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

[User]
Why are bullets rounded instead of being sharp (like a bullet-arrow)?

We progressed from bow and arrow to guns and bullets, I am just wondering what drove them to be rounded off instead of sharp pointed.

[Assistant]
At the speeds bullets are fired even a round one will easily penetrate human skin. Therefore bullets are shaped to maximise the accuracy of the weapon, minimize drag when they're in the air, and inflict a lot of damage when they do penetrate your body. Some of the deadliest bullets are in fact made with a small pit in their tip in order to cause them to expand upon impact with the target, making the wound much more deadly ( These are known as hollow-point bullets ).

Now military bullets often do have a "pointy" cone shaped bullet, but this is mostly for aerodynamics ( a streamlined bullet experiences less drag than a round one ).

If the goal is to penetrate armour, then typically the bullets will consist of some heavy penetrator made from tungsten-carbide or uranium, since these materials have a very high density and also mechanical properties that let them penetrate thicker layers of armour before disintegrating. These materials are also very damaging to the rifle they are fired from, so they almost always have a jacket of a softer metal which is less harsh on the rifle. Upon impact this jacket fractures, and the heavier core proceeds to penetrate the target's armour.


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

[User]
[Werewolves & Vampires] What if someone has false teeth.

We see in a lot of media that when someone is transformed  that their regular teeth will grow and sharpen. And if they change back like werewolves do that their teeth will return to normal.

But what if the person has dentures? Will they just have no teeth? Or will they grow in a full set of monster teeth? If a werewolf turns back into a human what would happen? Would the teeth all fall out, or would they turn back into normal teeth? Giving the person a new and healthy set of teeth.

[Assistant] I would assume if someone with no teeth became a werewolf they would grow teeth during their transformation, much the way they grow claws and other relevant wolf bits. If its the type of transformation where everything they had on them kind of gets absorbed into their new form the dentures would likely follow suit. A vampire will grow their signature canines at least, as theyre key to their supernatural hunting strategy as well.


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

[User] ELI5: Why does a stuffy nose seem to temporarily cure itself when you are excited or alert?

[Assistant] Adrenaline is released during times of excitement, stress etc. Adrenaline causes your blood vessels to constrict, which frees up space in your nose and allows you to breath. It is the basis for how decongestants work, which are stimulants and have a similar effect.


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

[User]
Editor pulled book from award consideration, failed to tell contributors that she had written a book that was nominated in the same category

I'm a few years out of my graduate program, but I still feel like I'm figuring out the unwritten rules of academia. I have a unique situation here that I was hoping others could comment on.

About two years ago, I was invited to submit a short piece (1,000 words) to an anthology of topics in my field. Over 50 of us had pieces included in the book. We were not paid (which we were all told upfront,) nor were the 20 or so people who edited our entries. This was a somewhat unusual situation where the person originally putting together the anthology passed away suddenly. A colleague of his ("Dr. Smith") took over the project and recruited all of the writers/editors.

The book did fairly well and was even nominated for an award from a well-known association in our field. Dr. Smith emailed us all with the news that the book had been nominated, but explained she was pulling it from consideration for the award. Her reasoning was that because so many of us contributed, we would unfairly skew the voting. (Association members can all vote, non-members can also vote but their votes are counted as 1/2 a vote each.)

This seemed a little weird to me, but I was going to let it go until another contributor to the book emailed all of the contributors and said that they had discovered that Dr. Smith had written a book which was nominated for the same award in the same category as our anthology. (There are only 10 nominees per category.) Dr. Smith failed to disclose this information to us in her email explaining that she was removing our anthology from consideration. The contributor who flagged this also said they had reached out to the association hosting the award and they were told that it is not a conflict of interest and Dr. Smith was within her right to pull the anthology. This contributor didn't suggest any course of action, just said they thought everyone deserved to know.

What would you do if you found yourself in this situation? On the one hand, the anthology is technically Dr. Smith's. The cover lists her as the editor. On the other hand, she was clear in her emails as the book was being put together that she did not have much time to devote to the project, so editors and authors were encouraged to communicate directly with each other. This makes me uncomfortable about the idea that the book is "hers," even though her name is the one on the cover. I'm hesitant to contact her or the award association because she is a BIG fish in our little pond. I'm also hesitant to express my concerns to the award association for the same reason, and I'm wondering if this was why the contributor who flagged this was stonewalled.

Thanks for sticking with my saga. Thoughts?

[Assistant]
I would just move on, honestly, and not worry about it.

Since her name is on the book, and she has another book she'd rather push, there's not much you can do but complain. And it sounds like that will only possibly hurt your career and make her and the organization mad.

You have a publication from it, and the book has been well received. That's a huge accomplishment already given how little academic publications are read.

Focus your energy on your work since it sounds like this situation has progressed as far as it can.


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

[User]
What is the current research consensus for effective therapies?

Hi all,

Just wondering what the current consensus is regarding different types of psychological therapy and their efficacy?

[Assistant]
Cochrane Reviews are good for meta-analyses for the best treatments for different conditions.

Therapeutic alliance is definitely important but so is evidence-based formulation-driven treatment.

Ive changed methods (same client same alliance) when not getting results and a new modality has led to improved symptoms.


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

[User] ELI5: Why do drummers put towels and the like in their bass drums?

[Assistant]
If the bass drum rings too much when its played, it can make the entire sound of the band sound unclean.

Putting towels or pillows or whatever else in there gives the drum a more dead sound that doesnt ring as much, which sounds a lot cleaner.


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

[User] ELI5: Why do most websites have character limits for passwords while at the same time they force you to have an upper/lowercase letter, and a number to make your password more secure. Wouldn't removing the character limit and allowing much longer passwords make them more secure than 16 characters?

[Assistant]
Convention.

There is no technical strength to doing so. Users who will use insecure passwords without the restrictions will use insecure passwords with the restrictions, and cracking these cases isn't all that much more demanding. Meanwhile, increasing password length does substantially increase security. It would be far better practice to have, say, 10 characters minimum and no maximum than is currently common.


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

[User]
[Babylon 5] What if the humans had defeated the Minbari during the Earth-Minbari War?

Canonically, this is extremely unlikely to have happened since the Minbari were so much more advanced.

However, what if the outcome of the war had been reversed, with Humankind solidly defeating the Minbari and nearly wiping them out?

The Minbari are only saved from total extinction by the Humans pulling a last-minute act of "mercy".

How would this change the events of the series? Would the Minbari still be as powerful as they are in canon? Would the worlds be ready for the Shadow War in this timeline? What else might be different?

[Assistant] It would go completely differently and there's no way the situation would ever be reversed like you say.  The humans during their ways just fight until the enemy agrees to back off.  In this case, the humans hadn't wanted to fight to begin with.  The humans wipe out their warships, then force them to surrender and come to the negotiation table.  The results would mostly the same, except the Minbari fleet would be much weaker, likely resulting in the Shadow War going much more poorly.


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

[User]
[40k] Can the emperor of mankind still communicate with anybody by any means?

I know the emperor is basically on his death bed perpetually. But from my understanding he is still an incredibly powerful psyker, can he use that to communicate with anybody? The custodians maybe?

[Assistant]
He communicated telepathically with Alicia Dominica or whoever that proto-Sister of Battle lady was.  ~~They could also install a text to speech device~~.

It's implied that he's spoken to some others too.


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

[User]
[Starship Troopers] Is the Mobile Infantry even trained to kill bugs?

It seems most of their training is centered on fighting human enemies. Is the extent of their training against bugs simply, "fire at it until it stops moving"?

[Assistant]
The war against the Bugs of Klendathu was - in spite of what the Newscasts would tell you - never about winning quickly or cleanly, if indeed it was about winning at all.

**[WOULD YOU LIKE TO KNOW MORE?]**

\>>YES

Breaking!  New information leaked from CentCom indicates that the Terran Federation may have in fact been the driving force behind the devastating so-called Arachnid attacks, and quite possibly instigated the entire conflict themselves!  Recently revealed documents from a source identified as   have strongly indicated that the asteroid impact that claimed the lives of more than ,000,000 civilians and citizens in Buenos Aires was not, as Central Command had previous asserted, an Arachnid attack.  Instead, it is now thought to have merely been a chance circumstance.  The source, a top level  within the Bureau of  stated, "Think about it, do you really think the bugs would have the ability to launch a rock the size of a city half way across the entire galaxy at a significant fraction of the speed of light?  Much less with the telemetry to hit *anything at all*, much less a single, inhabited planet?  Plus, what reason would they have?  They had their own star cluster, for crying out loud, they sure didn't need ours!"

**[WOULD YOU LIKE TO KNOW MORE?]**

\>>YES

Corruption within the Federation!  How could the Central Government have launched out on a campaign across the galaxy, without even those most basic provisions or training to effectively root out the supposed Arachnid Menace?  Standard Mobile Infantry load-out as of July , 22 indicate that a typical MI serviceman's automatic rifle was equipped with hollow-point shells - long known to be hugely ineffective against the resilient Arachnid heavy carapace.  Further,  indicates that the Federal Mobile Infantry armories were at that same date stockpiling both armor-piercing and high-explosive MI ammunition - both of which demonstrably more effective at penetrating and neutralizing insectoid foes.

