would get a little pissed if the US sent domestic law enforcement to deal with what is clearly an international crisis.

[Assistant] By the time the National Guard and the FBI are involved, there's helicopter coverage and a van from the Eyewitness News.  Clearly, Santa has escalated beyond the North Pole and has reached the US to continue his rampage.


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

[User]
Does the existence of useful (but incorrect) ideas in history suggest a seat at the table for useful (but incorrect) ideas in the present? And what does this all say about the relationship of human knowledge to the world?

Should incorrectness or incoherence suggest the immediate dismissal of ideas?

Throughout history, people have successfully used knowledge that we would now consider to be wrong to successfully achieve goals. And the wrong ideas can be seen as steps on a ladder to more "correct" ideas that followed.

For example, roughly speaking, much of pre-Copernican astronomy was built on a completely "wrong" model, but was still useful for navigation, prediction of celestial events, etc.

Does this fact lend credence to Richard Rorty's view that *usefulness* should be the weightier criterion when considering ideas, or should *correctness* in relation to the "actual world" be the more heavily weighed criterion?

Here is a metaphor to help expand the question (Note--I'm not trying to say that I believe this IS THE WAY IT IS, it's just a metaphor to help articulate my question):

In the theory of evolution, it's generally considered that biological organisms are not evolving to reach some hypothetical, pre-existing final state. Instead, evolution is seen as an "accidental process" where random mutations are selected by nature in terms of the fitness (usefulness) they afford the organisms to survive and reproduce.

So in the metaphor, ideas reproduce and mutate. And the usefulness (fitness) of the slightly mutated ideas is the criterion that drives the selection process.

If an organism evolves according to no "correct" version of itself, do ideas evolve according to "correct" versions of themselves? Roughly speaking, some German idealists may consider there to be noumena or something resembling Plato's Forms -- some absolute truth of the universe that our progression of knowledge is working toward understanding bit by bit.

But if ideas evolve like organisms evolve, how does the "real world" (as ideas relate to it) fit into the metaphor?

I'm not sure if I understand Rorty's take on the relationship of  the universe to human enterprise (language, purpose, need, etc).

*"Anti-essentialists deny that there is a way to pick out an object from the rest of the universe except as the object of which a certain set of sentences are true."* (Philosophy and Social Hope)

I want to interpret this statement to mean that language (symbolic thought) brings the world into focus or even brings the world online for people in Rorty's view.

It is a strange idea to consider and I'm not sure if I interpret him correctly, nor am I sure if I'm asking the questions correctly.

(Edited to add Richard Rorty's full name)

[Assistant]
I believe Rorty's fundamental position is:

The world/reality is out there.

There is an infinite number of ways to interpret and describe said world.

One set of noises and marks does not better correspond to reality than any other set of noises and marks in any meaningful sense.

Therefore, to get something right/correct in itself is an unachievable and meaningless task.

We should prefer some descriptions of the world/beliefs over others in virtue of their greater pragmatic value, not for their ability to mirror reality.


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

[User] ELI5: What is turbulence? And how do airplane pilots sometimes know when they are about to hit turbulence?

[Assistant] Pilot here...Pilot reports are really the best way to know when it will be bumpy. One plane 100 miles ahead will report turbulence at a certain altitude to ATC and then they will relay the message to other planes. Those other planes can then decide if they want to deviate course or altitude...Also just don't fly into those big puffy white clouds, they are bumpy.


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

[User] ELI5: What is happening when a computer program is not responding?

[Assistant]
It could be a number of things, but generally there's two main culprits:

The first is that the program is behaving fine, but it's waiting on something. Could be data from a hard drive or network, or CPU time. Computers are only as fast as their slowest component. A bottleneck can prevent a program from making progress on its task, which leaves the program in a waiting state. If a program is waiting for too long, the operating system might assume there's something wrong with the *program*, and will mark it as not responding.

The other possibility is that there is something wrong with the program. It might have run into an error that's it hasn't been programmed to be able to recover from or respond to gracefully. Something like an infinite loop or a missing piece of required data can trigger this. If that happens and the program doesn't immediately exit, it will kind of just sit there like an idiot until the operating system notices and sorts it out.


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

[User]
[A Song of Ice and Fire / Game of thrones] How good is Tywin Lannister with a sword?

Tywin Lannister, Lord of Casterly Rock and Warden of the West, is one of the most infamous war tacticians in Westeros. He personally led the sacking of King's Landing during Robert's Rebellion and everyone in the Seven Kingdoms knows of his victory over the Reynes of Castemere.
But the question does come to mind, how good is Tywin Lannister personally with a sword? Many believe his son Jaime of the King's Guard to be the finest swordsman in the country, but did he gain that ability from his father or from his own learning?

[Assistant]
He's probably better than most, certainly better than the average common soldier. Growing up he was the heir to one of the wealthiest and most powerful house in all of Westeros. He would have had the best sword teachers and instructors that money could buy.

That said, he's probably nowhere near the likes of Ser Jaime or Ser Barristan Selmy. They have true passion for swordsmanship. They view it as a form of art and expression, learning, practicing, and improving because they enjoy it. Lord Tywin, on the other hand, likely only learned it because it was expected of him as the son of a Lord and it was a useful skill to know.


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

[User]
[Avengers: Infinity War] "Oh yeah, you're much more of a Thanos." What did Doctor Strange mean by this line?

Did he say it because Thanos turned out to be bigger/taller than he expected?

Dumb question I know. Every so often I think about this.

[Assistant]
After receiving a warning from Banner about "Thanos is coming", Strange had met and fought two unfamiliar groups, the Black Order and the Guardians, not knowing what Thanos looked like.