Infantry tactics drawn from the  Standard Service Field Manual issued to troops immediately before the disastrous offensive against the Bug homeworld of Klendathu notably lacked any tactical maneuvers or strategies specifically designed to counter then-known Arachnid field tactics, along with the demonstrable failure of the United Space Command to alert their own naval fleets to the anti-capital biological weaponry High Command reportedly already suspected the Bugs possessed.  The results: a fatality count that has yet to be de-classified, but surely reaches well on the  of millions.

On the surface, perhaps this oversight could simply be explained aware as mere incompetence from the upper leadership.  But further investigation has yielded the possibility of a far darker truth.

**[WOULD YOU LIKE TO KNOW MORE?]**

\>> YES

It is known to every school-child that the Terran Federation arose out of the failure of democracy to properly pacify and give order to Earth and its peoples.  The Federation realized that were the United Peoples of Earth to ever reach their true potential, every man and woman entrusted with the power to affect political change must hold stake in that system by virtue of duty to it.  As such, only those who served in the Federal Military earned the right to citizenship.

However, in recent decades even that just and proper ordering of our society has seen an increase in those who are dissatisfied with the perceived injustices it perpetrates on citizen and civilian alike.  According to one first-hand account from a civilian from   who declined to be named, the Federation had on numerous occasions killed those who have disagreed with its policies in an extra-judicial, and at times even indiscriminate manner.  Our source pointed to the recent quelling of the supposedly rebellious Mormon faction that, according to official press releases, not long ago sought independence from central Federal control.  No spokesperson from the Territory of Utah could be reached for comment by any available means.

The shocking news that may tie such lingering questions into a far darker reality have been brought together from a leak of classified material from the Office of  Intelligence indicates that the Grand Marshall of the Federation, in conjunction with many of the upper echelons of the Federal governing body conspired to falsify records in order to make it seem as though an extra-human attack against Earth was imminent.  According to the unnamed source, the tragedy that afflicted Buenos Aires was an unlikely, but timely, happenstance that the High Command quickly used to justify mobilization against their pre-determined "target foe:" the Arachnid race of Klendathu.  According to our source, the Central Command  R E was overheard saying prior to the final decision to move forward, "Never let a good crisis go to waste."

Our source states, "They knew the Bugs were going to be an intractable  foe.  They're a hivemind, after all.  Once you stir up the ant next - if you'll forgive the pun - the ants won't stop defending it until there are none left.  And by sending our guys in without the arms, armor, or intel they'd need to effectively combat the bugs - well, according to , , , and the rest, you'd have a recipe for a permanent conflict.  A war that might last a generation, or might never need end.  And nothing brings together humanity more than an attack - or perceived attack - on us all.  It was the perfect way for them to unite us all behind their hegemony against a common foe, and at the same time a convenient front line to send anyone who might express *doubts* about the veracity of the conflict's pretexts.  It was nothing less than an ingenious scheme to hold onto their slipping power indefinitely, and root out the elements of society that wanted to see them gone."

**[WOULD YOU LIKE TO KNOW MORE?]**

\>>YES

*We are terribly sorry, but due to unforeseen circumstances, transmissions to this terminal have been temporarily severed, for a period of not longer than [UNDEFINED].*

*If you have seen information you might have further questions about, we encourage you to report to your local Bureau of Citizen Affairs and speak to our representative.  We are always ready to serve you, especially in this time of crisis.*

*Apologies once again for this unexpected disruption of your programming, and thank you for your unwavering support for the Terran Federation in these trying times.*

*Good day, citizen!*


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

[User] ELI5: Why do some cats look completely different from both parents and siblings?

[Assistant]
Female cats often mate with more than one tomcat - and it's common in this situation to have kittens in the same litter which have different fathers.

The mother is the same (obviously) but they can and do look very different from their siblings and from what you might have thought the father was.


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

[User] ELI5: Why do so many American TV shows & movies film in Canada? Does Canada look more "American" than the actual USA?

[Assistant]
Our urban environments look identical to yours.... and there are numerous companies in Toronto, Vancouver that specialize in providing cars, police cruisers, ambulances etc. with big American city decals, providing USA Today newspaper kiosks, USPO mail boxes etc... our provincial and federal governments give huge tax breaks to film and tv production companies, our major cities have world-class film studios, our actors and actresses already can do most American style accents and for clothing extras, really we wear the same shit that you guys do.

When a US film crew needs to film a downtown city street in say New York or Chicago, both of those fine cities have film and tv relation offices. To close a major city street costs you $$$$. But.. with the exception of architectural or film purist nerds who can actually spot the difference, a downtown Toronto or Vancouver street looks enough alike that it makes no difference. And to close one of our streets will cost a lot less. Oh, and with the exchange rate being what it is, American productions can afford it that little bit extra more.


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

[User] ELI5: How long would it take for us to notice if the sun's mass suddenly became "zero"? How long does it take for Gravity to effect objects?

[Assistant]
The sun is a balance forces, between fusion explosions and gravity. If its mass became zero, we would notice in nine or ten minutes. Solar observatories would note that the sun was rapidly expanding. Of course, a few minutes later, the rapidly expanding cloud of plasma would encompass the earth and we would all die.

If you somehow made that not happen (a magical gravity barrier to disrupt Earth's orbit without destroying the sun), we would notice that the sun was in the wrong position and had the wrong magnitude, since we'd be moving away from it at right angles from the earth-sun line at the time of mass disruption.

How long would it take for us to notice? Well, we already know with high accuracy where the sun will be. And small enough changes will be thought instrument error rather than a physically impossible circumstance. But when a lot of observatories report the same change, or consistent changes over a longer period, we'll figure it out.

After one hour, the sun's position will be off by 0.082 degrees. Is that enough to notice? For some observatories, perhaps, but not enough to be conclusive. We'll cross 0.5 degrees about six hours in, one degree after thirteen hours, two degrees by twenty-five hours. So probably half a day in, scientists would be willing to announce that something was seriously wrong with our orbit.

At that point, we'll be just a few light-seconds further from the sun than we currently are, well under 1% difference. (We're going *fast*, but space is *huge*. It cancels out.) We'd pull in all the observatories that could point at the sun, and that would be enough to show that the sun's apparent magnitude was shrinking.

If you didn't have scientists and observatories handy, you'd notice that your timezone shifted an hour around eight days in. Sixteen days would give you another hour of change. The earth would be cooling off noticeably during this time -- our incoming solar radiation would drop over 7%. This doesn't mean the temperature would drop that much -- thanks, greenhouse gases! -- but the difference in temperature between the coldest and hottest parts of the sixteenth day will be something like 7% less than they would have been.

So please don't turn off the sun's gravity, and don't put up an anti-gravity barrier between the earth and the sun.


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

[User] ELI5:After a workout why is it my body is fine the whole day then when I wake up the next morning my body is completely sore?

[Assistant] DOMS- delayed onset muscle soreness. (Worse for females than it is for males.) When you exercise, you create microtears in your muscles. The body then repairs these tears, hopefully/usually better and stronger if you're training correctly- and this is what leads to muscle growth/hypertrophy.


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

[User] If I steal a chocolate bar from a shop, have I reduced the size of that company by an amount equal to the value of the chocolate bar?

[Assistant]
Yes, but there's a little more nuance to keep in mind...

As far as mechanics of calculating the GDP, it'd be a change in inventory. Change in inventory is a tricky thing... usually it means the inventory was sold to consumers; but there are edge cases of loss. As you point out, theft certainly exists. Also many products spoil and are thrown out. Also, some products can reduce in value (e.g. last year's fashion clothing moving from a high price retailer to a discount one). This sort of "loss" is fully accounted for, and yes it does end up counting as a reduction in GDP roughly for the amount of the stolen chocolate bar.

But there's also the income view of GDP: The chocolate bar maker was already paid by the shop. The ingredient producers were already paid by the chocolate maker. What is potentially reduced is whoever else would have paid to consume the chocolate bar. If the store was now one bar short, and a consumer who wanted one now went without purchasing one *then* income is reduced. If all consumers who were willing to pay for a chocolate bar still bought & paid for one the store's income would be the same (this is usually where people get confused). In short, because corporations *planned* for a certain amount of loss, your small specific theft is kind of already counted.  In the US the GDP release is paired with Gross Domestic Income (GDI), where these sorts of differences could show up.

This may seem odd, but in reality is small enough and consistent enough (in terms of US numbers at least) that it won't have any meaningful impact.


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

[User]
ELI5: What would happen if a person was in between two giant magnets that are repelling?

If that were pushed together what would happen to the person in the forcefield in the middle?

[Assistant] Nothing. No meaningful force is exerted on a person between two repelling magnets. The only force the magnets exert is on each other. The area between them in not being impacted, unless you happen to put something magnet in that area. Magnetic fields are not physical, tangible fields. They don't "create" anything physical when they interact with each other.


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

[User] eli5: Why is it so hard to reverse-engineer something? Shouldn't it be simple to just copy the parts exactly?

[Assistant]
No.

Let's say you try and reverse engineer an iPhone.

You need to know what each component is made of, this is NOT easy at all and requires some fairly high level analytical skills.

You also need to know how each component talks to each other. An iPhone isn't just the solid stuff, and then OS installed; there is firmware that controls how say the capacitance from the screen is delivered to other bits of circuitry. There is software that controls the battery.

Another example would be say a grain mill! You could build something that looks the same easily; a stone with an axel and then another stone on a pivot that can roll along in a circle. But if you don't know how to use it (the software) it's useless.

With modern stuff the material becomes a big factor!! Touch screens are made of very special materials for one. Military hardware? Can also be very exotic composites, it's not just steel etc.


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

[User]
ELI5: How do firemen know the cause of a fire after everything has burnt down?

Often times you hear about the cause of a fire being a cigarette for example. However, isn't the cigarette already long gone after the house/forrest/etc. has burnt down? How is it still possible find out what started the fire?

[Assistant]
23 years in the fire department here.

We cant always determine the exact cause especially with extensive damage.

Its science mixed with art for a lack of better words.

With the cigarette example you used, lets say someones house burned. Patterns indicate it started in their living room and the worst damage was in the area of the remnants of a chair. Wed dig that area out and look for sources of ignition such as electronics. If none are found wed assume it was a different source. We would interview the residents and if they said a certain person always sat in that chair wed ask more questions. Lets just say they say he sat there and smoked a lot and was even sitting there an hour before the fire started.

So what we couldnt say for certain is that the fire started in that chair and was for sure caused by the resident smoking. What we can say is the fire started at or near the chair, that no ignition sources such as electronics were in that area, and the fire was most likely caused by another ignition source. We can take samples to be tested for accelerants as well but if those arent present whats the most likely cause? Most likely the resident who was known to smoke in the chair accidentally discarded smoking materials. They continued to smolder until the chair caught fire. The fire then spread to items nearby then the structure itself.


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

[User]
[Star Wars] Were there any Imperial garrisons on Alderaan when it was destroyed?

In A New Hope it doesn't seem like much time passes between Leia being captured and Alderaan being destroyed. Did the Empire seriously destroy military assets and manpower, both of which cost $, to demonstrate the power of (and make a target of) the Death Star?

[Assistant]
Haha, yes.

EDIT: Tarkin considered the demonstration to be more valuable than any garrison. And giving those troops time to evacuate would've also given the rebels time to flee or make a big stink over the holonet. And considering what we know from *Rogue One*, this isn't out of character for Tarkin at all.


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

[User] ELI5: you all know the japanese snow monkey which bath in hotsprings. how can they actually leave the hotspring without freezing? when they leave the water, the fur is soaked and they should get problems with their body temperature.

[Assistant] Interestingly enough, snow monkeys have two layers of fur.  The inner fur has a lot more oil in it and is water resistant.  The outer fur isn't, however, and gets wet, but dries quickly due to hard shaking.


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

[User]
ELI5: What makes the Mona Lisa so highly regarded?

The Mona Lisa is always described as *the* work of art, but I'm not sure what make it stand out over so many other masterpieces.

[Assistant] It's by a famous artist/inventor and got a ton of press 100 years ago after being stolen. That made it an iconic piece of art, causing it to be studied by artists and the general public which has resulted in it's popularity perpetuating.


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

[User]
ELI5: How is time measured in space?

On earth time is measured via its orbit. But what about when you are not on a planet?

[Assistant]
Traditionally, time is measured in years (the Earth orbiting around the sun) and days (the Earth spinning away from the sun and back). However, these durations are for our convenience and have no real, universal significance. Astronauts living in space still use days. For instance, on the International Space Station, the astronauts use a day/night cycle that's based on the time in England (GMT).

Now, if your question is how to MEASURE time, that's fuzzier, especially if you get into relativity. The easiest way is to keep around a device that measures periods of a cesium 133 atom. Every 9,192,631,770 periods is one second.


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

[User]
Why does dust accumulate on fans?

One would think the fan would blow the dust off instead.

[Assistant] Static. As the fan blade moves through the air it picks up electrons from the fluid molecules. Since most household fans are made of plastic, thus insulators, they readily retain charge as opposed to metal fan blades which will dissipate the charge more readily through conduction. The dust, which is inevitably sucked in by the fan, will be electrically attracted to the charged fan blade and stick. The reason it doesn't blow off as you'd expect is due to the boundary layer effect and some regions of flow separation. Essentially, the shear layer is too weak to move the electrostaticly bonded particles.


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

[User] When/how did we learn that the North Pole was an ocean and the South Pole was a continent? Considering they were both covered in ice.

[Assistant]
Well, most of the ice in the Arctic is only a few meters deep, so its fairly common to see the ocean underneath in cracks, or by drilling down. Plus, its almost completely flat. Antarctica has clearly visible mountains and giant ice cliffs, which clearly wouldnt just be floating on the surface. They are very different looking places, especially on the coasts.

Also, Antarctica isnt really one landmass. Its actually an archipelago with sheets of ice covering and connecting the islands.


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

[User]
ELI5: Why do we have a color wheel, with purple next to red, and describe purple as a mix of red and blue, when the color spectrum has red at low frequencies and purple at high?

EDIT: Thanks for the replies!  Follow-up question: So if I understand correctly, we evolved 3 color receptors. They're pretty good at telling us if something is dark, red, between red and green, green, between green and blue, and blue depending on what combination of receptors are firing. But we can get even more bandwidth out of this codebook if we could use the red+blue combination, so the red receptor evolved the ability to respond to high and low frequencies, inventing purple? (I'm simplifying by talking about the receptors as if their activation was binary on/off.)

[Assistant]
There is a distinction between purple and violet.

Violet is what you see in the color spectrum / rainbow. Violet is a color directly associated with high-frequency (short wavelength) visible light (any higher and you go into ultra-violet).

Violet can look similar to purple and the terms 'violet' and 'purple' are often used interchangeably - but there is a technical difference.

Purple does not appear in the rainbow / color spectrum. Purple has no specific frequency / wavelength of light associated with it. Instead, purple is a combination of lower frequency light (red colors) and higher frequency light (violet colors) which your brain interprets as a purple or magenta color. So if you have a material that reflects some lower frequencies and some higher frequencies it will appear purple to you.


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

[User]
[Marvel] Would the Punisher prioritize saving innocent live(s) or killing his target?

I know the Punisher is extremely careful to not cause any collateral damage in his pursuit of criminals, even going so far as to kill other vigilantes because they have.

However, since he is so single-minded in his pursuit of villains, what would he do in a situation where he had to choose between letting an innocent person die and killing his target? For example, if a villain had made it so that a civilian died if they died, would he let them go?

Or how about if, while chasing a villain, he crossed paths with someone in need, perhaps from a car crash or something? How much does he truly care about saving lives?

[Assistant]
It depends on the situation really. People in normal, everyday peril don't really register for him if he's on a mission, so he won't let a mark go to pull somebody out of a fire or anything like that.

A villain threatening an innocent life as collateral to escape is another matter entirely. If there's a way he can take somebody down and save the hostage he will, shooting a guy in the head while they're holding a hostage for example. If there's no way he can beat the situation he'll spare the innocent life, but you better believe that guy will become his new #1 and he will be after them twice as hard.


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

[User] [Star Wars / Star Trek] Either a Federation vessel is somehow transported to a galaxy far, far away, or an Imperial diplomatic ship somehow ends up in federation space in the Milky Way. How do the civilizations react to one another?

[Assistant]
In short, not smoothly. A Federation ship in the GFFA is Voyager 2.0. Unable to get home, the empire would probably force them into the Rebel's arms.

However, a ISD that found it's self in the Federation would probably be tolerated until they started something with a random planet and then negotiated to death.

Fundamentally, the Imperial thought process and the Federation thought process are opposite and opposed. When push goes to shove, the Empire starts shooting and the Federation will finish shooting.


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

[User] ELI5. Saw a video of a white blood cell chasing down and ingesting a bacteria, why aren't white blood cells "alive" as their own beings?

[Assistant]
I know it's a flashback to, like, freshman biology but there are characteristics that we use to define what has life. They are responsiveness to stimuli, growth or change, ability to reproduce, metabolism and respiration, homeostasis-ness (freshman bio was a long time ago), cell structure, and reproduction. White blood cells check off a few but not all of them.

More importantly, though, they're part of *our* cell structure. Without us, they do not exist or exibit any of those characteristics. They are alive (in the sense that they can die, so they must be alive) but it's inherently not as their own beings. They're no different than our skin cells or our teeth - they're alive... As long as they are part of us because we are alive. But they don't have life.


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

[User] Why some of the great philosophers never married ?

[Assistant] Nietzsche's take on this pops up in Genealogy of Morals, essay 3, chapter 7, interestingly. His argument is that philosophers have a bias towards ascetic ideals because they are the conditions best suited for intellectual inquiry. Having a family detracts from these optimum conditions, and so philosophers chose not to marry so that they may stay at the centre of their little academic world.


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

[User] [ELI5]: Why do people sometimes refer to a husbands wife as, "Mrs. (Husband's name) Smith?" Like the husbands first name but just Mrs. at the start? Wouldn't it be easier to just say her name?

[Assistant] Waaaaaay back in the day, some women were proud to take their husbands name. It was like a badge worn with honor, or a prize ribbon won at a fair. It depends on how you look at it. It used to be considered proper or respectful to call someone by their name like that. Today, its a matter of personal opinion and the culture one has been raised with. Women tend to be more independent these days and have more ambitious goals than being a housewife or a Mrs. (insert husbands name here).