Then he saw the actual Thanos and goes "Yeah, that looks like a galactic conqueror all right".


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

[User] ELI5: How do buildings under construction not get all warped and structurally unsound during heavy rain?

[Assistant] As a carpenter, wood is actually much studier than you'd think. Obviously you don't want to expose the raw materials to the elements for a long period of time (over a week, give or take) but wood is fairly resistant. As for the heavy winds, we use "wall braces" to keep the walls in place. Additionally, walls are designed to support each other. Ideally you would plan to have at least two walls perpendicular to each other by the end of the day. As the final step,you have plywood which "ties" the wall together. It is next to inmpossible to knock over a wall that has been properly built and sheathed (had plywood put on) The main components of a house you would really want to shelter is the insulation (not just the actual "insulation" but anything inside the walls, including drywall" but by this point you would likely have roof rafters up and some plywood to protect the inside.


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

[User] ELI5: how do we measure a day on a planet like Jupiter if the entire planet is essentially just a giant cloud?

[Assistant] Gas giants can have differential rotation. Different latitudes on Jupiter spin at different rates. The polar regions on Jupiter take ~5 minutes longer to make a full rotation. Also the rotation of Jupiters magnetosphere is also used as a measure of 1 day on Jupiter.


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

[User]
How can humans share 60% of our genes with bananas?

I understand how we can share 96% of our genes with nonhuman primates. And I understand that we share about 99.8-9% of our genes with other people. But how can share 60% of our genes with a banana, which seems to be the same amount we share with fruit flies?

[Assistant]
One way to think about it: how much does a smart phone have in common with a refrigerator?  Basically nothing, right, they're totally different in size and purpose.  But think about it.

Both contain steel, plastics, and glass.  Both have circuit boards.  Those circuit boards have fiberglass, copper, gold, and semiconductor chips that contain silicon and plastic.

Remember, DNA describes *everything*, both the big obvious shape stuff you can see, and the basic chemical structures you can't.  The DNA sequences that humans share with bananas include instructions on how to build a cell membrane, how to create the amino acids that form proteins, how to assemble those proteins, how to build DNA itself, how to replicate and maintain it, etc.


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

[User] [Star Wars] Did Darth Sidious ever actually train Darth Vader in the dark side? Also, did Vader intend on eventually challenging his master?

[Assistant]
Even a lap dog isn't going to be much good if you can't teach it to attack something when needed.  There's much to be said about Darth Sidious, to be sure, but the man was nothing if not practical; everything he did served a purpose, or forwarded some kind of goal.  While it's unknown if Vader used any powers exclusively granted by the dark side of the Force, it's only common sense that there was at least some instruction in the philosophy and the mentality of the dark side, stretching all the way back to Vader's time with the Jedi.  And as far as usurping Sidious himself goes, I'll just leave this here:

> "You can destroy the Emperor.  He has *forseen* this.  Join me, and together we can rule the galaxy *as father and son!*"


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

[User] ELI5: How do NASA and other space agencies prevent all the satellites orbiting the earth from crashing into each other? How do we launch rockets without smashing into the satellites?

[Assistant]
Here is a simplified explanation.

The space agencies (not just NASA) keep a very close watch on orbits.  The paths of each satellite are quite predictable and many of them can be steered to correct the orbit.  With a bit of planning, there are plenty of gaps.  Here's why.

What we call space starts about 100 miles up.  Most satellites are in a range of about 100 miles to 22,500 miles up.  To compare with something more familiar, aircraft usually have to be a minimum of 1000 feet apart in altitude.  Even a small range from 100 miles to 200 miles up gives over 500 layers 1000 feet apart.

Now consider that the satellites could be anywhere over the earth's surface, which is roughly 200,000,000,000 square miles.  That's a lot of room.


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

[User] Are aerodynamics important for space travel?

[Assistant]
Absolutely. There are several ways in which it is important:

1) When launching into space, rocket designers must be careful about dynamic pressure. Usually launchers have a fairing to protect the satellite, which is dropped right after leaving the atmosphere. Also they try not to travel too fast before reaching a (near) vacuum because drag would be too high.

2) Space is not a perfect vacuum. Some residual atmosphere in the proximity of a planet may produce drag, causing orbits to decay and inducing torques on the spacecraft if not appropriately taken into account. Orbital decay is usually compensated with propulsion, torques to some extent can be compensated by the attitude control system but it's always better to make the spacecraft symmetric or passively stabilized (to avoid saturating reaction wheels or to save propellant).

3) Atmospheric entry at speeds much faster than Mach 5, usually called *hypersonic*, causing spacecrafts to burn up if they don't have a good heat shield.


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

[User] ELI5 what makes black holes so massive?

[Assistant]
Its the inverse - massive objects become black holes.

Stellar mass black holes form when a large star runs out of fuel and fizzles.  Without this massive energy source at the center it collapses under its own gargantuan weight into an object of infinite density - a black hole.

They can then keep adding mass by colliding with other objects or merging two black holes.

The formation process of the supermassive black holes at the center of galaxies is not well understood - they may be primordial objects that formed soon after the universe began.


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

[User]
[X-Men Days of Future Past] Wolverine's mission is to stop Raven from killing Trask to prevent the war against mutants in the future. What if Logan just killed Trask himself with a gun so it doesn't look like it was a mutant who killed him?

Wolverine finds Trasks, kills him with no witness around, police finds Trask dead and it's ruled out as a regular, random "human killed human" case. What is the outcome, how does the future turn out?

[Assistant] Trask's murder is sorta've like the murder of Franz Ferdinand.  It arguably triggered the crisis, but it didn't *cause* the crisis.  If the underlying cause isnt addressed, then the conflict will just boil over in some other way.