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

[User] ELI5:If the international space station can retain about 93% of the water used on board, why don't we implement some of the technology used in everyday homes?

[Assistant]
It is a very specific and expensive technology that isn't well suited for home use.

If we absolutely needed to conserve water like that, we would, but tap water is _really_ cheap (in the USA at least).


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

[User] ELI5: Before we saw the Earth for the first time in space, how did we know what our continents and lands looked like?

[Assistant]
Let's say that it is 1920 (so, no GPS other satellites). You have just found a island in the Pacific and want to know where it goes on the map. There are two things you would need to figure out to do that: how far north or south is the island, and how far east or west it is. One way to do this is by sighting the stars.

The stars look like they are fixed to a sort of celestial sphere that rotates around the Earth, with its axis of rotation going through our north and south poles. By looking at the north-south positions of the stars, you can figure out how tilted the celestial sphere appears to be from your position, which tells you how far north you are. For instance, if you see the North Star, you can almost directly read your north-south position. If it's overhead, you're close to the North Pole, and if it's on the horizon, your near the equator.

Determining your latitude (east-west) [EDIT: sorry, that should be longitude] position is much more tricky, and there is a long history concerning it, but it basically boils down to clocks. As the celestial sphere spins in sky, the stars will appear to be in different positions east or west depending on how far east or west you are. If you have an accurate clock and a star chart, you can determine where the stars would be at that time if you were at a reference point on the Earth (for instance Greenwich, England). Looking at where the stars actually are in your sky at that time, you can determine how far east or west you are.

A book that's well worth a read on this subject is *Longitude*. It discussed the problems and history of determining your position while navigating.


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

[User]
ELI5 Crypto is software, code. Isn't it hosted on a server somewhere on the world? Break the computer, break the crypto?

I don't understand how cyptocurrency can be forever. It's just code at the end of the day. That code must be run on a server somewhere right? Like all online games and data servers keep all digital data. Isn't cyptocurrency the same? If the server or computer dies, won't all the money just poof?

[Assistant]
Crypto currency is a decentralized system. There is no "central server" that is running the whole scheme. If you're familiar with Peer-to-Peer games where you don't connect to a server but instead directly to the players you want to play with crypto functions in similar terms.

Crypto is "run" by everyone who wants to run the code. If you imagine a network where your computer is connected to a few other computers, and those computers are connected to a few more, and those to a few more, that's kind of how crypto operates. Everyone who wants can store the blockchain. Your computer is constantly chatting to its neighbors to share information and try to keep up to date with what chain is the right one and who is doing what.

Unless a significant portion of the computers who are running crypto go poof you can fairly consider the system functionally immortal. You only need a single computer online to run the entire blockchain, and there are a lot of computers currently online.


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

[User] ELI5:Why are witches usually regarded as being evil while wizards are more generally portrayed as good?

[Assistant]
Wizards, in most lore, get their powers from studying and schooling where they learn the "science" behind their magic. They tend to be more on the "good" and responsible side of magic.

Witches/Warlocks are given supernatural abilities, usually from something evil (demon, devil, whatever) - they tend to be on the "personal gain" and "evil" side of magic.

Sorcerers are born with supernatural abilities and can go either good or evil and can hone their skills through training. Think Elsa from Frozen.


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

[User]
ELI5 How do humans acquire a taste for things such as wine, beer and coffee

For instance I absolutely hated beer when I was a young drinker but now absolutely love it. That may be because I am from Wisconsin but how does the brain hate a taste but then start to like it?

[Assistant]
The palate changes with age.  Bitter is a particularly bad flavor to young people.  This is supposedly because poisonous plants are often bitter, so we evolved to dislike that flavor in our youth.

Also your enjoyment of the beverage is only partially tied to its taste.  It's color, smell, intoxicating effects, and your memories of other times you've consumed it inform your opinion.

Finally, it's an addictive substance.  Even mild alcohol cravings can convince you that you not only tolerate the flavor, you prefer it.


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

[User] Does the US government run scientific experiments to determine if policies work?

[Assistant]
There are many cases in politics and government internationally where the lack of experimental evidence screwed things up. Therefore hopefully someone will learn from these mistakes and start running scientifically structured experiments on their policies.

1) Randomised urine samples for marijuana use in prisons lead to prisoners switching to harder drugs that didn't show up in urine samples. Marijuana use declined but heroin use increased.

2) A city/province in India had a bounty for a particular type of wild Cobra that was very dangerous and they wanted to get rid of them. You could catch and hand in a dead cobra for a reward. People started breeding the cobras at home to get the reward money. The government cancelled the scheme, so everyone released their farmed cobras into the wild. Cobra population increased massively.


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

[User] ELI5: Why do maps always start with North America on the left and end with Asia on the right?

[Assistant]
Europe is in the center.

Since most maps were created in europe  (America was not discovered yet, there was an "europlean cluster" and an "asian cluster" of influence) during history, it became "common" in the european (and then american, since it was discovered by europeans) "tradition".

If you look at japanese or chinese (or russian) maps they are asian-centric for example.


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

[User] In the Harry Potter universe, could someone commit suicide with the killing curse?

[Assistant]
I imagine that yes, yes you can, since as most spells the Killing Curse is emitted from the wand's tip, and the direction of the tip is what gives it its aim, one could shoot themselves.
But, the killing curse is fueled by the desire to kill, one would have to be absolutely sure in its intent to be able to shoot the spell aimed to him/herself, making it a hard, albeit 100% proof, suicide method.


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

[User]
ELI5: How come we can see highly detailed images of a nebula 10,000 light years away but not planets 4.5 light years away?

Or even in our own solar system for that matter?

[Assistant]
Compared to nebulae, planets are very very very very very small. You can see a mountain that is 1 kilometre away from you much clearer than you can see a grain of sand that is 1 metre away.

Edit: as several people have mentioned, planets don't emit any light of their own, this makes it extremely difficult to see planets when they're being drowned out by the light of their parent stars.


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

[User]
Update- I had the meeting about my progress

So my supervisor was very helpful and talked me through the next stages of my project and what they expect me to do over the next few months.

A lot of the confusion lies on my end since I was forcing myself to pack my days full of work when they were expecting me to take it a bit easier and focus on doing one major task instead of several smaller ones.

To be honest I'm kind of floundering at the minute. My head simply isn't in the game and I'm feeling really bad about everything. I think I need some time off to be honest.

[Assistant]
You fool! You fell victim to one of the classic blunders! The most famous is never get involved in a land war in Asia, but only slight less well known is this: Don't mistake activity for productivity!

Seriously though sounds like your advisor is good and was able to help set you straight. This is an incredibly common trap to fall into for PhD students, but it absolutely destroys productivity. You're doing very involved intellectual work- doing one think that's well thought out can have far more value than 20 things that aren't.


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

[User]
[The Culture]The sci-fi civilization of the Culture allows for mind uploading of people to computers and perfect cloning without destroying originals. How does the Culture decide which owns the property of the original, the original or the clone?

And if you are familiar with the Culture, I am sure you were rushing to respond that, aha! They both just get identical copies of everything in there is no conflict! To which I say aha! You are wrong!

There are two assets that can't be truly replicated.

1.  Handmade objects.  Given the goodlike powers that the AIs that run the Culture possess, they can make true copies of anything. However, just like in our real world, there must be some people who place a value on handmade artisanal goods. Be it food, art, paintings furniture etc. There must be some in the Culture which find special significance and value in originals of things made with great personal effort.

2.  Living space. Living space is unique and can't simply be copied. Well, a home and every object within it could be copied down to the last electron, but its position compared to the rest of the world is unique and can't be copied.

So who gets the original stuff?  The original or the copy?

**BONUS QUESTION!** Since the only rule that the Culture seems to have is you can't unconsentually harm others, what happens if you steal the possessions of others?  Well, the Minds can simply make copies of physical possessions. But what happens if someone moves into your home and refuses to leave? Will the Minds and others do anything besides shun you?

[Assistant]
I imagine that if the two copies were operating in the same ship at the same time, they would simply have a sit-down together and decide between themselves who exactly got what.

Any conflict between them would quickly come to an end because they'd be the laughing-stock of their ship's community for however long it went on.

The Culture enforces social norms by public participation, so there'd be a ton of mockery going around the ship both in physical space and on their version of the Internet.

Eventually the two copies would feel so harassed that they'd reach an agreement just to get everyone else to stop making fun of them.

**BONUS ANSWER:**

If someone were to move into your home and refuse to leave, what would likely happen first is that a friend of yours would make a big public display of inviting you to live in their house, which you would accept.

While you're crashing on their couch, everyone else on your ship would do whatever they thought would make living in your house unbearable for your squatter.

Maybe your neighbors would constantly play loud music at 3 AM and make your "street" the party street...

Maybe the ship's Mind would deliberately make the WiFi lag and disconnect from the TV at random while the squatter is trying to stream a movie...

Maybe somebody would decide to open an exotic foods cafeteria right next door, and give out nothing but that one particular fruit that smells like raw sewage (I think it's called durian).

There's a thousand different things that people could do without directly infringing upon the basic rights of your squatter (since that's obviously forbidden).

Like in the previous example, they'd just keep doing them until your squatter felt so harassed that they'd move out of your house and publically apologize to you for all the trouble they put you through, just so that people would stop messing with them.


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

[User]
CMV: If you couldn't emotionally handle killing an animal, you shouldn't eat products from that animal.

This doesnt apply to people who need to eat meat or animal products to survive. However in most of society animal products are a luxury and plant based food is more plentiful and cheaper.

Due to economies of scale, we are very disconnected from our food sources. It is very easy to eat a burger or a chicken nugget without a thought to where it came from.

If you couldn't personally kill the animal that your meal came from because the thought of killing it disturbs you, you are being hypocritical by paying someone else to carry out your violence.

I say you should avoid the animals products rather than a just the meat because with milk and eggs there is a lot of slaughter of male animals that most probably dont think about.

Of course there are people out there who have no problem killing a fish, but couldn't kill a cow.  Ot would be reasonable in this case to consume fish but not beef.

[Assistant]
And by the same logic, if you are uncomfortable with heights, you should not use electricity, or work in highrises, or use any other product that requires people to work high up. If you dislike deep water, you should avoid plastic entirely, since much of it is extracted from the ocean floor, which often requires divers doing maintenance. If you dislike public speaking you should not vote.

An advantage of modern economy is that the idea of being "comfortable" with performing a task is also something we can outsource. People who actually kill animals almost certainly don't have a problem doing it.


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

[User] ELI5: When it's really cold out, why can you see the exhaust from cars, but only until they warm up?

[Assistant] What is happening when you can see the exhaust is that warm water vapor is cooling and collecting into small droplets that are suspended in the air around them. When the exhaust system is cool the water starts condensing before it leaves the pipes. Once everyting is warmed up though the exhaust stays hot enough that by the time it has cooled enough for the water vapor to condense it is too dispersed into the atmosphere to form enough droplets to become opaque.


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

[User] [The Shawshank Redemption] Why did Andy talk to warden after hearing Tommy's story, instead of contacting his lawyer? He had to know there was no way warden Norton would ever let him leave Shawshank alive.

[Assistant] He thought he was on the Warden's good side. He had privileges no one else had, he did odd jobs for the staff, he was even protected by the guards. He thought he was a friend, or at least *more than just useful* to the Warden. The last thing on his mind would be the Warden's betrayal.


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

[User]
[Snowpiercer] Ive lost my arm. What happens next?

Passengers in the tail-end of the train are punished by having their arms frozen off. Their bare arm is coated in gel or water, a clamp (?) is placed around their bicep and their arm is pushed through a portal where its exposed to temperatures of -120 degrees centigrade. After a couple of minutes their arm is pulled back inside and shattered with a hammer. There are lots of one-armed survivors on the train- I want to know how the human body would react and heal to this trauma. Is it possible that you can freeze a limb without causing significant damage to the rest of the body? Theres no healthcare in the back of the train, how would they deal with symptoms like shock?

Its definitely an effective deterrent because its been giving me nightmares all week.

[Assistant]
> Is it possible that you can freeze a limb without causing significant damage to the rest of the body

Apparently.

> how would they deal with symptoms like shock?

Survive as best as possible. This punishment is meant to dissuade people. If the person dies well... more room for everyone else.


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

[User] ELI5: How can countries like Germany afford to make a college education free while some universities in the US charge $50k+ a year for tuition?

[Assistant]
Most EU countries have a higher tax rate than the US, combined with significantly lower military spending and smaller populations than the US.

In 2011, Germany had a tax revenue of $1.551 trillion.  In that same year, the US had a tax revenue of $4.218 trillion

The US had a population of 311.6 million.  Germany had a population of 81.8 million.

Then, on top of that, of their $4.218 trillion the US spent $693.485 billion on military.  Germany spent $48.8 billion.

So the US only had 2.71x more tax revenue despite having 3.8x more people - and then the US spent 14.2x more on their military than Germany.

(All values listed in USD$ and sourced from Wikipedia, so take it for what it's worth)


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

[User] ELI5: Why does my reflection appear upside down when I stare into a shiny spoon?

[Assistant]
When you look at a mirror, the light is reflected back in parallel lines so you see a perfect reflection.

When you look at the back of a spoon, the light is reflected and spread out so your reflection is warped to look bigger.

When you look at the front or inside of a spoon, the light is reflected opposite of how the back reflects the light. It isn't spread out, but focused at a point just a bit above the rom of the spoon. When it reaches your eye, the light has passed by the focal point and is spreading out again. But, because your passed the focal point, the reflected light from the bottom of the spoon is now at the top. The light that hit the top of the spoon is reflected, passes through the focal point, and carries on, now at the bottom of the reflected image.

It's basically because of that focal point. If you could get close enough you'd pass through that point and see an upright image again. Try it with a large, metal mixing bowl.


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

[User] Is consciousness a higher layer of abstraction, or is it the most concrete thing we can know?

[Assistant] This very antimony is the first problem wrestled with by Hegel in the Phenomenology of Spirit, and resurfaces throughout his work. Sense certainty, while initially appearing to be concrete, struggles with the problem of indexicals. The idea of an object, which might seem to be an abstraction imposed on sense data, is actually a means of making the consciousness of exteriority more sensible (thus avoiding the now is night problem)


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

[User]
ELI5: Why do game studios have to use publishers, And then why can these publishers take in millions leaving devs behind in the money being made?

I've yet to understand why or how this happens.

[Assistant]
As lovely as the thought is, the idea of a lone developer sitting in his garage making games does not really apply anymore. In a world where video games are a multi billion dollar industry you need a lot more than just programming skill to make a successful game.

Developers have to make the game, but publishers will:

* Fund the game while it is in development. People still have to get paid and the lights do not keep on by themselves. Developers generally do not get money until the product starts selling, publishers handle the costs until then.

* advertise and market the game

* utilize resources and connections to get the game a visibility edge

* Take majority financial risk if the game flops

* often handle the legal aspects that have to be cleared.

* get the game on store shelves.

* Often handle public relations and media connections.

These are all things developers often do not have the time bor resources to handle. In return for having a different company handle the risk and messy non-developer jobs the publishers get a sizable return on the investment.


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

[User] [DC Comics/Marvel Comics] How does the Batsuit compare technologically with the Iron Man armour?

[Assistant]
It doesn't come close. The batsuit is essentially very good body armor with various gadgets attached and a few gadgets plugged in. Iron Man is basically a one man army that's completely mobile.

Batman voluntarily chooses to equip himself with a lesser suit due to his preference for stealth, the type of foes he usually faces, and his no kill rule.

Not sure about more advanced batsuits such as the one Gordon wears, TDKR suit, etc.


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

[User]
[Black Mirror] In the world of "15 Million merits, why are the trash collector guys looked down at?

Why would you look down on someone who can walk around in slow pace and pick stuff up if the only thing you do the whole day is pedaling? I would definitely prefer the trash over the bicycle.

And do the trash collectors earn merits for their work aswell? If so, at the same rate as the people on the bicycles?

[Assistant]
The cleaners aren't looked down on for being cleaners they're looked down on for being overweight and being a drain on their society, while the slim/fit people are riding their bikes they're generating power for their city which is something the overweight ones are unable to do so as efficiently or for as long.

The cleaners do earn merits as they need to be able to feed themselves and the society doesn't appear to give anything away for free but it's doubtful that they earn anywhere near the same as the cyclists as there'd be no reason for people to want to ride the bikes and there'd be more overweight people.


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

[User]
Could I keep accelerating forever?

Suppose I'm in a spaceship which happens to have a very cool engine, an engine that can keep pushing the entire ship at 1 G with no fuel required. Now, heres my question: From my frame of reference, will I be able to keep speeding up, even as I push the speed of light? It is my understanding that from an outside frame of reference, I will never be going faster than *c*, and time dilation will make it such that in my frame of reference, light is still moving at *c* relative to me, but will I be able to keep accelerating at the same pace, will I still feel 1 G of acceleration?

[Assistant]
Yes. Since there's no absolute velocity, after accelerating for some period of time, the laws of physics will be no different and there is no reason why you should not be able to continue accelerating in exactly the same manner as before.

Of course, from an outside non accelerating point of view your velocity will not change linearly, instead it will asymptotically approach c.


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

[User]
ELI5: The process in which THC is broken down in your system.

I'm curious to what the actual process is. From ingesting, to how it travels through your body and ultimately passing.

[Assistant]
THC (tetrahydrocannabinol) is one of the main cannabinoids in cannabis. You don't have to ingest it, you can inhale it, but either way it ends up in your blood (by being absorbed by either your intestines or your lungs). The main difference is that it takes about 1-2 hours to absorb something through your intestines, but only about 5 minutes to absorb something through your lungs.

The blood carries the THC around your body, where it gets absorbed by all your fatty tissues like body fat, liver and obviously the brain (where it has the effects most people use it for). The THC can stay in these fatty tissues for well over a day, slowly being released back into the blood (important for anyone trying to pass a drug test, sometimes it can take a week or more for it to all be gone from your body).

Anyway, it's the liver that does the job of breaking the THC down. The THC gets broken down from its most potent form (usually ^9 -THC) to less potent form (11-hydroxy-^9 -THC) and then to the inactive form (nor-9-carboxy-^9 -THC). It's mostly the second form that ends up in the feces, and the last form that ends up in the urine. So about 65% of it exits your body via feces and the rest by urine. Most of the THC byproducts will be out of your system within 4 hours of it hitting your bloodstream, but to fully get rid of it all will take much longer (as mentioned above).

One final side note, if you're a breastfeeding mother, there's another way the THC can exit your body - via breast milk. This also means that you can feed cows on cannabis and have them produce THC-laden milk, which gives me a business idea....


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

[User]
If you burn or cut your fingertips, does the skin grow back with the same fingerprint?

I saw a movie where the bad guy burned his fingerprints off but when I accidentally burnt my own fingertips the print seemed to grow back the same.

[Assistant]
Depends on the extent of the damage - more specifically, if your injury is severe enough to disrupt the basal layer of your epidermis, your fingerprint would be affected. The friction ridges that define your fingerprint also exist in the junction between your dermis and your epidermis (as dermal papillae), and if your injury goes _that_ deep, it's possible to alter your print.

This is also what allows some prints to be taken from a cadaver, even if the epidermis is damaged. You just peel the skin off like a glove, and both the underside of the epidermis and the dermis will contain the ridge structures.


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

[User]
What's the effect of sound in a object moving at high speeds (as much as to experience time dilation) ? Also , will our thought processes be slower and would we be aware of that?

If someone standing behind me talks to me , or if I use headphones to listen to music while moving in a vehicle close to the speed of light, how would it feel like?

[Assistant]
The answer is very boring: nothing would really change for you. What you have to realize that relativistic corrections like time dilation only apply when going from one frame of reference to another. But within each individual (inertial) frame of reference all the laws of physics work just the same. In fact, this idea that no frame of reference is privileged is one of the key results of special relativity.

What this result means is that if you were on a spaceship and you had a clock with you, you would always see it move at the same rate, no matter if you were standing still with respect to the Earth or moving at 0.99c. In other words, from your perspective time would continue to pass unchanged and every process on the spaceship would look the same. You could talk to other people just as you could before (assuming there was air), your brain would work just the same, etc., etc.


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

[User] ELI5:Do modern batteries still benefit from a full depletion and full recharge?

[Assistant]
Nope. Not always anyway.

The memory effect was a phenomenon in NiCd and NiMH type rechargeable batteries. Most batteries these days use Li-Ion, which is actually harmed by doing full depletion cycles.


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

[User]
[Gundam Wing Endless Waltz] What purpose does the zero gundam's feathery wings serve?

This is a machine of war. What is the practicality of having the thrusters stylized into feathery wings?

[Assistant]
It's important to remember that the lead designers of the Gundams in Endless Waltz (and the designer of Wing Zero in particular) are as much artists as weapon designers.  They created what they considered the 'perfect' weapons, and saw themselves reflected in their machines.

As much as it was a weapon, Wing Zero was designed to also be an elegant masterpiece that all other mobile suits would be compared to.  Every part of Wing Zero had to be perfect, or at least as close as possible.  Each wing having multiple joints down to the level of individual feathers, meant that the Zero system could recommend movement down to the smallest increment possible.  At the same time, styling them like actual feathers reinforced Wing Zero's beauty and terror.

If something as small as a maneuvering fin was so carefully crafted that it was simultaneously proof against most mobile suit-quality weapons fire AND could operate to levels of performance beyond any other mobile suit AND was beautiful on top of that... then it tells an opponent that Wing Zero itself must be a quality of weapon so advanced that it's not even worth fighting against.


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

[User] ELI5: Why do some clocks run slow or fast, regardless of being digital or analog?

[Assistant]
Clocks are mechanisms/circuits that are designed to run at a fixed rate, and they are very good at that. There is only one, perfectly precise rate that is neither fast nor slow. It is impossible to hit this exactly, so every clock will be either fast or slow at a given moment. Most clocks are pretty damn close though, so you perhaps wouldn't notice.

Think of it like this: there are an infinite number of fast or slow rates, but only one precisely correct rate.


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

[User]
In Interstellar would the ship appear to be heading towards Miller's Planet for years or does time only begin to slow down once they have begun their descent into the planet's atmosphere?

Since they spend 23 earth years on Miller's Planet what would it look like to Romilly who was still on The Endurance? Would he still see the ship in space heading towards the planet for years or would he not be able to see them?

[Assistant] So, the orbital mechanics of Interstellar don't *entirely* make sense. But yeah, if a spaceship moves very close to a black hole, an external observer would see them as moving much more slowly. The light would be emitted more slowly too, which would make them very dim. This would also make the frequency of the light go down too. So as a spaceship approaches the event horizon, a distant observer would see them moving slower and slower, getting dimmer and dimmer, and redder and redder.


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

[User]
Do we love the feeling of being in love?

I read this somewhere a couple of years back.
I don't exactly remember it but it was something to the effect of, we like the feeling of being in love so much that we trick ourselves into thinking we love the person.
Is this ever heard in philosophy?

[Assistant]
Nietzsche writes literally that in Beyond Good and Evil (sect 175), and in this light, he is very close to 17th century French moralists. However, the oldest example of someone who tricks himself into thinking he is in love is doubtlessly Alicibiades in Plato's Symposium. Indeed, he thinks Socrates is going to provide him with the knowledge he lacks, but Socrates tries to make him understand that he is not going to give him knowledge and he has to do that for himself. This is in keeping with the Platonist idea of there being a process through which you should first love the beautiful bodies, then the beautiful minds and end up loving the Beautiful itself, i.e. the essence of Beauty, and ideas. Socrates is presented as a Silenus, that is a statue that looks awful on the outside but beautiful on the inside. He is the great trickster. Nietzsche would probably call him a polytropos (think of something like Machiavelli's fox).

In this light, we love the feeling of being in love because it diverts us from caring about ourselves, which we do not want to do (something Pascal famously analyzed as "divertissement"). In both cases, love is both a help if not a necessary means and an obstacle on the path towards self-knowledge.


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

[User]
ELI5: What gives the federal government the right to ban marijuana? And why can states violate that? [Serious]

I keep hearing about how the federal gov't bans all pot. But states still legalize medical marijuana, and in the case of Colorado, even recreational pot. So why can states violate the federal law? Also, if it took a constitutional amendment to ban alcohol at a federal level, why can they just decide to ban pot?

[Assistant]
The Commerce Clause of the Constitution gives Congress the authority to regulate items that have a high probability of being trafficked across state borders.

States that have chosen to legalize marijuana are simply choosing not to enforce federal marijuana laws and have gotten rid of most of their own criminal & civil penalties on the sale and trafficking of the drug. If the federal government wants to enforce those laws they now must carry out enforcement itself.

Prohibition was put through as a Constitutional Amendment because proponents felt it would be a more permanent change than a simple law that could easily be overturned. Remember when Prohibition passed no Amendment had ever been overturned at that point.


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

[User] ELI5: Why does salt and alcohol hurt open wounds?

[Assistant] When you have an open wound, you have exposed nerve endings. The signals that nerve ending send are chemical in nature. So when you introduce a high concentration of sodium ions (in the case of salt) you cause those nerve endings to misfire and send a signal of pain when there salt itself is not causing much damage at all. For alcohol it's the Ethanol that causes pain because we have little nodes called vanilloid receptors that detect heat so we dont burn ourselves. The Ethanol activates the vanilloid receptor and sends a misfired message to the brain that you're experiencing pain.


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

[User]
Why does diesel fuel use compression ignition and why do diesel engines have such low RPMs?

I should clarify that I am aware of how engines work in general (intake, compression, ignition, exhaust etc). I don't need an explanation as to how an engine actually fires. I want to know what the properties of diesel are that allow it to use compression ignition instead of spark ignition. Why do the engines have such low RPMs? What is it about diesel that allows for it to create so much torque at such low speeds?

[Assistant] Diesels typically operate at lower RPM because the rotating assembly has to be built to withstand the high compression, which is about twice that of a gasoline engine. Steel pistons, heavier connecting rods, and a long stroke lead to more rotating mass, all of which increase the forces involved at a given RPM.


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

[User] When I'm sitting in a quiet room, why do things "click"?

[Assistant]
They are always occuring, a cacophony of sound that we usually remain oblivious to. Our brains filter out an enormous amount of stimuli that they decide is unimportant to focus on. When there are fewer environmental stimuli, we tend to notice the smallest things as or minds work to occupy themselves - the itch on your back, the creaking of the floor, and shadows on the wall.

In a related note: people in sensory deprived environments are known to hallucinate and amplify stimuli as the brain works to keep itself occupied.


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

[User]
What does it mean to be immune to a disease, and how do "carriers" work?

From what I understand (I might even be completely wrong?) there is bound to be at least one person on this earth immune to disease X, they could carry it and spread it - but not be affected and killed by it. How does this work? Does their immune system not care about the disease or just isolate it in the body? What happens?

[Assistant]
There are different kinds of immunity.  If the infectious disease cannot grow in the host or has been completely wiped out, then they can't be a carrier.  This can happen several ways, for example:

1.  The disease has been completely obliterated by the concerted effort of your immune system or through drugs.  For example, if you clear a yeast infection completely, you can't give it to someone else afterwards because there's simply no yeast left.

2.  Certain people are naturally immune to certain types of disease because of there genetics.  For example, some people are immune to HIV because they don't have a receptor that HIV attaches to.  If the virus can't enter the cells, it can't infect and be passed on.

However, there are other disease that the host can contain (maybe for a little while anyway) and render asymptomatic but cannot completely clear, even with the help of drugs.  These include herpes, HIV.  The disease has mechanisms to avoid or suppress the immune system enough that there aren't any symptoms, but the disease can still be transmitted.  Every disease has it's own way of doing though.  Typhoid fever, for example, can be asymptomatic in a host, but still be tranmissible because in certain people the bacteria can "hide" from the host immune defense.


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

[User]
Would it be possible to use time dilation to travel into the future?

If somebody had an incurable disease or simply wished to live in future, say, 100 years from now, could they be launched at high speeds into space, sling shot around a far planet, and return to Earth in the distant future although they themselves had aged significantly less? If so, what are the constraints on this in terms of the speed required for it to be feasible and how far they would have to travel?  How close is it to possible with our current technologies? Would it be at all cost effective?

[Assistant] In terms of physics, yes. The technology for that doesn't exist right now though. We can send things at like 20 km/s, and we'd need to go like ten thousand times that fast to start seeing these effects.


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

[User]
Do mosquitoes have any significant role to play in the ecosystem? In general what living beings have almost no role to play in the ecosystem?

Also, are all "plants" types important to an ecosystem because they are autotrophs (apart from some archea bacteria)?

The basic ecosystem (for me) is: herbivore, carnivore and omnivore. Mosquitoes - do they help in pollination? (like insects do).

If answer is no then one can also argue that even humans are not required, but I'd say the "brain power" we've got changes the answer to "yes" (imo).

Just a thought, (consider) for female aedes mosquito, the virus apparently lives in her, so in a way the mosquito is helping the virus, does it count as a role? At the same time viruses are neither living nor dead so do they really need a place to "live", also if the mosquitoes suddenly vanish can the virus "live" somewhere else, is there any problem here?

[Assistant]
Mosquitoes are very important.

Mosquitoes actually play a role in pollination of many plants.  As well mosquito larva are an important food source for many fish, frogs, and so forth.. and adult mosquitoes are important food sources for birds, bats, dragonflies, and many other animals.

Mosquitoes are insects by the way.

I suppose some total parasites might not have beneficial roles.. unless you consider that they help keep population levels slightly lower.. such as the fact that some animals are weakened by parasites and die.


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

[User] [DC/Warhammer 40K] I've just found a motherbox and have been deemed worthy to use it. What do I do? Should I report it to a Tech Priest? Try to use it? Is it Tech Heresy?

[Assistant]
Let's forego the obvious observation that, as an average Imperial citizen, you'd be a hiveworlder indentured to a manufactorum and worked half to death, with next to no knowledge of how the wider Imperium works and your possibilities within it, because that's boring. Let's assume you're someone with substantial knowledge but not too much starting power, like minor hive nobility.

Let's also say the MotherBox imparts on you thorough knowledge of its powers and enough of them (initially at least) to be protected from most physical and mental assault. Since you're educated hive nobility, you know that's not enough; not unless you've willing to sacrifice everything and everyone in your life. Your personal and dynastic rivals would be more than willing to hold your entire family hostage to get you to play ball. The Inquisition would be happy to throw them into forms of torture not even the MotherBox can properly imagine, if they think it'll be leverage on you. The Imperium as a baseline is a society that spares no cruelty.

So, assuming you don't want to become some outcast star god hunted down by anyone brave and foolish enough to think they can take what you have, I'd say your best bet is to lay very low, and use your newfound powers to plan ahead very carefully. Gather information, hide your tracks, try to find out if there's anyone in a position of high power that can also be trusted not to screw you over, and go to them.

At the moment, in the Era Indomitus, your best overall bet would be to try to reach Guilliman. The guy may be willing to order the death of trillions, but he's not actively malicious. If you go to him, reveal your power, and submit to whatever tests he'll doubtlessly impose to earn his trust, you can probably become a highly placed agent, with you family/friends/allies being granted the highest level of protection as part of the package.


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

[User] ELI5: How come the super moon appears bigger like in some pictures but it looks like it barely changed size where I am?

[Assistant] The super moon is only 14% wider (diameter) than a regular full moon. With the human eye, it's difficult to tell that difference because the moon itself appears quite small to us. However, with a high zoom lens on a camera, it is possible to take pictures where the moon appears bigger. The super moon is also 30% brighter, making it easier to take these photographs.


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

[User]
If I wanted to travel to the Sun, at which direction do I point my thrusters?

**In a ship that are in earths orbit around the sun.**
I figure we already have momentum, so if I pointed the thrusters in the opposite direction of my momentum. Then I would decrease my speed around the sun and gravity should pull me in.
^(I think)

Or is it just as simple as pointing my engines away from the sun and head inwards? Like walking on one of the arms of a carousel towards the center.

[Assistant]
Too many wrong answers here.

If you accelerate against your motion, you'll need about 30 km/s relative to the Earth (as this is Earth's orbital velocity). You are in Earth's orbit, you need sqrt(30^(2)+11^(2))=32 km/s there to escape from Earth where 11 km/s is the escape velocity of Earth, but you also have ~7 km/s from the orbit, assuming a low Earth orbit (LEO) with suitable orientation. Total: ~25 km/s. With an efficient chemical rocket (400s I_sp) that needs a mass fraction of about 500. To get 100 kg towards the Sun you need 50 tonnes in LEO. That is the fastest (2-3 months) somewhat feasible way to reach the Sun but also the most inefficient one. It is similar to a Hohmann transfer.

If you accelerate with the motion of Earth until your orbit goes very far away from the Sun, you need about 21 km/s relative to the Earth. Close to Earth this needs 23.7 km/s, you have 7 km/s already => 16.7 km/s needed. Once you are very far away from the Sun, you can make a tiny burn to reduce your tangential velocity to zero, and from there you fall down to the Sun directly. Can take decades, but it is much more fuel-efficient. To get 100 kg to the Sun you only need 6.5 tonnes in LEO.

What a spacecraft would actually do is a gravity assist at Jupiter. Accelerate by 6.5 km/s to escape Earth at a speed of sqrt((7+6.5)^(2)-11^(2))=8 km/s, enough to reach Jupiter when timed properly. There, make a fly-by that reduces your tangential velocity to zero and gives you a bit of velocity towards the Sun already, then fall down towards the Sun. Takes a few years, but only 6.5 km/s and a few course correction maneuvers. To get 100 kg to the Sun you only need 500 kg in LEO. This is both more fuel-efficient and faster than the previous method. You can reduce the fuel requirements further if you add a gravity assist at Mars or Venus, but then you get quite limited in the possible launch times. With Jupiter alone such a mission is possible roughly once per year.

If you have impossibly strong magical thrusters, you can accelerate directly towards the Sun and hit it. But then you have to be so fast that Earth's orbital velocity simply does not matter. You would need speeds in excess of 1000 km/s to do that properly. With a ridiculously strong but not completely magical thruster you can also accelerate a bit backwards and then inwards to speed this up.


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

[User]
[Buffy the Vampire Slayer] Why doesn't Sunnydale descend into a mass orgy or chaos whenever Buffy is away?

She was gone the summer break betweem season 1 and 2 as well as the break between seaskn 2 and 3 though the Scoobies were there to help. Then again, how much help were they when they had difficulties fighting 1 vampire? after she died following season 5, the robot Buffy kept up the facade of a Slayer in town.

Edit- should read "mass orgy of chaos"

[Assistant]
The Slayer doesn't actually do much to protect people, most of the time.

Sure, she saves people every night, but that's a tiny fraction of the people taken by the massive population of vampires and other ghoulies that call Sunnydale home.

And then there are the other Hellmouths, like the one in Chicago. They don't have a slayer at all, but they get along just fine. Well, for certain definitions of the term.

The Watchers intentionally limited the power of the Slayers because they were afraid of them, and wanted someone the could control. The *Slayers*, multiple, could have put a serious damper on supernatural violence, if not ended it outright, but the Watchers decided that millions of lives over the course of centuries was a price worth paying, if it meant they could keep their power.

While Giles and Buffy believe that the nightly patrols are making a difference, they are really just a tool to train the Slayer and keep her sharp. What the Slayer is *really* for is stopping the apocalyptic events that tend to happen in their vicinity. The Master arising, the Hellmouth opening, the First Evil waking up hung over and hangry. *That* is why there's a slayer, and fate has a way of making sure that the Slayer is in the right place at the right time to keep the world from tipping completely into darkness.


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

[User]
Why don't mRNA vaccines require an adjuvant?

Most other vaccine types, especially the inactivated virus/bacteria or subunit vaccines require the co-administration of an adjuvant to elicit a good immune response leading to immunity. Vector vaccines, to my knowledge, also contain an "adjuvant" in the form of the actual virus used to deliver the DNA to cells. mRNA vaccines do not seem to require an adjuvant, and in fact the most successful mRNA vaccines have modifications on the RNA portion to *reduce* immunogenicity. Why is this? Do the RNA and lipids used in the vaccine have properties that somehow allow the immune system to decisively react to them, or their translation products, as "foreign" antigens?

ETA: I understand how general immunology and innate immunity works (I have been an MSc. structural biologist for ~10 years) with regards to MHC and TLR pathways, but I don't understand the molecular mechanism of *why* our immune systems seem to respond so effectively to 'intercellular' pathogens (eg. extracellularly expressed antigen subunits) as opposed to 'intracellular' antigens like protein/ protein subunits from vaccines without an adjuvant (although we do not seem to have this 'problem' during natural bacterial or fungal infections, presumably due to the abundance of immunogenic molecules present in bacterial cell membrane lipids etc)

[Assistant]
RNA itself has an adjuvant effect. Biontech mentions it in their presentation.

It makes sense for the body to defend itself against foreign RNA, before they express any foreign proteins.

There are so-called RNA sensors which are tightly regulated to prevent sensing of self-RNA.

Toll-like receptors can sense RNA, there are also pattern recognition receptors in the cytosol.


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

[User]
Is there a language-agnostic way to learn how to write multi-threaded programs?

Is there a language-agnostic way to learn how to write multi-threaded programs?

That is, without consulting each language, library etc. separately?

[Assistant]
Not really, but there are only a few different ways to do concurrency, so a lot of your knowledge transfers:

 - The threads/locks/semaphores model.
 - The actor model.
 - Promises/futures/tasks model.


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

[User] ELI5: When NASA made the first space suits, how did they know what space would be like? I.e., how did they know what to put on the suits?

[Assistant]
It was theorized to be a vacuum hundreds of years before we went to space. We can also produce vacuum chambers here on earth to design and test such a suit.

Keep in mind weve been making pressurized suits for several decades before space flight including for deep sea diving.


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

[User] [Willy Wonka] Did health inspectors all got killed inside Willy Wonka's factory?

[Assistant]
They always come back from Wonkas factory. Always.

Some of them come back quieter than they were before. Some of them come back looking very different. Some of them come back in a state which leaves their families and friends wishing they had not.

None of them come back unchanged by the experience.

But they always come back.


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

[User]
[DC Comics] Where was Superman during 9/11?

Did 9/11 happen in the DC Comics Universe? If so, what was Superman doing during that time? Was he asleep? Was he off-world?

Superman could have flown to New York the moment the first impact happened in order to rescue survivors from the burning building. He would have seen the second plane coming from a mile away with his X-Ray supervision, caught it, and set it down safely in a nearby field, thus rescuing everyone on board while taking the terrorists into custody.

While Superman rescued civilians from the inferno, Aquaman and/or Mera could have sent a giant torrent of water from the Hudson to douse the flames, thus preventing the building from ever collapsing. The Flash would then go up and down the stairs at lightspeed, emptying the building of its remaining inhabitants in a matter of moments (similar to Quicksilver's moment in X-Men Apocalypse) as Superman flew over to stop the third plane from crashing into the Pentagon and to lend a hand to the passengers of United 93. At the end of the day, 9/11 would have only claimed the lives of the people in the first plane and its impact zone.

So where was Superman? We all know that with great power comes great responsibility. How could he stand by idly as humans suffered?

[Assistant] The DC Universe operates on a sliding timescale, that roughly boils down to "Superman made his first public appearance about a decade ago, and that ushered in the modern age of heroism." This means that 9/11 happened before Superman was around.


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

[User] What is a double prion?

[Assistant] Prions are proteins that re-fold into a three dimensional form in which that protein is harmful to health. Alzheimers disease may be caused by two proteins that together cause the disease. Hence a double prion disease.  Amyloid beta and tau are both prions that are implicated in Alzheimers.


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

[User]
ELI5: Patent Trolls

For some reason this isn't clicking with me, who's the good guy and who's the bad guy in a situation like this? is there even a good and bad guy? The picture that keeps coming to mind is that guy who has that really general patent on console controllers.

[Assistant]
First off there never is a bad guy or a good guy only people. And in this case people abusing a legal system, and people getting screwed over by the former.

So a patent is a contract between a person/company and society. You keep inventing cool stuff and we promise not to copy you unfairly without paying you.

This is essential in the pharmaceutical industry where a new drug will take years and millions even possibly BILLIONS of dollars to make.

So a company Pfizer invents a new drug, now for a period of time (seven years / ten years?) only they can make sell that drug. During that time they have to make back the money that they spent on inventing the drug. After that time anyone can make that drug without paying Pfizer, so the price of drugs suddenly goes down.

So patent laws are good to make sure that companies have incentive to make new cool stuff. And patent wearing off is also important so eventually everyone can afford these new cool stuff that was invented. If patent laws were too strong and never wore off, then Pfizer could make one drug and sell it for a very high price and make loads of money and not bother to ever make any other drugs.

Now a patent troll is someone who buys a company that owns a patent that may be too broad or badly worded. E.g. if someone in the early fifties patented the idea of two computers communicating with each other (it doesn't matter the type of computer or what language they computers are using two computers talking to each other), at the time it seemed reasonable it was a new and innovative idea and the inventor needs credit for it, but some ends up with this patent and that company goes out of business and a patent troll buys that company.

Now the patent troll can sue basically anyone who invents pretty much any piece of software. They won't sue someone who is playing in their basement because they won't get money out of them, and they won't sue Sony or Microsoft because they won't win the court case. But they will sue start up companies and small businesses, the real innovators of the industry.

This is especially bad in the software industry because:

A) It is changing so fast that something innovative today is standard practice next year.

B) Patent lawyers know the law and don't know much about computers and software and programming languages.

C) Often a general process gets a patent like "computers talking to each other" or "a device that controls a computer" instead of the specific software and hardware that has actually been invented.

D) More than 50% of patents are software patents.

Patent law is essential for some industries, but it only stagnates and prevents innovation in the computer industry. And that it is why it should be reformed or abolished.


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

[User] [Star Wars] Were the clones aware that order 66 was going to be executed at some point, or was it programmed within their development from the start?

[Assistant]
In older Legends material, they knew from the start.

This changed with *The Clone Wars* CGI series, which added a control chip in their brains, and showed that the order was more of a Manchurian Candidate style command that they did not know about which the chips would enforce.

The Clone Wars is both Legends and Canon (though the currently-airing season is Canon-exclusive), and by the canon tier rules of Legends, newer material and material from The Clone Wars supercedes older material from books, games, and comics.


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

[User]
Where is the next largest mountain range being/going to be created?

Throughout random readings Ive found that the Appalachians used to be larger than the Himalayas. Are there any new ranges currently forming and will any range formed ever be as large as the Appalachians considering tectonic plate movement is gradually slowing?

[Assistant]
The Himalaya are still forming as the Indian subcontinent continues to move north in collision with the Eurasian plate.

There is (relatively recently initiated) subduction in Southeast Asia as well, as part of the same collision currently building the Himalayas.


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

[User]
Why do people only have 10 seconds of useful consciousness at high altitudes when most can hold their breath for at least 30 seconds?

On average people are able to hold their breath for 30 seconds, but in the event of rapid decompression at high altitudes (40,000ft) they will become useless after just a few seconds.

Why is this?

[Assistant]
That's only at like 45000-50000 ft where the air pressure is close to 2-3 psi. You can't hold your breath because your lungs and throat and such can't deal with the 12-13 psi difference. Time of useful conciousness decreases the higher you go. Around 15000 ft it's like 30 minutes.

Add on that since the concentration of O2 in your blood which was about even with that in the air in a pressurized cabin, or on supplimental oxygen is now greater than that in the low pressure air and breathing is actually removing O2 from the blood in your lungs, not adding it.


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

[User]
ELI5: why cant we just plant a huge amount of trees instead of trying to stop CO2 emissions?

It seems to me that most of our governments and environmentalists are focusing on peoples and companies reduction of CO2 emissions when discussing how to deal with climate change. This requires a lot of social pressure and peoples sacrifice. So I always wondered if we couldnt just plant a whole bunch of trees and other plants to solve the problem? I dont think anyone would oppose that.

[Assistant]
Trees can help to offset CO2 emissions, but theyre not free to grow  they require the correct soil and a lot of clean water.

You can grow trees where theyre not entirely meant to be growing, sure, but then you have something like Southern California that burns down if someone looks at it incorrectly.

Its also important to note that you cant cut down an existing forest and then just plant a bunch of trees to quickfix the fuckup  forests are highly complex ecosystems from root to canopy and Chet from Toledo planting 3000 of the same species of spruce tree where there used to be a thriving forest isnt going to fix anything.


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

[User]
ELI5: Why are older Cubans so set against opening up of diplomatic relations between the US and Cuba?

Surely this improves everyone's lot and actually has a more positive effect on the attitudes in the communist society of Cuba?

Is it just political sentiments or are there serious negative implications for older Cubans? Why are they so determined to make things difficult for US politicians?

[Assistant]
They got run out of their home country by the current governemnt.

Cuba and it's government stand to gain a LOT more than the US from normalizing relations and opening up trade.

They want this oppressive government to fail so that they can have an opportunity to reclaim their country.

There is probably a lot of lingering resentment over murdered/imprisoned family members too.

That's the very rough and incomplete description of their possition.